JP4186626B2

JP4186626B2 - Manufacturing method of rolling sliding member

Info

Publication number: JP4186626B2
Application number: JP2003010161A
Authority: JP
Inventors: 久原田; 一寿戸田
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 2003-01-17
Filing date: 2003-01-17
Publication date: 2008-11-26
Anticipated expiration: 2023-01-17
Also published as: JP2004218815A

Description

【０００１】
【発明の属する技術分野】
本発明は、転がり軸受、滑り軸受、一方向クラッチ等の構成部材のように相手部材との間で転がり接触若しくは滑り接触または両接触を含む接触をする転がり摺動部材の製造方法に関する。
【０００２】
【従来の技術】
従来より、例えば、転がり軸受の軌道面は、繰り返し荷重がかかるために寿命が短いという問題がある。この問題の対応策として、軌道面に対しショットピーニング加工を施して残留圧縮応力を付与し、転がり疲れ寿命を向上させる方策が知られている（特許文献１参照）。また、ショットピーニング加工よりも深い部分に高い残留圧縮応力を付与できるローラバニシング加工を施す方策も知られている（特許文献２参照）。
【０００３】
【特許文献１】
特開２００１−６５５７６号公報（第２頁）
【特許文献２】
特開２００２−１６８２５６号公報（第３頁）
【０００４】
【発明が解決しようとする課題】
しかしながら、ショットピーニング加工やローラバニシング加工により残留圧縮応力を付与すると、加工面が２００℃を超えるような温度となり、付与された残留圧縮応力が解放されるので、軌道面における残留圧縮応力が、深くなっていくにつれて、徐々に減少し、極小値を経て増大し、極大値を経てさらに減少していくような分布となってしまう（図２、流量２リットル／ｍｉｎ参照）。そして、残留圧縮応力の極小値が発生する部分と最大剪断応力が作用する部分とが一致してしまうと、残留圧縮応力付与による内部起点剥離防止効果が充分に得られず、短寿命なものになってしまうという問題がある。この問題を解消するため、残留圧縮応力の極小値が発生する部分を研磨により除去する方策が考えられるが、工程数が増加する等のため製造コストがかかり、また残留圧縮応力の極小値が発生する部分にばらつきがあるため均質な製品供給が難しいという新たな問題が生じる。
【０００５】
本発明はこのような事情に鑑みなされたものであり、残留圧縮応力の小さくなる部分の発生を抑制することにより長寿命化を実現した転がり摺動部材およびその製造方法、並びにそれを用いた転がり軸受の提供をその目的とする。
【０００６】
【課題を解決するための手段】
本発明の第１の転がり摺動部材の製造方法は、残留圧縮応力付与加工が施されたＳＵＪ２製の転がり摺動部材を製造する方法であって、
所定形状に形成されたＳＵＪ２製の中間素材を作製し、この中間素材に対し、圧縮応力の解放を抑制する冷却を行いながらボールを強圧で押し付けて転がり接触させる残留圧縮応力付与加工を施すことにより、
残留圧縮応力付与加工面から、残留圧縮応力付与加工面の残留圧縮応力より大きく、かつ残留圧縮応力が最大となる部分までの深さにおいて、当該加工面における残留圧縮応力と残留圧縮応力付与加工面の残留圧縮応力より小さい残留圧縮応力の最小値との差を１５０ＭＰａ以下に設定する工程を含み、
前記圧縮応力の解放を抑制する冷却が、前記中間素材の残留圧縮応力付与加工面の温度が１００℃を超え２００℃以下となる冷却であることを特徴としている（請求項１）。
上記の第１の製造方法によれば、ＳＵＪ２製の転がり摺動部材を製造に際して、圧縮応力の解放を抑制する前記冷却を行いながらボールを強圧で押し付けて転がり接触させる残留圧縮応力付与加工を施すので、残留圧縮応力が小さくなる部分（極小値）の発生を抑制できる。そのため、最大剪断応力が作用する部分の残留圧縮応力が小さいために短寿命になるということがなくなるので、従来以上に長寿命な転がり摺動部材が得られる。また、残留圧縮応力の小さい部分を研磨により除去する場合、研磨量が少なくてよいので、製造コストを低く抑えることができるという利点がある。
