Method of making a component part of a reclining device

Abstract

In 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, after the component part has been prepared, a predetermined portion of the component part is selectively heated up to a temperature greater than a transformation point of a material of the component part, and the component part is then cooled. During this heat treatment, portions of the component part other than the predetermined portion are left as a base material to thereby selectively increase the strength or the wear and abrasion resistance of the component part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives and features of the present invention will become more apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings, throughout which like parts are designated by like reference numerals, and wherein:

FIG. 1 is an exploded perspective view of a reclining device to which the present invention is applied;

FIG. 2 is a perspective view of a semiconductor laser beam machine, depicting the condition in which heat treatment is being conducted with respect to an internal gear constituting the reclining device of FIG. 1;

FIG. 3 is a photograph of a cross-section of internal teeth of the internal gear that underwent the heat treatment;

FIG. 4 is a graph indicating the surface hardness of the internal gear; and

FIG. 5 is a perspective view of the semiconductor laser beam machine, depicting the condition in which heat treatment is being conducted with respect to a guide bracket constituting the reclining device of FIG. 1.

Claims

1. 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; andleaving 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.

2. The method according to claim 1, 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.

3. The method according to claim 2, 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.

4. The method according to claim 3, 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.

5. The method according to claim 2, wherein heat treatment is selectively conducted with respect to internal teeth of the internal gear.

6. The method according to claim 5, wherein the heat treatment is conducted from inside the internal teeth while the internal gear is inclined and being rotated with respect to a heating source.

7. The method according to claim 2, wherein heat treatment is selectively conducted with respect to teeth of the pair of lock gears that are engageable with internal teeth of the internal gear.

8. The method according to claim 2, wherein heat treatment is selectively conducted with respect to portions of the pair of lock gears that are brought into contact with the cam.

9. The method according to claim 2, wherein heat treatment is selectively conducted with respect to a portion of the cam that is brought into contact with the pair of lock gears.

10. The method according to claim 1, wherein a laser is employed as a heating source.

11. The method according to claim 1, wherein the laser is a semiconductor laser.