With the rapid development of numerical control technology, the machine tool industry technology has also developed rapidly. Among them, high-speed machining can improve the machining rate of the machine tool and shorten the machining cycle of the workpiece. This requires the machine tool spindle and its related components to meet the needs of high-speed machining. At present, CNC machine tool spindle bearings are basically limited to four types of structural types: angular contact ball bearings, cylindrical roller bearings, two-way thrust angular contact ball bearings and tapered roller bearings.
The precision angular contact ball bearing is made of bearing steel. The points of the bearing are:
1. Contact fatigue strength
Under the action of cyclic load, the bearing is easily exposed to fatigue damage, that is, cracking and spalling, which is an important damage situation of the bearing. Therefore, in order to improve the service life of the bearing, the bearing steel must have a high contact fatigue strength.
2. Wear resistance
In the bearing task, not only the rolling friction between the ferrule, the rolling element and the maintenance frame occurs, but also the sliding friction occurs, so that the bearing parts wear directly. In order to increase the wear of the bearing parts, maintain the bearing accuracy and stability, and extend the service life, the bearing steel should have good wear resistance.
3. Hardness
Hardness is an important quality of bearing quality and has an indirect effect on contact fatigue strength, wear resistance and elastic limit. The hardness of the bearing steel in the application condition has to reach HRC61~65, which makes the bearing achieve high contact fatigue strength and wear resistance.
4. Anti-rust performance
In order to avoid corrosion and rust of bearing parts and finished products during processing, storage and operation, it is required that bearing steels should have good rust prevention performance.
5. Processing performance
In the course of consumption, bearing parts have to go through many cold and hot processing steps. In order to satisfy the request of small amount, high strength and high quality, bearing steel should have good processing performance. For example, cold, thermoforming properties, machinability, hardenability, and the like. In addition to the above basic requirements, the bearing steel should also reach the requirements of appropriate chemical composition, average external organization, less non-metallic inclusions, conformity of external appearance defects, and appearance of decarburization layer not exceeding the regular concentration.
