ON-LINE CONTROL AND QUALITY IMPROVEMENT OF LASER-BEAM WELDING BY HIGH-DYNAMIC CMOS CAMERAS – A MAJOR STEP IN MANUFACTURING QUALITY

摘要

Laser welding systems are part of production systems with the target of advancedrnmanufacturing quality. Advantages are improved efficiency by higher feed rates as well asrnmore flexibility in the choice of materials and forming. The automotive industry offers thernlatest challenges in terms of productivity and cost-cutting.rnIn this paper we will describe two different applications of CMOS cameras to the weldingrnprocess, both with the target of improved quality, higher feed rates and less standstill time ofrnthe welding system.rnIn the first application, the in-process laser welding control, a CMOS cameras has beenrnintegrated into the Nd-YAG-laser head of a production system. Based on the fast in-siturnimaging of the laser melt spot, an evaluation signal is provided into a control system. Thisrnsignal is monitored and has to be kept in certain limits.rnFurthermore, a CMOS is camera is integrated in the second application for a post-processrnquality control of a laser weld. The image system is able to differentiate between the unmachinedrnpart of the workpiece material and the welded area. A combination of 2 differentrntechniques, 2-D surface grey-level analysis and 3-D triangulation, provides a major step inrnoff-line quality control of laser welds.