JPH0315184A - Manufacture of composite outside electrode for ignition plug - Google Patents

Abstract

PURPOSE:To prevent a reduction in welding strength and the scattering in dimension by closing an open end section by the use of a cylindrical side wall, and thereby inserting a composite molded item into a molding frame with a section closed by the cylindrical side wall in the land so that an extrusion molded item is thereby formed. CONSTITUTION:A cup W5 is formed out of a cylindrical side wall 13 extending to the axial direction, an open end section 14 formed at one end of the side wall 13 and a closed end section 15 formed at the other end of the side wall 13 which are made up from the first metal which is anti-corrosive. In the second place, an engaging body W6 is formed in such a way that the second metal 2 which is shorter than the side wall in the axial direction but is excellent in heat conduction, is coupled in the side wall 13 on the closed end section 15 side. Then, said body is inserted into a metal mold 13 with the open section 32. This permits a composite molded item W7 which firmly encloses the whole of the circumference of the second metal 2 with the first metal 1 to be formed. Successively, the molded item W7 is inserted into a metal mold 34 with a section 16 closed together in the lead by means of extrusion molding by the use of a punch 33. By this constitution, a composite molded item W8 furnished with a slender shell section 18 can thereby be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a composite outer electrode of a spark plug installed in an internal combustion engine.

[Prior Art] JP-A-58-140985 describes a method for manufacturing a composite spark plug electrode. In this manufacturing method, a highly conductive second metal having a length shorter than the axial length of the cylindrical side wall formed in the cup made of the corrosion-resistant first metal is placed in the cylindrical shape at the closed end. After being fitted into the side wall, the cylindrical side wall is caulked to slightly close the open end to form a composite molded body with a small opening at one end. Subsequently, this composite molded body is inserted into a mold with the opening portion at the beginning using an E-shape press to form an extruded molded body with a reduced diameter composite molded body. [Problems to be Solved by the Invention] However, even if the extrusion molded body 200 formed by the above-described manufacturing method is inserted into a mold with the opening at the beginning and extruded, as shown in FIG. , the cylindrical side wall 2
01, the open end 202 may not be completely closed and the second metal 203 with good thermal conductivity may be exposed, or the recess 20 may be formed at the end of the cylindrical side wall 201 as shown in FIG.
There was a possibility that 4 would remain. Note that in the composite outer electrode manufactured by this manufacturing method, the firing part side is exposed to high temperatures, so in order to prevent corrosion of the second metal 203, the closed end of the cup is placed on the firing part side. The open end of the cup is placed on the side where it is welded to the metal shell. However, in the above-mentioned composite outer electrode as shown in FIG. 17, the second metal 203 is exposed on the side of the metal shell, and the contact area between the first metal 205 and the metal shell becomes small. For this reason, the composite outer electrode and the metal shell cannot be reliably joined by welding in some cases. In addition, in the case of the composite outer electrode as shown in FIG. 18, air is trapped in the recess 204 of the composite outer electrode during welding to the metal shell, resulting in reduced welding strength and dimensional variations. There was a possibility that this problem could occur. In addition, when reducing the diameter of the composite molded body by extrusion molding, it is impossible to extrude the composite molded body until the bandage completely passes through the aperture formed in the mold.
It was not possible to uniformly reduce all diameters of the composite molded body. In addition, if this extrusion molding method is used to insert the opening into the mold, the first metal will not apply much force around the opening, so the second metal
There was a possibility that the metal could not be completely contained.

The purpose of the present invention is to provide a method for manufacturing a composite outer electrode for a spark plug, which can reliably weld the composite outer electrode and the metal shell and prevent a decrease in welding strength and dimensional variations. In addition, the present invention eliminates unextruded parts during extrusion molding, makes it possible to uniformly reduce all diameters of the composite molded product, and the first
The object of the present invention is to provide a method for manufacturing a composite metal outer electrode for a spark plug, which can completely surround a second metal with metal.

[Manual punch to solve the problem] The method of manufacturing the composite metal outer electrode for a spark plug of the present invention employs the following technical means. The invention of claim 1 includes: a cylindrical wall extending in the axial direction from a first corrosion-resistant metal; an open end portion formed at one end of the cylindrical side wall;
and a first step of forming a cup having a closed end formed at the other end of the cylindrical side wall, and a second metal having good thermal conductivity having a length shorter than the axial length of the cylindrical side wall. A second step of fitting the closed end into the simple side wall, and closing the open end with the cylindrical side wall so that the second metal is tightly surrounded by the first metal. a third step of forming a molded body; and a fourth step of forming an extrusion molded body by inserting the composite molded body into a mold with the portion closed by the cylindrical side wall at the beginning by extrusion molding. It is characterized by having the following.