ここで、本発明において、残留圧縮応力付与加工とは、加工面に対し強制的に大きな残留圧縮応力を付与できる全ての機械加工を含むが、切削や研削など外形形成過程で必然的にある程度の残留圧縮応力が付与される加工を除く概念であり、ローラバニシング加工を含む。
【０００７】
上記の製造方法において、前記圧縮応力の解放を抑制する冷却は、前記中間素材の残留圧縮応力付与加工面の温度が１００℃を超え２００℃以下となる冷却である。このような冷却であれば、確実に加工面における残留圧縮応力と残留圧縮応力の最小値との差が１５０ＭＰａ以下となるので、従来よりも長寿命な転がり摺動部材が得られる。
ここで、本発明において、前記中間素材の残留圧縮応力付与加工面における温度の測定は、加工時に加工面を直接測定することができないので、加工面の近傍を測定することにより行う。そして、このようにして測定した温度が上記した特定の温度範囲であれば上記した効果が得られる。
また、本発明において、残留圧縮応力の各数値は、後記の図２以外は、絶対値で表している。
【０００８】
本発明の第２の転がり摺動部材の製造方法は、残留圧縮応力付与加工が施されたＳＵＪ２製の転がり摺動部材を製造する方法であって、
所定形状に形成されたＳＵＪ２製の中間素材を作製し、この中間素材に対し、圧縮応力の解放を抑制する冷却を行いながらボールを強圧で押し付けて転がり接触させる残留圧縮応力付与加工を施すことにより、
残留圧縮応力付与加工面から、残留圧縮応力付与加工面の残留圧縮応力より大きく、かつ残留圧縮応力が最大となる部分までの深さにおける残留圧縮応力を常に増大するように設定する工程を含み、
前記圧縮応力の解放を抑制する冷却が、前記中間素材の残留圧縮応力付与加工面の温度が１００℃以下となる冷却であることを特徴としている（請求項２）。
上記の第２の製造方法によれば、ＳＵＪ２製の転がり摺動部材を製造に際して、圧縮応力の解放を抑制する前記冷却を行いながらボールを強圧で押し付けて転がり接触させる残留圧縮応力付与加工を施して、残留圧縮応力が常に増大するようにするので、残留圧縮応力の極小値がなくなる。そのため、残留圧縮応力の極小値と最大剪断応力が作用する部分とが一致して短寿命になるということがなくなるので、従来以上に長寿命な転がり摺動部材が得られる。また、残留圧縮応力の小さい部分を研磨により除去する場合、研磨量が少なくてよいので、製造コストを低く抑えることができるという利点がある。
上記の第２の製造方法では、前記圧縮応力の解放を抑制する冷却が、前記中間素材の残留圧縮応力付与加工面の温度が５０℃以下となる冷却であるのが好ましい。
【０００９】
上記の第２の製造方法において、前記圧縮応力の解放を抑制する冷却は、前記中間素材の残留圧縮応力付与加工面の温度が１００℃以下となる冷却であるのが好ましい（請求項４）。このような冷却であれば、確実に残留圧縮応力が常に増大するようになるので、従来よりも長寿命な転がり摺動部材が得られる。
また、上記の第２の製造方法において、前記加工面における残留圧縮応力を６００ＭＰａ以上に設定することが好ましい。この場合には、加工面から残留圧縮応力が最大となる部分までの深さにおける残留圧縮応力が確実に６００ＭＰａ以上となるので、非常に長寿命な転がり摺動部材が得られる。そして、上記の製造方法において、前記加工面における残留圧縮応力と残留圧縮応力が最大となる部分の残留圧縮応力との差を３００ＭＰａ以下に設定することが好ましい。この場合には、残留圧縮応力がより平均化されているので、適用範囲の広い長寿命な転がり摺動部材が得られる。上記の製造方法において、前記圧縮応力の解放を抑制する冷却は、前記中間素材の残留圧縮応力付与加工面の温度が５０℃以下となる冷却であるのが好ましい。このような冷却であれば、従来よりも長寿命で適用範囲の広い転がり摺動部材が得られる。
【００１０】
上記した第１、第２の製造方法において、前記残留圧縮応力付与加工が、残留圧縮応力の最大値が８００ＭＰａ以上となる加工であることが好ましい。このような加工の場合に改善効果が顕著に現れるからである。また、残留圧縮応力付与加工としてボールを強圧で押し付けて転がり接触させるローラバニシング加工を用いており、より深い位置に高い残留圧縮応力を付与できるので、得られる転がり摺動部材をより広い用途に用いることができるという利点がある。
