JP3621194B2

JP3621194B2 - Core mold for bending hollow profiles

Info

Publication number: JP3621194B2
Application number: JP15449196A
Authority: JP
Inventors: 久男谷川; 公雄伊藤; 成幸中川; 謙二金森
Original assignee: Mitsubishi Aluminum Co Ltd; Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd; MA Aluminum Corp
Priority date: 1996-06-14
Filing date: 1996-06-14
Publication date: 2005-02-16
Anticipated expiration: 2016-06-14
Also published as: JPH105881A

Description

【０００１】
【発明の属する技術分野】
本発明は中空形材の曲げ加工用芯型に関するものであり、特に、回転式曲げ加工機などを用いて中空形材に曲げ加工を施す際に、その湾曲部におけるシワ、変形、亀裂などの発生を防止することができる中空形材の曲げ加工用芯型に関する。
【０００２】
【従来の技術】
自動車などの輸送機器を軽量化することはエネルギーの節約や地球環境の保全などの観点から重要な課題とされ、その解決手段の一つのとして、エンジン、構造部材、各種導管、ボディ表皮などがアルミニウム合金で製造されるようになってきている。アルミニウム合金をフレームなどの構造部材として用いる場合は、軽量でかつ比剛性に優れた方形横断面の中空形状が多く採用される。そして、これらの構造部材や各種導管の多くは、長さ方向に二次元的あるいは三次元的に湾曲した形状に成形される。湾曲した中空部材を成形する一つの方法は割り型を用いて鋳型する方法であるが、押出しによって予め直管状に成形された中空形材を後加工で曲げて成形することができれば、生産効率の面でも強度の面でも有利となる場合が多い。
【０００３】
しかし、例えば方形横断面の中空形材をそのまま曲げると、外向き湾曲面（曲げ半径が大きくなるほうの面）が延伸され、内向き湾曲面（曲げ半径が小さいほうの面）が圧縮されて側面が撓み、湾曲部における中空部が偏平に変形して、外向き湾曲面またはその近傍の側面に亀裂を生じたり、内向き湾曲面またはその近傍の側面にシワが寄ったり、極端な場合には湾曲部で折れてしまうなどの問題が生じる。
【０００４】
この問題を解決する一つの手段として、中空形材の湾曲部における横断面形状が変化しないように湾曲部の中に芯型を挿入した上で曲げ加工を行い、管体の偏平化やシワの発生を防止する方法が採用されている。この目的で用いられる芯型として、従来から湾曲芯型および積層芯型の２種類のものが知られている。
【０００５】
従来の芯型の内、湾曲芯型を用いて中空形材を曲げる方法の一例を図６に示す。
図６において、符号１は横断面長方形の中空形材を示している。この中空形材１はアルミニウム合金製で、押出成形により直管状に成形された形材である。
【０００６】
符号３０は全体として回転式曲げ加工機を示している。この回転式曲げ加工機３０は、概略、搬送台３１、ローラ部材３２、およびクランプ部材３３からなっている。搬送台３１は、中空形材１を定置してローラ部材３２の外周に沿って（図では右から左へ）搬送する装置である。ローラ部材３２は、中空形材１の内向き湾曲面３を受け込むローラ溝３４を有する円筒体であり、その軸芯３５に連結された回転駆動装置（図示せず）によって、搬送台３１の搬送方向と一致する方向に回転するようになっている。このローラ溝３４の曲げ半径は、中空形材１の内向き湾曲面３の設計された曲げ半径と一致している。クランプ部材３３は、図示しない支柱によってローラ部材の回転軸３５に連結され、ローラ部材３２と一緒に回転するようになっている。またこのクランプ部材３３は、中空形材１を受け込むクランプ溝３６を有していて、このクランプ溝３６とローラ溝３４との間に中空形材１を挟んで挟圧し、中空形材１の湾曲しようとする部分（湾曲部）の先端をローラ溝３４に固定するとともに、湾曲部における中空形材の横断面形状の変形を外側から拘束するようになっている。
【０００７】
ここで用いられる湾曲芯型４０は、概略、中空形材１の中空部に挿入し得る横断面形状を有する直方体であるが、ただし中空形材１の中空部に挿入された状態で、湾曲部の外向き湾曲面２の側となる面４２が、外向き湾曲面２の設計された曲げ半径と等しい曲げ半径を有する曲面に成形され、この湾曲面４２が湾曲芯型４０の先端部において、対向する平面４３に当接している。
【０００８】
先ず、中空形材１を回転式曲げ加工機３０の搬送台３１に定置し、その後端部の開口から、出し入れ自在の挿入棒４１の先端に固定した湾曲芯型４０を挿入し、湾曲部の内部に配置する。次に、中空形材１の湾曲部の前方先端をローラ溝３４とクランプ溝３６との間に挟んで固定する。この状態でローラ部材３２とクランプ部材３３とを一緒に回転軸３５の駆動力によって回転すると、中空形材１は、ローラ溝３４の曲げ半径を内向き湾曲面３の曲げ半径として曲げられる。この時、中空形材１の外向き湾曲面２は、湾曲芯型４０によって内側から拘束されているので、偏平化することなく、湾曲部においても一定の中空部横断面形状が維持されるようになる。
【０００９】
従来の芯型の他の例は積層芯型である。この積層芯型を用いて中空形材を曲げる方法の一例を図７に示す。
図７において、符号１は横断面長方形の中空形材を示している。また符号３０は全体として前記と同様な回転式曲げ加工機を示している。
【００１０】
この場合、中空形材１の湾曲部の内部には、積層芯型５０が、出し入れ自在の挿入棒５１の先端に取り付けられて挿入されている。この積層芯型５０は、長方形の可撓性材料からなる板材５１，５１，…が複数枚積層されてなり、その積層部の横断面形状が、中空形材１の中空部内に挿入し得る形状とされている。
【００１１】
この積層芯型５０を用いて中空形材１を曲げるには、先ず、この中空形材１を回転式曲げ加工機３０の搬送台３１に乗せ、直管状の中空形材１の中空部に上記の積層芯型５０を挿入し、挿入棒５１で湾曲部まで押し込み、中空形材１の湾曲部先端をローラ溝３４とクランプ溝３６との間に挟んで固定する。この状態でローラ部材３２とクランプ部材３３とを一緒に回転軸３５の駆動力によって回転すると、中空形材１は、ローラ溝３４の曲げ半径を内向き湾曲面３の曲げ半径として曲げられる。この時、中空形材１の内部の積層芯型５０もそれぞれの板材５１，５１，…が互いに進行方向にズレながら曲がり、積層芯型５０の横断面形状は湾曲しても変化しない。従って中空形材１も、積層芯型５０によって内側から拘束されて、湾曲部において偏平化することなく、中空部の横断面形状が一定に維持されるようになる。
【００１２】
【発明が解決しようとする課題】
