JPH038531A - Manufacture of main fittings - Google Patents

Abstract

PURPOSE:To prevent a wrinkle from being generated on the outer circumference of a caulked groove part to manufacture main fittings excellent in dimensional accuracy by forming a hexagonal cylindrical part small in diameter from the central part to one side after a round bar stock is extruded to form an axial hole in the manufacture of the main fittings of a spark plug. CONSTITUTION:A body W1 having an arcuate corner 101, a small center holes 102, 103 is formed of a round steel bar stock at a 1st forming part of a cold extrusion machine. Then, a large diameter part 104, a small diameter part 105 and large center holes 106, 107 are formed at a 2nd forming part to make a body W2, further, a 1st cylindrical part 109 smaller in diameter than another part 108 and circular in sections is formed on one side of the body W2 at a 3rd forming part to make a body W3 forming holes 110, 111 on the axes of both end faces and a stepped hole 112 is formed on the inside of a hole 110 at a 4th forming part to make a body W4. Furthermore, an axial hole 113 is formed at a 5th forming part to make a body W5, then, at the 2nd stage by a 6th forming part, a 2nd cylindrical part 115 smaller in diameter than the central part 114 and having a hexagonal section is formed on the other side of the body W5 to make the main fittings 100 of the spark plug 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a metal shell, and in particular to a method for manufacturing a metal shell,
It relates to the manufacturing method of metal shells such as glow plugs, oxygen sensors, water temperature sensors, knock sensors, fuse-type temperature sensors, or thermistor-type temperature sensors.

[Prior Art] Conventionally, for example, in some types of gasoline engines, an ignition plug having a hexagonal metal shell with a smaller diameter above the center of the body is mounted in a recess formed in the cylinder head. ing.

The main metal fitting of a spark plug with such a shape (Yoguchi-Shiba Patent No. 0036050) is formed by extrusion molding to form a cylindrical part on one side of the center of the body with a diameter smaller than the diameter of the center and a hexagonal cross section. Through the pre-process and extrusion molding,
It is manufactured by a manufacturing method that includes the first two steps and the second step of forming a shaft hole that axially passes through the body formed in the step.

In addition, in the pre-process, as shown in FIGS. 12 and 13, a recess 2 on one side of the body 200 is punched using a punch 210.
01 is extruded forward into the gap 221 between the mandrel 220 and the die 230 with a hexagonal inner peripheral hole 231. At this time, the cylindrical portion 202 on one side of the body 200
A cylindrical portion 20 extending in the axial direction of the hexagonal portion 203
It becomes 2. In addition, conventionally, cooling air and cooling oil are supplied to the body 200 to prevent excessive frictional heat from occurring between the inner circumferential surface of the body 200 and the outer circumferential surface of the mandrel 220.
00 into the recess 201 on one side to prevent generation of excessive frictional heat.

[Problems to be Solved by the Invention] However, in the conventional manufacturing method described above, since the shaft hole forming is performed after the hexagonal forming, the recess 2 of the body 200 is
When the mandrel 220 is inserted into the 01, the cylindrical part 20
2 is squeezed by the die 230, there is a problem that cooling air and cooling oil cannot be easily discharged to the outside of the recess 201.

Therefore, as shown in FIG. 14, the inside of the recess 201 near the boundary between the extruded hexagonal part 203 and the body 200 (cutting line A-A in FIG. 13) There was a problem in that a recess 204 was formed in the axial direction of the circumferential surface, which served as a discharge flow path for cooling air and cooling oil.

Further, in the ignition plug, the metal shell and the insulator are assembled by caulking the rear end of the metal shell.

However, when this caulking is performed, wrinkles appear in the caulking groove of the metal shell due to the recess 204 in the body 200, which impairs the appearance and results in a defective product.

An object of the present invention is to provide a method for manufacturing a metal shell that prevents the occurrence of dents in the body during hexagonal molding.

[Means for Solving the Problems] The method for manufacturing a metal shell of the present invention includes the steps of:
A first step of forming a shaft hole passing through the body in the axial direction, and extrusion molding to form a hexagonal cross section with a diameter smaller than the diameter of the center part on one side of the center part of the body formed by the first process. A technical means comprising a second step of forming a shaped cylindrical portion was adopted.

