Patent ID: 7500310

Claim:
A method of making a component part of a reclining device that is used to adjust an inclination of a seat back with respect to a seat cushion, said method comprising: preparing the component part; selectively heating a predetermined portion of the component part up to a temperature greater than a transformation point of a material of the component part; cooling the component part; and leaving portions of the component part other than the predetermined portion as a base material to thereby selectively increase a strength or a wear and abrasion resistance of the component part; wherein the reclining device comprises a guide bracket to be secured to one of a seat cushion and a seat back that can be inclined relative to the seat cushion, an internal gear to be secured to the other of the seat cushion and the seat back, a cam rotatably mounted between the guide bracket and the internal gear, and a pair of lock gears interposed between the guide bracket and the internal gear so as to be radially slidable in association with rotation of the cam, and wherein the component part comprises at least one of the guide bracket, the internal gear, the cam, and the pair of lock gears; wherein the guide bracket comprises a plurality of guide members for guiding the pair of lock gears so as to be slidable relative thereto, and wherein heat treatment is selectively conducted with respect to a portion of an entire outer circumference of each of the plurality of guide members; and wherein the heat treatment is conducted while the guide bracket is inclined and being rotated with respect to a heating source, and the heating source is being moved.