JP2004044787A - Method for manufacturing bearing raceway member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a bearing raceway member, which prolongs the life of a bearing raceway member composed of a carbon steel for machine structural use. <P>SOLUTION: In manufacturing the bearing raceway member, at least the raceway 1c is hardened by heat treatment of a blank B for a raceway member worked in a predetermined shape. The raceway member 1c is ground, and is subjected to a work hardening to at least Hv800 by roller-burnishing in the depth of at least 0.2 mm from its surface. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【産業上の利用分野】
この発明は、機械構造用炭素鋼からなる軸受軌道部材の製造方法に関する。
【０００２】
【従来の技術と発明が解決しようとする課題】
従来、転がり軸受の軌道輪のような軌道部材の素材としては、一般に軸受鋼や浸炭鋼等の軸受用鋼が用いられている。ところが、前記軸受用鋼は高価であることから、転がり軸受の製造コストが高くつくという問題があった。そこで、価格が比較的安いＳ４５ＣやＳ５５Ｃ等の機械構造用炭素鋼によって軌道部材を形成することが一部で行われている。しかし、この場合には、軌道部の焼入硬さが軸受用鋼と比べて低く、その疲労強度を十分に確保することができないので、軌道部材の寿命が短いという問題があった。
この発明は前記問題点に鑑みてなされたものであり、機械構造用炭素鋼からなる軸受軌道部材の長寿命化を図ることができる軸受軌道部材の製造方法を提供することを目的とする。
【０００３】
【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部材の製造方法は、所定形状に加工した機械構造用炭素鋼からなる軌道部材用のブランクを熱処理して、少なくとも軌道部を硬化させた後、当該軌道部を旋削又は研削によって仕上げ、さらに当該軌道部にローラバニシング加工を施して、軌道部の表面から少なくとも０．２ｍｍの深さの硬さをＨｖ８００以上に加工硬化させることを特徴としている（請求項１）。
【０００４】
この軸受軌道部材の製造方法によれば、軌道部材の軌道部にローラバニシング加工を施して、軌道部の表面から少なくとも０．２ｍｍの深さの硬さをＨｖ８００以上にしているので、当該ローラバニシング加工によって軌道部に残留圧縮応力が生じるとともに、その表面粗さが向上する点と相まって、ローラバニシング加工を施していない従来品と比べて軌道部の疲労強度を高めることができる。
【０００５】
前記軸受軌道部材の製造方法においては、含有炭素量が０．４２重量％以上の機械構造用炭素鋼を用いてもよく（請求項２）、この場合は従来の軸受用鋼にほぼ匹敵する疲労強度を発揮することができる。
前記軸受軌道部材の製造方法においては、前記ローラバニシング加工によって、軌道部の表面から少なくとも０．１５ｍｍの深さの残留圧縮応力を、８００ＭＰａ以上にするのが好ましい（請求項３）。この場合には、前記従来品と比べて軌道部の疲労強度をより効果的に高めることができる。
【０００６】
【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説明する。
図１は、この発明の一実施形態にかかる軸受軌道部材の製造方法を示す工程図である。この製造方法は、深溝玉軸受の軌道部材としての内輪１の製造に適用されるものであり、まず、機械構造用炭素鋼であるＳ５５Ｃからなる環状素材Ａ（図１（ａ）参照）に旋削加工を施して、端面１ａ、外周１ｂ、軌道部１ｃ及び内周１ｄ等を所定形状に加工する（図１（ｂ）参照）。次に、この旋削加工されたブランクＢをいわゆるズブ焼入によって熱処理して、ＨＲＣ５５程度の硬さに硬化させる（図１（ｃ）参照）。その後、熱処理が完了したブランクＢの端面１ａ、軌道部１ｃ及び内周１ｄを、研削によって所定精度に仕上げる（図１（ｄ）参照）。
【０００７】
