JP2004358530A

JP2004358530A - Rocker arm and method for manufacturing the same

Info

Publication number: JP2004358530A
Application number: JP2003161583A
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: 2003-06-06
Filing date: 2003-06-06
Publication date: 2004-12-24
Anticipated expiration: 2023-06-06
Also published as: JP3659961B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rocker arm by performing cold forging of a stock formed of a metallic wire, and to enhance the performance of an engine with the rocker arm built therein. <P>SOLUTION: A second intermediate stock 34b having a pair of side wall parts 2a and a base part 39 to connect one end part to each other in the width direction of the side wall parts 2a respectively by performing cold forging on a stock obtained by cutting a metallic wire to the predetermined length. First and second connection parts are formed by blanking the base part 39 of the second intermediate stock 34b. When it is assumed that a roller 35 is disposed at the position corresponding to the position of arrangement of the roller in a rocker arm to be obtained on the inner side of the second intermediate stock 34b to be blanked, the roller 35 is not allowed to interfere with the base part 39. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、エンジンの動弁機構に組み込み、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のカムフォロアを構成する、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、ロッカーアームを金属線材から成る素材に潤滑被膜層を形成して冷間鍛造を施す事により造る場合には、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る場合には、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、ロッカーアームの製造方法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む事により、この金属線材９の外周面に潤滑皮膜層を形成しておく。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行なう第二中間素材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。
【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様に、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と、製造作業に要する時間を或る程度短縮でき、ロッカーアーム１のコストの低減を図り易くなる。
【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１の場合には、次の▲１▼▲２▼の点で、ロッカーアームを組み込んだエンジンの性能を向上できる余地がある。
▲１▼ 第一、第二の連結部３、４を設ける為に第一中間素材２４に打ち抜き加工を施す事により形成される透孔２９が、１対の側壁部２の幅方向に関してほぼ中央部に位置している。又、この透孔２９は、打ち抜き加工により形成される為、その内周面は粗い剪断面及び破断面となっている。この為、ロッカーアーム１にローラを組み付けてカムフォロアを構成した状態で、このローラの両端面と上記剪断面及び破断面とが接触する可能性がある。この様にローラの両端面と剪断面及び破断面とが接触した場合には、このローラを円滑に回転させる事が難しくなり、ロッカーアーム１を組み込んだエンジンの性能向上を妨げる原因となる。又、上記ローラの両端面と剪断面及び破断面とが接触した場合には、このローラの両端面が異常摩耗したり、当該接触部で摩耗により生じた摩耗粉がエンジンの構成部材同士の隙間に入り込んで、エンジンの性能低下を招く可能性もある。特許文献１に記載されたロッカーアーム１の場合には、この様な点で、ロッカーアームを組み込んだエンジンの性能を向上できる余地がある。
▲２▼ 軽量化を図る面から未だ改良の余地がある。即ち、特許文献１に記載されたロッカーアーム１の場合には、第一の連結部３の片面｛図２２（ａ）の左側面｝での、各側壁部２、２の長さ方向一端縁（図２２の下端縁）の立ち上がり位置Ｐが、ロッカーアーム１の長さ方向一端縁（図２２の下端縁）付近となっている。この為、上記各側壁部２、２の長さ寸法が大きくなり、上記ロッカーアーム１の体積が不必要に嵩んで、上記ロッカーアーム１の重量が嵩む原因となっている。この様にロッカーアーム１の重量が嵩んだ場合には、このロッカーアーム１を組み込んだエンジンの出力性能等の性能の低下を招く原因となる。特許文献１に記載されたロッカーアーム１の場合には、この様な点でも、ロッカーアーム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得るロッカーアームで、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。
【００１４】
【課題を解決するための手段】
本発明のロッカーアーム及びその製造方法のうち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した１対の通孔とを備え、この第一の連結部が弁体と係合する第一の係合部を有するものであり、上記第二の連結部が揺動支持部材と係合する第二の係合部を有するものであり、上記各通孔に両端部を支持する支持軸の中間部にローラを支持する。
【００１５】
特に、請求項１に記載したロッカーアームは、上記第一、第二の連結部を形成する為の打ち抜き加工により上記各側壁部の内面に形成される剪断面及び破断面の総てを、上記ローラの両端面に対向させない。尚、ローラの両端面と外周面との連続部には面取りを形成する場合もあるが、この場合での請求項１に記載した「ローラの両端面」は、この面取りを除いた（面取りの内周縁よりも中心寄りの）部分である。
【００１６】
又、請求項４に記載したロッカーアームは、上記第一の係合部と反対側となる上記第一、第二の各連結部の片面に位置する上記各側壁部の長さ方向両端縁を、この長さ方向に関して、この第一の係合部のうちの上記弁体の基端面の中心を突き当てるべき部分から、上記第二の係合部のうちの上記揺動支持部材の先端面の中心を突き当てるべき部分又はこの揺動支持部材に設けた雄ねじ部を螺合する為のねじ孔の中心迄の間に位置させている。
【００１７】
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１対の側壁部とこれら両側壁部の一部同士を連結した基部とを備えた中間素材のこの基部に打ち抜き加工を施す事により、上記第一、第二の各連結部を形成する打ち抜き工程を備え、この打ち抜き加工を施すべき上記中間素材の内側で、得るべきロッカーアームでのローラの配置位置に対応する位置にこのローラを配置したと仮定した場合に、このローラと上記基部とが干渉しない様に、上記中間素材の形状及び寸法を規制する。
【００１８】
【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り得られたロッカーアームによれば、金属線材製の素材に冷間鍛造を施す事により得るロッカーアームで、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２に記載したロッカーアームの製造方法等により得られた請求項１に記載したロッカーアームの場合には、各側壁部の内面に打ち抜き加工により形成される剪断面及び破断面と、ローラの両端面とが接触する事を防止できる。この為、このローラを組み付けたロッカーアームで、このローラを円滑に回転させる事ができる。又、このローラ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、ロッカーアームを組み込んだエンジンの出力性能等の性能の向上を図れる。又、上記打ち抜き加工後の工程で、上記剪断面及び破断面を、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。
又、請求項３に記載したロッカーアームの場合には、各側壁部の容積を小さくできる為、ロッカーアーム全体の軽量化を図れる。この為、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。
【００１９】
【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、金属線材製の素材に冷間鍛造を施す事により得るロッカーアーム１ａ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るべく、第二中間素材３４ｂ（図１１〜１５）の一部を打ち抜く事により生じた剪断面及び破断面とローラ３５との位置関係と、１対の側壁部２、２の長さ方向両端縁の位置とを、それぞれ規制した点にある。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。
【００２０】
本例のロッカーアーム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をその中間部に回転自在に支持する為の、支持軸（図示せず）の両端部を支持固定する様に構成している。
【００２１】
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。
【００２２】
又、本例の場合には、上記第一、第二の連結部３ａ、４ａの他面（図１、３の左側面、図２の裏側面）に位置する、各側壁部２、２の長さ方向（図１〜２上下方向）両端縁を、この長さ方向に関して、上記第一の凹部３６のうちの上記弁体の先端面の中心を突き当てるべき部分αから、上記第二の凹部４０のうちの上記ラッシュアジャスタの先端面の中心部を突き当てるべき部分β迄の間に位置させている。更に、図２に示す様に、各側壁部２ａ、２ａの幅方向にロッカーアーム１ａを見た状態での、このロッカーアーム１ａの外周縁の形状を、矩形の長さ方向両端に１対の台形を連続させると共に、互いに隣り合う１対の直線部５６ａ〜５６ｇ同士を曲線部５７ａ〜５７ｈで滑らかに連続させた如き形状としている。そして、上記第一、第二の各連結部３ａ、４ａを厚さ方向（図２と同方向）に見た場合での外形を、複数の直線部５６ａ、５６ｃ〜５６ｅ、５６ｇ、５６ｈを備えた、角を丸めた台形状としている。又、図４に示す様に、上記各側壁部２ａに形成した、前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。
【００２３】
更に、本例のロッカーアーム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、剪断面及び破断面が形成されている。そして、この剪断面及び破断面の総てを、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と上記剪断面及び破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個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、上記剪断面及び破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Ｑ）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。
【００２４】
