车铣复合数控机床空间误差建模和补偿

Modeling and Compensation of Spatial Errors in Turning and Milling Compound CNC Machine Tools

空间误差是影响车铣复合数控机床零件加工精度的最重要因素,现有方法对机床各轴的定位精度提升效果不好,为此设计车铣复合数控机床空间误差建模和补偿方法。忽略机床两个旋转轴的位置无关误差,通过齐次坐标变换理论构建其几何误差辨识模型,对几何误差辨识模型进行简化,实现两轴的几何误差辨识。在工件坐标系下,根据旋转轴几何误差辨识结果,采用多体理论构建机床空间误差模型。基于此误差模型,利用理想状态的逆运动学设计同步空间误差补偿策略,通过迭代方式对各轴补偿值进行计算,实现空间误差补偿。测试结果表明:设计方法补偿后,实验机床X轴、Y轴、Z轴的定位精度提升了0.6μm,B轴、C轴的定位精度提升了4″、3″,各轴的重复定位精度有很大提升,机床的反行程实验圆度也有所提升。

The spatial error is the most important factor affecting the machining accuracy of turning and milling compound CNC machine tools.The positioning accuracy of each axis of the existing machine tools is not improved effectively.Therefore,a modeling and compensation methods for the spatial error of turning and milling compound CNC machine tools were designed.Ignoring the position independent errors of the two rotating axes of the machine tool,the geometric error identification model of the machine tool was constructed through homogeneous coordinate transformation theory,and the geometric error identification model was simplified to realize the geometric error identification of the two axes.In the workpiece coordinate system,according to the results of geometric error identification of the rotation axis,the spatial error model of the machine tool was constructed using the multi-body theory.Based on the error model,the synchronous spatial error compensation strategy was designed by using the ideal inverse kinematics,and the compensation values of each axis were calculated by iteration to realize the compensation of spatial error.The test results show that the positioning accuracies of X axis,Y axis and Z axis of the experimental machine tool are improved by 0.6μm after the compensation of the designed method.The positioning accuracies of axis B and axis C are improved by 4″and 3″respectively,the repeated positioning accuracy of each axis is greatly improved,and the roundness of the reverse stroke test of the machine tool is also improved.