A method for generating clean-up toolpath of multi-patch solid model based on point-searching

Traditional methods for generating clean-up toolpath are based on STL models or surface offset methods. We present the point-searching method which adopts the integral multi-patch solid model to generate pencil-cut and fillet-cut clean-up toolpath. For pencil-cut with ball-end cutter, the distance between the ball-end center and the solid model equals to the distance between the ball-end center and the part surface. The point that satisfies the distance requirement is on the cutter center curve. While searching points on the cutter center curve, initial points are selected on the part surface and converted into the parameter domain. Search center and search direction are then determined according to the initial points. Search operation is then carried out to search every point that satisfies the distance requirement, and the cutter center curve can be generated with the searched points. Given tool orientation for each point on the curve, cutter location (CL) can be found at the tool-tip along tool orientation. As for fillet-cut, we use different sizes of ball-end cutters to generate a set of cutter center curves. For each point on the curves, two cutter-contact (CC) points and two CL points of the selected ball-end cutter can be obtained. All the CL points form the fillet-cut toolpath. Within the point-searching method, the multi-patch model is considered as a whole one, no single surface on the solid model is taken out for special consideration, surface offset and intersections can be avoided and the searching process is steady. Computer implementation and practical examples are also presented in this paper. The results show that the proposed method is feasible and efficient.