研削による仕上げ加工が完了すると、前記軌道部１ｃの表面にローラバニシング加工（ディープローリング加工）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Ｃを、軌道部１ｃの表面に強圧で押し付けて転がり接触させながら、軌道部１ｃの軸方向断面に沿って移動させるものである。このローラバニシング加工においては、軌道部１ｃの表面から少なくとも０．２ｍｍの深さの硬さをＨｖ８００以上に加工硬化させるとともに、軌道部１ｃの表面から少なくとも０．１５ｍｍの深さの残留圧縮応力が８００ＭＰａ以上、より好ましくは、表面から少なくとも０．２ｍｍの深さにおいても残留圧縮応力が８００ＭＰａ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。
【０００８】
図２は前記ローラバニシング加工後における軌道部１ｃの表面からの各深さにおける硬さを測定した結果を示すグラフ図であり、図３は前記軌道部１ｃの表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。これら各図には、比較のために軌道部に高周波焼入処理したもの、及び軌道部にショットピーニングを施したものの測定結果も併せて記載している。
【０００９】
図２より明らかなように、ローラバニシング加工後の軌道部１ｃは、その表面から少なくとも０．２ｍｍの深さにおいて、Ｈｖ８００以上の硬さが確保されており、高周波焼入品及びショットピーニング品よりも大幅に硬くなっている。また、図３より明らかなように、前記軌道部１ｃは、その表面から少なくとも０．１５ｍｍの深さにおいて、８００ＭＰａ以上の残留圧縮応力が生じており、しかも、ショットピーニング品に比べて約２倍の深さまで加工硬化が生じている。
さらに、前記ローラバニシング加工によって軌道部１ｃの表面粗さを小さくすることができる。この表面粗さは本願発明者の試験によれば、最大高さ粗さ（Ｒｍａｘ）で加工前の１／２以下にできることが確認されている。
【００１０】
前記の製造方法によって得られた内輪１は、ローラバニシング加工によって軌道部１ｃの表面から少なくとも０．２ｍｍの深さの硬さをＨｖ８００以上に加工硬化させているので、軌道部１ｃの表面の粗さが小さくなる点と相まって、ローラバニシング加工を施していない従来品と比べて軌道部１ｃの疲労強度を効果的に高めることができる。特に、前記実施の形態の形態においては、軌道部１ｃの表面から少なくとも０．１５ｍｍの深さの残留圧縮応力を８００ＭＰａ以上としているので、軌道部１ｃの疲労強度をより効果的に高めることができる。したがって、前記内輪１を組み込んだ深溝玉軸受の寿命を従来品に比べて大幅に延ばすことができる。具体的には、前記内輪１を軸受型番６２０６の内輪に適用して、清浄油中において寿命試験を行った結果、軸受鋼（ＳＵＪ−２）からなる同型番の軸受にほぼ匹敵する寿命を発揮し得ることが確認されている。
【００１１】
この発明に用いる軌道部材の素材としては、種々の機械構造用炭素鋼を用いることができるが、特に、Ｓ４５Ｃ、Ｓ５０Ｃ、Ｓ５５Ｃ等、含有炭素量が０．４２重量％以上のものを用いる場合には、軸受鋼や浸炭鋼等の軸受用鋼からなる転がり軸受にほぼ匹敵する寿命を発揮することができる。
また、前記ブランクＢの焼入は高周波焼入で行ってもよく、この場合には、少なくとも軌道部１ｃを焼入硬化させればよい。
さらに、この発明の製造方法は、転がり軸受の内輪だけでなく、外輪の製造方法としても勿論適用して実施することができる。
また、この発明は、例えば鉄鋼機械用のドライブシャフトに用いられる十字継手の内輪としての十字軸や外輪としてのカップのような、高圧条件で使用される軌道部を備える種々の軸受軌道部材の製造方法として好適に用いられる。
【００１２】
【発明の効果】
以上のように、請求項１記載の軸受軌道部材の製造方法によれば、軌道部材の軌道部にローラバニシング加工を施して、軌道部の表面から少なくとも０．２ｍｍの深さの硬さをＨｖ８００以上にしているので、軌道部に残留圧縮応力を付与し、軌道部の表面の粗さを向上させ得る点と相まって、ローラバニシング加工を施していない従来品と比べて軌道部の疲労強度を高めることができ、ひいては軌道部材の長寿命化を図ることができる。
【００１３】
請求項２記載の軸受軌道部材の製造方法によれば、安価な材料で軸受用鋼からなる転がり軸受にほぼ匹敵する寿命を確保することができる。
請求項３記載の軸受軌道部材の製造方法によれば、従来品と比べて軌道部の疲労強度をより効果的に高めることができ、軌道部材の長寿命化をより効果的に図ることができる。
【図面の簡単な説明】
【図１】この発明の軸受軌道部材の製造方法の一実施形態を示す工程図である。
【図２】軌道部の表面からの各深さにおける硬さを測定した結果を示すグラフ図である。
【図３】軌道部の表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　　　内輪
１ｃ　　軌道部
Ｂ　　　ブランク[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a bearing race member made of carbon steel for machine structure.
