JP4182335B2

JP4182335B2 - Spinning molding method and catalytic converter container

Info

Publication number: JP4182335B2
Application number: JP2002355238A
Authority: JP
Inventors: 明川合; 潤司森川
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2002-09-18
Filing date: 2002-12-06
Publication date: 2008-11-19
Anticipated expiration: 2022-12-06
Also published as: JP2004160536A

Description

【０００１】
【発明の属する技術分野】
本発明は、素管の端部にテーパ部と小径のストレート部とを連続に成形するスピニング成形方法とこのスピニング成形方法により素管から一体に成形された触媒コンバータ容器とに関する。
【０００２】
【従来の技術】
例えば、自動車の排気系に装備される排ガス浄化用の触媒コンバータは、図８に示されるように、金属製の容器１に触媒担体Ｓを内装した構造となっており、通常は、エンジンから延ばされた排気管Ｐの途中に直列に介装される。このような触媒コンバータにおいて、その容器（触媒コンバータ容器）１は、触媒担体Ｓを収納保持する比較的大径の触媒保持部２を中央部に備えると共に、前記排気管Ｐに接続（溶接）される比較的小径の接続部３を両端部に備え、さらに触媒保持部２から接続部３に向かって次第に縮径するコーン部４とを備えている。
【０００３】
そして従来、この種の触媒コンバータ容器１は、製造コストの低減を図るため、素管の端部にスピニング成形を加えてコーン部４と接続部３とを一体に成形し、素管の非成形部は触媒保持部２としてそのまま用いるようにしている。
図９は、従来一般に行われていたスピニング成形方法を示したもので、素管Ｗの中間部をクランパ１０によってクランプし、成形工具１１を素管Ｗの軸Ｏの回りに相対的に公転させながら、太線矢印のように素管Ｗの軸Ｏに傾斜する方向と平行な方向とへ、クランパ１１による被クランプ側（中間部側）から管端側へ送って、テーパ部Ｗａとストレート部Ｗｂとを同時成形し、この送り（パス）を繰返して、所定の寸法形状を有する上記コーン部４と接続部３とを形成するようにしていた。
【０００４】
ところで、この種の触媒コンバータ容器１は、軽量化や材料コストの低減を図りかつ熱容量を小さくして初期アイドリング時の触媒効率を高めるには、触媒保持部２の板厚をできるだけ薄くする必要があり、一方、排気管Ｐに加わる曲げモーメントに耐える強度、剛性を確保するには、接続部３の板厚をできるだけ厚くする必要がある。
しかるに、上記図９に示した一般的なスピニング成形によれば、素管Ｗの被クランプ側から管端側へ成形工具１１を送って成形を進めるため、材料が自由端となる管端側へ流れ、接続部３およびコーン部４の板厚が素管Ｗの板厚よりも薄くなる傾向にあり、接続部３の強度、剛性を確保するには、素管Ｗとして厚肉のものを選択せざるを得ない状況にあった。また、このスピニング成形においては、成形工具１１をテーパ部Ｗａの途中に戻して（細線矢印で示す）から管端側へ送る動作を繰返すので、テーパ部Ｗａの上部側（被クランプ側に寄った部位）に局所的な薄肉部Ｗｆが形成され易く、該薄肉部Ｗｆが応力集中部となる、という問題もあった。
【０００５】
そこで従来、上記接続部３およびコーン部４の板厚を素管よりも増肉させるため、前記図９に示したスピニング成形方法において、素管Ｗの管端を押圧工具（回転体）により軸方向に押え、管端に向う材料の流れを規制して、触媒保持部２から接続部３の先端に至るまでの板厚を徐々に増肉することが行われていた（例えば、特許文献１、特許文献２等参照）。
なお、本発明者等は、図１０に示すように、クランパ１０によりクランプした素管Ｗに対し、成形工具１１を、太線矢印のように素管Ｗの軸Ｏに平行な方向と傾斜する方向とへ、管端側から被クランプ側へ送ってストレート部Ｗｂとテーパ部Ｗａとを同時成形し、この送り（パス）を繰返すごとにストレート部Ｗｂとテーパ部Ｗａとの境界部Ｗｃを被クランプ側へ進ませることにより、上記管端の押圧工具を不要にした改良タイプのスピニング成形方法を考案し、既に特願２００１−３１３８７６号（未公知）にて明らかにしている。
【０００６】
【特許文献１】
特開平１１−１３２０３８号公報
【特許文献２】
特開２０００−１７９３３４号公報
【０００７】
【発明が解決しようとする課題】
しかしながら、上記特許文献１、２に記載されたスピニング成形方法によれば、素管Ｗの管端を押える押圧工具とこれを支持する装置が必要なため、成形設備にかかるコスト負担が増大する、という問題があった。
一方、上記図１０に示した改良スピニング成形方法によれば、テーパ部Ｗａの中間に材料が集まり易くなるため、屈曲部である境界部Ｗｃ付近の増肉がいま一つ不足する、という問題があった。
【０００８】
本発明は、上述した問題点に鑑みてなされたもので、その課題とするところは、管端を押圧工具により押えることなく十分なる増肉を図ることができるようにし、もって設備コストの低減と強度の安定的向上とに大きく寄与するスピニング成形方法を提供し、併せて該スピニング成形方法により成形された触媒コンバータ容器を提供することにある。
【０００９】
【課題を解決するための手段】
上記課題を解決するため、本発明に係るスピニング成形方法は、成形工具を素管の軸回りに相対的に公転させながら、素管の半径方向と軸方向とに送って、該素管の端部に先端へ向けて次第に縮径するテーパ部と該テーパ部に連続する小径のストレート部とを成形するスピニング成形方法において、始めに、前記成形工具を前記素管の軸に傾斜する方向へ、その中間部側から管端側へ送って該素管の端部をテーパ形状に絞り、次に、前記成形工具を前記素管の軸に傾斜する方向へ往復運動させて、該素管の端部の絞り部分をさらに絞ると共に該絞り部分の板厚を増加させ、次に、前記成形工具を前記素管の軸に平行な方向へ、その管端側から中間部側へ送って前記ストレート部を成形すると共に該ストレート部と前記テーパ部との境界部を増肉させ、最終的に、前記成形工具を素管の軸に傾斜する方向と平行な方向とへ移動させて仕上成形を行うことを特徴とする。
