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JP3547655B2 - Method for manufacturing speaker edge - Google Patents

Method for manufacturing speaker edge Download PDF

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Publication number
JP3547655B2
JP3547655B2 JP20491499A JP20491499A JP3547655B2 JP 3547655 B2 JP3547655 B2 JP 3547655B2 JP 20491499 A JP20491499 A JP 20491499A JP 20491499 A JP20491499 A JP 20491499A JP 3547655 B2 JP3547655 B2 JP 3547655B2
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JP
Japan
Prior art keywords
polyurethane foam
foam sheet
speaker edge
edge
speaker
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JP20491499A
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Japanese (ja)
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JP2001036997A (en
Inventor
信也 溝根
信也 金子
清 池田
裕子 山崎
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Inoac Corp
Panasonic Corp
Panasonic Holdings Corp
Original Assignee
Inoac Corp
Panasonic Corp
Matsushita Electric Industrial Co Ltd
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Description

【0001】
【発明の属する技術分野】
この発明は、コーン本体(スピーカ振動板本体とも称される。)周縁のスピーカエッジの製造方法に関する。
【0002】
【従来の技術】
通常、スピーカは、図に示すように、コーン紙からなるコーン本体50がその周縁に設けられたスピーカエッジ60を介してフレームFに保持されることにより、コーン本体50の振動が妨げられないようにされている。このスピーカエッジ60の形状は、コーン本体50の振動を妨げないようにするため、内周縁61と外周縁63間が上方あるいは下方へ断面円弧状に湾曲した屈曲部65とされている。
【0003】
従来、前記スピーカエッジの製造方法としては、発泡ゴム組成物を型内成形するものや、コーン本体を型内に配置して該型内に熱可塑性樹脂、例えばアクリルやポリカーボネートあるいは熱可塑性ポリウレタン樹脂等の溶融樹脂を射出成形するもの、またはブロック状に発泡成形されたポリウレタンフォームのスラブを所定厚みのシート状に切り出し、そのポリウレタンフォームシートをプレス型による1回の加熱圧縮成形でスピーカエッジ形状にするものなどがある。
【0004】
しかし、従来のスピーカエッジの製造方法には、次のような問題がある。まず、発泡ゴム組成物を型内成形する製造方法にあっては、得られるスピーカエッジが重いため、コーン本体と貼り合わせて使用すると振動系の質量が重くなり、音圧周波数特性が低下する問題がある。しかも、そのゴム製スピーカエッジはコーン本体との接着に際して高度な技術を要する問題もある。
【0005】
また、熱可塑性樹脂を溶融させて射出成形する製造方法にあっては、溶融樹脂の温度が200〜300℃程度と極めて高いため、型内でコーン本体と一体成形する際にコーン本体が熱で損傷し易い問題がある。
【0006】
