JP2023036977A - rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing for achieving a longer life by suppressing the occurrence of surface starting point separation on at least one of a first raceway surface, a second raceway surface, and rolling surface.

SOLUTION: A rolling bearing 1 includes an inner ring 3, an outer ring 6, and a plurality of rolling elements 10, the inner ring 3 having a first raceway surface 4, the outer ring 6 having a second raceway surface 7, the plurality of rolling element 10 each having a rolling surface 11. First Mises stress of 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 a material constituting at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to rolling bearings.

Japanese Patent Laying-Open No. 2011-7234 (Patent Document 1) discloses an inner ring having a first raceway surface, an outer ring having a second raceway surface, and a rolling surface arranged between an outer ring of the inner ring and having a rolling surface. A rolling bearing with rolling elements is disclosed.

JP 2011-7234 A

During use of the rolling bearing, the contact stress between the inner ring and rolling elements continues to act on the inner ring and rolling elements, and the contact stress between the outer ring and rolling elements continues to act on the outer ring and rolling elements. These contact stresses initiate fatigue cracks in at least one of the first raceway surface, the second raceway surface and the rolling surface. When the rolling bearing is used for a long period of time, fatigue cracks progress and part of at least one of the first raceway surface, the second raceway surface, and the rolling surface peels off. This delamination is called surface initiated delamination. An object of the present invention is to provide a rolling bearing having a long life by suppressing the occurrence of surface-originating flaking on at least one of a first raceway surface, a second raceway surface and a rolling contact surface. be.

A rolling bearing of the present invention includes an inner ring, an outer ring arranged on the outer peripheral side 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 facing the first raceway surface. Each of the plurality of rolling elements has a rolling surface 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 the material that constitutes at least one of the first raceway surface, the second raceway surface, and the rolling surface. less than the yield stress of

According to the rolling bearing of the present invention, it is possible to suppress the occurrence of surface-originating flaking on at least one of the first raceway surface, the second raceway surface, and the rolling surface, thereby providing a long-life rolling bearing. can be provided.

1 is a schematic partial cross-sectional perspective view of a rolling bearing according to Embodiment 1 of the present invention; FIG. 1 is a schematic partial enlarged cross-sectional view of a rolling bearing according to Embodiment 1 of the present invention; FIG. FIG. 4 is a graph showing the distribution of residual compressive stress applied to rolling bearings of Example 1, Comparative Example 2, and Comparative Example 3 of the present invention; Equivalent stress acting on at least one of the inner ring, outer ring and rolling elements of the rolling bearings of Example 1 and Comparative Examples 1 to 3 of the present invention in the thickness direction of at least one of the inner ring, outer ring and rolling elements It is a figure which shows the graph showing distribution of. FIG. 5 is a graph showing the distribution of residual compressive stress applied to the rolling bearings of Example 2, Comparative Examples 4 and 5 of the present invention; At least one of the inner ring, outer ring and rolling elements of the equivalent stress acting on at least one of the inner ring, outer ring and rolling elements of the rolling bearings of Example 2, Comparative Example 1, Comparative Example 4 and Comparative Example 5 of the present invention FIG. 4 is a graph showing distributions in two thickness directions; The anisotropy of the residual compressive stress applied to at least one of the first raceway surface, the second raceway surface and the rolling contact surface of the rolling bearing according to the first embodiment of the present invention 1 is a graph showing the effect on the relationship between the first residual compressive stress and the ratio of equivalent stresses acting on at least one of the inner ring, outer ring and rolling elements of the rolling bearing according to Example 1. FIG. Before using the rolling bearing according to Embodiment 1 of the present invention, at least one of the first raceway surface, the second raceway surface and the rolling contact surface is adjusted by rolling each rolling element on the inner ring and the outer ring. FIG. 5 is a graph showing the distribution of the residual compressive stress applied to the inner ring, the outer ring, and at least one of the rolling elements in the thickness direction; FIG. 5 is a schematic plan view of a rolling bearing according to Embodiment 2 of the present invention; FIG. 10 is a schematic partial enlarged cross-sectional view of the rolling bearing according to Embodiment 2 of the present invention taken along the cross-sectional line XX shown in FIG. 9;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
A rolling bearing 1 according to Embodiment 1 will be described with reference to FIGS. 1 to 8. FIG. 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. As shown in FIGS. The inner ring 3, the outer ring 6 and the plurality of rolling elements 10 are made of steel, for example bearing steel. The steel forming the inner ring 3, the outer ring 6, and the plurality of rolling elements 10 may be high chromium bearing steel defined in the JIS standard (JIS4805:2008). The steel forming the inner ring 3, the outer ring 6, and the plurality of rolling elements 10 may be SUJ2 steel specified in the JIS standard.