本発明のスピニング成形方法においては、初期段階で管端部を薄肉化した後、中期段階で管端部の増肉を図るので、最終的に成形されるテーパ部およびストレート部が必要以上に増肉されることはなくなる。また、終盤で管端側から中間部側へ成形工具を送ってストレート部を成形することで、境界部の増肉も進み、境界部を含めたテーパ部およびストレート部の板厚はほぼ一定となる。また、初期段階で素管の中央側から管端側へ成形工具を送って高能率にテーパ形状に絞った後に、成形工具の往復運動による絞りを行うので、全体の成形時間が短縮する。もちろん、素管の管端を押える押圧工具を用いることなく成形を行うので、成形設備にかかるコストも大幅に低減する。
上記課題を解決するため、本発明に係る触媒コンバータ容器は、請求項１に記載のスピニング成形方法により素管の端部にテーパ部とストレート部とを一体に成形し、前記素管の非成形部を触媒担体が収納保持される触媒保持部として、前記ストレート部を排気管が接続される接続部として、前記テーパ部を前記触媒保持部と前記接続部とを連接するコーン部としてそれぞれ用いる触媒コンバータ容器であって、前記接続部および前記コーン部の板厚が、前記両部の境界部をも含めて前記触媒保持部の板厚よりも厚くなっており、かつ板厚ほぼ一定に平均化していることを特徴とする。
このように構成した触媒コンバータ容器は、接続部およびコーン部が、該両部の境界部も含めて触媒保持部の板厚よりも厚くなっており、かつ板厚ほぼ一定に平均化しているので、応力集中が緩和される。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を添付図面に基いて説明する。
図１は、本発明に係るスピニング成形方法の第１の実施形態の基本工程を示したものである。本第１の実施の形態において、初期乃至中期段階では、同図（１）に示すように、成形工具１１を素管Ｗの軸Ｏに傾斜する方向へ往復運動させて（太線矢印Ａ、Ａ´にて示す）、素管Ｗの端部Ｗ´をテーパ形状に絞る。また、最終段階では、同図（２）に示すように、成形工具１１を素管Ｗの軸Ｏに平行な方向と傾斜する方向とへ往復運動させて（太線矢印Ｂ、Ｂ´にて示す）、テーパ部Ｗａとストレート部Ｗｂとを成形する。このように初期乃至中期段階で、成形工具１１の直線的な往復運動だけで素管Ｗの端部（管端部）Ｗ´を絞ることで、管端部Ｗ´の中間部分から先端側にかけてほぼ一様に増肉が進む。一方、このように増肉が進んだ後の最終段階で、テーパ部Ｗａとストレート部Ｗｂとを成形するので、この段階では、材料流動がほとんど起こらず、したがって、得られるテーパ部Ｗａとストレート部Ｗｂとの板厚は、両部の間の境界部Ｗｃをも含めて十分な厚さとなる。
【００１１】
本第１の実施の形態は、前記図８に示した触媒コンバータ容器１の成形に適用したもので、得られた成形体Ｆは、図２に示すように、素管Ｗの非成形部Ｗ″が前記触媒担体Ｓ（図８）を収納保持する触媒保持部２として、そのストレート部Ｗｂが前記排気管Ｐ（図８）を接続させる接続部３として、そのテーパ部Ｗａが前記コーン部４としてそれぞれ供されるようになる。しかして、この成形体Ｆは、排気管Ｐが接続される接続部３（Ｗｂ）を始め、該接続部３とコーン部（Ｗａ）４との境界部５（Ｗｃ）の板厚が、素管Ｗの板厚よりも十分に厚くなっているので、前記排気管Ｐの接続に必要な強度、剛性が十分に確保される。換言すれば、素管Ｗとしてより薄肉のものを用いることができるようになり、薄肉の素管Ｗの使用が可能になる分、材料コストが低減するばかりか軽量化も実現する。また、素管Ｗとしてより薄肉のものを用いる分、触媒保持部２の熱容量が小さくなり、初期アイドリング時に触媒担体Ｓの加熱が促進されて浄化効率が高まるようになる。
【００１２】
なお、触媒コンバータの製造に際しては、素管Ｗの一端部Ｗ´にテーパ部Ｗａ（コーン部４）とストレート部Ｗｂ（接続部３）とを成形した後、その被加工部Ｗ″（触媒保持部２）に触媒担体Ｓを収納し、その後、素管Ｗの他端部にテーパ部Ｗａ（コーン部４）とストレート部Ｗｂ（接続部３）とを成形するようにしても、予め素管Ｗに触媒担体Ｓを収納した後、その両端部に順次テーパ部Ｗａ（コーン部４）とストレート部Ｗｂ（接続部３）とを成形するようにしてもよい。
【００１３】
以下、本第１の実施の形態としてのスピニング成形方法を、図３および図４に基いて具体的に説明する。
スピンニング成形に際しては、図３（１）に示すように、スピニング成形装置内のクランパ１０に素管Ｗの長手方向中間部をクランプさせ、このクランプされた素管Ｗに対して、一対の成形工具（成形ローラ）１１を素管Ｗの軸Ｏの回りに公転させながら、半径方向（Ｙ軸方向）と軸方向（Ｘ軸方向）とへ移動させる。素管Ｗは、前記成形しようとする触媒コンバータ容器１（図８）の触媒保持部２の内径と同じ口径を有するものを選択し、また、本スピニング成形による増肉を考慮して適宜板厚のものを選択する。なお、この素管Ｗは、溶接管であっても、シームレス管であってもよい。
【００１４】
上記した成形工具１１の公転およびＸ軸、Ｙ軸方向への移動は、スピニング成形装置内の制御装置により制御されるようになっており、図４に示すように、スタート（Ｓ１）に応じて、先ず、成形ローラ１１の公転回転数が適宜選択されると共にその駆動源が駆動され（Ｓ２）、次いで、ステップＳ３で行程数ａが０（ａ＝０）に設定される。なお、以下の説明では、説明の便宜のため、図３の右方向への成形ローラ１１の移動をＸ軸前進、これと反対方向（図の左方向）への成形ローラ１１の移動をＸ軸後退、半径内方向への成形ローラ１１の移動をＹ軸前進、半径外方向への成形ローラ１１の移動をＹ軸後退とそれぞれ呼ぶこととする。
【００１５】
スピニング成形に際しては、先ず、ステップＳ４でこれから行う行程数１が加えられ（ａ＝ａ＋１）、図３（２）および図４のステップＳ５に示す初期乃至中期段階のスピニング成形が行われる。このスピニング成形では、成形ローラ１１を次第にＹ軸後退させながら、すなわち成形ローラ１１の公転径を次第に拡大させながら管端側からクランパ１０による被クランプ側へ成形ローラ１１をＸ軸前進させた後、成形ローラ１１をＹ軸前進させながら、すなわち成形ローラ１１の公転径を次第に縮小させながら被クランプ側から管端側へ成形ローラ１１をＸ軸後退させる。これにより、成形工具１１は素管Ｗの軸Ｏに傾斜する方向へ太線矢印Ａ、Ａ´のように一往復運動し、これに応じて素管Ｗの端部Ｗ´はテーパ形状に絞られる。このとき、Ｘ軸方向の移動量をα、Ｙ軸方向の移動量をβとすると、管端側から被クランプ側への成形ローラ１１の移動軌跡Ａ→は[αＸ→−βＹ→]となり、一方、被クランプ側から管端側への成形ローラ１１の移動軌跡Ａ´→は[−αＸ→＋βＹ→]となる。
