JP2004141904A

JP2004141904A - Method and device of forming with hydraulic press

Info

Publication number: JP2004141904A
Application number: JP2002308148A
Authority: JP
Inventors: Hakushin Izeki; 井関　博進; Kiyoto Kondo; 近藤　清人
Original assignee: Aisin Takaoka Co Ltd
Current assignee: Aisin Takaoka Co Ltd
Priority date: 2002-10-23
Filing date: 2002-10-23
Publication date: 2004-05-20

Abstract

PROBLEM TO BE SOLVED: To integrally form a shape having high degree of complexity which is unformable by conventional spinning methods at a low cost and in a short time without producing weld defects. SOLUTION: A movable die 21 on which a main shape imparting part 22 is provided and a fixed die 23 on which an auxiliary shape imparting part 24 which cooperates with the main shaping part and a length adjusting part 25 continuing to the auxiliary shape imparting part are provided are prepared. A metallic pipe 10 the inside of which is filled with a liquid is arranged between both the dies 21, 23 and also press forming is performed with both dies. In this way, such a shape that a part pressed between the main shape imparting part 22 and the auxiliary shape imparting part 24 is declinate or off-centered to the other part is imparted to the metallic pipe 10 while preventing the generation of product defects (wrinkles, for example) on a side where pressing is performed with the main shape imparting part 22 on the basis of finishing action of the pipe wall with the length adjusting part 25 and on the other side. COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、中空金属製品の液圧プレス成形方法と、液圧プレス成形装置とに関するものである。
【０００２】
【従来の技術】
従来、ワークとしての金属管の端部に複雑な形状を付与する方法としてスピニング加工法が知られている。例えば、金属素管の管軸とスピニング加工用ロールの公転軸とを偏芯させた状態でスピニング加工を施すことにより、素管部の管軸に対して偏芯し且つ素管部と一体的な偏芯縮径部を成形する方法が提案されている（特許文献１参照）。また、金属素管の管軸とスピニング加工用ロールの公転軸とを傾斜させた状態でスピニング加工を施すことにより、素管部の管軸に対して傾斜し且つ素管部と一体的な偏角縮径部を成形する方法が提案されている（特許文献２参照）。
【０００３】
【特許文献１】
特許第２９５７１５３号（特許請求の範囲）
【特許文献２】
特許第２９５７１５４号（特許請求の範囲）
【０００４】
【発明が解決しようとする課題】
しかしながら、上述のようなスピニング加工法にも欠点がある。まず、金属素管の端部外周に押し当てる複数のロールを同素管の管軸に対して偏芯又は偏角させた状態で相対公転させるための機構を備えたスピニング加工設備が必要となるが、そのような設備は複雑且つ高価である。また、スピニング加工は金属素管の管端を段階的に絞る逐次絞り加工であることから、一工程での絞り量を多くすると割れや減肉等の製品欠陥が生じやすい。このため、一工程での絞り量を少量にとどめ複数の絞り工程を経る必要があり、加工時間が長くなる傾向にある。
【０００５】
更には、上記偏芯・偏角スピニング加工で成形できる形状には限界がある。即ちスピニング加工は本質的に素管の外側から内側に向けての回転絞り加工であるため、例えば金属素管の外径を超えて外側に張り出すような偏芯・偏角形状や、中心となる軸に対して回転対称性のない形状（例えば円以外の断面形状）などのように更に複雑度の高い形状を一体成形することができない。
【０００６】
本発明の目的は、従来のスピニング加工では成形不可能であったような複雑度の高い形状をも、製品欠陥を伴うことなく安価に且つ短時間に一体成形可能な中空金属製品の液圧プレス成形方法を提供することにある。また、その成形方法の実施に適した液圧プレス成形装置を提供することにある。
【０００７】
【課題を解決するための手段】
請求項１の発明は、主付形部が設けられた第１プレス型と、該第１プレス型の主付形部と協働する副付形部及びその副付形部に連なる線長調整部が設けられた第２プレス型からなる成形装置を準備する工程と、前記成形装置の第１及び第２プレス型間に保持した中空な金属素材内に液体を満たす工程と、内部に液体が満たされた金属素材を前記第１及び第２プレス型でプレス成形する工程とを備え、前記線長調整部による金属素材壁部の整形作用に基づいて前記主付形部が押圧する側と反対側において製品欠陥が発生するのを防止しつつ、前記金属素材に対し、第１プレス型の主付形部と第２プレス型の副付形部との間でプレスされた部位が他部位に対して偏角及び／又は偏芯するような形状を付与することを特徴とする中空金属製品の液圧プレス成形方法である。
【０００８】
この方法によれば、内部に液体が満たされた金属素材を第１及び第２プレス型でプレス成形することにより、当該金属素材に対し、第１プレス型の主付形部と第２プレス型の副付形部との間でプレスされた部位が他部位に対して偏角及び／又は偏芯するような形状が付与される。そして、第２プレス型には副付形部と連なる線長調整部が設けられているため、偏角及び／又は偏芯形状付与を目的としたプレス成形に際しても、線長調整部による金属素材壁部の整形作用に基づき、前記主付形部が押圧する側と反対側において被押圧物（中空金属素材）にシワや座屈などの製品欠陥が発生するのを防止することができる。つまり、この方法によれば、従来のスピニング加工では成形不可能であったような複雑度の高い形状をも、シワや座屈などの製品欠陥を伴うことなく安価に且つ短時間に一体成形可能となる。
【０００９】
請求項２の発明は、請求項１に記載の中空金属製品の液圧プレス成形方法において、前記プレス工程で得られたプレス成形品から前記線長調整部に対応する部位を切り離すことにより、製品の端部又はその近傍に所望の偏角及び／又は偏芯形状を有する中空金属製品を得ることを特徴とする。
【００１０】
この方法によれば、プレス工程で得られたプレス成形品から不要な部位（線長調整部に対応する部位）を切断して取り除くことにより、製品の端部又はその近傍に所望の偏角及び／又は偏芯形状を有する中空金属製品が得られる。
【００１１】
請求項３の発明は、請求項１又は２に記載の中空金属製品の液圧プレス成形方法において、前記中空な金属素材は、パイプ状の本体部と、その本体部の径よりも小径な縮径部とを有する金属パイプであり、前記金属パイプ縮径部の表面の長手方向線長と、前記プレス工程で得られるプレス成形品のうちの前記第２プレス型の副付形部及び線長調整部によって付形及び整形される部位の長手方向における線長とが一致又は近似するように、前記第２プレス型の形状又は前記金属パイプの形状が設定されていることを特徴とする。
【００１２】
