考虑热误差的双转台机床工艺误差谱预测方法

五轴数控机床的几何误差和热误差是影响工件加工精度的两个重要因素,对这些误差因素进行分析可以有效提高薄壁件工件的加工精度。本文首先基于齐次坐标变换法,建立了双转台五轴数控机床的旋转轴几何误差模型;然后基于对标准球进行在机接触测量,辩识得出两旋转轴的12项几何误差,这些误差考虑了两旋转轴之间的相互影响和其热误差的影响;最后分析五轴数控机床加工空间的几何误差场,在该加工空间内几何误差从中心到外侧逐渐增加,当A轴旋转角度增加时,误差的最大值也随之增加。与其它位置误差辨识方法相比,本方法的测量精度符合加工要求,测量时间只需要30 min。

A prediction method of process error spectrum for double turntable machine tool considering thermal error

Geometric error and thermal error of the five-axis CNC machine tool are two important factors that affect the machining accuracy of workpiece. The analysis of these error factors can effectively improve the machining accuracy of thin-walled workpiece. Firstly, based on the homogeneous coordinate transformation method, the geometric error model of rotating axis of five-axis CNC machine tool with double turntable is formulated. Then, on the basis of standard ball, the machine contact measurement is carried out. Twelve geometric errors of the two rotating axles are identified. These errors consider the mutual influence between the two rotating axles and the influence of thermal error. Finally, the geometric error field in the machining space of five-axis CNC machine tool is analyzed. In this machining space, the geometric error gradually increases from the center to the outside. When the rotation angle of axle increases, the maximum error also increases. Compared with other position error identification methods, the measurement accuracy of the proposed method meets the processing requirements. The measurement time only needs 30 min.