また、ポリウレタンフォームシートを1回の加熱圧縮成形で製造する方法にあっては、図に示したスピーカエッジの屈曲部基部66,67の外側(凸側)がプレス成形型による加熱圧縮時に大きく伸ばされて低密度になると共に、反対の内側(凹側)がほとんど伸ばされることなく圧縮されて高密度になり、このようなスピーカエッジ表面における密度の不均一が強度の低下を招くため、スピーカエッジの耐久性等において好ましくなかった。特に、スピーカエッジは、スピーカエッジ60の内周側がコーン本体50の周縁と一緒に振動し、スピーカエッジ60の外周側がフレームFによって拘束されるため、フレーム側の屈曲部基部67に疲労が集中するようになり、前記のような1回の加熱熱圧縮成形で得られたスピーカエッジでは、屈曲部基部の強度が十分であるとは言い難かった。
【0007】
なお、その他の製造方法として、多孔質発泡樹脂シートからなる複数の細長い片を、その短辺側どうしで重ね合わせ、金型でリング状に加熱成形することにより、前記重ね合わせ部を熱溶着してリング状のエッジ仕掛かり品を作成し、次いでエッジ成形金型で加熱成形することによってスピーカエッジとする方法も提案されている。しかし、その場合、得られるスピーカエッジは、前記細長い片の重ね合わせ部において、密度及び剛性が、他の非重ね合わせ部よりも高くなって柔軟性が損なわれ、スピーカの音声出力の際に音響特性に悪影響を与えるだけでなく、強度的な耐久性にも悪影響を与えるようになる。
【0008】
【発明が解決しようとする課題】
この発明は、前記の点に鑑みなされたもので、軽量性、音響特性及び耐久性に優れるスピーカエッジを簡単に得ることのできる製造方法を提供するものである。
【0009】
【課題を解決するための手段】
すなわち、請求項1の発明は、6〜25mm厚さの軟質ポリウレタンフォームシートを平板で予備加熱圧縮して1.5〜4mm厚さの平板状圧縮ポリウレタンフォームシートにした後、前記平板状圧縮ポリウレタンフォームシートを環形状に切断し、次いで前記環形状からなる平板状圧縮ポリウレタンフォームシートを厚み0.6〜1.0mmとなるように凹凸型面を有するスピーカエッジ用金型でさらに加熱圧縮して屈曲部を有するスピーカエッジ形状に賦形することを特徴とするスピーカエッジの製造方法に係る。
【0010】
請求項2の発明は、前記軟質ポリウレタンフォームシートの密度が20〜60kg/m であることを特徴とする
【0011】
【発明の実施の形態】
以下添付の図面に従ってこの発明を詳細に説明する。
図1は請求項1の発明の一実施例に係る製造方法の概略を示す製造工程図である。
【0012】
まず、請求項1の発明の実施例について説明する。図1は、その実施例に係る製造工程を示す図であり、予備加熱圧縮成形工程、切断工程、最終加熱圧縮工程よりなる。
【0013】
予備加熱圧縮成形工程では、図1(a)に示すように、厚み6〜25mmの軟質ポリウレタンフォームシート11を平板21で予備加熱圧縮して厚み1.5〜4mmの平板状圧縮ポリウレタンフォーム12を形成する。
【0014】
軟質ポリウレタンフォームシート11は、軟質ポリウレタンフォームのスラブから、厚み6〜25mmのシートにカットしたものが用いられる。厚み6〜25mmとしたのは、予備加熱圧縮や最終加熱圧縮における圧縮程度を考慮し、スピーカの音響特性やスピーカエッジの耐久性が良好となるように設定した。軟質ポリウレタンフォームシート11の平面形状は、目的とするスピーカエッジよりも大きい形状であればよく、四角形や円形等とされる。また、軟質ポリウレタンフォームシート11の密度は20〜60kg/mが好ましい。この範囲の密度とすることによって、前記音響特性、耐久性及び軽量性がさらに優れたスピーカエッジが得られるようになる。
【0015】
平板21,21は、対向する面が平面とされたものであって金属等からなり、前記軟質ウレタンフォームシート11を平面間で挟むことができる大きさとされている。この平板21は、図示しない電熱ヒータ等の加熱手段と接続されて加熱されるようになっており、また図示しない公知のプレス装置と接続されて軟質ポリウレタンフォームシート11を平板状に圧縮できるようになっている。その際の加熱圧縮条件は、加熱温度が180〜240℃、圧縮時間が10〜120秒とされ、特には190℃〜210℃、15〜30秒とするのが、軟質ポリウレタンフォームシート11の圧縮形状を良好に固定できることから、好ましい。
【0016】
前記予備加熱圧縮成形によって軟質ポリウレタンフォームシート11が平板状に圧縮される際、軟質ポリウレタンフォームシート11が平板21によって均一に圧縮されるため、得られる平板状圧縮ポリウレタンフォームシート12は、密度の均一性が高いものとなる。
【0017】
