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標題: 含NURBS曲線之車床刀具路徑產生
Tool Path Generation with NURBS Curves for Lathe
作者: 邱成豪
Chou, Cheng Hao
關鍵字: lathe;車床;tool path generation;NURBS curve;Bezier curve;offset;刀具路徑規劃;NURBS曲線;Bezier曲線;偏置
出版社: 機械工程學系

The purpose of this thesis is to develop a CAD/CAM system for lathe machining. Users can design the geometry of a workpiece by elements which include types of lines, arcs and freeform curves(Bezier, B-Spline and NURBS curves). After offsetting the designed contour, efficient tool paths for rough cut and finish cut can be generated to lathe machining, the designed workpiece contour satisfying the precision requirement without gauging.
As to the contour offsetting, interference index method is applied to solve the self-intersecting loop interference problems for freeform curves. The convex hull property of Bezier curves and the idea of accumulative position errors are used to obtain offset curves by decomposing freeform curves into piecewise Bezier curves. After correct offset curves have being obtained, tool paths are generated by proper path generation methods according contour shape characteristics.
In most commercial CAD/CAM softwares, three commonly used procedures are include in the path generation method: repetitive turning cycle(G71), repetitive facing cycle(G72) and pattern repetitive cycle(G73). In order to avoid undercutting in rough cut, proper combination of procedures for path generation are chosen according to the contour characteristics of the designed workpiece. This system provides two lathe machining cycle procedures(G71 and G72) to produce secure zone in machining, such that an accurate and intact designed workpiece can be lathe machined.
Keyword: lathe, tool path generation, NURBS curve, Bezier curve, offset.
Appears in Collections:機械工程學系所

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