この方法によれば、第１プレス型の主付形部が金属パイプの縮径部を引き延ばし加減で押圧しても、前記主付形部が押圧する側と反対側（即ち副付形部及び線長調整部によって受け止められる側）において被押圧物（金属パイプ）にシワや座屈などの製品欠陥が発生することが確実に回避される。
【００１３】
請求項４の発明は、請求項３に記載の中空金属製品の液圧プレス成形方法において、前記金属パイプ縮径部の表面の長手方向線長と、前記プレス工程で得られるプレス成形品のうちの前記第１プレス型の主付形部によって付形される部位の長手方向における最大線長とが一致又は近似するように、前記第１プレス型の形状又は前記金属パイプの形状が設定されていることを特徴とする。
【００１４】
この方法によれば、第１プレス型の主付形部によって押圧される金属パイプの被押圧部位が過度に減肉されたり割れたりすることが確実に回避される。
【００１５】
請求項５の発明は、請求項１〜４のいずれかに記載の中空金属製品の液圧プレス成形方法において、前記第１及び第２のプレス型並びにこれら両プレス型間に保持される中空な金属素材は、前記線長調整部を中心として左右対称形状に構成されており、前記プレス工程を経て、製品の端部又はその近傍に所望の偏角及び／又は偏芯形状を有する中空金属製品が二個同時に得られることを特徴とする。この方法によれば、１回のプレス成形で所望の中空金属製品を二個同時に得ることができ、生産性が向上する。
【００１６】
なお、請求項１〜５において、「前記第１及び第２プレス型の少なくとも一方に、金属素材の本来の断面形状とは異なる異形断面形状を金属素材に付与するための付形部位、又は、金属素材の一部に局部的な凹凸形状を付与するための付形部位が設けられていること」は好ましい。この場合には、中空金属製品に所望の偏角及び／又は偏芯形状を付与する際に、異形断面形状や局部的な凹凸形状を併せて付与することが可能となり、生産性が向上する。
【００１７】
請求項６の発明は、中空な金属素材内に満たした液体の液圧を調整する液圧調整手段と、相対接近離間可能な第１及び第２のプレス型からなるプレス成形手段とを備えた液圧プレス成形装置であって、前記第１プレス型には、液体を満たした金属素材を押圧して形状を付与するための主付形部が設けられ、前記第２プレス型には、第１プレス型の主付形部と協働する副付形部、及び、その副付形部に連なると共に第１及び第２プレス型によるプレス成形時に前記主付形部が押圧する側と反対側において製品欠陥が発生するのを防止するための線長調整部が設けられていることを特徴とする液圧プレス成形装置である。
【００１８】
この装置によれば、内部に液体が満たされた金属素材を第１及び第２プレス型でプレス成形することにより、第１プレス型の主付形部と第２プレス型の副付形部との協働作用に基づいて、当該金属素材に対して所望の形状（例えば金属素材の一部が他部位に対して偏角及び／又は偏芯するような形状）が付与される。そして、第２プレス型には副付形部と連なる線長調整部が設けられているため、プレス成形の際に、線長調整部による金属素材壁部の整形作用に基づき、前記主付形部が押圧する側と反対側において被押圧物（中空金属素材）にシワや座屈などの製品欠陥が発生するのを防止することができる。
【００１９】
なお、請求項６において、前記主付形部は、金属素材に対しその一部が他部位に対して偏角及び／又は偏芯するような形状を付与すべく第１プレス型から第２プレス型に向けて突設されており、前記線長調整部は、線長調整のための距離を確保すべく第２プレス型から第１プレス型に向けて突設又は第２プレス型において凹設されていること、は好ましい。また、請求項６において、前記液圧調整手段は、第１及び第２プレス型によるプレス成形により液体を満たした金属素材が変形する際も金属素材内の液圧を所定の目標圧に維持すること、は好ましい。この場合には、液圧調整手段により、プレス成形によって金属素材が変形する際も金属素材内の液圧が所定の目標圧に維持されるため、金属素材の内壁面に過大な圧力が加わることが無く、過大な液圧に起因した割れや座屈などの製品欠陥の発生を防止することができる。
【００２０】
【発明の実施の形態】
以下、本発明のいくつかの実施形態を説明する。最初に、製品本体部に対して管端が偏角した形状を持つ中空金属製品の成形事例を図１〜図４を参照して説明する。なお、図１〜図４の成形事例で用いられる成形装置及び成形手法は、図５以下の他の事例にも同じく当てはまることを付言しておく。
【００２１】
液圧プレス成形の出発材料となる中空な金属素材としては、図１に示すようなステンレス鋼（ＳＵＳ）製金属パイプ１０が用いられる（図１には金属パイプ１０の４つの径変箇所にａ，ｂ，ｃ及びｄの記号を付す）。この金属パイプ１０は、ストレートパイプ状の本体部１１，１１と、その中程において当該本体部の径よりも小径化された縮径部１２とを有している。縮径部１２とは、径変箇所ａとｄとの間の部分を指し、本体部１１，１１とは、径変箇所ａよりも左の部分および径変箇所ｄよりも右の部分を指す。更に、縮径部１２は、左テーパ部（区間ａｂ）、ストレート部（区間ｂｃ）及び右テーパ部（区間ｃｄ）の三部から構成される。つまりテーパ部とは、左又は右の本体部１１とストレート部（区間ｂｃ）との間にあって径が徐々に変化している部分のことである。金属パイプ１０において本体部１１と縮径部１２とはそれぞれの中心軸線が軸線Ｌ１に完全一致している。また、この金属パイプ１０は、縮径部１２のストレート部（区間ｂｃ）の中心位置にて軸線Ｌ１と直交する仮想中心面Ｐを挟んで左右対称をなす。図１に示すような縮径部１２を有する金属パイプ１０は、例えば真っ直ぐな金属パイプの一部に対し、同軸（非偏芯）スピニング装置を用いた同軸絞り加工等の縮径加工を施すことにより比較的簡単に得ることができる。
【００２２】
液圧プレス成形に使用する液圧プレス成形装置は、金属パイプ１０内に満たした液体（例えば水）の液圧を調整するための液圧調整手段と、プレス成形手段としての金型装置とを具備している。
【００２３】
図１に示すように、液圧調整手段は、金属パイプ１０の左右両端部開口を封止するための左右一対のシール治具１３，１４と、調圧ポンプ機構１５とから構成される。一対のシール治具のうちの少なくとも一方（１３）には連通路１６が形成されており、この連通路１６を介して金属パイプ内部と調圧ポンプ機構１５とが連通可能となっている。調圧ポンプ機構１５は、金属パイプ１０内に液体を追加供給したり金属パイプ１０内から液体を逃したりしながら金属パイプ１０内の液圧が目標圧にほぼ保たれるように液圧のフィードバック制御を行う。尚、図１には図示しないが、金属パイプ１０の各端部と各シール治具１３，１４との接合領域に可撓性のシールリングを介在させてもよい。
【００２４】
プレス成形手段としての金型装置は、第１のプレス型としての可動型（上型）２１と、第２のプレス型としての固定型（下型）２３とを備えている。可動型２１は、図示しない駆動機構により固定型２３に対し接近離間可能となっている。プレス成形時、両型２１，２３間には前記一対のシール治具１３，１４によって保持された金属パイプ１０が配置される。
【００２５】
可動型２１には、金属パイプの縮径部１２にほぼ対応して、該パイプに所望形状（この場合偏角形状）を付与するための主付形部２２が設けられている。主付形部２２は前記仮想中心面Ｐを挟んで左右対称形状をなしている。この主付形部２２は、可動型２１から固定型２３に向けて突設されており、プレス成形時には金属パイプの縮径部１２をやや引き延ばし加減で上から下に押圧する。主付形部２２による押圧によって、金属パイプ１０の被押圧部位（即ちパイプの上面側）が過度に減肉されたり割れたりする虞れがある。このような金属パイプの上面側における減肉や割れの発生を回避するために、金属パイプ縮径部１２の表面の長手方向線長Ｄ１（具体的にはＤ１＝区間ａｂ長＋区間ｂｃ長＋区間ｃｄ長）と、主付形部２２によって付形される部位の長手方向における最大線長Ｄ２（即ち図１及び図２における境界点Ｎ１から境界点Ｎ２までの主付形部のアウトラインの長さ）とが一致又は近似するように、主付形部２２のアウトライン長Ｄ２（又は金属パイプ縮径部１２の表面の長手方向線長Ｄ１）が設定されている。
【００２６】
固定型２３には、金属パイプの縮径部１２にほぼ対応して、二つの副付形部２４，２４と、その二つの副付形部間に位置する線長調整部２５とが設けられている。固定型の二つの副付形部２４，２４及び線長調整部２５は、前記仮想中心面Ｐを挟んで左右対称形状をなしている。二つの副付形部２４，２４は、金属パイプ縮径部１２の二つのテーパ部（区間ａｂ及び区間ｃｄ）にそれぞれ対応して設けられており、可動型２１の主付形部２２が前記両テーパ部の上面側を押圧して変形させる際にその押圧力を背後で受け止めて両テーパ部の下面側形状を整える役目を担う。即ち、可動型の主付形部２２と固定型の副付形部２４とは、所望形状付与に際して協働関係にある。
【００２７】