【００１５】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照しながら説明する。
図１は、この発明の一実施形態にかかる転がり摺動部材の製造方法を示す工程図である。この製造方法は、玉軸受の内輪の製造に適用されるものであり、まず、軸受鋼（ＳＵＪ２）からなる環状素材１（図１(a)参照）に旋削加工を施して、端面２ａ、外周２ｂ、軌道２ｃおよび内周２ｄ等を所定形状に加工する（図１(b)参照）。ついで、この旋削加工されたブランク２に浸炭焼入を含む熱処理を施して、その表面硬さが例えばロックウェルＣ硬さ６０以上となるように硬化させる（図１(c)参照）。その後、熱処理が完了したブランク２の端面２ａ、軌道２ｃおよび内周２ｄを、研削によって所定精度に仕上げ、中間素材３を得る（図１(d)参照）。
【００１６】
研削による仕上げ加工が完了すると、前記軌道２ｃの表面にローラバニシング加工を施す（図１(e)参照）。このローラバニシング加工は、油圧で保持されたセラミックス製の鏡面ボール４を、軌道２ｃの表面に強圧で押し付けて転がり接触させながら、軌道２ｃの軸方向断面に沿って移動させるものである。そして、転がり接触は、冷却液供給装置のノズル５から冷却液を一定の流量となるよう吐出させながら行う。これにより、加工面の温度が低くなり、ローラバニシング加工用の鏡面ボール４と軌道２ｃとの接触による摩擦熱によって圧縮応力が解放されることが抑えられる。冷却液の流量は、加工面の温度が２００℃以下となるようにするのが好ましく、より好ましくは１００℃以下、さらに好ましくは５０℃以下となるように設定する。すなわち、１００℃を超え２００℃以下であると、残留圧縮応力の解放が抑制されて残留圧縮応力が小さくなる度合いが減り、また１００℃以下であると、残留圧縮応力の極小値がなくなり、さらに５０℃以下であると加工面における残留圧縮応力が６００ＭＰａ以上となるからである。なお、このローラバニシング加工においては、軌道２ｃ表面に対し、残留圧縮応力の最大値が８００ＭＰａ以上、より好ましくは９００ＭＰａ以上となるように、そのバニシング量や加圧力等の加工条件を選択する。
【００１７】
このようにして得られた内輪は、軌道における残留圧縮応力が小さくなる部分（極小値）の発生が抑制または消失するようになっているので、より長寿命なものになっている。
【００１８】
図２は前記ローラバニシング加工後における加工面からの各深さにおける残留圧縮応力を測定した結果を示すグラフ図である。この図には、冷却液の流量が２リットル／ｍｉｎの場合（１．０倍の流量の場合、比較例）、１．５倍の流量の場合、２．０倍の流量の場合、３．０倍の流量の場合について記載している。なお、冷却液の流量以外の実験条件は、８４０℃で４５分間、油焼入れ、１８０℃で２時間の焼戻し処理を行ったＳＵＪ２製のスラスト円板を用い、冷却液を用いながら、ワーク回転数１００ｒｐｍ／ｍｉｎ、ツール送り０．１ｍｍ／ｒｅｖ、使用加工液：エマルカットＤＣ６４（協同油脂社製）、直径６．３ｍｍのセラミックス鏡面ボールを用いたローラバニシング加工を施す、とした。
【００１９】
図２から明らかなように、１．５倍の流量の場合は、加工面からの深さ０．０１ｍｍにおいて残留圧縮応力の極小値が存在するが、１．０倍の流量の場合に比べて、圧縮応力の解放が抑制されてより大きな残留圧縮応力が付与されていることがわかる。すなわち、１．０倍のときは１５２ＭＰａで、１．５倍の流量の場合は３２０ＭＰａであり、２倍以上付与されていることがわかる。よって、１．５倍の流量にした方が、より長寿命なものになることがわかる。
また、２．０倍の流量の場合は、加工面における残留圧縮応力が４２４ＭＰａで、深さ０．０９ｍｍ（残留圧縮応力が最大となる深さ）における残留圧縮応力が９１３ＭＰａであり、加工面から残留圧縮応力が最大となる深さまでにおいて、常に残留圧縮応力が増大するようになっているので、最大剪断応力が作用する部分が残留圧縮応力の極小値と一致することがないことがわかる。よって、２．０倍の流量にした場合には、より長寿命なものになることがわかる。
さらに、３．０倍の流量の場合は、加工面における残留圧縮応力が６３０ＭＰａで、深さ０．０９ｍｍ（残留圧縮応力が最大となる深さ）における残留圧縮応力が８９６ＭＰａで、その差が２６６ＭＰａとなっており、流量が１．０倍、１．５倍、２．０倍の場合に比べて、より最大値と最小値との差が小さくなっていることがわかる。よって、３．０倍の流量にした場合には、より適用範囲の広い長寿命なものになることがわかる。
