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JP3618937B2 - Optical element molding method and precision element molding method - Google Patents

Optical element molding method and precision element molding method Download PDF

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Publication number
JP3618937B2
JP3618937B2 JP31514096A JP31514096A JP3618937B2 JP 3618937 B2 JP3618937 B2 JP 3618937B2 JP 31514096 A JP31514096 A JP 31514096A JP 31514096 A JP31514096 A JP 31514096A JP 3618937 B2 JP3618937 B2 JP 3618937B2
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Prior art keywords
molding
shape
mold
temperature
molding surface
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JPH10158019A (en
Inventor
勇 執行
昌之 冨田
瑞和 余語
裕之 久保
潔 山本
正樹 大森
直 宮崎
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Canon Inc
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Canon Inc
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B40/00—Preventing adhesion between glass and glass or between glass and the means used to shape it, hold it or support it
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
    • C03B11/06—Construction of plunger or mould
    • C03B11/08—Construction of plunger or mould for making solid articles, e.g. lenses
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B40/00—Preventing adhesion between glass and glass or between glass and the means used to shape it, hold it or support it
    • C03B40/04—Preventing adhesion between glass and glass or between glass and the means used to shape it, hold it or support it using gas
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B7/00—Distributors for the molten glass; Means for taking-off charges of molten glass; Producing the gob, e.g. controlling the gob shape, weight or delivery tact
    • C03B7/10—Cutting-off or severing the glass flow with the aid of knives or scissors or non-contacting cutting means, e.g. a gas jet; Construction of the blades used
    • C03B7/12—Cutting-off or severing a free-hanging glass stream, e.g. by the combination of gravity and surface tension forces
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2215/00—Press-moulding glass
    • C03B2215/63—Pressing between porous dies supplied with gas, i.e. contactless pressing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
    • Y02P40/57—Improving the yield, e-g- reduction of reject rates

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Description

【０００１】
【発明の属する利用分野】
本発明は、例えば、カメラやビデオカメラに用いられるレンズ等の高精度な光学素子を熱間加工で成形するための光学素子の成形方法及び光学素子及び光学素子成形用素材の製造方法及び精密素子の成形方法及び精密素子に関するものである。
【０００２】
【従来の技術】
近年、研削・研磨による精密光学素子の加工方法に代わり、加熱軟化させたガラス等の成形素材を、成形型を用いて直接プレス成形する方法が注目されている。
通常、この種の成形には、胴型とその胴型内で摺動する上下型よりなる成形用型部材を用いて、加熱軟化状態にある成形素材をプレスし、型部材の成形面に対応した光学機能面を成形素材に転写し、その後冷却を行い、型部材から精密光学素子を取り出す方法が用いられている。
【０００３】
また、特公昭４８−２２９７７号や特開昭５９−１９５５４１号には、多孔質材や超音波振動を用いて型表面にガス膜を作り、その膜を介して型と成形素材である軟化ガラスを非接触の状態でレンズ等に成形する技術が開示されている。
【０００４】
【発明が解決しようとする課題】
しかしながら、前記の成形型の成形面を成形素材に接触させて形状を転写させ精密光学素子を得るような従来例では、加熱された型と成形素材が直接に接触するために、成形素材と型との間に融着が発生したり、また成形時の型と成形素材の温度差により成形素材が不均一な熱収縮を起こすことに起因する、面の転写不良が発生したりする等の問題があった。特に成形素材がガラスである場合には、成形温度が高いためこの様な問題が顕著となり、成形温度を上げて成形時間の短縮を図ることや、高温の溶融ガラスから直接に精密光学素子を成形することは非常に困難であった。また更に、成形素材であるガラスと成形型の接触によりガラスと型材が反応したり、型の表面の磨耗等により型が劣化したりするため、使用できる成形型の材料も限定され、成形できるガラスの種類もごく限られたものとなってしまうという問題があった。
【０００５】
上記のような問題を避けるために、前述の特公昭４８−２２９７７号や特開昭５９−１９５５４１号には型と成形素材であるガラスを接触させないで成形する技術が開示されている。このようにガラスと型とを非接触の状態で成形する事は理想的であり、融着防止や成形品の表面状態に対しては効果がある。しかしながら、軟化状態にある高温の成形素材を非接触で成形すると、成形後の冷却期間の間に成形素材が型とは無関係に自由収縮するため、成形時の形状と冷却完了時の形状が異なってしまう。特に、成形品の肉厚形状が一定でなかったり、成形品への冷却が不均一であったりすると、冷却中に成形品の内部に温度分布が発生して冷却中の熱収縮が均等に起こらず、収縮が温度の比較的高い部分に集中するため、冷却後にその部分がくぼんだ状態に変形してしまう。これは、いわゆるヒケと呼ばれるものであり、このようなヒケが生ずると、完成した光学素子の形状が本来の目的とする形状と大きくかけ離れてしまう。特に成形素材がガラスの場合では、成形可能な温度域であるガラス転移点温度以上では熱膨張率が極端に大きく、成形が終了して成形時の温度からガラス転移点温度まで冷却する間にガラスが大きく収縮し、且つこの収縮変形を制御することが容易でないため、高精度の製品を作り出すのは非常に困難であるという問題があった。この問題は、成形素材と型とを接触させる前述の方法でも同様に発生する問題でもあった。
【０００６】
また更に、成形素材と型を接触させて成形するか否かに拘わらず、型と成形素材の熱膨張率の違いがあると、温度変化により型と成形品との寸法形状に微妙な差が発生する。この現象は成形型を用いた温度変化を伴う成形方法では不可避のものであり、一旦成形素材に転写した型の形状が、温度の変化、特に冷却による温度の変化により、型の形状とずれてしまうことを意味する。
【０００７】
成形素材と型を接触させて成形する方式では、冷却時に成形素材と型が中途半端に接触していると、成形素材と型が部分的な剥離を起し、形状の転写性に問題を起こす。これを防ぐため、成形品が自重で変形を起こさない温度近くまで型に圧力をかけておき、成形品と型の剥離を防ぐ方法や、単に高温で型と成形素材との間に発生する密着力を利用して、成形品が変形を起こしにくい温度付近まで成形品と型を密着させておく方法がとられている。
【０００８】
しかし、この様な方法のうち、型に圧力を加える方法では、最終的に形状を転写させる温度、即ち冷却が進んでいったときに圧力を解除する温度を厳密に管理できる利点はあるが、成形品に無理な力をかけることになり、成形品の割れや型の損傷を引き起こすという問題があった。また、形状によっては対応しきれないという問題もあった。また、密着力に頼る方法も、型と成形品の密着力を左右する微妙な界面状態を厳密に管理することが実質上不可能であるため、型と成形品の離型する温度が不安定となり、形状の転写性が安定しなかったり、上記の圧力をかける方法と同様に成形品に割れ等の欠陥を引き起こすという問題があった。さらに、成形素材と型を接触させないで成形する方法の場合にも、成形素材が型と接触していないため温度変化のどの時点で型の形状が成形素材に転写されるかが不安定で成形品の形状が安定せず、高精度な形状を転写させることはほとんど不可能であるという問題があった。
【０００９】
また、型に供給される成形素材の表面に切断痕等の欠陥があると、成形を非接触の状態で行っても、成形された成形品に欠陥が残り、その部分を再度研削研磨したりして削除する必要が生じ、本来の目的を達成できないという根本的な問題があり、上記の従来例では、この点に関する技術的な開示はされていない。
また、光学素子の成形法に於いて重要な条件の一つとして、型とガラスの融着を防止することがあげられる。言い換えれば型とガラスの離型性を良くすることが必要である。このことを主たる目的として従来から、型材料やガラス材料に関していろいろな提案がされている。いくつかの例を挙げるならば、特開昭４９−５１１１２号には１３Ｃｒマルテンサイト鋼が、特開昭５２−４５６１３号にはＳｉＣ及びＳｉ３Ｎ４が、特開昭６０−２４６２３０号には超硬合金に貴金属をコーティングした材料が提案されている。更に最近では特に離型性に優れていると考えられている炭素系材料として特開昭６１−１８３１３４号にはダイヤモンド薄膜が、特開平２−８０３３０号には水素化アモルファス炭素膜が提案されている。また特開昭６０−２１０５３４号には離型機能を有する薄膜を予めガラス素材にコーティングする成形方法が提案されている。
【００１０】
しかし１３Ｃｒマルテンサイト鋼は酸化しやすくさらに高温でＦｅがガラス中に拡散してガラスが着色される欠点を持つ。またＳｉＣ，Ｓｉ３Ｎ４は極めてガラスとの親和性が強いため融着が発生しやすい。貴金属をコーティングした型は極めて軟らかいためキズが付きやすい欠点を持つ。ダイヤモンド薄膜は光学的な鏡面性を得ることが困難である。水素化アモルファス炭素膜は上記のいずれよりも優れた離型性を持つ。問題点としては薄膜であるために強力な外力によって剥離する場合があることである。膜の剥離は、型とガラスの熱膨張率の違いに起因する熱応力によってプレス成形した後の冷却中に膜に対する剪断力が発生するために起こると考えられる。即ち型とガラスはプレス直後から冷却中は、強力に密着しているため熱応力によって膜が剥離するのである。そしてこの剥離現象は型の周辺部に於いて特に顕著である。その理由は型の周辺部が最も熱応力が大きく、また凸レンズの場合周辺部が肉薄であり中心部に比べて型とガラスが強く密着していると考えられるためである。少しでも膜が剥離するとその部分で型とガラスが融着したり成形品が割れたりするため型として使用することができなくなる。また離型機能を有する薄膜を予めガラス素材にコーティングすればプレス後の型とガラスの密着力を減少させることはできるが、特に凸レンズの周辺部分のように密着力が強くなる場所に於いて融着を防止する手段としては十分な物ではない。また薄膜をコーティングする工程がよけいに必要となる。
【００１１】
このように従来は、特に型の周辺部に於いて融着が発生したり、型の膜が剥離したりすることが問題であった。唯一の対策として周辺部の型材料にグラファイト等の離型性の良い材料を使えば融着は防止できるが、軟らかく消耗しやすく、また汚れの発生源になるため適当な材料ではない。
また、光学素子を成形する場合、軟化状態のガラス塊を成形型でプレス成形し、成形光学素子を得るが、良好な外観精度を有するガラス塊を、安価に製造する方法の開発が、最近進んでいる。
【００１２】
一方、所望の成形光学素子の形状に近い形状に、予め、成形用素材であるガラス塊の形状を成形する技術の開発も進んでいる。成形光学素子に近い形状に成形された成形用素材の利点は、プレス成形時の変形量が小さいため、プレス成形時間が短く済む点、および、成形型表面に成膜されている離型作用を有する薄膜を、プレス成形時にプレス変形に伴う剪断応力により破損することを防止できる点がある。
【００１３】
良好な外観精度を有するガラス塊を、安価に製造する方法として、以下に示す製造方法が具体的に知られている。
すなわち、流出口から流出している溶融ガラス流を、下方からガスが噴出している受け型の上に、受け型から浮上している状態で受け、溶融ガラス塊を得る方法である。このようにして得られたガラス塊は、上下面とも滑らかな自由表面からなっているので、表面粗さも非常に滑らかであり、良好な外観精度を有している。また、後加工を必要としないので、その製造コストも非常に安価なものである。
【００１４】
具体例として、ガス噴出孔の開いている受け型にガラス塊を得る例としては、特公平７−５１４４６号が知られている。また、多孔質の材料からなる受け型からガスが噴出している状態で、溶融ガラス流を受けガラス塊を得る例としては、古くは、特公昭４８−２２９７７号に既にその記載が見られ、最近では、特開平６−１２２５２６号、特開平６−１４４８４５号、特開平６−２０６７３０号等にその記載が見られる。
【００１５】
一方、成形用素材であるガラス塊をプレス成形して、所望の形状の成形ガラス塊を得る方法として、特開平４−３７６１４号が知られている。ここでは、受け型の上に受けたガラス塊を、受け型から取り出し、プレス成形用下型の上に置き、熱変形可能な温度までガラス塊を再加熱した後、このガラス塊を成形して、所望の形状の成形ガラス塊を得ている。
【００１６】
しかしながら、上記従来例である、ガラス塊を受け型から浮上した状態で受ける方法には、以下に示すような欠点があった。
すなわち、受け型から噴出しているガス流によって、受け型の上に受けられたガラス塊の下面が上方に持ち上げられた状態のまま固化してしまう。すなわち、得られたガラス塊の下面が凹んでしまうのである。
【００１７】
このように、下面が凹んでいるガラス塊を光学素子成形用素材として用いて、プレス成形して成形光学素子を得た場合、プレス成形機のチャンバーの内部に満たされている窒素ガスが、プレス成形時に、このガラス塊の下面の凹み部分に取り込まれた状態でプレス成形が行われ、その結果得られた成形光学素子の下面には、「ガス残り」と呼ばれる凹み部分が発生し、不良品となり、光学素子として使うことはできない。
【００１８】
このような、ガラス塊の下面の凹みを防止するためには、受け型から噴出しているガス流の流量を減らせば良い。しかし、噴出ガス流量を減らしすぎた場合、溶融ガラスと受け型が接触してしまう。このようなガラス塊は、多孔質の受け型の細孔の凸凹形状を転写しているので、外観が悪く、光学素子成形用素材として用いることはできない。
【００１９】
ガラス塊の下面の凹みを防止するもうひとつの方法として、受け型から噴出するガスとして高温のガスを用いる方法がある。すなわち、受け型から噴出しているガスの温度を高くし、かつ、噴出ガス流量を少なくすることにより、ガラス塊の下面の凹みを防止できる。しかし、この場合も、噴出ガス温度を高くしすぎた場合や噴出ガス流量を減らしすぎた場合、溶融ガラスと受け型が接触してしまう。
【００２０】
このように、従来から知られている、ガラス塊の下面の凹みを防止する方法は、しばしば溶融ガラスと受け型が接触することがあり、ガラス塊に接触痕が生じやすく、その最適な条件を設定することは困難であった。
一方、ガラス塊をプレス成形して所望の形状の成形ガラス塊を得る方法の従来例である、特開平４−３７６１４号には、以下に示す欠点があった。
【００２１】
すなわち、ガラス塊をプレス成形して所望の形状のガラス塊を得るに先立ち、このガラス塊を熱変形可能な温度まで再加熱するに際し、再加熱に非常に長い時間を要する点である。具体的に、特開平４−３７６１４号の実施例の記載によれば、５分乃至２０分の時間が、再加熱に必要となっている。
このように、再加熱に長時間を要する理由は、急激に加熱してガラス塊の温度が過昇温して、ガラス塊と成形用下型とが融着することを防止するために、再加熱の温度を低く抑えているためである。
【００２２】
また、ガラス光学素子のプレス成形に使用されるガラス素材には、既に述べたことと重複するが、形状、容量、表面粗さ等が要求される。
形状は図４１や図４２に示すように凹形状の型５４０の場合にはガラス素材５３９の曲率半径が大きく、凸形状の型５４２の場合にはガラス素材５４１の曲率半径が小さいとプレス変形時に型とガラスの間にガス残りが発生してしまう。従って、ガラス素材の形状としては中心部から順次型と接触変形してゆくように曲率半径を調整しなければならない（凹形状の型の場合：ガラス素材は凸でかつその曲率半径＜型の曲率半径、凸形状の型の場合：ガラス素材は凸あるいは凹の場合にはその曲率半径＞型の曲率半径）。
【００２３】
容量は型構造にもよるが大きいと図４３に示すようにはみ出し部が大きくなり、成形時の割れの原因になったり、後加工が必要になったりする。また小さいと図４４のようにレンズの有効径がとれなくなる。従って容量も所要の範囲に調整することが必要になる。
表面粗さはレンズとしては透過率等の関係上、Ｒｍａｘで０．０２μｍ以下であることが必要である。それを満たすには型の表面粗さがＲｍａｘで０．０２μｍ以下であることは当然であるがガラス素材としても０．０４μｍ以下であることが必要である。これ以上になるとプレスによっても表面粗さが０．０２μｍ以下にはならない。
【００２４】
これらの仕様を満たすガラス素材を作成するのに以下の方法が提案されている。
（ａ）特公平４−２０８５４号
ガラス素材を研削、研磨によりレンズ形状に近似の曲率形状にし、かつ表面粗さをＲｍａｘで０．０１μｍ以下にする。
（ｂ）特公平４−４３８５１号
ガラス素材を加熱軟化させ表面張力により球状にし、かつ表面粗さをＲｍａｘで０．０４μｍ以下にする。
（ｃ）特公平３−６０４３５号
溶融状態にあるガラスを一方の面は光学ガラス素子と近似形状の熱加工治具により成形しもう一方の面は表面張力により成形して精密成形用のガラス素材を得る。
【００２５】
また、多孔質部材を用いたものとしては以下のものがある。
（ｄ）特開昭６１−２６６３１７号
ガラス素材を多孔質部材を用いて加圧ガスを介して非接触状態で、加熱軟化、搬送する。
しかし、これらの方法には以下のような問題点がある。特公平４−２０８５４号の研削、研磨による方法ではこの後の洗浄工程も含めこれらの工程分コスト高になる。さらに、研磨によるヤケ、表面汚れ等の成形への悪影響があること、研削研磨によるガラス材料の無駄等の欠点もある。これに対して特公平４−４３８５１号のガラス材料を加熱軟化させ表面張力により球状化する方法では上記の問題点は解決されるものの、形状として球状しかできず凹レンズ成形用のガラス素材の作製が不可能である。また、凸レンズやメニスカスレンズの場合にも近似形状のガラス素材と比較して変形量が大きくなり、成形タクトが延びたり、型への負荷が大きくなったりするという欠点がある。特開平３−６０４３５号の溶融状態にあるガラスから素材を作製する方法では、研削研磨による方法での問題点は解決されるものの、一方の面の形状調整ができない。さらに、ガラス材料の種類により、粘度カーブの急なものや失透性の強いものは作製が困難である。
【００２６】
また、特開昭６１−２６６３１７号では、多孔質部材を用いて加熱、搬送を行っているがこの方法ではガラス素材は加熱前に形状調整を行っており、立方体や直方体をしたガラスブロックから上下面に任意の曲率半径を持ったレンズ形状への変形は不可能である。
以上のようにこれまで提案された方法では、研削研磨による方法ではコスト高となり、表面張力を利用した熱変形では形状の調整が不可能である。
【００２７】
従って、本発明は上述した課題に鑑みてなされたものであり、その目的は、溶融軟化状態にある成形素材から直接に高精度な形状及び面精度を有する光学素子等の精密素子を、研削研磨等の後加工なしで得ることが出来る精密素子の成形方法を提供することである。
また、本発明の他の目的は、型の周辺部における融着を防止したり型の膜剥離を防止することである。
【００２８】
また、本発明のさらに他の目的は、光学素子成形用素材として適した、下面に凹みのないガラス塊を、容易にかつ確実に製造する方法を提供することである。
また、本発明のさらに他の目的は、ガラス塊をプレス成形して所望の形状の成形ガラス塊を得る方法において、プレス成形に先立つ再加熱時間を短く、または、無くすことを可能にする、成形ガラス塊の製造方法を提供することである。
【００２９】
また、本発明のさらに他の目的は、所要の形状と容量を有したプレス成形用のガラス材料を安価に作製することである。
また、本発明のさらに他の目的は、成形時間が短く、かつ型耐久の向上が図れる成形方法を提供することである。
【００３１】
【課題を解決するための手段】
上述した課題を解決し、目的を達成するために、本発明に係わる精密素子の成形方法は、光学素子等の精密素子を溶融軟化状態の成形素材から直接に成形する方法において、少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が多孔質の材料から作られた型ユニットを準備する工程と、前記型ユニットを開き、多孔質の成形面からキャビティー内に流体を噴出させるとともに、溶融軟化された成形素材を供給するノズルから、溶融軟化状態の成形素材を成形面と非接触状態を保った状態で前記型ユニットに供給する工程と、成形素材の自重と表面張力により、前記ノズルから型ユニットの成形面上に供給された成形素材を、前記ノズルから分離する工程と、前記成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で前記型ユニットに圧力を加え、前記型ユニットを閉じ、前記成形素材を補正された成形面の状態にならわせ、補正された形状の成形品を得る工程と、成形素材を型ユニットに供給した後から、型ユニットに圧力を加え型ユニットを閉じ、成形素材を成形面の形状に倣わせる工程の間に、成形素材への第１の冷却開始し、さらに前記型ユニットを閉じ、成形素材を成形面の形状にならわせた後に第二の冷却を開始し、成形品が所望する最終形状になるまでの間に冷却を行い精密素子の形状を得る工程と、前記型ユニット内の精密素子の冷却完了後、型ユニットを開き精密素子を取り出す工程とを具備することを特徴としている。
【００３３】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、成形面より噴出させる流体の圧力、流量、温度、及び成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率をパラメーターとして含むシミュレーションにより得られることを特徴としている。
【００３４】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴としている。
【００３５】
また、この発明に係わる精密素子の成形方法において、前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴としている。
また、この発明に係わる精密素子の成形方法において、型ユニットに圧力を加え成形素材を加圧する際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力を制御することを特徴としている。
【００３６】
また、本発明に係わる精密素子の成形方法は、光学素子等の精密素子を成形する方法において、少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、少なくとも成形後に機能面となる部分に対応する部分の表面に、高低差が５μｍ以上の鋭角的な段差が存在しない様に仕上げられた成形素材を準備する工程と、前記型ユニットを開き、成形素材を型ユニットに供給すると共に、多孔質の成形面からキャビティー内に流体を噴出させ、成形素材を成形面と非接触状態を保った状態で加熱し、軟化させる工程と、成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、該予備成形品の表面近傍の粘度が１０7.6ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、補正された形状の精密素子の少なくとも表面近傍の粘度が１０8ｄＰａ・ｓ以上となったときに、成形面から流体の噴出を再開すると共に、精密素子と成形面との間に空隙を設ける工程と、成形素材を加熱、軟化した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始し、成形面からの流体の噴出を再開した直後から第３の冷却を開始し、成形品が所望する最終形状になるまでの間に冷却を行い、精密素子の形状を得る工程と、第２の冷却の際に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、型ユニット内の精密素子の冷却完了後、型ユニットを開き精密素子を取り出す工程とを具備することを特徴としている。
【００３７】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率の少なくとも１つをパラメーターとして含むシミュレーションにより得られることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴としている。
【００３８】
また、この発明に係わる精密素子の成形方法において、前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴としている。
【００３９】
また、この発明に係わる精密素子の成形方法において、型ユニットに圧力を加え非接触の状態で成形素材を加圧する際及び形状転写後の型内での冷却の際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力を制御することを特徴としている。
【００４０】
また、本発明に係わる精密素子の成形方法は、光学素子等の精密素子を溶融軟化状態の成形素材から直接に成形する方法において、少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、前記型ユニットを開き、多孔質の成形面からキャビティー内に流体を噴出させると共に、溶融軟化された成形素材を供給するノズルより、溶融軟化状態の成形素材を成形面と非接触状態を保った状態で型ユニットに供給する工程と、成形素材の自重と表面張力により、前記ノズルから型ユニットの成形面上に供給された成形素材を分離する工程と、成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、該予備成形品の表面近傍の粘度が１０７．６ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、成形素材をノズルから分離した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始する工程と、第２の冷却の際に、少なくとも、補正された形状の精密素子の表面と成形面との間に密着力が働いている間に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、少なくとも、素子の表面と成形面との間の密着力が解消するまでの冷却を行い、その後、型ユニットを開き所望の形状に近似した形状を有する成形素子を取り出す工程と、所望の形状に近似した形状の成形素子をさらに室温まで冷却し、所望の形状の精密素子を得る工程とを具備することを特徴としている。
【００４１】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率、及び成形素子の表面と成形面との間の密着力をパラメーターとして含むシミュレーションにより得られることを特徴としている。
【００４２】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴としている。
【００４３】
また、この発明に係わる精密素子の成形方法において、前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記第２の冷却の際の型部材の追従が、成形面と精密素子の間の密着力により行われることを特徴としている。
【００４４】
また、この発明に係わる精密素子の成形方法において、前記第２の冷却の際の型部材の追従が、型部材に圧力を加えることにより行われることを特徴としている。
【００４５】
また、本発明に係わる精密素子の成形方法は、光学素子等の精密素子を成形する方法において、少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、少なくとも成形後に機能面となる部分に対応する部分の表面に、高低差が５μｍ以上の鋭角的な段差が存在しない様に仕上げられた成形素材を準備する工程と、前記型ユニットを開き、成形素材を型ユニットに供給すると共に、多孔質の成形面からキャビティー内に流体を噴出させ、成形素材を成形面と非接触状態を保った状態で加熱し、軟化させる工程と、成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、該予備成形品の表面近傍の粘度が１０７．６ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、成形素材を加熱、軟化した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始する工程と、第２の冷却の際に、少なくとも、補正された形状の精密素子の表面と成形面との間に密着力が働いている間に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、少なくとも、素子の表面と成形面との間の密着力が解消するまでの冷却を行い、その後、型ユニットを開き所望の形状に近似した形状を有する成形素子を取り出す工程と、所望の形状に近似した形状の成形素子をさらに室温まで冷却し、所望の形状の精密素子を得る工程とを具備することを特徴としている。
【００４６】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率、及び成形素子の表面と成形面との間の密着力をパラメーターとして含むシミュレーションにより得られることを特徴としている。
【００４７】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴としている。
【００４８】
また、この発明に係わる精密素子の成形方法において、前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記第２の冷却の際の型部材の追従が、成形面と精密素子の間の密着力により行われることを特徴としている。
【００４９】
また、この発明に係わる精密素子の成形方法において、前記第２の冷却の際の型部材の追従が、型部材に圧力を加えることにより行われることを特徴としている。
【００５０】
また、本発明に係わる精密素子の成形方法は、光学素子等の精密素子を溶融軟化状態の成形素材から直接に成形する方法において、少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、前記型ユニットを開き、多孔質の成形面からキャビティー内に流体を噴出させると共に、溶融軟化された成形素材を供給するノズルより、溶融軟化状態の成形素材を成形面と非接触状態を保った状態で型ユニットに供給する工程と、成形素材の自重と表面張力により、前記ノズルから型ユニットの成形面上に供給された成形素材を前記ノズルから分離する工程と、成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、該予備成形品の表面近傍の粘度が１０７．６ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、補正された形状の精密素子の少なくとも表面近傍の粘度が１０８ｄＰａ・ｓ以上となったときに、成形面から流体の噴出を再開すると共に、精密素子と成形面との間に空隙を設ける工程と、成形素材をノズルから分離した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始し、成形面からの流体の噴出を再開した直後から第３の冷却を開始し、成形品が所望する最終形状になるまでの間に冷却を行い精密素子の形状を得る工程と、第２の冷却の際に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、型ユニット内の精密素子の冷却完了後、型ユニットを開き精密素子を取り出す工程とを具備することを特徴としている。
【００５１】
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率の少なくとも１つをパラメーターとして含むシミュレーションにより得られることを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴としている。
【００５２】
また、この発明に係わる精密素子の成形方法において、前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴としている。
また、この発明に係わる精密素子の成形方法において、前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴としている。
【００５３】
また、この発明に係わる精密素子の成形方法において、型ユニットに圧力を加え非接触の状態で成形素材を加圧する際及び形状転写後の型内での冷却の際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力を制御することを特徴としている。
【００５４】
また、本発明に係わる光学素子の成形方法は、重量調整されたガラス素材を成形用型でプレスして光学素子を成形する方法において、前記成形用型型が、光学素子の少なくとも光線有効径内を形成するための第１の型部材と、それ以外の部分を形成するための第２の型部材で構成され、第２の型部材の内部または表面を経由してガスを成形面に流しながら成形することを特徴としている。
【００５５】
また、この発明に係わる光学素子の成形方法において、プレス成形中に前記第２の型部材と成形された光学素子はガス層を介して非接触であることを特徴としている。
また、この発明に係わる光学素子の成形方法において、前記第２の型部材が多孔質セラミックまたは、多孔質金属または、多孔質炭素であることを特徴としている。
【００５６】
また、この発明に係わる光学素子の成形方法において、上型を構成する第２の型部材を経由するガスの温度と、下型を構成する第２の型部材を経由するガスの温度の差が１０℃以上であることを特徴としている。
【００６２】
【発明の実施の形態】
以下、本発明の好適な実施形態について、添付図面を参照して詳細に説明する。
（第１の実施形態）
図１は、第１の実施形態で用いられる成形装置の概略図である。図１において１は型ユニットであり、下型構成部材２と上型構成部材３とから概略構成されている。下型構成部材２と上型構成部材３は、それぞれ下型部材１１と、上型部材２１と、それらを保持する下型ホルダー１２と上型ホルダー２２とを備えている。なお、下型ホルダー１２と上型ホルダー２２には、流体を下型部材１１と上型部材２１にバランスよく供給分配するための圧力室１２ａ、２２ａが設けられている。また、ヒータ１３，２３と図示せぬ測温手段が埋め込まれていて、この側温手段の検出信号に基づいて、後述するコントローラ４１により下型部材１１及び上型部材１２の温度と流体の温度を最終的に調整することが出来るようになされている。また、１１ａ，２１ａは、それぞれ精密素子の形状を決定する下型部材１１と上型部材２１の成形面を示している。３１は流体の供給パイプであり、不図示の流体供給源から矢印Ａ部を介して供給された流体を圧力・流量調節器３２ａ，３２ｂヘ供給するようになされている。更に圧力・流量調節器３２ａ，３２ｂの先には、それぞれ流体の温度調整を行うための加熱ヒータ３３ａ，３３ｂが取り付けられている。また、下型構成部材２及び上型構成部材３には不図示の駆動装置がそれぞれ取り付けられており、下型構成部材２及び上型構成部材３は図に示す矢印Ｂａ，Ｂｂ方向（上下左右方向）にそれぞれ独立に移動できる様になされていると共に、下型部材１１及び上型部材２１のセンタを中心として、矢印Ｃａ，Ｃｂ方向に任意の回転数で回転出来るようになされている。下型構成部材２及び上型構成部材３と加熱ヒータ３３ａ，３３ｂの間は、耐熱性のあるフレキシブルチューブ３４ａ，３４ｂとロータリージョイント１４，２４によって接続されており、下型構成部材２と上型構成部材３の上下左右方向及び回転方向の動きを妨げない様になされている。また、４１はヒーター１３，２３の温度及び流体の流量、圧力、温度を制御するコントローラであり、信号線４４ａ，４４ｂによりヒーター１３，２３に接続されていると共に、信号線４２ａ，４２ｂ，４３ａ，４３ｂにより圧力・流量調節器３２ａ，３２ｂ及び加熱ヒータ３３ａ，３３ｂに接続されている。
【００６３】
図２は溶融軟化状態の成形素材を供給ノズルから吐出して型ユニット１に供給し、供給された成形素材をノズルから分離する工程を示す図である。図２において１０１は、溶融軟化状態の成形素材１０２を吐出する供給ノズルであり、１０２ｂは、下型部材１１の成形面１１ａの上に供給された分離前の成形素材塊を示し、１０２ｃは成形素材１０２と分離前の成形素材塊１０２ｂの間に作られるくびれ部を示す。１０２ａは成形面１１ａ上に得られた供給ノズル１０１から分離された後の成形素材塊を表わす。
【００６４】
図３は型ユニットの成形面の補正の方法を模式的に表したものである。図３において、２０１は、精密素子が最終的に必要とする形状を表す。２０２は、成形素材が加熱されて膨張した状態を示し、この状態で、型部材の成形面２０４の形状が流体の薄膜２０３を介して成形素材（精密素子）の表面に転写される。薄膜２０３を形成する流体は、成形面から噴出される。成形面２０４の形状は、精密素子の形状転写時に要求される形状２０２に流体の薄膜２０３の厚さを加えて曲率半径等が補正されている。２０５は、形状転写直後の高温の状態から成形素材を冷却するときに発生するヒケ等に起因する変形をキャンセルする補正量を示す。即ち、形状転写後精密素子が冷却されると、その中央部がヒケ等によりへこむので、これをキャンセルするために型部材の成形面は、２０６で示す様に２０４で示す形状に更に２０６で示す堀込みが加えられている。これにより、成形素材の表面は、高温で成形面の形状が転写されるときには、２０５で示す量だけ中央部が出っ張ることになるが、成形素材が冷却されるにつれて、この出っ張りがヒケにより引っ込んで行き、最終的に、必要とされる形状２０１に落ち着く。なお、成形面の形状２０４及び２０６は、成形素材に形状を転写する高温時に必要とされる形状であり、低温時においては、型部材の熱収縮により、２０７及び２０７ａで示すような形状となる。従って、型部材を製作するときには、２０７および２０７ａで示すような形状に成形面を加工しておく。
【００６５】
次に、上記の成形装置を使用して精密素子を成形する工程を、図を用いて具体的に説明する。なお、ここで成形される精密素子は、ビデオカメラに用いられるもので、光学有効面の曲率半径がＲ２０ｍｍとＲ３５ｍｍ、中心肉厚が３ｍｍ、外径Φ１４ｍｍの両凸の球面レンズである。成形素材には、温度が１３００℃の時に１０１．５ｄＰａ・ｓ、１２００℃の時の１０１．６ｄＰａ・ｓ、１１００℃の時に１０１．８ｄＰａ・ｓ、１０００℃の時に１０２．２ｄＰａ・ｓ、８９０℃の時に１０２．９ｄＰａ・ｓ、７２０℃の時に１０５ｄＰａ・ｓ、６１０℃の時に１０７．６ｄＰａ・ｓ、４９８℃の時に１０１３ｄＰａ・ｓの粘度となる粘性特性を有する光学ガラスを用いた。
【００６６】
また、下型部材１１の成形面１１ａと上型部材２１の成形面２１ａは、予め成形素材の形状転写時の形状及び冷却後の形状を流体の膜厚及びヒケ等の変形を考慮してシミュレーション計算を行い、最終的に精密素子に必要とされる形状が実現される様に補正を加えて加工されている。
具体的には、上型２１の成形面２１ａの場合、まず、図３に示すように、精密素子であるレンズの標準的な使用条件（例えば２０℃）における理論形状２０１（Ｒ３５ｍｍ）から、形状転写時の温度まで昇温したときの理論形状２０２がどのような形状になるかを算出する。即ち、成形時の形状転写時の温度を、このガラスが１０７．９ｄＰａ・ｓの粘度を示す温度である６００℃に設定し、理論形状２０１がどれだけ膨張するかを算出し、その値を理論形状２０１に加えて膨張時の理論形状２０２とする。次に、成形面２１ａと膨張時の理論形状２０２の間に介在する流体膜２０３の厚さが平均５μｍ前後となるような条件を、流体の流量、流体の粘度、ガラスの粘度、及び型ユニットに加えられる圧力等から算出する。そして、これらの条件で成形を行ったときの流体膜２０３の厚さ分布をあらためてシミュレーション計算し、この求められた流体膜２０３の膜厚分布を膨張時の理論形状２０２に加えて形状転写時の成形面の理論形状２０４を決定する。次に、形状転写後の冷却によるヒケ等の変形量を算出する。この計算では、形状転写温度から冷却していくときの刻々変化する流体及び型ユニットの温度、ガラスの保有熱、及び熱伝導率に基づいてガラスの温度分布を求め、その時々の熱収縮による応力とガラスの応力緩和計数等からヒケの量を算出する。このヒケの量を補正量２０５として成形面の理論形状２０４に重ね合わせ、形状転写時の成形面の部分的な補正形状２０６を決定する。さらに、成形面の材料の熱収縮による補正の量を算出し、形状転写温度の成形面の理論形状２０４とヒケによる補正の理論形状２０６とに重ね合わせて、冷間時の成形面の最終理論形状２０７，２０７ａを決定する。この最終理論形状に基づいて、上型部材２１の成形面２１ａを多孔質の穴部のくぼみを除いた面をＲｍａｘ０．３ミクロン以下となるような鏡面状態に加工した。また、下型部材１１の成形面１１ａも同様の手法で形状を求め加工した。また、型部材１１，２１の材料としては、気孔率が３０％で、最大穴径が８ミクロンである多孔質カーボンを用い、流体には型部材１１，２１の酸化を防ぐために窒素ガスを用いた。
【００６７】
次いで、このように加工準備した型部材１１，２１を図１に示す成形装置に取り付け、図２に示すような方法で軟化ガラス塊を得た。ここでこの行程を図２を用いてより具体的に説明する。
まず、図示せぬガラス溶融炉でガラス素材を溶融し、脱泡、均質化行程を経て、軟化状態の成形素材である均質な溶融ガラス１０２を得る。それをガラス溶融炉の末端に設けられている成形素材供給ノズル１０１へ導く。供給ノズル１０１を１２００℃の温度に設定し溶融ガラス１０２を流出させると共に、下型構成部材２を供給ノズル１０１の直下に移動させ、図２（ａ）に示すように成形面１１ａ上に所定の容量のガラスを受けた後、図２（ｂ）に示すように下型構成部材２を矢印Ｄのように下方へ少し下げ、供給ノズル１０１と切断前の成形素材塊であるガラス塊１２ｂの間にクビレ部１０２ｃを発生させる。この状態で、１０２ｃがガラスの自重と表面張力により分離にいたるまで待機し（図２（ｃ）の状態）、軟化状態の成形素材塊であるガラス塊１０２ａを得た。
【００６８】
このように１０２の分離工程において下型構成部材２を一旦停止させることにより、クビレ部１０２ｃの部分が冷やされることが少なくなり、自重と表面張力により自然に分離することが可能となる。そのため、分離部に成形素材が糸状に固化した切断痕や、破断痕が残らずに、１０２ａの表面には有害な欠陥が生じることがなくなる。また、この時の流体（窒素ガス）の温度は、ガラスを成形面１１ａに受ける時はガラスの転移点付近の温度である５００℃に、その直後には６００℃になるようにヒータ３３ａとヒータ１３の温度を調整する。また、窒素ガスの流量も溶融ガラス１０２を成形面１１ａに受ける直前までは毎分２０リッター、その後は毎分５リッターとなるように圧力・流量調節器３２ａで制御した。このようにすることで溶融ガラス１０２が成形面１１ａに達する前に１０２の先端が多少冷却されて固化し、窒素ガスの流量も増えるために、溶融ガラス１０２の先端が全く成形面１１ａに接触することがなく、また上記の分離方法を用いることとの相乗作用により、表面には全く欠陥がないガラス塊１０２ａが得られた。
【００６９】
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの成形面１１ａで受けている下面近傍の粘度が１０６〜１０７．５ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面１１ａと成形面２１ａから噴出する窒素ガスの流量を毎分２０リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂとヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が３．２ｍｍとなるまで毎秒５ｍｍの速度で型ユニット１を閉じた。次いで窒素ガスの温度と流量を６００℃と毎分１０リッターに設定し、冷間時のレンズの中心肉厚が３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が２０Ｋｇｆとなるように圧力を徐々に上げながら、且つ、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、レンズに成形面１１ａ，２１ａの形状を転写させた（第１の冷却終了）。
【００７０】
上記の形状転写の工程と、第１の冷却の工程に続き、第２の冷却を行った。これは窒素ガスの流量はそのままで、温度を１００℃に設定し、更に型ユニット１への加圧力を１０Ｋｇｆとなるように徐々に減圧しながら冷却を開始した。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５℃）となった時に型ユニットを開き、下型部材１１からは窒素ガスを噴出させたままの状態で、レンズを図示せぬ吸着ハンドで取り出した。更に成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１．５本、クセがニュートンリング１本以下に収まり、通常の使用には十分に耐えられる精度を得ることができた。
【００７１】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、全ての温度制御点において１０℃のばらつき範囲に収まり、また型ユニット１の開閉速度等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなり、冷却速度、特に第２の冷却速度が毎分２０℃より遅くなると自重変形や窒素ガスの圧力の影響を受けやすくなり、精度が劣化することが確認された。
【００７２】
（第２の実施形態）
次に第１の実施形態と同じ装置、同じ材料を用いて片面がＲ５０ｍｍ、もう一方の面がＲ４０ｍｍを基準とする非球面形状をなす、レンズの中心肉厚が４．３ｍｍ、直径がΦ２３ｍｍである、コンパクトカメラ用の両凸のガラス非球面レンズの成形を行った。
【００７３】
第１の実施形態と同様に、下型部材１１の成形面１１ａと上型部材２１の成形面２１ａは、成形前にシミュレーションにより求めた数々の補正を考慮した形状に加工し、その後更に実際に成形を行い、その形状データをもとに最終的な補正を行って形状を決定した。具体的には、第１の実施形態と同様に、上型２１の成形面２１ａの場合、図３に示すように、精密素子であるレンズの標準的な使用条件である２０℃における形状２０１（Ｒ４０ｍｍを基準とする非球面形状）に対し、成形時の形状転写時の温度を、６００℃に設定し、第１の補正の量の一部であるガラスの温度膨張による変形量を算出し、その結果から、この条件下における精密素子の形状２０２を求めた。更に、第２の補正の量である、その時の成形面と精密素子の間に介在する流体の膜厚分布を含む膜厚２０３が平均３ミクロン前後の厚さになるような条件を算出設定し、形状転写時の成形面の基本形状２０４を決定した。次に第３の補正の量に相当する、形状転写後の冷却によるヒケ等による補正量２０５を求め、形状転写時の成形面の部分的な形状２０６を決定し、更に第１の補正の量の残りの部分に相当する、型ユニットの成形面の材料の温度収縮による補正の量から、型の冷間時、特に型の成形面の形状を加工する時の成形面の形状２０７及び２０７ａ（図３において２０７と２０７ａのハッチング部分の形状）を求た。そして、その形状データにより、上型部材２１の成形面２１ａを多孔質の穴部のくぼみを除いた面を鏡面状態に加工し、一旦、シミュレーションで決定した成形条件で実際にレンズを成形した。次いで、この成形したレンズの形状を測定し、所定の形状と若干ずれている部分を再度補正加工して、出っ張りのない平滑な鏡面状態に仕上げ、最終的な成形面２１の形状とした。また、下型部材１１の成形面１１ａも同様の手法で形状を求め加工した。また、型部材１１、２１の材料として気孔率が２５％であり、最大穴径が６ミクロンである多孔質からなるＡｌＯ３を用い、流体にはクリーンなエアーを用いた。
【００７４】
次いで、このように加工準備した型部材１１、２１を図１に示す成形装置に取り付け、第１の実施形態と全く同様にしてガラス塊１０２ａを得た。
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの下型部材１１で受けている下面近傍の粘度が１０６〜１０７．５ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜１０６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面１１ａ，２１ａから噴出するエアーの流量を毎分２５リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が４．６ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで噴出エアーの温度と流量を６００℃と毎分１５リッターに設定し、冷間時のレンズの中心肉厚が４．３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が４５Ｋｇｆとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、レンズに成形面１１ａ，２１ａの形状を転写させた（第１の冷却終了）。
【００７５】
上記の形状転写の工程と、第１の冷却の工程に続き、第２の冷却を行った。これはエアーの流量はそのままで、温度を１５０℃に設定し、更に型ユニット１への加圧力を２０Ｋｇｆとなるように徐々に減圧しながら冷却を開始した。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５℃）となった時に、型ユニット１への加圧を解除すると共に流量を毎分７リッターにして冷却を続け、レンズ表面の温度が４９８℃（ガラス粘度１０１３ｄＰａ・ｓ）を下回った所で型ユニットを開き、レンズを取り出した。型ユニット１を開き、下型部材１１からはエアーを噴出させたままの状態で、レンズを図示せぬ吸着ハンドで取り出した。更にこの成形を数回繰り返し、またこの時の温度、加圧・減圧タイミングなどの再現性は５℃の温度範囲に、速度等のばらつきも３％以内に収まるように厳密に制御しながら成形を実施した。その後、完成した複数のレンズを２０℃の温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり第１の実施形態以上の良好な結果を得ることができた。
【００７６】
（第３の実施形態）
次に図４に示す型部材を第１の実施形態で用いた成形装置を用いて、直径がΦ１０ｍｍ、凸面の曲率半径がＲ２０ｍｍ、凹面の曲率半径がＲ３０ｍｍ、中心部の肉厚が３．３ｍｍ、周縁部の厚さが約３．１ｍｍである凸メニスカス形状のレンズを成形した。ここで、図４において、２１１、２２１はそれぞれ下型部材と上型部材であり、それらにはレンズの光学面を形成する成形面２１１ａと２２１ａが加工されている。更に、下型部材２１１と上型部材２２１の外周にはそれぞれレンズの周縁の下部と上部を形成する成形面２１６ａと２２６ａを有したリング部材２１６，２２６が取り付けられている。また、下型部材２１１と上型部材２２１は、気孔率が１５％で最大穴径が１５ミクロン、リング部材２１６，２２６は気孔率が１０％で最大穴径が２０ミクロンの多孔質の窒化珪素で作られていて、図示せぬ供給装置からそれぞれの圧力室１２ｂ，１２ｃ，２２ｂ，２２ｃに流体を個々に独立に供給することができるようになっており、それぞれの光学面の成形面と周縁部の成形面と成形素材の間の流体の膜厚を独立に制御出来るようになっている。また、成形素材は、第１の実施形態と同じガラス材料を用い、流体としては窒素ガスを用いた。
【００７７】
この実施形態では、レンズの光学面の成形面２１１ａ，２２１ａと周縁部の成形面２１６ａ，２２６ａの形状は、一旦レンズの冷間での形状を成形面上にそのまま加工して予備成形を行い、成形された光学素子の形状誤差を補正する様に成形面の補正加工量を求め、それを再度成形面の形状に反映して加工し直し、鏡面状態に仕上げた。また、予備成形における形状転写時の温度は６１０℃とし、窒素ガスの膜厚は光学面の部分で１０ミクロン、周縁部でおよそ２０ミクロンであるようにした。
【００７８】
次いで、このように準備した型部材２１１，２２１，２１６，２２６を第１の実施形態と同様に図１に示す成形装置に取り付け、同様の方法で軟化ガラス塊を得た。この時の窒素ガスの温度は、ガラスを成形面２１１ａに受ける時はガラスの転移点付近の温度である５００℃に、その直後にはガラスの粘度で１０７．３ｄＰａ・ｓに相当する温度である６２０℃になるように温度を調整し、更に窒素ガスの流量は、溶融ガラス１０２を成形面２１１ａに受ける直前までは、成形面２１１ａで毎分１８リッター、成形面２１６ａで毎分８リッター、その後はどちらも毎分５リッターとなるように制御した。
【００７９】
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの下型部材２１１で受けている下面近傍の粘度が１０５．６〜１０７ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜１０５．６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面２１１ａ，２２１ａから噴出する窒素ガスの流量を毎分２０リッター、成形面２１６ａ，２２６ａからの流量をそれぞれ毎分１４リッター、１２リッターとし、温度をガラスの粘度で１０５．８ｄＰａ・ｓに相当する６８０℃となるように設定し（第１の冷却開始）、更に下型構成部材２と上型構成部材３が互いに逆回転となるような回転方向で、回転数が２００ｒｐｍとなるように徐々に回転速度を上げながら、ガラス塊１０２ａの中心肉厚が３．５ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで、下型構成部材２と上型構成部材３の回転を保った状態で、窒素ガスの温度を６１０℃、成形面２１１ａ，２２１ａからの流量が毎分１５リッター、成形面２１６ａ，２２６ａからの流量がそれぞれ毎分１２リッター、１１リッターとなるように設定し、冷間時のレンズの中心肉厚が３．３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が２５Ｋｇｆとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、レンズに成形面２１１ａ，２２１ａの形状を転写させた（第１の冷却終了）。
【００８０】
なお、上記の成形の工程において、下型構成部材２と上型構成部材を互いに逆方向に回転させるのは以下のような理由による。即ち、多孔質材料の孔は完全に均一に開いていることはなく、微視的に見ると不均一であることが多く、そのため流体の流量、圧力の分布が不均一になりやすい。この圧力等の不均一は流体の膜厚の不均一につながり成形品の形状に影響を及ぼす。この影響を回避するために、型とガラス素材を相対的に回転させ、型とそれに対向する成形面をずらし、膜を均一にするものである。
【００８１】
上記の形状転写の工程と、第１の冷却の工程に続き、第２の冷却を行った。ここでは窒素ガスの流量と下型構成部材２と上型構成部材３の回転はそのままで、温度を１５０℃に設定し、更に型ユニット１への加圧力を１３Ｋｇｆとなるように徐々に減圧しながら冷却を開始した。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５℃）となった時に下型構成部材２と上型構成部材３の回転を停止すると同時に型ユニットを開き、下型部材２１１から窒素ガスを噴出させたままの状態で、レンズを図示せぬ吸着ハンドで取り出した。更に成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、十分な精度を得ることができた。
【００８２】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、全ての温度制御点において１０℃のばらつき範囲に収まり、型ユニットの開閉速度及び下型構成部材２と上型構成部材３の回転数等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなることが確認された。
【００８３】
（第４の実施形態）
次に第１の実施形態と全く同じものを、図５に示す様に予め重量調整されたガラス塊より成形した実施形態を述べる。なお、下型１１の成形面１１ａと上型２１の成形面２１ａは、第１の実施形態と全く同様にして形状を求め、加工したものを用いた。
【００８４】
まず、第１の実施形態で用いたと同じガラスのブロックから、ガラス塊を切り出し、それを更に研削研磨により容積で３１１ｍｍ３となるようなガラス塊に仕上げ、更に、このガラス塊の研削研磨面以外の部分に、バーナーによる火炎処理を行うことにより、ガラス塊の表面の５ミクロン以上の鋭角な段差を取り去り、滑らかな表面を有する容量が３１１ｍｍ３のガラス塊を得た。
【００８５】
次いで、このガラス塊を窒素ガスが毎分３０リッター噴出されている成形面１１ａの上に載置した後、ヒータ１３と加熱ヒータ３３ａにより、窒素ガスの温度をガラスの粘度で１０５．４ｄＰａ・ｓに相当する温度である７００℃に上げガラス塊を加熱した。この時上型構成部材３も下型構成部材２の真上に移動させ、同様の温度の窒素ガスを流し、ガラス塊を上部からも加熱した。このようにすることで、表面に有害な欠陥の全くない、粘度が１０６ｄＰａ・ｓの軟化ガラス塊１０２ａを得た。
【００８６】
次に、第１の実施形態と同様に、成形面１１ａ，２１ａから噴射する窒素ガスの流量を毎分２０リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し、ガラス塊１０２ａの中心肉厚が３．２ｍｍとなるまで毎秒５ｍｍの速度で型ユニット１を閉じた。次いで、第１の実施形態と全く同じ工程を経て、レンズを成形し、精度を測定したところ、第１の実施形態で得られた結果と同じ結果が得られ、また、レンズ表面にも有害な欠陥は全く見られなかった。
【００８７】
更に、最初に準備するガラス塊の表面処理の条件を多少振りながら成形を続けた結果、表面に残る段差が５ミクロンを越えたり、鋭角的な段差が残ったりすると、加熱軟化した後に、表面を更に滑らかにするための時間が非常にかかったり、場合によっては、この加熱軟化により段差が解消せず、成形後のレンズ表面に欠陥が残ったりし、実用上、大きな問題になることが確認された。
【００８８】
（第５の実施形態）
次に第３の実施形態と全く同じものを、図５に示す様に予め重量調整されたガラス塊より成形した実施形態を述べる。なお、下型２１１の成形面２１１ａと上型２２１の成形面２２１ａ及び成形面２２６ａは、第３の実施形態と全く同様にして形状を求め、加工したものを用いた。
【００８９】
まず、第１の実施形態で用いたと同じガラスブロックから、ガラス塊を切り出し、それを更に研削研磨により容積で２５０ｍｍ３となるようなガラス塊に仕上げ、更に、このガラス塊の研削研磨面以外の部分に、バーナーによる火炎処理を行うことにより、ガラス塊の表面の５ミクロン以上の鋭角な段差を取り去り、滑らかな表面を有する容量が２５０ｍｍ３のガラス塊を得た。
【００９０】
次いで、このガラス塊を窒素ガスが毎分２５リッター噴出されている成形面２１１ａの上に載置した後、窒素ガスの温度をガラスの粘度で１０５．４ｄＰａ・ｓに相当する温度である７００℃に上げガラス塊を加熱した。この時上型構成部材３も下型構成部材２の真上に移動させ、成形面２１６ａ，２２１ａ，２２６ａにも同様の温度の窒素ガスを流し、ガラス塊を上下、外周部からも加熱した。このようにすることで、表面に有害な欠陥の全くない、粘度が１０６ｄＰａ・ｓの軟化ガラス塊１０２ａを得た。
【００９１】
次に、第３の実施形態と同様に、成形面２１１ａ，２２１ａから噴射する窒素ガスの流量を毎分２０リッター、成形面２１６ａ，２２６ａからの流量をそれぞれ毎分１４リッター、１２リッターとし、温度をガラスの粘度で１０５．８ｄＰａ・ｓに相当する６８０℃となるように設定し、更に下型構成部材２と上型構成部材３が互いに逆回転となるような回転方向で、回転数が２００ｒｐｍとなるように徐々に回転速度を上げながら、１０２ａの中心肉厚が３．５ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。
【００９２】
次いで、第３の実施形態と全く同じように上型構成部材２と下型構成部材３の回転を保った状態で、窒素ガスの温度を６１０℃、成形面２１１ａ，２２１ａからの流量が毎分１５リッター、成形面２１６ａと２２６ａからの流量がそれぞれ毎分１２リッター、１１リッターとなるように設定し、冷間時のレンズの中心肉厚が３．３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が２５Ｋｇｆとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、レンズに成形面２１１ａ，２２１ａの形状を転写させた。その後１０１２ｄＰａ・ｓでレンズを取り出し、精度を測定したところ、第３の実施形態で得られた結果と同じ結果が得られ、また、レンズ表面にも有害な欠陥は全く見られず、また、加熱軟化前のガラス塊の表面の状態に対しても同様の結果が得られた。
【００９３】
次いで
以上第１乃至第５の実施形態をまとめると、第１の方法においては、第１の工程は、精密素子の成形形状転写時と精密素子の使用時や型ユニットの加工時の温度における精密素子と型ユニットとの熱膨張差による形状の相違量を含めた熱収縮量の補正や、成形および冷却時の不均一な熱分布に起因する精密素子のヒケの発生位置と量を前もって成形型で補正しておく事により、成形された精密素子が所望の形状を得られるようにすることであり、この際に成形面と精密素子の間に存在する流体の厚さも補正しておく。また、型ユニットの成形面を多孔質の材料で作り、その成形面から成形素材に向けてエアーやＮ２ガス等の流体を噴出させ、成形面表面にごく薄い流体膜を形成することで成形素材と成形面の接触を防ぐことが出来る。この目的のためには、多孔質の最大穴径が２０ミクロン以下、望ましくは１０ミクロン以下で気孔率が１０〜３５％の材料からなり、材料は対酸化性のあるアルミナや窒化珪素、炭化珪素等のセラミックや、多孔質カーボンからなり、更に成形面の表面は、流体膜が破れ、成形素材に傷を付けないようにするためにも、出っ張りの無い平滑な鏡面状に加工されていることが必要となる。
【００９４】
次に第２の工程により、型と成形素材の接触、特に溶融軟化された形状が不定の状態の成形素材をノズルから流出させ型に供給する時に発生しやすい成形素材と型との接触を防ぐことが出来、更にこの時に、一時的に噴出する流体の温度を下げたり流量を増やすことにより、接触を確実に防ぐことが出来る。また、型ユニットの成形面上に供給された成形素材を前記ノズルから分離する際に、型ユニット上に成形素材を必要量を受け止めた後、型ユニットを一旦下降させ、型ユニット上の成形素材とノズルより流出する成形素材との間にくびれを発生させ、更に成形素材の自重と表面張力によりくびれを発達させ分離を行うことにより、型ユニット上に、成形後に影響がでるような欠陥の全く無い、表面が非常に滑らかな成形素材塊を得ることが出来る。
【００９５】
次に第３の工程においても型の成形面から流体を噴出させながら型ユニットを閉じる事により、成形面と成形素材の接触を防ぐことが可能となり、前述の型と成形素材の接触による傷や接触による急冷による欠陥を防止することが可能となる。また、この時に型ユニットを閉じる速度、タイミング、圧力、および噴出させる流体の流量・圧力、温度等を確実に再現することにより、安定した形状の転写を得ることが出来る。型ユニットを、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度範囲の時に閉じ、型ユニットを閉じ終わった時の流体の膜厚が２０ミクロン以下、より高精度な素子を成形する場合は、５〜１０ミクロン、望ましくは、３ミクロン以下になるように流体の圧力と流量を制御し、又、同時に型を閉じる圧力および速度も流体の膜厚を前記の範囲内に収まるように成形素材の温度に逆比例させながら制御する事により成形素材を成形面の補正された形状にならわす。また、この型ユニットを閉じる時の動作は成形素材の温度に対応して制御されることが望ましく、各々の動作における温度のばらつきは１０℃以下、望ましくは５℃以下とし、同様に噴出させる流体の温度も同じ範囲に収めることが望ましく、流体の流量及び圧力のばらつき及び型ユニットを閉じる速度と圧力のばらつきは５％以内、望ましくは３％以内とすることにより、補正を施された型ユニットの成形面の形状の転写性をより安定して得ることが可能となる。
【００９６】
次の第４の工程での第１の冷却は、成形素材の粘度を制御し、型ユニットの成形面の補正された形状を正確に成形素材に転写させるために行われるものであり、第一の冷却の完了時に上記の流体の膜厚に成るように、成形素材の粘度を制御しながら徐々に冷却を行う。この第１の冷却完了時において成形素材と型ユニットの成形面が流体の膜を挟んで一致することにより、冷却完了後の精密素子の形状及び面精度が確保される。また、この第１の冷却完了時点では、成形素材や型ユニットや流体の温度等は上記の範囲内に収めておく必要がある。その後の第２の冷却は第１の冷却より早い速度で行なうことが出来、ここでの冷却は、一旦転写された補正形状が、冷却により補正前の形状、つまり精密素子の本来の所望する形状に一致し、更に連続成形において冷却収縮によりばらつきが生じないように行われるものである。そのためには、補正形状を決定した時の冷却開始温度や冷却時の温度分布等の諸条件を正確に再現する必要がある。この再現性は、上記と同様に冷却開始時から成形素材の粘度で１０１２ｄＰａ・ｓを示す温度の範囲での温度のばらつきとして１０℃以下、望ましくは５℃以下とすることにより安定した再現性が得られる。また、この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で補正形状を決定する時に定められるものであるが、転写した形状が自重や流体の圧力により変形を起こさないようにするためには、精密素子の表面を毎分２０℃以上の速度で冷却する必要があり、また、流体の圧力や流量にも急激な変化を与えないようにする必要がある。更にこの第２の冷却は、成形された精密素子が変形を発生させにくくなる粘度である１０１２ｄＰａ・ｓまで行われる。また、特に精密な転写性を要求されるものや、複雑な形状のものに対しては成形素材が歪を新たに発生させない粘度である１０１４．５ｄＰａ・ｓまで行うことにより、より精密な形状転写性が得られる。以上のような冷却を経ることで、この工程の終了時には型ユニットの成形面の形状と成形された精密素子の形状は膨張率の差の分の補正量や、予め見込んでおいてヒケに対する補正量のために完全に一致しないが、成形素材がほぼ固化しており、成形面と非接触状態にあるため、精密素子の形状は型ユニットの成形面の形状に左右されることなく、所望の形状を維持できる。
【００９７】
最後の第５の工程で、上記のようにすでに固化している精密素子を型ユニットを解放して取り出すことにより、所望の形状を転写された精密素子を得る。この時も精密素子と型ユニットの成形面との間には、流体による膜が介在しているようにすることにより、精密素子の表面に成形面との接触による傷などの発生を防ぐと同時に、成形面も固化した精密素子との接触による損傷を防ぐことが出来る。
【００９８】
また、第２の方法においては、第１の工程及び第４、第５、第６の工程は、上記の第１の方法の第１の工程及び第３、第４、第５の工程と同様である。
ここでは次の第２の工程は、精密素子の成形素材を準備する際に、成形後の精密素子に欠陥が発生しないように、成形素材の成形後に機能面となる部分に対応する部分の表面を、滑らかに仕上げる工程であり、その部分に相当する部分の表面を光学的な欠陥、つまり加圧成形することにより解消出来ない欠陥を予め取り除くことである。具体的には、表面を高低差が５ミクロン以上の鋭角的な段差が存在しないように仕上げることであり、傷や欠け等の微視的に見た時に鋭角的な部分が存在しないように処理する事である。この処理は、従来から行われている、研削研磨による方法や、酸処理などによる表面エッチングや、火炎や熱風による表面の軟化光揮処理等により行われる。
【００９９】
次の第３の行程を実施する事により、成形素材を型ユニットの成形面と非接触の状態で加熱軟化することが可能となるため、型ユニット上に、成形後に成形面に影響が出ることが無い、無欠陥の表面が非常に滑らかな状態の軟化した成形素材塊を得る事が出来る。この時、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度まで成形素材を加熱する事により、次の第４の工程につなげることが可能となる。その後の工程は前述のように第１の方法と同様であり、最終的に所望の形状の精密素子を得ることが出来る。
【０１００】
更に、第３の方法においては、成形面の予め補正された形状を、流体の圧力、流量、温度、及び成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と多孔質の材料で作られた型部材の熱膨張率等を成形条件のパラメーターとしてシミュレーションし、事前に成形される精密素子の形状を予測し、それを基に型ユニットの成形面の形状を補正しておく事により、高精度な形状及び面精度を有する精密素子を得ることができる。この補正は、型部材と成形素材の熱膨張差に伴う第１の補正と、型ユニットの成形面と成形素材との間に介在する流体の厚さをキャンセルするための第３の補正を組み合わせたものであり、成形型の成形面の形状加工時にこの補正を行うことで、成形が完了し型ユニットより取り出した精密素子の形状を所望の形状と一致させることが出来る。
【０１０１】
ここで第１の補正は、形状転写時と型部材の形状加工時や精密素子の使用時の温度差、及び型部材と成形素材の熱膨張率の違いから発生する、型部材の成形面と精密素子の形状のズレ量の補正であり、具体的には、所望の精密素子の使用温度での形状を形状転写温度までの温度差による精密素子の形状変化量を成形素材の膨張率で算出し、更にその精密素子の形状変化量を形状転写温度から型ユニットの成形面の加工時の温度差までの型部材の形状変化量として型部材の膨張率で算出した量を型部材成形面の形状の第１の補正の量とするものである。第２の補正は、型部材と成形素材との間に介在する流体の厚さ、特に形状転写時の流体の膜厚及び膜厚分布による形状の変化量を補正するもので、流体の流量や、温度とその時の粘度、成形素材の温度と粘度、及び型ユニットに加えられる圧力等から、流体の圧力分布及び膜厚とその分布状態を算出し、それを型部材の成形面の形状の第２の補正の量とする。第３の補正は、特に精密素子が形状を転写した後に、冷却され型から取り出されるまで、場合によっては、取り出し後も含めての冷却によるヒケ等による変形量の補正であり、主に冷却時に刻々と変化する流体や型ユニットの温度と成形素材の保有熱と温度伝導率に支配される、成形素材自体の温度分布とそれに伴うその時々の粘度分布と熱膨張率とそれらにより算出される応力と、成形素材独自の応力緩和係数によりヒケの量を算出し、更にその量に、その時々の成形素材の自重や流体の圧力変化等による形状の変化量を算出して加算したものを第３の補正の量とする。
【０１０２】
更に、第４の方法においては、予め所望する精密素子の最終形状に近似した形状を有する素子を成形し、その成形中及び成形終了後の成形、形状データから得られた情報を型部材の成形面の形状へフィードバックすることにより、高精度な形状及び面精度を有する光学素子等を得ることが出来る。この補正方法は、最初に精密素子の形状とほぼ同等の形状の成形面を有する型ユニットを用いて、予め設定し、固定された諸条件下で素子を一旦成形し、成形完了後の使用条件と同じ状態の素子の形状と、使用した型ユニットの成形面の形状を比較し、そこで判明した形状の相違量を、基本的には型ユニットの成形面への補正量として用い、成形条件の変更で補正出来るような単純な補正の場合は、成形条件をも修正することにより、成形した精密素子を所望の形状に一致させることが可能となる。また、この補正を数回繰り返すことにより、より精度のよい安定した形状を得ることも可能となり、更に前述のシミュレーションによる型ユニットの成形面の補正方法を組合わせて実施することで同様の効果を得ることが出来る。
【０１０３】
更に、第５の方法においては、成形面の多孔質部より噴出する流体の温度を制御する事により、成形素材の温度を制御することが出来る。これは、成形素材が型ユニットと非接触状態にある事や、成形素材が型ユニットに覆われており、外部から成形素材の温度を測定することが実質上不可能であるが、成形素材に直接に接触する流体の温度を制御し、その伝熱により成形素材の温度を間接的に制御することで解決され、また、こうする事により、成形素材に対して、より応答性の良い確実な温度制御を行なうことが出来る。ここで、流体の温度の制御方法としては、流体を供給源の近傍で直接に加熱温調して用いることでも十分に目的を達成することができるが、一旦前述の型ユニット等に組み込まれたヒーター等の加熱源により、再度温調をかけなおして用いることで、より良好な成形素材への温度制御を実現することが可能となる。
【０１０４】
更に、第６の方法においては、成形素材の粘度に合わせ成形型の成形面より噴出させる流体の噴出圧力と流体の流量と、型ユニットへの加圧力を制御することにより、高精度な形状及び面精度を有する光学素子を得ることができる。ここで、成形素材の硬さに相当する粘度変化に同調させて、流体の流量や圧力と型ユニットへの加圧力を制御する事により、型ユニットの成形面と成形素材の間の流体の膜厚を確実に安定させて制御することが出来、その結果、完成した精密素子が、より一層、高精度で、かつ連続成形時においてもばらつきの少ない安定した形状を得ることが可能となる。
【０１０５】
