DEVELOPMENT OF MULTI-DETECTOR SYSTEMSFOR THE PROCESS MONITORING OF LASER BEAM WELDING CAPABLE FOR INDUSTRIAL USE

摘要

The increasing industrial use of lasers for material treatment induces a growing amount ofrnquestions due to fulfilling quality specifications given by the installed quality managementrnsystems. They have to be answered for a successful application of the laser as a productionrntool.rnDifferent single detector approaches for process monitoring systems have partly beenrnevaluated with success in industrial use. Nevertheless, the bandwidth of probabilities for therndetection of different individual welding defects is very narrow for single process monitoringrnsolutions. In general, such a system often is able to detect only a low variety of differentrndefects. Due to that, complex applications with a large number of different origins of defectsrncan not be monitored adequately by single detector systems. The combination of severalrnstand-alone systems is not favourable due to high cost and low integration level.rnTo solve these problems, the use of a multi detector system is a promising approach. At thernForschungsgesellschaft für Strahlwerkzeuge (FGSW) a multi detector system for processrnmonitoring has been developed that integrates discrete photo diode based sensors and arnCMOS camera. The discrete sensors are used for the monitoring of laser back reflection fromrnthe keyhole and the thermal emission of the weld zone. The camera based system follows thernapproach of spatially resolved measurements with additional information. The integration ofrnboth these approaches leads to a process monitoring system which is capable of thernmonitoring of a broad bandwidth of defects originating from different causes. The knowledgernand experience so far gained has entered the development and realization of a multi detectorrnsystem in the BMBF-funded project INESS.