なお、流量が１．０倍の場合は加工面の温度が２１０℃であり、流量が１．５倍の場合は加工面の温度が１３２℃であり、流量が２．０倍の場合は加工面の温度が８５℃であり、流量が３．０倍の場合は加工面の温度が４３℃であった。
【００２０】
（その他の事項）
上記では、冷却液を用いたが、これに限定するものではなく、可能であれば、冷却液に代えて冷却気体を用いてもよい。
さらに、ボールの材質として、セラミックスに限定するものではなく、加工する素材の表面よりも硬いものであればよく、例えば、高硬度の鋼であってもよい。
なお、上記では、加工面を研磨しない場合について説明したが、必要に応じて研磨してもよい。残留圧縮応力の解放を抑制しているので、従来よりも研磨量を少なく済ますことができるという利点がある。
さらに、上記では、玉軸受用の内輪について説明したが、外輪であっても同様に適用することができる。また、転動体も同様にして製造することができる。さらに、玉軸受だけでなく、その他の各種のころ軸受、滑り軸受、一方向クラッチ等の転がり接触若しくは滑り接触または両接触を含む接触をする構成部材についても、同様に適用することが可能である。
【００２１】
【発明の効果】
以上のように、請求項１の転がり摺動部材の製造方法によれば、残留圧縮応力が小さい部分の発生を抑制できるので、その部分と最大剪断応力が作用する部分とが一致したとしても従来よりも長寿命な転がり摺動部材が得られる。上記の製造方法において、圧縮応力を解放する冷却として中間素材の残留圧縮応力付与加工面の温度が１００℃を超え２００℃以下となる冷却を行う場合には、確実に残留圧縮応力が小さい部分の発生が抑制されて従来よりも長寿命な転がり摺動部材が得られる。
【００２２】
請求項２の転がり摺動部材の製造方法によれば、残留圧縮応力の極小値がなくなるので、残留圧縮応力の極小値と最大剪断応力が作用する部分とが一致して短寿命になるということがなく、従来以上に長寿命な転がり摺動部材が得られる。上記の製造方法において、圧縮応力の解放を抑制する冷却として中間素材の残留圧縮応力付与加工面の温度が１００℃以下となる冷却を行うことにより、確実に残留圧縮応力が常に増大するようになるので、従来よりも長寿命な転がり摺動部材が得られる。また、上記の製造方法において、加工面における残留圧縮応力を６００ＭＰａ以上に設定するようにした場合には、非常に長寿命な転がり摺動部材が得られる。さらに、加工面における残留圧縮応力と残留圧縮応力が最大となる部分の残留圧縮応力との差を３００ＭＰａ以下に設定するようにした場合には、適用範囲の広い長寿命な転がり摺動部材が得られる。そして、圧縮応力の解放を抑制する冷却として中間素材の残留圧縮応力付与加工面の温度が５０℃以下となる冷却を行う場合には、従来よりも長寿命で適用範囲の広い転がり摺動部材が得られる。
【００２３】
上記した製造方法において、前記残留圧縮応力付与加工が、残留圧縮応力の最大値が８００ＭＰａ以上となる加工である場合には、顕著に寿命の改善効果が現れる。また、残留圧縮応力付与加工としてボールを強圧で押し付けて転がり接触させるローラバニシング加工を用いており、より適用範囲の広いものが得られるという利点がある。
【図面の簡単な説明】
【図１】本発明の転がり摺動部材の製造方法の一例を示す模式的な工程図である。
【図２】ローラバニシング加工後における加工面からの各深さにおける残留圧縮応力を測定した結果を示すグラフ図である。
【符号の説明】
１環状素材
２ブランク
２ａ端面
２ｂ外周
２ｃ軌道
２ｄ内周
３中間素材
４鏡面ボール
５ノズル[0001]
BACKGROUND OF THE INVENTION
The present invention is a rolling bearing, a sliding bearing, relates to the production how the rolling sliding member to contact comprising rolling contact or sliding contact or both contact with the mating member as components, such as one-way clutch .
