JP4655390B2

JP4655390B2 - Manufacturing method of annular material for bearing race

Info

Publication number: JP4655390B2
Application number: JP2001072115A
Authority: JP
Inventors: 学黒田
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 2000-07-04
Filing date: 2001-03-14
Publication date: 2011-03-23
Anticipated expiration: 2021-03-14
Also published as: JP2002079347A

Description

【０００１】
【産業上の利用分野】
この発明は、軸受軌道輪（内外輪）用の環状素材の製造方法に関し、特に、内輪外径と外輪内径との寸法差が大きい例えば深溝球軸受の軌道輪に用いられる環状素材の製造方法に関する。
【０００２】
【従来の技術】
図７は従来の深溝球軸受の製造工程における、軌道輪用環状素材の製造方法の一例を示す工程図である。この製造方法においては、まず、熱間鍛造によって軸受鋼等からなる棒材から環状の円筒素材１０１を形成する（図７ａ参照）。次に、この円筒素材１０１に焼鈍及びショトピーニングを施した後、幅研磨（図７ｂ参照）、外径研磨（図７ｃ参照）、及び内径旋削（図７ｄ参照）をこの順に施し、さらに内外周のコーナ部に旋削にて面取加工を施す（図７ｅ参照）。
【０００３】
次いで、前記円筒素材１０１の両面に、旋削にて輪抜き用のステッキ溝１０２を形成して、中央の連結部１０３を介して互いに連結された外輪用の大径円筒部１０４と内輪用の小径円筒部１０５とをそれぞれ形成するとともに、前記ステッキ溝１０２の開口縁に糸面取りを施す（図７ｆ参照）。その後、プレスにて前記連結部１０３を打ち抜いて、大径円筒部１０４と小径円筒部１０５とを互いに分離することにより、外輪用環状素材１０６及び内輪用環状素材１０７を得る（図７ｇ参照）。
【０００４】
【発明が解決しようとする課題】
前記従来の環状素材の製造方法においては、外輪用環状素材１０６の内径と内輪用環状素材１０７の外径との差に対応させて、両円筒部１０４，１０５の相互間に、両者を繋ぐための繋ぎ部１０８を設けておく必要があり、この繋ぎ部１０８は切粉及び抜きかすとして廃棄されることから、材料歩留まりが悪く、その分、製造コストが高く付くという問題があった。また、前記ステッキ溝１０２を形成するためのバイトの寿命が短いので、その加工効率が悪く生産性が低いという問題もあった。
この発明は前記問題点に鑑みてなされたものであり、材料歩留まり及び生産性を高めることができる軸受軌道輪用の環状素材の製造方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
前記目的を達成するためのこの発明の軸受軌道輪用の環状素材の製造方法は、軸受の外輪用環状素材と内輪用環状素材とを製造する方法であって、鍛造によって鋼製の棒材から外輪用の大径円筒部と内輪用の小径円筒部とを、前記大径円筒部の軸方向の一端部内周と前記小径円筒部の軸方向の他端部外周とを軸方向に重ね合わせて互いに連結した状態で形成する工程と、前記小径円筒部を大径円筒部の内部に押し込むと同時に、両円筒部の連結部をその一部を残してせん断する工程と、前記連結部の一部を介して互いに連結された状態で前記大径円筒部とその内部に押し込まれている小径円筒部のそれぞれの端面を同時に研磨する工程と、
前記連結部の一部を介して互いに連結された両円筒部を軸方向に相対的に移動させて互いに分離する工程と、大径円筒部を冷間ローリング加工にて拡径する工程とをこの順に含み、前記鍛造によって形成された小径円筒部の内径、外径及び幅の各寸法が、前記内輪用環状素材の各寸法に対して、それぞれ所定の取りしろを有する値に設定されており、前記大径円筒部の内径が、小径円筒部の外径に近似する寸法に設定され、その幅寸法が小径円筒部の幅と同じ寸法に設定されていることを特徴としている。
【０００６】
この軸受軌道輪用の環状素材の製造方法によれば、両円筒部の連結部を、その一部を残してせん断するので、両円筒部を当該一部で連結した状態で幅研磨することができる。このため、両円筒部の端面の同時研磨を支障なく行うことができる。また、両円筒部を前記一部で連結した状態で、両円筒部を軸方向に相対的に移動させて互いに分離するので、従来のステッキ溝を形成することなく両者を分離させることができる。しかも、両円筒部を分離した後に大径円筒部を冷間ローリング加工にて拡径するので、両円筒部を分離する前において大径円筒部の内径を小径円筒部の外径に近似させておくことができる。このため、両円筒部を繋ぐための従来の繋ぎ部を形成する必要がない。
【０００７】
前記軸受軌道輪用の環状素材の製造方法においては、前記大径円筒部と小径円筒部とを形成する工程と、両円筒部の連結部をその一部を残してせん断する工程との間に、連結部の軸方向幅を減少させる工程を含んでいるのが好ましい（請求項２）。この場合には、前記連結部の軸方向幅を予め小さくしておくことができるので、前記小径円筒部を大径円筒部の内部に少ない荷重で容易に押し込むことができる。このため、小径円筒部を大径円筒部の内部に押し込む際に、大径円筒部の連結部側の端面が当該連結部に引っ張られて凹入変形するのを抑制することができる。