更に、第７の方法においては、型ユニットに圧力を加え成形素材を加圧する際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力分布を制御することにより、高精度な形状及び面精度を有する光学素子等を得ることができる。これは、加圧成形中に型部材を成形素材に対して回転摺動させる事により、成形素材と型部材の成形面との間の流体の膜厚を均一化することが容易となり、より高精度な精密素子を得る事ができるようになり、特に回転軸を中心とした軸対象に膜厚が容易に均一化することにより、レンズ等の機能面が軸対象の形状の球面を基本とする形状の精密素子に対しては大きな効果を発揮する事が可能となる。
【０１０６】
（第６の実施形態）
次に第１の実施形態と全く同じものを、図５に示す様に予め重量調整されたガラス塊より成形した他の実施形態を述べる。なお、下型１１の成形面１１ａと上型２１の成形面２１ａは、第１の実施形態と略同様にして、ただし、図３Ａに示すように、流体の膜厚を考慮せず、また、最終的な形状転写時の温度をガラス素材が１０９ｄＰａ・ｓの粘度を示す温度に設定し形状を求め、加工したものを用いた。
【０１０７】
まず、このように加工準備した型部材１１，２１を図１に示す成形装置に取り付け、さらに第１の実施形態で用いたと同じガラスのブロックから、ガラス塊を切り出し、それを図５（ａ）に示す様に更に研削研磨により容積で３１１ｍｍ３となるようなガラス塊に仕上げ、更に、このガラス塊の研削研磨面以外の部分に、バーナーによる火炎処理を行うことにより、ガラス塊の表面の５ミクロン以上の鋭角な段差を取り去り、図５（ｂ）に示すような滑らかな表面を有する容量が３１１ｍｍ３のガラス塊を得た。
【０１０８】
次いで、このガラス塊を窒素ガスが毎分３０リッター噴出されている成形面１１ａの上に載置した後、ヒータ１３と加熱ヒータ３３ａにより、窒素ガスの温度をガラスの粘度で１０５．４ｄＰａ・ｓに相当する温度である７００℃に上げガラス塊を加熱した。この時上型構成部材３も下型構成部材２の真上に移動させ、同様の温度の窒素ガスを流し、ガラス塊を上部からも加熱した。このようにすることで、表面に有害な欠陥の全くない、粘度が１０６ｄＰａ・ｓの軟化ガラス塊１０２ａを得た。
【０１０９】
次に、第１の実施形態と同様に、成形面１１ａ，２１ａから噴射する窒素ガスの流量を毎分２０リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が３．２ｍｍとなるまで毎秒５ｍｍの速度で型ユニット１を閉じた。次いで、窒素ガスの温度と流量をガスの膜厚が２０ミクロン程度となる様に、６１０°Ｃ（ガラスの粘度で１０７．６ｄＰａ・ｓに相当する温度）と毎分１０リッターに設定し、冷間時のレンズの中心肉厚が３．０５ｍｍに相当する位置になったときに、型ユニット１を閉じ、成形面への圧力が２ＭＰａとなる様に圧力を徐々に上げながら、同時に、レンズの表面近傍の粘度が１０７．６Ｐａ・ｓとなる様に速度を調整しながら型ユニット１を閉じ予備成形品を得た。
【０１１０】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に初期に１．５ＭＰａ、最終的に２ＭＰａの力が加わる様に徐々に圧力を上げて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
また、軟化ガラス塊１０２ａを得た直後から、予備成形品を得るまでの間に、成形素材への第１の冷却を開始し、予備成形品を得た直後から第２の冷却を開始した。第２の冷却は不図示の冷却装置により型ユニット１の外部より、冷却用の窒素ガスを吹きつけることにより行われ、その時において、型構成部材２，３への外部からの拘束を解き、下型部材１１及び上型部材２１がレンズの収縮に追従出来るようにした。
【０１１１】
また、第２の冷却開始後すぐに、レンズの表面近傍の粘度が１０８ｄＰａ・ｓとなった時点で、成形面１１ａ，２１ａから流体を１５ｋＰａの圧力で瞬間的に噴出させると同時に型ユニット１を僅かに開き、レンズを成形面から離型させ、その後直ちに流体の圧力を１．０２ｋＰａ、流量をそれぞれ毎分３リッターに設定し、第３の冷却を行った。
【０１１２】
第３の冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となったときに型ユニット１を完全に開き、下型部材１１からは窒素ガスを噴出させたままの状態で、レンズを不図示の吸着ハンドで取り出した。さらに成形の完了した複数のレンズを使用条件と同等の温度である２０°Ｃの温度下において精度を測定したが、全てアスがニュートンリング１．７本、クセがニュートンリング１本以下に収まり、通常の使用には十分耐えられる精度を得ることができた。
【０１１３】
なお、この複数回の成形のときの温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、温度に付いては第２の冷却完了までの間に全ての温度制御点において２０°Ｃのばらつきの範囲、その後は３０°Ｃのばらつきの範囲に収まり、型ユニットの開閉速度等のばらつきも５％に収まっていたが、さらに条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を越えると精度が悪くなることが確認された。
【０１１４】
（第７の実施形態）
次に第６の実施形態と同じ装置、同じ材料を用いて片面がＲ５０ｍｍ、もう一方の面がＲ４０ｍｍを基準とする非球面形状をなす、レンズの中心肉厚が４．３ｍｍ、直径がΦ２３ｍｍである、コンパクトカメラ用の両凸のガラス非球面レンズの成形を行った。
【０１１５】
第６の実施形態と同様にして、図３Ａに示すように２０°Ｃでの形状２０１に対してガラスの粘度で１０１２ｄＰａ・ｓ（５１５°Ｃ）で第１の補正形状２０４を求め、ヒケ等の補正量２０５を求め、ガラスの粘度で１０１２ｄＰａ・ｓでの補正形状２０６を求める。更に型の収縮を考慮して冷間での型形状２０７，２０７ａを決定する。そして、その形状データにより、上型部材２１の成形面２１ａを多孔質の穴部のくぼみを除いた面をニュートンリングのずれで０．２本以内となるような鏡面状態に加工し、一旦、シミュレーションで決定した成形条件で実際にレンズを成形した。次いで、この成形したレンズの形状を測定し、所定の形状と若干ずれている部分を再度補正加工して、出っ張りのない平滑な鏡面状態に仕上げ、最終的な成形面２１の形状とした。また、下型部材１１の成形面１１ａも同様の手法で形状を求め加工した。また、型部材１１、２１の材料として気孔率が２５％であり、最大穴径が６ミクロンである多孔質からなるＡｌＯ３を用い、流体にはクリーンなエアーを用いた。なお、この成形面の表面には、離型層としてカーボン膜を多孔質の孔が塞がらない様にして蒸着させた。この離型層は型とガラスの融着を防ぎ、成形面の鏡面性を失うものでなければ、特にカーボン膜に限定されるものではない。
【０１１６】
次いで、このように加工準備した型部材１１、２１を図１に示す成形装置に取り付け、第６の実施形態と全く同様にしてガラス塊を切り出し、切削部を研磨加工し、第６の実施形態と全く同様にして軟化状態にあるガラス塊１０２ａを得た。
このガラス塊１０２ａが１０６．５ｄＰａ・ｓの温度になった時点で、成形面１１ａ，２１ａから噴出するエアーの流量を毎分２５リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が４．６ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで噴出エアーの温度と流量を６００℃（ガラスの粘度で１０７．９ｄＰａ・ｓに相当する温度）と毎分１５リッターに設定し、冷間時のレンズの中心肉厚が４．３２ｍｍに相当する位置になった時に、型ユニット１を閉じ、成形面への圧力が４．５ＭＰａとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。なお、このときのガス厚は８ミクロン程度であった。
【０１１７】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に初期に２ＭＰａ、形状が最初に転写しおわるときに８ＭＰａの力が加わる様に徐々に圧力を上げて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
また、軟化ガラス塊１０２ａを得た直後から、予備成形品を得るまでの間に、成形素材への第１の冷却を開始し、予備成形品を得た直後から第２の冷却を開始した。その時において、型構成部材２，３に外部から成形面に前述のように第２の冷却完了時に８ＭＰａの圧力となる様に圧力を加え、下型部材１１と上型部材２１をレンズの肉厚方向の収縮に追従させた。第２の冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となった時点で、下型部材２と上型部材３への加圧を解除すると同時に、第６の実施形態と同様に成形面１１ａ，２１ａから流体を噴出させ、レンズを成形面から離型させた。その後さらに流量を毎分７リッターに設定して、第３の冷却を行い、レンズの表面の温度が４９８°Ｃ（ガラスの粘度で１０１３ｄＰａ・ｓ）を下回ったときに型ユニット１を完全に開き、下型部材１１からはエアーを噴出させたままの状態で、レンズを不図示の吸着ハンドで取り出した。さらにこの成形を数回繰り返し、またこのときの温度及び加圧・減圧等のタイミングの再現性は、第２の冷却完了までは１０°Ｃ、その後は５°Ｃの温度範囲に、速度等のばらつきも３％以内に収まる様に厳密に制御しながら成形を実施した。その後、完成した複数のレンズを２０°Ｃの温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、第６の実施形態以上の良好な結果を得ることができた。
【０１１８】
（第８の実施形態）
次に図４に示す型部材を第６の実施形態で用いた成形装置を用いて、直径がΦ１０ｍｍ、凸面の曲率半径がＲ２０ｍｍ、凹面の曲率半径がＲ３０ｍｍ、中心部の肉厚が３．３ｍｍ、周縁部の厚さが約３．１ｍｍである凸メニスカス形状のレンズを成形した。ここで、図４において、２１１、２２１はそれぞれ下型部材と上型部材であり、それらにはレンズの光学面を形成する成形面２１１ａと２２１ａが加工されている。更に、下型部材２１１と上型部材２２１の外周にはそれぞれレンズの周縁の下部と上部を形成する成形面２１６ａと２２６ａを有したリング部材２１６，２２６が取り付けられている。また、下型部材２１１と上型部材２２１は、気孔率が１５％で最大穴径が１５ミクロン、リング部材２１６，２２６は気孔率が１０％で最大穴径が２０ミクロンの多孔質の窒化珪素で作られていて、図示せぬ供給装置からそれぞれの圧力室１２ｂ，１２ｃ，２２ｂ，２２ｃに流体を個々に独立に供給することができるようになっており、それぞれの光学面の成形面と周縁部の成形面と成形素材の間の流体の膜厚を独立に制御出来るようになっている。また、成形素材は、第６の実施形態と同じガラス材料を用い、流体としては窒素ガスを用いた。また、離型層として第７の実施形態と同様のものを用いた。
【０１１９】
この実施形態では、レンズの光学面の成形面２１１ａ，２２１ａと周縁部の成形面２１６ａ，２２６ａの形状は、一旦レンズの冷間での形状を成形面上にそのまま加工して予備成形を行い、成形された光学素子の形状誤差を補正する様に成形面の補正加工量を求め、それを再度成形面の形状に反映して加工し直し、鏡面状態に仕上げた。また、予備成形における形状転写時の温度は５５５℃（ガラスの粘度で１０１０ｄＰａ・ｓ）として実施した。
【０１２０】
次いで、このように準備した型部材２１１，２２１，２１６，２２６を第６の実施形態と同様に図１に示す成形装置に取り付け、さらに、第６の実施形態で用いたのと同じガラスブロックから、ガラス塊を切り出し、それをさらに研削研磨により容積が２５０ｍｍ３となるようなガラス塊に仕上げ、さらにこのガラス塊の研削研磨面以外の部分に、バーナーによる火炎処理を行うことにより、ガラス塊の表面の５ミクロン以上の鋭角な段差を取り去り、滑らかな表面を有する容量が２５０ｍｍ３のガラス塊を得た。
【０１２１】
次いで、このガラス塊を窒素ガスが毎分２５リッター噴出されている成形面２１１ａの上に載置した後、窒素ガスの温度をガラスの粘度で１０５．４ｄＰａ・ｓに相当する温度である７００℃に上げガラス塊を加熱した。この時上型構成部材３も下型構成部材２の真上に移動させ、成形面２１６ａ，２２１ａ，２２６ａにも同様の温度の窒素ガスを流し、ガラス塊を上下、外周部からも加熱した。このようにすることで、表面に有害な欠陥の全くない、粘度が１０６ｄＰａ・ｓの軟化ガラス塊１０２ａを得た。
【０１２２】
その直後に、成形面２１１ａ，２２１ａから噴出する窒素ガスの流量を毎分２０リッター、成形面２１６ａ，２２６ａからの流量をそれぞれ毎分１４リッター、１２リッターとし、温度をガラスの粘度で１０５．８ｄＰａ・ｓに相当する６８０℃となるように設定し（第１の冷却開始）、更に下型構成部材２と上型構成部材３が互いに逆回転となるような回転方向で、回転数が２００ｒｐｍとなるように徐々に回転速度を上げながら、ガラス塊１０２ａの中心肉厚が３．５ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで、下型構成部材２と上型構成部材３の回転を保った状態で、窒素ガスの温度を６１０℃、成形面２１１ａ，２２１ａからの流量を膜厚が１２ミクロン前後となる様に毎分１５リッター、成形面２１６ａ，２２６ａからの流量がそれぞれ毎分１２リッター、１１リッターとなるように設定し、冷間時のレンズの中心肉厚が３．３３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が成形面で２．５ＭＰａとなる様に圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。
【０１２３】
さらに、その直後にガスの噴出と回転を停止し、レンズの表面近傍の粘度が１０８．５ｄＰａ・ｓとなったときに、さらに型ユニットの成形面に５ＭＰａの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧をし、予備成形品の形状を成形面の形状にならわせた。
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品を得た直後に第６の実施形態と同様に第２の冷却を行った。その時において、型構成部材２，３に外部から成形面に上記のように５ＭＰａの圧力から第２の冷却の完了時に７．５ＭＰａとなる様に圧力を徐々に加えて行き、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。冷却開始後、レンズの表面近傍の粘度が１０１０ｄＰａ・ｓ（温度で約５５５°Ｃ）となったときに、成形面１１ａ，２１ａから第６の実施形態と同様に流体を噴出させ、同時に型構成部材２，３への加圧を解除し、レンズの離型を行った。その後すぐに流体の温度を１５０°Ｃ、流量をそれぞれ毎分５リッターとし、同時に型構成部材２，３の回転を、それぞれの向きが逆方向となるような回転方向で、１５０ｒｐｍの速度で回転させ、流体の膜厚の均一化を図りながら第３の冷却を実施した。ガラスの粘度が１０１３ｄＰａ・ｓを越えたところで型構成部材２，３を停止すると同時に、型ユニット１を開き、レンズを取り出し、室温まで冷却した。更に成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１．２本、クセがニュートンリング０．５本以下に収まり、十分な精度を得ることができた。 また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、第６の実施形態と同様の範囲に収まっており、また、型ユニットの開閉速度及び下型構成部材２と上型構成部材３の回転数等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなることが確認された。
【０１２４】
以上第６乃至第８の実施形態をまとめると、第８の方法においては、第１の工程は、精密素子の成形形状転写時と精密素子の使用時や型ユニットの加工時の温度における精密素子と型ユニットとの熱膨張差による形状の相違量を含めた熱収縮量の補正や、成形及び冷却時の不均一な熱分布に起因する精密素子のヒケの発生位置と量を前もって成形型で補正しておく事により、成形された精密素子が所望の形状を得られるようにする事であり、この際に、予備成形品を得る時の成形面と予備成形品との間に存在する流体の厚さも補正しておく事も必要である。また、型ユニットの成形面を多孔質の材料で作り、その成形面から成形素材に向けてエアーやＮ２ガス等の流体を噴出させ、成形面表面にごく薄い流体膜を形成する事で高温の軟化状態の成形素材と成形面の接触を防ぐ事が出来る。この目的のためには、多孔質の最大穴径が２０ミクロン以下、望ましくは１０ミクロン以下で気孔率が１０〜３５％の材料からなり、材料は耐酸化性のあるアルミナや窒化珪素、炭化珪素等のセラミックや、多孔質カーボン等を用い、更に成形面の表面は、流体膜が破れ、成形素材に傷を付けないようにし、更に補正された形状の精密素子を得る段階での、成形面と予備成形品の接触時の転写性を確保するためには、出っ張りの無い平滑な鏡面状で、精密素子の機能を確保できる所望の面精度に加工されている事が必要となる。
【０１２５】
次に第２の工程は、精密素子の成形素材を準備する際に、成形後の精密素子に欠陥が発生しないように、成形素材の成形後に機能面となる部分に対応する部分の表面を、滑らかに仕上げる工程であり、その部分に相当する部分の表面を光学的な欠陥、つまり加圧成形する事により解消できない欠陥を予め取り除くことである。具体的には、表面を高低差が５ミクロン以上の鋭角的な段差が存在しないように仕上げることであり、傷や欠け等の微視的に見たときに鋭角的な部分が存在しないように処理する事である。この処理は、従来から行われている、研削研磨による方法や、酸処理などによる表面エッチングや、火炎や熱風による表面の軟化光揮処理等により行われる。
【０１２６】
更に第３の工程を実施することにより、成形素材を型ユニットの成形面と非接触の状態で加熱軟化する事が可能となるため、型ユニット上に、成形後に成形面に影響が出ることが無い、無欠陥の表面が非常に滑らかな状態の軟化した成形素材塊を得る事ができる。この時、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度まで成形素材を加熱する事により、次の第４の工程につなげることが可能となる。
【０１２７】
次の第４の工程においても型の成形面から流体を噴出させながら型ユニットを閉じる事により、成形面と高温の成形素材の接触を防ぐ事が可能となり、次工程での補正された形状の精密素子を得る事が容易になるような形状を有した、表面い欠陥の全く無い予備成形品を得ることが出来る。この工程において得る予備成形品の形状は、次工程でのプレス時に、成形素材が大きな変形を起こさずに、変形が成形素材の流動ではなく、見かけ上、ほとんど曲げによる変形であるかのような微少な変形で事足りるような形状である事が望ましい。この為に、予備成形品の形状は、次の工程で得る補正された形状の精密素子のプレスの加圧方向の肉厚に対し、それよりも０〜３％厚くするか、または肉厚より０．５ｍｍを超えない範囲の厚さで、また、外径も同様にほとんど同じかごく僅かに小さな形状である事が望ましく、次工程での加圧力が予備成形品全体に出来るだけ均等にかかり、変形量がどこでも出来るだけ同じとなるような、成形面と相似した形状である事が望ましい。また、このような形状にする事により、次工程での成形が実質的に曲げを主体とする変形となり、成形面を形成する多孔質の材料の穴部の微細な転写が抑制され、穴部の形状が残ら無い表面を有する精密素子を得る事が出来るようになる。更にこの工程において型ユニットを閉じる速度、タイミング、圧力、及び噴出させる流体の流量・圧力、温度等を確実に再現する事により、再現性のある安定した形状の予備成形品を得る事が出来る。これは、型ユニットを、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度範囲の時に閉じ、予備成形品の形状を得た時の流体の膜厚が２０ミクロン以下、より安定した形状の予備成形品を得る場合は、１０ミクロン以下になるように流体の圧力と流量を制御し、また、同時に型を閉じる圧力及び速度も流体の膜厚を前記の範囲内に収まるように成形素材の温度に逆比例させながら制御する事により成形素材を成形面の補正された形状にならわす事により達成される。また、この型ユニットを閉じるときの動作は成形素材の温度に対応して制御される事が望ましく、各々の動作における温度のばらつきは１０℃以下、望ましくは５℃以下とし、同様に噴出させる流体の温度も同じ範囲に収める事が望ましく、流体の流量及び圧力のばらつき及び型ユニットを閉じる速度と圧力のばらつきは５％以内、望ましくは３％以内とする事により、予備成形品の形状をより安定して得る事が可能となる。
【０１２８】
次の第５の工程は、前記第４の工程で得た予備成形品を型部材の成形面に接触させ、補正を施された成形面の形状を正確に予備成形品に転写し、冷却完了後の精密素子の形状を確定するために行われる物であり、予備成形品の表面が、細かな形状を転写しないような条件のもとで、プレス成形が行われる。これは、前述のような材料・材質から作られている型部材の成形面の流体の噴出孔である多孔質の穴部の形状を転写しないように、予備成形品の表面近傍の粘度が高くなった時点で、具体的にはガラスの軟化温度である１０７．６ｄＰａ・ｓの粘度を示す温度以下になった時に、予備成形品と型部材の成形面を接触させた状態で圧力を加えて形状を修正し、補正された成形面の形状を予備成形品に転写させる事であり、この時の圧力も同様に、穴部の形状を転写しないような圧力、具体的には５ＭＰａ以下、好ましくは２ＭＰａ以下である事が望ましい。但し、この圧力は成形素材の粘度と穴部の形状が前述のような時の圧力であり、粘度が高いときや、穴部の大きさが更に細かいときには、もっと高い圧力を加えることも可能である。
【０１２９】
次の第６の工程は、補正された形状の成形面と密着している補正形状の精密素子を、成形面の多孔質の穴から流体を再度噴出させ、成形面から精密素子を浮上させる力を与えると同時に、必要に応じて外部からも成形面から精密素子を引き離す力を与えて離型させ、精密素子と成形面との間に空隙を設ける工程であり、この工程の目的は、一旦成形され補正された形状を有する精密素子の形状が、冷却時の型と成形素材の収縮差により劣化をするのを防ぐ為に行われるものであり、成形素材が成形面と離れても自重や他の外力により変形しにくく、かつ型と素材の収縮量の差が大きくならない温度範囲にて実現される。具体的な温度範囲は、上限に対しては成形面との離型行為や次工程の非接触状態での冷却の初期に変形を起こさない粘度である、１０８ｄＰａ・ｓ以上、望ましくは１０９ｄＰａ・ｓ以上の粘度となる温度以下で行うことが必要である。また、下限の温度は、熱収縮量の差が大きくなり、成形素材が型の収縮に追従できる範囲の温度以上であれば良く、成形素材と型の膨張率の差に大きく左右されるが、通常、成形素材が１０１２ｄｐａ・ｓ以下の粘性を示す温度以上であることが望ましい。また、この工程の離型動作を容易にするために、型の成形面の表面がカーボンや白金等に代表される成形素材との濡れ性の悪い材料で作られていることがより良い結果をもたらす。
【０１３０】
次の第７の工程での第１の冷却は、成形素材の粘度を制御し、型ユニットの成形面の補正された形状を成形素材に転写させ安定した形状の予備成形品を得るために行われるものであり、第１の冷却の完了時に前述の流体の膜厚になるように、成形素材の粘度を制御しながら徐々に冷却を行う。この第１の冷却完了時に於いて、予備成形品が成形面との間に厚さを制御された流体の膜を挟んで成形される事により、次工程に必要な予備成形品の形状精度が確保される。また、この第１の冷却完了時点では、成形素材や型ユニットや流体の温度等は前述の範囲内に収めておく事が望まれる。更にその後の第２の冷却は、一旦接触により転写された補正形状が、成形素材がほぼ固まり、離型時において形状が変化しないような前述の温度まで行われ、更に連続成形において形状のばらつきが生じないように行われるものである。その為には、冷却開始温度や冷却時の冷却速度や温度分布や、特に離型時である冷却完了時の温度及び温度分布を正確に再現する必要がある。この時の再現性は、離型時までの温度のばらつきとして２０℃以下、望ましくは１０℃以下とする事により安定した形状の再現性を得る事が可能となる。また、この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で成形面の補正形状を決定する時に定められるものである。更に、その後の第３の冷却は第１、第２の冷却より速い速度で行うことが出来、ここでの冷却は、一旦離型前までに転写された補正形状が、冷却により補正前の形状、つまり精密素子の本来の所望する形状に一致し、更に連続成形において冷却収縮によりばらつきが生じないように行われるものである。そのためには、補正形状を決定したときの第３の冷却開始温度（＝離型温度）や冷却時の温度分布等の諸条件を正確に再現する必要がある。この再現性は、上記と同様に冷却開始時から成形された精密素子が変形を発生させにくくなる粘度である１０１２ｄＰａ・ｓを示す温度、より精密な転写性を要求されるものや、複雑な形状のものに対しては成形素材が歪を新たに発生させない粘度である１０１４．５ｄＰａ・ｓ迄の温度のばらつきとして３０℃以下、望ましくは１５℃以下とする事により安定した再現性が得られる。また、この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で補正形状を決定する時に定められるものであるが、転写した形状が自重や流体の圧力により変形を起こさないようにするためには、精密素子の表面を毎分２０℃以上の速度で冷却する事が望ましく、また、流体の圧力や流量にも急激な変化を与えないようにする事が望ましい。以上のような冷却を経ることで、この工程の終了時には型ユニットの成形面の形状と成形された精密素子の形状はそれぞれの膨張率の差の分の補正量や、予め見込んでおいたヒケに対する補正量のために完全に一致しないが成形面と非接触状態にあるため、精密素子の形状は型ユニットの成形面の形状に左右される事なく、所望の形状を維持できる。
【０１３１】
次の第８の工程は、第２の冷却中での形状転写時の型部材の成形面と成形素材の熱収縮量の違いによる、形状のズレを補正する工程である。これは、型部材の成形面が精度よく鏡面状態に仕上げられて、その面状態を転写させるような成形においては、型部材と成形素材とに冷却中の収縮量の違いがあると、成形した形状が冷却中に不均一に成形面に接触し、その時々の温度の型の成形面の形状を部分的に転写し、離型後の精密素子の成形面がいびつになったり、不連続な面形状になったりしてしまい、本来の所望とする面形状を得ることが出来なくなってしまうと言う事を防ぐための工程であり、この型と精密素子の接触冷却中の型に成形面を精密素子の表面に、精密素子の肉厚方向の収縮に追従する様に密着させておく事で始めて解決することが出来る。なお、この精密素子の表面への型部材の追従には、成形面と精密素子の間の密着力を利用して行っても良いが、より確実性を増し、精密素子の形状に左右されないようにする為には、型部材から外部に圧力を加える事によって行う事が望ましい。
【０１３２】
最後の第９の工程で、上記のようにすでに固化している精密素子を型ユニットから取り出すことにより、所望の形状を転写された精密素子を得る。この時も精密素子と型ユニットの成形面との間には、流体による膜が介在しているようにする事により、精密素子の表面の成形面との接触による傷などの発生を防ぐと同時に、成形面も固化した精密素子との接触による損傷を防ぐ事が出来る。
【０１３３】
また、第９の方法においては、成形面の予め補正された形状を、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と多孔質の材料で作られた型部材の熱膨張率等を成形条件のパラメータとしてシミュレーションし、事前に成形される精密素子の形状を予測し、それを基に型ユニットの成形面の形状を補正しておく事により、高精度な形状及び面精度を有する精密素子を得る事が出来る。この補正は、型部材と成形素材の熱膨張差に伴う第１の補正と、成形素材の冷却に伴うヒケ等をキャンセルするための第２の補正を組み合わせたものであり、成形型の成形面の形状加工時にこの補正を行うことで、成形が完了し型ユニットから取り出し、更に冷却の完了した時点の精密素子の形状を所望の形状と一致させる事が出来る。
【０１３４】
ここで第１の補正は、形状転写時と型部材の形状加工時や精密素子の使用時の温度差、及び型部材と成形素材の熱膨張率の違いから発生する、型部材の成形面と精密素子の形状のズレ量の補正であり、具体的には、所望の精密素子の使用温度での形状を、第２の冷却の際の型部材の追従が終わる最終的な形状転写温度までの温度差による精密素子の形状変化量を成形素材の膨張率で算出し、更にその精密素子の形状変化量を最終的な形状転写温度から型ユニットの形成面の加工時の温度差までの型部材の形状変化量として型部材の膨張率で算出した量を型部材成形面の形状の第１の補正の量とするものである。第２の補正は、特に精密素子が形状を転写した後に、型内及び型からの取り出し後の冷却による収縮やヒケ等による部分的な変形を含めた変形量の補正であり、主に冷却時に刻々と変化する流体や型ユニットの温度と成形素材の保有熱と温度伝導率に支配される、成形素材自体の温度分布とそれに伴うその時々の粘度分布と熱膨張率とそれらにより算出される応力と、成形素材独自の応力緩和係数によりヒケの量を算出し、更にその量に、その時々の成形素材の自重や流体の圧力変化等による形状の変化量を算出して加算したものを第２の補正の量とするものである。
【０１３５】
また、第１０の方法においては、予め所望する精密素子の最終形状に近似した形状を有する素子を成形し、その成形中及び成形終了後の成形、形状データから得られた情報を型部材の成形面の形状へフィードバックする事により、高精度な形状及び面精度を有する光学素子等を得る事ができる。この補正方法は、最初に精密素子の形状とほぼ同等の形状の成形面を有する型ユニットを用いて、予め設定し、固定された諸条件下で素子を一旦成形し、成形完了後の使用条件と同じ状態の素子の形状と、使用した型ユニットの成形面の形状を比較し、そこで判明した形状の相違量を、基本的には型ユニットの成形面への補正量として用い、成形条件の変更で補正出来るような単純な補正の場合は、成形条件をも修正する事により、成形した精密素子を所望の形状に一致させることが可能となる。また、この補正を数回繰り返すことにより、より精度のよい安定した形状を得る事も可能となり、更に前述のシミュレーションによる型ユニットの成形面の補正方法を組み合わせて実施する事で同様の効果を得る事が出来る。
【０１３６】
また、第１１の方法においては、成形面の多孔質部より噴出する流体の温度を制御する事により、成形素材の温度を制御する事ができる。これは、成形素材が型ユニットと非接触状態にある事や、成形素材が型ユニットに覆われており、外部から成形素材の温度を測定することが実質上不可能であるが、成形素材に直接に接触する流体の温度を制御し、その伝熱により成形素材の温度を間接的に制御する事で解決され、また、こうする事により、成形素材に対して、より応答性の良い確実な温度制御を行うことが出来る。ここで、流体の温度の制御方法としては、流体を供給源の近傍で直接に加熱温調して用いる事でも十分に目的を達成することが出来るが、一旦前述の様に加熱温調した流体を更に流体が成形素材に触れる直前の流体の通路である型ユニット等に組み込まれたヒーター等の加熱源により、再度温調をかけ直して用いることで、より良好な成形素材への温度制御を実現することが可能となる。
【０１３７】
また、第１２の方法においては、成形素材の粘度に合わせ成形型の成形面より噴出される流体の噴出圧力と流体の流量と、型ユニットへの加圧力を制御する事により、高精度な形状及び面精度を有する光学素子を得る事ができる。ここで、成形素材の硬さに相当する粘度変化に同調させて、流体の流量や圧力と型ユニットへの加圧力を制御する事により、型ユニットの成形面と成形素材の間の流体の膜厚を確実に安定させて制御する事が出来、その結果、予備成形品及びその後の完成した精密素子が、より一層、高精度で、かつ連続成形時においてもばらつきの少ない安定した形状を得る事が可能となる。
【０１３８】
また、第１３の方法においては、成形面の形状に近似した形状を有する予備成形品を得る際及び形状転写後の型内での冷却の際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力分布を制御する事により、高精度な形状及び面精度を有する光学素子等を得る事ができる。これは、加圧成形中に型部材を成形素材に対して回転摺動させる事により、成形素材と型部材の成形面との間の流体の膜厚を均一化する事が容易となり、より高精度な精密素子を得る事が出来るようになり、特に回転軸を中心とした軸対称に膜厚が容易に均一化する事により、レンズ等の機能面が軸対称の形状の球面を基本とする形状の精密素子に対しては大きな効果を発揮する事が可能となる。
【０１３９】
（第９の実施形態）
次に第１の実施形態と全く同じものを成形する他の実施形態を述べる。なお、下型１１の成形面１１ａと上型２１の成形面２１ａは、第６の実施形態と全く同様にして、ただし最終的な形状転写時の温度を、ガラス素材が１０１４ｄＰａ・ｓの粘度を示す温度に設定し形状を求め、加工したものを用いた。
【０１４０】
まず、第１の実施例とまったく同様の方法により、成形面１１ａ上にガラス塊１０２ａを得た。
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの成形面１１ａで受けている下面近傍の粘度が１０６〜１０７．５ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面１１ａと成形面２１ａから噴出する窒素ガスの流量を毎分２０リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂとヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が３．２ｍｍとなるまで毎秒５ｍｍの速度で型ユニット１を閉じた。次いで窒素ガスの温度と流量をガスの膜厚が２０ミクロン程度となる様に、６００℃と毎分１０リッターに設定し、冷間時のレンズの中心肉厚が３．０５ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が２０Ｋｇｆとなるように圧力を徐々に上げながら、且つ、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。
【０１４１】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に２００ｋｇｆの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
また、軟化ガラス塊１０２ａを得た直後から、予備成形品を得るまでの間に、成形素材への第１の冷却を開始し、予備成形品を得た直後から第２の冷却を開始した。第２の冷却は不図示の冷却装置により型ユニット１の外部より、冷却用の窒素ガスを吹きつけることにより行われ、その時において、型構成部材２，３への外部からの拘束を解き、下型部材１１及び上型部材２１がレンズの収縮に追従出来るようにした。冷却開始後、レンズの表面近傍の粘度が１０１４ｄＰａ・ｓとなり、成形面１１ａ，２１ａとレンズとの間の密着力が無くなった時点で型ユニット１を開き、レンズを不図示の吸着ハンドで取り出し、室温まで冷却した。さらに成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１．５本、クセがニュートンリング１本以下に収まり、十分な精度を得ることができた。
【０１４２】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、すべての温度制御点において１０°Ｃのばらつき範囲に収まり、また、型ユニットの開閉速度等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなることが確認された。
【０１４３】
（第１０の実施形態）
次に第９の実施形態と同じ装置、同じ材料を用いて片面がＲ５０ｍｍ、もう一方の面がＲ４０ｍｍを基準とする非球面形状をなす、レンズの中心肉厚が４．３ｍｍ、直径がΦ２３ｍｍである、コンパクトカメラ用の両凸のガラス非球面レンズの成形を行った。
【０１４４】
第９の実施形態と同様に、下型部材１１の成形面１１ａと上型部材２１の成形面２１ａは、成形前にシミュレーションにより求めた数々の補正を考慮した形状に加工し、その後更に実際に成形を行い、その形状データをもとに最終的な補正を行って形状を決定した。具体的には、第９の実施形態と同様に、上型２１の成形面２１ａの場合、図３Ａに示すように、精密素子であるレンズの標準的な使用条件である２０℃における形状２０１（Ｒ４０ｍｍを基準とする非球面形状）に対し、成形時の形状転写時の温度を、ガラスの粘度で１０１２ｄＰａ・ｓを示す温度に設定し、第１の補正の量の一部であるガラスの温度膨張による変形量を算出し、その結果から、この条件下における精密素子の形状２０４を求めた。次に第２の補正の量に相当する、形状転写後の冷却によるヒケ等による補正量２０５を求め、形状転写時の成形面の部分的な形状２０６を決定し、更に第１の補正の量の残りの部分に相当する、型ユニットの成形面の材料の温度収縮による補正の量から、型の冷間時、特に型の成形面の形状を加工する時の成形面の形状２０７及び２０７ａ（図３Ａにおいて２０７と２０７ａのハッチング部分の形状）を求た。そして、その形状データにより、上型部材２１の成形面２１ａを多孔質の穴部のくぼみを除いた面を鏡面状態に加工し、一旦、シミュレーションで決定した成形条件で実際にレンズを成形した。次いで、この成形したレンズの形状を測定し、所定の形状と若干ずれている部分を再度補正加工して、出っ張りのない平滑な鏡面状態に仕上げ、最終的な成形面２１の形状とした。また、下型部材１１の成形面１１ａも同様の手法で形状を求め加工した。また、型部材１１、２１の材料として気孔率が２５％であり、最大穴径が６ミクロンである多孔質からなるＡｌＯ３を用い、流体にはクリーンなエアーを用いた。なお、この成形面の表面には、離型層としてカーボン膜を多孔質の孔が塞がらない様にして蒸着させた。この離型層は型とガラスの融着を防ぎ、成形面の鏡面性を失うものでなければ、特にカーボン膜に限定されるものではない。
【０１４５】
次いで、このように加工準備した型部材１１、２１を図１に示す成形装置に取り付け、第１の実施形態と全く同様にしてガラス塊１０２ａを得た。
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの下型部材１１で受けている下面近傍の粘度が１０６〜１０７．５ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面１１ａ，２１ａから噴出するエアーの流量を毎分２５リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が４．６ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで噴出エアーの温度と流量を６００℃と毎分１５リッターに設定し、冷間時のレンズの中心肉厚が４．３２ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が４５Ｋｇｆとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。なお、このときのガスの膜厚は８ミクロン程度であった。
【０１４６】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に２２０ｋｇｆの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品の形状を型の成形面の形状にならわせた直後に第９の実施形態と同様に第２の冷却を行った。その時において、型構成部材２，３に外部から１５０ｋｇｆの圧力を加え、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となったときに、型構成部材２，３への加圧を解除すると同時に型ユニット１を開き、レンズを取り出し室温まで冷却した。さらにこの成形を数回繰り返し、またこのときの温度及び加圧・減圧等のタイミングの再現性は、５°Ｃの温度範囲に、速度等のばらつきも３％以内に収まる様に厳密に制御しながら成形を実施した。その後、完成した複数のレンズを２０°Ｃの温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、第９の実施形態以上の良好な結果を得ることができた。
【０１４７】
（第１１の実施形態）
次に図４に示す型部材を第１の実施形態で用いた成形装置を用いて、直径がΦ１０ｍｍ、凸面の曲率半径がＲ２０ｍｍ、凹面の曲率半径がＲ３０ｍｍ、中心部の肉厚が３．３ｍｍ、周縁部の厚さが約３．１ｍｍである凸メニスカス形状のレンズを成形した。ここで、図４において、２１１、２２１はそれぞれ下型部材と上型部材であり、それらにはレンズの光学面を形成する成形面２１１ａと２２１ａが加工されている。更に、下型部材２１１と上型部材２２１の外周にはそれぞれレンズの周縁の下部と上部を形成する成形面２１６ａと２２６ａを有したリング部材２１６，２２６が取り付けられている。また、下型部材２１１と上型部材２２１は、気孔率が１５％で最大穴径が１５ミクロン、リング部材２１６，２２６は気孔率が１０％で最大穴径が２０ミクロンの多孔質の窒化珪素で作られていて、図示せぬ供給装置からそれぞれの圧力室１２ｂ，１２ｃ，２２ｂ，２２ｃに流体を個々に独立に供給することができるようになっており、それぞれの光学面の成形面と周縁部の成形面と成形素材の間の流体の膜厚を独立に制御出来るようになっている。また、成形素材は、第１の実施形態と同じガラス材料を用い、流体としては窒素ガスを用いた。また、離型層として第１０の実施形態と同様のものを用いた。
【０１４８】
この実施形態では、レンズの光学面の成形面２１１ａ，２２１ａと周縁部の成形面２１６ａ，２２６ａの形状は、一旦レンズの冷間での形状を成形面上にそのまま加工して予備成形を行い、成形された光学素子の形状誤差を補正する様に成形面の補正加工量を求め、それを再度成形面の形状に反映して加工し直し、鏡面状態に仕上げた。また、このときの最終的な形状転写時の温度は５１５°Ｃ（ガラスの粘度で１０１２ｄＰａ・ｓ）として実施した。
【０１４９】
次いで、このように準備した型部材２１１，２２１，２１６，２２６を第１の実施形態と同様に図１に示す成形装置に取り付け、同様の方法で軟化ガラス塊を得た。この時の窒素ガスの温度は、ガラスを成形面２１１ａに受ける時はガラスの転移点付近の温度である５００℃に、その直後にはガラスの粘度で１０７．３ｄＰａ・ｓに相当する温度である６２０℃になるように温度を調整し、更に窒素ガスの流量は、溶融ガラス１０２を成形面２１１ａに受ける直前までは、成形面２１１ａで毎分１８リッター、成形面２１６ａで毎分８リッター、その後はどちらも毎分５リッターとなるように制御した。
【０１５０】
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの下型部材２１１で受けている下面近傍の粘度が１０５．６〜１０７ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜１０５．６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面２１１ａ，２２１ａから噴出する窒素ガスの流量を毎分２０リッター、成形面２１６ａ，２２６ａからの流量をそれぞれ毎分１４リッター、１２リッターとし、温度をガラスの粘度で１０５．８ｄＰａ・ｓに相当する６８０℃となるように設定し（第１の冷却開始）、更に下型構成部材２と上型構成部材３が互いに逆回転となるような回転方向で、回転数が２００ｒｐｍとなるように徐々に回転速度を上げながら、ガラス塊１０２ａの中心肉厚が３．５ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで、下型構成部材２と上型構成部材３の回転を保った状態で、窒素ガスの温度を６１０℃、成形面２１１ａ，２２１ａからの流量を膜厚が１２ミクロン前後となる様に毎分１５リッター、成形面２１６ａ，２２６ａからの流量がそれぞれ毎分１２リッター、１１リッターとなるように設定し、冷間時のレンズの中心肉厚が３．３３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が２５Ｋｇｆとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。
【０１５１】
さらに、その直後にガスの噴出と回転を停止し、さらに型ユニット１の成形面に１００ｋｇｆの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品を得た直後に第１０の実施形態と同様に第２の冷却を行った。その時において、型構成部材２，３に外部から７５ｋｇｆの圧力を加え、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となったときに、型構成部材２，３への加圧を解除すると同時に型ユニット１を開き、レンズを取り出し室温まで冷却した。さらに成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、十分な精度を得ることができた。
【０１５２】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、すべての温度制御点において１０°Ｃのばらつき範囲に収まり、また、型ユニットの開閉速度及び型構成部材の回転数等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなることが確認された。
【０１５３】
以上第９乃至第１１の実施形態をまとめると、第１４の方法においては、第１の工程は、精密素子の成形形状転写時と精密素子の使用時や型ユニットの加工時の温度における精密素子と型ユニットとの熱膨張差による形状の相違量を含めた熱収縮量の補正や、成形及び冷却時の不均一な熱分布に起因する精密素子のヒケの発生位置と量を前もって成形型で補正しておく事により、成形された精密素子が所望の形状を得られるようにする事である。また、型ユニットの成形面を多孔質の材料で作り、その成形面から成形素材に向けてエアーやＮ２ガス等の流体を噴出させ、成形面表面にごく薄い流体膜を形成する事で高温の軟化状態の成形素材と成形面の接触を防ぐ事が出来る。この目的のためには、多孔質の最大穴径が２０ミクロン以下、望ましくは１０ミクロン以下で気孔率が１０〜３５％の材料からなり、材料は耐酸化性のあるアルミナや窒化珪素、炭化珪素等のセラミックや、多孔質カーボン等を用い、更に成形面の表面は、流体膜が破れ、成形素材に傷を付けないようにし、更に接触時の面精度の転写性を確保するためにも、出っ張りの無い平滑な鏡面状で、精密素子の機能を確保できる粗さに加工されている事が必要となる。
【０１５４】
次に第２の工程により、型と成形素材の接触、特に溶融軟化された形状が不定の状態の成形素材をノズルから流出させ型ユニットに供給する時に発生しやすい成形素材と型ユニットの成形面との接触を防ぐ事が出来、更にこの時に、一時的に噴出する流体の温度を下げたり流量を増やすことにより、接触を確実に防ぐ事が出来る。また、型ユニットの成形面上に供給された成形素材を前記ノズルから分離する際に、型ユニット上に成形素材を必要量を受け止めた後、型ユニットと一旦下降させ、ノズルより流出する成形素材と型ユニット上の成形素材との間にくびれを発生させ、更に成形素材の自重と表面張力によりくびれを発達させ分離を行う事により、型ユニット上に、成形後に影響が出るような欠陥の全く無い、表面が非常に滑らかな成形素材塊を得ることが出来る。
【０１５５】
次に第３の工程においても型の成形面から流体を噴出させながら型ユニットを閉じる事により、成形面と成形素材の接触を防ぐ事が可能となり、次工程での補正された形状の精密素子を得る事が容易になるような形状を有した、表面に欠陥の全く無い予備成形品を得ることが出来る。この工程において得る予備成形品の形状は、次工程でのプレス時に、成形素材が大きな変形を起こさずに、変形が成形素材の流動ではなく、見かけ上、ほとんど曲げによる変形であるかのような微少な変形で事足りるような形状である事が望ましい。この為に、予備成形品の形状は、次の工程で得る補正された形状の精密素子のプレスの加圧方向の肉厚に対し、それよりも０〜３％厚くするか、又は肉厚より０．５ｍｍを超えない範囲の厚さで、また、外径も同様にほとんど同じかごく僅かに小さな形状である事が望ましく、次工程での加圧力が予備成形品全体に出来るだけ均等に掛かり、変形量がどこでも出来るだけ同じとなるような、成形面と相似した形状である事が望ましい。また、このような形状にする事により、次工程での成形が実質的に曲げを主体とする変形となり、成形面を形成する多孔質の材料の穴部の微細な転写が抑制され、穴部の形状が残ら無い表面を有する精密素子を得る事が出来るようになる。更にこの工程において型ユニットを閉じる速度、タイミング、圧力、及び噴出させる流体の流量・圧力、温度等を確実に再現する事により、再現性のある安定した形状の予備成形品を得る事が出来る。これは、型ユニットを、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度範囲の時に閉じ、予備成形品の形状を得た時の流体の膜厚が２０ミクロン以下、より安定した形状の予備成形品を得る場合は、１０ミクロン以下になるように流体の圧力と流量を制御し、また、同時に型を閉じる圧力及び速度も流体の膜厚を前記の範囲内に収まるように成形素材の温度に逆比例させながら制御する事により成形素材を成形面の補正された形状にならわす事により達成される。また、この型ユニットを閉じるときの動作は成形素材の温度に対応して制御される事が望ましく、各々の動作における温度のばらつきは１０℃以下、望ましくは５℃以下とし、同様に噴出させる流体の温度も同じ範囲に収める事が望ましく、流体の流量及び圧力のばらつき及び型ユニットを閉じる速度と圧力のばらつきは５％以内、望ましくは３％以内とする事により、型ユニットの成形面の形状をより安定して得る事が可能となる。
【０１５６】
次の第４の工程は、前記工程で得た予備成形品を型部材の成形面に接触させ、補正を施された成形面の形状を正確に予備成形品に転写し、冷却完了後の精密素子の形状を確定するために行われるものであり、予備成形品の表面が、細かな形状を転写しないような条件のもとで、プレス成形が行われる。これは、前述のような材料・材質から作られている型部材の成形面の流体の噴出孔である多孔質の穴部の形状を転写しないように、予備成形品の表面近傍の粘度が高くなった時点で、具体的には１０７．６ｄＰａ・ｓ以上の粘度となった時に、予備成形品と型部材の成形面を接触させた状態で圧力を加えて形状を修正し、補正された成形面の形状を予備成形品に転写させる事であり、この時の圧力も同様に、穴部の形状を転写しないような圧力、具体的には５ＭＰａ以下、好ましくは２ＭＰａ以下である事が望ましい。但し、この圧力は成形素材の粘度と穴部の形状が前述のような時の圧力であり、粘度が高いときや、穴部の大きさが更に細かいときには、もっと高い圧力を加えることも可能である。
【０１５７】
次の第５の工程での第１の冷却は、成形素材の粘度を制御し、型ユニットの成形面の補正された形状を成形素材に転写させ安定した形状の予備成形品を得るために行われるものであり、第１の冷却の完了時に前述の流体の膜厚になるように、成形素材の粘度を制御しながら徐々に冷却を行う。この第１の冷却完了時において、予備成形品が成形面との間に厚さを制御された流体の膜を挟んで成形される事により、次工程に必要な予備成形品の形状精度が確保される。また、この第１の冷却完了時点では、成形素材や型ユニットや流体の温度等は前述の範囲内に収めておく事が望まれる。更にその後の第２の冷却は第１の冷却より速い速度で行うことが出来、ここでの冷却は、一旦転写された補正形状が、冷却により補正前の形状、つまり精密素子の本来の所望する形状に一致し、更に連続成形において冷却収縮等によりばらつきが生じないように行われるものである。その為には、冷却開始温度や冷却時の冷却速度や温度分布等の諸条件を正確に再現する必要がある。この再現性は、上記と同様に冷却開始時から成形素材の粘度で１０12ｄＰａ・ｓを示す温度の範囲での温度のばらつきとして１０℃以下、望ましくは５℃以下とする事により安定した形状の再現性が得られる。又この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で成形面の補正形状を決定する時に定められるものである。
【０１５８】
次の第６の工程は、形状転写後の型部材の成形面と成形素材の熱収縮量の違いによる、冷却時の形状のズレを補正する工程である。これは、通常、加圧変形できる温度状態の成形素材は粘着力があり、特に型部材の成形面が精度よく鏡面状態に仕上げられて、その面状態を転写させるような成形においては、この力が成形素材の表面と成形面との間に強い密着力として働く。この力は接触面の形状や接触面の界面の微細な状態に左右され易く、それ故その力の大きさは不安定であり、その分布状態も不均一である為、接触面全体が一様に剥離せずに、部分的に徐々に剥離して行ったり、段階的に剥離して行き、その結果、出来上がった面状態が不安定で、場合によっては成形された面が不連続になったりしてしまい、最終的に所望の形状と一致させる事ができないという問題がある。この問題は、少なくとも、型の素材の間に、転写面を変形させるような大きさの密着力が働いている間に、その素子の表面と成形面の密着を維持するように、その素子の収縮に合せて型部材を追従させる事により初めて解決させることが可能となる。
【０１５９】
更に前記の第２の冷却を、この型部材の追従の工程が完了するまで行い、その後、型ユニットを開き成形素子を取り出す事（第７の工程）により、所望の形状に近似した形状を有する成形素子を得ることが出来る。また、この第２の冷却の終了点、つまり型部材の追従工程完了時点は、密着力如何により決められる物であるが、通常、素材の粘度で１０１２〜１４．５ｄＰａ・ｓで行われるのが理想的である。
【０１６０】
次の第８の工程で、この所望の形状に近似した形状を有する成形素子を更に室温迄冷却する事により、熱収縮が起こり、前記素子が所望の形状を有する精密素子の形状となり、目的とする精密素子を得ることが出来る。
また、第１５の方法においては、成形面の予め補正された形状を、流体の圧力、流量、温度、及び成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と多孔質の材料で作られた型部材の熱膨張率等を成形条件のパラメーターとしてシミュレーションし、事前に成形される精密素子の形状を予測し、それを基に型ユニットの成形面の形状を補正しておく事により、高精度な形状及び面精度を有する精密素子を得る事ができる。この補正は、型部材と成形素材の熱膨張差に伴う第１の補正と、成形素材の冷却に伴うヒケ等をキャンセルするための第２の補正を組み合わせたものであり、成形型の成形面の形状加工時にこの補正を行うことで、成形が完了し型ユニットより取り出し、更に冷却の完了した時点の精密素子の形状を所望の形状と一致させる事が出来る。
【０１６１】
ここで第１の補正は、形状転写時と型部材の形状加工時や精密素子の使用時の温度差、及び型部材と成形素材の熱膨張率の違いから発生する、型部材の成形面と精密素子の形状のズレ量の補正であり、具体的には、所望の精密素子の使用温度での形状を、第２の冷却の際の型部材の追従が終わる最終的な形状転写温度までの温度差による精密素子の形状変化量を成形素材の膨張率で算出し、更にその精密素子の形状変化量を最終的な形状転写温度から型ユニットの形成面の加工時の温度差までの型部材の形状変化量として型部材の膨張率で算出した量を型部材の成形面の形状の第１の補正の量とするものである。第２の補正は、特に精密素子が形状を転写した後に、冷却され型から取り出され、更に取り出し後の冷却による収縮やヒケ等による部分的な変形を含めた変形量の補正であり、主に冷却時に刻々と変化する成形素材の保有熱と温度伝導率に支配される、成形素材自体の温度分布とそれに伴うその時々の粘度分布と熱膨張率とそれらにより算出される応力と、成形素材独自の応力緩和係数によりヒケの量を算出し、更にその量に、その時々の成形素材の自重や外部応力の変化等による形状の変化量を算出して加算したものを第２の補正の量とするものである。
【０１６２】
また、第１６の方法においては、予め所望する精密素子の最終形状に近似した形状を有する素子を成形し、その成形中及び成形終了後の成形、形状データから得られた情報を型部材の成形面の形状へフィードバックする事により、高精度な形状及び面精度を有する光学素子等を得る事ができる。この補正方法は、最初に精密素子の形状とほぼ同等の形状の成形面を有する型ユニットを用いて、予め設定し、固定された諸条件下で素子を一旦成形し、成形完了後の使用条件と同じ状態の素子の形状と、使用した型ユニットの成形面の形状を比較し、そこで判明した形状の相違量を、基本的には型ユニットの成形面への補正量として用い、成形条件の変更で補正出来るような単純な補正の場合は、成形条件をも修正する事により、成形した精密素子を所望の形状に一致させることが可能となる。また、この補正を数回繰り返すことにより、より精度のよい安定した形状を得る事も可能となり、更に前述のシミュレーションによる型ユニットの成形面の補正方法を組み合わせて実施する事で同様の効果を得る事が出来る。
【０１６３】
また、第１７の方法は、前記成形面の多孔質部より噴出する流体の温度を制御する事により、成形素材の温度を制御する事ができる。これは、成形面の形状に近似した形状を有する予備成形品を得る際に、成形素材が型ユニットと非接触状態にある事や、成形素材が型ユニットに覆われており、外部から成形素材の温度を測定することが実質上不可能であるが、成形素材に直接に接触する流体の温度を制御し、その伝熱により成形素材の温度を間接的に制御する事で解決され、また、こうする事により、成形素材に対して、より応答性の良い確実な温度制御を行うことが出来る。ここで、流体の温度の制御方法としては、流体を供給源の近傍で直接に加熱温調して用いる事でも十分に目的を達成することが出来るが、一旦前述の様に加熱温調した流体を更に流体が成形素材に触れる直前の流体の通路である型ユニット等に組み込まれたヒーター等の加熱源により、再度温調をかけ直して用いることで、より良好な成形素材への温度制御を実現することが可能となる。
【０１６４】
また、第１８の方法においては、前記の第１７の方法と同様に、成形面の形状に近似した形状を有する予備成形品を得る際に、成形素材の粘度に合わせ成形型の成形面より噴出される流体の噴出圧力と流体の流量と、型ユニットへの加圧力を制御する事により、安定的な形状を有する予備成形品を得る事ができる。ここで、成形素材の硬さに相当する粘度変化に同調させて、流体の流量や圧力と型ユニットへの加圧力を制御する事により、型ユニットの成形面と成形素材の間の流体の膜厚を確実に安定させて制御する事が出来、その結果、成形された予備成形品が、連続成形時においてもばらつきの少ない安定した形状を得る事が可能となる。
【０１６５】
また、第１９の方法においては、第２の冷却の際の型部材の追従を、成形面と精密素子の間の密着力を利用して行う事により高精度な精密素子を得られるようにする事であり、型部材の少なくとも一つを、精密素子の肉厚方向の収縮に追従できるように、外部からの拘束を解くことにより実現される。
また、第２０の方法においては、第１９の方法と同様に、第２の冷却の際の型部材の追従を、型部材に外部から圧力を加える事により、より確実に実行する事により、より安定的に高精度な精密素子を得られるようにする事であり、型部材の少なくとも一つに、精密素子の肉厚方向の収縮に追従できるように、外部から圧力を加える事により実現される。
【０１６６】
（第１２の実施形態）
次に第１の実施形態と全く同じものを成形する他の実施形態を述べる。なお、下型１１の成形面１１ａと上型２１の成形面２１ａは、第６の実施形態と全く同様にして、ただし最終的な形状転写時の温度を、ガラス素材が１０１４ｄＰａ・ｓの粘度を示す温度に設定し形状を求め、加工したものを用いた。
【０１６７】
まず、このように加工準備した型部材１１，２１を図１に示す成形装置に取り付け、さらに第１の実施形態で用いたと同じガラスブロックから、ガラス塊を切り出し、それを図５（ａ）に示す様に更に研削研磨により容積で３１１ｍｍ３となるようなガラス塊に仕上げ、更に、このガラス塊の研削研磨面以外の部分に、バーナーによる火炎処理を行うことにより、ガラス塊の表面の５ミクロン以上の鋭角な段差を取り去り、図５（ｂ）に示すような滑らかな表面を有する容量が３１１ｍｍ３のガラス塊を得た。
【０１６８】
次いで、このガラス塊を窒素ガスが毎分３０リッター噴出されている成形面１１ａの上に載置した後、ヒータ１３と加熱ヒータ３３ａにより、窒素ガスの温度をガラスの粘度で１０５．４ｄＰａ・ｓに相当する温度である７００℃に上げガラス塊を加熱した。この時上型構成部材３も下型構成部材２の真上に移動させ、同様の温度の窒素ガスを流し、ガラス塊を上部からも加熱した。このようにすることで、表面に有害な欠陥の全くない、粘度が１０６ｄＰａ・ｓの軟化ガラス塊１０２ａを得た。
【０１６９】
次に、成形面１１ａ，２１ａから噴射する窒素ガスの流量を毎分２０リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が３．２ｍｍとなるまで毎秒５ｍｍの速度で型ユニット１を閉じ、中心肉厚が３．０５ｍｍの予備成形品を得た。
【０１７０】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に２００ｋｇｆの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧をし、予備成形品の形状を成形面の形状にならわせた。
また、軟化ガラス塊１０２ａを得た直後から、予備成形品を得るまでの間に、成形素材への第１の冷却を開始し、予備成形品を得た直後から第２の冷却を開始した。第２の冷却は不図示の冷却装置により型ユニット１の外部より、冷却用の窒素ガスを吹きつけることにより行われ、その時において、型構成部材２，３への外部からの拘束を解き、下型部材１１及び上型部材２１がレンズの収縮に追従出来るようにした。冷却開始後、レンズの表面近傍の粘度が１０１４ｄＰａ・ｓとなり、成形面１１ａ，２１ａとレンズとの間の密着力が無くなった時点で型ユニット１を開き、レンズを不図示の吸着ハンドで取り出し、室温まで冷却した。さらに成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１．５本、クセがニュートンリング１本以下に収まり、十分な精度を得ることができた。
【０１７１】
更に、最初に準備するガラス塊の表面処理の条件を多少振りながら成形を続けた結果、表面に残る段差が５ミクロンを越えたり、鋭角的な段差が残ったりすると、加熱軟化した後に、表面を更に滑らかにするための時間が非常にかかったり、場合によっては、この加熱軟化により段差が解消せず、成形後のレンズ表面に欠陥が残ったりし、実用上、大きな問題になることが確認された。
【０１７２】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、すべての温度制御点において１０°Ｃのばらつき範囲に収まり、また、型ユニットの開閉速度等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなり、また、冷却速度、特に第２の冷却速度が毎分２０°Ｃより遅くなると自重変形や窒素ガスの圧力の影響を受けやすくなり、精度が劣化することが確認された。
【０１７３】
（第１３の実施形態）
次に第１２の実施形態と同じ装置、同じ材料を用いて片面がＲ５０ｍｍ、もう一方の面がＲ４０ｍｍを基準とする非球面形状をなす、レンズの中心肉厚が４．３ｍｍ、直径がΦ２３ｍｍである、コンパクトカメラ用の両凸のガラス非球面レンズの成形を行った。
【０１７４】
第１２の実施形態と同様に、下型部材１１の成形面１１ａと上型部材２１の成形面２１ａは、成形前にシミュレーションにより求めた数々の補正を考慮した形状に加工し、その後更に実際に成形を行い、その形状データをもとに最終的な補正を行って形状を決定した。具体的には、第１４の実施形態と同様に、上型２１の成形面２１ａの場合、図３Ａに示すように、精密素子であるレンズの標準的な使用条件である２０℃における形状２０１（Ｒ４０ｍｍを基準とする非球面形状）に対し、成形時の形状転写時の温度を、ガラスの粘度で１０１２ｄＰａ・ｓを示す温度に設定し、第１の補正の量の一部であるガラスの温度膨張による変形量を算出し、その結果から、この条件下における精密素子の形状２０４を求めた。次に第２の補正の量に相当する、形状転写後の冷却によるヒケ等による補正量２０５を求め、形状転写時の成形面の部分的な形状２０６を決定し、更に第１の補正の量の残りの部分に相当する、型ユニットの成形面の材料の温度収縮による補正の量から、型の冷間時、特に型の成形面の形状を加工する時の成形面の形状２０７及び２０７ａ（図３Ａにおいて２０７と２０７ａのハッチング部分の形状）を求た。そして、その形状データにより、上型部材２１の成形面２１ａを多孔質の穴部のくぼみを除いた面をニュートンリングのずれで０．２本以内となるような鏡面状態に加工し、一旦、シミュレーションで決定した成形条件で実際にレンズを成形した。次いで、この成形したレンズの形状を測定し、所定の形状と若干ずれている部分を再度補正加工して、出っ張りのない平滑な鏡面状態に仕上げ、最終的な成形面２１の形状とした。また、下型部材１１の成形面１１ａも同様の手法で形状を求め加工した。また、型部材１１、２１の材料として気孔率が２５％であり、最大穴径が６ミクロンである多孔質からなるＡｌＯ３を用い、流体にはクリーンなエアーを用いた。なお、この成形面の表面には、離型層としてカーボン膜を多孔質の孔が塞がらない様にして蒸着させた。この離型層は型とガラスの融着を防ぎ、成形面の鏡面性を失うものでなければ、特にカーボン膜に限定されるものではない。
【０１７５】
次いで、このように加工準備した型部材１１、２１を図１に示す成形装置に取り付け、第１２の実施形態と全く同様にしてガラス塊を切り出し、切削部を研磨加工し、第１２の実施形態と全く同様にして軟化状態にあるガラス塊１０２ａを得た。
このガラス塊１０２ａが１０６．５ｄＰａ・ｓの温度になった時点で、成形面１１ａ，２１ａから噴出するエアーの流量を毎分２５リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が４．６ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで噴出エアーの温度と流量を６００℃（ガラスの粘度で１０７．９ｄＰａ・ｓに相当する温度）と毎分１５リッターに設定し、冷間時のレンズの中心肉厚が４．３２ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が４５ｋｇｆとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。なお、このときのガス厚は８ミクロン程度であった。
【０１７６】
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品を得た直後に第１２の実施形態と同様に第２の冷却を行った。その時において、型構成部材２，３に外部から１５０ｋｇｆの圧力を加え、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となったときに、型構成部材２，３への加圧を解除すると同時に型ユニット１を開き、レンズを取り出し室温まで冷却した。さらにこの成形を数回繰り返し、またこのときの温度及び加圧・減圧等のタイミングの再現性は、５°Ｃの温度範囲に、速度等のばらつきも３％以内に収まる様に厳密に制御しながら成形を実施した。その後、完成した複数のレンズを２０°Ｃの温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、第１２の実施形態以上の良好な結果を得ることができた。
【０１７７】
（第１４の実施形態）
次に図４に示す型部材を第１２の実施形態で用いた成形装置を用いて、直径がΦ１０ｍｍ、凸面の曲率半径がＲ２０ｍｍ、凹面の曲率半径がＲ３０ｍｍ、中心部の肉厚が３．３ｍｍ、周縁部の厚さが約３．１ｍｍである凸メニスカス形状のレンズを成形した。ここで、図４において、２１１、２２１はそれぞれ下型部材と上型部材であり、それらにはレンズの光学面を形成する成形面２１１ａと２２１ａが加工されている。更に、下型部材２１１と上型部材２２１の外周にはそれぞれレンズの周縁の下部と上部を形成する成形面２１６ａと２２６ａを有したリング部材２１６，２２６が取り付けられている。また、下型部材２１１と上型部材２２１は、気孔率が１５％で最大穴径が１５ミクロン、リング部材２１６，２２６は気孔率が１０％で最大穴径が２０ミクロンの多孔質の窒化珪素で作られていて、図示せぬ供給装置からそれぞれの圧力室１２ｂ，１２ｃ，２２ｂ，２２ｃに流体を個々に独立に供給することができるようになっており、それぞれの光学面の成形面と周縁部の成形面と成形素材の間の流体の膜厚を独立に制御出来るようになっている。また、成形素材は、第１２の実施形態と同じガラス材料を用い、流体としては窒素ガスを用いた。また、離型層として第１３の実施形態と同様のものを用いた。
【０１７８】
この実施形態では、レンズの光学面の成形面２１１ａ，２２１ａと周縁部の成形面２１６ａ，２２６ａの形状は、一旦レンズの冷間での形状を成形面上にそのまま加工して予備成形を行い、成形された光学素子の形状誤差を補正する様に成形面の補正加工量を求め、それを再度成形面の形状に反映して加工し直し、鏡面状態に仕上げた。また、予備成形における形状転写時の温度は５１５℃（ガラスの粘度で１０１２ｄＰａ・ｓ）として実施した。
【０１７９】
次いで、このように準備した型部材２１１，２２１，２１６，２２６を第１２の実施形態と同様に図１に示す成形装置に取り付け、さらに、第１４の実施形態で用いたのと同じガラスブロックから、ガラス塊を切り出し、それをさらに研削研磨により容積が２５０ｍｍ３となるようなガラス塊に仕上げ、さらにこのガラス塊の研削研磨面以外の部分に、バーナーによる火炎処理を行うことにより、ガラス塊の表面の５ミクロン以上の鋭角な段差を取り去り、滑らかな表面を有する容量が２５０ｍｍ３のガラス塊を得た。
【０１８０】
次いで、このガラス塊を窒素ガスが毎分２５リッター噴出されている成形面２１１ａの上に載置した後、窒素ガスの温度をガラスの粘度で１０５．４ｄＰａ・ｓに相当する温度である７００℃に上げガラス塊を加熱した。この時上型構成部材３も下型構成部材２の真上に移動させ、成形面２１６ａ，２２１ａ，２２６ａにも同様の温度の窒素ガスを流し、ガラス塊を上下、外周部からも加熱した。このようにすることで、表面に有害な欠陥の全くない、粘度が１０６ｄＰａ・ｓの軟化ガラス塊１０２ａを得た。
【０１８１】
その直後に、成形面２１１ａ，２２１ａから噴出する窒素ガスの流量を毎分２０リッター、成形面２１６ａ，２２６ａからの流量をそれぞれ毎分１４リッター、１２リッターとし、温度をガラスの粘度で１０５．８ｄＰａ・ｓに相当する６８０℃となるように設定し（第１の冷却開始）、更に下型構成部材２と上型構成部材３が互いに逆回転となるような回転方向で、回転数が２００ｒｐｍとなるように徐々に回転速度を上げながら、ガラス塊１０２ａの中心肉厚が３．５ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じ、さらにレンズの中心肉厚が３．３３ｍｍになった時に、型ユニット１を閉じる圧力が２５ｋｇｆとなる様に圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。なお、このときのガス層の厚みは平均１２ミクロンであった。
【０１８２】
さらに、その直後にガスの噴出と型構成部材２，３の回転を停止し、さらに型ユニットに１００ｋｇｆの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧をし、予備成形品の形状を成形面の形状にならわせた。
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品を得た直後に第１２の実施形態と同様に第２の冷却を行った。その時において、予備成形品の形状が成形面の形状に一致した後、型構成部材２，３に外部から７５ｋｇｆの圧力を加え、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となったときに、型構成部材２，３への加圧を解除し型ユニット１を開き、レンズを取り出し、室温まで冷却した。更に成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、十分な精度を得ることができた。
【０１８３】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、すべての温度制御点において１０°Ｃのばらつき範囲に収まっており、また、型ユニットの開閉速度及び下型構成部材２と上型構成部材３の回転数等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなることが確認された。
【０１８４】
以上第１２乃至第１４の実施形態をまとめると、第２１の方法においては、第１の工程は、精密素子の成形形状転写時と精密素子の使用時や型ユニットの加工時の温度における精密素子と型ユニットとの熱膨張差による形状の相違量を含めた熱収縮量の補正や、成形及び冷却時の不均一な熱分布に起因する精密素子のヒケの発生位置と量を前もって成形型で補正しておく事により、成形された精密素子が所望の形状を得られるようにする事である。また、型ユニットの成形面を多孔質の材料で作り、その成形面から成形素材に向けてエアーやＮ２ガス等の流体を噴出させ、成形面表面にごく薄い流体膜を形成する事で高温の軟化状態の成形素材と成形面の接触を防ぐ事が出来る。この目的の為には、多孔質の最大穴径が２０ミクロン以下、望ましくは１０ミクロン以下で気孔率が１０〜３５％の材料からなり、材質には耐酸化性のあるアルミナや窒化珪素、炭化珪素等のセラミックや、多孔質カーボン等を用い、更に成形面の表面は、流体膜が破れ、成形素材に傷を付けないようにし、更に接触時の面精度の転写性を確保するためにも、出っ張りの無い平滑な鏡面状で、精密素子の機能を確保できる荒さに加工されている事が必要となる。
【０１８５】
次に第２の工程により、精密素子の成形素材を準備する際に、成形後の精密素子に欠陥が発生しないように、成形素材の成形後に機能面となる部分に対応する部分の表面を、滑らかに仕上げる工程であり、その部分に相当する部分の表面を光学的な欠点、つまり加圧成形する事により解消出来ない欠陥を予め取り除くことである。具体的には、表面を高低差が５ミクロン以上の鋭角的な段差が存在しないように仕上げることであり、傷や欠け等の微視的に見たときに鋭角的な部分が存在しないように処理する事である。この処理は、従来から行われている、研削研磨による方法や、酸処理などによる表面エッチングや、火炎や熱風による表面の軟化光揮処理等により行われる。
【０１８６】
更に第３の工程を実施することにより、成形素材を型ユニットの成形面と非接触の状態で加熱軟化する事が可能となるため、型ユニット上に、成形後に成形面に影響が出ることが無い、無欠陥の表面が非常に滑らかな状態の軟化した成形素材塊を得る事が出来る。この時、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度まで成形素材を加熱する事により、次の第４の工程につなげることが可能となる。
【０１８７】
