From cross-section to scanning path in rapid prototyping

This paper introduces some key technologies in laser path generation including contour scanning path and internal scanning path for stereolithography. To generate the contour scanning path the cross-sectional contours must be offset a distance inward solid area in the course of machining parts because of the size of laser light spot. A simple calculating method of offset contours and a modified algorithm of detecting self-intersection points are presented. To generate the internal scanning path an algorithm of sub-regional scanning path generation is presented. The algorithm divides complex sectional contours into some simple non-hole sub-region, the scanning path in every sub-region is continuous and the sub-regions are scanned in turn. At the same while, the scanning path is optimized in two ways. The first one is that the joining path between the regions is optimized, which is effective on decreasing the vacant path. The second one is that the scanning path out of place at extreme points in a sub-region is optimized. The experiment shows the proposed algorithm not only improve the machine equality but also advancing the machine efficiency