The inner ring 3 has a first raceway surface 4 . The outer ring 6 has a second raceway surface 7 facing 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 multiple rolling elements 10 may be multiple rollers. The rolling bearing 1 may be a roller bearing. The rolling bearing 1 may further include a retainer 15 that retains the plurality of rolling elements 10 .

The outer ring 6 can rotate about the axis 2 with respect to the inner ring 3 via a plurality of rolling elements 10 . Lubricating oil may be supplied to the rolling bearing 1 while the outer ring 6 rotates about the axis 2 with respect to the inner ring 3 . The rolling bearing 1 of the present embodiment is not particularly limited, but may be used under lean lubrication conditions (low Λ conditions). The lean lubrication condition (low Λ condition) is a condition in which the oil film parameter Λ defined by Equation (1) is 1 or less.

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 contact surface 11. represents roughness.

A first curvature radius in the axial direction (y direction) of at least one rolling bearing 1 of the inner ring 3 , the outer ring 6 and each rolling element 10 is It is different from the second radius of curvature in the circumferential direction (x direction). In this embodiment, the first radius of curvature of the inner ring 3 in the axial direction (y direction) is different from the second radius of curvature of the inner ring 3 in the circumferential direction (x direction). The first radius of curvature of the outer ring 6 in the axial direction (y direction) is different from the second radius of curvature of the outer ring 6 in the circumferential direction (x direction). A first radius of curvature in the axial direction (y direction) of each rolling element 10 is different from a second radius of curvature in the circumferential direction (x direction) of each rolling element 10 . Specifically, the first radius of curvature of the inner ring 3 in the axial direction (y direction) may be greater than the second radius of curvature of the inner ring 3 in the circumferential direction (x direction). The first radius of curvature of the outer ring 6 in the axial direction (y direction) may be larger than the second radius of curvature of the outer ring 6 in the circumferential direction (x direction). The first radius of curvature of each rolling element 10 in the axial direction (y direction) may be greater than the second radius of curvature of each rolling element 10 in the circumferential direction (x direction).

The first residual compressive stress σ _y0 in the axial direction (y direction) of at least one of the inner ring 3 and the outer ring 6 of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 is expressed by the first raceway surface 4. greater than the second residual compressive stress σ _x0 in the circumferential direction (x-direction) of at least one of the inner ring 3 and outer ring 6 of the second raceway surface 7 and rolling contact surface 11; Therefore, the first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 decreases. The first equivalent stress σ _e0 on at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling surface 11 is calculated as follows: less than the yield stress of the material constituting at least one of The occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed. As used herein, equivalent stress means Mises stress.

On the other hand, the first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 is Plastic deformation occurs in at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling surface 11 when the yield stress of the material forming at least one of the rolling surfaces 11 is exceeded. A fatigue crack occurs in at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11, and surface-originating flaking occurs.

Hereinafter, with reference to Example 1, Example 2, and Comparative Examples 1-5, the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 in at least one axial direction (y direction) The residual compressive stress _σy0 of 1 is made larger than the second residual compressive stress _σx0 in at least one circumferential direction (x direction) of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11. , the first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 is reduced.

