A freeform surface finishing toolpath planning method based on dual-vector local excess-spacing dynamic detection

Abstract

Freeform surface finishing is central to aerospace, automotive, and precision equipment manufacturing, where toolpath plays a critical role in machining quality and efficiency control. Conventional iso-planar toolpath planning tends to result in three issues: depending on manually specified path spacing, producing excessive spacing in abrupt curvature regions, and increasing redundant cutting and non-cutting travel. To address these issues, this paper presents a freeform surface finishing toolpath planning method based on dual-vector local excess-spacing dynamic detection. The method first determines the basic path interval from a scallop-height constraint and generates base section curves according to the section-plane angle. A dual-vector detection mechanism is then leveraged to identify continuous excess-spacing interval regions, based on which interpolation curves are generated recursively until the spacing threshold is satisfied. Finally, an improved GA (genetic algorithm) utilizing a greedy initial population, endpoint-distance caching, adaptive mutation, elitism, and local search, is adopted to optimize the connection order of toolpath curves. Simulations and experimental studies validate the effectiveness and practicality of the proposed method. While maintaining the same machining quality, the proposed method achieves a higher machining efficiency (reductions of more than 40% both in total toolpath length and real machining time), compared to the conventional methods.