JP2004202571A

JP2004202571A - Deformed pipe as manufactured for bulging, hydrostatic bulging device and method, and bulged product

Info

Publication number: JP2004202571A
Application number: JP2003020962A
Authority: JP
Inventors: Atsushi Tomizawa; 淳富澤; Masayasu Kojima; 正康小嶋
Original assignee: Mitsubishi Motors Corp; Sumitomo Metal Industries Ltd; Sumitomo Pipe and Tube Co Ltd
Current assignee: Mitsubishi Motors Corp; Nippon Steel Corp; Nippon Steel Pipe Co Ltd
Priority date: 2002-11-08
Filing date: 2003-01-29
Publication date: 2004-07-22
Anticipated expiration: 2023-01-29
Also published as: JP4060723B2

Abstract

<P>PROBLEM TO BE SOLVED: To attain a larger pipe expansion ratio than before by enabling a pushing process from a pipe end in the axial direction. <P>SOLUTION: A deformed pipe as manufactured 11 for bulging has its outer diameter and circumference gradually increasing or decreasing from one end to the other end in its axial direction. A parallel portion 11a or 11b is formed at least on one end of the pipe. Even in the case of the hydrostatic bulging of a deformed pipe of which cross sectional shape changes like a tapered pipe, a larger pipe expansion ratio than before is attainable due to the feasibility of giving an axial push as well as an internal pressure. Further, connection with other component or inserting connection can be facilitated. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、液圧バルジ加工に供する異形素管、及び、この異形素管を液圧バルジ加工する液圧バルジ加工装置、液圧バルジ加工方法、並びに、液圧バルジ加工を施されたバルジ加工品に関するものである。
【０００２】
【従来の技術】
液圧バルジ加工には、通常の成形法に比べて以下の特長がある。
▲１▼ 長手方向に断面形状の異なるやや複雑な形状を得ることができるため、従来は溶接で組み付けられていた部品の一体成形が可能になる。
【０００３】
▲２▼ 製品の全体に亘って加工硬化が得やすいため、軟質な素管を用いても高強度な製品を得ることができる。
▲３▼ スプリングバックが少なく、製品の寸法精度が良好である（形状凍結性が良好である）ため、手直しの工程が省略できる。
【０００４】
以上のような優れた特長が評価され、近年、特に自動車部品の製造工程に採用されるようになってきた。
一般的な管の液圧バルジ加工工程は、素材となる長手方向に均一な円断面を有するストレートな管（以下、「ストレート素管」と呼ぶ。）を、（１）曲げ加工、（２）押し潰し加工（以下、「予成形」と呼ぶ。）、（３）液圧バルジ加工、の一連の加工工程を経ることによって製品を製造するものである。
【０００５】
図１８に示す最終工程である液圧バルジ加工では、上下の金型１，２内にセットされたストレート素管Ｐ１の中に注入孔３を通じて加工液を注入し、内圧を高めることに加えて、シール工具を兼ねた軸押し工具４，５によって両管端から軸方向に素管Ｐ１を押し込む（以下、「軸押し」と呼ぶ。）ことで、種々の断面形状を有する製品Ｐ２を製造する。なお、シール工具を兼ねた軸押し工具４，５は図示しない油圧シリンダに接続されており、バルジ加工中に軸方向位置或いは軸押し力が制御されている。
【０００６】
ここで、液圧バルジ加工における、管端からの軸方向への軸押しは、膨出時のメタルフローを助長せしめて拡管限界を向上させる効果があり、極めて重要である。すなわち、軸押しを実施することなく内圧増加のみで加工を行うと、ストレート素管Ｐ１の膨出に対応して板厚が著しく減少するために、加工中の早い段階で材料の破断に至り、限られた成形範囲（拡管限界）しか得られないのである。
【０００７】
しかしながら、上記の液圧バルジ加工においても以下に述べるような問題がある。
すなわち、軸方向に断面形状の異なるやや複雑な形状を得ることができるといっても、それには限界がある。周長増加率＝｛（当該部位の製品の外周長／素管の円周長）−１｝×１００％と定義すれば、製品の形状要求性能や素管の材質・板厚にもよるが、軸押しが有効な管端部領域は除いて、周長増加率は高々２５％程度が限界である。このような制約条件のもとで、製品の形状設計の自由度を上げ、より複雑な断面形状を有する製品を得るためには、素管形状の工夫が必要である。
【０００８】
この問題に対する一つの有力な対策は、ストレート素管に代えて略円錐状の素管（以下、「テーパ素管」と呼ぶ。）を用いることであり、ストレート素管での成形が困難な部品、例えば軸方向に沿って大きく周長が変化する部品に対しても周長増加率を低く抑えることができる（例えば特許文献１参照。）。
【０００９】
【特許文献１】
特開２００１−３２１８４２号公報（第１頁、図２）
【００１０】
【発明が解決しようとする課題】
しかしながら、テーパ素管などの軸方向に断面形状が変化する異形鋼管を用いてバルジ加工を行う場合に、図１８に示す従来のストレート素管のバルジ加工用のシール工具を使用した場合には、軸押しは困難である。図１９に示すように、大径側ではテーパ素管ＴＰ１を押し込むことができず、また、小径側では軸押し加工に伴いテーパ素管ＴＰ１の内外面の拘束が不十分となってシール漏れが発生してしまうからである。
【００１１】
従って、テーパ素管ＴＰ１の液圧バルジ加工では、図２０に示すような、先端部がテーパ状のシール工具６，７やそれに類似した端面シール等を使用し、軸押しを行わない方法が一般的であり、テーパ素管ＴＰ１の軸押しが出来ないため、限られた成形範囲（拡管限界）しか得られないという問題がある。このようなことから、テーパ素管などの軸方向に断面形状が変化する異形鋼管のバルジ加工を行う場合でも、管端からの軸方向への押し加工を可能にする技術が望まれていた。なお、図２０中のＴＰ２は管端部を成形した後のテーパ素管、ＰＴ３は製品を示す。
【００１２】
また、これらの問題とは別に、テーパ素管などの異形鋼管を素材としてハイドロフォームした製品ＰＴ３は、図１２（ａ）に示すように、管端部が斜めにθだけ傾いているため、他の部材との溶接・接合が容易ではない。更に、管端を他部品に差し込んで結合する（以下、「差し込み結合」という。）場合の位置決め及び溶接が困難である。そのため、後工程でバルジ加工した製品の端部を切り落としたり、後加工を付加する場合もあった。
【００１３】
本発明は、上記した従来の問題点に鑑みてなされたものであり、軸方向に横断面形状が変化する異形鋼管を採用した液圧バルジ加工において、管端からの軸方向への押し加工を可能にして従来以上に大きな拡管率を得ることができるバルジ加工用異形素管、及び、液圧バルジ加工装置、液圧バルジ加工方法、並びに、バルジ加工品を提供することを目的としている。
