Laser hardening device

Abstract

A laser hardening device for forming a hardened layer on the surface of an object irradiated by a laser beam is so arranged as to emit a laser beam which is linearly polarized in the incidence plane containing the normal to the surface and the optic axis of the laser beam irradiating the surface. The device comprises a first concave mirror for condensing the laser beam the incidence plane, and a second concave mirror for condensing the laser beam in a perpendicular plane to the incidence plane, the first concave mirror being disposed closer than the second concave mirror to the laser oscillator in the path of the laser beam. Laser beam is therefore absorbed at a high absorption rate by the object, and a hardened layer is formed without coating a laser absorption agent onto the object. The incidence angle of the laser is preferably no less than 60 degrees, and by arranging that the laser beam is parallel on the irradiated surface, a uniform, hardened layer is obtained. Moreover, by blowing shield gas on the irradiated surface from a gas nozzle provided with a smoothing mechanism such as metal mesh, oxidation of the hardened layer or surface melting due to oxidation is prevented and a more desirable hardened surface is obtained.

Dependencies are inferred from the claim text.