JP7401179B2 - rolling bearing - Google Patents

Description

The present invention relates to rolling bearings.

Japanese Unexamined Patent Publication No. 2011-7234 (Patent Document 1) discloses an inner ring having a first raceway surface, an outer ring having a second raceway surface, and an outer ring having a rolling surface and disposed between the inner ring and the outer ring. The present disclosure discloses a rolling bearing including rolling elements.

Japanese Patent Application Publication No. 2011-7234

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

The 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 that faces 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 residual compressive stress in the axial direction of the inner ring and the outer ring of at least one of the first raceway surface, the second raceway surface and the rolling surface is It is larger than the second residual compressive stress in the circumferential direction of at least one of the inner ring and the outer ring.

According to the rolling bearing of the present invention, occurrence of surface-originated flaking on at least one of the first raceway surface, the second raceway surface, and the rolling surface can be suppressed, and the rolling bearing can have a long life. may be provided.

1 is a schematic partial cross-sectional perspective view of a rolling bearing according to Embodiment 1 of the present invention. 1 is a schematic partial enlarged sectional view of a rolling bearing according to Embodiment 1 of the present invention. FIG. 2 is a graph showing the distribution of residual compressive stress applied to the rolling bearings of Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. The equivalent stress acting on at least one of the inner ring, outer ring, and each rolling element 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 each rolling element. It is a figure which shows the graph showing the distribution of. FIG. 7 is a graph showing the distribution of residual compressive stress applied to the rolling bearings of Example 2, Comparative Example 4, and Comparative Example 5 of the present invention. The equivalent stress acting on at least one of the inner ring, outer ring, and each rolling element of the rolling bearings of Example 2, Comparative Example 1, Comparative Example 4, and Comparative Example 5 of the present invention is at least one of the inner ring, outer ring, and each rolling element. FIG. 3 is a diagram showing a graph showing distribution in the thickness direction. The anisotropy of the residual compressive stress imparted to at least one of the first raceway surface, the second raceway surface, and the rolling surface of the rolling bearing according to the first embodiment of the present invention is FIG. 2 is a graph showing the influence on the relationship between the ratio of equivalent stress acting on at least one of the inner ring, outer ring, and each rolling element of the rolling bearing according to No. 1 and the first residual compressive stress. 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 surface is formed by rolling each rolling element relative to the inner ring and the outer ring. FIG. 3 is a graph showing the distribution of residual compressive stress applied to the inner ring, the outer ring, and at least one of the rolling elements in the thickness direction. FIG. 2 is a schematic plan view of a rolling bearing according to Embodiment 2 of the present invention. 10 is a schematic partially enlarged cross-sectional view taken along the cross-sectional line XX shown in FIG. 9 of a rolling bearing according to a second embodiment of the present invention. FIG.

Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals, and the description thereof will not be repeated.

(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, for example. 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 that faces the first raceway surface 4 . The outer ring 6 is arranged on the outer peripheral side of the inner ring 3. The 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.

The outer ring 6 can rotate about the shaft 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 shaft 2 relative to the inner ring 3. The rolling bearing 1 of this embodiment may be used under lean lubrication conditions (low Λ conditions), although there are no particular limitations thereto. 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 surface 11. Represents roughness.

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 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). The first radius of curvature of each rolling element 10 in the axial direction (y direction) is different from the second radius of curvature of each rolling element 10 in the circumferential direction (x direction). Specifically, the first radius of curvature of the inner ring 3 in the axial direction (y direction) may be larger 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 larger 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 outer ring 6 of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is 4. It is larger 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 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 decreases. 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 The yield stress of the material constituting at least one of the Occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed. As used herein, equivalent stress means Mises stress.