しかし、従来の湾曲芯型４０または積層芯型５０を用いる方法にはそれぞれ問題があって、実質的に変形、シワ、亀裂などの欠点がない湾曲部を得ることは困難であった。すなわち、湾曲芯型４０を用いる場合は、回転式曲げ加工機３０によって中空形材１を曲げるに際して、中空形材１の内向き湾曲面３を拘束することができないので、この内向き湾曲面３およびその近傍の側面が圧縮されてシワになりやすい。一方、積層芯型５０を用いる場合は、積層部の横断面形状を中空形材１の中空部の横断面形状に一致させると曲げた後で中空形材１から抜き取れなくなるので、中空形材１の中空部の横断面寸法より幾分小さく成形する必要があり、このため、曲げ加工に際して、湾曲部の全周を拘束することができず、湾曲部に偏平化などの横断面形状の変化を起こしてしまう。
【００１３】
本発明は、上記の課題を解決するためになされたものであって、従ってその目的は、中空形材に曲げ加工を施す際に、湾曲部における中空形材の変形、シワ、亀裂などの発生を防止することができる中空形材の曲げ加工用芯型を提供することにある。
【００１４】
【課題を解決するための手段】
上記の課題は、外向き湾曲面の設計された曲げ半径と等しい曲げ半径の曲面を有し、芯型の少なくとも側面に配設されている湾曲型材と、外向き湾曲面と内向き湾曲面との間に積層されて中空形材の長さ方向に延びる複数の可撓性板材からなる積層型材とから構成された曲げ加工用芯型を提供することによって解決できる。上記の積層型材は、芯型の幅方向に湾曲型材に挟まれて配設されていることが好ましい。また、芯型の側面に配設された湾曲型材の少なくとも外向き湾曲面側の厚さが、芯型全体の幅の１５％ないし３５％の範囲内とされていることが好ましい。
【００１５】
本発明はまた、前記において、湾曲型材が芯型のそれぞれの側面に配設され、積層型材が湾曲型材に挟まれて配設され、それぞれの前記湾曲型材の厚さが外向き湾曲面側から内向き湾曲面側に向かって漸次縮小され、かつ積層型材の厚さが外向き湾曲面側から内向き湾曲面側に向かって漸次拡大されてなる曲げ加工用芯型を提供する。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態を実施例により図面を用いて説明する。以下の説明において、従来の技術として図６，図７を用いて説明した構成要素と共通しているものは同一番号を付してその説明を省略または簡略化する。
この実施例の曲げ加工用芯型（以下、単に「芯型」という）は、直管状の中空形材を曲げるために用いられるものである。この中空形材１は、図２に示すように、中空部の横断面形状が高さＨ、幅Ｄを有する長方形をなしている。この中空形材１は、湾曲部４において、高さＨの方向に、外向き湾曲面２を弧線Ｂに沿って曲げるように計画されている。従って、曲げられた後では、中空形材１の中空部の幅Ｄを形成する２面の内、一方が外向き湾曲面２となり、他方が内向き湾曲面３となる。また、中空部の高さＨを形成する面はそれぞれ側面５，５となる。
【００１７】
（実施例１）
図１は、前記の中空形材１を曲げるために用いる芯型１０の先端部を示している。
図１に示す芯型１０は、中空形材１の外向き湾曲面２の設計された曲げ半径と等しい曲げ半径の曲面２ａを有する湾曲型材１３と、外向き湾曲面２と内向き湾曲面３との間に積層されて中空形材１の長さ方向に延びる複数の可撓性板材１１ａ，１１ｂ，…，１１ｎからなる積層型材１２とから構成されている。
【００１８】
この芯型１０の横断面形状は長方形であって、その高さと幅の寸法は、これを中空形材１の中空部に許容し得るクリアランスを持って挿入し得る値とされている。ここでは説明のため、クリアランスを無視して、芯型１０の横断面の高さをＨ、幅をＤと表記する。
【００１９】
この芯型１０は、双方の側面５ａ，５ａに湾曲型材１３，１３が配設され、積層型材１２は、これらの湾曲型材１３，１３に挟まれて配設されている。そして、湾曲型材１３，１３の厚さｄは、芯型１０全体の幅Ｄの１５％ないし３５％の範囲内とされている。また、積層型材１２は、その先端が湾曲型材１３の先端より長さＬだけ突出している。
【００２０】
次に、この芯型１０を用いて前記の中空形材１を曲げる方法の一例を、図３を用いて説明する。この方法では、従来例において説明した前記の回転式曲げ加工機３０を使用する。
先ず、中空形材１を回転式曲げ加工機３０（例えば大洋社製「ドローベンダー」）の搬送台３１に定置し、前記の芯型１０を出し入れ自在の挿入棒１４の先端に固定して、中空形材１の後部開口から湾曲部４の位置まで挿入する。この際、湾曲型材１３の曲面２ａが、曲げようとする中空形材１の外向き湾曲面２に対向するように挿入する。
【００２１】
次に湾曲部４の先端部をローラ溝３４とクランプ溝３６との間に、内向き湾曲面３をローラ溝３４側として挟んで固定する。この状態でローラ部材３２とクランプ部材３３とを一緒に中空形材１の搬送方向に回転すると、中空形材１は、後方の直管部が搬送台３１によって拘束されているため、ローラ溝３４の曲げ半径を内向き湾曲面３の曲げ半径として曲げられる。
【００２２】
実施例１の芯型１０を用いた上記の方法によれば、中空形材１の湾曲部４において、外向き湾曲面２は、その中空部の両側面５，５に対向して配設された湾曲型材１３，１３のそれぞれの湾曲面２ａによって拘束されるので、設計され弧線Ｂに沿って曲げられ、偏平化することがない。また、積層型材１２が芯型１０の幅方向に湾曲型材１３，１３に挟まれて配設されているので、芯型１０の外向き湾曲面２に対する拘束力と内向き湾曲面３に対する拘束力が均衡して中空形材１の亀裂などが生じ難くなる。
【００２３】
更に、内向き湾曲面３およびその近傍の側面は、湾曲部４において、外側からローラ溝３４によって、また内側から、湾曲しても高さＨが変わらない積層型材１２によって拘束されるので、ローラ溝３４の湾曲に沿って曲げられ、シワなどの変形が生じることがない。
【００２４】
中空形材１の側面は、外側からローラ溝３４の側面とクランプ溝３６の側面とによって、また内側から湾曲型材１３の側面５ａ，５ａによって拘束されているので、シワや撓みなどの変形が生じることがない。
【００２５】
上記の作用によって、中空形材１の湾曲部４においては、その外向き湾曲面２とその近傍の側面が、シワや亀裂を発生することなく必要な分量だけ延伸され、内向き湾曲面３とその近傍の側面にもシワなどの変形が生じることなく、湾曲部４においても非湾曲部と同様の横断面形状が維持される。
【００２６】
図１に示した上記実施例１において、湾曲型材１３，１３の厚さｄは、芯型１０全体の幅Ｄの１５％ないし３５％の範囲内とすることが好ましい。実験の結果、ｄ／Ｄの比率が１５％未満では、湾曲型材１３の湾曲面２ａによる変形防止効果が不十分で、湾曲部４の横断面に変形が生じ易くなり、また３５％を越えると、内向き湾曲面３近傍における無拘束空間が増大するとともに外向き湾曲面２における拘束力が過大となって、外向き湾曲面近傍の伸長に対して素材の延展性が対応できず変形や亀裂が生じ易くなることがわかった。
【００２７】
湾曲型材１３，１３の厚さｄと芯型１０の幅Ｄとの比ｄ／Ｄを変化させて曲げ加工を行ったときの、曲げ加工後の湾曲部の状態を観察した試験例を以下に示す。この試験では、アルミニウム合金押出し形材を、内向き曲げ半径１５０ｍｍに曲げ加工した。湾曲型材厚さｄ（ｍｍ）と芯型幅Ｄ（ｍｍ）、その比（ｄ／Ｄ）および曲げ加工後の湾曲部の状態（結果）を表１に示す。
【００２８】
【表１】

