Tool path generation for contour parallel milling with incomplete mesh model

Abstract

In this paper, a tool path generation method for contour parallel milling based on an incomplete two-manifold mesh model, namely, an inexact polyhedron which is widely used in recent commercialized computer-aided manufacturing software systems is presented. The method consists of three major steps: machining area detection, 2D offset, and path linking. Machining areas obtained from a mesh model are closed 2D lines. Thus, offsetting closed lines is essential to generate mesh-based contour parallel tool path. For contour parallel path elements, a new offset algorithm for closed 2D lines with islands is introduced and the result is illustrated. The main point of the proposed algorithm is that every point is set to be an offset using bisectors, and then invalid offset lines, which are not to be participated in offsets, are detected in advance and handled with an invalid offset edge handling algorithm in order to generate raw offset lines without local invalid loops. As a result, the proposed offset method is proved to be robust and simple, moreover, has a near O(n) time complexity, where n denotes the number of input lines. The proposed algorithm has been implemented and tested with 2D lines of various shapes. Finally, contour parallel path is made through linking offset path elements.