JP3943958B2

JP3943958B2 - Method and apparatus for bending hollow double pipe

Info

Publication number: JP3943958B2
Application number: JP2002049082A
Authority: JP
Inventors: 三郎荒井
Original assignee: VISTA. CO., LTD.; Sankei Giken Kogyo Co Ltd
Current assignee: VISTA. CO., LTD.; Sankei Giken Kogyo Co Ltd
Priority date: 2002-02-26
Filing date: 2002-02-26
Publication date: 2007-07-11
Anticipated expiration: 2022-02-26
Also published as: JP2003245722A

Description

【０００１】
【発明の属する技術分野】
本発明は例えば自動車等の内燃機関の排気管などに使用する中空二重管の曲げ加工方法および装置に関する。
【０００２】
【従来の技術】
上記のような中空二重管の曲げ加工装置は、従来種々提案されており、従来は例えば内管内に棒状の内部芯金を、また内外管間に筒状芯金をそれぞれ挿入し、その内外管間の間隔を一定に保ったままで曲げダイスにより所定の角度に曲げ加工を施すようにしている（例えば、本出願人が先に提案した特開平１０−７１４３０号公報等参照）。
【０００３】
ところが最近の排気管等に用いる中空二重管は、軽量化や小型コンパクトに構成するために、内外管の間隔をなるべく狭くすることが求められている。そのため、内外管に配置する筒状芯金も必然的に肉厚を薄くせざるを得ないが、あまり薄いと筒状芯金が変形もしくは破損して良好に曲げ加工を施すことができない等の問題があった。
【０００４】
【発明が解決しようとする課題】
本発明は上記従来の問題点に鑑みて提案されたもので、内外管の間隔が狭く肉厚の薄い中空二重管にあっても良好に曲げ加工を施すことのできる中空二重管の曲げ加工方法および装置を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記の目的を達成するために本発明による中空二重管の曲げ加工方法および装置は、以下の構成としたものである。
【０００６】
即ち、本発明による中空二重管の曲げ加工方法は、中空二重管の内管内および内管と外管との間にそれぞれ芯金を挿入して曲げダイスにより曲げ加工を行う中空二重管の曲げ加工方法において、上記内管の一端部を除く略全長を予め断面略長円形に形成して外管内に挿入固定し、その内管と外管との間に舌片状の中間芯金を配置すると共に、先端部に断面略長円形の成形芯金を有する内部芯金を内管内に挿入したのち上記成形芯金を約９０度回動して該成形芯金の長軸方向が曲げダイスの半径方向に向いた状態で上記曲げダイスを回動して上記内外管の曲げ加工を行った後、上記内外管を上記内部芯金および成形芯金に対して相対移動させることによって上記曲げ加工部をも含めて上記成形芯金により断面長円形の内管の短軸方向の周面を拡径して外管と略同心状の円形状に成形するようにしたことを特徴とする。
【０００７】
また本発明による中空二重管の曲げ加工装置は、中空二重管の内管内および内管と外管との間にそれぞれ芯金を挿入して曲げ開始位置近傍に配置し、上記中空二重管を曲げダイスにより曲げ加工を行う中空二重管の曲げ加工装置において、上記内外管間に配置される芯金を舌片状に形成すると共に、上記内管内に配置される芯金の先端部に断面略長円形の成形芯金を屈折可能に且つ上記曲げ加工時に上記成形芯金の長軸方向が曲げダイスの半径方向に向いた状態となるように上記内管内に配置される芯金に対して約９０度回動可能に設けたことを特徴とする。
【０００８】
【発明の実施の形態】
以下、本発明による中空二重管の曲げ加工方法および装置を、図に示す実施形態に基づいて具体的に説明する。
【０００９】
図１は本発明による曲げ加工装置の一実施形態を示す横断平面図、図２はその右側面図、図３は図１におけるＡ−Ａ線断面図である。
【００１０】
本実施形態の曲げ加工装置は、基台１上の回動支軸１ａを中心に回動可能に設けた平面略円形の曲げダイス２と、その曲げダイス２に形成した接線方向に突出する突出部２ａに脱着可能に設けた固定用ダイス３と、上記曲げダイス２の近傍にそれと接するようにして上記基台１上に配置固定したシュー４と、そのシュー４に対して脱着可能に取付けた案内ダイス５等よりなり、上記曲げダイス２と固定用ダイス３との間に中空二重管１０を挟んで固定すると共に、上記シュー４と案内ダイス５との間に上記中空二重管１０を挟んで摺動可能に保持させる構成である。