二つの副付形部２４，２４が固定型２３の上面に対しやや窪んだ態様で設けられているのに対し、両副付形部の中間に位置する線長調整部２５は、固定型２３から可動型２１に向けて突設されている。線長調整部２５の突出は、線長調整のための距離をかせぐためである。即ち、可動型の主付形部２２がプレス成形時に金属パイプの縮径部１２をやや引き延ばし加減で上から下に押圧することによる影響として、金属パイプ１０の下面側には肉余りが生じ、その肉余りを吸収すべくシワや座屈が発生する虞れがある。このような金属パイプの下面側におけるシワや座屈の発生を回避するために、金属パイプ縮径部１２の表面の長手方向線長Ｄ１（具体的にはＤ１＝区間ａｂ長＋区間ｂｃ長＋区間ｃｄ長）と、副付形部２４及び線長調整部２５によって付形及び整形（即ち線長調整）される部位の長手方向における線長Ｄ３（即ち図１及び図２における境界点Ｎ３から線長調整部の頂点Ｎ４を経由して境界点Ｎ５にいたるまでの副付形部及び線長調整部の連続したアウトラインの長さ）とが一致又は近似するように、副付形部２４及び線長調整部２５の連続したアウトライン長Ｄ３（又は金属パイプ縮径部１２の表面の長手方向線長Ｄ１）が設定されている。
【００２８】
次に、上記液圧プレス成形装置を用いた液圧プレス成形の手順等について説明する。まず図１に示すように、中空な金属素材としての上記金属パイプ１０を可動型２１と固定型２３との間に配置すると共に、金属パイプ１０の両端部にシール治具１３，１４を装着する。金属パイプ１０は、両シール治具１３，１４により固定型２３上に接触載置された状態で保持される（図１では参照番号記入の便宜から、金属パイプ１０を固定型２３に対し非接触状態で描いている）。
【００２９】
金型装置への金属パイプ１０のセッティングが完了すると、金属パイプ１０内には液体（例えば水）が充填されると共に、調圧ポンプ機構１５によって金属パイプ内の液圧が大気圧以上の目標圧（具体的には約１００〜３００気圧＝約１０〜３０ＭＰａ）に調節される。この目標圧は、金属パイプ１０の肉厚や剛性を考慮しつつ、液圧のみでパイプの変形が起こり得ない圧力に定められている。尚、調圧ポンプ機構１５は、下記プレス成形の最中においても金属パイプ１０内の液圧が前記目標圧を維持し得るように液圧制御を行う。
【００３０】
続いて、固定型２３に対し可動型２１を押し付けて金属パイプ１０をプレス成形する。このときのプレス圧は、５０〜３００ＭＰａである。その結果、図２に示すように、金属パイプ１０の縮径部１２には、可動型の主付形部２２並びに固定型の副付形部２４及び線長調整部２５に対応した形状が付与される。即ち、金属パイプ縮径部１２の二つのテーパ部（区間ａｂ及び区間ｃｄ）に対応する部位であって主付形部２２と副付形部２４とによって挟圧される各部位には、パイプ本体部１１の軸線Ｌ１に対し下方に傾斜した軸線Ｌ２を中心軸線とする偏角形状が付与される。即ち偏角とは、本体部の中心軸線Ｌ１と当該偏角部位の中心軸線Ｌ２とが一致せず、互いに傾斜した関係にあることをいう。他方、金属パイプ縮径部１２のストレート部（区間ｂｃ）に対応する部位であって主付形部２２と線長調整部２５とによって挟圧される部位は、複雑に歪んだ形状となる。
【００３１】
前記主付形部２２と副付形部２４とによって付形された部位は、最終製品における偏角した管端部として有用な部位である。これに対し、主付形部２２と線長調整部２５とによって歪んだ形状となった部位は、最終製品の一部とはならない不要な部位である。このため、プレス成形後に液体を排出し且つ金型装置から取り外して得られる筒状の中間製品に対しては、図２に破線で示す二箇所の切断線Ｓに沿って切断が施される。この二箇所での切断により、図４に示すように筒状の中間製品から線長調整部２５に対応する歪み形状部位（二点鎖線で示す部位）が除去されて、傾斜軸線Ｌ２を中心軸線とする偏角した管端部３１を有する最終製品３０（実線で示す）が二個同時に得られる。
【００３２】
なお、図３（Ａ）は図２中のＡ−Ａ線断面（Ａ−Ａ線は切断線Ｓに沿う）を示し、図３（Ｂ）は図２中のＢ−Ｂ線断面（Ｂ−Ｂ線は仮想中心面Ｐに沿う）を示す。換言すれば、図３（Ａ）は不要部分として除去される歪み形状部位の端面形状を示し、図３（Ｂ）は同歪み形状部位の中心位置での断面を示す。図３（Ａ）及び（Ｂ）から示唆されるように、プレス成形手段としての可動型２１及び固定型２３の各形状は、偏角した管端部となる部位の端面形状が金属パイプ１０の本体部１１と相似形である真円形となり、且つ、捨て去られるべき歪み形状部位の中心断面が長円形又は楕円形となるように形状設定されている。しかも、プレス時においてシワや座屈が、偏角した管端部となる部位に生じ難くするために、図３（Ａ）に示す真円の外周長Ｃ１と、図３（Ｂ）に示す長円又は楕円の外周長Ｃ２とがほぼ一致するように、可動型２１及び固定型２３の各形状が設定されている。
【００３３】
このように図１〜図４の成形事例によれば、内部に液体が満たされた金属パイプ１０を可動型２１及び固定型２３でプレス成形することにより、主付形部２２と副付形部２４とにより挟圧される部位に対して、中心軸線Ｌ２が本体部１１の軸線Ｌ１に対して傾斜する偏角形状を正確且つ迅速に付与することができる。更には、かかる偏角形状付与を目的とした特殊プレス成形にもかかわらず、固定型２３の中央に設けられた線長調整部２５による金属パイプ壁の整形作用（線長調整作用）に基づき、主付形部２２が押圧する側と反対側であって副付形部２４が付形に関与する部位において、シワや座屈等の製品欠陥が発生するのを効果的に防止することができる。
【００３４】
また、出発材料となる金属パイプ１０並びに可動型２１及び固定型２３を前記仮想中心面Ｐを挟んで左右対称な形状としたことにより、一度のプレス成形で、金属パイプ１０の二箇所に二つの偏角形状を付与することができ、ひいては、その後の切断により、偏角した管端部３１を有する最終製品３０を二個同時に製造することができる。それ故、本実施形態によれば、所望の管端形状を有する中空金属製品３０を極めて効率的に生産することができる。
【００３５】
上記図１〜図４では、偏角した管端部３１を有する中空金属製品３０の成形事例を説明したが、可動型２１の主付形部２２の形状並びに固定型２３の副付形部２４及び線長調整部２５の形状を、プレス成形で得たい形状に合致するように変更することで、管端に様々な複雑形状を持つ中空金属製品を製造することが可能となる。以下、図５〜図１１を参照して、本発明により成形可能な複雑形状の態様を説明する。
【００３６】
図５は、本体部１１に対して管端が偏芯した形状を持つ中空金属製品の成形事例を示す。この例では、製品本体部１１の中心軸線Ｌ１に対して、可動型の主付形部２２及び固定型の副付形部２４によって付形される管端部３１の中心軸線Ｌ２が所定距離だけオフセットしている。つまり管端部３１は本体部１１に対して偏芯している。ここで偏芯とは、本体部の中心軸線Ｌ１と管端部の中心軸線Ｌ２とが一致しないのみならず、互いに所定距離を隔てて平行な関係にあることをいう。プレス成形後に二箇所の切断線Ｓに沿って切断すれば、一度に二個の中空金属製品を得られる点は前記事例と同じである。
【００３７】
図６は、本体部１１に対して管端が大きく偏角した形状を持つ中空金属製品の成形事例を示す。管端の偏角という点では前記図２の事例と共通するが、図６の事例は偏角の程度が極端に大きくなっている。即ち図６では、管端部３１の先端（切断線Ｓに沿って切断される部位）が金属パイプの本体部１１の外周面よりも更に半径方向外側に大きく突出する位置にまで達している点に特徴がある。図６のように、管端部３１の先端が金属パイプの本体部１１の外周面よりも更に半径方向外側に大きく突出するような偏角形状は、絞り加工を基調とする従来の偏角スピニング加工によっては得ることができない形状であり、本発明の偏角プレス成形法によって初めて一体成形可能となった形状である。尚、プレス成形後に二箇所の切断線Ｓに沿って切断すれば、一度に二個の中空金属製品を得られる点は前記事例と同じである。
【００３８】
図７は、本体部１１に対して管端が大きく偏角した形状を持つ中空金属製品の成形事例を示す。管端の偏角という点では前記図２の事例と共通するが、図７の事例は偏角の態様が全く異なる。即ち図７では、偏角した管端の根元部分であって固定型２３の側に、直角に近い急角度で曲げ部３２が形成される点に特徴がある。この曲げ部３２は、固定型２３の副付形部２４の一部が山形に突出形成されることによって実現される。図７のように、偏角した管端の根元部分に急角度の曲げ部３２を有するような偏角形状は、絞り加工を基調とする従来の偏角スピニング加工によっては得ることができない形状であり、本発明の偏角プレス成形法によって初めて一体成形可能となった形状である。尚、プレス成形後に二箇所の切断線Ｓに沿って切断すれば、一度に二個の中空金属製品を得られる点は前記事例と同じである。
【００３９】