続く切断工程では、前記平板状圧縮ポリウレタンフォームシート12を、図1(b)に示すように、スピーカエッジの大きさに対応した環形状にトムソン刃等の切断具22により切断し、環形状からなる平板状圧縮ポリウレタンフォームシート13を形成する。その際、前記平板状圧縮ポリウレタンフォームシート12は、既に予備加熱圧縮成形によって密度が増大し、剛性が適度に高まっているため、切断刃との接触部で変形が少なくなり、正確に切断することができるので、最終的にスピーカエッジになった際の寸法精度が高まる。
【0018】
最終加熱圧縮成形工程では、図1(c)に示すように、前記環形状からなる平板状圧縮ポリウレタンフォームシート13を、スピーカエッジ形状の凹凸型面を有するスピーカエッジ用金型23に挟んで加熱圧縮成形し、厚み0.6〜1.0mmのスピーカエッジに賦形する。加熱圧縮条件は前記予備加熱圧縮成形時と同様の範囲である。この工程において、前記環形状からなる平板状圧縮ポリウレタンフォームシート13は、既に予備加熱圧縮成形によって元の厚みよりも薄くなっているため、スピーカエッジ用金型23の凹凸に良好に追従し、しかも凹部や凸部に賦形される屈曲部では、その内面と外面とで伸び量の差が小さくなるため、圧縮により得られる密度が均一性の高いものになる。また、厚み0.6〜1.0mmに圧縮するのは、スピーカの良好な音響特性、スピーカエッジの耐久性が良好となるように設定された値である。
【0019】
前記のようにして得られたスピーカエッジ10は、軽量性に優れ、その後、スピーカコーン本体の外周縁に固着されて使用された場合、スピーカの音響特性に優れ、また耐久性にも優れる効果を奏する。
【0020】
【実施例】
以下にこの発明の具体的実施例と、参考のための比較例を示す。
・実施例1
密度33kg/mの軟質ポリウレタンフォームのスラブを厚み8mmにカットして平面寸法160×140mmからなる平面四角形の軟質ポリウレタンフォームシートを形成し、この1枚の軟質ポリウレタンフォームシートを、200℃に加熱した平らな鉄板間に配置し、20秒間予備加熱圧縮して厚み2mmの平板状圧縮ポリウレタンフォームシートを得た。その際、鉄板間の縁には厚さ2mmのスペーサー配置し、鉄板間の隙間が2mmとなるようにした。
【0021】
その後、前記平板状圧縮ポリウレタンフォームシートを内径80mm、外径140mmの環形状にトムソン刃で切断し、環形状からなる平板状圧縮ポリウレタンフォームシートを得た。次いで、前記環形状からなる平板状圧縮ポリウレタンフォームシートを、スピーカエッジ形状に対応した凹凸型面を有するスピーカエッジ用金型内に配置し最終加熱圧縮することによって、厚み;0.8mm、ロール径;4mm、ロール内径;107mm、ロール外径;125mm、ロール全高;6.4mmのスピーカエッジを得た。その際の加熱圧縮条件は、全圧力1トン、金型温度210℃、プレス時間15秒である。
【0022】
・実施例2
実施例1における鉄板間に配置したスペーサーの厚みを3mmにして、厚み3mmの平板状圧縮ポリウレタンフォームシートを形成した点を除き、その他は実施例1と同様にしてスピーカエッジを形成した。このスピーカエッジの厚みやその他の寸法は実施例1と同じである。
【0023】
・比較例1
実施例で用いた密度33kg/mの軟質ポリウレタンフォームのスラブを厚み8mmにカットして得た軟質ウレタンフォームシートを、予備加熱圧縮することなく、直接スピーカエッジ用金型で厚み0.8mmまで加熱圧縮し、比較例1のスピーカエッジを成形した。その際、スピーカエッジ用金型は実施例で用いたものを使用し、また加熱圧縮条件は、プレス時間を20秒とした以外実施例と同じである。
【0024】
・比較例2
実施例で用いた密度33kg/mの軟質ポリウレタンフォームのスラブを厚み12mmにカットしたものを用いた以外は、比較例1と同じ条件で比較例2のスピーカエッジを成形した。
【0025】
前記実施例及び比較例に対し、次のようにして引張強度、耐久音響試験、耐寒音響試験を行うと共に、屈曲部(コーナー部)断面については電子顕微鏡写真撮影を行って樹脂の疎密状態を調べた。それらの結果を表1に示す。
【0026】
引張強度の測定は、スピーカエッジの周方向を幅方向として10mm幅、径方向を長さ方向にして両端間長さ25mmで切断して得られたΩ状の試験片に対し、その両端を引張試験機のチャック(チャック間10mm)に固定し、両端間が拡がるように引っ張ることによって行った。なお、引張強度の測定は、JIS−K−7127にまねて行った。
【0027】
