JP2008082377A - Rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To elongate durability of a rolling device by suppressing increase of surface roughness and applying compression residual stress to a rolling element raceway surface applied with surface finishing. <P>SOLUTION: The rolling device 1 is provided with an outer ring 10 having an outer ring side rolling element raceway surface 14 on an inner diameter face 12, an inner ring 20 having an inner ring side rolling element raceway surface 24 facing the outer ring side rolling element raceway surface 14 on an outer diameter face 22, and a plurality of rolling elements 30 loaded so as to freely roll between both rolling element raceway surfaces 14, 24. The outer ring side rolling element raceway surface 14 and the inner ring rolling element raceway surface 24 are provided as machined raceway surfaces applied with surface finishing, and by hitting the machined raceway surfaces with substantially spherical glass beads with a mean particle diameter of 30-200 μm, the surface roughness of a portion hit with the glass beads is provided within a range of 0.04-0.25Ra, and the surface residual stress of the portion hit with the glass beads is provided within a range from -140 to -90 MPa. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling device such as a rolling bearing, and more particularly to the extension of the life of a rolling device in which damage to the raceway surface becomes a problem, and particularly to the extension of the life of a large-diameter rolling device.

Since rolling devices such as rolling bearings repeatedly receive shear stress under high surface pressure during use, in order to withstand the shear stress and ensure a rolling fatigue life, for example, high carbon chromium bearing steel such as SUJ2 is used as a material. Is formed. Moreover, hardness is set to the range of HRC58-64 by performing the quenching and tempering process to the high carbon chromium bearing steel used as a material.
Further, in rolling bearings made of case-hardened steel such as SCr420, SCM420, SAE4320H, etc., the surface hardness is set in the range of HRC58 to 64 by performing carburizing, carbonitriding or quenching and tempering. The core hardness is set in the range of HRC30-48.

  However, in recent years, maintenance-free rolling devices and reduction in fuel consumption of automobiles equipped with rolling devices have been demanded, and the use conditions of the rolling devices have become severe. For this reason, foreign matter mixed in the lubricating oil used in the rolling device and damage and peeling of the bearing surface due to poor lubrication of the rolling device are problematic, and the long life of the rolling device under such severe use conditions There is a growing demand for aging.

In response to such a demand, for example, Patent Documents 1 to 3 shown below propose a rolling device that can extend the life by focusing on the compressive residual stress effective in rolling fatigue. .
In the rolling device described in Patent Document 1, the surface of the rolling element raceway surface is obtained by performing barrel finishing on the roughened surface after the rolling body raceway surface of the outer ring and the inner ring is roughened by shot blasting. Is the oil pool shape, and the minimum value of the compressive residual stress in the surface layer portion from the surface of the rolling element raceway surface to a depth of 100 μm is 90 MPa or more.

With such a rolling device, the surface layer portion has a high compressive residual stress and a large number of specific minute depressions are formed, so that a stable oil film is formed on the surface of the rolling element raceway surface. Thus, the life of the rolling device can be extended.
In addition, the rolling device described in Patent Document 2 sets the maximum compressive residual stress in the outermost surface portion of the rolling element raceway surface to 100 kgf / mm ² or more, and compresses at a position 300 μm below the surface of the rolling element raceway surface. The residual stress is 40 kgf / mm ² or more.

With such a rolling device, the hardness of the outermost surface portion of the rolling element raceway surface is improved, so that indentations due to foreign matter are less likely to be formed on the rolling element raceway surface, and the rolling device is in a contaminated lubrication environment. Even when used, it is possible to extend the life of the rolling device.
Moreover, the rolling device described in Patent Document 3 has a maximum compressive residual stress in the surface layer portion of 50 to 50 mm when the depth from the surface of the rolling element raceway surface is in the range of 0 to 50 μm. While being within the range of 110 kgf / mm ² , the average wavelength of the surface roughness of the rolling element raceway surface is 25 μm or less.

With such a rolling device, peeling of a depth of about 5 to 10 μm is unlikely to occur on the surface of the rolling element raceway surface, so even if the rolling device is used in a severe lubricating environment. The life of the rolling device can be extended.
Japanese Patent Application No. 7-43239 (FIG. 1) Japanese Patent No. 2949794 (FIG. 1) Japanese Patent No. 3125434 (FIG. 1)

However, the conventional rolling device described above may cause the following problems.
In the rolling device described in Patent Document 1, after the rolling element raceway surface is roughened by shot blasting, barrel finishing is performed on the roughened surface so that the workpiece is rotated in the basket. Due to the characteristics, there is a possibility that the outer ring and the inner ring are limited to a small-diameter shape and size such as a cam follower outer ring. Therefore, for example, it is difficult to apply to a large-diameter rolling device whose inner diameter exceeds 80 mm.