次に第４の工程においても型の成形面から流体を噴出させながら型ユニットを閉じる事により、成形面と成形素材の接触を防ぐ事が可能となり、次工程での補正された形状の精密素子を得ることが容易になるような形状を有した、表面に欠陥の全く無い予備成形品を得ることが出来る。この工程に於いて得る予備成形品の形状は、次工程でのプレス時に、成形素材が大きな変形を起こさずに、変形が成形素材の流動ではなく、見かけ上、ほとんど曲げによる変形であるかのような微少な変形で事足りるような形状である事が望ましい。この為に、予備成形品の形状は、次の工程で得る補正された形状の精密素子のプレスの加圧方向の肉厚に対し、それよりも０〜３％厚くするか、又は肉厚より０．５ｍｍを超えない範囲の厚さで、また、外径も同様にほとんど同じかごく僅かに小さな形状である事が望ましく、次工程での加圧力が予備成形品全体に出来るだけ均等にかかり、変形量がどこでも出来るだけ同じとなるような、成形面と相似した形状である事が望ましい。また、このような形状にする事により、次工程での成形が実質的に曲げを主体とする変形となり、成形面を形成する多孔質の材料の穴部の微細な転写が抑制され、穴部の形状が残ら無い表面を有する精密素子を得る事が出来るようになる。更にこの工程において型ユニットを閉じる速度、タイミング、圧力、及び噴出させる流体の流量・圧力、温度等を確実に再現する事により、再現性のある安定した形状の予備成形品を得る事が出来る。これは、型ユニットを、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度範囲の時に閉じ、予備成形品の形状を得た時の流体の膜厚が２０ミクロン以下、より安定した形状の予備成形品を得る場合は、１０ミクロン以下になるように流体の圧力と流量を制御し、又、同時に型を閉じる圧力及び速度も流体の膜厚を前記の範囲内に収まるように成形素材の温度に逆比例させながら制御する事により成形素材を成形面の補正された形状にならわす事により達成される。また、この型ユニットを閉じるときの動作は成形素材の温度に対応して制御される事が望ましく、各々の動作における温度のばらつきは１０℃以下、望ましくは５℃以下とし、同様に噴出させる流体の温度も同じ範囲に収める事が望ましく、流体の流量及び圧力のばらつき及び型ユニットを閉じる速度と圧力のばらつきは５％以内、望ましくは３％以内とする事により、型ユニットの成形面の形状をより安定して転写する事が可能となる。
【０１８８】
次の第５の工程は、前記工程で得た予備成形品を型部材の成形面に接触させ、補正を施された成形面の形状を正確に予備成形品に転写し、冷却完了後の精密素子の形状を確定するために行われる物であり、予備成形品の表面が、細かな形状を転写しないような条件のもとで、プレス成形が行われる。これは、前述のような材料・材質から作られている型部材の成形面の流体の噴出孔である多孔質の穴部の形状を転写しないように、予備成形品の表面近傍の粘度が高くなった時点で、具体的には１０７．６ｄＰａ・ｓ以上の粘度となった時に、予備成形品と型部材の成形面を接触させた状態で圧力を加えて形状を修正し、補正された成形面の形状を予備成形品に転写させる事であり、この時の圧力も同様に、穴部の形状を転写しないような圧力、具体的には５ＭＰａ以下、好ましくは２ＭＰａ以下である事が望ましい。但し、この圧力は成形素材の粘度と穴部の形状が前述のような時の圧力であり、粘度が高いときや、穴部の大きさが更に細かいときには、もっと高い圧力を加えることも可能である。
【０１８９】
次の第６の工程での第１の冷却は、成形素材の粘度を制御し、型ユニットの成形面の補正された形状を成形素材に転写させ安定した形状の予備成形品を得るために行われるものであり、安定した形状の予備成形品が得られるように、成形素材の粘度と流体の膜厚を制御しながら徐々に冷却を行う。この第１の冷却完了時において、予備成形品が成形面との間に厚さを制御された流体の膜を挟んで成形される事により、次工程に必要な予備成形品の形状精度が確保される。また、この第１の冷却完了時点では、成形素材や型ユニットや流体の温度等は前述の範囲内に収めておく事が望まれる。更にその後の第２の冷却は第１の冷却より速い速度で行うことが出来、ここでの冷却は、一旦転写された補正形状が、冷却により補正前の形状、つまり精密素子の本来の所望する形状に一致し、更に連続成形において冷却収縮等によりばらつきが生じないように行われるものである。その為には、冷却開始温度や冷却時の冷却速度や温度分布等の諸条件を正確に再現する必要がある。この再現性は、上記と同様に冷却開始時から成形素材の粘度で１０12ｄＰａ・ｓを示す温度の範囲での温度のばらつきとして１０℃以下、望ましくは５℃以下とする事により安定した形状の再現性が得られる。また、この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で成形面の補正形状を決定する時に定められるものである。
【０１９０】
次の第７の工程は、形状転写後の型部材の成形面と成形素材の熱収縮量の違いによる、冷却時の形状のズレを補正する工程である。これは、通常、加圧変形できる温度状態の成形素材は粘着力があり、特に型部材の成形面が精度よく鏡面状態に仕上げられて、その面状態を転写させるような成形に於いては、この力が成形素材の表面と成形面との間に強い密着力として働く。この力は接触面の形状や接触面の界面の微細な状態に左右され易く、それ故その力の大きさは不安定であり、その分布状態も不均一である為、接触面全体が一様に剥離せずに、部分的に徐々に剥離して行ったり、段階的に剥離して行き、その結果、出来上がった面状態が不安定で、場合によっては成形された面が不連続になったりしてしまい、最終的に所望の形状と一致させる事が出来ないという問題がある。この問題は、少なくとも、型と素材の間に、転写面を変形させるような大きさの密着力が働いている間に、その素子の表面と成形面の密着を維持するように、その素子の収縮に合せて型部材を追従させる事により初めて解決させることが可能となる。
【０１９１】
更に前記の第２の冷却を、この型部材の追従の工程が完了するまで行い、その後、型ユニットを開き成形素子を取り出す事（第８の工程）により、所望の形状に近似した形状を有する成形素子を得ることが出来る。また、この第２の冷却の終了点、つまり型部材の追従工程完了時点は、密着力如何により決められる物であるが、通常、素材の粘度で１０１２〜１４．５ｄＰａ・ｓで行われるのが理想的である。
【０１９２】
次の第９の工程で、この所望の形状に近似した形状を有する成形素子を更に室温迄冷却する事により、熱収縮が起こり、前記素子が所望の形状を有する精密素子の形状となり、目的とする精密素子を得ることが出来る。
（第１５の実施形態）
次に第１の実施形態と全く同じものを成形する他の実施形態を述べる。なお、下型１１の成形面１１ａと上型２１の成形面２１ａは、第６の実施形態と全く同様にして、ただし最終的な形状転写時の温度を、ガラス素材が１０８ｄＰａ・ｓの粘度を示す温度に設定し形状を求め、加工したものを用いた。
【０１９３】
まず、第１の実施例とまったく同様の方法により、成形面１１ａ上にガラス塊１０２ａを得た。
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの成形面１１ａで受けている下面近傍の粘度が１０６〜１０７．５ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面１１ａと成形面２１ａから噴出する窒素ガスの流量を毎分２０リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂとヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が３．２ｍｍとなるまで毎秒５ｍｍの速度で型ユニット１を閉じた。次いで窒素ガスの温度と流量をガスの膜厚が２０ミクロン程度となる様に、６１０℃（ガラスの粘度で１０７．６ｄＰａ・ｓに相当する温度）と毎分１０リッターに設定し、冷間時のレンズの中心肉厚が３．０５ｍｍに相当する位置になった時に、型ユニット１を閉じ、成形面への圧力が２ＭＰａとなるように圧力を徐々に上げながら、且つ、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。
【０１９４】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に初期に１．５ＭＰａ、最終的に２ＭＰａの力が加わる様に徐々に圧力を上げて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
また、軟化ガラス塊１０２ａを得た直後から、予備成形品を得るまでの間に、成形素材への第１の冷却を開始し、予備成形品を得た直後から第２の冷却を開始した。第２の冷却は不図示の冷却装置により型ユニット１の外部より、冷却用の窒素ガスを吹きつけることにより行われ、その時において、型構成部材２，３への外部からの拘束を解き、下型部材１１及び上型部材２１がレンズの収縮に追従出来るようにした。
【０１９５】
また、第２の冷却開始後すぐに、レンズの表面近傍の粘度が１０８ｄＰａ・ｓとなった時点で、成形面１１ａ，２１ａから流体を１５ｋＰａの圧力で瞬間的に噴出させると同時に型ユニット１を僅かに開き、レンズを成形面から離型させ、その後直ちに流体の圧力を１．０２ｋＰａ、流量をそれぞれ毎分３リッターに設定し、第３の冷却を行った。
【０１９６】
第３の冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となったときに型ユニット１を完全に開き、下型部材１１からは窒素ガスを噴出させたままの状態で、レンズを不図示の吸着ハンドで取り出した。さらに成形の完了した複数のレンズを使用条件と同等の温度である２０°Ｃの温度下において精度を測定したが、全てアスがニュートンリング１．７本、クセがニュートンリング１本以下に収まり、通常の使用には十分耐えられる精度を得ることができた。
【０１９７】
なお、この複数回の成形のときの温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、温度については第２の冷却完了までの間に全ての温度制御点において２０°Ｃのばらつきの範囲、その後は３０°Ｃのばらつきの範囲に収まり、型ユニットの開閉速度等のばらつきも５％に収まっていたが、さらに条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を越えると精度が悪くなることが確認された。
【０１９８】
（第１６の実施形態）
次に第１５の実施形態と同じ装置、同じ材料を用いて片面がＲ５０ｍｍ、もう一方の面がＲ４０ｍｍを基準とする非球面形状をなす、レンズの中心肉厚が４．３ｍｍ、直径がΦ２３ｍｍである、コンパクトカメラ用の両凸のガラス非球面レンズの成形を行った。
【０１９９】
第１５の実施形態と同様に、下型部材１１の成形面１１ａと上型部材２１の成形面２１ａは、成形前にシミュレーションにより求めた数々の補正を考慮した形状に加工し、その後更に実際に成形を行い、その形状データをもとに最終的な補正を行って形状を決定した。具体的には、第１７の実施形態と同様に、上型２１の成形面２１ａの場合、図３Ａに示すように、精密素子であるレンズの標準的な使用条件である２０℃における形状２０１（Ｒ４０ｍｍを基準とする非球面形状）に対し、成形時の形状転写時の温度を、ガラスの粘度で１０１２ｄＰａ・ｓを示す温度である５１５℃に設定し、第１の補正の量の一部であるガラスの温度膨張による変形量を算出し、その結果から、この条件下における精密素子の形状２０４を求めた。次に第２の補正の量に相当する、形状転写後の冷却によるヒケ等による補正量２０５を求め、形状転写時の成形面の部分的な形状２０６を決定し、更に第１の補正の量の残りの部分に相当する、型ユニットの成形面の材料の温度収縮による補正の量から、型の冷間時、特に型の成形面の形状を加工する時の成形面の形状２０７及び２０７ａ（図３Ａにおいて２０７と２０７ａのハッチング部分の形状）を求た。そして、その形状データにより、上型部材２１の成形面２１ａを多孔質の穴部のくぼみを除いた面をニュートンリングのずれで０．２本以内となるような鏡面状態に加工し、一旦、シミュレーションで決定した成形条件で実際にレンズを成形した。次いで、この成形したレンズの形状を測定し、所定の形状と若干ずれている部分を再度補正加工して、出っ張りのない平滑な鏡面状態に仕上げ、最終的な成形面２１の形状とした。また、下型部材１１の成形面１１ａも同様の手法で形状を求め加工した。また、型部材１１、２１の材料として気孔率が２５％であり、最大穴径が６ミクロンである多孔質からなるＡｌＯ３を用い、流体にはクリーンなエアーを用いた。なお、この成形面の表面には、離型層としてカーボン膜を多孔質の孔が塞がらない様にして蒸着させた。この離型層は型とガラスの融着を防ぎ、成形面の鏡面性を失うものでなければ、特にカーボン膜に限定されるものではない。
【０２００】
次いで、このように加工準備した型部材１１、２１を図１に示す成形装置に取り付け、第１５の実施形態と全く同様にして軟化状態にあるガラス塊１０２ａを得た。
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの下型部材１１で受けている下面近傍の粘度が１０６〜１０７．５ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面１１ａ，２１ａから噴出するエアーの流量を毎分２５リッター、温度をガラスの粘度で１０６．５ｄＰａ・ｓに相当する６５０℃となるように圧力・流量調節器３２ａ，３２ｂと加熱ヒータ３３ａ，３３ｂをコントローラ４１により制御し（第１の冷却開始）、ガラス塊１０２ａの中心肉厚が４．６ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで噴出エアーの温度と流量を６００℃と毎分１５リッターに設定し、冷間時のレンズの中心肉厚が４．３２ｍｍに相当する位置になった時に、型ユニット１を閉じ、成形面への圧力が４．５ＭＰａとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．９ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。なお、このときのガスの膜厚は８ミクロン程度であった。
【０２０１】
さらに、その直後にガスの噴出を停止し、さらに型ユニット１の成形面に初期に２ＭＰａ、形状が最初に転写しおわるときに３ＭＰａの力が加わる様に徐々に圧力を上げて閉じ、予備成形品と型部材の成形面を接触させた状態で、予備成形品の形状を成形面の形状にならわせた。
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品を得た直後に第１５の実施形態と同様に第２の冷却を行った。その時において、予備成形品の形状が型の形状にならった後、型構成部材２，３に外部から第２の冷却完了時に最終的に８ＭＰａの圧力となる様に圧力を徐々に加え、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。第２の冷却開始後、レンズの表面近傍の粘度が１０１２ｄＰａ・ｓ（温度で約５１５°Ｃ）となった時点で、下型部材２と上型部材３への加圧を解除すると同時に、第１５の実施形態と同様に成形面１１ａ，２１ａから流体を噴出させ、レンズを成形面から離型させた。その後さらに流量を毎分７リッターに設定して、第３の冷却を行い、レンズの表面の温度が４９８°Ｃ（ガラスの粘度で１０１３ｄＰａ・ｓ）を下回ったときに型ユニット１を完全に開き、下型部材１１からはエアーを噴出させたままの状態で、レンズを不図示の吸着ハンドで取り出した。さらにこの成形を数回繰り返し、またこのときの温度及び加圧・減圧等のタイミングの再現性は、第２の冷却完了までは１０°Ｃ、その後は５°Ｃの温度範囲に、速度等のばらつきも３％以内に収まる様に厳密に制御しながら成形を実施した。その後、完成した複数のレンズを２０°Ｃの温度下において精度を測定したが、全てアスがニュートンリング１本、クセがニュートンリング０．５本以下に収まり、第１５の実施形態以上の良好な結果を得ることができた。
【０２０２】
（第１７の実施形態）
次に図４に示す型部材を第１５の実施形態で用いた成形装置を用いて、直径がΦ１０ｍｍ、凸面の曲率半径がＲ２０ｍｍ、凹面の曲率半径がＲ３０ｍｍ、中心部の肉厚が３．３ｍｍ、周縁部の厚さが約３．１ｍｍである凸メニスカス形状のレンズを成形した。ここで、図４において、２１１、２２１はそれぞれ下型部材と上型部材であり、それらにはレンズの光学面を形成する成形面２１１ａと２２１ａが加工されている。更に、下型部材２１１と上型部材２２１の外周にはそれぞれレンズの周縁の下部と上部を形成する成形面２１６ａと２２６ａを有したリング部材２１６,２２６が取り付けられている。また、下型部材２１１と上型部材２２１は、気孔率が１５％で最大穴径が１５ミクロン、リング部材２１６,２２６は気孔率が１０％で最大穴径が２０ミクロンの多孔質の窒化珪素で作られていて、図示せぬ供給装置からそれぞれの圧力室１２ｂ,１２ｃ,２２ｂ,２２ｃに流体を個々に独立に供給することができるようになっており、それぞれの光学面の成形面と周縁部の成形面と成形素材の間の流体の膜厚を独立に制御出来るようになっている。また、成形素材は、第６の実施形態と同じガラス材料を用い、流体としては窒素ガスを用いた。また、離型層として第１６の実施形態と同様のものを用いた。
【０２０３】
この実施形態では、レンズの光学面の成形面２１１ａ，２２１ａと周縁部の成形面２１６ａ，２２６ａの形状は、一旦レンズの冷間での形状を成形面上にそのまま加工して予備成形を行い、成形された光学素子の形状誤差を補正する様に成形面の補正加工量を求め、それを再度成形面の形状に反映して加工し直し、鏡面状態に仕上げた。また、予備成形における形状転写時の温度は５５５℃（ガラスの粘度で１０１０ｄＰａ・ｓ）として実施した。
【０２０４】
次いで、このように準備した型部材２１１，２２１，２１６，２２６を第１７の実施形態と同様に図１に示す成形装置に取り付け、同様の方法で軟化ガラス塊を得た。この時の窒素ガスの温度は、ガラスを成形面２１１ａに受ける時はガラスの転移点付近の温度である５００℃に、その直後にはガラスの粘度で１０７．３ｄＰａ・ｓに相当する温度である６２０℃になるように温度を調整し、更に窒素ガスの流量は、溶融ガラス１０２を成形面２１１ａに受ける直前までは、成形面２１１ａで毎分１８リッター、成形面２１６ａで毎分８リッター、その後はどちらも毎分５リッターとなるように制御した。
【０２０５】
次に下型構成部材２を上型構成部材３の直下に移動し、ガラス塊１０２ａの下型部材２１１で受けている下面近傍の粘度が１０５．６〜１０７ｄＰａ・ｓ、その他の表面近傍の粘度が１０３〜１０５．６ｄＰａ・ｓであり、中心付近が十分に柔らかいうちに、成形面２１１ａ，２２１ａから噴出する窒素ガスの流量を毎分２０リッター、成形面２１６ａ，２２６ａからの流量をそれぞれ毎分１４リッター、１２リッターとし、温度をガラスの粘度で１０５．８ｄＰａ・ｓに相当する６８０℃となるように設定し（第１の冷却開始）、更に下型構成部材２と上型構成部材３が互いに逆回転となるような回転方向で、回転数が２００ｒｐｍとなるように徐々に回転速度を上げながら、ガラス塊１０２ａの中心肉厚が３．５ｍｍとなるまで毎秒８ｍｍの速度で型ユニット１を閉じた。次いで、下型構成部材２と上型構成部材３の回転を保った状態で、窒素ガスの温度を６１０℃、成形面２１１ａ，２２１ａからの流量を膜厚が１２ミクロン前後となる様に毎分１５リッター、成形面２１６ａ，２２６ａからの流量がそれぞれ毎分１２リッター、１１リッターとなるように設定し、冷間時のレンズの中心肉厚が３．３３ｍｍに相当する位置になった時に、型ユニット１を閉じる圧力が成形面で２．５ＭＰａとなるように圧力を徐々に上げながら、更に同時に、レンズの表面近傍の粘度が１０７．６ｄＰａ・ｓとなるように速度を調整しながら型ユニット１を閉じ、予備成形品を得た。
【０２０６】
さらに、その直後にガスの噴出と回転を停止し、レンズの表面近傍の粘度が１０８．５ｄＰａ・ｓとなったときに、さらに型ユニットの成形面に１０ＭＰａの圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧をし、予備成形品の形状を成形面の形状にならわせた。
上記の予備成形品を得るまでの間の第１の冷却の工程に続き、予備成形品を得た直後に第１５の実施形態と同様に第２の冷却を行った。その時において、予備成形品の形状が方にならった後更に型構成部材２，３に外部から成形面に第２の冷却の完了時に最終的に７．５ＭＰａとなる様に圧力を徐々に減じて行きながら、型部材１１，２１をレンズの肉厚方向の収縮に追従させた。冷却開始後、レンズの表面近傍の粘度が１０１０ｄＰａ・ｓ（温度で約５５５°Ｃ）となったときに、成形面１１ａ，２１ａから第１７の実施形態と同様に流体を噴出させ、同時に型構成部材２，３への加圧を解除し、レンズの離型を行った。その後すぐに流体の温度を１５０°Ｃ、流量をそれぞれ毎分５リッターとし、同時に型構成部材２，３の回転を、それぞれの向きが逆方向となるような回転方向で、１５０ｒｐｍの速度で回転させ、流体の膜厚の均一化を図りながら第３の冷却を実施した。ガラスの粘度が１０１３ｄＰａ・ｓを越えたところで型構成部材２，３を停止すると同時に、型ユニット１を開き、レンズを取り出し、室温まで冷却した。更に成形の完了した複数のレンズを使用条件と同等の温度である２０℃の温度下において精度を測定したが、全てアスがニュートンリング１．２本、クセがニュートンリング０．５本以下に収まり、十分な精度を得ることができた。
【０２０７】
また、この複数回の成形の時の温度及び加圧・減圧等の動作の切り替えタイミングの再現性は、第１５の実施形態と同様の範囲に収まっており、また、型ユニットの開閉速度及び下型構成部材２と上型構成部材３の回転数等のばらつきも５％に収まっていたが、更に条件を多少振りながら成形を続けた結果、この温度や速度のばらつきの範囲を超えると精度が悪くなることが確認された。
【０２０８】
なお、これら前述の実施形態では、流体に圧縮性流体を用いているが溶融塩のような非圧縮性流体を用いても同様の効果が得られることは言うまでもない。
以上説明したように、上記の第１５乃至第１７の実施形態によれば、成形品と型の成形面との接触に起因する融着や面の転写不良及び成形面の劣化を回避することが出来、更に型の成形面と成形品の熱膨張差に起因する形状転写不良を回避することが可能となり、更に研削研磨等の加工方法により発生する、研削研磨屑等の廃棄物を極端に削減することが可能となり、光学レンズ等の精密素子を大量に安価に提供することができる。
【０２０９】
以上第１５乃至第１７の実施形態をまとめると、第２２の方法においては、第１の工程は、精密素子の成形形状転写時と精密素子の使用時や型ユニットの加工時の温度における精密素子と型ユニットとの熱膨張差による形状の相違量を含めた熱収縮量の補正や、成形及び冷却時の不均一な熱分布に起因する精密素子のヒケの発生位置と量を前もって成形型で補正しておく事により、成形された精密素子が所望の形状を得られるようにする事であり、この際に、予備成形品を得る時の成形面と予備成形品との間に存在する流体の厚さも補正しておく事も必要である。また、型ユニットの成形面を多孔質の材料で作り、その成形面から成形素材に向けてエアーやＮ２ガス等の流体を噴出させ、成形面表面にごく薄い流体膜を形成する事で高温の軟化状態の成形素材と成形面の接触を防ぐ事が出来る。この目的のためには、多孔質の最大穴径が２０ミクロン以下、望ましくは１０ミクロン以下で気孔率が１０〜３５％の材料からなり、材質には耐酸化性のあるアルミナや窒化珪素、炭化珪素等のセラミックや、多孔質カーボン等を用い、更に成形面の表面は、流体膜が破れ、成形素材に傷を付けないようにし、更に補正された形状の精密素子を得る段階での、成形面と予備型品の接触時の転写性を確保するためには、出っ張りの無い平滑な鏡面状で、精密素子の機能を確保できる所望の面精度に加工されている事が必要となる。
【０２１０】
次に第２の工程により、型と成形素材の接触、特に溶融軟化された形状が不定の状態の成形素材をノズルから流出させ型ユニットに供給する時に発生しやすい成形素材と型ユニットの成形面との接触を防ぐ事が出来、更にこの時に、一時的に噴出する流体の温度を下げたり流量を増やすことにより、接触を確実に防ぐ事が出来る。また、型ユニットの成形面上に供給された成形素材を前記ノズルから切断分離する際に、型ユニット上に成形素材を必要量を受け止めた後、型ユニットを一旦下降させ、ノズルより流出する成形素材と型ユニット上の成形素材との間にくびれを発生させ、更に成形素材の自重と表面張力によりくびれを発達させ分離を行う事により、型ユニット上に、成形後に影響がでるような欠陥の全く無い、表面が非常に滑らかな成形素材塊を得ることが出来る。
【０２１１】
次に第３の工程においても型の成形面から流体を噴出させながら型ユニットを閉じる事により、成形面と高温の成形素材の接触を防ぐことが可能となり、次工程での補正された形状の精密素子を得る事が容易になるような形状を有した、表面に欠陥の全く無い予備成形品を得ることが出来る。この工程に於いて得る予備成形品の形状は、次工程でのプレス時に、成形素材が大きな変形を起こさずに、変形が成形素材の流動ではなく、みかけ上、ほとんど曲げによる変形であるかのような微少な変形で事足りるような形状である事が望ましい。この為に、予備成形品の形状は、次の工程で得る補正された形状の精密素子のプレスの加圧方向の肉厚に対し、それよりも０〜３％厚くするか、または肉厚より０．５ｍｍを超えない範囲の厚さで、また、外径も同様にほとんど同じか極僅かに小さな形状であることが望ましく、次工程での加圧力が予備成形品全体に出来るだけ均等に掛かり、変形量がどこでもできるだけ同じとなるような、成形面と相似した形状である事が望ましい。また、このような形状にする事により、次工程での成形が実質的に曲げを主体とする変形となり、成形面を形成する多孔質の材料の穴部の微細な転写が抑制され、穴部の形状が残ら無い表面を有する精密素子を得る事が出来るようになる。更にこの工程に於いて型ユニットを閉じる速度、タイミング、圧力、及び噴出させる流体の流量・圧力、温度等を確実に再現することにより再現性のある安定した形状の予備成形品を得ること事が出来る。これは、型ユニットを、成形素材が１０３〜１０９ｄＰａ・ｓの粘度を示す温度範囲の時に閉じ、予備成形品の形状を得た時の流体の膜厚が２０ミクロン以下、より安定した形状の予備成形品を得る場合は、１０ミクロン以下になるように流体の圧力と流量を制御し、又、同時に型を閉じる圧力及び速度も流体の膜厚を前記の範囲内に収まるように成形素材の温度に逆比例させながら制御する事により成形素材を成形面の補正された形状にならわすことにより達成される。また、この型ユニットを閉じる時の動作は成形素材の温度に対応して制御されることが望ましく、各々の動作における温度のばらつきは１０℃以下、望ましくは５℃以下とし、同様に噴出させる流体の温度も同じ範囲に収めることが望ましく、流体の流量及び圧力のばらつき及び型ユニットを閉じる速度と圧力のばらつきは５％以内、望ましくは３％以内とする事により、予備成形品の形状をより安定して得る事が可能となる。。
【０２１２】
次の第４の工程は、前記工程で得た予備成形品を型部材の成形面に接触させ、補正を施された成形面の形状を正確に予備成形品に転写し、冷却完了後の精密素子の形状を確定するために行われる物であり、予備成形品の表面が、細かな形状を転写しないような条件のもとで、プレス成形が行われる。これは、前述のような材料・材質から作られている型部材の成形面の流体の噴出孔である多孔質の穴部の形状を転写しないように、予備成形品の表面近傍の粘度が高くなった時点で、具体的にはガラスの軟化温度である１０７．６ｄＰａ・ｓの粘度を示す温度以下になった時に、予備成形品と型部材の成形面を接触させた状態で圧力を加えて形状を修正し、補正された成形面の形状を予備成形品に転写させる事であり、この時の圧力も同様に、穴部の形状を転写しないような圧力、具体的には５ＭＰａ以下、好ましくは２ＭＰａ以下である事が望ましい。但し、この圧力は成形素材の粘度と穴部の形状が前述のような時の圧力であり、粘度が高い時や、穴部の大きさが更に細かい時には、もっと高い圧力を加える事も可能である。
【０２１３】
次の第５の工程は、補正された形状の成形面と密着している補正形状の精密素子を、成形面の多孔質の穴から流体を再度噴出させ、成形面から精密素子を浮上させる力を与えると同時に、必要に応じて外部からも成形面から精密素子を引き離す力を与えて離型させ、精密素子と成形面との間に空隙を設ける工程であり、この工程の目的は、一旦成形され補正された形状を有する精密素子の形状が、冷却時の型と成形素材の収縮差により劣化をするのを防ぐ為に行われるものであり、成形素材が成形面と離れても自重や他の外力により変形しにくく、かつ型と素材の収縮量の差が大きくならない温度範囲で実施される。具体的な温度範囲は、上限に対しては成形面との離型行為や次工程の非接触状態での冷却の初期に変形を起こさない粘度である、１０８ｄＰａ・ｓ以上、望ましくは１０９ｄＰａ・ｓ以上の粘度となる温度以下で行うことが必要である。又、下限の温度は、熱収縮量の差が大きくなり、成形素材が型の収縮に追従できなくなる温度以上であれば良く、成形素材と型の膨張率の差に大きく左右されるが、通常、成形素材が１０１２ｄＰａ・ｓ以下の粘性を示す温度以上であることが望ましい。また、この工程の離型動作を容易にするために、型の成形面の表面がカーボンや白金等に代表される成形素材との濡れ性の悪い材料で作られていることがよりよい結果をもたらす。
【０２１４】
次の第６の工程での第１の冷却は、成形素材の粘度を制御し、型ユニットの成形面の補正された形状を成形素材に転写させ安定した形状の予備成形品を得るために行われるものであり、第１の冷却の完了時に前述の流体の膜厚になるように、成形素材の粘度を制御しながら徐々に冷却を行う。この第１の冷却完了時において、予備成形品が成形面との間に厚さを制御された流体の膜を挟んで成形される事により、次工程に必要な予備成形品の形状精度が確保される。また、この第１の冷却完了時点では、成形素材や型ユニットや流体の温度等は前述の範囲内に収めておく事が望まれる。更にその後の第２の冷却は、一旦接触により転写された補正形状が、成形素材がほぼ固まり、離型時において形状が変化しないような前述の温度まで行われ、更に連続成形において形状のばらつきが生じないように行われるものである。その為には、冷却開始温度や冷却時の冷却速度や温度分布や、特に離型時である冷却完了時の温度及び温度分布を正確に再現する必要がある。この時の再現性は、離型時までの温度のばらつきとして２０℃以下、望ましくは１０℃以下とする事により安定した形状の再現性を得る事が可能となる。また、この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で成形面の補正形状を決定する時に定められるものである。更に、その後の第３の冷却は第１、第２の冷却より速い速度で行うことが出来、ここでの冷却は、一旦離型前までに転写された補正形状が、冷却により補正前の形状、つまり精密素子の本来の所望する形状に一致し、更に連続成形において冷却収縮によりばらつきが生じないように行われるものである。そのためには、補正形状を決定した時の第３の冷却開始温度（＝離型温度）や冷却時の温度分布などの諸条件を正確に再現する必要がある。この再現性は、上記と同様に冷却開始時から成形された精密素子が変形を発生させにくくなる粘度である１０１２ｄＰａ・ｓを示す温度、より精密な転写性を要求されるものや、複雑な形状のものに対しては成形素材が歪を新たに発生させない粘度である１０１４．５ｄＰａ・ｓ迄の温度のばらつきとして３０℃以下、望ましくは１５℃以下とする事により安定した再現性が得られる。又、この時の冷却速度や冷却時の温度分布は、成形素材に割れや、大きな複屈折等による欠陥を生じない範囲で補正形状を決定する時に定められるものであるが、転写した形状が自重や流体の圧力により変形を起こさないようにするためには、精密素子の表面を毎分２０℃以上の速度で冷却する事が望ましく、また、流体の圧力や流量にも急激な変化を与えないようにする事が望ましい。以上のような冷却を経ることで、この工程の終了時には型ユニットの成形面の形状と成形された精密素子の形状はそれぞれの膨張率の差の分の補正量や、予め見込んでおいたヒケに対する補正量のために完全に一致しないが成形面と非接触状態にあるため、精密素子の形状は型ユニットの成形面の形状に左右される事なく、所望の形状を維持できる。
【０２１５】
次の第７の工程は、第２の冷却中での形状転写時の型部材の成形面と成形素材の熱収縮量の違いによる、形状のズレを補正する工程である。これは、型部材の成形面が精度よく鏡面状態に仕上げられて、その面状態を転写させるような成形においては、型部材と成形素材とに冷却中の収縮量の違いがあると、成形した形状が冷却中に不均一に成形面に接触し、その時々の温度の型の成形面の形状を部分的に転写し、離型後の精密素子の成形面がいびつになったり、不連続な面形状になったりしてしまい、本来の所望とする面形状を得ることが出来なくなってしまうと言う事を防ぐための工程であり、この型と精密素子の接触冷却中に型の成形面を精密素子の表面に、精密素子の肉厚方向の収縮に追従する様に密着させておく事で始めて解決することが出来る。なお、この精密素子の表面への型部材の追従には、成形面と精密素子の間の密着力を利用して行っても良いが、より確実性を増し、精密素子の形状に左右されないようにするためには、型部材に外部から圧力を加える事によって行う事が望ましい。
【０２１６】
最後の第８の工程で、上記のようにすでに固化している精密素子を型ユニットから取り出すことにより、所望の形状を転写された精密素子を得る。この時も精密素子と型ユニットの成形面との間には、流体による膜が介在しているようにする事により、精密素子の表面に成形面との接触による傷などの発生を防ぐと同時に、成形面も固化した精密素子との接触による損傷を防ぐ事が出来る。
【０２１７】
また、第２３の方法においては、前記成形面の予め補正された形状を、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と多孔質の材料で作られた型部材の熱膨張率等を成形条件のパラメーターとしてシミュレーションし、事前に成形される精密素子の形状を予測し、それを基に型ユニットの成形面の形状を補正しておく事により、高精度な形状及び面精度を有する精密素子を得る事ができる。この補正は、型部材と成形素材の熱膨張差に伴う第１の補正と、成形素材の冷却に伴うヒケ等をキャンセルするための第２の補正を組み合わせたものであり、成形型の成形面の形状加工時にこの補正を行うことで、成形が完了し型ユニットより取り出し、更に冷却の完了した時点の精密素子の形状を所望の形状と一致させる事が出来る。
【０２１８】
ここで第１の補正は、形状転写時と型部材の形状加工時や精密素子の使用時の温度差、及び型部材と成形素材の熱膨張率の違いから発生する、型部材の成形面と精密素子の形状のズレ量の補正であり、具体的には、所望の精密素子の使用温度での形状を、第２の冷却の際の型部材の追従が終わる最終的な形状転写温度までの温度差による精密素子の形状変化量を成形素材の膨張率で算出し、更にその精密素子の形状変化量を最終的な形状転写温度から型ユニットの成形面の加工時の温度差までの型部材の形状変化量として型部材の膨張率で算出した量を型部材の成形面の形状の第１の補正の量とするものである。第２の補正は、特に精密素子が形状を転写した後に、型内及び型からの取り出し後の冷却による収縮やヒケ等による部分的な変形を含めた変形量の補正であり、主に冷却時に刻々と変化する流体や型ユニットの温度と成形素材の保有熱と温度伝導率に支配される、成形素材自体の温度分布とそれに伴うその時々の粘度分布と熱膨張率とそれらにより算出される応力と、成形素材独自の応力緩和係数によりヒケの量を算出し、更にその量に、その時々の成形素材の自重や流体の圧力変化等による形状の変化量を算出して加算したものを第２の補正の量とするものである。
【０２１９】
また、第２４の方法においては、予め所望する精密素子の最終形状に近似した形状を有する素子を成形し、その成形中及び成形終了後の成形、形状データから得られた情報を型部材の成形面の形状へフィードバックする事により、高精度な形状及び面精度を有する光学素子等を得る事ができる。この補正方法は、最初に精密素子の形状とほぼ同等の形状の成形面を有する型ユニットを用いて、予め設定し、固定された諸条件下で素子を一旦成形し、成形完了後の使用条件と同じ状態の素子の形状と、使用した型ユニットの成形面の形状を比較し、そこで判明した形状の相違量を、基本的には型ユニットの成形面への補正量として用い、成形条件の変更で補正出来るような単純な補正の場合は、成形条件をも修正する事により、成形した精密素子を所望の形状に一致させることが可能となる。また、この補正を数回繰り返すことにより、より精度のよい安定した形状を得る事も可能となり、更に前述のシミュレーションによる型ユニットの成形面の補正方法を組み合わせて実施する事で同様の効果を得る事が出来る。
【０２２０】
また、第２５の方法においては、前記成形面の多孔質部より噴出する流体の温度を制御する事により、成形素材の温度を制御する事ができる。これは、成形素材が型ユニットと非接触状態にある事や、成形素材が型ユニットに覆われており、外部から成形素材の温度を測定することが実質上不可能であるが、成形素材に直接に接触する流体の温度を制御し、その伝熱により成形素材の温度を間接的に制御する事で解決され、また、こうする事により、成形素材に対して、より応答性の良い確実な温度制御を行うことが出来る。ここで、流体の温度の制御方法としては、流体を供給源の近傍で直接に加熱温調して用いる事でも十分に目的を達成することが出来るが、一旦前述の様に加熱温調した流体を更に流体が成形素材に触れる直前の流体の通路である型ユニット等に組み込まれたヒーター等の加熱源により、再度温調をかけ直して用いることで、より良好な成形素材への温度制御を実現することが可能となる。
【０２２１】
また、第２６の方法においては、成形素材の粘度に合わせ成形型の成形面より噴出させる流体の噴出圧力と流体の流量と、型ユニットへの加圧力を制御する事により、高精度な形状及び面精度を有する光学素子を得る事ができる。ここで、成形素材の硬さに相当する粘度変化に同調させて、流体の流量や圧力と型ユニットへの加圧力を制御する事により、型ユニットの成形面と成形素材の間の流体の膜厚を確実に安定させて制御する事が出来、その結果、予備成形品及びその後の完成した精密素子が、より一層、高精度で、かつ連続成形時においてもばらつきの少ない安定した形状を得る事が可能となる。
【０２２２】
また、第２７の方法においては、成形面の形状に近似した形状を有する予備成形品を得る際及び形状転写後の型内での冷却の際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力分布を制御する事により、高精度な形状及び面精度を有する光学素子等を得る事が出来る。これは、加圧成形中に型部材を成形素材に対して回転摺動させる事により、成形素材と型部材の成形面との間の流体の膜厚を均一化する事が容易となり、より高精度な精密素子を得る事が出来るようになり、特に回転軸を中心とした軸対象に膜厚が容易に均一化する事により、レンズ等の機能面が軸対称の形状の球面を基本とする形状の精密素子に対しては大きな効果を発揮する事が可能となる。
【０２２３】
（第１８の実施形態）
図６は本発明の第１８の実施形態の成形方法を示すための型構造の図である。符号３０１は上型の第１型部材、符号３０２は下型の第１部材、符号３０３は上型の第２型部材、符号３０４は下型の第２型部材、符号３０５は第２型部材３０３を固定するためのリング、符号３０６は第２型部材３０４を固定するためのリング、符号３０７，３０８はガスの通路、符号３０９は成形品を示す。
【０２２４】
図７は成形品を芯取りして得た光学素子３１０を示す。
レンズ成形用素材としてＳＫ１２（ｎｄ＝１．５８３１３，νｄ＝５９．４，Ｔｇ＝５０６℃，Ａｔ＝５３８℃）を用い、これによってプリフォームとして直径１２ｍｍ、中心厚７ｍｍのゴブ（ガラス塊）を作成した。
この素材からＲ１＝１６．４５ｍｍ、Ｒ２＝１６．８６ｍｍ、中心厚＝４．５ｍｍ、光線有効径＝Φ１２ｍｍ、外径＝Φ１４ｍｍの両凸レンズを作成する。
【０２２５】
図６に示す型の製造方法としては超硬合金よりなる型部材３０１，３０２に放電加工でガスの通路３０７、３０８を形成した。さらに多孔質アルミナ、多孔質ジルコニア、多孔質炭化珪素、多孔質ステンレス、多孔質炭素等からなる型部材３０３，３０４をレンズ面以外を加工して、型部材３０１，３０２に嵌合挿入した。さらに固定用のリング３０５，３０６を挿入し不図示の固定ピンで型部材同士を固定した。最後にレンズ面を研削研磨加工して仕上げた。
【０２２６】
第２部材３０３，３０４の内径はΦ１２．２ｍｍで光学素子の光線有効径よりわずかに大きくした。
Ｎ２雰囲気下の成形装置内のプレス軸に上記型を取付け、上下型間にガラス素材を投入し、型とガラスを加熱して５８０℃に加熱した。つぎに上型を下降させてプレスを開始した。型部材３０１，３０２によってガラスが変形を開始した後にＮ２ガスを型部材３０３，３０４に流し込み、上下型の隙間から成形室内に放出するようにした。Ｎ２ガスは通路３０７，３０８に入る前に不図示のヒータにより型温度と同等に加熱する。またガスの流量は不図示の流量調整器で制御する。
【０２２７】
変形が完了した後、型温度とガス温度を同等に保ちながら冷却し、２００℃まで冷却したところで上型を上昇させて型とガラスを離型した。取り出した成形品の外観を顕微鏡で観察したところ第１の型部材に対応する部分は微細な型の表面あらさを転写していたが、第２の型部材に対応する部分は型の接触痕が全くなく滑らかな状態であって型とガラスが非接触の状態で形成されたことがわかった。成形品を芯取り加工して光学素子３１０を得た。得られた光学素子は光線有効径内は設計値に対しニュートンリング０．５本の精度を有していた。また光線有効径外は所定の曲面からのズレは５μｍ前後であったが、機械的な精度としては十分な値であった。
【０２２８】
上記プロセスを５００ショット連続で行いその結果を図８にまとめた。
型部材３０３，３０４の材質および気孔率、ガス流量に関して各種条件で５００ショットおこなったが全て外観品質は融着が無く、形状精度に関しても良好な結果を得られた。
（第１９の実施形態）
第１８の実施形態と同じ装置、型、ガラスを使用して同様のプロセスで両凸レンズを形成した。第１８の実施形態では離型温度は２００℃としたが、ここでは離型温度５００℃にして成形時間を短縮することを目的とした。相違点としては変形が完了した後は上型の第２型部材に供給するガスの温度だけを低下させて第２型部材から放出されるガスの温度が、下型の第２型部材から放出されるガスの温度より１０℃低く保たれるように、ガスの温度を制御した。型温度が５００℃まで低下した時点で上型を上昇させて型とガラスを離型した。成形品は下型上に残っていたので直ちにオートハンドで取り出すことができた。その結果連続的に成形を５００ショット繰り返すことが出来た。このことは、低い温度で離型させる場合には問題はないがＴｇ点近くのような高い温度で離型させる場合には、上下のガスの温度差を持たせることで成形品が必ず下型に残るように制御できることを示している。
【０２２９】
上型と下型のガスの温度差を変えて連続成形ができるかどうかを調べた。比較例として温度差が無いかまたは少ない場合には離型した時に成形品が上型に付着した状態になることがありその後のオートハンドによる取り出しに支障を生じ、連続成形ができなかった。ガスの温度差と離型性の関係を図９に示す。
（第２０の実施形態）
図１０は第２０の実施形態の成形方法を示すための型構造の図である。符号３１１は上型の第１型部材、符号３１２は上型の第２型部材、符号３１３は下型、符号３１４はガスの通路、符号３１５は成形品を示す。
【０２３０】
図１１は成形品を芯取りして出来た光学素子３１６を示す。
レンズ成形用素材としてＬａＫ１２（ｎｄ＝１．６７７９０，νｄ＝５４．９，Ｔｇ＝５６２℃，Ａｔ＝５９３℃）が用いられ、これによってプリフォームとして直径２３ｍｍ、中心厚１２ｍｍのゴブ（ガラス塊）を作成した。
この素材からＲ１（凹）＝１４．２３２ｍｍ（非球面）、Ｒ２（凸）＝１５５．３ｍｍ、中心厚＝１．５ｍｍ、外径＝Φ２９ｍｍ、Ｒ１の光線有効径＝Φ２０ｍｍ、Ｒ２の光線有効径＝Φ２７ｍｍでＲ１側に４５度の面取りをした凹メニスカスレンズを作成する。
【０２３１】
図１０に示す型の製造方法は超硬合金からなる型部材３１１に放電加工でガスの通路３１４を形成した。さらにモリブデンよりなる型部材３１２を型部材３１１にネジ止めした。第１型部材の非球面加工部分の外径は２３ｍｍで、第２型部材の内径は２４ｍｍとしガスが通過することを目的として型部材３１１と型部材３１２の隙間は幅０．５ｍｍとした。第２型部材のレンズ成形面は４５度のテーパー面とした。
【０２３２】
Ｎ２雰囲気下の成形装置内のプレス軸に上記型を取り付け、上下型間にガラス素材を投入し、型とガラスを加熱して６２５℃に加熱した。次に上型を下降させてプレスを開始した。型部材３１１，３１３によってガラスが変形を開始した後にＮ２ガスをガス通路３１４に流し込み型部材３１１と３１２の隙間から成形室内に放出するようにした。Ｎ２ガスの温度は通路３１４に入る前に不図示のヒータにより型温度と同等に加熱している。またガスの流量は不図示の流量調整器で制御する。
【０２３３】
変形が完了した後、型温度とガラス温度を同等に保ちながら冷却し、２００℃まで冷却した所で上型を上昇させて型とガラスを離型した。取り出した成形品の外観は融着などの欠陥が無く、凹面側はΦ２２の範囲で上型３１１と接触しており、Φ２４．５からΦ３０までは型部材３１２によって４５度のテーパー面が形成されていた。また、Φ２２からΦ２４．５の間は完全な自由表面であった。成形品を芯取り加工して光学素子３１６を得た。得られた光学素子は設計値に対し凹面側（非球面）は０．３μｍのずれ、凸面側（球面）はニュートンリング０．５本の精度を有していた。外周部の４５度のテーパー面は設計値からのズレが３μｍ前後で機械的な精度としては十分な数値であった。
【０２３４】
上記プロセスをガスの流量を変えてそれぞれ５００ショット行いその結果を図１２にまとめた。全て外観品質は融着が無く、形状精度に関しても良好な結果を得られた。比較のためにガスを流さずに成形を行ったが２０ショットで第２型部材３１２にガラスが融着し成形が不可能となった。
（第２１の実施形態）
図１３は第２１の実施形態の成形方法を示すための型構造の図である。符号３１７は上型、符号３１８は下型の第１型部材、符号３１９は下型の第２型部材、符号３２０は固定用のリング、符号３２１はガスの通路、符号３２２は成形品を示す。図１４は成形された光学素子３２３を示す。光学素子３２３は芯取り加工をせず、成形されたままの状態で鏡筒に組み込むことが出来た。
【０２３５】
レンズ形成用素材としてＬａＦ０１０（ｎｄ＝１．７３３１０，νｄ＝４９．４，Ｔｇ＝５７１℃，Ａｔ＝６００℃）を用い、これによってプリフォームとして直径１０．６ｍｍの球を作成した。
上記素材からＲ１＝１８．５ｍｍ、Ｒ２＝１６．４ｍｍ、中心厚＝５ｍｍ、光線有効径＝Φ１２ｍｍ、Ｒ２両側の外径がΦ１３ｍｍに規定された両凸レンズを作成する。
【０２３６】
図１３に示す型の製造方法としては超硬合金からなる型部材３１８に放電加工でガスの通路３２１を形成した。さらに球面研磨をした後に炭素膜をコーティングした。さらに多孔質炭素よりなる型部材３１９を型部材３１８に嵌合挿入した。さらに固定用のリング３２０を挿入し、不図示の固定ピンで型部材同士を固定した。第２型部材３１９の内径はΦ１３で、成形品の芯取り加工を不要にした。
【０２３７】
Ｎ２雰囲気下の成形装置内のプレス軸に上記型を取り付け、上下型間にガラス素材を投入し、型とガラスを加熱して６４０℃に加熱した。次に上型を下降させてプレスを開始した。型部材３１７，３１８によってガラスが変形を開始した後にＮ２ガスをガス通路３２１に流し込み型部材３１７と３１９の隙間から成形室内に放出するようにした。Ｎ２ガスの温度は通路３２１に入る前に不図示のヒータにより型温度と同等に加熱する。
【０２３８】
変形が完了した後、型温度とガラス温度を同等に保ちながら冷却し、２００℃まで冷却した所で上型を上昇させて型とガラスを離型した。取り出した成形品の外観を顕微鏡で観察したところ第１の型部材に対応する部分は微細な型の表面あらさを転写していたが、第２の型部材に対応する部分は型の接触痕が全くなく滑らかな状態であって型とガラスが非接触の状態で形成されたことがわかった。得られた光学素子は光線有効径内は両面とも設計値に対しニュートンリング０．５本の精度を有していた。またＲ２面側の外径Φ１３は所定の数値からのズレが２μｍ前後で、芯取りをしないで使用できるレベルであった。
【０２３９】
上記プロセスを５００ショット行ったが品質上の問題は発生せず連続で成形することが可能であった。
比較として第２の型部材３１９の材質を、超硬合金で作成し、炭素膜をコーティングした材料を使用したが、５０ショット成形したところで型部材３１９の水平面の部分の炭素膜が剥離し、更に成形を続けたところその部分から融着が発生した。
【０２４０】
（第２２の実施形態）
図１５は第２２の実施形態の成形方法を示すための型構造の図である。符号３２４は上型、符号３２５は下型、符号３２６は胴型、符号３２７は外径を形成するための第２型部材、符号３２８はガスの通路、符号３２９は成形品を示す。
図１６は得られた光学素子３３０を示す。
【０２４１】
レンズ成形用素材として第２２の実施形態と同じくＳＫ１２を用い、これによってプリフォームとして直径１２ｍｍ、中心厚６．３ｍｍのゴブ（ガラス塊）を作成した。上記素材からＲ１＝１６．４５ｍｍ、Ｒ２＝１６．８６ｍｍ、中心厚４．５ｍｍ、光線有効径＝Φ１２ｍｍ、外径＝Φ１４ｍｍの両凸レンズを作成する。
【０２４２】
図１５に示す型の製造方法としては超硬合金からなる型部材３２４，３２５を研磨した後、炭素膜をコーティングした。さらに多孔質炭素からなる第２型部材３２７を胴型３２６に嵌合させた。型部材３２４，３２５と胴型３２６の隙間は１０μｍで、ガスの逃げ道を確保しつつ、型部材３２４，３２５の偏心を防止する量とした。
【０２４３】
Ｎ２雰囲気下の成形装置内のプレス軸に上記型を取り付け、上下型間にガラス素材を投入し、型とガラスを加熱して５８０℃に加熱した。つぎに上型を下降させてプレスを開始した。型部材３２４，３２５によってガラスが変形を開始した後にＮ２ガスを型部材３２７に流し込み、上下型と胴型の隙間から成形室内に放出するようにした。Ｎ２ガスの温度は通路３２８に入る前に不図示のヒータにより型温度と同等に加熱する。またガスの流量は不図示の流量調整器で制御する。
【０２４４】
変形が完了した後、型温度とガス温度を同等に保ちながら冷却し、２００℃まで冷却したところで上型を上昇させて型とガラスを離型した。取り出した成形品の外観を顕微鏡で観察したところ球面部分は微細な型の表面あらさを転写していたが、外径部分は型の接触痕が全くなく滑らかな状態であって、型とガラスが非接触の状態で成形されたことがわかった。得られた光学素子は光線有効径内は設計値に対しニュートンリング０．５本以下の精度を有していた。又外径は設計値からのズレが５μｍで、機械的な精度としては十分な値であった。
【０２４５】
上記プロセスを５００ショット行ったが品質上の問題は発生せず、連続で成形することが可能であった。
比較として第２型部材３２７の材質を超硬合金で作成し、炭素膜をコーティングした材料を使用したが、第２型部材３２７と上下型３２４，３２５の隙間にガラスが入り込み、その結果上下型を胴型から抜き出すことができなくなった。
【０２４６】
上記結果から第２型部材からガスを流すことによって、上下型と胴型の隙間にガラスが入り込むことを防止できることがわかった。
以上説明したように、重量調整されたガラス素材を成形用型でプレスして光学素子を成形する方法において使用する型が、光学素子の少なくとも光線有効径内を形成するための第１の型部材とそれ以外の部分を形成するための第２の型部材で構成され、第２の型部材に形成されている通路の内部、または表面を経由してガスを成形面に流しながら成形することによって、とくに融着や膜剥離の発生しやすいレンズ周辺部で、型とガラスを非接触の状態で成形することができ、その結果、融着などのトラブルが無く連続的に成形を行うことができるようになる。
【０２４７】
さらに上下型でガスの温度差をつけることによって離型した時に安定的に成形品を下型上に残してハンドリングのトラブルを防止できる。
また、外径形成部材として多孔質材を使えば型の隙間にガラスが入り込まない状態で芯取りの必要のない光学素子を得ることが出来る。
上記の第１８乃至第２２の実施形態をまとめると、第２８の方法において、光学素子周辺部に融着や型の膜剥離が発生しやすいことに注目し、周辺部に於いて型とガラスの密着力をゼロにするために非接触の状態で成形する方法を提案している。ただし光線有効系内は光学的精度を達成するために型とガラスは接触させ、光線有効径外は鏡筒などとの組み合わせ上必要な機械的精度は必要だが光学的精度は不要であるため型とガラスは非接触とした。ここで言う光学的精度とは０．５μｍ程度以下の形状誤差を言い、機械的精度とは１０μｍ程度の形状誤差を言う。
【０２４８】
具体的な方法としては、重量調整されたガラス素材を成型用型でプレスして光学素子を成形する方法に於いて使用する型が、光学素子の少なくとも光線有効径内を形成するための第１の型部材と、それ以外の部分を形成するために第２の型部材で構成され、第２の型部材の内部または表面を経由してガスを成形面に流しながら成形することによって上記目的を達成した。また第２の型部材と成形された光学素子はガス層を介して非接触であることによって上記目的をより確実に達成できた。
【０２４９】
第２の型部材の表面にガス層を形成するためには型形状を工夫してガスの通過する隙間を形成し型表面にガスを放出するような構造にしても良いが、より好ましくは第２の型部材を多孔質セラミックまたは、多孔質金属または、多孔質炭素で作成することである。このような多孔質材料を使用することにより第２の型部材の表面全域に於いて均等にガスが放出されるので非接触状態で機械的精度を出すことが容易になる。
【０２５０】
また付随する目的として上型を構成する第２の型部材を経由するガスの温度と、下型を構成する第２の型部材を経由するガスの温度の差を１０℃以上にすることによって離型する時に上面、下面のどちらを先に離型させるかを制御することもできる。これにより離型後光学素子を必ず下型上に残したいような装置構造に於いても、トラブルの発生を防止できる。
【０２５１】
上記の第１８乃至第２２の実施形態で得られる光学素子は、少なくとも光線有効径内は型と接触した面でありかつそれ以外の表面に非接触状態で型によって形状を形成された部分を持つ。光線有効径内は型と接触することで光学的精度（形状誤差０．５μｍ以下程度）で成形することが出来、光線有効径外は型と非接触であるが機械的精度（形状誤差１０μｍ以下程度）を維持することで鏡筒への組立が可能である。また光線有効径外は全ての部分が機械的精度を必要とするわけではなく、全く型から拘束を受けない自由表面が存在しても差し支えない。
（第２３の実施形態）
第２３の実施形態では、光学素子成形用素材として適したガラス塊を、溶融ガラス流から得る方法について説明する。
【０２５２】
図１７は、本発明の第２３の実施形態であるガラス塊の製造において用いた、受け型の構成を説明する図である。
図１７において、４０１は溶融ガラス流出パイプ、４０２は溶融ガラス流、４０３は多孔質の受け型、４０４は多孔質の受け型４０３を保持している受け型保持ブロック、４０５は多孔質の受け型４０３の背面に位置し型保持ブロック４０４により囲まれているガス供給室、４０６はガス供給室４０５に低温のガスを供給するための低温ガス供給管、４０７はガス供給室４０５に高温のガスを供給するための高温ガス供給管、４０８は高温ガス供給管４０７の内部に設けられたガス加熱用の白金巻線ヒータ、４０９は低温ガス供給管４０６および高温ガス供給管４０７の途中に設けられたガス流量調整バルブである。
【０２５３】
図１８乃至図２１は、第２３の実施形態である溶融ガラス塊の製造工程を、順次説明する図である。これらの図を用いて、本実施形態における動作を説明する。
ガラス溶融るつぼ（図示せず）の内部で溶融されたガラスは、ガラス溶融るつぼの下部に設置された溶融ガラス流出パイプ４０１を通って流出してくる。
【０２５４】
溶融ガラス流を受け型に受ける工程の初期段階において、図１８に示すように、溶融ガラス流４０２の先端は、多孔質の受け型４０３の上方の位置にある。この時、低温ガス供給管４０６および高温ガス供給管４０７のガス流量調整バルブ４０９は開かれており、低温ガス供給管４０６から低温ガスが、高温ガス供給管４０７からは高温ガスが、ガス供給室４０５の内部に供給され、混合されている。そして、この混合された温度のガスが、多孔質の受け型４０３の細孔を通って、受け型４０３の受け面に噴出している。
【０２５５】
更に、溶融ガラス流４０２の流出が進み、溶融ガラス流４０２の先端部の下降が進むと、図１９に示すように、溶融ガラス流４０２の先端部が多孔質の受け型４０３の受け面に接近した状態になる。しかし、この時、多孔質の受け型４０３の受け面からは混合された温度のガスが噴出しているので、溶融ガラス流４０２の先端部と多孔質の受け型４０３とが接触することは無い。なお、この時も、低温ガス供給管４０６と高温ガス供給管４０７の両方からガスが供給されている。
【０２５６】
さらに溶融ガラス流４０２の流出が進むと、図２０に示すように、溶融ガラス流４０２が多孔質の受け型４０３の上に溜り始める。この状態で、低温ガス供給管４０６に設けたガス流量調整バルブ４０９を閉じ始める。すると、ガス供給室４０５に供給される低温ガスの量が減り始めるので、ガス供給室４０５で混合されたガスの温度は上がり始め、多孔質の受け型４０３の受け面から噴出しているガスの温度も上がり始める。
【０２５７】
そして、低温ガス供給管４０６のガス流量調整バルブ４０９を閉じ、受け型４０３の上に溜った溶融ガラスの重量が所望の値になった後、受け型４０３を下方へ下降させ、溶融ガラスを括れさせ、自然切断させ、溶融ガラス塊４１０を得る。この状態を図２１に示す。この時、低温ガス供給管４０６は閉じられており、高温ガス供給管４０７から高温のガスがガス供給室４０５に供給されている。そして、多孔質の受け型４０３の受け面から噴出している高温のガスにより溶融ガラス塊４１０は浮上している。
【０２５８】
このようにして得られたガラス塊４１０は、常に受け型４０３から浮上した状態であるので、その上下面とも自由表面からなっており、非常に滑らかである。また、ガラス塊４１０には、受け型４０３との接触痕もない。更に、ガラス塊の製造工程に最適な温度条件のガスで、ガラス塊４１０を浮上させているので、ガラス塊の下面が噴出ガスにより持ち上げられ凹んだ状態で固化することは無く、このようにして得られたガラス塊４１０の下面は、受け型４０３の形状にほぼ倣った形をしている。
【０２５９】
すなわち、このようにして得られたガラス塊４１０は、外観・形状ともに優れており、光学素子成形用素材として大変適している。
次に、本実施形態のより具体的な実施例について、具体的に述べる。
白金製のガラス溶融るつぼ（図示せず）の中で溶融された光学ガラスは、溶融るつぼの下部に接続された白金製の溶融ガラス流出パイプ４０１を通って、液滴状に流出している。この流出されている溶融ガラス流４０２の温度は１０００℃である。
【０２６０】
受け型４０３は、多孔質のカーボンからなっており、この気孔率は３０％であり、平均孔径１５μｍの細孔が開いている。この多孔質の受け型４０３の受け面は、半径１５ｍｍの球面に加工されている。受け型４０３の下部および側面は、ステンレス製の受け型保持部材４０４で囲まれている。そして、受け型４０３の下面と受け型保持部材４０４の間には、ガス供給室４０５となる空間部が設けられている。
【０２６１】
そして、このガス供給室４０５には、低温ガス供給管４０６と高温ガス供給管４０７の２種類のガス供給管が、受け型保持部材４０４を通って接続されている。低温ガス供給管４０６はステンレスのパイプからなっており、この低温ガス供給管４０６を通って、室温の窒素ガスがガス供給室４０５に供給される。高温ガス供給管４０７は、ステンレスのパイプの中に白金製の巻線ヒータ４０８が設置されており、このステンレスのパイプと白金巻線ヒータ４０８の間には、絶縁のため石英ガラスのパイプ（図示せず）が設置されている。この高温ガス供給管４０７の中に室温の窒素ガスを供給すると、この高温ガス供給管４０７の中を通過する間に、窒素ガスは加熱された白金巻線ヒータ４０８により加熱され、高温のガスがガス供給室４０５の中に供給される。
【０２６２】
本実施形態において、低温ガス供給管４０６はガス供給室４０５の中心部に１本設置されており、高温ガス供給管４０７は、低温ガス供給管４０６の回りに円周上に６本設置されている。
ガス流量調整バルブ４０９は、低温ガス供給管４０６および６本の高温ガス供給管４０７の全てに設けられている。このガス流量調整バルブ４０９により、ガス流量を予め設定された値から流量０まで連続的に制御することが可能である。本実施形態においては、低温ガス供給管４０６では最大５リットル／分の流量の窒素ガスを流すことができ、また、高温ガス供給管４０７では、各１本につき、最大１リットル／分の流量の５００℃の温度の高温の窒素ガスを流すことができるように、ガス流量調整バルブ４０９は設定されている。
【０２６３】
そして、受け型４０３と一体になっている受け型保持部材４０４と低温ガス供給管４０６と高温ガス供給管４０７は、上下に位置制御可能な上下駆動装置（図示せず）に連結されており、上下動できるようになっている。
次に、この装置を使ってガラス塊４１０を得る工程の具体的な様子を、図１８乃至図２１を用いて説明する。
【０２６４】
図１８は、溶融ガラス流４０２を受け型４０３に受け始める直前の様子を示している。この時、受け型４０３は、溶融ガラス流出パイプ４０１の出口の下方１０ｍｍの位置まで上昇し停止している。この時、低温ガス供給管４０６および６本の高温ガス供給管４０７のガス流量調整バルブ４０９は、全て全開になっている。従って、低温ガス供給管４０６から５リットル／分の流量の室温の窒素ガスが、６本の高温ガス供給管４０７から合計６リットル／分の流量の５００℃の窒素ガスが、ガス供給室４０５の中に供給されている。この低温ガスと高温ガスはガス供給室４０５の中で混合され、このガスは多孔質の受け型４０３の細孔を通って受け面に噴出している。この時、受け面から噴出しているガスの温度は、３００℃であった。なお、本実施形態では、受け型保持部材４０４の中には加熱用のヒータは設置されていない。
【０２６５】
図１９は、溶融ガラス流４０２がさらに流出した時の様子を示している。この時、溶融ガラス４０２の先端部は、多孔質の受け型４０３の受け面に近接しているが、受け面からガスが噴出しているので、溶融ガラス流４０２の先端部と多孔質の受け型４０３の受け面とが接触することは無い。なお、この時も、低温ガス供給管４０６および６本の高温ガス供給管４０７のガス流量調整バルブ４０９は、全て全開になっている。なお、図１９はゴブ受け開始、すなわち、図１８の状態から、１秒後の様子を示している。
【０２６６】
図２０は、溶融ガラス流４０２がさらに流出し、溶融ガラスが受け型４０３の上に溜まっている状態の様子を示している。この時、低温ガス供給管４０７のガス流量調整バルブ４０９を連続的に閉じつつある。ガス流量バルブ４０９を閉じ始めたのは、ゴブ受け開始後２秒後からであり、その後３秒かけて、ガス流量バルブ４０９を連続的に徐々に閉じた。更に、ゴブ受け開始後７秒後に、受け型４０３の上に溜まった溶融ガラスの重量が所望の値になったので、受け型４０３を下方へ５ｍｍ下降させ、その状態で１秒保持する間に、溶融ガラス流を括れさせ、さらに自然切断し、溶融ガラス塊４１０を得た。
【０２６７】
この時、ガス供給室４０５には高温ガス供給管から高温のガスが供給されており、この高温のガスが受け型４０３から噴出しており、このガスによりガラス塊４１０は浮上保持されている。この状態を図２１に示す。この時、受け型４０３の受け面から噴出しているガスの温度は４００℃であった、このようにして得られたガラス塊４１０は、その重量が２．５ｇであり、その下面に凹み等は無く、上下面とも滑らかな自由表面からなっており、受け型４０３との接触痕等は無いので、光学素子成形用素材として大変適している。
【０２６８】
本実施形態特有の効果として、外観・形状ともに優れており、光学素子成形用素材として大変適しているガラス塊を、溶融ガラス流から得るための最適な成形条件を、ガス温度、ガス流量、低温ガス流停止タイミングの組み合わせから、容易に求めることができる点がある。従って、所望とするガラス塊の大きさや形状、また、ガラスの種類が異なった場合も、その最適成形条件を、容易に素早く求めることができる。
【０２６９】
（第２４の実施形態）
第２４の実施形態では、光学素子成形用素材として適したガラス塊を、溶融ガラス流から得る方法について説明する。
図２２は、本発明の第２４の実施形態であるガラス塊の製造において用いた、受け型の構成を説明する図である。
【０２７０】
図２２において、４０１は溶融ガラス流出パイプ、４０２は溶融ガラス流、４０３は多孔質の受け型、４０４は多孔質の受け型４０３を保持している受け型保持ブロック、４０６は低温のガスを供給するための低温ガス供給管、４０７は高温のガスを供給するための高温ガス供給管、４０８は高温ガス供給管４０７の内部に設けられたガス加熱用の白金巻線ヒータ、４０９は低温ガス供給管４０６および高温ガス供給管４０７の途中に設けられたガス流量調整バルブである。また４１１は多孔質の受け型４０３の背面に位置し型保持ブロック４０４により囲まれているガス供給室を中心部分と外周部分との２つの空間に分割するための隔壁であり、４１２は隔壁４１１により分割された中心部ガス供給室であり、４１３は隔壁４１１により分割された外周部ガス供給室である。中心部ガス供給室４１２には、低温ガス供給管４０６と高温ガス供給管４０７が接続されている。また、外周部ガス供給室４１３には、高温ガス供給管４０７が接続されている。
【０２７１】
図２３乃至図２６は、本第２４の実施形態である溶融ガラス塊の製造工程を、順次説明する図である。これらの図を用いて、本実施形態における動作を説明する。
ガラス溶融るつぼ（図示せず）の内部で溶融されたガラスは、ガラス溶融るつぼの下部に設置された溶融ガラス流出パイプ１を通って流出してくる。
【０２７２】
溶融ガラス流を受け型に受ける工程の初期段階において、図２３に示すように、溶融ガラス流４０２の先端は、多孔質の受け型４０３の上方の位置にある。この時、中心部ガス供給室４１２に接続された低温ガス供給管４０６のガス流量調整バルブ４０９は開かれており、高温ガス供給管４０７のガス流量調整バルブ４０９は閉められている。また、外周部ガス供給室４１３に接続された高温ガス供給管４０７のガス流量調整バルブ４０９も開かれている。従って、中心部ガス供給室４１２には低温のガスが供給され、外周部ガス供給室４１３には高温のガスが供給され、これらのガスが、多孔質の受け型４０３の細孔を通って、受け型４０３の受け面に噴出している。その結果、受け型４０３の受け面の中心部からは低温のガスが噴出しており、外周部からは高温のガスが噴出している。
【０２７３】
更に、溶融ガラス流４０２の流出が進み、溶融ガラス流４０２の先端部の下降が進むと、図２４に示すように、溶融ガラス流４０２の先端部が多孔質の受け型４０３の受け面に接近した状態になる。しかし、この時、多孔質の受け型４０３の受け面からガスが噴出しているので、溶融ガラス流４０２の先端部と多孔質の受け型４０３とが接触することは無い。なお、この時、中心部ガス供給室４１２に接続された低温ガス供給管４０６とガス流量調整バルブ４０９を閉じ始め、反対に、高温ガス供給管４０７のガス流量調整バルブ４０９を開け始めている。
【０２７４】
さらに溶融ガラス流４０２の流出が進むと、図２５に示すように、溶融ガラス流４０２が多孔質の受け型４０３の上に溜り始める。この状態で、中心部ガス供給室４１２に接続された低温ガス供給管４０６のガス流量調整バルブ４０９は閉じられ、逆に、高温ガス供給管４０７のガス流量調整バルブ４０９が開けられている。すると、中心部ガス供給室４１２に供給されるガスの温度は上がるので、多孔質の受け型４０３の受け面の中心部から噴出しているガスの温度が上がる。
【０２７５】
そして、受け型４０３の上に溜った溶融ガラスの重量が所望の値になった後、受け型４０３を下方へ下降させ、溶融ガラスを括れさせ、自然切断させ、溶融ガラス塊４１０を得る。この状態を図２６に示す。この時、多孔質の受け型４０３の受け面から噴出している高温のガスにより溶融ガラス塊４１０は浮上している。
【０２７６】
このようにして得られたガラス塊４１０は、常に受け型４０３から浮上した状態であるので、その上下面とも自由表面からなっており、非常に滑らかである。また、ガラス塊４１０には、受け型４０３との接触痕もない。更に、ガラス塊の製造工程に最適な温度条件のガスで、ガラス塊４１０を浮上させているので、ガラス塊の下面が噴出ガスにより持ち上げられ凹んだ状態で固化することは無く、このようにして得られたガラス塊４１０の下面は、受け型４０３の形状にほぼ倣った形をしている。
【０２７７】
すなわち、このようにして得られたガラス塊４１０は、外観・形状ともに優れており、光学素子成形用素材として大変適している。
次に、本実施形態のより具体的な実施形態について、具体的に述べる。
白金製のガラス溶融るつぼ（図示せず）の中で溶融された光学ガラスは、溶融るつぼの下部に接続された白金製の溶融ガラス流出パイプ４０１を通って、液滴状に流出している。この流出されている溶融ガラス流４０２の温度は１０００℃である。
【０２７８】
受け型４０３は、多孔質のカーボンからなっており、この気孔率は３０％であり、平均孔径１５μｍの細孔が開いている。この多孔質の受け型４０３の受け面は、半径１５ｍｍの球面に加工されている。受け型４０３の下部および側面は、ステンレス製の受け型保持部材４０４で囲まれている。そして、受け型４０３の下面と受け型保持部材４０４の間には、ガス供給室４０５となる空間部が設けられている。
【０２７９】
このガス供給室は、その内部に設けられたステンレス製の円筒状の隔壁４１１により中心部ガス供給室４１２と外周部ガス供給室４１３の２つに分割されている。
中心部ガス供給室４１２には、低温ガス供給管４０６と高温ガス供給管４０７の２種類のガス供給管が接続されている。また、外周部ガス供給室４１３には、高温ガス供給管４０７が接続されている。低温ガス供給管４０６はステンレスのパイプからなっており、この低温ガス供給管４０６を通って、室温の窒素ガスがガス供給室に供給される。高温ガス供給管４０７は、ステンレスのパイプの中に白金製の巻線ヒータ４０８が設置されており、このステンレスのパイプと白金巻線ヒータ４０８の間には、絶縁のため石英ガラスのパイプ（図示せず）が設置されている。この高温ガス供給管４０７の中に室温の窒素ガスを供給すると、この高温ガス供給管４０７の中を通過する間に、窒素ガスは加熱された白金巻線ヒータ４０８により加熱され、高温のガスがガス供給室の中に供給される。
【０２８０】
本実施形態において、中心部ガス供給室４１２は、低温ガス供給管４０６と高温ガス供給管４０７が各１本ずつ接続されている。また、周辺部ガス供給室４１３には、円周上に６本の高温ガス供給管４０７が設置されている。
ガス流量調整バルブ４０９は、低温ガス供給管４０６および６本の高温ガス供給管４０７の全てに設けられている。このガス流量調整バルブ４０９により、ガス流量を予め設定された値から流量０まで連続的に制御することが可能である。本実施形態においては、低温ガス供給管４０６では最大５リットル／分の流量の窒素ガスを流すことができ、また、高温ガス供給管４０７では、各１本につき、最大１リットル／分の流量の５００℃の温度の高温の窒素ガスを流すことができるように、ガス流量調整バルブ４０９は設定されている。
【０２８１】
そして、受け型４０３と一体になっている受け型保持部材４０４と低温ガス供給管４０６と高温ガス供給管４０７は、上下に位置制御可能な上下駆動装置（図示せず）に連結されており、上下動できるようになっている。
次に、この装置を使って溶融ガラス塊４１０を得る工程の具体的な様子を、図２３乃至図２６を用いて説明する。
【０２８２】
図２３は、溶融ガラス流４０２を受け型４０３に受け始める直前の様子を示している。この時、受け型４０３は、溶融ガラス流出パイプ４０１の出口の下方１０ｍｍの位置まで上昇し停止している。この時、中心部ガス供給室４１２に接続されている低温ガス供給管４０６と、外周部ガス供給室４１３接続されている高温ガス供給管４０６は、全て全開になっている。従って、中心部ガス供給室４１２へ低温ガス供給管４０６から５リットル／分の流量の室温の窒素ガスが、周辺部ガス供給室４１３へ６本の高温ガス供給管４０７から合計６リットル／分の流量の５００℃の窒素ガスが、供給されている。このガスは多孔質の受け型４０３の細孔を通って受け面に噴出している。この時、受け面から噴出しているガスの温度は、中心部で１５０℃、外周部で４００℃であった。なお、本実施形態では、受け型保持部材４０４の中には加熱用のヒータは設置されていない。
【０２８３】
図２４は、溶融ガラス流４０２がさらに流出した時の様子を示している。この時、溶融ガラス４０２の先端部は、多孔質の受け型４０３の受け面に近接しているが、受け面からガスが噴出しているので、溶融ガラス流４０２の先端部と多孔質の受け型４０３の受け面とが接触することは無い。なお、この時、中心部ガス供給室４１２に接続されている低温ガス供給管４０６のガス流量調整バルブ４０９は、閉じ始めており、逆に高温ガス供給管４０７のガス流量調整バルブ４０９は、開き始めている。これらのガス流量調整バルブ４０９の開度調整は、ゴブ受け開始、すなわち、図２３の状態から、１秒後から行なわれ、その後３秒かけて、低温ガス供給管４０６のガス流量調整バルブ４０９を閉じるとともに、高温ガス供給管４０７のガス流量調整バルブ４０９を全開にした。なお、この間、外周部ガス供給室４１３に供給されている高温ガス供給管４０７のガス流量調整バルブ４０９は全開のままである。なお、図２４は、ゴブ受け開始後、１．５秒後の様子を示している。
【０２８４】
図２５は、溶融ガラス流４０２がさらに流出し、溶融ガラスが受け型４０３の上に溜まっている状態の様子を示している。この時、中心部ガス供給室４１２には１リットル／分の流量の５００℃の窒素ガスが、外周部ガス供給室４１３には６リットル／分の流量の５００℃の窒素ガスが、供給されている。ゴブ受け開始後８秒後に、受け型３の上に溜まった溶融ガラスの重量が所望の値になったので、受け型４０３を下方へ５ｍｍ下降させ、その状態で１秒保持する間に、溶融ガラス流を括れさせ、さらに自然切断し、溶融ガラス塊４１０を得た。
【０２８５】
この時、ガス供給室には高温ガス管４０７から高温のガスが供給されており、この高温のガスが受け型４０３から噴出しており、このガスによりガラス塊４１０は浮上保持されている。この状態を図２６に示す。この時、受け型４０３の受け面から噴出しているガスの温度は４００℃であった、このようにして得られたガラス塊４１０は、その重量が２．７ｇであり、その下面に凹み等は無く、上下面とも滑らかな自由表面からなっており、受け型４０３との接触痕等は無いので、光学素子成形用素材として大変適している。
【０２８６】
本実施形態特有の効果として、外観・形状ともに優れており、光学素子成形用素材として大変適しているガラス塊を、溶融ガラス流から得るための最適な成形条件を、中心部ガス供給室と外周部ガス供給室に供給するガスの、ガス温度、ガス流量、低温ガス流停止タイミングの組み合わせから、第２７の実施形態に比べより容易に求めることができる点がある。従って、所望とするガラス塊の大きさや形状、また、ガラスの種類が異なった場合も、その最適成形条件を、第２７の実施形態に比べより容易に素早く求めることができる。
【０２８７】
（第２５の実施形態）
第２５の実施形態では、光学素子成形用素材として適した成形ガラス塊を、プレス成形して得る方法について説明する。
図２７は、第２５の実施形態である成形ガラス塊の製造において用いた、成形型の構成を説明する図である。
【０２８８】
図２７において、４０６は低温のガスを供給するための低温ガス供給管、４０７は高温のガスを供給するための高温ガス供給管、４０８は高温ガス供給管４０７の内部に設けられたガス加熱用の白金線ヒータ、４０９は低温ガス供給管４０６および高温ガス供給管４０７の途中に設けられたガス流量調整バルブである。４１４は多孔質の成形型、４１５は多孔質の成形型４１４を保持している成形型保持ブロックであり、４０５は多孔質の成形型４１４の背面に位置し成形型保持ブロックで囲まれている供給室である。低温ガス供給管４０６と高温ガス供給管４０７はガス供給室４０５に接続されている。また、４１６は成形用下型であり、４１７は予め用意されたガラス塊である。
【０２８９】
図２８乃至図３２は、第２５の実施形態である成形ガラス塊の製造工程を、順次説明する図である。これらの図を用いて、本実施形態における動作を説明する。
ガラス塊４１７は、実施形態２７，２８に記載したような方法で予め製造され、用意されている。従って、本実施形態によるガラス塊の製造工程の初期段階において、このガラス塊４１７は比較的低温の状態にある。
【０２９０】
ガラス塊を成形する工程の初期段階において、図２７に示すように、予め用意されたガラス塊４１７は、成形用下型４１６の上に乗せられている。この時、成形用下型４１６は所望の温度に加熱されている。この時、多孔質の成形型４１４は、ガラス塊４１７の上方の位置にある。この時、低温ガス供給管４０６のガス流量調整バルブ４０９は閉じられており、一方、高温ガス供給管４０７のガス流量調整バルブ４０９は開かれている。そして、高温のガスがガス供給室４０５の内部に供給され、この高温のガスが多孔質の成形型４１４の細孔を通って、成形型４１４の成形面に噴出している。
