Design and Manufacture of High-Performance Hydrostatic Air Bearing Spindle with Grid-Shaped Grooves.

Abstract

This paper describes the design and manufacture of a new hydrostatic air bearing spindle with grid-shaped grooves that can provide a relatively high damping ratio in a high-frequency region of resonance, as well as high stiffness. The numbers of inner grooves on the inner surfaces of the thrust, angular and radial bearings are determined so that gas film damping becomes maximum near the natural frequencies of the thrust and radial vibration modes. Increases in groove number and groove depth generally result in high damping in the high-frequency region, but excessive increases cause damping to be negative in the low-frequency region. The design procedure to determine the optimal value of the groove parameters is described by the design charts based on numerical calculation. From the evaluation of the manufactured prototype, it is proved that the proposed air bearing spindle can realize relatively high damping ratios of thrust, angular and radial modes of 0.07, 0.11 and 0.15, respectively, while maintaining high static stiffnesses of 627 N/μm and 99 N/μm in the thrust and radial directions, respectively.