【００１４】
【課題を解決するための手段】
上記した目的を達成するために、本発明に係るバルジ加工用異形素管は、軸方向の一方から他方にかけて外径が漸次増加又は減少する周長を有すると共に、少なくとも一方端側に平行部を形成することとしている。
【００１５】
そして、このような構成の本発明に係る異形素管を、上下の両金型本体の少なくとも一方の端側内面と、この端側内面に対応する軸押し工具の外面に夫々平行部を設けた本発明に係る液圧バルジ加工装置の金型内にセットすれば、内圧付与と共に軸方向への押し込みが可能になって、液圧バルジ加工が施された本発明に係るバルジ加工品では、従来以上に大きな拡管率を得ることが可能になり、また、他の部品との接合も容易に行なえるようになる。
【００１６】
【発明の実施の形態】
本発明に係るバルジ加工用異形素管１１は、バルジ加工に供される異形素管であって、図６（ａ）（ｂ）にその断面を示すように、軸方向の一方から他方にかけて外径が漸次増加又は減少する周長を有すると共に、少なくとも一方端（図６に示した例では小径側及び大径側の両端）側に平行部１１ａ，１１ｂを形成したものであり、前記平行部１１ａ，１１ｂはバルジ加工での軸押し量とシールに必要な長さの和以上の長さを有することが望ましい。
【００１７】
図６（ａ）に示す実施例を図１５（ａ）（ｂ）を用いて更に詳細に説明する。図１５（ａ）は最も基本的な形態を示すもので、円断面を有するテーパ部の両端に円断面を有する平行部１１ａ，１１ｂを形成したものである。また、図１５（ｂ）は長方形断面を有するテーパ部の両端に長方形断面を有する平行部１１ａ，１１ｂを設けたものである。図１５（ｂ）に示す例では、平行部１１ａ，１１ｂは全長に亘り小径側１１ａでは図８（ａ）に示す断面、大径側１１ｂでは図９（ｃ）に示す断面を有している。
【００１８】
次に、図６（ｂ）に示す実施例の詳細を図１６（ａ）（ｂ）を用いて説明する。
図１６（ａ）は円断面を有するテーパ部の両端に円断面を有する平行部１１ａ，１１ｂを形成したものであり、大径側の平行部１１ｂと中央のテーパ部との間に移行部１１ｃを有している。また、図１６（ｂ）は長方形断面を有するテーパ部の両端に長方形断面を有する平行部１１ａ，１１ｂを設けたものであり、大径側の平行部１１ｂと中央のテーパ部との間に前記と同様に移行部１１ｃを有している。
【００１９】
これら図１５（ｂ）や図１６（ｂ）では両端部に形成した平行部１１ａ，１１ｂの形状が単に長方形断面を有するものを示したが、平行部１１ａ，１１ｂの形状は、図１０に示すような台形断面形状や、図１１に示すような断面形状、或いは、図示していない多角形の断面形状などであっても良い。更に、バルジ加工後の最終端面形状が製品の端面形状と一致していれば、材料歩留りが向上することになり、好適である。
【００２０】
また、図１５（ｂ）や図１６（ｂ）においては中央のテーパ部も長方形断面としたものを示しているが、特に中央部が長方形断面である理由はなく、図１５（ａ）や図１６（ａ）のように円断面でも当然良いし、バルジ加工の金型に挿入できるように曲げ加工や上下左右からの押し潰し加工を行ったものでも良い。
【００２１】
図１４（ａ）に示す様な円断面を有するテーパ部の大径側端部にのみ平行部１１ｂを有する本発明に係る異形素管１１の製造方法について説明する。
図１４（ａ）に示した形状の本発明に係る異形素管１１は、図１４（ｂ）に示した形状の板を単純曲げし、ア−イとア’−イ’、ウ−エとウ’−エ’、イ−オとウ−オ、イ’−オとウ’−オの端部を接合すれば、図１４（ａ）に示したような大径側端部にのみ平行部１１ｂを有する本発明に係る異形素管１１が製造できる。
【００２２】
一方、図１４（ｃ）には、図１４（ｂ）を破線で併記すると共に、これに近い台形形状を実線で示している。
実線と破線との比較で明らかなように、図１４（ｃ）に実線で示す台形を単純曲げした場合には、イウオの領域とイ’ウ’オの領域に肉余りを生じてしまう。すなわち、台形形状を素材とした板巻き工程では、本発明に係る異形素管１１のように、端部に平行部１１ｂを有する異形素管の製造は困難である。
【００２３】
最も単純な方法は、図１４を用いて説明したように、本発明に係る異形素管１１の展開形状を有する板を単純曲げして接合する方法であるが、次に、これ以外の方法で、前述の図１５、図１６に示す形状の本発明に係る異形素管１１を製造する方法について説明する。
【００２４】
図１５（ａ）に示す形状の場合は、例えば単なるテーパ管を素材として小径側は穴拡げ加工、大径側は絞り加工を行うことによって得ることができる。また、図１５（ｂ）に示す形状の場合は、上記に加えて中央の胴長部に押し潰し加工を行うことによって得ることができる。
【００２５】
図１６（ａ）に示す形状の場合は、例えば単なるテーパ管を素材として小径側、大径側共に穴拡げ加工を行えば良い。また、図１６（ｂ）に示す形状の場合は、上記に加えて中央の胴長部に押し潰し加工を行うことによって得ることができる。
【００２６】
図７は本発明の別の態様を示したものである。図７（ａ）に示したものは長方形断面のテーパ部の両端に長方形断面の平行部１１ａ，１１ｂが形成されている。
【００２７】
この図７に示した例では、単なるテーパ管に小径側の平行部１１ａではδＬ＋Ｌ０、大径側の平行部１１ｂではδＬ’＋Ｌ０ ’の部分に対応する製品の部分に、製品と略同一の幅、高さの寸法を有する矩形断面を形成せしめ、かつ、コーナ部の曲率半径Ｒを後述のように決定することで、次工程であるバルジ加工で後述の金型本体１２，１３とシール工具を兼ねた軸押し工具１４，１５により、バルジ加工時の軸押し加工で座屈などが発生せず極めてスムーズな材料の押し込みが可能になる。
【００２８】
図８は図７（ａ）（ｂ）に示した例における小径側の平行部１１ａの各断面形状を説明する図であり、（ａ）から（ｃ）の断面の幅Ｗ０と高さＨ０はほぼ一定であり、コーナ部の曲率半径Ｒを予成形により段階的に変化させている。なお、図８の（ｃ）は端部、（ａ）は小径側端部より軸方向にδＬ＋Ｌ０だけ離れた位置、（ｂ）はそれらの中間位置での断面図を示している。
【００２９】
すなわち、図８（ａ）〜（ｃ）に示すように、予成形した端部でのコーナ部の曲率半径をＲ０、小径側端部より軸方向にδＬ＋Ｌ０だけ離れた位置のコーナ部の曲率半径をＲ１、小径側端部より軸方向にＸだけ離れた位置のコーナ部の曲率半径をＲ（ｘ）とすると、
Ｒ０ ≧Ｒ（ｘ）≧Ｒ１
としている。この図８の例では、４つのコーナ部の曲率半径を同一にしたが、勿論これらを同一にする必要はない。
【００３０】
さらに詳細には、単なるテーパ管の両端部を基準周長とした、端部からの位置Ｘにおける周長差δｄ（ｘ）は、
δｄ（ｘ）＝π・（Ｄ０ ’−Ｄ０）・Ｘ／ＬＴ
となる。
【００３１】
予成形で端部の断面を幅Ｗ０、高さＨ０の矩形に形成する際、上記周長差δｄ（ｘ）に対応して、図８に示すようにコーナ部の曲率半径Ｒ（ｘ）の寸法を軸方向位置で変化させることによって、適正な予成形形状の決定が可能である。
【００３２】
図９は図７（ａ）に示した例における大径側の平行部１１ｂの各断面形状を説明する図であり、（ａ）から（ｃ）の断面の幅Ｗ０ ’と高さＨ０ ’はほぼ一定であり、コーナ部の曲率半径Ｒを予成形により段階的に変化させている。なお、図９の（ｃ）は端部、（ａ）は大径側端部より軸方向にδＬ’＋Ｌ０ ’だけ離れた位置、（ｂ）はそれらの中間位置での断面図を示している。
【００３３】
すなわち、図９（ａ）〜（ｃ）に示すように、予成形した端部でのコーナ部の曲率半径をＲ０ ’、大径側端部より軸方向にδＬ’＋Ｌ０ ’だけ離れた位置のコーナ部の曲率半径をＲ１ ’、大径側端部より軸方向にＸだけ離れた位置のコーナ部の曲率半径をＲ’（ｘ）とすると、
Ｒ０ ’≦Ｒ’（ｘ）≦Ｒ１ ’
としている。
【００３４】
また、単なるテーパ管の両端部を基準周長とした、端部からの位置Ｘにおける周長差δｄ（ｘ）は、
δｄ（ｘ）＝π・（Ｄ０ ’−Ｄ０）・Ｘ／ＬＴ
となる。
【００３５】
端部の断面を幅Ｗ０ ’、高さＨ０ ’の矩形に形成する際、上記周長差δｄ（ｘ）に対応して、図９に示すようにコーナ部の曲率半径Ｒ’（ｘ）の寸法を軸方向位置で変化させることによって、適正な形状の決定が可能である。
