Rolling/sliding part, rolling bearing, cam follower, and method of modificating surface of rolling/sliding part

Abstract

The invention provides a cam follower having an outer ring which is used in a state where the cam follower comes into sliding contact or rolling contact with a mating part. The outer ring is configured such that the hardness of a surface layer portion existing between the surface and at least 3 μm below the surface is Hv 780 to 900, and the hardness of an internal surface portion existing at a depth of 10 μm or more from the surface is lower than the hardness of the surface layer portion and less than Hv 780. Such hardness can be obtained by performing soft shot blasting or flow barrel processing on a surface layer portion of a base material to be the outer ring.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a rolling / sliding part (hereinafter referred to as rolling / sliding part) which is used in a state where the rolling / sliding part comes into sliding contact or rolling contact with a mating part, a rolling bearing, a cam follower, and the like. [0002] In a bearing ring and bearing elements which constitute a bearing or an outer ring which constitutes a cam follower, their surfaces are often peeled (also referred to as “peeling damage.” In order to prevent this peeling, a method of increasing the hardness of surface layer portions of those parts or a method of applying residual compressive stress to the surface layer portions is already known (for example, Patent Documents 1 to 5). [0003] Patent Document 1; Japanese Unexamined Patent Application Publication No. 5-288257 [0004] Patent Document 2: Japanese Unexamined Patent Application Publication No. 5-288221 [0005] Patent Document 3: Japanese Unexamined Patent Applica...

AI Technical Summary

Benefits of technology

[0009] The present invention has been made to cope with the above problems. Therefore, an object of the invention is to obtain a low-cost rolling / sliding part which is hardly peeled and has little probability that causes pitching in a mating member. Further, another object of the invention is to obtain a rolling bearing and a cam follower with employing such a rolling / sliding part.

[0016] According to the rolling / sliding part of the present invention, it is possible to prevent most of peeling that is surface peeling. Moreover, since the rolling / sliding part of the present invention only needs an improvement in the hardness of only a surface layer portion existing between a surface thereof and a depth of 3 μm (a depth of 5 μm at a maximum) from the surface, occurrence of cracks in the rolling / sliding part itself or occurrence of premature pitching to a contacting mating member can be prevented only with processing by soft shot-blasting or flow barrel processing. Moreover, processing for roughness removal such as superfinishing becomes unnecessary, which contributes to a low cost.

[0017] By the surface modificating method of a rolling / sliding part of the present invention, measurement of the hardness of a modificated surface becomes easy, and the processing efficiency of the surface modificating when a rolling / sliding part is manufactured can be improved.

Problems solved by technology

Since this hard processing makes the surface of the part rough which becomes a primary factor which causes premature pitching in a contacting mating member, superfinishing for roughness fining is required after the surface modification.

Further, there is also a possibility that the hard shot peening generates minute cracks in the surface layer portion.

This also requires superfinishing for roughness fining after the surface modification, which results in cost-up.

Images