JP2005000960A

JP2005000960A - Rocker arm and its production method

Info

Publication number: JP2005000960A
Application number: JP2003168250A
Authority: JP
Inventors: Shoichi Abe; 正一阿部; Kiyoshi Okubo; 潔大久保; Yasushi Watanabe; 靖渡辺; Takanori Oshima; 崇徳大嶋
Original assignee: NSK Ltd; NSK Steering Systems Co Ltd
Current assignee: NSK Ltd; NSK Steering Systems Co Ltd
Priority date: 2003-06-12
Filing date: 2003-06-12
Publication date: 2005-01-06

Abstract

<P>PROBLEM TO BE SOLVED: To improve the performance of an engine incorporating a rocker arm produced by applying cold-forging to a metallic wire rod-made blank. <P>SOLUTION: The blank obtained by cutting off the metallic wire rod into a prescribed length is pressed from both sides in the axial direction of the blank, so that cold-forging is applied to the blank and a barrel-shaped first intermediate blank 33 having the maximum diameter at the axially intermediate part is produced. Successively, the cold-forging is applied to the first intermediate blank 33 by pressing the blank 33 from both sides in the diametrical direction of the first intermediate blank 33, and a second intermediate blank 34b provided with one pair of side wall parts 2a and a base part 39 connecting both of one end parts of both side wall parts 2a in the width direction is produced. When the cold-forging is performed, burr on the outer peripheral side is not caused. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、カムシャフトの回転を弁体（吸気弁及び排気弁）の往復運動に変換する為、エンジンの動弁機構に組み込んだ状態で使用する、ロッカーアーム及びその製造方法に関する。
【０００２】
【従来の技術】
レシプロエンジン（往復ピストンエンジン）には、一部の２サイクルエンジンを除き、クランクシャフトの回転と同期して開閉する吸気弁及び排気弁を設けている。この様なレシプロエンジンでは、上記クランクシャフトの回転と同期して（４サイクルエンジンの場合には１／２の回転速度で）回転するカムシャフトの動きを、ロッカーアームにより、上記吸気弁及び排気弁に伝達し、これら吸気弁及び排気弁をそれぞれの軸方向に往復運動させる場合がある。
【０００３】
この様なエンジンの動弁機構に組み込むロッカーアームとして従来一般的には、鋳造品（鋳鉄品或はアルミニウムダイキャスト品）を使用していた。又、近年、鋼板等の金属板にプレス加工を施す事により上記ロッカーアームを造る事も考えられ、一部で実施されている。但し、この様な鋳造品のロッカーアームや、金属板製のロッカーアームの場合には、製造作業に要する時間が長くなったり、材料の無駄が多くなる事により、コストが嵩むと言った問題がある。
【０００４】
これに対して、特許文献１に記載されている様に、金属線材を所定長さに切断して得た素材（ブランク）に冷間鍛造を施す事によりロッカーアームを製造する方法が提案されている。特許文献１によると、金属線材から成る素材に冷間鍛造を施す事によりロッカーアームを造れば、亀裂の発生がなく高精度に製造でき、作業性を良好にできるとしている。又、ロッカーアームをこの様な冷間鍛造により造れば、熱間鍛造により造る場合に比べて、形状精度及び寸法精度を高くできる。図２２〜２８は、上記特許文献１に記載された、ロッカーアームとその製造方法とに関する発明を表している。尚、このロッカーアームの製造方法に就いては、上記特許文献１に詳しく記載されている為、ここでは簡単に説明する。ロッカーアーム１は、図２２に示す様に、互いにほぼ平行な１対の側壁部２、２と、これら両側壁部２、２の長さ方向両端部同士を連結する第一の連結部３及び第二の連結部４とを有する。これら第一の連結部３及び第二の連結部４のうち、第一の連結部３は、弁体の基端部を突き当てる為の第一の係合部６を、第二の連結部４は、ラッシュアジャスタ等の揺動支持部材の先端部を突き当てる為の第二の係合部７を、それぞれ有する。
【０００５】
又、特許文献１には記載されていないが、実際に使用するロッカーアームの場合には、上記両側壁部２、２の長さ方向中間部に１対の円孔を、互いに同心に形成し、これら両円孔に、カムと係合するローラを回転自在に支持する為の支持軸の両端部を支持自在とする。
【０００６】
上述の様なロッカーアーム１を造る作業は、次の様にして行なう。先ず、図２３に示す様に、回転支持装置８にコイル状に巻回した金属線材９の端部を、冷間鍛造成形機１０に設けたローラ式線材供給機構１１により引き出して、この冷間鍛造成形機１０の内部に導入する。上記金属線材９は、断面が矩形状である。又、この金属線材９を予めリン酸亜鉛等の潤滑液槽に漬け込み、この金属線材９の外周面に潤滑皮膜層を形成する。そして、第一工程として、図２４に示す様に、上記冷間鍛造成形機１０に設けた切断機構１２で、上記金属線材９を所定長さに切断する事により、直方体状の素材（ブランク）１３を造る。尚、上記冷間鍛造成形機１０は、横型多段式鍛造成形機と呼ばれるもので、内側に固設されたダイブロック１４と、このダイブロック１４に対し接近又は離隔（遠近動）する様に水平方向に往復運動するラム１５とを備える。このうちのダイブロック１４には、複数の固定型１６ａ〜１６ｄを、水平方向に互いに間隔をあけて配置している。又、上記ラム１５の一部で、これら固定型１６ａ〜１６ｄと対向する位置に、複数の可動型１７ａ〜１７ｄを、それぞれ型ホルダ１８ａ〜１８ｄを介して配置している。そして、これら各固定型１６ａ〜１６ｄと各可動型１７ａ〜１７ｄとを配置した部分に、第一の鍛造ステーション１９と第一の打ち抜きステーション２０と第二の鍛造ステーション２１と第二の打ち抜きステーション２２とを、それぞれ設けている。上記第一工程により得られた直方体状の素材１３は、上記冷間鍛造成形機１０に設けた素材旋回供給機構２３により、この素材１３の向きを９０度変えつつ、上記第一の鍛造ステーション１９に供給する。
【０００７】
この第一の鍛造ステーション１９では、第二工程として、図２５に詳示する様に、可動型１７ａにより固定型１６ａに、上記素材１３を水平方向に打ち込む事で、この素材１３に冷間鍛造を施して、ロッカーアーム１の大まかな形状及び寸法を有する第一中間素材２４を造る。この第一中間素材２４は、１対の側壁部２（図２２）と、これら両側壁部２の幅方向中間部同士を連結する基部５１とを備えた、断面Ｈ字形である。又、上記第一中間素材２４の厚さ方向中間部外周面にバリ２５が、全周に亙り形成される。この様な冷間鍛造を行なう上記素材１３の外周面には予め潤滑皮膜層を形成している為、上記固定型１６ａ及び可動型１７ａの内面と、この素材１３の外面との間に作用する摩擦を小さく抑えられる。そして、この構成により、上記第一中間素材２４の成形作業性及び形状精度を良好にできる。この様な第二工程により得られた第一中間素材２４は、上記固定型１６ａと可動型１７ａとの間から取り出して、図２６に詳示する様な、第一の打ち抜きステーション２０に供給する。
【０００８】
この第一の打ち抜きステーション２０では、第三工程として、固定型１６ｂの通孔２６内に設けた筒状の押し出し部材２７の先端面と、筒状の可動型１７ｂの先端面との間で、上記第一中間素材２４のうち、上記バリ２５を除いた本体部分を挟持する。そして、上記通孔２６内にこの本体部分を押し込む事により、このバリ２５を、この通孔２６の開口端周縁部で除去する。これと同時に、上記押し出し部材２７の内側に設けた孔あけ用パンチ２８により、上記第一中間素材２４に設けた基部５１（図２５）の中間部を打ち抜いて、透孔２９を有する第二中間素材３０を造る。この透孔２９を形成する事により、この第二中間素材３０には、１対の側壁部２（図２２）の長さ方向両端部同士を連結する第一、第二の両連結部３、４が形成される。この様な第三工程により得られた第二中間素材３０は、上記固定型１６ｂと可動型１７ｂとの間から取り出して、図２７に詳示する様な、第二の鍛造ステーション２１に供給する。
【０００９】
この第二の鍛造ステーション２１では、第四工程として、可動型１７ｃにより固定型１６ｃに、上記第二中間素材３０を水平方向に打ち込む事により、この第二中間素材３０に冷間鍛造を施して、完成品に近い寸法及び形状を有する第三中間素材３１を造る。この際、この第三中間素材３１の厚さ方向中間部外周面と透孔２９の内周面とに、それぞれバリ２５ａ、２５ｂが形成される。この様な冷間鍛造を施す上記第二中間素材３０の外面には、予め潤滑皮膜層を形成している為、上記固定型１６ｃ及び可動型１７ｃの内面と、上記第二中間素材３０の外面との間に作用する摩擦を小さく抑えられる。そして、この構成により、上記第三中間素材３１の成形作業性及び形状精度を良好にできる。この様な第四工程が終了したならば、上記固定型１６ｃと可動型１７ｃとの間から上記第三中間素材３１を取り出して、この第三中間素材３１を、図２８に詳示する様な、第二の打ち抜きステーション２２に供給する。
【００１０】
この第二の打ち抜きステーション２２では、第五工程として、前記第三工程の場合と同様にして、上記第三中間素材３１の外周面に形成されたバリ２５ａを除去する。これと同時に、この第三中間素材３１の透孔２９の内周面に形成されたバリ２５ｂも除去して、ロッカーアーム１の完成品とする。このロッカーアーム１は、上記第二の打ち抜きステーション２２の固定型１６ｄと可動型１７ｄとの間から、例えば図示しない取り出し用チャックにより所定位置に取り出す。又、特許文献１には記載されていないが、実際に使用するロッカーアームの場合には、別の加工機械を用いて、各側壁部２（図２２）の中間部で互いに整合する位置に１対の円孔を形成する為の孔あけ加工を行なう事もある。
【００１１】
上述の様に構成する特許文献１に記載されたロッカーアームの製造方法の場合には、ロッカーアーム１を多段式の冷間鍛造機により製造する為、製造作業に要する時間を或る程度短縮でき、作業性を良好にできる。又、各可動型１７ａ〜１７ｄを水平方向に移動させる為、可動型を上下方向に移動させる事により鍛造作業を行なう場合に比べて、各可動型１７ａ〜１７ｄを往復移動させる為の駆動機構に加わる負担を小さくできる。この為、ロッカーアーム１を得る為の冷間鍛造作業の高速化を図り易くできる。
【００１２】
【特許文献１】
特開平１０−３２８７７８号公報
【００１３】
【発明が解決しようとする課題】
上述した特許文献１に記載されたロッカーアームの製造方法の場合には、次の▲１▼〜▲３▼の点で、得られるロッカーアーム１を組み込んだエンジンの性能向上の為の改良の余地がある。
▲１▼ ロッカーアーム１を得る為の鍛造工程である、第二、第四工程の総てで、素材１３（又は第二中間素材３０）を、互いに同方向である、軸方向（長さ方向）に対し直交する方向（基部５１又は各連結部３、４の厚さ方向）の両側から加圧する事により、この素材１３（又は第二中間素材３０）に冷間鍛造を施している。この為、上記第二、第四工程で、素材１３及び第二中間素材３０のうち、得られるロッカーアーム１の同じ部分に対応する一部に、過大な応力が集中し易くなり、得られるロッカーアーム１で強度を十分に確保する事が難しくなる。
【００１４】
又、上記素材１３は直方体状であり、軸方向（長さ方向）に関して断面積が一様である。これに対して、上記第二中間素材３０は、軸方向に関して断面積が一様ではない（大きく変化している）。故に、この第二中間素材３０を上記素材１３から直ちに冷間鍛造により得る事はできず、バリ２５を伴った第一中間素材２４を冷間鍛造により造り、その後の打ち抜き工程でこのバリ２５を除去して、上記第二中間素材３０を造らなければならない。
この様に、バリ２５を伴う冷間鍛造を行なうと、上記第二中間素材３０の内部の組織状の組織の流れである、ファイバーフローが、このバリ２５の流動方向に沿って新たに創製される。これに伴って、元の第一中間素材２４に形成されていたファイバーフローが、上記バリ２５部分で乱れて不連続になってしまう。又、後工程でこのバリ２５を除去する事により、この部分のファイバーフローが分断（切断）される。この様にファイバーフローが分断されると、得られるロッカーアーム１の完成品（製品）の強度が低下する傾向になる。又、バリを分断すると、これに伴い、剪断面や破断面が生じて、欠陥発生のおそれが生じるし、又、形状精度が悪化する原因となる。又、鍛造荷重が増大する為、大きな鍛造能力を有する設備が必要になる。又、当然ながら、バリ２５の為に、材料の損失量が多くなり、コストの増大を招く原因となる。
