JP7731384B2 - Rolling bearings - Google Patents
Rolling bearingsInfo
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- JP7731384B2 JP7731384B2 JP2023001831A JP2023001831A JP7731384B2 JP 7731384 B2 JP7731384 B2 JP 7731384B2 JP 2023001831 A JP2023001831 A JP 2023001831A JP 2023001831 A JP2023001831 A JP 2023001831A JP 7731384 B2 JP7731384 B2 JP 7731384B2
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Description
本発明は、転がり軸受に関する。 The present invention relates to a rolling bearing.
特開２０１１－７２３４号公報（特許文献１）は、第１の軌道面を有する内輪と、第２の軌道面を有する外輪と、転動面を有しかつ内輪の外輪との間に配置された転動体とを備える転がり軸受を開示している。 JP 2011-7234 A (Patent Document 1) discloses a rolling bearing comprising an inner ring having a first raceway surface, an outer ring having a second raceway surface, and rolling elements having rolling surfaces and disposed between the inner ring and the outer ring.
転がり軸受の使用中に、内輪と転動体との間の接触応力が内輪と転動体とに作用し続けるとともに、外輪と転動体との間の接触応力が外輪と転動体とに作用し続ける。これらの接触応力は、第１の軌道面、第２の軌道面及び転動面の少なくとも１つに疲労亀裂を発生させる。転がり軸受を長期間使用すると、疲労亀裂が進展して、第１の軌道面、第２の軌道面及び転動面の少なくとも１つの一部が剥離する。この剥離は、表面起点型剥離と呼ばれる。本発明の目的は、第１の軌道面、第２の軌道面及び転動面の少なくとも１つに表面起点型剥離が発生することを抑制して、長い寿命を有する転がり軸受を提供することである。 During use of a rolling bearing, contact stresses between the inner ring and rolling elements continue to act on the inner ring and rolling elements, and contact stresses between the outer ring and rolling elements continue to act on the outer ring and rolling elements. These contact stresses cause fatigue cracks to occur in at least one of the first raceway surface, second raceway surface, and rolling surface. When the rolling bearing is used over an extended period of time, the fatigue cracks propagate, causing flaking of at least one of the first raceway surface, second raceway surface, and rolling surface. This flaking is called surface-initiated flaking. The object of the present invention is to provide a rolling bearing with a long life by suppressing the occurrence of surface-initiated flaking in at least one of the first raceway surface, second raceway surface, and rolling surface.
本発明の転がり軸受は、希薄潤滑条件で使用される転がり軸受である。本発明の転がり軸受は、内輪と、内輪の外周側に配置された外輪と、内輪と外輪との間に配置される複数の転動体とを備える。内輪は、第１の軌道面を有している。外輪は、第１の軌道面に対向する第２の軌道面を有している。複数の転動体の各々は、第１の軌道面および第２の軌道面に接触する転動面を有している。第１の軌道面は、複数の転動体が接触する内輪の表面である。第２の軌道面は、複数の転動体が接触する外輪の表面である。転動面は、第１の軌道面及び第２の軌道面に接触する転動体の表面である。第１の軌道面、第２の軌道面及び転動面の少なくとも１つにおける第１のミーゼス応力は、第１の軌道面、第２の軌道面及び転動面の少なくとも１つを構成する材料の降伏応力よりも小さい。第１の軌道面、第２の軌道面及び転動面の少なくとも１つにおける第１のミーゼス応力は、第１の軌道面、第２の軌道面及び転動面の少なくとも１つを有する内輪、外輪及び複数の転動体の各々の少なくとも１つの第２のミーゼス応力よりも小さい。第２のミーゼス応力は、内輪、外輪及び複数の転動体の各々の少なくとも１つの内部におけるミーゼス応力の最大値である。 The rolling bearing of the present invention is a rolling bearing used under lean lubrication conditions. The rolling bearing of the present invention includes an inner ring, an outer ring arranged on the outer periphery of the inner ring, and a plurality of rolling elements arranged between the inner ring and the outer ring. The inner ring has a first raceway surface. The outer ring has a second raceway surface opposite the first raceway surface. Each of the plurality of rolling elements has a rolling surface in contact with the first raceway surface and the second raceway surface. The first raceway surface is a surface of the inner ring with which the plurality of rolling elements contact. The second raceway surface is a surface of the outer ring with which the plurality of rolling elements contact. The rolling surface is a surface of the rolling element that contacts the first raceway surface and the second raceway surface. The first von Mises stress in at least one of the first raceway surface, the second raceway surface, and the rolling surface is smaller than the yield stress of a material constituting at least one of the first raceway surface, the second raceway surface, and the rolling surface. The first von Mises stress in at least one of the first raceway surface, the second raceway surface, and the rolling surface is smaller than the second von Mises stress in at least one of the inner ring, the outer ring, and the plurality of rolling elements having at least one of the first raceway surface, the second raceway surface, and the rolling surface, and the second von Mises stress is the maximum value of the von Mises stress in at least one of the inner ring, the outer ring, and the plurality of rolling elements.
本発明の転がり軸受によれば、第１の軌道面、第２の軌道面及び転動面の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受が提供され得る。 The rolling bearing of the present invention can suppress the occurrence of surface-initiated flaking on at least one of the first raceway surface, the second raceway surface, and the rolling surface, thereby providing a rolling bearing with a long life.
以下、図面を参照して、本発明の実施の形態について説明する。なお、以下の図面において同一または相当する部分には同一の参照番号を付し、その説明は繰返さない。 Embodiments of the present invention will now be described with reference to the drawings. Note that identical or corresponding parts in the following drawings will be designated by the same reference numerals, and their descriptions will not be repeated.
（実施の形態１）
図１から図８を参照して、実施の形態１に係る転がり軸受１を説明する。図１及び図２に示されるように、本実施の形態の転がり軸受１は、内輪３と、外輪６と、複数の転動体１０とを備える。内輪３と、外輪６と、複数の転動体１０とは、例えば、軸受鋼のような鋼で作られている。内輪３と外輪６と複数の転動体１０とを構成する鋼は、ＪＩＳ規格（ＪＩＳ４８０５：２００８）に定められる高クロム軸受鋼であってもよい。内輪３と外輪６と複数の転動体１０とを構成する鋼は、ＪＩＳ規格に定められるＳＵＪ２鋼材であってもよい。
(Embodiment 1)
A rolling bearing 1 according to a first embodiment will be described with reference to FIGS. 1 to 8 . As shown in FIGS. 1 and 2 , the rolling bearing 1 of this embodiment includes an inner ring 3, an outer ring 6, and a plurality of rolling elements 10. The inner ring 3, the outer ring 6, and the plurality of rolling elements 10 are made of steel such as bearing steel. The steel constituting the inner ring 3, the outer ring 6, and the plurality of rolling elements 10 may be high-chromium bearing steel as specified in the JIS standard (JIS 4805:2008). The steel constituting the inner ring 3, the outer ring 6, and the plurality of rolling elements 10 may be SUJ2 steel as specified in the JIS standard.
内輪３は、第１の軌道面４を有している。外輪６は、第１の軌道面４に対向する第２の軌道面７を有している。外輪６は、内輪３の外周側に配置されている。複数の転動体１０は、内輪３と外輪６との間に配置されている。複数の転動体１０の各々は、第１の軌道面４および第２の軌道面７に接触する転動面１１を有している。複数の転動体１０は複数のころであってもよい。転がり軸受１は、ころ軸受であってもよい。転がり軸受１は、複数の転動体１０を保持する保持器１５をさらに備えてもよい。 The inner ring 3 has a first raceway surface 4. The outer ring 6 has a second raceway surface 7 opposing the first raceway surface 4. The outer ring 6 is arranged on the outer peripheral side of the inner ring 3. A plurality of rolling elements 10 are arranged between the inner ring 3 and the outer ring 6. Each of the plurality of rolling elements 10 has a rolling surface 11 that contacts the first raceway surface 4 and the second raceway surface 7. The plurality of rolling elements 10 may be a plurality of rollers. The rolling bearing 1 may be a roller bearing. The rolling bearing 1 may further include a cage 15 that holds the plurality of rolling elements 10.