On the other hand, 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 When the stress is greater than the yield stress of the material constituting at least one of the rolling surfaces 11, plastic deformation occurs in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11. Fatigue cracks occur in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11, and surface-originated peeling 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). 1 residual compressive stress σ _y0 is made 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, second raceway surface 7, and rolling surface 11. This indicates that 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 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 as Hertzian contact. 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 an elliptical contact surface having a major axis a and a minor axis 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 long axis direction of the contact ellipse is the axial direction (y direction) of the rolling bearing 1, and the short axis direction of the contact ellipse is the circumferential direction (x direction) of the rolling bearing 1.

In Example 1, Example 2, and Comparative Examples 1-5, using Hertz's theory, an inner ring 3 and an outer ring each having at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 are constructed. 6 and each rolling element 10 was simulated. Specifically, the maximum contact pressure P _max that acts 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 short radius b is 1 mm. and at least one of the inner ring 3, the outer ring 6, and each rolling element 10 has the residual compressive stress distribution shown in Tables 1 and 2. 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, outer ring 6, and each rolling element 10 is In at least one thickness direction of 10, it has a 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 equal to the residual compressive stress σ y in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. , has the distribution B shown in FIG. A negative sign on the vertical axis in FIG. 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.

In Example 1, 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. 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 , is larger than 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 surface 11. In this specification, a large compressive stress means a large absolute value of the compressive stress.

Furthermore, as shown in distribution A and distribution B in FIG. The compressive stress σ _y is larger than the residual compressive stress σ _x in the circumferential direction (x direction). 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 is determined by the residual compressive stress σ y in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. It may be maximum at 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, outer ring 6, and each rolling element 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, outer ring 6, and each rolling element 10 are 6 and each rolling element 10 has a distribution A shown in FIG. 3 in at least one thickness direction. 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, outer ring 6, and each rolling element 10 are 6 and each rolling element 10 has a distribution B shown in FIG. 3 in at least one thickness direction. 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 each rolling element 10.

As shown in FIG. 4, the equivalent stress of Example 1 in at least one surface region 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 region. The residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10 is applied to the inner ring 3, outer ring 6, and each rolling element in at least one surface region of the inner ring 3, outer ring 6, and each rolling element 10. 10. In this specification, the surface region refers to 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). This refers to the region from the depth to the depth where the equivalent stress is minimal. In FIG. 4, the horizontal axis indicates the position z/b of at least one of the inner ring 3, the outer ring 6, and each rolling element 10 in the thickness direction, which is normalized by the minor radius b of the contact ellipse. The surface layer 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 at least one surface of the inner ring 3, 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 area may be up to depth.

At least one surface layer region of the inner ring 3, outer ring 6, and each rolling element 10 is at least one surface of the inner ring 3, outer ring 6, and each rolling element 10, that is, the first raceway surface 4, the second raceway surface 7, and At least one of the rolling surfaces 11 is included. The first equivalent stress σ _e0 of the first embodiment in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is It is lower than the first equivalent stress in Comparative Examples 2 and 3 in at least one of the rolling surfaces 11. In FIG. 4, the position z/b=0 corresponds to at least one surface of the inner ring 3, outer ring 6, and 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 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 as follows. It can be thought of 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 the first 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). The radius of curvature is different from that of 2. 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 is greater than the isotropic residual compressive stress in Comparative Examples 2 and 3 because of the anisotropic contact stress between the inner ring 3 and each rolling element 10 and the outer ring. 6 and each rolling element 10 can be dealt with more effectively.

In this way, the anisotropic residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10 is reduced to at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. The equivalent stress acting on at least one of the inner ring 3, outer ring 6, and each rolling element 10 is reduced in at least one surface layer region of the inner ring 3, outer ring 6, and each rolling element 10, including the inner ring 3, outer ring 6, and each rolling element 10. The equivalent stress in at least one surface layer region of the inner ring 3, outer ring 6, and each rolling element 10 is 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. becomes smaller than Therefore, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling 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, outer ring 6, and each rolling element 10 is It has a distribution C shown in FIG. 5 in at least one thickness direction of 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 is equal to the residual compressive stress σ y of at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the thickness direction. has a distribution D shown in FIG. A 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.