引用文献１に記載されたロッカーアームの製造方法の場合には、同様の事が第四、第五工程で繰り返される、即ち、バリ２５ａ、２５ｂを伴う冷間鍛造を施した後、これら各バリ２５ａ、２５ｂを除去する為、製品の強度低下や精度悪化が、ますます生じ易くなる。
又、冷間鍛造に伴って形成されるバリ２５、２５ａ、２５ｂのうちでも、外周側に生じるバリ（外バリ）２５、２５ａは、周囲に形成される為、容積が大きくなる。この為、内周側に生じるバリ（内バリ）２５ｂに比べて、材料の損失量が多くなる事が顕著になる。尚、内バリ２５ｂに就いては、発生させない事が望ましいが、やむを得ない場合には、ロッカーアーム１の完成品の使用に対し影響が少ない部分に設ける必要がある。
特許文献１に記載されたロッカーアームの製造方法の場合には、この様な点で、得られるロッカーアーム１を組み込んだエンジンの性能である、耐久性を向上できる余地がある。
【００１５】
▲２▼ 実際に使用するロッカーアーム１の場合には、前記各側壁部２（図２２）に、中間部にローラを支持した支持軸の両端部を支持する為の円孔を形成するが、これら各円孔が全長に亙って単なる円筒面である場合には、この支持軸の両端部をこれら各円孔に十分な結合強度を持って結合固定する事ができない。この為、ロッカーアーム１にローラを組み付けて構成した、カムフォロアの耐久性を十分に確保する事が難しくなる。即ち、上記各円孔を上述の様に単なる円筒面とした場合には、上記支持軸の両端部をこれら各円孔に、単なる圧入、接着、焼き嵌め等により固定しなければならず、上記カムフォロアの耐久性を十分に確保する事が難しくなる。特許文献１に記載されたロッカーアームの製造方法の場合には、上記各側壁部２に円孔を形成する事は記載されておらず、勿論、この円孔に対する支持軸の両端部の結合強度を向上させる事は考慮されていない。特許文献１に記載されたロッカーアームの製造方法の場合には、この様な点で、得られるロッカーアーム１を組み込んだエンジンの性能である、耐久性を向上できる余地がある。
【００１６】
▲３▼ 前記第二の鍛造ステーション２１等で、弁体又は揺動支持部材を突き当てる為の第一、第二の各係合部部６、７（図２２）を形成すべく冷間鍛造を行なう際に、第二中間素材３０等の一部で、これら第一、第二の各係合部６、７の近くに材料の余肉部の逃げ部を設ける事は考慮されていない。この為、これら第一、第二の各係合部６、７の形成の為に上記第二中間素材３０等の余肉部を効果的に逃がす事ができず、これら第一、第二の各係合部部６、７の形状精度及び寸法精度を良好にする事ができない。この為、ロッカーアーム１の所定位置に弁体又はラッシュアジャスタを、精度良く係合させる事が難しくなる。特許文献１に記載されたロッカーアームの製造方法の場合には、この様な点で、得られるロッカーアーム１を組み込んだエンジンの性能を向上できる余地がある。
本発明のロッカーアーム及びその製造方法は、この様な事情に鑑みて、金属線材製の素材に冷間鍛造を施す事によりロッカーアームを造る場合で、このロッカーアームを組み込んだエンジンの性能向上を図るベく発明したものである。
【００１７】
【課題を解決するための手段】
本発明のロッカーアームは何れも、金属線材を所定長さに切断する事で得られた素材に冷間鍛造を施す事により造られ、互いに間隔をあけて設けられた１対の側壁部と、これら両側壁部の長さ方向両端寄り部分同士を連結する第一、第二の連結部と、これら両側壁部の互いに整合する位置に形成された互いに同心の１対の通孔とを備え、これら第一、第二の各連結部が、弁体又は揺動支持部材と係合する係合部を有するものである。
【００１８】
特に、請求項１に記載したロッカーアームに於いては、上記素材を長さ方向両側から加圧する事によりこの素材に冷間鍛造を施して第一中間素材を造る工程と、この第一中間素材を上記長さ方向に対し直交する方向の両側から加圧する事によりこの第一中間素材に冷間鍛造を施して第二中間素材を造る工程とを備えた工程により造られている。
【００１９】
又、請求項４に記載したロッカーアームに於いては、上記各側壁部に上記各通孔を形成する際に、これら各通孔の外側開口端部に面取りを同時に形成している。
【００２０】
又、請求項６に記載したロッカーアームに於いては、上記素材又この素材から得られた中間素材に冷間鍛造を施す事により上記第一の係合部又は第二の係合部を形成した、中間素材又は別の中間素材を造る際に、この中間素材又は別の中間素材の一部で、上記１対の側壁部よりも幅方向内側に外れた部分のうち、長さ方向に関して上記第一の係合部又は第二の係合部を形成すべき部分と同位置の少なくとも一部を、上記冷間鍛造に使用する型を当てない逃げ部としている。
【００２１】
又、請求項８に記載したロッカーアームに於いては、内部の繊維状の組織の流れであるファイバーフローが、全体的にロッカーアームの長さ方向に流れており、このファイバーフローが、少なくともこの長さ方向の両端縁と、上記第一、第二の各連結部の間に形成された透孔の内周面とを除いた部分で切断されていない。
【００２２】
又、請求項２に記載したロッカーアームの製造方法は、上述の請求項１に記載したロッカーアームの製造方法であって、上記素材を長さ方向両側から加圧する事によりこの素材に冷間鍛造を施して第一中間素材を造る工程と、この第一中間素材を上記長さ方向に対し直交する方向の両側から加圧する事によりこの第一中間素材に冷間鍛造を施して第二中間素材を造る工程とを備える。
【００２３】
又、請求項３に記載したロッカーアームの製造方法は、上述の請求項１に記載したロッカーアームの製造方法であって、上記素材を長さ方向両側から加圧する事によりこの素材に冷間鍛造を施して、得るべきロッカーアームの長さ方向に関する、この長さ方向に対し直交する方向の断面積の変化に対応してその断面積を長さ方向に関して変化させた第一中間素材を造る工程と、この第一中間素材を上記長さ方向に対し直交する方向の両側から加圧する事によりこの第一中間素材に冷間鍛造を施して、外周側でのバリを発生させない工程とを備える。
【００２４】
又、請求項５に記載したロッカーアームの製造方法は、上述の請求項４に記載したロッカーアームの製造方法であって、各側壁部に各通孔を形成する際に、これら各通孔の外側開口端部に面取りを同時に形成する。
【００２５】
又、請求項７に記載したロッカーアームの製造方法は、上述の請求項６に記載したロッカーアームの製造方法であって、上記素材又この素材から得られた中間素材に冷間鍛造を施す事により第一の係合部又は第二の係合部を形成した、中間素材又は別の中間素材を造る際に、この中間素材又は別の中間素材の一部で、１対の側壁部よりも幅方向内側に外れた部分のうち、長さ方向に関して上記第一の係合部又は第二の係合部を形成すべき部分と同位置の少なくとも一部を、上記冷間鍛造に使用する型を当てない逃げ部とする。
【００２６】
【作用】
上述の様に構成される本発明のロッカーアーム及びその製造方法によれば、金属線材製の素材に冷間鍛造を施す事によりロッカーアームを造る場合で、このロッカーアームを組み込んだエンジンの性能向上を図れる。
即ち、請求項１に記載したロッカーアームの場合には、素材及び第一中間素材での冷間鍛造の際の加圧方向が９０度異なる。この為、総ての冷間鍛造工程で素材及び中間素材を同方向の両側から加圧する場合に比べて、得られるロッカーアームの一部に、過大な応力が集中する事を抑える事ができる。又、金属線材を押し出し成形により造った場合には、上記素材の内部の組織の繊維状の流れ（ファイバーフロー）が、この素材の長さ方向にほぼ一致する。そして、この素材から得られた第一中間素材のファイバーフローの多くを、この第一中間素材の長さ方向に対しほぼ平行にし、又は平行に近づける事ができる。請求項１に記載したロッカーアームの場合には、この様な第一中間素材を長さ方向に対し直交する方向に加圧する事によりこの第一中間素材に冷間鍛造を施している為、この第一中間素材を長さ方向両側から加圧する事によりこの第一中間素材に冷間鍛造を施す場合に比べて、得られるロッカーアームのファイバーフローをこのロッカーアームの全体形状に対応した滑らかな流れとする事ができる。これらの結果、得られたロッカーアームの強度を向上でき、このロッカーアームを組み込んだエンジンの耐久性の向上を図れる。
又、請求項３に記載したロッカーアームの製造方法の場合には、第一中間素材に冷間鍛造を施す際に外周側でのバリ（外バリ）を発生させない様にしている為、前述の特許文献１に記載されたロッカーアームの製造方法の場合と異なり、外バリ部分にファイバーフローが創製される事がない。この為、ファイバーフローを、この外バリ部分で乱される事もなく、この外バリの除去に伴って分断される事もない。この為、ロッカーアームの完成品（製品）の強度向上を図れる。又、外バリの除去に伴う剪断面や破断面に起因する欠陥が生じる事もなく、ロッカーアームの形状精度を良好にできる。更に、鍛造荷重を小さくできると共に、材料費の低減を図り易くなる。
尚、内周側に生じるバリ（内バリ）はない事が好ましいが、内バリが形成される場合でも、この内バリは、ロッカーアームの使用に対し影響を及ぼさない位置に設ける事が好ましい。
【００２７】
又、請求項４に記載したロッカーアームの場合には、各側壁部に形成した通孔の外側開口端周縁部に、ローラを支持する支持軸の両端部を（径方向外方に塑性変形させた部分と面取り部とを係合させる状態に）かしめ固定する事ができる。この為、ロッカーアームにローラを組み付けて成るカムフォロアで、上記各側壁部に上記支持軸の両端部を、十分な結合強度で結合固定でき、上記ロッカーアームを組み込んだエンジンの耐久性の向上を図れる。更に、この支持軸の端部を通孔に挿入する作業を容易に行なえる。この為、支持軸を結合したロッカーアームのコスト低減を図れる。
【００２８】
又、請求項６に記載したロッカーアームの場合には、第一の係合部又は第二の係合部を冷間鍛造により形成した、中間素材又は別の中間素材を造る際に、素材又は中間素材のうち、この第一の係合部又は第二の係合部を形成すべき部分の近い位置に存在する余肉部を、円滑に逃がす事ができる。この為、この第一の係合部又は第二の係合部の形状精度及び寸法精度を良好にでき、得られたロッカーアームの使用時に、このロッカーアームの所定位置に弁体又は揺動支持部材を精度良く係合させる事ができる。従って、このロッカーアームを組み込んだエンジンの性能向上を図れる。更に、上記冷間鍛造に使用する型に過大な荷重が加わる事を防止でき、この型の耐久性の向上を図れる。この為、ロッカーアームの量産時での単品のコストを低減できる。
【００２９】
又、請求項８に記載したロッカーアームの場合には、成形作業性を良好にできると共に、強度及び形状精度の向上を図れる。
【００３０】
【発明の実施の形態】
図１〜２１は、本発明の実施の形態の１例を示している。尚、本例の特徴は、金属線材製の素材３２（図６）に冷間鍛造を施す事によりロッカーアーム１ａ（図１〜４）を造る場合に、得られるロッカーアーム１ａを組み込んだエンジンの性能向上を図るべく、上記素材３２及びこの素材３２から得られる第一中間素材３３（図７）に冷間鍛造を施す際の加圧方向と、各側壁部２ａ、２ａに通孔５、５を形成する際の打ち抜き作業と、それぞれが第一、第二の各係合部である第一、第二の各凹部３６、４０を形成する際の冷間鍛造作業とを、それぞれ工夫した点にある。ロッカーアーム１ａの製造装置に就いては、前述の図２２〜２８に示した製造装置とほぼ同様である為、重複する説明は省略若しくは簡略にし、以下、本例の特徴部分を中心に説明する。
【００３１】
本例のロッカーアームの製造方法により得るロッカーアーム１ａは、図１〜４に示す様に、互いにほぼ平行でそれぞれ略三角形に形成した１対の側壁部２ａ、２ａと、これら両側壁部２ａ、２ａの長さ方向（図１、２の上下方向）両端部同士を連結する第一の連結部３ａ及び第二の連結部４ａとを有する。又、これら両側壁部２、２の長さ方向中間部に１対の円孔５、５を、互いに同心に形成し、これら両円孔５、５に、カムと係合するローラ３５を回転自在に支持する為の支持軸の両端部を支持固定自在としている。
【００３２】
又、弁体の基端部を突き当てる為、上記第一の連結部３ａの片面（図１、３の右側面、図２の表側面）に、第一の係合部である第一の凹部３６を形成している。又、ラッシュアジャスタの先端部を突き当てる為、上記第二の連結部４ａの片面（図１の右側面、図２の表側面）に、第二の係合部である、半球面状の第二の凹部４０を形成している。尚、本例の場合には、第二の係合部に揺動支持部材としてラッシュアジャスタの先端部を係合する例を示しているが、第二の連結部４ａにねじ孔を形成し、このねじ孔部分にアジャストねじを螺着する構造に関しても、本発明を適用できる。又、図４に示す様に、上記各側壁部２ａに形成した、上記支持軸の両端を支持する為の円孔５の軸方向外側（図４の下側）の開口端周縁部に、母線が直線である、摺鉢状の面取り３７を形成している。
【００３３】
更に、本例のロッカーアームの製造方法により造られるロッカーアーム１ａの場合には、上記第一、第二の連結部３ａ、４ａを形成する為の打ち抜き加工により、上記各側壁部２ａ、２ａの幅方向一端寄り部分（図１、４の右端寄り部分）の内面に、図１に梨地で示す様に、剪断面が生じる。上記ロッカーアーム１ａでは、この剪断面全体を、前記ローラ３５の両端面と、この両端面と外周面との連続部に形成した面取り５２（図２）との何れにも対向させない。但し、この面取り５２部分は、上記各側壁部２ａ、２ａの内面と擦れ合う事はないので、この面取り５２と上記剪断面とが対向する事は、差し支えない。尚、図１ではローラ３５を、２本の二点鎖線の同心円で示しているが、これら同心円のうちの外側の円はローラ３５の外周面（面取り５２の外周縁）を、内側の円はローラ３５の端面（面取り５２の内周縁）を、それぞれ表している（後述する図１３、１８で同じ）。又、本例の場合には、上記剪断面のうちの上記ローラ３５側（図１の左側）の端縁で、最も幅方向片側（図１の右側）に寄った部分（点Ｐ）が、第一、第二の各連結部３ａ、４ａの片面（図１の右側面）のうちの第一、第二の各凹部３６、４０から外れた部分よりも幅方向片側（図１の右側）に位置する様にしている。又、本例の場合には、ロッカーアーム１ａの内部の繊維状の組織の流れであるファイバーフローが全体的にロッカーアーム１ａの長さ方向に流れている。又、このファイバーフローが、少なくともこの長さ方向の両端縁と、上記第一、第二の各連結部３ａ、４ａの間に形成された透孔４５の内周面を除いた部分で切断されていない。尚、上記各側壁部２ａ、２ａは、略三角形に形成している。これら各側壁部２ａ、２ａをこの様な形状に形成する理由は、これら各側壁部２ａ、２ａの中間部に所定の大きさの円孔５を形成する事と、ロッカーアーム１ａの軽量化を図る事との両立を図る為である。又、上記各側壁部２ａ、２ａの一部で、第一、第二の各連結部３ａ、４ａと幅方向（図１の左右方向、図２の表裏方向）にほぼ同じ位置に円孔５、５を形成する等の場合には、上記各側壁部２ａ、２ａを、軽量化を図る事を考慮して、略菱形に形成する場合もある。この場合にも、本発明の製造方法を採用する事により、適切に工程及び中間素材の形状を設定すれば、所望の形状を有するロッカーアームを製造する事が可能となる。