外輪６は、複数の転動体１０を介して、内輪３に対して、軸２を中心に回転し得る。外輪６が内輪３に対して軸２を中心に回転している間、転がり軸受１には潤滑油が供給されてもよい。本実施の形態の転がり軸受１は、特に限定されないが、希薄潤滑条件（低Λ条件）下で使用されてもよい。希薄潤滑条件（低Λ条件）は、式（１）で定義される油膜パラメータΛが１以下となる条件である。 The outer ring 6 can rotate about the shaft 2 relative to the inner ring 3 via multiple rolling elements 10. While the outer ring 6 rotates about the shaft 2 relative to the inner ring 3, lubricating oil may be supplied to the rolling bearing 1. The rolling bearing 1 of this embodiment may be used under lean lubrication conditions (low Λ conditions), although this is not particularly limited. Lean lubrication conditions (low Λ conditions) are conditions under which the oil film parameter Λ defined by equation (1) is 1 or less.
式（１）において、ｈminは最小油膜厚さを表し、Ｒq1は第１の軌道面４または第２の軌道面７の二乗平均粗さを表し、Ｒq2は転動面１１の二乗平均粗さを表す。 In formula (1), h min represents the minimum oil film thickness, R q1 represents the root mean square roughness of the first raceway surface 4 or the second raceway surface 7 , and R q2 represents the root mean square roughness of the rolling surface 11 .
内輪３、外輪６及び各転動体１０の少なくとも１つの転がり軸受１の軸方向（ｙ方向）の第１の曲率半径は、内輪３、外輪６及び各転動体１０の少なくとも１つの転がり軸受１の周方向（ｘ方向）の第２の曲率半径と異なっている。本実施の形態では、内輪３の軸方向（ｙ方向）の第１の曲率半径は、内輪３の周方向（ｘ方向）の第２の曲率半径と異なっている。外輪６の軸方向（ｙ方向）の第１の曲率半径は、外輪６の周方向（ｘ方向）の第２の曲率半径と異なっている。各転動体１０の軸方向（ｙ方向）の第１の曲率半径は、各転動体１０の周方向（ｘ方向）の第２の曲率半径と異なっている。特定的には、内輪３の軸方向（ｙ方向）の第１の曲率半径は、内輪３の周方向（ｘ方向）の第２の曲率半径より大きくてもよい。外輪６の軸方向（ｙ方向）の第１の曲率半径は、外輪６の周方向（ｘ方向）の第２の曲率半径より大きくてもよい。各転動体１０の軸方向（ｙ方向）の第１の曲率半径は、各転動体１０の周方向（ｘ方向）の第２の曲率半径より大きくてもよい。 The first radius of curvature in the axial direction (y direction) of at least one rolling bearing 1 of the inner ring 3, outer ring 6, and each rolling element 10 is different from the second radius of curvature in the circumferential direction (x direction) of at least one rolling bearing 1 of the inner ring 3, outer ring 6, and each rolling element 10. In this embodiment, the first radius of curvature in the axial direction (y direction) of the inner ring 3 is different from the second radius of curvature in the circumferential direction (x direction) of the inner ring 3. The first radius of curvature in the axial direction (y direction) of the outer ring 6 is different from the second radius of curvature in the circumferential direction (x direction) of the outer ring 6. The first radius of curvature in the axial direction (y direction) of each rolling element 10 is different from the second radius of curvature in the circumferential direction (x direction) of each rolling element 10. Specifically, the first radius of curvature in the axial direction (y direction) of the inner ring 3 may be larger than the second radius of curvature in the circumferential direction (x direction) of the inner ring 3. The first radius of curvature in the axial direction (y direction) of the outer ring 6 may be larger than the second radius of curvature in the circumferential direction (x direction) of the outer ring 6. The first radius of curvature in the axial direction (y direction) of each rolling element 10 may be larger than the second radius of curvature in the circumferential direction (x direction) of each rolling element 10.
第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの内輪３及び外輪６の軸方向（ｙ方向）における第１の残留圧縮応力σy0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの内輪３及び外輪６の周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きい。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は減少する。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを構成する材料の降伏応力よりも小さくなる。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得る。本明細書において、相当応力は、ミーゼス（Mises）応力を意味する。 The first residual compressive stress σ y0 in the axial direction (y direction) of the inner ring 3 and outer ring 6 of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is greater than the second residual compressive stress σ x0 in the circumferential direction (x direction) of the inner ring 3 and outer ring 6 of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. Therefore, the first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is reduced. The first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is smaller than the yield stress of the material constituting at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The occurrence of surface-initiated flaking in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed. In this specification, equivalent stress means Mises stress.
これに対し、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0が、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを構成する材料の降伏応力より大きいとき、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに塑性変形が発生する。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに、疲労亀裂が発生して、表面起点型剥離が発生する。 In contrast, when the first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is greater than the yield stress of the material that constitutes at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11, plastic deformation occurs in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. A fatigue crack initiates in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11, causing surface-initiated spalling.
以下、実施例１、実施例２及び比較例１－５を参照して、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの軸方向（ｙ方向）における第１の残留圧縮応力σy0を、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きくすることによって、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0が減少することを示す。 Hereinafter, with reference to Examples 1 and 2 and Comparative Examples 1 to 5, it will be shown that by making the first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surfaces 4, the second raceway surfaces 7 and the rolling surfaces 11 larger than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surfaces 4, the second raceway surfaces 7 and the rolling surfaces 11, the first equivalent stress σ e0 in at least one of the first raceway surfaces 4, the second raceway surfaces 7 and the rolling surfaces 11 decreases.
内輪３と各転動体１０との間の接触、及び、外輪６と各転動体１０との間の接触は、ヘルツ接触とみなすことができる。内輪３と各転動体１０との間の接触面、及び、外輪６と各転動体１０との間の接触面は、長半径ａ及び短半径ｂを有する楕円形の接触面とみなすことができる。長半径ａは、接触楕円の長軸方向における半径を意味し、短半径ｂは、接触楕円の短軸方向における半径を意味する。接触楕円の長軸方向は、転がり軸受１の軸方向（ｙ方向）であり、接触楕円の短軸方向は、転がり軸受１の周方向（ｘ方向）である。 The contact between the inner ring 3 and each rolling element 10, and the contact between the outer ring 6 and each rolling element 10, can be considered to be Hertzian contact. The contact surfaces between the inner ring 3 and each rolling element 10, and the contact surfaces between the outer ring 6 and each rolling element 10, can be considered to be elliptical contact surfaces with major radius a and minor radius b. The major radius a refers to the radius of the contact ellipse in the major axis direction, and the minor radius b refers to the radius of the contact ellipse in the minor axis direction. The major axis direction of the contact ellipse is the axial direction (y direction) of the rolling bearing 1, and the minor axis direction of the contact ellipse is the circumferential direction (x direction) of the rolling bearing 1.
実施例１、実施例２及び比較例１－５では、ヘルツの理論を用いて、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを有する内輪３、外輪６及び各転動体１０の少なくとも１つに生じる相当応力をシミュレーションした。具体的には、転動面１１と第１の軌道面４及び第２の軌道面７の少なくとも１つとの間に作用する最大接触面圧Ｐmaxが３．０ＧＰａであり、短半径ｂが１ｍｍであり、かつ、内輪３、外輪６及び各転動体１０の少なくとも１つの少なくとも１つが表１及び表２に示される残留圧縮応力分布を有する場合において、内輪３、外輪６及び各転動体１０の少なくとも１つの相当応力をシミュレーションした。 In Examples 1 and 2 and Comparative Examples 1 to 5, Hertz's theory was used to simulate the equivalent stress occurring in at least one of the inner ring 3, outer ring 6, and each rolling element 10, which have at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. Specifically, the equivalent stress in at least one of the inner ring 3, outer ring 6, and each rolling element 10 was simulated when the maximum contact surface pressure P max acting between the rolling surface 11 and at least one of the first raceway surface 4 and second raceway surface 7 was 3.0 GPa, the minor radius b was 1 mm, and at least one of the inner ring 3, outer ring 6, and each rolling element 10 had the residual compressive stress distribution shown in Tables 1 and 2.
