PROCESSING METHOD FOR LASER WELDING IN PIPE AND LASER WELDING HEAD

摘要

PURPOSE: To prevent the reserving of oxidized molten metal in a welding region by feeding a first protective gas through a laser welding head to a welding region in a tube and feeding a second gas through between the periphery of the laser beam welding head and the tube to the welding region. CONSTITUTION: The flow of the first protective gas is introduced on the inner side of an optical path and emerges outside from an injection window 5 along an arrow f1 direction. The first gas contains trace amts. of active gases, such as oxygen and hydrogen, in an inert as, such as argon, helium or nitrogen and protects the oxidized molten metal reservoir. The second gas flows axially from the point on the upstream side of the welding region and is run between the welding head 1 and a sleeve 2 at intervals of once a year toward an arrow f2 direction. The second gas is similarly the inert gas contg. the trace amt. of the active gas and inactivates the metallic particles evaporating from the surface of the oxidized molten metal reservoir. More preferably the gas protects the welding head 1 against the splashes from the oxidized molten metal reservoir.