In Example 2, an anisotropic residual compressive stress is applied to at least one of the inner ring 3, 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 , is larger than 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 surface 11.

Furthermore, as shown in distribution C and distribution D in FIG. The compressive stress σ _y is larger than the residual compressive stress σ _x in the circumferential direction (x direction). 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 is determined by the residual compressive stress σ y in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. 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 σ _y in at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the axial direction (y direction) is maximum is greater than 0, and 0. It may be greater than .03, or it may be greater than 0.05. The position z/b in the thickness direction at which the residual compressive stress σ _y in at least one of the inner ring 3, outer ring 6, and each rolling element 10 in the axial direction (y direction) is maximum may be smaller than 1.00, and may be smaller than 0. It may be smaller than .90 or smaller 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, outer ring 6, and each rolling element 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, outer ring 6, and each rolling element 10 are 6 and each rolling element 10 has a distribution C shown in FIG. 5 in at least one thickness direction. 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, outer ring 6, and each rolling element 10 are 6 and each rolling element 10 has a distribution D shown in FIG. 5 in at least one thickness direction. 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 each rolling element 10.

As shown in FIG. 6, the equivalent stress of Example 2 in at least one surface region 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 region. The residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10 is applied to the inner ring 3, outer ring 6, and each rolling element in at least one surface region of the inner ring 3, outer ring 6, and each rolling element 10. 10.

At least one surface layer region of the inner ring 3, outer ring 6, and each rolling element 10 is at least one surface of the inner ring 3, outer ring 6, and each rolling element 10, that is, the first raceway surface 4, the second raceway surface 7, and At least one of the rolling surfaces 11 is included. The first equivalent stress σ _e0 of the second embodiment in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is It is lower than the first equivalent stress in Comparative Examples 4 and 5 in at least one of the rolling surfaces 11. In FIG. 4, the position z/b=0 corresponds to at least one surface of the inner ring 3, outer ring 6, and 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 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 considered as follows. It will be done. 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 the first 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). The radius of curvature is different from that of 2. 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 is greater than the isotropic residual compressive stress in Comparative Examples 4 and 5 because of the anisotropic contact stress between the inner ring 3 and each rolling element 10 and the outer ring. 6 and each rolling element 10 can be dealt with more effectively.

In this way, the anisotropic residual compressive stress imparted to at least one of the inner ring 3, outer ring 6, and each rolling element 10 is reduced to at least one of the first raceway surface 4, second raceway surface 7, and rolling surface 11. The equivalent stress acting on at least one of the inner ring 3, outer ring 6, and each rolling element 10 is reduced in at least one surface layer region of the inner ring 3, outer ring 6, and each rolling element 10, including the inner ring 3, outer ring 6, and each rolling element 10. The equivalent stress in at least one surface layer region of the inner ring 3, outer ring 6, and each rolling element 10 is 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. becomes smaller than Therefore, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed.

As in Example 1 and Example 2 shown in FIGS. 4 and 6, 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 , the second equivalent stress σ _e2 of 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. Good too. The second equivalent stress σ _e2 is the maximum value of the equivalent stress inside at least one of the inner ring 3, outer ring 6, and each rolling element 10. In other words, the ratio n of equivalent stresses shown in FIG. 7 may be less than 1. In this specification, the ratio n of equivalent stress 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 outer ring 6 of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is 4. It is larger 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 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 decreases, and the ratio n of the equivalent stress may 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 is The yield stress of the material constituting at least one of the Occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed.

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 outer ring 6 may be −0.7 or more, and − It may be 0.6 or more, or -0.5 or more. 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 The second equivalent stress σ _e2 of at least one of the inner ring 3, outer ring 6, and each rolling element 10 having at least one surface 11 can be made smaller. 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, and may be −0.1 It may be less than or equal to -0.2.