表１に示されるように、実施例１では、内輪３、外輪６及び各転動体１０の少なくとも１つの周方向（ｘ方向）の残留圧縮応力σxは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図３に示される分布Ａを有している。実施例１では、内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図３に示される分布Ｂを有している。図３の縦軸における負号は、内輪３、外輪６及び各転動体１０の少なくとも１つに付与される応力が圧縮応力であることを意味する。 As shown in Table 1, in Example 1, the residual compressive stress σ x in the circumferential direction (x direction) of at least one of the inner ring 3, outer ring 6, and each rolling element 10 has distribution A shown in Figure 3 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In Example 1, the residual compressive stress σ y in the axial direction (y direction) of at least one of the inner ring 3, outer ring 6, and each rolling element 10 has distribution B shown in Figure 3 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. The negative sign on the vertical axis in Figure 3 means that the stress applied to at least one of the inner ring 3, outer ring 6, and each rolling element 10 is compressive stress.
実施例１では、内輪３、外輪６及び各転動体１０の少なくとも１つに異方的な残留圧縮応力が付与されている。具体的には、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの軸方向（ｙ方向）における第１の残留圧縮応力σy0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きい。本明細書において、圧縮応力が大きいことは、圧縮応力の絶対値が大きいことを意味する。 In Example 1, an anisotropic residual compressive stress is imparted to at least one of the inner ring 3, the outer ring 6, and each rolling element 10. Specifically, the first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is larger than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. In this specification, a large compressive stress means that the absolute value of the compressive stress is large.
さらに、図３の分布Ａ及び分布Ｂに示されるように、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの表層領域において、軸方向（ｙ方向）における残留圧縮応力σyは、周方向（ｘ方向）における残留圧縮応力σxよりも大きい。内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）における残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、内輪３、外輪６及び各転動体１０の少なくとも１つの表面（すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つ）で最大となってもよい。 3 , the residual compressive stress σy in the axial direction (y direction) is greater than the residual compressive stress σx in the circumferential direction (x direction) in the surface layer region of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The residual compressive stress σy in the axial direction (y direction) of at least one of the inner ring 3, the outer ring 6, and each rolling element 10 may be maximum in the thickness direction of at least one of the inner ring 3, the outer ring 6, and each rolling element 10 on at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10 (i.e., at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11).
これに対し、表１に示されるように、比較例１では、内輪３、外輪６及び各転動体１０には、残留圧縮応力は付与されていない。比較例２では、内輪３、外輪６及び各転動体１０の少なくとも１つの周方向（ｘ方向）の残留圧縮応力σx及び軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図３に示される分布Ａを有している。比較例３では、内輪３、外輪６及び各転動体１０の少なくとも１つの周方向（ｘ方向）の残留圧縮応力σx及び軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図３に示される分布Ｂを有している。比較例２及び比較例３では、内輪３、外輪６及び各転動体１０の少なくとも１つに等方的な残留圧縮応力σx，σyが付与されている。 In contrast, as shown in Table 1, in Comparative Example 1, no residual compressive stress is imparted to the inner ring 3, outer ring 6, and each rolling element 10. In Comparative Example 2, the circumferential (x-direction) residual compressive stress σx and the axial (y-direction) residual compressive stress σy of at least one of the inner ring 3, outer ring 6, and each rolling element 10 have distribution A shown in Figure 3 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In Comparative Example 3, the circumferential (x-direction) residual compressive stress σx and the axial (y-direction) residual compressive stress σy of at least one of the inner ring 3, outer ring 6, and each rolling element 10 have distribution B shown in Figure 3 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In Comparative Examples 2 and 3, isotropic residual compressive stresses σx and σy are imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10.
図４に示されるように、内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域における実施例１の相当応力は、表層領域における比較例２及び比較例３の相当応力よりも低い。内輪３、外輪６及び各転動体１０の少なくとも１つに付与される残留圧縮応力は、内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域において、内輪３、外輪６及び各転動体１０の少なくとも１つに作用する相当応力を減少させる。本明細書において、表層領域は、内輪３、外輪６及び各転動体１０の少なくとも１つの表面（すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つ）から、相当応力が極小となる深さまでの領域を意味する。図４において、横軸は、接触楕円の短半径ｂで規格化された、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向の位置ｚ／ｂを示す。表層領域は、例えば、ｚ／ｂが０．２以下である領域であってもよい。表層領域は、例えば、内輪３、外輪６及び各転動体１０の少なくとも１つの表面（すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つ）から５０μｍの深さまでの領域であってもよい。 As shown in Figure 4, the equivalent stress in Example 1 in the surface layer region of at least one of the inner ring 3, outer ring 6, and each rolling element 10 is lower than the equivalent stress in the surface layer region of Comparative Examples 2 and 3. The residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10 reduces the equivalent stress acting on at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the surface layer region of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In this specification, the surface layer region refers to the region from the surface of at least one of the inner ring 3, outer ring 6, and each rolling element 10 (i.e., at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11) to the depth where the equivalent stress is minimal. In Figure 4, the horizontal axis represents the position z/b in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10, normalized by the minor radius b of the osculating ellipse. The surface region may be, for example, a region where z/b is 0.2 or less. The surface region may be, for example, a region extending to a depth of 50 μm from the surface of at least one of the inner ring 3, outer ring 6, and rolling elements 10 (i.e., at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11).
内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域は、内輪３、外輪６及び各転動体１０の少なくとも１つの表面、すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを含む。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける実施例１の第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける比較例２及び比較例３の第１の相当応力よりも低い。図４において、位置ｚ／ｂ＝０は、内輪３、外輪６及び各転動体１０の少なくとも１つの表面、すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを表す。 At least one surface region of the inner ring 3, the outer ring 6, and each rolling element 10 includes at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10, i.e., at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The first equivalent stress σ e0 of Example 1 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is lower than the first equivalent stress of Comparative Examples 2 and 3 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. In Figure 4, the position z/b = 0 represents at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10, i.e., at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11.
表層領域において、実施例１の相当応力及び第１の相当応力σe0が、それぞれ、表層領域における比較例２及び比較例３の相当応力及び第１の相当応力よりも低くなる理由は、以下のように考えられる。軸方向（ｙ方向）における内輪３、外輪６及び各転動体１０の少なくとも１つの第１の曲率半径は、周方向（ｘ方向）における内輪３、外輪６及び各転動体１０の少なくとも１つの第２の曲率半径と異なっている。そのため、軸方向（ｙ方向）における内輪３と各転動体１０との間の接触応力は、周方向（ｘ方向）における内輪３と各転動体１０との間の接触応力と異なる。軸方向（ｙ方向）における外輪６と各転動体１０との間の接触応力は、周方向（ｘ方向）における外輪６と各転動体１０との間の接触応力と異なる。実施例１の異方的な残留圧縮応力は、比較例２及び比較例３の等方的な残留圧縮応力よりも、内輪３と各転動体１０との間の異方的な接触応力と外輪６と各転動体１０との間の異方的な接触応力とに、より効果的に対処し得る。 The reason why the equivalent stress and first equivalent stress σ e0 of Example 1 are lower than the equivalent stress and first equivalent stress of Comparative Example 2 and Comparative Example 3 in the surface layer region, respectively, is believed to be as follows: The first radius of curvature of at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the axial direction (y direction) is different from the second radius of curvature of at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the circumferential direction (x direction). Therefore, the contact stress between the inner ring 3 and each rolling element 10 in the axial direction (y direction) is different from the contact stress between the inner ring 3 and each rolling element 10 in the circumferential direction (x direction). The contact stress between the outer ring 6 and each rolling element 10 in the axial direction (y direction) is different from the contact stress between the outer ring 6 and each rolling element 10 in the circumferential direction (x direction). The anisotropic residual compressive stress in Example 1 can more effectively deal with the anisotropic contact stress between the inner ring 3 and each rolling element 10 and the anisotropic contact stress between the outer ring 6 and each rolling element 10 than the isotropic residual compressive stress in Comparative Examples 2 and 3.
