关键词: 低温加工, 聚晶立方氮化硼刀具, 淬硬轴承钢, 刀具磨损, 加工表面质量

Abstract: In the high-speed hard turning processes for hardened bearing steels, there were some problems such as rapid tool wear, serious chip entanglement and poor machined surface quality. The high-speed hard turning tests of GCr15 bearing ring were carried out with PCBN tools using high-pressure cryogenic CO2 jet as cooling medium, and compared with high-pressure emulsion and high-speed dry cutting, and the effects of cooling conditions and cutting parameters on cutting performances and machined surface quality were analyzed. The results show that within a certain range of the cutting parameters, the use of high-pressure cryogenic CO2 jet assisted cutting may effectively reduce tool wears and improve chip breakings, but it is also more likely to chipping when the tools are in the stage of severe wear. When the cutting speed is high, the high pressure cryogenic CO2 jet may improve the surface quality of the workpieces more significantly, effectively reduce the surface roughness of the workpieces, increase the residual compressive stresses and surface microhardnesses.

Key words: cryogenic machining, polycrystalline cubic boron nitride(PCBN) tool, hardened bearing steel, tool wear, machined surface quality