The invention according to claim 2 is characterized in that the composite molded body is extrusion-molded by a composite molded body that is then extruded.

[Function] Composite outer ilI for spark plugs of the present invention! The manufacturing method of the electrode has the following effects using the above-mentioned technical means. <Action of Claim 1> By reliably closing the open end with the cylindrical side wall, the composite molded body can be inserted into the mold with the part closed by the cylindrical side wall leading, and the extruded molded body can be shaped. However, since the second metal is tightly surrounded by the first metal, the second metal is not exposed more than the first metal. Therefore, the contact area of the first metal of the composite outer electrode with the main metal fitting becomes large.

In addition, since the second metal is tightly surrounded by the first metal, no recesses remain at the end of the cylindrical side wall, so when joining the composite outer electrode and the main metal fitting by welding, etc. No air is trapped inside. (Effect of Claim 2) By extrusion-molding the composite molded body with a composite molded body to be extruded next, the closed end of the previous composite molded body and the next composite molded body are formed in a cylindrical shape (by the II wall). Since the closed part comes into contact with the closed part, force is applied to the part of the composite molded body which is closed by the cylindrical side wall. [Effects of the Invention] The method for manufacturing the composite metal outer electrode for a spark plug of the present invention is as described above. (Effects of Claim 1) The composite outer electrode and the metal shell can be reliably welded together. Furthermore, the composite outer electrode can be Since air is not trapped in the weld, it is possible to prevent a decrease in welding strength and the occurrence of dimensional variations.

(Effect of Claim 2) In the previous composite molded product, it is possible to eliminate the unextruded portion that is not extruded, so that it is possible to obtain an extruded molded product having a uniform outer peripheral shape in the axial direction.

Further, in the composite molded body to be extruded next, force is applied to the portion closed by the cylindrical side wall, so that the second metal can be more reliably and more tightly surrounded by the first metal.

[Example 1] A method for manufacturing a composite metal outer electrode for a spark plug according to the present invention will be explained based on an example shown in Figs. 1 to 13. 1 to 12 show the manufacturing process of a composite outer electrode of a spark plug installed in an internal combustion engine employing the present invention.

This article describes the manufacturing process of the composite outer electrode of a spark plug. at first,
As shown in Figure 1, the first material is made of nickel, nickel alloy, Inconel (trademark), etc.
Cut the round bar-shaped body W1 from steel metal. By inserting this body W1 into a mold (not shown) and punching it with a punch (not shown), a bullet-shaped body W2 having an arcuate corner 11 on the lower end surface is formed as shown in FIG. form. This body W2 is pressed (not shown) to form a bullet-shaped body W3 having parallel end surfaces as shown in Fig. 3. Next, the body W3 is punched with a punch (not shown). As a result, as shown in Fig. 4, a bullet-shaped body W4 having a pilot hole 12 at the center of one end surface is formed.The pilot hole 12 of this body W4 is further punched with a punch (not shown). ,
As shown in FIG. 5, a cylindrical side wall 13 extending in the axial direction
, a cup W having an open end 14 formed at one end of the side wall 13 and a closed end 15 formed at the other end of the side wall 13.
5 is formed (Step II). Then, a second metal 2 (6th
As shown in FIG. Insert the second metal 2 so that it protrudes from JX2. The first metal 1 and the second metal 2 fitted together in this state are pressurized and integrated using a press (not shown), thereby tightly fitting the first metal 1 and the second metal 2. A fitted body W6 is formed (second step). Then, as shown in FIGS. 8 and 9, this fitted body W6 is inserted into the mold 31 with the open end 14 at the beginning and punched with the punch 32. For this reason, the closing portion 1 of the side wall 13
6 closes the open end 14 and forms a composite molded body W7 having both parallel end surfaces in which the entire periphery of the second metal 2 is tightly enclosed by the first metal 1 (third step). As shown in FIG. 14, when this composite molded body W7 is extruded and the composite molded body W7 is inserted into the mold 100 with the closed end 15 leading, the extruded molded body Wa is formed. As shown in FIG. 15, when the unpressed portion 101 of the extruded body Wa is removed by trimming, a part of the first metal 1 is folded 102 as shown in FIG.
There is an inconvenience that it may come off.

In order to solve such inconvenience, this composite molded body W7
is inserted into a mold 34 by extrusion molding using a bunch 33, as shown in FIG. 10, with the closing portion 16 at the beginning. For this reason, the unpressed portion 17 formed on the head,
and extends downward from the unpressed portion 17, and is extended downward from the unpressed portion 1
A composite molded body W8 having a body 18 that is thinner than 1 is formed. Then, as shown in FIG. 11, the unpressed portion 17 of the composite molded body W8 is removed by punching (trimming) using a trimming punch and a trimming die to form a bar-shaped composite molded body W9. Therefore, even if the unpressed portion 17 is removed by trimming, part of the first metal 1 will not come off from the fold.