【００１１】
上記中空二重管１０の内管１１としては、その一端側１１ａを除く略全長を予め断面略長円形１１ｂに形成したものを用いるもので、その長円形部分１１ｂの形成方法等は適宜であるが、例えば図４（Ａ）に示すように全体を断面円形に形成した内管１１の一端部１１ａを除く略全長を、図に省略したプレス機等で直径方向両側から押圧して同図（Ｂ）のように断面長円形に形成すればよい。そのようにして断面長円形に形成した内管１１の外側には、同図（Ｃ）のように外管１２を嵌合して、それら両管を相対的に位置固定するもので、その固定手段は適宜であるが本実施形態においては、内管１１の一端側１１ａの端縁１１ｃを拡径して外管内面に添わせ、その接合部を溶接によって一体的に固着した構成である。
【００１２】
上記の中空二重管１０を曲げ加工するに当たっては、内管１１の長円形部１１ｂ内に内部芯金６を、また上記長円形部１１ｂの短軸方向両側の内管１１と外管１２との間には一対の中間芯金７ａ・７ｂをそれぞれ配置するもので、上記内部芯金６は内管１１の長円形部１１ｂ内に丁度嵌る大きさの断面略長円形状に形成され、中間芯金７ａ・７ｂは上記長円形部１１ｂの短軸方向両側の内管１１と外管１２との間、より詳しくは内管短軸側と外管との間の間隔が広い部分の空間断面形状に合わせて図３に示すように断面略円弧状に形成されている。
【００１３】
上記中間芯金７ａ・７ｂは、図１に示すように、その後端部（図で左側）を基台１上に固定して設けた支持部材８に連結固定し、内部芯金６は連結ロッド６０を介して上記固定支持部材８に連結固定する構成である。その固定支持部材８に上記両芯金６，７ａ，７ｂを連結固定した状態において、その各芯金は図１に示すように前記曲げダイス２による曲げ開始位置Ｌの近傍に常時位置し、各芯金６，７ａ，７ｂの前端部は上記位置Ｌよりも前側（図で右側）に突出するように構成されている。
【００１４】
上記各中間芯金７ａ，７ｂの前端部の曲げ方向外側には、それぞれ面取り部７１が形成され、その各面取り部７１は内外管１１・１２の最終曲げ形状と略同一の曲面形状に形成されている。すなわち、曲げ方向内側に位置する中間芯金７ｂの面取り部７１は、内管１１の外周面の最終曲げ形状と略同一の曲面形状に形成され、曲げ方向外側に位置する中間芯金７ａの面取り部７１は、外管１２の内周面の最終曲げ形状と略同一の曲面形状に形成されている。
【００１５】
また内部芯金６の前端部は滑らかな曲面形状に形成され、その前端部には内管１１の前記長円形部１１ｂを曲げ加工する補助芯金６１と、上記長円形部１１ｂを略円形に成形加工する成形芯金６２とが順に数珠状に設けられている。その補助芯金６１は、内管１１の長円形部１１ｂ内に丁度嵌る大きさの断面略長円形状に形成され、該補助芯金６１の前記曲げ方向内側および外側の面は滑らかな曲面形状に形成されている。また上記成形芯金６２は、上記長円形部１１ｂ内を挿通可能な断面略長円形に形成され、その長軸方向両側の面は内管１１の前記一端側１１ａの円形部内周面と同径の円弧状曲面に形成されている。
【００１６】
上記内部芯金６と補助芯金６１および成形芯金６２との連結構造は適宜であるが、本実施形態においては、図５（ａ）に示すように内部芯金６と補助芯金６１とはリンク６３および連結ピン６４・６５とで屈折可能に連結され、成形芯金６２は上記連結ピン６５に一端を回動可能に連結したロッド６６を介して上記補助芯金６１および内部芯金６に対して屈折可能に連結すると共に、成形芯金６２に形成した孔６２ａに上記ロッド６６を摺動可能に嵌合することによって上記補助芯金６１および内部芯金６に対して回動可能に連結されている。図中、６７は上記ロッド６６に対する成形芯金６２の抜け止め兼回動範囲規制用の係止ピン、６２ｂはその係止ピン６７が摺動する円弧状長孔で、その長孔の範囲内において上記成形芯金６２は上記補助芯金６１および内部芯金６に対して約９０度回動可能である。
【００１７】
また前記内外管１１・１２を曲げ加工装置に装着した状態において、その内外管１１・１２の後端部には、図１に示すように曲げ加工時に内管１１を外管１２と共に曲げダイス２側に同時に送り出すための送り部材９を設けるとよく、その送り部材９は、本実施形態においては外管１２の端部外周面に嵌合固着する上下２つ割りの固定部材９１・９２と、その両固定部材９１・９２に形成した孔９１ａ・９２ａに両端部９３ａを貫通させて連結保持した内管押板９３等よりなる。
【００１８】