耐久音響試験は、ボイスコイル径26.2mm、外径106mm、重量3.3gのポリプロピレン製コーン本体(コーン紙)を、実施例と比較例のスピーカエッジに接合し、同一ボイスコイル、同一磁気回路のスピーカ(松下電子部品株式会社製、スピーカ品番「EAS14P124AR2」)に組み付け、ミュージックソースをピーク入力50W、平均25Wのレベルで入力し、常温における96時間の連続動作テストを行い、亀裂が発生するか否かを調べた。また、耐寒音響試験は、耐久音響試験と同様の構成とし、−40℃で15Wのホワイトノイズの定格入力を加え、96時間連続動作テストを行い、亀裂が発生するか否かを調べた。
【0028】
【表1】

Figure 0003547655
【0029】
前記測定の結果から、各実施例のスピーカエッジは、比較例1のスピーカエッジに比べて引張強度が強く、耐久音響試験、耐寒音響試験でも耐久性に優れているのがわかる。比較例2は、エッジの亀裂を防ぐため、ウレタンフォームシートの厚みを10mmに増して樹脂強度を高めようとしたものであるが、耐寒音響試験で亀裂が発生し、低温時での耐久性改善に効果が得られないことが判明した。
【0030】
また、スピーカエッジ断面に対する電子顕微鏡写真(図示せず)から、実施例1,2では屈曲部(コーナー部)においても、エッジ全体に渡って樹脂がほぼ均一に分散した構造となっているのが確認できた。それに対し、比較例1,2では、エッジの屈曲部に樹脂が密の部分と疎の部分が存在していた。その樹脂の不均一が耐久性や、音響に悪影響を与えていると考えられる。特に、比較例2においては、厚みを増したにも関わらず、樹脂の疎密が改善されていないのがわかった。
【0031】
【発明の効果】
以上図示し説明したように、請求項1の発明によれば、軟質ポリウレタンフォームシートを平板で予備加熱圧縮するため、その際に軟質ポリウレタンフォームシートには平板による均一な圧力が加わり、得られる平板状圧縮ポリウレタンフォームシートが、密度の均一性の高いものとなる。しかも、重ね合わせ部を有しないため、部分的に密度が高くなることもない。したがって、耐久性や音響特性が良好になる。さらに1枚の軟質ポリウレタンフォームシートを平板で予備加熱圧縮すればよいため、複数の細長い片を端部で重ね合わせてリング状にしながら型面間に配置して加熱圧縮する場合と異なり、重ね合わせ量や位置ズレ等に対する注意を払う必要がなくなり、作業が簡略になる。
【0032】
また、予備加熱圧縮では、厚さ6〜25mmの軟質ポリウレタンフォームシートを1.5〜4mm厚さとなるように圧縮するため、得られる平板状圧縮ポリウレタンフォームシートは、その後のスピーカエッジ用金型による加熱圧縮成形に必要な適度な柔軟性を備えている。しかも、予備加熱圧縮によって厚みが薄くされた平板状圧縮ポリウレタンシートを、スピーカエッジ用金型でスピーカエッジの凹凸形状に賦形するため、その賦形の際に凸部外側と凹部内側とで変形量の差が小さくなって密度の不均一を生じにくくなり、密度の不均一による音響特性及び耐久性の悪影響を減らすことができる。
【0033】
それらの効果に加え、請求項1の発明においては、環形状に切断する時点により、次のような作用、効果を奏する。
請求項1の発明では、予備加熱圧縮により密度が大になって形状保持性が高くなった平板状圧縮ポリウレタンシートに対し、環形状に切断する作業を行うため、その切断作業時に平板状圧縮ポリウレタンシートが捻れたり、歪んだりしにくく、正確に切断できるようになる。したがって小型から大型までの広範囲のスピーカエッジの製造に好適である。
【0034】
さらに、請求項の発明のように、用いる軟質ポリウレタンフォームシートを密度20〜60kg/mのものとすれば、音響特性及び耐久性がより良好なスピーカエッジを得ることができる。
【図面の簡単な説明】
【図1】請求項1の発明の一実施例に係る製造方法の概略を示す製造工程図である。
【図2】一般的なスピーカコーンの一部切り欠き斜視図である。
【符号の説明】
10 スピーカエッジ
10a 切断前のスピーカエッジ賦形品
11 軟質ポリウレタンフォームシート
11a 環形状からなる軟質ポリウレタンフォームシート
12 平板状圧縮ポリウレタンフォームシート
13 環形状からなる平板状圧縮ポリウレタンフォームシート
21 平板
22 切断具
23 スピーカエッジ用金型[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a speaker edge around a cone body (also referred to as a speaker diaphragm body).
