Research On Cryogenic Process And Equipment Of Automobile Hub-bearing

Automobile hub-bearing is one of the most important parts of the car. The unstable quality of domestic product influences hub-bearing's service life and reliability. These problems, which are caused by the met stable phase retained austenite, perennially plagued the domestic enterprise that produces auto-hub bearings. To improve the quality of auto-hub bearing, the cryogenic treatment was adopted to control the percentage of retained austenite of bearing rings.To meet the characteristics and requirements, the shortcomings of current cryogenic in structure was removed. Conveying belt cryogenic equipment, which will use with the conveying belt heat treatment production line, and well shape cryogenic equipment were designed.To satisfy the mass production requirement of efficiency, stable and low cost, the relationship between cryogenic treatment parameters and microstructure of the hub-bearing was studied. The percentage of retained austenite after different cryogenic treatment was measured by X-ray diffraction experimental. The equation, which revealed the relationship between the percentage of retained austenite and cryogenic temperature and insulation time, was established by the analyzing of measurement result data. The investigation revealed, that the amount of retained austenitic can be sharply reduced by lower cryogenic temperature and extend insulation time. In order to study relationship between cryogenic treatment parameter, microstructure of bearings and mechanical performance, the hardness and toughness of the bearing parts were tested. The curve relation between cryogenic treatment parameters and mechanical performance was established.