【００２９】
表１の結果から、ｄ／Ｄの値が１５％ないし３５％の範囲内できわめて良好な横断面形状を有する湾曲部が得られたことがわかる。
【００３０】
曲げられた後の湾曲部４からこの芯型１０を取り出すには、単に挿入棒１４とともに芯型１０を引き抜けばよい。この際、湾曲型材１３は中空形材１の直管部の延長線上にあるので、引き抜きの抵抗にならない。また積層部１２は、湾曲部４内で全体として曲げられているが、積層されたそれぞれの可撓性板材１１ａ〜１１ｎが引き抜きに際して平板状態に戻るので、これらも引き抜きの障害にならず、容易に取り出すことができる。
【００３１】
（実施例２）
図４に、実施例１において示したものと同様な中空形材１を曲げるために用いる芯型の他の実施例を示す。図４において、この芯型２０は、中空形材１の外向き湾曲面２の設計された曲げ半径と等しい曲げ半径の曲面２ａを有する湾曲型材２３，２３と、外向き湾曲面２と内向き湾曲面３との間に積層されて中空形材１の長さ方向に延びる複数の可撓性板材２１ａ，２１ｂ，…，２１ｎからなる積層型材２２とから構成されている。
【００３２】
この芯型２０の横断面形状は長方形であって、その高さと幅の寸法は、これを中空形材１の中空部に許容し得るクリアランスを持って挿入し得る値とされている。ここでは説明のため、クリアランスを無視して、芯型１０の横断面の高さをＨ、幅をＤと表記する。
【００３３】
この芯型２０は、双方の側面５ａ，５ａに湾曲型材２３，２３が配設され、積層型材２２は、これらの湾曲型材２３，２３に挟まれて配設されている。そして実施例２の芯型２０においては、それぞれの湾曲型材２３の厚さが、湾曲部の外向き湾曲面２側の厚さｄ１から内向き湾曲面３側の厚さｄ２に向かって漸次縮小され、一方、積層型材２２の幅は、湾曲部の外向き湾曲面２側の幅ｗ１から内向き湾曲面３側の幅ｗｎに向かって漸次拡大されて、芯型２０全体として一定の幅Ｄが維持されるようになっている。この積層型材２２の幅の変化は、積層された板材２１ａ，２１ｂ，…，２１ｎのそれぞれの幅ｗ１，ｗ２，…，ｗｎを段階的に順次拡大することによって達成される。
【００３４】
芯型２０は、中空形材１の中空部の横断面形状に等しい横断面形状を有するので、実施例１の芯型１０と同様にして中空形材１内に挿入することができる。芯型２０を挿入した中空形材１は、実施例１と同様にして回転式曲げ加工機３０を用いて曲げ加工を行うことができる。
【００３５】
実施例２の芯型２０を用いれば、曲げ加工に際して、芯型の両側面５ａ，５ａをなす湾曲型材２３，２３が、これに挟まれた積層型材２２を内向き湾曲面３の方向に押圧するように作用するため、積層型材２２による内向き湾曲面３への拘束力が強まり、内向き湾曲面３とその近傍の側面におけるシワを防止する効果が更に高められる。一方、外向き湾曲面２とその近傍の側面においては、積層型材２２が内向き湾曲面３の方向に押圧されることによって芯型２０の外向き湾曲面側の幅Ｄがわずかに縮小し、このため型の拘束力が若干弱まり、無理な伸長が抑制され、亀裂を防止する効果が更に高められる。
【００３６】
（実施例３）
本発明の芯型は、異形横断面の中空形材の曲げ加工にも適用することができる。その一例を実施例３として図５に示す。図５は、段差を有する異形横断面の中空形材６と、これを曲げるために挿入された芯型２５の横断面を示している。この中空形材６は、それぞれ段差が設けられた外向き湾曲面６１，６２と、内向き湾曲面６３と、側面６４ａ，６４ｂ，６４ｃとによって形成されている。
【００３７】
図５に示す芯型２５は、中空形材６のそれぞれ側面６４ａ，６４ｂ，６４ｃに対向する位置に湾曲型材２６，２６，２６が配設され、芯型２５の幅方向に湾曲型材２６，２６，２６に挟まれて積層型材２７，２７が配設されてなっている。それぞれの湾曲型材２６は、図示しないが、外向き湾曲面の設計された曲げ半径と等しい曲げ半径の曲面を有している。また、それぞれの積層型材２７は、それぞれ外向き湾曲面６１，６２と内向き湾曲面６３との間に積層されて中空形材６の長さ方向に延びる複数の可撓性板材２８，２８，…からなっている。
【００３８】
この芯型２５を用いて前記の中空形材６を曲げる方法の一例を、以下に示す。この方法では、実施例１の場合に用いたものと同様の回転式曲げ加工機３０を使用する。ただし、搬送台３１の受け面とクランプ溝３６の横断面形状を、前記の中空形材６の外向き湾曲面６１，６２およびその近傍の側面を外側から拘束することができる形状に変更する。
【００３９】
中空形材６を回転式曲げ加工機３０の搬送台３１に定置し、前記の芯型２５を出し入れ自在の挿入棒の先端に固定して、中空形材６の後部開口から湾曲部の位置まで挿入する。この際、湾曲型材２６の曲面が、曲げようとする中空形材１の外向き湾曲面に対向するように挿入する。
【００４０】
次に湾曲部の先端部をローラ溝３４とクランプ溝３６との間に、内向き湾曲面３をローラ溝３４側として挟んで固定する。この状態でローラ部材３２とクランプ部材３３とを一緒に中空形材６の搬送方向に回転すると、中空形材６は、後方の直管部が搬送台３１によって拘束されているため、ローラ溝３４の曲げ半径を内向き湾曲面の曲げ半径として曲げられる。
【００４１】
実施例３の芯型２５を用いた上記の方法によれば、中空形材６の湾曲部において、外向き湾曲面６１，６２とその近傍の側面は、外側からクランプ溝３６によって、また内側から、中空部の各側面６４ａ，６４ｂ，６４ｃに配設された湾曲型材２６，２６，２６によって拘束されるので、設計された弧線通りに曲げられ、変形、亀裂などが生じることがない。
【００４２】
また、内向き湾曲面６３とその近傍の側面は、外側からローラ溝３４によって、また内側から、湾曲しても高さが変わらない積層型材２８，２８によって拘束されているので、設計された内向き湾曲面通りに成形され、シワなどの変形が生じることがない。
【００４３】
上記の作用によって、異形横断面の中空形材６の湾曲部においても、外向き湾曲面６１，６２とその近傍の側面が偏平化などの変形や亀裂を生じることなく必要な分量だけ延伸され、内向き湾曲面６３とその近傍の側面にシワなどの変形が生じることなく、湾曲部においても非湾曲部と同様の横断面形状が保持される。
【００４４】
本発明の芯型において、積層型材を構成する可撓性板材は、中空形材の湾曲部で曲げ加工時および芯型の抜き取り時に、長さ方向に屈曲し得る材質のものであればよいので、例えば銅板、鉛板、アルミニウム板など反発弾性の小さいものであってもよく、また鋼板、プラスチック板など反発弾性の大きいものであってもよい。また、特に中空形材の側面と対向する位置に配設された湾曲型材は、曲げ加工時に中空形材に鋭い切り込みを生じないように、その角部（稜線部分）を丸めて成形することが好ましい。
【００４５】
以上、実施例１〜実施例３で説明した芯型は、横断面角形の中空形材を曲げる際に用いられるものであるが、本発明の芯型が適用できる中空形材はこれに限定されるものではない。例えば横断面形状が台形、円形または楕円形などの中空形材であっても、これに挿入する芯型の横断面形状を全体として台形、円形または楕円形などに成形しておけば、同様に横断面形状に変形、シワ、亀裂などのない湾曲部を形成することができる。また、外側の周面に、長さ方向に延びるフィンや周方向に延びるフランジなどが一体に成形された中空形材を曲げる場合にも、本発明の芯型は有利に使用することができる。更に、本発明の芯型は、横断面コ字状または樋状など、長さ方向に解放縁部がある形材を曲げる際にも適用することができる。
【００４６】
本発明の芯型を用いて中空形材を曲げれば、湾曲部における剛性劣化が防止され、また横断面形状が非湾曲部と変わらないので、本発明の芯型は、自動車など輸送機器の中空構造部材や各種導管などの湾曲部の形成に好適に使用できるばかりでなく、中空の建築部材、家具部材、配線・配管部材などの曲げ加工にも用いることができる。
【００４７】
【発明の効果】
本発明の中空形材の曲げ加工用芯型は、外向き湾曲面の設計された曲げ半径と等しい曲げ半径の曲面を有する湾曲型材と、外向き湾曲面と内向き湾曲面との間に積層されて中空形材の長さ方向に延びる複数の可撓性板材からなる積層型材とから構成されたものであるので、これを用いて中空形材を曲げれば、湾曲部における中空部が内側から拘束されるので横断面形状が変化せず、湾曲部のシワ、変形、亀裂などが防止される。