【００１６】
上記成形ローラ１１の一往復運動（一行程）後、図４のステップＳ６で、管端の口径ｄａが、目標の口径ｄに所定のマージンδを加えた値[ｄ＋δ]に達したかどうかが判断され、達していない場合は、再び、行程数をカウントし（Ｓ４）、成形ローラ１１をさらに追い込みながら往復運動させ（Ｓ５）、管端の口径ｄａが[ｄ＋δ]以下になるまで前記往復運動が繰返えされる。
そして、管端の口径ｄａが[ｄ＋δ]以下になったら、図３（３）および図４のステップＳ７に示す最終段階のスピニング成形が行われる。このスピニング成形では、成形工具１１を素管Ｗの軸Ｏに平行な方向と傾斜する方向とへ、太線矢印Ｂ、Ｂ´で示すように往復運動させ、テーパ部Ｗａとストレート部Ｗｂとを同時成形する。この時、成形工具１１の往復運動は、通常一回だけでよいが、設定するマージンδ（Ｓ６）の大きさによっては、成形工具１１の往復運動を二回以上繰返えしてもよい。
その後は、成形ローラ１１をＹ軸後退させる（Ｓ８）と共に、Ｘ軸後退させ（Ｓ９）、成形ローラ１１をスタート位置に復帰させ、さらに、その回転（公転）を停止し（Ｓ１０）、これにて一連のスピニング成形は終了（停止）する（Ｓ１１）。
【００１７】
なお、上記第１の実施の形態においては、素管Ｗを位置固定して成形工具１１を素管Ｗの軸Ｏの回りに公転させるようにしたが、成形工具１１を公転させずに素管Ｗをその軸Ｏを中心に回転させるようにしてもよい。
また、上記実施の形態においては、成形の最終段階でも成形ローラ１１を往復運動させるようにしたが、この最終段階では、素管Ｗの管端側から被クランプ側へ、または被クランプ側から管端側へ一回だけ成形ローラ１１を移動させるようにしてもよい。
【００１８】
図５は、本発明に係るスピニング成形方法の第２の実施形態の基本工程を示したものである。本第２の実施の形態において、初期段階では、同図（１）に示すように、前記成形工具（成形ローラ）１１を素管Ｗの軸Ｏに傾斜する方向へ、その被クランプ側（中間部側）から管端側へ送って（太線矢印Ｃ、Ｃ´にて示す）、管端部Ｗ´をテーパ形状に絞る。この成形は、前記図９に示した一般的なスピニング成形と似た加工様式となり、これにより、材料が管端側へ流れて絞り部分の板厚が素管Ｗの板厚よりわずか薄くなる。また、この工程は、成形工具１１をテーパ部Ｗａの途中に戻して（細線矢印にて示す）から管端側へ送る動作を繰返すので、絞り部分の上部側（被クランプ側に寄った部位）に局所的な薄肉部Ｗｆが形成される。
【００１９】
中期段階では、図５（２）に示すように、成形工具１１を素管Ｗの軸Ｏに傾斜する方向へ往復運動させて（太線矢印Ａ、Ａ´にて示す）、前記絞り部分（管端部Ｗ´）をさらに絞る。この成形は、前記図１（１）に示した、第１の実施の形態における初期乃至中期段階と同じ加工様式となり、これにより上記初期段階で薄肉化した管端部Ｗ´の増肉が進み、前記薄肉部Ｗｆも解消される。
【００２０】
末期段階では、図５（３）に示すように、成形工具１１を素管Ｗの軸Ｏに平行な方向へ、管端側から被クランプ側へわずかの距離だけ送り（太線矢印Ｄにて示す）、ストレート部Ｗｂを成形する。すると、このストレート部Ｗｂの成形と同時にテーパ部Ｗａも最終形状に近づき、両者の間に屈曲形状の境界部Ｗｃが出現する。しかして、この末期段階では、管端側から被クランプ側への成形工具１１の送りを繰返すことで、管端側の材料が境界部Ｗｃ側へ寄せられ、これにより境界部Ｗｃ付近が増肉される。すなわち、図１０に示した改良タイプのスピニング成形に際して生じる可能性のあった境界部Ｗｃ付近の増肉不足が解消される。
【００２１】
さらに、最終段階では、図５（４）に示すように、成形工具１１を素管Ｗの軸Ｏに傾斜する方向と平行な方向とへ、被クランプ側から管端側へ送って（太線矢印Ｅにて示す）、仕上成形を行い、これにより所望の寸法形状を有する成形体Ｆ（図２）が得られる。なお、この最終段階における成形工具１１の送り方向は任意であり、管端側から被クランプ側へ送ってもよい。
【００２２】
本第２の実施の形態においては、上記したように一旦、初期段階で管端部を薄肉化した後、中期段階で管端部の増肉を図るので、最終的に成形されるテーパ部Ｗａおよびストレート部Ｗｂが必要以上に増肉されることはなくなる。したがって、素管Ｗの非成形部Ｗ″（図２）と成形後の管端部（Ｗａ、Ｗｂ）との間に大きな板厚差が生じることはなく、両者の境界部が応力集中部となることはない。また、中期段階における成形工具１１の往復運動により、初期段階で生じた薄肉部Ｗｆが解消されると共に、末期工程における境界部Ｗｃへの材料寄せにより、該境界部Ｗｃ付近の薄肉化も防止されるので、境界部Ｗｃを含めたテーパ部Ｗａおよびストレート部Ｗｂの板厚は平均化され、管端部に応力集中部が残存することもない。したがって、得られる成形体Ｆに対する強度的信頼性は、著しく高いものとなる。
【００２３】
ところで、成形工具１１の往復運動により管端部Ｗ´を絞る場合は、しわが発生し易いため、１パス当りの絞り量をあまり大きくとれない、という制約がある。一方、被クランプ側から管端側へ成形工具１１を送って管端部Ｗ´を絞る場合は、１パス当りの絞り量を比較的大きくとることができ、その分、成形能率が向上する。本第２の実施の形態においては、初期段階でこの成形能率の高い絞り成形（図５(1)）を行っているので、その後の成形、すなわち成形工具１１の往復運動による絞り成形（図５(2)）のパス回数を、第１の実施の形態に比べて大幅に削減することができ、その分、全体の成形に要する時間が短縮する。
【００２４】
図６は、本第２の実施の形態における具体的な成形フローを示したもので、前記第１の実施の形態における成形フロー（図４）と同じステップには、同一符号を付している。本第２の実施の形態においては、スタート（Ｓ１）に応じて、成形ローラ１１の公転回転数が適宜選択されると共にその駆動源が駆動され（Ｓ２）た後、ステップ２１で、図５（１）に示した初期段階の絞り成形（スピニング成形）が行われる。このスピニング成形は、被クランプ側から管端側へ成形工具１１を送って、管端部Ｗ´をテーパ形状に絞るようにするので、前記したように１パス当りの絞り量を比較的大きくとることができ、短時間で成形が終了する。
