ENHANCEMENT OF SUS304 PENETRATION BY IRRADIATION WITH PULSE EXCITED YAG LASER-BEAM TOGETHER WITH 2 RECTANGULARLY MODULATED CW YAG LASER-BEAMS

A pulse-excited YAG laser beam and two rectangularly modulated CW YAG laser beams transmitted through optical fibres were collimated and con densed to a focal point by combining optics developed to increase lase r power for materials processing. We found that the cross sectional sh ape of SUS304 penetration is strongly dependent on the delay time betw een incidence of the pulse-excited YAG laser beam and that of the rect angularly modulated CW ones. We obtained a deep penetration welding wi th half the power density of simultaneous irradiation with both types of laser beam using the combining optics, when we irradiate with the p ulse-excited YAG laser beam just after a keyhole has been formed by th e previous irradiation with CW YAG laser beams.