その内管押板９３は図１および図３に示すように前記一対の中間芯金７ａ・７ｂ間に位置し、その内管押板９３の中央部には前記内部芯金６の連結ロッド６０を挿通する摺動可能な貫通孔９３ａが形成されている。その内管押板９３を内管１１の後端部に当接させた状態で上記両固定部材９１・９２を外管１２の後端部外周面に被せ、その両固定部材９１・９２間に外管１２を挟んで一対のボルト９４で締付けることによって上記両固定部材９１・９２および内管押板９３を外管１２に一体的に固着する構成である。
【００１９】
上記の構成において、中空二重管１０を曲げるに当たっては、先ず、内部芯金６の連結ロッド６０および中間芯金７ａ・７ｂの後端部を支持部材８に連結固定すると共に、上記送り部材９のボルト９４を弛め、かつ固定用ダイス３を外した状態で、前記図６（Ａ）のように一端部を除く略全長を断面長円形に形成した内管１１と、その内管１１の外周に嵌合固着した外管１２とを曲げダイス２の所定の位置にセットする。
【００２０】
その際、内外管１１・１２間には中間芯金７ａ・７ｂを挿入し、内管１１内には内部芯金６およびそれに連結した補助芯金６１および成形芯金６２を挿入するもので、その成形芯金６２は前述のように断面長円形に形成されており、その長軸方向が内管１１の長円形部分１１ｂの長軸方向と平行となるように向きを揃えて挿入すればよい。
【００２１】
そして上記内外管１１・１２が図６（Ａ）のように所定の位置にセットされたところで、同図（Ｂ）のように成形芯金６２を手動もしくは工具等で約９０度回動して該成形芯金６２の長軸方向が曲げダイス２の曲げ方向すなわち曲げダイスの半径方向に向いた状態となるようにする。その状態で、固定用ダイス３を取付け、送り部材９の内管押板９３を内管１１の後端部に当接させた状態でボルト９４を締め付けることによって前記図１の状態にセットされる。
【００２２】
次いで、上記図１の状態から曲げダイス２を固定用ダイス３と共に図中矢印ａ方向に回動すると、中空二重管１０の外管１２が同方向に徐々に引き寄せられ、その外管１２の後端部に固着した送り部材９も外管１２とともにダイス２側に移動する。それに伴って上記送り部材９の内管押板９３により内管１１も同方向に押されて外管１２と一体に曲げダイス２側に徐々に送り出されながら、曲げダイス２と、内部芯金６・補助芯金６１および中間芯金７ａ・７ｂによって内外管１１・１２が図７のように曲げダイスに沿って円弧状に湾曲形成される。
【００２３】
特に中間芯金７ａ・７ｂの前端部に、前記図１のように曲げ開始位置Ｌよりも前方に突出し、内外管１１・１２の最終曲げ形状と略同一形状の面取り部７１を形成すると、内外管１１・１２にしわ等が発生することなく良好に曲げ加工を施すことができる。又そのとき上記内外管１１・１２の曲げダイス２に沿う引っ張り回動動作に伴って内管１１の長円形部分１１ｂは前記成形芯金６２によって順次外管１２と略同心状の円形形状に成形されていく。
【００２４】
そして図７のように内外管１１・１２の所定の角度の曲げ加工が終了したところで、図８に示すように固定用ダイス３を外し、送り部材９のボルト９４を弛めて、内外管１１・１２を手動もしくは図に省略した引っ張り機構等によって図８の矢印ｂ方向に引き抜くと、内管１１の残りの長円形部分１１ｂが成形芯金６２によって順次円形形状に形成され、図９のように内外管１１・１２との間隔が略全長にわたって一定の同心状の屈曲した中空二重管が得られるものである。
【００２５】
つまり、本発明は中間芯金７ａ・７ｂの肉厚をかせぐために、内管を断面長円形に変形させて内外管１１・１２の隙間を増やした状態で内外管１１・１２間および内管１１内に、上記中間芯金７ａ・７ｂおよび内部芯金６を挿入して曲げ加工を行い、加工後に成形芯金６２により内管１１を所定の円形形状に戻すものである。また内管１１の長円形状から略真円への変化は周長をほぼ同じにすることで、内管１１に無理な力が掛かることなく成形でき、曲げ加工後は芯金から内外管を相対的に抜き取る作業で同時に容易に成形できるものある。
【００２６】
なお上記実施形態は、成形芯金６２を図６（Ａ）の状態から同図（Ｂ）の状態に手動もしくは工具等で回動するようにしたが、例えば前記ロッド６６と成形芯金６２の孔６２ａとの間に螺旋状のカム等を設けて、内外管１１・１２を曲げる際の内管１１と成形芯金６２との接触摩擦力で成形芯金６２が図６（Ａ）の状態から同図（Ｂ）の状態に自動的に回動するようにしてもよい。
【００２７】
あるいは上記ロッド６６と成形芯金６２との間にバネ等を設けて、自由状態において成形芯金６２が常時図６（Ｂ）の状態となるように回動付勢し、内外管１１・１２を装着する際には、内管１１の長円形部分１１ｂを成形芯金６２に嵌めて該長円形部分１１ｂと成形芯金６２の長軸方向が内部芯金６の長軸方向と揃うように回動して装着する。そして内外管１１・１２を図６（Ａ）の状態にセットしたとき成形芯金６２が上記のバネ等によって図６（Ｂ）の状態に自動的に回動するように構成することもできる。
