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Modeling and simulation of process monitoring and control in laser cutting

 
: Schulz, W.; Kostrykin, V.; Michel, J.; Niessen, M.

Radons, G.; Neugebauer, Reimund:
Nonlinear dynamics of production systems
Weinheim: Wiley-VCH, 2004
ISBN: 3-527-40430-9
S.411-426
International Symposium on Investigations of Non-Linear Dynamic Effects in Production Systems <4, 2003, Chemnitz>
Englisch
Konferenzbeitrag
Fraunhofer ILT ()

Abstract
Laser cutting at moderate conditions is well established in industries. Both, high cutting speed for efficient machining and low cutting speed during contour cutting change the dynamical properties of the process which are related to quality features of the cut. To guarantee the product quality of laser processing the industry tries to introduce monitoring and control systems. Understanding becomes crucial to develop robust and reliable laser processes and machines. The laser beam fusion cutting process is a Free Boundary Problem for the motion of two phase boundaries. In the long time limit of such dissipative dynamical systems a reduction of the dimension in phase space occurs. The degrees of freedom are identified by methods of singular perturbation theory and integral methods are applied to derive the equations of motion. Applying spectral methods the solution can be calculated with arbitrary accuracy. As result, two mechanisms for the formation of adherent dross are revealed theoretically, identified by the monitoring system and can be avoided by modulation of the laser beam power. The onset of evaporation and the increase of capillary forces are the two physical phenomena relevant for the build-up of adherent dross. The dynamic model predicts a modulation frequency for the laser power that leads to almost complete suppression of adherent dross in contour cutting.

: http://publica.fraunhofer.de/dokumente/N-23450.html