Next, as shown in FIG.
The composite molded body W9 is inserted into a mold 36 as a mold frame having a rectangular aperture 37 with the molded body 6 at the beginning.

Then, by extruding the composite molded body W9 by the composite molded body W91 to be extruded next, the composite molded body W9 is extruded.
Since the closing portion 16 of the composite molded body W91 contacts the closed end portion 15 of the composite molded body W91, a large force is applied to the closing portion 16 of the composite molded body W91. Therefore, the next composite molded body W91 is:
The first metal 1 can surround the second metal 2 more reliably and more closely.

Furthermore, since the previous composite molded body W9 is extruded into the composite molded body W91 and passes through the aperture 37 of the mold 36 in its entirety, it is possible to completely eliminate the unextruded portion 17. Further, when the composite molded body W9 passes through the aperture 37 of the mold 36, it is narrowed uniformly in the axial direction, thereby forming an extruded molded body WIO having a rectangular cross section (
4th step). FIG. 13 shows a spark plug 4 having a composite outer electrode 41 made in accordance with the present invention.

Since the composite outer electrode 41 reliably closes the open end 14 with the closing portion 16 of the survey wall 13 in the third step,
Even if the composite molded body W9 is extruded with the closing portion 16 at the beginning in the fourth step, the end face of the second metal 2 is not exposed from the first metal 1. Therefore, it is possible to prevent the second metal 2 from corroding, and also to prevent the second metal 2 from corroding.
The contact area between the closing portion 16 and the end surface of the metal shell 42 can be reliably obtained by welding. Therefore,
The closing portion 16 of the composite outer electrode 41 is reliably welded to the end of the metal shell 42.

In addition, since the open end 14 is reliably closed by the closing portion 16 of the side wall 13, there is no recess left at the end of the side wall 13, so that the composite outer measuring electrode 41 and the end face of the metal shell 42 are Air is not trapped inside the composite outer sinter electrode 41 during welding. Therefore, the composite external electrode 41 can prevent low welding strength and dimensional variations. In addition, in the composite outer electrode 41 manufactured according to the present invention, the closing part 16 which is a joint part is joined to the end face of the metal shell 42 by welding, and the closed end part 15 which is the ignition part side is connected to the center electrode 43 and spark discharge. They face each other with a gap in between. In another embodiment, as long as the first, second, third, and fourth steps are included in the manufacturing process of the composite outer III electrode, other steps may be omitted.

[Brief explanation of the drawing]

Figures 1 to 12 are process diagrams showing the manufacturing process according to the method for manufacturing a composite outer electrode of a spark plug employing the present invention, and Figure 13 is a process diagram of an ignition plug having a composite outer electrode manufactured according to the present invention. It is a sectional view showing the main parts of the stopper. FIGS. 14 to 16 are process diagrams showing manufacturing steps illustrated as comparative examples of the present invention. Figures 17 and 18
The figure shows a conventional ignition plug outside the compound! FIG. 2 is a process diagram showing the manufacturing process of the L electrode manufacturing method. In the figure 1... First metal 2... Second metal 4... Ignition plug 13... Side wall (f! J-shaped side wall> 14... Open end part
15... Closed end portion 16... Closing portion (portion closed by the cylindrical side wall) 36... Mold (formwork) 41...
・Composite external measuring electrode 42... Metal shell W5... Cup W9... Composite molding W10... Extruded product Fig. 1 Fig. 12 Fig. 3 Fig. 4 Fig. 12 Fig. 5 16 @ No. 71! l 8th momme 15 14... Open end 15... Closed end -5... Cup 19 Figure 1110 Figure *12 Figure 16... Closed part (1! Part closed by I-shaped side wall) 4...Composite molded body 10...Extrusion molded body 36...Mold (form) 2

Claims (1)

[Scope of Claims] 1) (a) A cylindrical side wall extending in the axial direction from a corrosion-resistant first metal, an open end portion formed at one end of the cylindrical side wall, and an open end portion formed at the other end of the cylindrical side wall. (b) applying a second metal having good thermal conductivity to a length shorter than the axial length of the cylindrical side wall around the closed end; a second step of fitting into the cylindrical side wall; (c) closing the open end with the cylindrical side wall to form a composite molded body in which the second metal is tightly surrounded by the first metal; (d) a fourth step of inserting the composite molded body into a mold with the portion closed by the cylindrical side wall at the beginning to form an extrusion molded body by extrusion molding; A method for manufacturing a composite outer electrode for a stopper. 2) Claim 1, wherein the composite molded body is extruded by a composite molded body that is then extruded.
A method for manufacturing a composite outer electrode for a spark plug as described in .