JPH0420714A - Manufacture of main metallic member for glow plug - Google Patents

Abstract

PURPOSE:To raise the dimensional accuracy of a completed product and prevent the exclusion die from breakage by providing a first work process in which on one endface of a round rod-shaped cylindrical body a first recessed section is formed, second work process in which on the other end face of the cylindrical body a second recessed section is formed and at the same time on the side of the other end a hexagonal section is formed, third work process in which in the hexagonal inside a third recessed section is formed, and fourth work process in which a shaft hole is formed that pierces through the first recessed section and the third recessed section. CONSTITUTION:In the first work process on one end face of a round rod-shaped cylindrical body a first recessed section 113 is formed by extrusion. At this time on the other end face of the cylindrical body a recessed section is not formed. Next, in the second work process on the other end face of the cylindrical body (b) a second recessed section 137 with a diameter larger than that of the first recessed section is formed and at the same time a hexagonal section 132 is formed by upsetting. And since in the third work process third recessed sections 149 and 159 are formed by extrusion in this hexagonal section, the inner circumferential face of the third recessed section is never deformed. With this arrangement when in the fourth work process both the first recessed section and the third recessed section are connected and they are pierced in the axial direction to form an axial hole 15 by punching, there is not fluctuation in the inner diameters of the axial hole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a metal shell for a glow plug used in a diesel engine, and particularly to a method of manufacturing a metal shell having a hexagonal portion.

[Prior Art] Japanese Patent Publication No. 2-6412 discloses a first step of thinning the inner diameter of a part of the pipe material by extrusion molding of the cut pipe material, and thinning the outer diameter. A manufacturing method is described that includes a second step of forming a hexagonal portion on one side of the pipe material.

In addition, conventionally, as a manufacturing method for a main metal fitting for a glow plug, a shaft hole of the desired inner diameter to be obtained in the final process is made in the end of a rod-shaped material cut to a regular length using an extrusion molding tool such as a punch or pin. There is also a manufacturing method that includes one step, a second step of reducing the outer diameter of the material by extrusion molding, and a third step of forming a hexagonal portion on one side of the pipe material with the reduced outer diameter.

[Problems to be Solved by the Invention] However, in the former manufacturing method, when the pipe material is cut out, burrs and the like remain on the inner circumferential end, making it difficult to cut out the pipe material into a constant volume. For this reason,
Since the dimensional accuracy of the molded product in the axial direction deteriorates, there is a problem that the dimensional accuracy of the finished product in the axial direction deteriorates.

In addition, in the former and latter manufacturing methods, when forming one side of the material and pipe material into a hexagonal shape, even if an extrusion molding tool such as a mandrel is inserted into the material and pipe material, the material and pipe material will deform. As a result, sink marks occur on the inner peripheral surfaces of the raw material and pipe material. As a result, the inner circumferential surface of the molded product (raw material and pipe material) becomes distorted, resulting in a problem in that the dimensional accuracy of the inner diameter of the shaft hole in the finished product deteriorates.

Furthermore, in the latter manufacturing method, it is necessary to make a shaft hole in the end of the material in the first step with the inner diameter desired in the final step, so it is necessary to use a punch or pin with a small diameter. Therefore, when drilling the shaft hole, a large stress is generated in the punch or pin, which may cause the punch or pin to break or crack.

An object of the present invention is to provide a method for manufacturing a main metal fitting for a glow plug, which can improve the dimensional accuracy of the finished product. A further object of the present invention is to provide a method for manufacturing a main metal fitting for a glow plug that can prevent damage to the extrusion molding tool.

[Means for Solving the Problems] (Claim 1) The method for manufacturing a metal shell for a glow plug of the present invention includes a first step of forming a first recess in one end surface of a round bar-shaped body by extrusion molding; A second recess having a diameter larger than the first recess is formed on the other end surface of the fuselage by upsetting, and a hexagonal portion having a diameter larger than the fuselage on the other end of the fuselage.
a third step of forming a third recess in the hexagonal portion by extrusion molding; and a shaft hole that communicates the first recess and the third recess and passes through the body in the axial direction by punching. The fourth forming
It has a process.

(Claim 2) The first recess is formed to have substantially the same diameter as the shaft hole by forming the recess in one end surface of the body and then narrowing the inner diameter of the recess.

[Operation] (Claim 1) In the first step, a first recess is formed in one end surface of the round bar-shaped body by extrusion molding. At this time, no recess is formed on the other end surface of the body.