上述の様に構成する本例のロッカーアーム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。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、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である。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に示したものと異なり、ロッカーアーム１ａの製造工程でバリを発生させない。
【００２５】
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を軸方向に圧縮する、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。この第一中間素材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。
【００２６】
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。
【００２７】
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の径方向両側からこの第一中間素材３３を圧縮加工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の外面との間で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する。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。
【００２８】
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に第三の冷間鍛造（本成形）を施して、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。
【００２９】
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、弁体の先端部を突き当てる為の第一の凹部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、これら各逃げ部４１、４１に固定型４３及び可動型４４が突き当たらない様にしている。この構成により、これら固定型４３と可動型４４とに過大な荷重を加わる事を防止でき、これら各型４３、４４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低減できる。又、本例の場合には、上記各逃げ部４１、４１を、上記基部３９の長さ方向に関して上記第一の凹部３６と同位置とし、この第一の凹部３６の近くに設けている。この為、この第一の凹部３６を形成する場合に、余肉部の逃げを円滑に行なわせ、この第一の凹部３６を所定の形状及び寸法に精度良く加工し易くできる。
【００３０】
更に、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、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。この構成により、上記固定型４３と可動型４４とに過大な荷重が加わる事を、より効果的に防止できる。又、上記基部３９のうち、上記第二の凹部４０と反対側位置を第二の逃げ部４２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精度良く加工し易くできる。
【００３１】
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の内面の中間部を、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の内面の中間部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Ｐ）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。
【００３２】
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の形成により、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。
【００３３】
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。
【００３４】
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。そして、この構成により、これら各型４７、４８の寿命向上を図ると共に、上記第一の凹部３６を所定の形状及び寸法に精度良く加工し易くしている。
【００３５】
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。そして、この構成により、上記各型４７、４８の寿命向上を図ると共に、上記第二の凹部４０を所定の形状及び寸法に精度良く加工し易くしている。
【００３６】
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。
【００３７】
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。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。
【００３８】
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、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及び破断面の総てがローラ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、上記剪断面及び破断面と、ローラ３５の両端面とが接触する事を防止できる。この為、ローラ３５を組み付けたロッカーアーム１ａ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、本例のロッカーアーム１ａを組み込んだエンジンの出力性能等の性能の向上を図れる。又、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。
【００３９】
又、本例のロッカーアームの場合には、第一、第二の連結部３ａ、４ａの他面（図１、３の左側面、図２の裏側面）に位置する、上記各側壁部２、２の長さ方向両端縁を、この長さ方向に関して、第一の凹部３６のうちの弁体の先端面の中心を突き当てるべき部分αから、第二の凹部４０のうちのラッシュアジャスタの先端面の中心部を突き当てるべき部分β迄の間に位置させている。この為、上記各側壁部２ａ、２ａの長さ方向寸法を短くでき、これら各側壁部２ａ、２ａの容積を小さくできて、ロッカーアーム１ａ全体の軽量化を図れる。この為、このロッカーアーム１ａを組み込んだエンジンの性能を、より向上できる。更に、本例の場合には、上記第一、第二の各連結部３ａ、４ａを厚さ方向に見た場合での外形を、複数の直線部５６ａ、５６ｃ〜５６ｅ、５６ｆ、５６ｇを備えた台形状としている。この為、この外形を、これら各直線部５６ａ、５６ｃ〜５６ｅ、５６ｆ、５６ｇ部分の中間部を外側に膨らませた円弧形とする場合に比べて、上記第一、第二の各連結部３ａ、４ａの容積を小さくでき、ロッカーアーム１ａ全体を、より軽量にできる。
【００４０】
尚、本例のロッカーアームの場合と異なり、第二の連結部４ａに第二の凹部４０を形成しない代わりに、この第二の連結部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、請求項３に係る本発明を適用する事もできる。この場合には、例えば、第一の凹部３６と反対側となる第一、第二の各連結部３ａ、４ａの片面に位置する各側壁部２ａ、２ａの長さ方向両端縁を、この長さ方向に関して、上記第一の凹部３６のうちの弁体の基端面の中心を突き当てるべき部分から、上記ねじ孔の中心迄の間に位置させる。この様な構造の場合も、本例の場合と同様に、上記各側壁部２ａ、２ａの容積を小さくできる為、ロッカーアーム全体の軽量化を図れる。
【００４１】
又、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。
【００４２】
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。
【００４３】
又、本例の場合には、各側壁部２ａ、２ａの内面に形成される剪断面及び破断面の総てがローラ３５の両端面に対向しないロッカーアーム１ａを造る為に、第二中間素材３４ａに第三の冷間鍛造を施して第二中間素材３４ｂ（図１１〜１５）を造る第四工程として、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でのローラ３５の配置位置に対応する位置にこのローラ３５を配置したと仮定した場合でも、このローラ３５と基部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。但し、上述の様な各側壁部２ａ、２ａの内面に形成される剪断面及び破断面の総てがローラ３５の両端面に対向しない、ロッカーアーム１ａを得る為の製造方法は、本例の方法に限定するものではない。例えば、このロッカーアーム１ａを得る為の別の製造方法の第１例として、第二中間素材３４ｂの基部３９に打ち抜き加工を施して第三中間素材４６（図１６〜１９）を造る第五行程の後に、図２９に示す様に、この打ち抜き加工により各側壁部２ａ、２ａの幅方向一端部（図２９の右端部）で内面に剪断面及び破断面（図２９にａで示す部分）が形成された部分を、同図に矢印で示す様にこれら各側壁部２ａ、２ａの側方（図２９の上下方向）に向け折り曲げる冷間鍛造を施す事もできる。
【００４４】
又、上記ロッカーアーム１ａを得る為の別の製造方法の第２例として、第二中間素材３４ｂの基部３９に打ち抜き加工を施して第三中間素材４６を造る第五行程の後に、図３０に示す様に、この打ち抜き加工により各側壁部２ａ、２ａの幅方向一端部（図３０の右端部）で内面に剪断面及び破断面（図３０にａで示す部分）が形成された部分を、同図に矢印で示す様にこれら各側壁部２ａ、２ａの幅方向（図３０の左右方向）に向く様に、バーリング加工等により塑性変形させる冷間鍛造を施す事もできる。この様な、図２９、３０に示すロッカーアームの製造方法によれば、上記第四工程で得られた、打ち抜き加工を施すべき第二中間素材３４ｂの内側で、得るべきロッカーアーム１ａでのローラ３５の配置位置に対応する位置にこのローラ３５を配置したと仮定した場合に、このローラ３５と基部３９とが干渉するとしても、剪断面及び破断面の総てがローラ３５の両端面に対向しない、ロッカーアーム１ａを造る事ができる。
【００４５】
【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】ロッカーアームの製造方法を示すフローチャート。
【図６】同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】図１１（ａ）の部分拡大図。
【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。
【図２９】剪断面及び破断面がローラの両端面に対向しないロッカーアームを得る為の別の製造方法の第１例を、図１６のＨ−Ｈ断面部分で示す図。
【図３０】同第２例を、図１６のＨ−Ｈ断面部分で示す図。
【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
５６ａ〜５６ｇ直線部
５７ａ〜５７ｈ曲線部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rocker arm and a method of manufacturing the same, which are incorporated in a valve mechanism of an engine and constitute a cam follower for converting rotation of a camshaft into reciprocating motion of a valve body (an intake valve and an 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-stroke engines. In such a reciprocating engine, the movement of the camshaft rotating in synchronization with the rotation of the crankshaft (at a rotation speed of 1/2 in the case of a four-cycle engine) is controlled by the rocker arm to the intake valve and the exhaust valve. And the intake and exhaust valves may reciprocate in their respective axial directions.