【００３６】
上記は矩形断面の場合を説明したものであるが、矩形の組み合わせ形状や多角形形状でも、同様な方法で、バルジ加工時の極めて安定した軸押しを可能にせしめることが可能である。
【００３７】
製品が台形断面を有する場合の例を図１０に、また、製品がＬ字型の断面を有する場合の例を図１１に示している。いずれも、大径側の予成形形状の例であり（ｃ）が大径側端部、（ａ）が大径側端部より軸方向にδＬ’＋Ｌ０ ’だけ離れた位置、（ｂ）はそれらの中間位置での夫々断面図を示したものである。
【００３８】
また、本発明に係る液圧バルジ加工装置は、内側に例えば図１、図４や図１７のようなキャビティを形成した上下の金型本体１２，１３と、これら両金型本体１２，１３とで請求項１〜３の何れか記載の異形素管１１の両端部を夫々挟持状に保持すべく、両金型本体１２，１３の夫々の端部間に先端部を挿入されるシール工具を兼ねた軸押し工具１４，１５とを備え、前記どちらか一方の軸押し工具１５には加工液の注入孔１６が設けられ、また、両金型本体１２，１３の少なくとも一方の端側（図１、図４及び図１７に示した例では小径側及び大径側の両端側）内面と、この端側内面に対応する軸押し工具の外面には夫々平行部１２ａ，１２ｂ、１３ａ，１３ｂ、１４ａ，１５ａが設けられているものである。この軸押し工具１４，１５の外面の平行部１４ａ，１５ａは、軸押し時に内面から素管を拘束し、スムーズな変形を可能ならしめる役割を有している。
【００３９】
そして、この液圧バルジ加工装置において、小径部側の軸押し量をδＬ、大径部側の軸押し量をδＬ’、小径部側のシールに必要な長さをＬ０、大径部側のシールに必要な長さをＬ０ ’とした場合、両金型本体１２，１３の少なくとも一方の端側（図１、図４及び図１７に示した例では小径側及び大径側の両端側）内面に設けられた平行部１２ａ，１２ｂ、１３ａ，１３ｂの長さは、小径部側に設けられている場合にはδＬ＋Ｌ０以上、大径部側に設けられている場合にはδＬ’＋Ｌ０ ’以上であり、この金型本体１２，１３に設けられた平行部１２ａ，１２ｂ、１３ａ，１３ｂに対応する軸押し工具１４，１５の平行部１４ａ，１５ａの長さは、小径部側に設けられる場合にはδＬ＋Ｌ０以上、大径部側に設けられる場合にはＬ０ ’以上であることが望ましい。
【００４０】
ところで、上記の本発明に係る液圧バルジ加工装置において、小径側（大径側）のシール工具を兼ねた軸押し工具１４（１５）の先端部は、異形素管１１の素材となる単なるテーパ管ＰＴ或いは異形素管１１の小径側端部（大径側端部）に挿入可能でなければならず、また、平行部１４ａ（１５ａ）は、軸押し完了時における平行部１４ａ（１５ａ）の最先端部分と異形素管１１の内面との間に隙間が生じないことが望ましい。
【００４１】
例えば、図１に示したように、異形素管１１の素材となる単なるテーパ管ＰＴを上下の金型本体１２，１３にセットした後、管端部に形成する平行部１１ａ，１１ｂを液圧バルジ加工を実施するに先立って上下の金型本体１２，１３内で形成する場合には、
【００４２】
Ａ．小径側のシール工具を兼ねた軸押し工具１４（図２参照）
先端の局部的凹部を無視した包絡線の周長ＳＤ０：
ＳＤ０ ≦（Ｄ０ −２ｔ／ｃｏｓθ）×π
但し、Ｄ０：小径部の外径
ｔ：異形素管１１の肉厚
θ＝ｔａｎ−１｛（Ｄ０ ’−Ｄ０）／（２・ＬＴ）｝
ＬＴ：テーパ管ＰＴの長さ
Ｄ０ ’：大径部の外径
【００４３】
Ｂ．大径側のシール工具を兼ねた軸押し工具１５（図３参照）
先端の局部的凹部を無視した包絡線の周長ＳＤ０ ’：
ＳＤ０ ’≦｛Ｄ０ ’−２ｔ／ｃｏｓθ｝×π
【００４４】
一方、図４に示したように、異形素管１１の管端部に形成する平行部１１ａ，１１ｂを、上下の金型本体１２，１３にセットする前に、予め形成してある場合には、
【００４５】
Ａ’．小径側のシール工具を兼ねた軸押し工具１４の先端部の周長ＳＤ０：
ＳＤ０ ≦平行部１４ａの周長ＳＤ
Ｂ’．大径側のシール工具を兼ねた軸押し工具１５の先端部の周長ＳＤ０ ’：
ＳＤ０ ’≦平行部１５ａの周長ＳＤ’
が必要である。
【００４６】
上記の本発明に係る液圧バルジ加工装置を用いてバルジ加工品１７を成形する場合には、例えば本発明に係る異形素管１１の素材である単なるテーパ管ＰＴを、図１（ａ）に示すように、本発明に係る液圧バルジ加工装置の一対の金型本体１２，１３内にセットする。次に、バルジ加工に先立ち、シール工具を兼ねた軸押し工具１４，１５を軸方向に移動させ、金型本体１２，１３と軸押し工具１４，１５にはさまれたテーパ管ＰＴの管端、例えば両端に、図１（ｂ）に示すように、平行部１１ａ，１１ｂを形成し、本発明に係る異形素管１１となす。また、この時、軸押し工具１４，１５による異形素管１１の軸押しのタイミングを同一とせず、例えば軸押し工具１５をある程度押し付けた段階で軸押し工具１４の押し付けを開始しても良く、異形素管１１が金型本体１２，１３内で安定する軸押しタイミングを選定すれば良い。
【００４７】
この時、上述の寸法を基準にして金型本体１２，１３とシール工具を兼ねた軸押し工具１４，１５の寸法設計を行えば、軸押し工具１４，１５をテーパ管ＴＰにスムーズに挿入することができる。
【００４８】
図１（ｂ）の状態では、図２（ｂ）、図３（ｂ）に示すように、テーパ管ＴＰの両管端には、小径側にＬ０以上望ましくはδＬ＋Ｌ０以上、大径側にＬ０ ’以上の長さの平行部１１ａ，１１ｂが形成され（本発明の異形素管１１）、内圧が付加された加工液のシールが完全に行われる状態になっている。
【００４９】
その後、加工液の内圧を上昇させつつ、更に軸押し工具１４，１５を軸方向に移動せしめ、液圧バルジ加工を施し、図１（ｃ）に示したように、本発明に係るバルジ加工品１７を形成する。
【００５０】
すなわち、本発明に係る異形素管１１を本発明に係る液圧バルジ加工装置にセットして行うバルジ加工では、軸押しが可能になる結果、本発明に係るバルジ加工品１７にあっては、従来以上に大きな拡管率を得ることが可能になり、また、バルジ加工品１７の端面は、図１２（ｂ）に示すように、軸心に対して垂直であるので、他の部品との接合も容易に行なえるようになり、差し込み結合の位置決め及び溶接が可能となる。
【００５１】
図５は、図１に示した実施例と別の実施例を示したもので、両金型本体１２，１３の両端部に平行部１２ａ，１２ｂ、１３ａ，１３ｂを有するのは同様であるが、両金型本体１２，１３の大径側の平行部１２ｂ，１３ｂの内側のキャビティが、図１に示した例のように局部的に狭まることなく、前記平行部１２ｂ，１３ｂの内側のキャビティが大径端を基準にして軸方向に単調に減少するものを示している。
【００５２】
この場合には、軸押しの抵抗が小さく、メタルフローとしても有利であるため、図５に示すように、成形範囲（拡管限界）の拡大効果はさらに大きくなる。従って、本発明に係る液圧バルジ加工装置にあっては、金型本体１２，１３のキャビティ形状を図５に示す形状に設計することが推奨される。
【００５３】
一方、自動車部品においては、製品の端部の断面形状が矩形に近いものや矩形の組み合わせ、或いは多角形等の形状も多い。
【００５４】
図１７は図７（ａ）に示す本発明の異形素管１１を用いた場合の本発明の実施例を示している。すなわち、前述の図７（ａ）に示す異形素管１１を金型本体１２，１３内にセットする。図７（ｂ）に本発明の異形素管１１の小径側の拡大図を示しているが、その小径側平行部１１ａの断面形状は図８に示している。このような断面形状の異形素管１１に対し、本発明の一例を示すシール工具を兼ねた軸押し工具１４，１５を用いて成形を行う。すなわち、図７（ｃ）は小径側のシール工具を兼ねた軸押し工具１４を示しているが、幅Ｗ０ −２ｔ、高さＨ０ −２ｔ、角部はＲ１の平行部１４ａを有している。
【００５５】
図１７（ａ）の状態から端部に軸押し工具１４，１５を押し込み、図１７（ｂ）の段階で異形素管１１の端部の成形が終了し、ちょうど図１６（ｂ）に示す異形素管１１を得ることができると共に、内圧が付加された加工液のシールが完全に行われた状態になっている。当然のことながら、実際の加工においては、異形素管１１の端部の平行部１１ａ，１１ｂはＲ寸法や平行部１１ａ，１１ｂの真直度が多少変動しても本発明の効果は認められ、本発明の技術的思想から外れるものではない。