[0002]
[Prior art]
Conventionally, for example, a raceway surface of a rolling bearing has a problem that its life is short due to repeated load. As a countermeasure against this problem, there is known a method of applying a shot peening process to the raceway surface to give a residual compressive stress to improve a rolling fatigue life (see Patent Document 1). Also known is a method of performing roller burnishing that can apply a high residual compressive stress to a deeper portion than shot peening (see Patent Document 2).
[0003]
[Patent Document 1]
JP 2001-65576 A (2nd page)
[Patent Document 2]
JP 2002-168256 A (page 3)
[0004]
[Problems to be solved by the invention]
However, if the residual compressive stress is applied by shot peening or roller burnishing, the processed surface becomes a temperature exceeding 200 ° C., and the applied residual compressive stress is released. The distribution gradually decreases, increases through the minimum value, and further decreases through the maximum value (see FIG. 2, flow rate 2 liter / min). If the portion where the minimum value of the residual compressive stress occurs and the portion where the maximum shear stress acts coincide with each other, the effect of preventing the internal origin peeling due to the residual compressive stress cannot be sufficiently obtained, and the life is shortened. There is a problem of becoming. In order to solve this problem, it is conceivable to remove the portion where the minimum value of residual compressive stress occurs by polishing. However, the manufacturing cost increases due to the increase in the number of processes and the minimum value of residual compressive stress is generated. There is a new problem that it is difficult to supply a homogeneous product due to variations in the parts to be processed.
[0005]
The present invention has been made in view of such circumstances, a rolling sliding member that realizes a long life by suppressing the occurrence of a portion where residual compressive stress is reduced, a manufacturing method thereof, and a rolling using the same. The purpose is to provide a bearing.
[0006]
[Means for Solving the Problems]
The manufacturing method of the 1st rolling sliding member of this invention is a method of manufacturing the rolling sliding member made from SUJ2 by which the residual compressive stress provision process was performed,
By producing an intermediate material made of SUJ2 formed in a predetermined shape, and applying a residual compressive stress application process that presses the ball with high pressure and makes rolling contact with this intermediate material while cooling to suppress the release of compressive stress ,
In the depth from the residual compressive stress imparted processed surface to the portion where the residual compressive stress is greater than that of the residual compressive stress imparted processed surface and the residual compressive stress is maximized, the residual compressive stress and the residual compressive stress imparted processed surface on the processed surface Including a step of setting a difference from the minimum value of the residual compressive stress smaller than the residual compressive stress of 150 MPa or less,
The cooling that suppresses the release of the compressive stress is a cooling in which the temperature of the residual compressive stress applying processed surface of the intermediate material exceeds 100 ° C. and becomes 200 ° C. or less (Claim 1).
According to the first manufacturing method, when a rolling sliding member made of SUJ2 is manufactured, a residual compressive stress imparting process is performed in which the ball is pressed and brought into rolling contact with the strong pressure while performing the cooling to suppress the release of the compressive stress. Therefore, generation | occurrence | production of the part (minimum value) where residual compressive stress becomes small can be suppressed. For this reason, since the residual compressive stress at the portion where the maximum shear stress acts is small, there is no longer a short life, so that a rolling sliding member having a longer life than the conventional one can be obtained. Further, when the portion having a small residual compressive stress is removed by polishing, there is an advantage that the manufacturing cost can be reduced because the polishing amount may be small.
Here, in the present invention, the residual compressive stress applying process includes all machining that can forcibly apply a large residual compressive stress to the processed surface, but is inevitably to some extent in the outer shape forming process such as cutting and grinding. It is a concept that excludes processing to which residual compressive stress is applied, and includes roller burnishing.
[0007]
In the above manufacturing method, inhibiting the release of the compressive stress cooling, Ru cooling der the temperature of the residual compressive stress imparted processing surface of the intermediate material is equal to or less than 200 ° C. exceed 100 ° C.. With such cooling, the difference between the residual compressive stress on the processed surface and the minimum value of the residual compressive stress is 150 MPa or less, so that a rolling sliding member having a longer life than the conventional one can be obtained.
Here, in the present invention, the measurement of the temperature of the intermediate material on the processing surface to which the residual compressive stress is applied is performed by measuring the vicinity of the processing surface because the processing surface cannot be directly measured during processing. And if the temperature measured in this way is the above-mentioned specific temperature range, the above-mentioned effect will be acquired.
In the present invention, each numerical value of the residual compressive stress is expressed as an absolute value except for FIG.
