A global toolpath smoothing for micro-line toolpath based on edge error estimation and regional optimization

Abstract

In CNC machining, micro-line toolpaths are widely used for machining parts with free-form surfaces, which are usually fitted to smooth curves to enhance machining efficiency and quality. This paper presents a global toolpath smoothing method based on a novel edge error estimation and regional control points optimization. Firstly, some dominant points are selected according to cubic polynomial fitting error. Subsequently, an initial NURBS curve is generated iteratively. During each iteration, new dominant points are added, and the parameters of the tool tip points are updated. Finally, an edge error estimation method for NURBS curves is proposed and integrated into a regional optimization scheme to generate the resultant NURBS curve under geometric deviation constraints. Simulation and experiment results demonstrate that the proposed method can reduce the number of control points and curvature extreme of the resultant NURBS curve compared with the reference method. Furthermore, our method streamlines the interpolation process, resulting in time savings ranging from 10.66 % to 17.30 %, all the while adhering to the same geometric and kinematic constraints. The method offers an efficient solution for micro-line toolpath interpolation in CNC machining, improving the machining efficiency.