JP2021089067A - Thrust roller bearing - Google Patents

Abstract

To provide a thrust roller bearing improved in resistance to foreign matter.SOLUTION: A thrust roller bearing 1 includes a plurality of rollers 2 radially arranged, and a pair of annular raceway discs 3 and 4 having raceway surfaces 3a and 4a on which the plurality of rollers 2 are rolled, and disposed in a manner that the raceway surfaces 3a and 4a are opposed to each other. The rollers 2 are composed of high carbon chromium bearing steel; include 1.1-1.6 mass% of carbon and 0.1-0.6 mass% of nitrogen within a range of 0.1 mm from a surface; and have surface compression residual stress less than -900 MPa, surface roughness of 0.01-0.10 by Rvk and 0.01-0.08 by Rk, and Vickers hardness of the surface of 860-980. At least one of the raceway disks 3 and 4 is composed of carbon steel, and the surface roughness of the raceway surfaces 3a and 4a is 0.05-0.20 by Rvk, and 0.08-0.15 by Rk.SELECTED DRAWING: Figure 1

Description

The present invention relates to thrust roller bearings.

Thrust roller bearings are known to include a plurality of rollers arranged radially and a pair of annular track discs having a raceway surface on which the plurality of rollers roll (see, for example, Patent Document 1). Thrust roller bearings are inserted between a non-rotating member and a rotating member, for example, in a vehicle transmission, and are used to smooth the rotation of the rotating member while receiving a thrust force in the direction of the central axis of the bearing.

Japanese Unexamined Patent Publication No. 2003-239891

In thrust roller bearings, when foreign matter is contained in the lubricating oil, wear may increase due to the influence of the foreign matter. In recent years, the amount of lubricating oil supplied to a vehicle transmission or the like has been decreasing, and the amount of foreign matter contained in the lubricating oil has also tended to increase due to the influence of wear powder generated in other members such as a housing. Therefore, even when the amount of foreign matter contained in the lubricating oil is large, a thrust roller bearing having high foreign matter resistance capable of suppressing wear is desired.

Therefore, an object of the present invention is to provide a thrust roller bearing having improved foreign matter resistance.

The present invention has a plurality of rollers arranged radially and a raceway surface on which the plurality of rollers roll, and an annular shape arranged so that the raceway surfaces face each other, for the purpose of solving the above problems. The roller is made of high carbon chrome bearing steel, contains 1.1 mass% or more and 1.6 mass% or less of carbon within a range of 0.1 mm from the surface, and contains 0 nitrogen. It contains 1 mass% or more and 0.6 mass% or less, the surface compressive residual stress is less than -900 MPa, the surface roughness is 0.01 or more and 0.10 or less in Rvk, and 0.01 or more and 0.08 or less in Rk. The Vickers hardness of the surface is 860 or more and 980 or less, at least one of the track discs is made of carbon steel, and the surface roughness of the track surface is 0.05 or more and 0.20 or less in Rvk. , Provide a thrust roller bearing having an Rk of 0.08 or more and 0.15 or less.

According to the present invention, foreign matter resistance can be improved.

It is sectional drawing which shows the cross section including the bearing central axis of the thrust roller bearing which concerns on one Embodiment of this invention. (A) and (b) are diagrams for explaining wear due to foreign matter contained in the lubricating oil. It is a figure explaining Rvk and Rk which are parameters representing surface roughness. It is a figure which shows various parameters of the roller in an Example and a conventional example of this invention, (a) is Rvk, (b) is Rk, (c) is hardness, (d) is a figure which shows surface residual stress. .. It is a figure which shows the surface roughness of the track surface of the track disk in the Example and the prior art of this invention, (a) is a figure which shows Rvk, (b) is a figure which shows Rk. It is a figure which shows the wear mass in an Example of this invention and a conventional example.

[Embodiment]
Embodiments of the present invention will be described with reference to FIGS. 1 to 6. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect.

FIG. 1 is a cross-sectional view showing a cross section including a bearing central axis of the thrust roller bearing according to the present embodiment. In the thrust roller bearing 1, a plurality of rollers 2 arranged radially, an annular first track board 3 having a first raceway surface 3a on which the plurality of rollers 2 roll, and a plurality of rollers 2 roll. It is provided with an annular second track board 4 having a second track surface 4a. The first and second racetracks 3 and 4 are arranged so that the first and second raceway surfaces 3a and 4a face each other in the axial direction of the bearing central axis O. In this thrust roller bearing, the first racetrack 3 and the second racetrack 4 rotate relative to each other around the bearing center axis O.

The thrust roller bearing 1 is inserted between a rotating member and a non-rotating member in, for example, a vehicle transmission or an industrial machine, and the rotating member rotates while receiving an axial thrust force due to the rolling of a plurality of rollers 2. To facilitate.

