Mixed tiny path smoothing method based on sliding convolution windows for CNC machining

Abstract

The machining toolpaths of complex free-form surface parts are generated using computer-aided manufacturing (CAM) systems and programmed by a series of mixed tiny paths composed of tiny lines, arcs, and non-uniform rational B-spline (NURBS). The mixed tiny paths need to be smoothed to eliminate the tangential discontinuities at corners. This paper proposes a mixed tiny path smoothing method based on sliding convolution windows (MSSCW). In this method, the mixed tiny path is firstly converted into a positional signal along the travel length in the spatial domain, and then sliding convolution windows, which centered on each original interpolation point, are used to generate high-order continuous smoothed toolpath. Finally, the smoothing error is checked and corrected by modifying the length duration of the sliding convolution windows. Compared with conventional path smoothing method, the MSSCW method is suitable for various computer numerical control (CNC) machining toolpaths, and the continuity of the smoothed toolpath can be adjusted according to user requirements. Consequently, the feasibility and effectiveness of the proposed method are validated in simulations and experimental results which realize the improvement of the machining quality of complex free-form surfaces.