HARDENING METHOD BY LASER WORKING AND DEVICE THEREFOR

PURPOSE:To execute simultaneously cutting and hardening of a steel material in the stage of cutting a thick steel material by laser cutting by providing an annular ejecting port for cooling water around the laser irradiating port of a laser nozzle. CONSTITUTION:An assist gas is first introduced from a gas inlet 9 into a laser nozzle 12 and is ejected from the irradiating port 14 of said nozzle in the stage of cutting a thick steel material 16 to be worked by laser working. A laser oscillator is then oscillated and the laser beam is focused by a focusing lens 8 and is irradiated on a steel plate 16 from the port 14, by which the steel material is cut. Cooling water is supplied at the same time from an inlet 17 and is ejected from the annular ejecting port 15 for cooling water of the nozzle 12. The cut surface which is melt-cut by the laser beam and is heated up to a high temp. is quickly cooled by the cooling water, by which the hardening treatment substantially free from distortion by cutting and heat is made possible.