【００５６】
その後、加工液の内圧を上昇させつつ、更に軸押し工具１４，１５を軸方向に移動せしめ、液圧バルジ加工を施した本発明に係るバルジ加工品１７を得ることができる。
【００５７】
なお、バルジ加工に先立って行う管端の平行部１１ａ，１１ｂの成形を、予成形やそれ以前の段階で行っても良い。絞り加工、穴拡げ加工、スウェージング加工、スピング加工など既存の加工法やその組み合わせによって実施できる。
【００５８】
本発明に係る液圧バルジ加工装置の構成部材であるシール工具を兼ねた軸押し工具１４，１５のシール構成の例を図１３に示している。
（ａ）は異形素管１１の端面と接する端面１４ｂ，１５ｂでシールする場合の例、（ｂ）は同じく端面１４ｂ，１５ｂに突起１４ｃ，１５ｃを付与した例、（ｃ）は平行部１４ａ，１５ａの端面１４ｂ，１５ｂとの境界部に段差１４ｄ，１５ｄを付与した例、（ｄ）は平行部１４ａ，１５ａにＯリング１８を付与した例を示しているが、いずれも前述の平行部１４ａ，１５ａと周長の範囲を満足するものである。
【００５９】
今回示した例は、あくまでも本発明の１つの具体例を示すものであり、金型本体１２，１３のキャビティの形状も比較的簡単な形状のものを示しているが、当然、通常の自動車部品に代表される３次元の複雑な形状でも良い。
【００６０】
また、上記の例では、小径側と大径側の両方から軸押しするものを示しているが、本発明をどちらか片側に適用し、他方は従来から行われている例えば図１７に示すような軸押しが無い方式を採用しても良い。軸押しの効果は製品形状によって変化するため、その場合に応じて本発明の適用範囲を決定すればよいのである。
【００６１】
さらに、上記の例では主として、異形素管１１の素材として単純なテーパ管ＰＴの場合を記述したが、単純なテーパ管ＰＴを組み合わせて溶接したものや、テーパ管と通常のストレート管を組み合わせた場合にも、両端部それぞれが単純なテーパ管の一部と近似できるため、本発明の異形素管１１の素材として適用できる。
【００６２】
【発明の効果】
以上説明したように、本発明によれば、例えばテーパ管のように軸方向に横断面形状が変化する異形鋼管の液圧バルジ加工を行う場合でも、内圧付与と共に軸方向への押し込みが可能になって、従来以上に大きな拡管率を得ることが可能になり、また、他の部品との接合や差し込み結合も容易に行なえるようになる。
【図面の簡単な説明】
【図１】本発明の第１実施例を示す説明図で、異形素管の管端部に形成する平行部を、液圧バルジ加工に先立って行う場合の一例を示し、（ａ）はテーパ管の金型本体へのセッティング状態を示した縦断面図、（ｂ）は液圧バルジ加工前に平行部を形成した状態を示した縦断面図、（ｃ）は液圧バルジ加工終了後の状態を示した縦断面図である。
【図２】小径側の上金型本体とシール工具を兼ねた軸押し工具と異形素管端部の関係を表す図１（ａ）〜（ｃ）に相当する図である。
【図３】大径側の上金型本体とシール工具を兼ねた軸押し工具と異形素管端部の関係を表す図１（ａ）〜（ｃ）に相当する図である。
【図４】本発明の第２実施例を示す説明図で、異形素管の管端部の平行部を予め形成してある場合の一例を示し、（ａ）は異形素管の金型本体へのセッティング状態を示した縦断面図、（ｂ）は液圧バルジ加工前の状態を示した縦断面図、（ｃ）は液圧バルジ加工終了後の状態を示した縦断面図である。
【図５】本発明の第３実施例を示す説明図で、大径側の平行部の内側のキャビティが大径端を基準にして軸方向に単調に減少する例を示し、（ａ）はテーパ管の金型本体へのセッティング状態を示した縦断面図、（ｂ）は液圧バルジ加工前に平行部を形成した状態を示した縦断面図、（ｃ）は液圧バルジ加工終了後の状態を示した縦断面図である。
【図６】（ａ）（ｂ）は本発明の異形素管の素材であるテーパ管の一例を示した縦断面図である。
【図７】異形素管の一実施例を示す図で、（ａ）は全体斜視図を、（ｂ）は小径側の拡大図を、（ｃ）は小径側のシール工具を兼ねた軸押し工具の拡大図を示す。
【図８】製品が矩形断面を有する場合の本発明の異形素管の一例を示した小径側の断面図で、（ａ）は小径側端部より軸方向にδＬ＋Ｌ０だけ離れた位置の断面図、（ｃ）端部の断面図、（ｂ）はそれらの中間位置での断面図である。
【図９】図８と同様の異形素管の一例を示した大径側の断面図で、（ａ）は大径側端部より軸方向にδＬ’＋Ｌ０ ’だけ離れた位置の断面図、（ｃ）は端部の断面図、（ｂ）はそれらの中間位置での断面図である。
【図１０】製品が台形断面を有する場合の図９（ａ）〜（ｃ）と同様の図である。
【図１１】製品がＬ字型の断面を有する場合の図９（ａ）〜（ｃ）と同様の図である。
【図１２】長方形断面を持つ部品の側面にバルジ成形品を接合する場合の説明図で、（ａ）は従来、（ｂ）は本発明のバルジ成形品を示す説明図で、製品の軸方向に対して管端部の傾きを示した説明図、（ｃ）はバルジ成形品の断面図である。
【図１３】（ａ）〜（ｄ）はシール工具を兼ねた軸押し工具のシール構成を夫々説明する図である。
【図１４】大径側端部に平行部を有する本発明に係る異形鋼管を製造する方法について説明する図であり、（ａ）は全体斜視図、（ｂ）は展開図、（ｃ）は（ｂ）に示した展開図に近い台形形状を示した図である。
【図１５】（ａ）は円断面を有するテーパ部の両端に円断面を有する平行部を形成した本発明異形素管の例、（ｂ）は長方形断面を有するテーパ部の両端に長方形断面を有する平行部を設けた本発明異形素管の例を示した図である。
【図１６】（ａ）（ｂ）は図１９（ａ）（ｂ）において大径側の平行部と中央のテーパ部との間に移行部を有した本発明異形素管の例を示した図である。
【図１７】本発明の第４実施例を示す説明図で、異形素管の管端部の平行部を予め形成してある場合の他の例を示し、（ａ）は異形素管の金型本体へのセッティング状態を示した縦断面図、（ｂ）は液圧バルジ加工前の状態を示した縦断面図、（ｃ）は液圧バルジ加工終了後の状態を示した縦断面図である。
【図１８】従来のストレート素管の液圧バルジ加工の説明図で、（ａ）は加工前、（ｂ）加工終了時を示す縦断面図である。
【図１９】従来のストレート素管のシール工具を兼ねた軸押し加工用工具でテーパ素管の軸押しを行った場合の問題点を説明する図である。
【図２０】従来のテーパ素管の液圧バルジ加工工程の説明図で、（ａ）は加工前、（ｂ）内圧付加前、（ｃ）加工終了時を示す縦断面図である。
【符号の説明】
１１異形素管
１１ａ平行部
１１ｂ平行部
１２上金型本体
１２ａ平行部
１２ｂ平行部
１３下金型本体
１３ａ平行部
１３ｂ平行部
１４軸押し工具
１４ａ平行部
１５軸押し工具
１５ａ平行部
１６注入孔
１７バルジ加工品[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a deformed element pipe used for hydraulic bulge processing, a hydraulic bulge processing apparatus, a hydraulic bulge processing method for hydraulically bulging the deformed element pipe, and a bulge processing subjected to hydraulic bulge processing. It is about goods.
[0002]
[Prior art]
The hydraulic bulge processing has the following features compared to normal molding methods.
{Circle around (1)} Since a slightly complicated shape having a different cross-sectional shape in the longitudinal direction can be obtained, it is possible to integrally form components that have been assembled by welding in the past.
