A G3 Continuous Tool Path Correction and Smoothing Method for CNC Machining

The toolpath in Computer Numerical Control (CNC) machining program is commonly composed of small line segments and fed to CNC machining centers to control the machining process. The connection points of the toolpath only have G
⁰
continuity, resulting in discontinuity of velocity, acceleration and jerk in the machining process which leads to varying cutting load and leaves marks on the surface of the workpiece. This paper presents a tool path smoothing method by enforcing the G
³
continuity of the smoothed toolpath. The command points retrieved from the CNC machining program are first corrected by fitted B splines while constraining the tool path error within tolerance. Then the corrected command points are smoothed by the Bezier spline corner transition method. Simulations and experiments demonstrate that the proposed G
³
continuous tool path correction and smoothing method generates a smoother toolpath, reduces the tracking error and contour error, leading to more accurate machining of the workpiece.