Measurement And Analysis Of Rotation Error Of The Ultra-precision Aerostatic Spindle

As one of the important components of the ultra-precision machining machine,the aerostatic spindles have its rotary error that directly affects the machining accuracy of the machine tools.Therefore,in the process of designing,manufacturing and assembling of the machine tools,the measuring of the spindle rotation error is a key technology which is also an important technical problem to improve the measurement accuracy.Firstly,according to the specific requirements of the spindle design in this paper,closed aerostatic bearings are selected as the supporting components,and the design of the bearing structure and the spindle control system will be emphasized.By studying the working principle of the aerostatic bearing,the orifice throttling structure has been choosed.The main structurel dimensions of the bearing are designed by the gauge pressure ratio method.By studying the control system of the main shaft and using a full-closed-loop control scheme,the stability of the main shaft system is improved.Secondly,fourier transform and MATLAB are used to simulate and analyze the harmonic components in the spindle rotation error and the synchronous error and asynchronous error.Based on the Inverse Method,Multi-step Method,Multi-point Method and the Two-point Inverse Method measurement theory proposed in this paper,by comparing the predicted value with the simulated value,the relative error of each method is calculated as well as the advantages and disadvantages of each method.Based on the analysis above,the Two-point Inverse Method was chosen to measure the aerostatic spindle.Then,based on the experimental measurement hardware system,the designed aerostatic spindle is measured to obtain the rotation errors of the spindle at different speeds.Based on the measured data of the total errorsat different speeds of the spindle and the synchronous errors and asynchronous errors,the relationship between the speed and the corresponding errors is obtained.Based on the simulation analysis of the measured data,the main harmonic components of the spindle rotation errors are obtained.The reliability of the separation accuracy of the Two-point Inverse Method was verified by comparing the Two-point Inverse method with the measurement results of the US Lion Rotation Error Analyzer on the time-domain image and the frequency-domain image.Finally,through the experiment of measuring the rotary errors of the aerostatic spindle,the source of the spindle rotation error is analyzed.Based on the principle of the influence of the unbalance of spindle movement on the rotation error,the front-end surface of the spindle is selected to perform the experiment of dynamic balance correction of the spindle.By balancing the moment of inertia of the main shaft,the unbalanced movement problem of the main shaft is solved.Based on the value of the harmonic component of the gyration errors corresponding to the different deviations of the standard ball,the influence of the deviations on the rotation error of the spindle is obtained,and the installation deviation is reduced by designing the vacuum adsorption device to fine-tune the position of the standard ball.Based on the rotation error value corresponding to different installation deviations of the sensor,the installation deviation influence is obtained,and the installation deviation is corrected by the measurement software.