【００２８】
【発明の効果】
以上説明したように本発明による中空二重管の曲げ加工方法および装置は、中空二重管の内管を、その一端部を除いて予め断面略長円形に形成して外管内に挿入固定し、その長円形内管と外管との間に略舌片状の中間芯金を、また内管内には、先端部に断面略長円形の成形芯金を有する内部芯金を、それぞれ挿入した状態で曲げダイスにより曲げ加工を行うと共に、上記内外管を引き抜くことによって上記長円形の内管を成形芯金により外管と略同心状の円形状に成形するようにしたから、内外管１１・１２の間隔が狭く内外管１１・１２間に前記従来例のような筒状芯金を用いることができない場合にも略同心状で所定の角度屈曲した中空二重管を容易に製造することができるものである。
【図面の簡単な説明】
【図１】本発明による曲げ加工装置の一実施形態を示す横断平面図。
【図２】上記曲げ加工装置の右側面図。
【図３】図１におけるＡ−Ａ線断面図。
【図４】（Ａ）〜（Ｃ）は曲げ加工用内外管の準備工程の一例を示す横断平面図。
（Ａ１）〜（Ｃ１）はその左側面図。
（Ａ２）〜（Ｃ２）はその右側面図。
【図５】（Ａ）は補助芯金および成形芯金の連結構造を示す一部横断平面図。
（Ｂ）は（Ａ）におけるＢ−Ｂ線断面図。
【図６】（Ａ）は曲げ加工装置に中空二重管を装着する状態の横断平面図。
（Ｂ）は曲げ加工装置に中空二重管を装着した状態の横断平面図。
【図７】上記曲げ加工装置による加工状態の横断平面図。
【図８】曲げ加工した中空二重管を加工装置から引き抜く状態の横断平面図。
【図９】（Ａ）は曲げ加工終了後の中空二重管の横断平面図。
（Ｂ）は（Ａ）におけるＢ−Ｂ線断面図。
【符号の説明】
１基台
２曲げダイス
３固定用ダイス
４シュー
５案内ダイス
６内部芯金
６１補助芯金
６２成形芯金
７中間芯金
８固定支持部材
９送り部材
１０中空二重管
１１内管
１２外管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for bending a hollow double pipe used for an exhaust pipe of an internal combustion engine such as an automobile.
[0002]
[Prior art]
Various types of hollow double pipe bending apparatuses as described above have been proposed in the past. Conventionally, for example, a rod-shaped inner core bar is inserted into the inner pipe, and a cylindrical core bar is inserted between the inner and outer pipes. Bending is performed at a predetermined angle by a bending die while keeping the interval between the tubes constant (for example, see Japanese Patent Application Laid-Open No. 10-71430 previously proposed by the present applicant).
[0003]
However, hollow double pipes used for recent exhaust pipes and the like are required to be as narrow as possible between the inner and outer pipes in order to reduce the weight and to be compact and compact. For this reason, the cylindrical cored bar placed on the inner and outer pipes inevitably has to be made thinner, but if it is too thin, the cylindrical cored bar may be deformed or damaged and cannot be bent well. There was a problem.
