JP2016196958A - Rolling device and rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling device which can be manufactured in a simple processing method, for achieving a longer life by suppressing its surface damage even when used with rolling parts having lower oil film formability, and to provide a rolling bearing.SOLUTION: A deep groove ball bearing 1 includes an outer ring 11, an inner ring 12, and balls 13. The arithmetic mean roughness of the surface of the rolling part of each of the outer ring 11 and the inner ring 12 is larger than the arithmetic mean roughness of the surface of the rolling part of each of the balls 13. The Rockwell hardness of the surface of the rolling part of each of the outer ring 11 and the inner ring 12 is lower than the Rockwell hardness of the surface of the rolling part of each of the balls 13. The surfaces of the rolling parts of the outer ring 11 and the inner ring 12 are subjected to chemical treatment after tempering treatment. With the chemical treatment, coatings 11B, 12B including at least one of iron oxide and compound are formed on the surfaces of the rolling parts of the outer ring 11 and the inner ring 12, respectively.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rolling device and a rolling bearing, and particularly to a rolling device and a rolling bearing provided with first and second rolling parts.

  When a rolling device such as a rolling bearing is used in an environment where oil film formation is insufficient due to poor lubrication of the rolling part, surface damage such as peeling and seizure and peeling caused by this surface damage may occur. Occurs on the surface of moving parts. Thereby, the lifetime of a rolling device falls. For example, the paper “Lubrication” (Non-Patent Document 1) describes a rolling bearing under the condition that the oil film parameter Λ indicating the severity of the lubrication state is about 1.2 or more between the inner and outer rings of the rolling bearing and the rolling elements. However, it is described that, when the hydraulic parameter Λ is 1.2 or less, surface-lamination type peeling occurs in the rolling part, so that the life of the rolling bearing is reduced.

  As a general countermeasure against surface damage of a rolling bearing used in a state where oil film formation is poor, there is a method of reducing the surface roughness of the rolling portion of the rolling bearing by polishing or superfinishing. As another surface damage countermeasure, for example, in Japanese Patent Application Laid-Open No. 2006-161887 (Patent Document 1), a minute concave portion is formed in a roller or a rolling portion of an inner and outer ring of a needle roller bearing, and solid lubrication is performed in the concave portion. A method of coating the agent is described. In addition, for example, Japanese Patent No. 2997074 (Patent Document 2) describes a method of forming minute concave portions at random in a rolling portion to enhance oil film forming ability.

JP 2006-161887 A Japanese Patent No. 2997074

Takada, H., Suzuki, Susumu Maeda, Lubrication, 26, 9, (1981), p. 645-650

  In the method of reducing the surface roughness of the rolling part of the rolling bearing by the above polishing and superfinishing, the surface roughness may not be sufficiently reduced because the processing is difficult depending on the shape and dimensions of the processing member. . Moreover, in the method described in each of the above publications, since the recess is formed in the rolling part, the machining process is complicated.

  The present invention has been made in view of the above problems, and its object is to suppress the surface damage even if it can be manufactured by a simple processing method and is used in a state where the oil film forming property of the rolling part is poor. It is providing the rolling device and rolling bearing which implement | achieve a lifetime.

  The rolling device according to the present invention includes a first rolling part made of JIS standard SUJ2, and a second rolling part made of JIS standard SUJ2 in contact with the first rolling part. Each of the first and second rolling parts is tempered after being quenched. The arithmetic average roughness of the surface of the rolling part of the first rolling component is larger than the arithmetic average roughness of the surface of the rolling part of the second rolling component. The Rockwell hardness of the surface of the rolling part of the first rolling component is lower than the Rockwell hardness of the surface of the rolling part of the second rolling component. The surface of the rolling part of the first rolling part is subjected to a chemical conversion treatment after being tempered, and at least one of iron oxide and compound is formed on the surface of the rolling part of the first rolling part by chemical conversion treatment. A film containing such is formed.