前記軸受軌道輪用の環状素材の製造方法においては、前記冷間ローリング加工によって、大径円筒部のコーナ部を面取りするのが好ましく（請求項３）、これにより、従来の旋削による面取り工程を省略することができる。
また、前記軸受軌道輪用の環状素材の製造方法においては、前記鍛造行程において前記小径円筒部を有底筒状に成形し、前記小径円筒部を大径円筒部の内部に押し込むと同時に、前記小径円筒部の底部の穴明け加工を行ってもよい。
【０００８】
【発明の実施の形態】
以下、この発明の実施の形態について、添付図面を参照しながら詳細に説明する。
図１は、この発明の一実施形態に係る軸受軌道輪用の環状素材の製造方法を示す工程図である。この製造方法は、深溝玉軸受の内輪用環状素材Ａ及び外輪用環状素材Ｂの製造に適用されるものであり、まず、軸受鋼等の鋼からなる棒材に熱間鍛造を施して、互いに連結された外輪用の大径円筒部１と内輪用の小径円筒部２とを形成する（図１ａ参照）。前記大径円筒部１の内周端部と小径円筒部２の外周端部とは、軸方向において重ね合わせた状態で互いに連結されている。また、これら両円筒部１，２は、例えば多段フォーマを使用することにより、高速且つ連続的に一体成形することができる。
【０００９】
前記小径円筒部２の外径、内径及び幅の各寸法は、最終的に得られる内輪用環状素材Ａの各寸法に対して、所定の取りしろを有する値に設定されている。また、大径円筒部１の内径は、小径円筒部２の外径に近似する寸法に設定されており、その幅は最終的に得られる外輪用環状素材Ｂの幅に対して、所定の取りしろを有する値、つまり小径円筒部２の幅と同じ寸法に設定されている。したがって、この大径円筒部１は外輪用環状素材Ｂに対して内外径が小さくなっており、その分、肉厚が厚くなっている。なお、両円筒部１，２の重ね合わせた部分（連結部）Ｊの軸方向幅Ｄは、大径円筒部１及び小径円筒部２のサイズに応じて２〜５ｍｍ程度に設定される。
【００１０】
次に、前記小径円筒部２の図において左側の端面をプレスによって軸方向へ押圧して、当該小径円筒部２を大径円筒部１の内部に押し込む（図１ｂ参照）。これにより、両円筒部１，２の連結部Ｊに軸方向へのせん断力が作用するが、この連結部Ｊはその一部を残した状態でせん断する。すなわち、小径円筒部２の軸方向への移動に伴って、連結部Ｊが塑性変形とせん断とを生じながら図において右側に向かって移動し、小径円筒部２が大径円筒部１に対して完全に重なった状態で、前記連結部Ｊにせん断が生じない部分が残存し、このせん断が生じない部分を介して大径円筒部１と小径円筒部２とが互いに連結されている。なお、両円筒部１，２を多段フォーマによって成形する場合には、前記小径円筒部２を大径円筒部１の内部に押し込む工程を、当該多段フォーマで一連に行ってもよい。
【００１１】
次いで、前記大径円筒部１及び小径円筒部２のそれぞれの両端面を、平面研削盤を用いてそれぞれ同時に研磨して、その幅寸法を整える（図１ｃ参照）。この際、両円筒部１，２が互いに連結されており、両者が相対的に遊動するのを阻止した状態で研磨することができるので、当該研磨を支障なく行うことができる。このように、大径円筒部１及び小径円筒部２のそれぞれの端面を同時に研磨することにより、これらを別々に研磨する場合よりも、研磨工数を削減することができる。なお、前記平面研削盤としては、対向させた一対の砥石車の間に回転ホルダを用いて大径円筒部１及び小径円筒部２を通過させるガードナー形のものを用いる。
【００１２】
両円筒部１，２の端面の研磨が終了すると、大径円筒部１の内部に小径円筒部２を保持したまま、大径円筒部１の外周をセンタレス研削盤を用いて研磨して、その外径寸法を整える（図１ｄ参照）。その後、小径円筒部２の内周を旋削して、その内径寸法を整える（図１ｅ参照）。これらの工程においても両円筒部１，２が互いに連結されており、両者が相対的に遊動するのが阻止されているので、その加工を支障なく行うことができる。
【００１３】
小径円筒部２の内周旋削が完了すると、プレスを用いて小径円筒部２の端面を押圧し、両円筒部１，２を軸方向に相対的に移動させて互いに分離させる（図１ｆ参照）。次いで、大径円筒部１の内周及び小径円筒部２の外周をそれぞれ旋削して、その寸法を整える（図１ｇ参照）。
その後、大径円筒部１に冷間ローリング加工を施して、その内外径を所定寸法に拡径する（図１ｉ参照）。この冷間ローリングは、例えば成形ロール２１とマンドレル２２との間で大径円筒部１を挟み込んで圧延することにより、その肉厚を減少させて内外径を拡径するものである（図２及び図３参照）。この冷間ローリングにおいては、大径円筒部１の外径寸法をセンサにより検知して、当該外径寸法が所定範囲になるようにその圧延量を制御する。そして、冷間ローリングが完了した後、必要により大径円筒部１にサイジングを施して、その外径寸法を整える。
また、前記冷間ローリングにおいて、大径円筒部１の内外周のコーナ部１ａも同時に塑性変形させて面取りする。このように内外径を拡径すると同時にコーナ部１ａを面取りすることにより、別途旋削により面取りを行う工程を省略することができる。一方、小径円筒部２については、旋削によって各コーナ部を面取りする（図１ｈ参照）。
以上により、内輪用環状素材Ａ及び外輪用環状素材Ｂを得ることができ、これら環状素材Ａ，Ｂは、旋削にてそれぞれ軌道が形成されるとともに、必要に応じて旋削にてシール溝が形成される。
【００１４】