【０２９１】
続いて、この高温のガスが成形面から噴出している状態の成形型４１４を、図２８に示すように、ガラス塊４１７の上面に近接した位置まで下降する。この状態で、成形面から噴出している高温のガスにより、ガラス塊４１７は熱変形可能な温度まで加熱される。
その後、成形型４１４を微速で下降させる。この間、成形面からは高温のガスが噴出しているので、成形型４１４の成形面とガラス塊４１７の上面とが接触することは無い。この時の様子を図２９に示す。
【０２９２】
更に、成形型４１４の下降が進むと、図３０に示すように、成形型保持ブロック４１５と下型４１６が接触し、ガラス塊４１７のプレス変形が終了する。なお、ガラス塊４１７をプレス成形する工程の間、成形面から高温ガスが噴射しているので、成形型４１４とガラス塊４１７が接触することは無い。
ガラス塊４１７のプレス変形が終了した後、そのままの状態で、図３１に示すように、高温ガス供給管４０７のガス流量調整バルブ４０９を閉じ始め、逆に、低温ガス供給管４０６のガス流量調整バルブを開け始めた。
【０２９３】
更に、図３２に示すように、高温ガス供給管４０７のガス流量調整バルブを閉め、低温ガス供給管４０６から低温のガスをガス供給室へ供給し、低温ガスを成形面から噴出している状態で、プレス成形された成形ガラス塊４１８を冷却した。
そして、取り出し可能な温度まで成形ガラス塊４１８を冷却した後、成形ガラス塊４１８を取り出した。
【０２９４】
このようにして得られた成形ガラス４１８は、その成形に先立って行う再加熱を、多孔質の成形型から噴射する高温のガスによって行うので、速い時間で成形可能な温度まで到達することができ、特に、予め用意されたガラス塊４１７の温度が十分に高い場合、成形に先立って行う再加熱の時間はほとんど不要になり、多孔質の成形型４１４の成形面から高温のガスを噴出した状態で、直ちに、ガラス塊４１７をプレス成形することが可能になる。また本実施形態により、成形型から噴射している高温のガスによりガラス塊４１７を加熱する場合、ガラス塊４１７の下面が過剰に加熱されることは無く、従って、ガラス塊４１７の下面と下型４１６とが融着することは無い。また、このようにして得られた成形ガラス塊４１８の上面は、プレス成形中、常に、成形型４１４から噴出しているガスにより非接触状態に保たれているので、非常に滑らかである。
【０２９５】
このようにして得られた成形ガラス塊４１８は、その上面は滑らかな自由表面であり、また、その下面は融着することも無く、このような外観精度に優れ、所望する形状となっている。
このようにして得られた成形ガラス塊４１８は、所望の成形光学素子に近似した形状をしているので、この成形ガラス塊４１８を光学素子成形用素材として用いると、成形時間が短くなる点、成形時に成形型に付けられている離型作用を有する薄膜を剥離されることが無くなる点等の利点がある。
【０２９６】
次に、本実施形態のより具体的な実施形態について、具体的に述べる。
成形型４１４は、多孔質の炭素珪素（ＳｉＣ）からなっており、この気孔率は２０％であり、平均孔径５μｍである。この多孔質の成形型４１４の成形面は、半径１０ｍｍの球面に加工されている。成形型４１４の上部および側面は、ステンレス製の成形型保持部材４１５で囲まれている。そして、成形型４１４の上面と成形型保持部材４１５の間には、ガス供給室４０５となる空間部が設けられている。また、成形型保持部材４１５の中には加熱用のカートリッジヒータ（図示せず）が設置されている。
【０２９７】
そして、このガス供給室４０５には、低温ガス供給管４０６と高温ガス供給管４０７の２種類のガス供給管が、成形型保持部材４１５を通って接続されている。低温ガス供給管４０６はステンレスのパイプからなっており、この低温ガス供給管４０６を通って、室温の窒素ガスがガス供給室４０５に供給される。高温ガス供給管４０７は、ステンレスのパイプの中に白金製の巻線ヒータ４０８が設置されており、このステンレスのパイプと白金巻線ヒータ４０８の間には、絶縁のため石英ガラスのパイプ（図示せず）が設置されている。この高温ガス供給管４０７の中に室温の窒素ガスを供給すると、この高温ガス供給管４０７の中を通過する間に、窒素ガスは加熱された白金巻線ヒータ４０８により加熱され、高温のガスがガス供給室４０５の中に供給される。
【０２９８】
本実施形態において、低温ガス供給管４０６はガス供給室４０５の中に円周上に４本設置されており、高温ガス供給管４０７は、低温ガス供給管４０６と交互に円周上に４本設置されている。
ガス流量調整バルブ４０９は、低温ガス供給管４０６および高温ガス供給管４０７の全てに設けられている。このガス流量調整バルブ４０９により、ガス流量を予め設定された値から流量０まで連続的に制御することが可能である。本実施形態においては、低温ガス供給管４０６では、各１本につき、最大５リットル／分の流量の窒素ガスを流すことができ、また、高温ガス供給管４０７では、１本につき、最大５リットル／分の流量の９００℃の温度の高温の窒素ガスを流すことができるように、ガス流量調整バルブ４０９は設定されている。
【０２９９】
そして、成形型４１４と一体になっている成形型保持部材４１５と低温ガス供給管４０６と高温ガス供給管４０７は、上下に位置制御可能な上下駆動装置（図示せず）に連結されており、上下動できるようになっている。
また、下型４１６は、カーボン材料で作られており、その成形面は半径３０ｍｍの球面に加工されている。そして、この下型４１６の内部には、加熱用のカートリッジヒータ（図示せず）が設置されている。
【０３００】
次に、この装置を使って成形ガラス塊４１８を得る工程の具体的な様子を、図２７乃至図３２を用いて説明する。
図２７は、成形工程の初期状態を示す。この時、ガラス塊２１７は、別の装置（図示せず）より溶融ガラス流から得られたガラス塊を、直ちにこの下型２１６の中に搬送したので、３００℃の温度であった。そして、下型４１６は、内蔵するカートリッジヒータ（図示せず）により、常時４００℃に加熱されている。一方、成形型保持ブロック４１５は内蔵するカートリッジヒータ（図示せず）により、常時６００℃に加熱されている。そして、４本の高温ガス供給管４０７からは、合計２０リットル／分の流量の９００℃の高温の窒素ガスがガス供給室４０５の中に供給されている。そして、この高温ガスは、多孔質の成形型４１４の細孔を通って成形面から噴出している。この成形面から噴出しているガスの温度は７００℃であった。
【０３０１】
ガラス塊４１７を下型４１６の上に載せた後、高温のガスが噴出している状態の成形型４１４を下降させ、図２８に示すように、ガラス塊４１７の上面に接近した位置で保持した。この状態で２０秒保持したところ、ガラス塊４１７は熱変形可能な温度まで加熱された。なお、この時のガラス塊４１７の温度は、上面が７００℃、中央部６００℃、下面が５５０℃であった。
【０３０２】
その後、直ちに、成形型４１４を下降させ始めた。下降速度は、０．２ｍｍ／秒であった。この時、成形型４１４の成形面からは高温のガスが噴出しているので、成形型４１４とガラス塊４１７が接触することは無い。このように、ガラス塊４１７をプレス成形している途中の様子を図２９に示す。
成形型４１４を下降させ始めてから２５秒後に、図３０に示すように、成形型保持ブロック４１５と下型４１６とが突き当たり、ガラス塊４１７のプレス成形が完了した。
【０３０３】
その後、直ちに、高温ガス供給管４０７のガス流量調整バルブ４０９を閉じ始めると同時に、低温ガス供給管４０６のガス流量調整バルブ４０９を開き始めた。図３１にこの様子を示す。１秒後に、高温ガス供給管４０７のガス流量調整バルブ４０９は完全に閉じられた。また、低温ガス供給管４０６のガス流量調整バルブ４０９は１０秒かけて全開にした。図３２にこの様子を示す。この間、成形型４１４の成形面から噴出しているガスの温度は下がるので、成形ガラス塊４１８は冷却される。更に、５秒冷却した時、成形ガラス塊４１８は取り出し可能な温度になったので、成形型４１４を上昇し、成形ガラス塊４１８を取り出した。
【０３０４】
このようにして得られた成形ガラス塊４１８は、その上面は自由表面からなっており成形型４１４との接触痕は無く、また、その下面は、下型４１６との融着は無く、滑らかであり、凹メニスカス形状のレンズを成形するための光学素子成形用素材として大変適している。
本実施形態特有の効果として、外観精度が優れており、所望の光学素子形状に近似した形状の、光学素子成形用素材として大変適している成形ガラス塊を、予め用意されたガラス塊を加熱して得るに際して、成形型から噴出するガスの温度を制御することにより、効率的な加熱冷却が可能なので、加熱および冷却に要する時間が非常に短くなり、成形時間の大幅短縮が可能になる。
【０３０５】
以上説明したように、上記の実施形態によれば、受け型から噴出しているガスの温度を制御することにより、光学素子成形用素材として適した、下面に凹みの無いガラス塊を、容易にかつ確実に製造することができる。
また、成形型から噴出しているガスの温度を制御することにより、ガラス塊をプレス成形して所望の形状の成形ガラス塊を得る方法において、加熱および冷却に要する時間を短くすることができる。
【０３０６】
また、受け型から噴出しているガスの温度をより正確かつ素早く制御することにより、光学素子成形用素材として適した、下面の凹みの無いガラス塊を、より容易にかつ確実に製造することができる。
また、成形型から噴出しているガスの温度をより正確かつ素早く制御することにより、ガラス塊をプレス成形し所望の形状の成形ガラス塊を得る方法において、加熱および冷却に要する時間をより短くすることができる。
【０３０７】
上記の第２３乃至第２５の実施形態をまとめると、第２９の方法においては、溶融ガラス塊製造工程において、その時間毎に所望される最適の温度のガスを多孔質の受け型の受け面から噴出するために、多孔質の受け型の背面に所望する異なった温度のガスを供給し、この所望の温度のガスを多孔質の受け型の受け面から噴出させる。
【０３０８】
多孔質の受け型の受け面から噴出するガスの温度を、経時的に所望の温度に制御するためには、受け型の背面に供給されるガスの温度を経時的に消耗の温度に制御することが、制御性が良く、受け型から噴出するガスの温度を短い時間で所望の温度に制御できるので望ましい。このとき、受け型の細孔を通過する間にガスの温度が下がるので、受け型の背面に供給されるガスの温度は、受け型の受け面から噴出するガスの所望の温度に比べ、高くすることが好ましい。
【０３０９】
なお、多孔質の受け型から噴出するガスの温度を制御する他の方法として、受け型の背面に供給するガスの温度を常時一定にし、受け型を保持する型ホルダーにヒータを内蔵し、このヒータにより型ホルダーの温度を制御し、それにより多孔質の受け型の温度を制御し、この多孔質の受け型の細孔を通過する噴出ガスの温度を制御する方法もある。しかし、この方法では、多孔質の受け型の熱伝導率が小さいため温度の追従性が悪く、本実施形態に比べ制御性が極めて悪い。
【０３１０】
このようにして、多孔質の受け型の受け面から噴出するガスの温度を、経時的に所望の温度に制御した場合、この受け型の上に受けられたガラス塊の下面には凹みは無く、光学素子成形用素材として優れた外観形状を有している。
なお、多孔質の受け型の受け面から噴出するガスの温度の経時的な制御としては、溶融ガラス流を受け型に受け始める初期の段階で、ガスの温度を低くし、その後、ガスの温度を高くすることが望ましい。このようにガス温度を制御することにより、溶融ガラスと受け型が接触すること無く、また、下面に凹みの無いガラス塊を、容易に、かつ、確実に得ることができる。
【０３１１】
なぜならば、初期の段階でガスの温度を低くすることにより、溶融ガラスと受け型が接触することを防止し、また、その後、ガスの温度を高くすることにより、ガラス塊の冷却速度が遅くなるので、下面が凹んだ状態でガラス塊が固化することを防止でき、ガラス塊の下面がその自重で下方に変形し、受け型の面の形状にほぼ倣った形になった後、固化することができるからである。
【０３１２】
また、第３０の方法においては、ガラス塊製造工程において、その時間毎に所望される最適の温度のガスを多孔質の成形型の成形面から噴出するために、多孔質の成形型の背面に所望する異なった温度のガスを供給し、この所望の温度のガスを多孔質の成形型の成形面から噴出させる。
多孔質の成形型の成形面から噴出するガスの温度を、経時的に所望の温度に制御するためには、成形型の背面に供給されるガスの温度を経時的に所望の温度に制御することが、制御性が良く、成形型から噴出するガスの温度を短い時間で所望の温度に制御できるので望ましい。このとき、成形型の細孔を通過する間にガスの温度が下がるので、成形型の背面に供給されるガスの温度は、成形型の成形面から噴出するガスの所望の温度に比べ、高くすることが望ましい。
【０３１３】
このようにして、多孔質の成形型の成形面から噴出するガスの温度を、経時的に所望の温度に制御した場合、多孔質の成形型でガラス塊をプレス成形するに先立って行う、ガラス塊を再加熱する工程を、大幅に短縮、または、削減できる。なお、多孔質の成形型の成形面から噴出するガスの温度の経時的な制御としては、ガラス塊をプレス成形し始める初期の段階で、ガスの温度を高くし、その後、ガスの温度を低くすることが望ましい。このようにガス温度を制御することにより、ガラス塊を再加熱する工程を、大幅に短縮、または、削減できる。
【０３１４】
なぜならば、ガラス塊をプレス成形し始める初期の段階で、多孔質の成形型から噴出するガスの温度を高くすることにより、ガラス塊上部の部分を熱変形可能な温度まで、短い時間で上げることができる。この時、ガラス塊の温度が前もって十分高ければ、この工程に先立ってガラス塊を再加熱する工程は不要となる。また、そうで無い場合も、短時間の再加熱を行えば、その後の多孔質の成形型から噴出される高温のガスにより、ガラス塊上部を熱変形可能な温度まで短い時間で上げることができるからである。
【０３１５】
また、多孔質の成形型から噴出される高温のガスにより、ガラス塊の上部を熱変形可能な温度まで加熱する時、このガスによりガラス塊の反対側の部分が過剰に加熱されることは無い。従って、この加熱によりガラス塊が反対側の下型と融着することは無い。そのため、多孔質の成形型から噴出される高温のガスにより、ガラス塊を加熱する場合、ガラス塊を急加熱しても融着しないので、加熱に要する時間を短くできる。
【０３１６】
また、第３１の方法においては、その時間毎に所望される最適の温度のガスを多孔質の受け型の受け面から噴出するために、多孔質の受け型の背面に所望する異なった温度のガスを供給し、この所望の温度のガスを多孔質の受け型の受け面から噴出させる。
この時、溶融ガラス塊製造工程の時間毎に所望される異なった温度のガスを、多孔質の受け型の背面に供給するために、受け型の背面に設置された、異なった温度のガスを供給できる複数のガス供給管のうちから適切なガス供給管を選択し、所望の温度のガスを多孔質の受け型の背面に供給することにより、所望の温度のガスを所望の時間に遅れることなく得ることができる。
【０３１７】
なぜならば、異なった温度のガスを供給できる複数のガス供給管のうちから適切なガス供給管を選択し、温度の異なったガスを混合することにより、瞬時に、所望とする温度のガスを得ることができる。
例えば、ガス温度を高くする場合は、次のようにする。先ず、最初、低温と高温の２つの温度を含む複数のガス供給管からガスを供給し、それらを混合し、低温のガスを多孔質の受け型の背面に供給する。次に、低温のガス供給管からの低温ガス供給を停止する。すると、多孔質の受け型の背面に供給されるガスの温度は直ちに上昇する。逆に、ガスの温度を低くする場合は、最初、低温のガス供給管からはガスが供給されていない状態で、高温のガスを多孔質の受け型の背面に供給する。次に、低温ガス供給管から低温ガスを供給する。すると、多孔質の受け型の背面に供給されている混合されたガスの温度が直ちに下がる。
【０３１８】
このように、多孔質の受け型の背面に設置された複数のガス供給管のうちから適切なガス供給管を選択し、所望の温度のガスを多孔質の受け型の背面に供給することにより、所望の温度のガスを所望の時間に遅れることなく得ることができる。
なお、この時のガス供給管の選択切替は、瞬間的に断続的に行っても、連続的に行っても良く、後者の方が、より精度の高いガス温度コントロールが可能となる。また、選択切替するガス供給管の本数は、１本に限らず複数本でも良く、その場合、これらのガス供給管の選択切替のタイミングは、各々のガス供給管毎に異なっていても良い。
【０３１９】
なお、多孔質の受け型の背面に供給するガスの温度を変える手段として、受け型の背面に設置された唯一のガス供給管の内部に加熱用のヒータを設け、このヒータの出力を調整することにより、供給ガスの温度を変える手段が従来から知られている。しかし、この方法では、ガスの温度を瞬時に所望の温度に制御することはできない。なぜならば、この方法では、ヒータの温度を所望の温度にし、さらに、ヒータからの熱伝達によりガスの温度を所望の温度にするのに時間がかかるためである。
【０３２０】
一方、本方法では、ガスの温度を瞬時に所望の温度にすることができる。従って、溶融ガラス塊を製造する工程において、最適の噴出ガスの温度制御が可能になるので、得られたガラス塊の下面には凹みは無く、光学素子成形用素材として優れた外観形状を有している。
また、第３２の方法においては、その時間ごとに所望される最適の温度のガスを多孔質の成形型の成形面から噴出するために、多孔質の成形型の背面に所望する異なった温度のガスを供給し、この所望の温度のガスを多孔質の成形型の成形面から噴出させる。
【０３２１】
この時、成形ガラス塊製造工程の時間毎に所望される異なった温度のガスを、多孔質の成形型の背面に供給するために、成形型の背面に設置された、異なった温度のガスを供給できる複数のガス供給管のうちから適切なガス供給管を選択し、所望の温度のガスを多孔質の成形型の背面に供給することにより、所望の温度のガスを所望の時間に遅れることなく得ることができる。
【０３２２】
このように、本方法では、ガスの温度を瞬時に所望の温度にすることができる。従って、成形ガラス塊を製造する工程において、最適の噴出ガスの温度制御が可能になるので、多孔質の成形型でガラス塊をプレス成形するに先立って行う、ガラス塊を再加熱する工程を、大幅に短縮、または、削減できる。
（第２６の実施形態）
図３３は第２６の実施形態に係わる光学素子成形用ガラス素材の作製方法を示す概略図である。
【０３２３】
図３３（ａ）で５０１は図３４に組成を示すガラス素材であり、所要の体積になるように直方体に切断されている。５０２はガラス素材の上面を形成するための多孔質カーボン材で高温ガスを吹き出す面５０２ａはＲ５０に加工されている。５０３，５０４はガラス素材の下面を形成するための多孔質カーボン材で高温ガス（後の成形において非酸化状態である必要があり、本実施形態ではＮ２を用いている）を吹き出す面５０３ａ、５０４ａはＲ２８に加工されている。ここで下面を形成する多孔質カーボン材を５０３，５０４と２分割にしているのは後の成形においてガラス素材を下に落とし、型に投入するためである。５０５，５０６は高温ガスを密閉するための外枠であり５０６は多孔質カーボン材と同様に２分割されている。５０７，５０８，５０９は高温ガスを導入するパイプであり、不図示の加熱装置から高温ガスが送られていくる。
【０３２４】
ここで高温ガスをこのガラスの粘度で１０６ｄＰａ・ｓである７４０℃に設定し、３０リットル／分の流量で高温ガスを吹き出し、図３３（ｂ）に示すように変形させた。図３３（ｂ）で５１０は高温ガス、５１１は変形したガラス素材である。２分後、上面形成用の多孔質カーボン材５０２をガラス素材から遠ざけ下面形成用の多孔質カーボン材５０３，５０４から吹き出す高温ガスの流量を２リットル／分に絞った。これは吹き出す時間とガラス素材の肉厚の関係をとると、２分後に所要の肉厚８．７ｍｍに達しており、ここで変形を抑えるために上面形成用の多孔質カーボン材５０２を遠ざけ、保持するに足りる流量だけ下面形成用の多孔質カーボン材５０３，５０４から高温ガスを吹き出した。また２分間の変形中、上面形成用の多孔質カーボン材５０２は吹き出し時間と変形量の関係から徐々に下に移動させている。
【０３２５】
この方法で作製したガラス素材の表面粗さを測定すると、熱変形前の切断されたブロック材ではＲｍａｘで１μｍ以上あったのが０．０２μｍｍになり、成形用のガラス素材の仕様を満たしていた。
比較例として高温ガスの温度を変化させた時の状況を図３５に示す。先ず、ガラスの粘度で１０４．５ｄＰａ・ｓに相当する温度８４０℃に設定した時には変形が急であり流量を絞っても自重により変形が進んでしまい、図３５に示すように多孔質カーボン材の外まで変形してしまう。これはガラスの粘度で１０５ｄＰａ・ｓに相当する温度８００℃以下であれば高温ガスの流量を絞ることにより発生しない。逆に高温ガスの温度をガラスの粘度で１０８．５ｄＰａ・ｓに相当する温度６５５℃に設定した時には変形が非常に遅く所要の形状になるのに数十分を要し、表面粗さもＲｍａｘで０．０４μｍ以下にならなかった。しかし、ガラスの粘度で１０８ｄＰａ・ｓに相当する温度６７５℃以上であれば変形も数分で完了し、表面粗さもＲｍａｘで０．０４μｍ以下になり、ガラス素材の仕様を満たす。
【０３２６】
このガラス素材をプレス成形して光学素子を成形する方法を図３６を用いて説明する。図３６において５１２はレンズの上面を形成するための上型で、ガラスと接触する面５１２ａはＲ５４に研磨してある。５１３はレンズの下面を形成するための下型で、ガラスと接触する面５１３ａはＲ３０に研磨してある。５１４は上下型の軸を合わせるための胴型である。図３６（ａ）に示すようにガラス素材を浮上させた状態で下型５１３の真上に持ってゆき、図３６（ｂ）に示すように多孔質カーボン部材を左右に開き下型上にガラス素材を落とす。この時、上下型はこのガラスの粘度で１０１２ｄＰａ・ｓに相当する５７０℃に不図示の加熱装置で調温してある。その後、多孔質カーボン材を胴型外へ出し、図３６（ｃ）のように上型を下降させプレスする。プレスはガラス素材の中心部から接触変形するようになっており、ガス残りは発生しない。プレス変形は上型のツバ部５１２ｂが胴型の上部５１４ａに突き当たった時点で終了する。この方法で作製したレンズはフィゾー干渉計によるとアス及びクセがニュートンリング０．５本以下の良好な形状精度を有していた。型の温度をこのガラスの粘度で１０１３ｄＰａ・ｓより大きく（低温）したものは変形が完了するまでにガラスの温度が下がってしまい押し切らなかったり、レンズ表面がしわ状になる不良が発生した。逆に型の温度をこのガラスの粘度で１０１０ｄＰａ・ｓより小さく（高温）したものはプレス完了後すぐに取り出すと自重や取り出し時の外力により変形してしまい形状精度が悪化したため１０１０ｄＰａ・ｓに相当する温度以下に冷却した後、取り出さなければならなかった。また、型も劣化が激しく耐久性が低下した。以上のように本実施形態によるガラス素材の作製方法とその後のプレス成形方法によれば、切断したガラスブロックから安価に所要の容積、形状、表面粗さを有したガラス素材を作成することができ、かつ成形時間の短縮と型の耐久性の向上が図れる。
【０３２７】
（第２７の実施形態）
図３７に示すように凹レンズ成形用のガラス素材を作製した。ガラスは第２６の実施形態で用いたものと同じものである。高温ガスの温度をガラスの粘度で１０7ｄＰａ・ｓに相当する７０５℃にし、流量を３５リットル／分に設定した。３分間吹き出すことにより所要の中心厚になった。３分間吹き出した時点で上面形成用の多孔質カーボン部材５１８からの高温ガスの温度をガラスの粘度で１０9.5ｄＰａ・ｓに相当する６２０℃に、流量を５リットル／分に変更し、下面形成用の多孔質カーボン部材５１９からの高温ガスの温度はそのまま７０５℃、流量を５リットル／分に変更した。２分後、高温ガスの吹き出しを止めると同時に上面形成用の多孔質カーボン部材５１８への高温ガス導入パイプ５２２から真空引きし、ガラス素材５１７を上面形成用の多孔質カーボン部材５１８に真空吸着した。吸着前に上面形成用の多孔質カーボン部材５１８からの高温ガスの温度を下げたのは、ガラス素材の温度が高いと変形しやすく真空吸着によるガラス素材５１７と多孔質カーボン部材５１８との接触面積が増えるため、この後の工程でガラスを下型上へ落下させるのが困難になるためである。
【０３２８】
真空吸着したまま、図３８（ａ）に示すように下型の真上にガラス素材５１７を運び、図３８（ｂ）に示すように少しガスを吹き出すことにより、ガラス素材５１７を下型５２６上に落とす。この時上下型５２５，５２６はガラスの粘度で１０１０ｄＰａ・ｓに相当する６００℃に調温してある。ここで５２８は、ガラス素材を下型の中心にセットするための位置決めピンである。その後、多孔質カーボン部材を胴型外へ出し、図３８（ｃ）の様に上型５２５を下降させプレスする。この時、位置決めピンは、プレス変形が開始するとガラス素材５１７から遠ざかる。
【０３２９】
この方法で作製したレンズはフィゾー干渉計によるとアス及びクセがニュートンリング０．５本以下の良好な形状精度を有していた。
以上のように本実施形態によるガラス素材の作製方法とその後のプレス成形方法によれば、切断したガラスブロックから安価に所要の容積、形状、表面粗さを有したガラス素材を作製することができ、かつ成形時間の短縮と型の耐久性の向上が図れる。
【０３３０】
また、ガラス素材の上下面に温度差を設けて、真空吸着によりガラス素材の搬送が可能となる。
（第２８の実施形態）
図３９に示すように凸メニスカスレンズ成形用のガラス素材５３１を作製した。ガラスは図４０に組成を示すガラスを用いた。第２６の実施形態と同様な方法でガラス素材５３１の作製及びプレス成形を行った。ただし条件としては高温ガスはガラスの粘度で１０６ｄＰａ・ｓに相当する温度７４０℃とし、３分間４０リットル／分の流量で吹き付けた。光学素子成形用の上下型の温度はガラスの粘度で１０１２ｄＰａ・ｓに相当する温度にした。
【０３３１】
この方法で作製したレンズは形状精度としては、フィゾー干渉計により、アス及びクセがニュートンリング０．５本以下と良好であったが、下型の劣化が激しく成形品の曇耐久が１００ｓｈｏｔ程度しかなかった。そこで、下型の劣化を抑えるために、ガラス素材の作製時、形状を形成した後、下面形成用の多孔質カーボンからの高温ガスをガラスの粘度で１０９．５ｄＰａ・ｓに相当する温度にして３分間保持した後下型へ投入した。すると下型の劣化はなくなり、２０００ｓｈｏｔ成形後も成形品の曇りは発生しなかった。
【０３３２】
以上のように本実施形態によるガラス素材の作製方法とその後のプレス成形方法によれば、切断したガラスブロックから安価に所要の容積、形状、表面粗さを有したガラス素材を作製することができ、かつ成形時間の短縮と型の耐久性の向上が図れる。
また、型の劣化が激しいガラスについてはガラス素材の下面の温度を下げることにより型の耐久を向上させることができる。
【０３３３】
本実施形態では多孔質部材としてカーボンを用いたがその他多孔質セラミックや金属でも同様の効果が得られた。
上記の第２６乃至第２８の実施形態をまとめると、第３３の方法においては、切断あるいは研削により所定の体積に調寸したガラス塊を多孔質部材の間で高温ガスによりガラスの粘度で１０5〜１０8ｄＰａ・ｓに加熱することにより所定の形状に変形させるとともにその表面粗さをＲｍａｘで０．０４μｍ以下にする。これは、高温ガスによる加熱であるため型とは直接接触せず型の表面粗さの影響を受けない。またガラスの粘度で１０5〜１０8ｄＰａ・ｓに加熱するため立方体や直方体からレンズ形状などへの変形が可能である。
【０３３４】
また、第３４の方法においては、上記の第３３の方法で作製したガラス素材をそのガラスの粘度で１０１０〜１０１３ｄＰａ・ｓに相当する温度に調温した型に投入してプレス成形する。ガラス素材の温度が高温ガスで変形するほどの温度であるため型の温度がガラスの粘度で１０１０ｄＰａ・ｓより小さい（高温）とガラスの温度が高いため型の劣化が激しく、型の耐久性が落ちるとともに、プレス後、成形品の取り出し温度（ガラスの粘度で１０１０ｄＰａ・ｓ以下）まで冷却する必要があり成形時間が長くなる。型の温度をガラスの粘度で１０１０〜１０１３ｄＰａ・ｓに相当する温度にすることにより型の劣化が少なくなり、プレス後の冷却時間が短縮される。また型の温度がガラスの粘度で１０１３ｄＰａ・ｓより大きい（低温）と変形途中でガラスが冷えてしまいプレス変形が完了しない。
【０３３５】
なお、本発明は、その主旨を逸脱しない範囲で、上記実施形態を修正又は変形したものに適用可能である。
【０３３６】
【発明の効果】
以上説明した様に、本発明によれば、成形品と型の成形面との接触に起因する融着や面の転写不良、及び型の成形面の劣化を回避することができる。また、型の成形面と成形品の熱膨張差に起因する形状転写不良を回避することが出来る。さらに、研削研磨等の加工方法により発生する研削研磨屑等の廃棄物を極端に削減することが可能となり、レンズ等の精密素子を大量に安価に提供することが出来る。
【０３３７】
また、融着や膜剥離の発生しやすいレンズ周辺部で、型とガラスを非接触の状態で成形することができ、その結果融着などのトラブルがなく連続的に成形を行うことが出来る。さらに、上下の型で噴出するガスに温度差をつけることによって、離型したときに安定的に成形品を下型上に残してハンドリングのトラブルを防止できる。さらに、外形成形部材として多孔質材を使用することにより、型の隙間にガラスが入り込まない状態で芯取りの必要のない光学素子を得ることが出来る。
【０３３８】
また、受け型から噴出しているガスの温度を制御することにより、光学素子成形用素材として適した、下面に凹みのないガラス塊を、容易にかつ確実に製造することが出来る。また、成形型から噴出しているガスの温度を制御することにより、ガラス塊をプレス成形して所望の形状の成形ガラス塊を得る方法において、加熱及び冷却に要する時間を短くすることが出来る。また、受け型から噴出しているガスの温度をより正確かつ素早く制御することにより、光学素子成形用素材として適した、下面に凹みのないガラス塊を、より容易にかつ確実に製造することが出来る。さらに、成形型から噴出しているガスの温度をより正確かつ素早く制御することにより、ガラス塊をプレス成形して所望の形状の成形ガラス塊を得る方法において、加熱及び冷却に要する時間をより短くすることが出来る。
【０３３９】
また、ガラスブロックから任意の曲率半径を有するレンズ状のガラス素材を安価に作製可能となる。また、型へ投入する前のガラス素材の上下面に温度差を設けることが可能となり、型への搬送が有利になり、型の耐久性の向上も図れる。また、成形時間の短縮も図れる。
【図面の簡単な説明】
【図１】精密素子の成形装置の概略構成図である。
【図２】成形素材の分離方法を説明するための図である。
【図３】成形面の補正方法を示す概念図である。
【図３Ａ】成形面の補正方法を示す概念図である。
【図４】型ユニットの構造を示す図である。
【図５】成形素材の状態を示す図である。
【図６】型の構造を示す図である。
【図７】芯取り後の光学素子の形状を示す図である。
【図８】型の材料を示す図である。
【図９】上型と下型の温度差を示す図である。
【図１０】型の構造を示す図である。
【図１１】芯取り後の光学素子の形状を示す図である。
【図１２】ガスの流量と成形品の外観品質の関係を示す図である。
【図１３】型の構造を示す図である。
【図１４】芯取りを不要にした光学素子を示す図である。
【図１５】型の構造を示す図である。
【図１６】芯取りを不要にした光学素子を示す図である。
【図１７】型の構造を示す図である。
【図１８】光学素子成形用素材を成形する工程を示す図である。
【図１９】光学素子成形用素材を成形する工程を示す図である。
【図２０】光学素子成形用素材を成形する工程を示す図である。
【図２１】光学素子成形用素材を成形する工程を示す図である。
【図２２】型の構造を示す図である。
【図２３】光学素子成形用素材を成形する工程を示す図である。
【図２４】光学素子成形用素材を成形する工程を示す図である。
【図２５】光学素子成形用素材を成形する工程を示す図である。
【図２６】光学素子成形用素材を成形する工程を示す図である。
【図２７】型の構造を示す図である。
【図２８】光学素子成形用素材を成形する工程を示す図である。
【図２９】光学素子成形用素材を成形する工程を示す図である。
【図３０】光学素子成形用素材を成形する工程を示す図である。
【図３１】光学素子成形用素材を成形する工程を示す図である。
【図３２】光学素子成形用素材を成形する工程を示す図である。
【図３３】凸レンズ成形用ガラス素材の製造方法を示す図である。
【図３４】ガラス素材の組成を示す図である。
【図３５】変形しすぎたガラス素材を示す図である。
【図３６】光学素子の成形方法を示す図である。
【図３７】凹レンズ成形用ガラス素材の製造方法を示す図である。
【図３８】光学素子の成形方法を示す図である。
【図３９】凸メニスカスレンズ成形用ガラス素材の製造方法を示す図である。
【図４０】ガラス素材の組成を示す図である。
【図４１】凸面成形時のガス残り状態を示す図である。
【図４２】凹面成形時のガス残り状態を示す図である。
【図４３】ガラス素材の容量が大きすぎた場合を示す図である。
【図４４】ガラス素材の容量が小さすぎた場合を示す図である。
【符号の説明】
１ 型ユニット
２ 下型構成部材
３ 上型構成部材
１１ 下型部材
１１ａ，２１ａ 成形面
１２ 下型ホルダー
１２ａ，２２ａ 圧力室
１３，２３ ヒータ
２１ 上型部材
２２ 上型ホルダー
３１ 供給パイプ
３２ａ，３２ｂ 圧力・流量調節器
３３ａ，３３ｂ 加熱ヒータ
３４ａ，３４ｂ フレキシブルチューブ
４１ コントローラ
１０２ａ ガラス塊[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical element molding method, an optical element, a method for manufacturing an optical element molding material, and a precision element for molding a high-precision optical element such as a lens used in a camera or a video camera by hot working. And a precision element.
[0002]
[Prior art]
In recent years, a method of directly press-molding a molding material such as heat-softened glass or the like using a molding die has attracted attention, instead of a processing method of a precision optical element by grinding and polishing.
Normally, this type of molding uses a molding die consisting of a barrel mold and upper and lower molds that slide within the barrel mold, and presses the molding material in a heat-softened state to accommodate the molding surface of the mold member. A method is used in which the optical functional surface thus transferred is transferred to a molding material, followed by cooling, and taking out the precision optical element from the mold member.
[0003]
In Japanese Patent Publication No. 48-22777 and Japanese Patent Application Laid-Open No. 59-195541, a gas film is formed on the surface of a mold using a porous material or ultrasonic vibration, and the mold and molding material are softened glass through the film. A technique for forming a lens or the like in a non-contact state is disclosed.
[0004]
[Problems to be solved by the invention]
However, in the conventional example in which the molding surface of the molding die is brought into contact with the molding material to transfer the shape to obtain a precision optical element, the heated die and the molding material are in direct contact with each other. There are problems such as fusing between the mold and the surface of the molding material due to non-uniform thermal shrinkage due to the temperature difference between the mold and the molding material. was there. In particular, when the molding material is glass, such a problem becomes prominent because the molding temperature is high, and it is possible to shorten the molding time by raising the molding temperature, or molding precision optical elements directly from high-temperature molten glass. It was very difficult to do. Furthermore, since the glass and the mold material react due to contact between the glass as the molding material and the mold, or the mold deteriorates due to wear on the surface of the mold, the usable mold material is also limited. There was a problem that the number of types became very limited.
[0005]
In order to avoid the above problems, Japanese Patent Publication No. 48-22777 and Japanese Patent Application Laid-Open No. 59-195541 disclose techniques for molding without bringing a mold and glass as a molding material into contact with each other. Thus, it is ideal to form the glass and the mold in a non-contact state, and it is effective for preventing fusion and for the surface state of the molded product. However, if a hot molding material in a softened state is molded in a non-contact manner, the molding material will shrink freely regardless of the mold during the cooling period after molding, so the shape when molding is different from the shape when cooling is completed. End up. In particular, if the thickness of the molded product is not constant or the cooling to the molded product is not uniform, a temperature distribution will occur inside the molded product during cooling, and heat shrinkage during cooling will occur evenly. However, since the shrinkage concentrates on a relatively high temperature portion, the portion is deformed into a depressed state after cooling. This is a so-called sink, and when such a sink occurs, the shape of the completed optical element is greatly different from the original target shape. In particular, when the molding material is glass, the thermal expansion coefficient is extremely large above the glass transition point temperature, which is the temperature range that can be molded, and the glass is cooled while the molding is finished and cooled from the molding temperature to the glass transition temperature. However, since it is difficult to control the shrinkage deformation, it is very difficult to produce a highly accurate product. This problem is also a problem that occurs in the same manner as described above in which the molding material and the mold are brought into contact with each other.
[0006]
Furthermore, regardless of whether the molding material and the mold are brought into contact with each other or not, if there is a difference in the coefficient of thermal expansion between the mold and the molding material, there will be a subtle difference in the dimensional shape between the mold and the molded product due to temperature changes. Occur. This phenomenon is unavoidable in a molding method involving a temperature change using a mold, and the shape of the mold once transferred to the molding material deviates from the shape of the mold due to a temperature change, particularly a temperature change due to cooling. It means to end.
[0007]
In the molding method in which the molding material and the mold are in contact, if the molding material and the mold are in contact with each other halfway during cooling, the molding material and the mold partially peel off, causing a problem in shape transferability. . To prevent this, pressure is applied to the mold close to a temperature at which the molded product does not deform due to its own weight, and a method of preventing the molded product from peeling off the mold, or simply the adhesion that occurs between the mold and the molding material at a high temperature. A method is used in which the molded product and the mold are brought into close contact with each other up to a temperature near the temperature at which the molded product is not easily deformed.
[0008]
However, among these methods, in the method of applying pressure to the mold, there is an advantage that the temperature at which the shape is finally transferred, that is, the temperature at which the pressure is released when cooling progresses can be strictly controlled. There was a problem that excessive force was applied to the molded product, causing cracking of the molded product and damage to the mold. In addition, there was a problem that some shapes could not be handled. Also, the method that relies on the adhesion force is virtually impossible to strictly control the delicate interface state that affects the adhesion force between the mold and the molded product, so the temperature at which the mold and the molded product are released is unstable. Thus, there is a problem that the shape transferability is not stable, and the molded product is caused to have a defect such as a crack as in the method of applying the pressure. Furthermore, even in the case of molding without contacting the molding material and the mold, the molding material is not in contact with the mold, so it is unstable to determine when the shape of the mold is transferred to the molding material. There is a problem that the shape of the product is not stable and it is almost impossible to transfer a highly accurate shape.
[0009]
In addition, if there is a defect such as a cut mark on the surface of the molding material supplied to the mold, even if molding is performed in a non-contact state, the defect remains in the molded product, and that part is ground and polished again. Therefore, there is a fundamental problem that the original purpose cannot be achieved. In the conventional example described above, no technical disclosure is made on this point.
Further, one of the important conditions in the molding method of the optical element is to prevent the fusion between the mold and the glass. In other words, it is necessary to improve mold releasability between the mold and the glass. With this as the main purpose, various proposals have conventionally been made regarding mold materials and glass materials. Some examples include 13Cr martensitic steel in JP-A-49-51112, SiC and Si3N4 in JP-A-52-45613, and cemented carbide in JP-A-60-246230. A material coated with a noble metal has been proposed. Further, recently, as a carbon-based material considered to be particularly excellent in releasability, a diamond thin film is proposed in Japanese Patent Laid-Open No. 61-183134, and a hydrogenated amorphous carbon film is proposed in Japanese Patent Laid-Open No. 2-80330. Yes. JP-A-60-210534 proposes a molding method in which a glass material is coated with a thin film having a releasing function in advance.
[0010]
However, 13Cr martensitic steel is easily oxidized and has the disadvantage that Fe diffuses into the glass at a high temperature and the glass is colored. SiC, Si3N4Has a strong affinity with glass and is likely to cause fusion. Molds coated with precious metals are very soft and have the disadvantage of being easily scratched. Diamond thin film is difficult to obtain optical specularity. The hydrogenated amorphous carbon film has a release property superior to any of the above. The problem is that since it is a thin film, it may be peeled off by a strong external force. The peeling of the film is considered to occur because a shearing force is generated on the film during the cooling after the press molding due to the thermal stress caused by the difference in thermal expansion coefficient between the mold and the glass. That is, since the mold and the glass are strongly adhered immediately after pressing and during cooling, the film peels off due to thermal stress. This peeling phenomenon is particularly remarkable at the periphery of the mold. The reason is that the peripheral part of the mold has the largest thermal stress, and in the case of a convex lens, the peripheral part is thin, and it is considered that the mold and the glass are in close contact with each other compared to the central part. If the film peels off even a little, the mold and glass are fused at that portion or the molded product is cracked, so that it cannot be used as a mold. In addition, if the glass material is coated with a thin film having a mold release function in advance, the adhesion between the pressed mold and the glass can be reduced. However, it is particularly useful in places where the adhesion is strong, such as the peripheral part of a convex lens. It is not a sufficient means to prevent wearing. Also, a thin film coating process is required.
[0011]
As described above, conventionally, there has been a problem that fusion occurs at the periphery of the mold or the film of the mold is peeled off. The only countermeasure is to use a material with good releasability, such as graphite, as the mold material in the periphery, but it is not a suitable material because it is soft and easy to wear out and becomes a source of dirt.
In addition, when molding an optical element, a softened glass lump is press-molded with a mold to obtain a molded optical element. However, development of a method for producing a glass lump having good appearance accuracy at low cost has recently been advanced. It is out.
[0012]
On the other hand, development of a technique for forming a shape of a glass lump, which is a forming material, into a shape close to the shape of a desired shaping optical element has been advanced in advance. The advantage of the molding material molded in a shape close to the molding optical element is that the amount of deformation during press molding is small, so that the press molding time can be shortened, and the mold release action formed on the mold surface There exists a point which can prevent that the thin film which it has is damaged by the shearing stress accompanying press deformation at the time of press molding.
[0013]
As a method for producing a glass lump having good appearance accuracy at low cost, the following production methods are specifically known.
That is, it is a method of obtaining a molten glass lump by receiving the molten glass flow flowing out from the outlet in a state of floating from the receiving mold on the receiving mold from which gas is jetted from below. Since the glass lump obtained in this way consists of smooth free surfaces on both the upper and lower surfaces, the surface roughness is also very smooth and has good appearance accuracy. Further, since no post-processing is required, the manufacturing cost is very low.
[0014]
As a specific example, Japanese Patent Publication No. 7-51446 is known as an example of obtaining a glass lump in a receiving mold having gas ejection holes. In addition, as an example of obtaining a glass lump by receiving a molten glass flow in a state where gas is ejected from a receiving mold made of a porous material, the description has already been seen in Japanese Patent Publication No. 48-22777, Recently, the description can be found in JP-A-6-122526, JP-A-6-144845, JP-A-6-206730, and the like.
[0015]
On the other hand, JP-A-4-37614 is known as a method for press-molding a glass lump that is a forming material to obtain a shaped glass lump having a desired shape. Here, the glass lump received on the receiving mold is taken out from the receiving mold, placed on the lower mold for press molding, reheated to a temperature at which heat deformation is possible, and then the glass lump is molded. To obtain a shaped glass lump of a desired shape.
[0016]
However, the method of receiving the glass lump in a state of floating from the receiving mold, which is the conventional example, has the following drawbacks.
That is, due to the gas flow ejected from the receiving mold, the lower surface of the glass block received on the receiving mold is solidified while being lifted upward. That is, the lower surface of the obtained glass lump is recessed.
[0017]
Thus, when a molded optical element is obtained by press molding using a glass lump having a concave lower surface as an optical element molding material, the nitrogen gas filled inside the chamber of the press molding machine is pressed. At the time of molding, press molding is performed in a state of being taken into the concave portion of the lower surface of the glass lump. As a result, a concave portion called “gas residue” is generated on the lower surface of the molded optical element, resulting in a defective product. Therefore, it cannot be used as an optical element.
[0018]
In order to prevent such depression of the lower surface of the glass lump, the flow rate of the gas flow ejected from the receiving mold may be reduced. However, if the flow rate of the jet gas is reduced too much, the molten glass and the receiving mold come into contact. Since such a glass lump transfers the uneven shape of the pores of the porous receiving mold, it has a poor appearance and cannot be used as an optical element molding material.
[0019]
As another method for preventing the depression of the lower surface of the glass block, there is a method using a high-temperature gas as the gas ejected from the receiving mold. That is, the depression of the lower surface of the glass block can be prevented by increasing the temperature of the gas ejected from the receiving mold and decreasing the flow rate of the ejected gas. However, also in this case, if the temperature of the jet gas is excessively increased or if the flow rate of the jet gas is excessively reduced, the molten glass and the receiving mold come into contact with each other.
[0020]
As described above, the conventionally known methods for preventing the dent on the lower surface of the glass lump often contact the molten glass with the receiving mold. It was difficult to set.
On the other hand, Japanese Patent Laid-Open No. 4-37614, which is a conventional example of a method for obtaining a molded glass lump having a desired shape by press-molding the glass lump, has the following drawbacks.
[0021]
That is, prior to press-molding a glass lump to obtain a glass lump of a desired shape, it takes a very long time to reheat the glass lump when it is reheated to a temperature at which it can be thermally deformed. Specifically, according to the description of Examples in JP-A-4-37614, a time of 5 minutes to 20 minutes is necessary for reheating.
As described above, the reason why reheating takes a long time is to reheat in order to prevent the glass lump and the molding lower mold from fusing due to rapid heating and excessive temperature rise of the glass lump. This is because the heating temperature is kept low.
[0022]
In addition, the glass material used for the press molding of the glass optical element is required to have a shape, a capacity, a surface roughness, etc., which are already described.
As shown in FIGS. 41 and 42, when the concave mold 540 is used, the glass material 539 has a large radius of curvature. When the convex mold 542 is used, if the glass material 541 has a small radius of curvature, A gas residue is generated between the mold and the glass. Therefore, the radius of curvature must be adjusted so that the shape of the glass material sequentially contacts and deforms from the center (in the case of a concave shape: the glass material is convex and its radius of curvature <the curvature of the mold) Radius, convex mold: If the glass material is convex or concave, the radius of curvature is greater than the radius of curvature of the mold.
[0023]
If the capacity is large depending on the mold structure, the protruding portion becomes large as shown in FIG. 43, which may cause cracking during molding or require post-processing. If it is small, the effective diameter of the lens cannot be obtained as shown in FIG. Therefore, it is necessary to adjust the capacity to a required range.
The surface roughness of the lens needs to be 0.02 μm or less in terms of Rmax in terms of transmittance and the like. In order to satisfy this, it is natural that the surface roughness of the mold is 0.02 μm or less in terms of Rmax, but the glass material also needs to be 0.04 μm or less. If it exceeds this, the surface roughness does not become 0.02 μm or less even by pressing.
[0024]
The following methods have been proposed to create a glass material that satisfies these specifications.
(A) No. 4-20854
The glass material is ground and polished so as to have a curvature shape approximate to the lens shape, and the surface roughness Rmax is 0.01 μm or less.
(B) Japanese Patent Publication 4-43851
The glass material is softened by heating to make it spherical by surface tension, and the surface roughness is made Rmax 0.04 μm or less.
(C) Japanese Patent Publication No. 3-60435
Glass in a molten state is formed on one surface by an optical glass element and a heat processing jig having an approximate shape, and the other surface is formed by surface tension to obtain a glass material for precision forming.
[0025]
Moreover, there exist the following as what uses a porous member.
(D) JP-A-61-266317
A glass material is heated and softened and conveyed in a non-contact state via a pressurized gas using a porous member.