[0004]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-mentioned conventional problems, and it is possible to bend a hollow double tube that can be bent well even in a hollow double tube having a small interval between the inner and outer tubes and a thin wall. An object is to provide a processing method and apparatus.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a method and apparatus for bending a hollow double tube according to the present invention has the following configuration.
[0006]
That is, the hollow double pipe bending method according to the present invention is a hollow double pipe in which a core metal is inserted in the inner pipe of the hollow double pipe and between the inner pipe and the outer pipe, and bending is performed by a bending die. In the bending method, the substantially entire length excluding one end of the inner tube is formed in advance in a substantially oval cross section and inserted and fixed in the outer tube, and a tongue-shaped intermediate core between the inner tube and the outer tube In addition, after inserting an inner core bar having a molded core bar having a substantially oval cross section at the front end into the inner tube, the molded core bar is rotated by about 90 degrees and the major axis direction of the molded core bar is bent. after bending of the inner and outer tube by rotating the bending die in a state oriented in a radial direction of the die, the by Rukoto by relatively moving the inner and outer pipes with respect to the internal core metal and molding the core metal expanding the peripheral surface of the short-axis direction of the oval cross section of the inner tube by the molding core metal including a processing unit bending Characterized in that so as to mold the outer tube substantially concentric circular shape by.
[0007]
Further, the hollow double pipe bending apparatus according to the present invention includes a metal core inserted in the inner pipe of the hollow double pipe and between the inner pipe and the outer pipe, and arranged near the bending start position. In a hollow double pipe bending apparatus for bending a pipe with a bending die, a cored bar arranged between the inner and outer pipes is formed in a tongue-like shape, and a tip of the cored bar arranged in the inner pipe A cored bar disposed in the inner tube so that the cored bar having a substantially oval cross section can be refracted and the long axis direction of the molded cored bar is oriented in the radial direction of the bending die during the bending process. On the other hand, it is provided so as to be rotatable about 90 degrees .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method and an apparatus for bending a hollow double pipe according to the present invention will be specifically described based on embodiments shown in the drawings.
[0009]
1 is a transverse plan view showing an embodiment of a bending apparatus according to the present invention, FIG. 2 is a right side view thereof, and FIG. 3 is a sectional view taken along line AA in FIG.
[0010]
The bending apparatus according to the present embodiment includes a planar substantially circular bending die 2 provided so as to be rotatable about a rotation support shaft 1a on a base 1, and a protrusion protruding in a tangential direction formed on the bending die 2. A fixing die 3 detachably provided on the portion 2a, a shoe 4 disposed and fixed on the base 1 in contact with the bending die 2 in the vicinity thereof, and a detachable attachment to the shoe 4 A guide die 5 or the like is used, and the hollow double tube 10 is fixed between the bending die 2 and the fixing die 3, and the hollow double tube 10 is connected between the shoe 4 and the guide die 5. It is the structure hold | maintained so that it can slide on both sides.
[0011]
As the inner tube 11 of the hollow double tube 10, a tube having a substantially entire length excluding its one end side 11 a formed in advance in a substantially oval cross section 11 b is used, and a method for forming the oval portion 11 b is appropriate. However, for example, as shown in FIG. 4A, the entire length excluding one end portion 11a of the inner tube 11 having a circular cross section as a whole is pressed from both sides in the diametrical direction with a press machine or the like omitted in the drawing. What is necessary is just to form in cross-sectional oval shape like B). The outer tube 12 is fitted on the outside of the inner tube 11 formed in an oval cross-section as shown in FIG. 3C, and the two tubes are relatively fixed in position. In this embodiment, the end 11c of the one end side 11a of the inner tube 11 is expanded to follow the inner surface of the outer tube, and the joint is integrally fixed by welding.
[0012]
In bending the hollow double tube 10, the inner core 6 is placed in the oval portion 11 b of the inner tube 11, and the inner tube 11 and the outer tube 12 on both sides of the oval portion 11 b in the short axis direction. A pair of intermediate core bars 7a and 7b are respectively disposed between the inner core bars 6. The inner core bar 6 is formed in a substantially oval cross section having a size that fits in the oval part 11b of the inner tube 11. The core bars 7a and 7b are spatial cross sections of a portion having a wide space between the inner tube 11 and the outer tube 12 on both sides of the oval portion 11b in the short axis direction, more specifically, between the inner tube minor axis side and the outer tube. According to the shape, as shown in FIG.