[0003]
Conventionally, a cast product (a cast iron product or an aluminum die-cast product) has been generally used as a rocker arm to be incorporated in such a valve operating 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. 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 an increase in the time required for the manufacturing operation and an increase in waste of material. 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. I have. According to Patent Literature 1, when a rocker arm is formed by forming a lubricating coating layer on a material made of a metal wire and performing cold forging, it can be manufactured without cracks, can be manufactured with high precision, and has good workability. It can be done. In addition, when the rocker arm is manufactured by such cold forging, the shape accuracy and the dimensional accuracy can be increased as compared with the case where the rocker arm is manufactured by hot forging. 22 to 28 show an invention relating to a method of manufacturing a rocker arm described in Patent Document 1 described above. The method of manufacturing the rocker arm is described in detail in Patent Document 1 described above, and will be briefly described here. As shown in FIG. 22, the rocker arm 1 has a pair of side walls 2 and 2 which are substantially parallel to each other, and a first connecting portion 3 which connects these two side walls 2 and 2 at both ends in the longitudinal direction. And a second connecting portion 4. Among these first connection part 3 and second connection part 4, the first connection part 3 is provided with a first engagement part 6 for abutting the base end of the valve body, and a second connection part. 4 has a second engagement portion 7 for abutting a tip end of a swing support member such as a lash adjuster.
[0005]
Although not described in Patent Document 1, in the case of a rocker arm that is actually used, a pair of circular holes are formed concentrically with each other at the longitudinally intermediate portions of the side walls 2 and 2. Both ends of a support shaft for rotatably supporting a roller engaged with a cam are freely supported in these circular holes.
[0006]
The operation of manufacturing the rocker arm 1 as described above is performed as follows. First, as shown in FIG. 23, the end of the metal wire 9 wound in a coil shape around the rotation supporting device 8 is pulled out by a roller type wire feeding mechanism 11 provided in a cold forging machine 10, and this cold It is introduced into the forging machine 10. The metal wire 9 has a rectangular cross section. The metal wire 9 is previously immersed in a lubricating liquid tank such as zinc phosphate to form a lubricating film layer 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 a cutting mechanism 12 provided in the cold forging machine 10, thereby forming a rectangular parallelepiped material (blank). Build 13. The cold forging machine 10 is a so-called horizontal multi-stage forging machine. The cold forging machine 10 is provided with a die block 14 fixed inside and a horizontal so as to approach or separate from the die block 14 (moving far and near). And a ram 15 reciprocating in the direction. In the die block 14, a plurality of fixed dies 16a to 16d are arranged at intervals in the horizontal direction. In addition, a plurality of movable dies 17a to 17d are arranged at portions of the ram 15 facing the fixed dies 16a to 16d via mold 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 provided at portions where the fixed dies 16 a to 16 d and the movable dies 17 a to 17 d are arranged. Are provided respectively. The cuboid material 13 obtained in the first step is turned 90 degrees by the material turning supply mechanism 23 provided in the cold forging machine 10 while the first forging station 19 is turned. To supply.
[0007]
In this first forging station 19, as shown in detail in FIG. 25, the material 13 is horizontally driven into a fixed die 16a by a movable die 17a, as shown in FIG. To produce the first intermediate material 24 having the approximate shape and dimensions of the rocker arm 1. The first intermediate material 24 has an H-shaped cross section including a pair of side walls 2 (FIG. 22) and a base 51 connecting the widthwise intermediate portions of the side walls 2. A burr 25 is formed on the outer peripheral surface of the intermediate portion in the thickness direction of the first intermediate material 24 over the entire circumference. Since a lubricating film layer is previously formed on the outer peripheral surface of the material 13 to be subjected to such cold forging, it acts between the inner surfaces of the fixed mold 16a and the movable mold 17a and the outer surface of the material 13. Friction can be kept small. With this configuration, the workability and the shape accuracy of the first intermediate material 24 can be improved. The first intermediate material 24 obtained in such a second step is taken out from between the fixed die 16a and the movable die 17a and supplied to a first punching station 20 as shown in detail in FIG. .
[0008]
In the first punching station 20, as a third step, between the distal end surface of the cylindrical extrusion member 27 provided in the through hole 26 of the fixed die 16b and the distal end surface of the cylindrical movable die 17b, The main body portion of the first intermediate material 24 excluding the burr 25 is sandwiched. Then, by pushing the main body portion into the through hole 26, the burr 25 is removed at the peripheral edge of the opening end of the through hole 26. At the same time, the intermediate portion of the base 51 (FIG. 25) provided on the first intermediate material 24 is punched out by the punch 28 for punching provided inside the pushing member 27, and the second intermediate portion having the through-hole 29 is punched out. The material 30 is made. By forming the through holes 29, the second intermediate material 30 includes first and second connecting portions 3 that connect both ends of the pair of side walls 2 (FIG. 22) in the length direction. 4 are formed. The second intermediate material 30 obtained in 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 horizontally driving the second intermediate material 30 into the fixed die 16c by the movable die 17c. Then, a third intermediate material 31 having a size and a shape close to a finished product is manufactured. At this time, burrs 25a and 25b are formed on the outer peripheral surface in the thickness direction intermediate portion of the third intermediate material 31 and 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 that performs such cold forging, the inner surface of the fixed die 16c and the movable die 17c and the outer surface of the second intermediate material 30 The friction acting between them can be kept small. With this configuration, the 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 die 16c and the movable die 17c, and the third intermediate material 31 is shown in detail in FIG. Then, it is supplied to the second punching station 22.
