Study on the removal mechanism of ultrasonic vibration-assisted helical grinding for hole-making in SiC ceramics

Ultrasonic vibration-assisted helical grinding(UVHG) has emerged as a novel method for hole precision machining in brittle silicon carbide(SiC) ceramics. The impact of coupled multiple movements in UVHG makes the materials removal mechanism, the evolution law of tool wear and machining quality extremely complicated. To address that, this paper systematically investigates the UVHG of SiC ceramics for hole-making through theoretical modeling, simulation analysis, and experimental validation. Based on the indentation fracture theory and the trajectory analysis of abrasives, the SiC ceramics removal mechanism of UVHG is investigated considering the impact of multi-abrasive. The SiC ceramics removal process can be divided into four stages, sequentially named abrasive indentation, crack expansion, crack interweaving and material removal. Considering the influence of the previous and subsequent cut-in positions of the abrasive, a dual-abrasive simulation is constructed to verify the material removal mechanism and determine the influence of process parameters on the material removal process. It’s found that ultrasonic vibration enhances the crack interweaving effect in removing material from adjacent cut-in positions. A mechanical model of UVHG is constructed by novelly combining the conical frustum removal volume and the semi-ellipsoid removal volume. The model exhibit congruence with experimentally measured grinding forces in trend variation patterns. Through the hole-making experiment of UVHG, the influence law of process parameters on grinding force is obtained and utilized to calibrate the mechanical model. Moreover, the grinding wheel wear is analyzed by characterizing the topography of the worn wheel and the machining quality of the machined hole. The UVHG method has been proven effective in improving the wheel wear by enhancing the crack interweaving and optimizing the motion trajectory of abrasives, contributing to the maximum reduction in the roughness of the hole’s bottom surface by 41.8%.