こうして、内輪３、外輪６及び各転動体１０の少なくとも１つに付与される異方的な残留圧縮応力は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを含む内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域において、内輪３、外輪６及び各転動体１０の少なくとも１つに作用する相当応力を減少させる。内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域における相当応力は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを構成する材料の降伏応力よりも小さくなる。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得る。 In this way, the anisotropic residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and rolling elements 10 reduces the equivalent stress acting on at least one of the inner ring 3, outer ring 6, and rolling elements 10 in the surface region of at least one of the inner ring 3, outer ring 6, and rolling elements 10, including at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. The equivalent stress in the surface region of at least one of the inner ring 3, outer ring 6, and rolling elements 10 is smaller than the yield stress of the material constituting at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. As a result, the occurrence of surface-initiated flaking on at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11 can be suppressed.
表２に示されるように、実施例２では、内輪３、外輪６及び各転動体１０の少なくとも１つの周方向（ｘ方向）の残留圧縮応力σxは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図５に示される分布Ｃを有している。実施例２では、内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図５に示される分布Ｄを有している。図５の縦軸における負号は、内輪３、外輪６及び各転動体１０の少なくとも１つに付与される応力が圧縮応力であることを意味する。 As shown in Table 2, in Example 2, the residual compressive stress σ x in the circumferential direction (x direction) of at least one of the inner ring 3, outer ring 6, and each rolling element 10 has the distribution C shown in Fig. 5 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In Example 2, the residual compressive stress σ y in the axial direction (y direction) of at least one of the inner ring 3, outer ring 6, and each rolling element 10 has the distribution D shown in Fig. 5 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. The negative sign on the vertical axis in Fig. 5 means that the stress applied to at least one of the inner ring 3, outer ring 6, and each rolling element 10 is compressive stress.
実施例２では、内輪３、外輪６及び各転動体１０の少なくとも１つに異方的な残留圧縮応力が付与されている。具体的には、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの軸方向（ｙ方向）における第１の残留圧縮応力σy0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きい。 In Example 2, an anisotropic residual compressive stress is imparted to at least one of the inner ring 3, the outer ring 6, and each rolling element 10. Specifically, the first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is greater than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11.
さらに、図５の分布Ｃ及び分布Ｄに示されるように、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの表層領域において、軸方向（ｙ方向）における残留圧縮応力σyは、周方向（ｘ方向）における残留圧縮応力σxよりも大きい。内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）における残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、内輪３、外輪６及び各転動体１０の少なくとも１つの内部で最大となってもよい。 5 , the residual compressive stress σy in the axial direction (y direction) is greater than the residual compressive stress σx in the circumferential direction (x direction) in the surface layer region of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The residual compressive stress σy in the axial direction (y direction) of at least one of the inner ring 3, the outer ring 6, and each rolling element 10 may be maximum inside at least one of the inner ring 3, the outer ring 6, and each rolling element 10 in the thickness direction of at least one of the inner ring 3, the outer ring 6, and each rolling element 10.
特定的には、内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）における残留圧縮応力σyが最大となる厚さ方向の位置ｚ／ｂは、０より大きく、０．０３より大きくてもよく、０．０５より大きくてもよい。内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）における残留圧縮応力σyが最大となる厚さ方向の位置ｚ／ｂは、１．００より小さくてもよく、０．９０より小さくてもよく、０．８０より小さくてもよい。 Specifically, the position z/b in the thickness direction at which the residual compressive stress σy in at least one axial direction (y direction) of the inner ring 3, the outer ring 6, and each rolling element 10 is maximized may be greater than 0, and may be greater than 0.03, or may be greater than 0.05. The position z/b in the thickness direction at which the residual compressive stress σy in at least one axial direction (y direction) of the inner ring 3, the outer ring 6, and each rolling element 10 is maximized may be less than 1.00, less than 0.90, or less than 0.80.
これに対し、表２に示されるように、比較例１では、内輪３、外輪６及び各転動体１０には、残留圧縮応力は付与されていない。比較例４では、内輪３、外輪６及び各転動体１０の少なくとも１つの周方向（ｘ方向）の残留圧縮応力σx及び軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図５に示される分布Ｃを有している。比較例５では、内輪３、外輪６及び各転動体１０の少なくとも１つの周方向（ｘ方向）の残留圧縮応力σx及び軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、図５に示される分布Ｄを有している。比較例４及び比較例５では、内輪３、外輪６及び各転動体１０の少なくとも１つに等方的な残留圧縮応力σx，σyが付与されている。 In contrast, as shown in Table 2, in Comparative Example 1, no residual compressive stress was imparted to the inner ring 3, outer ring 6, and each rolling element 10. In Comparative Example 4, the circumferential (x-direction) residual compressive stress σx and the axial (y-direction) residual compressive stress σy of at least one of the inner ring 3, outer ring 6, and each rolling element 10 had the distribution C shown in Figure 5 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In Comparative Example 5, the circumferential (x-direction) residual compressive stress σx and the axial (y-direction) residual compressive stress σy of at least one of the inner ring 3, outer ring 6, and each rolling element 10 had the distribution D shown in Figure 5 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. In Comparative Examples 4 and 5, isotropic residual compressive stresses σx and σy were imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10.
図６に示されるように、内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域における実施例２の相当応力は、表層領域における比較例４及び比較例５の相当応力よりも低い。内輪３、外輪６及び各転動体１０の少なくとも１つに付与される残留圧縮応力は、内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域において、内輪３、外輪６及び各転動体１０の少なくとも１つに作用する相当応力を減少させる。 As shown in Figure 6, the equivalent stress in Example 2 in the surface region of at least one of the inner ring 3, outer ring 6, and each rolling element 10 is lower than the equivalent stress in the surface region of Comparative Examples 4 and 5. The residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10 reduces the equivalent stress acting on at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the surface region of at least one of the inner ring 3, outer ring 6, and each rolling element 10.
内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域は、内輪３、外輪６及び各転動体１０の少なくとも１つの表面、すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを含む。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける実施例２の第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける比較例４及び比較例５の第１の相当応力よりも低い。図４において、位置ｚ／ｂ＝０は、内輪３、外輪６及び各転動体１０の少なくとも１つの表面、すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを表す。 At least one surface region of the inner ring 3, the outer ring 6, and each rolling element 10 includes at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10, i.e., at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The first equivalent stress σ e0 of Example 2 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is lower than the first equivalent stress of Comparative Examples 4 and 5 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. In Figure 4, the position z/b = 0 represents at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10, i.e., at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11.
表層領域において、実施例２の相当応力及び第１の相当応力σe0が、それぞれ、比較例４及び比較例５の相当応力及び第１の相当応力よりも低くなる理由は、以下のように考えられる。軸方向（ｙ方向）における内輪３、外輪６及び各転動体１０の少なくとも１つの第１の曲率半径は、周方向（ｘ方向）における内輪３、外輪６及び各転動体１０の少なくとも１つの第２の曲率半径と異なっている。そのため、軸方向（ｙ方向）における内輪３と各転動体１０との間の接触応力は、周方向（ｘ方向）における内輪３と各転動体１０との間の接触応力と異なる。軸方向（ｙ方向）における外輪６と各転動体１０との間の接触応力は、周方向（ｘ方向）における外輪６と各転動体１０との間の接触応力と異なる。実施例２の異方的な残留圧縮応力は、比較例４及び比較例５の等方的な残留圧縮応力よりも、内輪３と各転動体１０との間の異方的な接触応力と外輪６と各転動体１０との間の異方的な接触応力とに、より効果的に対処し得る。 The reason why the equivalent stress and first equivalent stress σ e0 of Example 2 are lower than the equivalent stress and first equivalent stress of Comparative Example 4 and Comparative Example 5, respectively, in the surface layer region is believed to be as follows: The first radius of curvature of at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the axial direction (y direction) is different from the second radius of curvature of at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the circumferential direction (x direction). Therefore, the contact stress between the inner ring 3 and each rolling element 10 in the axial direction (y direction) is different from the contact stress between the inner ring 3 and each rolling element 10 in the circumferential direction (x direction). The contact stress between the outer ring 6 and each rolling element 10 in the axial direction (y direction) is different from the contact stress between the outer ring 6 and each rolling element 10 in the circumferential direction (x direction). The anisotropic residual compressive stress in Example 2 can more effectively deal with the anisotropic contact stress between the inner ring 3 and each rolling element 10 and the anisotropic contact stress between the outer ring 6 and each rolling element 10 than the isotropic residual compressive stress in Comparative Examples 4 and 5.