【００３４】
上述の様に構成するロッカーアーム１ａは、図５に示す様にして製造する。次に、このロッカーアーム１ａの製造方法を詳しく説明する。先ず、回転支持装置８にコイル状に巻回した金属線材の端部を、冷間鍛造成形機１０に設けたローラ式線材供給機構１１（図２３参照）等により、この冷間鍛造成形機１０の内側に導入する。又、本例の場合には、上記金属線材の断面を円形としている。又、この金属線材は、予めリン酸亜鉛等の潤滑化成液槽に漬け込む事により、その外周面にリン酸亜鉛皮膜等の潤滑皮膜層を形成しておく。又、この金属線材は、押し出し成形により造っている。この為、この金属線材の内部の組織の繊維状の流れ（ファイバーフロー）の方向は、この金属線材の長さ方向にほぼ一致している。そして、第一工程として、上記冷間鍛造成形機１０に設けた切断機構１２（図２４参照）で、上記金属線材を所定長さに切断する事により、図６に示す様な円柱状の素材（ブランク）３２を造る。尚、本例でロッカーアームを製造する為に使用する冷間鍛造成形機１０は、公知の多段式冷間鍛造機を用いれば良い。例えば、前述の図２３〜２８に示した、従来から知られているロッカーアームの製造方法で使用するものとほぼ同様のものを使用する事もできる。この為、以下の説明では、上記冷間鍛造成形機１０の具体的構造は省略若しくは簡略にする。又、本例で使用する冷間鍛造成形機１０は、前述の図２３〜２８に示したものとは異なり、ロッカーアーム１ａの製造工程で、少なくとも外周側のバリ（外バリ）は発生させない。
【００３５】
上記第一工程で得られた円柱状の素材３２は、上記冷間鍛造成形機１０に設けた第一の鍛造ステーションに、向きを変える事なく移動する。そして、第二工程として、上記素材３２を、可動型により固定型に、水平方向に打ち込んで、この素材３２を軸方向（長さ方向）に圧縮しつつ径方向に膨らませる第一の冷間鍛造（予備成形）を施し、図７に示す様な形状を有する第一中間素材３３を造る。即ち、この第一の冷間鍛造では、上記素材３２の軸方向両側から、可動型及び固定型により、この素材３２を加圧する。この様にして得られた第一中間素材３３は、直径が軸方向中間部で最大となった樽状の形状を有する。即ち、この第一中間素材３３は、中間部に設けた、直径が最大となった最大直径部３８から軸方向両端に向かう程、直径が小さくなっている。又、この第一中間素材３３の軸方向両端面を、ほぼ平坦面としている。尚、上記最大直径部３８の軸方向位置は、前記１対の側壁部２ａ、２ａの位置に合わせて規制し、軸方向中間部であるが、必ずしも軸方向中央部ではない。又、樽状の第一中間素材３３の軸方向に対し直交する方向の各断面積は、後述する第二中間素材３４ｂの長さ方向に対し直交する方向の各断面積にほぼ対応している。この第一中間素材３３の形状は、鍛造時の材料の流動等を考慮して、慎重に設定しなければならない。
【００３６】
上記第一中間素材３３を形成したならば、続いて、上記冷間鍛造成形機１０に設けた素材旋回供給装置２３（図２４参照）により、図８に示す様に、上記第一中間素材３３の向きを９０度変えつつ、この第一中間素材３３を、上記第一の鍛造ステーションから第二の鍛造ステーションに供給する。
【００３７】
次いで、第三工程として、この第二の鍛造ステーションの可動型により固定型に、上記第一中間素材３３を水平方向に打ち込む事により、この第一中間素材３３の長さ方向に対し直交する方向である径方向両側から、この第一中間素材３３を加圧する第二の冷間鍛造（第二の予備成形）を施す。そして、図９〜１０に示す様な、ロッカーアーム１ａ（図１〜４）の大まかな形状及び寸法を有する第二中間素材３４ａを造る。この第二中間素材３４ａは、１対の側壁部２ａ、２ａと、これら両側壁部２ａ、２ａの幅方向一端縁｛図９（ａ）、図１０の右端縁｝同士を連結する基部３９とを備える。又、この基部３９の長さ方向中間部を、上記各側壁部２ａ、２ａと反対側｛図９（ａ）、図１０の右側｝に少しだけ突出させている。又、本例の場合には、上記第一中間素材３３の最大直径部３８に対応する位置で、上記第二中間素材３４ａを構成する各側壁部２ａ、２ａの幅方向｛図９（ａ）、図１０の左右方向｝の寸法が最大となる様にしている。この様な第二の冷間鍛造を施す第一中間素材３３の外周面には予め潤滑皮膜層を形成している為、上記固定型及び可動型の内面と、この第一中間素材３３の外面との間に作用する摩擦を小さく抑えられる。そして、この構成により、第二中間素材３４ａの成形作業性及び形状精度を良好にできる。この様な第三工程により得られた第二中間素材３４ａは、上記固定型と可動型との間から取り出して、第三の鍛造ステーションに供給する。
【００３８】
次いで、第四工程として、この第三の鍛造ステーションの可動型４４｛図１１（ａ）、図１５｝により固定型４３（図１５）に、上記第二の冷間鍛造と同様にして、上記第二中間素材３４ａを水平方向に打ち込む。そして、この第二中間素材３４ａを、上記第二の冷間鍛造の場合と同方向から加圧して、この第二中間素材３４ａに第三の冷間鍛造（本成形）を施し、図１１〜１５に示す様な、ロッカーアーム１ａの完成品に少し近づいた形状及び寸法を有する、第二中間素材３４ｂを造る。この第二中間素材３４ｂは、前記基部３９の長さ方向中間部を、各側壁部２ａ、２ａと反対側に大きく突出させている。又、上記基部３９の片面｛図１１（ａ）の右側面、図１１（ｂ）の表側面｝の長さ方向両端部を、前記第一、第二の各凹部３６、４０の大まかな形状及び寸法に形成している。又、上記第三の冷間鍛造では、上記各側壁部２ａ、２ａの形状及び寸法が完成品とほぼ同じになる様に調整する。
【００３９】
更に、本例の場合には、上記基部３９の長さ方向一端部（図１１の下端部）の両側面で、長さ方向に関して弁体の先端部を突き当てる為の第一の凹部３６と同位置で、この第一の凹部３６から幅方向｛図１１（ａ）の表裏方向、図１１（ｂ）の左右方向、図１５の上下方向｝に外れた両端部を、上記第三の冷間鍛造を施す際の材料の逃げ部４１、４１としている。そして、これら各逃げ部４１、４１に、前記固定型４３及び可動型４４が当たらない様にしている。
【００４０】
又、上記基部３９の長さ方向他端部（図１１の上端部）の他面｛図１１（ａ）の左側面、図１１（ｂ）の裏側面｝で、長さ方向に関してラッシュアジャスタの先端部を突き当てる為の第二の凹部４０と同位置で、この第二の凹部４０と反対側位置を、上記第三の冷間鍛造を施す際の材料の第二の逃げ部４２としている。そして、この第二の逃げ部４２にも、上記固定型４３及び可動型４４が当たらない様にしている。
【００４１】
更に、本例の場合には、この第二中間素材３４ｂの内側で、得るべきロッカーアーム１ａ（図１〜４）でのローラ３５の配置位置に対応する位置に、これら第二中間素材３４ｂとロッカーアーム１ａとを図示しない支持軸を介して組み合わせたと仮定した場合にも、上記ローラ３５と上記基部３９とが干渉しない様に、上記第二中間素材３４ｂの形状及び寸法を規制している。具体的には、図１４に詳示する様に、上記第二中間素材３４ｂの長さ方向中間部の内面を、前記各側壁部２ａの内面である平滑な平面部５３の奥端縁と、上記基部３９の中間部の内面を構成する円筒面部５４とが、曲面部５５により連続した形状とする。そして、上記第二中間素材３４ｂの内側に上記ローラ３５を、上述の様に組み付けたと仮定した場合に、このローラ３５が、上記平面部５３と円筒面部５４と曲面部５５との何れにも干渉しない様に、上記第二中間素材３４ｂの内面の形状及び寸法を規制する。又、上記ローラ３５の前記面取り５２を除く両端面が、上記各側壁部２ａの内面を構成する平面部５３の奥端縁（図１４の点Ｑ）よりも外側（図１４の左側）に位置する様にする。この様な第四工程により得られた第二中間素材３４ｂは、上記第三の鍛造ステーションの固定型４３と可動型４４との間から取り出して、第一の打ち抜きステーションに供給する。
【００４２】
次いで、この第一の打ち抜きステーションで行なう孔あけ工程である、第五工程として、固定型と可動型との間で、上記第二中間素材３４ｂのうち、基部３９の長さ方向中間部以外の部分を挟持しつつ、この固定型又は可動型の内側に設けた孔あけ用パンチにより、この中間部に打ち抜き加工を施す。好ましくはこの孔あけ用パンチを、前記両側壁部２ａ、２ａの間側から挿入し、打ち抜き廃材（目抜き材）を、これら両側壁部２ａ、２ａと反対側に排出する。この理由は、打ち抜き加工に伴って生じるバリが、上記ローラ３５を配置する側に向かない様にする為である。そしてこの打ち抜き加工により、図１６〜１９に示す様な、厚さ方向に貫通する透孔４５をその中間部に形成した、第三中間素材４６を造る。又、この透孔４５の加工により、各側壁部２ａ、２ａの長さ方向両端部同士を連結する第一、第二の両連結部３ａ、４ａが形成される。更に、上記第五工程では、上記打ち抜き加工と同時に、上記各側壁部２ａ、２ａの幅方向一端部｛図１６（ａ）、図１７の右端部、図１６（ｂ）の表側端部｝の形状及び寸法を調整する為の鍛造加工を施す。尚、図１７では、上記第三中間素材４６と共に、上記打ち抜き加工により上記基部３９を打ち抜く事により生じた小片（目抜き材）５０を合わせて示している。
【００４３】
又、上記透孔４５を形成する事により、上記各側壁部２ａ、２ａの幅方向一端寄り部分｛図１６（ａ）、図１４、１７〜１９の右端寄り部分｝を含む、上記透孔４５の内周面で上記小片５０の外周縁と連続していた部分（図１６、１８に梨地で示す部分、図１９に矢印ａでその範囲を示す部分）に、剪断面及び破断面が形成される。この様な第五工程により得られた第三中間素材４６は、上記第一の打ち抜きステーションの可動型と固定型との間から取り出して、第四の鍛造ステーションに供給する。
【００４４】
この第四の鍛造ステーションでは、第六工程として、図２０〜２１に示す様に、可動型４８により固定型４７に、上記第三中間素材４６を前記第二、第三の冷間鍛造と同様に水平方向に打ち込む事により、この第三中間素材４６に第四の冷間鍛造（サイジング）を施し、第一、第二の各凹部３６、４０を所定の形状及び寸法に精度良く調整した、図２０〜２１に示す様な、第四中間素材４９を造る。この様な第四の冷間鍛造の場合も、前記第二、第三の冷間鍛造の場合と同方向から上記第三中間素材４６を加圧する。
【００４５】
又、上記第四の冷間鍛造の場合も、上記第三の冷間鍛造の場合と同様に、第一連結部３ａの両側面で、上記第一の凹部３６から幅方向｛図２０（ａ）の表裏方向、図２０（ｂ）の左右方向、図２１の上下方向｝に外れた両端部を、上記第四の冷間鍛造を施す際の材料の逃げ部４１、４１として、これら各逃げ部４１、４１に固定型４７及び可動型４８が突き当たらない様にしている。更に、第二の連結部４ａの他面｛図２０（ａ）の左側面、図２０（ｂ）の裏側面｝で、第二の凹部４０と反対側位置を、上記第四の冷間鍛造を施す際の材料の第二の逃げ部４２としている。
【００４６】
尚、上記第四の鍛造ステーションでは、可動型４８により固定型４７に、上記第三中間素材４６を水平方向に打ち込む工程を、必要に応じて繰り返す事により、上記第一、第二の各凹部３６、４０の形状及び寸法を調整するのと同時に、上記各側壁部２ａ、２ａの平行度の調整や、これら各側壁部２ａ、２ａの内側面同士の間隔及び外側面同士の間隔の調整を行なう事もできる。又、これら各側壁部２ａ、２ａの幅方向一端部にかえりが生じた場合に、若干の面押しを行なう事で、このかえりを低減、若しくは解消する事もできる。この様な第六工程が終了したならば、上記第四の鍛造ステーションの固定型４７と可動型４８との間から上記第四中間素材４９を取り出して、この第四中間素材４９を第二の打ち抜きステーションに供給する。
【００４７】
この第二の打ち抜きステーションでは、第七工程として、上記第四中間素材４９の各側壁部２ａ、２ａの一部に第二の打ち抜き加工を施して、前述の図１〜４に示したロッカーアーム１ａの完成品を造る。本例の場合には、この第二の打ち抜き加工を、前記冷間鍛造成形機１０の内部で行なう。この為の方法の一つとして、第四の鍛造ステーションから第二の打ち抜きステーションに上記第四中間素材４９を供給する際に、この第二の打ち抜きステーションの固定型及び可動型の先端面と上記各側壁部２ａ、２ａの外側面とが対向する様に、上記第四中間素材４９の向きを９０度変える方法が考えられる。そして、上記第二の打ち抜きステーションの固定型と可動型との間で、上記第四中間素材４９を挟持すると共に、この固定型又は可動型の内側に設けた孔あけ用パンチにより前記各円孔５、５を形成する方法が考えられる。又、別の方法として、第四の鍛造ステーションから第二の打ち抜きステーションに上記第四中間素材４９を、向きを変更する事なくそのまま供給し、第一〜第四の鍛造ステーションの各可動型４４、４８を往復移動させる為の駆動機構（スライド機構）の動きを、両側に設けたカム型によりこの往復移動方向と９０度異なる方向に変換し、このカム型に取り付けた孔あけ用パンチにより上記各円孔５、５を形成する方法もある。又、本例の場合には、これら各円孔５、５の軸方向外側の開口端周縁部に面取り３７（図４）を、これら各円孔５、５の孔あけ加工と同時に、鍛造加工により形成する。この様にして得られたロッカーアーム１ａの完成品は、上記第二の打ち抜きステーションから、取り出し用チャックにより所定位置に取り出す。
【００４８】