[0003]
(2) Since work hardening is easily obtained over the entire product, a high-strength product can be obtained even if a soft blank tube is used.
(3) Since the spring back is small and the dimensional accuracy of the product is good (the shape freezing property is good), the rework process can be omitted.
[0004]
The excellent features as described above have been evaluated, and in recent years, they have been adopted particularly in the manufacturing process of automobile parts.
The general hydraulic bulging process for pipes is a straight pipe (hereinafter referred to as “straight blank pipe”) having a uniform circular cross section in the longitudinal direction, which is a material, (1) bending, (2) A product is manufactured through a series of processing steps of crushing (hereinafter referred to as “preforming”) and (3) hydraulic bulging.
[0005]
In the hydraulic bulging process, which is the final process shown in FIG. 18, in addition to increasing the internal pressure by injecting the processing liquid through the injection hole 3 into the straight base pipe P1 set in the upper and lower molds 1,2. The product P2 having various cross-sectional shapes is manufactured by pushing the raw pipe P1 in the axial direction from both pipe ends by the shaft pushing tools 4 and 5 also serving as a sealing tool (hereinafter referred to as “shaft pushing”). . The shaft pushing tools 4 and 5 that also serve as a sealing tool are connected to a hydraulic cylinder (not shown), and the axial position or the shaft pushing force is controlled during bulging.
[0006]
Here, in the hydraulic bulge processing, the axial pushing from the pipe end in the axial direction has the effect of promoting the metal flow during bulging and improving the expansion limit, and is extremely important. That is, if the processing is performed only by increasing the internal pressure without carrying out the shaft pressing, the plate thickness is remarkably reduced corresponding to the bulging of the straight base tube P1, leading to the fracture of the material at an early stage during processing. Only a limited forming range (expansion limit) can be obtained.
[0007]
However, the above-described hydraulic bulging also has the following problems.
That is, even if it is possible to obtain a slightly complicated shape having a different cross-sectional shape in the axial direction, there is a limit to this. Perimeter increase rate = {(peripheral length of the product at the relevant part / circumferential length of the tube) -1} x 100%, depending on the required shape of the product and the material and thickness of the tube Except for the tube end region where the axial pushing is effective, the maximum increase in circumference is about 25% at most. Under such constraint conditions, in order to increase the degree of freedom of product shape design and to obtain a product having a more complicated cross-sectional shape, it is necessary to devise a raw pipe shape.
[0008]
One effective countermeasure against this problem is to use a substantially conical tube (hereinafter referred to as a “taper tube”) instead of a straight tube, and it is difficult to form a straight tube. For example, the rate of increase in circumference can be kept low even for parts whose circumference varies greatly along the axial direction (see, for example, Patent Document 1).
[0009]
[Patent Document 1]
JP 2001-321842 A (first page, FIG. 2)
[0010]
[Problems to be solved by the invention]
However, when bulging is performed using a deformed steel pipe whose cross-sectional shape changes in the axial direction, such as a taper pipe, when the conventional straight blank pipe bulging seal tool shown in FIG. 18 is used, It is difficult to push the shaft. As shown in FIG. 19, the taper pipe TP1 cannot be pushed in on the large diameter side, and the inner and outer surfaces of the taper pipe TP1 are insufficiently restricted due to the axial pushing process on the small diameter side, resulting in seal leakage. It will occur.
[0011]
Therefore, in the hydraulic bulge processing of the taper pipe TP1, a method of using a sealing tool 6 or 7 having a tapered tip or a similar end face seal as shown in FIG. There is a problem that only a limited forming range (expansion limit) can be obtained because the axial push of the taper pipe TP1 cannot be performed. For this reason, there has been a demand for a technique that enables axial pressing from the pipe end even when bulging a deformed steel pipe whose cross-sectional shape changes in the axial direction, such as a taper pipe. In addition, TP2 in FIG. 20 shows the taper element pipe | tube after shape | molding a pipe end part, PT3 shows a product.
[0012]
In addition to these problems, the product PT3 hydroformed using a deformed steel pipe such as a taper pipe has a pipe end inclined obliquely by θ as shown in FIG. It is not easy to weld and join with other members. Furthermore, positioning and welding are difficult when the pipe end is inserted into another part and connected (hereinafter referred to as “plug-in connection”). For this reason, the end of the bulged product in the subsequent process may be cut off or post-processed may be added.
[0013]
The present invention has been made in view of the above-described conventional problems, and in the hydraulic bulge processing employing a deformed steel pipe whose cross-sectional shape changes in the axial direction, the axial pressing from the pipe end is performed. It is an object of the present invention to provide a deformed element tube for bulge processing that can be obtained with a larger pipe expansion rate, a hydraulic bulge processing device, a hydraulic bulge processing method, and a bulge processed product.
[0014]
[Means for Solving the Problems]
In order to achieve the above-described object, the deformed element pipe for bulge processing according to the present invention has a circumferential length in which the outer diameter gradually increases or decreases from one side to the other side in the axial direction, and at least one parallel end portion is provided on one end side. Trying to form.
[0015]
Then, the deformed element pipe according to the present invention having such a configuration is provided with parallel portions on at least one end inner surface of the upper and lower mold bodies and on the outer surface of the axial pushing tool corresponding to the end inner surface, respectively. If set in the mold of the hydraulic bulge processing apparatus according to the present invention, it is possible to push in the axial direction while applying the internal pressure, and in the bulge processed product according to the present invention subjected to the hydraulic bulge processing, As a result, it becomes possible to obtain a larger tube expansion rate and to easily join other parts.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The deformed element tube 11 for bulge processing according to the present invention is a deformed element tube used for bulge processing, and is shown in FIGS. 6 (a) and 6 (b). The parallel portion 11a, 11b is formed on at least one end (both ends on the small diameter side and the large diameter side in the example shown in FIG. 6) and has a circumferential length in which the diameter gradually increases or decreases. It is desirable that the lengths 11a and 11b have a length that is equal to or greater than the sum of the amount of shaft pressing in bulge processing and the length necessary for sealing.
[0017]
The embodiment shown in FIG. 6 (a) will be described in more detail with reference to FIGS. 15 (a) and 15 (b). FIG. 15A shows the most basic form, in which parallel portions 11a and 11b having a circular cross section are formed at both ends of a tapered portion having a circular cross section. Further, FIG. 15B is a view in which parallel portions 11a and 11b having a rectangular cross section are provided at both ends of a tapered portion having a rectangular cross section. In the example shown in FIG. 15 (b), the parallel parts 11a and 11b have a cross section shown in FIG. 8 (a) on the small diameter side 11a and a cross section shown in FIG. 9 (c) on the large diameter side 11b. .
[0018]
Next, details of the embodiment shown in FIG. 6B will be described with reference to FIGS.
In FIG. 16A, parallel portions 11a and 11b having a circular cross section are formed at both ends of a tapered portion having a circular cross section, and a transition portion 11c is formed between the large diameter side parallel portion 11b and the central tapered portion. have. FIG. 16B is a view in which parallel portions 11a and 11b having a rectangular cross section are provided at both ends of a tapered portion having a rectangular cross section. As in the case of FIG.
[0019]
15 (b) and 16 (b), the shapes of the parallel portions 11a and 11b formed at both end portions simply have a rectangular cross section, but the shapes of the parallel portions 11a and 11b are shown in FIG. Such a trapezoidal cross-sectional shape, a cross-sectional shape as shown in FIG. 11, a polygonal cross-sectional shape not shown, or the like may be used. Furthermore, if the final end face shape after the bulge processing matches the end face shape of the product, the material yield is improved, which is preferable.
[0020]
Further, in FIGS. 15B and 16B, the central taper portion also has a rectangular cross section. However, there is no reason why the central portion has a rectangular cross section, and FIG. 15A and FIG. Of course, a circular cross section may be used as in FIG. 16 (a), or it may be bent or crushed from the top, bottom, left and right so that it can be inserted into a bulge mold.
[0021]
A method of manufacturing the deformed element tube 11 according to the present invention having the parallel portion 11b only at the large diameter side end portion of the tapered portion having a circular cross section as shown in FIG.
The deformed element tube 11 according to the present invention having the shape shown in FIG. 14 (a) is obtained by simply bending the plate having the shape shown in FIG. 14 (b). If the ends of U'-e ', io and woo, and ii'-o and woo'-o are joined, only the large-diameter side end as shown in FIG. The deformed element tube 11 according to the present invention having 11b can be manufactured.