Subsequently, in a second step, a second recess having a diameter larger than the first recess is formed on the other end of the fuselage, while a hexagonal portion having a diameter larger than the fuselage is formed on the other end of the fuselage by upsetting. Then, in the third step, the third recess is formed within this hexagonal portion by extrusion molding, so that the inner circumferential surface of the third recess does not become distorted.

Therefore, in the fourth step, when the shaft hole that communicates the first recess and the third recess and passes through the body in the axial direction is formed by punching, the inner diameter of the shaft hole will not be uneven.

Further, since the round bar-shaped body is used in this way, it is very easy to cut out the body to a certain volume, and the axial dimension of the molded product becomes constant.

(Claim 2) A relatively large recess is formed in one end surface of the body, and then a first recess having approximately the same diameter as the shaft hole is formed, so that the recess is relatively large with respect to the diameter of the body. It becomes possible to form. Therefore, no large stress is generated in the extrusion molding tools such as punches or pins that form large recesses. Therefore, when forming a recess on one end surface of the round rod-shaped body, the extrusion molding tool such as a punch or pin will not break or crack.

[Effects of the Invention] (Claim 1) Since the inner diameter of the shaft hole does not become uneven and the axial dimension of the molded product does not become long, the dimensional accuracy of the finished product can be improved.

(Claim 2) Since the stress generated in the extrusion molding tool such as a punch or bottle is smaller than that in conventional manufacturing methods, damage to the extrusion molding tool such as the punch or bottle can be suppressed.

[Example] A method of manufacturing a main metal fitting for a glow plug according to the present invention will be described based on an example shown in the drawings.

1 to 18 show a first embodiment of the present invention. 1 to 12 show the state of molding the body, and FIGS. 13 to 17 show each molding section of the cold extrusion molding machine.

The cold extrusion molding machine includes first to fifth molding sections 1 to 5 arranged linearly.

The first molding section 1 is a molding section that performs the first step of the present invention, and has a die 11, a punch 12, a bottle 13, and a kickout sleeve 14, as shown in FIG. The first molding section 1 extrudes the body a (FIGS. 1 and 2) to form the body b (FIGS. 3 and 4).

The second molding section 2 is a molding section that performs the first step of the present invention, and has a die 21, a punch 22, a bottle 23, and a kickout sleeve 24, as shown in FIG. This second molding section 2 is made by extrusion molding the fuselage C (fifth
and FIG. 6).

The third molding section 3 is a molding section that performs the second step of the present invention, and has a die 31, a punch 32, a punch holder 33, a bottle 34, and a kickout sleeve 35, as shown in FIG. This third molding section 3 is.

Upload molding of fuselage C to obtain fuselage d (Figures 7 and 8)
form.

The fourth molding section 4 is a molding section that performs the third step of the present invention, and has a die 41, a punch 42, a punch holder 43, a bottle 44, and a kickout sleeve 45, as shown in FIG. This fourth molding section 4 extrudes the body d to form the body e (FIGS. 9 and 1O).

The fifth molding section 5 is a molding section that performs the fourth step of the present invention, and has a die 51, a punch 52, and a kickout sleeve 53, as shown in FIG.

This fifth molding section 5 is formed by punching and molding the body e and the body f (
11 and 12).

Each die 11.21.31.41.51 is integrally incorporated into a fixed member (not shown) of the cold extrusion molding machine. Also, each punch 12.22.32.42.5
2 shows a method of manufacturing a main metal fitting for a glow plug according to the sixth embodiment, which is integrated into a movable member (not shown) that moves back and forth in a cold extrusion molding machine, based on FIGS. 1 to 18. explain.

■, a round bar-shaped body a with predetermined dimensions from the first extruded steel (SIOC)
cut. As described above, since the round bar-shaped body a is used to manufacture the main metal fitting for the glow plug, it is very easy to cut out the body a into a certain volume, and the axial dimension of the molded product is constant. The dimensional accuracy of the finished product is improved.

The round rod-shaped body a is transferred to the entrance of the die 11 of the first molding section 1 by a transfer device (not shown), and is held at the entrance of the die 11.

Then, as the movable member moves downward in the figure toward the fixed member, the body a is moved to the die 11 by the punch 12.
inserted within.

The body a inserted into the die 11 is formed into a round rod shape with a predetermined diameter and a predetermined length.

At the same time, a recess 113 is formed on the axis of one end surface by the bottle 13.
is formed.

Therefore, in this first molded part 1, the first end 111 has a cylindrical cross section and the second end 11 has a circular cross section.
2 is formed.

Then, as the movable member separates from the fixed member and moves upward in the figure, the punch 12 separates from the body, and the kick-out sleeve 14 kicks the body out of the die 11.