[0002]
[Prior art]
Normally, as shown in FIG. 2 , the loudspeaker does not hinder the vibration of the cone body 50 by holding the cone body 50 made of cone paper on the frame F via the speaker edge 60 provided on the periphery thereof. It has been like that. The shape of the speaker edge 60 is a bent portion 65 curved between the inner peripheral edge 61 and the outer peripheral edge 63 upward or downward in an arc-shaped cross section so as not to hinder the vibration of the cone body 50.
[0003]
Conventionally, the method for producing the speaker edge includes a method in which a foamed rubber composition is molded in a mold, a method in which a cone body is disposed in a mold, and a thermoplastic resin such as acrylic, polycarbonate, or thermoplastic polyurethane resin in the mold. A slab of polyurethane foam formed by injection molding of a molten resin or foamed into a block shape is cut into a sheet having a predetermined thickness, and the polyurethane foam sheet is formed into a speaker edge shape by one heat compression molding using a press mold. There are things.
[0004]
However, the conventional method for manufacturing a speaker edge has the following problems. First, in the manufacturing method of molding a foamed rubber composition in a mold, since the obtained speaker edge is heavy, the mass of the vibrating system becomes heavy when used by being bonded to the cone body, and the sound pressure frequency characteristic is reduced. There is. In addition, there is a problem that the rubber speaker edge requires a high level of technology when adhering to the cone body.
[0005]
Further, in the production method of melting and injection-molding a thermoplastic resin, the temperature of the molten resin is extremely high at about 200 to 300 ° C., so that when the cone body is integrally molded with the cone body in a mold, the cone body is heated. There is a problem that is easily damaged.
[0006]
Further, in the method for producing the polyurethane foam sheet in a single heat compression molding, the outside of the bent base portions 66 and 67 of the speaker edge as shown in FIG. 2 (convex side) is large at the time of heat compression by press molding mold As the sheet is stretched to have a low density, the opposite inner side (concave side) is compressed almost without being stretched to a high density, and the unevenness of the density on the speaker edge surface causes a decrease in strength. It was not preferable in edge durability and the like. In particular, as for the speaker edge, the inner peripheral side of the speaker edge 60 vibrates together with the peripheral edge of the cone body 50, and the outer peripheral side of the speaker edge 60 is restrained by the frame F, so that the fatigue concentrates on the bent base 67 on the frame side. As described above, it was difficult to say that the strength of the base portion of the bent portion was sufficient in the speaker edge obtained by the one-time heat compression molding as described above.
[0007]
In addition, as another manufacturing method, a plurality of elongated pieces made of a porous foamed resin sheet are overlapped with each other on their short sides, and are heat-molded into a ring shape by a mold, thereby heat-welding the overlapped portion. In addition, a method has been proposed in which a ring-shaped edge-finished product is formed by heating and then heated and formed by an edge-forming mold to form a speaker edge. However, in this case, the obtained speaker edge has a higher density and rigidity at the overlapping portion of the elongated pieces than at the other non-overlapping portions, impairs flexibility, and generates an acoustic sound when the speaker outputs sound. Not only does it adversely affect the characteristics, but also has an adverse effect on strength durability.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and provides a manufacturing method capable of easily obtaining a speaker edge having excellent lightness, acoustic characteristics, and durability.
[0009]
[Means for Solving the Problems]
That is, the invention according to claim 1 is characterized in that a flexible polyurethane foam sheet having a thickness of 6 to 25 mm is preliminarily heated and compressed on a flat plate to obtain a flat compressed polyurethane foam sheet having a thickness of 1.5 to 4 mm. The foam sheet is cut into a ring shape, and then the flat compressed polyurethane foam sheet having the ring shape is further heated and compressed with a speaker edge mold having an uneven surface so as to have a thickness of 0.6 to 1.0 mm. The present invention relates to a method for manufacturing a speaker edge, which is shaped into a speaker edge having a bent portion .