【００４８】
前記において、積層型材が芯型の幅方向に湾曲型材に挟まれて配設されていれば、芯型の外向き湾曲面に対する拘束力と内向き湾曲面に対する拘束力が均衡して中空形材の亀裂などが生じ難くなる。
【００４９】
このとき湾曲型材が、芯型の少なくとも側面に配設されていれば、外向き湾曲面とその近傍の側面が湾曲型材によって拘束されるので、外向き湾曲面が設計された弧線に沿って曲げられ、偏平化することがない。
【００５０】
また、芯型の側面に配設された湾曲型材の少なくとも外向き湾曲面側の厚さが、芯型全体の幅の１５％ないし３５％の範囲内とされていれば、湾曲部に発生するシワ、変形、亀裂などが更に軽減される。
【００５１】
前記において、湾曲型材が芯型のそれぞれの側面に配設され、積層型材が湾曲型材に挟まれて配設され、それぞれの前記湾曲型材の厚さが外向き湾曲面側から内向き湾曲面側に向かって漸次縮小され、かつ積層型材の厚さが外向き湾曲面側から内向き湾曲面側に向かって漸次拡大されていれば、内向き湾曲面が強く拘束され、外向き湾曲面とその近傍の側面における拘束力が比較的緩和されるので、内向き湾曲面とその近傍の側面におけるシワ、外向き湾曲面とその近傍の側面における亀裂を防止する効果が更に高められる。
【図面の簡単な説明】
【図１】本発明の一実施例を示す横断斜視図。
【図２】本発明を適用する中空形材の一例を示す横断斜視図。
【図３】本発明の一適用例を示す部分縦断側面図。
【図４】本発明の他の一実施例を示す横断斜視図。
【図５】本発明の更に他の一実施例を示す横断斜視図。
【図６】従来の芯型の適用例を示す部分縦断側面図。
【図７】従来の他の芯型の適用例を示す部分縦断側面図。
【符号の説明】
２ａ ……曲面
１０……芯型
１１ａ，１１ｂ，１１ｎ ……可撓性板材
１２……積層型材
１３……湾曲型材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a core for bending a hollow shape, and in particular, when bending the hollow shape using a rotary bending machine or the like, such as wrinkles, deformation, cracks, etc. in the curved portion. The present invention relates to a core for bending a hollow profile that can be prevented from occurring.
[0002]
[Prior art]
It is important to reduce the weight of transportation equipment such as automobiles from the viewpoint of saving energy and preserving the global environment. As one solution, engines, structural members, various conduits, body skins, etc. are made of aluminum. It is becoming manufactured with alloys. When an aluminum alloy is used as a structural member such as a frame, a hollow shape having a square cross section that is lightweight and excellent in specific rigidity is often used. Many of these structural members and various conduits are formed into a shape that is two-dimensionally or three-dimensionally curved in the length direction. One method for forming a curved hollow member is to mold using a split mold. However, if a hollow shaped material previously formed into a straight tube by extrusion can be bent and formed by post-processing, the production efficiency can be improved. It is often advantageous both in terms of surface and strength.
[0003]
However, for example, if a hollow section having a rectangular cross section is bent as it is, the outward curved surface (the surface with the larger bending radius) is stretched and the inward curved surface (the surface with the smaller bending radius) is compressed. In extreme cases, the side surface is bent, the hollow part of the curved part is deformed flat, and the outward curved surface or the side surface in the vicinity thereof is cracked, or the inward curved surface or the side surface in the vicinity thereof is wrinkled. Causes problems such as breaking at the curved portion.
[0004]
One way to solve this problem is to insert the core mold into the curved part so that the cross-sectional shape of the curved part of the hollow profile does not change, and then bend it to flatten the tube or A method for preventing the occurrence is employed. Conventionally, there are two known core types used for this purpose, a curved core type and a laminated core type.
[0005]
FIG. 6 shows an example of a method for bending a hollow shape using a curved core mold among conventional core molds.
In FIG. 6, the code | symbol 1 has shown the hollow shape material of a cross section rectangle. The hollow member 1 is made of an aluminum alloy and is a member formed into a straight tube shape by extrusion.
[0006]