(2) Second extrusion process The body formed by the first molding part 1 is transferred from the inlet of the die 11 of the first molding part 1 to the inlet of the die 21 of the second molding part 2 by a transfer device. is held at the entrance of the

Then, by moving the movable member toward the fixed member downward in the figure, the punch 22 causes the fuselage cutter die 21 to
inserted within.

The die 21 forms a first end portion 121 on one side (lower side in the figure) of the fuselage insert inserted into the die 21, which has a smaller diameter than the fuselage. Also, the tapered portion 12 is formed between the first end portion 121 and the second end portion 122 by the die 21.
3 is formed.

At the same time, a recess 113 is formed on the axis of one end surface by the pin 23.
In order to form a more elongated first recess 124, the second molded part 2 has a first end 1 having a cylindrical cross section.
21 and a second end portion 122 having a circular cross section is formed.

Then, as the movable member separates from the fixed member and moves upward in the drawing, the punch 22 separates from the body C, and the body C is kicked out from within the die 21 by the kick-out sleeve 24.

(2) Upsetting process The body C formed by the second forming section 2 is transferred from the inlet of the die 21 of the second forming section 2 to the inlet of the die 31 of the third forming section 3 by a transfer device. held at the entrance.

Then, as the movable member moves downward in the figure toward the fixed member, the punch 32 moves the body C toward the die 31.
inserted within.

The body C inserted into the die 31 has a hexagonal outer shape with a larger diameter than the center part 133 having approximately the same diameter as the second end part 122 at the other end (the upper end in the drawing) of the body C inserted into the die 31. Two end portions (hexagonal shaped portions) 132 are formed. Furthermore, a first tapered portion 134 is formed between the first end portion 131 and the central portion 133 by the die 31, and a second tapered portion 135 is formed between the second end portion 132 and the central portion 133.

At the same time, a first recess 136 having substantially the same dimensions as the first recess 124 is formed on the axis of one end surface of the body C by the pin 34, and a first recess 136 having substantially the same dimensions as the first recess 124 is formed on the axis of the other end surface of the body C by the punch 32 and the bunch holder 33. A second recess 137 having a slightly larger diameter than the first recess 136 is formed.

Therefore, in this third molding section 3, a plurality of stepped bodies each having a first end 131 having a circular outer shape, a central portion 133 having a circular outer shape, and a second end 132 having a hexagonal outer shape are formed. d is formed.

Then, as the movable member moves upward in the figure while being shielded from the fixed member, the punch 32 separates from the body d, and the body d is kicked out from within the die 31 by the kick-out sleeve 35.

(3) Third extrusion process The body d formed by the third forming section 3 is transferred from the inlet of the die 31 of the third forming section 3 to the inlet of the die 41 of the fourth forming section 4 by the transfer device. held at the entrance.

As the movable member moves downward in the figure toward the fixed member, the body d is inserted into the die 41 by the punch 42.

The first end 141 of the body d inserted into the die 41 is formed at one end of the body d by the die 41, the first end 141 having a smaller diameter than the first central part 143 having approximately the same diameter as the first end 131.

Also, the first end portion 141 and the first central portion 1 are formed by the die 41.
A first tapered portion 145 is formed between the first central portion 143 and the second central portion 144, and a second tapered portion 145 is formed between the first central portion 143 and the second central portion 144.
6 is formed, and a third tapered portion 147 is formed between the second end portion 142 and the second central portion 144.

At the same time, a first recess 148 having substantially the same dimensions as the first recess 136 is formed on the axis of one end surface of the body C by the pin 44, and a second recess 137 is formed on the axis of the other end surface of the body C by the punch 42. A third recess 149 having a larger diameter is formed.

Therefore, in this fourth molded part 4, a first end part 141 having a circular outer shape, a first central part 143 having a circular outer shape,
A second central portion 144 and a second end portion 14 having a hexagonal outer shape.
A plurality of stepped fuselage e having 2 is formed.

That is, since the hexagonal second end 142 is formed while forming the third recess 149, there is sufficient volume of the body d to form the second end 142.
The inner peripheral surface of the body e is not distorted.

As the movable member separates from the fixed member and moves upward in the drawing, the bunch 42 separates from the upper end surface of the body e in the drawing,
The body e is kicked out from inside the die 41 by the kick-out sleeve 44.

(2) Punching process The body e formed by the fourth forming section 4 is transferred from the inlet of the die 41 of the fourth forming section 4 to the inlet of the die 51 of the fifth forming section 5 by the transfer device. is held in

As the movable member moves downward in the figure toward the fixed member, the punch 52 punches the first end 141 of the body e;
The first central portion 143 and the second central portion 144 are inserted into the die 51 .