こうして、内輪３、外輪６及び各転動体１０の少なくとも１つに付与される異方的な残留圧縮応力は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを含む内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域において、内輪３、外輪６及び各転動体１０の少なくとも１つに作用する相当応力を減少させる。内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域における相当応力は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを構成する材料の降伏応力よりも小さくなる。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得る。 In this way, the anisotropic residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and rolling elements 10 reduces the equivalent stress acting on at least one of the inner ring 3, outer ring 6, and rolling elements 10 in the surface region of at least one of the inner ring 3, outer ring 6, and rolling elements 10, including at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. The equivalent stress in the surface region of at least one of the inner ring 3, outer ring 6, and rolling elements 10 is smaller than the yield stress of the material constituting at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. As a result, the occurrence of surface-initiated flaking on at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11 can be suppressed.
図４及び図６に示される実施例１及び実施例２のように、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを有する内輪３、外輪６及び各転動体１０の少なくとも１つの第２の相当応力σe2よりも小さくてもよい。第２の相当応力σe2は、内輪３、外輪６及び各転動体１０の少なくとも１つの内部における相当応力の最大値である。言い換えると、図７に示される相当応力の比ｎは、１未満であってもよい。本明細書において、相当応力の比ｎは、第２の相当応力σe2に対する第１の相当応力σe0の比ｎで与えられる（ｎ＝σe0／σe2）。 As in Examples 1 and 2 shown in Figures 4 and 6, the first equivalent stress σe0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 may be smaller than the second equivalent stress σe2 in at least one of the inner ring 3, the outer ring 6, and each rolling element 10 having at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The second equivalent stress σe2 is the maximum value of the equivalent stress inside at least one of the inner ring 3, the outer ring 6, and each rolling element 10. In other words, the equivalent stress ratio n shown in Figure 7 may be less than 1. In this specification, the equivalent stress ratio n is given by the ratio n of the first equivalent stress σe0 to the second equivalent stress σe2 (n = σe0 / σe2 ).
第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの内輪３及び外輪６の軸方向（ｙ方向）における第１の残留圧縮応力σy0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの内輪３及び外輪６の周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きい。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は減少して、相当応力の比ｎが１未満となり得る。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを構成する材料の降伏応力よりも小さくなる。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得る。 The first residual compressive stress σ y0 in the axial direction (y direction) of the inner ring 3 and outer ring 6 of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is greater than the second residual compressive stress σ x0 in the circumferential direction (x direction) of the inner ring 3 and outer ring 6 of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. Therefore, the first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is reduced, and the equivalent stress ratio n can become less than 1. The first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 becomes smaller than the yield stress of the material constituting at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The occurrence of surface-initiated flaking on at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling surface 11 can be suppressed.
各転動体１０と内輪３及び外輪６の少なくとも１つとの間に作用する最大接触面圧Ｐmaxに対する第１の残留圧縮応力σy0の比は、－０．７以上であってもよく、－０．６以上であってもよく、－０．５以上であってもよい。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを有する内輪３、外輪６及び各転動体１０の少なくとも１つの第２の相当応力σe2よりも小さくすることができる。各転動体１０と内輪３及び外輪６の少なくとも１つとの間の最大接触面圧Ｐmaxに対する第１の残留圧縮応力σy0の比は、０．０未満であってもよく、－０．１以下であってもよく、－０．２以下であってもよい。 The ratio of the first residual compressive stress σ y0 to the maximum contact pressure P max acting between each rolling element 10 and at least one of the inner ring 3 and the outer ring 6 may be −0.7 or greater, −0.6 or greater, or −0.5 or greater. Therefore, the first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be smaller than the second equivalent stress σ e2 in at least one of the inner ring 3, the outer ring 6, and each rolling element 10 having at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The ratio of the first residual compressive stress σ y0 to the maximum contact pressure P max acting between each rolling element 10 and at least one of the inner ring 3 and the outer ring 6 may be less than 0.0, may be −0.1 or less, or may be −0.2 or less.
残留圧縮応力の異方性αは、１より大きい。残留圧縮応力の異方性αは、第２の残留圧縮応力σx0に対する第１の残留圧縮応力σy0の比で与えられる（α＝σy0／σx0）。残留圧縮応力の異方性αは、１．３以上であってもよく、１．５以上であってもよく、１．７５以上であってもよく、２．０以上であってもよい。残留圧縮応力の異方性αは、特に限定されないが、２０以下であってもよく、１０以下であってもよく、５．０以下であってもよい。 The anisotropy α of the residual compressive stress is greater than 1. The anisotropy α of the residual compressive stress is given by the ratio of the first residual compressive stress σ y0 to the second residual compressive stress σ x0 (α = σ y0 /σ x0 ). The anisotropy α of the residual compressive stress may be 1.3 or more, 1.5 or more, 1.75 or more, or 2.0 or more. The anisotropy α of the residual compressive stress is not particularly limited, but may be 20 or less, 10 or less, or 5.0 or less.
図７に示されるように、残留圧縮応力の異方性αが１より大きくなるにつれて、転がり軸受１に作用する相当応力の比ｎが１未満となる第１の残留圧縮応力σy0の範囲が拡大する。図７の横軸における負号は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに付与される応力が圧縮応力であることを意味する。例えば、残留圧縮応力の異方性αが１．３に等しいとき、１６５０ＭＰａ以下の第１の残留圧縮応力σy0は、第１の相当応力σe0を第２の相当応力σe2よりも低下させることできる。そのため、残留圧縮応力の異方性αを１より大きくすることにより、多様な第１の残留圧縮応力σy0を有するより多くの種類の転がり軸受１において、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0を減少させることができる。より多くの種類の転がり軸受１において、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得る。 As shown in Figure 7, as the anisotropy α of the residual compressive stress increases beyond 1, the range of the first residual compressive stress σy0 in which the ratio n of the equivalent stress acting on the rolling bearing 1 is less than 1 expands. The negative sign on the horizontal axis in Figure 7 means that the stress applied to at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is compressive. For example, when the anisotropy α of the residual compressive stress is equal to 1.3, a first residual compressive stress σy0 of 1650 MPa or less can reduce the first equivalent stress σe0 more than the second equivalent stress σe2 . Therefore, by increasing the anisotropy α of the residual compressive stress beyond 1, the first equivalent stress σe0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be reduced in more types of rolling bearings 1 having various first residual compressive stresses σy0 . In more types of rolling bearings 1 , the occurrence of surface-initiated flaking on at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling surface 11 can be suppressed.
表層領域において、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの軸方向（ｙ方向）における第１の残留圧縮応力σy0を、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きく２つの方法を以下に例示する。第一の方法は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにショットピーニング加工またはバニシング加工を施すことである。 In the surface layer region, two methods are given below to make the first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 larger than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The first method is to subject at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 to shot peening or burnishing.
