(1997)
Publication Type: Thesis
Publication year: 1997
Publisher: Meisenbach
Edited Volumes: Fertigungstechnik - Erlangen 65
The aim of the thesis was the understanding of the transient processes that lead to welding failures at the beginning and end of the laser beam welding process, during the machining of contour elements or even during quasi stationary phases. This was the basis for the development of improved processing strategies that lead to optimized machining results. Basically two different kinds of transient processes have been separated. Extrinsic transient processes occur, if processing parameters change during the machining. Intrinsic transient are caused by the inherent dynamics of the welding process itself and can be observed during the whole welding process. An identification of the reasons for machining failures caused by extrinsic transient processes was possible by means of a correlation between the machining parameters, process emissions and the machining result in combination with FEM simulations of the thermo-mechanical processes during laser beam welding. So it was possible to develop machining strategies to avoid these machining failures.
To characterize and to deal with intrinsic transient processes new methods have been introduced, that base on the theory of nonlinear dynamic systems. For example it was possible to minimize process fluctuations by means of a resonant stimulation of the welding process, so that machining results were improved considerably.