基于球杆仪位姿的机床回转台几何误差辨识研究

摘要

In order to decouple the coupling errors caused by the linkage of moving axis when measuring the geometric errors of the rotary axis,this paper proposed a new method of error identification based on the actual position of the Double Ball-bar(DBB).With the rotary table of a CFXYZA type of five-axis CNC machine tool as the measuring object,a combined measurement model was designed to measure the directions of X,Y,and Z of the DBB.Six groups of ball-bar's length variations were obtained by changing the installation position and height of DBB's center base on the rotary table;and then,the relational expression of the geometric errors and the length variations was deduced based on the homogeneous transformation theory,thus six geometric errors of the rotary table were identified.The measurement test and the identification results showed that the proposed method could not only improve the identification accuracy,but also eliminate the coupling errors of the moving axis,which is of reference significance for the geometric error measurement and identification of the the same type of CNC machine tools.%针对误差测量中由移动轴联动引起的旋转轴与移动轴误差耦合现象,提出一种基于球杆仪实际位姿的误差辨识方法.以CFXYZA型五轴数控机床的回转台为测量对象,设计了球杆仪X向,Y向及Z向组合测量模式,通过改变球杆仪中心座的安装位置和高度,共测得6组杆长变化数据,再利用齐次变换理论推导几何误差参数与杆长变化量的关系式,以辨识出回转台6项几何误差.测量试验和辨识结果表明,使用该法不仅提高了辨识精度,而且可消除测量过程中耦合的移动轴误差,对同类型机床回转台的几何误差测量、辨识均具有参考意义.