上述の様に構成する本例のロッカーアームの製造方法の場合には、金属線材製の素材３２に冷間鍛造を施す事によりロッカーアーム１ａを造る場合で、このロッカーアーム１ａを組み込んだエンジンの性能向上を図れる。
即ち、本例の場合には、第二工程として、上記素材３２を軸方向（長さ方向）両側から加圧する事によりこの素材３２に第一の冷間鍛造を施し、第三、第四工程として、この素材３２から得られた第一、第二中間素材３３、３４ａを長さ方向に対し直交する方向（基部３９又は各連結部３ａ、４ａの厚さ方向）の両側から加圧する事により、この第一、第二中間素材３３、３４ａに第二、第三の冷間鍛造を施している。この様に、第一の冷間鍛造と、第二、第三の各冷間鍛造とで、素材３２と第一、第二各中間素材３３、３４ａとを互いに９０度異なる方向の両側から加圧するので、総ての冷間鍛造で素材及び中間素材を同方向の両側から加圧する場合に比べ、得られるロッカーアーム１ａの一部に、過大な応力が集中する事を抑える事ができる。
【００４９】
又、本例の様に、金属線材を押し出し成形により造った場合には、上記素材３２のファイバーフローが、この素材３２の長さ方向にほぼ一致する。そして、この素材３２から得られた第一中間素材３３のファイバーフローの多くを、この第一中間素材３３の長さ方向に対しほぼ平行にし、又は平行に近づける事ができる。本例の場合には、上記第三工程等で、この様な第一中間素材３３等を長さ方向に対し直交する方向の両側から加圧する事によりこの第一中間素材３３等に冷間鍛造を施している為、この第一中間素材３３等を長さ方向両側から加圧する事によりこの第一中間素材３３等に冷間鍛造を施す場合に比べて、得られるロッカーアーム１ａのファイバーフローをこのロッカーアーム１ａの全体形状に対応した滑らかな流れとする事ができる。これらの結果、得られたロッカーアーム１ａの強度を十分に確保でき、このロッカーアーム１ａを組み込んだエンジンの耐久性の向上を図れる。又、本例の場合には、上記第三、四、六工程で、第一〜第三中間素材３３、３４ａ、４６を長さ方向に対し直交する方向の両側から加圧する事によりこれら各中間素材３３、３４ａ、４６に冷間鍛造を施す際に、外周側でのバリ（外バリ）を全く発生させない様に工程を設定している。この為、前述の特許文献１に記載されたロッカーアームの製造方法の場合と異なり、外バリ部分にファイバーフローが創製される事がない。従って、ファイバーフローを、この外バリ部分で乱される事もなく、この外バリの除去の伴って分断される事もない。この為、ロッカーアーム１ａの完成品（製品）の強度向上を図れる。又、外バリの除去に伴う剪断面や破断面に起因する欠陥が生じる事もなく、ロッカーアーム１ａの形状精度を良好にできる。勿論、材料損失を抑えて、材料費の低減を図り易くなる。
【００５０】
又、上記ファイバーフローの多くに対しほぼ直交する方向又はこの方向に近い方向の両側から、上記第一中間素材３３等を加圧する事によりこの第一中間素材３３等に冷間鍛造を施す際に、外バリを全く発生させない様に工程を設定している為、可動型及び固定型と第一中間素材３３等との接触面積が小さくなり、この第一中間素材３３等に加わる力を小さくできる。この為、ロッカーアーム１ａの成形性を良好にできると共に、冷間鍛造に使用する固定型及び可動型に過大な荷重が加わる事を防止でき、これら固定型及び可動型の寿命向上を図れる。従って、ロッカーアーム１ａの量産時での単品のコストを低減できる。更に、各部の変形量を小さくして、加工硬化を抑え易くなる。
【００５１】
更に、図７に示した第一中間素材３３を得る為の第二工程で、上記素材３２を軸方向（長さ方向）両側から加圧する事により、この素材３２に第一の冷間鍛造を施している。この為、金属線材の直径を大きくする事なく、得られる第一中間素材３３を、本例の様な、軸方向中間部で直径が最大になった樽状に形成し易くできる。この為、この樽状の第一中間素材３３により、本例の様な、長さ方向中間部で幅方向寸法が最大になった略三角形の１対の側壁部２ａ、２ａを有する、第二中間素材３４ａを造り易くできる。しかも、発生する外バリをなくす事ができる。又、内バリは、発生する場合でも、製品の使用に対する影響を及ぼさない位置で少なく抑える事ができる。従って、軽量なロッカーアーム１ａを安価に造れる。又、本例の場合には、ロッカーアーム１ａのファイバーフローが全体的にこのロッカーアーム１ａの長さ方向に流れている。又、このファイバーフローが、少なくともこの長さ方向の両端縁と、上記第一、第二の各連結部３ａ、４ａの間に形成された透孔４５の内周面とを除いた部分で切断されていない。この為、成形作業性を良好にできると共に、強度及び形状精度の向上を図れる。
【００５２】
更に、本例の場合には、各側壁部２ａ、２ａに形成した通孔５、５の外側開口端周縁部に形成した面取り３７（図４）に、ローラ３５を支持した支持軸の両端部をかしめ付ける事ができる。具体的には、この支持軸の両端部を径方向外方に塑性変形させて成る鍔状部分と上記面取り３７とを係合させる事ができる。この為、上記各通孔５、５にこの支持軸の両端部を、十分な結合強度で結合固定する事ができる。この結果、ロッカーアーム１ａにローラ３５を組み付けて成るカムフォロアで、各側壁部２ａ、２ａに支持軸の両端部を、十分な結合強度で結合固定でき、上記ロッカーアーム１を組み込んだエンジンの耐久性の向上を図れる。更に、上記支持軸の端部を何れか１個の通孔５の内側に、上記面取り３７により案内しつつ挿入できる為、この通孔５内へのこの支持軸の挿入作業を容易に行なえる。この為、この支持軸及びローラ３５とロッカーアーム１ａとを組み合わせたカムフォロアのコスト低減を図れる。
【００５３】
更に、本例の場合には、図１１に示す様な第二の中間素材３４ｂを得る為の前記第四工程で、前記第一、第二の各凹部３６、４０を冷間鍛造により形成する際に、この第二中間素材３４ｂの基部３９の長さ方向に関して上記第一、第二の各凹部３６、４０と同位置と、これら第一、第二の各凹部３６、４０の近くに、材料の逃げ部４１又は第二の逃げ部４２を設けている。又、図１６に示した第三中間素材４６から図２０に示した第四中間素材４９を得る為の前記第六工程で、前記第一、第二の各凹部３６、４０を冷間鍛造により形成する際に、上記第三中間素材４６のうちの、１対の側壁部２ａ、２ａよりも幅方向内側に外れた部分で、長さ方向に関して上記第一、第二の各凹部３６、４０を形成すべき部分と同位置と、これら第一、第二の各凹部３６、４０の近くに、材料の逃げ部４１又は第二の逃げ部４２を設けている。従って、上記第一、第二の各凹部３６、４０を形成する場合に、第二中間素材３４ｂ及び第三中間素材４６の余肉部の逃げを円滑に行なわせ、これら第一、第二の各凹部３６、４０を所定の形状及び寸法に精度良く加工し易くできる。この為、これら第一、第二の各凹部３６、４０の形状精度及び寸法精度を良好にでき、得られたロッカーアーム１ａの使用時に、このロッカーアーム１ａの所定位置に弁体の基端部及びラッシュアジャスタの先端部を精度良く係合させて、このロッカーアーム１ａを組み込んだエンジンの性能向上を図れる。しかも、上記第二の逃げ部４２は、上記基部３９又は第二の連結部４ａのうち、上記第二の凹部４０と反対側位置としている為、この第二の凹部４０を所定の形状及び寸法に、より精度良く加工し易くできる。更に、鍛造に使用する固定型４３、４７及び可動型４４、４８に過大な荷重が加わる事を防止でき、これら各型４３、４７、４４、４８の寿命向上を図れる。この為、ロッカーアーム１ａの量産時での単品のコストを、より低減できる。
【００５４】
又、本例の場合には、第一、第二の連結部３ａ、４ａを形成する為の打ち抜き加工により各側壁部２ａ、２ａの内面に形成された剪断面全体がローラ３５の両端面に対向しない、ロッカーアーム１ａを造れる。そして、この様にして得られたロッカーアーム１ａによれば、上記ローラ３５の両端面と、粗い剪断面とが接触する（擦れ合う）事を防止できる。この為、上記ローラ３５を上記ロッカーアーム１ａに組み付けた状態で、このローラ３５を円滑に回転させる事ができる。又、このローラ３５の両端面に異常摩耗が発生する事を防止できると共に、当該接触部での摩耗に基づく摩耗粉の発生を抑える事ができる。従って、上記ロッカーアーム１ａを組み込んだエンジンの出力向上、耐久性向上等、性能の向上を図れる。この様な性能向上の為に、上記打ち抜き加工後の工程で、上記剪断面を面押し等により平滑化する面倒な作業を行なう必要がなくなる。
【００５５】
又、本例の場合には、第五、第六工程として、基部３９の打ち抜き加工と、第一、第二の各凹部３６、４０を所定の形状及び寸法に精度良く調整する為の鍛造加工とを、別工程で行なっている。この為、これら各凹部３６、４０の形状及び寸法の精度の向上を図り易くなる。
【００５６】
尚、本例の場合には、各側壁部２ａ、２ａに設ける各円孔５、５を打ち抜き加工により形成しているが、本発明では、これら各円孔５、５を、この打ち抜き加工の代わりに、シェービング加工や、切削加工により形成する事もできる。但し、このうちの切削加工を採用する場合には、ロッカーアーム１ａのコストが上昇する原因となる。この為、このロッカーアーム１ａのコストの低減を図る面からは、上記各円孔５、５を、打ち抜き加工又はシェービング加工により形成する事が好ましく、より好ましくは、このうちの打ち抜き加工により上記各円孔５、５を形成する。又、冷間鍛造成形機１０から取り出した中間素材を別のプレス加工機に搬送して、この別のプレス加工機で上記各円孔５、５の打ち抜き加工を行なう事もできる。
【００５７】
又、本例の場合には、金属線材に予めリン酸亜鉛皮膜等の潤滑皮膜層を形成している。但し、冷間鍛造成形機１０の金型の内面に潤滑剤を塗布したり、冷間鍛造成形機１０の内部に潤滑油を供給する等により、素材３２及び第一〜第四中間素材３３、３４ａ、３４ｂ、４６、４９の外面と金型の内面との間での摩擦を抑える事もできる。
【００５８】
【発明の効果】
本発明は、以上に述べた通り構成され作用するので、ロッカーアームを組み込んだエンジンの性能向上を図れる。
【図面の簡単な説明】
【図１】本発明の実施の形態の１例のロッカーアームの完成品を、一部を省略して示す断面図。
【図２】図１の右方から見た図。
【図３】図１のＡ−Ａ断面図。
【図４】同Ｂ−Ｂ断面図。
【図５】第１例のロッカーアームの製造方法を示すフローチャート。
【図６】第１例の製造方法の第一工程により得られる素材を示しており、（ａ）は正面図、（ｂ）は（ａ）の側方から見た図。
【図７】第二工程により得られる第一中間素材を示しており、（ａ）は正面図、（ｂ）は（ａ）のＣ−Ｃ断面図。
【図８】第一の鍛造ステーションから第二の鍛造ステーションへ第一中間素材を移動する際にこの第一中間素材の向きを９０度変える状態を示す図。
【図９】第三工程により得られる第二中間素材を示しており、（ａ）は断面図、（ｂ）は（ａ）の右方から見た図。
【図１０】図９（ａ）のＤ−Ｄ断面図。
【図１１】第四工程により得られる第二中間素材を示しており、（ａ）は断面図、（ｂ）は（ａ）の右方から見た図。
【図１２】図１１（ａ）のＥ−Ｅ断面図。
【図１３】同部分拡大図。
【図１４】図１２のＦ部拡大断面図。
【図１５】第四工程の鍛造作業の途中の状態を、図１１（ａ）のＧ−Ｇ断面部分で示す図。
【図１６】第五工程により得られる第三中間素材を示しており、（ａ）は断面図、（ｂ）は（ａ）の右方から見た図。
【図１７】同第三中間素材と、第五工程の打ち抜き加工時に生じた小片とを、図１６（ａ）のＨ−Ｈ断面部分で示す図。
【図１８】図１６（ａ）の部分拡大断面図。
【図１９】図１７のＩ部拡大断面図。
【図２０】第六工程により得られる第四中間素材を示しており、（ａ）は断面図、（ｂ）は（ａ）の右方から見た図。
【図２１】第六工程の鍛造作業の途中の状態を、図２０（ａ）のＪ−Ｊ断面部分で示す図。
【図２２】従来から知られたロッカーアームの製造方法により得られたロッカーアームを示しており、（ａ）は正面図、（ｂ）は（ａ）の左方から見た図。
【図２３】従来から知られたロッカーアームの製造方法によりロッカーアームを製造する状態を示す略斜視図。
【図２４】同製造方法に使用する冷間鍛造成形機の部分断面図。
【図２５】冷間鍛造成形機の第一の鍛造ステーションを示す、図２４の部分拡大断面図。
【図２６】同第一の打ち抜きステーションを示す、図２４の部分拡大断面図。
【図２７】同第二の鍛造ステーションを示す、図２４の部分拡大断面図。
【図２８】同第二の打ち抜きステーションを示す、図２４の部分拡大断面図。
【符号の説明】
１、１ａロッカーアーム
２、２ａ側壁部
３、３ａ第一の連結部
４、４ａ第二の連結部
５円孔
６第一の係合部
７第二の係合部
８回転支持装置
９金属線材
１０冷間鍛造成形機
１１ローラ式線材供給機構
１２切断機構
１３素材
１４ダイブロック
１５ラム
１６ａ〜１６ｄ固定型
１７ａ〜１７ｄ可動型
１８ａ〜１８ｄ型ホルダ
１９第一の鍛造ステーション
２０第一の打ち抜きステーション
２１第二の鍛造ステーション
２２第二の打ち抜きステーション
２３素材旋回供給機構
２４第一中間素材
２５、２５ａ、２５ｂバリ
２６通孔
２７押し出し部材
２８孔あけ用パンチ
２９透孔
３０第二中間素材
３１第三中間素材
３２素材
３３第一中間素材
３４ａ、３４ｂ第二中間素材
３５ローラ
３６第一の凹部
３７面取り
３８最大直径部
３９基部
４０第二の凹部
４１逃げ部
４２第二の逃げ部
４３固定型
４４可動型
４５透孔
４６第三中間素材
４７固定型
４８可動型
４９第四中間素材
５０小片
５１基部
５２面取り
５３平面部
５４円筒面部
５５曲面部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rocker arm and a method for manufacturing the same used in a state where the camshaft is incorporated in a valve operating mechanism of an engine in order to convert the rotation of a camshaft into a reciprocating motion of a valve body (intake valve and exhaust valve).
