关键词: 动态误差, 功率谱密度, 空气静压导轨, 气膜波动, 小波变换

Abstract: The fluctuation of gas film of aerostatic guideway has been the main factor of the workpiece waviness in ultra-precision machining. The stiffness equation of a double row orifice of aerostatic guideway is derived by using Reynolds equation in order to analyze the performance of aerostatic guideway, the measurement experiment of corresponding static stiffness of aerostatic guideway is carried out to verify the correctness and feasibility of the established model of stiffness. Dynamic model of aerostatic guideway is established by combining the modal analysis result. The simulated results of stiffness and fluctuation frequency with the variation of thickness of gas film are obtained according to the dynamic model; the effect of fluctuation of gas film on the machining result is analyzed on the basis of the amplitude of vibration. Wavelet transform is used to decompose the measured signal of workpiece into low frequency signal and high frequency signal in every scale, and the power spectral density is used to analyze high frequency signal. Which scale the signal of gas film fluctuation lies in is identified according to the frequency of guideway system, the impact of gas fluctuation on the machining can be derived from the amplitude of power spectral density.

Key words: Aerostatic guideway, Dynamic error, Gas film fluctuation, Power spectral density, Wavelet transform