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 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 σ _y0 in which the ratio n of the equivalent stress acting on the rolling bearing 1 is less than 1 increases. Expanding. A negative sign on the horizontal axis in 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 surface 11 is compressive stress. For example, when the anisotropy α of the residual compressive stress is equal to 1.3, the first residual compressive stress σ _y0 of 1650 MPa or less causes the first equivalent stress σ _e0 to be lower than the second equivalent stress σ _e2 I can do that. Therefore, by making the anisotropy α of the residual compressive stress larger than 1, in more types of rolling bearings 1 having various first residual compressive stresses σ _y0 , the first raceway surface 4, the second The first equivalent stress σ _e0 in at least one of the raceway surface 7 and the rolling surface 11 can be reduced. In more types of rolling bearings 1, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed.

In the surface 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 set to the first raceway surface 4, Two methods will be exemplified below in which the second residual compressive stress σ _{x0 in at least one of 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). 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.

In the second method, before using the rolling bearing 1, each rolling element 10 is connected to the inner ring 3 and This means that the outer ring 6 is caused to roll for a short period of time. The ratio of the high first maximum contact pressure to the second maximum contact pressure may be greater than 1.0, and 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 smaller than 3.0 and may be 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 outer ring 6 at a first maximum contact pressure of 5.6 GPa before using the rolling bearing 1, as shown in FIG. , an inner ring 3, an outer ring 6, and each rolling element, including at least one surface of 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 residual compressive stress σ _y0 can be greater than the second residual compressive stress σ _x0 in at least one of the ten surface regions.

The effects of the rolling bearing 1 of this embodiment will be explained.
The rolling bearing 1 of this embodiment includes an inner ring 3, an outer ring 6 disposed on the outer peripheral side of the inner ring 3, and a plurality of rolling elements 10 disposed 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 that faces 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 outer ring 6 of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is 4. It is larger 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 surface 11.

At least one first radius of curvature of the inner ring 3, outer ring 6, and each rolling element 10 in the axial direction (y direction) of the rolling bearing 1 is the same as that of the inner ring 3, outer ring 6, and each rolling element 10 in the circumferential direction (x direction) of the rolling bearing 1. The second radius of curvature of at least one of the rolling elements 10 is different. 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 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 By making the residual compressive stress σ _x0 larger than the second residual compressive stress σ x0 in the circumferential direction (x direction) of at least one of the surface 7 and the rolling surface 11, anisotropic contact stress can be effectively dealt with. 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 decreases. According to the rolling bearing 1 of the present embodiment, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and the long A rolling bearing 1 having a long life can be provided.

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 is may be smaller than the second equivalent stress σ _e2 of at least one of the inner ring 3, outer ring 6, and each rolling element 10 having at least one of the raceway surface 7 and rolling surface 11 of 2. The second equivalent stress σ _e2 is the maximum value of the equivalent stress inside at least one of the inner ring 3, outer ring 6, and each rolling element 10. According to the rolling bearing 1 of the present embodiment, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and the long A rolling bearing 1 having a long life can be provided.

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 is determined by the first It may be maximum at at least one of the raceway surface 4, the second raceway surface 7, and the rolling surface 11. 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 decreases. According to the rolling bearing 1 of the present embodiment, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and the long A rolling bearing 1 having a long life can be provided.

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 is determined by the residual compressive stress σ y in the thickness direction of at least one of the inner ring 3, outer ring 6, and each rolling element 10. 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 each rolling element 10 decreases. According to the rolling bearing 1 of the present embodiment, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and the long A rolling bearing 1 having 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 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 in at least one of the first raceway surface 4, the second raceway surface 7, and the rolling 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, occurrence of surface-originated peeling on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 can be suppressed, and the long A rolling bearing 1 having a long life can be provided.

