LASER BEAM GAS CUTTING METHOD

PURPOSE:To easily cut thick-wall material by condensing a laser beam on material to be machined by a conical type mirror and a concave mirror and injecting high-pressure assisting gas from the laser beam central part with a laser beam gas cutting device. CONSTITUTION:In a machining head 7 of the laser beam gas cutting device 7, the laser beam 4 is reflected by the conical type mirror 12 of a cassegrainian optical system made of Mo, etc., through a lens 15 made of ZnSe provided to the center of a pressure diaphragm 14 and reflected and condensed by the concave mirror 13 with an open hole in the center and a focus is formed on the tip of the machining head 7. On the other hand, low-pressure assisting gas 9 such as O2 and N2 is supplied from the central part of the machining head 7 and the high-pressure assisting gas 18 with 10-20kgf/cm is supplied to a high-pressure nozzle 16 in the machining head 7 and the high-speed assisting gas flow 19 is surrounded and injected by the low-speed assisting gas flow 20 from a low-speed nozzle 8. Even the thick-wall metal material, etc., can be easily cut by the above-mentioned high output laser beam and injection of the high-pressure assisting gas.