Rough cut tool path planning for B-spline surfaces using convex hull boxes

摘要

The objective of this paper is to present a non-uniform layered rough cut plan for B-spline surfacesusing convex hull boxes. The tool path plan generated by this method will rapidly remove mostredundant material from stock material without overcutting. First, a B-spline surface is decomposed into piecewise Bezier surfaces, of which the convex hullboxes form an approximate model for rough cutting. Then, according to the top planes of thoseconvex hull boxes, the stock material is divided into layers of different thickness. The cavity contourfor each layer is obtained using a simplified union Boolean operation on convex hull boxes. Finally,from the top down, each layer is processed like a 2D pocket die cavity. The algorithm is implemented on a personal computer. It is shown that the rough cut plan is veryefficient since no computation for solving nonlinear equations is needed, and no overcutting occurssince B-spline surfaces are protected by the convex hull property of Bezier surfaces.