Study Of Tilt Characteristics Of Aerostatic Thrust Bearings

Because of the advantages of no friction,low wear and low heat,aerostatic bearings have been widely used in the field of ultra-precision measurement and processing,and they have become one of the most important basic components of ultra-precision motion platform.With the development of the research on aerostatic bearings,researchers found that under the action of the impact load,the torque produced by eccentric load,and the error caused by the processing and assembling error of the system,the aerostatic bearings are always tilt.This tilt vibration has a harmful effect on the positioning accuracy and stability of ultra-precision motion platform.In order to reduce the harm of the tilt vibration and improve the stability of the system,a numerical method is proposed in this paper to calculate the static and dynamic tilt characteristics of the aerostatic bearings.The influence of the structure parameters and operating parameters on the static and dynamic tilt characteristics are analyzed,and the accuracy of the numerical model is verified by experiments.In this paper,on the basis of Reynolds lubrication equation,the static and dynamic characteristics of aerostatic bearings are obtained by perturbation method.The static and dynamic tilt stiffness and damping of the aerostatic bearings are calculated.The influence of structure parameters of aerostatic bearings and the external load on the static stiffness and damping are researched at the meantime.The influence of the number of extrusion and the load on the dynamic stiffness and damping of the aerostatic bearings are also researched.Then,the experimental platform of the aerostatic bearing tilt is built,and the response of aerostatic bearings under external excitation is tested by hammering method.Based on modal analysis method,the mode of the aerostatic bearing is calculated,and the tilt stiffness of the aerostatic bearing is calculated by using the method of parameter identification.The accuracy of the numerical model is verified by comparing the experimental results with the numerical results.Finally,a new global pressure measuring method which combines the pressure-sensitive film and image post-processing method is proposed to obtain the pressure distribution of the gas film.The experimental results are in good agreement with the simulation results.