Study of the influence of tool rake angle in ductile machining of optical quartz glass

Abstract

The SPH simulation model of optical quartz glass was established to study the ductile machining process with different tool rake angles. The material removal mode, stress distribution, cutting force, and subsurface damage during machining were analyzed. The critical cutting depths of brittle-ductile transition under different tool rake angles were obtained. The simulation results show that the tool negative rake angle is better than the positive rake angle in promoting the ductile machining of optical quartz glass. When the tool rake angle is negative, significant compressive stress which suppresses the crack generation by reducing the stress intensity factor KI is generated in the chip forming area, thus realizing the ductile machining of optical quartz glass. The greater the tool negative rake angle is, the more stable the cutting force and the greater the critical cutting depths of brittle-ductile transition are. When the tool negative rake angle is greater than − 35°, the subsurface damage of the optical quartz glass is aggravated, and the subsurface residual stress is complicated. When the tool negative rake angle ranges from − 15° to − 35°, the optical quartz glass is not only machined in a stable ductile region but also has less subsurface damage. Finally, nano-scratch experiments were carried out, and the critical depths of the brittle-ductile transition obtained by the experiments are basically consistent with the simulation results, which verify the correctness of the simulation results. The research results in this paper could provide a theoretical basis for the optimal selection of tool rake angle in the ductile machining of optical quartz glass.