図８は、本体部１１に対して管端近傍が２段階に偏角すると共に管端が偏芯した形状を持つ中空金属製品の成形事例を示す。即ち図８では、本体部１１の中心軸線Ｌ１に対して第１の偏角部３３の中心軸線Ｌ２が傾斜すると共に、その軸線Ｌ２に対して第２の偏角部３４の中心軸線Ｌ３が更に傾斜角度を増して傾斜している。更に、この第２の偏角部３４に対しては、本体部１１に対して偏芯した管端部３５が連続する。即ち、管端部３５の中心軸線Ｌ４と本体部１１の中心軸線Ｌ１とは平行関係にある。図８のように、本体部１１に対して管端近傍が２段階に偏角し且つ管端が偏芯した複雑な形状は、絞り加工を基調とする従来の偏角スピニング加工によっては得ることができない形状であり、本発明の偏角及び偏芯プレス成形法によって初めて一体成形可能となった形状である。
【００４０】
図２、図６、図７及び図８の偏角事例では、本体部１１の中心軸線Ｌ１と、偏角した部分の中心軸線Ｌ２等とが同一垂直面内に存在することを前提としていたが、本発明の偏角プレス成形における偏角方向は、偏角部分の中心軸線がそのような同一垂直面内にある場合に限定されない。例えば図９に示すように、本体部１１の中心軸線Ｌ１がｘｙｚ三次元直交座標系のｘ軸方向に延びているものと仮定した場合に、当該本体部１１に対して偏角した管端部３１における中心軸線Ｌ２が、前記ｘｙｚ三次元直交座標系のｙ軸方向とｚ軸方向とを合成したｙｚ合成方向に延びていてもよい。つまり、本発明の偏角プレス成形法によれば、製品の管端を任意の方向に偏角させることができる。
【００４１】
本発明の偏角及び／又は偏芯プレス成形法は基本的にプレス成形であるので、可動型２１及び固定型２３の形状設定次第で、プレス成形品の全部又は一部に対して、金属パイプ１０の断面形状（真円形）とは異なる異形断面形状を付与することができる。例えば、図１０（Ａ）に示す真円形状の他に、正方形や長方形などの矩形状（図１０（Ｂ）参照）、六角形などの多角形状（図１０（Ｃ）参照）、あるいは星型形状（図１０（Ｄ）参照）などの異形断面形状を付与することができる。
【００４２】
また図１１に示すように、可動型２１及び固定型２３にその他の付形部位としての凹部（２６，２７）や凸部（２８，２９）を局部的に形成しておくことで、金属パイプ１０に局部的な凹凸形状を付与してもよい。
【００４３】
図１２は、本件方法及び装置を用いて成形した触媒コンバータケースの一例を示す。このケースの端部４１は本体部４２に対し偏芯成形されると共に、出発材である金属パイプ１０の縮径部テーパ部分を利用して成形した部位４３には、センサ用の座部４４が局部的に突出形成されている。この座部４４は、可動型２１の一部に図１１の凹部２６のような付形部位を設けておくことで、プレス成形時に金属パイプ１０に対して一体成形される。この座部４４に対し後加工で取付孔４５を穿設することにより、当該取付孔４５を介して座部４４に対しセンサ（例えば酸素濃度や温度測定用のセンサ）が取り付け可能となる。
【００４４】
図１３（Ａ）及び（Ｂ）は、本件方法及び装置を用いて成形した触媒コンバータケースの別例を示す。図１３（Ａ）の例では、ケースの出口側端部４６が本体部４２と同軸関係にあるのに対し、ケースの入口側端部４１は本体部４２に対し偏角している。また、図１３（Ｂ）の２個の触媒コンバータケースを並列連結した例では、各ケースの出口側端部４６が本体部４２と同軸関係にあるのに対し、各ケースの入口側端部４１は本体部４２に対し偏芯している。いずれの事例も、入口側端部４１の根元付近にセンサ４７用の座部４４を成形している。このように本発明の成形方法によれば、触媒コンバータケースの入口側端部４１を任意の方向に偏角させ、又は、偏芯させることができるため、触媒コンバータケースの設計自由度が増す。また、特に図１３（Ｂ）の事例では、各コンバータケースの入口側端部４１を偏芯させたことで、両入口側端部４１を連結するフランジ部品４８の通気穴間の間隔（穴ピッチＱ）が小さくて済む。換言すれば、フランジ部品４８における穴ピッチＱを拡大することなく、比較的大径のコンバータケースを２個並列配置することが可能となる。このように、本件の液圧プレス成形方法及び装置は、触媒コンバータケースの成形又は製造に極めて有用である。
【００４５】
本発明は触媒コンバータケースの成形又は製造に適用されるのみならず、その他の中空金属製品、例えば、自動車の配管系を構成するパイプ、排気マフラーのケース、あるいは排気マニホールドの集合部等の成形又は製造に適用可能であることは言うまでもない。
【００４６】
出発材料となる中空な金属素材１０の材質は、ＳＵＳ以外の鉄系材料、アルミニウム系材料等どのような金属でもよい。また、上記各事例では、線長調整部２５を第２プレス型２３から第１プレス型２１に向けて突設したが、第２プレス型２３において凹んだ状態で設けられてもよい（即ち凹設）。
【００４７】
【発明の効果】
以上詳述したように本発明の液圧プレス成形方法によれば、従来のスピニング加工では成形不可能であったような複雑度の高い形状をも、製品欠陥を伴うことなく安価に且つ短時間に一体成形可能となる。また、本発明の液圧プレス成形装置によれば、上記液圧プレス成形方法を確実に実施可能となる。
【図面の簡単な説明】
【図１】プレス前の成形装置及び金属パイプの一例を示す断面図。
【図２】プレス後の装置及び偏角中間製品の状態を示す断面図。
【図３】図２の中間製品の断面形状を示し、（Ａ）は図２のＡ−Ａ線での断面図、（Ｂ）は図２のＢ−Ｂ線での断面図。
【図４】図２の中間製品を切断して製品化したときの断面図。
【図５】偏芯成形の一例を示す断面図。
【図６】偏角成形の別例を示す断面図。
【図７】偏角成形の別例を示す断面図。
【図８】偏角及び偏芯成形の一例を示す断面図。
【図９】偏角成形の別例を示す断面図。
【図１０】（Ａ）〜（Ｄ）は製品断面の形状例を示す断面図。
【図１１】局部凹凸形状の成形例を示す断面図。
【図１２】自動車部品への本発明の適用例を示す斜視図。
【図１３】（Ａ）及び（Ｂ）は本発明の適用例を示す斜視図。
【符号の説明】
１０…金属パイプ（中空な金属素材）、１１…金属パイプの本体部、１２…金属パイプの縮径部、１３，１４…シール治具、１５…調圧ポンプ機構（１３〜１５は液圧調整手段を構成する）、２１…第１プレス型としての可動型、２２…可動型の主付形部、２３…第２プレス型としての固定型（２１，２３はプレス成形手段を構成する）、２４…固定型の副付形部、２５…固定型の線長調整部、Ｌ１，Ｌ２，Ｌ３，Ｌ４…軸線、Ｐ…仮想中心面、Ｓ…切断線。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a hydraulic press forming method for a hollow metal product and a hydraulic press forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a spinning method is known as a method of giving a complicated shape to an end of a metal tube as a work. For example, by performing spinning with the pipe axis of the metal pipe and the revolving axis of the spinning roll being eccentric, the pipe axis is eccentric with respect to the pipe axis of the pipe section and integrated with the pipe section. A method of forming a large eccentric reduced diameter portion has been proposed (see Patent Document 1). Further, by performing the spinning process with the pipe axis of the metal pipe and the revolving axis of the spinning roll being tilted, the metal pipe is inclined with respect to the pipe axis of the pipe section and is unbalanced integrally with the pipe section. There has been proposed a method of forming a reduced-angle portion (see Patent Document 2).