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 applied to at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 is Reducing the equivalent stress acting on at least one of the inner ring 3, outer ring 6, and each roller in at least one surface region _R1 , _R2 of the inner ring 3, outer ring 6, and each roller, including at least one of the dynamic surfaces 11. . According to the rolling bearing 1 of the present embodiment, surface-originated peeling can be suppressed from occurring on at least one of the first raceway surface 4, the second raceway surface 7, and the rolling surface 11 of each roller. Thus, a rolling bearing 1 having a long life can be provided.

(Embodiment 2)
A rolling bearing 1b according to a second embodiment will be described with reference to FIGS. 9 and 10. The rolling bearing 1b of this 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 plurality of rolling elements 10b are plural 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).

A 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 a second radius of at least one of the inner ring 3 and outer ring 6 in the circumferential direction (x direction) of the rolling bearing 1b. It is 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 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).

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

The rolling bearing 1b of this embodiment has the same effects as the rolling bearing 1 of the first embodiment, as described below.

In the rolling bearing 1b of this embodiment, the plurality of rolling elements 10b are plural balls. In 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 equal to 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 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 equal to the first radius of curvature 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 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.

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 By making the second residual compressive stress σ _x0 larger than the second residual compressive stress σ x0 in at least one circumferential direction (x direction) of the 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 the outer ring 6 decreases. According to the rolling bearing 1b of the present embodiment, the occurrence of surface-originated peeling 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 may be provided.

Embodiment 1 and Embodiment 2 disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

Reference Signs List 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 (7)

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, and further comprising:
A plurality of rolling elements are provided between the inner ring and the outer ring, each of the plurality of rolling elements having a rolling surface that contacts the first raceway surface and the second raceway surface. and
The first raceway surface is the surface of the inner ring that contacts the plurality of rolling elements, the second raceway surface is the surface of the outer ring that contacts the plurality of rolling elements, and the rolling surface is the surface of the outer ring that contacts the plurality of rolling elements. a surface of the rolling element that contacts the first raceway surface and the second raceway surface,
The first residual compressive stress in the axial direction of the inner ring and the outer ring of at least one of the first raceway surface, the second raceway surface, and the rolling surface is A rolling bearing that is larger than a second residual compressive stress in the circumferential direction of the at least one inner ring and the outer ring of the raceway surface and the rolling surface. The first equivalent stress in the at least one of the first raceway surface, the second raceway surface, and the rolling surface is the first equivalent stress in the at least one of the first raceway surface, the second raceway surface, and the rolling surface. The second equivalent stress is smaller than the second equivalent stress of each of the inner ring, the outer ring, and the plurality of rolling elements having the at least one, and the second equivalent stress is smaller than the second equivalent stress of the inner ring, the outer ring, and the plurality of rolling elements. A rolling bearing according to claim 1, wherein the maximum value of the equivalent stress within the at least one of each of the rolling elements. The residual compressive stress in the at least one axial direction of each of the inner ring, the outer ring, and the plurality of rolling elements is the residual compressive stress in the at least one thickness direction of each of the inner ring, the outer ring, and the plurality of rolling elements. The rolling bearing according to claim 1 or 2, wherein the rolling bearing is maximum at at least one of the first raceway surface, the second raceway surface, and the rolling surface. The residual compressive stress in the at least one axial direction of each of the inner ring, the outer ring, and the plurality of rolling elements is the residual compressive stress in the at least one thickness direction of each of the inner ring, the outer ring, and the plurality of rolling elements. The rolling bearing according to claim 1 or 2, wherein the rolling bearing reaches its maximum inside the at least one of each of the inner ring, the outer ring, and the plurality of rolling elements. The ratio of the first residual compressive stress to the maximum contact pressure acting between each of the plurality of rolling elements and at least one of the inner ring and the outer ring is -0.7 or more and less than 0.0. , The rolling bearing according to any one of claims 1 to 4. The rolling bearing according to any one of claims 1 to 5, wherein the plurality of rolling elements are a plurality of rollers. The plurality of rolling elements are a plurality of balls,
Claims 1 to 3, 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. The rolling bearing according to any one of Item 5.

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