  When the rolling device is used under the condition that the oil film forming property between the surfaces of the rolling parts of the first and second rolling parts is poor, between the surfaces of the rolling parts of the first and second rolling parts, There is interference between minute roughness protrusions. According to the rolling device of the present invention, the surface of the rolling part of the first rolling part has an arithmetic average roughness larger than that of the surface of the rolling part of the second rolling part, and has a Rockwell hardness. Low. Furthermore, a film containing at least one of an iron oxide and a compound is formed on the surface of the rolling portion of the first rolling component by chemical conversion treatment. For this reason, after a short time has elapsed from the start of operation of the rolling device, the minute roughness protrusions on the surface of the rolling part of the first rolling part come into contact with the surface of the rolling part of the second rolling part. Thereby, the inclination of the minute roughness protrusion of the surface of the rolling part of the first rolling component can be reduced. Thereby, the local surface pressure of the minute roughness protrusion of the surface of the rolling part of the 1st rolling component and the surface of the rolling part of the 2nd rolling component which contacts this roughness protrusion falls. Therefore, damage to the surface of the rolling part of the second rolling component due to contact with the roughness protrusion can be suppressed. Therefore, the lifetime reduction of the rolling device due to damage of the surface of the rolling part of the second rolling component can be suppressed. Therefore, the long life of the rolling device can be realized. Further, by making the Rockwell hardness of the rolling part of the first rolling part lower than the Rockwell hardness of the rolling part of the second rolling part, the surface of the rolling part of the second rolling part is reduced. The progress of fatigue can be suppressed. With these effects, a long life of the rolling device can be realized.

  In the above rolling device, preferably, the coating contains triiron tetroxide. For this reason, the minute roughness protrusion on the surface of the rolling part of the first rolling component can be made brittle. Therefore, the minute roughness protrusions on the surface of the rolling part of the first rolling part come into contact with the surface of the rolling part of the second rolling part, so that the rolling part of the first rolling part It is easy to reduce the inclination of minute roughness protrusions on the surface.

  Preferably, in the above rolling device, the Rockwell hardness of the surface of the rolling part of the first rolling part is 0.5 or more lower than the Rockwell hardness of the surface of the rolling part of the second rolling part. . For this reason, the rolling part of the 2nd rolling component by the minute roughness protrusion of the surface of the rolling part of the 1st rolling component contacting the surface of the rolling part of the 2nd rolling component The progress of surface fatigue can be delayed. The Rockwell hardness is the Rockwell hardness C scale (HRC).

  In the above rolling device, preferably, the Rockwell hardness of the surface of the rolling part of the second rolling component is 61.5 HRC or more. For this reason, the rolling part of the 2nd rolling component by the minute roughness protrusion of the surface of the rolling part of the 1st rolling component contacting the surface of the rolling part of the 2nd rolling component The progress of surface fatigue can be further delayed.

  In the above rolling device, preferably, the first rolling component has a Rockwell hardness of 60.0 HRC. For this reason, it is possible to prevent the rolling fatigue life of the rolling device from being reduced due to the hardness reduction of the first rolling component.

  In the above rolling device, the surface of the rolling part of the first rolling component is not superfinished, and its arithmetic average roughness is about 0.15 to 0.7 μm. The root mean square slope of the curve is about 0.15 to 0.30. On the other hand, the surface of the rolling part of the second rolling part is superfinished, and its arithmetic average roughness May be used under the condition that the root mean square slope of the roughness curve is about 0.10 or less. When the arithmetic mean roughness and root mean square slope of the surface of the rolling part of the first rolling part cannot be reduced due to the shape and dimensions of the first rolling part, the above combination condition of roughness is satisfied. In some cases, surface damage (particularly peeling) is likely to occur in the rolling part of the second rolling component. However, even in this case, the inclination of the minute roughness protrusions on the surface of the rolling part of the first rolling component can be sufficiently reduced by applying the above surface treatment. For this reason, the fall of the lifetime of a rolling device by the surface damage (especially peeling) of the rolling part of a 2nd rolling component can be suppressed. Further, even in the above case, by applying the above hardness difference and limiting the hardness of the second rolling part, it is possible to suppress the progress of fatigue on the surface of the rolling part of the second rolling part. . For this reason, the fall of the lifetime of a rolling device by the surface damage (especially peeling) of the rolling part of a 2nd rolling component can be suppressed.

