Surface profile prediction modeling of spiral toolpath for axial ultrasonic vibration-assisted polishing

Hard and brittle materials are widely used in many frontier fields because of their better properties, and their efficient precision polishing methods are attracting much attention. The research on surface quality of optical lenses with surface finishing requirement not only involves surface roughness, but also surface form accuracy. The generated surface profile is a key factor affecting the surface form accuracy and overall smoothness. From experience, both processing mechanism of adopted method and toolpath have effects on the generated surface profile. For this, the paper presents a theoretical and experimental study of the generated surface profile of spiral toolpath in axial ultrasonic vibration-assisted polishing (UVAP). Based on classical Preston equation, Hertzian contact theory and the axial vibration-assisted processing principle, a prediction calculation model for generated surface profile of spiral toolpath is proposed. The model can specifically analyze the dwell-time distribution characteristics of periodically varying contact pressure and sliding velocity in the areas near/far-from the curvature center of curve toolpath, accurately predict the surface profile shape and material removal rate (MRR), and scientifically reveal the assisted processing principle. Accordingly, a series of experiments are conducted to verify the rationality of the proposed model and the polishing performance of axial UVAP. Compared to conventional methods, the predictions can more reasonably and accurately present the real surface profile characteristics, both high MRR and superior surface quality are obtained. This study would aid in achieving a deterministic processing technology of higher efficiency and better surface quality, laying a crucial theoretical basis for the global polishing of optical lens.