JPH0513148A - Manufacture of spark plug - Google Patents

Abstract

PURPOSE:To simplify the manufacture of a ground electrode having a composite structure by winding a sheet outer sheath material on a cylindrical core material to form a composite round bar, and repeating drawing process and annealing process to form a wire composite material made small in diameter. CONSTITUTION:A sheet outer sheath material 8 is wound on a cylindrical core material 7, and both the end parts of the outer sheath material 8 are welded to the core material 7 to form a composite round bar 9. The composite rotund bar 9 is subjected to drawing process and annealing process repeatedly to make the diameter small, and an alloy layer 10 is formed on the bonding critical surface between the core material 7 and outer sheath material 8 forming the composite round bar 9 to form a wire composite material 11. The composite material 11 is molded with a roller or a die so as to have roundness on the sectional rectangular four corners and cut into a determined dimension, and, further, the terminal of a molded material 12 is integrally bonded to the edge of a main metal fitting 5 by electric resistance welding. Thus, a ground electrode having a composite structure can be manufactured with a simple method, and the mass-production can be also performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug used in an internal combustion engine, and more particularly to a method of manufacturing a ground electrode.

[0002]

2. Description of the Related Art In recent years, as the performance of internal combustion engines has improved, the temperature of the combustion gas generated in the combustion chambers of the internal combustion engines has risen to a high temperature, which causes them to protrude into the combustion chambers and to mix with the tip of the center electrode. Since the ground electrode that performs spark discharge to ignite the above is constantly exposed to the above-mentioned high temperature combustion gas, it easily becomes hot. As a result, the ground electrode that becomes hot causes preignition. For the purpose of improving the thermal conductivity of the metal shell to which they are integrally joined, a metal of good thermal conductivity such as copper or nickel is enclosed in the ground electrode to form the ground electrode itself as a composite structure. Things have been proposed.

[0003]

However, in the case of the above-mentioned conventional one, a cup-shaped ground electrode made of nickel is filled with a rod-shaped copper material having good heat conductivity to form a ground electrode of a composite structure. Since the caulking portion of each ground electrode manufactured by plastic working is joined to the metal shell by electric resistance welding, the number of working steps increases, so the manufacturing workability decreases and the cost increases. There is.

Although a ground electrode of Inconel 600 is filled with a nickel material having good heat conductivity to form a ground electrode having a composite structure, the best and particularly simple manufacturing method has not been clarified.

Therefore, the present invention is intended to improve the drawbacks of the above-mentioned conventional ones, and to manufacture a ground electrode having a composite structure by a simple method.

[0006]

For this purpose, the insulator is held at the tip and arranged at a position facing the tip of the center electrode.
Ground electrode integrally joined to the metal shell, after winding the sheet-shaped outer cover material around the cylindrical core material, and welded both ends of the sheet-shaped outer cover material and the core material into a composite round bar, This composite round bar is reduced in diameter by repeatedly performing a wire drawing step and an annealing step, and after forming an alloy layer at the bonding interface between the core material and the sheet-shaped outer skin material forming the composite round bar, A wire-shaped composite material with a reduced diameter is molded with rollers or dies so that the four corners of the rectangular cross section have roundness, the molded material is cut to a specified size, and the edge of the metal shell is electrically cut. It is integrally joined by resistance welding.

In addition, the sheet-shaped outer skin material is formed into a pipe shape by welding in advance, the core material is inserted into the pipe-shaped outer skin material, and then this is formed into a composite round bar.

[0008]

With the above-mentioned structure, the ground electrode having a composite structure in which the core material made of pure nickel having good heat conductivity is enclosed inside the sheet-like outer material made of nickel alloy or the like, After winding the sheet-shaped skin material around the columnar core material,
Both ends of the sheet-like outer material and the core material are welded to each other to form a composite round bar, and the composite round bar is reduced in diameter by repeatedly performing a wire drawing step and an annealing step, and a composite round bar is formed. By forming an alloy layer at the joint interface between the core material and the sheet-shaped outer covering material to form a wire-shaped composite material having a reduced diameter, mass production can be performed easily and in large quantities.

Further, the sheet-shaped outer cover material is preliminarily welded into a pipe shape, the core material is inserted into the pipe-shaped outer cover material, and then the composite outer rod material is formed into a composite round bar, so that the ground electrode The manufacturing process can be simplified.