[0008]
The second method for producing a rolling sliding member of the present invention is a method for producing a rolling sliding member made of SUJ2 that has been subjected to residual compressive stress application processing,
By producing an intermediate material made of SUJ2 formed in a predetermined shape, and applying a residual compressive stress application process that presses the ball with high pressure and makes rolling contact with this intermediate material while cooling to suppress the release of compressive stress ,
Including a step of constantly increasing the residual compressive stress at a depth from the residual compressive stress imparted processed surface to a portion where the residual compressive stress is greater than the residual compressive stress of the residual compressive stress imparted processed surface and has the maximum residual compressive stress,
The cooling that suppresses the release of the compressive stress is a cooling that causes the temperature of the residual compressive stress applying processed surface of the intermediate material to be 100 ° C. or lower (claim 2).
According to the second manufacturing method described above, when a rolling sliding member made of SUJ2 is manufactured, a residual compressive stress applying process is performed in which the ball is pressed and brought into rolling contact with strong pressure while performing the cooling to suppress the release of the compressive stress. Thus, since the residual compressive stress is always increased, there is no minimum value of the residual compressive stress. For this reason, the minimum value of the residual compressive stress and the portion where the maximum shearing stress is applied are not shortened, so that a rolling sliding member having a longer life than before can be obtained. Further, when the portion having a small residual compressive stress is removed by polishing, there is an advantage that the manufacturing cost can be reduced because the polishing amount may be small.
In said 2nd manufacturing method, it is preferable that the cooling which suppresses release | extrication of the said compressive stress is cooling from which the temperature of the residual compression stress provision surface of the said intermediate material will be 50 degrees C or less.
[0009]
In the second manufacturing method, the cooling that suppresses the release of the compressive stress is preferably a cooling at which the temperature of the residual compressive stress applying surface of the intermediate material becomes 100 ° C. or lower (claim 4). Such cooling ensures that the residual compressive stress always increases, so that a rolling sliding member having a longer life than the conventional one can be obtained.
Moreover, in said 2nd manufacturing method, it is preferable to set the residual compressive stress in the said processed surface to 600 Mpa or more. In this case, since the residual compressive stress at the depth from the processed surface to the portion where the residual compressive stress is maximum is surely 600 MPa or more, a rolling sliding member having a very long life can be obtained. And in said manufacturing method, it is preferable to set the difference of the residual compressive stress in the said process surface and the residual compressive stress of the part where a residual compressive stress becomes the maximum to 300 Mpa or less. In this case, since the residual compressive stress is further averaged, a long-life rolling sliding member with a wide application range can be obtained. In the manufacturing method described above, the cooling that suppresses the release of the compressive stress is preferably a cooling at which the temperature of the residual compressive stress applying processed surface of the intermediate material is 50 ° C. or less. With such cooling, it is possible to obtain a rolling sliding member that has a longer life and a wider application range than before.
[0010]
In the first and second manufacturing methods described above, it is preferable that the residual compressive stress applying process is a process in which the maximum value of the residual compressive stress is 800 MPa or more. This is because the improvement effect appears remarkably in such processing. Moreover, by using a roller burnishing pressurized Engineering for rolling contact against at strong pressure ball as a residual compressive stress imparted processing, it is possible to impart a high residual compressive stresses in the deeper position, the sliding member rolling obtained wider applications There is an advantage that it can be used.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a process diagram showing a method for manufacturing a rolling sliding member according to an embodiment of the present invention. This manufacturing method is applied to the manufacture of an inner ring of a ball bearing. First, an annular material 1 (see FIG. 1 (a)) made of bearing steel (SUJ2) is turned to provide an end face 2a and an outer periphery. 2b, the track 2c, the inner periphery 2d, and the like are processed into a predetermined shape (see FIG. 1B). Next, the turned blank 2 is subjected to a heat treatment including carburizing and quenching so that the surface hardness thereof becomes, for example, a Rockwell C hardness of 60 or more (see FIG. 1 (c)). Thereafter, the end face 2a, the track 2c, and the inner periphery 2d of the blank 2 that has been heat-treated are finished to a predetermined accuracy by grinding to obtain an intermediate material 3 (see FIG. 1 (d)).
