The cold treatment of the bearing sleeve mainly refers to a processing process after the bearing material after forging heat treatment, mainly by staying in an environment after the quenching is placed in an environment where the quench is restored for a period of time, this process is called cold treatment, and the following turntable Everyone introduces the role of the cold treatment of the bearing ring and related process.
First, the effect of cold treatment Be Precision bearing is high in size stability; after the ferrule quenching (especially grading), the internal tissue still retains more residual austeel, which is unstable, in storage and use bearing In the process, it will continue to change, thereby changing the accuracy of the bearing. For this purpose, a cold treatment process is used, which reduces the residual bombs in the tissue and slightly improves the hardness of the part.
Second, cold treatment process and requirements
1. After quenching, stay at room temperature: After quenching, be sure to make cold treatment inside and outside the ferrule, otherwise it is easy to crack, cold to room temperature, cold treatment (generally no more than 30 minutes), otherwise it will stop the austenite The transformation of the hometown.
2, cold treatment temperature: The temperature of the cold treatment is mainly based on the martensite transition temperature MF of the steel, and the impact of cold treatment on mechanical properties and processability is considered. For GCR15 steel, cold treatment is used to use -70 ° C; when the accuracy requires less than a ferrule or device, the cold treatment temperature can be selected from -40 to -70 ° C; ultra-precision bearing, can be at -70 ° C ~ -80 ° C Cold treatment is carried out. Overcloowise temperature affects the bearing impact fatigue and contact life.
3, cold treatment insulation: Although the change in mass martensite is completed when it is cold to a certain temperature, but in order to make a batch of ferrule surfaces and the center of the center, there is a certain holding time, generally 1 to 1.5 h.
4, the cold treatment after cold treatment: After the ferrule is cold, placed in the air, and the temperature is slow to rise to the room temperature. Wenheng can’t be too fast, otherwise it is easy to crack; tempering time, otherwise the residual stress inside the ferrule can cause the ferrule crack, generally no more than 2 hours.