SURFACE HARDENING HEAT TREATING METHOD OF COIL SPRING

摘要

PURPOSE:To perform a hardening heat treatment to the surface of a coil spring quickly in a very short time, by coating a coil spring formed a from steel wire or a steel bar, and after that, irradiating laser light of high energy density onto its surface. CONSTITUTION:Said coil spring is coated with a graphite compound, etc. On the other hand, the direction of laser light 3a generated by a laser oscillator 2 is changed by a reflector 4, is focused 5 to energy density by which surface hardening heat treatment can be performed, and after that, laser light 3d obtained by changing its direction by a reflector 7 is irradiated at right angles with the lengthwise direction of said coil spring 1 which has been coated, by which the surface is heated. During the time of this irradiation, the laser light 3d is rotated in the direction of A by a fixed movable device 8, and also is moved in the direction of B. Subsequently, after the surface hardening treatment of the outside surface of the spring 1 has ended, a mirror 4 and a focusing lens 5 are moved by a movable storing case 6, the inside surface of the spring 1 is heated by the laser light whose direction has been changed by a mirror 7, and the surface hardening heat treatment is performed in the same way. As a result, a hardened layer whose surface hardness is HRC40-60 and whose depth is =0.2mm.is formed on the surface of the spring 1.