第二の方法は、転がり軸受１の使用前に、転がり軸受１の通常の使用状態における第２の最大接触面圧よりも高い第１の最大接触面圧で、各転動体１０を内輪３及び外輪６に対して短時間転動させることである。第２の最大接触面圧に対する高い第１の最大接触面圧の比は、１．０よりも大きくてもよく、１．３よりも大きくてもよい。第２の最大接触面圧に対する高い第１の最大接触面圧の比は、特に限定されないが、３．０より小さくてもよく、２．５以下であってもよい。例えば、第１の最大接触面圧は５．６ＧＰａであり、第２の最大接触面圧は３．０ＧＰａであってもよい。例えば、転がり軸受１の使用前に５．６ＧＰａの第１の最大接触面圧で各転動体１０を内輪３及び外輪６に対して転動させることによって、図８に示されるように、内輪３、外輪６及び各転動体１０の少なくとも１つの表面（すなわち、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つ）を含む内輪３、外輪６及び各転動体１０の少なくとも１つの表層領域において、第１の残留圧縮応力σy0を第２の残留圧縮応力σx0よりも大きくすることができる。 The second method is to roll each rolling element 10 against the inner ring 3 and the outer ring 6 for a short time before using the rolling bearing 1 at a first maximum contact pressure that is higher than the second maximum contact pressure in normal use of the rolling bearing 1. The ratio of the high first maximum contact pressure to the second maximum contact pressure may be greater than 1.0 or may be greater than 1.3. The ratio of the high first maximum contact pressure to the second maximum contact pressure is not particularly limited, but may be less than 3.0 or 2.5 or less. For example, the first maximum contact pressure may be 5.6 GPa, and the second maximum contact pressure may be 3.0 GPa. For example, by rolling each rolling element 10 against the inner ring 3 and the outer ring 6 at a first maximum contact surface pressure of 5.6 GPa before use of the rolling bearing 1, as shown in FIG. 8 , it is possible to make the first residual compressive stress σ y0 greater than the second residual compressive stress σ x0 in at least one surface region of the inner ring 3, the outer ring 6, and each rolling element 10, including at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10 (i.e., at least one of the first raceway surface 4 , the second raceway surface 7, and the rolling surface 11) .
本実施の形態の転がり軸受１の効果を説明する。
本実施の形態の転がり軸受１は、内輪３と、内輪３の外周側に配置された外輪６と、内輪３と外輪６との間に配置される複数の転動体１０とを備える。内輪３は、第１の軌道面４を有している。外輪６は、第１の軌道面４に対向する第２の軌道面７を有している。複数の転動体１０の各々は、第１の軌道面４および第２の軌道面７に接触する転動面１１を有している。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの内輪３及び外輪６の軸方向（ｙ方向）における第１の残留圧縮応力σy0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの内輪３及び外輪６の周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きい。
The effects of the rolling bearing 1 of this embodiment will be described.
The rolling bearing 1 of this embodiment comprises an inner ring 3, an outer ring 6 arranged on the outer peripheral side of the inner ring 3, and a plurality of rolling elements 10 arranged between the inner ring 3 and the outer ring 6. The inner ring 3 has a first raceway surface 4. The outer ring 6 has a second raceway surface 7 opposing the first raceway surface 4. Each of the plurality of rolling elements 10 has a rolling surface 11 in contact with the first raceway surface 4 and the second raceway surface 7. A first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 of the inner ring 3 and the outer ring 6 is greater than a second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 of the inner ring 3 and the outer ring 6 .
転がり軸受１の軸方向（ｙ方向）における内輪３、外輪６及び各転動体１０の少なくとも１つの第１の曲率半径は、転がり軸受１の周方向（ｘ方向）における内輪３、外輪６及び各転動体１０の少なくとも１つの第２の曲率半径と異なっている。そのため、転がり軸受１の軸方向（ｙ方向）における内輪３と各転動体１０との間の接触応力は、転がり軸受１の周方向（ｘ方向）における内輪３と各転動体１０との間の接触応力と異なる。転がり軸受１の軸方向（ｙ方向）における外輪６と各転動体１０との間の接触応力は、転がり軸受１の周方向（ｘ方向）における外輪６と各転動体１０との間の接触応力と異なる。 The first radius of curvature of at least one of the inner ring 3, outer ring 6, and rolling elements 10 in the axial direction (y direction) of the rolling bearing 1 is different from the second radius of curvature of at least one of the inner ring 3, outer ring 6, and rolling elements 10 in the circumferential direction (x direction) of the rolling bearing 1. Therefore, the contact stress between the inner ring 3 and each rolling element 10 in the axial direction (y direction) of the rolling bearing 1 is different from the contact stress between the inner ring 3 and each rolling element 10 in the circumferential direction (x direction) of the rolling bearing 1. The contact stress between the outer ring 6 and each rolling element 10 in the axial direction (y direction) of the rolling bearing 1 is different from the contact stress between the outer ring 6 and each rolling element 10 in the circumferential direction (x direction) of the rolling bearing 1.
第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの軸方向（ｙ方向）における第１の残留圧縮応力σy0を、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きくすることによって、異方的な接触応力に効果的に対処し得る。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は減少する。本実施の形態の転がり軸受１によれば、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１が提供され得る。 Anisotropic contact stress can be effectively addressed by making the first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 larger than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is reduced. According to the rolling bearing 1 of this embodiment, the occurrence of surface-initiated flaking in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and a rolling bearing 1 with a long life can be provided.
本実施の形態の転がり軸受１では、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを有する内輪３、外輪６及び各転動体１０の少なくとも１つの第２の相当応力σe2よりも小さくてもよい。第２の相当応力σe2は、内輪３、外輪６及び各転動体１０の少なくとも１つの内部における相当応力の最大値である。本実施の形態の転がり軸受１によれば、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１が提供され得る。 In the rolling bearing 1 of this embodiment, the first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 may be smaller than the second equivalent stress σ e2 in at least one of the inner ring 3, the outer ring 6, and each rolling element 10, which have at least one of the first raceway surface 4 , the second raceway surface 7, and the rolling surface 11. The second equivalent stress σ e2 is the maximum value of the equivalent stress inside at least one of the inner ring 3, the outer ring 6, and each rolling element 10. According to the rolling bearing 1 of this embodiment, the occurrence of surface-initiated flaking in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and a rolling bearing 1 with a long life can be provided.
内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つで最大となってもよい。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに作用する第１の相当応力σe0は減少する。本実施の形態の転がり軸受１によれば、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１が提供され得る。 The residual compressive stress σ y in the axial direction (y direction) of at least one of the inner ring 3, the outer ring 6, and each rolling element 10 may be maximum in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 in the thickness direction of at least one of the inner ring 3, the outer ring 6, and each rolling element 10. Therefore, the first equivalent stress σ e0 acting on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is reduced. According to the rolling bearing 1 of this embodiment, the occurrence of surface-initiated flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and a rolling bearing 1 with a long life can be provided.
内輪３、外輪６及び各転動体１０の少なくとも１つの軸方向（ｙ方向）の残留圧縮応力σyは、内輪３、外輪６及び各転動体１０の少なくとも１つの厚さ方向において、内輪３、外輪６及び各転動体１０の少なくとも１つの内部で最大となってもよい。そのため、内輪３、外輪６及び各転動体１０の少なくとも１つに作用する第１の相当応力σe0は減少する。本実施の形態の転がり軸受１によれば、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１が提供され得る。 The residual compressive stress σ y in the axial direction (y direction) of at least one of the inner ring 3, outer ring 6, and each rolling element 10 may be maximum inside at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. Therefore, the first equivalent stress σ e0 acting on at least one of the inner ring 3, outer ring 6, and each rolling element 10 is reduced. According to the rolling bearing 1 of this embodiment, the occurrence of surface-initiated flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and a rolling bearing 1 with a long life can be provided.
本実施の形態の転がり軸受１では、複数の転動体１０の各々と内輪３及び外輪６の少なくとも１つとの間に作用する最大接触面圧に対する第１の残留圧縮応力σy0の比は、－０．７以上０．０未満であってもよい。そのため、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つにおける第１の相当応力σe0は減少して、第１の相当応力σe0は、内輪３、外輪６及び各転動体１０の少なくとも１つの第２の相当応力σe2よりも小さくすることができる。本実施の形態の転がり軸受１によれば、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１が提供され得る。 In the rolling bearing 1 of this embodiment, the ratio of the first residual compressive stress σ y0 to the maximum contact surface pressure acting between each of the plurality of rolling elements 10 and at least one of the inner ring 3 and the outer ring 6 may be equal to or greater than −0.7 and less than 0.0. As a result, the first equivalent stress σ e0 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is reduced, and the first equivalent stress σ e0 can be made smaller than the second equivalent stress σ e2 of at least one of the inner ring 3, the outer ring 6, and each rolling element 10. According to the rolling bearing 1 of this embodiment, the occurrence of surface-initiated flaking in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and a rolling bearing 1 with a long life can be provided.