  Moreover, in the rolling device described in Patent Document 2, only the maximum compressive residual stress at the outermost surface portion of the rolling element raceway surface and the compressive residual stress at a position of 300 μm below the surface of the rolling element raceway surface are defined. The surface roughness of the rolling element raceway surface is not specified. Moreover, since a shot material having a large particle diameter (for example, a steel ball having an average particle diameter of 0.72 mm) that is used for general purposes is often used, the surface roughness after the treatment inevitably increases. For this reason, in order to obtain a surface roughness that can actually be used as a rolling device, it is necessary to finish the surface by performing a separate polishing process after shot peening. However, in particular, in a rolling device having a large diameter and a large grinding allowance, there is a possibility that the surface layer to which the compressive stress is applied may be removed by the machining allowance, which is difficult to apply.

Further, in the rolling device described in Patent Document 3, since it is assumed that the mating surface is used on a relatively rough surface such as a cam follower outer ring, so-called “familiarity” is improved. In addition, the surface roughness after the treatment is defined in a wide range. For this reason, for example, in an application where the mating surface is a mirror surface, there is a possibility that a problem of causing damage to the mating surface may occur, which makes it difficult to apply.
The present invention has been made paying attention to the above-mentioned problems, and can suppress the increase in surface roughness and impart compressive residual stress to the rolling element raceway surface subjected to surface finishing. It is an object to provide a simple rolling device.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention is an outer ring having an outer ring side rolling element raceway surface on an inner diameter surface, and an outer diameter surface facing the outer ring side rolling element raceway surface. In a rolling device comprising an inner ring having an inner ring-side rolling element raceway surface, and a plurality of rolling elements loaded so as to be freely rollable between both rolling element raceway surfaces,
At least one of the outer ring-side rolling element raceway surface and the inner ring-side rolling element raceway surface is a surface-finished processing raceway surface,
At least the processed orbital surface is collided with spherical or substantially spherical nonmetallic particles having an average particle diameter of 30 to 200 μm, so that the surface roughness of the portion with which the nonmetallic particles collide is 0.04 to 0.25 Ra. And the surface residual stress at the portion where the non-metallic particles collide is in the range of -140 to -90 MPa.

According to the present invention, spherical or substantially spherical nonmetallic particles having an average particle diameter of 30 to 200 μm are collided with the surface of the processed raceway surface, whereby the surface roughness of the portion where the nonmetallic particles are collided is reduced. The surface residual stress at the portion where the nonmetallic particles collide with each other is in the range of -140 to -90 MPa in the range of 0.04 to 0.25 Ra.
For this reason, it is possible to suppress an increase in surface roughness and to apply a compressive residual stress to the portion where the nonmetallic particles collide, and to extend the life of the portion where the nonmetallic particles collide. .
In addition, since it is a relatively simple process of causing non-metallic particles to collide with the surface of the processed raceway surface, the shape and size of the outer ring and inner ring to be processed are not limited, and the process It is possible to increase the types of outer rings and inner rings to which can be applied.

Next, the invention described in claim 2 is the invention described in claim 1, characterized in that the surface finishing process is a super-finishing process.
According to the present invention, since the surface finishing process applied to at least one of the outer ring side rolling element raceway surface and the inner ring side rolling element raceway surface is a superfinishing process, a stable oil film can be formed on the surface of the processing raceway surface. This makes it possible to extend the life of the rolling device.

Next, the invention described in claim 3 is the invention described in claim 1 or 2, wherein the non-metallic particles are glass beads.
According to the present invention, since the non-metallic particles that collide with at least the processing raceway surface are glass beads, it is easy to suppress an increase in the surface roughness of the portion with which the glass beads are collided.

Next, the invention described in claim 4 is the invention described in claim 1 or 2, wherein the non-metallic particles are ceramic beads.
According to the present invention, since the non-metallic particles that collide with at least the processing raceway surface are made of ceramic beads, it is easy to suppress an increase in the surface roughness of the portion with which the ceramic beads collide.