  The rolling bearing of this invention is comprised by said rolling device. The rolling bearing includes an outer ring having an outer ring raceway surface on an inner peripheral surface, an inner ring having an inner ring raceway surface on an outer peripheral surface, and a plurality of rolling elements that roll between the outer ring raceway surface and the inner ring raceway surface. . The outer ring and the inner ring are composed of a first rolling part, and the rolling element is composed of a second rolling part. Therefore, it is possible to provide a rolling bearing in which the outer ring and the inner ring are composed of the first rolling component, and the rolling element is composed of the second rolling component. Therefore, even if the rolling bearing is used under conditions where oil film formation is poor because the lubrication state between each of the outer ring and the inner ring and the rolling element is poor, the outer ring raceway surface and the inner ring raceway surface have minute roughness protrusions. Damage to the surface of the rolling part of the rolling element due to contact can be suppressed. Thereby, the long life of a rolling bearing is realizable.

  In the above rolling bearing, even when used under the condition that the oil film parameter is 1.2 or less in the lubrication between each of the outer ring and the inner ring and the rolling element, a minute roughness protrusion on the surface of the rolling part The inclination can be made sufficiently small and damage to the surface of the rolling part can be suppressed. Thereby, the long life of a rolling bearing can be realized effectively.

  As described above, according to the present invention, rolling that can be manufactured by a simple processing method and realizes a long life by suppressing surface damage even when used in a state where the oil film forming property of the rolling part is poor. Devices and rolling bearings can be provided.

It is a schematic sectional drawing which shows the structure of the deep groove ball bearing in one embodiment of this invention. It is an enlarged view which shows the structure of the P section of FIG. It is the schematic which shows the structure of the two-cylinder testing machine in an Example. It is a microscope enlarged photograph which shows the surface of the rolling part of the standard goods after the peeling-proof performance evaluation test in an Example, and the driven side test piece of Example 1. FIG. It is a microscope enlarged photograph which shows the surface of the rolling part of the driven side test piece of Example 2 and Example 3 after the peeling-proof performance evaluation test in an additional Example. It is a microscope enlarged photograph which shows the surface of the rolling part of the driven side test piece of Example 4 and Example 5 after the peeling-proof performance evaluation test in an additional Example. It is a microscope enlarged photograph which shows the surface of the rolling part of the driven side test piece of Example 6 and Example 7 after the peeling-proof performance evaluation test in an additional Example. It is a microscope enlarged photograph which shows the surface of the rolling part of the driven side test piece of Example 8 and Example 9 after the peeling-proof performance evaluation test in an additional Example. It is a microscope enlarged photograph which shows the surface of the rolling part of the driven side test piece of Example 10 after the peeling-proof performance evaluation test in an additional Example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a configuration of a rolling bearing as an example of a rolling device according to an embodiment of the present invention will be described. In this embodiment, a deep groove ball bearing will be described as an example of a rolling bearing.

  With reference to FIG. 1, the deep groove ball bearing 1 of the present embodiment is disposed between an annular outer ring 11, an annular inner ring 12 disposed inside the outer ring 11, and the outer ring 11 and the inner ring 12. And a plurality of balls 13 as rolling elements held by an annular retainer 14. The outer ring 11 has an outer ring raceway surface 11A on the inner peripheral surface. The inner ring 12 has an inner ring raceway surface 12A on the outer peripheral surface. That is, the outer ring raceway surface 11 </ b> A is formed on the inner peripheral surface of the outer ring 11, and the inner ring raceway surface 12 </ b> A is formed on the outer peripheral surface of the inner ring 12. The outer ring 11 and the inner ring 12 are arranged so that the outer ring raceway surface 11A and the inner ring raceway surface 12A face each other.

  Further, the balls 13 are configured to roll between the outer ring raceway surface 11A and the inner ring raceway surface 12A. The plurality of balls 13 are in contact with the outer ring raceway surface 11A and the inner ring raceway surface 12A at the ball rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by the cage 14, thereby rolling onto the annular raceway. It is held freely. Moreover, in the ball | bowl 13, the whole surface is the ball | bowl rolling surface 13A. With the above configuration, the outer ring 11 and the inner ring 12 of the deep groove ball bearing 1 are rotatable relative to each other.

  A grease composition (not shown) is sealed in a space sandwiched between the outer ring 11 and the inner ring 12, more specifically, a track space that is sandwiched between the outer ring raceway surface 11A and the inner ring raceway surface 12A. An oil film is formed between each of the outer ring 11 and the inner ring 12 and the ball 13 by this grease composition.