[Function] The method for manufacturing a metal shell of the present invention has the following effects by the above-mentioned technical means.

In the first step, a cylindrical body having a shaft hole is formed by extrusion molding the shaft hole passing through the body in the axial direction.

In the second step, a cylindrical part with a hexagonal cross section and a diameter smaller than the diameter of the center part is extruded on one side of the center of the body formed in the first step. A cylindrical body having a cylindrical portion on one side is formed.

In this way, by performing the second process after the first process, when a rod-shaped member such as a punch or mandrel is inserted into the shaft hole of the four bodies, the cylindrical part is squeezed and the cylindrical part Cooling air and cooling oil are collected from the inner peripheral portion of the shaft hole in a portion of the shaft hole that is not blocked by a rod-like member such as a punch or mandrel.

[Effects of the Invention] The method for manufacturing a metal shell of the present invention achieves the following effects through the technical means and operations described above.

It is possible to prevent the formation of depressions on the inner circumferential surface of the body that serve as exhaust channels for cooling air and cooling oil.

For example, when the method for manufacturing a metal shell of the present invention is adopted as a method for manufacturing a metal shell for a spark plug, even if the metal shell and the insulator are assembled by caulking the rear end of the metal shell, the 1
As shown in FIG. 0, it is possible to prevent wrinkles from forming on the outer periphery of the fastening groove portion 125 of the metal shell.

Embodiments] A method for manufacturing a metal shell of the present invention will be described based on embodiments shown in FIGS. 1 to 11.

1 to 10 represent a first embodiment of the present invention.

1 to 7 show the molded shape of the body in each molding section, and FIG. 8 shows a cold extrusion molding machine for molding the body by the method of manufacturing a metal shell for an ignition plug.

The cold extrusion molding machine A has first to sixth units arranged in a straight line.
It comprises a forming section 1.2.3.4.5.6 and transport means (not shown).

The first molding section 1 has a mold (die) 11, a punch 12, and a kickout bin 13, and performs upsetting to form a body W1 (FIG. 1). The second molding section 2 has a formwork (die) 21, a punch 22, a pin 23, and a kickout sleeve 24, and performs forward extrusion molding to form the body W.
2 (Fig. 2) is formed. In this embodiment, the first forming section 1 and the second forming section 2 perform centering forming for forming the third forming section 3 and subsequent sections.

The third molding section 3 has a formwork (die) 31, a punch 32, a punch holder 33, a bin 34, and a kickout sleeve 35, and performs composite (front and rear) extrusion molding to form the fuselage W3 (Fig. 3). form.

The fourth molding section 4 has a mold (die) 41, a punch 42, a bottle 43, and a kickout sleeve 44, and performs small hole molding to form the body W4 (FIG. 4).

The fifth forming section 5 is a forming means for carrying out the first step according to the present invention, and has a formwork (die) 51, a punch 52, a kick-out sleeve 53, and a scrap discharge section 54, and passes through a shaft hole. This forms a fuselage W5 (Fig. 5).

The sixth molding section 6 is a molding means that performs step 2I according to the present invention, and includes a mold (die) 61, a punch 62, a bunch kickout sleeve 63, a punch outer sleeve 64,
It has a mandrel 65 and a kickout sleeve 66 and is hexagonally formed to form the body W6 (FIGS. 6 and 7).

Each die 11.21.31.41.51.61 is integrally incorporated into a fixing member a of the cold extrusion molding machine A. Also, each punch 12.22.32.42.52
．． 62 is integrally incorporated into the movable member of the cold extrusion molding fiA.

In addition, inside the recess of each die 11.21.31.41.51.61 and each punch 12.22.32.42.52.
62 and the body, there is a means (not shown) for constantly supplying cooling air and cooling oil to cool the contact surface.
Powered by.

The transfer means has fingers or the like for gripping the body, and is used to transfer the body from the die of the forming section in the previous step to the die of the forming section in the second step.