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 regarded as Hertzian contacts. The contact surface between the inner ring 3 and each rolling element 10 and the contact surface between the outer ring 6 and each rolling element 10 can be regarded as elliptical contact surfaces having a major radius a and a minor radius b. . The major axis a means the radius in the major axis direction of the contact ellipse, and the minor axis b means the radius in the minor axis direction of the contact ellipse. 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 .

In Examples 1, 2, and Comparative Examples 1-5, Hertz's theory was used to construct an inner ring 3 and an outer ring having at least one of a first raceway surface 4, a second raceway surface 7, and a rolling contact surface 11. 6 and at least one of each rolling element 10 was simulated. Specifically, the maximum contact surface pressure P _max acting between the rolling surface 11 and at least one of the first raceway surface 4 and the second raceway surface 7 is 3.0 GPa, and the minor radius b is 1 mm. and when at least one of the inner ring 3, the outer ring 6 and each rolling element 10 has a residual compressive stress distribution shown in Tables 1 and 2, the inner ring 3, the outer ring 6 and each rolling element 10 At least one equivalent stress was simulated.

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, the outer ring 6 and each rolling element 10 is the inner ring 3, the outer ring 6 and each rolling element In at least one of the ten thickness directions, it has the distribution A shown in FIG. In Example 1, the residual compressive stress σ _y in at least one axial direction (y direction) of the inner ring 3 , outer ring 6 and each rolling element 10 is measured in at least one thickness direction of the inner ring 3 , outer ring 6 and each rolling element 10 , it has a distribution B shown in FIG. A negative sign on the vertical axis of FIG. 3 means that the stress applied to at least one of the inner ring 3, outer ring 6 and rolling elements 10 is compressive stress.

In Example 1, an anisotropic residual compressive stress is applied to at least one of the inner ring 3, outer ring 6 and rolling elements 10. FIG. Specifically, the first residual compressive stress σ _y0 in at least one axial direction (y direction) of the first raceway surface 4 , the second raceway surface 7 and the rolling contact surface 11 is calculated as follows: , the second residual compressive stress σ _x0 in the circumferential direction (x-direction) of at least one of the second raceway surface 7 and the rolling contact surface 11 . In this specification, a large compressive stress means that the absolute value of the compressive stress is large.

Furthermore, as shown by distributions A and B in FIG. 3 , residual The compressive stress _σy is greater than the residual compressive stress _σx in the circumferential direction (x direction). The residual compressive stress σ _y in at least one axial direction (y direction) of the inner ring 3 , the outer ring 6 and each rolling element 10 is calculated as follows: It may be maximum on at least one surface of the outer ring 6 and each rolling element 10 (that is, at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11).

On the other hand, as shown in Table 1, in Comparative Example 1, no residual compressive stress was applied to the inner ring 3, the outer ring 6, and the rolling elements 10. In Comparative Example 2, the residual compressive stress σ _x in the circumferential direction (x direction) and 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 are 6 and at least one thickness direction of each rolling element 10 has the distribution A shown in FIG. In Comparative Example 3, the residual compressive stress σ _x in the circumferential direction (x direction) and 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 are 6 and at least one thickness direction of each rolling element 10 has the distribution B shown in FIG. In Comparative Examples 2 and 3, isotropic residual compressive stresses σ _x and σ _y are applied to at least one of the inner ring 3 , outer ring 6 and rolling elements 10 .

As shown in FIG. 4, the equivalent stress of 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 of Comparative Examples 2 and 3 in the surface layer region. The residual compressive stress applied to at least one of the inner ring 3, the outer ring 6 and each rolling element 10 is applied to the inner ring 3, the outer ring 6 and each rolling element in the surface layer region of at least one of the inner ring 3, the outer ring 6 and each rolling element 10. reduce the equivalent stress acting on at least one of 10; In this specification, the surface layer region means at least one surface of the inner ring 3, the outer ring 6, and each rolling element 10 (that is, at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11). to the depth where the equivalent stress is minimal. In FIG. 4, the horizontal axis indicates the position z/b in the thickness direction of at least one of the inner ring 3, the outer ring 6 and each rolling element 10 normalized by the minor radius b of the contact ellipse. The surface region may be, for example, a region where z/b is 0.2 or less. The surface layer region is, for example, 50 μm from the inner ring 3, the outer ring 6, and at least one surface of each rolling element 10 (that is, at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11). It may be a region up to the depth.