  With reference to FIG. 2, the outer ring | wheel 11, the inner ring | wheel 12, and the ball | bowl 13 as a rolling component which comprise the deep groove ball bearing 1 are demonstrated. The ball 13 as the second rolling member is in contact with each of the outer ring 11 and the inner ring 12 as the first rolling member. All of the outer ring 11, the inner ring 12 and the ball 13 are made of JIS standard SUJ2. Each of the outer ring 11, the inner ring 12 and the balls 13 is tempered after being quenched. The arithmetic average roughness Ra of the surface of the rolling part of each of the outer ring 11 and the inner ring 12 is larger than the arithmetic average roughness Ra of the surface of the rolling part of the ball 13. In the present embodiment, the surface of the rolling portion of the ball 13 is subjected to super finishing, and the surface of each rolling portion of the outer ring 11 and the inner ring 12 may not be subjected to super finishing. Superfinishing is a process of finishing a work surface by applying vibration while pressing a fine-grained grindstone against a work piece with a low pressure. The surface of the rolling part of each of the outer ring 11 and the inner ring 12 may be merely processed to an arithmetic average roughness Ra of 0.7 μm or less by polishing.

  The Rockwell hardness of each of the outer ring 11 and the inner ring 12 is lower than the Rockwell hardness of the ball 13. The Rockwell hardness of each of the outer ring 11 and the inner ring 12 is preferably 0.5 or more lower than the Rockwell hardness of the ball 13. The Rockwell hardness of each of the outer ring 11 and the inner ring 12 is preferably HRC60 or more. The Rockwell hardness of the ball 13 is preferably 61.5 HRC or more.

  The surfaces of the rolling parts of the outer ring 11 and the inner ring 12 are subjected to a chemical conversion treatment after being tempered. A film of at least one of iron oxide and compound is formed on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12 by chemical conversion treatment.

  The rolling part of the outer ring 11 is a region including the outer ring raceway surface 11A, and the surface of the rolling part of the outer ring 11 constitutes the outer ring raceway surface 11A. A film 11 </ b> B is formed on the surface of the rolling part of the outer ring 11. The rolling part of the inner ring 12 is an area including the inner ring raceway surface 12A, and the surface of the rolling part of the inner ring 12 constitutes the inner ring raceway surface 12A. A film 12 </ b> B is formed on the surface of the rolling part of the inner ring 12. The rolling part of the ball 13 is an area including the ball rolling surface 13A, and the surface of the rolling part of the ball 13 constitutes the ball rolling surface 13A.

  Each of the coating 11B formed on the surface of the rolling part of the outer ring 11 and the coating 12B formed on the surface of the rolling part of the inner ring 12 preferably contains iron trioxide. That is, each of the coating 11B formed on the surface of the rolling part of the outer ring 11 and the coating 12B formed on the surface of the rolling part of the inner ring 12 is preferably formed by blackening. Further, the oil film parameter in lubrication between each of the outer ring 11 and the inner ring 12 and the ball 13 may be 1.2 or less. The hydraulic parameter Λ is a ratio between the oil film thickness and the surface roughness.

Next, the effect of this Embodiment is demonstrated.
According to the deep groove ball bearing 1 of the present embodiment, the surface of each rolling part of the outer ring 11 and the inner ring 12 has an arithmetic average roughness larger than the surface of the rolling part of the ball 13 and has a Rockwell hardness. Low. Furthermore, coatings 11B and 12B containing at least one of an iron oxide and a compound are formed on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12 by chemical conversion treatment. For this reason, after a short time has elapsed from the start of operation of the deep groove ball bearing 1, the minute roughness protrusions on the surface of the rolling part of each of the outer ring 11 and the inner ring 12 come into contact with the surface of the rolling part of the ball 13. In addition, it is possible to reduce the inclination of minute roughness protrusions on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12. As a result, the local surface pressure between the minute roughness protrusions on the surface of the rolling part of the outer ring 11 and the inner ring 12 and the surface of the rolling part of the ball 13 in contact with the roughness protrusion is reduced. Damage to the surface of the rolling part of the ball 13 due to contact with the protrusion can be suppressed. Therefore, it is possible to suppress a decrease in the life of the deep groove ball bearing 1 due to damage to the surface of the rolling portion of the ball 13. Therefore, the long life of the deep groove ball bearing 1 can be realized. Further, by making the Rockwell hardness of each rolling part of the outer ring 11 and the inner ring 12 lower than the Rockwell hardness of the rolling part of the ball 13, the progress of fatigue on the surface of the rolling part of the ball 13 is suppressed. Can do. By these actions, the local surface pressure between the minute roughness protrusions on the surface of the rolling part of the outer ring 11 and the inner ring 12 and the surface of the rolling part of the ball 13 in contact with the roughness protrusion is reduced, and the ball Since the fatigue strength of 13 is improved, damage to the surface of the rolling portion of the ball 13 due to contact with the roughness protrusion can be suppressed. Therefore, it is possible to suppress a decrease in the life of the deep groove ball bearing 1 due to damage to the surface of the rolling portion of the ball 13. Therefore, the long life of the deep groove ball bearing 1 can be realized.