The body e inserted into the die 51 has a reverse portion 151 having the same diameter as the first end portion 141 and a first central portion 14.
3, the first central portion 153 and the second central portion 144 have approximately the same diameter.
A second central portion 154 having approximately the same diameter is formed.

Furthermore, the opposite part 151 and the first central part 15 are formed by the die 51.
A first tapered portion 155 is formed between the first central portion 153 and the second central portion 154, and a second tapered portion 156 is formed between the first central portion 153 and the second central portion 154.
A third tapered portion 157 is formed between the head portion 152 having the same shape as the second end portion 142 and the second central portion 154 .

At the same time, the bunch 52 connects a first recess 158, which has approximately the same size as the first recess 148, and a third recess 159, which has approximately the same size as the third recess 149, to form a shaft hole 150 that axially passes through the body e. is formed.

Therefore, in the fifth molding part 5, a plurality of steps are formed, each having a reverse part 151 having a circular outer shape, a first central part 153 and a second central part 154 having a circular outer shape, and a head 152 having a hexagonal outer shape. A fuselage f is formed.

As the movable member separates from the fixed member and moves upward in the figure, the punch 52 separates from the body f, and the body f is kicked out from within the die 51 by the kick-out sleeve 53.

The body f formed by extrusion molding as described above is
A screw 72 is attached to the outer periphery of the first central portion 153 (see Fig. 18).
etc. are formed to manufacture the finished product, that is, the cylindrical metal shell 1.

FIG. 18 is a diagram showing a glow plug 8 for a diesel engine incorporating the cylindrical metal shell 7 manufactured by the manufacturing method of this embodiment.

The glow plug 8 is composed of a cylindrical metal shell 7, a heat-resistant metal tube 81, a center electrode 82, a heating coil 83, an insulating powder 84, and the like manufactured by the manufacturing method of this embodiment. The main metal fitting 7 includes a reverse portion 71 having a circular outer shape, and a first central portion 73 having a circular external thread 72.
, a second central portion 74 having a circular outer shape, and a head 75 having a hexagonal outer shape. The metal shell 7 also has a shaft hole 76 that penetrates the inside in the axial direction.

FIG. 19 shows a second embodiment of the present invention, and shows the state of the fuselage molded by the improved first molding section.

(The same parts as in the first example are given the same numbers.) In this example, a large recess (55% to 60% of the diameter of the body a) is formed on the axis of one end surface of the body a by the first extrusion process. diameter)
161, a second extrusion process is performed to narrow the inner diameter of the recess 161 and the diameter of the first end 111, thereby forming a hole with approximately the same diameter as the shaft hole 150 on the axis of one end surface of the body seat. Since one recess 136 is formed, the recess 161 can be formed relatively large with respect to the diameter of the body a.

Therefore, no large stress is generated in the bottle 23 forming the recess 161.

Therefore, since the stress generated in the bottle 23 during the first extrusion process is reduced, the bottle 23 will not break or crack.

(Modification) The extrusion molding machine is not limited to the cold extrusion molding machine of this embodiment as long as it is an extrusion molding machine that sequentially performs the first step, second step, third step, and fourth step.

[Brief explanation of drawings]

Figures 1 to 18 show the first embodiment of the present invention. Figures 1 to 12 are sectional views showing the molded shape of the body in each molding section. Figures 13 to 17 are cold extrusion. It is a sectional view showing each molding part of a molding machine. FIG. 18 is a half sectional view showing the glow plug. FIG. 19 shows a second embodiment of the present invention, and is a sectional view showing a molded state of a fuselage molded by another first molding section. In the diagram

Claims (1)

[Claims] 1) (a) A first step of forming a first recess on one end surface of the round rod-shaped body by extrusion molding; (b) forming a first recess on the other end surface of the body by upsetting molding; a second step of forming a hexagonal portion having a diameter larger than the body on the other end side of the body while forming a second concave portion having a diameter larger than the first concave portion; (c) forming a hexagonal portion within the hexagonal portion by extrusion molding; a third step of forming a third recess in the body; and (d) a fourth step of forming a shaft hole that communicates the first recess and the third recess and axially penetrates the body by punching. A method for manufacturing a main metal fitting for a glow plug. 2) The first recess is formed to have substantially the same diameter as the shaft hole by forming the recess in one end surface of the body and then narrowing the inner diameter of the recess.
A method for manufacturing a main metal fitting for a glow plug described in .