At least one surface layer region of the inner ring 3, the outer ring 6 and each rolling element 10 is formed by at least one surface of the inner ring 3, the outer ring 6 and each rolling element 10, that is, the first raceway surface 4, the second raceway surface 7 and the At least one of the rolling surfaces 11 is included. The first equivalent stress σ _e0 of Example 1 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 is obtained by the first raceway surface 4, the second raceway surface 7 and Lower than the first equivalent stress of Comparative Examples 2 and 3 on at least one of the rolling surfaces 11 . In FIG. 4, the position z/b=0 is the inner ring 3, outer ring 6 and at least one surface of each rolling element 10, that is, at least the first raceway surface 4, the second raceway surface 7 and the rolling surface 11. represents one.

The reason why the equivalent stress of Example 1 and the first equivalent stress σ _e0 in the surface layer region are lower than the equivalent stress of Comparative Examples 2 and 3 and the first equivalent stress in the surface layer region, respectively, is as follows. can be considered as At least one first curvature radius of the inner ring 3, outer ring 6 and each rolling element 10 in the axial direction (y direction) is equal to at least one first radius of curvature of the inner ring 3, outer ring 6 and each rolling element 10 in the circumferential direction (x direction). 2 radius of curvature. Therefore, the contact stress between the inner ring 3 and each rolling element 10 in the axial direction (y direction) differs 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 of Example 1 is greater than the isotropic residual compressive stress of Comparative Examples 2 and 3 in terms of the anisotropic contact stress between the inner ring 3 and each rolling element 10 and the outer ring Anisotropic contact stress between 6 and each rolling element 10 can be dealt with more effectively.

Thus, the anisotropic residual compressive stress applied to at least one of the inner ring 3, the outer ring 6 and each rolling element 10 is reduced to at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11. Equivalent stress acting on at least one of the inner ring 3 , the outer ring 6 and each rolling element 10 is reduced in at least one surface layer region of the inner ring 3 , the outer ring 6 and each rolling element 10 . The equivalent stress in the surface layer region of at least one of the inner ring 3, the outer ring 6 and each rolling element 10 is the yield stress of the material forming at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11. be smaller than Therefore, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed.

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, the outer ring 6 and each rolling element 10 is the inner ring 3, the outer ring 6 and each rolling element In at least one thickness direction of 10, it has a distribution C shown in FIG. In Example 2, the residual compressive stress σ _y in at least one axial direction (y direction) of the inner ring 3 , outer ring 6 and each rolling element 10 is measured in at least one thickness direction of the inner ring 3 , outer ring 6 and each rolling element 10 , it has a distribution D shown in FIG. A negative sign on the vertical axis of FIG. 5 means that the stress applied to at least one of the inner ring 3, outer ring 6 and rolling elements 10 is compressive stress.

In Example 2, an anisotropic residual compressive stress is applied to at least one of the inner ring 3, the outer ring 6 and each rolling element 10. FIG. Specifically, the first residual compressive stress σ _y0 in at least one axial direction (y direction) of the first raceway surface 4 , the second raceway surface 7 and the rolling contact surface 11 is calculated as follows: , the second residual compressive stress σ _x0 in the circumferential direction (x-direction) of at least one of the second raceway surface 7 and the rolling contact surface 11 .

Furthermore, as shown by distributions C and D in FIG. 5 , residual The compressive stress _σy is greater than the residual compressive stress _σx in the circumferential direction (x direction). The residual compressive stress σ _y in at least one axial direction (y direction) of the inner ring 3 , the outer ring 6 and each rolling element 10 is calculated as follows: It may be maximum inside at least one of the outer ring 6 and each rolling element 10 .