本実施の形態の転がり軸受１では、複数の転動体１０は複数のころであってもよい。第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つに付与される異方的な残留圧縮応力は、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つを含む内輪３、外輪６及び各ころの少なくとも１つの表層領域Ｒ1，Ｒ2において、内輪３、外輪６及び各ころの少なくとも１つに作用する相当応力を減少させる。本実施の形態の転がり軸受１によれば、第１の軌道面４、第２の軌道面７及び各ころの転動面１１の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１が提供され得る。 In the rolling bearing 1 of this embodiment, the plurality of rolling elements 10 may be a plurality of rollers. The anisotropic residual compressive stress imparted to at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 reduces the equivalent stress acting on the inner ring 3, the outer ring 6, and at least one of the rollers in the surface layer regions R1 , R2 of the inner ring 3, the outer ring 6, and at least one of the rollers, which include at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. According to the rolling bearing 1 of this embodiment, the occurrence of surface-initiated flaking can be suppressed on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 of each roller, and a rolling bearing 1 with a long life can be provided.
（実施の形態２）
図９及び図１０を参照して、実施の形態２に係る転がり軸受１ｂを説明する。本実施の形態の転がり軸受１ｂは、実施の形態１の転がり軸受１と同様の構成を備えるが、主に以下の点で異なる。
(Embodiment 2)
A rolling bearing 1b according to embodiment 2 will be described with reference to Figures 9 and 10. The rolling bearing 1b of this embodiment has a similar configuration to the rolling bearing 1 of embodiment 1, but differs mainly in the following respects.
本実施の形態の転がり軸受１ｂでは、複数の転動体１０ｂは複数の玉である。転がり軸受１ｂは、深溝玉軸受であってもよい。軸方向（ｙ方向）における各転動体１０ｂの曲率半径は、周方向（ｘ方向）における各転動体１０ｂの曲率半径に実質的に等しい。各転動体１０ｂは、軸方向（ｙ方向）及び周方向（ｘ方向）において、実質的に等方的な形状を有している。 In the rolling bearing 1b of this embodiment, the multiple rolling elements 10b are multiple balls. The rolling bearing 1b may be a deep groove ball bearing. The radius of curvature of each rolling element 10b in the axial direction (y direction) is substantially equal to the radius of curvature of each rolling element 10b in the circumferential direction (x direction). Each rolling element 10b has a substantially isotropic shape in the axial direction (y direction) and the circumferential direction (x direction).
転がり軸受１ｂの軸方向（ｙ方向）における内輪３及び外輪６の少なくとも１つの第１の曲率半径は、転がり軸受１ｂの周方向（ｘ方向）における内輪３及び外輪６の少なくとも１つの第２の曲率半径と異なっている。本実施の形態では、軸方向（ｙ方向）における内輪３の曲率半径は、周方向（ｘ方向）における内輪３の曲率半径と異なっている。軸方向（ｙ方向）における外輪６の曲率半径は、周方向（ｘ方向）における外輪６の曲率半径と異なっている。特定的には、軸方向（ｙ方向）における内輪３の曲率半径は、周方向（ｘ方向）における内輪３の曲率半径より大きくてもよい。軸方向（ｙ方向）における外輪６の曲率半径は、周方向（ｘ方向）における外輪６の曲率半径より大きくてもよい。 The first radius of curvature of at least one of the inner ring 3 and outer ring 6 in the axial direction (y direction) of rolling bearing 1b is different from the second radius of curvature of at least one of the inner ring 3 and outer ring 6 in the circumferential direction (x direction) of rolling bearing 1b. In this embodiment, the radius of curvature of the inner ring 3 in the axial direction (y direction) is different from the radius of curvature of the inner ring 3 in the circumferential direction (x direction). The radius of curvature of the outer ring 6 in the axial direction (y direction) is different from the radius of curvature of the outer ring 6 in the circumferential direction (x direction). Specifically, the radius of curvature of the inner ring 3 in the axial direction (y direction) may be larger than the radius of curvature of the inner ring 3 in the circumferential direction (x direction). The radius of curvature of the outer ring 6 in the axial direction (y direction) may be larger than the radius of curvature of the outer ring 6 in the circumferential direction (x direction).
本実施の形態では、第１の軌道面４及び第２の軌道面７の少なくとも１つを含む内輪３及び外輪６の少なくとも１つの表層領域において、軸方向（ｙ方向）における残留圧縮応力σyは、周方向（ｘ方向）における残留圧縮応力σxよりも大きい。本実施の形態における、内輪３及び外輪６の少なくとも１つの厚さ方向での、軸方向（ｙ方向）の残留圧縮応力σyの分布と周方向（ｘ方向）の残留圧縮応力σxの分布とは、それぞれ、実施の形態１における、内輪３及び外輪６の少なくとも１つの厚さ方向での、軸方向（ｙ方向）の残留圧縮応力σyの分布と周方向（ｘ方向）の残留圧縮応力σxの分布と同様であってもよい。本実施の形態では、転動面１１には、異方的な残留圧縮応力は付与されていない。 In the present embodiment, the residual compressive stress σy in the axial direction (y direction) is greater than the residual compressive stress σx in the circumferential direction (x direction) in at least one surface layer region of the inner ring 3 and the outer ring 6, including at least one of the first raceway surface 4 and the second raceway surface 7. In the present embodiment, the distribution of the residual compressive stress σy in the axial direction (y direction) and the distribution of the residual compressive stress σx in the circumferential direction (x direction) in the thickness direction of at least one of the inner ring 3 and the outer ring 6 may be similar to the distribution of the residual compressive stress σy in the axial direction (y direction) and the distribution of the residual compressive stress σx in the circumferential direction (x direction) in the thickness direction of at least one of the inner ring 3 and the outer ring 6 in Embodiment 1 , respectively. In the present embodiment, no anisotropic residual compressive stress is imparted to the rolling surface 11.
本実施の形態の転がり軸受１ｂは、以下のように、実施の形態１の転がり軸受１と同様の効果を奏する。 The rolling bearing 1b of this embodiment achieves the same effects as the rolling bearing 1 of embodiment 1, as follows:
本実施の形態の転がり軸受１ｂでは、複数の転動体１０ｂ複数の玉である。第１の軌道面４及び第２の軌道面７の少なくとも１つにおいて、軸方向（ｙ方向）における第１の残留圧縮応力σy0は、周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きい。 In the rolling bearing 1b of this embodiment, the plurality of rolling elements 10b are balls. In at least one of the first raceway surfaces 4 and the second raceway surfaces 7, the first residual compressive stress σ y0 in the axial direction (y direction) is greater than the second residual compressive stress σ x0 in the circumferential direction (x direction).
本実施の形態の転がり軸受１ｂでは、転がり軸受１ｂの軸方向（ｙ方向）における内輪３及び外輪６の少なくとも１つの第１の曲率半径は、転がり軸受１ｂの周方向（ｘ方向）における内輪３及び外輪６の少なくとも１つの第２の曲率半径と異なっている。そのため、転がり軸受１ｂの軸方向（ｙ方向）における内輪３と各玉との間の接触応力は、転がり軸受１ｂの周方向（ｘ方向）における内輪３と各玉との間の接触応力と異なる。転がり軸受１ｂの軸方向（ｙ方向）における外輪６と各玉との間の接触応力は、転がり軸受１ｂの周方向（ｘ方向）における外輪６と各玉との間の接触応力と異なる。 In the rolling bearing 1b of this embodiment, the first radius of curvature of at least one of the inner ring 3 and outer ring 6 in the axial direction (y direction) of the rolling bearing 1b is different from the second radius of curvature of at least one of the inner ring 3 and outer ring 6 in the circumferential direction (x direction) of the rolling bearing 1b. Therefore, the contact stress between the inner ring 3 and each ball in the axial direction (y direction) of the rolling bearing 1b is different from the contact stress between the inner ring 3 and each ball in the circumferential direction (x direction) of the rolling bearing 1b. The contact stress between the outer ring 6 and each ball in the axial direction (y direction) of the rolling bearing 1b is different from the contact stress between the outer ring 6 and each ball in the circumferential direction (x direction) of the rolling bearing 1b.