However, these methods have the following problems. In the method of grinding and polishing of Japanese Patent Publication No. 4-20854, the cost for these processes including the subsequent cleaning process is high. Further, there are disadvantages such as a bad influence on molding such as burns and surface contamination due to polishing, and waste of glass material due to grinding and polishing. In contrast, the method of heating and softening the glass material of Japanese Examined Patent Publication No. 4-43851 to spheroidize by surface tension solves the above-mentioned problems, but the shape can only be spherical and the production of a glass material for forming a concave lens is possible. Impossible. Further, in the case of a convex lens or a meniscus lens, there is a drawback that the amount of deformation becomes larger than that of an approximately shaped glass material, and the molding tact is extended and the load on the mold is increased. In the method of producing a raw material from glass in a molten state disclosed in Japanese Patent Application Laid-Open No. 3-60435, the problems with the method by grinding and polishing are solved, but the shape of one surface cannot be adjusted. Furthermore, depending on the type of glass material, it is difficult to produce a material having a steep viscosity curve or a material having strong devitrification.
[0026]
In JP-A-61-266317, heating and transport are performed using a porous member. However, in this method, the glass material is shaped before heating, and is moved from a cube or rectangular parallelepiped glass block. Deformation into a lens shape with an arbitrary curvature radius on the lower surface is impossible.
As described above, in the methods proposed so far, the cost of the grinding and polishing method is high, and the shape cannot be adjusted by thermal deformation using surface tension.
[0027]
Accordingly, the present invention has been made in view of the above-described problems, and its purpose is to grind and polish a precision element such as an optical element having a highly accurate shape and surface accuracy directly from a molding material in a melt-softened state. It is an object of the present invention to provide a method for forming a precision element that can be obtained without post-processing such as.
Another object of the present invention is to prevent fusion at the periphery of the mold and to prevent film peeling of the mold.
[0028]
Still another object of the present invention is to provide a method for easily and reliably producing a glass lump suitable for use as an optical element molding material and having no dent on the lower surface.
Another object of the present invention is to provide a method for obtaining a shaped glass lump having a desired shape by press-molding the glass lump, which makes it possible to shorten or eliminate the reheating time prior to press molding. It is to provide a method for producing a glass lump.
[0029]
Still another object of the present invention is to produce a glass material for press molding having a required shape and capacity at a low cost.
Still another object of the present invention is to provide a molding method capable of shortening molding time and improving mold durability.
[0031]
[Means for Solving the Problems]
In order to solve the above-mentioned problems and achieve the purpose,A precision element molding method according to the present invention is a method of directly molding a precision element such as an optical element from a melt-softened molding material, and is composed of at least two mold members, and a cavity formed by them. A mold in which the shape of the molding surface for determining the shape of the precision element has a shape corrected in advance so as to be the final shape of the desired precision element, and the molding surface is made of a porous material. A step of preparing the unit, and the mold unit is opened, and fluid is ejected from the porous molding surface into the cavity, and the melt-softened molding material is formed from the nozzle for supplying the melt-softened molding material. And a molding material supplied from the nozzle onto the molding surface of the mold unit by the weight and surface tension of the molding material. Separating from the nozzle, and ejecting fluid from the molding surface, applying pressure to the mold unit in a non-contact state between the soft molding material and the molding surface, and closing the mold unit, After the molding material is brought into the corrected molding surface state to obtain a molded product having a corrected shape, and after the molding material is supplied to the mold unit, the mold unit is closed by applying pressure to the mold unit. During the process of copying the material to the shape of the molding surface, the first cooling to the molding material is started, the mold unit is closed, and after the molding material is made to conform to the shape of the molding surface, the second cooling is performed. Starting and cooling the molded product to a desired final shape to obtain the shape of the precision element; and after cooling the precision element in the mold unit, opening the mold unit and taking out the precision element; It is characterized by having It is set to.
[0033]
Further, in the precision element molding method according to the present invention, the previously corrected shape of the molding surface is given to the pressure, flow rate, temperature of the fluid ejected from the molding surface, and the temperature, viscosity, and mold unit of the molding material. It is characterized in that it can be obtained by a simulation including the pressure, temperature, and thermal expansion coefficient of the mold member forming the molding material and the molding surface as parameters.
[0034]
Further, in the precision element molding method according to the present invention, the pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape is during molding of the molding material and It is characterized in that it is obtained by processing the molding data and shape data after the molding is completed.
In the precision element molding method according to the present invention, the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface.
[0035]
Further, in the precision element molding method according to the present invention, at least one of the fluid ejection pressure, the fluid flow rate, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. It is characterized by.
In the precision element molding method according to the present invention, when a pressure is applied to the mold unit to pressurize the molding material, the mold member constituting the mold unit is rotated and slid with respect to the molding material, and the molding material, the molding surface, It is characterized by controlling the pressure of the fluid existing between the two.
[0036]
The precision element molding method according to the present invention is a method for molding a precision element such as an optical element, which is composed of at least two mold members and determines the shape of the precision element of the cavity formed by them. A mold made of a porous material having a shape that has been corrected in advance so that the shape of the molding surface is the final shape of the desired precision element, and that the molding surface is finished in a mirror state A step of preparing a unit, and a step of preparing a molding material finished so that there is no sharp step with a height difference of 5 μm or more on the surface of a portion corresponding to a portion that becomes a functional surface after molding, The mold unit is opened, the molding material is supplied to the mold unit, fluid is ejected from the porous molding surface into the cavity, and the molding material is heated in a non-contact state with the molding surface. The process of softening, the fluid is ejected from the molding surface, the mold unit is closed with the softened molding material and the molding surface kept in a non-contact state, and the molding material is corrected to the shape of the molding surface of the mold member. And obtaining a preform having a shape approximate to the shape of the molding surface, and a viscosity in the vicinity of the surface of the preform is 107.6When the pressure reaches dPa · s or more, the ejection of fluid from the molding surface is stopped, pressure is applied to the mold unit to close it, and pressure is applied while the preformed product and the molding surface of the mold member are in contact with each other. A step of matching the shape of the product with the shape of the molding surface to obtain a corrected precision element, and a viscosity of at least the surface of the corrected precision element is 108When the pressure becomes dPa · s or more, the process of resuming the ejection of fluid from the molding surface and providing a gap between the precision element and the molding surface, and immediately after heating and softening the molding material, Before the obtaining step, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the corrected precision element, and the ejection of fluid from the molding surface was resumed. Immediately after that, the third cooling is started and the molded product is cooled until the desired final shape is obtained to obtain the shape of the precision element, and the surface of the element and the molding during the second cooling. Match the shrinkage of the element to maintain the close contact of the surface.TypeAnd a step of following the member and a step of opening the mold unit and taking out the precision element after the cooling of the precision element in the mold unit is completed.
[0037]
Further, in the precision element molding method according to the present invention, the previously corrected shape of the molding surface forms the molding material temperature, viscosity, pressure applied to the mold unit, temperature, and molding material and molding surface. It is characterized by being obtained by simulation including at least one coefficient of thermal expansion of the mold member as a parameter.
Further, in the precision element molding method according to the present invention, the pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape is during molding of the molding material and It is characterized in that it is obtained by processing the molding data and shape data after the molding is completed.
[0038]
In the precision element molding method according to the present invention, the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface.
Further, in the precision element molding method according to the present invention, at least one of the fluid ejection pressure, the fluid flow rate, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. It is characterized by.
[0039]
Further, in the precision element molding method according to the present invention, the mold constituting the mold unit is configured to apply pressure to the mold unit to press the molding material in a non-contact state and to cool in the mold after transferring the shape. It is characterized in that the member is rotated and slid with respect to the molding material, and the pressure of the fluid existing between the molding material and the molding surface is controlled.
[0040]
Further, the precision element molding method according to the present invention is a method of directly molding a precision element such as an optical element from a melt-softened molding material. The precision element molding method includes at least two mold members and is formed by them. The shape of the molding surface that determines the shape of the precision element of the cavity has a shape that has been corrected in advance to be the final shape of the desired precision element, and the molding surface is finished in a mirror state. A step of preparing a mold unit made of a porous material, and opening the mold unit to eject a fluid from the porous molding surface into the cavity and supplying a melt-softened molding material, The mold unit is formed from the nozzle by the process of supplying the mold material in the melt-softened state to the mold unit in a non-contact state with the molding surface, and the weight and surface tension of the molding material. The process of separating the molding material supplied on the surface, the fluid is ejected from the molding surface, the mold unit is closed while the softened molding material and the molding surface are kept in a non-contact state, and the molding material is molded And a step of obtaining a preform having a shape approximate to the shape of the molding surface according to the corrected shape of the molding surface, and the viscosity in the vicinity of the surface of the preform is 107.6When the pressure reaches dPa · s or more, the ejection of fluid from the molding surface is stopped, pressure is applied to the mold unit to close it, and pressure is applied while the preformed product and the molding surface of the mold member are in contact with each other. The process of aligning the shape of the product with the shape of the molding surface to obtain a precision element with a corrected shape, and immediately after separating the molding material from the nozzle to the step of obtaining the preformed product, A process of starting the second cooling immediately after obtaining the precision element having the corrected shape, and at least the surface of the precision element having the corrected shape at the time of the second cooling. A step of following the mold member in accordance with the contraction of the element so as to maintain the adhesion between the surface of the element and the molding surface while the adhesion force is acting between the molding surface and at least the surface of the element Cool until the adhesion between the mold and the molding surface is eliminated. Thereafter, a step of opening the mold unit and taking out a molding element having a shape approximating the desired shape, and a step of further cooling the molding element having a shape approximating the desired shape to room temperature to obtain a precision element having the desired shape are obtained. It is characterized by having.
[0041]
Further, in the precision element molding method according to the present invention, the previously corrected shape of the molding surface forms the molding material temperature, viscosity, pressure applied to the mold unit, temperature, and molding material and molding surface. It is characterized by being obtained by a simulation including the coefficient of thermal expansion of the mold member and the adhesion between the surface of the molding element and the molding surface as parameters.
[0042]
Further, in the precision element molding method according to the present invention, the pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape is during molding of the molding material and It is characterized in that it is obtained by processing the molding data and shape data after the molding is completed.
In the precision element molding method according to the present invention, the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface.
[0043]
Further, in the precision element molding method according to the present invention, at least one of the fluid ejection pressure, the fluid flow rate, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. It is characterized by.
The precision element molding method according to the present invention is characterized in that the follow-up of the mold member during the second cooling is performed by an adhesion force between the molding surface and the precision element.
[0044]
The precision element molding method according to the present invention is characterized in that the follow-up of the mold member during the second cooling is performed by applying pressure to the mold member.
[0045]
The precision element molding method according to the present invention is a method for molding a precision element such as an optical element, which is composed of at least two mold members and determines the shape of the precision element of the cavity formed by them. A mold made of a porous material having a shape that has been corrected in advance so that the shape of the molding surface is the final shape of the desired precision element, and that the molding surface is finished in a mirror state A step of preparing a unit, and a step of preparing a molding material finished so that there is no sharp step with a height difference of 5 μm or more on the surface of a portion corresponding to a portion that becomes a functional surface after molding, The mold unit is opened, the molding material is supplied to the mold unit, fluid is ejected from the porous molding surface into the cavity, and the molding material is heated in a non-contact state with the molding surface. The process of softening, the fluid is ejected from the molding surface, the mold unit is closed with the softened molding material and the molding surface kept in a non-contact state, and the molding material is corrected to the shape of the molding surface of the mold member. To obtain a preform having a shape approximate to the shape of the molding surface, and when the viscosity in the vicinity of the surface of the preform becomes 107.6 dPa · s or more, the fluid from the molding surface Stop spraying, close the mold unit by applying pressure, pressurize the preformed product and the molding surface of the mold member in contact with each other, and adjust the shape of the preformed product to the shape of the molding surface. The first cooling to the molding material is started between the process of obtaining the precision element and the process immediately after heating and softening the molding material to the process of obtaining the preform, and the precision element of the corrected shape is further obtained. A step of starting the second cooling immediately after being obtained; When cooling the element, at least while the adhesion force is acting between the surface of the precision element of the corrected shape and the molding surface, the element surface and the molding surface are kept in close contact with each other. The process of following the mold member in accordance with the shrinkage of the mold, and at least cooling until the adhesive force between the surface of the element and the molding surface is eliminated, and then opening the mold unit to approximate the desired shape And a step of obtaining a precision element having a desired shape by further cooling the molding element having a shape approximate to a desired shape to room temperature.
[0046]
Further, in the precision element molding method according to the present invention, the previously corrected shape of the molding surface forms the molding material temperature, viscosity, pressure applied to the mold unit, temperature, and molding material and molding surface. It is characterized by being obtained by a simulation including the coefficient of thermal expansion of the mold member and the adhesion between the surface of the molding element and the molding surface as parameters.
[0047]
Further, in the precision element molding method according to the present invention, the pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape is during molding of the molding material and It is characterized in that it is obtained by processing the molding data and shape data after the molding is completed.
In the precision element molding method according to the present invention, the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface.
[0048]
Further, in the precision element molding method according to the present invention, at least one of the fluid ejection pressure, the fluid flow rate, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. It is characterized by.
The precision element molding method according to the present invention is characterized in that the follow-up of the mold member during the second cooling is performed by an adhesion force between the molding surface and the precision element.
[0049]
The precision element molding method according to the present invention is characterized in that the follow-up of the mold member during the second cooling is performed by applying pressure to the mold member.
[0050]
Further, the precision element molding method according to the present invention is a method of directly molding a precision element such as an optical element from a melt-softened molding material. The precision element molding method includes at least two mold members and is formed by them. The shape of the molding surface that determines the shape of the precision element of the cavity has a shape that has been corrected in advance to be the final shape of the desired precision element, and the molding surface is finished in a mirror state. A step of preparing a mold unit made of a porous material, and opening the mold unit to eject a fluid from the porous molding surface into the cavity and supplying a melt-softened molding material, The mold unit is formed from the nozzle by the process of supplying the mold material in the melt-softened state to the mold unit in a non-contact state with the molding surface, and the weight and surface tension of the molding material. A step of separating the molding material supplied on the surface from the nozzle, and a fluid is ejected from the molding surface, and the mold unit is closed while the softened molding material and the molding surface are kept in a non-contact state. In accordance with the shape of the corrected molding surface of the mold member to obtain a preform having a shape approximate to the shape of the molding surface, and the viscosity in the vicinity of the surface of the preform is 107.6When the pressure reaches dPa · s or more, the ejection of fluid from the molding surface is stopped, pressure is applied to the mold unit to close it, and pressure is applied while the preformed product and the molding surface of the mold member are in contact with each other. A step of matching the shape of the product with the shape of the molding surface to obtain a corrected precision element, and a viscosity of at least the surface of the corrected precision element is 108When the pressure becomes dPa · s or more, the process of resuming the ejection of fluid from the molding surface and providing a gap between the precision element and the molding surface, and immediately after separating the molding material from the nozzle, Before the obtaining step, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the corrected precision element, and the ejection of fluid from the molding surface was resumed. Immediately after starting the third cooling, the process of cooling until the molded product has the desired final shape to obtain the shape of the precision element, and the surface of the element and the molding surface during the second cooling A step of following the mold member in accordance with the contraction of the element so as to maintain the adhesion of the element, and a step of opening the mold unit and taking out the precision element after the cooling of the precision element in the mold unit is completed. It is said.
[0051]
Further, in the precision element molding method according to the present invention, the previously corrected shape of the molding surface forms the molding material temperature, viscosity, pressure applied to the mold unit, temperature, and molding material and molding surface. It is characterized by being obtained by simulation including at least one coefficient of thermal expansion of the mold member as a parameter.
Further, in the precision element molding method according to the present invention, the pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape is during molding of the molding material and It is characterized in that it is obtained by processing the molding data and shape data after the molding is completed.
[0052]
In the precision element molding method according to the present invention, the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface.
Further, in the precision element molding method according to the present invention, at least one of the fluid ejection pressure, the fluid flow rate, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. It is characterized by.
[0053]
Further, in the precision element molding method according to the present invention, the mold constituting the mold unit is configured to apply pressure to the mold unit to press the molding material in a non-contact state and to cool in the mold after transferring the shape. It is characterized in that the member is rotated and slid with respect to the molding material, and the pressure of the fluid existing between the molding material and the molding surface is controlled.
[0054]
The optical element molding method according to the present invention is a method of molding an optical element by pressing a weight-adjusted glass material with a molding die, wherein the molding die is at least within the effective beam diameter of the optical element. The first mold member for forming the second mold member and the second mold member for forming the other part, while flowing the gas to the molding surface via the inside or the surface of the second mold member It is characterized by molding.
[0055]
In the optical element molding method according to the present invention, the second mold member and the optical element molded during press molding are not in contact with each other through a gas layer.
In the method of molding an optical element according to the present invention, the second mold member is porous ceramic, porous metal, or porous carbon.
[0056]
In the optical element molding method according to the present invention, the difference between the temperature of the gas passing through the second mold member constituting the upper mold and the temperature of the gas passing through the second mold member constituting the lower mold is It is characterized by being 10 ° C. or higher.
[0062]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a schematic view of a molding apparatus used in the first embodiment. In FIG. 1, reference numeral 1 denotes a mold unit, which is schematically composed of a lower mold component 2 and an upper mold component 3. Each of the lower mold component 2 and the upper mold component 3 includes a lower mold member 11, an upper mold member 21, a lower mold holder 12 and an upper mold holder 22 for holding them. The lower mold holder 12 and the upper mold holder 22 are provided with pressure chambers 12 a and 22 a for supplying and distributing fluid to the lower mold member 11 and the upper mold member 21 in a balanced manner. Further, heaters 13 and 23 and temperature measuring means (not shown) are embedded. Based on the detection signal of the side temperature means, the temperature of the lower mold member 11 and the upper mold member 12 and the temperature of the fluid are controlled by the controller 41 described later. Can be finally adjusted. Moreover, 11a and 21a have shown the molding surface of the lower mold | type member 11 and the upper mold | type member 21 which determine the shape of a precision element, respectively. A fluid supply pipe 31 supplies a fluid supplied from a fluid supply source (not shown) to the pressure / flow rate regulators 32a and 32b via an arrow A portion. Further, heaters 33a and 33b for adjusting the temperature of the fluid are attached to the ends of the pressure / flow rate regulators 32a and 32b, respectively. The lower mold component 2 and the upper mold component 3 are each provided with a driving device (not shown). The lower mold component 2 and the upper mold component 3 are arranged in the directions indicated by arrows Ba and Bb (up, down, left and right). And the center of the lower mold member 11 and the upper mold member 21 can be rotated at arbitrary rotational speeds in the directions of the arrows Ca and Cb. The lower mold component 2 and the upper mold component 3 and the heaters 33a and 33b are connected by heat-resistant flexible tubes 34a and 34b and rotary joints 14 and 24, and the lower mold component 2 and the upper mold are connected. It is made so as not to obstruct the movement of the component 3 in the vertical and horizontal directions and in the rotational direction. Reference numeral 41 denotes a controller that controls the temperature of the heaters 13 and 23 and the flow rate, pressure, and temperature of the fluid. The controller 41 is connected to the heaters 13 and 23 by signal lines 44a and 44b, and the signal lines 42a, 42b, 43a, and 43b is connected to pressure / flow rate regulators 32a, 32b and heaters 33a, 33b.
[0063]
FIG. 2 is a diagram showing a process of discharging the melt-softened molding material from the supply nozzle and supplying it to the mold unit 1 and separating the supplied molding material from the nozzle. In FIG. 2, 101 is a supply nozzle for discharging the molding material 102 in a melt-softened state, 102b is a molding material block before separation supplied onto the molding surface 11a of the lower mold member 11, and 102c is molding. The constriction part made between the raw material 102 and the molding raw material lump 102b before separation is shown. Reference numeral 102a denotes a molding material lump after being separated from the supply nozzle 101 obtained on the molding surface 11a.
[0064]
FIG. 3 schematically shows a method of correcting the molding surface of the mold unit. In FIG. 3, 201 represents the shape that the precision element finally needs. Reference numeral 202 denotes a state in which the molding material is heated and expanded, and in this state, the shape of the molding surface 204 of the mold member is transferred to the surface of the molding material (precision element) through the fluid thin film 203. The fluid forming the thin film 203 is ejected from the molding surface. The shape of the molding surface 204 is corrected by adding the thickness of the fluid thin film 203 to the shape 202 required at the time of transferring the shape of the precision element to correct the radius of curvature. Reference numeral 205 denotes a correction amount for canceling deformation caused by sink marks or the like generated when the molding material is cooled from a high temperature state immediately after the shape transfer. That is, when the precision element is cooled after the shape transfer, the central portion thereof is dented due to sink marks or the like, and in order to cancel this, the molding surface of the mold member is further indicated by 206 in the shape indicated by 204 as indicated by 206. An excavation is added. As a result, when the shape of the molding surface is transferred at a high temperature, the center portion of the surface of the molding material protrudes by an amount indicated by 205. However, as the molding material is cooled, this protrusion is retracted due to sink marks. Go and finally settle down to the required shape 201. The shapes 204 and 206 of the molding surface are required at a high temperature at which the shape is transferred to the molding material. At a low temperature, the shapes as shown by 207 and 207a are obtained due to thermal contraction of the mold member. . Therefore, when the mold member is manufactured, the molding surface is processed into a shape as indicated by 207 and 207a.
[0065]
Next, the process of molding a precision element using the above molding apparatus will be specifically described with reference to the drawings. The precision element molded here is used for a video camera, and is a biconvex spherical lens having an optically effective surface with radiuses of curvature of R20 mm and R35 mm, a center thickness of 3 mm, and an outer diameter of Φ14 mm. The molding material has 10 when the temperature is 1300 ° C.1.5dPa · s, 10 at 1200 ° C1.6dPa · s, 10 at 1100 ° C1.810 at dPa · s, 1000 ° C.2.2dPa · s, 10 at 890 ° C2.9dPa · s, 10 at 720 ° C5dPa · s, 10 at 610 ° C7.6dPa · s, 10 at 498 ° C13dAn optical glass having a viscosity characteristic with a viscosity of Pa · s was used.
[0066]
In addition, the molding surface 11a of the lower mold member 11 and the molding surface 21a of the upper mold member 21 are preliminarily simulated in consideration of deformations such as the thickness of the fluid and the shape after cooling, and the shape after cooling of the molding material. Calculation is performed, and processing is performed with correction so that the shape required for the precision element is finally realized.
Specifically, in the case of the molding surface 21a of the upper die 21, first, as shown in FIG. 3, from the theoretical shape 201 (R35mm) under the standard use condition (for example, 20 ° C.) of the lens that is a precision element, The shape of the theoretical shape 202 when the temperature is raised to the temperature at the time of transfer is calculated. That is, the shape transfer temperature during molding is set to 600 ° C., which is a temperature at which this glass exhibits a viscosity of 107.9 dPa · s, and how much the theoretical shape 201 expands is calculated, and the value is calculated theoretically. In addition to the shape 201, a theoretical shape 202 at the time of expansion is used. Next, the flow rate of the fluid, the viscosity of the fluid, the viscosity of the glass, and the mold unit are set such that the thickness of the fluid film 203 interposed between the molding surface 21a and the theoretical shape 202 when expanded is about 5 μm on average. It is calculated from the pressure applied to. Then, the thickness distribution of the fluid film 203 when the molding is performed under these conditions is newly calculated by simulation, and the obtained film thickness distribution of the fluid film 203 is added to the theoretical shape 202 at the time of expansion, and at the time of shape transfer. The theoretical shape 204 of the molding surface is determined. Next, the amount of deformation such as sink marks due to cooling after shape transfer is calculated. In this calculation, the temperature distribution of the glass is determined based on the temperature of the fluid and the mold unit that changes from the shape transfer temperature and the temperature of the glass unit, the heat held by the glass, and the thermal conductivity. And the amount of sink marks is calculated from the stress relaxation coefficient of the glass. The amount of this sink is superposed on the theoretical shape 204 of the molding surface as a correction amount 205 to determine a partial correction shape 206 of the molding surface during shape transfer. Further, the amount of correction due to heat shrinkage of the material of the molding surface is calculated and superimposed on the theoretical shape 204 of the molding surface of the shape transfer temperature and the theoretical shape 206 of correction due to sink marks, so that the final theory of the molding surface in the cold state is calculated. The shapes 207 and 207a are determined. Based on this final theoretical shape, the molding surface 21a of the upper mold member 21 was processed into a mirror surface state in which the surface excluding the recess of the porous hole portion was Rmax 0.3 microns or less. Further, the molding surface 11a of the lower mold member 11 was processed for its shape by the same method. As the material of the mold members 11 and 21, porous carbon having a porosity of 30% and a maximum hole diameter of 8 microns is used, and nitrogen gas is used for the fluid to prevent oxidation of the mold members 11 and 21. It was.
[0067]
Next, the mold members 11 and 21 prepared as described above were attached to the molding apparatus shown in FIG. 1, and a softened glass lump was obtained by the method shown in FIG. Here, this process will be described more specifically with reference to FIG.
First, a glass material is melted in a glass melting furnace (not shown), and after defoaming and homogenization steps, a homogeneous molten glass 102 that is a softened molding material is obtained. It is guided to a molding material supply nozzle 101 provided at the end of the glass melting furnace. The supply nozzle 101 is set to a temperature of 1200 ° C. and the molten glass 102 is caused to flow out, and the lower mold component 2 is moved directly below the supply nozzle 101, and a predetermined surface is formed on the molding surface 11a as shown in FIG. After receiving the capacity glass, the lower mold component 2 is slightly lowered downward as shown by an arrow D as shown in FIG. 2 (b), and between the supply nozzle 101 and the glass lump 12b which is the lump of the molding material before cutting. The neck portion 102c is generated. In this state, the process waits until the glass 102c is separated by its own weight and surface tension (the state shown in FIG. 2C), thereby obtaining a glass lump 102a which is a softened molding lump.
[0068]
Thus, by temporarily stopping the lower mold component 2 in the separation step 102, the constricted portion 102c is less likely to be cooled and can be naturally separated by its own weight and surface tension. Therefore, no destructive defect is generated on the surface of 102a without leaving a cut mark or a break mark in which the molding material is solidified in the separation portion. Further, the temperature of the fluid (nitrogen gas) at this time is such that the temperature near the glass transition point is 500 ° C. when the glass is received by the molding surface 11a, and 600 ° C. immediately thereafter. Adjust the temperature of 13. Further, the flow rate of nitrogen gas was controlled by the pressure / flow rate regulator 32a so that the flow rate was 20 liters per minute until immediately before the molten glass 102 was received by the molding surface 11a, and then 5 liters per minute. By doing in this way, before the molten glass 102 reaches the molding surface 11a, the tip of the glass 102 is somewhat cooled and solidified, and the flow rate of nitrogen gas is increased, so that the tip of the molten glass 102 is completely in contact with the molding surface 11a. In addition, a glass lump 102a having no defects on the surface was obtained due to a synergistic effect with the use of the above-described separation method.
[0069]
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the molding surface 11a of the glass lump 102a is 10.6-107.5dPa · s, the viscosity in the vicinity of other surfaces is 103~6dPa · s, while the vicinity of the center is sufficiently soft, the flow rate of nitrogen gas ejected from the molding surface 11a and the molding surface 21a is 20 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 3.2 mm. The mold unit 1 was closed at a speed of 5 mm per second until Next, the temperature and flow rate of nitrogen gas are set to 600 ° C. and 10 liters per minute, and when the center thickness of the lens in the cold state is at a position corresponding to 3 mm, the pressure for closing the mold unit 1 is 20 kgf. While the pressure is gradually increased, the viscosity near the lens surface is 107.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s, and the shapes of the molding surfaces 11a and 21a were transferred to the lens (end of the first cooling).
[0070]
Subsequent to the shape transfer step and the first cooling step, second cooling was performed. The nitrogen gas flow rate was kept as it was, the temperature was set to 100 ° C., and cooling was started while gradually reducing the pressure applied to the mold unit 1 to 10 kgf. After starting cooling, the viscosity near the surface of the lens is 1012The mold unit was opened when dPa · s (temperature was about 515 ° C.), and the lens was taken out with a suction hand (not shown) while nitrogen gas was being blown out from the lower mold member 11. Furthermore, the accuracy was measured for a plurality of molded lenses at a temperature of 20 ° C, which is the same temperature as the operating conditions. However, all the Asses were within 1.5 Newton rings and the habit was within 1 Newton ring. It was possible to obtain a precision that could be used sufficiently.
[0071]
In addition, the reproducibility of the switching timing of the operation such as temperature and pressurization / depressurization at the time of the plurality of moldings is within a variation range of 10 ° C. at all temperature control points, and the opening / closing speed of the mold unit 1 and the like. The variation was also within 5%, but as a result of continuing molding while further changing the conditions, the accuracy deteriorated when the temperature and speed variation range was exceeded, and the cooling rate, especially the second cooling rate, was reduced every minute. It was confirmed that when the temperature was lower than 20 ° C., it was easily affected by its own weight deformation and the pressure of nitrogen gas, and the accuracy deteriorated.
[0072]
(Second Embodiment)
Next, using the same apparatus and the same material as the first embodiment, one surface has an aspherical shape based on R50 mm and the other surface is based on R40 mm. The center thickness of the lens is 4.3 mm and the diameter is Φ23 mm. A biconvex glass aspheric lens for a compact camera was molded.
[0073]
As in the first embodiment, the molding surface 11a of the lower mold member 11 and the molding surface 21a of the upper mold member 21 are processed into a shape that takes into account a number of corrections obtained by simulation before molding, and then actually Molding was performed and final correction was performed based on the shape data to determine the shape. Specifically, as in the first embodiment, in the case of the molding surface 21a of the upper die 21, as shown in FIG. 3, a shape 201 (20 ° C.) that is a standard use condition of a lens that is a precision element. For an aspherical shape based on R40 mm), the temperature at the time of shape transfer during molding is set to 600 ° C., and the amount of deformation due to temperature expansion of the glass, which is part of the first correction amount, is calculated. From the result, the shape 202 of the precision element under these conditions was obtained. Furthermore, the second correction amount is calculated and set so that the film thickness 203 including the film thickness distribution of the fluid interposed between the molding surface and the precision element at that time becomes an average thickness of about 3 microns. The basic shape 204 of the molding surface during shape transfer was determined. Next, a correction amount 205 due to sink marks due to cooling after shape transfer, which corresponds to the third correction amount, is obtained, a partial shape 206 of the molding surface at the time of shape transfer is determined, and further the first correction amount. From the amount of correction due to the temperature shrinkage of the material of the molding surface of the mold unit, which corresponds to the remaining part of the molding unit, the molding surface shapes 207 and 207a ( In FIG. 3, the shapes of hatched portions 207 and 207a were obtained. Then, based on the shape data, the molding surface 21a of the upper mold member 21 was processed into a mirror surface with the porous hole indented, and the lens was actually molded under the molding conditions determined by simulation. Next, the shape of the molded lens was measured, and the portion slightly deviated from the predetermined shape was corrected again, and finished to a smooth mirror surface state without a bulge to obtain the final shape of the molding surface 21. Further, the molding surface 11a of the lower mold member 11 was processed for its shape by the same method. The mold members 11 and 21 are made of porous AlO having a porosity of 25% and a maximum hole diameter of 6 microns.3And clean air was used as the fluid.
[0074]
Next, the mold members 11 and 21 prepared as described above were attached to the molding apparatus shown in FIG. 1, and a glass lump 102a was obtained in exactly the same manner as in the first embodiment.
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the lower mold member 11 of the glass lump 102a is 10.6-107.5While the viscosity in the vicinity of dPa · s and other surfaces is 103 to 106 dPa · s, and the vicinity of the center is sufficiently soft, the flow rate of air ejected from the molding surfaces 11a and 21a is 25 liters per minute, and the temperature is the viscosity of the glass. 106.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 4. The mold unit 1 was closed at a speed of 8 mm per second until 6 mm. Next, when the temperature and flow rate of the blown air are set to 600 ° C. and 15 liters per minute, and the center thickness of the lens when cold is at a position corresponding to 4.3 mm, the pressure for closing the mold unit 1 is 45 kgf. While increasing the pressure gradually, the viscosity near the lens surface is 10 at the same time.7.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s, and the shapes of the molding surfaces 11a and 21a were transferred to the lens (end of the first cooling).
[0075]
Subsequent to the shape transfer step and the first cooling step, second cooling was performed. The air flow rate was kept as it was, the temperature was set to 150 ° C., and cooling was started while gradually reducing the pressure applied to the mold unit 1 to 20 kgf. After starting cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature is about 515 ° C.), the pressure on the mold unit 1 is released and the flow rate is set to 7 liters per minute to continue cooling, so that the lens surface temperature is 498 ° C. (glass viscosity of 1013The mold unit was opened at a position lower than dPa · s), and the lens was taken out. The mold unit 1 was opened, and the lens was taken out with a suction hand (not shown) while air was being blown out from the lower mold member 11. Furthermore, this molding is repeated several times, and the reproducibility of the temperature, pressurization / decompression timing, etc. at this time is in the temperature range of 5 ° C, and the molding is performed while strictly controlling so that the variation in speed is within 3%. Carried out. After that, the accuracy of the completed lenses was measured at a temperature of 20 ° C., but all the asses were 1 Newton ring and the habit was less than 0.5 Newton rings, and better results than the first embodiment were obtained. I was able to get it.
[0076]
(Third embodiment)
Next, using the molding apparatus using the mold member shown in FIG. 4 in the first embodiment, the diameter is Φ10 mm, the convex radius of curvature is R20 mm, the concave radius of curvature is R30 mm, and the central wall thickness is 3.3 mm. A convex meniscus lens having a peripheral edge thickness of about 3.1 mm was molded. Here, in FIG. 4, 211 and 221 are a lower mold member and an upper mold member, respectively, and molding surfaces 211a and 221a forming an optical surface of the lens are processed. Further, ring members 216 and 226 having molding surfaces 216a and 226a that form the lower and upper portions of the periphery of the lens are attached to the outer periphery of the lower mold member 211 and the upper mold member 221, respectively. The lower mold member 211 and the upper mold member 221 have a porosity of 15% and a maximum hole diameter of 15 microns, and the ring members 216 and 226 have porous silicon nitride having a porosity of 10% and a maximum hole diameter of 20 microns. The fluid can be independently supplied to each pressure chamber 12b, 12c, 22b, 22c from a supply device (not shown), and the molding surface and the peripheral edge of each optical surface The film thickness of the fluid between the molding surface of the part and the molding material can be controlled independently. Moreover, the same glass material as 1st Embodiment was used for the shaping | molding raw material, and nitrogen gas was used as a fluid.
[0077]
In this embodiment, the shapes of the molding surfaces 211a and 221a of the optical surface of the lens and the molding surfaces 216a and 226a of the peripheral portion are once processed by preliminarily processing the cold shape of the lens on the molding surface, The correction processing amount of the molding surface was calculated so as to correct the shape error of the molded optical element, and it was reflected again on the shape of the molding surface and processed again to finish it in a mirror surface state. The temperature during shape transfer in the preforming was 610 ° C., and the film thickness of the nitrogen gas was 10 microns at the optical surface and about 20 microns at the periphery.
[0078]
Next, the mold members 211, 211, 216, and 226 prepared in this way were attached to the molding apparatus shown in FIG. 1 similarly to the first embodiment, and a softened glass lump was obtained by the same method. The temperature of the nitrogen gas at this time is 500 ° C., which is the temperature near the glass transition point when the glass is received on the molding surface 211a, and immediately after that, the viscosity of the glass is 10%.7.3The temperature is adjusted to 620 ° C. which is a temperature corresponding to dPa · s, and the flow rate of nitrogen gas is 18 liters per minute on the molding surface 211a until just before the molten glass 102 is received on the molding surface 211a. The surface 216a was controlled to be 8 liters per minute, and thereafter, both were 5 liters per minute.
[0079]
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the lower mold member 211 of the glass lump 102a is 10.5.6-107dPa · s, the viscosity in the vicinity of other surfaces is 103-105.6The flow rate of nitrogen gas ejected from the molding surfaces 211a and 221a is 20 liters per minute and the flow rate from the molding surfaces 216a and 226a is 14 liters and 12 liters per minute respectively while the center is sufficiently soft. And the temperature is 10 as the viscosity of the glass.5.8The temperature is set to 680 ° C. corresponding to dPa · s (first cooling start), and the rotational speed is 200 rpm in the rotational direction in which the lower mold component 2 and the upper mold component 3 are rotated in the opposite directions. The mold unit 1 was closed at a speed of 8 mm per second until the center thickness of the glass lump 102a reached 3.5 mm while gradually increasing the rotation speed so that Next, in a state where the lower mold component 2 and the upper mold component 3 are kept rotating, the temperature of the nitrogen gas is 610 ° C., the flow rate from the molding surfaces 211a and 221a is 15 liters per minute, the molding surfaces 216a and 226a The flow rate is set to be 12 liters and 11 liters per minute, respectively, and when the center thickness of the lens in the cold state is at a position corresponding to 3.3 mm, the pressure for closing the mold unit 1 is 25 kgf. While increasing the pressure gradually, the viscosity near the surface of the lens is 10 at the same time.7.6The mold unit 1 was closed while adjusting the speed so as to be dPa · s, and the shapes of the molding surfaces 211a and 221a were transferred to the lens (end of the first cooling).
[0080]
In the above molding step, the lower mold component 2 and the upper mold component are rotated in opposite directions for the following reason. That is, the pores of the porous material are not completely uniform and often non-uniform when viewed microscopically, and therefore the flow rate and pressure distribution of the fluid tend to be non-uniform. This non-uniformity such as pressure leads to non-uniform film thickness of the fluid and affects the shape of the molded product. In order to avoid this influence, the mold and the glass material are relatively rotated, the mold and the molding surface facing it are shifted, and the film is made uniform.
[0081]
Subsequent to the shape transfer step and the first cooling step, second cooling was performed. Here, the flow rate of the nitrogen gas and the rotation of the lower mold component 2 and the upper mold component 3 remain unchanged, the temperature is set to 150 ° C., and the pressure applied to the mold unit 1 is gradually reduced to 13 kgf. Cooling was started. After starting cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature is about 515 ° C.), the rotation of the lower mold component 2 and the upper mold component 3 is stopped, and at the same time, the mold unit is opened and nitrogen gas is blown out from the lower mold member 211. Then, the lens was taken out with a suction hand (not shown). Furthermore, the accuracy was measured at a temperature of 20 ° C, which is the same temperature as the use conditions, for a plurality of molded lenses, but all of them were within 1 Newton ring and a habit of less than 0.5 Newton rings. Accurate accuracy could be obtained.
[0082]
In addition, the reproducibility of the switching timing of the temperature and the operation such as pressurization / depressurization at the time of the plurality of moldings is within a variation range of 10 ° C. at all temperature control points, and the opening / closing speed of the mold unit and the lower mold configuration The variation in the number of revolutions of the member 2 and the upper mold component 3 was also within 5%. However, as a result of continuing the molding while slightly changing the conditions, the accuracy deteriorates when the temperature and speed variation ranges are exceeded. It was confirmed.
[0083]
(Fourth embodiment)
Next, an embodiment in which the same material as that of the first embodiment is molded from a glass block whose weight has been adjusted in advance as shown in FIG. 5 will be described. The molding surface 11a of the lower mold 11 and the molding surface 21a of the upper mold 21 were obtained by processing the shapes in the same manner as in the first embodiment and using them.
[0084]
First, a glass lump is cut out from the same glass block as used in the first embodiment, and is further ground and polished to a volume of 311 mm.3The glass lump is finished into a glass lump, and a flame treatment with a burner is performed on the part other than the ground and polished surface of the lump, thereby removing a sharp step of 5 microns or more on the surface of the lump. With a capacity of 311 mm3A glass lump was obtained.
[0085]
Next, this glass lump is placed on the molding surface 11a on which nitrogen gas is ejected 30 liters per minute, and then the temperature of the nitrogen gas is set to 10 by the viscosity of the glass by the heater 13 and the heater 33a.5.4The glass lump was heated to 700 ° C., which is a temperature corresponding to dPa · s. At this time, the upper mold component 3 was also moved directly above the lower mold component 2, and a nitrogen gas having the same temperature was allowed to flow, so that the glass lump was heated from above. In this way, the viscosity is 10 with no harmful defects on the surface.6A dPa · s softened glass lump 102a was obtained.
[0086]
Next, as in the first embodiment, the flow rate of nitrogen gas injected from the molding surfaces 11a and 21a is 20 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s, and the glass wall 102a has a thickness of 5 mm per second until the center thickness becomes 3.2 mm. Mold unit 1 was closed at speed. Then, through the same process as in the first embodiment, the lens was molded and the accuracy was measured. As a result, the same result as that obtained in the first embodiment was obtained, and it was also harmful to the lens surface. There were no defects.
[0087]
Furthermore, as a result of continuing molding while slightly changing the conditions of the surface treatment of the glass lump prepared first, if the step remaining on the surface exceeds 5 microns or an acute step remains, the surface is softened after heating and softening. It takes a long time to make it smoother, and in some cases, this heat softening does not eliminate the step, leaving defects on the lens surface after molding, and it has been confirmed that this is a serious problem in practice. It was.
[0088]
(Fifth embodiment)
Next, an embodiment in which the same material as that of the third embodiment is formed from a glass block whose weight has been adjusted in advance as shown in FIG. 5 will be described. The molding surface 211a of the lower mold 211, the molding surface 221a and the molding surface 226a of the upper mold 221 were obtained by processing the shape in the same manner as in the third embodiment.
[0089]
First, a glass lump is cut out from the same glass block used in the first embodiment, and is further ground and polished by 250 mm in volume.3The glass lump is finished into a glass lump, and a flame treatment with a burner is performed on the part other than the ground and polished surface of the lump, thereby removing a sharp step of 5 microns or more on the surface of the lump. With a capacity of 250mm3A glass lump was obtained.
[0090]
Next, after placing this glass lump on the molding surface 211a on which nitrogen gas is ejected at 25 liters per minute, the temperature of the nitrogen gas is set to 10 as the viscosity of the glass.5.4The glass lump was heated to 700 ° C., which is a temperature corresponding to dPa · s. At this time, the upper mold component 3 was also moved immediately above the lower mold component 2, and nitrogen gas having the same temperature was passed through the molding surfaces 216a, 221a, and 226a, and the glass block was heated from the upper and lower sides and the outer periphery. In this way, the viscosity is 10 with no harmful defects on the surface.6A dPa · s softened glass lump 102a was obtained.
[0091]
Next, as in the third embodiment, the flow rate of nitrogen gas injected from the molding surfaces 211a and 221a is 20 liters per minute and the flow rate from the molding surfaces 216a and 226a is 14 liters and 12 liters per minute, respectively. The viscosity of the glass is 105.8The temperature is set to 680 ° C. corresponding to dPa · s, and further, the lower mold component 2 and the upper mold component 3 are rotated in such a direction that they are opposite to each other and the rotation speed is 200 rpm. While increasing the speed, the mold unit 1 was closed at a speed of 8 mm per second until the central thickness of 102a reached 3.5 mm.
[0092]
Next, in the same manner as in the third embodiment, with the upper mold component 2 and the lower mold component 3 kept rotating, the temperature of the nitrogen gas is 610 ° C., and the flow rates from the molding surfaces 211a and 221a are every minute. 15 liters, the flow rate from the molding surfaces 216a and 226a is set to be 12 liters and 11 liters per minute, respectively, and when the center thickness of the lens when cold is at a position corresponding to 3.3 mm, While gradually increasing the pressure to close the unit 1 to 25 kgf, at the same time, the viscosity near the lens surface is 107.6The mold unit 1 was closed while adjusting the speed so as to be dPa · s, and the shapes of the molding surfaces 211a and 221a were transferred to the lens. Then 1012When the lens was taken out with dPa · s and the accuracy was measured, the same result as the result obtained in the third embodiment was obtained, and no harmful defects were found on the lens surface. Similar results were obtained for the surface condition of the previous glass block.
[0093]
Then
The first to fifth embodiments can be summarized as follows. In the first method, the first step is the precision element at the temperature when transferring the molding shape of the precision element, when using the precision element, or when processing the mold unit. The amount of heat shrinkage including the amount of difference in shape due to the difference in thermal expansion between the mold unit and the mold unit, and the occurrence position and amount of precision element sinks due to uneven heat distribution during molding and cooling are determined in advance in the mold. By correcting, the molded precision element can obtain a desired shape. At this time, the thickness of the fluid existing between the molding surface and the precision element is also corrected. Also, the molding surface of the mold unit is made of a porous material, and air or N is directed from the molding surface to the molding material.2It is possible to prevent contact between the molding material and the molding surface by ejecting a fluid such as gas and forming a very thin fluid film on the molding surface. For this purpose, the porous material is made of a material having a maximum pore diameter of 20 microns or less, preferably 10 microns or less and a porosity of 10 to 35%. The surface of the molding surface is processed into a smooth mirror surface with no bulge so that the fluid film is not broken and the molding material is not damaged. Is required.
[0094]
Next, the second step prevents contact between the mold and the molding material, in particular, contact between the molding material and the mold, which is likely to occur when the molding material with an indefinite melt-softened shape is discharged from the nozzle and supplied to the mold. Further, at this time, contact can be reliably prevented by lowering the temperature of the fluid temporarily ejected or increasing the flow rate. Also, when separating the molding material supplied on the molding surface of the mold unit from the nozzle, after receiving the required amount of molding material on the mold unit, the mold unit is once lowered and the molding material on the mold unit By forming a constriction between the nozzle and the molding material flowing out from the nozzle, and further developing and separating the necking due to the weight and surface tension of the molding material, there is no defect on the mold unit that can be affected after molding. There can be obtained a molding material lump having a very smooth surface.
[0095]
Next, in the third step, it is possible to prevent the contact between the molding surface and the molding material by closing the mold unit while ejecting fluid from the molding surface of the mold. It is possible to prevent defects due to rapid cooling due to contact. Further, at this time, the transfer of a stable shape can be obtained by reliably reproducing the closing speed, timing, pressure, flow rate / pressure, temperature, and the like of the fluid to be ejected. Mold unit with 10 molding materials3-109When forming a highly accurate element with a fluid film thickness of 20 microns or less when the mold unit is closed after closing in the temperature range showing the viscosity of dPa · s, preferably 3 The pressure and flow rate of the fluid are controlled to be less than a micron, and at the same time, the pressure and speed at which the mold is closed are also controlled in inverse proportion to the temperature of the molding material so that the film thickness of the fluid is within the above range. By this, the molding material is arranged in the corrected shape of the molding surface. Further, the operation when closing the mold unit is preferably controlled in accordance with the temperature of the molding material, and the temperature variation in each operation is 10 ° C. or less, preferably 5 ° C. or less, and the fluid to be ejected similarly. It is desirable to keep the temperature of the mold within the same range, the flow rate and pressure variation of the fluid and the variation of the speed and pressure of closing the mold unit are within 5%, preferably within 3%. It becomes possible to more stably obtain the transferability of the shape of the molding surface.
[0096]
The first cooling in the next fourth step is performed to control the viscosity of the molding material and accurately transfer the corrected shape of the molding surface of the mold unit to the molding material. The cooling is gradually performed while controlling the viscosity of the molding material so that the film thickness of the fluid is obtained when the cooling of the film is completed. When the first cooling is completed, the molding material and the molding surface of the mold unit coincide with each other with the fluid film interposed therebetween, thereby ensuring the shape and surface accuracy of the precision element after the cooling is completed. Further, at the time of completion of the first cooling, it is necessary to keep the molding material, the mold unit, the temperature of the fluid, and the like within the above ranges. The subsequent second cooling can be performed at a faster speed than the first cooling. In this case, the correction shape once transferred is the shape before correction by cooling, that is, the original desired shape of the precision element. Further, it is performed so that variation does not occur due to cooling shrinkage in continuous molding. For this purpose, it is necessary to accurately reproduce various conditions such as the cooling start temperature when the correction shape is determined and the temperature distribution during cooling. Similar to the above, this reproducibility is 10 times the viscosity of the molding material from the start of cooling.12Stable reproducibility can be obtained by setting the temperature variation within the temperature range indicating dPa · s to 10 ° C. or less, preferably 5 ° C. or less. In addition, the cooling rate and the temperature distribution during cooling are determined when determining the corrected shape within a range that does not cause cracks in the molding material or defects due to large birefringence. In order to prevent deformation due to the pressure of the fluid or the fluid, it is necessary to cool the surface of the precision element at a rate of 20 ° C. or more per minute, and the fluid pressure and flow rate are not changed suddenly. It is necessary to do so. Furthermore, this second cooling is a viscosity at which the molded precision element is less likely to cause deformation.12up to dPa · s. In addition, for a material that requires particularly precise transferability or a complex shape, the molding material has a viscosity that does not newly generate strain.14.5By performing up to dPa · s, more precise shape transferability can be obtained. Through the above-described cooling, at the end of this process, the shape of the molding surface of the mold unit and the shape of the molded precision element are corrected for the difference in the expansion coefficient, or corrected for sink marks in advance. The shape of the precision element is not influenced by the shape of the molding surface of the mold unit, because the molding material is almost solidified and is not in contact with the molding surface. The shape can be maintained.
[0097]
In the final fifth step, the precision element already solidified as described above is taken out by releasing the mold unit to obtain a precision element having a desired shape transferred. At this time, a film made of a fluid is interposed between the precision element and the molding surface of the mold unit, so that the surface of the precision element can be prevented from being damaged due to contact with the molding surface. In addition, the molded surface can be prevented from being damaged by contact with the solidified precision element.
[0098]
In the second method, the first step and the fourth, fifth and sixth steps are the same as the first step and the third, fourth and fifth steps of the first method. It is.
Here, the next second step is the surface of the portion corresponding to the portion that will become the functional surface after molding the molding material so that no defects will occur in the molded precision element when preparing the molding material for the precision element. Is a process of smooth finishing, and is to remove in advance an optical defect, that is, a defect that cannot be eliminated by pressure molding the surface of the part corresponding to that part. Specifically, the surface is finished so that there are no sharp steps with a height difference of 5 microns or more, and processing is performed so that there are no sharp parts when viewed microscopically such as scratches and chips. Is to do. This treatment is performed by a conventional method such as grinding and polishing, surface etching by acid treatment, softening of the surface by flame or hot air, and the like.
[0099]
By performing the following third step, it becomes possible to heat soften the molding material in a non-contact state with the molding surface of the mold unit, so that the molding surface is affected after molding on the mold unit. It is possible to obtain a softened material lump with no defects and a very smooth surface. At this time, the molding material is 103-109By heating the molding material to a temperature showing a viscosity of dPa · s, it is possible to connect to the next fourth step. Subsequent steps are the same as in the first method as described above, and a precision element having a desired shape can be finally obtained.
[0100]
Further, in the third method, the pre-corrected shape of the molding surface is obtained by changing the pressure, flow rate, temperature of the fluid, the temperature and viscosity of the molding material, and the pressure, temperature, and molding material and porosity applied to the mold unit. Simulation of the coefficient of thermal expansion of a mold member made of quality material as a parameter of molding conditions, predicting the shape of a precision element to be molded in advance, and correcting the shape of the molding surface of the mold unit based on it Thus, a precision element having a highly accurate shape and surface accuracy can be obtained. This correction combines the first correction associated with the difference in thermal expansion between the mold member and the molding material and the third correction for canceling the thickness of the fluid interposed between the molding surface of the mold unit and the molding material. Therefore, by performing this correction at the time of shape processing of the molding surface of the molding die, the shape of the precision element that has been molded and taken out from the mold unit can be matched with the desired shape.
[0101]
Here, the first correction is the molding surface of the mold member, which is generated due to the temperature difference between the shape transfer and the shape processing of the mold member or when using the precision element, and the difference in thermal expansion coefficient between the mold member and the molding material. This is correction of the amount of deviation of the shape of the precision element. Specifically, the shape change at the working temperature of the desired precision element is calculated by the expansion rate of the molding material by changing the shape of the precision element due to the temperature difference up to the shape transfer temperature. Furthermore, the amount calculated by the expansion coefficient of the mold member as the shape change amount of the mold member from the shape transfer temperature to the temperature difference during processing of the molding surface of the mold unit is calculated as the amount of change in the shape of the precision element. This is the first correction amount of the shape. The second correction is to correct the thickness of the fluid interposed between the mold member and the molding material, particularly the amount of change in shape due to the thickness and thickness distribution of the fluid during shape transfer. From the temperature and viscosity at that time, the temperature and viscosity of the molding material, the pressure applied to the mold unit, etc., the pressure distribution and film thickness of the fluid and its distribution state are calculated, and this is used to calculate the shape of the molding surface of the mold member. The amount of correction is 2. The third correction is correction of deformation due to sink marks or the like due to cooling including cooling after taking out from the mold, especially after the precision element has transferred the shape, and mainly during cooling. The temperature distribution of the molding material itself, the resulting viscosity distribution and the coefficient of thermal expansion, and the stresses calculated by them, governed by the ever-changing temperature of the fluid and mold unit, the retained heat and temperature conductivity of the molding material The amount of sink is calculated based on the stress relaxation coefficient unique to the molding material, and the amount of shape change due to the weight of the molding material or the pressure change of the fluid is calculated and added to the amount. The amount of correction.
[0102]
Furthermore, in the fourth method, an element having a shape that approximates the final shape of the desired precision element is formed in advance, and information obtained from the shape data during and after the forming is formed. By feeding back to the surface shape, an optical element having a highly accurate shape and surface accuracy can be obtained. This correction method uses a mold unit having a molding surface with a shape almost the same as the shape of a precision element first, pre-sets the element once under fixed conditions, and uses conditions after completion of molding. Compare the shape of the element in the same state with the shape of the molding surface of the used mold unit, and use the amount of the shape difference found there as a correction amount to the molding surface of the mold unit. In the case of a simple correction that can be corrected by changing, it is possible to match the molded precision element with a desired shape by correcting the molding conditions. It is also possible to obtain a more accurate and stable shape by repeating this correction several times. Further, the same effect can be obtained by combining the correction method of the molding surface of the mold unit by the above-mentioned simulation. Can be obtained.
[0103]
Furthermore, in the fifth method, the temperature of the molding material can be controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. This is because the molding material is not in contact with the mold unit, and the molding material is covered with the mold unit, and it is virtually impossible to measure the temperature of the molding material from the outside. This can be solved by controlling the temperature of the fluid that is in direct contact and indirectly controlling the temperature of the molding material through heat transfer. Temperature control can be performed. Here, as a method for controlling the temperature of the fluid, the purpose can be sufficiently achieved by directly adjusting the temperature of the fluid in the vicinity of the supply source. However, the fluid temperature is once incorporated in the mold unit or the like. By re-adjusting the temperature using a heating source such as a heater, it is possible to realize better temperature control of the molding material.
[0104]
Furthermore, in the sixth method, by controlling the ejection pressure of the fluid ejected from the molding surface of the molding die, the flow rate of the fluid, and the pressure applied to the mold unit in accordance with the viscosity of the molding material, a highly accurate shape and An optical element having surface accuracy can be obtained. Here, the fluid film between the molding surface of the mold unit and the molding material is controlled by controlling the flow rate and pressure of the fluid and the pressure applied to the mold unit in synchronization with the viscosity change corresponding to the hardness of the molding material. The thickness can be reliably controlled and controlled. As a result, the finished precision element can obtain a stable shape with higher accuracy and less variation even during continuous molding.
[0105]
Furthermore, in the seventh method, when pressurizing the molding material by applying pressure to the mold unit, the mold member constituting the mold unit is rotated and slid with respect to the molding material and exists between the molding material and the molding surface. By controlling the pressure distribution of the fluid, an optical element having a highly accurate shape and surface accuracy can be obtained. This is because it is easy to make the film thickness of the fluid between the molding material and the molding surface of the mold member uniform by rotating and sliding the mold member with respect to the molding material during pressure molding. Accurate precision elements can be obtained, and the functional surface of the lens, etc., is basically a spherical surface of the shape of the axis, especially by making the film thickness easily uniform on the axis object around the rotation axis. It is possible to exert a great effect on a precision element having a shape.
[0106]
(Sixth embodiment)
Next, another embodiment will be described in which the same material as that of the first embodiment is formed from a glass block whose weight has been adjusted in advance as shown in FIG. The molding surface 11a of the lower mold 11 and the molding surface 21a of the upper mold 21 are substantially the same as those in the first embodiment, except that the film thickness of the fluid is not considered as shown in FIG. 3A. The final temperature of the shape transfer is 109The shape obtained by setting the temperature at a viscosity of dPa · s and determining the shape was used.
[0107]
First, the mold members 11 and 21 prepared as described above are attached to the molding apparatus shown in FIG. 1, and a glass block is cut out from the same glass block as used in the first embodiment. 311mm in volume by grinding and polishing as shown in3In addition, a portion of the glass lump other than the ground and polished surface is subjected to flame treatment with a burner to remove an acute step of 5 microns or more on the surface of the glass lump. 311mm capacity with smooth surface as shown in b)3A glass lump was obtained.
[0108]
Next, this glass lump is placed on the molding surface 11a on which nitrogen gas is ejected 30 liters per minute, and then the temperature of the nitrogen gas is set to 10 by the viscosity of the glass by the heater 13 and the heater 33a.5.4The glass lump was heated to 700 ° C., which is a temperature corresponding to dPa · s. At this time, the upper mold component 3 was also moved directly above the lower mold component 2, and a nitrogen gas having the same temperature was allowed to flow, so that the glass lump was heated from above. In this way, the viscosity is 10 with no harmful defects on the surface.6A dPa · s softened glass lump 102a was obtained.
[0109]
Next, as in the first embodiment, the flow rate of nitrogen gas injected from the molding surfaces 11a and 21a is 20 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 3. The mold unit 1 was closed at a speed of 5 mm per second until 2 mm. Next, the temperature and flow rate of the nitrogen gas are adjusted to 610 ° C. (the viscosity of the glass is 10 so that the film thickness of the gas becomes about 20 microns.7.6(temperature corresponding to dPa · s) and 10 liters per minute, and when the center thickness of the lens in the cold state is at a position corresponding to 3.05 mm, the mold unit 1 is closed and While gradually increasing the pressure so that the pressure becomes 2 MPa, at the same time, the viscosity near the surface of the lens is 107.6The mold unit 1 was closed while adjusting the speed to be Pa · s to obtain a preformed product.
[0110]
Further, immediately after that, the gas ejection is stopped, and the pressure is gradually increased so that a force of 1.5 MPa and finally 2 MPa is initially applied to the molding surface of the mold unit 1, and the preform and the mold member are closed. The shape of the preform was adjusted to the shape of the molding surface while the molding surface was in contact.
In addition, immediately after obtaining the softened glass lump 102a and before obtaining a preformed product, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the preformed product. The second cooling is performed by blowing a cooling nitrogen gas from the outside of the mold unit 1 by a cooling device (not shown). At that time, the restriction from the outside to the mold components 2 and 3 is released, The mold member 11 and the upper mold member 21 can follow the contraction of the lens.
[0111]
Also, immediately after the start of the second cooling, the viscosity near the surface of the lens is 108When the pressure reaches dPa · s, the fluid is instantaneously ejected from the molding surfaces 11a and 21a at a pressure of 15 kPa, and at the same time, the mold unit 1 is slightly opened to release the lens from the molding surface, and immediately thereafter the fluid pressure Was set to 1.02 kPa, the flow rate was set to 3 liters per minute, and the third cooling was performed.
[0112]
After the start of the third cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature is about 515 ° C), the mold unit 1 is completely opened, and the lens is taken out with a suction hand (not shown) while nitrogen gas is being blown out from the lower mold member 11. It was. Furthermore, the accuracy was measured at a temperature of 20 ° C., which is the same temperature as the use conditions, for a plurality of molded lenses, but all of them were within 1.7 Newton rings and one habit of Newton rings. It was possible to obtain accuracy that could withstand normal use.
[0113]
It should be noted that the reproducibility of the temperature and the switching timing of the operation such as pressurization / depressurization at the time of the plurality of moldings is 20 ° C at all temperature control points until the completion of the second cooling. The range of variation of the product, and then within the range of variation of 30 ° C, and the variation of the opening and closing speed of the mold unit, etc. were within 5%. It was confirmed that the accuracy deteriorated when exceeding the range of variation.
[0114]
(Seventh embodiment)
Next, using the same apparatus and the same material as in the sixth embodiment, one surface has an aspherical shape based on R50 mm and the other surface is R40 mm. The center thickness of the lens is 4.3 mm and the diameter is Φ23 mm. A biconvex glass aspheric lens for a compact camera was molded.
[0115]
Similarly to the sixth embodiment, the viscosity of the glass is 10 with respect to the shape 201 at 20 ° C. as shown in FIG. 3A.12The first correction shape 204 is obtained at dPa · s (515 ° C), the correction amount 205 such as sink marks is obtained, and the viscosity of the glass is 1012A correction shape 206 at dPa · s is obtained. Further, the mold shapes 207 and 207a in the cold are determined in consideration of mold shrinkage. Then, according to the shape data, the molding surface 21a of the upper mold member 21 is processed into a mirror surface state in which the surface excluding the hollow of the porous hole portion is within 0.2 due to Newton ring deviation, The lens was actually molded under the molding conditions determined by simulation. Next, the shape of the molded lens was measured, and the portion slightly deviated from the predetermined shape was corrected again, and finished to a smooth mirror surface state without a bulge to obtain the final shape of the molding surface 21. Further, the molding surface 11a of the lower mold member 11 was processed for its shape by the same method. The mold members 11 and 21 are made of porous AlO having a porosity of 25% and a maximum hole diameter of 6 microns.3And clean air was used as the fluid. A carbon film as a release layer was deposited on the surface of the molding surface so that the porous holes were not blocked. The release layer is not particularly limited to the carbon film as long as it does not prevent the mold and the glass from being fused and loses the specularity of the molding surface.
[0116]
Next, the mold members 11 and 21 prepared as described above are attached to the molding apparatus shown in FIG. 1, the glass lump is cut out in the same manner as in the sixth embodiment, the cutting portion is polished, and the sixth embodiment is processed. In the same manner as above, a glass lump 102a in a softened state was obtained.
This glass lump 102a is 106.5When the temperature reaches dPa · s, the flow rate of air ejected from the molding surfaces 11a and 21a is 25 liters per minute and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 4. The mold unit 1 was closed at a speed of 8 mm per second until 6 mm. Next, the temperature and flow rate of the blown air are set to 600 ° C. (10% in terms of glass viscosity).7.9(temperature corresponding to dPa · s) and 15 liters per minute, and when the center thickness of the lens when cold is in a position corresponding to 4.32 mm, the mold unit 1 is closed and the pressure on the molding surface While gradually increasing the pressure so that the pressure becomes 4.5 MPa, at the same time, the viscosity near the lens surface is 107.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product. The gas thickness at this time was about 8 microns.
[0117]
Further, immediately after that, the gas injection is stopped, and the pressure is gradually increased so that a force of 2 MPa is initially applied to the molding surface of the mold unit 1 and 8 MPa is applied when the shape is first transferred, and then the preform is closed. The shape of the preform was adjusted to the shape of the molding surface while the product and the molding surface of the mold member were in contact with each other.
In addition, immediately after obtaining the softened glass lump 102a and before obtaining a preformed product, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the preformed product. At that time, pressure is applied to the mold components 2 and 3 from the outside so that the pressure becomes 8 MPa when the second cooling is completed as described above, and the lower mold member 11 and the upper mold member 21 are made thicker than the lens. The directional contraction was followed. After the start of the second cooling, the viscosity near the surface of the lens is 1012When the pressure reaches dPa · s (temperature is about 515 ° C.), the pressure applied to the lower mold member 2 and the upper mold member 3 is released, and at the same time, the fluid flows from the molding surfaces 11a and 21a as in the sixth embodiment. Was ejected to release the lens from the molding surface. Thereafter, the flow rate was further set to 7 liters, the third cooling was performed, and the temperature of the lens surface was 498 ° C. (the viscosity of the glass was 1013The mold unit 1 was completely opened when the pressure was lower than dPa · s), and the lens was taken out with a suction hand (not shown) while air was being blown out from the lower mold member 11. Furthermore, this molding is repeated several times, and the temperature and the reproducibility of the timing such as pressurization / decompression are within a temperature range of 10 ° C. until the completion of the second cooling, and then 5 ° C. Molding was carried out while strictly controlling the variation to be within 3%. After that, the accuracy of the completed lenses was measured at a temperature of 20 ° C., but all the ashes were within 1 Newton ring and the habit was within 0.5 Newton rings, which is better than the sixth embodiment. The result was obtained.
[0118]
(Eighth embodiment)
Next, using a molding apparatus using the mold member shown in FIG. 4 in the sixth embodiment, the diameter is Φ10 mm, the convex radius of curvature is R20 mm, the concave radius of curvature is R30 mm, and the central thickness is 3.3 mm. A convex meniscus lens having a peripheral edge thickness of about 3.1 mm was molded. Here, in FIG. 4, 211 and 221 are a lower mold member and an upper mold member, respectively, and molding surfaces 211a and 221a forming an optical surface of the lens are processed. Further, ring members 216 and 226 having molding surfaces 216a and 226a that form the lower and upper portions of the periphery of the lens are attached to the outer periphery of the lower mold member 211 and the upper mold member 221, respectively. The lower mold member 211 and the upper mold member 221 have a porosity of 15% and a maximum hole diameter of 15 microns, and the ring members 216 and 226 have porous silicon nitride having a porosity of 10% and a maximum hole diameter of 20 microns. The fluid can be independently supplied to each pressure chamber 12b, 12c, 22b, 22c from a supply device (not shown), and the molding surface and the peripheral edge of each optical surface The film thickness of the fluid between the molding surface of the part and the molding material can be controlled independently. Moreover, the same glass material as 6th Embodiment was used for the shaping | molding raw material, and nitrogen gas was used as a fluid. Further, the same release layer as in the seventh embodiment was used.