[0010]
In the second punching station 22, as a fifth step, burrs 25a formed on the outer peripheral surface of the third intermediate material 31 are removed 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 to obtain a completed rocker arm 1. The rocker arm 1 is taken out from between the fixed die 16d and the movable die 17d of the second punching station 22 to a predetermined position by, for example, a take-out chuck (not shown). Although not described in Patent Literature 1, in the case of a rocker arm that is actually used, another processing machine is used to position the rocker arm at a position where it is aligned with each other at an intermediate portion of each side wall 2 (FIG. 22). Drilling is performed to form a pair of circular holes.
[0011]
When the rocker arm 1 is manufactured by a multi-stage cold forging machine as in the manufacturing method of the rocker arm described in Patent Document 1 configured as described above, the time required for the manufacturing operation can be reduced to some extent. The cost of the arm 1 can be easily reduced.
[0012]
[Patent Document 1]
JP-A-10-328778
[0013]
[Problems to be solved by the invention]
In the case of the rocker arm 1 described in Patent Document 1 described above, there is room for improving the performance of the engine incorporating the rocker arm in the following points (1) and (2).
{Circle around (1)} The through hole 29 formed by punching the first intermediate material 24 to provide the first and second connecting portions 3 and 4 is substantially centered in the width direction of the pair of side wall portions 2. Located in the department. Further, since the through hole 29 is formed by punching, the inner peripheral surface has a rough shear surface and a broken surface. For this reason, in a state where a roller is assembled to the rocker arm 1 to form a cam follower, there is a possibility that both end surfaces of the roller come into contact with the sheared surface and the fractured surface. When the both end surfaces of the roller and the sheared surface and the broken surface come into contact in this manner, it becomes difficult to rotate the roller smoothly, which hinders an improvement in the performance of the engine incorporating the rocker arm 1. Further, when both end surfaces of the roller come into contact with the sheared surface and the broken surface, the both end surfaces of the roller are abnormally worn, or the abrasion powder generated by the abrasion at the contact portion causes a gap between engine components. There is also a possibility that the engine may get into the engine and degrade the performance of the engine. In the case of the rocker arm 1 described in Patent Literature 1, there is room for improving the performance of an engine incorporating the rocker arm in such a point.
(2) There is still room for improvement in terms of weight reduction. That is, in the case of the rocker arm 1 described in Patent Literature 1, one side edge of each of the side walls 2 and 2 on one side of the first connecting portion 3 (the left side in FIG. 22A). The rising position P (the lower edge in FIG. 22) is near one edge in the length direction of the rocker arm 1 (the lower edge in FIG. 22). For this reason, the length of each of the side wall portions 2 and 2 is increased, and the volume of the rocker arm 1 is unnecessarily increased, which causes the rocker arm 1 to increase in weight. When the weight of the rocker arm 1 is increased in this manner, it causes a decrease in performance such as the output performance of an engine incorporating the rocker arm 1. In the case of the rocker arm 1 described in Patent Literature 1, there is still room for improving the performance of an engine incorporating the rocker arm in such a point.
In view of such circumstances, a rocker arm and a method of manufacturing the same according to the present invention provide a rocker arm obtained by subjecting a metal wire material to cold forging and improving the performance of an engine incorporating the rocker arm. It was invented well.
[0014]
[Means for Solving the Problems]
Each of the rocker arms of the present invention and the method of manufacturing the same is manufactured by performing cold forging on a material obtained by cutting a metal wire into a predetermined length, and is provided at an interval from each other. A pair of side walls, a first and a second connecting part connecting the both side wall parts near both ends in the longitudinal direction, and a pair of through-holes formed at positions where these side wall parts are aligned with each other. And a second engagement portion in which the first connection portion has a first engagement portion that engages with the valve body, and the second connection portion engages with the swing support member. A roller is supported at an intermediate portion of a support shaft that supports both ends of each through hole.
[0015]
In particular, in the rocker arm described in claim 1, all of the shear surface and the fracture surface formed on the inner surface of each of the side wall portions by the punching process for forming the first and second connection portions are described. Do not face both ends of the roller. In some cases, a chamfer is formed at a continuous portion between the both end surfaces and the outer peripheral surface of the roller. In this case, the “both end surfaces of the roller” described in claim 1 excludes this chamfer (see FIG. This is a part closer to the center than the inner periphery.
[0016]
Further, the rocker arm according to claim 4 is configured such that both side edges of the side walls located on one surface of the first and second connecting portions opposite to the first engaging portion are arranged in the longitudinal direction. In the length direction, from the portion of the first engagement portion where the center of the base end surface of the valve body is to be abutted, the distal end surface of the swing support member of the second engagement portion The center of the screw hole for screwing the part to be abutted or the male screw part provided on the swing support member.
[0017]
A method for manufacturing a rocker arm according to a second aspect is the method for manufacturing a rocker arm according to the first aspect, wherein the pair of side walls and a part of these side walls are connected to each other. By performing a punching process on the base portion of the intermediate material having the base portion, a punching step of forming the first and second connection portions is provided, and the punching process is performed inside the intermediate material to be subjected to the punching process. When it is assumed that the roller is disposed at a position corresponding to the position of the roller on the power rocker arm, the shape and dimensions of the intermediate material are regulated so that the roller does not interfere with the base.
[0018]
[Action]
According to the rocker arm of the present invention configured as described above and the rocker arm obtained by the method of manufacturing the same, the rocker arm is obtained by cold forging a metal wire material, and the rocker arm is incorporated. The engine performance can be improved.
That is, in the case of the rocker arm according to claim 1 obtained by the method of manufacturing a rocker arm according to claim 2, a shear surface and a fracture surface formed by punching an inner surface of each side wall portion; Contact with both end surfaces of the roller can be prevented. Therefore, the roller can be smoothly rotated by the rocker arm having the roller assembled. In addition, it is possible to prevent the occurrence of abnormal wear on both end surfaces of the roller, and to suppress the generation of wear powder due to the wear at the contact portion. Therefore, the performance such as the output performance of the engine incorporating the rocker arm can be improved. Further, in the step after the punching process, it is not necessary to perform a troublesome operation of smoothing the sheared surface and the fractured surface by pressing the surface.
Further, in the case of the rocker arm described in claim 3, since the volume of each side wall can be reduced, the weight of the entire rocker arm can be reduced. Therefore, the performance of the engine incorporating the rocker arm can be improved.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 21 show an example of an embodiment of the present invention. The feature of this example is a rocker arm 1a obtained by subjecting a metal wire material to cold forging. In order to improve the performance of an engine incorporating the rocker arm 1a, a second intermediate material 34b (FIG. 11) is used. To 15), the positional relationship between the shear surface and the fracture surface generated by punching out a part of the roller 35 and the roller 35, and the positions of the longitudinal ends of the pair of side walls 2 and 2, respectively, are regulated. is there. The manufacturing device of the rocker arm 1a is substantially the same as the manufacturing device shown in FIGS. 22 to 28, and thus the duplicated description will be omitted or simplified, and the following description will focus on the features of this example. .