[0002]
[Prior art]
The reciprocating engine (reciprocating piston engine) is provided with an intake valve and an exhaust valve that open and close in synchronization with the rotation of the crankshaft except for some two-cycle engines. In such a reciprocating engine, the movement of the camshaft that rotates in synchronization with the rotation of the crankshaft (in the case of a four-cycle engine, at half the rotational speed) is caused to move the intake valve and the exhaust valve by the rocker arm. The intake valve and the exhaust valve may be reciprocated in the respective axial directions.
[0003]
Conventionally, a cast product (a cast iron product or an aluminum die cast product) has been used as a rocker arm incorporated in such a valve mechanism of an engine. In recent years, it has been considered that the rocker arm is made by pressing a metal plate such as a steel plate, and some of them are implemented. However, in the case of such a rocker arm made of a cast product or a rocker arm made of a metal plate, there is a problem that the cost is increased due to a longer time required for the manufacturing work and an increase in waste of materials. is there.
[0004]
On the other hand, as described in Patent Document 1, there has been proposed a method of manufacturing a rocker arm by cold forging a material (blank) obtained by cutting a metal wire into a predetermined length. Yes. According to Patent Document 1, if a rocker arm is made by cold forging a material made of a metal wire, it can be manufactured with high accuracy without cracks and workability can be improved. Further, if the rocker arm is manufactured by such cold forging, the shape accuracy and dimensional accuracy can be increased as compared with the case where it is manufactured by hot forging. 22 to 28 show an invention related to a rocker arm and a manufacturing method thereof described in Patent Document 1. The method for manufacturing the rocker arm is described in detail in the above-mentioned Patent Document 1, and will be briefly described here. As shown in FIG. 22, the rocker arm 1 includes a pair of side wall portions 2, 2 that are substantially parallel to each other, a first connection portion 3 that connects both end portions in the length direction of both side wall portions 2, 2, and And a second connecting portion 4. Of these first connecting part 3 and second connecting part 4, the first connecting part 3 has a first engaging part 6 for abutting the base end part of the valve body as a second connecting part. Reference numerals 4 each have a second engaging portion 7 for abutting the tip of a swing support member such as a lash adjuster.
[0005]
In addition, although not described in Patent Document 1, in the case of a rocker arm to be actually used, a pair of circular holes are formed concentrically with each other in the middle portion in the longitudinal direction of the both side wall portions 2 and 2. The both end portions of the support shaft for rotatably supporting the roller engaged with the cam can be supported in both the circular holes.
[0006]
The operation of making the rocker arm 1 as described above is performed as follows. First, as shown in FIG. 23, the end portion of the metal wire 9 wound in a coil shape on the rotation support device 8 is pulled out by a roller-type wire supply mechanism 11 provided in the cold forging machine 10, and this cold It is introduced into the forging machine 10. The metal wire 9 has a rectangular cross section. Further, the metal wire 9 is immersed in a lubricating liquid tank such as zinc phosphate in advance, and a lubricant film layer is formed on the outer peripheral surface of the metal wire 9. Then, as a first step, as shown in FIG. 24, the metal wire 9 is cut into a predetermined length by the cutting mechanism 12 provided in the cold forging machine 10 to obtain a rectangular parallelepiped material (blank). Build 13 The cold forging machine 10 is called a horizontal multi-stage forging machine, and the die block 14 fixed on the inner side and the horizontal so that the die block 14 approaches or separates (perspectively moves). And a ram 15 that reciprocates in the direction. Among these, the die block 14 has a plurality of fixed dies 16a to 16d arranged at intervals in the horizontal direction. In addition, a plurality of movable dies 17a to 17d are arranged in part of the ram 15 at positions facing these fixed dies 16a to 16d via die holders 18a to 18d, respectively. The first forging station 19, the first punching station 20, the second forging station 21, and the second punching station 22 are arranged on the portions where the fixed dies 16 a to 16 d and the movable dies 17 a to 17 d are arranged. Are provided. The rectangular parallelepiped material 13 obtained by the first step is rotated by a material turning supply mechanism 23 provided in the cold forging machine 10 while changing the direction of the material 13 by 90 degrees, while the first forging station 19 To supply.
[0007]
In this first forging station 19, as shown in detail in FIG. 25, the material 13 is cold forged into the material 13 by driving the material 13 horizontally into the stationary die 16a by the movable die 17a as shown in FIG. The first intermediate material 24 having the rough shape and size of the rocker arm 1 is produced. The first intermediate material 24 has an H-shaped cross section including a pair of side wall portions 2 (FIG. 22) and a base portion 51 that connects the width direction intermediate portions of both side wall portions 2. Further, burrs 25 are formed on the outer peripheral surface of the intermediate portion in the thickness direction of the first intermediate material 24 over the entire periphery. Since a lubricating film layer is formed in advance on the outer peripheral surface of the material 13 for performing such cold forging, it acts between the inner surfaces of the fixed mold 16 a and the movable mold 17 a and the outer surface of the material 13. Friction can be kept small. With this configuration, the molding workability and shape accuracy of the first intermediate material 24 can be improved. The first intermediate material 24 obtained by the second step is taken out from between the fixed die 16a and the movable die 17a and supplied to the first punching station 20 as shown in detail in FIG. .
[0008]
In the first punching station 20, as a third step, between the tip surface of the cylindrical push-out member 27 provided in the through hole 26 of the fixed die 16b and the tip surface of the cylindrical movable die 17b, Of the first intermediate material 24, the main body portion excluding the burr 25 is sandwiched. Then, the burr 25 is removed at the peripheral edge of the opening end of the through hole 26 by pushing the main body portion into the through hole 26. At the same time, a second intermediate portion having a through hole 29 is punched out by punching the intermediate portion of the base portion 51 (FIG. 25) provided in the first intermediate material 24 by the punching punch 28 provided inside the pushing member 27. The material 30 is made. By forming the through hole 29, the first intermediate member 30 is connected to the second intermediate material 30 by connecting both end portions in the length direction of the pair of side wall portions 2 (FIG. 22). 4 is formed. The second intermediate material 30 obtained by the third step is taken out from between the fixed die 16b and the movable die 17b and supplied to the second forging station 21 as shown in detail in FIG. .
[0009]
In the second forging station 21, as a fourth step, the second intermediate material 30 is cold forged by driving the second intermediate material 30 horizontally into the fixed die 16c by the movable die 17c. Then, the third intermediate material 31 having a size and shape close to that of the finished product is produced. At this time, burrs 25a and 25b are formed on the outer peripheral surface of the third intermediate material 31 in the thickness direction and on the inner peripheral surface of the through hole 29, respectively. Since the lubricating film layer is formed in advance on the outer surface of the second intermediate material 30 to be subjected to such cold forging, the inner surfaces of the fixed mold 16c and the movable mold 17c, and the outer surface of the second intermediate material 30 The friction acting between the two can be kept small. With this configuration, the molding workability and shape accuracy of the third intermediate material 31 can be improved. When the fourth step is completed, the third intermediate material 31 is taken out from between the fixed mold 16c and the movable mold 17c, and the third intermediate material 31 is shown in detail in FIG. To the second punching station 22.
[0010]
In the second punching station 22, the burr 25a formed on the outer peripheral surface of the third intermediate material 31 is removed as the fifth step in the same manner as in the third step. At the same time, the burr 25b formed on the inner peripheral surface of the through hole 29 of the third intermediate material 31 is also removed, and a finished product of the rocker arm 1 is obtained. The rocker arm 1 is taken out from a fixed die 16d and a movable die 17d of the second punching station 22 to a predetermined position by a take-out chuck (not shown), for example. In addition, although not described in Patent Document 1, in the case of a rocker arm that is actually used, another processing machine is used to position 1 at a position where they are aligned with each other at an intermediate portion of each side wall portion 2 (FIG. 22). A drilling process may be performed to form a pair of circular holes.
[0011]
In the case of the rocker arm manufacturing method described in Patent Document 1 configured as described above, since the rocker arm 1 is manufactured by a multistage cold forging machine, the time required for the manufacturing operation can be shortened to some extent. , Workability can be improved. Further, since the movable molds 17a to 17d are moved in the horizontal direction, the drive mechanism for reciprocating the movable molds 17a to 17d is compared with the case where the forging work is performed by moving the movable molds in the vertical direction. The added burden can be reduced. For this reason, it is possible to easily increase the speed of the cold forging work for obtaining the rocker arm 1.
[0012]
[Patent Document 1]
JP-A-10-328778
[0013]
[Problems to be solved by the invention]
In the case of the rocker arm manufacturing method described in Patent Document 1 described above, there is room for improvement for improving the performance of the engine incorporating the rocker arm 1 obtained in the following points (1) to (3). There is.
(1) The material 13 (or the second intermediate material 30) is the same direction in the axial direction (length direction) in all of the second and fourth steps, which are forging steps for obtaining the rocker arm 1. The material 13 (or the second intermediate material 30) is subjected to cold forging by applying pressure from both sides in the direction orthogonal to the thickness direction of the base 51 or the connecting portions 3 and 4. For this reason, in the second and fourth steps, excessive stress is easily concentrated on a part of the material 13 and the second intermediate material 30 corresponding to the same part of the obtained rocker arm 1, and the obtained rocker is obtained. It becomes difficult to ensure sufficient strength with the arm 1.
[0014]
The material 13 has a rectangular parallelepiped shape, and has a uniform cross-sectional area in the axial direction (length direction). On the other hand, the second intermediate material 30 has a non-uniform cross-sectional area in the axial direction (changes greatly). Therefore, the second intermediate material 30 cannot be immediately obtained from the material 13 by cold forging, and the first intermediate material 24 with the burrs 25 is made by cold forging, and the burrs 25 are formed in the subsequent punching process. It must be removed to make the second intermediate material 30.
As described above, when cold forging with the burr 25 is performed, a fiber flow, which is a flow of a textured structure inside the second intermediate material 30, is newly created along the flow direction of the burr 25. The Along with this, the fiber flow formed in the original first intermediate material 24 is disturbed and discontinuous at the burr 25 portion. Further, by removing this burr 25 in a later step, the fiber flow in this portion is divided (cut). When the fiber flow is divided in this way, the strength of the finished product (product) of the obtained rocker arm 1 tends to decrease. Further, when the burrs are divided, a shearing surface and a fracture surface are generated along with this, and there is a risk of occurrence of defects, and the shape accuracy is deteriorated. Moreover, since the forging load increases, equipment having a large forging capacity is required. Naturally, because of the burr 25, the amount of material loss increases, causing an increase in cost.
In the case of the rocker arm manufacturing method described in the cited document 1, the same thing is repeated in the fourth and fifth steps, that is, after performing cold forging with burrs 25a and 25b, each of these burrs. Since 25a and 25b are removed, the strength and accuracy of the product are more likely to deteriorate.
Also, of the burrs 25, 25a, 25b formed by cold forging, the burrs (outer burrs) 25, 25a generated on the outer peripheral side are formed on the periphery, so that the volume increases. For this reason, it is remarkable that the amount of material loss is larger than the burr (inner burr) 25b generated on the inner peripheral side. It should be noted that it is desirable not to generate the inner burr 25b. However, if it is unavoidable, the inner burr 25b needs to be provided in a portion having little influence on the use of the finished product of the rocker arm 1.
In the case of the rocker arm manufacturing method described in Patent Document 1, there is room for improving the durability, which is the performance of the engine incorporating the obtained rocker arm 1, in this respect.
[0015]
(2) In the case of the rocker arm 1 that is actually used, each side wall 2 (FIG. 22) is formed with a circular hole for supporting both ends of a support shaft that supports a roller at an intermediate portion. When each of these circular holes is a mere cylindrical surface over the entire length, both ends of the support shaft cannot be coupled and fixed to these circular holes with sufficient coupling strength. For this reason, it is difficult to sufficiently secure the durability of the cam follower configured by assembling a roller on the rocker arm 1. That is, when each circular hole is a simple cylindrical surface as described above, both end portions of the support shaft must be fixed to these circular holes by simple press-fitting, adhesion, shrink fitting, etc. It becomes difficult to ensure sufficient durability of the cam follower. In the case of the method for manufacturing a rocker arm described in Patent Document 1, it is not described that a circular hole is formed in each of the side wall portions 2 and, of course, the bonding strength of both ends of the support shaft to the circular hole. It is not considered to improve. In the case of the rocker arm manufacturing method described in Patent Document 1, there is room for improving the durability, which is the performance of the engine incorporating the obtained rocker arm 1, in this respect.
[0016]
(3) Cold forging to form first and second engaging portions 6 and 7 (FIG. 22) for abutting the valve body or the swing support member at the second forging station 21 or the like. It is not considered that a part of the second intermediate material 30 or the like is provided with a relief portion for the surplus material portion in the vicinity of the first and second engaging portions 6 and 7. For this reason, because of the formation of the first and second engaging portions 6 and 7, the surplus portion of the second intermediate material 30 and the like cannot be effectively escaped. The shape accuracy and dimensional accuracy of each of the engaging portions 6 and 7 cannot be improved. For this reason, it becomes difficult to accurately engage the valve body or the lash adjuster at a predetermined position of the rocker arm 1. In the case of the rocker arm manufacturing method described in Patent Document 1, there is room for improving the performance of the engine incorporating the obtained rocker arm 1 in this respect.
In view of such circumstances, the rocker arm and the manufacturing method thereof according to the present invention improve the performance of an engine incorporating the rocker arm when the rocker arm is manufactured by cold forging a metal wire material. Invented.
[0017]
[Means for Solving the Problems]
Each of the rocker arms of the present invention is produced by cold forging a material obtained by cutting a metal wire into a predetermined length, and a pair of side wall portions provided at intervals from each other, The first and second connecting portions that connect the portions near both ends in the length direction of both side wall portions, and a pair of concentric through holes formed at positions where the both side wall portions are aligned with each other, Each of the first and second connecting portions has an engaging portion that engages with the valve body or the swing support member.