[0010]
A second aspect of the present invention, the density of the flexible polyurethane foam sheet characterized in that it is a 20~60kg / m 3.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a manufacturing process diagram showing an outline of a manufacturing method according to an embodiment of the present invention .
[0012]
First, an embodiment of the present invention will be described. FIG. 1 is a view showing a manufacturing process according to the embodiment, and includes a preheating compression molding process, a cutting process, and a final heating compression process.
[0013]
In the preheating compression molding step, as shown in FIG. 1A, a flexible polyurethane foam sheet 11 having a thickness of 6 to 25 mm is preheated and compressed by a flat plate 21 to form a flat compressed polyurethane foam 12 having a thickness of 1.5 to 4 mm. Form.
[0014]
As the flexible polyurethane foam sheet 11, a sheet obtained by cutting a flexible polyurethane foam slab into a sheet having a thickness of 6 to 25 mm is used. The thickness was set to 6 to 25 mm in consideration of the degree of compression in the preheating compression and the final heating compression, and was set so that the acoustic characteristics of the speaker and the durability of the speaker edge were good. The planar shape of the flexible polyurethane foam sheet 11 may be any shape as long as it is larger than the intended speaker edge, such as a square or a circle. The density of the flexible polyurethane foam sheet 11 is preferably 20~60kg / m 3. By setting the density in this range, a speaker edge having more excellent acoustic characteristics, durability, and lightness can be obtained.
[0015]
The flat plates 21 and 21 have flat surfaces facing each other and are made of metal or the like, and have such a size that the soft urethane foam sheet 11 can be sandwiched between the flat surfaces. The flat plate 21 is connected to a heating means (not shown) such as an electric heater to be heated, and is connected to a known press device (not shown) so that the flexible polyurethane foam sheet 11 can be compressed into a flat plate shape. Has become. The heating and compression conditions at this time are as follows: a heating temperature of 180 to 240 ° C. and a compression time of 10 to 120 seconds, and particularly 190 ° C. to 210 ° C. and 15 to 30 seconds. This is preferable because the shape can be fixed well.
[0016]
When the flexible polyurethane foam sheet 11 is compressed into a flat plate shape by the preheating compression molding, the flexible polyurethane foam sheet 11 is uniformly compressed by the flat plate 21, so that the obtained flat compressed polyurethane foam sheet 12 has a uniform density. It becomes high.
[0017]
In the subsequent cutting step, the flat compressed polyurethane foam sheet 12 is cut into a ring shape corresponding to the size of the speaker edge by a cutting tool 22 such as a Thomson blade as shown in FIG. A compressed polyurethane foam sheet 13 is formed. At this time, the flat compressed polyurethane foam sheet 12 has already been increased in density by pre-heating and compression molding, and has a moderately increased rigidity. Therefore, dimensional accuracy at the time of finally becoming a speaker edge is improved.
[0018]
In the final heat compression molding step, as shown in FIG. 1 (c), the ring-shaped flat compressed polyurethane foam sheet 13 is heated by being sandwiched between speaker edge molds 23 having a speaker edge-shaped uneven surface. It is compression-molded and shaped into a speaker edge having a thickness of 0.6 to 1.0 mm. The heating compression conditions are in the same range as in the preheating compression molding. In this step, since the flat compressed polyurethane foam sheet 13 having the ring shape has already been thinner than the original thickness by the preheating compression molding, it follows the unevenness of the speaker edge mold 23 well, and In the bent portion formed into the concave portion or the convex portion, the difference in the amount of elongation between the inner surface and the outer surface is small, so that the density obtained by compression becomes high. Further, the compression to a thickness of 0.6 to 1.0 mm is a value set so that the good acoustic characteristics of the speaker and the durability of the speaker edge become good.
[0019]
The loudspeaker edge 10 obtained as described above is excellent in lightness, and when used after being fixed to the outer peripheral edge of the loudspeaker cone main body, the loudspeaker edge 10 has excellent effects of excellent acoustic characteristics and excellent durability. Play.
[0020]
【Example】
Hereinafter, specific examples of the present invention and comparative examples for reference are shown.