  According to the present invention, it is possible to suppress the increase in surface roughness and to apply compressive residual stress to the rolling element raceway surface that has undergone surface finishing processing, thereby extending the life of the rolling device. It becomes.

Next, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view for explaining a rolling device 1 which is an example of this embodiment and a life tester 2 of the rolling device 1. In the present embodiment, a tapered roller bearing using a tapered roller as a rolling element will be described as an example of the rolling device.

The specifications of the tapered roller bearing are as follows.
Identification number: HR32017XJ
Bearing inner diameter: 85mm
Bearing outer diameter: 130mm
Assembly width: 29mm
Basic dynamic load rating: 143000N

The properties of the tapered roller bearing are as follows.
Surface hardness: HRC58-64
Surface retained austenite: 3 to 10% by volume
Note that the specifications and properties of the rolling device 1, that is, the tapered roller bearing are not limited to the above values.
As shown in FIG. 1, the rolling device 1 of this embodiment includes an outer ring 10, an inner ring 20, and a plurality of rolling elements 30.

The outer ring 10 and the inner ring 20 are made of SUJ2 that has been baked.
The outer ring 10 has an outer ring side rolling element raceway surface 14 on an inner diameter surface 12, and is attached to a housing 4 as a rotating body via a fitting member 6. The fitting member 6 is fixed to an axial load loading means (not shown), and this axial load loading means functions to load the rolling device 1 with an axial load by applying an axial load Fs to the fitting member 6. have.

  The outer ring-side rolling element raceway surface 14 is a machining raceway surface that has been surface-finished by superfinishing. The processing raceway surface, that is, the outer ring-side rolling element raceway surface 14 has a surface roughness of 0 by colliding with a substantially spherical shot material having an average particle diameter of 30 to 200 μm (hereinafter referred to as “shot peening”). 0.04 to 0.25 Ra, and the surface residual stress is in the range of −140 to −90 MPa.

Non-metallic particles are used as the shot material. In the present embodiment, a case where glass beads are used as non-metallic particles will be described as an example.
As a method of shot peening, a general-purpose shot peening apparatus was used, the injection pressure was set in the range of 2.0 to 6.0 kg / cm ² , and the injection time was set in the range of 10 to 20 min. Moreover, the weight of the rolling device 1 in one shot peening process was set within the range of 1 to 20 kgf.

  The inner ring 20 has an inner ring side rolling element raceway surface 24 facing the outer ring side rolling element raceway surface 14 on the outer diameter surface 22, and a bearing seat 8 a that forms one end of the rotation axis 8 on the rotation axis 8. Is fixed. The rotating shaft 8 is fixed to a radial load loading means (not shown), and this radial load loading means has a function of applying a radial load to the rolling device 1 by applying a radial load Fr to the rotating shaft 8. is doing.

Like the outer ring-side rolling element raceway surface 14, the inner ring-side rolling element raceway surface 24 is a machining raceway surface that has been surface-finished by superfinishing. Further, the inner ring-side rolling element raceway surface 24 has a surface roughness in the range of 0.04 to 0.25 Ra and a surface residual stress of −140 by the same method as the outer ring-side rolling element raceway surface 14. It is in the range of -90 MPa.
Each rolling element 30 is slidably loaded between the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 and is formed by tapered rollers.

  In addition, a lubricant (not shown) having a high viscosity such as grease is disposed in a gap formed between the outer ring 10 and the inner ring 20. Here, the gap formed between the outer ring 10 and the inner ring 20 includes the gap formed between the outer ring-side rolling element raceway surface 14 and the rolling element 30, and the inner ring-side rolling element raceway surface 24. Both of the gaps formed between the rolling elements 30 are included.

Next, functions and effects of the rolling device 1 having the above-described configuration will be described.
Hereinafter, a life test of the rolling device 1 using the life test machine 2 will be described.
The conditions of the life test are shown below.
Radial load: 35750N
Axial load: 15680N
Inner ring speed: 1500rpm
Lubricant: Pure grease lubrication or water-mixed grease Grease amount: 60 g
Foreign matter in grease: average particle size 70-140 μm
Hardness of foreign matter in grease: 64HRc
Amount of foreign matter in grease: 0.05 g

  During the test, the life tester 2 is stopped when the frequency of the life tester 2 becomes five times the initial frequency. Then, the presence or absence of damage on the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 is confirmed by a stereomicroscope. If there is no damage, the test is restarted, and if there is damage, the test is terminated.