[0018]
In particular, in the rocker arm according to claim 1, a step of cold forging the material to form a first intermediate material by pressurizing the material from both sides in the length direction, and the first intermediate material The first intermediate material is cold-forged by pressurizing from both sides in the direction orthogonal to the length direction to produce a second intermediate material.
[0019]
In the rocker arm according to the fourth aspect of the present invention, when the through holes are formed in the side wall portions, chamfering is simultaneously formed at the outer opening end portions of the through holes.
[0020]
Further, in the rocker arm according to claim 6, the first engagement portion or the second engagement portion is formed by cold forging the material or an intermediate material obtained from the material. When the intermediate material or another intermediate material is made, the intermediate material or a part of the other intermediate material, the portion of the intermediate material or the portion separated from the pair of side wall portions inward in the width direction, the above-mentioned in the length direction. At least a part of the same position as the portion where the first engagement portion or the second engagement portion is to be formed is a relief portion where a die used for the cold forging is not applied.
[0021]
Further, in the rocker arm according to claim 8, the fiber flow which is the flow of the internal fibrous tissue flows in the entire length direction of the rocker arm, and this fiber flow is at least this It is not cut | disconnected in the part except the both ends edge of the length direction, and the internal peripheral surface of the through-hole formed between each said 1st, 2nd connection part.
[0022]
A rocker arm manufacturing method according to claim 2 is the rocker arm manufacturing method according to claim 1 described above, wherein the material is cold forged by pressurizing the material from both sides in the length direction. The first intermediate material is made by cold forging by pressing the first intermediate material from both sides in the direction perpendicular to the length direction. The process of making.
[0023]
The rocker arm manufacturing method according to claim 3 is the rocker arm manufacturing method according to claim 1 described above, wherein the material is cold forged by pressurizing the material from both sides in the length direction. To produce a first intermediate material whose cross-sectional area is changed with respect to the length direction corresponding to the change of the cross-sectional area in the direction perpendicular to the length direction with respect to the length direction of the rocker arm to be obtained. And a step of applying cold forging to the first intermediate material by pressurizing the first intermediate material from both sides in a direction orthogonal to the length direction so as not to generate burrs on the outer peripheral side.
[0024]
A rocker arm manufacturing method according to claim 5 is the rocker arm manufacturing method according to claim 4 described above, and when each through hole is formed in each side wall portion, each of the through holes is formed. A chamfer is simultaneously formed at the outer opening end.
[0025]
The rocker arm manufacturing method according to claim 7 is the rocker arm manufacturing method according to claim 6 described above, wherein cold forging is applied to the material or an intermediate material obtained from the material. When forming an intermediate material or another intermediate material in which the first engaging portion or the second engaging portion is formed by the above, a part of this intermediate material or another intermediate material is more than a pair of side wall portions. A die that uses at least a part of the portion that is distant inward in the width direction at the same position as the portion where the first engagement portion or the second engagement portion is to be formed in the length direction for the cold forging. It is assumed that the escape part is not hit.
[0026]
[Action]
According to the rocker arm of the present invention configured as described above and the manufacturing method thereof, the performance of an engine incorporating the rocker arm is improved when the rocker arm is made by cold forging a metal wire material. Can be planned.
That is, in the case of the rocker arm according to the first aspect, the pressurizing directions at the time of cold forging with the material and the first intermediate material differ by 90 degrees. For this reason, compared with the case where a raw material and an intermediate raw material are pressurized from both sides of the same direction in all the cold forging processes, it can suppress that an excessive stress concentrates on a part of rocker arm obtained. When a metal wire is made by extrusion molding, the fibrous flow (fiber flow) of the internal structure of the material substantially coincides with the length direction of the material. And much of the fiber flow of the first intermediate material obtained from this material can be made substantially parallel to the length direction of the first intermediate material, or close to parallel. In the case of the rocker arm described in claim 1, since this first intermediate material is cold forged by pressurizing such a first intermediate material in a direction perpendicular to the length direction, Compared to the case where cold forging is applied to the first intermediate material by pressurizing the first intermediate material from both sides in the length direction, the resulting fiber flow of the rocker arm is a smooth flow corresponding to the overall shape of the rocker arm. Can be. As a result, the strength of the obtained rocker arm can be improved, and the durability of the engine incorporating this rocker arm can be improved.
Further, in the case of the rocker arm manufacturing method according to the third aspect, when the first intermediate material is cold forged, the burr on the outer peripheral side (outside burr) is not generated. Unlike the case of the rocker arm manufacturing method described in Patent Document 1, no fiber flow is created in the outer burr portion. For this reason, the fiber flow is not disturbed by the outer burr portion, and is not divided along with the removal of the outer burr. For this reason, the strength of the finished product (product) of the rocker arm can be improved. In addition, the shape accuracy of the rocker arm can be improved without causing defects due to the sheared surface and the fractured surface accompanying the removal of the outer burr. Further, the forging load can be reduced and the material cost can be easily reduced.
In addition, it is preferable that there is no burr (inner burr) generated on the inner peripheral side, but even when the inner burr is formed, it is preferable to provide the inner burr at a position that does not affect the use of the rocker arm.
[0027]
In the case of the rocker arm according to the fourth aspect, both end portions of the support shaft supporting the roller are plastically deformed radially outwardly at the outer opening end peripheral portion of the through hole formed in each side wall portion. And the chamfered portion can be fixed by caulking. For this reason, the cam follower in which the roller is assembled to the rocker arm, the both end portions of the support shaft can be coupled and fixed to each side wall portion with sufficient coupling strength, and the durability of the engine incorporating the rocker arm can be improved. . Further, the operation of inserting the end portion of the support shaft into the through hole can be easily performed. For this reason, the cost reduction of the rocker arm which couple | bonded the support shaft can be aimed at.
[0028]
Further, in the case of the rocker arm according to claim 6, when the intermediate material or another intermediate material in which the first engaging portion or the second engaging portion is formed by cold forging is used, Of the intermediate material, it is possible to smoothly escape the surplus portion present at a position near the portion where the first engagement portion or the second engagement portion is to be formed. For this reason, the shape accuracy and dimensional accuracy of the first engagement portion or the second engagement portion can be improved, and when the obtained rocker arm is used, the valve body or swing support is provided at a predetermined position of the rocker arm. The members can be engaged with high accuracy. Therefore, the performance of an engine incorporating this rocker arm can be improved. Furthermore, it is possible to prevent an excessive load from being applied to the die used for the cold forging, and to improve the durability of the die. For this reason, the cost of the single item at the time of mass production of the rocker arm can be reduced.
[0029]
In the case of the rocker arm according to the eighth aspect, the molding workability can be improved and the strength and shape accuracy can be improved.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
1 to 21 show an example of an embodiment of the present invention. The feature of this example is that an engine incorporating the rocker arm 1a obtained when the rocker arm 1a (FIGS. 1 to 4) is manufactured by cold forging the material 32 (FIG. 6) made of metal wire. In order to improve the performance, the pressure direction when cold forging the material 32 and the first intermediate material 33 (FIG. 7) obtained from the material 32, and the through holes 5, 5 in the side walls 2a, 2a. And the cold forging operation when forming the first and second recesses 36 and 40, which are the first and second engaging portions, respectively. It is in. Since the manufacturing apparatus of the rocker arm 1a is substantially the same as the manufacturing apparatus shown in FIGS. 22 to 28 described above, the overlapping description will be omitted or simplified, and the following description will focus on the features of this example. .
[0031]
As shown in FIGS. 1 to 4, the rocker arm 1a obtained by the method of manufacturing the rocker arm of this example includes a pair of side wall portions 2a and 2a that are substantially parallel to each other and formed in a substantially triangular shape, and both side wall portions 2a It has the 1st connection part 3a and the 2nd connection part 4a which connect the both ends of the length direction (up-down direction of FIG. 1, 2) of 2a. Further, a pair of circular holes 5 and 5 are formed concentrically with each other in the longitudinal direction intermediate part of both side wall parts 2 and 2, and a roller 35 engaged with the cam is rotated in these circular holes 5 and 5. Both end portions of the support shaft for supporting freely can be supported and fixed.
[0032]
Further, in order to abut the base end portion of the valve body, the first engaging portion is a first engaging portion on one side of the first connecting portion 3a (the right side surface in FIGS. 1 and 3 and the front side surface in FIG. 2). A recess 36 is formed. In addition, in order to abut the tip of the lash adjuster, a semi-spherical first portion which is a second engaging portion is provided on one side of the second connecting portion 4a (the right side surface in FIG. 1 and the front side surface in FIG. 2). A second recess 40 is formed. In the case of this example, an example is shown in which the tip end portion of the lash adjuster is engaged as the swing support member with the second engaging portion, but a screw hole is formed in the second connecting portion 4a. The present invention can also be applied to a structure in which an adjustment screw is screwed into the screw hole portion. Further, as shown in FIG. 4, a bus bar is formed on the peripheral edge of the opening end on the outer side in the axial direction (the lower side in FIG. 4) of the circular hole 5 for supporting both ends of the support shaft formed on each side wall 2a. Is a straight bowl-shaped chamfer 37.
[0033]
Further, in the case of the rocker arm 1a manufactured by the method of manufacturing the rocker arm of this example, the side wall portions 2a and 2a are formed by punching to form the first and second connecting portions 3a and 4a. A shearing surface is formed on the inner surface of the portion near one end in the width direction (the portion near the right end in FIGS. 1 and 4) as shown by the matte surface in FIG. 1. In the rocker arm 1a, the entire shearing surface is not made to oppose either the both end surfaces of the roller 35 or the chamfer 52 (FIG. 2) formed at the continuous portion between the both end surfaces and the outer peripheral surface. However, since the chamfered 52 portion does not rub against the inner surfaces of the side wall portions 2a and 2a, the chamfered 52 and the sheared surface may face each other. In FIG. 1, the roller 35 is shown by two concentric circles of two-dot chain lines. The outer circle of these concentric circles is the outer peripheral surface of the roller 35 (the outer peripheral edge of the chamfer 52), and the inner circle is The end surface of the roller 35 (the inner peripheral edge of the chamfer 52) is shown (the same applies to FIGS. 13 and 18 described later). In the case of this example, the edge (point P) closest to one side in the width direction (right side in FIG. 1) at the edge of the roller 35 side (left side in FIG. 1) of the shearing surface, One side of the first and second connecting portions 3a, 4a (the right side surface in FIG. 1), one side in the width direction (the right side in FIG. 1) than the portion removed from the first and second concave portions 36, 40. It is trying to be located in. In the case of this example, the fiber flow, which is the flow of the fibrous tissue inside the rocker arm 1a, flows entirely in the length direction of the rocker arm 1a. Further, the fiber flow is cut at a portion excluding at least both end edges in the length direction and the inner peripheral surface of the through hole 45 formed between the first and second connecting portions 3a and 4a. Not. In addition, each said side wall part 2a, 2a is formed in the substantially triangular shape. The reason why these side wall portions 2a and 2a are formed in such a shape is that a circular hole 5 of a predetermined size is formed in the middle portion of each of the side wall portions 2a and 2a and the rocker arm 1a is reduced in weight. This is in order to achieve a balance with that. In addition, the circular holes 5 are located at substantially the same positions in the width direction (left and right direction in FIG. 1, the front and back direction in FIG. 2) of the first and second connecting portions 3a and 4a in a part of the side walls 2a and 2a. In the case of forming 5 or the like, the side walls 2a and 2a may be formed in a substantially rhombus shape in consideration of weight reduction. Also in this case, by adopting the manufacturing method of the present invention, it is possible to manufacture a rocker arm having a desired shape if the process and the shape of the intermediate material are appropriately set.
[0034]
The rocker arm 1a configured as described above is manufactured as shown in FIG. Next, the manufacturing method of this rocker arm 1a will be described in detail. First, the end of the metal wire wound around the rotary support device 8 in a coil shape is transferred to the cold forging machine 10 by a roller-type wire supply mechanism 11 (see FIG. 23) provided in the cold forging machine 10. Introduce inside. In this example, the metal wire has a circular cross section. In addition, this metal wire is preliminarily immersed in a lubricating chemical bath such as zinc phosphate, so that a lubricating coating layer such as a zinc phosphate coating is formed on the outer peripheral surface thereof. Moreover, this metal wire is made by extrusion molding. For this reason, the direction of the fibrous flow (fiber flow) of the structure inside the metal wire substantially coincides with the length direction of the metal wire. Then, as a first step, a cylindrical material as shown in FIG. 6 is obtained by cutting the metal wire into a predetermined length by a cutting mechanism 12 (see FIG. 24) provided in the cold forging machine 10. (Blank) 32 is made. In addition, what is necessary is just to use the well-known multistage type cold forging machine for the cold forging molding machine 10 used in order to manufacture a rocker arm in this example. For example, it is possible to use substantially the same one as used in the conventionally known rocker arm manufacturing method shown in FIGS. For this reason, in the following description, the specific structure of the cold forging machine 10 is omitted or simplified. Further, the cold forging machine 10 used in the present example does not generate burrs (outer burrs) at least on the outer peripheral side in the manufacturing process of the rocker arm 1a, unlike the one shown in FIGS.
[0035]
The columnar material 32 obtained in the first step moves to the first forging station provided in the cold forging machine 10 without changing the direction. Then, as a second step, the material 32 is driven into a fixed die by a movable die in the horizontal direction, and the first cold is made to expand in the radial direction while compressing the material 32 in the axial direction (length direction). Forging (preliminary molding) is performed to produce a first intermediate material 33 having a shape as shown in FIG. That is, in this first cold forging, the material 32 is pressurized from both sides in the axial direction of the material 32 by a movable die and a fixed die. The first intermediate material 33 obtained in this way has a barrel shape whose diameter is maximized at the axially intermediate portion. That is, the first intermediate material 33 has a diameter that decreases toward the both ends in the axial direction from the maximum diameter portion 38 having the maximum diameter provided in the intermediate portion. Further, both end surfaces in the axial direction of the first intermediate material 33 are substantially flat surfaces. The axial position of the maximum diameter portion 38 is regulated according to the position of the pair of side wall portions 2a, 2a, and is an intermediate portion in the axial direction, but is not necessarily the central portion in the axial direction. Each cross-sectional area in the direction orthogonal to the axial direction of the barrel-shaped first intermediate material 33 substantially corresponds to each cross-sectional area in the direction orthogonal to the length direction of the second intermediate material 34b described later. . The shape of the first intermediate material 33 must be carefully set in consideration of the material flow during forging.
