Executing Organisation: Project Management Agency Karlsruhe (PTKA) | Federal Ministry of Education and Research (BMBF)
The joining process of laser transmission welding is highly dependent on temporal preceding manufacturing processes. To secure process stability and product quality the usage of process monitoring and control systems is consequently indispensable. Currently used monitoring processes like pyrometer or melt travel control do not allow adequate reliable and space-resolved statements about local existing failures. A promising alternative to these methods is the optical coherence tomography (OCT), which is a contactless imaging process based on the principle of interferometry.
The main project objective is the development of an adaptive laser transmission welding process controlled by inline optical tomography. This approach enables the acquisition of quantitative information of the weld forming process as detection of weld geometry, pores and leakages as well as joining gaps. Based on neural networks, this information shall then be processed and fed back to a control unit, which adapts process parameters in real-time.
The developed OCT system is very suitable for the identification of pores and weld defects in amorphous (PC) and semi-crystalline (PA6) materials after the welding process (right picture). At the moment a first prototype is built up, which combines the measuring beam of the OCT with the laser beam for the contactless inline characterization of the weld seam during the welding process (left picture).