[0002]
[Prior Art and Problems to be Solved by the Invention]
Conventionally, as a material of a raceway member such as a raceway of a rolling bearing, bearing steel such as bearing steel or carburized steel is generally used. However, since the bearing steel is expensive, there is a problem that the manufacturing cost of the rolling bearing is high. In view of this, a track member is partially formed of carbon steel for machine structure such as S45C and S55C, which are relatively inexpensive. However, in this case, the quenching hardness of the raceway portion is lower than that of the bearing steel, and the fatigue strength thereof cannot be sufficiently ensured, so that there is a problem that the life of the raceway member is short.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a bearing race member capable of extending the life of a bearing race member made of carbon steel for machine structure.
[0003]
[Means for Solving the Problems]
The method for manufacturing a bearing race member of the present invention for achieving the above object is to heat-treat a blank for a race member made of carbon steel for machine structure processed into a predetermined shape, and after at least hardening the race portion, The track portion is finished by turning or grinding, and the track portion is subjected to roller burnishing to harden a hardness of at least 0.2 mm from the surface of the track portion to Hv800 or more (claim). Item 1).
[0004]
According to this method for manufacturing a bearing race member, the raceway portion of the raceway member is subjected to roller burnishing, and the hardness at a depth of at least 0.2 mm from the surface of the raceway portion is set to Hv800 or more. In addition to the residual compressive stress generated in the raceway due to the processing and the improvement in the surface roughness, the fatigue strength of the raceway can be increased as compared with the conventional product without roller burnishing.
[0005]
In the manufacturing method of the bearing race member, carbon steel for machine structural use having a carbon content of 0.42% by weight or more may be used (claim 2), and in this case, a fatigue almost equal to conventional bearing steel is used. It can demonstrate strength.
In the method of manufacturing a bearing race member, it is preferable that a residual compressive stress at a depth of at least 0.15 mm from the surface of the race portion be 800 MPa or more by the roller burnishing process. In this case, the fatigue strength of the track portion can be more effectively increased as compared with the conventional product.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a process chart showing a method for manufacturing a bearing race member according to an embodiment of the present invention. This manufacturing method is applied to the manufacture of the inner race 1 as a raceway member of a deep groove ball bearing. First, a ring material A (see FIG. 1A) made of S55C which is carbon steel for machine structure is turned. By processing, the end face 1a, the outer circumference 1b, the track portion 1c, the inner circumference 1d, and the like are processed into a predetermined shape (see FIG. 1B). Next, the turned blank B is heat-treated by so-called quenching to harden it to a hardness of about 55 HRC (see FIG. 1C). Thereafter, the end face 1a, the track portion 1c, and the inner circumference 1d of the blank B, on which the heat treatment has been completed, are finished to a predetermined accuracy by grinding (see FIG. 1D).
[0007]
When finishing by grinding is completed, roller burnishing (deep rolling) is performed on the surface of the track portion 1c (see FIG. 1 (e)). In this roller burnishing process, a ceramic mirror ball C held by hydraulic pressure is moved along the axial cross section of the raceway portion 1c while being pressed against the surface of the raceway portion 1c with strong pressure to make rolling contact. In this roller burnishing, the hardness at a depth of at least 0.2 mm from the surface of the track portion 1c is hardened to Hv800 or more, and the residual compressive stress at a depth of at least 0.15 mm from the surface of the track portion 1c is reduced. Processing conditions such as burnishing amount and pressure are selected so that the residual compressive stress is 800 MPa or more even at a depth of at least 0.2 mm from the surface, at least 800 MPa.
[0008]
FIG. 2 is a graph showing the results of measuring the hardness at each depth from the surface of the track portion 1c after the roller burnishing process. FIG. 3 is a graph showing the residual compression at each depth from the surface of the track portion 1c. It is a graph which shows the result of having measured stress. In each of these figures, for comparison, the measurement results of the track portion subjected to induction hardening and the track portion subjected to shot peening are also shown.
[0009]
As is clear from FIG. 2, the track portion 1c after the roller burnishing has a hardness of Hv800 or more at least at a depth of 0.2 mm from the surface thereof, and is higher than the induction hardened product and the shot peened product. Is also significantly harder. As is clear from FIG. 3, the track portion 1c has a residual compressive stress of 800 MPa or more at a depth of at least 0.15 mm from the surface thereof, and is about twice as large as the shot peened product. Work hardening has occurred up to the depth.
Further, the surface roughness of the track portion 1c can be reduced by the roller burnishing process. According to the test of the inventor of the present invention, it has been confirmed that the surface roughness can be reduced to 1/2 or less of the maximum height roughness (Rmax) before processing.