Reference numeral 30 indicates a rotary bending machine as a whole. The rotary bending machine 30 is roughly composed of a conveyance table 31, a roller member 32, and a clamp member 33. The conveyance stand 31 is a device that places the hollow profile 1 and conveys it along the outer periphery of the roller member 32 (from right to left in the figure). The roller member 32 is a cylindrical body having a roller groove 34 that receives the inwardly curved surface 3 of the hollow shape member 1, and a rotation driving device (not shown) connected to the shaft core 35 of the transport base 31. It rotates in a direction that coincides with the transport direction. The bending radius of the roller groove 34 coincides with the designed bending radius of the inwardly curved surface 3 of the hollow profile 1. The clamp member 33 is connected to the rotation shaft 35 of the roller member by a post (not shown), and rotates together with the roller member 32. The clamp member 33 has a clamp groove 36 for receiving the hollow member 1. The clamp member 33 sandwiches the hollow member 1 between the clamp groove 36 and the roller groove 34 and presses the hollow member 1. The tip of the portion to be curved (curved portion) is fixed to the roller groove 34, and the deformation of the cross-sectional shape of the hollow shape material in the curved portion is constrained from the outside.
[0007]
The curved core mold 40 used here is generally a rectangular parallelepiped having a cross-sectional shape that can be inserted into the hollow portion of the hollow shape member 1, but the curved portion is inserted in the hollow portion of the hollow shape member 1. The surface 42 on the side of the outward curved surface 2 is formed into a curved surface having a bending radius equal to the designed bending radius of the outward curved surface 2, and the curved surface 42 is formed at the tip of the curved core die 40. It abuts against the opposing flat surface 43.
[0008]
First, the hollow shape member 1 is placed on the transport base 31 of the rotary bending machine 30, and the curved core die 40 fixed to the tip of the insertion rod 41 that can be freely inserted and removed is inserted from the opening at the rear end thereof. Place inside. Next, the front end of the curved portion of the hollow shape member 1 is fixed between the roller groove 34 and the clamp groove 36. When the roller member 32 and the clamp member 33 are rotated together by the driving force of the rotary shaft 35 in this state, the hollow profile 1 is bent with the bending radius of the roller groove 34 as the bending radius of the inwardly curved surface 3. At this time, the outward curved surface 2 of the hollow shape member 1 is constrained from the inside by the curved core die 40, so that a constant hollow portion cross-sectional shape is maintained even in the curved portion without being flattened. become.
[0009]
Another example of a conventional core type is a laminated core type. FIG. 7 shows an example of a method of bending a hollow shape using this laminated core mold.
In FIG. 7, the code | symbol 1 has shown the hollow shape material of a cross section rectangle. Reference numeral 30 indicates a rotary bending machine similar to the above as a whole.
[0010]
In this case, the laminated core mold 50 is attached to and inserted into the distal end of the insertion rod 51 that can be freely inserted and removed, inside the curved portion of the hollow shape member 1. The laminated core mold 50 is formed by laminating a plurality of