  Tables 1 and 2 show the results of the life test. Table 1 shows various conditions and life ratios in Examples and Comparative Examples, and Table 2 shows a graph comparing the life ratios described in Table 1 for each Example and Comparative Example. ing. The life ratio shown in Table 1 and Table 2 is the life time of Comparative Example 1, which is an untreated product, that is, when the frequency of the life tester 2 becomes five times the initial frequency, The test time when the moving body raceway surface 14 and the inner ring-side rolling element raceway surface 24 are damaged is defined as a reference value (1.0), and the ratio to the reference value is shown.

As shown in Tables 1 and 2, the rolling devices of Examples 1 to 6 have a life ratio in the range of 5.1 to 6.1 times that of the rolling device of Comparative Example 1. The service life is greatly extended.
On the other hand, the rolling device of Comparative Example 2 is different from the rolling device of the present invention in the type and shape of the shot material, and uses SiC (silicon ceramics) particles having an acute angle portion as the shot material. The surface roughness of the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 is increased. As a result, the life ratio is 0.8 times that of the rolling device of Comparative Example 1, and the life is shortened.

  Further, the rolling device of Comparative Example 3 has an average particle size of the shot material of 350 μm, which exceeds the upper limit of the average particle size in the rolling device of the present invention, so the outer ring side rolling element raceway surface 14 and the inner ring The compressive residual stress of the side rolling element raceway surface 24 is greatly reduced to -150 MPa. As a result, the life ratio is 0.6 times that of the rolling device of Comparative Example 1, and the life is shortened.

Further, in the rolling device of Comparative Example 4, the compressive residual stress of the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 is −60 MPa, and the upper limit value of the compressive residual stress in the rolling device of the present invention is set. Over. As a result, the life ratio is 1.6 times that of the rolling device of Comparative Example 1, and although the life is extended, the effect of extending the life is not sufficiently obtained.
Therefore, in the rolling device 1 according to the present embodiment, the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 are set as surface-finished machining raceway surfaces, and the average particle diameter is set on the machining raceway surface. By performing shot peening with a substantially spherical shot material of 30 to 200 μm, the surface roughness of the processed raceway surface is set within the range of 0.04 to 0.25 Ra, and the surface residual stress is set within the range of −140 to −90 MPa. It is said.

As a result, it is possible to suppress an increase in surface roughness and to apply a compressive residual stress to the surface-finished processing raceway surface, that is, the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24. Therefore, the life of the rolling device 1 can be extended.
Further, in the rolling device 1 of the present embodiment, the outer ring-side rolling element track is made by a relatively simple process of causing non-metallic particles to collide with the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24. It is possible to suppress an increase in surface roughness and to apply compressive residual stress to the surface 14 and the inner ring side rolling element raceway surface 24.

As a result, the shape and size of the outer ring 10 and the inner ring 20 to be processed are not limited, and the types of the outer ring 10 and the inner ring 20 to which the process can be applied can be increased. It is possible to increase the types of applicable rolling devices 1.
In particular, it is difficult to apply the conventional treatment, for example, it can be applied to a large-diameter rolling device 1 having an inner diameter exceeding 80 mm, and the long life of the large-diameter rolling device 1 is long. Can be realized.

Furthermore, in the rolling device 1 of the present embodiment, substantially spherical glass beads having an average particle diameter of 30 to 200 μm are used as the shot material.
For this reason, the surface of the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 is not subjected to the polishing process on the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 after shot peening. The roughness can be set to a surface roughness that can be used as the rolling device 1.

As a result, the present invention can be applied to the case where the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 to be processed are mirror-finished, and the outer ring 10 and the inner ring 20 to which the process can be applied. Therefore, it is possible to increase the types of rolling devices 1 to which the process can be applied.
Moreover, since it is not necessary to perform a grinding | polishing process with respect to the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 after shot peening, it becomes possible to reduce the manufacturing cost of the rolling device 1. It becomes possible to improve the manufacturing efficiency of the rolling device 1.

In the rolling device 1 according to the present embodiment, the surface finishing process applied to the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 is a superfinishing process, and thus the outer ring-side rolling element raceway surface 14. In addition, a stable oil film can be formed on the surface of the inner ring-side rolling element raceway surface 24.
As a result, the life of the rolling device 1 can be extended.
Further, in the rolling device 1 of the present embodiment, since the non-metallic particles that collide with the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 are glass beads, that is, the portion where the glass beads collide, that is, It becomes easy to suppress the increase in the surface roughness of the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24.