[0022]
On the other hand, in FIG. 14 (c), FIG. 14 (b) is shown with a broken line, and a trapezoidal shape close to this is shown with a solid line.
As apparent from the comparison between the solid line and the broken line, when the trapezoid shown by the solid line in FIG. That is, in the plate winding process using a trapezoidal shape as a raw material, it is difficult to manufacture a deformed element tube having a parallel portion 11b at the end, like the deformed element tube 11 according to the present invention.
[0023]
As described with reference to FIG. 14, the simplest method is a method of simply bending and joining the plates having the developed shape of the deformed element tube 11 according to the present invention. A method of manufacturing the deformed element tube 11 according to the present invention having the shape shown in FIGS. 15 and 16 will be described.
[0024]
In the case of the shape shown in FIG. 15A, it can be obtained, for example, by using a simple tapered tube as a raw material and expanding the hole on the small diameter side and drawing on the large diameter side. In addition, in the case of the shape shown in FIG. 15B, in addition to the above, it can be obtained by performing a crushing process on the central trunk portion.
[0025]
In the case of the shape shown in FIG. 16 (a), for example, a simple taper tube may be used as a material to perform hole expansion processing on both the small diameter side and the large diameter side. In addition, in the case of the shape shown in FIG. 16B, in addition to the above, it can be obtained by performing a crushing process on the central body length portion.
[0026]
FIG. 7 shows another embodiment of the present invention. In the case shown in FIG. 7A, parallel portions 11a and 11b having a rectangular cross section are formed at both ends of a tapered portion having a rectangular cross section.
[0027]
In the example shown in FIG. 7, a portion of the product corresponding to the portion of δL + L0 in the parallel portion 11a on the small diameter side and δL ′ + L0 ′ in the parallel portion 11b on the large diameter side of the simple tapered tube By forming a rectangular cross section having a height dimension and determining the curvature radius R of the corner portion as will be described later, the die main bodies 12 and 13 and the sealing tool which will be described later are formed by bulging as the next step. The shaft pushing tools 14 and 15 that also serve as the shaft pushing process during the bulge machining do not cause buckling or the like, and the material can be pushed in extremely smoothly.
[0028]
FIG. 8 is a diagram for explaining the cross-sectional shapes of the small-diameter parallel portion 11a in the example shown in FIGS. 7A and 7B. The width W0 and the height H0 of the cross-sections from (a) to (c) are as follows. The radius of curvature R of the corner portion is changed stepwise by pre-forming. 8C shows an end portion, FIG. 8A shows a position away from the end portion on the small diameter side by δL + L0 in the axial direction, and FIG. 8B shows a cross-sectional view at an intermediate position thereof.
[0029]
That is, as shown in FIGS. 8A to 8C, the radius of curvature of the corner portion at the pre-formed end portion is R0, and the radius of curvature of the corner portion at a position separated by δL + L0 in the axial direction from the end portion on the small diameter side. R1 and the radius of curvature of the corner portion at a position separated by X in the axial direction from the end portion on the small diameter side is R (x).
R0 ≧ R (x) ≧ R1
It is said. In the example of FIG. 8, the radius of curvature of the four corner portions is the same, but it is not necessary to make them the same.
[0030]
More specifically, the circumferential length difference δd (x) at the position X from the end portion, where both end portions of the simple taper tube are the reference circumferential length,
δd (x) = π · (D0′−D0) · X / LT
It becomes.
[0031]
When the cross section of the end portion is formed into a rectangle having a width W0 and a height H0 by pre-molding, the curvature radius R (x) of the corner portion corresponds to the circumference difference δd (x) as shown in FIG. By changing the dimensions in the axial position, it is possible to determine an appropriate preformed shape.
[0032]
FIG. 9 is a diagram for explaining each cross-sectional shape of the large-diameter parallel portion 11b in the example shown in FIG. 7A. The cross-sectional width W0 ′ and height H0 ′ of FIGS. The radius of curvature R of the corner portion is changed stepwise by pre-forming. 9C is an end portion, FIG. 9A is a position away from the large diameter side end portion by δL ′ + L0 ′ in the axial direction, and FIG. 9B is a cross-sectional view at an intermediate position thereof. .
[0033]
That is, as shown in FIGS. 9A to 9C, the radius of curvature of the corner portion at the pre-formed end portion is R0 ′, and is located at a position away from the large-diameter end portion by δL ′ + L0 ′ in the axial direction. When the radius of curvature of the corner portion is R1 ′ and the radius of curvature of the corner portion at a position separated by X from the end on the large diameter side in the axial direction is R ′ (x),
R0 ′ ≦ R ′ (x) ≦ R1 ′
It is said.
[0034]
Further, the circumferential difference δd (x) at the position X from the end portion, where both end portions of the simple tapered tube are the reference circumferential length,
δd (x) = π · (D0′−D0) · X / LT
It becomes.
[0035]
When the end section is formed into a rectangle having a width W0 ′ and a height H0 ′, the radius of curvature R ′ (x) of the corner portion corresponds to the circumference difference δd (x) as shown in FIG. By changing the dimensions in the axial position, it is possible to determine an appropriate shape.
[0036]
The above describes the case of a rectangular cross section, but it is possible to enable extremely stable axial pressing during bulge processing by a similar method even in the case of a rectangular combination shape or polygonal shape.
[0037]
FIG. 10 shows an example where the product has a trapezoidal cross section, and FIG. 11 shows an example where the product has an L-shaped cross section. Each is an example of a preformed shape on the large diameter side, (c) is the large diameter side end, (a) is a position away from the large diameter side end in the axial direction by δL ′ + L0 ′, (b) is Cross-sectional views at intermediate positions thereof are shown.
[0038]
Further, the hydraulic bulge processing apparatus according to the present invention includes upper and lower mold bodies 12 and 13 having cavities as shown in FIGS. 1, 4 and 17, for example, and both the mold bodies 12 and 13. In order to hold the both end portions of the deformed element tube 11 according to any one of claims 1 to 3 in a sandwiched manner, a sealing tool for inserting a tip portion between the respective end portions of both mold bodies 12 and 13 is provided. The shaft pushing tools 14 and 15 are also provided, and one of the shaft pushing tools 15 is provided with a machining fluid injection hole 16, and at least one end side of both mold bodies 12 and 13 (see FIG. 1, in the examples shown in FIGS. 4 and 17, the inner surfaces of the small-diameter side and the large-diameter side) and the outer surfaces of the axial pressing tools corresponding to the end-side inner surfaces are parallel parts 12 a, 12 b, 13 a, 13 b, respectively. 14a and 15a are provided. The parallel portions 14a and 15a on the outer surfaces of the shaft pressing tools 14 and 15 have a role of restraining the raw tube from the inner surface when the shaft is pressed and enabling smooth deformation.
[0039]
In this hydraulic bulge processing apparatus, the axial pushing amount on the small diameter side is δL, the axial pushing amount on the large diameter side is δL ′, the length required for sealing on the small diameter side is L0, and the large diameter side is pushed. When the length required for sealing is L0 ', at least one end side of both mold bodies 12 and 13 (both ends on the small diameter side and the large diameter side in the examples shown in FIGS. 1, 4 and 17). The length of the parallel parts 12a, 12b, 13a, 13b provided on the inner surface is δL + L0 or more when provided on the small diameter part side, and δL ′ + L0 ′ or more when provided on the large diameter part side. The lengths of the parallel portions 14a and 15a of the axial pushing tools 14 and 15 corresponding to the parallel portions 12a, 12b, 13a and 13b provided in the mold main bodies 12 and 13 are provided on the small diameter portion side. Is δL + L0 or more, and when it is provided on the large diameter side, L0 ′ or more. It is desirable
[0040]
By the way, in the hydraulic bulge processing apparatus according to the present invention described above, the tip portion of the axial pushing tool 14 (15) that also serves as a sealing tool on the small diameter side (large diameter side) is a simple taper that becomes the material of the deformed element tube 11. It must be insertable into the small diameter side end (large diameter side end) of the tube PT or the deformed element tube 11, and the parallel portion 14a (15a) is the parallel portion 14a (15a) of the parallel portion 14a (15a) when the axial push is completed. It is desirable that there is no gap between the most advanced portion and the inner surface of the deformed element tube 11.
