磨床电主轴动静压轴承静动特性的理论研究

Theoretical study on the static and dynamic characteristics of hydrostatic and dynamic bearings for grinding machine electric spindle

针对精密磨床电主轴的高精度设计需要,采用动静压轴承作为支承轴承,动静压轴承采用四油腔小孔节流结构。文章分析了动静压轴承的结构和使用工况,给出了动静压轴承的静动特性的理论计算方法,分析了节流孔径d和油腔面积A对静动特性的影响,静特性包括承载力F和流量Q,动特性包括刚度系数k和阻尼系数c。研究结果表明:随着d的增大,F先增大后减小,在d为0.5 mm时达到最大值;Q随d的增大而增大,且增大的趋势逐渐变缓;F随A的增大呈线性增大,当A大于1 000 mm^(2)之后F开始减小。Q随着A增大而增大,但增大趋势有递增迹象;主刚度k_(xx)随着d的增大先增大后减小,在d为0.5 mm时达到最大值,k_(yy)随着d增大而减小,但在d为0.5 mm之后的减小趋势放缓;随着A的增加,两个方向主刚度k_(xx)、k_(yy)均近似线性增大,k_(xx)在A大于1 000 mm^(2)时达到最大值,交叉刚度k_(xx)随着A增大而递减,但在递减趋势逐渐平缓。

In order to meet the need of high-precision design of electric spindle of precision grinding machine,static and static bearings are used as support bearings,and the structure of static and static bearings is small orifice restrictor with four oil cavities.The structure and operating conditions of the bearings are analyzed,the theoretical calculation method of the static and dynamic characteristics of the bearings is given,and the influence of the throttle aperture d and the oil cavity area A on the static and dynamic characteristics is analyzed.The static characteristics include the bearing capacity F and the flow rate Q,and the dynamic characteristics include the stiffness coefficient k and the damping coefficient c.The results show that with the increase of d,F first increases and then decreases,and reaches the maximum value when d is 0.5 mm.Q increases with the increase of d,and the increasing trend becomes slower.F increases linearly with the increase of A,and begins to decrease when A is greater than 1 000 mm^(2).Q increases with the increase of A,but the increasing trend shows an increasing sign.The principal stiffness k_(xx) firstly increases and then decreases with the increase of d,and reaches the maximum value when d is 0.5 mm.k_(yy) decreases with the increase of diameter,but the decreasing trend slows down after d is 0.5 mm.With the increase of A,the principal stiffness k_(xx) and k_(yy) in both directions increase approximately linearly,and k_(xx) reaches the maximum value when A is greater than 1 000 mm^(2).The cross-stiffness k_(xx) decreases with the increase of A,but the decreasing trend is gradually gradual.