Graphics-assisted cutter orientation correction for collision-free five-axis machining

Automated cutter orientation correction is very important for achieving collision-free five-axis NC machining, in particular to the machining situations with complex collisions, i.e. multiple-points colliding or fully engaged colliding. In the current paper, we present a novel approach to identify admissible tool orientations for collision avoidance in five-axis ball-end milling with complex machining environment. The proposed approach is built upon two techniques: graphics-assisted cubic mapping; and instantaneous visibility and accessibility cones computation. For each colliding cutter location (CL), the graphics-assisted cubic mapping algorithm computes the cutter's instantaneous visibility cone with respect to machining environment and the occlusion depth along each obstructed direction. With the given instantaneous visibility and occlusion depth information, an algorithm of spherical region shrinking is then developed to compute the cutter's accessibility cone, which represents the aggregate of all admissible directions of the cutter for current machining point. Therefore, a collision-free cutter orientation can be ensured by adjusting the cutter with the accessibility cone. The mapping computation is performed very efficiently by taking the advantage of rapid performance from graphics hardware. By employing instantaneous visibility and accessibility computation, the accuracy and robustness in handling complex collision situations is improved. Also the required computational memory usage is greatly reduced.