A method of manufacturing the metal shell for a spark plug of this embodiment will be explained based on FIGS. 1 to 8.

(a) Round rod-shaped body cut from steel (not shown)
is transferred by the transfer means to the entrance of the recess of the die 11 of the first molding section 1 in a substantially parallel direction without being reversed, and is held at the entrance of the recess of the die 11.

As the movable member of the cold extrusion molding machine A moves downward in the figure toward the fixed member a, the punch 12 press-fits the round rod-shaped body into the recess of the die 11.

The round rod-shaped body press-fitted into the recess of the die 11 has an arc-shaped corner 10 formed by the die 11 in the first molding part 1.
1 is formed, and centering small holes 102 and 103 are formed on the axes of both end surfaces by the tip of the punch 12 and the tip of the kickout bin 13. Therefore, the first molding section 1
In the first step, by cold extrusion molding as described above,
The fuselage W1 shown in the figure is formed.

The punch 12 is separated from the body W1 by moving the movable member of the cold extrusion molding fiA away from the fixed member a in the direction shown in the figure. At this time, kickout bin 13
The body W1 is taken out from within the recess of the die 11.

(b) Next, the body W1 formed by the first molding part 1
is transferred by the transfer means from the first molding section 1 to the entrance of the recess of the die 21 of the second molding section 2 in a substantially parallel direction without being reversed, and is held at the entrance of the recess of the die 21.

The punch 22 presses the body W1 into the recess of the die 21 by moving the movable member of the cold extrusion molding machine A downward in the figure toward the fixed member a.

The body W1 press-fitted into the recess of the die 21 has a large diameter portion 104 formed by the die 21 in the second molding part 2.
A small-diameter portion 105 is formed, and large centering holes 106 and 107 are formed at the axes of both end surfaces by the tip of the punch 22 and the tip of the bottle 23. Therefore, in the second molding section 2, the body W2 shown in FIG. 2 is formed by cold extrusion molding as described above.

As the movable member of the cold extrusion molding machine A moves away from the fixed member a and moves upward in the figure, the punch 22 separates from the body W2. At this time, the kickout sleeve 24
The body W2 is removed from the recess of the die 21.

(c) Next, the fuselage W2 formed by the second molding part 2
is transferred by the transfer means from the second molding section 2 to the entrance of the recess of the die 31 of the third molding section 3 in a substantially parallel direction without being reversed, and is held at the entrance of the recess of the die 31.

The punch 32 presses the body W2 into the recess of the die 31 by moving the movable member of the cold extrusion molding machine A downward in the figure toward the fixed member a.

In the body W2 press-fitted into the recess of the die 31, a first cylindrical part 10 having a circular cross section and a smaller diameter than the other part 108 is formed on one side of the body W2 by the die 31 in the third molding part 3.
9 is formed. Further, a hole 110 is formed on the axis of both end faces of C1 by the tip of the punch 32 and the tip of the bottle 34.
111 is formed. Therefore, in the third molding section 3, the body W3 shown in FIG. 3 is formed by cold extrusion molding as described above.

As the movable member of the cold extrusion molding machine A moves away from the fixed member a and in the direction shown in the figure, the punch 32 separates from the body W3. At this time, kickout sleeve 3
5, the body W3 is taken out from within the recess of the die 31.

(d) Next, the fuselage W3 formed by the third molding section 3
is transferred by the transfer means from the third molding section 3 to the entrance of the recess of the die 41 of the fourth molding section 4 in a substantially parallel direction without being reversed, and is held at the entrance of the recess of the die 41.

As the movable member of the cold extrusion molding machine A moves downward in the figure toward the fixed member a, the punch 42 press-fits the body W3 into the recess of the die 41 and into the gap between the die 41 and the bottle 43.

In the body W3 press-fitted into the recess of the die 41 and the gap between the die 41 and the bottle 43, a stepped hole 112 is formed inside one side of the body W3 by the punch 42 in the fourth molding part 4.
is formed. Therefore, in the fourth molding section 4, the body W4 shown in FIG. 4 is formed by cold extrusion molding as described above.
is formed.

