JPH0681848A - Rolling bearing - Google Patents

Abstract

PURPOSE:To provide a hybrid rolling bearing suitable for high speed rotation by forming a rolling body made of ceramic so as to improve a separating life and a hoop stress resistance characteristic of the rolling bearing whose bearing ring is made of steel. CONSTITUTION:In a hybrid rolling bearing, it is constituted by applying nitriding treatment after applying carburization quenching to at least a raceway surface of a steel-made race.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing, and more particularly to a so-called hybrid rolling bearing in which rolling elements are made of ceramics and races are made of steel.

[0002]

2. Description of the Related Art The hybrid rolling bearing described above is conventionally used under a high-speed use condition such as a machine tool spindle and a small temperature rise.

[0003]

However, a large tensile stress acts on the bearing ring (for example, the inner ring) of the rolling bearing that rotates at a high speed due to the expansion due to the centrifugal force. General S
For UJ2 material, the limit of hoop stress is 15kg for safety.
It is said to be f / mm ² or less, and when the dn product (d: bearing inner diameter, n: rotational speed rpm) is 2.5 million or more, the above limit is exceeded and burst occurs when minute surface damage occurs. There is a risk.

On the other hand, considering the effect of heat generation due to the rolling contact of the hybrid rolling bearing, the hardness of the ceramic rolling elements hardly decreases due to the heat generation, while the hardness of the steel bearing ring decreases at the high temperature due to the heat generation. Come here. Therefore, the difference in hardness between the ceramic rolling element and the steel bearing ring is further increased, and as a result, the life of the steel bearing ring may be shortened.

Therefore, an object of the present invention is to improve the hoop stress resistance and to further reduce the decrease in high temperature hardness during rolling, thereby extending the service life of the hybrid rolling bearing.

[0006]

In order to solve the above-mentioned problems, the present invention relates to a rolling bearing in which the rolling element is made of ceramics, and at least the rotation-side bearing ring is made of steel. At least the raceway surface of the bearing ring is carburized and quenched, and then nitrided.

[0007]

[Examples] Table 1 shows the results of point contact life tests of a ceramic rolling element and a cylindrical test piece obtained by carburizing carburized steel as a bearing ring and further nitriding the same, together with comparative examples. Show.

[0008]

[Table 1]

Test conditions Ceramic ball: φ7 / 16 inch Various materials Cylindrical test piece: (Diameter) 25 mm × (Length) 22 mm Hertz contact surface pressure: Pmax667 kgf / mm ² Number of times of loading (cylindrical test piece): 22195 c. p. m Lubrication: Turbine oil As can be seen from the above test results, in the case of the example, a peeling life of 10 times that of Comparative Example 1 and about 6 times that of Comparative Example 2 can be obtained. In addition, compared to the hoop resistance of SUJ2 inner ring,
The inner ring of the carburized and hardened product is excellent, approximately 25 kgf
/ Mm ² can be used.

[0010]

As described above, according to the present invention, in the hybrid rolling bearing, at least the raceway surface of the steel rotating-side bearing ring is carburized and quenched, and then subjected to the nitriding treatment, so that the peeling life is excellent and the durability is improved. It is possible to provide a rolling bearing having high hoop stress, that is, a rolling bearing suitable for high speed rotation.

Claims (1)

[Claims] 1. A rolling bearing in which the rolling elements are made of ceramics, and at least the rotating side bearing ring is made of steel, and at least the raceway surface of the steel bearing ring is carburized and quenched, and then subjected to nitriding treatment. Rolling bearing characterized by having been applied.