[0016]
When finishing by grinding is completed, roller burnishing is performed on the surface of the track 2c (see FIG. 1 (e)). In this roller burnishing process, the mirror surface ball 4 made of ceramics held by hydraulic pressure is moved along the axial cross section of the track 2c while being pressed against the surface of the track 2c with a strong pressure and brought into rolling contact. Then, the rolling contact is performed while discharging the coolant from the nozzle 5 of the coolant supply device so as to have a constant flow rate. As a result, the temperature of the processed surface is lowered, and the release of compressive stress due to frictional heat caused by contact between the mirror-finished ball 4 for roller burnishing and the track 2c is suppressed. The flow rate of the cooling liquid is preferably set so that the temperature of the processed surface is 200 ° C. or less, more preferably 100 ° C. or less, and further preferably 50 ° C. or less. That is, when the temperature exceeds 100 ° C. and is 200 ° C. or less, the release of the residual compressive stress is suppressed and the degree of reduction of the residual compressive stress is reduced, and when the temperature is 100 ° C. or less, the minimum value of the residual compressive stress disappears. It is because the residual compressive stress in a processed surface will be 600 Mpa or more when it is 50 degrees C or less. In this roller burnishing process, the processing conditions such as the burnishing amount and the applied pressure are selected so that the maximum value of the residual compressive stress is 800 MPa or more, more preferably 900 MPa or more with respect to the surface of the track 2c.
[0017]
The inner ring thus obtained has a longer life because generation of a portion (minimum value) in which the residual compressive stress in the track becomes small is suppressed or eliminated.
[0018]
FIG. 2 is a graph showing the results of measuring the residual compressive stress at each depth from the processed surface after the roller burnishing. This figure shows that when the flow rate of the coolant is 2 liters / min (comparative example when the flow rate is 1.0 times), when the flow rate is 1.5 times, and when the flow rate is 2.0 times, The case of 0 times flow rate is described. The experimental conditions other than the flow rate of the coolant were SUJ2 thrust discs that had been tempered at 840 ° C. for 45 minutes, oil-quenched, and 180 ° C. for 2 hours. 100 rpm / min, tool feed 0.1 mm / rev, working fluid: Emulcut DC64 (manufactured by Kyodo Yushi Co., Ltd.), and roller burnishing using a ceramic mirror ball with a diameter of 6.3 mm.
[0019]
As is clear from FIG. 2, when the flow rate is 1.5 times, there is a minimum value of residual compressive stress at a depth of 0.01 mm from the processed surface, but compared with the case where the flow rate is 1.0 times. It can be seen that release of the compressive stress is suppressed and a larger residual compressive stress is applied. That is, when it is 1.0 times, it is 152 MPa, and when it is 1.5 times the flow rate, it is 320 MPa. Therefore, it can be seen that the flow rate is 1.5 times longer.
When the flow rate is 2.0 times, the residual compressive stress on the processed surface is 424 MPa, and the residual compressive stress at a depth of 0.09 mm (depth at which the residual compressive stress is maximized) is 913 MPa. Since the residual compressive stress always increases up to the depth at which the residual compressive stress becomes maximum, it can be seen that the portion where the maximum shear stress acts does not coincide with the minimum value of the residual compressive stress. Therefore, it can be seen that when the flow rate is 2.0 times, the service life is longer.
Furthermore, in the case of a 3.0 times flow rate, the residual compressive stress on the processed surface is 630 MPa, the residual compressive stress at a depth of 0.09 mm (depth at which the residual compressive stress is maximized) is 896 MPa, and the difference is 266 MPa. It can be seen that the difference between the maximum value and the minimum value is smaller than in the case where the flow rates are 1.0 times, 1.5 times, and 2.0 times. Therefore, it can be seen that when the flow rate is 3.0 times, the service life is longer and the application range is wider.
When the flow rate is 1.0 times, the processing surface temperature is 210 ° C., when the flow rate is 1.5 times, the processing surface temperature is 132 ° C., and when the flow rate is 2.0 times, the processing surface is processed. When the surface temperature was 85 ° C. and the flow rate was 3.0 times, the processed surface temperature was 43 ° C.
[0020]
(Other matters)
In the above description, the cooling liquid is used. However, the present invention is not limited to this. If possible, a cooling gas may be used instead of the cooling liquid.
Furthermore, the material of the ball is not limited to ceramics, but may be any material that is harder than the surface of the material to be processed. For example, high hardness steel may be used .
In the above description, the case where the processed surface is not polished has been described. However, the processed surface may be polished as necessary. Since the release of the residual compressive stress is suppressed, there is an advantage that the amount of polishing can be reduced as compared with the prior art.
Furthermore, in the above description, the inner ring for the ball bearing has been described. However, the present invention can be similarly applied to the outer ring. Moreover, a rolling element can be manufactured similarly. Further, not only ball bearings but also various other roller bearings, sliding bearings, one-way clutches, and other components that make rolling contact or sliding contact or contact including both contacts can be similarly applied. .