[0041]
For example, as shown in FIG. 1, after setting a simple tapered tube PT, which is a material of the deformed element tube 11, to the upper and lower mold bodies 12, 13, parallel portions 11a, 11b formed at the tube ends are hydraulically pressurized. When forming in the upper and lower mold bodies 12 and 13 prior to performing the bulge processing,
[0042]
A. Axial pushing tool 14 that also serves as a small diameter side sealing tool (see Fig. 2)
Envelope circumference SD0 ignoring the local recess at the tip:
SD0 ≦ (D0 −2t / cos θ) × π
However, D0: Outer diameter of the small diameter part
t: thickness of the deformed element tube 11
θ = tan−1 {(D0′−D0) / (2 · LT)}
LT: Length of tapered tube PT
D0 ': Outer diameter of large diameter part
[0043]
B. Shaft pushing tool 15 that also serves as a sealing tool on the large diameter side (see Fig. 3)
Envelope circumference SD0 'ignoring the local recess at the tip:
SD0 ′ ≦ {D0′−2t / cos θ} × π
[0044]
On the other hand, as shown in FIG. 4, when the parallel portions 11a and 11b formed at the tube end portions of the deformed element tube 11 are formed in advance before being set on the upper and lower mold bodies 12 and 13, ,
[0045]
A '. Peripheral length SD0 of the tip portion of the axial pushing tool 14 that also serves as a sealing tool on the small diameter side:
SD0 ≦ peripheral length SD of the parallel portion 14a
B '. Peripheral length SD0 ′ of the tip portion of the shaft pushing tool 15 that also serves as a sealing tool on the large diameter side:
SD0 '≦ peripheral length SD' of the parallel portion 15a
is required.
[0046]
When forming the bulge processed product 17 using the hydraulic bulge processing apparatus according to the present invention, for example, a simple taper tube PT which is a material of the deformed element tube 11 according to the present invention is shown in FIG. As shown, it is set in a pair of mold bodies 12, 13 of a hydraulic bulge processing apparatus according to the present invention. Next, prior to the bulge processing, the axial push tools 14 and 15 that also serve as a sealing tool are moved in the axial direction, and the pipe ends of the tapered pipe PT sandwiched between the mold main bodies 12 and 13 and the axial push tools 14 and 15. For example, as shown in FIG. 1B, parallel portions 11a and 11b are formed at both ends to form the deformed element tube 11 according to the present invention. Further, at this time, the shaft pressing tool 14 or 15 may not start the shaft pressing of the deformed element tube 11 at the same time, and for example, the pressing of the shaft pressing tool 14 may be started when the shaft pressing tool 15 is pressed to some extent. A shaft pressing timing at which the deformed element tube 11 is stable in the mold bodies 12 and 13 may be selected.
[0047]
At this time, if the dimension design of the shaft pushing tools 14 and 15 which also serve as the sealing tool is performed based on the above-mentioned dimensions, the shaft pushing tools 14 and 15 are smoothly inserted into the tapered tube TP. be able to.
[0048]
In the state of FIG. 1 (b), as shown in FIGS. 2 (b) and 3 (b), at both ends of the tapered tube TP, L0 on the small diameter side or more, preferably δL + L0 or more, and L0 on the large diameter side. The parallel portions 11a and 11b having the above length are formed (the deformed element tube 11 of the present invention), and the working fluid to which the internal pressure is applied is completely sealed.
[0049]
Thereafter, while increasing the internal pressure of the machining fluid, the axial pushing tools 14 and 15 are further moved in the axial direction to perform hydraulic bulging, and as shown in FIG. 1 (c), the bulging product according to the present invention. 17 is formed.
[0050]
That is, in the bulge processing performed by setting the deformed element tube 11 according to the present invention to the hydraulic bulge processing apparatus according to the present invention, as a result of being able to push the shaft, in the bulge processed product 17 according to the present invention, It becomes possible to obtain a larger pipe expansion rate than before, and the end surface of the bulge processed product 17 is perpendicular to the axis as shown in FIG. Can be easily performed, and positioning and welding of the bayonet coupling are possible.
[0051]
FIG. 5 shows another embodiment different from the embodiment shown in FIG. 1, and it is the same that parallel portions 12a, 12b, 13a, 13b are provided at both end portions of both mold bodies 12, 13, respectively. The cavities inside the parallel parts 12b and 13b on the large diameter side of the mold bodies 12 and 13 are not locally narrowed as in the example shown in FIG. Shows a monotonic decrease in the axial direction with respect to the large-diameter end.
[0052]
In this case, since the resistance of shaft pushing is small and it is advantageous as a metal flow, the effect of expanding the forming range (expansion limit) is further increased as shown in FIG. Therefore, in the hydraulic bulge processing apparatus according to the present invention, it is recommended that the cavity shapes of the mold main bodies 12 and 13 are designed in the shape shown in FIG.
[0053]
On the other hand, in automobile parts, there are many shapes in which the cross-sectional shape of the end of the product is close to a rectangle, a combination of rectangles, or a polygon.
[0054]
FIG. 17 shows an embodiment of the present invention in which the deformed element tube 11 of the present invention shown in FIG. That is, the deformed element tube 11 shown in FIG. 7A is set in the mold main bodies 12 and 13. FIG. 7B shows an enlarged view of the small-diameter side of the deformed element tube 11 of the present invention, and the cross-sectional shape of the small-diameter side parallel portion 11a is shown in FIG. The deformed element tube 11 having such a cross-sectional shape is molded using the axial push tools 14 and 15 that also serve as a sealing tool showing an example of the present invention. That is, FIG. 7C shows a shaft pushing tool 14 that also serves as a small diameter side sealing tool, but has a width W0-2t, a height H0-2t, and a corner portion having a parallel portion 14a of R1. .
[0055]
The shaft pushing tools 14 and 15 are pushed into the end from the state shown in FIG. 17A, and the end of the deformed element tube 11 is completely formed at the stage shown in FIG. 17B. The raw tube 11 can be obtained, and the machining fluid to which the internal pressure is applied is completely sealed. As a matter of course, in actual processing, the parallel portions 11a and 11b at the ends of the deformed element tube 11 have the effect of the present invention even if the R dimension and the straightness of the parallel portions 11a and 11b vary somewhat. It does not depart from the technical idea of the present invention.
[0056]
Thereafter, while the internal pressure of the working fluid is increased, the axial pushing tools 14 and 15 are further moved in the axial direction to obtain the bulged product 17 according to the present invention subjected to the hydraulic bulging.
[0057]
In addition, you may perform the shaping | molding of the parallel parts 11a and 11b of a pipe end performed before a bulge process in a preforming or the stage before it. It can be carried out by existing processing methods such as drawing, hole expanding, swaging and sping, and combinations thereof.
[0058]
FIG. 13 shows an example of the seal configuration of the axial push tools 14 and 15 that also serve as a sealing tool that is a component of the hydraulic bulge processing apparatus according to the present invention.
(A) is an example in the case of sealing with end faces 14b and 15b in contact with the end face of the deformed element tube 11, (b) is an example in which protrusions 14c and 15c are provided on the end faces 14b and 15b, and (c) is a parallel part 14a, 15d shows an example in which steps 14d and 15d are provided at the boundaries between the end faces 14b and 15b, and FIG. 9d shows an example in which an O-ring 18 is provided on the parallel parts 14a and 15a. 15a and the circumference range.
[0059]
The example shown here is only one specific example of the present invention, and the shape of the cavities of the mold bodies 12 and 13 is relatively simple. A three-dimensional complicated shape represented by
[0060]
In the above example, the shaft is pushed from both the small-diameter side and the large-diameter side. However, the present invention is applied to one side and the other is conventionally performed, for example, as shown in FIG. You may employ | adopt the method without an axial push. Since the effect of the shaft change varies depending on the product shape, the application range of the present invention may be determined according to the case.
[0061]
Furthermore, in the above example, the case of a simple taper tube PT is mainly described as the material of the deformed element tube 11, but a combination of a simple taper tube PT and a taper tube and a normal straight tube are combined. Even in this case, both end portions can be approximated to a part of a simple taper tube, and therefore can be applied as a material for the deformed element tube 11 of the present invention.
[0062]
【The invention's effect】
As described above, according to the present invention, even when a hydraulic bulging process is performed on a deformed steel pipe whose cross-sectional shape changes in the axial direction, such as a tapered pipe, it is possible to push in the axial direction together with the application of internal pressure. As a result, it is possible to obtain a larger expansion ratio than before, and it is also possible to easily join and plug in other parts.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a first embodiment of the present invention, and shows an example in which a parallel portion formed at a tube end portion of a deformed element tube is performed prior to hydraulic bulging, and FIG. The longitudinal cross-sectional view which showed the setting state to the metal mold body of a pipe, (b) is the longitudinal cross-sectional view which showed the state which formed the parallel part before hydraulic bulge processing, (c) is after hydraulic bulge processing completion | finish. It is the longitudinal cross-sectional view which showed the state.
