基于非均匀B样条拟合算法的加工误差测量

Machining error measurement based on non-uniform rational B-spline curve

数控机床加工零件,通常在零件加工后采用另外的仪器进行加工误差测量,重复装夹必然造成精度降低和工时延长。数控机床通过控制走刀路径使其按照特定轨迹运动,因此工件的加工误差可通过测量轨迹误差得到。文中运用非均匀B样条曲线拟合及曲线特征点提取的方法,将测量轨迹与理想轨迹进行拟合实现工件加工误差的在机测量。通过在数控机床上试验一直线圆弧样品加工验证了该方法的可行性。

The machining error was usually measured by other instruments after the parts processed completely during CNC machining, the repeating clamping inevitably led to reduced accuracy and longer working hours. Tool path travelled as specific trajectory was controlled by CNC machining tool, so the machining error can be obtained by measuring the trajectory error. In this paper, an on-line measurement method was developed to get machining error by fitting measured trajectory to desired trajectory, based on non-uniform rational B-spline （NURBS） curve fitting and curve feature point extraction. The feasibility was verified by a test of straight circular sample processing in CNC machine tool.