以上の製造方法においては、従来のステッキ溝を形成することなく両円筒部１，２どうしを分離させることができるので、加工効率の悪い当該ステッキ溝を形成するための切削工程を省略することができ、その分、生産性を高めることができる。しかも、両円筒部１，２を分離する前の大径円筒部１の内径を、小径円筒部２の外径に近似させておくことができるので、両円筒部１，２部を繋ぐための従来の繋ぎ部を形成する必要がない。このため、材料歩留まりを高めることができる。具体的には、型番６２０３において、材料歩留まりを従来の製法に比べて約２０％高めることができる。
【００１５】
前記実施の形態においては、小径円筒部２を大径円筒部１の内部に押し込む前に、連結部Ｊの左端部に旋削にて切り欠き３を形成しておいてもよく（図４参照）、この場合には、この切り欠き３に応力集中が生じるので、小径円筒部２を大径円筒部１の内部に少ない荷重で容易に押し込むことができる。
また、前記冷間ローリング工程において、大径円筒部１を拡径すると同時にその内周に軌道を成形してもよく、この場合には、旋削にて軌道を形成する場合よりも材料歩留まりをさらに高めることができる。
【００１６】
図５は他の実施の形態を示す工程図である。この実施の形態が図１に示す実施の形態と異なる点は、図１に示す実施の形態においては、大径円筒部１と小径円筒部２とを形成した段階で、小径円筒部２の穴明け加工が完了しているのに対して（図１ａ参照）、図５に示す実施の形態においては、小径円筒部２を有底筒状に形成して、当該小径円筒部２を大径円筒部１の内部に押し込む工程が完了した後に、その穴明け加工を行うようにしている点である。
この実施の形態においては、前記穴明け加工までの一連の工程を多段フォーマを用いて熱間鍛造で行っている。すなわち、前記多段フォーマの第１工程として棒材を据え込み鍛造した後（図５ａ参照）、第２工程として連結部Ｊを介して互いに連結された大径円筒部１と小径円筒部２とを成形する（図５ｂ参照）。この際、前記小径円筒部２は有底筒状に成形する。次いで、第３工程として前記小径円筒部２の図において左側の端面を軸方向へ押圧して、当該小径円筒部２を大径円筒部１の内部に押し込んだ後（図５ｃ参照）、第４工程として小径円筒部２の穴明けを行う（図５ｄ参照）。以後の工程は図１ｃ〜図ｉに示す工程と同様である。
【００１７】
図６はさらに他の実施の形態を示す工程図である。この実施の形態が図１に示す実施の形態と異なる点は、図１に示す実施の形態においては、大径円筒部１と小径円筒部２とを形成した段階で、小径円筒部２の穴明け加工が完了しているのに対して、図６に示す実施の形態においては、小径円筒部２を有底筒状に形成して、当該小径円筒部２を大径円筒部１の内部に押し込む工程と同時に、その穴明け加工を行うようにしている点、及び図１に示す実施の形態における大径円筒部１と小径円筒部２とを形成する工程（図１ａ参照）と、両円筒部１，２の連結部Ｊをその一部を残してせん断する工程（図１ｂ参照）との間に、前記小径円筒部２を大径円筒部１からさらに突出させて前記連結部Ｊの軸方向幅Ｄを減少させる工程を行っている点である。
【００１８】
この実施の形態においても、前記穴明け加工までの一連の工程を多段フォーマを用いて熱間鍛造で行っている。すなわち、前記多段フォーマの第１工程として棒材を据え込み鍛造した後（図６ａ参照）、第２工程として連結部Ｊを介して互いに連結された大径円筒部１と小径円筒部２とを成形する（図６ｂ参照）。この際、前記連結部Ｊの軸方向幅Ｄは、図１ａに示す連結部Ｊの軸方向幅Ｄと等しいか、これよりも大きくなるように設定している。また、前記小径円筒部２は有底筒状に成形する。次いで、第３工程として前記小径円筒部２の図において右側の端面を軸方向へ押圧して、当該小径円筒部２を大径円筒部１からさらに突出させると同時に、前記連結部Ｊの軸方向幅Ｄを減少させて、その最終的な軸方向幅Ｅを図１ａに示す連結部Ｊの軸方向幅Ｄよりも小さくする（図６ｃ参照）。その後、第４工程として前記小径円筒部２の図において左側の端面を軸方向へ押圧して、当該小径円筒部２を大径円筒部１の内部に押し込むと同時に、小径円筒部２の穴明けを行う（図６ｄ参照）。以後の工程は図１ｃ〜図ｉに示す工程と同様である。
【００１９】
この実施の形態においては、連結部Ｊの最終的な軸方向幅Ｅが、図１に示す連結部Ｊの軸方向幅Ｄよりも小さくなっているので、小径円筒部２を大径円筒部１の内部に少ない荷重で容易に押し込むことができる。このため、小径円筒部２を大径円筒部１の内部に押し込む際に、大径円筒部１の連結部Ｊ側の端面が当該連結部Ｊに引っ張られて他面側へ凹入変形するいわゆる端面ダレが生じるのを抑制することができる。このため、大径円筒部１の寸法精度を高めることができ、その端面の取りしろが不足していわゆる黒皮残り等の製品不良が発生するのを防止することができる。
また、前記第２工程において連結部Ｊの軸方向幅Ｄを、第３工程完了後の軸方向幅Ｅと等しくなるように一気に成形すると、その変形抵抗により成形型の負担が大きくなって、当該成形型の寿命が短くなるが、この実施の形態では２工程に分けて連結部Ｊの軸方向の幅出しを行っているので、成形型の寿命を確保することができる。
なお、この発明の軸受軌道輪用の環状素材の製造方法は、前記した深溝玉軸受用の環状素材の他、ローラ軸受用の環状素材等、他の転がり軸受用の環状素材の製造方法にも適用して実施することができる。
【００２０】
【発明の効果】