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, outer ring 6, and each rolling element ₁₀ is maximum is greater than 0 and 0 It may be greater than 0.03 and may be greater than 0.05. The position z/b in the thickness direction where the residual compressive stress _σy in the axial direction (y direction) of at least one of the inner ring 3, outer ring 6, and each rolling element 10 is maximum may be less than 1.00, and may be 0 It may be less than 0.90 and may be less than 0.80.

On the other hand, as shown in Table 2, in Comparative Example 1, no residual compressive stress was applied to the inner ring 3, the outer ring 6, and the rolling elements 10. In Comparative Example 4, the residual compressive stress σ _x in the circumferential direction (x direction) and 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 are 6 and at least one thickness direction of each rolling element 10 has a distribution C shown in FIG. In Comparative Example 5, the residual compressive stress σ _x in the circumferential direction (x direction) and 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 are 6 and at least one thickness direction of each rolling element 10 has a distribution D shown in FIG. In Comparative Examples 4 and 5, isotropic residual compressive stresses σ _x and σ _y are applied to at least one of the inner ring 3 , outer ring 6 and rolling elements 10 .

As shown in FIG. 6, the equivalent stress of Example 2 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 of Comparative Examples 4 and 5 in the surface layer region. The residual compressive stress applied to at least one of the inner ring 3, the outer ring 6 and each rolling element 10 is applied to the inner ring 3, the outer ring 6 and each rolling element in the surface layer region of at least one of the inner ring 3, the outer ring 6 and each rolling element 10. reduce the equivalent stress acting on at least one of 10;

At least one surface layer region of the inner ring 3, the outer ring 6 and each rolling element 10 is formed by at least one surface of the inner ring 3, the outer ring 6 and each rolling element 10, that is, the first raceway surface 4, the second raceway surface 7 and the At least one of the rolling surfaces 11 is included. The first equivalent stress σ _e0 of Example 2 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 is obtained by Lower than the first equivalent stress of Comparative Examples 4 and 5 on at least one of the rolling surfaces 11 . In FIG. 4, the position z/b=0 is the inner ring 3, outer ring 6 and at least one surface of each rolling element 10, that is, at least the first raceway surface 4, the second raceway surface 7 and the rolling surface 11. represents one.

The reason why the equivalent stress of Example 2 and the first equivalent stress σ _e0 in the surface layer region are lower than the equivalent stress and the first equivalent stress of Comparative Examples 4 and 5, respectively, is considered as follows. be done. At least one first curvature radius of the inner ring 3, outer ring 6 and each rolling element 10 in the axial direction (y direction) is equal to at least one first radius of curvature of the inner ring 3, outer ring 6 and each rolling element 10 in the circumferential direction (x direction). 2 radius of curvature. Therefore, the contact stress between the inner ring 3 and each rolling element 10 in the axial direction (y direction) differs 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 of Example 2 is greater than the isotropic residual compressive stress of Comparative Examples 4 and 5, and the anisotropic contact stress between the inner ring 3 and each rolling element 10 and the outer ring Anisotropic contact stress between 6 and each rolling element 10 can be dealt with more effectively.

Thus, the anisotropic residual compressive stress applied to at least one of the inner ring 3, the outer ring 6 and each rolling element 10 is reduced to at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11. Equivalent stress acting on at least one of the inner ring 3 , the outer ring 6 and each rolling element 10 is reduced in at least one surface layer region of the inner ring 3 , the outer ring 6 and each rolling element 10 . The equivalent stress in the surface layer region of at least one of the inner ring 3, the outer ring 6 and each rolling element 10 is the yield stress of the material forming at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11. be smaller than Therefore, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed.

As in Examples 1 and 2 shown in FIGS. 4 and 6, the first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 is , the inner ring 3 having at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11, the outer ring 6 and at least one of the rolling elements 10 are less than the second equivalent stress σ _e2 good too. The second equivalent stress σ _e2 is the maximum 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 FIG. 7 may be less than one. In this specification, the equivalent stress ratio n is given by the ratio n of the first equivalent stress σ _e0 to the second equivalent stress σ _e2 (n=σ _e0 /σ _e2 ).