[0119]
In this embodiment, the shapes of the molding surfaces 211a and 221a of the optical surface of the lens and the molding surfaces 216a and 226a of the peripheral portion are once processed by preliminarily processing the cold shape of the lens on the molding surface, The correction processing amount of the molding surface was calculated so as to correct the shape error of the molded optical element, and it was reflected again on the shape of the molding surface and processed again to finish it in a mirror surface state. Further, the temperature at the time of shape transfer in the preforming is 555 ° C. (10% in terms of glass viscosity).10dPa · s).
[0120]
Next, the mold members 211, 211, 216, and 226 prepared in this way are attached to the molding apparatus shown in FIG. 1 similarly to the sixth embodiment, and further, from the same glass block used in the sixth embodiment. Then, the glass lump is cut out and the volume is 250 mm by grinding and polishing.3The glass lump is finished to a glass lump, and the part other than the ground and polished surface of the lump of glass is subjected to flame treatment with a burner, thereby removing a sharp step of 5 microns or more on the surface of the lump of glass, and a smooth surface. The capacity is 250mm3A glass lump was obtained.
[0121]
Next, after placing this glass lump on the molding surface 211a on which nitrogen gas is ejected at 25 liters per minute, the temperature of the nitrogen gas is set to 10 as the viscosity of the glass.5.4The glass lump was heated to 700 ° C., which is a temperature corresponding to dPa · s. At this time, the upper mold component 3 was also moved immediately above the lower mold component 2, and nitrogen gas having the same temperature was passed through the molding surfaces 216a, 221a, and 226a, and the glass block was heated from the upper and lower sides and the outer periphery. In this way, the viscosity is 10 with no harmful defects on the surface.6A dPa · s softened glass lump 102a was obtained.
[0122]
Immediately thereafter, the flow rate of nitrogen gas ejected from the molding surfaces 211a and 221a is 20 liters per minute, the flow rate from the molding surfaces 216a and 226a is 14 liters and 12 liters per minute, respectively, and the temperature is 10 in terms of glass viscosity.5.8The temperature is set to 680 ° C. corresponding to dPa · s (first cooling start), and the rotational speed is 200 rpm in the rotational direction in which the lower mold component 2 and the upper mold component 3 are rotated in the opposite directions. The mold unit 1 was closed at a speed of 8 mm per second until the center thickness of the glass lump 102a reached 3.5 mm while gradually increasing the rotation speed so that Next, in a state where the lower mold component 2 and the upper mold component 3 are kept rotating, the temperature of the nitrogen gas is 610 ° C., and the flow rate from the molding surfaces 211a and 221a is adjusted every minute so that the film thickness is about 12 microns. When the flow rate from the 15 liters and the molding surfaces 216a and 226a is set to 12 liters and 11 liters per minute, respectively, and the center thickness of the lens when cold is at a position corresponding to 3.33 mm, While gradually increasing the pressure so that the pressure for closing the unit 1 is 2.5 MPa on the molding surface, at the same time, the viscosity near the surface of the lens is 107.6The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product.
[0123]
Further, immediately after that, the ejection and rotation of the gas are stopped, and the viscosity near the surface of the lens is 10%.8.5When the pressure reaches dPa · s, the molding surface of the mold unit is further closed by applying a pressure of 5 MPa, and pressure is applied while the preformed product and the molding surface of the mold member are in contact with each other. Matched to the shape of the molding surface.
Following the first cooling step until the above preformed product is obtained, the second cooling is performed in the same manner as in the sixth embodiment immediately after obtaining the preformed product. At that time, pressure is gradually applied to the mold constituent members 2 and 3 from the outside to the molding surface from the pressure of 5 MPa as described above to 7.5 MPa when the second cooling is completed, and the mold members 11 and 21 are then applied. Was made to follow contraction in the thickness direction of the lens. After the start of cooling, when the viscosity in the vicinity of the lens surface reaches 1010 dPa · s (temperature is about 555 ° C.), fluid is ejected from the molding surfaces 11a and 21a as in the sixth embodiment, and at the same time, the mold configuration The pressure applied to the members 2 and 3 was released, and the lens was released. Immediately thereafter, the fluid temperature was set to 150 ° C., the flow rate was set to 5 liters per minute, and at the same time, the mold components 2 and 3 were rotated at a speed of 150 rpm in the direction of rotation in which the directions were opposite. The third cooling was carried out while making the fluid film thickness uniform. The viscosity of the glass is 1013At the same time as dPa · s was exceeded, the mold components 2 and 3 were stopped, and at the same time, the mold unit 1 was opened, the lens was taken out, and cooled to room temperature. Furthermore, the accuracy was measured at 20 ° C, which is the same temperature as the operating conditions, for a plurality of molded lenses, but all the Asches were 1.2 Newton rings and the habits were less than 0.5 Newton rings. Enough accuracy could be obtained. In addition, the reproducibility of the temperature and the switching timing of the operation such as pressurization / depressurization during the plurality of moldings is within the same range as in the sixth embodiment, and the opening / closing speed and lowering of the mold unit are reduced. Variations in the rotational speed of the mold component 2 and the upper mold component 3 were also within 5%. However, as a result of continuing molding while further changing the conditions, the accuracy would be exceeded if the temperature and speed variations were exceeded. It was confirmed that it would get worse.
[0124]
The sixth to eighth embodiments can be summarized as follows. In the eighth method, the first step is the precision element at the temperature when transferring the molding shape of the precision element, when using the precision element, or when processing the mold unit. The amount of heat shrinkage including the amount of difference in shape due to the difference in thermal expansion between the mold unit and the mold unit, and the occurrence position and amount of precision element sinks due to uneven heat distribution during molding and cooling are determined in advance in the mold. By correcting, it is possible to obtain the desired shape of the molded precision element. At this time, the fluid existing between the molding surface and the preform when the preform is obtained It is also necessary to correct the thickness. In addition, the molding surface of the mold unit is made of a porous material, and a fluid such as air or N2 gas is ejected from the molding surface toward the molding material to form a very thin fluid film on the molding surface. Contact between the softened molding material and the molding surface can be prevented. For this purpose, the porous material is made of a material having a maximum pore diameter of 20 microns or less, preferably 10 microns or less and a porosity of 10 to 35%. The material is oxidation-resistant alumina, silicon nitride or silicon carbide. In addition, the surface of the molding surface is made of a ceramic surface such as porous carbon, so that the fluid film is not broken and the molding material is not damaged, and the molded surface at the stage of obtaining a precision element with a corrected shape. In order to ensure transferability at the time of contact between the preform and the preform, it is necessary to have a smooth mirror surface with no protrusion and processed to a desired surface accuracy that can ensure the function of the precision element.
[0125]
Next, in the second step, when preparing the molding material of the precision element, the surface of the part corresponding to the part that becomes the functional surface after molding of the molding material, so as not to cause defects in the molded precision element, This is a smooth finishing step, and is to remove in advance optical defects, that is, defects that cannot be eliminated by pressure molding, in the surface corresponding to the portion. Specifically, the surface is finished so that there is no sharp step with a height difference of 5 microns or more, so that there is no sharp portion when viewed microscopically such as scratches and chips. Is to process. This treatment is performed by a conventional method such as grinding and polishing, surface etching by acid treatment, softening of the surface by flame or hot air, and the like.
[0126]
Furthermore, by performing the third step, it becomes possible to heat and soften the molding material in a non-contact state with the molding surface of the mold unit, so that the molding surface may be affected after molding on the mold unit. It is possible to obtain a soft molded material lump having a defect-free surface and a very smooth state. At this time, the molding material is 103-109By heating the molding material to a temperature showing a viscosity of dPa · s, it is possible to connect to the next fourth step.
[0127]
In the next fourth step, it is possible to prevent the contact between the molding surface and the high-temperature molding material by closing the mold unit while ejecting fluid from the molding surface of the mold. It is possible to obtain a preform that has a shape that makes it easy to obtain a precision element and has no surface defects. The shape of the preform obtained in this process is such that the molding material does not undergo major deformation when pressed in the next process, and the deformation is not a flow of the molding material, but is apparently almost a deformation due to bending. It is desirable that the shape is sufficient with a slight deformation. For this purpose, the shape of the preform is 0 to 3% thicker than the thickness in the pressing direction of the corrected precision element obtained in the next step, or more than the thickness. It is desirable that the thickness does not exceed 0.5 mm, and the outer diameter is also almost the same, but the shape is slightly smaller, and the pressure applied in the next process is applied as evenly as possible to the entire preform. It is desirable that the shape be similar to the molding surface so that the deformation amount is the same as much as possible. In addition, by adopting such a shape, the molding in the next process becomes a deformation mainly composed of bending, and the fine transfer of the hole portion of the porous material forming the molding surface is suppressed. Thus, it is possible to obtain a precision element having a surface in which the shape remains. Furthermore, a reproducible and stable preform can be obtained by reliably reproducing the closing speed, timing, pressure, flow rate / pressure, temperature, etc. of the fluid to be ejected in this step. This is the mold unit, the molding material is 103-109When the temperature is in the temperature range showing the viscosity of dPa · s and the shape of the preform is obtained, the fluid film thickness is 20 microns or less, and when obtaining a preform with a more stable shape, it is 10 microns or less. The pressure and flow rate of the fluid are controlled in the same manner, and at the same time, the pressure and speed at which the mold is closed are controlled while making the film thickness of the fluid inversely proportional to the temperature of the molding material so as to be within the above range. This is achieved by imitating the corrected shape of the molding surface. The operation when closing the mold unit is desirably controlled in accordance with the temperature of the molding material, and the temperature variation in each operation is 10 ° C. or less, preferably 5 ° C. or less. It is desirable to keep the temperature in the same range, and the variation of the flow rate and pressure of the fluid and the variation of the speed and pressure of closing the mold unit should be within 5%, preferably within 3%. It can be obtained stably.
[0128]
In the next fifth step, the preformed product obtained in the fourth step is brought into contact with the molding surface of the mold member, and the shape of the corrected molding surface is accurately transferred to the preformed product to complete the cooling. This is performed to determine the shape of the subsequent precision element, and press molding is performed under conditions such that the surface of the preform does not transfer a fine shape. This is because the viscosity in the vicinity of the surface of the preform is high so as not to transfer the shape of the porous hole that is the fluid ejection hole of the molding surface of the mold member made of the material as described above. At that point, specifically, the glass softening temperature is 107.6When the temperature is lower than the temperature indicating the viscosity of dPa · s, the shape is corrected by applying pressure in a state where the preform and the molding surface of the mold member are in contact with each other, and the shape of the corrected molding surface is changed to the preform. Similarly, it is desirable that the pressure at this time be a pressure that does not transfer the shape of the hole, specifically, 5 MPa or less, preferably 2 MPa or less. However, this pressure is the pressure when the viscosity of the molding material and the shape of the hole are as described above. If the viscosity is high or the size of the hole is finer, higher pressure can be applied. is there.
[0129]
The sixth step is to force the precision element with the corrected shape in close contact with the corrected shape molding surface to re-eject the fluid from the porous hole of the molding surface and lift the precision element from the molding surface. At the same time, if necessary, the step of releasing the precision element from the molding surface to release it from the molding surface and releasing the mold to provide a gap between the precision element and the molding surface. This is done to prevent the shape of the precision element that has been shaped and corrected from deteriorating due to the shrinkage difference between the mold and the molding material during cooling. It is realized in a temperature range in which it is difficult to be deformed by other external forces and the difference in shrinkage between the mold and the material does not increase. The specific temperature range is a viscosity that does not cause deformation at the initial stage of the mold release action and cooling in the non-contact state in the next process with respect to the upper limit.8dPa · s or more, preferably 109It is necessary to carry out at a temperature not higher than dPa · s. In addition, the lower limit temperature has a large difference in the amount of heat shrinkage, and the molding material only needs to be at or above the temperature range that can follow the shrinkage of the mold. Usually the molding material is 1012It is desirable that the temperature be equal to or higher than a temperature showing a viscosity of dpa · s or lower. In order to facilitate the mold release operation in this process, it is better that the surface of the molding surface of the mold is made of a material having poor wettability with a molding material typified by carbon or platinum. Bring.
[0130]
The first cooling in the next seventh step is performed in order to control the viscosity of the molding material and transfer the corrected shape of the molding surface of the mold unit to the molding material to obtain a preform with a stable shape. The cooling is gradually performed while controlling the viscosity of the molding material so that the film thickness of the fluid is reached when the first cooling is completed. When the first cooling is completed, the preform is molded with a fluid film having a controlled thickness between the molding surface and the shape accuracy of the preform required for the next process is increased. Secured. In addition, at the time of completion of the first cooling, it is desirable that the molding material, the mold unit, the temperature of the fluid, and the like be within the aforementioned ranges. Further, the second cooling after that is performed to the above-mentioned temperature so that the corrected shape once transferred by contact is almost solidified and the shape does not change at the time of mold release. This is done so that it does not occur. For this purpose, it is necessary to accurately reproduce the cooling start temperature, the cooling rate and temperature distribution at the time of cooling, and particularly the temperature and temperature distribution at the time of completion of cooling that is at the time of mold release. When the reproducibility at this time is 20 ° C. or less, preferably 10 ° C. or less as the temperature variation until release, a stable shape reproducibility can be obtained. Further, the cooling rate and the temperature distribution during cooling at this time are determined when determining the corrected shape of the molding surface within a range that does not cause cracks in the molding material or defects due to large birefringence. Further, the subsequent third cooling can be performed at a faster speed than the first and second cooling, and the cooling here is performed by changing the correction shape once transferred before the mold release to the shape before correction by cooling. That is, it is performed so as to coincide with the original desired shape of the precision element and to prevent variation due to cooling shrinkage in continuous molding. For this purpose, it is necessary to accurately reproduce various conditions such as the third cooling start temperature (= release temperature) when the correction shape is determined and the temperature distribution during cooling. This reproducibility is a viscosity at which the precision element molded from the start of cooling is less likely to be deformed as described above.12For materials that require dPa · s, more precise transferability, or complex shapes, the molding material has a viscosity that does not newly generate distortion 1014.5Stable reproducibility can be obtained by setting the temperature variation up to dPa · s to 30 ° C. or less, preferably 15 ° C. or less. In addition, the cooling rate and the temperature distribution during cooling are determined when determining the corrected shape within a range that does not cause cracks in the molding material or defects due to large birefringence. In order not to cause deformation due to the pressure of the fluid or the fluid, it is desirable to cool the surface of the precision element at a rate of 20 ° C. or more per minute, and the fluid pressure and flow rate are not abruptly changed. It is desirable to do so. Through the above-described cooling, at the end of this step, the shape of the molding surface of the mold unit and the shape of the molded precision element are corrected for the difference between the respective expansion coefficients and the previously estimated sink mark. However, because the amount of correction is not completely the same, the shape of the precision element is not affected by the shape of the molding surface of the mold unit, and the desired shape can be maintained.
[0131]
The next eighth step is a step of correcting a shift in shape due to a difference in heat shrinkage between the molding surface of the mold member and the molding material at the time of shape transfer during the second cooling. This is because the molding surface of the mold member is accurately finished into a mirror surface state, and in molding that transfers the surface state, molding is performed if there is a difference in shrinkage during cooling between the mold member and the molding material. The shape contacts the molding surface unevenly during cooling, partially transfers the shape of the molding surface of the mold at that temperature, and the molding surface of the precision element after mold release becomes distorted or discontinuous This is a process to prevent the surface shape from becoming the original desired surface shape, and it is impossible to obtain the desired surface shape. This can only be solved by bringing the precision element into close contact with the surface of the precision element so as to follow contraction in the thickness direction of the precision element. The following of the mold member to the surface of the precision element may be performed using the adhesion force between the molding surface and the precision element, but it increases the certainty and does not depend on the shape of the precision element. For this purpose, it is desirable to apply pressure from the mold member to the outside.
[0132]
In the final ninth step, the precision element already solidified as described above is taken out of the mold unit to obtain a precision element having a desired shape transferred. At this time, a film made of fluid is interposed between the precision element and the molding surface of the mold unit, thereby preventing the occurrence of scratches due to contact with the molding surface of the precision element. In addition, the molding surface can be prevented from being damaged by contact with the solidified precision element.
[0133]
Further, in the ninth method, the mold member made of the molding material and the porous material with the shape corrected in advance of the molding surface, the temperature and viscosity of the molding material, and the pressure and temperature applied to the mold unit High-precision shape by simulating the coefficient of thermal expansion of the mold as a parameter of molding conditions, predicting the shape of the precision element to be molded in advance, and correcting the shape of the molding surface of the mold unit based on it In addition, a precision element having surface accuracy can be obtained. This correction is a combination of the first correction associated with the difference in thermal expansion between the mold member and the molding material and the second correction for canceling sink marks or the like associated with cooling of the molding material. By performing this correction at the time of shape processing, it is possible to make the shape of the precision element coincident with the desired shape when molding is completed and taken out of the mold unit and further cooling is completed.
[0134]
Here, the first correction is the molding surface of the mold member, which is generated due to the temperature difference between the shape transfer and the shape processing of the mold member or when using the precision element, and the difference in thermal expansion coefficient between the mold member and the molding material. This is correction of the amount of deviation of the shape of the precision element. Specifically, the shape of the desired precision element at the operating temperature is changed to the final shape transfer temperature until the follow-up of the mold member during the second cooling ends. Calculate the shape change amount of the precision element due to the temperature difference by the expansion coefficient of the molding material, and further change the shape change amount of the precision element from the final shape transfer temperature to the temperature difference when processing the forming surface of the mold unit The amount calculated by the expansion coefficient of the mold member as the amount of change in shape is used as the first correction amount of the shape of the mold member molding surface. The second correction is a correction of a deformation amount including a partial deformation due to shrinkage or sinking due to cooling in the mold and after removal from the mold after the precision element has transferred the shape. The temperature distribution of the molding material itself, the resulting viscosity distribution and the coefficient of thermal expansion, and the stresses calculated by them, governed by the ever-changing temperature of the fluid and mold unit, the retained heat and temperature conductivity of the molding material The amount of sink is calculated based on the stress relaxation coefficient unique to the molding material, and the amount of shape change due to the molding material's own weight or fluid pressure change is added to that amount. This is the amount of correction.
[0135]
In the tenth method, an element having a shape that approximates the final shape of the desired precision element is formed in advance, and information obtained from the shape data during and after the forming and the shape data is formed. By feeding back to the surface shape, an optical element having a highly accurate shape and surface accuracy can be obtained. This correction method uses a mold unit having a molding surface with a shape almost the same as the shape of a precision element first, pre-sets the element once under fixed conditions, and uses conditions after completion of molding. Compare the shape of the element in the same state with the shape of the molding surface of the used mold unit, and use the amount of the shape difference found there as a correction amount to the molding surface of the mold unit. In the case of simple correction that can be corrected by change, it is possible to match the molded precision element with a desired shape by correcting the molding conditions. In addition, by repeating this correction several times, it becomes possible to obtain a more accurate and stable shape, and the same effect can be obtained by combining the correction method of the molding surface of the mold unit by the above-described simulation. I can do it.
[0136]
In the eleventh method, the temperature of the molding material can be controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. This is because the molding material is not in contact with the mold unit, and the molding material is covered with the mold unit, and it is virtually impossible to measure the temperature of the molding material from the outside. This can be solved by controlling the temperature of the fluid that is in direct contact and indirectly controlling the temperature of the molding material by its heat transfer. Temperature control can be performed. Here, as a method for controlling the temperature of the fluid, it is possible to sufficiently achieve the purpose by directly adjusting the temperature of the fluid in the vicinity of the supply source. By using the heat source such as a heater incorporated in the mold unit, which is the fluid passage just before the fluid touches the molding material, the temperature is adjusted again to achieve better temperature control of the molding material. It can be realized.
[0137]
In the twelfth method, a highly accurate shape is obtained by controlling the ejection pressure of the fluid ejected from the molding surface of the molding die, the flow rate of the fluid, and the pressure applied to the mold unit in accordance with the viscosity of the molding material. In addition, an optical element having surface accuracy can be obtained. Here, the fluid film between the molding surface of the mold unit and the molding material is controlled by controlling the flow rate and pressure of the fluid and the pressure applied to the mold unit in synchronization with the viscosity change corresponding to the hardness of the molding material. The thickness can be reliably stabilized and controlled, and as a result, the preform and the completed precision element can obtain a stable shape with higher accuracy and less variation even during continuous molding. Is possible.
[0138]
In the thirteenth method, the mold member constituting the mold unit is used as a molding material when obtaining a preform having a shape approximate to the shape of the molding surface and when cooling in the mold after the shape transfer. In contrast, by controlling the pressure distribution of the fluid existing between the molding material and the molding surface by rotating and sliding, an optical element having a highly accurate shape and surface accuracy can be obtained. This is because it is easy to make the film thickness of the fluid between the molding material and the molding surface of the mold member uniform by rotating and sliding the mold member with respect to the molding material during pressure molding. Accurate precision elements can be obtained, and the functional surface of the lens, etc. is based on a spherical surface that is symmetrical with respect to the axis, especially by making the film thickness easily uniform with respect to the axis of rotation. It is possible to exert a great effect on a precision element having a shape.
[0139]
(Ninth embodiment)
Next, another embodiment for molding exactly the same one as the first embodiment will be described. The molding surface 11a of the lower mold 11 and the molding surface 21a of the upper mold 21 are exactly the same as in the sixth embodiment, except that the final shape transfer temperature is 10% for the glass material.14The shape obtained by setting the temperature at a viscosity of dPa · s and determining the shape was used.
[0140]
First, a glass lump 102a was obtained on the molding surface 11a by the same method as in the first example.
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the molding surface 11a of the glass lump 102a is 10.6-107.5dPa · s, the viscosity in the vicinity of other surfaces is 103~6dPa · s, while the vicinity of the center is sufficiently soft, the flow rate of nitrogen gas ejected from the molding surface 11a and the molding surface 21a is 20 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 3.2 mm. The mold unit 1 was closed at a speed of 5 mm per second until Next, the temperature and flow rate of the nitrogen gas are set to 600 ° C. and 10 liters per minute so that the film thickness of the gas is about 20 microns, and the center thickness of the lens when cold is at a position corresponding to 3.05 mm. As the pressure closes the mold unit 1, the pressure in the vicinity of the lens surface is 10 while gradually increasing the pressure so that the pressure is 20 kgf.7.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product.
[0141]
Further, immediately after that, the gas injection is stopped, and the molding surface of the mold unit 1 is closed by applying a pressure of 200 kgf, and the shape of the preform is changed while the preform and the molding surface of the mold member are in contact with each other. Matched to the shape of the molding surface.
In addition, immediately after obtaining the softened glass lump 102a and before obtaining a preformed product, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the preformed product. The second cooling is performed by blowing a cooling nitrogen gas from the outside of the mold unit 1 by a cooling device (not shown). At that time, the restriction from the outside to the mold components 2 and 3 is released, The mold member 11 and the upper mold member 21 can follow the contraction of the lens. After starting cooling, the viscosity near the surface of the lens is 1014When dPa · s was reached and the adhesion between the molding surfaces 11a and 21a and the lens was lost, the mold unit 1 was opened, and the lens was taken out with a suction hand (not shown) and cooled to room temperature. In addition, the accuracy of the molded lenses was measured at a temperature of 20 ° C, which is the same temperature as the operating conditions. However, all the Asses were within 1.5 Newton rings and the habit was within 1 Newton ring. Accurate accuracy could be obtained.
[0142]
In addition, the reproducibility of the switching timing of the operation such as temperature and pressurization / depressurization at the time of the plurality of moldings is within a variation range of 10 ° C at all temperature control points, and the opening / closing speed of the mold unit, etc. However, as a result of continuing molding while slightly changing the conditions, it was confirmed that the accuracy deteriorated when the temperature and speed variations were exceeded.
[0143]
(Tenth embodiment)
Next, using the same apparatus and the same material as in the ninth embodiment, one surface has an aspherical shape based on R50 mm and the other surface is R40 mm. The center thickness of the lens is 4.3 mm and the diameter is Φ23 mm. A biconvex glass aspheric lens for a compact camera was molded.
[0144]
As in the ninth embodiment, the molding surface 11a of the lower mold member 11 and the molding surface 21a of the upper mold member 21 are processed into a shape that takes into account numerous corrections obtained by simulation before molding, and then actually Molding was performed and final correction was performed based on the shape data to determine the shape. Specifically, as in the ninth embodiment, in the case of the molding surface 21a of the upper die 21, as shown in FIG. 3A, a shape 201 (20 ° C.) that is a standard use condition of a lens that is a precision element. The temperature at the time of shape transfer at the time of molding is 10 in terms of glass viscosity.12The temperature indicating dPa · s was set, and the amount of deformation due to temperature expansion of the glass, which is a part of the first correction amount, was calculated. From the result, the shape 204 of the precision element under this condition was obtained. Next, a correction amount 205 due to sink marks due to cooling after shape transfer, which corresponds to the second correction amount, is obtained, a partial shape 206 of the molding surface at the time of shape transfer is determined, and further the first correction amount. From the amount of correction due to the temperature shrinkage of the material of the molding surface of the mold unit, which corresponds to the remaining part of the molding unit, the molding surface shapes 207 and 207a ( 3A, the shapes of hatched portions 207 and 207a) were obtained. Then, based on the shape data, the molding surface 21a of the upper mold member 21 was processed into a mirror surface with the porous hole indented, and the lens was actually molded under the molding conditions determined by simulation. Next, the shape of the molded lens was measured, and the portion slightly deviated from the predetermined shape was corrected again, and finished to a smooth mirror surface state without a bulge to obtain the final shape of the molding surface 21. Further, the molding surface 11a of the lower mold member 11 was processed for its shape by the same method. The mold members 11 and 21 were made of porous AlO3 having a porosity of 25% and a maximum hole diameter of 6 microns, and clean air was used as the fluid. A carbon film as a release layer was deposited on the surface of the molding surface so that the porous holes were not blocked. The release layer is not particularly limited to the carbon film as long as it does not prevent the mold and the glass from being fused and loses the specularity of the molding surface.
[0145]
Next, the mold members 11 and 21 prepared as described above were attached to the molding apparatus shown in FIG. 1, and a glass lump 102a was obtained in exactly the same manner as in the first embodiment.
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the lower mold member 11 of the glass lump 102a is 10.6-107.5dPa · s, the viscosity in the vicinity of other surfaces is 103~6dPa · s, while the vicinity of the center is sufficiently soft, the flow rate of air ejected from the molding surfaces 11a and 21a is 25 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 4. The mold unit 1 was closed at a speed of 8 mm per second until 6 mm. Next, the temperature and flow rate of the blown air are set to 600 ° C. and 15 liters per minute, and when the center thickness of the lens when cold is at a position corresponding to 4.32 mm, the pressure for closing the mold unit 1 is 45 kgf. While increasing the pressure gradually, the viscosity near the lens surface is 10 at the same time.7.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product. At this time, the film thickness of the gas was about 8 microns.
[0146]
Further, immediately after that, the gas injection is stopped, and the molding surface of the mold unit 1 is closed by applying a pressure of 220 kgf, and the shape of the preform is changed while the preform and the molding surface of the mold member are in contact with each other. Matched to the shape of the molding surface.
Following the first cooling step until the preform is obtained, the second cooling is performed in the same manner as in the ninth embodiment immediately after the shape of the preform matches the shape of the molding surface of the mold. Went. At that time, a pressure of 150 kgf was applied to the mold constituent members 2 and 3 from the outside to cause the mold members 11 and 21 to follow contraction in the thickness direction of the lens. After starting cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature was about 515 ° C.), the mold unit 1 was opened at the same time as the pressure applied to the mold components 2 and 3 was released, and the lens was taken out and cooled to room temperature. Furthermore, this molding is repeated several times, and the reproducibility of the temperature and timing such as pressurization / decompression at this time is strictly controlled so that the variation in speed is within 3% within the temperature range of 5 ° C. The molding was carried out. After that, the accuracy of the completed lenses was measured at a temperature of 20 ° C., but all the ashes were within 1 Newton ring and the habit was within 0.5 Newton rings, which is better than that of the ninth embodiment. The result was obtained.
[0147]
(Eleventh embodiment)
Next, using the molding apparatus using the mold member shown in FIG. 4 in the first embodiment, the diameter is Φ10 mm, the convex radius of curvature is R20 mm, the concave radius of curvature is R30 mm, and the central wall thickness is 3.3 mm. A convex meniscus lens having a peripheral edge thickness of about 3.1 mm was molded. Here, in FIG. 4, 211 and 221 are a lower mold member and an upper mold member, respectively, and molding surfaces 211a and 221a forming an optical surface of the lens are processed. Further, ring members 216 and 226 having molding surfaces 216a and 226a that form the lower and upper portions of the periphery of the lens are attached to the outer periphery of the lower mold member 211 and the upper mold member 221, respectively. The lower mold member 211 and the upper mold member 221 have a porosity of 15% and a maximum hole diameter of 15 microns, and the ring members 216 and 226 have porous silicon nitride having a porosity of 10% and a maximum hole diameter of 20 microns. The fluid can be independently supplied to each pressure chamber 12b, 12c, 22b, 22c from a supply device (not shown), and the molding surface and the peripheral edge of each optical surface The film thickness of the fluid between the molding surface of the part and the molding material can be controlled independently. Moreover, the same glass material as 1st Embodiment was used for the shaping | molding raw material, and nitrogen gas was used as a fluid. Further, the same release layer as in the tenth embodiment was used.
[0148]
In this embodiment, the shapes of the molding surfaces 211a and 221a of the optical surface of the lens and the molding surfaces 216a and 226a of the peripheral portion are once processed by preliminarily processing the cold shape of the lens on the molding surface, The correction processing amount of the molding surface was calculated so as to correct the shape error of the molded optical element, and it was reflected again on the shape of the molding surface and processed again to finish it in a mirror surface state. The final shape transfer temperature at this time is 515 ° C. (glass viscosity is 1012dPa · s).
[0149]
Next, the mold members 211, 211, 216, and 226 prepared in this way were attached to the molding apparatus shown in FIG. 1 similarly to the first embodiment, and a softened glass lump was obtained by the same method. The temperature of the nitrogen gas at this time is 500 ° C., which is the temperature near the glass transition point when the glass is received on the molding surface 211a, and immediately after that, the viscosity of the glass is 10%.7.3The temperature is adjusted to 620 ° C. which is a temperature corresponding to dPa · s, and the flow rate of nitrogen gas is 18 liters per minute on the molding surface 211a until just before the molten glass 102 is received on the molding surface 211a. The surface 216a was controlled to be 8 liters per minute, and thereafter, both were 5 liters per minute.
[0150]
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the lower mold member 211 of the glass lump 102a is 10.5.6-107dPa · s, the viscosity in the vicinity of other surfaces is 103-105.6The flow rate of nitrogen gas ejected from the molding surfaces 211a and 221a is 20 liters per minute and the flow rate from the molding surfaces 216a and 226a is 14 liters and 12 liters per minute respectively while the center is sufficiently soft. And the temperature is 10 as the viscosity of the glass.5.8The temperature is set to 680 ° C. corresponding to dPa · s (first cooling start), and the rotational speed is 200 rpm in the rotational direction in which the lower mold component 2 and the upper mold component 3 are rotated in the opposite directions. The mold unit 1 was closed at a speed of 8 mm per second until the center thickness of the glass lump 102a reached 3.5 mm while gradually increasing the rotation speed so that Next, in a state where the lower mold component 2 and the upper mold component 3 are kept rotating, the temperature of the nitrogen gas is 610 ° C., and the flow rate from the molding surfaces 211a and 221a is adjusted every minute so that the film thickness is about 12 microns. When the flow rate from the 15 liters and the molding surfaces 216a and 226a is set to 12 liters and 11 liters per minute, respectively, and the center thickness of the lens when cold is at a position corresponding to 3.33 mm, While gradually increasing the pressure to close the unit 1 to 25 kgf, at the same time, the viscosity near the lens surface is 107.6The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product.
[0151]
Further, immediately after that, the injection and rotation of the gas are stopped, and the molding surface of the mold unit 1 is closed by applying a pressure of 100 kgf, and the preform is in contact with the molding surface of the mold member. The shape was made to match the shape of the molding surface.
Following the first cooling step until the above preformed product is obtained, second cooling is performed in the same manner as in the tenth embodiment immediately after obtaining the preformed product. At that time, a pressure of 75 kgf was applied to the mold constituent members 2 and 3 from the outside to cause the mold members 11 and 21 to follow contraction in the thickness direction of the lens. After starting cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature was about 515 ° C.), the mold unit 1 was opened at the same time as the pressure applied to the mold components 2 and 3 was released, and the lens was taken out and cooled to room temperature. Furthermore, the accuracy was measured for a plurality of molded lenses at a temperature of 20 ° C., which is the same temperature as the operating conditions. All of them were as small as 1 Newton ring and quasi 0.5 or less Newton rings. Accurate accuracy could be obtained.
[0152]
Also, the reproducibility of the temperature and the switching timing of the operation such as pressurization / depressurization at the time of the plurality of moldings is within a variation range of 10 ° C at all temperature control points, and the opening / closing speed of the mold unit and Variations in the number of rotations of the mold components were also within 5%, but as a result of continuing molding while further changing the conditions, it was confirmed that the accuracy would deteriorate if the temperature and speed variations were exceeded. .
[0153]
The ninth to eleventh embodiments can be summarized as follows. In the fourteenth method, the first step is the precision element at the temperature when transferring the molding shape of the precision element, when using the precision element, or when processing the mold unit. The amount of heat shrinkage including the amount of difference in shape due to the difference in thermal expansion between the mold unit and the mold unit, and the occurrence position and amount of precision element sinks due to uneven heat distribution during molding and cooling are determined in advance in the mold. By making corrections, the molded precision element can obtain a desired shape. In addition, the molding surface of the mold unit is made of a porous material, and a fluid such as air or N2 gas is ejected from the molding surface toward the molding material to form a very thin fluid film on the molding surface. Contact between the softened molding material and the molding surface can be prevented. For this purpose, the porous material is made of a material having a maximum pore diameter of 20 microns or less, preferably 10 microns or less and a porosity of 10 to 35%. The material is alumina, silicon nitride or silicon carbide having oxidation resistance. In order to ensure that the surface of the molding surface does not break the fluid film and damage the molding material, and to ensure the transfer accuracy of the surface accuracy at the time of contact, It must be smooth and mirror-like with no protrusion and processed to a roughness that can ensure the function of the precision element.
[0154]
Next, in the second step, the molding material and the molding surface of the molding unit that are likely to be generated when the molding material in contact with the mold, particularly the melted and softened shape, flows out of the nozzle and is supplied to the molding unit. Can be prevented, and at this time, contact can be reliably prevented by lowering the temperature of the fluid temporarily ejected or increasing the flow rate. In addition, when separating the molding material supplied on the molding surface of the mold unit from the nozzle, after receiving the required amount of molding material on the mold unit, the molding material is lowered once with the mold unit and flows out from the nozzle. By forming a constriction between the mold unit and the molding material on the mold unit, and further developing and separating the constriction due to the weight and surface tension of the molding material, there is no defect on the mold unit that may affect after molding. There can be obtained a molding material lump having a very smooth surface.
[0155]
Next, in the third process, it is possible to prevent the contact between the molding surface and the molding material by closing the mold unit while ejecting fluid from the molding surface of the mold. Thus, it is possible to obtain a preform having a shape that makes it easy to obtain The shape of the preform obtained in this process is such that the molding material does not undergo major deformation when pressed in the next process, and the deformation is not a flow of the molding material, but is apparently almost a deformation due to bending. It is desirable that the shape is sufficient with a slight deformation. For this purpose, the shape of the preform is 0 to 3% thicker than the thickness in the press direction of the precision element of the corrected shape obtained in the next step, or more than the thickness. It is desirable that the thickness does not exceed 0.5mm, and the outer diameter is also the same, but it should be a very small shape, and the pressure applied in the next process is applied to the entire preform as evenly as possible. It is desirable that the shape be similar to the molding surface so that the deformation amount is the same as much as possible. In addition, by adopting such a shape, the molding in the next process becomes a deformation mainly composed of bending, and the fine transfer of the hole portion of the porous material forming the molding surface is suppressed. Thus, it is possible to obtain a precision element having a surface in which the shape remains. Furthermore, a reproducible and stable preform can be obtained by reliably reproducing the closing speed, timing, pressure, flow rate / pressure, temperature, etc. of the fluid to be ejected in this step. This is the mold unit, the molding material is 103-109When the temperature is in the temperature range showing the viscosity of dPa · s and the shape of the preform is obtained, the fluid film thickness is 20 microns or less, and when obtaining a preform with a more stable shape, it is 10 microns or less. The pressure and flow rate of the fluid are controlled in the same manner, and at the same time, the pressure and speed at which the mold is closed are controlled by making the film thickness of the fluid inversely proportional to the temperature of the molding material so that it falls within the above range This is achieved by imitating the corrected shape of the molding surface. The operation when closing the mold unit is desirably controlled in accordance with the temperature of the molding material, and the temperature variation in each operation is 10 ° C. or less, preferably 5 ° C. or less. The temperature of the mold unit should be within the same range, and the flow rate and pressure variation of the fluid and the speed and pressure variation of closing the mold unit should be within 5%, preferably within 3%. Can be obtained more stably.
[0156]
In the next fourth step, the preform obtained in the previous step is brought into contact with the molding surface of the mold member, the shape of the corrected molding surface is accurately transferred to the preform, and the precision after cooling is completed. This is performed to determine the shape of the element, and press molding is performed under conditions such that the surface of the preform does not transfer a fine shape. This is because the viscosity in the vicinity of the surface of the preform is high so as not to transfer the shape of the porous hole that is the fluid ejection hole of the molding surface of the mold member made of the material as described above. At that point, specifically 107.6When the viscosity reaches dPa · s or more, the shape is corrected by applying pressure while the preform is in contact with the molding surface of the mold member, and the corrected molding surface is transferred to the preform. Similarly, it is desirable that the pressure at this time is a pressure that does not transfer the shape of the hole, specifically 5 MPa or less, preferably 2 MPa or less. However, this pressure is the pressure when the viscosity of the molding material and the shape of the hole are as described above. If the viscosity is high or the size of the hole is finer, higher pressure can be applied. is there.
[0157]
The first cooling in the next fifth step is performed to control the viscosity of the molding material and transfer the corrected shape of the molding surface of the mold unit to the molding material to obtain a preform with a stable shape. The cooling is gradually performed while controlling the viscosity of the molding material so that the film thickness of the fluid is reached when the first cooling is completed. When the first cooling is completed, the preform is molded with a fluid film having a controlled thickness between the molding surface and the shape accuracy of the preform required for the next process is ensured. Is done. In addition, at the time of completion of the first cooling, it is desirable that the molding material, the mold unit, the temperature of the fluid, and the like be within the aforementioned ranges. The second cooling after thatFirst coolingCooling here can be performed at a faster speed, and the corrected shape once transferred matches the shape before correction due to cooling, that is, the original desired shape of the precision element. This is performed so as not to cause variation. For this purpose, it is necessary to accurately reproduce various conditions such as the cooling start temperature, the cooling rate during cooling, and the temperature distribution. Similar to the above, this reproducibility is 10 times the viscosity of the molding material from the start of cooling.12Stable shape reproducibility can be obtained by setting the temperature variation within the temperature range indicating dPa · s to 10 ° C. or less, preferably 5 ° C. or less. The cooling rate and the temperature distribution at the time of cooling are determined when determining the corrected shape of the molding surface within a range that does not cause cracks in the molding material or defects due to large birefringence.
[0158]
The next sixth step is a step of correcting a shape shift during cooling due to a difference in heat shrinkage between the molding surface of the mold member after the shape transfer and the molding material. This is because, usually, a molding material in a temperature state that can be deformed under pressure has an adhesive force, and this force is particularly great in molding in which the molding surface of a mold member is accurately finished to a mirror surface and the surface state is transferred. Works as a strong adhesion between the surface of the molding material and the molding surface. This force is easily influenced by the shape of the contact surface and the fine state of the interface of the contact surface. Therefore, the magnitude of the force is unstable and the distribution state is not uniform, so the entire contact surface is uniform. In some cases, the surface state is unstable and the molded surface becomes discontinuous in some cases. As a result, there is a problem that it cannot be finally matched with a desired shape. This problem is that at least the contact between the surface of the element and the molding surface is maintained while the adhesive force is large enough to deform the transfer surface between the mold materials. It is possible to solve the problem only by causing the mold member to follow the shrinkage.
[0159]
Further, the second cooling is performed until the following process of following the mold member is completed, and then the mold unit is opened and the molding element is taken out (seventh process) to have a shape approximate to a desired shape. A molded element can be obtained. Further, the end point of the second cooling, that is, the completion time of the follow-up process of the mold member is determined depending on the adhesion force.12~14.5Ideally, it is performed at dPa · s.
[0160]
In the next eighth step, the molded element having a shape approximated to the desired shape is further cooled to room temperature, whereby thermal shrinkage occurs, and the element becomes the shape of a precision element having the desired shape. Can be obtained.
Further, in the fifteenth method, the pre-corrected shape of the molding surface is obtained by changing the pressure, flow rate, temperature of the fluid, the temperature and viscosity of the molding material, and the pressure, temperature, and molding material and porosity applied to the mold unit. Simulation of the coefficient of thermal expansion of a mold member made of quality material as a parameter of molding conditions, predicting the shape of a precision element to be molded in advance, and correcting the shape of the molding surface of the mold unit based on it Thus, a precision element having a highly accurate shape and surface accuracy can be obtained. This correction is a combination of the first correction associated with the difference in thermal expansion between the mold member and the molding material and the second correction for canceling sink marks or the like associated with cooling of the molding material. By performing this correction at the time of shape processing, it is possible to make the shape of the precision element coincident with the desired shape when molding is completed and taken out of the mold unit and further cooled.
[0161]
Here, the first correction is the molding surface of the mold member, which is generated due to the temperature difference between the shape transfer and the shape processing of the mold member or when using the precision element, and the difference in thermal expansion coefficient between the mold member and the molding material. This is correction of the amount of deviation of the shape of the precision element. Specifically, the shape of the desired precision element at the operating temperature is changed to the final shape transfer temperature until the follow-up of the mold member during the second cooling ends. Calculate the shape change amount of the precision element due to the temperature difference by the expansion coefficient of the molding material, and further change the shape change amount of the precision element from the final shape transfer temperature to the temperature difference when processing the forming surface of the mold unit The amount calculated by the expansion coefficient of the mold member as the amount of change in shape is used as the first correction amount of the shape of the molding surface of the mold member. The second correction is a correction of a deformation amount including a partial deformation due to shrinkage or sinking due to cooling after the precision element has transferred the shape and then being cooled and taken out from the mold, and mainly. The temperature distribution of the molding material itself, the resulting viscosity distribution and thermal expansion coefficient associated with it, the stress calculated by them, the stress calculated by them, and the molding material's own, which are governed by the heat and temperature conductivity of the molding material that changes every moment during cooling The amount of sink is calculated from the stress relaxation coefficient of the second, and the amount of shape change due to the weight of the molding material or the change of external stress at that time is calculated and added to that amount as the second correction amount. To do.
[0162]
In the sixteenth method, an element having a shape approximated to a final shape of a desired precision element is formed in advance, and information obtained from the shape data during and after the forming and shape data is formed. By feeding back to the surface shape, an optical element having a highly accurate shape and surface accuracy can be obtained. This correction method uses a mold unit having a molding surface with a shape almost the same as the shape of a precision element first, pre-sets the element once under fixed conditions, and uses conditions after completion of molding. Compare the shape of the element in the same state with the shape of the molding surface of the used mold unit, and use the amount of the shape difference found there as a correction amount to the molding surface of the mold unit. In the case of simple correction that can be corrected by change, it is possible to match the molded precision element with a desired shape by correcting the molding conditions. In addition, by repeating this correction several times, it becomes possible to obtain a more accurate and stable shape, and the same effect can be obtained by combining the correction method of the molding surface of the mold unit by the above-described simulation. I can do it.
[0163]
In the seventeenth method, the temperature of the molding material can be controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. This is because the molding material is not in contact with the mold unit, or the molding material is covered by the mold unit when a preform having a shape that approximates the shape of the molding surface is obtained. Although it is practically impossible to measure the temperature of the material, it is solved by controlling the temperature of the fluid that is in direct contact with the molding material, and indirectly controlling the temperature of the molding material by its heat transfer, By doing so, it is possible to perform reliable temperature control with better responsiveness to the molding material. Here, as a method for controlling the temperature of the fluid, it is possible to sufficiently achieve the purpose by directly adjusting the temperature of the fluid in the vicinity of the supply source. By using the heat source such as a heater incorporated in the mold unit, which is the fluid passage just before the fluid touches the molding material, the temperature is adjusted again to achieve better temperature control of the molding material. It can be realized.
[0164]
In the eighteenth method, as in the seventeenth method, when a preform having a shape approximate to the shape of the molding surface is obtained, it is ejected from the molding surface of the molding die in accordance with the viscosity of the molding material. By controlling the fluid ejection pressure, the fluid flow rate, and the pressure applied to the mold unit, a preform having a stable shape can be obtained. Here, the fluid film between the molding surface of the mold unit and the molding material is controlled by controlling the flow rate and pressure of the fluid and the pressure applied to the mold unit in synchronization with the viscosity change corresponding to the hardness of the molding material. The thickness can be reliably controlled and controlled, and as a result, the molded preform can obtain a stable shape with little variation even during continuous molding.
[0165]
In the nineteenth method, a high-precision precision element can be obtained by following the mold member during the second cooling using the adhesion between the molding surface and the precision element. That is, it is realized by releasing the constraint from the outside so that at least one of the mold members can follow contraction in the thickness direction of the precision element.
In the twentieth method, as in the nineteenth method, the follow-up of the mold member during the second cooling can be performed more reliably by applying pressure from the outside to the mold member. This is to obtain a highly accurate precision element stably, and is realized by applying external pressure to at least one of the mold members to follow the shrinkage of the precision element in the thickness direction. .
[0166]
(Twelfth embodiment)
Next, another embodiment for molding exactly the same one as the first embodiment will be described. The molding surface 11a of the lower mold 11 and the molding surface 21a of the upper mold 21 are exactly the same as in the sixth embodiment, except that the final shape transfer temperature is 10% for the glass material.14The shape obtained by setting the temperature at a viscosity of dPa · s and determining the shape was used.
[0167]
First, the mold members 11 and 21 prepared as described above are attached to the molding apparatus shown in FIG. 1, and a glass block is cut out from the same glass block as used in the first embodiment, which is shown in FIG. 5 (a). 311mm in volume by grinding and polishing as shown3In addition, a portion of the glass lump other than the ground and polished surface is subjected to flame treatment with a burner to remove an acute step of 5 microns or more on the surface of the glass lump. 311mm capacity with smooth surface as shown in b)3A glass lump was obtained.
[0168]
Next, this glass lump is placed on the molding surface 11a on which nitrogen gas is ejected 30 liters per minute, and then the temperature of the nitrogen gas is set to 10 by the viscosity of the glass by the heater 13 and the heater 33a.5.4The glass lump was heated to 700 ° C., which is a temperature corresponding to dPa · s. At this time, the upper mold component 3 was also moved directly above the lower mold component 2, and a nitrogen gas having the same temperature was allowed to flow, so that the glass lump was heated from above. In this way, the viscosity is 10 with no harmful defects on the surface.6A dPa · s softened glass lump 102a was obtained.
[0169]
Next, the flow rate of nitrogen gas injected from the molding surfaces 11a and 21a is 20 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 3. The mold unit 1 was closed at a rate of 5 mm per second until 2 mm, and a preform with a center thickness of 3.05 mm was obtained.
[0170]
Further, immediately after that, the gas ejection is stopped, and the molding surface of the mold unit 1 is closed by applying a pressure of 200 kgf, and pressurization is performed while the preformed product and the molding surface of the mold member are in contact with each other. The shape of the product was adjusted to the shape of the molding surface.
In addition, immediately after obtaining the softened glass lump 102a and before obtaining a preformed product, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the preformed product. The second cooling is performed by blowing a cooling nitrogen gas from the outside of the mold unit 1 by a cooling device (not shown). At that time, the restriction from the outside to the mold components 2 and 3 is released, The mold member 11 and the upper mold member 21 can follow the contraction of the lens. After starting cooling, the viscosity near the surface of the lens is 1014When dPa · s was reached and the adhesion between the molding surfaces 11a and 21a and the lens was lost, the mold unit 1 was opened, and the lens was taken out with a suction hand (not shown) and cooled to room temperature. In addition, the accuracy of the molded lenses was measured at a temperature of 20 ° C, which is the same temperature as the operating conditions. However, all the Asses were within 1.5 Newton rings and the habit was within 1 Newton ring. Accurate accuracy could be obtained.
[0171]
Furthermore, as a result of continuing molding while slightly changing the conditions of the surface treatment of the glass lump prepared first, if the step remaining on the surface exceeds 5 microns or an acute step remains, the surface is softened after heating and softening. It takes a long time to make it smoother, and in some cases, this heat softening does not eliminate the step, leaving defects on the lens surface after molding, and it has been confirmed that this is a serious problem in practice. It was.
[0172]
In addition, the reproducibility of the switching timing of the operation such as temperature and pressurization / depressurization at the time of the plurality of moldings is within a variation range of 10 ° C at all temperature control points, and the opening / closing speed of the mold unit, etc. However, the accuracy deteriorated when the temperature and speed variations were exceeded, and the cooling rate, especially the second cooling rate, was reduced. It has been confirmed that when the temperature is slower than 20 ° C./min, it is easily affected by the deformation of its own weight and the pressure of nitrogen gas, and the accuracy deteriorates.
[0173]
(13th Embodiment)
Next, using the same apparatus and the same material as those in the twelfth embodiment, one surface has an aspherical shape based on R50 mm and the other surface is based on R40 mm. The center thickness of the lens is 4.3 mm and the diameter is Φ23 mm. A biconvex glass aspheric lens for a compact camera was molded.
[0174]
As in the twelfth embodiment, the molding surface 11a of the lower mold member 11 and the molding surface 21a of the upper mold member 21 are processed into a shape that takes into account numerous corrections obtained by simulation before molding, and then actually Molding was performed and final correction was performed based on the shape data to determine the shape. Specifically, as in the fourteenth embodiment, in the case of the molding surface 21a of the upper mold 21, as shown in FIG. 3A, a shape 201 (20 ° C.) that is a standard use condition of a lens that is a precision element. The temperature at the time of shape transfer at the time of molding is set to a temperature indicating 1012 dPa · s in terms of glass viscosity, and the glass temperature is a part of the first correction amount. The deformation amount due to expansion was calculated, and from the result, the shape 204 of the precision element under this condition was obtained. Next, a correction amount 205 due to sink marks due to cooling after shape transfer, which corresponds to the second correction amount, is obtained, a partial shape 206 of the molding surface at the time of shape transfer is determined, and further the first correction amount. From the amount of correction due to the temperature shrinkage of the material of the molding surface of the mold unit, which corresponds to the remaining part of the molding unit, the molding surface shapes 207 and 207a ( 3A, the shapes of hatched portions 207 and 207a) were obtained. Then, according to the shape data, the molding surface 21a of the upper mold member 21 is processed into a mirror surface state in which the surface excluding the hollow of the porous hole portion is within 0.2 due to Newton ring deviation, The lens was actually molded under the molding conditions determined by simulation. Next, the shape of the molded lens was measured, and the portion slightly deviated from the predetermined shape was corrected again, and finished to a smooth mirror surface state without a bulge to obtain the final shape of the molding surface 21. Further, the molding surface 11a of the lower mold member 11 was processed for its shape by the same method. The mold members 11 and 21 are made of porous AlO having a porosity of 25% and a maximum hole diameter of 6 microns.3And clean air was used as the fluid. A carbon film as a release layer was deposited on the surface of the molding surface so that the porous holes were not blocked. The release layer is not particularly limited to the carbon film as long as it does not prevent the mold and the glass from being fused and loses the specularity of the molding surface.
[0175]
Next, the mold members 11 and 21 prepared as described above are attached to the molding apparatus shown in FIG. 1, and a glass lump is cut out in the same manner as in the twelfth embodiment, and the cutting portion is polished. In the same manner as above, a glass lump 102a in a softened state was obtained.
This glass lump 102a is 106.5When the temperature reaches dPa · s, the flow rate of air ejected from the molding surfaces 11a and 21a is 25 liters per minute and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 4. The mold unit 1 was closed at a speed of 8 mm per second until 6 mm. Next, the temperature and flow rate of the blown air are set to 600 ° C. (temperature corresponding to 107.9 dPa · s in terms of glass viscosity) and 15 liters per minute, and the center thickness of the lens when cold corresponds to 4.32 mm. At the same time, while gradually increasing the pressure so that the pressure for closing the mold unit 1 is 45 kgf, the viscosity near the lens surface is 107.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product. The gas thickness at this time was about 8 microns.
[0176]
Following the first cooling step until the above preformed product is obtained, second cooling is performed in the same manner as in the twelfth embodiment immediately after obtaining the preformed product. At that time, a pressure of 150 kgf was applied to the mold constituent members 2 and 3 from the outside to cause the mold members 11 and 21 to follow contraction in the thickness direction of the lens. After starting cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature was about 515 ° C.), the mold unit 1 was opened at the same time as the pressure applied to the mold components 2 and 3 was released, and the lens was taken out and cooled to room temperature. Furthermore, this molding is repeated several times, and the reproducibility of the temperature and timing such as pressurization / decompression at this time is strictly controlled so that the variation in speed is within 3% within the temperature range of 5 ° C. The molding was carried out. After that, the accuracy of the completed lenses was measured at a temperature of 20 ° C., but all the ashes were within 1 Newton ring and the habit was within 0.5 Newton rings, which is better than the twelfth embodiment. The result was obtained.
[0177]
(Fourteenth embodiment)
Next, using a molding apparatus using the mold member shown in FIG. 12 in the twelfth embodiment, the diameter is Φ10 mm, the convex radius of curvature is R20 mm, the concave radius of curvature is R30 mm, and the central thickness is 3.3 mm. A convex meniscus lens having a peripheral edge thickness of about 3.1 mm was molded. Here, in FIG. 4, 211 and 221 are a lower mold member and an upper mold member, respectively, and molding surfaces 211a and 221a forming an optical surface of the lens are processed. Further, ring members 216 and 226 having molding surfaces 216a and 226a that form the lower and upper portions of the periphery of the lens are attached to the outer periphery of the lower mold member 211 and the upper mold member 221, respectively. The lower mold member 211 and the upper mold member 221 have a porosity of 15% and a maximum hole diameter of 15 microns, and the ring members 216 and 226 have porous silicon nitride having a porosity of 10% and a maximum hole diameter of 20 microns. The fluid can be independently supplied to each pressure chamber 12b, 12c, 22b, 22c from a supply device (not shown), and the molding surface and the peripheral edge of each optical surface The film thickness of the fluid between the molding surface of the part and the molding material can be controlled independently. Further, the same glass material as that in the twelfth embodiment was used as the molding material, and nitrogen gas was used as the fluid. Further, the same release layer as in the thirteenth embodiment was used.
[0178]
In this embodiment, the shapes of the molding surfaces 211a and 221a of the optical surface of the lens and the molding surfaces 216a and 226a of the peripheral portion are once processed by preliminarily processing the cold shape of the lens on the molding surface, The correction processing amount of the molding surface was calculated so as to correct the shape error of the molded optical element, and it was reflected again on the shape of the molding surface and processed again to finish it in a mirror surface state. In addition, the temperature at the time of shape transfer in the preforming is 515 ° C. (10% in terms of glass viscosity).12dPa · s).
[0179]
Next, the mold members 211, 211, 216, and 226 prepared in this way are attached to the molding apparatus shown in FIG. 1 similarly to the twelfth embodiment, and further, from the same glass block used in the fourteenth embodiment. Then, the glass lump is cut out and the volume is 250 mm by grinding and polishing.3The glass lump is finished to a glass lump, and the part other than the ground and polished surface of the lump of glass is subjected to flame treatment with a burner, thereby removing a sharp step of 5 microns or more on the surface of the lump of glass, and a smooth surface. The capacity is 250mm3A glass lump was obtained.
[0180]
Next, after placing this glass lump on the molding surface 211a on which nitrogen gas is ejected at 25 liters per minute, the temperature of the nitrogen gas is set to 10 as the viscosity of the glass.5.4The glass lump was heated to 700 ° C., which is a temperature corresponding to dPa · s. At this time, the upper mold component 3 was also moved immediately above the lower mold component 2, and nitrogen gas having the same temperature was passed through the molding surfaces 216a, 221a, and 226a, and the glass block was heated from the upper and lower sides and the outer periphery. In this way, a softened glass lump 102a having a viscosity of 106 dPa · s and having no harmful defects on the surface was obtained.
[0181]
Immediately thereafter, the flow rate of nitrogen gas ejected from the molding surfaces 211a and 221a is 20 liters per minute, the flow rate from the molding surfaces 216a and 226a is 14 liters and 12 liters per minute, respectively, and the temperature is 10 in terms of glass viscosity.5.8The temperature is set to 680 ° C. corresponding to dPa · s (first cooling start), and the rotational speed is 200 rpm in the rotational direction in which the lower mold component 2 and the upper mold component 3 are rotated in the opposite directions. The mold unit 1 was closed at a rate of 8 mm per second until the center thickness of the glass lump 102a reached 3.5 mm while gradually increasing the rotation speed so that the center thickness of the lens became 3.33 mm. Sometimes, while gradually increasing the pressure so that the pressure to close the mold unit 1 becomes 25 kgf, at the same time, the viscosity near the surface of the lens is 107.6The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product. At this time, the average thickness of the gas layer was 12 microns.
[0182]
Further, immediately after that, the gas ejection and the rotation of the mold constituent members 2 and 3 are stopped, and the mold unit is closed by applying a pressure of 100 kgf, and the pre-formed product and the molding surface of the mold member are in contact with each other. The shape of the preform was adjusted to the shape of the molding surface.
Following the first cooling step until the above preformed product is obtained, second cooling is performed in the same manner as in the twelfth embodiment immediately after obtaining the preformed product. At that time, after the shape of the preform matches the shape of the molding surface, a pressure of 75 kgf was applied to the mold constituent members 2 and 3 from the outside to cause the mold members 11 and 21 to follow the contraction in the thickness direction of the lens. . After starting cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature was about 515 ° C.), the pressure on the mold components 2 and 3 was released, the mold unit 1 was opened, the lens was taken out, and cooled to room temperature. Furthermore, the accuracy was measured at a temperature of 20 ° C, which is the same temperature as the use conditions, for a plurality of molded lenses, but all of them were within 1 Newton ring and a habit of less than 0.5 Newton rings. Accurate accuracy could be obtained.
[0183]
In addition, the reproducibility of the switching timing of the temperature and pressurizing / depressurizing operation at the time of multiple moldings is within a variation range of 10 ° C at all temperature control points. Variations in speed and the number of revolutions of the lower mold component 2 and the upper mold component 3 were also within 5%, but as a result of continuing molding while slightly changing the conditions, this temperature and speed variation range was exceeded. It was confirmed that the accuracy deteriorated.
[0184]
To summarize the twelfth to fourteenth embodiments, in the twenty-first method, the first step is the precision element at the temperature when transferring the molding shape of the precision element, when using the precision element, or when processing the mold unit. The amount of heat shrinkage including the amount of difference in shape due to the difference in thermal expansion between the mold unit and the mold unit, and the occurrence position and amount of precision element sinks due to uneven heat distribution during molding and cooling are determined in advance in the mold. By making corrections, the molded precision element can obtain a desired shape. In addition, the molding surface of the mold unit is made of a porous material, and a fluid such as air or N2 gas is ejected from the molding surface toward the molding material to form a very thin fluid film on the molding surface. Contact between the softened molding material and the molding surface can be prevented. For this purpose, the porous material is made of a material having a maximum pore diameter of 20 microns or less, preferably 10 microns or less and a porosity of 10 to 35%. The material is oxidation-resistant alumina, silicon nitride, carbonized carbon. Ceramics such as silicon, porous carbon, etc. are used, and the surface of the molding surface is also protected from tearing the fluid film and scratching the molding material, and also to ensure transferability of surface accuracy during contact. It is necessary to have a smooth mirror surface with no protrusion and processed to a roughness that can ensure the function of the precision element.
[0185]
Next, when preparing the molding material of the precision element by the second step, the surface of the part corresponding to the part that becomes the functional surface after molding of the molding material, so as not to cause defects in the precision element after molding, This is a smooth finishing process, in which the surface of the portion corresponding to that portion is optically removed, that is, a defect that cannot be eliminated by press molding in advance. Specifically, the surface is finished so that there is no sharp step with a height difference of 5 microns or more, so that there is no sharp portion when viewed microscopically such as scratches and chips. Is to process. This treatment is performed by a conventional method such as grinding and polishing, surface etching by acid treatment, softening of the surface by flame or hot air, and the like.
[0186]
Furthermore, by performing the third step, it becomes possible to heat and soften the molding material in a non-contact state with the molding surface of the mold unit, so that the molding surface may be affected after molding on the mold unit. It is possible to obtain a softened molding lump with no defects and a very smooth surface. At this time, the molding material is 103-109By heating the molding material to a temperature showing a viscosity of dPa · s, it is possible to connect to the next fourth step.
[0187]
Next, in the fourth process, it is possible to prevent the contact between the molding surface and the molding material by closing the mold unit while ejecting fluid from the molding surface of the mold. It is possible to obtain a preform having a shape that makes it easy to obtain a surface and having no defects on the surface. The shape of the preform obtained in this process is that the molding material does not undergo major deformation when pressed in the next process, and the deformation is not due to the flow of the molding material, but is apparently almost a deformation due to bending. It is desirable that the shape is sufficient with such a slight deformation. For this purpose, the shape of the preform is 0 to 3% thicker than the thickness in the press direction of the precision element of the corrected shape obtained in the next step, or more than the thickness. It is desirable that the thickness does not exceed 0.5 mm, and the outer diameter is also almost the same, but the shape is slightly smaller, and the pressure applied in the next process is applied as evenly as possible to the entire preform. It is desirable that the shape be similar to the molding surface so that the deformation amount is the same as much as possible. In addition, by adopting such a shape, the molding in the next process becomes a deformation mainly composed of bending, and the fine transfer of the hole portion of the porous material forming the molding surface is suppressed. Thus, it is possible to obtain a precision element having a surface in which the shape remains. Furthermore, a reproducible and stable preform can be obtained by reliably reproducing the closing speed, timing, pressure, flow rate / pressure, temperature, etc. of the fluid to be ejected in this step. This is the mold unit, the molding material is 103-109When the temperature is in the temperature range showing the viscosity of dPa · s and the shape of the preform is obtained, the fluid film thickness is 20 microns or less, and when obtaining a preform with a more stable shape, it is 10 microns or less. In this way, the pressure and flow rate of the fluid are controlled, and at the same time, the pressure and speed at which the mold is closed are controlled while the film thickness of the fluid is controlled in inverse proportion to the temperature of the molding material so as to be within the above range. This is achieved by imitating the corrected shape of the molding surface. The operation when closing the mold unit is desirably controlled in accordance with the temperature of the molding material, and the temperature variation in each operation is 10 ° C. or less, preferably 5 ° C. or less. The temperature of the mold unit should be within the same range, and the flow rate and pressure variation of the fluid and the speed and pressure variation of closing the mold unit should be within 5%, preferably within 3%. Can be transferred more stably.
[0188]
In the next fifth step, the preformed product obtained in the previous step is brought into contact with the molding surface of the mold member, and the shape of the corrected molding surface is accurately transferred to the preformed product. This is performed to determine the shape of the element, and press molding is performed under the condition that the surface of the preform does not transfer a fine shape. This is because the viscosity in the vicinity of the surface of the preform is high so as not to transfer the shape of the porous hole that is the fluid ejection hole of the molding surface of the mold member made of the material as described above. At that point, specifically 107.6When the viscosity reaches dPa · s or more, the shape is corrected by applying pressure while the preform is in contact with the molding surface of the mold member, and the corrected molding surface is transferred to the preform. Similarly, it is desirable that the pressure at this time is a pressure that does not transfer the shape of the hole, specifically 5 MPa or less, preferably 2 MPa or less. However, this pressure is the pressure when the viscosity of the molding material and the shape of the hole are as described above. If the viscosity is high or the size of the hole is finer, higher pressure can be applied. is there.
[0189]
The first cooling in the next sixth step is performed in order to control the viscosity of the molding material and transfer the corrected shape of the molding surface of the mold unit to the molding material to obtain a preform with a stable shape. In order to obtain a preform with a stable shape, cooling is gradually performed while controlling the viscosity of the molding material and the film thickness of the fluid. When the first cooling is completed, the preform is molded with a fluid film having a controlled thickness between the molding surface and the shape accuracy of the preform required for the next process is ensured. Is done. In addition, at the time of completion of the first cooling, it is desirable that the molding material, the mold unit, the temperature of the fluid, and the like be within the aforementioned ranges. The second cooling after thatFirst coolingCooling here can be performed at a faster speed, and the corrected shape once transferred matches the shape before correction due to cooling, that is, the original desired shape of the precision element. This is performed so as not to cause variation. For this purpose, it is necessary to accurately reproduce various conditions such as the cooling start temperature, the cooling rate during cooling, and the temperature distribution. Similar to the above, this reproducibility is 10 times the viscosity of the molding material from the start of cooling.12Stable shape reproducibility can be obtained by setting the temperature variation within the temperature range indicating dPa · s to 10 ° C. or less, preferably 5 ° C. or less. Further, the cooling rate and the temperature distribution during cooling at this time are determined when determining the corrected shape of the molding surface within a range that does not cause cracks in the molding material or defects due to large birefringence.