plate members

51, 51,... Made of a rectangular flexible material, and the cross-sectional shape of the laminated portion can be inserted into the hollow portion of the hollow shape member 1. It is said that.
[0011]
In order to bend the hollow profile 1 using the laminated core mold 50, first, the hollow profile 1 is placed on the transport base 31 of the rotary bending machine 30, and the hollow profile 1 is placed in the hollow portion of the straight tubular profile 1. The laminated core die 50 is inserted and pushed into the curved portion with the insertion rod 51, and the distal end of the curved portion of the hollow shape member 1 is sandwiched and fixed between the roller groove 34 and the clamp groove 36. When the roller member 32 and the clamp member 33 are rotated together by the driving force of the rotary shaft 35 in this state, the hollow profile 1 is bent with the bending radius of the roller groove 34 as the bending radius of the inwardly curved surface 3. At this time, the laminated core die 50 inside the hollow shape member 1 also bends while the

plate members

51, 51,... Are displaced from each other in the traveling direction, and the cross-sectional shape of the laminated core die 50 does not change even if it is curved. Therefore, the hollow member 1 is also restrained from the inside by the laminated core die 50, and the cross-sectional shape of the hollow part is maintained constant without being flattened in the curved part.
[0012]
[Problems to be solved by the invention]
However, each of the conventional methods using the curved core mold 40 or the laminated core mold 50 has problems, and it has been difficult to obtain a curved portion substantially free from defects such as deformation, wrinkles, and cracks. That is, when the curved core die 40 is used, when the hollow profile 1 is bent by the rotary bending machine 30, the inward curved surface 3 of the hollow profile 1 cannot be constrained. And the side surface in the vicinity thereof is easily compressed and wrinkled. On the other hand, when the laminated core mold 50 is used, if the cross-sectional shape of the laminated portion is matched with the cross-sectional shape of the hollow portion of the hollow shape member 1, it cannot be pulled out from the hollow shape member 1 after being bent. Therefore, it is necessary to mold the hollow portion 1 slightly smaller than the cross-sectional dimension of the hollow portion. Therefore, the entire circumference of the bending portion cannot be constrained during bending, and the cross-sectional shape changes such as flattening in the bending portion. Will be caused.
[0013]
The present invention has been made in order to solve the above-described problems. Therefore, the object of the present invention is to generate deformation, wrinkles, cracks, etc. of the hollow shape material in the curved portion when bending the hollow shape material. An object of the present invention is to provide a core for bending a hollow shape member capable of preventing the above-described problem.
[0014]
[Means for Solving the Problems]
The above problem is bent equal bending radii are designed in the outward curved surface have a radius of the curved surface, the curved-type material is disposed on at least side surfaces of the core type, an outward curved surface and inwardly curved surface This can be solved by providing a bending core die that is composed of a plurality of flexible plate members that are laminated between each other and extend in the length direction of the hollow shape member. It is preferable that the laminated mold material is disposed between the curved mold materials in the width direction of the core mold . Also, at least the outward curved surface thickness of the curved member disposed on a side surface of the core type, which is preferably within the range of 35% by 15% of the core type total width.
[0015]
According to the present invention, in the above, the curved mold material is disposed on each side surface of the core mold, the laminated mold material is disposed between the curved mold materials, and the thickness of each curved mold material is determined from the outward curved surface side. Provided is a bending core die that is gradually reduced toward the inwardly curved surface side, and the thickness of the laminated mold material is gradually increased from the outwardly curved surface side toward the inwardly curved surface side.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, components that are common to the components described with reference to FIGS. 6 and 7 as conventional techniques are denoted by the same reference numerals, and description thereof is omitted or simplified.
The core for bending in this embodiment (hereinafter simply referred to as “core”) is used for bending a straight tubular hollow member. As shown in FIG. 2, the hollow shape member 1 has a rectangular shape in which the cross-sectional shape of the hollow portion has a height H and a width D. This hollow shape member 1 is planned to bend the outward curved surface 2 along the arc B in the direction of the height H in the curved portion 4. Therefore, after bending, one of the two surfaces forming the width D of the hollow portion 1 of the hollow shape member 1 becomes the outward curved surface 2 and the other becomes the inward curved surface 3. Further, the surfaces forming the height H of the hollow portion are the side surfaces 5 and 5, respectively.
[0017]
(Example 1)
FIG. 1 shows the tip of a core mold 10 used for bending the hollow profile 1.
A core mold 10 shown in FIG. 1 includes a curved mold 13 having a curved surface 2a having a bending radius equal to the designed bending radius of the outward curved surface 2 of the hollow profile 1, and the outward curved surface 2 and the inward curved surface 3. , 11n and a plurality of flexible plate members 11a, 11b,..., 11n.
[0018]
The cross-sectional shape of the core mold 10 is rectangular, and the height and width dimensions thereof are values that can be inserted into the hollow portion of the hollow shape member 1 with an allowable clearance. Here, for the sake of explanation, the clearance is ignored, and the height of the cross section of the core mold 10 is expressed as H and the width as D.
[0019]
The core mold 10 is provided with

curved mold members

13 and 13 on both side surfaces 5 a and 5 a, and the laminated mold member 12 is disposed between the

curved mold members

13 and 13. The thickness d of the

curved mold members

13 and 13 is in the range of 15% to 35% of the width D of the entire core mold 10. Further, the end of the laminated mold 12 protrudes from the end of the curved mold 13 by a length L.
[0020]
Next, an example of a method for bending the hollow profile 1 using the core mold 10 will be described with reference to FIG. In this method, the rotary bending machine 30 described in the conventional example is used.
First, the hollow shape member 1 is placed on a transport base 31 of a rotary bending machine 30 (for example, “Drawbender” manufactured by Taiyo Co., Ltd.), and the core mold 10 is fixed to the distal end of a removable insertion rod 14. The hollow shape member 1 is inserted from the rear opening to the position of the curved portion 4. At this time, the curved surface 2a of the curved mold 13 is inserted so as to face the outward curved surface 2 of the hollow profile 1 to be bent.
[0021]
Next, the curved portion 4 is fixed by sandwiching the tip portion of the curved portion 4 between the roller groove 34 and the clamp groove 36 with the inward curved surface 3 as the roller groove 34 side. In this state, when the roller member 32 and the clamp member 33 are rotated together in the conveying direction of the hollow member 1, the hollow member 1 has the straight straight tube portion constrained by the conveying table 31. Is bent as the bending radius of the inwardly curved surface 3.
[0022]
According to the above method using the core mold 10 of the first embodiment, in the curved portion 4 of the hollow shape member 1, the outward curved surface 2 is disposed to face both side surfaces 5 and 5 of the hollow portion. The

curved mold members

13 and 13 are constrained by the curved surfaces 2a of the

curved mold members

13, 13 so that they are designed and bent along the arc line B and are not flattened. In addition, since the laminated mold 12 is disposed between the

curved molds

13 and 13 in the width direction of the core mold 10, the constraint force on the outward curved surface 2 and the constraint force on the inward curved surface 3 of the core mold 10. Are not balanced and cracks of the hollow shape member 1 are less likely to occur.
[0023]
Further, the inwardly curved surface 3 and the side surface in the vicinity thereof are restrained by the roller groove 34 from the outside in the curved portion 4 and by the laminated mold material 12 whose height H does not change even when curved from the inside. It is bent along the curvature of the groove 34, and deformation such as wrinkles does not occur.
[0024]
Since the side surface of the hollow shape member 1 is constrained by the side surface of the roller groove 34 and the side surface of the clamp groove 36 from the outside and by the side surfaces 5a, 5a of the curved mold member 13 from the inside, deformation such as wrinkles and deflection occurs. There is nothing.
[0025]
Due to the above action, in the curved portion 4 of the hollow shape member 1, the outward curved surface 2 and the side surface in the vicinity thereof are extended by a necessary amount without generating wrinkles or cracks, and the inward curved surface 3 and A side cross-sectional shape similar to that of the non-curved portion is maintained in the curved portion 4 without causing deformation such as wrinkles on the side surface in the vicinity thereof.
[0026]
In the first embodiment shown in FIG. 1, the thickness d of the

curved mold members

13 and 13 is preferably in the range of 15% to 35% of the width D of the entire core mold 10. As a result of the experiment, when the ratio d / D is less than 15%, the deformation preventing effect by the curved surface 2a of the curved mold member 13 is insufficient, and the transverse section of the curved portion 4 is likely to be deformed, and when it exceeds 35%. The unconstrained space in the vicinity of the inwardly curved surface 3 increases, and the restraining force in the outwardly curved surface 2 becomes excessive, so that the extensibility of the material cannot cope with the elongation in the vicinity of the outwardly curved surface, and deformation or cracks It turned out that it becomes easy to occur.
[0027]
A test example in which the state of the curved portion after bending is observed when the bending is performed by changing the ratio d / D between the thickness d of the bending

mold members

13 and 13 and the width D of the core mold 10 is as follows. Show. In this test, an aluminum alloy extruded profile was bent to an inward bending radius of 150 mm. Table 1 shows the thickness d (mm) of the curved mold, the width D (mm) of the core mold, the ratio (d / D), and the state (result) of the curved portion after bending.
[0028]
[Table 1]