The plurality of rollers 2 are rotatably held by the annular cage 5 shown by the broken line in FIG. 1, and rotate as the first track board 3 and the second track board 4 rotate relative to each other. While being held by the cage 5, it revolves around the bearing central axis O. The first track board 3 has an annular and flat plate-shaped track portion 31 perpendicular to the axial direction and one side in the axial direction from the radial inner end of the track portion 31 (right side in FIG. 1, second). A short cylindrical brim 32 extending to the track board 4 side) is integrally provided. The surface on one side of the track portion 31 in the axial direction is the first track surface 3a. The second track board 4 has an annular and flat plate-shaped track portion 41 perpendicular to the axial direction. The surface of the track portion 41 on the other side in the axial direction (left side in FIG. 1, side of the first track board 3) is the second track surface 4a. In the present embodiment, the first track board 3 is provided on the rotating member, and the second track board 4 is provided on the non-rotating member.

The shapes of the first and second track boards 3 and 4 are not limited to those shown in the figure. For example, the brim 32 in the first track board 3 may be omitted, or the second track board 4 has a short cylindrical brim extending from the radial outer end of the track portion 41 to the other side in the axial direction. May have.

As the roller 2, it is preferable to use one made of high carbon chrome bearing steel having high wear resistance. In the present embodiment, the roller 2 is used in which the high carbon chrome bearing steel is subjected to a special heat treatment to further improve the surface hardness. More specifically, the roller 2 contains 1.1 mass% or more and 1.6 mass% or less of carbon and 0.1 mass% or more and 0.6 mass% or less of nitrogen in a range of 0.1 mm from the surface. As the first and second track discs 3 and 4, those made of carbon steel, which is relatively hard and has high wear resistance, were used.

As shown in FIG. 2A, in the thrust roller bearing 1, lubricating oil is supplied from the bearing central axis O side. When the lubricating oil contains a large amount of foreign matter 6 such as wear debris, as shown in FIG. 2B, the foreign matter 6 is caught in the fine irregularities on the surfaces of the rollers 2 and the raceway surfaces 3a and 4a. The flow of the lubricating oil makes it difficult for the foreign matter 6 to be discharged, and the surface of the rollers 2 and the raceway surfaces 3a and 4a is likely to be worn due to the influence of the foreign matter caught in the foreign matter 6. Therefore, in the present embodiment, by smoothing the surfaces of the rollers 2 and the raceway surfaces 3a and 4a, the discharge of the foreign matter 6 due to the flow of the lubricating oil is promoted, and the wear due to the influence of the foreign matter 6 is suppressed. ..

Specifically, in the present embodiment, the surface roughness of the roller 2 is 0.01 or more and 0.10 or less in Rvk and 0.01 or more and 0.08 or less in Rk. Further, in the present embodiment, the surface roughness of the raceway surfaces 3a and 4a of the first and second track discs 3 and 4 is 0.05 or more and 0.20 or less in Rvk and 0.08 or more in Rk. It was set to 0.15 or less. It is desirable that the surface roughness of both the raceway surfaces 3a and 4a of the first and second track discs 3 and 4 is within the above numerical range as in the present embodiment, but the first and second track discs 3 and 4 have surface roughness. Even if the surface roughness of at least one of the raceway surfaces 3a and 4a of the racetracks 3 and 4 is within the above numerical range, the effect of reducing the wear due to the influence of the foreign matter 6 can be obtained as compared with the conventional case. The surface roughness of the rollers 2 and the raceway surfaces 3a and 4a can be appropriately adjusted depending on the polishing conditions in the polishing process such as barrel polishing.

Here, Rvk and Rk representing the surface roughness are lubricity evaluation parameters (load curve parameters) of the plateau structure surface. As shown in FIG. 3, the region between the height positions where the equivalent straight line 72, which is the gentlest inclination of the central portion in the load curve 71 of the surface unevenness, intersects the load length ratios of 0% and 100% is the core portion 73. To do. The height (difference between the upper and lower levels) of the core portion 73 is Rk. Rvk represents the depth of the protruding valley portion 74.

Further, in the present embodiment, the rollers 2 are subjected to shot peening to increase the hardness of the surface of the rollers 2 to further improve the wear resistance. Specifically, the Vickers hardness of the surface of the roller 2 was set to 860 or more and 980 or less. Further, the surface compressive residual stress of the roller 2 was made smaller than −900 MPa (absolute value was made larger than 900 MPa). The surface hardness and compressive residual stress of the roller 2 can be appropriately adjusted depending on the shot peening conditions and the treatment conditions in the heat treatment step. Further, when the roller 2 is manufactured, it is preferable to perform shot peening after the heat treatment step and then to perform a polishing step. The Vickers hardness of the surfaces of the first and second track boards 3 and 4 was 780 or more and 850 or less.

