Rounding mechanism of a novel double-disc arc-contact lapping for high-precision rollers

Centerless grinding is the main technology for mass processing of rotary parts, which can improve the roundness of rotary parts. With the demand for higher levels of roundness accuracy (within 0.3 mu m), the development and operating costs of centerless grinding machines have increased dramatically. Taking cylindrical roller of bearing as research object, a new lapping process of double-disc arc-contact lapping ( DDACL) is presented in this work. On the processing mechanism, it is expounded how DDACL overcomes the three fundamental technical difficulties of centerless grinding process in geometric lobing, workpiece instability and work-regenerative chatter vibration, and the unique rounding mechanism of DDACL process is established. At the same time, the machine has simple structure, low precision requirement, and low cost. After lapping with 45 steel groove on the developed test bench, the roundness accuracy of the cylindrical roller is effectively controlled within 0.2 mu m, and the accuracy of some rollers can even reach 130 nm, which has significant precision advantages. According to the established DDACL rounding mechanism, the influence of 45 steel and PTFE groove material and electromagnetic driving force on the rounding speed of parts in the test is well explained. The process method proposed in this work paves the way for improving the roundness accuracy of other rotary parts, such as those seen in tapered roller and spherical roller.