[0029]
From the results of Table 1, it can be seen that a curved portion having a very good cross-sectional shape was obtained when the d / D value was in the range of 15% to 35%.
[0030]
In order to take out the core mold 10 from the bent portion 4 after being bent, it is only necessary to pull out the core mold 10 together with the insertion rod 14. At this time, since the curved mold 13 is on the extension line of the straight pipe portion of the hollow profile 1, it does not become a resistance to pulling out. The laminated portion 12 is bent as a whole within the curved portion 4, but the laminated flexible plate members 11a to 11n return to the flat plate state when being drawn, so that they are not obstructed by the drawing and can be easily performed. Can be taken out.
[0031]
(Example 2)
FIG. 4 shows another embodiment of the core type used for bending the hollow profile 1 similar to that shown in the embodiment 1. In FIG. 4, the core mold 20 includes

curved mold members

23 and 23 having curved surfaces 2 a having a bending radius equal to the designed bending radius of the outward curved surface 2 of the hollow profile 1, and the outward curved surface 2 and the inward facing. It is comprised from the lamination | stacking type | mold material 22 which consists of several flexible board | plate materials 21a, 21b, ..., 21n laminated | stacked between the curved surfaces 3 and extended in the length direction of the hollow shape member 1. FIG.
[0032]
The cross-sectional shape of the core mold 20 is rectangular, and the height and width dimensions thereof are values that can be inserted into the hollow portion of the hollow shape member 1 with an allowable clearance. Here, for the sake of explanation, the clearance is ignored, and the height of the cross section of the core mold 10 is expressed as H and the width as D.
[0033]
The core mold 20 is provided with

curved mold members

23 and 23 on both side surfaces 5a and 5a, and the laminated mold member 22 is disposed between the

curved mold members

23 and 23. In the core mold 20 of the second embodiment, the thickness of each curved mold member 23 is gradually reduced from the thickness d1 on the outward curved surface 2 side of the curved portion toward the thickness d2 on the inward curved surface 3 side. On the other hand, the width of the laminated mold 22 is gradually increased from the width w1 on the outward curved surface 2 side of the curved portion toward the width wn on the inward curved surface 3 side, so that the core mold 20 as a whole has a constant width D. Is to be maintained. The change in the width of the laminated mold 22 is achieved by sequentially expanding the widths w1, w2,..., Wn of the laminated plate members 21a, 21b,.
[0034]
Since the core die 20 has a cross-sectional shape equal to the cross-sectional shape of the hollow portion of the hollow shape member 1, it can be inserted into the hollow shape member 1 in the same manner as the core die 10 of the first embodiment. The hollow shape member 1 in which the core mold 20 is inserted can be bent using the rotary bending machine 30 in the same manner as in the first embodiment.
[0035]
If the core mold 20 of the second embodiment is used, the bending

mold members

23 and 23 forming both side surfaces 5a and 5a of the core mold press the laminated mold member 22 sandwiched between them in the direction of the inward curved surface 3 during bending. Therefore, the binding force to the inwardly curved surface 3 by the laminated mold 22 is increased, and the effect of preventing wrinkles on the inwardly curved surface 3 and the side surfaces in the vicinity thereof is further enhanced. On the other hand, on the outward curved surface 2 and the side surface in the vicinity thereof, the width D on the outward curved surface side of the core mold 20 is slightly reduced by pressing the laminated mold material 22 in the direction of the inward curved surface 3. For this reason, the mold restraining force is slightly weakened, excessive stretching is suppressed, and the effect of preventing cracks is further enhanced.
[0036]
(Example 3)
The core mold of the present invention can also be applied to bending a hollow profile having an irregular cross section. An example thereof is shown in FIG. FIG. 5 shows a cross section of a hollow member 6 having a deformed cross section having a step and a core mold 25 inserted to bend it. The hollow member 6 is formed by outward

curved surfaces

61 and 62 provided with steps, an inward curved surface 63, and

side surfaces

64a, 64b and 64c.
[0037]
In the core mold 25 shown in FIG. 5, the

curved mold members

26, 26, 26 are arranged at positions facing the side surfaces 64 a, 64 b, 64 c of the hollow profile 6, respectively, and the

curved mold members

26, 26 are arranged in the width direction of the core mold 25. , 26 are provided with

laminated mold members

27, 27. Although not shown, each curved mold member 26 has a curved surface having a bending radius equal to the designed bending radius of the outward curved surface. Each of the laminated mold members 27 is laminated between the outwardly

curved surfaces

61 and 62 and the inwardly curved surface 63 and extends in the length direction of the hollow member 6. It consists of ...
[0038]
An example of a method for bending the hollow profile 6 using the core mold 25 will be described below. In this method, the same rotary bending machine 30 as that used in the first embodiment is used. However, the cross-sectional shape of the receiving surface of the conveyance base 31 and the clamp groove 36 is changed to a shape that can restrain the outward

curved surfaces

61 and 62 of the hollow shape member 6 and the side surfaces in the vicinity thereof from the outside.
[0039]
From the rear opening of the hollow shape member 6 to the position of the curved portion, the hollow shape member 6 is fixed on the transport base 31 of the rotary bending machine 30 and the core die 25 is fixed to the distal end of the insertion / removal rod. insert. At this time, the curved mold member 26 is inserted so that the curved surface thereof faces the outward curved surface of the hollow profile 1 to be bent.
[0040]
Next, the inwardly curved surface 3 is sandwiched between the roller groove 34 and the clamp groove 36 as the roller groove 34 side, and the tip of the curved portion is fixed. In this state, when the roller member 32 and the clamp member 33 are rotated together in the conveying direction of the hollow member 6, the straight member of the hollow member 6 is restrained by the conveying table 31, so that the roller groove 34. Is bent as the bending radius of the inwardly curved surface.
[0041]
According to the above method using the core mold 25 of the third embodiment, in the curved portion of the hollow shape member 6, the outward