[0020]
As shown in FIGS. 1 to 4, the rocker arm 1a according to the present embodiment has a pair of side walls 2a, 2a substantially parallel to each other and formed in a substantially triangular shape, and a longitudinal direction of the side walls 2a, 2a. It has a first connecting portion 3a and a second connecting portion 4a for connecting both end portions (up and down directions of 1, 2). Further, a pair of circular holes 5, 5 are formed concentrically with each other at the longitudinally intermediate portions of the side walls 2, 2, and a roller 35 engaging with a cam is formed in each of the circular holes 5, 5. Both ends of a support shaft (not shown) for rotatably supporting the intermediate portion are supported and fixed.
[0021]
Also, in order to abut the base end of the valve body, a first engagement portion, which is a first engagement portion, is provided on one surface (the right side surface in FIGS. 1 and 3 and the front side surface in FIG. 2) of the first connection portion 3a. A recess 36 is formed. Further, in order to abut the tip of the lash adjuster, a hemispherical second engaging portion, which is a second engaging portion, is provided on one surface (the right side surface in FIG. 1 and the front side surface in FIG. 2) of the second connecting portion 4a. Two concave portions 40 are formed. Note that, in the case of this example, an example is shown in which the tip of the lash adjuster is engaged as a swing support member with the second engagement portion, but a screw hole is formed in the second connection portion 4a, The present invention can be applied to a structure in which an adjusting screw is screwed into the screw hole.
[0022]
Further, in the case of this example, each of the side wall portions 2 and 2 located on the other surface (the left side surface in FIGS. 1 and 3 and the back side surface in FIG. 2) of the first and second connecting portions 3a and 4a. With respect to the longitudinal direction, the both ends of the longitudinal direction (the vertical direction in FIGS. 1 and 2) from the portion α of the first concave portion 36 to which the center of the distal end face of the valve body is to be abutted with respect to the longitudinal direction. The central portion of the tip end surface of the lash adjuster in the concave portion 40 is located between the portion β to be abutted. Further, as shown in FIG. 2, when the rocker arm 1a is viewed in the width direction of each of the side walls 2a, 2a, the shape of the outer peripheral edge of the rocker arm 1a is formed by a pair of both ends in the longitudinal direction of the rectangle. The trapezoid is made continuous, and a pair of linear portions 56a to 56g adjacent to each other are smoothly connected by curved portions 57a to 57h. The outer shape of the first and second connecting portions 3a and 4a when viewed in the thickness direction (the same direction as FIG. 2) includes a plurality of linear portions 56a, 56c to 56e, 56g, and 56h. It has a trapezoidal shape with rounded corners. As shown in FIG. 4, a bus bar is formed at the periphery of the opening end on the axial side (lower side in FIG. 4) of the circular hole 5 for supporting both ends of the support shaft, which is formed on each side wall 2a. Are straight, and form a chamfer 37 in the shape of a bowl.
[0023]
Further, in the case of the rocker arm 1a of the present example, by punching to form the first and second connecting portions 3a, 4a, the portions of the side walls 2a, 2a near one end in the width direction (FIG. 1). 4, a shear surface and a fracture surface are formed on the inner surface of the inner surface (the portion near the right end of FIG. 4). Then, all of the sheared surface and the fractured surface are not opposed to either of the both end surfaces of the roller 35 and the chamfer 52 (FIG. 2) formed at a continuous portion between the both end surfaces and the outer peripheral surface. However, since the chamfer 52 does not rub against the inner surfaces of the side walls 2a, 2a, the chamfer 52 may face the sheared surface and the fractured surface. In FIG. 1, the roller 35 is indicated by two concentric circles of two-dot chain lines. The outer circle of these concentric circles indicates the outer peripheral surface of the roller 35 (the outer peripheral edge of the chamfer 52), and the inner circle indicates the inner circle. 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, a portion (point Q) of the edge of the sheared surface and the broken surface on the roller 35 side (left side in FIG. 1) which is closest to one side in the width direction (right side in FIG. 1). ) Is one side in the width direction (FIG. 1) of a portion of one side (the right side surface in FIG. 1) of each of the first and second connecting portions 3 a, 4 a which is separated from the first and second concave portions 36 and 40. To the right).
[0024]
The rocker arm 1a of the present embodiment configured as described above is manufactured as shown in FIG. Next, a method of manufacturing the rocker arm 1a will be described in detail. First, the end of the metal wire wound in a coil shape around the rotation supporting device 8 is supplied 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 the case of this example, the cross section of the metal wire is circular. Further, this metal wire is previously immersed in a lubricating solution bath such as zinc phosphate to form a lubricating film layer such as a zinc phosphate film on the outer peripheral surface thereof. Then, as a first step, the metal wire is cut into a predetermined length by a cutting mechanism 12 (see FIG. 24) provided in the cold forging machine 10, thereby forming a columnar material as shown in FIG. (Blank) 32 is made. The cold forging machine 10 used for manufacturing the rocker arm in this example is substantially the same as that used in the conventionally known rocker arm manufacturing method shown in FIGS. It is. Therefore, 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 this example does not generate burrs in the manufacturing process of the rocker arm 1a, unlike the one shown in FIGS.
[0025]
The columnar material 32 obtained in the first step moves to the first forging station provided in the cold forging machine 10 without changing its direction. Then, as a second step, the raw material 32 is horizontally driven into a fixed die by a movable die, and the raw material 32 is subjected to a first cold forging (preliminary molding) to compress the raw material 32 in an axial direction. A first intermediate material 33 having a shape as shown in FIG. The first intermediate material 33 has a barrel-like shape whose diameter is maximum at the axially intermediate portion. That is, the diameter of the first intermediate material 33 becomes smaller toward the both ends in the axial direction from the maximum diameter portion 38 provided at the intermediate portion and having the largest diameter. The axially opposite end surfaces of the first intermediate material 33 are substantially flat surfaces. The position of the maximum diameter portion 38 in the axial direction is regulated in accordance with the position of the pair of side walls 2a, 2a, and is an intermediate portion in the axial direction, but not necessarily a central portion in the axial direction.
[0026]
After the first intermediate material 33 is formed, as shown in FIG. 8, the first intermediate material 33 is formed 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 the first intermediate material 33 by 90 degrees.
[0027]
Next, as a third step, the first intermediate material 33 is horizontally driven into the fixed die by the movable die of the second forging station, so that the first intermediate material 33 is disposed on both sides in the radial direction of the first intermediate material 33. A second cold forging (second preforming) for compressing the material 33 is performed. 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 walls 2a, 2a, and a base 39 that connects one end in the width direction of these side walls 2a, 2a {right end in FIGS. 9A and 10}. Is provided. The lengthwise intermediate portion of the base 39 is slightly protruded from the side opposite to the side walls 2a, 2a (the right side in FIGS. 9A and 10). In the case of the present example, the width direction of each of the side walls 2a and 2a constituting the second intermediate material 34a at a position corresponding to the maximum diameter portion 38 of the first intermediate material 33 (FIG. 9A) 10, the dimension in the left-right direction｝ is maximized. Since the lubricating film layer is previously formed on the outer peripheral surface of the first intermediate material 33 subjected to such second cold forging, the inner surfaces of the fixed and movable dies and the outer surface of the first intermediate material 33 are formed. And the friction acting between them can be kept small. And with this configuration, the molding workability and the shape accuracy of the second intermediate material 34a are improved. The second intermediate material 34a obtained in the third step is taken out from between the fixed mold and the movable mold and supplied to the third forging station.