-Example 1
A slab of a flexible polyurethane foam having a density of 33 kg / m 3 is cut into a thickness of 8 mm to form a flat rectangular flexible polyurethane foam sheet having a planar dimension of 160 × 140 mm, and this single flexible polyurethane foam sheet is heated to 200 ° C. It was placed between flat iron plates and preheated and compressed for 20 seconds to obtain a 2 mm thick flat compressed polyurethane foam sheet. At that time, a spacer having a thickness of 2 mm was arranged on the edge between the iron plates so that the gap between the iron plates was 2 mm.
[0021]
Thereafter, the flat compressed polyurethane foam sheet was cut into a ring shape having an inner diameter of 80 mm and an outer diameter of 140 mm with a Thomson blade to obtain a ring-shaped flat compressed polyurethane foam sheet. Next, the flat compressed polyurethane foam sheet having the ring shape is placed in a speaker edge mold having an uneven surface corresponding to the speaker edge shape, and is finally heated and compressed to have a thickness of 0.8 mm and a roll diameter of 0.8 mm. 4 mm, roll inner diameter; 107 mm, roll outer diameter; 125 mm, roll height: 6.4 mm. The heating and compression conditions at that time are a total pressure of 1 ton, a mold temperature of 210 ° C., and a press time of 15 seconds.
[0022]
-Example 2
A speaker edge was formed in the same manner as in Example 1 except that the thickness of the spacer disposed between the iron plates in Example 1 was changed to 3 mm, and a flat compressed polyurethane foam sheet having a thickness of 3 mm was formed. The thickness and other dimensions of the speaker edge are the same as those in the first embodiment.
[0023]
-Comparative example 1
The flexible urethane foam sheet obtained by cutting the flexible polyurethane foam slab having a density of 33 kg / m 3 used in the examples to a thickness of 8 mm was directly heated to 0.8 mm in a speaker edge mold without preheating and compression. By heating and compressing, the speaker edge of Comparative Example 1 was formed. In this case, the speaker edge mold used was the same as that used in the example, and the heating and compression conditions were the same as in the example except that the pressing time was set to 20 seconds.
[0024]
-Comparative example 2
The speaker edge of Comparative Example 2 was molded under the same conditions as Comparative Example 1, except that the slab of the flexible polyurethane foam having a density of 33 kg / m 3 used in the example was cut to a thickness of 12 mm.
[0025]
The tensile strength, the durability acoustic test and the cold acoustic test were performed on the above Examples and Comparative Examples as follows, and the cross section of the bent portion (corner portion) was photographed with an electron microscope to check the density of the resin. Was. Table 1 shows the results.
[0026]
Tensile strength was measured by pulling both ends of an Ω-shaped test piece obtained by cutting the speaker edge at a width of 10 mm with the circumferential direction of the speaker edge as the width direction and a length of 25 mm between both ends with the radial direction as the length direction. The test was carried out by fixing to a chuck (10 mm between chucks) of a tester and pulling so as to widen both ends. The measurement of the tensile strength was performed according to JIS-K-7127.
[0027]
In the endurance acoustic test, a polypropylene cone body (cone paper) having a voice coil diameter of 26.2 mm, an outer diameter of 106 mm, and a weight of 3.3 g was joined to the speaker edges of the example and the comparative example, and the same voice coil and the same magnetic circuit were used. (Matsushita Electronic Parts Co., Ltd., speaker part number "EAS14P124AR2"), a music source is input at a peak input level of 50 W and an average level of 25 W, and a continuous operation test at room temperature for 96 hours is performed. I checked whether or not. Further, the cold-resistance acoustic test had the same configuration as the durability acoustic test. A rated input of 15 W of white noise was applied at −40 ° C., and a continuous operation test was performed for 96 hours to check whether or not cracks occurred.
[0028]
[Table 1]
Figure 0003547655
[0029]
From the measurement results, it can be seen that the speaker edge of each example has a higher tensile strength than the speaker edge of Comparative Example 1, and has excellent durability in the durability acoustic test and the cold acoustic test. In Comparative Example 2, in order to prevent edge cracking, the thickness of the urethane foam sheet was increased to 10 mm to increase the resin strength. However, cracks occurred in the cold acoustic test, and durability at low temperatures was improved. Was found to be ineffective.
