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On Orifice Design for Reducing Self-Excited Vibration of Aerostatic Guideway

Aerostatic guideway is an essential sub-system for high-accuracy measurement. As compressible air is used for suspension, several problems arise aside of its other advantages. The most important aspect that should be taken into consideration is self-excited vibration activated by inner or/and outer environments. This paper discusses how the orifice layouts and the orifice diameter affect the self-excited vibration of the aerostatic guideway, or two-dimension x-y stage as a whole. Theoretical formulas for flow coefficient of orifices are obtained and experiment of differential pressure test is conducted. Both theoretical and experimental approaches of aerostatic guideway design and characteristics of vibration attenuation are proposed in this research. The results show that by optimizing orifice diameter and orifice layouts, good effect on reduction of self-excited vibration can be achieved, with the time of vibration attenuation reduced from 1.8s to 0.9s.