[0028]
Next, as a fourth step, the second intermediate material 34a is horizontally driven into a movable mold 44 (FIG. 11A, FIG. 15) and a fixed mold 43 (FIG. 15) of the third forging station. Then, a third cold forging (final molding) is applied to the second intermediate material 34a, and the second intermediate material 34a has a shape and dimensions slightly closer to the finished product of the rocker arm 1a as shown in FIGS. The intermediate material 34b is made. The second intermediate material 34b has a lengthwise intermediate portion of the base 39 protruding largely to the side opposite to the side walls 2a, 2a. Also, one side of the base 39 (the right side in FIG. 11A, the front side in FIG. 11B) is formed by forming both ends in the longitudinal direction of the first and second concave portions 36 and 40 into a rough shape. And dimensions. In the third cold forging, the shapes and dimensions of the side walls 2a, 2a are adjusted to be substantially the same as the finished product.
[0029]
Further, in the case of this example, the first concave portion 36 for abutting the distal end portion of the valve body on both side surfaces of one longitudinal end portion (lower end portion in FIG. 11) of the base portion 39 in the width direction. 11 (a), the left and right directions in FIG. 11 (b), and the both ends deviated in the vertical direction の in FIG. 15 are used as the escape portions 41, 41 of the material when performing the third cold forging. The fixed mold 43 and the movable mold 44 are prevented from abutting on these escape portions 41, 41. With this configuration, it is possible to prevent an excessive load from being applied to the fixed mold 43 and the movable mold 44, and to improve the life of each of the molds 43 and 44. For this reason, the cost of the rocker arm 1a at the time of mass production can be reduced. Further, in the case of the present example, the relief portions 41 are located at the same position as the first concave portion 36 in the longitudinal direction of the base portion 39 and are provided near the first concave portion 36. For this reason, when forming the first concave portion 36, the escape of the excess portion is smoothly performed, and the first concave portion 36 can be easily processed into a predetermined shape and size with high accuracy.
[0030]
Further, the other end of the base portion 39 in the longitudinal direction (the upper end portion in FIG. 11) (the left side surface in FIG. 11A, the back side surface in FIG. 11B) pushes the tip end of the lash adjuster. A position opposite to the second concave portion 40 to be applied is a second escape portion 42 of a material when the third cold forging is performed. With this configuration, it is possible to more effectively prevent an excessive load from being applied to the fixed die 43 and the movable die 44. In addition, since the position of the base 39 opposite to the second recess 40 is defined as the second escape portion 42, the second recess 40 can be easily processed into a predetermined shape and size with high precision.
[0031]
Further, in the case of the present example, the second intermediate material 34b and the second intermediate material 34b are positioned inside the second intermediate material 34b at a position corresponding to the position of the roller 35 on the rocker arm 1a to be obtained (FIGS. 1-4). Even when it is assumed that the rocker arm 1a and the rocker arm 1a are combined via a support shaft (not shown), the shape and size of the second intermediate material 34b are regulated so that the roller 35 and the base 39 do not interfere with each other. Specifically, as shown in detail in FIG. 14, the middle part of the inner surface of the second intermediate material 34 b is connected to the inner peripheral edge of the smooth flat part 53, which is the inner surface of each side wall part 2 a, by the base part 39. And a cylindrical surface portion 54 that constitutes an intermediate portion of the inner surface of the solid-state imaging device. Then, assuming that the roller 35 is assembled inside the second intermediate material 34b as described above, the roller 35 interferes with any of the flat portion 53, the cylindrical surface portion 54, and the curved surface portion 55. The shape and dimensions of the inner surface of the second intermediate material 34b are regulated so as not to cause the problem. Also, both end surfaces of the roller 35 except for the chamfer 52 are located outside (the left side in FIG. 14) the deep end edge (point P in FIG. 14) of the flat portion 53 constituting the inner surface of each side wall 2a. I will do it. The second intermediate material 34b obtained in such a 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.
[0032]
Next, as a fifth step, which is a hole punching step performed in the first punching station, between the fixed mold and the movable mold, the second intermediate material 34b, except for the longitudinal direction intermediate portion of the base 39, of the second intermediate material 34b. The intermediate portion is punched by a punch for punching provided inside the fixed or movable die while holding the portion. Preferably, the punch for punching is inserted from the side between the side walls 2a, 2a, and the punched waste material (cutout material) is discharged to the side opposite to the side walls 2a, 2a. The reason for this is to prevent burrs generated during the punching process from facing the side where the roller 35 is arranged. Then, as shown in FIGS. 16 to 19, a third intermediate material 46 having a through hole 45 penetrating in the thickness direction formed at an intermediate portion thereof is manufactured by the punching process. In addition, the formation of the through hole 45 forms first and second connecting portions 3a and 4a for connecting both longitudinal end portions of the side walls 2a and 2a. Further, in the fifth step, simultaneously with the punching, one end in the width direction of each of the side walls 2a and 2a {the right end in FIGS. 16A and 17 and the front end in FIG. 16B}. Forging to adjust the shape and dimensions. In FIG. 17, together with the third intermediate material 46, a small piece (cutout material) 50 generated by punching the base 39 by the punching process is also shown.
[0033]
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 wall portions 2a, 2a (a portion near the right end in FIGS. 16 (a), 14 and 17 to 19). A shear surface and a fracture surface are formed on the inner peripheral surface of the portion that is continuous with the outer peripheral edge of the small piece 50 (the portion indicated by a satin finish in FIGS. 16 and 18 and the portion indicated by an arrow a in FIG. 19). . The third intermediate material 46 obtained in the fifth step is taken out from between the movable die and the fixed die of the first punching station and supplied to the fourth forging station.
[0034]
In the fourth forging station, as a sixth step, as shown in FIGS. 20 to 21, the third intermediate material 46 is driven horizontally by a movable die 48 into a fixed die 47, thereby forming the third intermediate material 46. A fourth intermediate material as shown in FIGS. 20 to 21 in which a fourth cold forging (sizing) is applied to 46 and the first and second concave portions 36 and 40 are precisely adjusted to predetermined shapes and dimensions. Build 49. In the case of such a fourth cold forging, similarly to the case of the third cold forging, on both sides of the first connecting portion 3a, the width direction from the first concave portion 36 shown in FIG. ), The left and right directions in FIG. 20B and the vertical direction｝ in FIG. 21 are used as the escape portions 41 of the material at the time of performing the fourth cold forging. The fixed mold 47 and the movable mold 48 are prevented from abutting on the parts 41, 41. With this configuration, the life of each of the dies 47 and 48 is improved, and the first concave portion 36 is easily processed into a predetermined shape and size with high accuracy.
[0035]
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 concave portion 40 is set to the fourth cold forging. Is used as the second escape portion 42 of the material. With this configuration, the life of each of the dies 47 and 48 is improved, and the second recess 40 is easily processed into a predetermined shape and size with high accuracy.