以上のように、請求項１記載の軸受軌道輪用の環状素材の製造方法によれば、従来の輪抜き用のステッキ溝を形成することなく両円筒部を互いに分離することができるので、加工効率の悪い当該ステッキ溝を形成するための切削工程を省略することができ、その生産性を高めることができる。しかも、両円筒部を繋ぐための従来の繋ぎ部を形成する必要がないので、その材料歩留まりを高めることができる。したがって、軸受軌道輪用の環状素材の製造コストを安くすることができる。
【００２１】
請求項２記載の軸受軌道輪用の環状素材の製造方法によれば、連結部の軸方向幅を小さくして小径円筒部を大径円筒部の内部に少ない荷重で容易に押し込めるようにしているので、小径円筒部を大径円筒部の内部に押し込む際に、大径円筒部の連結部側の端面が当該連結部に引っ張られて凹入変形するのを抑制することができる。このため、大径円筒部の寸法精度を高めることができ、その端面の取りしろが不足することにより製品不良が発生するのを防止することができる。
請求項３記載の軸受軌道輪用の環状素材の製造方法によれば、面取りのための旋削工程を省略することができるので、生産性をさらに高めることができる。
【図面の簡単な説明】
【図１】この発明の軸受軌道輪用の環状素材の製造方法を示す工程図である。
【図２】冷間ローリング工程の詳細を示す断面図である。
【図３】前図の平面図である。
【図４】他の実施の形態を示す断面図である。
【図５】さらに他の実施の形態を示す工程図である。
【図６】さらに他の実施の形態を示す工程図である。
【図７】従来例を示す工程図である。
【符号の説明】
１大径円筒部
１ａコーナ部
２小径円筒部
Ａ内輪用環状素材
Ｂ外輪用環状素材
Ｊ連結部[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing an annular material for a bearing race (inner and outer rings), and more particularly, to a method for producing an annular material used for a raceway of a deep groove ball bearing, for example, in which a dimensional difference between an inner ring outer diameter and an outer ring inner diameter is large. .
[0002]
[Prior art]
FIG. 7 is a process diagram showing an example of a method for manufacturing a ring-shaped ring ring material in a conventional deep groove ball bearing manufacturing process. In this manufacturing method, first, an annular cylindrical material 101 is formed from a rod made of bearing steel or the like by hot forging (see FIG. 7a). Next, after annealing and shot peening the cylindrical material 101, width polishing (refer to FIG. 7b), outer diameter polishing (refer to FIG. 7c), and inner diameter turning (refer to FIG. 7d) are performed in this order. A chamfering process is performed on the corner portion by turning (see FIG. 7e).
[0003]
Next, a stick groove 102 for removing a wheel is formed on both surfaces of the cylindrical material 101 by turning, and a large diameter cylindrical portion 104 for an outer ring and a small diameter for an inner ring are connected to each other via a central connecting portion 103. Each of the cylindrical portions 105 is formed, and a thread chamfer is applied to the opening edge of the stick groove 102 (see FIG. 7f). Thereafter, the connecting portion 103 is punched out by a press, and the large-diameter cylindrical portion 104 and the small-diameter cylindrical portion 105 are separated from each other, thereby obtaining an outer ring annular material 106 and an inner ring annular material 107 (see FIG. 7g).