【００２５】
その後は、第１の実施の形態と同じステップＳ３〜Ｓ６で、図５（２）に示した中期段階のスピニング成形が行われ、成形工具１１の往復運動により、管端部Ｗ´がさらに絞られると共に、その絞り部分が増肉される。
そして、ステップＳ６で、管端の口径ｄａが、目標の口径ｄに所定のマージンδを加えた値[ｄ＋δ]に達したと判断されると、ステップＳ２２で図５（３）に示した末期段階の成形が行われ、さらにステップＳ２３で仕上成形が行われる。Ｓ２２の成形は、管端側から被クランプ側への成形工具１１の送りを繰返すことで、管端側の材料を境界部Ｗｃ側へ寄せる内容を含み、これにより境界部Ｗｃが増肉される。また、ステップ２３の成形は、成形工具１１を被クランプ側から管端側へまたは管端側から被クランプ側へ送って寸法形状出しを行う内容を含み、これにより所望の寸法形状を有する成形体Ｆ（図２）が得られる。
その後は、第１の実施の形態と同じステップＳ８〜Ｓ１０を経て成形工具１１がスタート位置に復帰して回転（公転）を停止され、これにて一連のスピニング成形は終了（停止）する（Ｓ１１）。
【００２６】
【実施例】
外径１１４ｍｍ、板厚１．２ｍｍの素管Ｗを用い、図３に示した第１の実施の形態および図５に示した第２の実施の形態に従って素管Ｗの端部Ｗ´にスピニング成形を加えて、長さが約６５ｍｍのテーパ部Ｗａと長さが約１５ｍｍで口径（ｄ）が約５５ｍｍのストレート部Ｗｂとを有する成形体Ｆを得た。成形体Ｆは第１の実施の形態で得られたものを参考品、第２の実施の形態で得られたものを本発明品としてそれぞれ区分し、これら成形体Ｆについて、図７に示すように、その非成形部Ｗ″側からストレート部Ｗｂの中間に至るまで、１０ｍｍピッチで板厚を測定した。また、比較のため、同じ板厚（１．２ｍｍ）の同径の素管Ｗに対し、前記図１０に示した改良タイプのスピニング成形を加えて改良品を得ると共に、板厚１．５ｍｍの同径の素管に対し、前記図９に示した一般的なスピニング成形を加えて従来品を得、これら改良品および従来品についても、前記同様に板厚を測定した。
【００２７】
図７は、上記した板厚の測定結果を示したものである。同図に示す結果より、従来品では、テーパ部Ｗａおよびストレート部Ｗｂの板厚が素管Ｗの板厚（１．４ｍｍ）よりも薄くなっており、特にテーパ部Ｗａの、非成形部Ｗ″側に寄った部位（カの部位）に板厚の著しく薄くなる部分が生じる。一方、改良品の場合は、テーパ部Ｗａの中間部の板厚が素管Ｗの板厚（１．２ｍｍ）に対して、１．６ｍｍ以上とかなり厚くなっているが、ストレート部Ｗｂ側特にストレート部Ｗｂとテーパ部Ｗａとの境界部Ｗｃ付近の板厚が、元の素管Ｗの板厚（１．２ｍｍ）に近いレベルまで減じている。これに対し、参考品は、テーパ部Ｗａの中間部はもとより、前記境界部Ｗｃを含むストレート部Ｗｂの板厚が１．６ｍｍ以上（４０％以上の増肉）となっており、成形部の全体に増肉効果がゆきわっていることが明らかである。また、本発明品は、境界部Ｗｃを含むテーパ部Ｗａおよびストレート部Ｗｂの板厚が１．３ｍｍ程度に平均化しており、素管Ｗの非成形部Ｗ″との間の板厚差が本発明品１に比べて大幅に減じている。
【００２８】
【発明の効果】
以上、説明したように、本発明によれば、素管の管端を押える押圧工具を用いることなく成形を行うので、成形設備にかかるコストが大幅に低減する。しかも、境界部を含めたテーパ部およびストレート部の板厚は、素管の非成形部との間に大きな差を生じない状態で平均化されるので、得られる成形体に対する強度的信頼性は著しく向上する。また、初期段階に素管の中央側から管端側へ成形工具を送って高能率にテーパ形状に絞った後に、成形工具の往復運動による絞りを行うので、全体の成形時間の短縮が可能になる。
一方、本発明に係る触媒コンバータ容器によれば、上記したスピニング成形により境界部を含めたコーン部および接続部の板厚が、触媒保持部との間に大きな差を生じない状態で平均化されているので、応力集中が緩和され、強度的信頼性が高いものとなる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態としてのスピニング成形方法の基本工程を模式的に示す断面図である。
【図２】本第１の実施の形態により得られた成形体の形状を示す断面図である。
【図３】本第１の実施の形態にける成形過程を順を追って示す模式図である。
【図４】本第１の実施の形態を実行する際の成形フローを示すフローチャートである。
【図５】本発明の第２の実施形態としてのスピニング成形方法の基本工程を模式的に示す断面図である。
【図６】本第１の実施の形態を実行する際の成形フローを示すフローチャートである。
【図７】本発明に係るスピニング成形方法により得られた成形体のテーパ部およびストレートにおける板厚分布を、比較例と対比して示すグラフである。
【図８】従来の一般的な触媒コンバータの構造を示す断面図である。
【図９】従来の一般的なスピニング成形方法の実施状況を模式的に示す断面図である。
【図１０】本発明者等による改良スピニング成形方法の実施状況を模式的に示す断面図である。
【符号の説明】
１触媒コンバータ容器
２触媒保持部
３接続部
４コーン部
１０クランパ
１１成形工具（成形ローラ）
Ｗ素管
Ｗ’ 素管の端部
Ｗａテーパ部
Ｗｂストレート部
Ｗｃ境界部
Ｓ触媒担体
Ｐ排気管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spinning molding method in which a tapered portion and a small-diameter straight portion are continuously formed at an end portion of a raw pipe, and a catalytic converter container integrally formed from the raw pipe by this spinning molding method.