  Moreover, according to the deep groove ball bearing 1 of the present embodiment, the coating contains iron trioxide. For this reason, minute roughness protrusions on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12 can be made brittle. Accordingly, the minute roughness protrusions on the surface of the rolling part of each of the outer ring 11 and the inner ring 12 come into contact with the surface of the rolling part of the ball 13, thereby causing the minute roughness protrusions on the surface of the rolling part of the ball 13. It is easy to reduce the inclination of the.

  Further, according to the deep groove ball bearing 1 of the present embodiment, the Rockwell hardness of the surface of the rolling part of the outer ring 11 and the inner ring 12 is 0.5 or more than the Rockwell hardness of the surface of the rolling part of the ball 13. Low. For this reason, the rolling part of the 2nd rolling component by the minute roughness protrusion of the surface of the rolling part of the 1st rolling component contacting the surface of the rolling part of the 2nd rolling component The progress of surface fatigue can be delayed.

  Moreover, according to the deep groove ball bearing 1 of this Embodiment, the Rockwell hardness of the surface of the rolling part of the ball | bowl 13 is 61.5HRC or more. For this reason, the progress of fatigue on the surface of the rolling part of the ball 13 due to the minute roughness protrusions on the surface of the rolling part of the outer ring 11 and the inner ring 12 coming into contact with the surface of the rolling part of the ball 13 is delayed. be able to.

  The rolling of the ball 13 caused by repeated contact with the minute roughness protrusions on the surface of the rolling part of the outer ring 11 and the inner ring 12 due to the difference in hardness between the outer ring 11 and the inner ring 12 and the ball 13 and the limitation of the hardness of the ball 13. The progress of fatigue on the surface of the moving part can be suppressed. In addition, the surface of the rolling part of the outer ring 11 and the inner ring 12 is HRC60 or more. Further, since the average hardness of the outer ring 11, the inner ring 12 and the ball 13 can be maintained at 60 or more in HRC, it is possible to suppress a decrease in rolling fatigue life due to a decrease in the hardness of the rolling bearing. In addition, it is known as a common sense of a rolling bearing that when the bearing hardness is HRC 60 or less, the rolling fatigue life is reduced.

  Further, according to the deep groove ball bearing 1 of the present embodiment, the surface of the rolling part of the outer ring 11 and the inner ring 12 is not superfinished, and its arithmetic average roughness is 0.15 to 0. 0. The root mean square slope of the roughness curve is about 0.15 to 0.30, while the surface of the rolling part of the ball 13 is superfinished, and its arithmetic It may be used under the condition that the average roughness is about 0.1 μm or less and the root mean square slope of the roughness curve is about 0.10 or less. In the case where the arithmetic average roughness and root mean square slope of the surface of the rolling part of the outer ring 11 and the inner ring 12 cannot be reduced due to the shape and size of the outer ring 11 and the inner ring 12, the combination condition of the above roughness is satisfied. And surface damage (particularly peeling) is likely to occur at the rolling part of the ball 13. However, even in this case, by applying the hardness difference and the surface treatment, the inclination of the minute roughness protrusions on the surfaces of the rolling portions of the outer ring 11 and the inner ring 12 can be sufficiently reduced. For this reason, the lifetime reduction of the deep groove ball bearing 1 by the surface damage (especially peeling) of the rolling part of the ball | bowl 13 can be suppressed. Furthermore, the rolling fatigue strength of the surface of the rolling part of the ball 13 can be improved.

  Further, according to the deep groove ball bearing 1 of the present embodiment, the deep groove ball bearing 1 is used under conditions where the oil film formation is poor because the lubrication state between each of the outer ring 11 and the inner ring 12 and the ball 13 is poor. In addition, it is possible to suppress damage to the surface of the rolling portion of the ball 13 due to contact with the minute roughness protrusions of the outer ring raceway surface 11A and the inner ring raceway surface 12A. Thereby, the long life of the deep groove ball bearing 1 is realizable.