[0036]
Once the first intermediate material 33 is formed, the first intermediate material 33 is then moved as shown in FIG. 8 by the material turning supply device 23 (see FIG. 24) provided in the cold forging machine 10. The first intermediate material 33 is supplied from the first forging station to the second forging station while changing the direction of.
[0037]
Next, as a third step, the first intermediate material 33 is driven in the horizontal direction into the fixed mold by the movable mold of the second forging station, so that the direction perpendicular to the length direction of the first intermediate material 33 is obtained. The second cold forging (second pre-forming) is performed to pressurize the first intermediate material 33 from both sides in the radial direction. Then, a second intermediate material 34a having a rough shape and dimensions of the rocker arm 1a (FIGS. 1 to 4) as shown in FIGS. The second intermediate material 34a includes a pair of side wall portions 2a, 2a and a base portion 39 that connects one end edges {the right end edge in FIG. 9 (a), FIG. 10} of the both side wall portions 2a, 2a to each other. Is provided. Further, the intermediate portion in the longitudinal direction of the base portion 39 is slightly protruded on the side opposite to the side wall portions 2a and 2a {the right side in Fig. 9 (a) and Fig. 10}. In the case of this example, the width direction of each side wall 2a, 2a constituting the second intermediate material 34a at a position corresponding to the maximum diameter portion 38 of the first intermediate material 33 {FIG. 9 (a)]. , The dimension in the horizontal direction in FIG. 10 is maximized. Since the lubricating film layer is formed in advance on the outer peripheral surface of the first intermediate material 33 subjected to such second cold forging, the inner surfaces of the fixed mold and the movable mold, and the outer surface of the first intermediate material 33 The friction acting between the two can be kept small. With this configuration, the workability and shape accuracy of the second intermediate material 34a can be improved. The second intermediate material 34a obtained by such a third process is taken out from between the fixed mold and the movable mold and supplied to the third forging station.
[0038]
Next, as a fourth step, the movable die 44 of this third forging station {FIG. 11 (a), FIG. 15} is used to fix the fixed die 43 (FIG. 15) in the same manner as the second cold forging. The second intermediate material 34a is driven in the horizontal direction. And this 2nd intermediate material 34a is pressurized from the same direction as the case of said 2nd cold forging, This 3rd cold forging (main forming) is given to this 2nd intermediate material 34a, FIG. As shown in FIG. 15, a second intermediate material 34b having a shape and size slightly close to the finished product of the rocker arm 1a is produced. In the second intermediate material 34b, the lengthwise intermediate portion of the base portion 39 is protruded greatly on the side opposite to the side wall portions 2a, 2a. Also, the longitudinal ends of one side of the base 39 {the right side in Fig. 11 (a), the front side in Fig. 11 (b)} are roughly shaped as the first and second recesses 36, 40. And dimensions. In the third cold forging, the side walls 2a and 2a are adjusted so that the shapes and dimensions of the side walls 2a and 2a are substantially the same as the finished product.
[0039]
Furthermore, in the case of this example, a first recess 36 for abutting the tip end portion of the valve body in the length direction on both side surfaces of the length direction one end portion (the lower end portion in FIG. 11) of the base portion 39; At the same position, the opposite ends of the first recess 36 in the width direction {front and back direction in FIG. 11 (a), left / right direction in FIG. 11 (b), vertical direction in FIG. The relief portions 41 and 41 of the material when performing the forging are used. The fixed mold 43 and the movable mold 44 are prevented from hitting the escape portions 41, 41.
[0040]
The other end of the base portion 39 in the length direction (upper end portion in FIG. 11) (the left side surface in FIG. 11 (a), the back side surface in FIG. 11 (b)) is the lash adjuster in the length direction. At the same position as the second recess 40 for abutting the tip, the position opposite to the second recess 40 is used as the second escape portion 42 of the material when the third cold forging is performed. . Further, the fixed mold 43 and the movable mold 44 are prevented from hitting the second escape portion 42 as well.
[0041]
Further, in the case of this example, inside the second intermediate material 34b, the second intermediate material 34b and the second intermediate material 34b are positioned at positions corresponding to the positions of the rollers 35 on the rocker arm 1a (FIGS. Even when it is assumed that the rocker arm 1a is combined through a support shaft (not shown), the shape and size of the second intermediate material 34b are restricted so that the roller 35 and the base 39 do not interfere with each other. Specifically, as shown in detail in FIG. 14, the inner surface of the intermediate portion in the longitudinal direction of the second intermediate material 34 b is connected to the inner edge of each of the side wall portions 2 a and the rear end edge of the smooth flat surface portion 53. The cylindrical surface portion 54 constituting the inner surface of the intermediate portion of the base portion 39 has a continuous shape with the curved surface portion 55. When it is assumed that the roller 35 is assembled inside the second intermediate material 34b as described above, the roller 35 interferes with any of the flat surface portion 53, the cylindrical surface portion 54, and the curved surface portion 55. In order not to do so, the shape and dimensions of the inner surface of the second intermediate material 34b are restricted. Further, both end surfaces of the roller 35 excluding the chamfer 52 are located outside (on the left side in FIG. 14) from the back end edge (point Q in FIG. 14) of the flat surface portion 53 constituting the inner surface of each side wall 2a. To do. The second intermediate material 34b obtained by the fourth step is taken out from between the fixed die 43 and the movable die 44 of the third forging station and supplied to the first punching station.
[0042]
Next, as a fifth step, which is a drilling step performed at the first punching station, between the fixed die and the movable die, the second intermediate material 34b other than the intermediate portion in the longitudinal direction of the base portion 39b. While sandwiching the portion, the intermediate portion is punched by a punch for punching provided inside the fixed die or movable die. Preferably, the punch for punching is inserted between the side wall portions 2a and 2a, and the waste punching material (sealing material) is discharged to the opposite side to the side wall portions 2a and 2a. The reason for this is to prevent the burrs that accompany the punching process from facing the side where the roller 35 is disposed. And by this punching process, as shown in FIGS. 16-19, the 3rd intermediate raw material 46 which formed the through-hole 45 penetrated to the thickness direction in the intermediate part is made. Further, by processing the through holes 45, first and second connecting portions 3a and 4a are formed to connect the lengthwise ends of the side walls 2a and 2a. Furthermore, in the fifth step, at the same time as the punching process, one end in the width direction of each side wall 2a, 2a {FIG. 16 (a), right end in FIG. 17, front end in FIG. 16 (b)}. A forging process is performed to adjust the shape and dimensions. In FIG. 17, together with the third intermediate material 46, a small piece (cutting material) 50 generated by punching the base 39 by the punching process is also shown.
[0043]
Further, by forming the through-hole 45, the through-hole 45 including a portion near one end in the width direction of each of the side walls 2a and 2a {a portion near the right end in FIGS. 16A and 14 and 17 to 19}. A shear surface and a fracture surface are formed on the inner peripheral surface of the small piece 50 that is continuous with the outer peripheral edge of the small piece 50 (the portion indicated by the matte surface in FIGS. 16 and 18 and the portion indicated by the arrow a in FIG. 19). The The third intermediate material 46 obtained by the fifth step is taken out between the movable die and the fixed die of the first punching station and supplied to the fourth forging station.
[0044]
In the fourth forging station, as the sixth step, as shown in FIGS. 20 to 21, the third intermediate material 46 is transferred to the fixed die 47 by the movable die 48 as in the second and third cold forging. The fourth intermediate forging 46 was subjected to a fourth cold forging (sizing), and the first and second recesses 36 and 40 were adjusted to a predetermined shape and size with high precision. A fourth intermediate material 49 as shown in FIGS. In such a fourth cold forging, the third intermediate material 46 is pressurized from the same direction as in the second and third cold forging.
[0045]
Also in the case of the fourth cold forging, as in the case of the third cold forging, the width direction from the first recess 36 on both side surfaces of the first connecting portion 3a {FIG. ), The left and right directions in FIG. 20B, and the vertical direction in FIG. 21 are used as the material escape portions 41 and 41 when the fourth cold forging is performed. The fixed mold 47 and the movable mold 48 are prevented from contacting the portions 41 and 41. Further, on the other surface of the second connecting portion 4a {the left side surface in Fig. 20 (a), the back side surface in Fig. 20 (b)}, the position opposite to the second recess 40 is set to the fourth cold forging. The second escape portion 42 of the material when applying the above.
[0046]
In the fourth forging station, the step of driving the third intermediate material 46 in the horizontal direction into the fixed die 47 by the movable die 48 is repeated as necessary, so that each of the first and second recesses is repeated. At the same time as adjusting the shapes and dimensions of 36 and 40, adjustment of the parallelism of each of the side wall portions 2a and 2a, and adjustment of the interval between the inner side surfaces and the interval between the outer side surfaces of these side wall portions 2a and 2a. You can also do it. Further, when burr occurs at one end in the width direction of each of the side walls 2a and 2a, the burr can be reduced or eliminated by performing a slight surface pressing. When the sixth step is completed, the fourth intermediate material 49 is taken out from between the fixed die 47 and the movable die 48 of the fourth forging station, and the fourth intermediate material 49 is used as the second intermediate material 49. Supply to the punching station.
[0047]
In this second punching station, as a seventh step, the second punching process is performed on a part of each side wall 2a, 2a of the fourth intermediate material 49, and the rocker arm shown in FIGS. Build the finished product of 1a. In the case of this example, this second punching process is performed inside the cold forging machine 10. As one of the methods for this purpose, when the fourth intermediate material 49 is supplied from the fourth forging station to the second punching station, the fixed die and the movable die front end surface of the second punching station, and the above-mentioned A method of changing the direction of the fourth intermediate material 49 by 90 degrees so that the outer surfaces of the side walls 2a and 2a face each other is conceivable. The fourth intermediate material 49 is sandwiched between the fixed mold and the movable mold of the second punching station, and each of the circular holes is formed by a punch for punching provided inside the fixed mold or the movable mold. A method of forming 5, 5 is conceivable. As another method, the fourth intermediate material 49 is supplied as it is without changing the direction from the fourth forging station to the second punching station, and each movable die 44 of the first to fourth forging stations is supplied. The movement of the drive mechanism (sliding mechanism) for reciprocating 48 is converted into a direction different from this reciprocating movement direction by 90 degrees by the cam molds provided on both sides, and the punching holes attached to this cam mold There is also a method of forming the circular holes 5 and 5. Further, in the case of this example, a chamfer 37 (FIG. 4) is formed on the peripheral edge of the opening end on the axially outer side of each of the circular holes 5 and 5, and the forging process is performed simultaneously with the drilling of the circular holes 5 and 5. To form. The finished product of the rocker arm 1a thus obtained is taken out from the second punching station to a predetermined position by a take-out chuck.
[0048]
In the case of the method of manufacturing the rocker arm of the present example configured as described above, the rocker arm 1a is manufactured by cold forging the material 32 made of metal wire, and the engine incorporating the rocker arm 1a is used. Improve performance.
That is, in the case of this example, as a second step, the material 32 is subjected to first cold forging by pressurizing the material 32 from both sides in the axial direction (length direction), and the third and fourth steps. By pressing the first and second intermediate materials 33 and 34a obtained from the material 32 from both sides in the direction orthogonal to the length direction (the thickness direction of the base portion 39 or each of the connecting portions 3a and 4a) The first and second intermediate materials 33 and 34a are subjected to second and third cold forging. In this way, the first cold forging and the second and third cold forgings add the material 32 and the first and second intermediate materials 33 and 34a from both sides in directions different from each other by 90 degrees. Therefore, it is possible to suppress excessive stress from being concentrated on a part of the obtained rocker arm 1a as compared with the case where the material and the intermediate material are pressed from both sides in the same direction by all cold forging.
[0049]
Further, as in this example, when a metal wire is made by extrusion molding, the fiber flow of the material 32 substantially coincides with the length direction of the material 32. Then, most of the fiber flow of the first intermediate material 33 obtained from the material 32 can be made substantially parallel to or close to the length direction of the first intermediate material 33. In the case of this example, cold forging is performed on the first intermediate material 33 and the like by pressing the first intermediate material 33 and the like from both sides in the direction orthogonal to the length direction in the third step and the like. Therefore, the fiber flow of the rocker arm 1a is obtained compared to the case where cold forging is applied to the first intermediate material 33 by pressing the first intermediate material 33 from the both sides in the longitudinal direction. A smooth flow corresponding to the overall shape of the rocker arm 1a can be obtained. As a result, the strength of the obtained rocker arm 1a can be sufficiently secured, and the durability of the engine incorporating the rocker arm 1a can be improved. In the case of this example, in the third, fourth, and sixth steps, the first to third intermediate materials 33, 34a, and 46 are pressed from both sides in the direction orthogonal to the length direction, so that each of these intermediate materials is pressed. When cold forging the materials 33, 34a, and 46, the process is set so as not to generate any burr (outer burr) on the outer peripheral side. For this reason, unlike the case of the rocker arm manufacturing method described in Patent Document 1, the fiber flow is not created in the outer burr portion. Therefore, the fiber flow is not disturbed by the outer burr portion, and is not divided along with the removal of the outer burr. For this reason, the strength of the finished product (product) of the rocker arm 1a can be improved. In addition, the shape accuracy of the rocker arm 1a can be improved without causing defects due to the sheared surface and the fractured surface accompanying the removal of the outer burr. Of course, it is easy to reduce material costs by suppressing material loss.
[0050]
Also, when cold forging the first intermediate material 33 and the like by pressing the first intermediate material 33 and the like from both sides in a direction substantially perpendicular to or near the direction of most of the fiber flow, Since the process is set so as not to generate any external burrs, the contact area between the movable and fixed molds and the first intermediate material 33 is reduced, and the force applied to the first intermediate material 33 can be reduced. . Therefore, the moldability of the rocker arm 1a can be improved, and an excessive load can be prevented from being applied to the fixed mold and the movable mold used for cold forging, and the life of the fixed mold and the movable mold can be improved. Therefore, the cost of a single item at the time of mass production of the rocker arm 1a can be reduced. Furthermore, it becomes easy to suppress work hardening by reducing the deformation amount of each part.
