| Summary: | 碩士 === 國立臺北科技大學 === 製造科技研究所 === 99 === Surface cutting with spiral tool paths can save the machining time and take a streamline appearance of the part. Most of the spiral tool path planning does not take into account whether the residual scallop material on the machined surface is uniform or not. In this paper, two spiral tool path planning methods with constant-scallop height were been studied for rotational swept surface and general rectangular surface machining respectively. First, in the rotational swept surface, divide the control curve (the curve to generate the swept surface by sweeping) into several intervals based on the tolerance of the residual scallop height. Each interval is just the pitch of the spiral tool paths. Second, divide each arc length interval into some suitable partition points which determine the number of tool cutting points in one revolution on the swept surface. Finally, all the cutting points on the spiral tool paths can be calculated by applying the parametric equation of rotational swept surface. In the general rectangular surface, we develop a rectangular spiral tool paths pattern which machines the part surface from periphery to the inner centre successively. The generation of this tool paths pattern need two steps. To begin with, two set of Zig-type tool paths on the surface in cross directions must be computed with constant-scallop height path interval. Then, make a rearrangement for all the computed tool paths to generate rectangular spiral paths in a proper sequence. In this paper, a Matlab program was constructed for executing present algorithm. Some examples, including rotational swept surface and rectangular surface for spiral tool paths planning, were performed. The planned spiral tool paths also simulated in CAD/CAM system and machined on a CNC 5-axis machining center for demonstrating the validity of the proposed method. The results reveal that the proposed method is valuable.
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