Research On Self-excited Vibration Of Air Hammer Of Disk Hydrostatic Gas Thrust Bearing Based On Weak Coupling Method

With the advantages of high precision,low friction,simple structure and less pollution,gas bearing has been applied in more and more precision and ultra precision machining occasions.In order to obtain greater bearing capacity and higher stiffness,the simplest and most efficient method is to process the pressure equalizing groove in the bearing or increase the air supply pressure,but these two measures are easy to cause the self-excited vibration of the air hammer.The abnormal phenomenon of self-excited vibration of air hammer produces high frequency vibration accompanied by whistling,and the bearing will lose stability and cannot work.The input mathematical model of disc aerostatic thrust bearing was established,and the self-excited vibration of air hammer was studied.Firstly,starting from the gas continuity equation in polar coordinates,the gas Reynolds equation is obtained by combining the equation of state and the equation of motion.The Reynolds equation is reduced by using the Galerkin weighted residual method and discretized by using the finite element method;Then,the influence of bearing structural parameters on static characteristics such as bearing capacity,stiffness and flow rate is studied by programming;Finally,after the corresponding static characteristics are obtained,a short time interference is added to the program to make the bearing self-excited vibration by air hammer.Taking the air supply pressure and bearing mass as the coordinate axis parameters,the stable region of the bearing is obtained,and the characteristics of the stable region under different parameters are studied by changing the bearing parameters,The variation characteristics of self-excited vibration amplitude and vibration frequency of air hammer under different parameters are analyzed.On the basis of numerical simulation results,experimental verification is carried out.Experiments on a cellular platform verify the correctness of the simulation results;The critical point of air hammer is recorded,and the stability region of the bearing is constructed,which is compared with the stability region obtained by simulation;The relationship between film thickness and time is transformed by Fourier transform.The vibration amplitude and frequency are extracted and compared with the simulation results to verify its correctness.