JPH02285024A - Manufacturing roller bearing member from solid-hardened roller bearing steel - Google Patents

Abstract

PURPOSE: To produce a rolling bearing having a long service life by a slight time and energy by heating a stock to a primary austenitizing temp., deforming it, executing cooling, thereafter roughly finishing it in the state of a layered pearlitic stock and thereafter heating it to a secondary austenitizing temp.

CONSTITUTION: A steel stock is heated to a primary austenitizing temp., is deformed by forging or the like and is successively cooled to an ambient temp. in a gas such as nitrogen to form a fine layered pearlitic stock. In this state, it is machined and roughly finished, is immediately heated to a secondary austenitizing temp. lower than the primary austenitizing temp. and is held to the above temp. for a time sufficient for forming finely dispersed homogeneous austenite. Then, it is quenched in oil, salt or water to attain hardness of 64 by a Rockwell C scale. Finally, it is subjected to finish working and is finished into a rolling bearing member.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing rolling bearing members from through-hardened rolling bearing steel.

A known method of this type is West German Published Patent No. 202.
In No. 3101 (Japanese Patent Publication No. 50-31529), after the material is cooled from the forging temperature, it is annealed at 650 to 815°C, and then cut. However, the annealing process is time-consuming and energy-consuming, and large cementite particles are generated in the body during this annealing, so even after austenitization, quenching, and tempering, the quenched body remains in the quenched body. Coarse precipitated carbides are present. but,
In order to achieve an optimal fatigue strength of a rolling bearing component with a suitably long life, the precipitated carbides in the hardened matrix of the rolling bearing component must be as fine as possible.

The object of the invention is to provide a manufacturing method of the aforementioned type which can be carried out with little time and energy consumption and which provides a hardened green body which significantly increases the service life of rolling bearings.

Annealing is not necessary in the method of manufacturing a rolling bearing member according to the present invention. Therefore, the heat treatment of the material can be carried out economically in a short time and with little thermal energy consumption.

After cooling the material in a gas, e.g. air or nitrogen,
The relatively hardened layered pearlite material is processed on a lathe.
The method according to the invention, which is rough-machined with particularly durable cutting edges made of ceramic material or hard alloys, has the great advantage that it results in a homogeneous hardened green body with very fine precipitated carbides in the rolling bearing component. ing.

Rolling bearing components manufactured by this method have a significantly longer lifespan against internal wear and fatigue in the rolling raceway, even when the rolling raceway is lubricated with a lubricating oil that absorbs fine dust or dirt particles during operation. have.

Preferred implementations of the method according to the invention are specified in the dependent claims.

By means of the second aspect of the present invention, it is possible to remove scale from the surface of the material that is generated during hot rolling, forging, and/or hot pressing.

By means of the measures according to claim 3, a particularly homogeneous layered pearlite is produced in the material by cooling the material in gas.

By utilizing the measures according to claim 4, rough machining is carried out with extremely durable cutting edges which can consist of hard ceramic oxides, carbides and/or nitrogenous materials.

Claims 5 to 8 describe further preferred means.

The method of manufacturing a rolling bearing member from a through-hardened rolling bearing steel according to the present invention is carried out by treating the material as follows. That is, it is heated to a first austenitizing temperature of about 1150° C. to dissolve all carbides in the body, then deformed at this temperature, e.g. by forging, and then heated in a gas, e.g. in moving air or moving nitrogen. Upon cooling to ambient temperature, a fine layered pearlite matrix forms. Cooling for this is done at a rate of about 40°C/min from 900°C to 6°C.
It is best to carry out the process at temperatures up to 50°C.

In this pearlite base state, rough cutting is performed using, for example, a ceramic-coated rotary tool.

Next, about 8
heating to a second austenitizing temperature of 40°C;
Hold at said temperature for a sufficient period of time, e.g. 20 minutes, to form a homogeneous austenite in which the carbides are homogeneously dispersed and then in oil, salt or water to achieve a hardness of at least 64 on the Rockwell C scale. The material is then hardened and finally finished as a rolling bearing member by polishing and/or honing. After the material is hardened, an additional step of tempering the material may be inserted before finishing.
A holding period of ~2 hours is optimal, thereby achieving a hardness of 58-64 on the Rockwell C scale (see figure).

Furthermore, sand blasting or the like can be applied between cooling the material in the gas and rough cutting to remove scale from the surface of the material, which may occur in some cases, before machining the material.

Rolling bearing steels having the following analysis values (%) are suitable for use in this method.

C0.90-1, 10 Si 0.15-0, 35M n
0, 25~0, 40Cr
1-30 to 1.65 S 0.025 or less P 0.030 or less Residual impurities originating from iron and smelting, rolling bearing members manufactured from the above types of steel by the method based on the present invention have no This long fatigue life is achieved even in the presence of fine foreign particles, such as dust, in the lubricating oil.

[Brief explanation of drawings]

The figure is a graph showing the relationship between time and temperature for each stage of the method according to the invention. 506C

Claims (8)

[Claims] (1) The material is heated to a first austenitizing temperature of about 1150°C, deformed at this temperature, and then cooled in gas to ambient temperature to produce a layered pearlite matrix, which is rough-cut. , heated to a second austenitizing temperature lower than the first austenitizing temperature, held at said temperature to form homogeneous austenite containing finely dispersed carbides, and quenched in oil, salt or water. A method for manufacturing a rolling bearing member from a through-hardened rolling bearing steel comprising the steps of: producing a hardness of at least 64 on the Rockwell C scale and finishing it as a rolling bearing member; A method characterized in that the layered pearlite matrix is then rough-finished and immediately thereafter heated to a second austenitizing temperature. (2) The method according to claim 1, characterized in that the material is subjected to sand blasting or the like after being cooled in a gas. (3) A method according to claim 1 or 2, characterized in that the material is cooled in a gas at a temperature of 900 to 650°C at a rate of about 40°C/min. (4) The method according to at least one of claims 1 to 4, characterized in that the cutting process of the material is performed with a cutting blade made of a ceramic material. (5) A method according to at least one of claims 1 to 4, characterized in that heating to the second austenitizing temperature is maintained at a level of about 840° C. for about 20 minutes. (6) 1 at 160 to 240℃ after quenching the material.
The method according to any one of claims 1 to 5, characterized in that the tempering is carried out by holding for 2 to 2 hours. (7) The method according to any one of claims 1 to 6, characterized in that finishing processing of the material is performed by polishing and/or honing. (8) The following analysis values (%): C 0.90-1.10 Si 0.15-0.35 Mn 0.25-0.40 Cr 1.30-1.65 S 0.025 or less P 0 Claims 1 to 7 characterized in that a steel consisting of iron and impurities resulting from smelting is used, with a residual of .030 or less.
Please describe one of the methods listed above.