数控机床转台位置相关几何误差的快速测量与辨识

Rapid measurement and identification of position dependent geometric errors of CNC machine tool turntable

为快速辨识数控机床转台位置相关几何误差,提出一种基于球杆仪的转台位置相关几何误差快速测量辨识方法。首先,基于齐次坐标变换建立转台位置相关几何误差模型,得到球杆仪杆长变化量与几何误差的关系;其次,设计球杆仪六次锥形安装方式,推导出误差辨识矩阵,记录球杆仪杆长变化量,快速辨识出转台位置相关几何误差,并提出一种球杆仪安装误差消除方法,有效剔除了安装误差的影响;最后,基于转台位置相关几何误差的辨识结果,对附加实验中球杆仪杆长变化量进行预测,预测精度较高;在此基础上,对转台位置相关几何误差进行补偿,补偿后的精度明显提高。结果表明:该方法可准确快速辨识出数控机床转台位置相关几何误差,对提高机床精度具有重要的意义。

In order to quickly and systematically identify the position dependent geometric error terms of CNC machine tool turntable,a rapid measurement and identification method of the geometric error of the turntable based on a double ballbar is proposed. Firstly, based on the homogeneous coordinate transformation theory,the position dependent geometric error model of the machine tool turntable is established,and the relationship between the change in ballbar length and the geometric error during the movement of the ballbar is obtained. Then,a six-time tapered installation method of the ballbar is designed,the error identification matrix expression is direved,the change in the length of the ballbar during the movement of the ballbar is record,and the position dependent geometric error terms of the turntable can be quickly identified. Then,a method for eliminating the installation error of the double ballbar is proposed,which can effectively eliminate the influence of the installation error in the raw data of the ballbar measurement. Finally,based on the identification results of the position dependent geometric errors of the turntable,the change in the length of the ballbar in the additional experiment is predicted,and compared with the experimental results,the prediction accuracy is high. On this basis,the position dependent geometric error of the turntable is compensated. It is show that after compensation,the accuracy is significantly improved compared with that before compensation. The experimental results show that the method can accurately and quickly identify the position dependent geometric error terms of the turntable,which has important significance for improving the accuracy of the machine tool.