[0030]
Also, from electron micrographs (not shown) of the speaker edge cross section, Examples 1 and 2 show that even in the bent portion (corner portion), the resin is almost uniformly dispersed throughout the entire edge. It could be confirmed. On the other hand, in Comparative Examples 1 and 2, the resin had a dense portion and a sparse portion at the bent portion of the edge. It is considered that the unevenness of the resin adversely affects durability and sound. In particular, in Comparative Example 2, it was found that the density of the resin was not improved even though the thickness was increased.
[0031]
【The invention's effect】
As shown and described above, according to the first aspect of the present invention , the flexible polyurethane foam sheet is preheated and compressed by a flat plate. At this time, a uniform pressure is applied to the flexible polyurethane foam sheet by the flat plate to obtain a flat plate. The compressed polyurethane foam sheet has high density uniformity. In addition, since there is no overlapping portion, the density does not partially increase. Therefore, durability and acoustic characteristics are improved. Further, since one flexible polyurethane foam sheet may be pre-heated and compressed on a flat plate, a plurality of elongated pieces are overlapped at the end to form a ring, and are placed between the mold surfaces while being heated and compressed. It is not necessary to pay attention to the amount and the displacement, and the operation is simplified.
[0032]
In the preheating compression, a flexible polyurethane foam sheet having a thickness of 6 to 25 mm is compressed so as to have a thickness of 1.5 to 4 mm. It has moderate flexibility required for heat compression molding. In addition, since the flat compressed polyurethane sheet whose thickness has been reduced by pre-heating and compression is shaped into the uneven shape of the speaker edge by the speaker edge mold, it is deformed between the convex outside and the concave inside during the shaping. The difference in the amount becomes small and uneven density is less likely to occur, and adverse effects of acoustic characteristics and durability due to uneven density can be reduced.
[0033]
In addition to these effects, in the invention of claim 1 , the following operations and effects are exerted depending on the time of cutting into a ring shape.
According to the first aspect of the present invention, the flat compressed polyurethane sheet having a high density and a high shape retention due to the preliminary heating and compression is cut into an annular shape. The sheet is less likely to be twisted or distorted, and can be cut accurately. Therefore, it is suitable for manufacturing a wide range of speaker edges from small to large.
[0034]
Furthermore, when the flexible polyurethane foam sheet used has a density of 20 to 60 kg / m 3 as in the invention of claim 2 , a speaker edge having better acoustic characteristics and durability can be obtained.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram showing an outline of a manufacturing method according to an embodiment of the present invention.
FIG. 2 is a partially cutaway perspective view of a general speaker cone.
[Explanation of symbols]
10 Speaker Edge 10a Speaker Edge Shaped Product Before Cutting 11 Soft Polyurethane Foam Sheet 11a Ring-Shaped Soft Polyurethane Foam Sheet 12 Flat Compression Polyurethane Foam Sheet 13 Ring-Shaped Flat Compression Polyurethane Foam Sheet 21 Flat Plate 22 Cutting Tool 23 Mold for speaker edge

Claims (2)

6〜25mm厚さの軟質ポリウレタンフォームシートを平板で予備加熱圧縮して1.5〜4mm厚さの平板状圧縮ポリウレタンフォームシートにした後、
前記平板状圧縮ポリウレタンフォームシートを環形状に切断し、
次いで前記環形状からなる平板状圧縮ポリウレタンフォームシートを厚み0.6〜1.0mmとなるように凹凸型面を有するスピーカエッジ用金型でさらに加熱圧縮して屈曲部を有するスピーカエッジ形状に賦形することを特徴とするスピーカエッジの製造方法。
After preheating and compressing a flexible polyurethane foam sheet having a thickness of 6 to 25 mm with a flat plate into a flat compressed polyurethane foam sheet having a thickness of 1.5 to 4 mm,
Cutting the flat compressed polyurethane foam sheet into a ring shape,
Then, the ring-shaped flat compressed polyurethane foam sheet is further heated and compressed in a speaker edge mold having an uneven surface so as to have a thickness of 0.6 to 1.0 mm to give a speaker edge shape having a bent portion. A method for manufacturing a speaker edge, characterized by being shaped.
前記軟質ポリウレタンフォームシートの密度が20〜60kg/m であることを特徴とする請求項1に記載のスピーカエッジの製造方法。Method of manufacturing a speaker edge according to claim 1, the density of the flexible polyurethane foam sheet characterized in that it is a 20~60kg / m 3.
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