空气静压主轴气膜的压强分布与动态特性分析

Pressure Distribution of Gas Film and Dynamic Analysis for Gas Spindle

空气静压主轴的动态特性对机床加工精度影响很大,需要对主轴气膜的压强分布进行分析计算,从而分析其动态特性.通过对主轴在轴套内不同姿态时气膜压强分布采用无因次化压力膜雷诺润滑方程法进行有限元计算,得出不同姿态对应的坐标系各轴向的轴承反力以及反力矩,并探讨工作区间的主轴刚度以及角刚度的近似值,建立主轴力学方程分析主轴重心运动轨迹;引入旋转欧拉方程研究主轴轴线偏转状态,讨论主轴不同几何参数时轴线稳定性;提出通过提高主轴径向主惯性张量与轴向主惯性张量比值(采用径厚比大的盘形主轴结构)的方法提高机床的加工精度.可以为主轴结构设计提供理论指导,并为求解主轴刀具运动轨迹提供方法.

The machining precision is greatly influenced by the dynamic characteristics of the gas spindle.Therefore it is necessary to analyze and calculate the pressure distribution of the gas film to deduce the dynamic characteristics.The dimensionless Reynolds lubricating equation was processed with the finite element methods to acquire the pressure distribution of gas film at different poses in the spindle,thereby the counterforce and countertorque in the three axial directions corresponding to the spindle pose was acquired.Then the approximations of the rigidity and the angular rigidity of the gas spindle were discussed.With the rigidity parameter,the dynamic equation of six-freedom was established to obtain the barycenter orbit.Euler equation was introduced to analyze the deflexion of the spindle axes and to discuss the stability of the spindle axes with different geometry parameters.The method to promote the accuracy of machine tools was proposed: to increase the ratio of the radial inertia tensor to the axial inertia tensor of spindles(the pan model spindle with higher diameter-thickness ratio).It provides theoretical basis for the structure design of spindle and calculating method to solve the tool movement orbit.