CAD/CAM based generation of collision free robot programs through the integration of a virtual machining environment

Abstract

Robots employed in machining applications (e.g fettling of castings, deburring,...) are often programmed via a "teach-in" procedure. This is often not economical for the machining of small series and / or complex work pieces. The time needed for the "teach-in" programming is often much higher than the real production time. CAD/CAM programming as done for classical multi-axis NC-controlled milling operations is a potential solution to cope with small series. Based on the CAD model, the CAM-system generates a tool path, which is output as a CLDATA file (Cutter Location DATA) and in a next phase converted by a NC-postprocessor to a specific machine (robot) program. An important task of the postprocessor is the conversion from CLDATA to robot co-ordinates. Today the programming of such multi-axis machining operations is still a complex task. The risk for having collisions between moving machine (robot) components during operation is high and the consequences drastic. Within this paper, an innovative concept is proposed. A robot simulation system ("virtual machining environment") has tightly been integrated with the postprocessor. Each postprocessed position is directly checked for collision and if it occurs, a collision avoidance algorithm is applied. The developed programming concept has been demonstrated on two robot cells: one for the manufacturing of models for casting applications and one for the polishing of ship propeller blades.