  Further, according to the deep groove ball bearing 1 of the present embodiment, even if it is used under the condition that the oil film parameter is 1.2 or less in the lubrication between each of the outer ring 11 and the inner ring 12 and the ball 13, the rolling The inclination of the minute roughness protrusion on the surface of the part can be sufficiently reduced, and damage to the surface of the rolling part can be suppressed. Thereby, the long life of the deep groove ball bearing 1 can be effectively realized.

Examples of the present invention will be described below.
Two types of test pieces having different combinations of materials using the two-cylinder testing machine shown in FIG. 3 (hereinafter referred to as a standard product, Example 1. The standard product is a comparative example, and Example 1 is an example of the present invention. The peel resistance evaluation test was conducted. Table 1 shows the test piece shape of the driving side (hereinafter referred to as D side) test piece (D side cylinder) and the driven side (hereinafter referred to as F side) test piece (F side cylinder) and the conditions of the rolling test. .

  A D-side specimen and an F-side specimen were prepared. The D-side test piece has a cylindrical shape with an outer diameter (diameter) of 40 mm, an inner diameter (diameter) of 20 mm, a width of 12 mm, and an axial secondary curvature radius of 60 mm. The axial surface roughness of the D-side test piece was polished to have an arithmetic average roughness Ra of about 0.65 μm and a root mean square slope RΔq of about 0.27. On the other hand, the F-side test piece has a cylindrical shape with an outer diameter (diameter) of 40 mm, an inner diameter (diameter) of 20 mm, a width of 12 mm, and an axial secondary curvature radius of 0 mm. The surface roughness in the axial direction of the rolling part of the F-side test piece was superfinished so that the arithmetic average roughness Ra was about 0.02 μm and the root mean square slope RΔq was about 0.013. As shown in Table 1, the rolling test conditions were such that peeling (small peeling) was likely to occur at the rolling part of the F-side test piece.

  The D side test piece was fixed to the drive side (D side) rotation shaft so as to be rotatable about the axis, and the F side test piece was fixed to the driven side (D side) rotation shaft so as to be rotatable about the axis. In this state, the outer peripheral surfaces of the D-side test piece and the F-side test piece were brought into contact with each other. The D-side rotating shaft was rotated by a motor while applying a load to the F-side test piece in a direction to bring the F-side test piece closer to the D-side test piece. As a result, the F-side test piece and the D-side test piece were rotated in opposite directions. At this time, the lubricating oil was supplied to the outer peripheral surfaces of the D-side test piece and the F-side test piece from the felt pad for oil supply impregnated with the lubricating oil. An additive-free poly-α-olefin oil (equivalent to VG5) was used as this lubricating oil. The test time was 4 hours. As test conditions, the rotation speed of the D-side rotation shaft was 2000 rpm. Furthermore, the load applied to the F-side test piece was 230 kgf.

  Next, Table 2 shows the conditions for creating the materials of the two types of test pieces.

  First, a standard product (comparative example) will be described. The steel material of the standard product (comparative example) was JIS standard SUJ2. For the D-side quenching method, a standard product (comparative example) was soaked at 850 ° C. for 1 hour and then cooled in oil at 80 ° C. The D side tempering temperature was 180 ° C. The D side tempering time was 2 hours. The F-side quenching method, the F-side tempering temperature, and the F-side tempering time were the same as the D-side quenching method, the D-side tempering temperature, and the D-side tempering time, respectively. The standard product (comparative example) was not treated with the triiron tetroxide film. Both the D-side width surface Rockwell hardness (Rockwell hardness C scale) and the F-side width surface Rockwell hardness (Rockwell hardness C scale (HRC)) were 62.2.

  Next, Example 1 will be described. The steel material of Example 1 is the same as a standard product (comparative example), and is JIS standard SUJ2. Regarding the D-side quenching method, Example 1 was soaked at 850 ° C. for 1 hour and then cooled in 80 ° C. oil as in the standard product (comparative example). The D side tempering temperature was 200 ° C. The D side tempering time was 10 hours. The F-side quenching method and the F-side tempering temperature were the same as the D-side quenching method and the D-side tempering temperature, respectively. Unlike the D-side tempering time, the F-side tempering time was 1 hour. The triiron tetroxide coating treatment of Example 1 was performed only on the D-side test piece. After quenching and tempering the D-side test piece, polishing and adjusting the shape of the test piece, the treated product is immersed for 30 minutes in an alkaline aqueous solution mainly composed of sodium hydroxide (NaOH) heated to 1400 ± 5 ° C. The film was processed. There was no change in surface roughness before and after coating treatment. The D-side width surface Rockwell hardness (Rockwell hardness C scale) was 60.7. The F-side width surface Rockwell hardness (Rockwell hardness C scale (HRC)) was 61.5.

