Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Process monitoring and process control at laser beam welding by means of nonlinear dynamics



Datum: 22.02.2002


Author


Reporter

  • Prof. Dr.-Ing. M. Geiger
  • Prof. Dr.-Ing. B. Scholz-Reiter, TU Cottbus

Process monitoring and control systems can support the efficient qualification of new laser welding applications. However, the development of corresponding systems is complicated by an insufficient knowledge of the mutual interactions of different physical subsystems that are involved in the laser welding process. The interactions of these physical subsystems are explained for a stationary process model. In addition, the influences of fundamental process parameter on the laser welding dynamics are investigated in real experiments. Process signal analysis show that the area of deep penetration welding is characterised by a high dynamical process complexity which supports the formation of process pores. Therefore, in order to stabilise the welding process the so called resonant stimulation, a process control known from nonlinear dynamics, is qualified for the laser welding process. A systematic approach for the determination of suitable control parameter that enable an improvement of the weld seam quality is suggested. However, the machining results also demonstrate that resonance catastrophes can be induced if resonant stimulation is applied to the welding process. In order to overcome these drawbacks the frequency modulated resonant stimulation is introduced which yields an additional improvement of the machining results./