[0010]
The inner ring 1 obtained by the above manufacturing method has a hardness of at least 0.2 mm from the surface of the raceway portion 1c hardened to Hv800 or more by roller burnishing, so that the surface of the raceway portion 1c has a rough surface. In combination with the point that the track portion 1c becomes smaller, the fatigue strength of the raceway portion 1c can be effectively increased as compared with the conventional product without roller burnishing. In particular, in the embodiment, since the residual compressive stress at a depth of at least 0.15 mm from the surface of the raceway portion 1c is 800 MPa or more, the fatigue strength of the raceway portion 1c can be more effectively increased. . Therefore, the life of the deep groove ball bearing incorporating the inner ring 1 can be greatly extended as compared with the conventional product. Specifically, the inner ring 1 was applied to the inner ring of the bearing model number 6206, and a life test was performed in clean oil. As a result, a life almost equivalent to that of the same model number bearing made of bearing steel (SUJ-2) was exhibited. It is confirmed that it is possible.
[0011]
As the material of the raceway member used in the present invention, various carbon steels for mechanical structures can be used. Particularly, when a material having a carbon content of 0.42% by weight or more, such as S45C, S50C, S55C, is used. Can exhibit a life almost equivalent to a rolling bearing made of bearing steel such as bearing steel or carburized steel.
The quenching of the blank B may be performed by induction hardening. In this case, at least the track portion 1c may be quenched and hardened.
Further, the manufacturing method of the present invention can be applied and practiced not only as a method of manufacturing the outer ring but also of the inner ring of the rolling bearing.
The present invention is also directed to the manufacture of various bearing race members having a race portion used under high pressure conditions, such as a cross shaft as an inner ring of a cross joint used for a drive shaft for a steel machine and a cup as an outer ring. It is suitably used as a method.
[0012]
【The invention's effect】
As described above, according to the method for manufacturing a bearing race member according to the first aspect, the raceway portion of the raceway member is subjected to roller burnishing to have a hardness of at least 0.2 mm from the surface of the raceway portion with a hardness of Hv800. As described above, the residual compressive stress is applied to the raceway portion, and the surface roughness of the raceway portion can be improved, and the fatigue strength of the raceway portion is increased as compared with the conventional product without roller burnishing. As a result, the life of the track member can be extended.
[0013]
According to the method of manufacturing a bearing race member according to the second aspect, it is possible to secure a life almost equal to that of a rolling bearing made of bearing steel with an inexpensive material.
According to the method of manufacturing a bearing race member according to the third aspect, the fatigue strength of the race portion can be more effectively increased as compared with the conventional product, and the life of the race member can be more effectively extended. .
[Brief description of the drawings]
FIG. 1 is a process chart showing one embodiment of a method for manufacturing a bearing race member of the present invention.
FIG. 2 is a graph showing the results of measuring the hardness at each depth from the surface of a track portion.
FIG. 3 is a graph showing the results of measuring residual compressive stress at each depth from the surface of a raceway.
[Explanation of symbols]
1 Inner ring 1c Track section B Blank

Claims (3)

所定形状に加工した機械構造用炭素鋼からなる軌道部材用のブランクを熱処理して、少なくとも軌道部を硬化させた後、当該軌道部を旋削又は研削によって仕上げ、さらに当該軌道部にローラバニシング加工を施して、軌道部の表面から少なくとも０．２ｍｍの深さの硬さをＨｖ８００以上に加工硬化させることを特徴とする軸受軌道部材の製造方法。A blank for a track member made of carbon steel for machine structure processed into a predetermined shape is heat-treated, and after at least the track portion is hardened, the track portion is finished by turning or grinding, and further, the track portion is subjected to roller burnishing. And a work hardening at a depth of at least 0.2 mm from the surface of the raceway portion to Hv800 or more. 含有炭素量が０．４２重量％以上の機械構造用炭素鋼を用いる請求項１記載の軸受軌道部材の製造方法。The method for producing a bearing race member according to claim 1, wherein carbon steel for machine structural use having a carbon content of 0.42% by weight or more is used. 前記ローラバニシング加工によって、軌道部の表面から少なくとも０．１５ｍｍの深さの残留圧縮応力を、８００ＭＰａ以上にする請求項１記載の軸受軌道部材の製造方法。2. The method of manufacturing a bearing race member according to claim 1, wherein the residual burn stress at a depth of at least 0.15 mm from the surface of the race portion is made 800 MPa or more by the roller burnishing process. 3.

Images