超精密机床径推一体式空气静压轴承的静态特性

摘要

A new vertical spindle supporting system was presented to improve the stiffness of an aerostatic bearing and to meet the requirements of machine tools for aerostatic bearings.The Computational Fluid Dynamics (CFD) and Finite Volume Method (FVM) were used for simulating the flow field and pressure field inside the aerostatic bearing and for researching its static characteristics.The grid subdivision in the direction of film thickness was implemented while establishing the grid of the gas film.Finally,a 2 μm/grid on the thrust surfaces and 2.5μm/grid on the radial surfaces along the film thickness direction were achieved.Results indicate that the gas velocities around the orifices are about 200 m/s and 1 m/s when the pressure distribution of the gas film is changed and the loading capacity is achieved 3 508 N/μm.It concludes that the static characteristics of the aerostatic bearing can be improved by increasing supply pressures or decreasing the diameters of orifices.%提出了一种新的径推一体式静压主轴支撑方式来优化机床主轴系统性能,以满足超精密飞切机床对气体静压轴承高刚度的要求.采用计算流体力学和有限体积法对气体静压轴承气膜内部的流场与压力场进行仿真,并研究其静态特性.为提高计算精度,完成了轴承宏观尺寸与气膜厚度相差几个数量级时气膜厚度方向2 μm间距的网格划分.仿真结果表明,在偏心状态下由于气膜压力的变化使节流孔气体流速在1～200 m/s内变化,机床所采用径推一体式轴承静态刚度达到3 508 N/μm.研究表明,通过增大轴承的供气压强和减小节流孔的直径可改善轴承的静态性能进而提升机床性能.