[0002]
[Prior art]
For example, as shown in FIG. 8, a catalytic converter for purifying exhaust gas equipped in an exhaust system of an automobile has a structure in which a catalyst carrier S is housed in a metal container 1, and usually extends from an engine. The exhaust pipe P is inserted in series in the middle. In such a catalytic converter, the container (catalytic converter container) 1 is provided with a relatively large-diameter catalyst holding part 2 for accommodating and holding the catalyst carrier S in the center part, and is connected (welded) to the exhaust pipe P. And a cone portion 4 that gradually decreases in diameter from the catalyst holding portion 2 toward the connection portion 3.
[0003]
Conventionally, in order to reduce the manufacturing cost, this type of catalytic converter container 1 is formed by integrally forming the cone portion 4 and the connection portion 3 by adding spinning forming to the end portion of the raw tube, and unforming the raw tube. The part is used as it is as the catalyst holding part 2.
FIG. 9 shows a conventional spinning forming method, in which the intermediate portion of the raw tube W is clamped by the clamper 10 and the forming tool 11 is relatively revolved around the axis O of the raw tube W. However, the taper portion Wa and the straight portion Wb are sent from the clamped side (intermediate portion side) to the tube end side by the clamper 11 in a direction parallel to the direction inclined to the axis O of the raw tube W as indicated by a thick line arrow. Are formed at the same time, and this feeding (pass) is repeated to form the cone portion 4 and the connecting portion 3 having a predetermined size and shape.
[0004]
By the way, this type of catalytic converter container 1 needs to be as thin as possible in order to reduce the weight, reduce the material cost, reduce the heat capacity, and increase the catalyst efficiency at the initial idling. On the other hand, in order to ensure the strength and rigidity that can withstand the bending moment applied to the exhaust pipe P, it is necessary to make the connecting portion 3 as thick as possible.
However, according to the general spinning forming shown in FIG. 9, since the forming tool 11 is fed from the clamped side of the raw tube W to the tube end side and the forming proceeds, the material is moved to the tube end side where the free end is formed. Flow, the thickness of the connecting part 3 and the cone part 4 tend to be thinner than the thickness of the raw tube W, and in order to ensure the strength and rigidity of the connecting part 3, select a thick tube as the raw tube W I was in a situation where I had to. Further, in this spinning molding, since the forming tool 11 is returned to the middle of the taper portion Wa (indicated by a thin line arrow) and sent back to the tube end side, the upper side of the taper portion Wa (closed to the clamped side) is repeated. There is also a problem that a local thin portion Wf is easily formed in the portion), and the thin portion Wf becomes a stress concentration portion.
[0005]
Therefore, conventionally, in order to increase the thickness of the connecting portion 3 and the cone portion 4 as compared with the raw tube, in the spinning forming method shown in FIG. 9, the tube end of the raw tube W is pivoted by a pressing tool (rotating body). The thickness of the plate from the catalyst holding unit 2 to the tip of the connection unit 3 is gradually increased by controlling the material flow toward the tube end and restricting the flow of the material toward the tube end (for example, Patent Document 1). , See Patent Document 2).
In addition, as shown in FIG. 10, the present inventors, for the raw tube W clamped by the clamper 10, incline the forming tool 11 with a direction parallel to the axis O of the raw tube W as indicated by a thick arrow. The straight part Wb and the taper part Wa are simultaneously molded from the pipe end side to the clamped side, and the boundary part Wc between the straight part Wb and the taper part Wa is clamped each time this feed (pass) is repeated. The improved spinning forming method that eliminates the need to press the pipe end is devised, and has already been clarified in Japanese Patent Application No. 2001-313876 (unknown).
[0006]
[Patent Document 1]
JP 11-1332038 A [Patent Document 2]
Japanese Patent Laid-Open No. 2000-179334
[Problems to be solved by the invention]
However, according to the spinning forming method described in Patent Documents 1 and 2, since a pressing tool for pressing the tube end of the raw tube W and a device for supporting the pressing tool are necessary, the cost burden on the forming equipment increases. There was a problem.
On the other hand, according to the improved spinning forming method shown in FIG. 10, the material is likely to gather in the middle of the taper portion Wa, so that there is a problem that the thickness increase near the boundary portion Wc which is a bent portion is insufficient. there were.
[0008]
The present invention has been made in view of the above-described problems, and the object of the present invention is to enable sufficient thickness increase without pressing the tube end with a pressing tool, thereby reducing the equipment cost. An object of the present invention is to provide a spinning molding method that greatly contributes to the stable improvement of strength, and to provide a catalytic converter container molded by the spinning molding method.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problem, the spinning forming method according to the present invention sends the forming tool to the radial direction and the axial direction of the raw pipe while relatively revolving around the axis of the raw pipe, and ends the raw pipe. In a spinning molding method of molding a tapered portion gradually reducing the diameter toward the tip and a small-diameter straight portion continuous to the tapered portion, first, in a direction in which the molding tool is inclined to the axis of the raw tube, From the intermediate side to the tube end side, the end of the raw tube is squeezed into a taper shape, and then the forming tool is reciprocated in a direction inclined to the axis of the raw tube, thereby Further reducing the throttle part and increasing the thickness of the throttle part, and then sending the forming tool from the pipe end side to the intermediate part side in a direction parallel to the axis of the raw pipe And the boundary between the straight part and the taper part is increased. Is allowed, ultimately, and performing said forming tool are moved to the direction parallel to the direction inclined to the axis of the base pipe and finish forming.
In the spinning molding method of the present invention, after the pipe end is thinned in the initial stage, the pipe end is increased in the middle stage, so that the taper part and the straight part to be finally formed are increased more than necessary. There is no meat. Also, by forming a straight part by sending a forming tool from the pipe end side to the intermediate part side at the end stage, the thickness of the boundary part increases, and the thickness of the taper part and the straight part including the boundary part is almost constant. Become. In addition, since the forming tool is sent from the center side to the pipe end side at the initial stage and is highly efficiently squeezed into a tapered shape, the forming tool is squeezed by reciprocating motion, so that the entire forming time is shortened. Of course, since the forming is performed without using a pressing tool for pressing the tube end of the raw tube, the cost of the forming equipment is greatly reduced.