[0036]
In the fourth forging station, the step of horizontally driving the third intermediate material 46 into the fixed mold 47 by the movable mold 48 is repeated as necessary, so that the first and second concave portions are formed. At the same time as adjusting the shapes and dimensions of 36 and 40, adjustment of the parallelism of the side walls 2a and 2a, and adjustment of the space between the inner surfaces and the space between the outer surfaces of the side walls 2a and 2a are performed. You can do it. Further, when a burr occurs at one end in the width direction of each of the side walls 2a, 2a, the burr can be reduced or eliminated by slightly pressing the surface. 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 placed in the second forging station. Supply to the punching station.
[0037]
In the second punching station, as a seventh step, a second punching process is performed on a part of each of the side walls 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, the second punching is performed inside the cold forging machine 10. As one of the methods for this, when supplying the fourth intermediate material 49 from the fourth forging station to the second punching station, the leading end surfaces of the fixed and movable dies of the second punching station and the 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 considered. Then, the fourth intermediate material 49 is sandwiched between the fixed die and the movable die of the second punching station, and each of the circular holes is formed by a punch for punching provided inside the fixed die or the movable die. 5 and 5 are formed. As another method, the fourth intermediate material 49 is supplied from the fourth forging station to the second punching station as it is without changing the direction, and each movable mold 44 of the first to fourth forging stations is supplied. , 48 for reciprocating movement of the drive mechanism (slide mechanism) is converted into a direction different from the reciprocating movement direction by 90 degrees by cam dies provided on both sides, and the above-mentioned hole is punched by the punch for punching attached to the cam type. There is also a method of forming the respective circular holes 5,5. Further, in the case of the present example, a chamfer 37 (FIG. 4) is formed by forging at the same time as the drilling of each of the circular holes 5 at the peripheral edge of the opening end on the outside in the axial direction of each of the circular holes 5. The finished product of the rocker arm 1a thus obtained is taken out from the second punching station to a predetermined position by a takeout chuck.
[0038]
In the case of the method of manufacturing the rocker arm according to the present embodiment configured as described above, the first and second connecting portions 3a and 4a are formed on the inner surfaces of the side walls 2a and 2a by punching. The rocker arm 1a in which all of the shear surface and the fracture surface do not face both end surfaces of the roller 35 can be manufactured. According to the rocker arm 1a obtained in this manner, it is possible to prevent the sheared surface and the broken surface from coming into contact with both end surfaces of the roller 35. Therefore, the roller 35 can be smoothly rotated by the rocker arm 1a on which the roller 35 is assembled. In addition, it is possible to prevent occurrence of abnormal wear on both end surfaces of the roller 35 and to suppress generation of wear powder due to wear at the contact portion. Therefore, the performance such as the output performance of the engine incorporating the rocker arm 1a of the present embodiment can be improved. Further, in the step after the punching, it is not necessary to perform a troublesome operation of smoothing the sheared surface by pressing the surface.
[0039]
In the case of the rocker arm of the present embodiment, each of the side wall portions 2 located on the other surface (the left side surface in FIGS. 1 and 3 and the back side surface in FIG. 2) of the first and second connecting portions 3a and 4a. The lengthwise end edges of the lash adjuster of the second recess 40 from the portion α of the first recess 36 to which the center of the distal end face of the valve body should be abutted with respect to this length direction. The center of the tip surface is located between the part β to be abutted. For this reason, the lengthwise dimension of each of the side walls 2a, 2a can be shortened, the volume of each of the side walls 2a, 2a can be reduced, and the entire rocker arm 1a can be reduced in weight. Therefore, the performance of the engine incorporating the rocker arm 1a can be further improved. Further, in the case of the present example, the outer shape when the first and second connecting portions 3a and 4a are viewed in the thickness direction is provided with a plurality of linear portions 56a, 56c to 56e, 56f and 56g. It has a trapezoidal shape. For this reason, compared with the case where the outer shape is a circular arc shape in which the middle portion of each of the straight portions 56a, 56c to 56e, 56f, and 56g is expanded outward, the first and second connecting portions 3a are used. 4a, the volume of the rocker arm 1a can be made lighter.
[0040]
Unlike the rocker arm of the present embodiment, instead of not forming the second concave portion 40 in the second connecting portion 4a, a screw hole is formed in the second connecting portion 4a, and the adjusting hole is formed in the screw hole portion. The present invention according to claim 3 can be applied to a structure in which a screw is screwed. In this case, for example, the lengthwise end edges of the side walls 2a, 2a located on one surface of the first and second connecting portions 3a, 4a opposite to the first concave portion 36 are separated by this length. In the vertical direction, the first concave portion 36 is located between a portion to which the center of the base end face of the valve body is to be abutted and the center of the screw hole. Also in the case of such a structure, the volume of each of the side walls 2a, 2a can be reduced similarly to the case of this example, so that the weight of the entire rocker arm can be reduced.
[0041]
Further, in the case of the present example, the circular holes 5, 5 provided in the side walls 2a, 2a are formed by punching, but in the present invention, these circular holes 5, 5 are formed by the punching. Alternatively, it can be formed by shaving or cutting. However, when the cutting process is used, the cost of the rocker arm 1a increases. For this reason, from the viewpoint of reducing the cost of the rocker arm 1a, it is preferable that each of the circular holes 5, 5 is formed by a punching process or a shaving process. More preferably, each of the circular holes 5, 5 is formed by the punching process. The circular holes 5, 5 are formed. Further, the intermediate material taken out from the cold forging machine 10 can be conveyed to another press machine, and the above-mentioned circular holes 5, 5 can be punched by the other press machine.
[0042]
Further, in the case of this example, a lubricating film layer such as a zinc phosphate film is formed on the metal wire in advance. However, 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, the material 32 and the first to fourth intermediate materials 33, Friction between the outer surfaces of the molds 34a, 34b, 46, and 49 and the inner surface of the mold can be suppressed.
[0043]
Further, in the case of this example, the second intermediate material is formed in order to manufacture the rocker arm 1a in which all of the sheared surface and the broken surface formed on the inner surface of each of the side walls 2a, 2a do not face both end surfaces of the roller 35. As a fourth step of performing the third cold forging on the first intermediate material 34a to produce the second intermediate material 34b (FIGS. 11 to 15), the arrangement of the roller 35 on the rocker arm 1a to be obtained inside the second intermediate material 34b Even when it is assumed that the roller 35 is disposed at a position corresponding to the position, the shape and size of the second intermediate material 34b are regulated so that the roller 35 and the base 39 do not interfere with each other. However, as described above, the manufacturing method for obtaining the rocker arm 1a in which all of the shear surface and the fracture surface formed on the inner surface of each of the side wall portions 2a and 2a do not face both end surfaces of the roller 35 is described in the present example. It is not limited to the method. For example, as a first example of another manufacturing method for obtaining the rocker arm 1a, a fifth process of punching the base 39 of the second intermediate material 34b to form the third intermediate material 46 (FIGS. 16 to 19). After this, as shown in FIG. 29, this punching process causes a shear surface and a fracture surface (portion indicated by a in FIG. 29) on the inner surface at one widthwise end (right end in FIG. 29) of each of the side walls 2a and 2a. The formed portion may be subjected to cold forging to bend toward the side of each of the side walls 2a, 2a (vertical direction in FIG. 29) as indicated by arrows in the same figure.