[0004]
[Problems to be solved by the invention]
In the conventional manufacturing method of the annular material, the cylindrical portions 104 and 105 are connected to each other in accordance with the difference between the inner diameter of the outer ring annular material 106 and the outer diameter of the inner ring annular material 107. The connecting portion 108 is required to be provided, and the connecting portion 108 is discarded as chips and chips. Therefore, there is a problem in that the material yield is low and the manufacturing cost is increased accordingly. In addition, since the tool for forming the stick groove 102 has a short life, there is a problem that its processing efficiency is low and productivity is low.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing an annular material for a bearing race that can improve material yield and productivity.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a method for producing an annular material for a bearing race of the present invention is a method for producing an annular material for an outer ring and an annular material for an inner ring of a bearing, and forging from a steel bar by forging. A large-diameter cylindrical portion for the outer ring and a small-diameter cylindrical portion for the inner ring are overlapped in the axial direction with the inner periphery of one end portion in the axial direction of the large-diameter cylindrical portion and the outer periphery of the other end portion in the axial direction of the small-diameter cylindrical portion. Forming in a state of being connected to each other, pushing the small-diameter cylindrical portion into the large-diameter cylindrical portion and simultaneously shearing the connecting portions of both cylindrical portions, and a part of the connecting portion Simultaneously polishing the end surfaces of the large-diameter cylindrical portion and the small-diameter cylindrical portion pushed into the large-diameter cylindrical portion while being connected to each other via
The steps of separating the two cylindrical portions connected to each other through a part of the connecting portion relative to each other in the axial direction and the step of expanding the diameter of the large-diameter cylindrical portion by cold rolling are performed. In order, each dimension of the inner diameter, outer diameter and width of the small-diameter cylindrical portion formed by the forging is set to a value having a predetermined margin for each dimension of the annular material for the inner ring, The inner diameter of the large-diameter cylindrical part is set to a dimension that approximates the outer diameter of the small-diameter cylindrical part, and the width dimension is set to the same dimension as the width of the small-diameter cylindrical part .
[0006]
According to this method for producing an annular material for a bearing ring, the connecting portion of both cylindrical portions is sheared leaving a part thereof, so that the width polishing can be performed in a state where both cylindrical portions are connected by the portion. it can. For this reason, simultaneous polishing of the end faces of both cylindrical portions can be performed without hindrance. Moreover, since both cylindrical parts are relatively moved in the axial direction and separated from each other in a state in which both cylindrical parts are connected to each other, both can be separated without forming a conventional stick groove. Moreover, since the large diameter cylindrical portion is expanded by cold rolling after separating both cylindrical portions, the inner diameter of the large diameter cylindrical portion is approximated to the outer diameter of the small diameter cylindrical portion before separating both cylindrical portions. I can leave. For this reason, it is not necessary to form the conventional connection part for connecting both cylindrical parts.
[0007]
In the manufacturing method of the annular material for the bearing ring, between the step of forming the large-diameter cylindrical portion and the small-diameter cylindrical portion and the step of shearing the connecting portion of both the cylindrical portions leaving a part thereof. Preferably, the method includes a step of reducing the axial width of the connecting portion. In this case, since the axial width of the connecting portion can be reduced in advance, the small-diameter cylindrical portion can be easily pushed into the large-diameter cylindrical portion with a small load. For this reason, when pushing a small diameter cylindrical part into the inside of a large diameter cylindrical part, it can suppress that the end surface by the side of the connection part of a large diameter cylindrical part is pulled by the said connection part, and is indented and deformed.
In the manufacturing method of the annular material for the bearing race, it is preferable that the corner portion of the large-diameter cylindrical portion is chamfered by the cold rolling process (Claim 3), thereby performing a conventional chamfering process by turning. Can be omitted.
Further, in the method of manufacturing the annular material for the bearing race, the small diameter cylindrical portion is formed into a bottomed cylindrical shape in the forging step, and the small diameter cylindrical portion is pushed into the large diameter cylindrical portion at the same time, You may drill the bottom part of a small diameter cylindrical part.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a process diagram showing a method for manufacturing an annular material for a bearing race according to an embodiment of the present invention. This manufacturing method is applied to the manufacture of the annular material A for the inner ring and the annular material B for the outer ring of the deep groove ball bearing. First, hot forging is applied to a bar made of steel such as bearing steel, A large-diameter cylindrical portion 1 for the outer ring and a small-diameter cylindrical portion 2 for the inner ring are formed (see FIG. 1a). The inner peripheral end portion of the large-diameter cylindrical portion 1 and the outer peripheral end portion of the small-diameter cylindrical portion 2 are connected to each other in an overlapped state in the axial direction. Further, the cylindrical portions 1 and 2 can be integrally formed at a high speed and continuously by using, for example, a multistage former.
