Hydrostatic Worktable Performance of an Ultra-precision Optical Aspheric Machine Tool

Abstract

Hydrostatic guide-ways utilizing thin film feedback restrictor are applied for the ultra-precision optical aspheric machine tool that we have developed. this machine tool. The parameters of the PM flow controllers have a direct influence on the dynamic performance of the hydrostatic worktable. During the machining process, the cutting force acted on the cutting tool and other load will be transferred to the hydrostatic guide-way. On the basis of the flow equation of the PM controller and the force schematic of the hydrostatic worktable, this paper theoretically establishes a mathematic model of the hydrostatic guide-ways of the worktable. The transfer function is derived, and the influence of the restrictor parameters, including the initial flow rate, oil film thickness, pump pressure and initial flow ratio, on the dynamic performance of the hydrostatic guide-way is studied. According to the results, it needs the longest time at the flow rate ratio Kr of 5 for the hydrostatic bearing system to adjust and the maximum displacement and the maximum overshoot arose. When the flow rate of the restrictor reaches 20cm3/s, the overshoot and response time of the hydrostatic guide-way bearing system hardly increase. The final displacement of the system decreases when the pump pressure increases. The effect of pump pressure increase provides a decrease in the final displacement of the system.