In ultra-precision fly-cutting machining, the aerostatic spindle is the key component, which has significant influence on the machined surface quality. The unbalanced spindle directly affects the machining accuracy. In this article, a prediction model of machining surface topography is proposed which involves the effect of the gas film performance of spindle in microscale. With the Weierstrass function, unstable transient response of the aerostatic spindle system is derived by the motion model of the spindle, which response signal represents the surface profile in the ultra-precision machining. Meanwhile, the experiment is performed with different rotation speed of the spindle. And the effect of the unbalanced aerostatic spindle on the surface generation is discussed in time and frequency domain. The conclusion shows that the similar cyclical surface ripple of the workpiece is independent of the spindle speed, and the rotation speed of the spindle and unbalanced spindle directly affects the machining surface topography. This study is quite meaningful for deeply understanding the influence rule of spindle unbalanced error from the viewpoint of machined surface and vibration frequency.
Purpose
To identify the dynamic feature of the aerostatic slider caused by gas film, an evaluation system by a piezoelectric acceleration sensor is presented in time and frequency domain.
Design/methodology/approach
The dynamic pressure fluctuation is evaluated by the wavelet transform, cross correlation analysis and power spectral density (PSD). Wavelet transform is used to process the measured result of the aerostatic slider and the signal is decomposed into high-frequency and low-frequency signal. Correlation analysis method is used to evaluate the impact of the initial gas gap on the fluctuation in time domain.
Findings
According to the PSD analysis of the processed signal in the frequency domain, the natural frequency of the aerostatic slider is identified from the measured signal in frequency domain; this method provides a basis for the identification of guideway errors.
Research limitations/implications
The method can also be applied to the error identification of other components of the machine tool.
Originality/value
Wavelet transform is used to process the measured result of the aerostatic slider by acceleration sensor, and the signal is decomposed into high-frequency and low-frequency signal. Correlation analysis method is used to evaluate the impact of the initial gas gap on the fluctuation in time domain. According to the PSD analysis of the processed signal in the frequency domain, the natural frequency of the aerostatic slider is identified from the measured signal in frequency domain; this method provides a basis for the identification of slider errors.
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