Research On Numerical Analysis And Experiment Of Fluid-structure Interaction Of Aerostatic Motorized Spindle

High-speed aerostatic motorized spindle integrates the characteristics of high-speed motorized spindle and gas bearings,it is widely used in precision and ultra-precision CNC machine tools with the advantages of high precision,high speed,low wear,high cleanliness and smooth operation.With the development of theories and applications of gas bearings,simple characteristic study of gas bearing has been unable to meet the actual design demands.The study of the gas bearing should take full account of the interaction between the gas bearing and the rotor,especially the influence of the rotor motion on the gas bearings-rotor system.This thesis regards the high-speed aerostatic spindle as research subject,the effect of two-way fluid-structure interaction on the gas bearings-rotor system,rotor tilting on the capacity and stiffness of the radial bearing are studied.At the same time,the static and dynamic loading experiment to test the static and dynamic performance of aerostatic motorized spindle is carrying out.The simulation model of gas bearings-rotor system is established,then the numerical analysis method is used to simulate the two-way fluid-structure interaction.The load capacity characteristics of gas bearings-rotor system under radial and axial loading are analyzed.The results show that the rotor displacement,the gas bearing film pressure and capacity are changing dynamically during the fluid-structure interaction process.When the system is stable,the rotor is tilted,the air film thickness and pressure distribution is not uniform.The radial displacement of the rotor has increased trend with the rotor speed increases when the supply pressure is constant,increasing the supply pressure can reduce the radial displacement of the rotor and this can reduce the probability of collision between the rotor and the radial bearing.The simulation model of radial gas bearing under rotor tilting condition is established,and the CFD method is used to simulate the flow field.The changes of capacity and stiffness of the radial gas bearing under different tilt angle,different speed and different film eccentricity are analyzed.The results show that the when the rotor is stationary,bearing capacity decreases with the increase of tilt angle,while the bearing capacity increases with the increase of tilt angle when the rotor rotates,which reflects the effect of the hydrodynamic effect on the nonuniform air film thickness.The bearing stiffness increases with the increase of tilt angle when the rotor rotates.The experiment rig for performance test of high-speed aerostatic motorized spindle is established,then the static and dynamic radial loading experiment are carried out by using the non-contact loading method on the aerostatic motorized spindle.The displacement of rotor front and rear end are obtained under different load,different supply pressure and different speed,then compared with the fluid-structure interaction data.The results show that the simulation results are in agreement with the experimental results,and the effectiveness of the fluid-structure interaction simulation can be verified.