Tool path error prediction of a five-axis machine tool with geometric errors

Abstract Predicting the actual tool path of a machine tool prior to machining a part provides useful data in order to ensure or improve the dimensional accuracy of the part. The actual tool path can be estimated by accounting for the effect of the machine tool geometric error parameters. In computer aided design/computer aided manufacture (CAD/CAM) systems, the nominal tool path [or CL (cutter location) data] is directly generated from the curves and surfaces to be machined and the errors of the machine tool are not considered. In order to take these errors into consideration, they must first be identified and then used in the machine tool forward kinematic model. In this paper a method is presented to identify the geometric errors of machine tools and predict their effect on the tool-tip position. Both the link errors (position-independent geometric error parameters) and the motion errors (position-dependent geometric error parameters) are considered. The nominal and predicted tool paths are compared and an assessment is made of the resulting surfaces with respect to the desired part profile tolerance. A methodology is also suggested to integrate this tool within a CAD/CAPP (computer aided process planning)/CAM environment.

摘要 在加工零件之前预测机床的实际刀具路径可提供有用的数据，以确保或提高零件的尺寸精度。通过考虑机床几何误差参数的影响，可以估算实际刀具路径。在计算机辅助设计/计算机辅助制造（CAD/CAM）系统中，名义刀具路径[或CL（刀具位置）数据]是直接由要加工的曲线和曲面生成的，机床的误差未被考虑。为了考虑这些误差，必须首先识别它们，然后将其用于机床正向运动学模型。本文提出了一种识别机床几何误差并预测其对刀尖位置影响的方法。同时考虑了连杆误差（与位置无关的几何误差参数）和运动误差（与位置有关的几何误差参数）。对名义刀具路径和预测刀具路径进行了比较，并根据所需的零件轮廓公差对所得表面进行了评估。还提出了一种将此工具集成到CAD/CAPP（计算机辅助工艺规划）/CAM环境中的方法。