  In the rolling device 1 of the present embodiment, both the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 are surface-finished machining raceway surfaces, but the present invention is not limited to this. Alternatively, one of the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 may be a surface-finished machining raceway surface. In short, at least one of the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 may be a surface-finished machining raceway surface. However, like the rolling device 1 of the present embodiment, both the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 are set as surface-finished machining raceway surfaces, and the machining raceway surface is It is preferable to perform shot peening because the rolling device 1 can be effectively extended in life.

  In the rolling device 1 of the present embodiment, shot peening is performed on the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24. However, the present invention is not limited to this. Shot peening may be performed on other parts including the moving body raceway surface 14 and the inner ring-side rolling element raceway surface 24. In short, shot peening may be performed on at least the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24.

  Furthermore, in the rolling device 1 of the present embodiment, the substantially spherical shot material is caused to collide with the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24. However, the present invention is not limited to this. . That is, the spherical shot material may collide with the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24. In short, by making a spherical or substantially spherical shot material having an average particle diameter of 30 to 200 μm collide, the surface roughness of the portion where the shot material is collided is within the range of 0.04 to 0.25 Ra, and the shot is shot. What is necessary is just to make the surface residual stress of the part which made the material collide into the range of -140--90MPa.

  In the rolling device 1 of the present embodiment, the surface finishing process performed on the outer ring side rolling element raceway surface 14 and the inner ring side rolling element raceway surface 24 is a superfinishing process, but is not limited thereto. The surface finishing process performed on the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 may be, for example, a buffing process. Further, the surface finishing processing performed on the outer ring-side rolling element raceway surface 14 and the inner ring-side rolling element raceway surface 24 may be different from each other.

  In the rolling device 1 of the present embodiment, glass beads are used as the shot material. However, the type of the shot material is not limited to this, for example, ceramic beads or the like as the shot material other than glass beads. Non-metallic particles may be used. In short, the type of the shot material may be any non-metallic particle that makes it easy to suppress an increase in the surface roughness of the portion where the shot material collides.

  Moreover, in the rolling device 1 of this embodiment, the rolling element 30 is formed by a tapered roller, and the rolling device 1 is a tapered roller bearing. However, the configuration of the rolling device 1 is limited to this. is not. That is, for example, the rolling element 30 may be formed of a cylindrical roller, the rolling device 1 may be a cylindrical roller bearing, the rolling element 30 may be formed of a steel ball, and the rolling device 1 may be a ball bearing.

  Further, in the rolling device 1 of the present embodiment, the outer ring 10 and the inner ring 20 are formed using SUB2 that has been burned, but the present invention is not limited to this. That is, the outer ring 10 and the inner ring 20 may be formed using, for example, carbonitrided SUJ2 as a material, or may be formed using SUJ2 subjected to induction hardening. Further, the outer ring 10 and the inner ring 20 may be made of, for example, a material whose surface is hardened by carbonitriding or carburizing a case-hardened steel such as SCM420 or SCr420.

It is sectional drawing for demonstrating the rolling device which is an example of this embodiment, and the lifetime tester of a rolling device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling device 2 Life test machine 4 Housing 6 Fitting member 8 Rotating shaft 10 Outer ring 12 Inner ring surface 14 Outer ring side rolling element raceway surface 20 Inner ring 22 Outer diameter surface 24 Inner ring side rolling element raceway surface 30 Rolling element Fs Axial load Fr Radial load

Claims (4)

An outer ring having an outer ring-side rolling element raceway surface on an inner diameter surface, an inner ring having an inner ring-side rolling element raceway surface facing the outer ring-side rolling element raceway surface on an outer diameter surface, and rolling between both rolling element raceway surfaces A plurality of rolling elements loaded in the rolling device,
At least one of the outer ring-side rolling element raceway surface and the inner ring-side rolling element raceway surface is a surface-finished processing raceway surface,
At least the processed orbital surface is collided with spherical or substantially spherical nonmetallic particles having an average particle diameter of 30 to 200 μm, so that the surface roughness of the portion with which the nonmetallic particles collide is 0.04 to 0.25 Ra. And a surface residual stress at a portion where the nonmetallic particles collide with each other is in a range of −140 to −90 MPa.   The rolling device according to claim 1, wherein the surface finishing process is a super-finishing process.   The rolling device according to claim 1, wherein the non-metallic particles are glass beads.   The rolling device according to claim 1, wherein the non-metallic particles are ceramic beads.

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