Abstract: The corners on the toolpath lead to discontinuous tool motion of the machine tools during high-precision Computer Numerical Control（CNC）machining,especially in the finish machining process,resulting in varying cutting load which leaves tool deflection marks on the workpiece surface,hence reducing machining quality.To solve this problem,a G3 continuous tool path smoothing algorithm was proposed.The linear tool path was first divided into different non-fitting or fitting regions.Then,a corner transition model with optimized curvature was constructed based on B-spline for the non-fitting region to generate G3 continuous toolpath.For the toolpath in the fitting regions,the toolpath was fitted by B-spline and the G3 continuity of tool path at the connection points of consecutive non-fitting and the fitting regions was regarded as the fitting constraint.The proposed algorithm was demonstrated with simulations and experiments in following a tool path on a CNC machine tool.It was shown that the proposed G3 continuous tool path generation algorithm gave G3 continuous tool path,and reduced the tracking errors and contour errors,leading to better machining quality.

Key words: G3 continuous, B-spline, curvature, transition, fitting

摘要： 在高精度数控加工尤其是高精度数控精加工过程中,小线段描述的数控加工刀具路径上存在的拐角,导致加工过程中机床的运动不连续,产生的不均匀刀具负载会引起刀具抖动,进而在工件表面留下刀痕,降低加工质量。为了提高加工质量,提出了一种G3连续的数控加工刀具路径平滑算法。算法首先将刀具路径划分为拟合区域与非拟合区域,然后基于B样条曲线建立曲率优化的拐角平滑过渡模型,并对非拟合区域中的刀具路径进行平滑处理。对于拟合区域中的刀具路径,算法以拟合区域、非拟合区域连接点处保持G3连续为约束条件,对刀具路径进行拟合处理。仿真和实验表明本文提出的算法能够产生G3连续的平滑刀具路径,减少追踪误差、轮廓误差,提高加工质量。

关键词: G3连续, B样条, 曲率, 过渡, 拟合