[0009]
The dimensions of the outer diameter, inner diameter, and width of the small-diameter cylindrical portion 2 are set to values having a predetermined allowance with respect to the dimensions of the finally obtained inner ring annular material A. Further, the inner diameter of the large-diameter cylindrical portion 1 is set to a dimension that approximates the outer diameter of the small-diameter cylindrical portion 2, and the width thereof is a predetermined value relative to the width of the annular material B for the outer ring that is finally obtained. The value having a margin, that is, the same dimension as the width of the small diameter cylindrical portion 2 is set. Therefore, the large-diameter cylindrical portion 1 has a smaller inner and outer diameter than the annular material B for the outer ring, and the thickness is increased accordingly. The axial width D of the overlapped portion (connecting portion) J of both cylindrical portions 1 and 2 is set to about 2 to 5 mm according to the sizes of the large diameter cylindrical portion 1 and the small diameter cylindrical portion 2.
[0010]
Next, in the drawing of the small diameter cylindrical portion 2, the left end face is pressed in the axial direction by pressing to push the small diameter cylindrical portion 2 into the large diameter cylindrical portion 1 (see FIG. 1b). Thereby, although the shearing force to an axial direction acts on the connection part J of both the cylindrical parts 1 and 2, this connection part J shears in the state which left the part. That is, as the small-diameter cylindrical portion 2 moves in the axial direction, the connecting portion J moves toward the right side in the drawing while undergoing plastic deformation and shearing, and the small-diameter cylindrical portion 2 moves relative to the large-diameter cylindrical portion 1. In the completely overlapped state, a portion where the shear does not occur remains in the connecting portion J, and the large diameter cylindrical portion 1 and the small diameter cylindrical portion 2 are connected to each other through the portion where the shear does not occur. In addition, when both the cylindrical parts 1 and 2 are shape | molded with a multistage former, the process of pushing the said small diameter cylindrical part 2 in the inside of the large diameter cylindrical part 1 may be performed in series by the said multistage former.
[0011]
Next, both end surfaces of the large-diameter cylindrical portion 1 and the small-diameter cylindrical portion 2 are simultaneously polished using a surface grinder to adjust the width dimension (see FIG. 1c). At this time, since both cylindrical portions 1 and 2 are connected to each other and can be polished in a state in which they are relatively prevented from floating, the polishing can be performed without any trouble. Thus, polishing each end face of the large-diameter cylindrical portion 1 and the small-diameter cylindrical portion 2 at the same time can reduce the number of polishing steps compared to the case where these are separately polished. The surface grinder is a Gardner type that allows the large-diameter cylindrical portion 1 and the small-diameter cylindrical portion 2 to pass through a rotating holder between a pair of facing grinding wheels.
[0012]
When the polishing of the end faces of both cylindrical portions 1 and 2 is completed, the outer periphery of the large diameter cylindrical portion 1 is polished using a centerless grinding machine while the small diameter cylindrical portion 2 is held inside the large diameter cylindrical portion 1. The outer diameter is adjusted (see FIG. 1d). Thereafter, the inner circumference of the small-diameter cylindrical portion 2 is turned to adjust the inner diameter (see FIG. 1e). Also in these steps, the cylindrical portions 1 and 2 are connected to each other and are prevented from relatively loosely moving, so that the processing can be performed without any trouble.
[0013]
When the inner peripheral turning of the small-diameter cylindrical portion 2 is completed, the end surface of the small-diameter cylindrical portion 2 is pressed using a press, and both the cylindrical portions 1 and 2 are moved relative to each other in the axial direction so as to be separated from each other (see FIG. 1f). . Next, the inner circumference of the large-diameter cylindrical portion 1 and the outer circumference of the small-diameter cylindrical portion 2 are respectively turned to adjust the dimensions (see FIG. 1g).
Thereafter, the large-diameter cylindrical portion 1 is subjected to cold rolling, and the inner and outer diameters are expanded to a predetermined dimension (see FIG. 1i). In this cold rolling, for example, the large-diameter cylindrical portion 1 is sandwiched and rolled between the forming roll 21 and the mandrel 22 to reduce the wall thickness and expand the inner and outer diameters (FIG. 2 and FIG. 2). (See FIG. 3). In this cold rolling, the outer diameter dimension of the large-diameter cylindrical portion 1 is detected by a sensor, and the rolling amount is controlled so that the outer diameter dimension falls within a predetermined range. Then, after the cold rolling is completed, sizing is performed on the large-diameter cylindrical portion 1 as necessary to adjust the outer diameter.
In the cold rolling, the corner portions 1a on the inner and outer circumferences of the large-diameter cylindrical portion 1 are simultaneously plastically deformed and chamfered. Thus, by chamfering the corner portion 1a at the same time as expanding the inner and outer diameters, it is possible to omit the step of chamfering separately by turning. On the other hand, about the small diameter cylindrical part 2, each corner part is chamfered by turning (refer FIG. 1h).
As described above, the annular material A for the inner ring and the annular material B for the outer ring can be obtained. In the annular materials A and B, a track is formed by turning, and a seal groove is formed by turning as necessary. Is done.