By moving the movable member of the cold extrusion molding machine A away from the fixed member a and moving upward in the drawing, the punch 42 separates from the upper end surface of the body W4 in the drawing. At this time, the body W4 is removed from the recess of the die 41 by the kick-out sleeve 44.

(e) Next, the fuselage W4 formed by the fourth molding part 4
is transferred by the transfer means from the fourth molding section 4 to the entrance of the recess of the die 51 of the fifth molding section 5 in a substantially parallel direction without being reversed, and is held at the entrance of the recess of the die 51.

The punch 52 presses the body W4 into the recess of the die 51 by moving the movable member of the cold extrusion molding machine A downward in the figure toward the fixed member a.

In the body W4 press-fitted into the recess of the die 51, a shaft hole 113 is formed inside the body W4 by a punch 62 in the fifth molding part 5, and passes through the body W4 in the axial direction. At this time, the discharged scraps are discharged to the outside through the scrap discharge section 54. Therefore, in the fifth molding section 5, the body W5 shown in FIG. 5 is formed by cold extrusion molding as described above.

As the movable member of the cold extrusion molding machine A moves away from the fixed member a and moves downward in the figure, the punch 52 separates from the body W5. At this time, the kickout sleeve 53
The body W5 is removed from the recess of the die 51.

) Next, the fuselage W5 formed by the fifth molding part 5
is transferred by the transfer means from the fifth molding section 5 to the entrance of the recess of the die 61 of the sixth molding section 6 with its vertical direction reversed, and is held at the entrance of the recess of the die 61.

By moving the movable member of the cold extrusion fiA toward the fixed member a, the punch 62 press-fits the body W5 into the recess of the die 61, and the body 5
The other side of the bunch outer sleeve 64 is press-fitted into the bunch outer sleeve 64.

The body W5 press-fitted into the recess of the die 61 and into the punch outer sleeve 64 has the die 61, the mandrel 65 and the punch outer sleeve 6 in the sixth molding section 6.
4, a second cylindrical portion 115 having a smaller diameter than the central portion 114 and a hexagonal cross section is formed on the other side of the body W5.

Therefore, in the sixth molding section 6, the body W6 shown in FIG. 6 is formed by cold extrusion molding as described above.

By moving the movable member of the cold extrusion molding 1fiA away from the fixed member a and moving upward in the figure, it is kicked out by the bunch kickout sleeve 63, and the punch 62, punch kickout sleeve 63, and punch outer sleeve 64 are removed from the body W6. move away from

At this time, the body W6 is removed from the recess of the die 61 by the kick-out sleeve 66.

As described above, by performing the second process by the sixth forming part 6 after the first process by the fifth forming part 5, the fuselage W
When the punch 62 and mandrel 65 are inserted into the shaft hole 113 of No. 5, the punch outer sleeve 64
Even when the convex portion 115 is constricted, cooling air and cooling oil from the inner peripheral portion of the second cylindrical portion 115 gather in the gap 116 that is not closed by the punch 62 and the mandrel 65 in the shaft hole 113. Therefore, since cooling air and cooling oil are not present in the inner circumferential portion of the second cylindrical portion 115, no dents are generated on the inner circumferential surface of the second cylindrical portion 115 of the body W6.

Further, when the present invention is adopted as a method for manufacturing a metal shell for a spark plug as in this embodiment, the metal shell 100 and the insulator 72 are assembled by caulking the rear end portion 121 of the metal shell 100. Also, since no dent occurs on the inner circumferential surface of the second cylindrical portion 115 of the body W6, the metal shell 100 as shown in FIG.
When the rear end portion 121 is caulked, wrinkles can be prevented from forming on the outer periphery of the caulking groove portion 125.

Note that processing can be performed without the punch 62 inserted into the punch kickout sleeve 63, and in this case, the gap 116 becomes larger and the problem can be solved.

(G) The body W6 formed by extrusion molding as described above has a thread 122 formed on the outer periphery of the first cylindrical part 109, and a second cylindrical part 109, as shown in FIG. 115
By cutting the circular part 1, which has a smaller diameter than the hexagonal part 123.
24, the caulking groove portion 125 is formed, and the metal shell 100 is manufactured. And, at the tip of this metal shell 100,
The outer electrode 126 of any shape is attached by a joining method such as welding.

