Model Of Dynamic Behaviour In Laser Beam Welding

Processes like plasma development and quenching modulation of the evaporation rate, pressure variation, energy coupling or melt transport and their interdependence determine the welding process. The investigation of these processes with optical and acoustical methods is presented. When measuring the radiation of the luminous phenomenon in different wavelenght ranges, the transition from metal vapour to laser-induced plasma and vice versa as well as plasma density fluctuations in the keyhole are shown. This result is supported by measuring the pressure variations in the enviroment with a microphone. The case of full penetration welding is particularly investigated. In this case the luminous phenomenon below the workpiece and the CO2 radiation, transmitted through the keyhole is measured additionally. All these investigations result in a presented model. The model shows that the variation of the metal vapour density mainly determines the above-mentioned processes like energy coupling, pressure variations and so on, and therefore has a great influence on laser beam welding.