(Evaluation of foreign matter resistance)
The thrust roller bearing 1 according to the present embodiment was prototyped and used as an example, and the foreign matter resistance was evaluated. The thrust roller bearing 1 according to the embodiment was manufactured as follows. The bar of JISSUJ2 was cut and used as the work of the example. The atmosphere was set to a carbon potential of 1.2 to 1.6 and an ammonia concentration of 0.1 to 0.5 vol%, and the work of the roller was held at a temperature of 820 to 870 ° C. for 1 hour for carburizing and nitriding. It was immersed in the oil of the above, rapidly cooled and quenched. After quenching, tempering was performed at 200 ° C. for 1 hour, then shot peening was performed, polishing was performed, and barrel polishing was performed for 2 hours. In the range of 0.1 mm from the surface of the roller 2 of the example, carbon is 1.1 mass% to 1.6 mass%, and nitrogen is 0.1 mass% to 0.1 0.6 mass%. The conditions for shot peening are as follows.
・ Shot particle size: 100 μm or less ・ Shot grain material: Iron ・ Shot pressure: 0.5 MPa
The steel plate of SAE1075 was punched in an annular shape and forged to produce a work of the first track board of the example and a work of the second track board of the example. Hold the first track board work of Example and the second track board work of Example at a temperature of 760 to 830 ° C. for 0.5 hours, immerse in oil at 80 ° C., quench and quench. did. After quenching, it was tempered at 200 ° C. for 1 hour, then polished and barrel-polished for 5 hours to obtain a first track board 3 of an example and a second track board 4 of an example. The steel plate of SPCD was punched out so as to remove the annular and pocket portion, and used as the cage 5. A thrust roller bearing 1 is manufactured by combining the roller 2 of the embodiment, the first track board 3 of the embodiment, the second track board 4 of the embodiment, and the cage 5, and this is used as the thrust roller bearing 1 of the embodiment. And said.

The foreign matter resistance was evaluated for 20 hours while supplying lubricating oil containing 0.06 mass% of foreign matter 6 composed _{of SiO 2} having a particle size of about 50 μm from the bearing central shaft O side with an axial load of 9 kN and a rotation speed of 2000 rpm. The test was carried out by measuring the wear mass obtained by subtracting the post-test mass from the initial mass. The number of tests was three.

Further, for comparison with the examples, the thrust rollers of the conventional example in which the rollers 2 made of a hardened tempered material of high carbon chrome bearing steel are used and the surface roughness of the rollers 2 and the raceway surfaces 3a and 4a are not particularly adjusted are used. Bearings were prepared and the foreign matter resistance was evaluated in the same manner as in the examples.

The thrust rolling bearing 1 according to the conventional example was manufactured as follows. The bar of JISSUJ2 was cut and used as the work of the conventional example. The work of the conventional example was held at a temperature of 820 to 850 ° C. for 0.5 hours, and then immersed in oil at 80 ° C. for rapid cooling and quenching. After quenching, tempering was performed at 200 ° C. for 1 hour, polishing was performed, and barrel polishing was performed for 1 hour to obtain the value of 2 in the conventional example. The steel plate of SAE1075 was punched in an annular shape and forged to produce a work of the first track board of the conventional example and a work of the second track board of the conventional example. The work of the first track board of the conventional example and the work of the second track board of the conventional example are held at a temperature of 760 to 830 ° C. for 0.5 hours, immersed in oil at 80 ° C., rapidly cooled and quenched. did. After quenching, it was tempered at 200 ° C. for 1 hour, then polished and barrel-polished for 1 hour to obtain a first track board 3 of the conventional example and a second track board 4 of the conventional example. The steel plate of SPCD was punched out so as to remove the annular and pocket portion, and used as the cage 5. A thrust roller bearing 1 is manufactured by combining a conventional roller 2, a conventional first track board 3, a conventional second track board 4, and a cage 5, and this is used as a conventional thrust roller bearing 1. And said.

The Rvk of the roller 2 surface in the examples and the conventional examples is shown in FIG. 4 (a), the Rk is shown in FIG. 4 (b), the Vickers hardness of the roller 2 surface is shown in FIG. 4 (c), and the surface residual stress of the roller 2 is shown. Each is shown in FIG. 4 (d). Further, Rvk on the surfaces of the track surfaces 3a and 4a of the track boards 3 and 4 in the examples and the conventional examples is shown in FIG. 5 (a), and Rk is shown in FIG. 5 (b), respectively.

