Quality and Process Control of Nd: YAG - Laser Welding Using fuzzy Pattern Recognition Techniques for Multisensor Systems
Quality monitoring is necessary for a stable manufacturing, especially in the case of laser welding processes. During the project a system was developed which allows the analysis of in process data by fuzzy pattern recognition methods. This resulted in improved prediction of seam irregularities as compared with conventional methods. The work was carried out in the framework of the MAINE cooperative project funded by the Free State of Saxony.
Pulsed laser weld quality monitoring by the statistical analysis of reflected light
This paper describes a technique for monitoring the quality of laser welds by statistical analysis of the reflected light signal from the weld surface. An algorithm is used which analyses the variance of the peak values of the reflected signal as a measure of surface weld dynamics during pulsed Nd:YAG laser welding in the heat conduction mode. Kalman filtering is used to separate a useful signal from the background noise. A good correlation between weld disruption and signal fluctuation has been identified. This technique could be used in tandem with the present practice of simply using the peak values of the reflected (or emitted) light as an indicator of weld quality.
Akzeleratorunterstützte Fuzzy-Klassifikation zur Echtzeit-Prozeßüberwachung
Die Uberwachung von Prozessen, fur die kein vollstandiges exaktes mathematisches Modell verfugbar ist, kann unter Verwendung eines Grobmodells mittels Fuzzy-Klassifikation erfolgen. Grundlage dafur sind geeignete Merkmale, die direkt oder indirekt Informationen uber den interessierenden Prozeszustand enthalten. Durch die Benutzung von fuzzy sets konnen Unsicherheiten in der Modellstruktur und in den auszuwertenden Messignalen berucksichtigt werden. Fur einen Einsatz in der Echtzeituberwachung wird ein Akzeleratorsystem auf der Basis programmierbarer Gate Arrays vorgestellt, mit dem eine zeitkritische Anwendung eines online-Beratungssystems ermoglicht wird. Anwendungsgebiete und Einsatzfalle werden kurz dargestellt.