[0003]
[Patent Document 1]
Patent No. 2957153 (Claims)
[Patent Document 2]
Patent No. 2957154 (Claims)
[0004]
[Problems to be solved by the invention]
However, the spinning method described above also has disadvantages. First, it is necessary to provide a spinning processing facility equipped with a mechanism for relatively revolving a plurality of rolls pressed against the outer periphery of the end of the metal tube in an eccentric or deviated state with respect to the tube axis of the tube. However, such equipment is complex and expensive. Further, since the spinning process is a sequential drawing process in which the end of a metal tube is drawn stepwise, if the drawing amount in one step is increased, product defects such as cracks and thinning are likely to occur. For this reason, it is necessary to reduce the amount of drawing in one step to a small amount and to go through a plurality of drawing steps, which tends to increase the processing time.
[0005]
Furthermore, there is a limit to the shape that can be formed by the eccentricity / eccentricity spinning process. That is, since spinning is essentially rotary drawing from the outside to the inside of the base tube, for example, an eccentric / eccentric shape that extends outside beyond the outside diameter of the metal base tube, It is not possible to integrally mold a shape having a higher degree of complexity, such as a shape having no rotational symmetry with respect to a given axis (for example, a cross-sectional shape other than a circle).
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic press for a hollow metal product that can be integrally formed in a short time at a low cost without a product defect, even with a complicated shape that cannot be formed by conventional spinning. It is to provide a molding method. Another object of the present invention is to provide a hydraulic press molding apparatus suitable for carrying out the molding method.
[0007]
[Means for Solving the Problems]
The invention of claim 1 is a first press die provided with a main shaping portion, a sub shaping portion cooperating with the main shaping portion of the first press die, and a wire length adjustment connected to the sub shaping portion. Preparing a forming device comprising a second press die provided with a portion, a step of filling the hollow metal material held between the first and second press dies of the forming device with a liquid, Press-forming the filled metal material with the first and second press dies, and opposing a side pressed by the main shaping portion based on a shaping action of the metal material wall portion by the wire length adjusting portion. The portion pressed between the main shaping portion of the first press die and the sub shaping portion of the second press die is located on the other side of the metal material while preventing product defects from occurring on the side. Hydraulic pressure of a hollow metal product characterized by imparting a shape that is deviated and / or decentered with respect to the hollow metal product It is less molding method.
[0008]
According to this method, the metal material filled with the liquid is press-formed by the first and second press dies, and the main press portion of the first press die and the second press die are formed on the metal material. A shape is formed such that a portion pressed between the auxiliary shaping portion and the other portion is deviated and / or eccentric with respect to another portion. Since the second press die is provided with a wire length adjusting portion connected to the sub-shape portion, the metal material by the wire length adjusting portion can be used even in press forming for the purpose of imparting an eccentric angle and / or an eccentric shape. Based on the shaping action of the wall portion, it is possible to prevent a product defect such as wrinkles or buckling from being generated on the pressed object (hollow metal material) on the side opposite to the side pressed by the main shaping portion. In other words, according to this method, it is possible to integrally mold a highly complex shape that could not be formed by conventional spinning at low cost in a short time without product defects such as wrinkles and buckling. It becomes.
[0009]
According to a second aspect of the present invention, in the method for hydraulic press forming of a hollow metal product according to the first aspect, a portion corresponding to the wire length adjusting section is cut off from the press-formed product obtained in the pressing step. Is characterized in that a hollow metal product having a desired declination and / or eccentric shape is obtained at or near the end of the hollow metal product.
[0010]
According to this method, an unnecessary portion (a portion corresponding to the wire length adjusting portion) is cut and removed from the press-formed product obtained in the pressing step, so that a desired declination and a desired declination can be obtained at or near the end of the product. A hollow metal product having an eccentric shape is obtained.
[0011]
According to a third aspect of the present invention, in the method for hydraulic press forming of a hollow metal product according to the first or second aspect, the hollow metal material has a pipe-shaped main body and a reduced diameter smaller than the diameter of the main body. A metal pipe having a diameter portion, a length in the longitudinal direction of a surface of the metal pipe reduced diameter portion, and a sub-shape portion and a wire length of the second press die of a press-formed product obtained in the pressing step. The shape of the second press die or the shape of the metal pipe is set so that the line length in the longitudinal direction of the part to be shaped and shaped by the adjustment unit matches or approximates.
[0012]
According to this method, even if the main shaping portion of the first press mold extends and presses the reduced diameter portion of the metal pipe, the side opposite to the side pressed by the main shaping portion (that is, the sub shaping portion and The occurrence of product defects such as wrinkles and buckling in the pressed object (metal pipe) on the side received by the wire length adjustment unit is reliably avoided.
[0013]
According to a fourth aspect of the present invention, in the method for hydraulic press forming of a hollow metal product according to the third aspect, the length of the surface of the reduced diameter portion of the metal pipe in the longitudinal direction and the press-formed product obtained in the pressing step are included. The shape of the first press die or the shape of the metal pipe is set so that the maximum line length in the longitudinal direction of the portion formed by the main press forming portion of the first press die coincides or approximates. It is characterized by having.
[0014]
According to this method, the pressed portion of the metal pipe pressed by the main shaping portion of the first press die is reliably prevented from being excessively reduced in thickness or broken.
[0015]
According to a fifth aspect of the present invention, in the method for hydraulically press-forming a hollow metal product according to any one of the first to fourth aspects, the first and second press dies and the hollow held between the two press dies are provided. The metal material is formed in a symmetrical shape with respect to the wire length adjusting portion as a center, and after the pressing step, a hollow metal product having a desired angle and / or eccentric shape at or near an end of the product Are obtained at the same time. According to this method, two desired hollow metal products can be simultaneously obtained by one press molding, and the productivity is improved.
[0016]
In addition, in Claims 1-5, "a shaping part for giving a deformed cross-sectional shape different from the original cross-sectional shape of the metal material to at least one of the first and second press dies, or It is preferable that a shaping portion for providing a local uneven shape is provided in a part of the metal material. " In this case, when imparting a desired declination and / or eccentric shape to the hollow metal product, it is possible to additionally impart an irregular cross-sectional shape or a local uneven shape, thereby improving productivity.
[0017]
The invention according to claim 6 is provided with a hydraulic pressure adjusting means for adjusting the hydraulic pressure of the liquid filled in the hollow metal material, and press forming means comprising first and second press dies which can be relatively approached and separated. A hydraulic press forming apparatus, wherein the first press mold is provided with a main shaping portion for applying a shape by pressing a metal material filled with liquid, and the second press mold includes a A sub-shaped portion cooperating with the main shaped portion of one press die, and a side connected to the sub-shaped portion and opposite to a side pressed by the main shaped portion during press forming by the first and second press dies; A hydraulic press molding apparatus characterized by being provided with a wire length adjusting section for preventing occurrence of a product defect in the above.
[0018]
According to this apparatus, the metal material filled with the liquid is press-formed by the first and second press dies, so that the main press portion of the first press die and the sub-press portion of the second press die are formed. Of the metal material is given a desired shape (for example, a shape in which a part of the metal material is deviated and / or decentered with respect to other parts). Since the second press die is provided with a wire length adjusting portion connected to the sub-shape portion, the main shaping portion is formed based on the shaping action of the metal material wall portion by the wire length adjusting portion during press forming. It is possible to prevent a product defect such as wrinkles or buckling from being generated on the pressed object (hollow metal material) on the side opposite to the side pressed by the portion.
[0019]
In the sixth aspect, the main shaping portion is formed by a first press die and a second press die so as to give the metal material a shape in which a part thereof is deviated and / or decentered with respect to other parts. The wire length adjusting portion is provided so as to project from the second press die toward the first press die or to be concave in the second press die so as to secure a distance for wire length adjustment. Is preferred. Further, in claim 6, the liquid pressure adjusting means maintains the liquid pressure in the metal material at a predetermined target pressure even when the metal material filled with liquid is deformed by press molding with the first and second press dies. Is preferred. In this case, the liquid pressure adjusting means maintains the liquid pressure in the metal material at a predetermined target pressure even when the metal material is deformed by press molding, so that excessive pressure is applied to the inner wall surface of the metal material. Therefore, it is possible to prevent the occurrence of product defects such as cracks and buckling due to excessive hydraulic pressure.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, some embodiments of the present invention will be described. First, an example of forming a hollow metal product having a shape in which the pipe end is deviated from the product body will be described with reference to FIGS. It should be noted that the molding apparatus and the molding method used in the molding examples shown in FIGS. 1 to 4 also apply to the other examples shown in FIG.
