Study On The Dynamic Characteristics Of The Aerostatic Bearings Spindle And Its Influence On Workpiece Turning Quality

With the development and progress of society,people are increasingly demanding on the quality and performance of the product.Lathe is one of the most widely used processing equipments.Because of the dynamic characteristics of the spindle at high speed,it will directly affect the machining surface quality.Therefore,the dynamic characteristics of the spindle system is one of the important indexes to evaluate the machining accuracy of the lathe.At present,the domestic precision lathe,whether its reliability,functional completeness and stability,or from precision have a certain distance in comparison with foreign advanced machine tools.In this paper,the bearing mechanism of aerostatic bearing is analyzed.And improve the structure of the spindle system with the aerostatic bearing.In the view of the maximum bearing stiffness and the reduction of the gas diffusion and circulation,optimize the structure and working parameters.Based on the basic equation of gas lubrication,simplify some conditions in hydromechanics and deduce the general form of the Reynolds equation.Besides,analyze the boundary conditions.Based on the theory of hydrostatic gas lubrication,the Reynolds equation is treated by dimensionless method and discretized by finite element method.The basic performance parameters of bearing are determined by the method of proportional division and successive over-relaxation.The pressure distribution of gas film flow field is simulated by FLUENT software.With the effect of various factors,study the change of the bearing capacity and stiffness of small bore aerostatic bearings.The basic theory of rotor dynamics is analyzed in this paper.Simplify the spindle rotor system model and establish the dynamic model of the aerostatic bearing rotor system.The natural frequencies and mode shapes are obtained by modal analysis.Based on the vibration characteristics of spindle,calculate the endpoint displacement response of the forced vibration of spindle by MATLAB.And regard it as the basis for the evaluation and prediction of the machined surface quality.