[0013]
As shown in FIG. 1, the intermediate core bars 7a and 7b are connected and fixed to a support member 8 provided with their rear end portions (left side in the figure) fixed on the base 1, and the inner core bars 6 are connected rods. In this configuration, the fixing support member 8 is connected and fixed via the reference numeral 60. In the state where the above-mentioned cored bars 6, 7a, 7b are connected and fixed to the fixed support member 8, the respective cored bars are always located in the vicinity of the bending start position L by the bending die 2, as shown in FIG. The front end portions of the core bars 6, 7a, 7b are configured to protrude to the front side (right side in the drawing) from the position L.
[0014]
A chamfered portion 71 is formed on the outer side in the bending direction of the front end portion of each of the intermediate core bars 7a and 7b, and each chamfered portion 71 is formed in a curved surface shape that is substantially the same as the final bent shape of the inner and outer tubes 11 and 12. ing. That is, the chamfered portion 71 of the intermediate core metal 7 b located inward bend is formed in the final bent shape substantially the same curved shape of the outer peripheral surface of the inner tube 11, an intermediate core metal 7 which is located outwardly bending a The chamfered portion 71 is formed in a curved surface shape substantially the same as the final bent shape of the inner peripheral surface of the outer tube 12.
[0015]
The front end portion of the inner core bar 6 is formed in a smooth curved shape, and the front end portion thereof has an auxiliary core bar 61 for bending the oval portion 11b of the inner tube 11 and the oval portion 11b in a substantially circular shape. A forming metal core 62 to be formed is provided in a bead shape in order. The auxiliary cored bar 61 is formed in a substantially oval cross section having a size just fitting into the oval part 11b of the inner tube 11, and the inner and outer surfaces of the auxiliary cored bar 61 in the bending direction are smoothly curved. Is formed. The formed core bar 62 is formed in a substantially oval cross section that can be inserted into the oval portion 11b, and both surfaces in the major axis direction have the same diameter as the inner circumferential surface of the circular portion on the one end side 11a of the inner tube 11. Are formed in an arcuate curved surface.
[0016]
The connecting structure of the inner core bar 6, the auxiliary core bar 61, and the molded core bar 62 is appropriate. In the present embodiment, as shown in FIG. Are connected to the link 63 and the connecting pins 64 and 65 so as to be able to bend, and the formed cored bar 62 is connected to the connecting pin 65 via a rod 66 whose one end is rotatably connected to the auxiliary cored bar 61 and the inner cored bar 6. The rod 66 is slidably fitted in a hole 62a formed in the molded core 62 so as to be rotatable with respect to the auxiliary core 61 and the inner core 6. It is connected. Drawing, stop and locking pin for rotation range restricting leakage of molding the core metal 62 with respect to the rod 66 is 67, 62 b in the arc-shaped elongated hole whose locking pin 67 slides, the range of the long hole Inside, the forming cored bar 62 is rotatable about 90 degrees with respect to the auxiliary cored bar 61 and the inner cored bar 6.
[0017]
Further, when the inner and outer tubes 11 and 12 are mounted on a bending apparatus, the inner tube 11 and the outer tube 12 are bent together with the outer tube 12 at the rear end of the inner and outer tubes 11 and 12 as shown in FIG. It is preferable to provide a feeding member 9 for simultaneously feeding to the side, and in this embodiment, the feeding member 9 is divided into two upper and lower fixing members 91 and 92 which are fitted and fixed to the outer peripheral surface of the end portion of the outer tube 12. It consists of an inner tube pressing plate 93 and the like which are held by connecting both end portions 93a through holes 91a and 92a formed in both fixing members 91 and 92.
[0018]
As shown in FIGS. 1 and 3 , the inner tube pressing plate 93 is positioned between the pair of intermediate core bars 7 a and 7 b, and a connecting rod 60 of the inner core bar 6 is disposed at the center of the inner tube pressing plate 93. A slidable through-hole 93a is formed. In a state where the inner tube pressing plate 93 is in contact with the rear end portion of the inner tube 11, the both fixing members 91 and 92 are put on the outer peripheral surface of the rear end portion of the outer tube 12, The fixing members 91 and 92 and the inner tube pressing plate 93 are integrally fixed to the outer tube 12 by being tightened with a pair of bolts 94 with the outer tube 12 interposed therebetween.