  The microscope picture of the rolling part of the F side test piece after a test is shown in FIG. A lot of peeling occurred in the standard product (comparative example), but no peeling occurred in Example 1. Table 3 shows the measurement results of the axial roughness of the rolling part of the D-side test piece after the test. Compared with the standard product (comparative example), the value of root mean square slope RΔq representing the slope of the roughness protrusion in Example 1 was lower. From these results, the D-side test piece having a large surface roughness of the rolling part is subjected to a triiron tetroxide coating treatment with a low hardness, and a combination of materials with a high hardness is applied to the F-side test piece. It was found that the roughness of the moving part has a small inclination and the peeling can be suppressed.

Additional examples of the present invention are described below.
Using the two-cylinder testing machine shown in FIG. 3, a peeling resistance evaluation test was performed on nine types of test pieces (hereinafter referred to as Examples 2 to 10) having different combinations of hardness. Examples 2, 5, 6, 8, 9, and 10 are comparative examples, and Examples 3, 4, and 7 are examples of the present invention. Table 4 shows the specimen shape of the D-side specimen and the F-side specimen and the conditions of the rolling test. Table 5 shows the combinations of the hardnesses of the nine types of test pieces.

  A D-side specimen and an F-side specimen were prepared. The D-side test piece has a cylindrical shape with an outer diameter (diameter) of 40 mm, an inner diameter (diameter) of 20 mm, a width of 12 mm, and an axial secondary curvature radius of 60 mm. The axial surface roughness of the D-side test piece was polished to have an arithmetic average roughness Ra of about 0.65 μm and a root mean square slope RΔq of about 0.27. On the other hand, the F-side test piece has a cylindrical shape having an outer diameter (diameter) of 40 mm, an inner diameter (diameter) of 20 mm, a width of 12 mm, and no axial secondary curvature radius. The surface roughness in the axial direction of the rolling part of the F-side test piece was superfinished so that the arithmetic average roughness Ra was about 0.02 μm and the root mean square slope RΔq was about 0.013. As shown in Table 1, the rolling test conditions were such that peeling (small peeling) was likely to occur at the rolling part of the F-side test piece.

  The D side test piece was fixed to the drive side (D side) rotation shaft so as to be rotatable about the axis, and the F side test piece was fixed to the driven side (D side) rotation shaft so as to be rotatable about the axis. In this state, the outer peripheral surfaces of the D-side test piece and the F-side test piece were brought into contact with each other. The D-side rotating shaft was rotated by a motor while applying a load to the F-side test piece in a direction to bring the F-side test piece closer to the D-side test piece. As a result, the F-side test piece and the D-side test piece were rotated in opposite directions. At this time, the lubricating oil was supplied to the outer peripheral surfaces of the D-side test piece and the F-side test piece from the felt pad for oil supply impregnated with the lubricating oil. An additive-free poly-α-olefin oil (equivalent to VG5) was used as this lubricating oil. The test time was 5 minutes. As test conditions, the rotation speed of the D-side rotation shaft was 2000 rpm. Furthermore, the load applied to the F-side test piece was 230 kgf.

  Next, Table 5 shows the conditions for creating the materials of nine types of test pieces of Examples 2 to 10.

  The steel materials of Examples 2 to 10 were all JIS standard SUJ2. The quenching method on the D side and the F side was cooled in 80 ° C. oil after soaking at 850 ° C. for 80 minutes in all of Examples 2 to 10. The D side tempering temperature was 250 ° C. in Examples 2 to 4, 230 ° C. in Examples 5 to 7, and 200 ° C. in Examples 8 to 10. The D side tempering time was 7.5 hours in Examples 2 to 7 and 3 hours in Examples 8 to 10. The F-side tempering temperature was 250 ° C. in Examples 2, 5, and 8, 230 ° C. in Examples 3, 6, and 9, and 200 ° C. in Examples 4, 7, and 10. The F-side tempering time was 7.5 hours in Examples 2, 3, 5, 6, 8, and 9, and 3 hours in Examples 4, 7, and 10. According to these tempering conditions, the respective width face Rockwell hardnesses of the D-side and F-side cylinders were controlled to three types of hardness of about 59.5 HRC, 60.5 HRC, and 61.5 HRC. Examples 2 to 10 all have different combinations of hardness on the D side and F side.

