Application of process monitoring and quality control of laser-welded blanks using an integrated multiple-sensors approach

To reach the goals of volume, quality and cost, the tailored blank industry requires inline process monitoring and quality control. For that purpose, many sensors have been developed and tested, with mitigated results. These sensors examine the signature of the welding process or the characteristics of the weld bead. These sensors highlight useful information, however, none of them can screen all possible weld defects and they are difficult to adjust in a factory environment. This paper shows that by merging data from several dedicated sensors into one system, weld defects can be detected with the required degree of confidence. An integrated multiple-sensors approach enables reliable in-line process monitoring and quality control. At the heart of the system lies a powerful real-time process monitoring and control system that acquires and processes data from several sources and merges them to evaluate weld quality. The sensors include a high-speed, high-resolution laser profiler that measures the geometric profile of the weld bead. A telemetric laser sensor that detects minute defects such as porosity or drops, and a light analyser that evaluates the status of the plasma, can easily be integrated into the system.