[0021]
【The invention's effect】
As described above, according to the manufacturing method of the rolling sliding member of claim 1, since the generation of a portion having a small residual compressive stress can be suppressed, even if the portion and the portion on which the maximum shear stress acts coincide with each other, Thus, a rolling sliding member having a longer life can be obtained. In the above manufacturing method, when the cooling of the processed surface of the intermediate material where the residual compressive stress is applied is over 100 ° C. and below 200 ° C. as the cooling for releasing the compressive stress, Occurrence is suppressed and a rolling sliding member having a longer life than the conventional one can be obtained.
[0022]
According to the method for manufacturing a rolling sliding member of claim 2 , since the minimum value of the residual compressive stress is eliminated, the minimum value of the residual compressive stress coincides with the portion where the maximum shear stress acts, and the life is shortened. Thus, a rolling sliding member having a longer life than the conventional one can be obtained. In the above manufacturing method, the residual compressive stress is always increased reliably by performing the cooling so that the temperature of the residual compressive stress imparted processed surface of the intermediate material becomes 100 ° C. or less as the cooling for suppressing the release of the compressive stress. Therefore, a rolling sliding member having a longer life than the conventional one can be obtained. In the above manufacturing method, when the residual compressive stress on the processed surface is set to 600 MPa or more, a rolling sliding member having a very long life can be obtained. Furthermore, when the difference between the residual compressive stress on the processed surface and the residual compressive stress at the portion where the residual compressive stress is maximum is set to 300 MPa or less, a long-life rolling sliding member with a wide application range is obtained. It is done. When cooling is performed so that the temperature of the residual compressive stress imparting processed surface of the intermediate material is 50 ° C. or less as cooling for suppressing the release of compressive stress, a rolling sliding member having a longer life and wider application range than before is provided. can get.
[0023]
In the manufacturing method described above, when the residual compressive stress imparting process is a process in which the maximum value of the residual compressive stress is 800 MPa or more, the effect of improving the life remarkably appears. Further, there is an advantage that uses a roller burnishing pressurized Engineering for rolling contact against at strong pressure ball as a residual compressive stress imparted processing, those wide more coverage is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic process chart showing an example of a method for producing a rolling sliding member of the present invention.
FIG. 2 is a graph showing the results of measurement of residual compressive stress at each depth from the processed surface after roller burnishing.
[Explanation of symbols]
1 annular material 2 blank 2a end surface 2b outer periphery 2c track 2d inner periphery 3 intermediate material 4 mirror surface ball 5 nozzle

Claims

A method of manufacturing a rolling sliding member made of SUJ2 subjected to a residual compressive stress applying process,
By producing an intermediate material made of SUJ2 formed in a predetermined shape, and applying a residual compressive stress application process that presses the ball with high pressure and makes rolling contact with this intermediate material while cooling to suppress the release of compressive stress ,
In the depth from the residual compressive stress imparted processed surface to the portion where the residual compressive stress is greater than that of the residual compressive stress imparted processed surface and the residual compressive stress is maximized, the residual compressive stress and the residual compressive stress imparted processed surface on the processed surface Including a step of setting a difference from the minimum value of the residual compressive stress smaller than the residual compressive stress of 150 MPa or less,
The method for manufacturing a rolling sliding member, wherein the cooling for suppressing the release of the compressive stress is a cooling in which the temperature of the residual compressive stress applying processed surface of the intermediate material exceeds 100 ° C. and becomes 200 ° C. or less.

A method of manufacturing a rolling sliding member made of SUJ2 subjected to a residual compressive stress applying process,
By producing an intermediate material made of SUJ2 formed in a predetermined shape, and applying a residual compressive stress application process that presses the ball with high pressure and makes rolling contact with this intermediate material while cooling to suppress the release of compressive stress ,
Including a step of constantly increasing the residual compressive stress at a depth from the residual compressive stress imparted processed surface to a portion where the residual compressive stress is greater than the residual compressive stress of the residual compressive stress imparted processed surface and has the maximum residual compressive stress,
The method for manufacturing a rolling sliding member, wherein the cooling for suppressing the release of the compressive stress is a cooling at which the temperature of the residual compressive stress applying processed surface of the intermediate material becomes 100 ° C. or less.

The method for manufacturing a rolling sliding member according to claim 2, wherein the cooling that suppresses the release of the compressive stress is a cooling at which the temperature of the residual compressive stress applying processed surface of the intermediate material becomes 50 ° C. or less.