In order to solve the above problems, a catalytic converter container according to the present invention is formed by integrally forming a taper portion and a straight portion at an end portion of a raw tube by the spinning forming method according to claim 1, and non-forming the raw tube. The catalyst is used as a catalyst holding part in which the catalyst carrier is housed and held, the straight part is used as a connection part to which an exhaust pipe is connected, and the taper part is used as a cone part connecting the catalyst holding part and the connection part. In the converter container, the plate thickness of the connection portion and the cone portion is thicker than the plate thickness of the catalyst holding portion including the boundary portion between the two portions, and the plate thickness is averaged to be almost constant. It is characterized by.
In the catalytic converter container configured as described above, the connecting portion and the cone portion are thicker than the plate thickness of the catalyst holding portion including the boundary portion between the two portions , and the plate thickness is averaged almost constant . , Stress concentration is relaxed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows the basic steps of a first embodiment of the spinning molding method according to the present invention. In the first embodiment, in the initial to middle stage, as shown in FIG. 1A, the forming tool 11 is reciprocated in the direction inclined to the axis O of the raw tube W (thick arrows A and A). ), The end W ′ of the raw tube W is narrowed to a tapered shape. Further, at the final stage, as shown in FIG. 2B, the forming tool 11 is reciprocated in a direction parallel to the axis O of the raw tube W and a direction inclined (indicated by bold arrows B and B ′). ), The taper portion Wa and the straight portion Wb are formed. Thus, in the initial to middle stage, by narrowing the end portion (tube end portion) W ′ of the raw tube W only by the linear reciprocating motion of the forming tool 11, from the intermediate portion of the tube end portion W ′ to the tip side. Thickening progresses almost uniformly. On the other hand, since the taper portion Wa and the straight portion Wb are formed at the final stage after the increase in thickness in this way, almost no material flow occurs at this stage, and therefore the taper portion Wa and the straight portion to be obtained are obtained. The plate thickness with Wb is sufficient including the boundary portion Wc between the two portions.
[0011]
The first embodiment is applied to the molding of the catalytic converter container 1 shown in FIG. 8, and the obtained molded body F has a non-molded portion W of the raw tube W as shown in FIG. ″ Is the catalyst holding portion 2 that houses and holds the catalyst carrier S (FIG. 8), the straight portion Wb is the connecting portion 3 that connects the exhaust pipe P (FIG. 8), and the tapered portion Wa is the cone portion 4. However, the molded body F includes a connecting portion 3 (Wb) to which the exhaust pipe P is connected, and a boundary portion 5 between the connecting portion 3 and the cone portion (Wa) 4. Since the plate thickness of (Wc) is sufficiently thicker than the plate thickness of the raw tube W, sufficient strength and rigidity necessary for the connection of the exhaust pipe P are ensured. As a result, it becomes possible to use a thinner wall and to use a thin walled tube W. Not only material costs are reduced, but also lighter weight is realized, and the heat capacity of the catalyst holding unit 2 is reduced by using a thinner tube W, and heating of the catalyst carrier S is promoted during initial idling for purification. Increases efficiency.
[0012]
In manufacturing the catalytic converter, after forming the tapered portion Wa (cone portion 4) and the straight portion Wb (connecting portion 3) at one end W ′ of the raw tube W, the workpiece W ″ (catalyst holding) The catalyst carrier S is accommodated in the portion 2), and thereafter the taper portion Wa (cone portion 4) and the straight portion Wb (connecting portion 3) are formed on the other end portion of the raw tube W. After the catalyst carrier S is accommodated in W, the taper portion Wa (cone portion 4) and the straight portion Wb (connecting portion 3) may be sequentially formed at both ends thereof.
[0013]
Hereinafter, the spinning molding method according to the first embodiment will be described in detail with reference to FIGS.
At the time of spinning forming, as shown in FIG. 3 (1), the clamper 10 in the spinning forming apparatus clamps the intermediate portion in the longitudinal direction of the raw tube W, and a pair of forming is performed on the clamped raw tube W. The tool (forming roller) 11 is moved in the radial direction (Y-axis direction) and the axial direction (X-axis direction) while revolving around the axis O of the raw tube W. The raw tube W is selected to have the same diameter as the inner diameter of the catalyst holding portion 2 of the catalytic converter container 1 (FIG. 8) to be molded, and the plate thickness is appropriately determined in consideration of the increase in thickness by this spinning molding. Choose one. The raw tube W may be a welded tube or a seamless tube.
[0014]
The revolution of the forming tool 11 and the movement in the X-axis and Y-axis directions are controlled by a control device in the spinning forming apparatus, and as shown in FIG. 4, according to the start (S1). First, the revolution speed of the forming roller 11 is appropriately selected and its drive source is driven (S2), and then the stroke number a is set to 0 (a = 0) in step S3. In the following description, for convenience of explanation, the movement of the molding roller 11 in the right direction in FIG. 3 is advanced by the X axis, and the movement of the molding roller 11 in the opposite direction (left direction in the figure) is the X axis. The backward movement and the movement of the forming roller 11 in the radial inward direction are referred to as Y-axis advance, and the movement of the forming roller 11 in the outward radial direction is referred to as Y-axis backward movement, respectively.
[0015]
In the spinning molding, first, the number of strokes 1 to be performed is added in step S4 (a = a + 1), and the initial to middle-stage spinning molding shown in FIG. 3 (2) and step S5 in FIG. 4 is performed. In this spinning molding, the molding roller 11 is moved forward from the tube end side to the clamped side by the clamper 10 while the molding roller 11 is gradually retracted in the Y axis, that is, the revolution diameter of the molding roller 11 is gradually increased. While the forming roller 11 is moved forward in the Y axis, that is, while the revolution diameter of the forming roller 11 is gradually reduced, the forming roller 11 is moved backward from the clamped side to the tube end side. As a result, the forming tool 11 reciprocates as indicated by the thick arrows A and A ′ in a direction inclined to the axis O of the raw tube W, and the end W ′ of the raw tube W is narrowed to a taper shape accordingly. . At this time, if the movement amount in the X-axis direction is α and the movement amount in the Y-axis direction is β, the movement locus A → of the forming roller 11 from the tube end side to the clamped side becomes [αX → −βY →] On the other hand, the movement trajectory A ′ → of the forming roller 11 from the clamped side to the tube end side is [−αX → + βY →].
