Self-excited Vibration Study Of Static Pressure Gas Bearing With Effects Of Extrusion

With the increasing sophistication of precision machining and ultra-precision machining technology,gas lubrication has been applied in more and more occasions.In order to improve the bearing capacity and rigidity of the static pressure gas bearing,a common method is to add a pressure equalization tank.But the existence of the pressure equalization tank will increase the tendency of the gas hammer self-excitation.Hammer self-excited phenomenon is an abnormal phenomenon.Domestic and foreign scholars from different angles to explain the incentive for hammer self-excitation,but failed to reach a consensus on the mechanism and the inhibition of the gas hammer self-excitation.The study of the gas bearing self-excited hammer phenomenon becomes a hot and difficult point.In this paper,the disc thrust hydrostatic gas bearing is used to study the hammer self-excited phenomenon.Considering the squeezing effect,the gas Reynolds equation can be deduced by using gas continuity equation,Reynolds equation,state equation and gas boundary conditions.The gas-liquid Reynolds equation is discretized.The processed Reynolds equation is combined with the motion equation of the gas bearing to obtain the state equation of the gas-solid coupling.This state equation is the final theoretical model of the hammer self-excitation.Based on the theoretical analysis,the numerical simulation and experimental research are carried out.Through experimental study,the vibration frequency and amplitude characteristics are analyzed and compared,with or without air hammer.After several experiments,the vibration amplitude range of air hammer self-excitation is studied.Through the numerical simulation,the static experiment and simulation analysis are verified.The relationship between the bearing capacity and the film gap is analyzed.The experimental results of the hammer self-excitation and the simulation results are analyzed.The relationship between the self-excited vibration frequency of the hammer and the natural frequency of the system are analyzed.The numerical simulation of the theoretical model is carried out to further analyze the relationship between the structural parameters of the gas bearing and the phenomenon of self-excitation.