Product Code: ICAL06_706

Self Guided Laser Welding
Authors:
Boris Regaard, Fraunhofer Institute for Laser Technology; Aachen Germany
Reinhart Poprawe, Fraunhofer Institute for Laser Technology; Aachen Germany
Stefan Kaierle, Fraunhofer Institute for Laser Technology; Aachen Germany
Presented at ICALEO 2006

High flexibility and consistent quality are key benefits of laser welding in production. However, little jitter of welding trajectory and velocity are required; e.g. in butt welding the focal point of the laser beam with respect to the joint must be maintained with accuracy better than 50 - 100 microns, depending on the focused beam radius. To meet these requirements, seam tracking devices are used. A sensor measures the joint position, usually 5 to 20 mm ahead of the welding position (TCP - Tool Center Point). The Seam Tracking control communicates with the robot to maintain the momentary TCP position and send the correction trajectory. This way, deviation of the joint position can be corrected. However, the robot still needs to meet accuracy restrictions since the seam tracking control has to receive accurate on-line information about the TCP position. This paper introduces an enhanced tracking sensor concept, where both the ahead joint position and the relative velocity between the welding head and the workpiece - and therefore the relative TCP position - are measured by one camera based sensor. By carrying out the laser beam correction with a robot-independent scanner system, seam tracking can be performed completely independent to the handling. This reduces cost in robot systems due to lower accuracy and output requirements, simplifies interfacing and installation and disengages from sensor teaching necessity.