As shown in FIG. 4A, the Rvk on the surface of the roller 2 is larger than 0.1 in the conventional example, but is 0.01 or more and 0.10 or less in the example. Further, as shown in FIG. 4B, the Rk on the surface of the roller 2 is larger than 0.1 in the conventional example, but is 0.01 or more and 0.08 or less in the example. As described above, in the examples according to the present invention, both Rvk and Rk of the surface of the roller 2 are smaller and the surface roughness is smaller than that of the conventional example.

Further, as shown in FIG. 4C, the Vickers hardness of the surface of the roller 2 is 830 or less in the conventional example, whereas it is 860 or more and 980 or less in the embodiment. Further, as shown in FIG. 4D, the surface compressive residual stress of the roller 2 is −900 MPa in the conventional example, whereas it is smaller than −900 MPa (absolute value is larger than 900 MPa) in the embodiment. , -1000 MPa or less. That is, in the embodiment according to the present invention, the surface of the roller 2 is harder and the absolute value of the surface compressive residual stress is larger than that of the conventional example.

Further, as shown in FIG. 5A, the Rvk on the surfaces of the raceway surfaces 3a and 4a is 0.2 or more in the conventional example, whereas it is 0.05 or more and 0.20 or less in the embodiment. is there. Further, as shown in FIG. 5B, the Rk on the surfaces of the raceway surfaces 3a and 4a is 0.2 or more in the conventional example, whereas it is 0.08 or more and 0.15 or less in the embodiment. is there. As described above, in the examples according to the present invention, both Rvk and Rk on the surfaces of the raceway surfaces 3a and 4a are smaller and the surface roughness is smaller than in the conventional examples.

The measurement results of the wear mass of the examples and the conventional examples are shown in FIG. The measurement result of FIG. 6 represents the average value of three tests. As shown in FIG. 6, in the embodiment according to the present invention, the wear mass is reduced by about 40% as compared with the conventional example, and it can be seen that the foreign matter resistance is significantly improved as compared with the conventional example. ..

(Actions and effects of embodiments)
As described above, in the thrust roller bearing 1 according to the present embodiment, the roller 2 is made of high carbon chromium bearing steel, the surface compressive residual stress is smaller than −900 MPa, and the surface roughness thereof is 0. It is 01 or more and 0.10 or less, Rk is 0.01 or more and 0.08 or less, and the Vickers hardness of the surface is 860 or more and 980 or less. Further, in the thrust roller bearing 1 according to the present embodiment, at least one of the racetracks 3 and 4 is made of carbon steel, and the surface roughness of the raceway surfaces 3a and 4a is 0.05 or more and 0.20 or less in Rvk. Moreover, the Rk is 0.08 or more and 0.15 or less.

By reducing the surface roughness of the rollers 2 and the raceway surfaces 3a and 4a, the foreign matter 6 is easily discharged by the flow of the lubricating oil, the wear due to the influence of the foreign matter 6 can be suppressed, and the foreign matter resistance can be improved. Further, by increasing the hardness of the surface of the roller 2 by shot peening, it becomes possible to further increase the wear resistance of the roller 2 and further improve the foreign matter resistance.

(Additional note)
Although the present invention has been described above based on the embodiments, these embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

In addition, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, the case where the rollers 2 are arranged in one row in the circumferential direction has been described, but the arrangement of the rollers 2 is not limited to this, and for example, the rollers 2 may be arranged in two or more rows. ..

1 ... Thrust roller bearing 2 ... Roller 3 ... 1st raceway 3a ... 1st raceway 31 ... Raceway 32 ... Brim 4 ... Second raceway 4a ... Second raceway 41 ... Raceway 5 ... Holding Vessel 6 ... Foreign matter 71 ... Load curve 72 ... Equivalent straight line 73 ... Core part 74 ... Protruding valley part O ... Bearing central axis

Claims (2)

With multiple rollers arranged in a radial pattern
It has a raceway surface on which the plurality of rollers roll, and includes a pair of annular racetracks arranged so that the raceway surfaces face each other.
At the time mentioned above
Made of high carbon chrome bearing steel
Within 0.1 mm from the surface, carbon is contained in an amount of 1.1 mass% or more and 1.6 mass% or less, and nitrogen is contained in an amount of 0.1 mass% or more and 0.6 mass% or less.
Surface compressive residual stress is less than -900 MPa,
The surface roughness is 0.01 or more and 0.10 or less in Rvk, and 0.01 or more and 0.08 or less in Rk.
The Vickers hardness of the surface is 860 or more and 980 or less,
At least one of the track boards
Made of carbon steel
The surface roughness of the raceway surface is 0.05 or more and 0.20 or less in Rvk and 0.08 or more and 0.15 or less in Rk.
Thrust roller bearing. Both of the pair of track boards
Made of carbon steel
The surface roughness of the raceway surface is 0.05 or more and 0.20 or less in Rvk and 0.08 or more and 0.15 or less in Rk.
The thrust roller bearing according to claim 1.

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