The first residual compressive stress σ _y0 in the axial direction (y direction) of at least one of the inner ring 3 and the outer ring 6 of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 is expressed by the first raceway surface 4. greater than the second residual compressive stress σ _x0 in the circumferential direction (x-direction) of at least one of the inner ring 3 and outer ring 6 of the second raceway surface 7 and rolling contact surface 11; Therefore, the first equivalent stress σ _e0 on at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling contact surface 11 can be reduced and the ratio of equivalent stresses n can be less than one. The first equivalent stress σ _e0 on at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling surface 11 is calculated as follows: less than the yield stress of the material constituting at least one of The occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed.

The ratio of the first residual compressive stress σ _y0 to the maximum contact surface 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 more, - It may be 0.6 or more, or -0.5 or more. Therefore, the first equivalent stress σ _e0 on at least one of the first raceway surface 4 , the second raceway surface 7 and the rolling surface 11 is the same as the first raceway surface 4 , the second raceway surface 7 and the rolling At least one of the inner ring 3, the outer ring 6 and each rolling element 10 with at least one of the surfaces 11 can be less than the second equivalent stress σ _e2 . The ratio of the first residual compressive stress σ _y0 to the maximum contact surface pressure P _max 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, −0.1 It may be less than or equal to -0.2 or less.

The anisotropy α of the residual compressive stress is greater than one. The anisotropy α of the residual compressive stress is given by the ratio of the first residual compressive stress _σy0 to the second residual compressive stress _σx0 (α= _σy0 / _σx0 ). 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.

As shown in FIG. 7, as the anisotropy α of the residual compressive stress becomes larger than 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 becomes less than 1 becomes Expanding. A negative sign on the horizontal axis of FIG. 7 means that the stress applied to at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 is compressive stress. For example, when the residual compressive stress anisotropy α is equal to 1.3, a first residual compressive stress σ _y0 less than or equal to 1650 MPa makes the first equivalent stress σ _e0 lower than the second equivalent stress σ _e2 can do Therefore, by making the anisotropy α of the residual compressive stress greater than 1, more types of rolling bearings 1 having various first residual compressive _stresses The first equivalent stress σ _e0 on at least one of the raceway surface 7 and the rolling surface 11 can be reduced. In more types of rolling bearings 1 , the occurrence of surface-originating flaking on at least one of the first raceway surface 4 , the second raceway surface 7 , and the rolling contact surface 11 can be suppressed.

In the surface layer region, 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 Two methods of increasing the second residual compressive stress σ _x0 in at least one circumferential direction (x-direction) of the second raceway surface 7 and the rolling contact surface 11 are exemplified below. A 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.

In the second method, before the rolling bearing 1 is used, each rolling element 10 is attached to the inner ring 3 and the rolling element 10 at a first maximum contact surface pressure higher than the second maximum contact surface pressure in normal use of the rolling bearing 1. It is to roll the outer ring 6 for a short period of time. A ratio of the high first maximum contact surface pressure to the second maximum contact surface pressure may be greater than 1.0 and may be greater than 1.3. The ratio of the high first maximum contact surface pressure to the second maximum contact surface pressure is not particularly limited, but may be less than 3.0 and may be 2.5 or less. For example, the first maximum contact surface pressure may be 5.6 GPa, and the second maximum contact surface 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 using the rolling bearing 1, as shown in FIG. , the inner ring 3 including the outer ring 6 and at least one surface of 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 outer ring 6 and each rolling element The first residual compressive stress σ _y0 can be greater than the second residual compressive stress σ _x0 in at least one surface region of the ten.