FIG. 2 is a view corresponding to FIGS. 1A to 1C showing a relationship between a small-diameter-side upper mold body, a shaft pushing tool that also serves as a sealing tool, and a deformed element tube end portion;
FIG. 3 is a view corresponding to FIGS. 1A to 1C showing a relationship between a large-diameter side upper die body, a shaft pushing tool which also serves as a sealing tool, and a deformed element pipe end portion.
FIG. 4 is an explanatory view showing a second embodiment of the present invention, showing an example in which the parallel portion of the tube end portion of the deformed element tube is formed in advance, (a) is a die body of the deformed element tube; (B) is a longitudinal sectional view showing a state before hydraulic bulging, and (c) is a longitudinal sectional view showing a state after finishing hydraulic bulging.
FIG. 5 is an explanatory view showing a third embodiment of the present invention, showing an example in which the cavity inside the parallel portion on the large diameter side monotonously decreases in the axial direction with respect to the large diameter end, (a) A longitudinal sectional view showing the setting state of the taper tube to the die body, (b) is a longitudinal sectional view showing a state in which a parallel portion is formed before the hydraulic bulge processing, and (c) is after the hydraulic bulging processing is completed. It is the longitudinal cross-sectional view which showed the state.
FIGS. 6A and 6B are longitudinal sectional views showing an example of a tapered tube that is a material of the deformed element tube of the present invention.
FIGS. 7A and 7B are diagrams showing an embodiment of a deformed element pipe, wherein FIG. 7A is an overall perspective view, FIG. 7B is an enlarged view of a small diameter side, and FIG. 7C is a shaft pusher also serving as a small diameter side sealing tool. An enlarged view of the tool is shown.
FIG. 8 is a cross-sectional view on the small diameter side showing an example of the deformed element pipe of the present invention when the product has a rectangular cross section, and (a) is a cross-sectional view at a position away from the end on the small diameter side by δL + L0 in the axial direction. (C) Sectional drawing of an edge part, (b) is sectional drawing in those intermediate positions.
9 is a cross-sectional view on the large-diameter side showing an example of a deformed element tube similar to FIG. 8, in which (a) is a cross-sectional view at a position away from the end on the large-diameter side by δL ′ + L0 ′ in the axial direction; (C) is sectional drawing of an edge part, (b) is sectional drawing in those intermediate positions.
10 is a view similar to FIGS. 9A to 9C when the product has a trapezoidal cross section. FIG.
11 is a view similar to FIGS. 9A to 9C when the product has an L-shaped cross section. FIG.
FIGS. 12A and 12B are explanatory diagrams when a bulge molded product is joined to a side surface of a part having a rectangular cross section, where FIG. 12A is a conventional diagram and FIG. 12B is an explanatory diagram showing a bulge molded product according to the present invention; Explanatory drawing which showed the inclination of the pipe edge part with respect to (c) is sectional drawing of a bulge molded product.
FIGS. 13A to 13D are diagrams for explaining a seal configuration of a shaft pushing tool which also serves as a sealing tool. FIG.
FIGS. 14A and 14B are diagrams for explaining a method of manufacturing a deformed steel pipe according to the present invention having a parallel portion at a large-diameter side end, FIG. 14A is an overall perspective view, FIG. 14B is a development view, and FIG. It is the figure which showed the trapezoid shape close | similar to the expanded view shown to (b).
15A is an example of a deformed element tube according to the present invention in which a parallel portion having a circular cross section is formed at both ends of a tapered portion having a circular cross section, and FIG. 15B is a diagram illustrating a rectangular cross section at both ends of a tapered portion having a rectangular cross section. It is the figure which showed the example of the deformed element tube of this invention which provided the parallel part which has.
16 (a) and 16 (b) show examples of the deformed element pipe of the present invention having a transition portion between the parallel portion on the large diameter side and the central tapered portion in FIGS. 19 (a) and 19 (b). FIG.
FIG. 17 is an explanatory view showing a fourth embodiment of the present invention, showing another example in which the parallel portion of the tube end portion of the deformed element tube is formed in advance, and (a) shows the gold of the deformed element tube The longitudinal cross-sectional view which showed the setting state to a type | mold main body, (b) is the longitudinal cross-sectional view which showed the state before hydraulic bulge processing, (c) is the longitudinal cross-sectional view which showed the state after completion | finish of hydraulic bulge processing is there.
18A and 18B are explanatory views of conventional hydraulic bulge processing of a straight element pipe, where FIG. 18A is a longitudinal sectional view showing a state before processing, and FIG.
FIG. 19 is a diagram for explaining a problem in the case where axial pressing of a taper element pipe is performed with a tool for axial pressing that also serves as a sealing tool for a conventional straight element pipe.
FIGS. 20A and 20B are explanatory views of a conventional hydraulic bulging process for a tapered pipe, in which FIG. 20A is a longitudinal sectional view before processing, (b) before application of internal pressure, and (c) at the end of processing;
[Explanation of symbols]
11 Deformed tube
11a Parallel part
11b Parallel part
12 Upper mold body
12a Parallel part
12b Parallel part
13 Lower mold body
13a Parallel part
13b Parallel part
14-axis push tool
14a Parallel part
15-axis push tool
15a Parallel part
16 Injection hole
17 Bulge processed products

Claims

A bulge, which is a deformed element pipe used for bulging, has a circumferential length in which an outer diameter gradually increases or decreases from one side to the other side in the axial direction, and a parallel portion is formed at least on one end side. Deformed tube for processing.

2. The deformed element pipe for bulge processing according to claim 1, wherein the parallel portion has a length equal to or greater than a sum of a shaft pressing amount in bulge processing and a length necessary for sealing.

A deformed element pipe for manufacturing a bulge processed product having a rectangular cross section, a rectangular combination shape or a polygonal shape, and the curvature radius R of the corner portion in the parallel portion corresponds to the axial distance of the tube end portion. 3. The deformed element tube for bulge processing according to claim 1 or 2, wherein the deformed element tube is changed in accordance with a change in a peripheral length difference of the deformed element tube.

A pair of mold bodies;
A seal in which tip portions are inserted between the respective end portions of both mold main bodies so as to hold both end portions of the deformed element pipe according to any one of claims 1 to 3 in a sandwiched manner with these two mold main bodies. Axial pushing tool that also serves as a tool,
Either one of the axial pushing tools is provided with a machining fluid injection hole,
The hydraulic bulge processing apparatus is characterized in that at least one end-side inner surface of both mold bodies and an outer surface of a shaft pushing tool corresponding to the end-side inner surface are provided with parallel portions, respectively.

In the hydraulic bulge processing apparatus according to claim 4,
The shaft pushing amount on the small diameter side is δL, the shaft pushing amount on the large diameter side is δL ′, the length required for the seal on the small diameter side is L0, and the length necessary for the seal on the large diameter side is L0 ′. if you did this,
The length of the parallel portion provided on the inner surface of at least one end of both mold bodies is δL + L0 or more when provided on the small diameter side, and δL ′ when provided on the large diameter side. + L0 'or more,
The length of the parallel part of the axial pushing tool corresponding to the parallel part provided in this mold is δL + L0 or more when provided on the small diameter part side, and L0 ′ or more when provided on the large diameter part side. Hydraulic bulge processing device characterized by that.

A method of performing hydraulic bulging on the deformed element pipe according to any one of claims 1 to 3 using the hydraulic bulge processing apparatus according to claim 4 or 5, wherein the deformed element pipe is a material of the deformed element pipe. After setting the taper tube to a pair of molds of the hydraulic bulge processing device, the axial pushing tool is moved in the axial direction, forming a parallel portion at the tube end of the simple taper tube, and forming a deformed element tube, A hydraulic bulging method characterized by performing a hydraulic bulging by moving a shaft pushing tool in an axial direction while increasing an internal pressure of a machining fluid.

The deformed element tube according to any one of claims 1 to 3 is set in a mold of the hydraulic bulge processing apparatus according to claim 4 or 5, and the hydraulic bulge is pressed in the axial direction while applying the internal pressure. A bulge processed product characterized by processing.