永磁同步型磨削电主轴运动精度分析

MOTION PRECISION ANALYSIS OF PERMANENT MAGNET SYBCHRONOUS GRINDING MOTORIZED SPINDLE

随着高档数控机床对主轴的运动精度的要求不断提高,研究永磁同步型磨削电主轴运行精度问题是十分必要的。在基于主轴振动误差和热分析的基础上,分别建立了径向误差运动、倾角误差运动和轴向误差运动数学模型。应用最小二乘法近似算法拟合主轴径向误差运动轨迹,然后对倾角运动误差进行建模,得到主轴回转轴线的倾斜角度。结合时域和频域信号分析方法,对轴向运动误差轨迹展开分析。为了实现一次测量主轴径向和轴向误差位移,并且获得主轴热误差,采用了典型的双标准球5-DOF测量主轴误差装置。通过国产某机床厂所研发永磁同步型磨削电主轴在试运行时主轴回转误差问题进行了实验。研究结果表明:当转速升高到最高转速,径向误差和轴向误差升高,离心力对主轴精度作用更加明显;当存在主轴偏心时,径向误差运动轨迹为逐渐由近似圆过渡到花瓣状态;双标准球五点法测试方法不仅可以判断电主轴制造存在的制造、装配等问题,并且该实验方法可应用于电主轴误差运动的实验,同时满足倾角误差、轴向误差运动和主轴温度变形的测试。

With the increasing requirements of the high-speed CNC machine tools for the motion accuracy of the spindle,it is necessary to study the accuracy of the permanent magnet synchronous(PMS)grinding motorized spindle.Based on the spindle vibration error and thermal analysis,mathematical models of radial error motion,tilt error motion and axial error motion are established.The least squares approximation algorithm is applied to fit the radial trajectory of the spindle,and then the inclination error is modeled to obtain the tilt angle of the spindle’s axis of rotation.Combined with the time domain and frequency domain signal analysis methods,the axial motion error trajectory is analyzed.To achieve a radial and axial error displacement of the spindle and obtain the spindle thermal error,a typical double standard ball 5-DOF measuring spindle error device is used.Experiments were carried out on the spindle rotation error during the test run by the PMS motorized spindle developed by a domestic machine tool factory.The results show that when the speed increases to the maximum speed,the radial error and the axial error increase,the centrifugal force has a more obvious effect on the spindle accuracy;when there is the spindle eccentricity,the radial error motion trajectory gradually transitions from the approximate circle to the petal state.The double standard ball five-point test method can not only judge the manufacturing,assembly and other problems of the electric spindle manufacturing,and the experimental method can be applied to the experiment of the electric spindle error motion,while satisfying the inclination error,the axial error motion and the spindle temperature deformation test.