[0021]
A stainless steel (SUS) metal pipe 10 as shown in FIG. 1 is used as a hollow metal material as a starting material for the hydraulic press molding (FIG. , B, c and d). The metal pipe 10 has straight pipe-shaped main bodies 11 and 11 and a reduced diameter portion 12 in the middle of the main body 11 having a diameter smaller than that of the main body. The reduced diameter portion 12 indicates a portion between the diameter changing portions a and d, and the main body portions 11 and 11 indicate a left portion of the diameter changing portion a and a right portion of the diameter changing portion d. . Further, the reduced diameter portion 12 is composed of three parts: a left tapered part (section ab), a straight part (section bc), and a right tapered part (section cd). That is, the tapered portion is a portion between the left or right main body portion 11 and the straight portion (section bc), the diameter of which gradually changes. In the metal pipe 10, the central axes of the main body portion 11 and the reduced diameter portion 12 completely coincide with the axis L1. The metal pipe 10 is symmetrical with respect to a virtual center plane P orthogonal to the axis L1 at the center position of the straight portion (section bc) of the reduced diameter portion 12. The metal pipe 10 having the reduced diameter portion 12 as shown in FIG. 1 is obtained by, for example, subjecting a part of a straight metal pipe to reduced diameter processing such as coaxial drawing using a coaxial (non-eccentric) spinning device. Can be obtained relatively easily.
[0022]
The hydraulic press forming apparatus used for the hydraulic press forming includes a hydraulic pressure adjusting means for adjusting the liquid pressure of a liquid (for example, water) filled in the metal pipe 10 and a mold apparatus as the press forming means. I have it.
[0023]
As shown in FIG. 1, the liquid pressure adjusting means includes a pair of left and right seal jigs 13 and 14 for sealing the left and right end openings of the metal pipe 10, and a pressure adjustment pump mechanism 15. A communication passage 16 is formed in at least one (13) of the pair of sealing jigs, and the inside of the metal pipe and the pressure regulating pump mechanism 15 can be communicated via the communication passage 16. The pressure-regulating pump mechanism 15 provides feedback of the fluid pressure so that the fluid pressure in the metal pipe 10 is substantially maintained at the target pressure while additionally supplying the fluid into the metal pipe 10 or escaping the fluid from the metal pipe 10. Perform control. Although not shown in FIG. 1, a flexible seal ring may be interposed in a joint region between each end of the metal pipe 10 and each of the seal jigs 13 and 14.
[0024]
The die apparatus as a press forming means includes a movable die (upper die) 21 as a first press die, and a fixed die (lower die) 23 as a second press die. The movable mold 21 can be approached to and separated from the fixed mold 23 by a drive mechanism (not shown). At the time of press molding, a metal pipe 10 held by the pair of sealing jigs 13 and 14 is disposed between the two dies 21 and 23.
[0025]
The movable mold 21 is provided with a main shaping portion 22 for giving a desired shape (in this case, a deviated shape) to the metal pipe substantially corresponding to the reduced diameter portion 12 of the metal pipe. The main shaping portion 22 has a symmetrical shape with respect to the virtual center plane P. The main shaping portion 22 is protruded from the movable die 21 to the fixed die 23, and presses the reduced diameter portion 12 of the metal pipe slightly upward and downward during press forming from above to below. The pressed portion of the metal pipe 10 (that is, the upper surface side of the pipe) may be excessively reduced in thickness or cracked by the pressing by the main shaping portion 22. In order to avoid such thinning and cracking on the upper surface side of the metal pipe, the longitudinal line length D1 (specifically, D1 = section ab length + section bc length + Section cd length) and the maximum line length D2 in the longitudinal direction of the portion formed by the main shaping portion 22 (that is, the outline length of the main shaping portion from the boundary point N1 to the boundary point N2 in FIGS. 1 and 2). The length D2 of the outline of the main shaping portion 22 (or the length D1 of the surface of the reduced diameter portion 12 of the metal pipe in the longitudinal direction) is set so as to match or approximate the length.
[0026]
The fixed die 23 is provided with two sub-shaped portions 24, 24 substantially corresponding to the reduced diameter portion 12 of the metal pipe, and a wire length adjusting portion 25 located between the two sub-shaped portions. ing. The two fixed shaped sub-shaping portions 24 and 24 and the line length adjusting portion 25 are symmetrical with respect to the virtual center plane P. The two sub-shaped portions 24, 24 are provided corresponding to the two tapered portions (section ab and section cd) of the reduced diameter portion 12 of the metal pipe, respectively. When the upper surfaces of both tapered portions are pressed and deformed, the pressing force is received behind, and the lower surface of both tapered portions is shaped. That is, the movable main shaping portion 22 and the fixed type sub-shaping portion 24 are in a cooperative relationship when a desired shape is provided.
[0027]
While the two sub-shaped portions 24 are provided slightly depressed with respect to the upper surface of the fixed die 23, the wire length adjustment portion 25 located between the two sub-shaped portions is provided with the fixed die 23. From the movable die 21. The protrusion of the wire length adjusting unit 25 is to increase the distance for wire length adjustment. That is, as a result of the main shaping portion 22 of the movable die slightly expanding and reducing the diameter-reduced portion 12 of the metal pipe at the time of press molding and pressing it downward from above, a surplus occurs on the lower surface side of the metal pipe 10, There is a possibility that wrinkles or buckling may occur to absorb the excess meat. In order to avoid the occurrence of wrinkles and buckling on the lower surface side of the metal pipe, a longitudinal line length D1 (specifically, D1 = section ab length + section bc length + The section cd length) and the line length D3 in the longitudinal direction of the portion to be shaped and shaped (that is, the line length adjustment) by the sub-shape portion 24 and the line length adjusting portion 25 (ie, from the boundary point N3 in FIGS. 1 and 2). The sub-shape portion 24 and the sub-shape portion 24 and the continuous outline of the line length adjustment portion up to the boundary point N5 via the vertex N4 of the line length adjustment portion coincide with or approximate to each other. A continuous outline length D3 of the wire length adjusting unit 25 (or a longitudinal line length D1 of the surface of the metal pipe reduced diameter portion 12) is set.
[0028]
Next, the procedure of hydraulic press molding using the above hydraulic press molding apparatus will be described. First, as shown in FIG. 1, the metal pipe 10 as a hollow metal material is disposed between a movable mold 21 and a fixed mold 23, and seal jigs 13 and 14 are attached to both ends of the metal pipe 10. . The metal pipe 10 is held in a state of being placed in contact with the fixed mold 23 by the two sealing jigs 13 and 14 (in FIG. 1, the metal pipe 10 is not in contact with the fixed mold 23 for the sake of convenience of entry of reference numbers). Drawn in the state).
[0029]
When the setting of the metal pipe 10 to the mold apparatus is completed, the metal pipe 10 is filled with a liquid (for example, water), and the liquid pressure in the metal pipe is adjusted to a target pressure equal to or higher than the atmospheric pressure by the pressure adjusting pump mechanism 15. (Specifically, the pressure is adjusted to about 100 to 300 atm = about 10 to 30 MPa). The target pressure is set to a pressure at which the deformation of the pipe cannot occur due to only the liquid pressure while considering the thickness and rigidity of the metal pipe 10. The pressure adjusting pump mechanism 15 controls the liquid pressure so that the liquid pressure in the metal pipe 10 can maintain the target pressure even during the following press forming.