[0016]
After one reciprocating motion (one stroke) of the forming roller 11, it is determined in step S6 of FIG. 4 whether or not the diameter da of the pipe end has reached a value [d + δ] obtained by adding a predetermined margin δ to the target diameter d. If it has been judged and has not been reached, the number of strokes is counted again (S4), and the reciprocating motion is performed while further pushing the forming roller 11 (S5), and the reciprocating motion is continued until the diameter da of the tube end becomes [d + δ] or less. Is repeated.
When the pipe end diameter da becomes equal to or less than [d + δ], the final spinning forming shown in step S7 of FIG. 3 (3) and FIG. 4 is performed. In this spinning forming, the forming tool 11 is reciprocated in the direction parallel to the axis O of the raw tube W and the direction inclined, as indicated by the thick line arrows B and B ′, and the taper portion Wa and the straight portion Wb are simultaneously moved. Mold. At this time, the reciprocating motion of the forming tool 11 is usually required only once, but the reciprocating motion of the forming tool 11 may be repeated two or more times depending on the size of the margin δ (S6) to be set.
Thereafter, the forming roller 11 is retracted in the Y axis (S8) and the X axis is retracted (S9), the forming roller 11 is returned to the start position, and the rotation (revolution) is stopped (S10). Thus, the series of spinning molding ends (stops) (S11).
[0017]
In the first embodiment, the raw tube W is fixed and the forming tool 11 is revolved around the axis O of the raw tube W. However, the forming tube 11 is not revolved. W may be rotated about its axis O.
In the above-described embodiment, the forming roller 11 is reciprocated even in the final stage of molding. However, in this final stage, the pipe end side of the raw tube W is to be clamped, or the pipe is to be clamped from the clamped side. The forming roller 11 may be moved only once to the end side.
[0018]
FIG. 5 shows the basic steps of the second embodiment of the spinning molding method according to the present invention. In the second embodiment, at the initial stage, as shown in FIG. 1A, the forming tool (forming roller) 11 is inclined to the axis O of the raw tube W in the direction to be clamped (intermediate). From the section side) to the pipe end side (indicated by thick arrows C and C ′), the pipe end W ′ is narrowed to a tapered shape. This forming is a processing mode similar to the general spinning forming shown in FIG. 9, whereby the material flows toward the tube end side, and the plate thickness of the drawn portion becomes slightly thinner than the plate thickness of the raw tube W. Further, in this step, the operation of returning the forming tool 11 to the middle of the taper portion Wa (indicated by the thin line arrow) and then sending it to the tube end side is repeated, so that the upper side of the throttle portion (site close to the clamped side) A locally thin portion Wf is formed.
[0019]
In the middle stage, as shown in FIG. 5 (2), the forming tool 11 is reciprocated in the direction inclined to the axis O of the raw tube W (indicated by thick arrows A and A ′), and the throttle portion (tube Further narrow the end W ′). This forming is the same processing mode as the initial to intermediate stage in the first embodiment shown in FIG. 1 (1), thereby increasing the thickness of the pipe end W ′ that has been thinned in the initial stage. The thin wall portion Wf is also eliminated.
[0020]
At the final stage, as shown in FIG. 5 (3), the forming tool 11 is fed in a direction parallel to the axis O of the raw tube W by a small distance from the tube end side to the clamped side (indicated by a thick arrow D). ), Forming the straight portion Wb. Then, at the same time as forming the straight portion Wb, the tapered portion Wa approaches the final shape, and a bent boundary portion Wc appears between the two. Thus, in this final stage, by repeatedly feeding the forming tool 11 from the tube end side to the clamped side, the material on the tube end side is brought closer to the boundary portion Wc, and thereby the vicinity of the boundary portion Wc is increased in thickness. Is done. That is, the lack of thickness increase near the boundary portion Wc that may occur during the improved type of spinning molding shown in FIG. 10 is resolved.
[0021]
Further, in the final stage, as shown in FIG. 5 (4), the forming tool 11 is sent from the clamped side to the tube end side in a direction parallel to the direction inclined to the axis O of the raw tube W (thick arrow). E)), and finish molding is performed, whereby a molded body F (FIG. 2) having a desired dimensional shape is obtained. Note that the feeding direction of the forming tool 11 in this final stage is arbitrary, and it may be fed from the tube end side to the clamped side.
[0022]
In the second embodiment, as described above, after the pipe end is once thinned in the initial stage, the pipe end is increased in the middle stage. And the straight portion Wb is not increased more than necessary. Therefore, a large difference in plate thickness does not occur between the non-formed portion W ″ (FIG. 2) of the raw tube W and the tube end portions (Wa, Wb) after forming, and the boundary portion between the two is the stress concentration portion. In addition, the thin-walled portion Wf generated in the initial stage is eliminated by the reciprocating motion of the forming tool 11 in the intermediate stage, and the material approach to the boundary part Wc in the final stage process causes the vicinity of the boundary part Wc. Since the thinning is also prevented, the thicknesses of the taper portion Wa and the straight portion Wb including the boundary portion Wc are averaged, and no stress concentration portion remains at the tube end portion. The strength reliability with respect to is extremely high.
[0023]
By the way, when the tube end portion W ′ is squeezed by the reciprocating motion of the forming tool 11, wrinkles are likely to occur, so that there is a restriction that the squeezing amount per pass cannot be made very large. On the other hand, when the forming tool 11 is sent from the clamped side to the tube end side to narrow the tube end portion W ′, the amount of drawing per pass can be made relatively large, and the forming efficiency is improved accordingly. In the second embodiment, since the drawing with high forming efficiency (FIG. 5 (1)) is performed at the initial stage, the subsequent forming, that is, the drawing by reciprocating movement of the forming tool 11 (FIG. 5). The number of passes (2)) can be greatly reduced as compared with the first embodiment, and the time required for the entire molding is reduced accordingly.
[0024]
FIG. 6 shows a specific molding flow in the second embodiment. The same steps as those in the molding flow (FIG. 4) in the first embodiment are denoted by the same reference numerals. . In the second embodiment, according to the start (S1), the revolution speed of the forming roller 11 is appropriately selected and its drive source is driven (S2). The initial stage drawing (spinning) shown in 1) is performed. In this spinning forming, the forming tool 11 is sent from the clamped side to the tube end side so that the tube end portion W ′ is narrowed into a tapered shape, so that the amount of drawing per pass is relatively large as described above. The molding can be completed in a short time.
[0025]
Thereafter, in the same steps S3 to S6 as in the first embodiment, the middle-stage spinning forming shown in FIG. 5B is performed, and the tube end W ′ is further narrowed by the reciprocating motion of the forming tool 11. In addition, the squeezed portion is increased in thickness.