[0190]
The next seventh step is a step of correcting a shape shift during cooling due to a difference in heat shrinkage between the molding surface of the mold member after the shape transfer and the molding material. This is usually because the molding material in a temperature state that can be deformed under pressure has adhesive force, and in particular, in the molding in which the molding surface of the mold member is accurately finished to a mirror surface state and the surface state is transferred, This force acts as a strong adhesion between the surface of the molding material and the molding surface. This force is easily influenced by the shape of the contact surface and the fine state of the interface of the contact surface. Therefore, the magnitude of the force is unstable and the distribution state is not uniform, so the entire contact surface is uniform. In some cases, the surface state is unstable and the molded surface becomes discontinuous in some cases. As a result, there is a problem that the desired shape cannot be finally matched. This problem is that at least the adhesion between the surface of the element and the molding surface is maintained between the mold and the material while the adhesive force is large enough to deform the transfer surface. It is possible to solve the problem only by causing the mold member to follow the shrinkage.
[0191]
Further, the second cooling is performed until the follow-up process of the mold member is completed, and then the mold unit is opened and the molding element is taken out (eighth process) to have a shape approximate to a desired shape. A molded element can be obtained. Further, the end point of the second cooling, that is, the completion time of the follow-up process of the mold member is determined depending on the adhesion force.12~14.5Ideally, it is performed at dPa · s.
[0192]
In the next ninth step, the molded element having a shape approximated to the desired shape is further cooled to room temperature, whereby heat shrinkage occurs, and the element becomes the shape of a precision element having the desired shape. Can be obtained.
(Fifteenth embodiment)
Next, another embodiment for molding exactly the same one as the first embodiment will be described. The molding surface 11a of the lower mold 11 and the molding surface 21a of the upper mold 21 are exactly the same as in the sixth embodiment, except that the final shape transfer temperature is 10% for the glass material.8The shape obtained by setting the temperature at a viscosity of dPa · s and determining the shape was used.
[0193]
First, a glass lump 102a was obtained on the molding surface 11a by the same method as in the first example.
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the molding surface 11a of the glass lump 102a is 10.6-107.5dPa · s, the viscosity in the vicinity of other surfaces is 103~6While the vicinity of the center is sufficiently soft, the flow rate of the nitrogen gas ejected from the molding surface 11a and the molding surface 21a is 20 liters per minute, and the temperature is 650, which corresponds to the glass viscosity of 106.5 dPa · s. Pressure / flow rate regulators 32a, 32b and heaters 33a, 33b are controlled by controller 41 (first cooling start) so that the temperature becomes 5 ° C., and a speed of 5 mm per second until the central thickness of glass lump 102a becomes 3.2 mm. The mold unit 1 was closed. Next, the temperature and flow rate of the nitrogen gas are adjusted to 610 ° C. (the viscosity of the glass is 10 so that the gas film thickness is about 20 microns.7.6(temperature corresponding to dPa · s) and 10 liters per minute. When the center thickness of the lens when cold is in a position corresponding to 3.05 mm, the mold unit 1 is closed and the pressure applied to the molding surface The mold unit 1 was closed while gradually increasing the pressure so as to be 2 MPa and adjusting the speed so that the viscosity in the vicinity of the lens surface was 107.6 dPa · s to obtain a preformed product.
[0194]
Further, immediately after that, the gas ejection is stopped, and the pressure is gradually increased so that a force of 1.5 MPa and finally 2 MPa is initially applied to the molding surface of the mold unit 1, and the preform and the mold member are closed. The shape of the preform was adjusted to the shape of the molding surface while the molding surface was in contact.
In addition, immediately after obtaining the softened glass lump 102a and before obtaining a preformed product, the first cooling to the molding material was started, and the second cooling was started immediately after obtaining the preformed product. The second cooling is performed by blowing a cooling nitrogen gas from the outside of the mold unit 1 by a cooling device (not shown). At that time, the restriction from the outside to the mold components 2 and 3 is released, The mold member 11 and the upper mold member 21 can follow the contraction of the lens.
[0195]
Immediately after the start of the second cooling, when the viscosity in the vicinity of the lens surface reaches 108 dPa · s, fluid is instantaneously ejected from the molding surfaces 11a and 21a at a pressure of 15 kPa, and at the same time, the mold unit 1 is The lens was slightly opened, the lens was released from the molding surface, and immediately thereafter, the fluid pressure was set to 1.02 kPa, the flow rate was set to 3 liters per minute, and third cooling was performed.
[0196]
After the start of the third cooling, the viscosity near the surface of the lens is 1012When dPa · s (temperature is about 515 ° C), the mold unit 1 is completely opened, and the lens is taken out with a suction hand (not shown) while nitrogen gas is being blown out from the lower mold member 11. It was. Furthermore, the accuracy was measured at a temperature of 20 ° C., which is the same temperature as the use conditions, for a plurality of molded lenses, but all of them were within 1.7 Newton rings and one habit of Newton rings. It was possible to obtain accuracy that could withstand normal use.
[0197]
Note that the reproducibility of the temperature and the switching timing of the operation such as pressurization / depressurization at the time of the plurality of moldings is a variation of 20 ° C. at all temperature control points until the completion of the second cooling. However, the variation in the opening / closing speed of the mold unit was within 5%, but as a result of continuing molding while slightly changing the conditions, this variation in temperature and speed It was confirmed that the accuracy deteriorated when the above range was exceeded.
[0198]
(Sixteenth embodiment)
Next, using the same apparatus and material as in the fifteenth embodiment, using the same material, one side has an aspherical shape based on R50 mm and the other side is R40 mm. The center thickness of the lens is 4.3 mm and the diameter is Φ23 mm. A biconvex glass aspheric lens for a compact camera was molded.
[0199]
As in the fifteenth embodiment, the molding surface 11a of the lower mold member 11 and the molding surface 21a of the upper mold member 21 are processed into a shape that takes into account numerous corrections obtained by simulation before molding, and then actually Molding was performed and final correction was performed based on the shape data to determine the shape. Specifically, as in the seventeenth embodiment, in the case of the molding surface 21a of the upper mold 21, as shown in FIG. 3A, a shape 201 (20 ° C.) that is a standard use condition of a lens that is a precision element. The temperature at the time of shape transfer at the time of molding is 10 in terms of glass viscosity.12The temperature indicating dPa · s is set to 515 ° C., and the amount of deformation due to temperature expansion of the glass, which is a part of the first correction amount, is calculated. From the result, the shape 204 of the precision element under this condition is obtained. Asked. Next, a correction amount 205 due to sink marks due to cooling after shape transfer, which corresponds to the second correction amount, is obtained, a partial shape 206 of the molding surface at the time of shape transfer is determined, and further the first correction amount. From the amount of correction due to the temperature shrinkage of the material of the molding surface of the mold unit, which corresponds to the remaining part of the molding unit, the molding surface shapes 207 and 207a ( 3A, the shapes of hatched portions 207 and 207a) were obtained. Then, according to the shape data, the molding surface 21a of the upper mold member 21 is processed into a mirror surface state in which the surface excluding the hollow of the porous hole portion is within 0.2 due to Newton ring deviation, The lens was actually molded under the molding conditions determined by simulation. Next, the shape of the molded lens was measured, and the portion slightly deviated from the predetermined shape was corrected again, and finished to a smooth mirror surface state without a bulge to obtain the final shape of the molding surface 21. Further, the molding surface 11a of the lower mold member 11 was processed for its shape by the same method. The mold members 11 and 21 are made of porous AlO having a porosity of 25% and a maximum hole diameter of 6 microns.3And clean air was used as the fluid. A carbon film as a release layer was deposited on the surface of the molding surface so that the porous holes were not blocked. The release layer is not particularly limited to the carbon film as long as it does not prevent the mold and the glass from being fused and loses the specularity of the molding surface.
[0200]
Next, the mold members 11 and 21 prepared for processing in this way were attached to the molding apparatus shown in FIG. 1, and a glass lump 102a in a softened state was obtained in exactly the same manner as in the fifteenth embodiment.
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the lower mold member 11 of the glass lump 102a is 10.6-107.5dPa · s, the viscosity in the vicinity of other surfaces is 103~6dPa · s, while the vicinity of the center is sufficiently soft, the flow rate of air ejected from the molding surfaces 11a and 21a is 25 liters per minute, and the temperature is 10 in terms of glass viscosity.6.5The controller 41 controls the pressure / flow rate regulators 32a and 32b and the heaters 33a and 33b so that the temperature becomes 650 ° C. corresponding to dPa · s (first cooling starts), and the center thickness of the glass block 102a is 4. The mold unit 1 was closed at a speed of 8 mm per second until 6 mm. Next, the temperature and flow rate of the blown air were set to 600 ° C. and 15 liters per minute, and when the center thickness of the lens when cold was at a position corresponding to 4.32 mm, the mold unit 1 was closed to the molding surface. The pressure in the vicinity of the surface of the lens is increased to 10 at the same time while gradually increasing the pressure so that the pressure becomes 4.5 MPa.7.9The mold unit 1 was closed while adjusting the speed so as to be dPa · s to obtain a preformed product. At this time, the film thickness of the gas was about 8 microns.
[0201]
Further, immediately after that, the gas injection is stopped, and the pressure is gradually increased so that a force of 2 MPa is initially applied to the molding surface of the mold unit 1 and 3 MPa is applied when the shape is first transferred. The shape of the preform was adjusted to the shape of the molding surface while the product and the molding surface of the mold member were in contact with each other.
Following the first cooling step until the above preformed product is obtained, the second cooling is performed in the same manner as in the fifteenth embodiment immediately after the preformed product is obtained. At that time, after the shape of the preform is changed to the shape of the mold, a pressure is gradually applied to the mold components 2 and 3 from the outside so that the pressure finally becomes 8 MPa when the second cooling is completed. 11 and 21 were made to follow contraction in the thickness direction of the lens. After the start of the second cooling, the viscosity near the surface of the lens is 1012At the time when dPa · s (temperature is about 515 ° C.), the pressurization to the lower mold member 2 and the upper mold member 3 is released, and at the same time, the fluid flows from the molding surfaces 11a and 21a as in the fifteenth embodiment. Was ejected to release the lens from the molding surface. Thereafter, the flow rate was further set to 7 liters, the third cooling was performed, and the temperature of the lens surface was 498 ° C. (the viscosity of the glass was 1013The mold unit 1 was completely opened when the pressure was lower than dPa · s), and the lens was taken out with a suction hand (not shown) while air was being blown out from the lower mold member 11. Furthermore, this molding is repeated several times, and the temperature and the reproducibility of the timing such as pressurization / decompression are within a temperature range of 10 ° C. until the completion of the second cooling, and then 5 ° C. Molding was carried out while strictly controlling the variation to be within 3%. After that, the accuracy of the completed lenses was measured at a temperature of 20 ° C., but all the ashes were within 1 Newton ring and the habit was within 0.5 Newton rings, which is better than the fifteenth embodiment. The result was obtained.
[0202]
(Seventeenth embodiment)
Next, the mold member shown in FIG.15thUsing the molding apparatus used in the embodiment, the diameter is Φ10 mm, the convex radius of curvature is R20 mm, the concave radius of curvature is R30 mm, the central thickness is 3.3 mm, and the peripheral thickness is about 3.1 mm. A convex meniscus lens was formed. Here, in FIG. 4, 211 and 221 are a lower mold member and an upper mold member, respectively, and molding surfaces 211a and 221a forming an optical surface of the lens are processed. Further, ring members 216 and 226 having molding surfaces 216a and 226a forming the lower and upper portions of the periphery of the lens are attached to the outer periphery of the lower mold member 211 and the upper mold member 221, respectively. The lower mold member 211 and the upper mold member 221 are porous silicon nitride having a porosity of 15% and a maximum hole diameter of 15 microns, and the ring members 216 and 226 are porous silicon nitride having a porosity of 10% and a maximum hole diameter of 20 microns. The fluid can be independently supplied to each pressure chamber 12b, 12c, 22b, 22c from a supply device (not shown), and the molding surface and the peripheral edge of each optical surface The film thickness of the fluid between the molding surface of the part and the molding material can be controlled independently. Moreover, the same glass material as 6th Embodiment was used for the shaping | molding raw material, and nitrogen gas was used as a fluid. Further, the same release layer as in the sixteenth embodiment was used.
[0203]
In this embodiment, the shapes of the molding surfaces 211a and 221a of the optical surface of the lens and the molding surfaces 216a and 226a of the peripheral portion are once processed by preliminarily processing the cold shape of the lens on the molding surface, The correction processing amount of the molding surface was calculated so as to correct the shape error of the molded optical element, and it was reflected again on the shape of the molding surface and processed again to finish it in a mirror surface state. Further, the temperature at the time of shape transfer in the preforming is 555 ° C. (10% in terms of glass viscosity).10dPa · s).
[0204]
Next, the mold members 211, 211, 216, and 226 prepared in this way were attached to the molding apparatus shown in FIG. 1 similarly to the seventeenth embodiment, and a softened glass lump was obtained by the same method. The temperature of the nitrogen gas at this time is 500 ° C., which is the temperature near the glass transition point when the glass is received on the molding surface 211a, and immediately after that, the viscosity of the glass is 10%.7.3The temperature is adjusted to 620 ° C. which is a temperature corresponding to dPa · s, and the flow rate of nitrogen gas is 18 liters per minute on the molding surface 211a until just before the molten glass 102 is received on the molding surface 211a. The surface 216a was controlled to be 8 liters per minute, and thereafter, both were 5 liters per minute.
[0205]
Next, the lower mold component 2 is moved directly below the upper mold component 3, and the viscosity in the vicinity of the lower surface received by the lower mold member 211 of the glass lump 102a is 10.5.6-107dPa · s, the viscosity in the vicinity of other surfaces is 103-105.6The flow rate of nitrogen gas ejected from the molding surfaces 211a and 221a is 20 liters per minute and the flow rate from the molding surfaces 216a and 226a is 14 liters and 12 liters per minute respectively while the center is sufficiently soft. And the temperature is 10 as the viscosity of the glass.5.8The temperature is set to 680 ° C. corresponding to dPa · s (first cooling start), and the rotational speed is 200 rpm in the rotational direction in which the lower mold component 2 and the upper mold component 3 are rotated in the opposite directions. The mold unit 1 was closed at a speed of 8 mm per second until the center thickness of the glass lump 102a reached 3.5 mm while gradually increasing the rotation speed so that Next, in a state where the lower mold component 2 and the upper mold component 3 are kept rotating, the temperature of the nitrogen gas is 610 ° C., and the flow rate from the molding surfaces 211a and 221a is adjusted every minute so that the film thickness is about 12 microns. When the flow rate from the 15 liters and the molding surfaces 216a and 226a is set to 12 liters and 11 liters per minute, respectively, and the center thickness of the lens when cold is at a position corresponding to 3.33 mm, While gradually increasing the pressure so that the pressure for closing the unit 1 is 2.5 MPa on the molding surface, and simultaneously adjusting the speed so that the viscosity in the vicinity of the lens surface becomes 107.6 dPa · s, the mold unit 1 Was closed to obtain a preform.
[0206]
Further, immediately after that, the ejection and rotation of the gas are stopped, and the viscosity near the surface of the lens is 10%.8.5When the pressure reaches dPa · s, the molding surface of the mold unit is further closed by applying a pressure of 10 MPa, and pressure is applied while the preformed product and the molding surface of the mold member are in contact with each other. Matched to the shape of the molding surface.
Following the first cooling step until the above preformed product is obtained, the second cooling is performed in the same manner as in the fifteenth embodiment immediately after the preformed product is obtained. At that time, after the shape of the preform is changed, the mold components 2 and 3 are further gradually reduced in pressure from the outside to the molding surface so that the pressure finally becomes 7.5 MPa when the second cooling is completed. While going, the mold members 11 and 21 were made to follow contraction in the thickness direction of the lens. After starting cooling, the viscosity near the surface of the lens is 1010When dPa · s (temperature is about 555 ° C.), fluid is ejected from the molding surfaces 11a and 21a in the same manner as in the seventeenth embodiment, and at the same time, the pressure on the mold components 2 and 3 is released. The lens was released. Immediately thereafter, the fluid temperature was set to 150 ° C., the flow rate was set to 5 liters per minute, and at the same time, the mold components 2 and 3 were rotated at a speed of 150 rpm in the direction of rotation in which the directions were opposite. The third cooling was carried out while making the fluid film thickness uniform. When the viscosity of the glass exceeded 1013 dPa · s, the mold constituent members 2 and 3 were stopped. At the same time, the mold unit 1 was opened, the lens was taken out, and cooled to room temperature. Furthermore, the accuracy was measured at 20 ° C, which is the same temperature as the operating conditions, for a plurality of molded lenses, but all the Asches were 1.2 Newton rings and the habits were less than 0.5 Newton rings. Enough accuracy could be obtained.
[0207]
In addition, the reproducibility of the temperature and the switching timing of the operation such as pressurization / decompression in the plurality of moldings is within the same range as that of the fifteenth embodiment, and the opening / closing speed and lowering of the mold unit. Variations in the rotational speed of the mold component 2 and the upper mold component 3 were also within 5%. However, as a result of continuing molding while further changing the conditions, the accuracy would be exceeded if the temperature and speed variations were exceeded. It was confirmed that it would get worse.
[0208]
In these aforementioned embodiments, a compressible fluid is used as the fluid, but it goes without saying that the same effect can be obtained even when an incompressible fluid such as a molten salt is used.
As described above, according to the fifteenth to seventeenth embodiments described above, it is possible to avoid fusion, surface transfer failure, and deterioration of the molding surface due to contact between the molded product and the molding surface of the mold. In addition, it is possible to avoid shape transfer defects due to the difference in thermal expansion between the molding surface of the mold and the molded product, and extremely reduce waste such as grinding polishing waste generated by processing methods such as grinding and polishing. Therefore, a large amount of precision elements such as optical lenses can be provided at a low cost.
[0209]
The fifteenth to seventeenth embodiments are summarized as follows. In the twenty-second method, the first step is a precision element at the temperature when transferring the molding shape of the precision element, using the precision element, or processing the mold unit. The amount of heat shrinkage including the amount of difference in shape due to the difference in thermal expansion between the mold unit and the mold unit, and the occurrence position and amount of precision element sinks due to uneven heat distribution during molding and cooling are determined in advance in the mold. By correcting, it is possible to obtain the desired shape of the molded precision element. At this time, the fluid existing between the molding surface and the preform when the preform is obtained It is also necessary to correct the thickness. In addition, the molding surface of the mold unit is made of a porous material, and a fluid such as air or N2 gas is ejected from the molding surface toward the molding material to form a very thin fluid film on the molding surface. Contact between the softened molding material and the molding surface can be prevented. For this purpose, it is made of a material having a maximum porous hole diameter of 20 microns or less, preferably 10 microns or less and a porosity of 10 to 35%. Using ceramics such as silicon, porous carbon, etc., and forming the surface of the molding surface at a stage where the fluid film is not broken and the molding material is not damaged, and a precision element with a corrected shape is obtained. In order to ensure transferability at the time of contact between the surface and the preliminary product, it is necessary to have a smooth mirror surface without protrusions and to have a desired surface accuracy that can ensure the function of the precision element.
[0210]
Next, in the second step, the molding material and the molding surface of the molding unit that are likely to be generated when the molding material in contact with the mold, particularly the melted and softened shape, flows out of the nozzle and is supplied to the molding unit. Can be prevented, and at this time, contact can be reliably prevented by lowering the temperature of the fluid temporarily ejected or increasing the flow rate. In addition, when the molding material supplied on the molding surface of the mold unit is cut and separated from the nozzle, after the required amount of molding material is received on the mold unit, the mold unit is once lowered and the molding material flows out from the nozzle. By forming a constriction between the material and the molding material on the mold unit, and further developing and separating the constriction due to the weight and surface tension of the molding material, defects that may affect the mold unit after molding It is possible to obtain a molding material lump having a very smooth surface and no surface.
[0211]
Next, in the third step, it is possible to prevent the contact between the molding surface and the high-temperature molding material by closing the mold unit while ejecting fluid from the molding surface of the die. It is possible to obtain a preform having a shape that makes it easy to obtain a precision element and having no surface defects. The shape of the preform obtained in this process is that the molding material does not undergo major deformation during pressing in the next process, and the deformation is not due to the flow of the molding material, but is apparently almost a deformation due to bending. It is desirable that the shape is sufficient with such a slight deformation. For this purpose, the shape of the preform is 0 to 3% thicker than the thickness in the pressing direction of the corrected precision element obtained in the next step, or more than the thickness. It is desirable that the thickness does not exceed 0.5 mm and the outer diameter is almost the same or slightly smaller, and the pressure applied in the next process is applied to the entire preform as evenly as possible. It is desirable that the shape be similar to the molding surface so that the amount of deformation is the same as much as possible. In addition, by adopting such a shape, the molding in the next process becomes a deformation mainly composed of bending, and the fine transfer of the hole portion of the porous material forming the molding surface is suppressed. Thus, it is possible to obtain a precision element having a surface in which the shape remains. Furthermore, it is possible to obtain a reproducible and stable shape preform by reliably reproducing the closing speed, timing, pressure, flow rate, pressure, temperature, etc. of the fluid to be ejected in this process. I can do it. This is the mold unit, the molding material is 103-109When the temperature is in the temperature range showing the viscosity of dPa · s and the shape of the preform is obtained, the fluid film thickness is 20 microns or less, and when obtaining a preform with a more stable shape, it is 10 microns or less. In this way, the pressure and flow rate of the fluid are controlled, and at the same time, the pressure and speed at which the mold is closed are controlled while the film thickness of the fluid is controlled in inverse proportion to the temperature of the molding material so as to be within the above range. This is achieved by following the corrected shape of the molding surface. Further, the operation when closing the mold unit is preferably controlled in accordance with the temperature of the molding material, and the temperature variation in each operation is 10 ° C. or less, preferably 5 ° C. or less, and the fluid to be ejected similarly. It is desirable to keep the temperature within the same range, and the variation of the flow rate and pressure of the fluid and the variation of the speed and pressure of closing the mold unit should be within 5%, preferably within 3%, so that the shape of the preform can be improved. It can be obtained stably. .
[0212]
In the next fourth step, the preform obtained in the previous step is brought into contact with the molding surface of the mold member, the shape of the corrected molding surface is accurately transferred to the preform, and the precision after cooling is completed. This is performed to determine the shape of the element, and press molding is performed under the condition that the surface of the preform does not transfer a fine shape. This is because the viscosity in the vicinity of the surface of the preform is high so as not to transfer the shape of the porous hole that is the fluid ejection hole of the molding surface of the mold member made of the material as described above. At that point, specifically, the glass softening temperature is 107.6When the temperature is lower than the temperature indicating the viscosity of dPa · s, the shape is corrected by applying pressure in a state where the preform and the molding surface of the mold member are in contact with each other, and the shape of the corrected molding surface is changed to the preform. Similarly, it is desirable that the pressure at this time be a pressure that does not transfer the shape of the hole, specifically, 5 MPa or less, preferably 2 MPa or less. However, this pressure is the pressure when the viscosity of the molding material and the shape of the hole are as described above. When the viscosity is high or the size of the hole is finer, higher pressure can be applied. is there.
[0213]
The next fifth step is to force the precision element of the corrected shape in close contact with the corrected shape of the molding surface to re-eject the fluid from the porous hole of the molding surface and lift the precision element from the molding surface. At the same time, if necessary, the step of releasing the precision element from the molding surface to release it from the molding surface and releasing the mold to provide a gap between the precision element and the molding surface. This is done to prevent the shape of the precision element that has been shaped and corrected from deteriorating due to the shrinkage difference between the mold and the molding material during cooling. It is carried out in a temperature range that does not easily deform due to other external forces and does not increase the difference in shrinkage between the mold and the material. The specific temperature range is a viscosity that does not cause deformation at the initial stage of the mold release action and cooling in the non-contact state in the next process with respect to the upper limit.8dPa · s or more, preferably 109It is necessary to carry out at a temperature not higher than dPa · s. Also, the lower limit temperature should be higher than the temperature at which the difference in thermal shrinkage becomes large and the molding material cannot follow the shrinkage of the mold, and it depends greatly on the difference in the expansion coefficient between the molding material and the mold. , Molding material is 1012It is desirable that the temperature be equal to or higher than a temperature showing a viscosity of dPa · s or lower. In order to facilitate the mold release operation in this process, it is better that the surface of the molding surface of the mold is made of a material having poor wettability with a molding material typified by carbon or platinum. Bring.
[0214]
The first cooling in the next sixth step is performed in order to control the viscosity of the molding material and transfer the corrected shape of the molding surface of the mold unit to the molding material to obtain a preform with a stable shape. The cooling is gradually performed while controlling the viscosity of the molding material so that the film thickness of the fluid is reached when the first cooling is completed. When the first cooling is completed, the preform is molded with a fluid film having a controlled thickness between the molding surface and the shape accuracy of the preform required for the next process is ensured. Is done. In addition, at the time of completion of the first cooling, it is desirable that the molding material, the mold unit, the temperature of the fluid, and the like be within the aforementioned ranges. Further, the second cooling after that is performed to the above-mentioned temperature so that the corrected shape once transferred by contact is almost solidified and the shape does not change at the time of mold release. This is done so that it does not occur. For this purpose, it is necessary to accurately reproduce the cooling start temperature, the cooling rate and temperature distribution at the time of cooling, and particularly the temperature and temperature distribution at the time of completion of cooling that is at the time of mold release. When the reproducibility at this time is 20 ° C. or less, preferably 10 ° C. or less as the temperature variation until release, a stable shape reproducibility can be obtained. Further, the cooling rate and the temperature distribution during cooling at this time are determined when determining the corrected shape of the molding surface within a range that does not cause cracks in the molding material or defects due to large birefringence. Further, the subsequent third cooling can be performed at a faster speed than the first and second cooling, and the cooling here is performed by changing the correction shape once transferred before the mold release to the shape before correction by cooling. That is, it is performed so as to coincide with the original desired shape of the precision element and to prevent variation due to cooling shrinkage in continuous molding. For this purpose, it is necessary to accurately reproduce various conditions such as the third cooling start temperature (= release temperature) when the correction shape is determined and the temperature distribution during cooling. This reproducibility is a viscosity at which the precision element molded from the start of cooling is less likely to be deformed as described above.12For materials that require dPa · s, more precise transferability, or complex shapes, the molding material has a viscosity that does not newly generate distortion 1014.5Stable reproducibility can be obtained by setting the temperature variation up to dPa · s to 30 ° C. or less, preferably 15 ° C. or less. In addition, the cooling rate and the temperature distribution during cooling are determined when determining the corrected shape within a range that does not cause cracks in the molding material or defects due to large birefringence. In order not to cause deformation due to the pressure of the fluid or the fluid, it is desirable to cool the surface of the precision element at a rate of 20 ° C. or more per minute, and the fluid pressure and flow rate are not abruptly changed. It is desirable to do so. Through the above-described cooling, at the end of this step, the shape of the molding surface of the mold unit and the shape of the molded precision element are corrected for the difference between the respective expansion coefficients and the previously estimated sink mark. However, because the amount of correction is not completely the same, the shape of the precision element is not affected by the shape of the molding surface of the mold unit, and the desired shape can be maintained.
[0215]
The next seventh step is a step of correcting a shift in shape due to a difference in heat shrinkage between the molding surface of the mold member and the molding material at the time of shape transfer during the second cooling. This is because the molding surface of the mold member is accurately finished into a mirror surface state, and in molding that transfers the surface state, molding is performed if there is a difference in shrinkage during cooling between the mold member and the molding material. The shape contacts the molding surface unevenly during cooling, partially transfers the shape of the molding surface of the mold at that temperature, and the molding surface of the precision element after mold release becomes distorted or discontinuous It is a process to prevent the surface shape from becoming the original desired surface shape, and it is impossible to obtain the desired surface shape. This can only be solved by bringing the precision element into close contact with the surface of the precision element so as to follow contraction in the thickness direction of the precision element. The following of the mold member to the surface of the precision element may be performed using the adhesion force between the molding surface and the precision element, but it increases the certainty and does not depend on the shape of the precision element. In order to achieve this, it is desirable to apply pressure to the mold member from the outside.
[0216]
In the final eighth step, the precision element already solidified as described above is taken out of the mold unit to obtain a precision element having a desired shape transferred. At this time, a film made of a fluid is interposed between the precision element and the molding surface of the mold unit, so that the surface of the precision element is prevented from being damaged due to contact with the molding surface. In addition, the molding surface can be prevented from being damaged by contact with the solidified precision element.
[0217]
In the twenty-third method, the pre-corrected shape of the molding surface is a mold made of a temperature and viscosity of the molding material, a pressure and temperature applied to the mold unit, and a molding material and a porous material. By simulating the coefficient of thermal expansion of the member as a parameter of molding conditions, predicting the shape of the precision element to be molded in advance, and correcting the shape of the molding surface of the mold unit based on it A precision element having a shape and surface accuracy can be obtained. This correction is a combination of the first correction associated with the difference in thermal expansion between the mold member and the molding material and the second correction for canceling sink marks or the like associated with cooling of the molding material. By performing this correction at the time of shape processing, it is possible to make the shape of the precision element coincident with the desired shape when molding is completed and taken out of the mold unit and further cooled.
[0218]
Here, the first correction is the molding surface of the mold member, which is generated due to the temperature difference between the shape transfer and the shape processing of the mold member or when using the precision element, and the difference in thermal expansion coefficient between the mold member and the molding material. This is correction of the amount of deviation of the shape of the precision element. Specifically, the shape of the desired precision element at the operating temperature is changed to the final shape transfer temperature until the follow-up of the mold member during the second cooling ends. Calculate the shape change amount of the precision element due to the temperature difference by the expansion coefficient of the molding material, and further change the shape change amount of the precision element from the final shape transfer temperature to the temperature difference when processing the molding surface of the mold unit The amount calculated by the expansion coefficient of the mold member as the amount of change in shape is used as the first correction amount of the shape of the molding surface of the mold member. The second correction is a correction of a deformation amount including a partial deformation due to shrinkage or sinking due to cooling in the mold and after removal from the mold after the precision element has transferred the shape. The temperature distribution of the molding material itself, the resulting viscosity distribution and the coefficient of thermal expansion, and the stresses calculated by them, governed by the ever-changing temperature of the fluid and mold unit, the retained heat and temperature conductivity of the molding material The amount of sink is calculated based on the stress relaxation coefficient unique to the molding material, and the amount of shape change due to the molding material's own weight or fluid pressure change is added to that amount. This is the amount of correction.
[0219]
In the twenty-fourth method, an element having a shape that approximates the final shape of a desired precision element is formed in advance, and information obtained from the shape data during and after the forming and shape data is formed. By feeding back to the surface shape, an optical element having a highly accurate shape and surface accuracy can be obtained. This correction method uses a mold unit having a molding surface with a shape almost the same as the shape of a precision element first, pre-sets the element once under fixed conditions, and uses conditions after completion of molding. Compare the shape of the element in the same state with the shape of the molding surface of the used mold unit, and use the amount of the shape difference found there as a correction amount to the molding surface of the mold unit. In the case of simple correction that can be corrected by change, it is possible to match the molded precision element with a desired shape by correcting the molding conditions. In addition, by repeating this correction several times, it becomes possible to obtain a more accurate and stable shape, and the same effect can be obtained by combining the correction method of the molding surface of the mold unit by the above-described simulation. I can do it.
[0220]
In the twenty-fifth method, the temperature of the molding material can be controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. This is because the molding material is not in contact with the mold unit, and the molding material is covered with the mold unit, and it is virtually impossible to measure the temperature of the molding material from the outside. This can be solved by controlling the temperature of the fluid that is in direct contact and indirectly controlling the temperature of the molding material by its heat transfer. Temperature control can be performed. Here, as a method for controlling the temperature of the fluid, it is possible to sufficiently achieve the purpose by directly adjusting the temperature of the fluid in the vicinity of the supply source. By using the heat source such as a heater incorporated in the mold unit, which is the fluid passage just before the fluid touches the molding material, the temperature is adjusted again to achieve better temperature control of the molding material. It can be realized.
[0221]
In the twenty-sixth method, by controlling the ejection pressure of the fluid to be ejected from the molding surface of the molding die, the flow rate of the fluid, and the pressure applied to the mold unit in accordance with the viscosity of the molding material, a highly accurate shape and An optical element having surface accuracy can be obtained. Here, the fluid film between the molding surface of the mold unit and the molding material is controlled by controlling the flow rate and pressure of the fluid and the pressure applied to the mold unit in synchronization with the viscosity change corresponding to the hardness of the molding material. The thickness can be reliably stabilized and controlled, and as a result, the preform and the completed precision element can obtain a stable shape with higher accuracy and less variation even during continuous molding. Is possible.
[0222]
In the twenty-seventh method, the mold member constituting the mold unit is used as a molding material when obtaining a preform having a shape approximate to the shape of the molding surface and when cooling in the mold after the shape transfer. In contrast, by controlling the pressure distribution of the fluid existing between the molding material and the molding surface by rotating and sliding, an optical element having a highly accurate shape and surface accuracy can be obtained. This is because it is easy to make the film thickness of the fluid between the molding material and the molding surface of the mold member uniform by rotating and sliding the mold member with respect to the molding material during pressure molding. Accurate precision elements can be obtained, and the functional surface of the lens, etc. is based on a spherical surface that is symmetrical with respect to the axis, especially by making the film thickness easily uniform on the axis centered on the rotation axis. It is possible to exert a great effect on a precision element having a shape.
[0223]
(Eighteenth embodiment)
FIG. 6 is a diagram of a mold structure for illustrating a molding method according to an eighteenth embodiment of the present invention. Reference numeral 301 is an upper first mold member, reference numeral 302 is a lower first member, reference numeral 303 is an upper second mold member, reference numeral 304 is a lower second mold member, and reference numeral 305 is a second mold member. Reference numeral 306 denotes a ring for fixing the second mold member 304, reference numerals 307 and 308 denote gas passages, and reference numeral 309 denotes a molded product.
[0224]
FIG. 7 shows an optical element 310 obtained by centering a molded product.
SK12 (nd = 1.58313, νd = 59.4, Tg = 506 ° C., At = 538 ° C.) is used as a lens molding material, and thereby a gob (glass lump) having a diameter of 12 mm and a center thickness of 7 mm is used as a preform. Created.
A biconvex lens having R1 = 16.45 mm, R2 = 16.86 mm, center thickness = 4.5 mm, effective beam diameter = Φ12 mm, and outer diameter = Φ14 mm is formed from this material.
[0225]
As a method of manufacturing the mold shown in FIG. 6, gas passages 307 and 308 were formed in the mold members 301 and 302 made of cemented carbide by electric discharge machining. Further, the mold members 303 and 304 made of porous alumina, porous zirconia, porous silicon carbide, porous stainless steel, porous carbon and the like were processed except for the lens surface and inserted into the mold members 301 and 302. Further, fixing rings 305 and 306 were inserted, and the mold members were fixed with fixing pins (not shown). Finally, the lens surface was ground and polished.
[0226]
The inner diameters of the second members 303 and 304 were Φ12.2 mm, which was slightly larger than the effective beam diameter of the optical element.
N2The mold was attached to a press shaft in a molding apparatus under an atmosphere, a glass material was put between the upper and lower molds, and the mold and glass were heated to 580 ° C. Next, the upper die was lowered to start pressing. N after the glass starts to deform by the mold members 301 and 3022The gas was poured into the mold members 303 and 304 and released into the molding chamber through the gap between the upper and lower molds. Before entering the passages 307 and 308, the N2 gas is heated to the mold temperature by a heater (not shown). The gas flow rate is controlled by a flow regulator (not shown).
[0227]
After the deformation was completed, the mold was cooled while keeping the mold temperature and gas temperature equal, and when the mold was cooled to 200 ° C., the upper mold was raised to release the mold from the glass. When the appearance of the molded product taken out was observed with a microscope, the portion corresponding to the first mold member had transferred the fine surface roughness of the mold, but the portion corresponding to the second mold member had a mold contact mark. It was found that the mold and the glass were formed in a non-contact state without any smoothness. The molded product was centered to obtain an optical element 310. The obtained optical element had an accuracy of 0.5 Newton rings with respect to the design value within the effective beam diameter. Further, the deviation from the predetermined curved surface outside the effective beam diameter was about 5 μm, but it was a sufficient value for mechanical accuracy.
[0228]
The above process was performed continuously for 500 shots, and the results are summarized in FIG.
Although 500 shots were performed under various conditions regarding the material, porosity, and gas flow rate of the mold members 303 and 304, the appearance quality was not fused, and good results were obtained with respect to shape accuracy.
(Nineteenth embodiment)
A biconvex lens was formed in the same process using the same apparatus, mold and glass as in the eighteenth embodiment. In the eighteenth embodiment, the mold release temperature is 200 ° C., but here, the mold release temperature is set to 500 ° C. for the purpose of shortening the molding time. The difference is that after the deformation is completed, only the temperature of the gas supplied to the upper second mold member is lowered and the temperature of the gas released from the second mold member is released from the lower second mold member. The temperature of the gas was controlled so that it was kept 10 ° C. below the temperature of the gas being produced. When the mold temperature decreased to 500 ° C., the upper mold was raised and the mold and the glass were released. Since the molded product remained on the lower mold, it could be taken out with an automatic hand immediately. As a result, the molding could be repeated 500 shots continuously. This is not a problem when the mold is released at a low temperature, but when the mold is released at a high temperature such as near the Tg point, the molded product always has a lower mold by providing a temperature difference between the upper and lower gases. It can be controlled to remain.
[0229]
It was investigated whether continuous molding could be performed by changing the temperature difference between the upper and lower mold gases. As a comparative example, when there was no or little temperature difference, the molded product might be attached to the upper mold when it was released from the mold. FIG. 9 shows the relationship between the gas temperature difference and releasability.
(20th embodiment)
FIG. 10 is a diagram of a mold structure for illustrating the molding method of the twentieth embodiment. Reference numeral 311 indicates an upper first mold member, reference numeral 312 indicates an upper second mold member, reference numeral 313 indicates a lower mold, reference numeral 314 indicates a gas passage, and reference numeral 315 indicates a molded product.
[0230]
FIG. 11 shows an optical element 316 made by centering a molded product.
LaK12 (nd = 1.67790, νd = 54.9, Tg = 562 ° C., At = 593 ° C.) is used as a lens molding material, and thereby a gob (glass lump) having a diameter of 23 mm and a center thickness of 12 mm is used as a preform. It was created.
From this material, R1 (concave) = 14.232 mm (aspheric surface), R2 (convex) = 155.3 mm, center thickness = 1.5 mm, outer diameter = Φ29 mm, R1 effective beam diameter = Φ20 mm, R2 effective beam diameter = A concave meniscus lens having a chamfer of 45 degrees on the R1 side at 27 mm is prepared.
[0231]
In the mold manufacturing method shown in FIG. 10, a gas passage 314 is formed in a mold member 311 made of a cemented carbide by electric discharge machining. Further, a mold member 312 made of molybdenum was screwed to the mold member 311. The outer diameter of the aspherical surface of the first mold member was 23 mm, the inner diameter of the second mold member was 24 mm, and the gap between the mold member 311 and the mold member 312 was 0.5 mm for the purpose of allowing gas to pass. The lens molding surface of the second mold member was a 45 ° tapered surface.
[0232]
N2The mold was attached to a press shaft in a molding apparatus in an atmosphere, a glass material was placed between the upper and lower molds, and the mold and glass were heated to 625 ° C. Next, the upper die was lowered to start pressing. After the glass started to be deformed by the mold members 311, 313, N2 gas was flowed into the gas passage 314 and was released from the gap between the mold members 311 and 312 into the molding chamber. N2Before entering the passage 314, the gas temperature is heated to the mold temperature by a heater (not shown). The gas flow rate is controlled by a flow regulator (not shown).
[0233]
After the deformation was completed, the mold was cooled while maintaining the mold temperature and the glass temperature at the same temperature, and the mold was released from the mold by raising the upper mold when cooled to 200 ° C. The appearance of the molded product taken out is free from defects such as fusion, the concave side is in contact with the upper die 311 in the range of Φ22, and a 45 ° tapered surface is formed by the mold member 312 from Φ24.5 to Φ30. It was. Moreover, between Φ22 and Φ24.5 was a complete free surface. The molded product was centered to obtain an optical element 316. The obtained optical element had a deviation of 0.3 μm on the concave side (aspheric surface) with respect to the design value, and the convex side (spherical surface) had an accuracy of 0.5 Newton rings. The 45 ° taper surface of the outer peripheral portion had a deviation from the design value of around 3 μm, which was a sufficient value for mechanical accuracy.
[0234]
The above process was performed for 500 shots with different gas flow rates, and the results are summarized in FIG. All appearance quality was not fused, and good results were obtained with respect to shape accuracy. For comparison, molding was carried out without flowing gas, but the glass was fused to the second mold member 312 in 20 shots, making molding impossible.
(21st Embodiment)
FIG. 13 is a diagram of a mold structure for illustrating the molding method of the twenty-first embodiment. Reference numeral 317 is an upper mold, reference numeral 318 is a lower first mold member, reference numeral 319 is a lower second mold member, reference numeral 320 is a fixing ring, reference numeral 321 is a gas passage, and reference numeral 322 is a molded product. . FIG. 14 shows a molded optical element 323. The optical element 323 was not centered and could be incorporated into the barrel as it was molded.
[0235]
LaF010 (nd = 1.733310, νd = 49.4, Tg = 571 ° C., At = 600 ° C.) was used as a lens forming material, and thereby a sphere having a diameter of 10.6 mm was formed as a preform.
A biconvex lens in which R1 = 18.5 mm, R2 = 16.4 mm, center thickness = 5 mm, effective beam diameter = Φ12 mm, and outer diameters on both sides of R2 are defined as Φ13 mm from the above-described material.
[0236]
As a method for manufacturing the mold shown in FIG. 13, a gas passage 321 was formed in a mold member 318 made of a cemented carbide by electric discharge machining. After further spherical polishing, a carbon film was coated. Further, a mold member 319 made of porous carbon was fitted and inserted into the mold member 318. Further, a fixing ring 320 was inserted, and the mold members were fixed with fixing pins (not shown). The inner diameter of the second mold member 319 is Φ13, eliminating the need for centering the molded product.
[0237]
N2The mold was attached to a press shaft in a molding apparatus in an atmosphere, a glass material was put between the upper and lower molds, and the mold and glass were heated to 640 ° C. Next, the upper die was lowered to start pressing. After the glass started to be deformed by the mold members 317 and 318, N 2 gas was poured into the gas passage 321 and was released into the molding chamber through the gap between the mold members 317 and 319. N2The gas temperature is heated to the mold temperature by a heater (not shown) before entering the passage 321.
[0238]
After the deformation was completed, the mold was cooled while maintaining the mold temperature and the glass temperature at the same temperature, and the mold was released from the mold by raising the upper mold when cooled to 200 ° C. When the appearance of the molded product taken out was observed with a microscope, the portion corresponding to the first mold member had transferred the fine surface roughness of the mold, but the portion corresponding to the second mold member had a mold contact mark. It was found that the mold and the glass were formed in a non-contact state without any smoothness. The obtained optical element had an accuracy of 0.5 Newton's ring with respect to the design value on both sides within the effective beam diameter. Further, the outer diameter Φ13 on the R2 surface side is a level that can be used without centering, with a deviation from a predetermined value of around 2 μm.
[0239]
Although the above process was performed for 500 shots, there was no problem in quality, and it was possible to form continuously.
For comparison, the material of the second mold member 319 was made of a cemented carbide and was coated with a carbon film. However, when 50 shots were formed, the carbon film on the horizontal surface of the mold member 319 was peeled off. When molding was continued, fusion occurred from that part.
[0240]
(Twenty-second embodiment)
FIG. 15 is a diagram of a mold structure for illustrating the molding method of the twenty-second embodiment. Reference numeral 324 indicates an upper mold, reference numeral 325 indicates a lower mold, reference numeral 326 indicates a body mold, reference numeral 327 indicates a second mold member for forming an outer diameter, reference numeral 328 indicates a gas passage, and reference numeral 329 indicates a molded product.
FIG. 16 shows the resulting optical element 330.
[0241]
As in the twenty-second embodiment, SK12 was used as a lens molding material, and thereby a gob (glass lump) having a diameter of 12 mm and a center thickness of 6.3 mm was formed as a preform. A biconvex lens having R1 = 16.45 mm, R2 = 16.86 mm, center thickness 4.5 mm, effective beam diameter = Φ12 mm, and outer diameter = Φ14 mm is formed from the above material.
[0242]
As a method for manufacturing the mold shown in FIG. 15, mold members 324 and 325 made of cemented carbide were polished and then coated with a carbon film. Further, a second mold member 327 made of porous carbon was fitted into the body mold 326. The gap between the mold members 324 and 325 and the body mold 326 is 10 μm, and is an amount that prevents eccentricity of the mold members 324 and 325 while ensuring a gas escape path.
[0243]
N2The mold was attached to a press shaft in a molding apparatus in an atmosphere, a glass material was placed between the upper and lower molds, and the mold and glass were heated to 580 ° C. Next, the upper die was lowered to start pressing. N after the glass starts to deform by the mold members 324 and 3252The gas was poured into the mold member 327 and released into the molding chamber through the gap between the upper and lower molds and the body mold. N2Before entering the passage 328, the gas temperature is heated to the mold temperature by a heater (not shown). The gas flow rate is controlled by a flow regulator (not shown).
[0244]
After the deformation was completed, the mold was cooled while keeping the mold temperature and gas temperature equal, and when the mold was cooled to 200 ° C., the upper mold was raised to release the mold from the glass. When the appearance of the molded product taken out was observed with a microscope, the spherical part transferred the surface roughness of the fine mold, but the outer diameter part was smooth with no mold contact marks. It was found that it was molded in a non-contact state. The obtained optical element had an accuracy of 0.5 or less Newton rings with respect to the design value within the effective beam diameter. Moreover, the deviation from the design value was 5 μm, which was a sufficient value for mechanical accuracy.
[0245]
Although the above process was performed for 500 shots, there was no problem in quality, and continuous molding was possible.
For comparison, the material of the second mold member 327 was made of a cemented carbide and a carbon film-coated material was used. However, glass entered the gap between the second mold member 327 and the upper and lower molds 324 and 325. Can no longer be extracted from the body mold.
[0246]
From the above results, it was found that the glass can be prevented from entering the gap between the upper and lower molds and the trunk mold by flowing gas from the second mold member.
As described above, the mold used in the method of molding an optical element by pressing a weight-adjusted glass material with a molding mold is a first mold member for forming at least the effective beam diameter of the optical element. And a second mold member for forming other parts, and by molding while flowing gas on the molding surface through the inside or surface of the passage formed in the second mold member In particular, the mold and glass can be molded in a non-contact state at the lens periphery, where fusion and delamination are likely to occur, and as a result, continuous molding can be performed without problems such as fusion. It becomes like this.
[0247]
Further, by providing a gas temperature difference between the upper and lower molds, it is possible to stably leave the molded product on the lower mold when the mold is released, thereby preventing handling problems.
In addition, if a porous material is used as the outer diameter forming member, an optical element that does not require centering can be obtained without glass entering the gaps in the mold.
Summarizing the above eighteenth to twenty-second embodiments, it is noted that in the twenty-eighth method, fusion and mold delamination are likely to occur at the periphery of the optical element. In order to make the adhesion force zero, a method of forming in a non-contact state is proposed. However, in order to achieve optical accuracy in the light beam effective system, the mold and glass are in contact. Outside the beam effective diameter, the mechanical accuracy required for the combination with the lens barrel is required, but optical accuracy is not required. And the glass were non-contact. The optical accuracy mentioned here means a shape error of about 0.5 μm or less, and the mechanical accuracy means a shape error of about 10 μm.
[0248]
As a specific method, a mold used in a method of molding an optical element by pressing a glass material whose weight has been adjusted with a molding mold is a first method for forming at least an effective beam diameter of the optical element. The mold member and the second mold member are formed to form the other parts, and the above object is achieved by molding the gas while flowing the gas on the molding surface via the inside or the surface of the second mold member. Achieved. In addition, the second mold member and the molded optical element are in non-contact through the gas layer, so that the above object can be achieved more reliably.
[0249]
In order to form a gas layer on the surface of the second mold member, the mold shape may be devised to form a gap through which gas passes and a gas may be released to the mold surface. The second mold member is made of porous ceramic, porous metal, or porous carbon. By using such a porous material, gas is evenly discharged over the entire surface of the second mold member, so that it is easy to obtain mechanical accuracy in a non-contact state.
[0250]
Further, as an accompanying purpose, the difference between the temperature of the gas passing through the second mold member constituting the upper mold and the temperature of the gas passing through the second mold member constituting the lower mold is set to 10 ° C. or more. It is also possible to control which of the upper and lower surfaces is released first when molding. As a result, troubles can be prevented even in an apparatus structure in which the optical element after release is always left on the lower mold.
[0251]
The optical elements obtained in the above-described eighteenth to twenty-second embodiments have a portion that is in contact with the mold at least within the effective beam diameter and that has a portion formed by the mold in a non-contact state on the other surface. . Within the effective diameter of the light beam, it can be molded with optical accuracy (shape error of about 0.5 μm or less) by contact with the mold, and outside the effective diameter of the light beam is non-contact with the mold, but mechanical accuracy (shape error of 10 μm or less) Can be assembled to the lens barrel. Further, not all parts outside the effective beam diameter require mechanical accuracy, and there may be free surfaces that are not constrained by the mold.
(23rd embodiment)
In the twenty-third embodiment, a method of obtaining a glass lump suitable as an optical element forming material from a molten glass flow will be described.
[0252]
FIG. 17 is a diagram for explaining the structure of the receiving mold used in the production of the glass lump according to the twenty-third embodiment of the present invention.
In FIG. 17, 401 is a molten glass outflow pipe, 402 is a molten glass flow, 403 is a porous receiving mold, 404 is a receiving mold holding block holding a porous receiving mold 403, and 405 is a porous receiving mold. A gas supply chamber located on the back surface of 403 and surrounded by the mold holding block 404, 406 is a low temperature gas supply pipe for supplying a low temperature gas to the gas supply chamber 405, and 407 is a high temperature gas supplied to the gas supply chamber 405. A high-temperature gas supply pipe for supply, 408 is a platinum winding heater for gas heating provided in the high-temperature gas supply pipe 407, and 409 is provided in the middle of the low-temperature gas supply pipe 406 and the high-temperature gas supply pipe 407. This is a gas flow rate adjustment valve.
[0253]
FIG. 18 thru | or FIG. 21 is a figure explaining sequentially the manufacturing process of the molten glass lump which is 23rd Embodiment. The operation in the present embodiment will be described with reference to these drawings.
Glass melted inside a glass melting crucible (not shown) flows out through a molten glass outflow pipe 401 installed at the lower part of the glass melting crucible.
[0254]
In the initial stage of the process of receiving the molten glass flow in the receiving mold, the tip of the molten glass flow 402 is at a position above the porous receiving mold 403 as shown in FIG. At this time, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 and the high temperature gas supply pipe 407 is opened, and the low temperature gas is supplied from the low temperature gas supply pipe 406 and the high temperature gas is supplied from the high temperature gas supply pipe 407 to the gas supply chamber. 405 is supplied inside and mixed. Then, the mixed temperature gas is ejected to the receiving surface of the receiving mold 403 through the pores of the porous receiving mold 403.
[0255]
Further, when the molten glass stream 402 flows out and the tip of the molten glass stream 402 descends, the tip of the molten glass stream 402 approaches the receiving surface of the porous receiving mold 403 as shown in FIG. It will be in the state. However, at this time, since the mixed temperature gas is ejected from the receiving surface of the porous receiving mold 403, the tip of the molten glass flow 402 does not contact the porous receiving mold 403. . Also at this time, gas is supplied from both the low temperature gas supply pipe 406 and the high temperature gas supply pipe 407.
[0256]
As the molten glass stream 402 further flows out, the molten glass stream 402 begins to accumulate on the porous receiving mold 403 as shown in FIG. In this state, the gas flow rate adjustment valve 409 provided in the low temperature gas supply pipe 406 starts to close. Then, since the amount of the low temperature gas supplied to the gas supply chamber 405 starts to decrease, the temperature of the gas mixed in the gas supply chamber 405 begins to rise, and the gas ejected from the receiving surface of the porous receiving mold 403 The temperature starts to rise.
[0257]
Then, the gas flow rate adjusting valve 409 of the low temperature gas supply pipe 406 is closed, and after the weight of the molten glass accumulated on the receiving mold 403 reaches a desired value, the receiving mold 403 is lowered downward to confine the molten glass. And cut naturally to obtain a molten glass lump 410. This state is shown in FIG. At this time, the low temperature gas supply pipe 406 is closed, and high temperature gas is supplied from the high temperature gas supply pipe 407 to the gas supply chamber 405. The molten glass lump 410 is levitated by the high-temperature gas ejected from the receiving surface of the porous receiving mold 403.
[0258]
Since the glass lump 410 obtained in this manner is always in a state of floating from the receiving mold 403, its upper and lower surfaces are both free surfaces and are very smooth. Further, the glass lump 410 has no contact mark with the receiving mold 403. Furthermore, since the glass lump 410 is levitated with a gas having a temperature condition optimum for the glass lump manufacturing process, the lower surface of the glass lump is lifted by the jet gas and does not solidify in a depressed state. The lower surface of the obtained glass block 410 has a shape that substantially follows the shape of the receiving mold 403.
[0259]
That is, the glass lump 410 obtained in this way is excellent in appearance and shape, and is very suitable as an optical element molding material.
Next, a more specific example of this embodiment will be specifically described.
The optical glass melted in a platinum glass melting crucible (not shown) flows out in the form of droplets through a platinum molten glass outflow pipe 401 connected to the lower part of the melting crucible. The temperature of the flowing molten glass stream 402 is 1000 ° C.
[0260]
The receiving mold 403 is made of porous carbon, has a porosity of 30%, and has pores with an average pore diameter of 15 μm. The receiving surface of the porous receiving mold 403 is processed into a spherical surface having a radius of 15 mm. The lower and side surfaces of the receiving mold 403 are surrounded by a stainless steel receiving mold holding member 404. A space serving as the gas supply chamber 405 is provided between the lower surface of the receiving mold 403 and the receiving mold holding member 404.
[0261]
Two types of gas supply pipes, a low temperature gas supply pipe 406 and a high temperature gas supply pipe 407, are connected to the gas supply chamber 405 through a receiving mold holding member 404. The low temperature gas supply pipe 406 is made of a stainless steel pipe, and nitrogen gas at room temperature is supplied to the gas supply chamber 405 through the low temperature gas supply pipe 406. The hot gas supply pipe 407 is provided with a platinum winding heater 408 in a stainless steel pipe, and between the stainless steel pipe and the platinum winding heater 408, a quartz glass pipe (see FIG. Not shown) is installed. When nitrogen gas at room temperature is supplied into the high temperature gas supply pipe 407, the nitrogen gas is heated by the heated platinum winding heater 408 while passing through the high temperature gas supply pipe 407. The gas is supplied into the gas supply chamber 405.
[0262]
In the present embodiment, one low temperature gas supply pipe 406 is installed at the center of the gas supply chamber 405, and six high temperature gas supply pipes 407 are installed on the circumference around the low temperature gas supply pipe 406. Yes.
The gas flow rate adjusting valve 409 is provided in all of the low temperature gas supply pipe 406 and the six high temperature gas supply pipes 407. The gas flow rate adjusting valve 409 can continuously control the gas flow rate from a preset value to a flow rate of zero. In this embodiment, the low temperature gas supply pipe 406 can flow nitrogen gas at a maximum flow rate of 5 liters / minute, and the high temperature gas supply pipe 407 has a maximum flow rate of 1 liter / minute for each one. The gas flow rate adjustment valve 409 is set so that high-temperature nitrogen gas having a temperature of 500 ° C. can flow.
[0263]
The receiving mold holding member 404, the low temperature gas supply pipe 406, and the high temperature gas supply pipe 407, which are integrated with the receiving mold 403, are connected to a vertical drive device (not shown) that can be vertically controlled. It can be moved up and down.
Next, a specific state of the process of obtaining the glass block 410 using this apparatus will be described with reference to FIGS.
[0264]
FIG. 18 shows a state immediately before the molten glass stream 402 is received by the receiving mold 403. At this time, the receiving mold 403 is raised to a position 10 mm below the outlet of the molten glass outflow pipe 401 and stopped. At this time, the gas flow rate adjustment valves 409 of the low temperature gas supply pipe 406 and the six high temperature gas supply pipes 407 are all fully opened. Therefore, nitrogen gas at room temperature at a flow rate of 5 liters / minute from the low temperature gas supply pipe 406 and nitrogen gas at 500 ° C. at a flow rate of 6 liters / minute in total from the six high temperature gas supply pipes 407 Being supplied inside. The low-temperature gas and the high-temperature gas are mixed in the gas supply chamber 405, and this gas is ejected to the receiving surface through the pores of the porous receiving mold 403. At this time, the temperature of the gas ejected from the receiving surface was 300 ° C. In the present embodiment, a heater for heating is not installed in the receiving mold holding member 404.
[0265]
FIG. 19 shows a state when the molten glass stream 402 further flows out. At this time, the tip of the molten glass 402 is close to the receiving surface of the porous receiving mold 403, but since gas is ejected from the receiving surface, the tip of the molten glass flow 402 and the porous receiving portion are There is no contact with the receiving surface of the mold 403. At this time, the gas flow rate adjustment valves 409 of the low temperature gas supply pipe 406 and the six high temperature gas supply pipes 407 are all fully opened. FIG. 19 shows a state after 1 second from the start of gob reception, that is, the state of FIG.
[0266]
FIG. 20 shows a state where the molten glass stream 402 further flows out and the molten glass is accumulated on the receiving mold 403. At this time, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 407 is continuously closed. The gas flow valve 409 started to be closed 2 seconds after the start of the gob reception, and thereafter, the gas flow valve 409 was gradually and gradually closed over 3 seconds. Further, 7 seconds after the start of the gob receiving, the weight of the molten glass accumulated on the receiving mold 403 has reached a desired value, so the receiving mold 403 is lowered 5 mm downward and held for 1 second in that state. The molten glass stream was constricted and further spontaneously cut to obtain a molten glass lump 410.
[0267]
At this time, the gas supply chamber 405 is supplied with a high-temperature gas from a high-temperature gas supply pipe, and this high-temperature gas is ejected from the receiving mold 403, and the glass lump 410 is floated and held by this gas. This state is shown in FIG. At this time, the temperature of the gas ejected from the receiving surface of the receiving mold 403 was 400 ° C. The glass lump 410 obtained in this way has a weight of 2.5 g and has a depression or the like on its lower surface. The upper and lower surfaces are smooth free surfaces, and there are no contact marks with the receiving mold 403, so that it is very suitable as an optical element molding material.
[0268]
As an effect peculiar to the present embodiment, the optimum molding conditions for obtaining a glass lump that is excellent in appearance and shape and very suitable as an optical element molding material from a molten glass stream are gas temperature, gas flow rate, low temperature There exists a point which can be easily calculated | required from the combination of a gas flow stop timing. Accordingly, even when the desired size and shape of the glass lump and the type of glass are different, the optimum molding conditions can be easily and quickly obtained.
[0269]
(24th Embodiment)
In the twenty-fourth embodiment, a method for obtaining a glass lump suitable as an optical element molding material from a molten glass flow will be described.
FIG. 22 is a view for explaining the structure of the receiving mold used in the production of the glass lump according to the twenty-fourth embodiment of the present invention.
[0270]
In FIG. 22, 401 is a molten glass outlet pipe, 402 is a molten glass stream, 403 is a porous receiving mold, 404 is a receiving mold holding block holding a porous receiving mold 403, and 406 is supplied with a low-temperature gas. 407 is a high-temperature gas supply pipe for supplying high-temperature gas, 408 is a platinum winding heater for gas heating provided inside the high-temperature gas supply pipe 407, and 409 is low-temperature gas supply This is a gas flow rate adjustment valve provided in the middle of the pipe 406 and the hot gas supply pipe 407. Reference numeral 411 denotes a partition wall which is located on the back surface of the porous receiving mold 403 and is divided into two spaces of a central portion and an outer peripheral portion and surrounded by the mold holding block 404, and 412 is a partition wall 411. 413 is a central gas supply chamber divided by, and 413 is an outer peripheral gas supply chamber divided by a partition wall 411. A low temperature gas supply pipe 406 and a high temperature gas supply pipe 407 are connected to the center gas supply chamber 412. A high temperature gas supply pipe 407 is connected to the outer peripheral gas supply chamber 413.
[0271]
FIG. 23 to FIG. 26 are diagrams for sequentially explaining the molten glass lump manufacturing process according to the twenty-fourth embodiment. The operation in the present embodiment will be described with reference to these drawings.
Glass melted inside a glass melting crucible (not shown) flows out through a molten glass outflow pipe 1 installed at the lower part of the glass melting crucible.
[0272]
In the initial stage of the process of receiving the molten glass flow in the receiving mold, the tip of the molten glass flow 402 is located above the porous receiving mold 403 as shown in FIG. At this time, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 connected to the central gas supply chamber 412 is opened, and the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 is closed. The gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 connected to the outer peripheral gas supply chamber 413 is also opened. Accordingly, a low temperature gas is supplied to the central gas supply chamber 412 and a high temperature gas is supplied to the outer peripheral gas supply chamber 413, and these gases pass through the pores of the porous receiving mold 403, It is ejected to the receiving surface of the receiving mold 403. As a result, low temperature gas is ejected from the central portion of the receiving surface of the receiving mold 403, and high temperature gas is ejected from the outer peripheral portion.
[0273]
Further, when the molten glass stream 402 flows out and the tip of the molten glass stream 402 descends, the tip of the molten glass stream 402 approaches the receiving surface of the porous receiving mold 403 as shown in FIG. It will be in the state. However, at this time, since the gas is ejected from the receiving surface of the porous receiving mold 403, the tip of the molten glass flow 402 does not come into contact with the porous receiving mold 403. At this time, the low temperature gas supply pipe 406 and the gas flow rate adjustment valve 409 connected to the central gas supply chamber 412 start to close, and conversely, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 starts to open.
[0274]
As the molten glass stream 402 further flows out, the molten glass stream 402 begins to accumulate on the porous receiving mold 403 as shown in FIG. In this state, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 connected to the central gas supply chamber 412 is closed, and conversely, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 is opened. As a result, the temperature of the gas supplied to the central gas supply chamber 412 increases, so that the temperature of the gas ejected from the central portion of the receiving surface of the porous receiving mold 403 increases.
[0275]
Then, after the weight of the molten glass accumulated on the receiving mold 403 reaches a desired value, the receiving mold 403 is lowered downward, the molten glass is constricted, and naturally cut to obtain a molten glass lump 410. This state is shown in FIG. At this time, the molten glass lump 410 is floated by the high-temperature gas ejected from the receiving surface of the porous receiving mold 403.
[0276]
Since the glass lump 410 obtained in this manner is always in a state of floating from the receiving mold 403, its upper and lower surfaces are both free surfaces and are very smooth. Further, the glass lump 410 has no contact mark with the receiving mold 403. Furthermore, since the glass lump 410 is levitated with a gas having a temperature condition optimum for the glass lump manufacturing process, the lower surface of the glass lump is lifted by the jet gas and does not solidify in a depressed state. The lower surface of the obtained glass block 410 has a shape that substantially follows the shape of the receiving mold 403.
[0277]
That is, the glass lump 410 obtained in this way is excellent in appearance and shape, and is very suitable as an optical element molding material.
Next, a more specific embodiment of this embodiment will be specifically described.
The optical glass melted in a platinum glass melting crucible (not shown) flows out in the form of droplets through a platinum molten glass outflow pipe 401 connected to the lower part of the melting crucible. The temperature of the flowing molten glass stream 402 is 1000 ° C.
[0278]
The receiving mold 403 is made of porous carbon, has a porosity of 30%, and has pores with an average pore diameter of 15 μm. The receiving surface of the porous receiving mold 403 is processed into a spherical surface having a radius of 15 mm. The lower and side surfaces of the receiving mold 403 are surrounded by a stainless steel receiving mold holding member 404. A space serving as the gas supply chamber 405 is provided between the lower surface of the receiving mold 403 and the receiving mold holding member 404.
[0279]
The gas supply chamber is divided into a central gas supply chamber 412 and an outer peripheral gas supply chamber 413 by a stainless steel cylindrical partition wall 411 provided therein.
Two types of gas supply pipes, a low temperature gas supply pipe 406 and a high temperature gas supply pipe 407, are connected to the center gas supply chamber 412. A high temperature gas supply pipe 407 is connected to the outer peripheral gas supply chamber 413. The low temperature gas supply pipe 406 is made of a stainless steel pipe, and nitrogen gas at room temperature is supplied to the gas supply chamber through the low temperature gas supply pipe 406. The high-temperature gas supply pipe 407 is provided with a platinum winding heater 408 in a stainless steel pipe, and a quartz glass pipe (see FIG. 5) is provided between the stainless steel pipe and the platinum winding heater 408 for insulation. Not shown) is installed. When nitrogen gas at room temperature is supplied into the high temperature gas supply pipe 407, the nitrogen gas is heated by the heated platinum winding heater 408 while passing through the high temperature gas supply pipe 407. It is supplied into the gas supply chamber.
