Design And Stability Analysis Of Porous Aerostatic Spindle

Aerostatic spindle is one of the most important parts in the ultra-precision machine tool.It has the advantages of high precision,no wear,long life and so on.However,the usual aerostatic spindle has the disadvantages of small load,low stiffness and poor stability,which limits its application.Therefore,this paper uses porous throttle which has larger load and stiffness.Because of the compressibility of the gas,stability of the aerostatic spindle is poor.At present,the study on the stability of the aerostatic spindle is mainly aimed at the thrust bearing with orifice,while the stability of the journal bearing is less.Therefore,this paper mainly studies the stability of porous hydrostatic spindle through FLUENT and ANSYS.The influence of gas pressure and bearing parameters on the static and dynamic stability is analyzed,and the accuracy of the results is verified by experiments.In this paper,the Reynolds equation of the hydrostatic bearing is calculated by the continuity equation and the N-S equation.And the flow rule of journal bearing is obtained by the fluid analysis software FLUENT.The pressure distribution of the journal bearing is obtained,and the effects of porous medium permeability and gas pressure on the load and stiffness of journal bearing are analyzed.Analyzing effect ion of film thickness and permeability,gas supply pressure and other factors on the vibration of air hammer.The stability of hydrostatic bearing is the premise that the aerostatic spindle can work stably and reliably.Therefore,this paper analyzed the static stability of porous aerostatic journal bearing by FLUENT after studying the static characteristics of the steady state.The dynamic Reynolds equation is solved by perturbation method.The stability of gas hammer vibration discriminant is obtained,analyzed the influence of permeability,gas film thickness and air pressure and other factors on the vibration of air hammer.This paper describes the mechanism of gas hammer vibration,put forward relevant measures to reduce the vibration of air hammer.The spindle is the high-speed rotation of the parts,which requires analysis of the dynamic stability of static pressure spindle,and the performance of dynamic stability performance as whirl.Therefore,this paper further analyzes the influence of the permeability,pressure and other factors on whirl,and uses FLUENT to obtain the dynamic stiffness of the spindle.The modal analysis of the spindle is carried out by ANSYS,and the natural frequency and mode of the spindle are obtained.In order to obtain the response of the spindle under the excitation,the harmonic response of the spindle is analyzed.The measures to improve the dynamic stability of the spindle are put forward.In order to verify the accuracy of the dynamic stability analysis of the hydrostatic spindle by using FLUENT,this paper uses the Lion Precision Spindle Error Analyzer to test the whirl of the spindle.And analyze the influence of rotating speed and pressure on the spindle whirl orbit.To verify the accuracy of the simulation results whirl orbit in Chapter fourth.