[0044]
As a second example of another manufacturing method for obtaining the rocker arm 1a, FIG. 30 shows a fifth process of punching the base portion 39 of the second intermediate material 34b to form the third intermediate material 46, As shown in the drawing, a portion in which a shear surface and a fracture surface (portion indicated by a in FIG. 30) are formed on the inner surface at one widthwise end portion (right end portion in FIG. 30) of each of the side wall portions 2a and 2a by the punching process. Cold forging for plastically deforming by burring or the like can also be performed so as to face in the width direction (the left-right direction in FIG. 30) of each of the side walls 2a, 2a as indicated by arrows in FIG. According to such a method of manufacturing the rocker arm shown in FIGS. 29 and 30, the roller with the rocker arm 1a to be obtained is obtained inside the second intermediate material 34b to be punched, obtained in the fourth step. When it is assumed that the roller 35 is arranged at a position corresponding to the arrangement position of the roller 35, even if the roller 35 and the base 39 interfere with each other, all of the shear surface and the fracture surface face the both end surfaces of the roller 35. No, the rocker arm 1a can be made.
[0045]
【The invention's effect】
Since the present invention is configured and operates as described above, the performance of the engine incorporating the rocker arm can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view partially illustrating a completed product of a rocker arm according to an embodiment of the present invention;
FIG. 2 is a view seen from the right side of FIG. 1;
FIG. 3 is a sectional view taken along line AA of FIG. 1;
FIG. 4 is a sectional view taken along the line BB in FIG.
FIG. 5 is a flowchart showing a method for manufacturing a rocker arm.
FIGS. 6A and 6B show a material obtained by a first step of the manufacturing method, wherein FIG. 6A is a front view and FIG.
7A and 7B show a first intermediate material obtained in a second step, wherein FIG. 7A is a front view, and FIG. 7B is a cross-sectional view taken along the line CC of FIG.
FIG. 8 is a view showing a state in which the direction 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.
9A and 9B show a second intermediate material obtained in the third step, wherein FIG. 9A is a cross-sectional view and FIG. 9B is a view as seen from the right side of FIG.
FIG. 10 is a sectional view taken along line DD in FIG.
11A and 11B show a second intermediate material obtained by a fourth step, wherein FIG. 11A is a cross-sectional view, and FIG. 11B is a view seen from the right side of FIG.
FIG. 12 is a sectional view taken along line EE of FIG.
FIG. 13 is a partially enlarged view of FIG.
FIG. 14 is an enlarged sectional view of a portion F in FIG. 12;
FIG. 15 is a view showing a state in the middle of the forging operation in the fourth step, taken along the line GG in FIG. 11A.
16A and 16B show a third intermediate material obtained by the fifth step, wherein FIG. 16A is a cross-sectional view, and FIG. 16B is a view as seen from the right side of FIG.
FIG. 17 is a diagram showing the third intermediate material and small pieces generated during the punching process in the fifth step, taken along the line HH in FIG. 16 (a).
FIG. 18 is a partially enlarged sectional view of FIG.
FIG. 19 is an enlarged sectional view of a portion I in FIG. 17;
FIGS. 20A and 20B show a fourth intermediate material obtained by the sixth step, wherein FIG. 20A is a cross-sectional view and FIG. 20B is a view seen from the right side of FIG.
FIG. 21 is a view 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 method of manufacturing a rocker arm, wherein FIG. 22A is a front view, and FIG. 22B is a diagram viewed from the left side of FIG.
FIG. 23 is a schematic perspective view showing a state where 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.
FIG. 25 is a partially enlarged sectional view of FIG. 24 showing a first forging station of the cold forging machine;
FIG. 26 is a partially enlarged sectional view of FIG. 24 showing the first punching station.
FIG. 27 is a partially enlarged 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.
FIG. 29 is a diagram showing a first example of another manufacturing method for obtaining a rocker arm whose shear surface and fracture surface do not face the both end surfaces of the roller, taken along the line HH in FIG. 16;
FIG. 30 is a view showing the second example in a section taken along line HH in FIG. 16;
[Explanation of symbols]
1, 1a rocker arm
2, 2a Side wall
3, 3a First connection part
4, 4a Second connection part
5 circular holes
6 First engaging part
7 Second engaging part
8 Rotation support device
9 Metal wires
10 Cold forging machine
11 Roller type wire rod feeding mechanism
12 Cutting mechanism
13 materials
14 die block
15 ram
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 Burr
26 through hole
27 Extruded member
28 Punch for drilling
29 through hole
30 Second intermediate material
31 Third intermediate material
32 materials
33 First intermediate material
34a, 34b Second intermediate material
35 rollers
36 First recess
37 chamfer
38 Maximum diameter part
39 base
40 Second recess
41 Escape
42 Second escape
43 fixed type
44 Movable type
45 through hole
46 Third intermediate material
47 fixed type
48 Movable type
49 Fourth intermediate material
50 pieces
51 base
52 chamfer
53 flat part
54 Cylindrical surface
55 Curved surface
56a to 56g Straight section
57a-57h Curved section

Claims

A pair of side walls, which are produced by subjecting a material obtained by cutting a metal wire to a predetermined length to cold forging and provided at intervals from each other, and both ends in the longitudinal direction of these side walls First and second connecting portions for connecting the deviating portions to each other, and a pair of through-holes formed at positions where these side walls are aligned with each other, and the first connecting portion is engaged with the valve body. A support having a first engagement portion, wherein the second connecting portion has a second engagement portion which engages with the swing support member, and a support for supporting both ends in each of the through holes. A rocker arm for supporting a roller at an intermediate portion of a shaft, wherein all of a shear surface and a fracture surface formed on an inner surface of each of the side wall portions by a punching process for forming the first and second connecting portions. Rocker arm that does not face both end faces of the roller.

2. A method for manufacturing a rocker arm according to claim 1, wherein the base material is punched out of an intermediate material having a pair of side walls and a base connecting a part of these side walls. Accordingly, a punching step for forming the first and second connecting portions is provided, and the roller is located at a position corresponding to the position of the roller on the rocker arm to be obtained inside the intermediate material to be subjected to the punching process. And a method of manufacturing a rocker arm that regulates the shape and dimensions of the intermediate material so that the roller does not interfere with the base when the base is arranged.

A pair of side walls, which are produced by subjecting a material obtained by cutting a metal wire to a predetermined length to cold forging and provided at intervals from each other, and both ends in the longitudinal direction of these side walls First and second connecting portions for connecting the deviating portions to each other, and a pair of through-holes formed at positions where these side walls are aligned with each other, and the first connecting portion is engaged with the valve body. A support having a first engagement portion, wherein the second connecting portion has a second engagement portion which engages with the swing support member, and a support for supporting both ends in each of the through holes. A rocker arm that supports a roller at an intermediate portion of a shaft, and a length direction of each of the side wall portions located on one surface of each of the first and second coupling portions on the opposite side to the first engagement portion. A portion of the first engagement portion to which the center of the base end face of the valve body is to be abutted with respect to the longitudinal direction. A portion of the second engaging portion to which the center of the tip end surface of the swing support member is to be abutted or a center of a screw hole for screwing a male screw portion provided in the swing support member. Rocker arm located between.