基于球杆仪的五轴数控机床误差快速检测方法

Fast error identification method for five-axis machine tools based on double ball-bar

几何误差是五轴数控机床重要误差源,针对传统测量方法仪器昂贵、测量周期长问题,提出基于球杆仪的五轴数控机床几何误差快速检测方法。对于机床的平动轴误差,利用多体系统理论及齐次坐标变换法,建立平动轴空间误差模型,通过球杆仪在同一平面不同位置进行两次圆轨迹,辨识出4项平动轴关键线性误差;针对五轴机床的转台和摆动轴,设计基于球杆仪的多条空间测试轨迹,完整求解出旋转轴12项几何误差。实验结果显示,所提方法获得转角定位误差与激光干涉仪法最大误差为0.001 8°,利用检测结果进行机床空间误差补偿,测试轨迹偏差由16μm降至4μm,为补偿前的25%,验证了方法的有效性。提出的五轴机床几何误差检测方法方便、便捷,适用于工业现场。

Geometric errors are important error sources of the computer numerically controlled(CNC)five-axis machine tool.The conventional measurement methods and instruments are expensive and have a long measurement period.To address these issues,a fast identification method for geometric errors of a five-axis machine tool based on a double ball-bar is proposed.For the errors of linear axes of the machine tool,a spatial error model for linear axes is formulated,which is based on the multi-body system theory and homogeneous coordinate transformation.By measuring two circular trajectories of a double ball-bar(DBB)at different positions on the same plane,4 key linear errors of the linear axes are identified.For the rotary table and swing axis of the five-axis machine tool,12 geometric errors of the rotary axes are ascertained using the axial,radial,and conical measurement modes of the DBB,combined with the polynomial model.The experimental results of angle positing error show that the maximum error of the proposed method is 0.0018°,compared with that of the laser interferometer method.By using the identification results of the machine tool space error,the error of the test track is reduced from 16μm to 4μm,which is 25%before compensation.It evaluates the effectiveness of the method.The proposed method of geometric error identification for five-axis machine tools is convenient,and suitable for the industrial field.