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UBC Theses and Dissertations
Generating efficient milling tool paths according to a preferred feed direction field Kumazawa, Guillermo Hiroki
A new method is presented to generate ball-end milling tool paths for the efficient three-axis machining of sculptured surfaces. The fundamental principle of the presented method is to generate the tool paths according to a preferred feed direction (PFD) field derived from the surface to be machined. In this work, the PFD at any point on the surface is the feed direction that maximizes the machining strip width. Theoretically, tool paths that always follow the direction of maximum machining strip width at each cutter contact point on the surface would maximize material removal, which leads to the shortest overall tool path length. Scallops are generated when a surface is machined using three-axis ball-end mills. There is no redundant machining if the scallop height is always maximized and the neighboring machining strips do not overlap. Unfortunately, these overlaps commonly exist for tool paths always following the preferred directions. Such redundant machining can be reduced via iso-scallop tool paths. Nonetheless, iso-scallop tool paths do not in general follow the preferred feed directions. To attain maximum machining efficiency via generating the shortest overall tool path length, the presented method analyzes the PFD field of the surface and segments the surface into distinct regions with similar PFD's by identifying the degenerate points and generating their separatrices. The tool paths of each region are generated by the iso-scallop method to mitigate redundant machining. Since a sequential approach is employed to generate the iso-scallop tool paths, an initial tool path is selected in such a way that the growing deviations of the subsequent tool paths from the PFD's are not significant. The proposed method has been validated with numerous case studies, showing that the generated tool paths have a shorter overall length compared with those generated by the existing methods.
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Attribution-NonCommercial-NoDerivatives 4.0 International