[0030]
Subsequently, the movable die 21 is pressed against the fixed die 23 to press-mold the metal pipe 10. The pressing pressure at this time is 50 to 300 MPa. As a result, as shown in FIG. 2, the reduced diameter portion 12 of the metal pipe 10 has a shape corresponding to the movable main shaping portion 22, the fixed sub shaping portion 24, and the wire length adjusting portion 25. Is done. In other words, each of the portions corresponding to the two tapered portions (section ab and section cd) of the metal pipe reduced diameter portion 12 and sandwiched by the main shaping portion 22 and the sub shaping portion 24 includes a pipe. An eccentric shape with the axis L2 inclined downward with respect to the axis L1 of the main body 11 as a central axis is provided. That is, the declination means that the central axis L1 of the main body portion and the central axis L2 of the deflected portion do not coincide with each other and are in a mutually inclined relationship. On the other hand, a portion corresponding to the straight portion (section bc) of the metal pipe reduced diameter portion 12 and pressed by the main shaping portion 22 and the wire length adjusting portion 25 has a complicatedly distorted shape.
[0031]
The part shaped by the main shaping part 22 and the sub shaping part 24 is a useful part as a deflected pipe end in the final product. On the other hand, the part distorted by the main shaping part 22 and the wire length adjusting part 25 is an unnecessary part that does not become a part of the final product. For this reason, the cylindrical intermediate product obtained by discharging the liquid after press molding and removing from the mold apparatus is cut along two cutting lines S indicated by broken lines in FIG. As a result of the cutting at these two locations, as shown in FIG. 4, a distortion-shaped portion (a portion indicated by a two-dot chain line) corresponding to the wire length adjusting portion 25 is removed from the cylindrical intermediate product, and the inclined axis L 2 is aligned with the central axis The two end products 30 (shown by solid lines) having the deviated tube ends 31 are obtained at the same time.
[0032]
3A shows a cross section taken along the line AA in FIG. 2 (the line AA is along the cutting line S), and FIG. 3B shows a cross section taken along the line BB in FIG. The B line is along the virtual center plane P). In other words, FIG. 3A shows an end face shape of a distorted portion to be removed as an unnecessary portion, and FIG. 3B shows a cross section at the center position of the distorted portion. As suggested from FIGS. 3A and 3B, each shape of the movable mold 21 and the fixed mold 23 as the press forming means is such that the end face shape of the deviated tube end portion is the shape of the metal pipe 10. The shape is set such that the shape becomes a true circle similar to the main body 11 and the center cross section of the distorted portion to be discarded becomes an oval or ellipse. Moreover, in order to make it difficult for wrinkles and bucklings to occur at the deviated pipe end portion at the time of pressing, the outer circumference length C1 of the perfect circle shown in FIG. 3A and the length shown in FIG. The shapes of the movable die 21 and the fixed die 23 are set so that the outer circumference C2 of the circle or the ellipse substantially matches.
[0033]
As described above, according to the molding examples of FIGS. 1 to 4, the metal pipe 10 filled with the liquid is press-molded by the movable mold 21 and the fixed mold 23 to form the main shaping portion 22 and the sub shaping portion. Thus, a deflected shape in which the central axis L2 is inclined with respect to the axis L1 of the main body 11 can be accurately and quickly given to the portion pinched by the pressure. Further, despite the special press forming for the purpose of imparting the deflected shape, based on the shaping action (wire length adjusting action) of the metal pipe wall by the wire length adjusting section 25 provided at the center of the fixed mold 23, On the side opposite to the side pressed by the main shaping portion 22 and where the sub shaping portion 24 participates in shaping, it is possible to effectively prevent the occurrence of product defects such as wrinkles and buckling. .
[0034]
In addition, since the metal pipe 10 as the starting material and the movable mold 21 and the fixed mold 23 are formed to be symmetrical with respect to the virtual center plane P, two press-molding operations are performed at two places of the metal pipe 10. A declination shape can be given, and by subsequent cutting, two end products 30 having deflected tube ends 31 can be manufactured simultaneously. Therefore, according to the present embodiment, the hollow metal product 30 having a desired pipe end shape can be produced extremely efficiently.
[0035]
In FIGS. 1 to 4 described above, the example of forming the hollow metal product 30 having the deviated pipe end 31 has been described, but the shape of the main shaping portion 22 of the movable mold 21 and the sub shaping portion 24 of the fixed mold 23 are described. By changing the shape of the wire length adjusting unit 25 so as to match the shape desired by press molding, it is possible to manufacture hollow metal products having various complicated shapes at the pipe end. Hereinafter, with reference to FIGS. 5 to 11, an embodiment of a complicated shape that can be formed by the present invention will be described.
[0036]
FIG. 5 shows an example of forming a hollow metal product having a shape in which the pipe end is eccentric with respect to the main body 11. In this example, the center axis L2 of the tube end 31 formed by the movable main shaping portion 22 and the fixed sub-shape portion 24 is a predetermined distance from the center axis L1 of the product main body 11. Offset. That is, the tube end 31 is eccentric with respect to the main body 11. Here, the eccentricity means that not only does the central axis L1 of the main body part and the central axis L2 of the pipe end part do not coincide with each other, but also that they are in a parallel relationship at a predetermined distance from each other. The point that two hollow metal products can be obtained at once by cutting along two cutting lines S after press molding is the same as the above-mentioned case.
[0037]
FIG. 6 shows an example of forming a hollow metal product having a shape in which the pipe end is largely deviated with respect to the main body 11. Although the example shown in FIG. 2 is common in terms of the deflection of the pipe end, the degree of the deflection is extremely large in the case of FIG. That is, in FIG. 6, the tip of the pipe end portion 31 (the portion cut along the cutting line S) reaches a position where it protrudes further outward in the radial direction than the outer peripheral surface of the main body portion 11 of the metal pipe. There is a feature. As shown in FIG. 6, the deflected shape in which the distal end of the pipe end 31 protrudes farther outward in the radial direction than the outer peripheral surface of the main body 11 of the metal pipe is formed by a conventional deflected spinning based on drawing. This is a shape that cannot be obtained by processing, and is a shape that can be integrally formed for the first time by the deflected press forming method of the present invention. In addition, if it cuts along two cutting lines S after press molding, the point which can obtain two hollow metal products at a time is the same as the said example.
[0038]
FIG. 7 shows a molding example of a hollow metal product having a shape in which the pipe end is largely deviated with respect to the main body 11. Although it is common to the case of FIG. 2 in the point of the deflection of the pipe end, the case of FIG. 7 is completely different in the aspect of the deflection. That is, FIG. 7 is characterized in that the bent portion 32 is formed at a steep angle close to a right angle on the side of the fixed mold 23 at the base of the deflected pipe end. The bent portion 32 is realized by forming a part of the auxiliary shaping portion 24 of the fixed die 23 so as to protrude in a mountain shape. As shown in FIG. 7, a deflected shape having a steep bent portion 32 at the base of the deflected pipe end is a shape that cannot be obtained by the conventional deflected spinning based on drawing. There is a shape that can be integrally formed for the first time by the deflection press forming method of the present invention. In addition, if it cuts along two cutting lines S after press molding, the point which can obtain two hollow metal products at a time is the same as the said example.
[0039]
FIG. 8 shows an example of forming a hollow metal product having a shape in which the vicinity of the pipe end is deviated in two steps with respect to the main body 11 and the pipe end is eccentric. That is, in FIG. 8, the center axis L2 of the first deflector 33 is inclined with respect to the center axis L1 of the main body 11, and the center axis L3 of the second deflector 34 is further inclined with respect to the axis L2. Inclined at an increased angle. Further, a tube end 35 eccentric to the main body 11 continues to the second deflected portion 34. That is, the central axis L4 of the tube end 35 and the central axis L1 of the main body 11 are in a parallel relationship. As shown in FIG. 8, a complicated shape in which the vicinity of the pipe end is deviated in two steps with respect to the main body 11 and the pipe end is eccentric can be obtained by the conventional deflector spinning based on drawing. It is a shape that cannot be integrally formed for the first time by the decentering and eccentric press forming method of the present invention.
[0040]
2, 6, 7, and 8, it has been assumed that the center axis L1 of the main body 11 and the center axis L2 of the deflected portion exist in the same vertical plane. The deflection direction in the deflection press forming of the present invention is not limited to the case where the center axis of the deflection portion is in such the same vertical plane. For example, as shown in FIG. 9, when it is assumed that the central axis L 1 of the main body 11 extends in the x-axis direction of the xyz three-dimensional orthogonal coordinate system, the pipe end deviated with respect to the main body 11. The central axis L2 at 31 may extend in the yz synthesis direction obtained by synthesizing the y-axis direction and the z-axis direction of the xyz three-dimensional orthogonal coordinate system. That is, according to the deflected press forming method of the present invention, the tube end of the product can be deflected in an arbitrary direction.
