| 摘要 |
PURPOSE:To harden both tooth surfaces surely by cooling one tooth surface with liquid nitrogen in the stage of rotating a gear and hardening one tooth surface by laser light then rotating the gear reverse and hardening the other tooth surface. CONSTITUTION:A light absorptive layer 2 which is easy to absorb laser light, such as a graphite film, is formed on the part of a gear 1 to be heat treated. On the other hand, the laser light L outputted from a laser oscillator 6 is reflected by a reflecting mirror 7 for transmission, and is reflected and condensed with a scanner mirror 8. The condensed light is reflected by an angle changing mirror 9 so as to arrive at the gear 1. The angle of the mirror 9 is so adjusted that the linear laser light L irradiates one tooth surface 3a of a tooth 3, then the gear 1 is rotated in an arrow (a) direction. The angle of the mirror 9 is changed upon ending of the hardening of the surface 3 so as to irradiate the surface 3b with the laser light L of a chain line, then the gear 1 is rotated reverse. Liquid nitrogen is injected from a nozzle 12 onto the surface 3a to prevent the tempering of the surface 3a. |
