Numerical Simulation Research And Experimental Study Of Combined Radial-thrust Hydrostatic Gas Bearing On High-Speed CNC Milling Machine

Rolling bearing and sliding bearing are widely used in high-speed spindle of CNC milling machine,but the service life of rolling bearing is reduced of abrasion,and the application of sliding bearing is limited due to friction.Gas bearing has become the major supporting mode in high-precision and high-speed machine tools because of their advantages such as high-rotation speed,good stability,high precision,long lifetime and so on.Radial-thrust gas bearing of high-speed spindle of CNC milling machine was chosen as research subject,mainly probe the influencing factor and distribution rule of pressure field,speed field load capacity and stiffness by theoretical analysis numerical simulation,experiment and analyses of flow field pressure distribution,speed distribution,load capacity and stiffness characteristics.The structural parameter of bearing was designed by the theory of dynamic and static bearing.And the three-dimensional numerical simulation model of bearing was built.The hybrid meshes for the separated zones of the numerical modeling were generated using the structured,unstructured grids.The better mesh quality was obtained by mesh independence.The characteristics between radial-thrust gas bearing and single radial gas bearing,such as the pressure distribution,velocity distribution and load capacity and changing pattern of stiffness were obtained by the method of CFD to simulate flow field in numerical value under different operating conditions.Based on the comparisons of the result,the distribution rules were very different.The result shows that two models have different flow field distribution characteristics.The dynamic pressure effect of radial-thrust gas bearing in high speed was more observably,however,the load capacity was smaller than that of single radial gas bearing due to the influence of thrust surface flow field;and the stiffness was larger than single radial gas bearing under the condition of high speed and heavy load.The characteristics of spindle and bearing were tested with no-load,cutting state and static condition.The test of load capacity under different eccentric ratio was carried out by using single and double loading method,and the results were compared with the simulation results;The load capacity was tested in different eccentricity ratio by myself-compiled LAB VIEW program the program of LAB VIEW.The data amplitude shaft were collected at different speed and supply pressure,analyzing the results of stability of rotor and it changed regularity.