JP3226327B2 - Method of manufacturing spark plug electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a spark plug electrode by plastic working.

[0002]

2. Description of the Related Art A center electrode of a spark plug is formed by fitting a copper core material into a nickel alloy base material formed into a cup shape, and this fitted body is sequentially formed by a plurality of plastic working stations constituted by punches and dies. It is manufactured by plastically processing to a small diameter step by step, and finally shaping the tip by cutting or grinding. In the subsequent processes such as cutting and grinding, during extrusion molding, a difference in material flow occurs between the central portion and the peripheral portion of the material due to frictional resistance between the die and the material, and the tip shape of the extruded product becomes a convex shape. Made for

[0003]

However, in the conventional manufacturing method, a step of shaping the front end surface of the center electrode is required, which is troublesome, and has a disadvantage of low productivity. An object of the present invention is to form a front end surface into a flat surface only by a plastic working process,
An object of the present invention is to provide a method for manufacturing a spark plug electrode which does not require post-processing such as cutting and has excellent productivity.

[0004]

SUMMARY OF THE INVENTION A method of manufacturing a spark plug electrode according to the present invention is directed to a composite columnar material comprising a good heat conductive metal and a heat resistant metal in a plurality of plastic working stations constituted by a punch and a die. In the method for manufacturing a spark plug electrode in which the plastic working is performed stepwise sequentially to a small diameter, before or during this plastic working step, a recess is provided in the front end surface of the base material or the intermediate material, and thereafter, the front end portion is formed. It is characterized in that it is extruded to a small diameter to form a flat tip surface.

[0005]

[Effects and Effects of the Invention] At the beginning or during the plastic working process,
A recess is formed in the front end surface of the material, and then the front end is formed into a small diameter by extrusion. As a result, the swelling of the tip surface during extrusion molding acts to flatten the recess,
Post-processing such as cutting can be eliminated. In addition, the shape and depth of the recess are determined by execution and error, or are determined by analyzing the amount of plastic deformation by a finite element method.

[0006]

1 and 2 show a manufacturing process of a spark plug center electrode according to a first embodiment of the present invention. A good heat conductive metal wire is cut into a predetermined length, and a cylindrical tip, which is an intermediate material having both ends parallel by end face striking, is forged into a flanged tip 1 shown in FIG. At the same time, the nickel alloy wire is cut into a predetermined length, and a columnar chip serving as a base material whose both ends are parallel to each other is forged into a cup-shaped chip 2 by end face striking. Next, as shown in (b) of FIG. 1, the flanged chip 1 is fitted into the cup-shaped chip 2 to form a fitting body 10. In this case, the recess 3 is formed at the tip (the lower end in the figure) of the cup-shaped chip 2 at the time of forging the cup-shaped chip 2 or forming the fitting body 10.

This fitting body 10 is shown in FIG.
An extrusion molding station A1 in which the punch P1, the die D1, and the kickout pin K1 are combined is formed into a small-diameter intermediate molded body 20 having a flange 21 at a rear end (upper end shown) shown in FIG. Next, a molding station A equipped with a die D2 and a punch P2 shown in FIG.
2, the flange 21 of the intermediate molded body 20 is cut,
A cylindrical intermediate molded body 30 shown in FIG. 1D is manufactured.

Thereafter, the punch P shown in FIG.
3. At a forming station A3 including a die D3 and a kickout pin K3, the intermediate formed body 30 is plastically processed to form a center electrode 40 having a small front end diameter portion 41 and a rear end flange portion 42.
Is molded. At this time, the kick-out pin K3 presses the distal end surface 43 of the center electrode 40 to correct the remaining unevenness to forge a flat surface. As a result, the center electrode 40 of the spark plug including the nickel alloy shell 44 and the good heat conductive metal core 45 shown in FIG.

FIGS. 3 and 4 show a second embodiment of the present invention. In this embodiment, the fitting body 10 having no concave portion 3 on the distal end face shown in FIG.
4, the extrusion station A4 in which the die D4 and the kickout pin K4 are combined, the flange 51 is provided at the rear end.
Is plastically processed. At this time, the tip of the kickout pin K4 bulges in a convex shape, and is strongly pressed to form the recess 6 on the tip surface of the initial molded body 50. Next, the die D5 and the punch P shown in FIG.
The flange 51 of the initial molded body 50 is cut by a molding station A5 provided with
To manufacture. Next, a molding process having a mold structure similar to that of the first embodiment shown in (c), (d) and (e) of FIG. 1 and (a), (b) and (c) of FIG. to go into.

Thus, according to the manufacturing method of the present invention,
Post-processing such as cutting or grinding of the front end surface 43 for forming the electrode front end surface flat is unnecessary, so that no cutting chips are generated and the manufacturing cost can be reduced. If the recesses 3 to 6 are not formed before or during the plastic working process as in the present invention, a large convex shape is formed on the front end surface 43 of the center electrode 40 in the extrusion forming process, It is extremely difficult to correct the convex shape by the kickout pin K3 in the plastic working in the process.

The method for manufacturing a spark plug electrode according to the present invention can be applied to the manufacture of a center electrode 40 having a core made of pure iron or pure nickel at the center of a copper core, or to the manufacture of a ground electrode having a rectangular cross section. Further, in the above-described embodiment, the cylindrical tip 1 made of a copper material having a flange is used, but the cylindrical tip 1 may have no such flange.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a spark plug electrode according to the present invention.

FIG. 2 is a sectional view of a plastic working station used in the manufacturing process of FIG.

FIG. 3 is a manufacturing process diagram of a spark plug electrode according to a second embodiment.

FIG. 4 is a sectional view of a plastic working station used in the manufacturing process of FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Flanged tip (intermediate material) 2 Cup-shaped tip (base material) 3, 6 recess 10 Fitted body (cylindrical material) 40 Center electrode 41 Small tip diameter part 43 Tip face

Claims (1)

(57) [Claims] 1. A spark plug electrode for plastically processing a composite cylindrical material composed of a good heat conductive metal and a heat resistant metal in a stepwise manner to a small diameter in a plurality of plastic working stations constituted by a punch and a die. In the manufacturing method, before or during this plastic working step, a recess is provided in the front end surface of the base material or the intermediate material, and thereafter, the front end portion is extruded to a small diameter to form a flat front end surface. A method for manufacturing a spark plug electrode.