Tool trajectory planning with inter-path consistency of feedrate for freeform surface machining

Abstract

For CNC machining of freeform surfaces, inter-path inconsistency of feedrate for tool trajectories can lead to surface defects such as overcutting, undercutting, and uneven tool marks, significantly affecting the surface quality of workpieces. However, existing tool trajectory planning methods typically focus only on motion planning for a single toolpath in the feed direction while neglecting the toolpath reference information in the cross-feed direction, which limits the potential improvement in machining quality. To address this issue, a tool trajectory planning method with inter-path consistency of feedrate is proposed in this paper, which includes an inter-path mapping and consistent redistribution algorithm for tool position points, as well as a feedrate planning algorithm based on interpolation between sub-toolpaths. By referring to the position and feedrate information of adjacent sub-toolpaths, the proposed method can achieve a more uniform feedrate distribution in the cross-feed direction. Additionally, to evaluate the effectiveness of the proposed method in optimizing inter-path consistency of feedrate, two evaluation indicators, inter-path feedrate distribution cosine similarity and feedrate gradient in cross-feed direction, are introduced. Simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method, showing that it can significantly improve inter-path consistency of feedrate compared to conventional methods, and finally enhance surface quality and machining efficiency.