Then, by integrally assembling the central fji 71, the insulator 72, etc. inside the metal shell 100 manufactured by the manufacturing method described above, a cylinder head of a gasoline engine as shown in FIG. A spark plug 7 is manufactured which is attached to a recess formed in an outer wall.

FIG. 11 represents a second embodiment of the present invention, and shows a cold extrusion molding machine for molding a body by a method for manufacturing a metal shell for a spark plug.

(Same as the first embodiment - Functional objects are given the same numbers) The cold extrusion molding ff1B of this embodiment has a formwork (first die) 81
, mandrel 82, kickout sleeve 83, punch outer sleeve (second die) 84, pin 85, pin kickout sleeve 86, and bin outer sleeve 87
It faces the sixth molded part 8 which has a shape of 1.

In this embodiment, in addition to the same effect as the first embodiment, the body W5 formed in the fifth forming section 5 of the cold extrusion molding machine B is transferred in a parallel direction to the sixth forming section 8 without reversing. By doing so, collision between the vicinity of the end of the body 5 and the vicinity of the recess of the second die 84 of the sixth molding part 8 can be prevented, so that the vicinity of the 4, 1 part of the body or the recess of the second die 84 can be prevented. Damage to nearby areas can be prevented.

Furthermore, for example, even when the body W5 is transferred from the mold (die) 51 of the fifth molding section 5 to the second die 81 of the sixth molding section 8 at high speed, the body W5 may be blown outward due to centrifugal force. There is no possibility of it happening. Therefore, it is possible to increase the transfer speed of the fuselage W5, thereby improving the productivity of the metal shell 100.

[Other Examples] In this example, the hexagonal second end portion was formed on the body in the sixth molding part, but the hexagonal second end portion may be formed on the body at any time after forming the shaft hole. can be formed.

That is, the cold extrusion molding machine is not limited to the cold extrusion molding machine of this embodiment as long as it is a cold extrusion molding machine that manufactures a metal shell using a manufacturing method that includes a first step and a second step.

In this example, extrusion molding was performed from the same direction between the first step and the second step, but extrusion molding may be performed from the opposite direction between the first step and the second step.

In this embodiment, the present invention was adopted as a method for manufacturing a main metal fitting for a spark plug. Adopted in the manufacturing method of the metal shell having the second cylindrical part and the shaft hole.
Also good.

[Brief explanation of drawings]

1 to 10 represent a first embodiment of the present invention. Figures 1 to 6 are cross-sectional views showing the molded shape of the fuselage in each molding section, Figure 7 is a bottom view of Figure 6, and Figure 8 is a molding of the fuselage by the method for manufacturing a metal shell for a spark plug. It is a sectional view showing a cold extrusion molding machine. FIG. 9 is a half-sectional view showing the metal shell for the spark plug, and FIG. 10 is a half-sectional view showing the spark plug. FIG. 11 represents a second embodiment of the present invention, and is a sectional view showing a cold extrusion molding section for molding a body by a method of manufacturing a metal shell for a spark plug. Figures 12 and 13 are cross-sectional views showing a molding machine that molds a fuselage using a conventional manufacturing method, and Figure 14 is A of Figure 13.
- It is a sectional view showing a fuselage in which a recess is formed by cutting A. A in the figure...Cold extrusion molding machine 1...First molding section 2.
...Second molding section 3...Third molding section 4...Fourth molding section 5...Fifth molding section (molding section that performs the 1st step)
6.8...Sixth molding section (molding section that performs the second process)
7... Spark plug 100... Main metal fitting for spark plug 11
5...Second cylindrical part (cylindrical part) Wl, W2, W3, W
4, W5, W6...fuselage

Claims (1)

[Scope of Claims] 1) A first step of forming a shaft hole passing through the body in the axial direction by extrusion molding; a second step of forming a cylindrical portion having a diameter smaller than the diameter of the central portion and a hexagonal cross section.