Dynamic characteristics of an aerostatic bearing spindle and its influence on surface topography in ultra-precision diamond turning

Abstract

In ultra-precision diamond turning (UPDT), aerostatic bearing spindle vibration plays the major part in many factors that influence surface topographies. In this paper, a five-degree-of-freedom dynamic model for an aerostatic bearing spindle is built up to describe its dynamic responses, involving translational motions and tilting motions, and to analyze the effects on surface topography of the spindle vibration under different cutting processes in UPDT. It was found that the spindle processes at the axial natural frequency along the axial direction, the radial natural frequency along the radial directions and the twin tilting natural frequencies around the radial directions, and when cutting develops from outside to the center of the machined surface, the dominant effects of the spindle's tilting motions on surface topography gradually disappear and the axial translational motion produces a great influence on surface topography. This was identified by the experimental results.