[0019]
In the above configuration, when bending the hollow double tube 10, first, the connecting rod 60 of the inner core bar 6 and the rear end portions of the intermediate core bars 7 a and 7 b are connected and fixed to the support member 8, and the feed member 9 is also connected. In the state where the bolt 94 is loosened and the fixing die 3 is removed, the inner tube 11 having an approximately full length excluding one end as shown in FIG. The outer tube 12 fitted and fixed to the outer periphery is set at a predetermined position of the bending die 2.
[0020]
At that time, the intermediate metal cores 7a and 7b are inserted between the inner and outer pipes 11 and 12, and the inner metal core 6 and the auxiliary metal core 61 and the molded metal core 62 connected thereto are inserted into the inner pipe 11, The molded metal core 62 is formed in an oval cross section as described above, and may be inserted with its orientation aligned so that the major axis direction thereof is parallel to the major axis direction of the oval portion 11b of the inner tube 11. .
[0021]
Then, when the inner and outer pipes 11 and 12 are set at predetermined positions as shown in FIG. 6A, the forming core 62 is rotated about 90 degrees manually or with a tool or the like as shown in FIG. The long axis direction of the cored bar 62 is set to be in the state of bending the bending die 2, that is, the radial direction of the bending die. In this state, the fixing die 3 is attached, and the bolt 94 is tightened in a state where the inner tube pressing plate 93 of the feeding member 9 is brought into contact with the rear end portion of the inner tube 11, so that the state shown in FIG. .
[0022]
Next, when the bending die 2 is rotated together with the fixing die 3 from the state of FIG. 1 in the direction of arrow a in the figure, the outer tube 12 of the hollow double tube 10 is gradually drawn in the same direction. The feed member 9 fixed to the rear end also moves to the die 2 side together with the outer tube 12. Along with this, the inner tube 11 is also pushed in the same direction by the inner tube pressing plate 93 of the feeding member 9 and gradually fed to the bending die 2 side integrally with the outer tube 12, while the bending die 2 and the inner core 6. The inner and outer pipes 11 and 12 are curved and formed in an arc along the bending die as shown in FIG. 7 by the auxiliary core bar 61 and the intermediate core bars 7a and 7b.
[0023]
In particular, when the chamfered portion 71 that protrudes forward from the bending start position L as shown in FIG. 1 and has substantially the same shape as the final bent shape of the inner and outer tubes 11 and 12 is formed at the front end portion of the intermediate core bars 7a and 7b, The pipes 11 and 12 can be favorably bent without generating wrinkles or the like. At that time, the oval portion 11b of the inner tube 11 is sequentially formed into a substantially concentric circular shape with the outer tube 12 by the forming mandrel 62 in accordance with the pulling and turning operation of the inner and outer tubes 11 and 12 along the bending die 2. It will be done.
[0024]
When the bending of the inner and outer tubes 11 and 12 at a predetermined angle is completed as shown in FIG. 7, the fixing die 3 is removed as shown in FIG. 8, the bolt 94 of the feed member 9 is loosened, and the inner and outer tubes 11 are removed. 9 is pulled out in the direction of arrow b in FIG. 8 manually or by a pulling mechanism or the like omitted in the drawing, the remaining oval portion 11b of the inner tube 11 is sequentially formed into a circular shape by the forming cored bar 62, as shown in FIG. In addition, a concentric bent hollow double tube having a constant distance from the inner and outer tubes 11 and 12 over substantially the entire length can be obtained.
[0025]
That is, in the present invention, in order to increase the thickness of the intermediate core bars 7a and 7b, the inner pipe is deformed into an oval cross section so that the gap between the inner and outer pipes 11 and 12 is increased and between the inner and outer pipes 11 and 12 and the inner pipe 11 The intermediate cored bars 7a and 7b and the inner cored bar 6 are inserted therein and bent, and the inner pipe 11 is returned to a predetermined circular shape by the molded cored bar 62 after the processing. Substantially change to the perfect circle from the oval shape of the inner tube 11 also by substantially the same circumferential length, can be molded without excessive force to the inner tube 11 is applied, the inner and outer tube after bending the metal core Some of them can be easily molded at the same time by relatively extracting work.
[0026]
In the above-described embodiment, the formed cored bar 62 is rotated from the state of FIG. 6A to the state of FIG. 6B manually or by a tool. A helical core or the like is provided between the hole 62a, and the molded core bar 62 is in the state shown in FIG. 6A by the contact frictional force between the inner pipe 11 and the molded core bar 62 when the inner and outer pipes 11 and 12 are bent. May be automatically rotated to the state shown in FIG.