When it is determined in step S6 that the pipe end diameter da has reached a value [d + δ] obtained by adding a predetermined margin δ to the target diameter d, the end stage shown in FIG. Stage molding is performed, and finish molding is further performed in step S23. The forming of S22 includes the content of bringing the material on the tube end side toward the boundary portion Wc by repeating the feeding of the forming tool 11 from the tube end side to the clamped side, thereby increasing the thickness of the boundary portion Wc. . In addition, the molding in step 23 includes the content of performing dimensioning by sending the molding tool 11 from the clamped side to the tube end side or from the tube end side to the clamped side, thereby forming a molded body having a desired dimension and shape. F (FIG. 2) is obtained.
Thereafter, through the same steps S8 to S10 as in the first embodiment, the forming tool 11 returns to the start position and stops rotating (revolution), thereby completing (stopping) a series of spinning forming operations (S11). ).
[0026]
【Example】
Using an element tube W having an outer diameter of 114 mm and a plate thickness of 1.2 mm, spinning is performed on an end W ′ of the element tube W according to the first embodiment shown in FIG. 3 and the second embodiment shown in FIG. Molding was applied to obtain a molded body F having a tapered portion Wa having a length of about 65 mm and a straight portion Wb having a length of about 15 mm and a diameter (d) of about 55 mm. The molded product F is divided into the product obtained in the first embodiment as a reference product and the product obtained in the second embodiment as a product of the present invention , and these molded products F are shown in FIG. In addition, the plate thickness was measured at a pitch of 10 mm from the non-molded portion W ″ side to the middle of the straight portion Wb. For comparison, an element tube W having the same plate thickness (1.2 mm) and the same diameter was also measured. On the other hand, the improved type spinning forming shown in FIG. 10 is added to obtain an improved product, and the general spinning forming shown in FIG. Conventional products were obtained, and the plate thickness of these improved products and conventional products was measured in the same manner as described above.
[0027]
FIG. 7 shows the measurement results of the plate thickness described above. From the results shown in the figure, in the conventional product, the thickness of the taper portion Wa and the straight portion Wb is thinner than the plate thickness (1.4 mm) of the raw tube W, and in particular, the non-molded portion W of the taper portion Wa. ″ A portion where the plate thickness is remarkably reduced occurs at the portion (figure portion) that is closer to the ″ side. ) Is considerably thicker than 1.6 mm, but the thickness of the straight portion Wb side, particularly in the vicinity of the boundary portion Wc between the straight portion Wb and the tapered portion Wa, is the thickness of the original tube W (1 In contrast, in the reference product , the thickness of the straight portion Wb including the boundary portion Wc is 1.6 mm or more (40% or more) in addition to the intermediate portion of the taper portion Wa. (Thickening), and the effect of increasing the thickness of the molded part It is clear. Further, the product of the present invention, the thickness of the tapered portion Wa and the straight portion Wb including the boundary portion Wc has averaged about 1.3 mm, between the non-forming portion W "of the base pipe W The plate thickness difference is significantly reduced as compared with the product 1 of the present invention.
[0028]
【The invention's effect】
As described above, according to the present invention , molding is performed without using a pressing tool for pressing the pipe end of the raw pipe, so that the cost for the molding equipment is greatly reduced. In addition, the thickness of the taper part and the straight part including the boundary part is averaged in a state that does not cause a large difference from the non-molded part of the raw tube, so the strength reliability for the obtained molded body is Remarkably improved. In addition, since the forming tool is sent from the center side to the pipe end side in the initial stage and is highly efficiently squeezed into a tapered shape, the forming tool is squeezed by reciprocating movement, so the overall forming time can be shortened. Become.
On the other hand, according to the catalytic converter container of the present invention, the plate thickness of the cone part and the connection part including the boundary part is averaged in the state in which no significant difference is generated between the catalyst holding part and the catalyst holding part. Therefore, the stress concentration is relaxed and the strength reliability is high.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a basic process of a spinning molding method as a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the shape of a molded body obtained according to the first embodiment.
FIG. 3 is a schematic diagram illustrating the molding process in the first embodiment step by step.
FIG. 4 is a flowchart showing a molding flow when executing the first embodiment.
FIG. 5 is a cross-sectional view schematically showing a basic process of a spinning molding method as a second embodiment of the present invention.
FIG. 6 is a flowchart showing a molding flow when executing the first embodiment.
FIG. 7 is a graph showing a plate thickness distribution in a tapered portion and a straight portion of a molded body obtained by the spinning molding method according to the present invention in comparison with a comparative example.
FIG. 8 is a cross-sectional view showing the structure of a conventional general catalytic converter.
FIG. 9 is a cross-sectional view schematically showing an implementation state of a conventional general spinning forming method.
FIG. 10 is a cross-sectional view schematically showing an implementation status of the improved spinning molding method by the present inventors.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Catalytic converter container 2 Catalyst holding part 3 Connection part 4 Cone part 10 Clamper 11 Molding tool (molding roller)
W Elementary pipe W ′ End part Wa of element pipe Wa Taper part Wb Straight part Wc Boundary part S Catalyst carrier P Exhaust pipe

Claims

A taper part that gradually sends a forming tool to the radial direction and the axial direction of the raw pipe while relatively revolving around the axis of the raw pipe and gradually reduces the diameter toward the tip of the raw pipe, and the tapered part In the spinning forming method of forming a straight portion having a small diameter continuous with the first, the forming tool is first sent in the direction inclined to the axis of the raw tube from the intermediate portion side to the tube end side to end the raw tube. The part is squeezed into a taper shape, and then the forming tool is reciprocated in a direction inclined to the axis of the base pipe to further squeeze the throttle part at the end of the base pipe and increase the plate thickness of the throttle part. Next, the forming tool is sent in the direction parallel to the axis of the raw pipe from the pipe end side to the intermediate part side to form the straight part, and the boundary part between the straight part and the taper part is formed. The thickness is increased, and finally, the forming tool is inclined in the direction inclined to the axis of the blank tube. Spinning molding method and performing finish forming by moving the the a direction.

A taper portion and a straight portion are integrally formed at an end portion of the raw tube by the spinning forming method according to claim 1, and the non-formed portion of the raw tube is used as a catalyst holding portion in which a catalyst carrier is housed and held. A catalytic converter container that serves as a connecting portion to which an exhaust pipe is connected and the tapered portion serves as a cone portion that connects the catalyst holding portion and the connecting portion, respectively, and the plate thickness of the connecting portion and the cone portion However, the catalytic converter container is characterized in that it is thicker than the plate thickness of the catalyst holding portion including the boundary portion between the two portions, and is averaged at a substantially constant plate thickness .