第１の軌道面４及び第２の軌道面７の少なくとも１つの軸方向（ｙ方向）における第１の残留圧縮応力σy0を、第１の軌道面４、第２の軌道面７及び転動面１１の少なくとも１つの周方向（ｘ方向）における第２の残留圧縮応力σx0よりも大きくすることによって、異方的な接触応力に効果的に対処し得る。内輪３及び外輪６の少なくとも１つにおける第１の第１の相当応力σe0は減少する。本実施の形態の転がり軸受１ｂによれば、第１の軌道面４及び第２の軌道面７の少なくとも１つに表面起点型剥離が発生することが抑制され得て、長い寿命を有する転がり軸受１ｂが提供され得る。 Anisotropic contact stress can be effectively addressed by making the first residual compressive stress σ y0 in the axial direction (y direction) of at least one of the first raceway surface 4 and the second raceway surface 7 greater than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. The first equivalent stress σ e0 in at least one of the inner ring 3 and the outer ring 6 is reduced. According to the rolling bearing 1b of this embodiment, the occurrence of surface-initiated flaking on at least one of the first raceway surface 4 and the second raceway surface 7 can be suppressed, and a rolling bearing 1b with a long life can be provided.
今回開示された実施の形態１及び実施の形態２はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The first and second embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.
１，１ｂ 転がり軸受、２ 軸、３ 内輪、４ 第１の軌道面、６ 外輪、７ 第２の軌道面、１０，１０ｂ 転動体、１１ 転動面、１５ 保持器。 1, 1b: rolling bearing, 2: shaft, 3: inner ring, 4: first raceway surface, 6: outer ring, 7: second raceway surface, 10, 10b: rolling elements, 11: rolling surface, 15: cage.
Claims (4)
第１の軌道面を有する内輪と、
前記内輪の外周側に配置された外輪とを備え、前記外輪は、前記第１の軌道面に対向する第２の軌道面を有しており、さらに、
前記内輪と前記外輪との間に配置される複数の転動体を備え、前記複数の転動体の各々は、前記第１の軌道面および前記第２の軌道面に接触する転動面を有しており、
前記第１の軌道面は前記複数の転動体が接触する前記内輪の表面であり、前記第２の軌道面は前記複数の転動体が接触する前記外輪の表面であり、前記転動面は前記第１の軌道面及び前記第２の軌道面に接触する前記転動体の表面であり、
前記第１の軌道面、前記第２の軌道面及び前記転動面の少なくとも１つにおける第１のミーゼス応力は、前記第１の軌道面、前記第２の軌道面及び前記転動面の前記少なくとも１つを構成する材料の降伏応力よりも小さく、
前記第１の軌道面、前記第２の軌道面及び前記転動面の前記少なくとも１つにおける前記第１のミーゼス応力は、前記第１の軌道面、前記第２の軌道面及び前記転動面の前記少なくとも１つを有する前記内輪、前記外輪及び前記複数の転動体の前記各々の少なくとも１つの第２のミーゼス応力よりも小さく、前記第２のミーゼス応力は、前記内輪、前記外輪及び前記複数の転動体の前記各々の前記少なくとも１つの内部におけるミーゼス応力の最大値である、転がり軸受。 A rolling bearing used under lean lubrication conditions, the rolling bearing comprising:
an inner ring having a first raceway surface;
an outer ring disposed on an outer peripheral side of the inner ring, the outer ring having a second raceway surface opposing the first raceway surface; and
a plurality of rolling elements disposed between the inner ring and the outer ring, each of the plurality of rolling elements having a rolling surface in contact with the first raceway surface and the second raceway surface;
the first raceway surface is a surface of the inner ring with which the plurality of rolling elements contact, the second raceway surface is a surface of the outer ring with which the plurality of rolling elements contact, and the rolling surface is a surface of the rolling element that contacts the first raceway surface and the second raceway surface,
a first von Mises stress in at least one of the first raceway surface, the second raceway surface, and the rolling surface is smaller than a yield stress of a material constituting the at least one of the first raceway surface, the second raceway surface, and the rolling surface;
a rolling bearing, wherein the first von Mises stress in the at least one of the first raceway surface, the second raceway surface, and the rolling surface is smaller than a second von Mises stress in at least one of the inner ring, the outer ring, and the plurality of rolling elements that have the at least one of the first raceway surface, the second raceway surface, and the rolling surface, and the second von Mises stress is a maximum value of the von Mises stress inside the at least one of the inner ring, the outer ring, and the plurality of rolling elements .
前記第１の軌道面、前記第２の軌道面及び前記転動面の前記少なくとも１つは、前記第１の軌道面及び前記第２の軌道面の少なくとも１つである、請求項１から請求項３のいずれか１項に記載の転がり軸受。 the plurality of rolling elements are a plurality of balls,
4. The rolling bearing according to claim 1, wherein the at least one of the first raceway surface, the second raceway surface, and the rolling surface is at least one of the first raceway surface and the second raceway surface.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2023001831A JP7731384B2 (en) | 2018-03-09 | 2023-01-10 | Rolling bearings |
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| Application Number | Priority Date | Filing Date | Title |
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| JP2018042634A JP7401179B2 (en) | 2018-03-09 | 2018-03-09 | rolling bearing |
| JP2023001831A JP7731384B2 (en) | 2018-03-09 | 2023-01-10 | Rolling bearings |
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| JP2018042634A Division JP7401179B2 (en) | 2018-03-09 | 2018-03-09 | rolling bearing |
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| JP2023036977A JP2023036977A (en) | 2023-03-14 |
| JP7731384B2 true JP7731384B2 (en) | 2025-08-29 |
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| JP2023001831A Active JP7731384B2 (en) | 2018-03-09 | 2023-01-10 | Rolling bearings |
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| JP7401179B2 (en) * | 2018-03-09 | 2023-12-19 | Ntn株式会社 | rolling bearing |
| CN120091944A (en) | 2022-10-24 | 2025-06-03 | 软银集团股份有限公司 | Information processing device, vehicle, information processing method, and information processing program |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002206523A (en) | 2001-01-12 | 2002-07-26 | Ntn Corp | Rolling bearing |
| JP2005226714A (en) | 2004-02-12 | 2005-08-25 | Koyo Seiko Co Ltd | Rolling part, rolling device using the same, and method of manufacturing the rolling part and the rolling device |
| JP2008151235A (en) | 2006-12-15 | 2008-07-03 | Nsk Ltd | Rolling device |
| JP2012180886A (en) | 2011-03-01 | 2012-09-20 | Ntn Corp | Cage and rolling bearing |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007186760A (en) * | 2006-01-13 | 2007-07-26 | Nsk Ltd | Method of manufacturing bearing ring for rolling bearing and rolling bearing |
| JP4802273B2 (en) * | 2009-10-06 | 2011-10-26 | Ｎｔｎ株式会社 | bearing |
| JP2015017661A (en) * | 2013-07-11 | 2015-01-29 | 日本精工株式会社 | Rolling bearing |
| JP7401179B2 (en) * | 2018-03-09 | 2023-12-19 | Ntn株式会社 | rolling bearing |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002206523A (en) | 2001-01-12 | 2002-07-26 | Ntn Corp | Rolling bearing |
| JP2005226714A (en) | 2004-02-12 | 2005-08-25 | Koyo Seiko Co Ltd | Rolling part, rolling device using the same, and method of manufacturing the rolling part and the rolling device |
| JP2008151235A (en) | 2006-12-15 | 2008-07-03 | Nsk Ltd | Rolling device |
| JP2012180886A (en) | 2011-03-01 | 2012-09-20 | Ntn Corp | Cage and rolling bearing |
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| Publication number | Publication date |
|---|---|
| JP2023036977A (en) | 2023-03-14 |
| JP2019157935A (en) | 2019-09-19 |
| JP7401179B2 (en) | 2023-12-19 |
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