[0014]
In the above manufacturing method, since both the cylindrical parts 1 and 2 can be separated without forming a conventional stick groove, the cutting process for forming the stick groove with poor processing efficiency can be omitted. Yes, productivity can be increased accordingly. In addition, since the inner diameter of the large-diameter cylindrical portion 1 before separating both the cylindrical portions 1 and 2 can be approximated to the outer diameter of the small-diameter cylindrical portion 2, There is no need to form a conventional connecting portion. For this reason, a material yield can be improved. Specifically, in the model number 6203, the material yield can be increased by about 20% compared to the conventional manufacturing method.
[0015]
In the embodiment, the notch 3 may be formed by turning at the left end of the connecting portion J before the small diameter cylindrical portion 2 is pushed into the large diameter cylindrical portion 1 (see FIG. 4). In this case, since stress concentration occurs in the notch 3, the small diameter cylindrical portion 2 can be easily pushed into the large diameter cylindrical portion 1 with a small load.
Further, in the cold rolling step, the large-diameter cylindrical portion 1 may be enlarged in diameter, and at the same time, a track may be formed on the inner periphery thereof. Can be increased.
[0016]
FIG. 5 is a process diagram showing another embodiment. This embodiment differs from the embodiment shown in FIG. 1 in that, in the embodiment shown in FIG. 1, the holes in the small diameter cylindrical portion 2 are formed at the stage where the large diameter cylindrical portion 1 and the small diameter cylindrical portion 2 are formed. In contrast to the completion of the opening process (see FIG. 1a), in the embodiment shown in FIG. 5, the small-diameter cylindrical portion 2 is formed into a bottomed cylindrical shape, and the small-diameter cylindrical portion 2 is formed into a large-diameter cylinder. After the step of pushing into the portion 1 is completed, the drilling process is performed.
In this embodiment, a series of steps up to the drilling process is performed by hot forging using a multistage former. That is, after the bar material is upset and forged as the first step of the multi-stage former (see FIG. 5a), the large-diameter cylindrical portion 1 and the small-diameter cylindrical portion 2 connected to each other via the connecting portion J as the second step. Mold (see FIG. 5b). At this time, the small-diameter cylindrical portion 2 is formed into a bottomed cylindrical shape. Next, as a third step, after pressing the left end face in the drawing of the small diameter cylindrical portion 2 in the axial direction and pushing the small diameter cylindrical portion 2 into the large diameter cylindrical portion 1 (see FIG. 5c), the fourth step As a process, the small-diameter cylindrical portion 2 is drilled (see FIG. 5d). The subsequent steps are the same as those shown in FIGS. 1c to i.
[0017]
FIG. 6 is a process diagram showing still another embodiment. This embodiment differs from the embodiment shown in FIG. 1 in that, in the embodiment shown in FIG. 1, the holes in the small diameter cylindrical portion 2 are formed at the stage where the large diameter cylindrical portion 1 and the small diameter cylindrical portion 2 are formed. In contrast to the completion of the machining, in the embodiment shown in FIG. 6, the small-diameter cylindrical portion 2 is formed into a bottomed cylindrical shape, and the small-diameter cylindrical portion 2 is placed inside the large-diameter cylindrical portion 1. At the same time as the pushing step, the drilling process is performed, the step of forming the large diameter cylindrical portion 1 and the small diameter cylindrical portion 2 in the embodiment shown in FIG. 1 (see FIG. 1a), and both cylinders During the step of shearing the connecting portion J of the portions 1 and 2 while leaving a part thereof (see FIG. 1b), the small diameter cylindrical portion 2 is further protruded from the large diameter cylindrical portion 1 and the shaft of the connecting portion J This is a point in which the step of reducing the direction width D is performed.
[0018]
Also in this embodiment, a series of steps up to the drilling process is performed by hot forging using a multistage former. That is, after the bar material is upset and forged as the first step of the multi-stage former (see FIG. 6a), the large-diameter cylindrical portion 1 and the small-diameter cylindrical portion 2 connected to each other via the connecting portion J as the second step. Mold (see FIG. 6b). At this time, the axial width D of the connecting portion J is set to be equal to or larger than the axial width D of the connecting portion J shown in FIG. 1a. The small diameter cylindrical portion 2 is formed into a bottomed cylindrical shape. Next, as a third step, the right end face in the drawing of the small-diameter cylindrical portion 2 is pressed in the axial direction to cause the small-diameter cylindrical portion 2 to further protrude from the large-diameter cylindrical portion 1, and at the same time, the axial direction of the connecting portion J By reducing the width D, the final axial width E is made smaller than the axial width D of the connecting portion J shown in FIG. 1a (see FIG. 6c). Thereafter, as a fourth step, the left end face in the drawing of the small-diameter cylindrical portion 2 is pressed in the axial direction to push the small-diameter cylindrical portion 2 into the large-diameter cylindrical portion 1 and at the same time, drill the small-diameter cylindrical portion 2. (See FIG. 6d). The subsequent steps are the same as those shown in FIGS. 1c to i.