[0010]

The present invention will be further described with reference to the embodiments shown in the drawings. (1) is a ground electrode (6) which is an embodiment of the present invention
And a center electrode (3) held at the tip of an insulator (2) and a spark at the tip of the center electrode (3). A ground electrode (6) integrally joined to the metal shell (5) is arranged at a position facing the discharge part (4).

The ground electrode (6) integrally joined to the metal shell (3) has a core material (7) made of a metal having good heat conductivity such as pure nickel material and pure iron. ) 95% nickel alloy (Si, C
It has a composite structure composed of an outer skin material (8) such as r, Al, Mn and the like, which is contained at a maximum of 5%.

Further, as shown in FIG. 2, the ground electrode (6) having this composite structure has a sheet-shaped outer cover (7) on a core (7) made of a metal having a good thermal conductivity such as pure nickel. After winding 8), both ends (seam) of the sheet-like outer skin material (8) and the core material (7) are welded to each other to form a composite round bar (9). On the other hand, the wire drawing step and the annealing step are repeatedly performed to reduce the diameter, and at the joint interface between the core material (7) forming the composite round bar (9) and the sheet-shaped outer skin material (8), an alloy layer (10 ) Is formed, the wire-shaped composite material (11) having a reduced diameter is formed by a roller or a die so that the four corners of the rectangular cross section have roundness. Cut into
The edge of the molded material (12) is joined to the edge of the metal shell (5) continuously and integrally by electric resistance welding.

Since the present invention has the above construction, the core material (7) made of pure nickel or the like having good thermal conductivity is enclosed inside the sheet-like outer material (8) made of nickel alloy or the like. A ground electrode (6) having the following composite structure is wound around a cylindrical core material (7) with a sheet-shaped outer cover material (8), and then both ends of the sheet-shaped outer cover material (8) and a core material (7). ) Are welded to form a composite round bar (9), and the composite round bar (9) is repeatedly subjected to a wire drawing step and an annealing step to reduce the diameter and to form the composite round bar (9). By forming an alloy layer at the joint interface (10) between the core material (7) and the sheet-like outer skin material (8), the wire-like composite material (11) has a reduced diameter,
The ground electrode (6) can be easily mass-produced in large quantities.

Further, as shown in FIG. 3, the sheet-shaped outer cover material (8) is preliminarily welded into a pipe-shaped outer cover material (13), and the core material (7) is inserted into the pipe-shaped outer cover material (13). By using the composite round bar (9) as described above, the manufacturing process of the ground electrode (6) can be further simplified.

[0015]

As described above, by manufacturing the ground electrode having the composite structure, unlike the conventional manufacturing method,
Since it is simple and can be mass-produced, it has an excellent effect of being able to provide a spark plug which is used in an internal combustion engine of high performance in recent years and has a good heat dissipation property at a low cost. is there.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of a spark plug tip portion according to an embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of a ground electrode according to an embodiment of the present invention.

FIG. 3 is an enlarged perspective view of a manufacturing process of another embodiment of the present invention.

[Explanation of symbols]

1 Tip of spark plug 2 insulator 3 Center electrode 4 Spark discharge part 5 metal shell 6 ground electrode 7 core material 8 outer skin 9 compound round bar 10 Alloy layer 11 Wire-shaped composite material 12 Molding material 13 Pipe-shaped skin material

Claims (2)

[Claims] 1. A grounding electrode, which is held at a tip of an insulator of a spark plug and is arranged at a position facing a tip of a center electrode, and which is integrally joined to a metal shell, and a sheet-like outer cover material on a cylindrical core material. After winding, both ends of the sheet-shaped outer covering material and the core material are welded to form a composite round bar, and the wire drawing step and the annealing step are repeatedly performed on the composite round bar to reduce the diameter. After forming an alloy layer at the joint interface between the core material and the sheet-shaped outer material that compose the composite round bar, the wire-shaped composite material having the reduced diameter is formed into a roller so that the four corners of the rectangular cross section have roundness. Alternatively, a method of manufacturing a spark plug, which is formed by molding with a die, cutting the molded material into a predetermined size, and further integrally joining it to the edge of the metal shell by electric resistance welding. 2. The spark according to claim 1, wherein the sheet-shaped outer cover material is preliminarily welded into a pipe shape, the core material is inserted into the pipe-shaped outer cover material, and then welded to form a composite round bar. Manufacturing method of plug.