多轴数控机床转台误差快速检测与分离

Fast geometric error measurement and identification of rotary table for multi-axis CNC machining tools

转台是多轴数控机床的重要运动部件,其精度对机床的加工精度产生重要影响。针对多轴数控机床转台的6项运动误差和2项轴间关系误差,提出转台误差检测及分离的快捷方法,基于球杆仪,能将8项转台误差中的7项快速检测和分离,1项采用激光干涉仪进行测量。首先,建立了球杆仪检测转台运动误差的多项式模型,分别采用平行于X轴、Y轴、Z轴和锥形的特殊安装方式依次分离出转台的3项平移误差和2项旋转误差。其次,提出利用检测球杆仪轨迹偏心的方法分离出转台旋转轴与对应平移轴间的2项轴间关系误差。为验证提出方法的有效性,对大型数控磨齿机的转台误差进行了检测、分离及加工验证实验。利用检测结果对工件加工误差进行了预测,预测值与工件加工实际误差的一致性证明了提出的转台误差检测方法有效。该方法具有操作简单、耗时少、适合于加工现场等优点。

Rotary table is the key moving component of multi-axis CNC machining tools and has deep influence to the machining accuracy of CNC machine tools. This paper presents the fast methods for the measurement and identifying geometric errors, within which 5 motion errors and 2 parallelism errors between rotary axis and corresponding transla- tional axis are obtained using a ball-bar device, and 1 motion error is obtained using the laser interferometer. Firstly, a polynomial model for detecting the motion errors of the rotary table based on ball bar device is established, with which 3 translation motion errors and 2 rotary errors of the rotary table are identified adopting the special installation modes of the ball bar device, including the modes parallel to X axis, Y axis, Z axis and conical mode. Secondly, a method identifying 2 parallelism errors between rotary axis and corresponding translational axis of the rotary table is developed through detecting the trajectory eccentricity of the ball-bar device. To verify the effectiveness of the error model and the error detection method, the rotary table geometric errors of a large-scale gear form grinding machine were measured, identified, and the machining verification experiment was carried out. The measurement results were used to predict the workpiece machining errors;the predicted values and the actual machining errors are consistent, which proves that the proposed rotary table error measurement method is effective;the proposed method features sim- ple operation, low time consumption and is suitable for machining field application.