An image-based "click&weld"-method for laser beam positioning in micro welding applications

In most laser welding applications the welding result is highly sensitive to the weld position and the initial determination of process parameters requires time-consuming adjustments to be made. In case of manufacturing individual parts with low quantities this is a significant cost driver. State-of-the-art CAD/CAM based manufacturing systems ease the creation of welding contours significantly but position deviations resulting, e.g., from workpiece tolerances or misplacements must still be compensated. Seam tracking systems are rather complicated to handle during process qualification as they require adjustment to a start position and are subject to be misguided by disturbances in the material. Besides, it is difficult to apply seam tracking to scanner-based micro welding operations. Therefore, we developed a system that enables the user to position welds easily and accurately by marking the intended weld position in a calibrated live-image of the workpiece, which is us ed as reference. Thereby, positioning errors are compensated. Because of the live image acquisition, it is also possible to observe the welding process and assess the geometrical properties of the weld surface immediately. Moreover, the paper describes how this idea is extended to a system for more complex weld contours and ends up with a system for image-based contour extraction.