  The microscope picture of the rolling part of the F side test piece of Examples 2-10 after a test is shown in FIGS. Table 6 shows the area ratio of the crack generation part in the micrograph of the rolling part of the F-side test piece after the test of each example. For the calculation of the area ratio, the photographs in FIGS. 5 to 9 were converted into monochrome images using commercially available image processing software for all the examples, the image was subjected to binarization processing, and only the crack generation portion was painted, and the area The rate was calculated. 5 to 9 and Table 6, D-side hardness is relatively softer than F-side hardness, that is, Examples 3, 4, and 7 in which the hardness difference was a positive value compared with the other examples. Clearly, the number of cracks (area), which is the initial stage of peeling, was small. In Examples 4 and 7 having an F-side hardness of 61.5 HRC, the number of cracks (area) was smaller when compared with Example 3 having a lower F-side hardness. From these results, it is possible to suppress the progress of fatigue on the surface of the F-side specimen and to suppress peeling by making the D-side specimen having a large surface roughness of the rolling part relatively harder than the F-side specimen. I understood. Moreover, in addition to the above-mentioned hardness difference, it was found that the effect of suppressing fatigue progression is further promoted by setting the hardness of the F-side test piece to 61.5 HRC or more.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing, 11 outer ring, 11A outer ring raceway surface, 11B, 12B coating | coated, 12 inner ring, 12A inner ring raceway surface, 13 balls, 13A ball rolling surface, 14 cage.

Claims (8)

A first rolling part made of JIS standard SUJ2,
A second rolling part in contact with the first rolling part and made of JIS standard SUJ2,
Each of the first and second rolling parts is tempered after being quenched,
The arithmetic mean roughness of the surface of the rolling part of the first rolling component is greater than the arithmetic mean roughness of the surface of the rolling part of the second rolling component,
The Rockwell hardness of the surface of the rolling part of the first rolling part is lower than the Rockwell hardness of the surface of the rolling part of the second rolling part,
The surface of the rolling part of the first rolling component is subjected to a chemical conversion treatment after the tempering treatment, and the surface of the rolling part of the first rolling component is subjected to the chemical conversion treatment with an iron oxide and A rolling device in which a film containing at least one of compounds is formed.   The rolling device according to claim 1, wherein the coating contains triiron tetroxide.   The Rockwell hardness of the surface of the rolling part of the first rolling component is 0.5 or more lower than the Rockwell hardness of the surface of the rolling part of the second rolling component. The rolling device described.   The Rockwell hardness of the surface of the rolling part of the second rolling part is 61.5 HRC or more, and the Rockwell hardness of the surface of the rolling part of the first rolling part is 60.0 HRC or more. The rolling device according to any one of claims 1 to 3. The surface of the rolling part of the second rolling part is superfinished,
The rolling device according to any one of claims 1 to 4, wherein the surface of the rolling portion of the first rolling component is not superfinished. It is a rolling bearing comprised by the rolling device of any one of Claims 1-5,
An outer ring having an outer ring raceway surface on the inner circumferential surface;
An inner ring having an inner ring raceway surface on the outer peripheral surface;
A plurality of rolling elements that roll between the outer ring raceway surface and the inner ring raceway surface;
A rolling bearing in which the outer ring and the inner ring are made of the first rolling part, and the rolling element is made of the second rolling part. It is a rolling bearing comprised by the rolling device of any one of Claims 1-5,
An outer ring having an outer ring raceway surface on the inner circumferential surface;
An inner ring having an inner ring raceway surface on the outer peripheral surface;
A plurality of rolling elements that roll between the outer ring raceway surface and the inner ring raceway surface;
A rolling bearing in which the outer ring and the inner ring are made of the second rolling part, and the rolling element is made of the first rolling part.   The rolling bearing according to claim 6 or 7, wherein an oil film parameter in lubrication between each of the outer ring and the inner ring and the rolling element is 1.2 or less.