Effects of the rolling bearing 1 of the present embodiment will be described.
A rolling bearing 1 of the present embodiment includes 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 facing the first raceway surface 4 . 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 first residual compressive stress σ _y0 in the axial direction (y direction) of at least one of the inner ring 3 and the outer ring 6 of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 is expressed by the first raceway surface 4. greater than the second residual compressive stress σ _x0 in the circumferential direction (x-direction) of at least one of the inner ring 3 and outer ring 6 of the second raceway surface 7 and rolling contact surface 11;

At least one first radius of curvature of the inner ring 3, the outer ring 6 and each rolling element 10 in the axial direction (y-direction) of the rolling bearing 1 is equal to that of the inner ring 3, the outer ring 6 and each rolling element 10 in the circumferential direction (x-direction) of the rolling bearing 1. It differs from the at least one second radius of curvature of the rolling bodies 10 . 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 equal to the contact stress between the inner ring 3 and each rolling element 10 in the circumferential direction (x direction) of the rolling bearing 1. Different from contact stress. 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 the contact stress between the outer ring 6 and each rolling element 10 in the circumferential direction (x direction) of the rolling bearing 1. different from

The first residual compressive stress σ _y0 in at least one axial direction (y direction) of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 is By making the second residual compressive stress σ _x0 in the circumferential direction (x-direction) of at least one of surface 7 and rolling surface 11 greater than that, anisotropic contact stress can be effectively dealt with. The first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling surface 11 decreases. According to the rolling bearing 1 of the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed. A rolling bearing 1 with a long life can be provided.

In the rolling bearing 1 of the present embodiment, the first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 is At least one of the inner ring 3, the outer ring 6 and each rolling element 10 having at least one of the two raceway surfaces 7 and rolling surfaces 11 may be smaller than the second equivalent stress σ _e2 . The second equivalent stress σ _e2 is the maximum 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 the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed. A rolling bearing 1 with a long life can be provided.

The residual compressive stress σ _y in at least one axial direction (y direction) of the inner ring 3 , outer ring 6 and each rolling element 10 in at least one thickness direction of the inner ring 3 , outer ring 6 and each rolling element 10 At least one of the raceway surface 4 , the second raceway surface 7 and the rolling surface 11 may be maximum. 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 contact surface 11 decreases. According to the rolling bearing 1 of the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed. A rolling bearing 1 with a long life can be provided.

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 obtained by: It may be maximum inside at least one of the 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 rolling elements 10 is reduced. According to the rolling bearing 1 of the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed. A rolling bearing 1 with a long life can be provided.

In the rolling bearing 1 of the present 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 is − It may be 0.7 or more and less than 0.0. Therefore, the first equivalent stress σ _e0 on at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 decreases, and the first equivalent stress σ _e0 6 and at least one second equivalent stress σ _e2 of each rolling element 10 . According to the rolling bearing 1 of the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling contact surface 11 can be suppressed. A rolling bearing 1 with a long life can be provided.

In the rolling bearing 1 of this embodiment, the multiple rolling elements 10 may be multiple rollers. The anisotropic residual compressive stress applied to at least one of the first raceway surface 4, the second raceway surface 7 and the rolling contact surface 11 is applied to the first raceway surface 4, the second raceway surface 7 and the rolling surface Equivalent stress acting on at least one of the inner ring 3, the outer ring 6 and each roller is reduced in at least one surface layer region _R1 , _R2 of the inner ring 3, the outer ring 6 and each roller including at least one of the sliding surface 11. . According to the rolling bearing 1 of the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 of each roller can be suppressed. Thus, a rolling bearing 1 with a long service life can be provided.

(Embodiment 2)
A rolling bearing 1b according to Embodiment 2 will be described with reference to FIGS. 9 and 10. FIG. The rolling bearing 1b of the present embodiment has the same configuration as the rolling bearing 1 of the first embodiment, but differs mainly in the following points.

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).

The first radius of curvature of at least one of the inner ring 3 and the outer ring 6 in the axial direction (y direction) of the rolling bearing 1b is the second radius of curvature of at least one of the inner ring 3 and the outer ring 6 in the circumferential direction (x direction) of the rolling bearing 1b. different from the radius of curvature. 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 greater 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 greater than the radius of curvature of the outer ring 6 in the circumferential direction (x-direction).

