为了提高大型复杂型体件加工用龙门式双摆头五轴机床的加工精度,用激光跟踪仪对五轴机床两个旋转轴准静态误差以及旋转轴中心轴线与三个直线轴间垂直度误差进行了辨识测量。基于刚体运动学原理和齐次变换矩阵方法建立了包含旋转轴准静态误差和旋转轴中心轴线与三个直线轴间垂直度误差的误差模型;用激光跟踪仪测出旋转轴循圆运动到不同角度位置时其端面上点的空间坐标,由此建立旋转轴误差方程组,求出旋转轴各项误差值。对循圆轨迹进行拟合得到圆心坐标,进而得到旋转轴中心轴线方程,求出旋转轴中心轴线与直线轴间的垂直度误差值。将旋转轴各项误差值代人误差补偿模型中,通过圆锥台误差补偿前后加工实验结果对比,表明所采用的旋转轴误差测量方法可以有效提高五轴机床的加工精度。
In order to improve the large-scale curved surface parts machining accuracy of five axis machine tool, a new method using laser tracker to identify quasi-static errors of rotary axis is proposed and a compensation experiment is also implemented, the error model of rotary axis is established based on the rigid body kinematics and at the same time the errors of perpendicularity between the rotation axis and linear axis are also given. Different circle paths are designed in different planes and spatial coordinates of four positions are measured. Some equations including all the error components of rotation axis are established and the error components can be obtained by solving the equations. The perpendicularity errors between the rotation axis and linear axis are obtained through the relationship with the fitting center of two following circle and linear axis. The proposed method is applied to a double swivel head spindle five axis machine tool for error measurement and compensation. Experimental results show that this method is quite convenient and effective.