[0019]
In this embodiment, since the final axial width E of the connecting portion J is smaller than the axial width D of the connecting portion J shown in FIG. 1, the small diameter cylindrical portion 2 is replaced by the large diameter cylindrical portion 1. Can be easily pushed into the interior of the housing with a small load. For this reason, when the small-diameter cylindrical portion 2 is pushed into the large-diameter cylindrical portion 1, the end surface on the connecting portion J side of the large-diameter cylindrical portion 1 is pulled by the connecting portion J so as to be recessed and deformed to the other surface side. The occurrence of end face sagging can be suppressed. For this reason, the dimensional accuracy of the large-diameter cylindrical portion 1 can be increased, and it is possible to prevent a product defect such as a so-called black skin residue from occurring due to insufficient margin of the end face.
Further, if the axial width D of the connecting portion J is formed at a stroke so as to be equal to the axial width E after the completion of the third step in the second step, the deformation resistance increases the burden on the mold, Although the life of the molding die is shortened, in this embodiment, since the connecting portion J is widened in two steps, the life of the molding die can be ensured.
In addition, the manufacturing method of the annular material for the bearing race of the present invention includes not only the annular material for the deep groove ball bearing described above but also the manufacturing method of the annular material for other rolling bearings such as the annular material for the roller bearing. Can be applied.
[0020]
【The invention's effect】
As described above, according to the method of manufacturing the annular material for the bearing race according to claim 1, both cylindrical portions can be separated from each other without forming a conventional sticking groove for ring removal. The cutting process for forming the stick groove having low efficiency can be omitted, and the productivity can be increased. And since it is not necessary to form the conventional connection part for connecting both cylindrical parts, the material yield can be raised. Therefore, the manufacturing cost of the annular material for the bearing race can be reduced.
[0021]
According to the method of manufacturing the annular material for the bearing race according to claim 2, the axial width of the connecting portion is reduced so that the small diameter cylindrical portion can be easily pushed into the large diameter cylindrical portion with a small load. Therefore, when the small diameter cylindrical portion is pushed into the large diameter cylindrical portion, it is possible to suppress the end surface of the large diameter cylindrical portion on the connecting portion side from being pulled and deformed by the connecting portion. For this reason, it is possible to improve the dimensional accuracy of the large-diameter cylindrical portion, and it is possible to prevent a product defect from occurring due to insufficient margin of the end face.
According to the method for producing an annular material for a bearing race according to claim 3, the turning process for chamfering can be omitted, so that productivity can be further increased.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a method for producing an annular material for a bearing race of the present invention.
FIG. 2 is a cross-sectional view showing details of a cold rolling process.
FIG. 3 is a plan view of the previous figure.
FIG. 4 is a cross-sectional view showing another embodiment.
FIG. 5 is a process diagram showing still another embodiment.
FIG. 6 is a process diagram showing still another embodiment.
FIG. 7 is a process diagram showing a conventional example.
[Explanation of symbols]
1 Large-diameter cylindrical portion 1a Corner portion 2 Small-diameter cylindrical portion A Inner ring annular material B Outer ring annular material J Connection portion

Claims

A method for producing an annular material for an outer ring of a bearing and an annular material for an inner ring,
Forging a large-diameter cylindrical portion for an outer ring and a small-diameter cylindrical portion for an inner ring from a steel bar by forging, an inner periphery of one end portion in the axial direction of the large-diameter cylindrical portion, and an outer periphery of the other end portion in the axial direction of the small-diameter cylindrical portion. And in a state where they are connected to each other in the axial direction ,
Simultaneously pressing the small-diameter cylindrical portion into the large-diameter cylindrical portion and shearing the connecting portions of both cylindrical portions, leaving a part thereof;
Simultaneously polishing the end surfaces of the large-diameter cylindrical portion and the small-diameter cylindrical portion pushed into the large-diameter cylindrical portion in a state of being connected to each other via a part of the connecting portion;
Separating both of the cylindrical portions connected to each other via a part of the connecting portion by moving them relative to each other in the axial direction;
Including a step of expanding the diameter of the large-diameter cylindrical portion by cold rolling in this order,
The inner diameter, the outer diameter, and the width of the small-diameter cylindrical portion formed by the forging are set to values having predetermined margins with respect to the dimensions of the inner ring annular material, and the large diameter An annular material for a bearing race , wherein the inner diameter of the cylindrical portion is set to a dimension that approximates the outer diameter of the small-diameter cylindrical portion, and the width dimension is set to be the same as the width of the small-diameter cylindrical portion . Production method.

Including a step of reducing an axial width of the connecting portion between the step of forming the large-diameter cylindrical portion and the small-diameter cylindrical portion and the step of shearing the connecting portions of both cylindrical portions leaving a part of them. A method for manufacturing an annular material for a bearing race according to claim 1.

The method for producing an annular material for a bearing race according to claim 1, wherein the corner portion of the large-diameter cylindrical portion is chamfered by the cold rolling process.

In the forging process, the small diameter cylindrical portion is formed into a bottomed cylindrical shape,
The annular material for a bearing race according to any one of claims 1 to 4, wherein the small diameter cylindrical portion is pushed into the large diameter cylindrical portion and, at the same time, the bottom of the small diameter cylindrical portion is drilled. Method.