[0051]
Further, in the second step for obtaining the first intermediate material 33 shown in FIG. 7, the material 32 is subjected to first cold forging by pressing the material 32 from both sides in the axial direction (length direction). Has been given. For this reason, without increasing the diameter of the metal wire, the obtained first intermediate material 33 can be easily formed into a barrel shape having a maximum diameter in the axially intermediate portion as in this example. For this reason, this barrel-shaped first intermediate material 33 has a pair of side walls 2a, 2a of a substantially triangular shape having a maximum width-direction dimension at the intermediate portion in the length direction, as in this example. The intermediate material 34a can be easily made. In addition, the external burr that occurs can be eliminated. Moreover, even if an internal burr | flash generate | occur | produces, it can suppress few at the position which does not have influence on use of a product. Therefore, the lightweight rocker arm 1a can be manufactured at low cost. Further, in the case of this example, the fiber flow of the rocker arm 1a generally flows in the length direction of the rocker arm 1a. Further, the fiber flow is cut at a portion excluding at least both end edges in the length direction and the inner peripheral surface of the through hole 45 formed between the first and second connecting portions 3a and 4a. It has not been. For this reason, the molding workability can be improved, and the strength and shape accuracy can be improved.
[0052]
Further, in the case of this example, both end portions of the support shaft that supports the roller 35 on the chamfer 37 (FIG. 4) formed on the outer peripheral edge portion of the outer opening end of the through holes 5 and 5 formed in the side walls 2a and 2a. Can be caulked. Specifically, the chamfered portion 37 and the chamfered portion formed by plastically deforming both ends of the support shaft radially outward can be engaged. Therefore, both end portions of the support shaft can be coupled and fixed to the through holes 5 and 5 with sufficient coupling strength. As a result, the cam follower in which the roller 35 is assembled to the rocker arm 1a, the both end portions of the support shaft can be coupled and fixed to the side wall portions 2a and 2a with sufficient coupling strength, and the durability of the engine incorporating the rocker arm 1 is achieved. Can be improved. Furthermore, since the end portion of the support shaft can be inserted inside any one of the through holes 5 while being guided by the chamfer 37, the insertion operation of the support shaft into the through hole 5 can be easily performed. . For this reason, the cost of the cam follower combining this support shaft and roller 35 and the rocker arm 1a can be reduced.
[0053]
Further, in the case of this example, the first and second recesses 36 and 40 are formed by cold forging in the fourth step for obtaining the second intermediate material 34b as shown in FIG. At the same time, with respect to the length direction of the base portion 39 of the second intermediate material 34b, at the same position as the first and second concave portions 36 and 40, and near the first and second concave portions 36 and 40, A material escape portion 41 or a second escape portion 42 is provided. In the sixth step for obtaining the fourth intermediate material 49 shown in FIG. 20 from the third intermediate material 46 shown in FIG. 16, the first and second recesses 36 and 40 are formed by cold forging. At the time of forming, the first and second recesses 36, 40 in the length direction at the portion of the third intermediate material 46 that is outside the pair of side walls 2a, 2a in the width direction. The material escape portion 41 or the second relief portion 42 is provided at the same position as that of the portion to be formed and in the vicinity of the first and second recesses 36 and 40. Accordingly, when the first and second recesses 36 and 40 are formed, the surplus portions of the second intermediate material 34b and the third intermediate material 46 are smoothly evacuated. It is possible to easily process the recesses 36 and 40 into a predetermined shape and size with high accuracy. For this reason, the shape accuracy and dimensional accuracy of each of the first and second recesses 36 and 40 can be improved, and when the obtained rocker arm 1a is used, the base end portion of the valve body is placed at a predetermined position of the rocker arm 1a. And the performance of an engine incorporating the rocker arm 1a can be improved by accurately engaging the tip of the lash adjuster. Moreover, since the second relief portion 42 is located on the opposite side of the second recess 40 in the base 39 or the second connecting portion 4a, the second recess 40 has a predetermined shape and size. In addition, it can be easily processed with higher accuracy. Furthermore, it is possible to prevent an excessive load from being applied to the fixed dies 43, 47 and the movable dies 44, 48 used for forging, and the life of these dies 43, 47, 44, 48 can be improved. For this reason, the cost of the single item at the time of mass production of the rocker arm 1a can be further reduced.
[0054]
Further, in the case of this example, the entire shearing surface formed on the inner surface of each side wall 2a, 2a by the punching process for forming the first and second connecting portions 3a, 4a is applied to both end surfaces of the roller 35. A rocker arm 1a that does not oppose can be made. And according to the rocker arm 1a obtained in this way, it is possible to prevent the both end faces of the roller 35 from coming into contact (rubbing) with a rough shear surface. For this reason, in a state where the roller 35 is assembled to the rocker arm 1a, the roller 35 can be smoothly rotated. Further, it is possible to prevent abnormal wear from occurring on both end faces of the roller 35 and to suppress generation of wear powder due to wear at the contact portion. Therefore, it is possible to improve the performance such as an improvement in output and durability of the engine incorporating the rocker arm 1a. In order to improve the performance as described above, it is not necessary to perform the troublesome work of smoothing the sheared surface by surface pressing or the like in the step after the punching process.
[0055]
In the case of this example, as the fifth and sixth steps, punching of the base 39 and forging for accurately adjusting the first and second recesses 36 and 40 to a predetermined shape and size. Are performed in a separate process. For this reason, it becomes easy to improve the accuracy of the shape and size of each of the recesses 36 and 40.
[0056]
In this example, the circular holes 5 and 5 provided in the side walls 2a and 2a are formed by punching. In the present invention, the circular holes 5 and 5 are formed by punching. Instead, it can be formed by shaving or cutting. However, when the cutting process is employed, the cost of the rocker arm 1a increases. For this reason, from the viewpoint of reducing the cost of the rocker arm 1a, the circular holes 5, 5 are preferably formed by punching or shaving, and more preferably, each of the above-described circular holes 5, 5 is formed by punching. Circular holes 5 and 5 are formed. Further, the intermediate material taken out from the cold forging machine 10 can be transported to another press machine, and the circular holes 5 and 5 can be punched by this other press machine.
[0057]
In the case of this example, a lubricating film layer such as a zinc phosphate film is previously formed on the metal wire. However, the material 32 and the first to fourth intermediate materials 33 are applied by applying a lubricant to the inner surface of the mold of the cold forging machine 10 or supplying lubricating oil to the inside of the cold forging machine 10. Friction between the outer surface of 34a, 34b, 46, 49 and the inner surface of the mold can also be suppressed.
[0058]
【The invention's effect】
Since the present invention is configured and operates as described above, the performance of an engine incorporating a rocker arm can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a finished rocker arm as an example of an embodiment of the present invention with a part thereof omitted.
FIG. 2 is a diagram viewed from the right side of FIG.
3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is a sectional view taken along the line BB in FIG.
FIG. 5 is a flowchart showing a method for manufacturing the rocker arm of the first example.
6A and 6B show materials obtained by the first step of the manufacturing method of the first example, where FIG. 6A is a front view, and FIG. 6B is a side view of FIG.
FIGS. 7A and 7B show a first intermediate material obtained by the second step, in which FIG. 7A is a front view, and FIG.
FIG. 8 is a diagram showing a state in which the orientation of the first intermediate material is changed by 90 degrees when the first intermediate material is moved from the first forging station to the second forging station.
FIGS. 9A and 9B show a second intermediate material obtained by the third step, where FIG. 9A is a cross-sectional view and FIG. 9B is a view as viewed from the right side of FIG.
FIG. 10 is a cross-sectional view taken along the line DD of FIG.
11A and 11B show a second intermediate material obtained by the fourth step, where FIG. 11A is a cross-sectional view, and FIG. 11B is a view as viewed from the right side of FIG.
FIG. 12 is a cross-sectional view taken along line EE in FIG.
FIG. 13 is an enlarged view of the same part.
14 is an enlarged cross-sectional view of a portion F in FIG.
FIG. 15 is a diagram showing a state in the middle of the forging operation in the fourth step, along a GG cross-section portion in FIG.
FIGS. 16A and 16B show a third intermediate material obtained by the fifth step, where FIG. 16A is a cross-sectional view, and FIG. 16B is a view as viewed from the right side of FIG.
FIG. 17 is a view showing the third intermediate material and a small piece generated at the time of the punching process in the fifth step in the HH cross-section portion of FIG. 16 (a).
18 is a partial enlarged cross-sectional view of FIG.
FIG. 19 is an enlarged cross-sectional view of a portion I in FIG.
20A and 20B show a fourth intermediate material obtained by the sixth step, where FIG. 20A is a cross-sectional view, and FIG. 20B is a view as viewed from the right side of FIG.
FIG. 21 is a diagram showing a state in the middle of the forging operation in the sixth step, taken along the line JJ in FIG. 20 (a).
22A and 22B show a rocker arm obtained by a conventionally known rocker arm manufacturing method, where FIG. 22A is a front view, and FIG. 22B is a view seen from the left side of FIG.
FIG. 23 is a schematic perspective view showing a state in which a rocker arm is manufactured by a conventionally known rocker arm manufacturing method.
FIG. 24 is a partial cross-sectional view of a cold forging machine used in the manufacturing method.
25 is a partially enlarged cross-sectional view of FIG. 24 showing a first forging station of the cold forging machine.
26 is a partially enlarged sectional view of FIG. 24 showing the first punching station. FIG.
FIG. 27 is a partially enlarged cross-sectional view of FIG. 24 showing the second forging station.
FIG. 28 is a partially enlarged sectional view of FIG. 24 showing the second punching station.
[Explanation of symbols]
1, 1a Rocker arm
2, 2a Side wall
3, 3a First connecting part
4, 4a Second connecting part
5 round holes
6 First engaging part
7 Second engaging part
8 Rotating support device
9 Metal wire
10 Cold forging machine
11 Roller wire supply mechanism
12 Cutting mechanism
13 materials
14 die block
15 lamb
16a-16d fixed type
17a-17d Movable type
18a-18d type holder
19 First forging station
20 First punching station
21 Second forging station
22 Second punching station
23 Material turning supply mechanism
24 First intermediate material
25, 25a, 25b Bali
26 through holes
27 Extruded member
28 Hole punch
29 Through-hole
30 Second intermediate material
31 Third intermediate material
32 materials
33 First intermediate material
34a, 34b Second intermediate material
35 Laura
36 First recess
37 Chamfer
38 Maximum diameter
39 Base
40 Second recess
41 Escape
42 Second relief
43 Fixed type
44 Movable type
45 Through hole
46 Third intermediate material
47 Fixed type
48 Movable type
49 Fourth Intermediate Material
50 small pieces
51 base
52 Chamfer
53 Plane section
54 Cylindrical surface
55 Curved surface

Claims

A pair of side wall portions that are made by cold forging a material obtained by cutting a metal wire into a predetermined length and spaced from each other, and both lengthwise ends of both side wall portions Each of the first and second coupling parts includes a first and second coupling part that couples the adjacent portions and a pair of concentric through holes formed at positions where both side wall parts are aligned with each other. The portion has an engaging portion that engages with the valve body or the swinging support member, and the material is cold forged by pressurizing the material from both sides in the length direction to produce the first intermediate material. And a step of cold-forging the first intermediate material to form a second intermediate material by pressurizing the first intermediate material from both sides in a direction orthogonal to the length direction. A built rocker arm.

A method for manufacturing a rocker arm according to claim 1, wherein the material is cold-forged by pressurizing the material from both sides in the longitudinal direction to produce a first intermediate material, A method of manufacturing a rocker arm comprising: a step of cold forging the first intermediate material to form a second intermediate material by applying pressure from both sides in a direction orthogonal to the length direction.

The method of manufacturing a rocker arm according to claim 1, wherein the material is cold forged by pressurizing the material from both sides in the length direction, and this length direction is related to the length direction of the rocker arm to be obtained. Corresponding to the change in the cross-sectional area in the direction orthogonal to the first intermediate material, the cross-sectional area is changed with respect to the length direction, and the first intermediate material in the direction orthogonal to the length direction A method of manufacturing a rocker arm comprising: a step of performing cold forging on the first intermediate material by applying pressure from both sides, and not generating burrs on the outer peripheral side.

A pair of side wall portions that are made by cold forging a material obtained by cutting a metal wire into a predetermined length and spaced from each other, and both lengthwise ends of both side wall portions Each of the first and second coupling parts includes a first and second coupling part that couples the adjacent portions and a pair of concentric through holes formed at positions where both side wall parts are aligned with each other. The rocker arm has an engaging portion that engages with the valve body or the swing support member, and when the through holes are formed in the side wall portions, the outer openings of the through holes are formed. Rocker arm with chamfered edges at the same time.

The method for manufacturing a rocker arm according to claim 4, wherein when each through hole is formed in each side wall portion, chamfering is simultaneously formed on the outer opening end portion of each through hole.

A pair of side wall portions that are made by cold forging a material obtained by cutting a metal wire into a predetermined length and spaced from each other, and both lengthwise ends of both side wall portions Each of the first and second coupling parts includes a first and second coupling part that couples the adjacent portions and a pair of concentric through holes formed at positions where both side wall parts are aligned with each other. The rocker arm has an engaging portion that engages with the valve body or the swing support member, and the first or second intermediate material obtained from the material is subjected to cold forging. When forming an intermediate material or another intermediate material in which the engagement portion or the second engagement portion is formed, the intermediate material or a part of the other intermediate material is wider than the pair of side wall portions in the width direction. Among the portions that are dislodged inward, the first engaging portion or the second engaging portion is formed in the length direction. At least a portion of the feeder part the same position, a manufacturing method of a rocker arm and escape portion that does not rely on the type to be used for forging the cold.

The method for producing a rocker arm according to claim 6, wherein the first engagement portion or the second engagement portion is formed by cold forging the material or an intermediate material obtained from the material. When producing an intermediate material or another intermediate material, a part of the intermediate material or another intermediate material, and a portion of the intermediate material that is separated from the pair of side wall portions on the inner side in the width direction, the first direction with respect to the length direction. A method for manufacturing a rocker arm, wherein at least part of the same position as a part where the engaging part or the second engaging part is to be formed is a relief part that does not contact a die used for the cold forging.

A pair of side wall portions that are made by cold forging a material obtained by cutting a metal wire into a predetermined length and spaced from each other, and both lengthwise ends of both side wall portions The first and second connecting portions that connect the adjacent portions, and a pair of concentric through holes formed at positions where the both side wall portions are aligned with each other. The rocker arm has an engagement portion that engages with the valve body or the rocking support member, and the fiber flow that is the flow of the fibrous tissue inside is generally the length of the rocker arm. The fiber flow is cut at a portion excluding at least both end edges in the length direction and the inner peripheral surface of the through hole formed between the first and second connecting portions. Not rocker arm.