curved surfaces

61 and 62 and the side surfaces in the vicinity thereof are clamped from the outside by the clamp groove 36 and from the inside. Since it is restrained by the

curved mold members

26, 26, 26 disposed on the side surfaces 64a, 64b, 64c of the hollow portion, it is bent according to the designed arc line, and deformation, cracks, etc. do not occur.
[0042]
Further, the inwardly curved surface 63 and the side surface in the vicinity thereof are constrained by the roller groove 34 from the outside, and from the inside by the

laminated mold members

28 and 28 whose height does not change even if curved, so that the designed inner It is shaped according to the direction of the curved surface, and deformation such as wrinkles does not occur.
[0043]
By the above action, even in the curved portion of the hollow shape member 6 having an irregular cross section, the outward

curved surfaces

61 and 62 and the side surfaces in the vicinity thereof are stretched by a necessary amount without causing deformation or cracking such as flattening, The inward curved surface 63 and the side surface in the vicinity thereof are not deformed such as wrinkles, and the same cross-sectional shape as that of the non-curved portion is maintained in the curved portion.
[0044]
In the core mold of the present invention, the flexible plate material constituting the laminated mold material may be any material that can be bent in the length direction at the time of bending at the curved portion of the hollow shape material and when the core mold is extracted. For example, a copper plate, a lead plate, an aluminum plate or the like having a small impact resilience may be used, and a steel plate or a plastic plate having a large impact resilience may be used. Further, in particular, a curved mold disposed at a position facing the side surface of the hollow profile may be formed by rounding its corners (ridge lines) so that the hollow profile is not sharply cut during bending. preferable.
[0045]
As described above, the core mold described in Examples 1 to 3 is used when bending a hollow section having a square cross section, but the hollow mold to which the core mold of the present invention can be applied is limited to this. It is not something. For example, even if the cross-sectional shape is a trapezoidal shape, a circular shape or an elliptical shape, if the core-shaped cross-sectional shape to be inserted is formed into a trapezoidal shape, a circular shape or an oval shape as a whole, the same A curved portion free from deformation, wrinkles, cracks or the like can be formed in the cross-sectional shape. The core mold of the present invention can also be advantageously used when bending a hollow shape in which a fin extending in the length direction, a flange extending in the circumferential direction, and the like are integrally formed on the outer peripheral surface. Furthermore, the core mold of the present invention can also be applied when bending a shape having a release edge in the length direction, such as a U-shaped cross section or a bowl shape.
[0046]
If the hollow shape member is bent using the core mold of the present invention, the deterioration of rigidity in the curved portion is prevented, and the cross-sectional shape is not different from that of the non-curved section. Therefore, the core mold of the present invention is used for transportation equipment such as automobiles. Not only can it be used suitably for the formation of curved parts such as hollow structural members and various conduits, but it can also be used for bending of hollow building members, furniture members, wiring / pipe members and the like.
[0047]
【The invention's effect】
The hollow core bending mold of the present invention includes a curved mold having a curved surface having a bending radius equal to the designed bending radius of the outward curved surface, and a laminate between the outward curved surface and the inward curved surface. Since the hollow shape material is bent using this, the hollow portion in the curved portion is formed on the inner side. Therefore, the cross-sectional shape does not change and wrinkles, deformation, cracks, etc. of the curved portion are prevented.
[0048]
In the above, if the laminated mold material is disposed so as to be sandwiched between the curved mold materials in the width direction of the core mold, the restraining force for the outward curved surface of the core mold and the restraining force for the inward curved surface are balanced, so Cracks are less likely to occur.
[0049]
At this time, if the curved mold material is disposed on at least the side surface of the core mold, the outward curved surface and the side surface in the vicinity thereof are constrained by the curved mold material, so that the outward curved surface is bent along the designed arc line. And is not flattened.
[0050]
Moreover, if the thickness of at least the outward curved surface side of the curved mold member disposed on the side surface of the core mold is within the range of 15% to 35% of the entire width of the core mold, the curved section is generated in the curved portion. Wrinkles, deformation, cracks, etc. are further reduced.
[0051]
In the above, the curved mold material is disposed on each side surface of the core mold, the laminated mold material is disposed between the curved mold materials, and the thickness of each curved mold material is from the outward curved surface side to the inward curved surface side. And the thickness of the laminated mold is gradually increased from the outward curved surface side to the inward curved surface side, the inward curved surface is strongly restrained, and the outward curved surface and its Since the restraining force on the side surfaces in the vicinity is relatively relaxed, the effect of preventing cracks in the inward curved surface and the side surfaces in the vicinity thereof, and cracks in the outward curved surface and the side surfaces in the vicinity thereof is further enhanced.
[Brief description of the drawings]
FIG. 1 is a transverse perspective view showing an embodiment of the present invention.
FIG. 2 is a transverse perspective view showing an example of a hollow member to which the present invention is applied.
FIG. 3 is a partially longitudinal side view showing an application example of the present invention.
FIG. 4 is a cross-sectional perspective view showing another embodiment of the present invention.
FIG. 5 is a transverse perspective view showing still another embodiment of the present invention.
FIG. 6 is a partially longitudinal side view showing an application example of a conventional core type.
FIG. 7 is a partially longitudinal side view showing another conventional core type application example.
[Explanation of symbols]
2a: Curved surface 10: Core mold 11a, 11b, 11n: Flexible plate 12: Laminated mold 13: Curved mold

Claims

When bending a hollow shape member, the core shape is used by being inserted into a curved portion formed by an outwardly curved surface, an inwardly curved surface and a side surface of the hollow portion of the hollow shape material, and the outwardly curved surface A curved mold having a curved surface having a bending radius equal to the designed bending radius, and a plurality of flexible plates stacked between the outward curved surface and the inward curved surface and extending in the length direction of the hollow profile. A hollow core bending core characterized in that it is disposed on at least a side surface of a core mold in which the curved mold material is combined .

The core for bending a hollow profile according to claim 1, wherein the laminated mold is disposed between the curved mold in the width direction of the core.

The thickness of at least the outward curved surface side of the curved mold member disposed on the side surface of the core mold is set within a range of 15% to 35% of the width of the entire core mold. Core type for bending hollow shape materials.

A curved mold material is disposed on each side surface of the core mold, a laminated mold material is disposed between the curved mold materials, and the thickness of each curved mold material is from the outward curved surface side toward the inward curved surface side. 2. The core for bending a hollow shape member according to claim 1, wherein the core is gradually reduced and the thickness of the laminated mold is gradually increased from the outward curved surface side toward the inward curved surface side. .