JP2965360B2 - Manufacturing method of metal shell for glow plug - 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 metal shell for a glow plug.

[0002]

2. Description of the Related Art In Japanese Patent Publication No. 2-6412,
A method (prior art) of manufacturing a metal shell for a glow plug by plastically processing a pipe material has been proposed.
This conventional technique involves cutting a pipe material at a predetermined axial dimension to obtain a cylindrical body, and inserting a metal core inside the cylindrical body to reduce the diameter of one side of the cylindrical body. A first drawing step of forming a first tubular body, and a second tubular body formed by inserting a metal core into the inside of the first tubular body to further reduce the diameter of one side of the first tubular body. The method includes a secondary drawing process for forming the material, and a forming process for forming a hexagonal portion to be engaged with a tool such as a wrench on the other end of the second tubular body.

[0003]

However, in the prior art, since an expensive pipe material is used, the cost is higher than a method of cutting a solid material having a circular cross section to obtain a cylindrical body. There was a problem of being bulky. Further, in the prior art, when cutting a pipe material to a desired size, the accuracy of the cut size is poor. Therefore, it was necessary to give a large amount of cutting allowance after molding. Further, since the cutting dimensions are varied, in the process of forming a hexagonal part to be engaged with the tool, there is a serious difficulty that the tool is broken when the cutting dimension is long and the hexagonal part is not formed well when the cutting dimension is short. Had occurred.

An object of the present invention is to provide a method of manufacturing a metal shell for a glow plug which is economical and can achieve uniform dimensional accuracy.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a first step of cutting a solid metal material having a circular cross section at a predetermined axial dimension to obtain a solid body; A second step of forming a hole to form a cylindrical body, and a third step of reducing the diameter of one end of the cylindrical body and increasing the axial dimension of the cylindrical body to obtain a cylindrical body, A fourth step of forming an engaged portion to be engaged with a tool on the other end side of the tubular body.

[0006]

By cutting a solid metal material having a circular cross section at a predetermined axial dimension, a solid body having no hole therein can be obtained. Then, a cylindrical body is obtained by forming an axial hole inside the solid body. Then,
By reducing the diameter of one end of the cylindrical body and increasing the axial dimension of the cylindrical body, a cylindrical body can be obtained. And
An engaged portion to be engaged with the tool is formed on the other end side of the tubular body, and a metallic shell for a glow plug is obtained. in this way,
Since the solid material is cut, there is almost no variation in cutting dimensions, and there is no problem in forming an engaged portion to be engaged with the tool.

[0007]

According to the present invention, the use of an inexpensive metal solid material having a circular cross section and cut at a predetermined axial dimension by use of a solid material makes it possible to compare with the prior art which uses an expensive pipe material. As a result, the dimensional accuracy of each metal shell can be made uniform, so that the method of manufacturing a metal shell for a glow plug is suitable for mass production.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a metal shell for a glow plug according to the present invention will be described with reference to an embodiment shown in FIGS. FIGS. 1 to 8 show a first embodiment of the present invention, and FIGS. 1 and 2 are views showing the shape of a molded product at the end of each manufacturing step of the method for manufacturing a metal shell for a glow plug. FIG. 7 to FIG. 7 show the respective manufacturing steps, and FIG. 8 shows a glow plug for a diesel engine.

The glow plug 1 for a diesel engine is:
As shown in FIG. 8, a cylindrical metal shell 3 having an axial hole 2 therein, a tube 4 attached to the distal end of the metal shell 3, and a center electrode 5 inserted in the tube 4.
And a heating coil 6 connected between the tip of the center electrode 5 and the inner peripheral surface of the tube 4, and an insulating powder 7 filled in the tube 4.

Hereinafter, a method of manufacturing the metal shell 3 of the glow plug 1 for a diesel engine will be described with reference to FIGS. The cutting step corresponds to the first step of the present invention,
The punching step corresponds to the second step of the present invention, the drawing step corresponds to the third step of the present invention, and the hexagonal section forming step corresponds to the fourth step.

(Cutting Step) By cutting an inexpensive round solid or coil-shaped metal solid material (not shown) having a circular cross section with a predetermined axial dimension, the cutting process shown in FIG.
As shown in (A), a solid body 8 having no internal hole is obtained. For this reason, the solid body 8 is very economical as compared with the conventional technique of obtaining a material from an expensive pipe material, and has a good precision in cutting dimensions.

(First Composite Molding Step) As shown in FIG.
When the cut solid body 8 is brought to the entrance of the die 9,
It is inserted into the die 9 by the punch 10. Then, the solid body 8 is first composite-molded by the die 9, the punch 10, the punch holder 11, the pin 12, and the kickout sleeve 16, so that the recess 13 is formed on one end surface as shown in FIG. A recess 14 having the same diameter and the same size as the recess 13 is formed on the other end surface. Then, the solid body 15 formed in the first composite forming step is kicked out by the kickout sleeve 16.