[0041]
Since the eccentric and / or eccentric press forming method of the present invention is basically press forming, depending on the setting of the shapes of the movable die 21 and the fixed die 23, a metal pipe can be used for all or a part of the press-formed product. An irregular cross-sectional shape different from the cross-sectional shape (true circle) of No. 10 can be provided. For example, in addition to the perfect circular shape shown in FIG. 10A, a rectangular shape such as a square or a rectangle (see FIG. 10B), a polygonal shape such as a hexagon (see FIG. 10C), or a star shape An irregular cross-sectional shape such as a shape (see FIG. 10D) can be provided.
[0042]
In addition, as shown in FIG. 11, the movable die 21 and the fixed die 23 are locally formed with concave portions (26, 27) and convex portions (28, 29) as other shaping portions, so that the metal pipe is formed. 10 may have a local uneven shape.
[0043]
FIG. 12 shows an example of a catalytic converter case formed using the present method and apparatus. An end portion 41 of the case is formed eccentrically with respect to the main body portion 42, and a sensor seat portion 44 is formed at a portion 43 formed by using a tapered portion of a reduced diameter portion of the metal pipe 10 as a starting material. It is formed to project locally. The seat portion 44 is formed integrally with the metal pipe 10 during press forming by providing a shaping portion such as the concave portion 26 in FIG. By drilling the mounting hole 45 in the seat portion 44 by post-processing, a sensor (for example, a sensor for measuring oxygen concentration or temperature) can be mounted on the seat portion 44 through the mounting hole 45.
[0044]
FIGS. 13A and 13B show another example of a catalytic converter case formed using the present method and apparatus. In the example of FIG. 13A, the outlet end 46 of the case is coaxial with the main body 42, whereas the inlet end 41 of the case is deviated from the main body 42. In the example of FIG. 13B in which two catalytic converter cases are connected in parallel, the outlet end 46 of each case is coaxial with the main body 42, whereas the inlet end 41 of each case is connected. Is eccentric with respect to the main body 42. In each case, a seat 44 for the sensor 47 is formed near the root of the inlet end 41. As described above, according to the molding method of the present invention, the inlet end 41 of the catalytic converter case can be deflected or eccentric in an arbitrary direction, so that the degree of freedom in designing the catalytic converter case increases. Further, in particular, in the case of FIG. 13B, the inlet end 41 of each converter case is eccentric, so that the gap (hole pitch) between the ventilation holes of the flange component 48 connecting the two inlet ends 41 is formed. Q) can be small. In other words, two relatively large-diameter converter cases can be arranged in parallel without increasing the hole pitch Q in the flange component 48. Thus, the hydraulic press molding method and apparatus of the present case are extremely useful for molding or manufacturing a catalytic converter case.
[0045]
The present invention is applicable not only to the molding or manufacturing of the catalytic converter case, but also to the molding or manufacturing of other hollow metal products, for example, pipes constituting an automotive piping system, a case of an exhaust muffler, or a collection portion of an exhaust manifold. It goes without saying that it is applicable to manufacturing.
[0046]
The material of the hollow metal material 10 serving as a starting material may be any metal such as an iron-based material other than SUS and an aluminum-based material. Further, in each of the above cases, the wire length adjusting section 25 protrudes from the second press mold 23 toward the first press mold 21, but may be provided in the second press mold 23 in a recessed state (that is, the recess is provided). ).
[0047]
【The invention's effect】
As described above in detail, according to the hydraulic press forming method of the present invention, even a complicated shape that cannot be formed by the conventional spinning process can be formed inexpensively and quickly without a product defect. It can be integrally molded. Further, according to the hydraulic press forming apparatus of the present invention, the above hydraulic press forming method can be reliably performed.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a forming apparatus and a metal pipe before pressing.
FIG. 2 is a sectional view showing the state of the device and the deflected intermediate product after pressing.
3 shows a cross-sectional shape of the intermediate product of FIG. 2, (A) is a cross-sectional view taken along line AA of FIG. 2, and (B) is a cross-sectional view taken along line BB of FIG.
FIG. 4 is a sectional view when the intermediate product of FIG. 2 is cut and commercialized.
FIG. 5 is a sectional view showing an example of eccentric molding.
FIG. 6 is a sectional view showing another example of declination molding.
FIG. 7 is a sectional view showing another example of declination molding.
FIG. 8 is a cross-sectional view showing an example of decentering and eccentric molding.
FIG. 9 is a cross-sectional view showing another example of declination molding.
FIGS. 10A to 10D are cross-sectional views showing examples of the shape of a product cross section.
FIG. 11 is a sectional view showing an example of forming a local uneven shape.
FIG. 12 is a perspective view showing an application example of the present invention to an automobile part.
13A and 13B are perspective views showing application examples of the present invention.
[Explanation of symbols]
10: Metal pipe (hollow metal material), 11: Main body of metal pipe, 12: Reduced diameter of metal pipe, 13, 14: Seal jig, 15: Pressure adjusting pump mechanism (13 to 15: hydraulic pressure adjustment) Means 21) a movable mold as a first press mold, 22 a main shaping part of the movable mold, 23 a fixed mold as a second press mold (21 and 23 constitute press molding means), 24: fixed type sub-shape portion; 25: fixed type wire length adjusting portion; L1, L2, L3, L4: axis, P: virtual center plane, S: cutting line.

Claims

A first press die provided with a main shaping portion, a second shaping portion cooperating with the main shaping portion of the first press die, and a second press portion provided with a wire length adjusting portion connected to the sub shaping portion A step of preparing a molding device consisting of a press die,
Filling a liquid into a hollow metal material held between the first and second press dies of the molding device;
Press forming a metal material filled with a liquid therein with the first and second press dies, and the main shaping portion is pressed by the shaping action of the metal material wall by the wire length adjusting portion. A portion pressed between the main shaping portion of the first press die and the sub shaping portion of the second press die while preventing the occurrence of product defects on the side opposite to the pressing side; A method of hydraulic press molding of a hollow metal product, wherein a shape is provided such that the metal is decentered and / or eccentric with respect to other parts.

By cutting off the portion corresponding to the wire length adjusting portion from the press-formed product obtained in the pressing step, a hollow metal product having a desired declination and / or eccentric shape at or near the end of the product is obtained. The method for hydraulically press-forming a hollow metal product according to claim 1, wherein:

The hollow metal material is a metal pipe having a pipe-shaped main body portion and a reduced diameter portion smaller in diameter than the main body portion,
The longitudinal line length of the surface of the metal pipe reduced diameter portion, and the portion of the press-formed product obtained in the pressing step, which is formed and shaped by the sub-shape portion and the wire length adjusting portion of the second press die. The shape of the second press die or the shape of the metal pipe is set such that the wire length in the longitudinal direction matches or approximates the length of the hollow metal product according to claim 1 or 2. Hydraulic press molding method.

A longitudinal line length of the surface of the metal pipe reduced diameter portion, and a maximum line length in a longitudinal direction of a portion formed by the main forming portion of the first press die in the press-formed product obtained in the pressing step; 4. The method according to claim 3, wherein the shape of the first press die or the shape of the metal pipe is set such that the shape of the first press die or the shape of the metal pipe is matched or approximated.

The first and second press dies and the hollow metal material held between the two press dies are configured to be symmetrical with respect to the wire length adjusting part, and after the pressing process, A hydraulic press for hollow metal products according to any one of claims 1 to 4, wherein two hollow metal products having a desired declination and / or eccentric shape are obtained at or near the end. Molding method.

A hydraulic press forming apparatus comprising: a liquid pressure adjusting means for adjusting a liquid pressure of a liquid filled in a hollow metal material; and press forming means including first and second press dies capable of relatively approaching and separating. hand,
The first press mold is provided with a main shaping portion for applying a shape by pressing a metal material filled with liquid,
The second press die includes a sub-shape portion cooperating with the main press portion of the first press die, and the main press portion connected to the sub-shape portion and press-formed by the first and second press dies. A hydraulic press forming apparatus, comprising: a wire length adjusting unit for preventing a product defect from being generated on a side opposite to a side pressed by a shape part.