[0280]
In this embodiment, the center gas supply chamber 412 is connected to one low temperature gas supply pipe 406 and one high temperature gas supply pipe 407. In the peripheral gas supply chamber 413, six high-temperature gas supply pipes 407 are installed on the circumference.
The gas flow rate adjusting valve 409 is provided in all of the low temperature gas supply pipe 406 and the six high temperature gas supply pipes 407. The gas flow rate adjusting valve 409 can continuously control the gas flow rate from a preset value to a flow rate of 0. In this embodiment, the low temperature gas supply pipe 406 can flow nitrogen gas at a maximum flow rate of 5 liters / minute, and the high temperature gas supply pipe 407 has a maximum flow rate of 1 liter / minute for each one. The gas flow rate adjustment valve 409 is set so that high-temperature nitrogen gas having a temperature of 500 ° C. can flow.
[0281]
The receiving mold holding member 404, the low temperature gas supply pipe 406, and the high temperature gas supply pipe 407, which are integrated with the receiving mold 403, are connected to a vertical drive device (not shown) that can be vertically controlled. It can be moved up and down.
Next, the specific state of the process of obtaining the molten glass lump 410 using this apparatus will be described with reference to FIGS.
[0282]
FIG. 23 shows a state immediately before the molten glass stream 402 is received by the receiving mold 403. At this time, the receiving mold 403 is raised to a position 10 mm below the outlet of the molten glass outflow pipe 401 and stopped. At this time, the low temperature gas supply pipe 406 connected to the central gas supply chamber 412 and the high temperature gas supply pipe 406 connected to the outer peripheral gas supply chamber 413 are all fully opened. Therefore, room-temperature nitrogen gas at a flow rate of 5 liters / minute from the low temperature gas supply pipe 406 to the central gas supply chamber 412 and a total of 6 liters / minute from the six hot gas supply pipes 407 to the peripheral gas supply chamber 413 A nitrogen gas having a flow rate of 500 ° C. is supplied. This gas is ejected to the receiving surface through the pores of the porous receiving mold 403. At this time, the temperature of the gas ejected from the receiving surface was 150 ° C. at the center and 400 ° C. at the outer periphery. In the present embodiment, a heater for heating is not installed in the receiving mold holding member 404.
[0283]
FIG. 24 shows the state when the molten glass stream 402 further flows out. At this time, the tip of the molten glass 402 is close to the receiving surface of the porous receiving mold 403, but since gas is ejected from the receiving surface, the tip of the molten glass flow 402 and the porous receiving portion are There is no contact with the receiving surface of the mold 403. At this time, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 connected to the central gas supply chamber 412 starts to close, and conversely, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 starts to open. Yes. The opening adjustment of these gas flow rate adjustment valves 409 is performed from the start of gob reception, that is, 1 second after the state of FIG. 23, and after that, over 3 seconds, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 is turned on. In addition to closing, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 was fully opened. During this time, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 supplied to the outer peripheral gas supply chamber 413 remains fully open. FIG. 24 shows a state 1.5 seconds after the start of gob reception.
[0284]
FIG. 25 shows a state in which the molten glass stream 402 further flows out and the molten glass is accumulated on the receiving mold 403. At this time, the central gas supply chamber 412 is supplied with 500 ° C. nitrogen gas at a flow rate of 1 liter / min, and the outer peripheral gas supply chamber 413 is supplied with 500 ° C. nitrogen gas at a flow rate of 6 liters / min. Yes. 8 seconds after the start of gob receiving, the weight of the molten glass accumulated on the receiving mold 3 has reached a desired value. Therefore, the receiving mold 403 is lowered 5 mm downward and melted while being held for 1 second in that state. The glass flow was constricted and further spontaneously cut to obtain a molten glass lump 410.
[0285]
At this time, a high-temperature gas is supplied from the high-temperature gas pipe 407 to the gas supply chamber, and this high-temperature gas is ejected from the receiving mold 403, and the glass lump 410 is floated and held by this gas. This state is shown in FIG. At this time, the temperature of the gas ejected from the receiving surface of the receiving mold 403 was 400 ° C. The glass lump 410 thus obtained has a weight of 2.7 g and has a dent or the like on its lower surface. The upper and lower surfaces are smooth free surfaces, and there is no contact mark with the receiving mold 403, so that it is very suitable as an optical element molding material.
[0286]
As an effect peculiar to this embodiment, the optimum molding conditions for obtaining a glass lump that is excellent in appearance and shape and is very suitable as a material for molding an optical element from a molten glass flow, the central gas supply chamber and the outer periphery The gas supplied to the partial gas supply chamber can be obtained more easily from the combination of the gas temperature, the gas flow rate, and the low temperature gas flow stop timing as compared with the twenty-seventh embodiment. Therefore, even when the desired size and shape of the glass lump and the type of glass are different, the optimum molding conditions can be determined more easily and quickly than in the twenty-seventh embodiment.
[0287]
(25th Embodiment)
In the twenty-fifth embodiment, a method will be described in which a molded glass lump suitable as an optical element molding material is obtained by press molding.
FIG. 27 is a diagram illustrating the configuration of a molding die used in the production of a shaped glass lump according to the twenty-fifth embodiment.
[0288]
In FIG. 27, reference numeral 406 denotes a low temperature gas supply pipe for supplying a low temperature gas, 407 denotes a high temperature gas supply pipe for supplying a high temperature gas, and 408 denotes a gas heating pipe provided inside the high temperature gas supply pipe 407. The platinum wire heater 409 is a gas flow rate adjusting valve provided in the middle of the low temperature gas supply pipe 406 and the high temperature gas supply pipe 407. 414 is a porous mold, 415 is a mold holding block that holds the porous mold 414, and 405 is located on the back of the porous mold 414 and is surrounded by the mold holding block. Supply room. The low temperature gas supply pipe 406 and the high temperature gas supply pipe 407 are connected to the gas supply chamber 405. Reference numeral 416 denotes a lower mold for molding, and reference numeral 417 denotes a glass lump prepared in advance.
[0289]
FIG. 28 to FIG. 32 are diagrams for sequentially explaining the manufacturing steps of the molded glass block according to the twenty-fifth embodiment. The operation in the present embodiment will be described with reference to these drawings.
The glass block 417 is manufactured and prepared in advance by the method described in the embodiments 27 and 28. Therefore, in the initial stage of the glass lump manufacturing process according to the present embodiment, the glass lump 417 is in a relatively low temperature state.
[0290]
In the initial stage of the step of forming the glass lump, as shown in FIG. 27, the glass lump 417 prepared in advance is placed on the lower mold 416 for molding. At this time, the lower mold 416 is heated to a desired temperature. At this time, the porous mold 414 is located above the glass block 417. At this time, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 is closed, while the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 is open. Then, a high-temperature gas is supplied into the gas supply chamber 405, and this high-temperature gas is ejected to the molding surface of the molding die 414 through the pores of the porous molding die 414.
[0291]
Subsequently, the mold 414 in a state where the high-temperature gas is ejected from the molding surface is lowered to a position close to the upper surface of the glass lump 417 as shown in FIG. In this state, the glass block 417 is heated to a temperature at which it can be thermally deformed by the high-temperature gas ejected from the molding surface.
Thereafter, the mold 414 is lowered at a slow speed. During this time, since the high-temperature gas is ejected from the molding surface, the molding surface of the molding die 414 and the upper surface of the glass block 417 do not come into contact with each other. FIG. 29 shows the situation at this time.
[0292]
Further, as the molding die 414 descends, the molding die holding block 415 and the lower die 416 come into contact with each other as shown in FIG. 30, and the press deformation of the glass block 417 is completed. In addition, since the high temperature gas is injected from the molding surface during the process of press-molding the glass lump 417, the molding die 414 and the glass lump 417 do not come into contact with each other.
After the press deformation of the glass block 417 is completed, as shown in FIG. 31, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 starts to close, and conversely, the gas flow rate adjustment of the low temperature gas supply pipe 406 starts. I started to open the valve.
[0293]
Further, as shown in FIG. 32, the gas flow rate adjustment valve of the high temperature gas supply pipe 407 is closed, the low temperature gas is supplied from the low temperature gas supply pipe 406 to the gas supply chamber, and the low temperature gas is ejected from the molding surface. Then, the press-molded molded glass lump 418 was cooled.
And after cooling the shaping | molding glass lump 418 to the temperature which can be taken out, the shaping | molding glass lump 418 was taken out.
[0294]
Since the molded glass 418 thus obtained is reheated prior to its molding with a high-temperature gas injected from the porous mold, it can reach a moldable temperature in a fast time. In particular, when the temperature of the glass lump 417 prepared in advance is sufficiently high, the time for reheating prior to molding is almost unnecessary, and high temperature gas is ejected from the molding surface of the porous mold 414. Thus, the glass lump 417 can be immediately press-molded. Further, according to this embodiment, when the glass block 417 is heated by the high-temperature gas sprayed from the mold, the lower surface of the glass block 417 is not excessively heated. 416 is not fused. Further, the upper surface of the molded glass lump 418 thus obtained is very smooth because it is always kept in a non-contact state by the gas ejected from the mold 414 during press molding.
[0295]
The molded glass lump 418 thus obtained has a smooth free surface on its upper surface, and its lower surface is not fused, is excellent in appearance accuracy and has a desired shape. .
Since the molded glass lump 418 thus obtained has a shape that approximates a desired molded optical element, when this molded glass lump 418 is used as an optical element molding material, the molding time is shortened. There are advantages such as the fact that the thin film having a releasing action attached to the mold during molding is not peeled off.
[0296]
Next, a more specific embodiment of this embodiment will be specifically described.
The mold 414 is made of porous carbon silicon (SiC), and has a porosity of 20% and an average pore diameter of 5 μm. The molding surface of the porous mold 414 is processed into a spherical surface having a radius of 10 mm. The upper and side surfaces of the mold 414 are surrounded by a stainless steel mold holding member 415. A space serving as a gas supply chamber 405 is provided between the upper surface of the mold 414 and the mold holding member 415. A heating cartridge heater (not shown) is installed in the mold holding member 415.
[0297]
Two types of gas supply pipes, a low temperature gas supply pipe 406 and a high temperature gas supply pipe 407, are connected to the gas supply chamber 405 through a mold holding member 415. The low temperature gas supply pipe 406 is made of a stainless steel pipe, and nitrogen gas at room temperature is supplied to the gas supply chamber 405 through the low temperature gas supply pipe 406. The hot gas supply pipe 407 is provided with a platinum winding heater 408 in a stainless steel pipe, and between the stainless steel pipe and the platinum winding heater 408, a quartz glass pipe (see FIG. Not shown) is installed. When nitrogen gas at room temperature is supplied into the high temperature gas supply pipe 407, the nitrogen gas is heated by the heated platinum winding heater 408 while passing through the high temperature gas supply pipe 407. The gas is supplied into the gas supply chamber 405.
[0298]
In the present embodiment, four low temperature gas supply pipes 406 are installed on the circumference in the gas supply chamber 405, and four high temperature gas supply pipes 407 are arranged on the circumference alternately with the low temperature gas supply pipe 406. is set up.
The gas flow rate adjusting valve 409 is provided in all of the low temperature gas supply pipe 406 and the high temperature gas supply pipe 407. The gas flow rate adjusting valve 409 can continuously control the gas flow rate from a preset value to a flow rate of zero. In the present embodiment, each of the low temperature gas supply pipes 406 can flow nitrogen gas at a maximum flow rate of 5 liters / minute, and the high temperature gas supply pipe 407 can flow up to 5 liters per line. The gas flow rate adjusting valve 409 is set so that high-temperature nitrogen gas having a flow rate of 900 ° C./min can flow.
[0299]
The mold holding member 415 integrated with the mold 414, the low temperature gas supply pipe 406, and the high temperature gas supply pipe 407 are connected to a vertical drive device (not shown) capable of vertical position control. It can be moved up and down.
The lower mold 416 is made of a carbon material, and the molding surface is processed into a spherical surface having a radius of 30 mm. A heating cartridge heater (not shown) is installed inside the lower mold 416.
[0300]
Next, a specific state of the process of obtaining the molded glass lump 418 using this apparatus will be described with reference to FIGS.
FIG. 27 shows the initial state of the molding process. At this time, the glass lump 217 was at a temperature of 300 ° C. because the glass lump obtained from the molten glass flow from another apparatus (not shown) was immediately conveyed into the lower mold 216. The lower mold 416 is constantly heated to 400 ° C. by a built-in cartridge heater (not shown). On the other hand, the mold holding block 415 is constantly heated to 600 ° C. by a built-in cartridge heater (not shown). From the four high-temperature gas supply pipes 407, high-temperature nitrogen gas at 900 ° C. with a flow rate of 20 liters / minute is supplied into the gas supply chamber 405. The high-temperature gas is ejected from the molding surface through the pores of the porous molding die 414. The temperature of the gas ejected from the molding surface was 700 ° C.
[0301]
After placing the glass block 417 on the lower mold 416, the mold 414 in a state where high-temperature gas is ejected is lowered and held at a position close to the upper surface of the glass block 417 as shown in FIG. . When kept in this state for 20 seconds, the glass block 417 was heated to a temperature at which it could be thermally deformed. In addition, the temperature of the glass lump 417 at this time was 700 degreeC on the upper surface, 600 degreeC of center parts, and 550 degreeC on the lower surface.
[0302]
Immediately thereafter, the mold 414 began to be lowered. The descending speed was 0.2 mm / second. At this time, since the high-temperature gas is ejected from the molding surface of the mold 414, the mold 414 and the glass block 417 do not come into contact with each other. Thus, the state in the middle of press-molding the glass lump 417 is shown in FIG.
25 seconds after starting to lower the mold 414, as shown in FIG. 30, the mold holding block 415 and the lower mold 416 hit each other, and the press molding of the glass block 417 was completed.
[0303]
Immediately thereafter, the gas flow rate adjustment valve 409 of the high temperature gas supply pipe 407 began to close, and at the same time, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 began to open. FIG. 31 shows this state. After 1 second, the gas flow rate adjustment valve 409 of the hot gas supply pipe 407 was completely closed. Further, the gas flow rate adjustment valve 409 of the low temperature gas supply pipe 406 was fully opened over 10 seconds. FIG. 32 shows this state. During this time, the temperature of the gas ejected from the molding surface of the molding die 414 is lowered, so that the molded glass lump 418 is cooled. Further, when cooled for 5 seconds, the molded glass lump 418 reached a temperature at which it could be taken out, so the mold 414 was raised and the molded glass lump 418 was taken out.
[0304]
The molded glass lump 418 thus obtained has a free surface on its upper surface, no contact marks with the mold 414, and its lower surface has no fusion with the lower mold 416 and is smooth. Yes, it is very suitable as an optical element molding material for molding a concave meniscus lens.
As an effect peculiar to the present embodiment, a pre-prepared glass lump is heated to a molded glass lump having excellent appearance accuracy and having a shape close to a desired optical element shape, which is very suitable as an optical element molding material. Therefore, by controlling the temperature of the gas ejected from the molding die, efficient heating and cooling can be performed, so that the time required for heating and cooling becomes very short and the molding time can be greatly shortened.
[0305]
As described above, according to the above-described embodiment, by controlling the temperature of the gas ejected from the receiving mold, it is possible to easily form a glass lump having no dent on the lower surface, which is suitable as an optical element molding material. And it can manufacture reliably.
In addition, by controlling the temperature of the gas ejected from the molding die, the time required for heating and cooling can be shortened in a method for press-molding a glass lump to obtain a shaped glass lump having a desired shape.
[0306]
In addition, by controlling the temperature of the gas ejected from the receiving mold more accurately and quickly, it is possible to more easily and reliably manufacture a glass lump suitable for an optical element molding material without a dent on the lower surface. it can.
In addition, by controlling the temperature of the gas ejected from the mold more accurately and quickly, the time required for heating and cooling is shortened in the method of press-molding the glass lump to obtain a shaped glass lump having a desired shape. be able to.
[0307]
Summarizing the above twenty-third to twenty-fifth embodiments, in the twenty-ninth method, in the molten glass lump production process, a gas having an optimum temperature is obtained from the receiving surface of the porous receiving mold for each time. In order to eject the gas, a gas having a different desired temperature is supplied to the back surface of the porous receiving mold, and the gas having the desired temperature is ejected from the receiving surface of the porous receiving mold.
[0308]
In order to control the temperature of the gas ejected from the receiving surface of the porous receiving mold to a desired temperature over time, the temperature of the gas supplied to the back surface of the receiving mold is controlled to the temperature of consumption over time. This is desirable because the controllability is good and the temperature of the gas ejected from the receiving mold can be controlled to a desired temperature in a short time. At this time, since the temperature of the gas is lowered while passing through the pores of the receiving mold, the temperature of the gas supplied to the back surface of the receiving mold is higher than the desired temperature of the gas ejected from the receiving surface of the receiving mold. It is preferable to do.
[0309]
As another method for controlling the temperature of the gas ejected from the porous receiving mold, the temperature of the gas supplied to the back surface of the receiving mold is always kept constant, and a heater is built in the mold holder that holds the receiving mold. There is also a method of controlling the temperature of the mold holder by a heater, thereby controlling the temperature of the porous receiving mold, and controlling the temperature of the jet gas passing through the pores of the porous receiving mold. However, in this method, since the heat conductivity of the porous receiving mold is small, the temperature followability is poor, and the controllability is extremely poor compared to the present embodiment.
[0310]
In this way, when the temperature of the gas ejected from the receiving surface of the porous receiving mold is controlled to a desired temperature over time, there is no dent on the lower surface of the glass block received on the receiving mold. It has an excellent external shape as an optical element molding material.
In addition, as a time-dependent control of the temperature of the gas ejected from the receiving surface of the porous receiving mold, the temperature of the gas is lowered in the initial stage of receiving the molten glass flow and receiving the mold, and then the temperature of the gas It is desirable to increase the value. By controlling the gas temperature in this way, it is possible to easily and reliably obtain a glass lump having no depression on the lower surface without contact between the molten glass and the receiving mold.
[0311]
This is because by lowering the temperature of the gas at the initial stage, the molten glass and the receiving mold are prevented from coming into contact with each other, and thereafter, the cooling rate of the glass block is lowered by increasing the temperature of the gas. Therefore, it is possible to prevent the glass lump from solidifying in a state where the bottom surface is recessed, and the bottom surface of the glass lump is deformed downward by its own weight, and is solidified after becoming a shape almost following the shape of the surface of the receiving mold. Because you can.
[0312]
Further, in the thirtieth method, in the glass lump production process, the gas at the optimum temperature desired every time is ejected from the molding surface of the porous molding die. A gas having a different desired temperature is supplied, and the gas having the desired temperature is ejected from the molding surface of the porous mold.
In order to control the temperature of the gas ejected from the molding surface of the porous mold to the desired temperature over time, the temperature of the gas supplied to the back surface of the mold is controlled to the desired temperature over time. This is desirable because the controllability is good and the temperature of the gas ejected from the mold can be controlled to a desired temperature in a short time. At this time, since the temperature of the gas decreases while passing through the pores of the mold, the temperature of the gas supplied to the back surface of the mold is higher than the desired temperature of the gas ejected from the molding surface of the mold. It is desirable to do.
[0313]
Thus, when the temperature of the gas ejected from the molding surface of the porous mold is controlled to a desired temperature over time, the glass is formed prior to press molding the glass lump with the porous mold. The process of reheating the mass can be greatly shortened or reduced. As the time-dependent control of the temperature of the gas ejected from the molding surface of the porous mold, the temperature of the gas is increased at the initial stage where the glass lump starts to be pressed, and then the temperature of the gas is decreased. It is desirable to do. By controlling the gas temperature in this way, the step of reheating the glass block can be greatly shortened or reduced.
[0314]
This is because, at the initial stage where the glass lump starts to be pressed, the temperature of the upper part of the glass lump is raised to a temperature at which the glass lump can be thermally deformed in a short time by increasing the temperature of the gas ejected from the porous mold. Can do. At this time, if the temperature of the glass lump is sufficiently high in advance, the step of reheating the glass lump prior to this step becomes unnecessary. Even if this is not the case, if the reheating is performed for a short time, the upper part of the glass lump can be raised to a temperature at which the glass lump can be thermally deformed in a short time by the high-temperature gas ejected from the porous mold thereafter. Because.
[0315]
Moreover, when the upper part of the glass lump is heated to a temperature at which the glass lump can be thermally deformed by the high-temperature gas ejected from the porous mold, the opposite side portion of the glass lump is not excessively heated by this gas. . Therefore, the glass lump is not fused with the lower mold on the opposite side by this heating. Therefore, when the glass lump is heated by the high-temperature gas ejected from the porous mold, the glass lump is not fused even when rapidly heated, so that the time required for heating can be shortened.
[0316]
In the thirty-first method, since a gas having an optimum temperature desired for each time is ejected from the receiving surface of the porous receiving mold, different temperatures are desired on the back surface of the porous receiving mold. A gas is supplied, and the gas at the desired temperature is ejected from the receiving surface of the porous receiving mold.
At this time, in order to supply a gas having a different temperature desired for the molten glass lump production process to the back surface of the porous receiving mold, gases having different temperatures installed on the back surface of the receiving mold are used. By selecting an appropriate gas supply pipe from among a plurality of gas supply pipes that can be supplied and supplying a gas having a desired temperature to the back surface of the porous receiving mold, the gas having the desired temperature is delayed for a desired time. You can get without.
[0317]
The reason is that an appropriate gas supply pipe is selected from a plurality of gas supply pipes that can supply gases having different temperatures, and a gas having a desired temperature is instantaneously obtained by mixing gases having different temperatures. be able to.
For example, when raising the gas temperature, the following is performed. First, gas is supplied from a plurality of gas supply pipes including two temperatures, low temperature and high temperature, mixed, and low temperature gas is supplied to the back surface of the porous receiving mold. Next, the low temperature gas supply from the low temperature gas supply pipe is stopped. Then, the temperature of the gas supplied to the back surface of the porous receiving mold immediately rises. Conversely, when lowering the gas temperature, first, the high-temperature gas is supplied to the back surface of the porous receiving mold in a state where the gas is not supplied from the low-temperature gas supply pipe. Next, a low temperature gas is supplied from a low temperature gas supply pipe. Then, the temperature of the mixed gas supplied to the back surface of the porous receiving mold is immediately lowered.
[0318]
In this way, by selecting an appropriate gas supply pipe from a plurality of gas supply pipes installed on the back surface of the porous receiving mold, and supplying a gas at a desired temperature to the back surface of the porous receiving mold. A gas having a desired temperature can be obtained without delaying to a desired time.
Note that the selection switching of the gas supply pipe at this time may be instantaneously performed intermittently or continuously, and the latter enables more accurate gas temperature control. In addition, the number of gas supply pipes to be selectively switched is not limited to one, and a plurality of gas supply pipes may be used. In this case, the timing for switching the gas supply pipes may be different for each gas supply pipe.
[0319]
As a means for changing the temperature of the gas supplied to the back surface of the porous receiving mold, a heater for heating is provided inside the only gas supply pipe installed on the back surface of the receiving mold, and the output of this heater is adjusted. Thus, means for changing the temperature of the supply gas are conventionally known. However, this method cannot instantaneously control the gas temperature to a desired temperature. This is because, in this method, it takes time to set the temperature of the heater to a desired temperature and further to set the temperature of the gas to the desired temperature by heat transfer from the heater.
[0320]
On the other hand, in this method, the gas temperature can be instantaneously set to a desired temperature. Therefore, since it is possible to optimally control the temperature of the blown gas in the process of manufacturing the molten glass lump, the bottom surface of the obtained glass lump has no dent and has an excellent external shape as an optical element molding material. ing.
Further, in the thirty-second method, in order to inject the gas at the optimum temperature desired every time from the molding surface of the porous molding die, different desired temperatures are formed on the back surface of the porous molding die. A gas is supplied, and the gas at the desired temperature is ejected from the molding surface of the porous mold.
[0321]
At this time, in order to supply the gas of different temperature desired for the time of the molding glass lump production process to the back of the porous mold, the gas of different temperature installed on the back of the mold is used. By selecting an appropriate gas supply pipe from among a plurality of gas supply pipes that can be supplied and supplying a gas having a desired temperature to the back surface of the porous mold, the gas having the desired temperature is delayed for a desired time. You can get without.
[0322]
Thus, in this method, the gas temperature can be instantaneously set to a desired temperature. Therefore, in the process of producing a molded glass lump, since it becomes possible to optimally control the temperature of the ejection gas, the step of reheating the glass lump prior to press molding the glass lump with a porous mold, It can be greatly shortened or reduced.
(26th Embodiment)
FIG. 33 is a schematic view showing a method for producing an optical element-forming glass material according to the twenty-sixth embodiment.
[0323]
In FIG. 33A, reference numeral 501 denotes a glass material whose composition is shown in FIG. 34, which is cut into a rectangular parallelepiped so as to have a required volume. Reference numeral 502 denotes a porous carbon material for forming the upper surface of the glass material, and a surface 502a through which high-temperature gas is blown is processed into R50. Reference numerals 503 and 504 are porous carbon materials for forming the lower surface of the glass material. Surfaces 503a and 504a for blowing out a high-temperature gas (which needs to be in a non-oxidized state in the subsequent molding and N2 is used in this embodiment). Is processed into R28. Here, the reason why the porous carbon material forming the lower surface is divided into two parts, 503 and 504, is to drop the glass material downward and put it into the mold in the subsequent molding. 505 and 506 are outer frames for sealing high temperature gas, and 506 is divided into two like the porous carbon material. Reference numerals 507, 508, and 509 denote pipes for introducing a high-temperature gas, and the high-temperature gas is sent from a heating device (not shown).
[0324]
Here the hot gas is 106The temperature was set to 740 ° C., which is dPa · s, and hot gas was blown out at a flow rate of 30 liters / minute to deform as shown in FIG. In FIG. 33B, 510 is a hot gas, and 511 is a deformed glass material. After 2 minutes, the porous carbon material 502 for forming the upper surface was kept away from the glass material, and the flow rate of the hot gas blown out from the porous carbon materials 503 and 504 for forming the lower surface was reduced to 2 liters / minute. This takes the relationship between the blowout time and the thickness of the glass material, and after 2 minutes, the required thickness reaches 8.7 mm. In order to suppress deformation, the porous carbon material 502 for forming the upper surface is moved away. A high-temperature gas was blown out from the porous carbon materials 503 and 504 for forming the lower surface at a flow rate sufficient to hold. During the deformation for 2 minutes, the porous carbon material 502 for forming the upper surface is gradually moved downward due to the relationship between the blowing time and the deformation amount.
[0325]
When the surface roughness of the glass material produced by this method was measured, the cut block material before thermal deformation had an Rmax of 1 μm or more, which was 0.02 μmm, which satisfied the specifications of the glass material for molding. .
As a comparative example, the situation when the temperature of the hot gas is changed is shown in FIG. First, the viscosity of the glass is 104.5When the temperature corresponding to dPa · s is set to 840 ° C., the deformation is sudden, and even if the flow rate is reduced, the deformation proceeds due to its own weight, and as shown in FIG. 35, it is deformed to the outside of the porous carbon material. This is a glass viscosity of 105If the temperature is equal to or lower than 800 ° C. corresponding to dPa · s, it is not generated by reducing the flow rate of the high temperature gas. Conversely, the temperature of the hot gas is set to 10 as the viscosity of the glass.8.5When the temperature corresponding to dPa · s was set to 655 ° C., deformation was very slow and required several tens of minutes to obtain the required shape, and the surface roughness was not less than 0.04 μm in Rmax. However, the viscosity of glass is 108If the temperature is equal to or higher than 675 ° C. corresponding to dPa · s, the deformation is completed in a few minutes, and the surface roughness is Rmax 0.04 μm or less, which satisfies the specifications of the glass material.
[0326]
A method for press-molding this glass material to form an optical element will be described with reference to FIG. In FIG. 36, 512 is an upper mold for forming the upper surface of the lens, and the surface 512a that comes into contact with the glass is polished to R54. Reference numeral 513 denotes a lower mold for forming the lower surface of the lens, and a surface 513a that comes into contact with glass is polished to R30. Reference numeral 514 denotes a body mold for aligning the upper and lower mold axes. As shown in FIG. 36 (a), the glass material is floated and taken right above the lower mold 513. As shown in FIG. 36 (b), the porous carbon member is opened to the left and right and the glass is placed on the lower mold. Drop the material. At this time, the upper and lower molds have a viscosity of 1012The temperature is adjusted to 570 ° C. corresponding to dPa · s by a heating device (not shown). Thereafter, the porous carbon material is taken out of the body mold, and the upper mold is lowered and pressed as shown in FIG. The press is deformed in contact from the center of the glass material, and no gas residue is generated. The press deformation ends when the upper collar portion 512b hits the upper portion 514a of the body mold. According to the Fizeau interferometer, the lens produced by this method had good shape accuracy with 0.5 or less Newton rings. The mold temperature is 10 times the viscosity of this glass.13When the temperature was higher than dPa · s (low temperature), the temperature of the glass dropped until the deformation was completed, and the glass surface was not pushed out, and the lens surface was wrinkled. Conversely, the mold temperature is set to 1010If it is smaller than dPa · s (high temperature), it will be deformed due to its own weight or external force at the time of removal if it is taken out immediately after the press is completed.10After cooling below the temperature corresponding to dPa · s, it had to be taken out. In addition, the mold was severely deteriorated and its durability was lowered. As described above, according to the method for producing a glass material and the subsequent press molding method according to the present embodiment, a glass material having a required volume, shape, and surface roughness can be produced at low cost from a cut glass block. In addition, the molding time can be shortened and the durability of the mold can be improved.
[0327]
(Twenty-seventh embodiment)
As shown in FIG. 37, a glass material for forming a concave lens was produced. Glass26thThis is the same as that used in the embodiment. The temperature of the hot gas is set to 10 as the glass viscosity.7The temperature was set to 705 ° C. corresponding to dPa · s, and the flow rate was set to 35 liters / minute. The required center thickness was obtained by blowing out for 3 minutes. The temperature of the hot gas from the porous carbon member 518 for forming the upper surface is set to 10 as the viscosity of the glass when blown out for 3 minutes.9.5The flow rate was changed to 620 ° C. corresponding to dPa · s to 5 liters / minute, the temperature of the hot gas from the porous carbon member 519 for forming the lower surface was changed to 705 ° C., and the flow rate was changed to 5 liters / minute. After 2 minutes, the hot gas was stopped from blowing out, and at the same time a vacuum was drawn from the hot gas introduction pipe 522 to the upper surface forming porous carbon member 518, and the glass material 517 was vacuum adsorbed to the upper surface forming porous carbon member 518. . The reason for lowering the temperature of the high-temperature gas from the porous carbon member 518 for forming the upper surface before adsorption is that the glass material 517 and the porous carbon member 518 are easily deformed when the temperature of the glass material is high. This is because it becomes difficult to drop the glass onto the lower mold in the subsequent process.
[0328]
With vacuum suction, the glass material 517 is carried right above the lower mold as shown in FIG. 38A, and a little gas is blown out as shown in FIG. To drop. At this time, the upper and lower molds 525 and 526 have a glass viscosity of 1010The temperature is adjusted to 600 ° C. corresponding to dPa · s. Here, 528 is a positioning pin for setting the glass material at the center of the lower mold. Thereafter, the porous carbon member is taken out of the body mold, and the upper mold 525 is lowered and pressed as shown in FIG. At this time, the positioning pin moves away from the glass material 517 when press deformation starts.
[0329]
According to the Fizeau interferometer, the lens produced by this method had good shape accuracy with 0.5 or less Newton rings.
As described above, according to the glass material production method and the subsequent press molding method according to the present embodiment, a glass material having a required volume, shape, and surface roughness can be produced at low cost from the cut glass block. In addition, the molding time can be shortened and the durability of the mold can be improved.
[0330]
Further, a temperature difference is provided between the upper and lower surfaces of the glass material, and the glass material can be conveyed by vacuum suction.
(Twenty-eighth embodiment)
As shown in FIG. 39, a glass material 531 for forming a convex meniscus lens was produced. The glass whose composition is shown in FIG. 40 was used. The glass material 531 was produced and press-molded by the same method as in the twenty-sixth embodiment. However, as a condition, the high-temperature gas has a glass viscosity of 106The temperature was 740 ° C. corresponding to dPa · s, and spraying was performed at a flow rate of 40 liters / minute for 3 minutes. The temperature of the upper and lower molds for molding the optical element is 10 as the viscosity of the glass.12The temperature was set to dPa · s.
[0331]
The lens produced by this method has a shape accuracy of 0.5 or less Newton rings by Fizeau interferometer, but the deterioration of the lower mold is severe and the fogging durability of the molded product is only about 100 shots. There wasn't. Therefore, in order to suppress the deterioration of the lower mold, after forming the shape at the time of producing the glass material, the high temperature gas from the porous carbon for forming the lower surface is changed to 10 by the viscosity of the glass.9.5After maintaining the temperature corresponding to dPa · s for 3 minutes, it was put into the lower mold. Then, the deterioration of the lower mold disappeared, and fogging of the molded product did not occur even after 2000 shot molding.
[0332]
As described above, according to the glass material production method and the subsequent press molding method according to the present embodiment, a glass material having a required volume, shape, and surface roughness can be produced at low cost from the cut glass block. In addition, the molding time can be shortened and the durability of the mold can be improved.
Further, with regard to glass whose mold is severely deteriorated, the durability of the mold can be improved by lowering the temperature of the lower surface of the glass material.
[0333]
In this embodiment, carbon is used as the porous member, but the same effect was obtained with other porous ceramics and metals.
26th to above28thIn summary, in the thirty-third method, a glass lump adjusted to a predetermined volume by cutting or grinding has a glass viscosity of 10 with high-temperature gas between porous members.Five-108By heating to dPa · s, it is deformed into a predetermined shape and its surface roughness is made Rmax 0.04 μm or less. Since this is heating by a high-temperature gas, it is not in direct contact with the mold and is not affected by the surface roughness of the mold. The viscosity of the glass is 10Five-108Since it is heated to dPa · s, it can be transformed from a cube or a rectangular parallelepiped into a lens shape.
[0334]
In the thirty-fourth method, the glass material produced by the thirty-third method is 10 in terms of the viscosity of the glass.10-1013It is put into a mold adjusted to a temperature corresponding to dPa · s and press-molded. Since the temperature of the glass material is such that it is deformed by a high-temperature gas, the mold temperature is 10 as the viscosity of the glass.10When the glass temperature is lower than dPa · s (high temperature) and the glass temperature is high, the mold deteriorates drastically and the durability of the mold decreases.10dPa · s or less) and the molding time becomes long. The mold temperature is 10 as the viscosity of the glass.10-1013By making the temperature corresponding to dPa · s, the deterioration of the mold is reduced, and the cooling time after pressing is shortened. The mold temperature is 10 in terms of glass viscosity.13If it is larger than dPa · s (low temperature), the glass is cooled during deformation and press deformation is not completed.
[0335]
Note that the present invention can be applied to modifications or variations of the above-described embodiment without departing from the spirit of the present invention.
[0336]
【The invention's effect】
As described above, according to the present invention, it is possible to avoid fusion, surface transfer failure, and deterioration of the molding surface of the mold due to contact between the molded product and the molding surface of the mold. Further, it is possible to avoid a shape transfer failure due to a difference in thermal expansion between the molding surface of the mold and the molded product. Furthermore, waste such as grinding polishing waste generated by a processing method such as grinding and polishing can be extremely reduced, and a large amount of precision elements such as lenses can be provided at low cost.
[0337]
Further, the mold and the glass can be molded in a non-contact state at the lens peripheral portion where fusion or film peeling is likely to occur. Furthermore, by giving a temperature difference to the gas ejected by the upper and lower molds, it is possible to stably leave the molded product on the lower mold when the mold is released and to prevent handling trouble. Furthermore, by using a porous material as the outer shape forming member, it is possible to obtain an optical element that does not need to be centered in a state in which glass does not enter the mold gap.
[0338]
Further, by controlling the temperature of the gas ejected from the receiving mold, it is possible to easily and reliably produce a glass lump suitable for an optical element molding material and having no recess on the lower surface. In addition, by controlling the temperature of the gas ejected from the molding die, the time required for heating and cooling can be shortened in a method for press-molding a glass lump to obtain a shaped glass lump having a desired shape. In addition, by controlling the temperature of the gas ejected from the receiving mold more accurately and quickly, it is possible to more easily and reliably produce a glass lump suitable for an optical element molding material and having no depression on the lower surface. I can do it. Furthermore, the time required for heating and cooling can be shortened in a method for press-molding a glass lump to obtain a shaped glass lump of a desired shape by controlling the temperature of the gas ejected from the mold more accurately and quickly. I can do it.
[0339]
Moreover, it becomes possible to produce a lens-shaped glass material having an arbitrary radius of curvature from the glass block at a low cost. In addition, it is possible to provide a temperature difference between the upper and lower surfaces of the glass material before being put into the mold, which is advantageous for conveyance to the mold and can improve the durability of the mold. In addition, the molding time can be shortened.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a precision element molding apparatus.
FIG. 2 is a diagram for explaining a molding material separation method;
FIG. 3 is a conceptual diagram showing a molding surface correction method.
FIG. 3A is a conceptual diagram illustrating a method of correcting a molding surface.
FIG. 4 is a diagram showing a structure of a mold unit.
FIG. 5 is a view showing a state of a molding material.
FIG. 6 is a diagram showing a structure of a mold.
FIG. 7 is a diagram showing the shape of the optical element after centering.
FIG. 8 is a diagram showing a mold material;
FIG. 9 is a diagram showing a temperature difference between an upper mold and a lower mold.
FIG. 10 is a diagram showing a structure of a mold.
FIG. 11 is a diagram showing the shape of the optical element after centering.
FIG. 12 is a diagram showing the relationship between the gas flow rate and the appearance quality of a molded product.
FIG. 13 is a view showing a structure of a mold.
FIG. 14 is a diagram showing an optical element that does not require centering.
FIG. 15 is a view showing a structure of a mold.
FIG. 16 is a diagram showing an optical element that does not require centering.
FIG. 17 is a view showing a structure of a mold.
FIG. 18 is a diagram showing a process of molding an optical element molding material.
FIG. 19 is a diagram showing a process of molding an optical element molding material.
FIG. 20 is a diagram illustrating a process of molding an optical element molding material.
FIG. 21 is a diagram showing a process of molding an optical element molding material.
FIG. 22 is a diagram showing a structure of a mold.
FIG. 23 is a diagram illustrating a process of molding an optical element molding material.
FIG. 24 is a diagram showing a process of molding an optical element molding material.
FIG. 25 is a diagram showing a process of molding an optical element molding material.
FIG. 26 is a diagram showing a process of molding an optical element molding material.
FIG. 27 is a diagram showing a structure of a mold.
FIG. 28 is a diagram showing a process of molding an optical element molding material.
FIG. 29 is a diagram showing a process of molding an optical element molding material.
FIG. 30 is a diagram showing a process of molding an optical element molding material.
FIG. 31 is a diagram showing a process of molding an optical element molding material.
FIG. 32 is a diagram showing a process of molding an optical element molding material.
FIG. 33 is a view showing a method for manufacturing a glass material for forming a convex lens.
FIG. 34 is a diagram showing the composition of a glass material.
FIG. 35 is a diagram showing a glass material that has been deformed too much.
FIG. 36 is a diagram showing a method for molding an optical element.
FIG. 37 is a view showing a method for manufacturing a glass material for forming a concave lens.
FIG. 38 is a diagram showing a method for molding an optical element.
FIG. 39 is a diagram showing a method for manufacturing a glass material for forming a convex meniscus lens.
FIG. 40 is a diagram showing the composition of a glass material.
FIG. 41 is a diagram showing a gas remaining state at the time of convex surface molding.
FIG. 42 is a diagram showing a gas remaining state at the time of concave surface molding.
FIG. 43 is a diagram showing a case where the capacity of the glass material is too large.
FIG. 44 is a diagram showing a case where the capacity of the glass material is too small.
[Explanation of symbols]
Type 1 unit
2 Lower mold components
3 Upper mold components
11 Lower mold parts
11a, 21a Molded surface
12 Lower mold holder
12a, 22a pressure chamber
13,23 Heater
21 Upper mold member
22 Upper mold holder
31 Supply pipe
32a, 32b Pressure / flow rate regulator
33a, 33b Heater
34a, 34b Flexible tube
41 controller
102a glass lump

Claims (36)

光学素子等の精密素子を溶融軟化状態の成形素材から直接に成形する方法において、
少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が多孔質の材料から作られた型ユニットを準備する工程と、
前記型ユニットを開き、多孔質の成形面からキャビティー内に流体を噴出させるとともに、溶融軟化された成形素材を供給するノズルから、溶融軟化状態の成形素材を成形面と非接触状態を保った状態で前記型ユニットに供給する工程と、
成形素材の自重と表面張力により、前記ノズルから型ユニットの成形面上に供給された成形素材を、前記ノズルから分離する工程と、
前記成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で前記型ユニットに圧力を加え、前記型ユニットを閉じ、前記成形素材を補正された成形面の状態にならわせ、補正された形状の成形品を得る工程と、
成形素材を型ユニットに供給した後から、型ユニットに圧力を加え型ユニットを閉じ、成形素材を成形面の形状に倣わせる工程の間に、成形素材への第１の冷却開始し、さらに前記型ユニットを閉じ、成形素材を成形面の形状にならわせた後に第二の冷却を開始し、成形品が所望する最終形状になるまでの間に冷却を行い精密素子の形状を得る工程と、
前記型ユニット内の精密素子の冷却完了後、型ユニットを開き精密素子を取り出す工程とを具備することを特徴とする精密素子の成形方法。In a method of directly molding precision elements such as optical elements from a molding material in a melt-softened state,
It is composed of at least two mold members, and has a shape that is corrected in advance so that the shape of the molding surface that determines the shape of the precision element of the cavity formed by them is the final shape of the desired precision element. And further providing a mold unit whose molding surface is made of a porous material;
The mold unit is opened, fluid is ejected from the porous molding surface into the cavity, and the melt-softened molding material is kept in non-contact with the molding surface from the nozzle that supplies the melt-softened molding material. Supplying the mold unit in a state;
Separating the molding material supplied from the nozzle onto the molding surface of the mold unit by its own weight and surface tension;
A molding surface in which fluid is ejected from the molding surface, pressure is applied to the mold unit in a state in which the molding material in a soft state and the molding surface are kept in a non-contact state, the mold unit is closed, and the molding material is corrected. To obtain a molded product with a corrected shape according to the state of
After supplying the molding material to the mold unit, pressure is applied to the mold unit to close the mold unit, and during the process of copying the molding material to the shape of the molding surface, the first cooling to the molding material is started, A step of closing the mold unit, making the molding material conform to the shape of the molding surface, starting the second cooling, and cooling until the molded product has a desired final shape to obtain the shape of the precision element; ,
And a step of opening the mold unit and taking out the precision element after the cooling of the precision element in the mold unit is completed. 前記成形面の予め補正された形状が、成形面より噴出させる流体の圧力、流量、温度、及び成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率をパラメーターとして含むシミュレーションにより得られることを特徴とする請求項１に記載の精密素子の成形方法。The pre-corrected shape of the molding surface forms the pressure, flow rate, temperature of the fluid ejected from the molding surface, the temperature and viscosity of the molding material, and the pressure and temperature applied to the mold unit, and the molding material and the molding surface. The method for molding a precision element according to claim 1 , wherein the method is obtained by simulation including a coefficient of thermal expansion of a mold member to be performed as a parameter. 前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴とする請求項１に記載の精密素子の成形方法。The pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape computes molding data and shape data during and after the molding of the molding material. The method for forming a precision element according to claim 1 , wherein the precision element is obtained. 前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴とする請求項１に記載の精密素子の成形方法。The method of molding a precision element according to claim 1 , wherein the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. 前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴とする請求項１に記載の精密素子の成形方法。2. The precision element according to claim 1 , wherein at least one of the ejection pressure of the fluid, the flow rate of the fluid, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. Molding method. 型ユニットに圧力を加え成形素材を加圧する際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力を制御することを特徴とする請求項１に記載の精密素子の成形方法。When pressurizing the mold material by applying pressure to the mold unit, the mold members that make up the mold unit are rotated and slid relative to the mold material, and the pressure of the fluid existing between the mold material and the molding surface is controlled. The method for forming a precision element according to claim 1 , wherein: 光学素子等の精密素子を成形する方法において、
少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、
少なくとも成形後に機能面となる部分に対応する部分の表面に、高低差が５μｍ以上の鋭角的な段差が存在しない様に仕上げられた成形素材を準備する工程と、
前記型ユニットを開き、成形素材を型ユニットに供給すると共に、多孔質の成形面からキャビティー内に流体を噴出させ、成形素材を成形面と非接触状態を保った状態で加熱し、軟化させる工程と、
成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、
該予備成形品の表面近傍の粘度が１０7.6ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、
補正された形状の精密素子の少なくとも表面近傍の粘度が１０8ｄＰａ・ｓ以上となったときに、成形面から流体の噴出を再開すると共に、精密素子と成形面との間に空隙を設ける工程と、
成形素材を加熱、軟化した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始し、成形面からの流体の噴出を再開した直後から第３の冷却を開始し、成形品が所望する最終形状になるまでの間に冷却を行い、精密素子の形状を得る工程と、
第２の冷却の際に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、
型ユニット内の精密素子の冷却完了後、型ユニットを開き精密素子を取り出す工程とを具備することを特徴とする精密素子の成形方法。In a method of molding a precision element such as an optical element,
It is composed of at least two mold members, and has a shape that is corrected in advance so that the shape of the molding surface that determines the shape of the precision element of the cavity formed by them is the final shape of the desired precision element. And providing a mold unit made of a porous material whose molding surfaces are mirror-finished;
A step of preparing a molding material finished so that there is no sharp step with a height difference of 5 μm or more on the surface of a portion corresponding to a portion that becomes a functional surface after molding;
The mold unit is opened, the molding material is supplied to the mold unit, and fluid is ejected from the porous molding surface into the cavity to heat and soften the molding material in a non-contact state with the molding surface. Process,
Fluid is ejected from the molding surface, the mold unit is closed with the softened molding material and molding surface kept in a non-contact state, and the molding material is made to conform to the corrected molding surface shape of the mold member. Obtaining a preform having a shape approximate to the shape of
When the viscosity in the vicinity of the surface of the preform becomes 10 7.6 dPa · s or more, the ejection of fluid from the molding surface is stopped, the mold unit is closed by applying pressure, and the preform and the mold member are molded. Pressurizing the surfaces in contact with each other, aligning the shape of the preform with the shape of the molding surface, and obtaining a corrected precision element;
A step of restarting the ejection of fluid from the molding surface and providing a gap between the precision device and the molding surface when the viscosity of at least the surface of the corrected precision device becomes 10 8 dPa · s or more When,
The first cooling to the molding material is started immediately after the molding material is heated and softened to the step of obtaining the preform, and the second cooling is performed immediately after obtaining the corrected precision element. Starting the third cooling immediately after resuming the ejection of fluid from the molding surface, cooling until the molded product has the desired final shape, and obtaining the shape of the precision element;
A step of following the mold member in accordance with the shrinkage of the element so as to maintain the adhesion between the surface of the element and the molding surface during the second cooling;
And a step of opening the mold unit and taking out the precision element after cooling of the precision element in the mold unit is completed. 前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率の少なくとも１つをパラメーターとして含むシミュレーションにより得られることを特徴とする請求項７に記載の精密素子の成形方法。The pre-corrected shape of the molding surface is a parameter of at least one of the temperature and viscosity of the molding material, the pressure and temperature applied to the mold unit, and the coefficient of thermal expansion of the mold member forming the molding material and the molding surface. The method for forming a precision element according to claim 7 , wherein the precision element is obtained by a simulation including. 前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴とする請求項７に記載の精密素子の成形方法。The pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape computes molding data and shape data during and after the molding of the molding material. The method for forming a precision element according to claim 7 , wherein the precision element is obtained. 前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴とする請求項７に記載の精密素子の成形方法。8. The precision element molding method according to claim 7 , wherein the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. 前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴とする請求項７に記載の精密素子の成形方法。8. The precision element according to claim 7 , wherein at least one of the ejection pressure of the fluid, the flow rate of the fluid, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. Molding method. 型ユニットに圧力を加え非接触の状態で成形素材を加圧する際及び形状転写後の型内での冷却の際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力を制御することを特徴とする請求項７に記載の精密素子の成形方法。When pressurizing the molding material in a non-contact state by applying pressure to the mold unit and cooling in the mold after shape transfer, the mold member constituting the mold unit is rotated and slid with respect to the molding material. The method for forming a precision element according to claim 7 , wherein the pressure of the fluid existing between the substrate and the forming surface is controlled. 光学素子等の精密素子を溶融軟化状態の成形素材から直接に成形する方法において、
少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、
前記型ユニットを開き、多孔質の成形面からキャビティー内に流体を噴出させると共に、溶融軟化された成形素材を供給するノズルより、溶融軟化状態の成形素材を成形面と非接触状態を保った状態で型ユニットに供給する工程と、
成形素材の自重と表面張力により、前記ノズルから型ユニットの成形面上に供給された成形素材を分離する工程と、
成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、
該予備成形品の表面近傍の粘度が１０7.6ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、
成形素材をノズルから分離した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始する工程と、
第２の冷却の際に、少なくとも、補正された形状の精密素子の表面と成形面との間に密着力が働いている間に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、
少なくとも、素子の表面と成形面との間の密着力が解消するまでの冷却を行い、その後、型ユニットを開き所望の形状に近似した形状を有する成形素子を取り出す工程と、
所望の形状に近似した形状の成形素子をさらに室温まで冷却し、所望の形状の精密素子を得る工程とを具備することを特徴とする精密素子の成形方法。In a method of directly molding precision elements such as optical elements from a molding material in a melt-softened state,
It is composed of at least two mold members, and has a shape that is corrected in advance so that the shape of the molding surface that determines the shape of the precision element of the cavity formed by them is the final shape of the desired precision element. And providing a mold unit made of a porous material whose molding surfaces are mirror-finished;
The mold unit is opened, fluid is ejected from the porous molding surface into the cavity, and the melt-softened molding material is kept in a non-contact state with the molding surface from a nozzle that supplies the melt-softened molding material. Supplying the mold unit in a state;
Separating the molding material supplied from the nozzle onto the molding surface of the mold unit by its own weight and surface tension;
Fluid is ejected from the molding surface, the mold unit is closed with the softened molding material and molding surface kept in a non-contact state, and the molding material is made to conform to the corrected molding surface shape of the mold member. Obtaining a preform having a shape approximate to the shape of
When the viscosity in the vicinity of the surface of the preform becomes 10 7.6 dPa · s or more, the ejection of fluid from the molding surface is stopped, the mold unit is closed by applying pressure, and the preform and the mold member are molded. Pressurizing the surfaces in contact with each other, aligning the shape of the preform with the shape of the molding surface, and obtaining a corrected precision element;
Immediately after separating the molding material from the nozzle and before the step of obtaining the preform, the first cooling to the molding material is started, and the second cooling is performed immediately after obtaining the corrected precision element. Starting the process;
At the time of the second cooling, at least while the adhesion force is working between the surface of the corrected precision element and the molding surface, the adhesion between the surface of the element and the molding surface is maintained. A step of following the mold member in accordance with the contraction of the element;
At least cooling until the adhesion force between the surface of the element and the molding surface is eliminated, then opening the mold unit and taking out the molding element having a shape approximate to the desired shape;
And a step of cooling a molding element having a shape approximate to a desired shape to room temperature to obtain a precision element having a desired shape. 前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率、及び成形素子の表面と成形面との間の密着力をパラメーターとして含むシミュレーションにより得られることを特徴とする請求項１３に記載の精密素子の成形方法。The pre-corrected shape of the molding surface is the temperature and viscosity of the molding material, the pressure applied to the mold unit, the temperature, the thermal expansion coefficient of the mold member forming the molding material and the molding surface, and the surface of the molding element. 14. The precision element molding method according to claim 13 , wherein the precision element molding method is obtained by a simulation including an adhesion force between the molding surface and the molding surface as a parameter. 前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴とする請求項１３に記載の精密素子の成形方法。The pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape computes molding data and shape data during and after the molding of the molding material. The method for forming a precision element according to claim 13 , wherein the precision element is obtained. 前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴とする請求項１３に記載の精密素子の成形方法。The method of molding a precision element according to claim 13 , wherein the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. 前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴とする請求項１３に記載の精密素子の成形方法。The precision element according to claim 13 , wherein at least one of the ejection pressure of the fluid, the flow rate of the fluid, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. Molding method. 前記第２の冷却の際の型部材の追従が、成形面と精密素子の間の密着力により行われることを特徴とする請求項１３に記載の精密素子の成形方法。14. The precision element molding method according to claim 13 , wherein the follow-up of the mold member during the second cooling is performed by an adhesion force between the molding surface and the precision element. 前記第２の冷却の際の型部材の追従が、型部材に圧力を加えることにより行われることを特徴とする請求項１３に記載の精密素子の成形方法。14. The method for forming a precision element according to claim 13 , wherein the follow-up of the mold member during the second cooling is performed by applying pressure to the mold member. 光学素子等の精密素子を成形する方法において、
少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、
少なくとも成形後に機能面となる部分に対応する部分の表面に、高低差が５μｍ以上の鋭角的な段差が存在しない様に仕上げられた成形素材を準備する工程と、
前記型ユニットを開き、成形素材を型ユニットに供給すると共に、多孔質の成形面からキャビティー内に流体を噴出させ、成形素材を成形面と非接触状態を保った状態で加熱し、軟化させる工程と、
成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、
該予備成形品の表面近傍の粘度が１０7.6ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、
成形素材を加熱、軟化した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始する工程と、
第２の冷却の際に、少なくとも、補正された形状の精密素子の表面と成形面との間に密着力が働いている間に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、
少なくとも、素子の表面と成形面との間の密着力が解消するまでの冷却を行い、その後、型ユニットを開き所望の形状に近似した形状を有する成形素子を取り出す工程と、
所望の形状に近似した形状の成形素子をさらに室温まで冷却し、所望の形状の精密素子を得る工程とを具備することを特徴とする精密素子の成形方法。In a method of molding a precision element such as an optical element,
It is composed of at least two mold members, and has a shape that is corrected in advance so that the shape of the molding surface that determines the shape of the precision element of the cavity formed by them is the final shape of the desired precision element. And providing a mold unit made of a porous material whose molding surfaces are mirror-finished;
A step of preparing a molding material finished so that there is no sharp step with a height difference of 5 μm or more on the surface of a portion corresponding to a portion that becomes a functional surface after molding;
The mold unit is opened, the molding material is supplied to the mold unit, and fluid is ejected from the porous molding surface into the cavity to heat and soften the molding material in a non-contact state with the molding surface. Process,
Fluid is ejected from the molding surface, the mold unit is closed with the softened molding material and molding surface kept in a non-contact state, and the molding material is made to conform to the corrected molding surface shape of the mold member. Obtaining a preform having a shape approximate to the shape of
When the viscosity in the vicinity of the surface of the preform becomes 10 7.6 dPa · s or more, the ejection of fluid from the molding surface is stopped, the mold unit is closed by applying pressure, and the preform and the mold member are molded. Pressurizing the surfaces in contact with each other, aligning the shape of the preform with the shape of the molding surface, and obtaining a corrected precision element;
The first cooling to the molding material is started immediately after the molding material is heated and softened to the step of obtaining the preform, and the second cooling is performed immediately after obtaining the corrected precision element. Starting the process;
At the time of the second cooling, at least while the adhesion force is working between the surface of the corrected precision element and the molding surface, the adhesion between the surface of the element and the molding surface is maintained. A step of following the mold member in accordance with the contraction of the element;
At least cooling until the adhesion force between the surface of the element and the molding surface is eliminated, then opening the mold unit and taking out the molding element having a shape approximate to the desired shape;
And a step of cooling a molding element having a shape approximate to a desired shape to room temperature to obtain a precision element having a desired shape. 前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率、及び成形素子の表面と成形面との間の密着力をパラメーターとして含むシミュレーションにより得られることを特徴とする請求項２０に記載の精密素子の成形方法。The pre-corrected shape of the molding surface is the temperature and viscosity of the molding material, the pressure applied to the mold unit, the temperature, the thermal expansion coefficient of the mold member forming the molding material and the molding surface, and the surface of the molding element. 21. The method for molding a precision element according to claim 20 , wherein the method is obtained by simulation including an adhesion force between the molding surface as a parameter. 前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴とする請求項２０に記載の精密素子の成形方法。The pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape computes molding data and shape data during and after the molding of the molding material. The method for molding a precision element according to claim 20 , wherein the precision element is obtained. 前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴とする請求項２０に記載の精密素子の成形方法。21. The precision element molding method according to claim 20 , wherein the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. 前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴とする請求項２０に記載の精密素子の成形方法。21. The precision element according to claim 20 , wherein at least one of the ejection pressure of the fluid, the flow rate of the fluid, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. Molding method. 前記第２の冷却の際の型部材の追従が、成形面と精密素子の間の密着力により行われることを特徴とする請求項２０に記載の精密素子の成形方法。21. The precision element molding method according to claim 20 , wherein the following of the mold member during the second cooling is performed by an adhesion force between the molding surface and the precision element. 前記第２の冷却の際の型部材の追従が、型部材に圧力を加えることにより行われることを特徴とする請求項２０に記載の精密素子の成形方法。21. The precision element molding method according to claim 20 , wherein the following of the mold member during the second cooling is performed by applying pressure to the mold member. 光学素子等の精密素子を溶融軟化状態の成形素材から直接に成形する方法において、
少なくとも二つ以上の型部材から構成され、それらにより形成されるキャビティーの精密素子の形状を決定する成形面の形状が、所望する精密素子の最終形状になるように予め補正された形状を有し、更に、それらの成形面が鏡面状態に仕上げられている多孔質の材料から作られた型ユニットを準備する工程と、
前記型ユニットを開き、多孔質の成形面からキャビティー内に流体を噴出させると共に、溶融軟化された成形素材を供給するノズルより、溶融軟化状態の成形素材を成形面と非接触状態を保った状態で型ユニットに供給する工程と、
成形素材の自重と表面張力により、前記ノズルから型ユニットの成形面上に供給された成形素材を前記ノズルから分離する工程と、
成形面から流体を噴出させ、軟化状態の成形素材と成形面とを非接触状態を保った状態で型ユニットを閉じ、成形素材を型部材の補正された成形面の形状にならわせ、成形面の形状に近似した形状を有する予備成形品を得る工程と、
該予備成形品の表面近傍の粘度が１０7.6ｄＰａ・ｓ以上となったときに、成形面からの流体の噴出を停止し、型ユニットに圧力を加えて閉じ、予備成形品と型部材の成形面を接触させた状態で加圧し、予備成形品の形状を成形面の形状にならわせ、補正された形状の精密素子を得る工程と、
補正された形状の精密素子の少なくとも表面近傍の粘度が１０8ｄＰａ・ｓ以上となったときに、成形面から流体の噴出を再開すると共に、精密素子と成形面との間に空隙を設ける工程と、
成形素材をノズルから分離した直後から、予備成形品を得る工程までの間に、成形素材への第１の冷却を開始し、さらに補正された形状の精密素子を得た直後から第２の冷却を開始し、成形面からの流体の噴出を再開した直後から第３の冷却を開始し、成形品が所望する最終形状になるまでの間に冷却を行い精密素子の形状を得る工程と、
第２の冷却の際に、その素子の表面と成形面の密着を維持する様に、その素子の収縮に合わせて型部材を追従させる工程と、
型ユニット内の精密素子の冷却完了後、型ユニットを開き精密素子を取り出す工程とを具備することを特徴とする精密素子の成形方法。In a method of directly molding precision elements such as optical elements from a molding material in a melt-softened state,
It is composed of at least two mold members, and has a shape that is corrected in advance so that the shape of the molding surface that determines the shape of the precision element of the cavity formed by them is the final shape of the desired precision element. And providing a mold unit made of a porous material whose molding surfaces are mirror-finished;
The mold unit is opened, fluid is ejected from the porous molding surface into the cavity, and the melt-softened molding material is kept in a non-contact state with the molding surface from a nozzle that supplies the melt-softened molding material. Supplying the mold unit in a state;
Separating the molding material supplied from the nozzle onto the molding surface of the mold unit from the nozzle by the weight and surface tension of the molding material;
Fluid is ejected from the molding surface, the mold unit is closed with the softened molding material and molding surface kept in a non-contact state, and the molding material is made to conform to the corrected molding surface shape of the mold member. Obtaining a preform having a shape approximate to the shape of
When the viscosity in the vicinity of the surface of the preform becomes 10 7.6 dPa · s or more, the ejection of fluid from the molding surface is stopped, the mold unit is closed by applying pressure, and the preform and the mold member are molded. Pressurizing the surfaces in contact with each other, aligning the shape of the preform with the shape of the molding surface, and obtaining a corrected precision element;
A step of restarting the ejection of fluid from the molding surface and providing a gap between the precision device and the molding surface when the viscosity of at least the surface of the corrected precision device becomes 10 8 dPa · s or more When,
Immediately after separating the molding material from the nozzle and before the step of obtaining the preform, the first cooling to the molding material is started, and the second cooling is performed immediately after obtaining the corrected precision element. Starting the third cooling immediately after resuming the ejection of the fluid from the molding surface, obtaining the shape of the precision element by cooling until the molded product has a desired final shape,
A step of following the mold member in accordance with the shrinkage of the element so as to maintain the adhesion between the surface of the element and the molding surface during the second cooling;
And a step of opening the mold unit and taking out the precision element after cooling of the precision element in the mold unit is completed. 前記成形面の予め補正された形状が、成形素材の温度、粘度、及び型ユニットに与えられる圧力、温度、及び成形素材と成形面を形成する型部材の熱膨張率の少なくとも１つをパラメーターとして含むシミュレーションにより得られることを特徴とする請求項２７に記載の精密素子の成形方法。The pre-corrected shape of the molding surface is a parameter of at least one of the temperature and viscosity of the molding material, the pressure and temperature applied to the mold unit, and the coefficient of thermal expansion of the mold member forming the molding material and the molding surface. The method for forming a precision element according to claim 27 , wherein the precision element is obtained by a simulation including. 前記成形面の予め補正された形状が、前記所望する精密素子の最終形状に近似した形状を有し、該形状が前記成形素材の成形中及び成形終了後の成形データ、形状データを演算処理することにより得られることを特徴とする請求項２７に記載の精密素子の成形方法。The pre-corrected shape of the molding surface has a shape that approximates the final shape of the desired precision element, and the shape computes molding data and shape data during and after the molding of the molding material. The method for molding a precision element according to claim 27 , wherein the precision element is obtained. 前記成形面の多孔質部から噴出する流体の温度を制御する事により、成形素材の温度を制御することを特徴とする請求項２７に記載の精密素子の成形方法。28. The precision element molding method according to claim 27 , wherein the temperature of the molding material is controlled by controlling the temperature of the fluid ejected from the porous portion of the molding surface. 前記流体の噴出圧力と流体の流量と型ユニットへの加圧力の内の少なくとも一つ以上が、成形素材の粘度に対応して制御されることを特徴とする請求項２７に記載の精密素子の成形方法。28. The precision element according to claim 27 , wherein at least one of the ejection pressure of the fluid, the flow rate of the fluid, and the pressure applied to the mold unit is controlled in accordance with the viscosity of the molding material. Molding method. 型ユニットに圧力を加え非接触の状態で成形素材を加圧する際及び形状転写後の型内での冷却の際に、型ユニットを構成する型部材を成形素材に対し回転摺動させ、成形素材と成形面との間に存在する流体の圧力を制御することを特徴とする請求項２７に記載の精密素子の成形方法。When pressurizing the molding material in a non-contact state by applying pressure to the mold unit and cooling in the mold after shape transfer, the mold member constituting the mold unit is rotated and slid with respect to the molding material. 28. The method for molding a precision element according to claim 27 , wherein the pressure of the fluid existing between the nozzle and the molding surface is controlled. 重量調整されたガラス素材を成形用型でプレスして光学素子を成形する方法において、
前記成形用型型が、光学素子の少なくとも光線有効径内を形成するための第１の型部材と、それ以外の部分を形成するための第２の型部材で構成され、第２の型部材の内部または表面を経由してガスを成形面に流しながら成形することを特徴とする光学素子の成形方法。In a method of molding an optical element by pressing a weight-adjusted glass material with a molding die,
The mold for molding is composed of a first mold member for forming at least the effective diameter of the optical element and a second mold member for forming other portions, and the second mold member. A method for molding an optical element, wherein the molding is performed while flowing a gas on the molding surface through the inside or surface of the optical element. プレス成形中に前記第２の型部材と成形された光学素子はガス層を介して非接触であることを特徴とする請求項３３に記載の光学素子の成形方法。 34. The method of molding an optical element according to claim 33 , wherein the optical element molded with the second mold member during press molding is non-contact through a gas layer. 前記第２の型部材が多孔質セラミックまたは、多孔質金属または、多孔質炭素であることを特徴とする請求項３３に記載の光学素子の成形方法。 34. The method for molding an optical element according to claim 33 , wherein the second mold member is porous ceramic, porous metal, or porous carbon. 上型を構成する第２の型部材を経由するガスの温度と、下型を構成する第２の型部材を経由するガスの温度の差が１０℃以上であることを特徴とする請求項３３に記載の光学素子の成形方法。Claims and the temperature of the gas passing through the second mold member constituting the upper mold, the difference in temperature of the gas passing through the second mold member constituting the lower mold, characterized in that at 10 ° C. or higher 33 2. A method for molding an optical element according to 1.
JP31514096A 1996-11-26 1996-11-26 Optical element molding method and precision element molding method Expired - Fee Related JP3618937B2 (en)

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