[0027]
Alternatively, a spring or the like is provided between the rod 66 and the cored bar 62, and the molded cored bar 62 is urged to rotate so as to always be in the state shown in FIG. Is attached, the oval portion 11b of the inner tube 11 is fitted to the molded core bar 62 so that the major axis direction of the oval portion 11b and the molded core bar 62 is aligned with the major axis direction of the inner core bar 6. Rotate and attach. When the inner and outer tubes 11 and 12 are set in the state shown in FIG. 6A, the molded cored bar 62 can be automatically rotated to the state shown in FIG.
[0028]
【The invention's effect】
As described above, the method and apparatus for bending a hollow double tube according to the present invention is such that the inner tube of the hollow double tube is formed in advance in a substantially oval cross section excluding one end thereof, and inserted and fixed in the outer tube. In addition, a substantially tongue-shaped intermediate cored bar is inserted between the oval inner tube and the outer tube, and an inner cored bar having a molded cored bar having a substantially oval cross section at the tip is inserted into the inner tube. In this state, the inner and outer pipes are formed into a circular shape substantially concentric with the outer pipe by forming the oval inner pipe by pulling out the inner and outer pipes. Even when the interval 12 is narrow and the cylindrical cored bar cannot be used between the inner and outer tubes 11 and 12, the hollow double tube that is substantially concentric and bent at a predetermined angle can be easily manufactured. It can be done.
[Brief description of the drawings]
FIG. 1 is a cross-sectional plan view showing an embodiment of a bending apparatus according to the present invention.
FIG. 2 is a right side view of the bending apparatus.
3 is a cross-sectional view taken along line AA in FIG.
FIGS. 4A to 4C are cross-sectional plan views illustrating an example of a preparation process for bending inner and outer pipes.
(A1)-(C1) are the left side views.
(A2)-(C2) is the right view.
FIG. 5A is a partially cross-sectional plan view showing a connecting structure of an auxiliary metal core and a molded metal core.
(B) is the BB sectional drawing in (A).
FIG. 6A is a cross-sectional plan view of a state in which a hollow double tube is attached to a bending apparatus.
(B) is a cross-sectional plan view of a state where a hollow double pipe is mounted on a bending apparatus.
FIG. 7 is a cross-sectional plan view of a processing state by the bending apparatus.
FIG. 8 is a cross-sectional plan view showing a state in which a bent hollow double pipe is pulled out from a processing apparatus.
FIG. 9A is a cross-sectional plan view of a hollow double tube after bending.
(B) is the BB sectional drawing in (A).
[Explanation of symbols]
1 Base 2 Bending Die 3 Fixing Die 4 Shoe 5 Guide Die 6 Internal Core 61 Auxiliary Core 62 Molded Core 7 Intermediate Core 8 Fixed Support Member 9 Feed Member 10 Hollow Double Tube 11 Inner Tube 12 Outer Tube

Claims

In a hollow double pipe bending method in which a core metal is inserted into the inner pipe of the hollow double pipe and between the inner pipe and the outer pipe, and bending is performed with a bending die, except for one end of the inner pipe. The entire length is formed in a substantially oval cross-section in advance and is inserted and fixed in the outer tube. A tongue-shaped intermediate core is disposed between the inner tube and the outer tube, and a molded core having a substantially oval cross-section at the tip. After inserting the inner cored bar having gold into the inner tube, the molded cored bar is rotated about 90 degrees , and the bending die is rotated with the long axis direction of the molded cored bar facing the radial direction of the bending die . and after bending of the inner and outer tube, an oval cross section by the molding core metal, including the bent portion by Rukoto moved relative to the inner and outer pipes with respect to the internal core metal and molding the core metal The inner surface of the inner tube of the inner tube is expanded in diameter to form a circular shape that is substantially concentric with the outer tube. Bending method of a hollow double tube, characterized in that.

A hollow double pipe is formed by inserting a metal core into the inner pipe of the hollow double pipe and between the inner pipe and the outer pipe and placing it in the vicinity of the bending start position, and bending the hollow double pipe with a bending die. in the bending apparatus, the metal core disposed between said inner and outer tubes so as to form a tongue-like, and capable refractive molding core metal of a substantially oval at the tip portion of the core bar disposed in the inner tube It is provided so as to be able to rotate about 90 degrees with respect to the core metal disposed in the inner tube so that the long axis direction of the formed core metal is oriented in the radial direction of the bending die during the bending process. A hollow double pipe bending machine.