(Second Composite Molding Step) As shown in FIG.
When the solid body 15 is carried to the entrance of the die 17, it is inserted into the die 17 by the punch 18. Then die 1
7, the solid body 15 is formed by the second composite molding with the punch 18, the punch holder 19, the pin 20, and the kick-out sleeve 24, so that a recess deeper than the recess 13 is formed on one end surface as shown in FIG. A recess 22 having the same diameter and the same size as the recess 21 is formed on the other end surface.
Then, the solid body 23 formed in the second composite forming step is kicked out by the kickout sleeve 24.

(Punching Step) As shown in FIG. 5, when the solid body 23 is carried to the entrance of the die 25, it is inserted into the die 25 by the punch 26. Then, by punching the solid body 23 by the punch 26 and the tubular member 28, a cylindrical body 30 having an axial hole 29 penetrating in the axial direction is formed as shown in FIG. At this time,
The piece discharged from the cylindrical body 30 is discharged to the outside through the discharge hole 31.

(Draw-Forming Step) As shown in FIG. 6, when the cylindrical body 30 is carried to the entrance of the die 32, the punch 3
3 and the punch holder 34 are inserted into the die 32. Then, the cylindrical body 30 is drawn by the die 32, the punch 33, and the punch holder 34 to thereby reduce the diameter of the leg 36 at one end to the head 37 at the other end, as shown in FIG. Thinner, longer axial dimension,
A tubular body 40 having an axial hole 39 with a step 38 therein is formed. Then, the cylindrical body 40 formed in the drawing step is kicked out by the kickout pin 35.

(Hexagonal Forming Step) As shown in FIG. 7, when the tubular body 40 is carried to the entrance of the die 41, it is inserted into the die 41 by the punch 42 and the punch holder 43. Then, the die 41, the punch 42, the punch holder 43, and the kickout pin 44 cause the tubular body 4 to move.
By forming a hexagonal part 0, as shown in FIG. 1 (F) and FIG.
The diameter of the distal end portion 47 of the leg portion 46 at one end is made smaller than that of the central portion 48, and a hexagonal portion 50 as an engaged portion to be engaged with a tool such as a wrench is formed at the head 49 at the other end. The metal shell 51 is formed. Then, after the metal shell 51 formed in the hexagonal part forming step is kicked out by the kickout pin 44, cutting is performed to form an outer peripheral screw 52 as shown in FIG.

As described above, in this embodiment, since the cylindrical body 40 is formed from the solid body 8 and the solid material is cut, the variation in the axial dimension of the solid body 8 is small. Therefore, the metal shell 3 having a shape with good dimensional accuracy of the hexagonal portion 50 can be easily formed. Therefore, a manufacturing method suitable for mass production can be provided as a manufacturing method of the metal shell 3 of the glow plug 1 for a diesel engine.

FIGS. 9 to 11 show a second embodiment of the present invention, and show the molded shapes of the molded articles at the end of the first composite molding step, at the end of the second composite molding step, and at the end of the punching step. is there.

As in this embodiment, at the time of the first and second composite molding steps and the punching step, the recesses 54, 5
Even when the solid bodies 60, 61 and the cylindrical body 62 in which the recesses 57, 58, 59 on the other end side are larger than the diameters of 5, 56 are formed,
The same effects as in the first embodiment can be obtained.

(Modification) In the present embodiment, the first composite molding step and the second composite molding step were performed. However, the first composite molding step may be omitted as long as the second composite molded body can be formed from a solid body. . In the present embodiment, the hexagonal portion is formed as the engaged portion, but any shape may be formed as long as the shape engages with the tool.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a molded shape of a molded product at the end of each manufacturing process of a first embodiment.

FIG. 2 is a cross-sectional view showing a molded shape of a metal shell at the end of a hexagonal portion forming step of the first embodiment.

FIG. 3 is a sectional view showing a first composite molding step of the first embodiment.

FIG. 4 is a sectional view showing a second composite molding step of the first embodiment.

FIG. 5 is a sectional view showing a punching step of the first embodiment.

FIG. 6 is a cross-sectional view showing a draw forming step of the first embodiment.

FIG. 7 is a sectional view showing a hexagonal portion forming step of the first embodiment.

FIG. 8 is a half sectional view showing a glow plug for a diesel engine.

FIG. 9 is a cross-sectional view showing a molded shape of a molded article at the end of a first composite molding step of the second embodiment.

FIG. 10 is a cross-sectional view showing a molded shape of a molded article at the end of a second composite molding step of the second embodiment.

FIG. 11 is a cross-sectional view showing a molded shape of a molded product at the end of a punching step according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glow plug for diesel engines 3, 51 Metal shell 8 Solid body 29 Axial hole 30 Cylindrical body 40 Cylindrical body 50 Hexagonal part (engaged part)

Claims (1)

(57) [Claims] 1. A first step of cutting a solid metal material having a circular cross section at a predetermined axial dimension to obtain a solid body, and (b) forming an axial hole inside the solid body. A second step of forming a cylindrical body to form a cylindrical body, and (c) a third step of reducing the diameter of one end of the cylindrical body and increasing the axial dimension of the cylindrical body to obtain a cylindrical body. And (d) a fourth step of forming an engaged portion to be engaged with a tool on the other end side of the tubular body.