Rolling bearing

Abstract

An inexpensive rolling bearing is proposed which can be used stably for a long time even for applications where the lubricating conditions are severe or bending stresses act. Inner (5) and outer (6) rings of rolling bearings mounted in a rocker arm (4) of an automobile are made of high-carbon chrome bearing steel. They are subjected to heat treatment in which after carbonitriding, high-temperature tempering is carried out. Then they are induction hardened to impart resistance to material quality change and a compressive stress of not less than 200 MPa to the surface layer, thereby markedly improving the rolling contact fatigue life and the tension-compression fatigue strength while keeping the material cost as before. Thus, this bearing can be used stably for a long time even though it is a full compliment type, lubricating conditions tend to worsen and the outer ring is repeatedly subjected to bending stress from the cam (3).

Description

technical field [0001] The present invention relates to a rolling bearing used in a bearing for a rocker arm of an automobile, etc., which is used in a condition requiring severe lubricating conditions or a condition in which bending stress acts. Background technique [0002] In recent years, in machinery such as automobiles, in order to reduce fuel costs and make maintenance-free, reduce the viscosity of the lubricating oil injected into the rolling bearing in the machine or use it for a long time without changing the lubricating oil. There are more and more occasions where bearings are operated under lubricated conditions. In bearings used under such harsh lubrication conditions, an appropriate oil film is not formed between the races and rolling elements, and surface heat or metal contact occurs, and the required service life may not be met. In particular, in full compliment roller bearings, since the amount of lubricating oil supplied between the raceway and the rollers...

AI Technical Summary

Problems solved by technology

[0006] However, since carbonitriding is a technique that diffuses from the material surface, it takes a long time to obtain the necessary carbonitriding depth

Therefore, there is a problem that the surface structure of the carbonitriding treated material becomes thicker, the entire grain size becomes larger, and the fatigue strength decreases.

[0007] In addition, for bearings for rocker arms, a method of improving wear resistance (shafts subjected to induction hardening after carburizing or carbonitriding treatment) has been proposed (refer to Patent Document 1). Change the carbon concentration distribution, control the carbon concentration and hardness of the shaft surface formed integrally with the inner ring, and the hardness of the interior to prevent wear of the outer ring due to contact with the advancing cam, but have not focused on the rolling life and fracture strength. technology

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