HEAD FOR HIGH OUTPUT LASER BEAM WELDING MACHINE

PURPOSE:To obtain a stable and homogeneous weld bead not affected by plasma and heat lens effect by adopting a nozzle part structure to pass assisting gas on an annular duct of the outside to be divided from a laser beam optical path. CONSTITUTION:A laser beam is converged by a concave mirror 1 of a condensing lens part, an optical path is changed in the nozzle opening direction by a reflection mirror 2, material to be welded is irradiated with the laser beam and the weld bead is formed on a weld zone. Simultaneously with this, gas supplied from an assisting gas supply port 3 is injected through the assisting gas duct part to be divided from the laser beam optical path part by a partition wall 5 and converged on the laser beam, by which generation of plasma on the weld zone is prevented effectively. Setting of a window on the welding head is obviated and even if continuous welding to use the high output laser beam is performed extending for a long time, the focal position and the depth of focus are not changed and further, power density at the bead focal position is not changed by adopting such structure.