In the present embodiment, the residual compressive stress σ _y is greater than the residual compressive stress σ _x in the circumferential direction (x direction). Distribution of residual compressive stress σy in the axial direction (y direction) and distribution of residual compressive stress _σx in the circumferential direction (x direction) in at least one thickness direction of the inner ring 3 and the outer ring ₆ in the present embodiment. are the distribution of residual compressive stress σ _y in the axial direction (y direction) and the residual compression in the circumferential direction (x direction) in at least one thickness direction of the inner ring 3 and the outer ring 6 in Embodiment 1, respectively. It may be similar to the distribution of stress σ _x . In the present embodiment, no anisotropic residual compressive stress is applied to the rolling surface 11 .

The rolling bearing 1b of the present embodiment has the same effects as the rolling bearing 1 of the first embodiment as follows.

In the rolling bearing 1b of this embodiment, the plurality of rolling elements 10b is a plurality of balls. On at least one of the first raceway surface 4 and the second raceway surface 7, the first residual compressive stress σ _y0 in the axial direction (y direction) is the second residual compressive stress σ in the circumferential direction (x direction). Greater than _x0 .

In the rolling bearing 1b of the present embodiment, the first curvature radius of at least one of the inner ring 3 and the outer ring 6 in the axial direction (y direction) of the rolling bearing 1b is equal to that of the inner ring 3 in the circumferential direction (x direction) of the rolling bearing 1b. and at least one second radius of curvature of the outer ring 6 . 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 the balls in the axial direction (y direction) of the rolling bearing 1b differs from the contact stress between the outer ring 6 and the balls in the circumferential direction (x direction) of the rolling bearing 1b.

The first residual compressive stress σ _y0 in at least one axial direction (y direction) of the first raceway surface 4 and the second raceway surface 7 is calculated by By being greater than the second residual compressive stress σ _x0 in at least one circumferential direction (x-direction) of surface 11, anisotropic contact stress can be effectively dealt with. The first equivalent stress σ _e0 in at least one of the inner ring 3 and outer ring 6 decreases. According to the rolling bearing 1b of the present embodiment, the occurrence of surface-originating flaking on at least one of the first raceway surface 4 and the second raceway surface 7 can be suppressed, and the rolling bearing has a long life. 1b can be provided.

Embodiment 1 and Embodiment 2 disclosed this time should be considered as examples in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

1, 1b rolling bearing, 2 shaft, 3 inner ring, 4 first raceway surface, 6 outer ring, 7 second raceway surface, 10, 10b rolling element, 11 rolling surface, 15 retainer.

Claims (5)

an inner ring having a first raceway surface;
an outer ring disposed on the outer peripheral side of the inner ring, the outer ring having a second raceway surface facing the first raceway surface;
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; and
The first von Mises stress in at least one of the first raceway surface, the second raceway surface and the rolling surface is the same as that of the first raceway surface, the second raceway surface and the rolling surface. A rolling bearing having a yield stress less than the yield stress of the material of which at least one is composed. against a second residual compressive stress in the circumferential direction of the at least one inner ring and the outer ring of the first raceway surface, the second raceway surface and the rolling surface; 2. A rolling bearing according to claim 1, wherein a ratio of first residual compressive stresses in the axial direction of said at least one inner ring and said outer ring of said raceway surface and said rolling contact surface is greater than one. The first von von Mises stress in the at least one of the first raceway surface, the second raceway surface and the rolling surface is equal to the first raceway surface, the second raceway surface and the rolling surface. is less than a second von Mises stress of said each of said inner ring, said outer ring and said plurality of rolling elements having said at least one of said second von Mises stress is said to have said inner ring, said outer ring and said plurality of 3. A rolling bearing according to claim 1 or claim 2, wherein the von von Mises stress within said at least one of said each of said rolling elements. 4. The rolling bearing according to any one of claims 1 to 3, wherein said plurality of rolling elements are a plurality of rollers. The plurality of rolling elements are a plurality of balls,
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. 5. The rolling bearing according to any one of items 4.

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