JPH08285280A - Manufacture of housing for glow plug - Google Patents

Abstract

PURPOSE: To provide a highly reliable product by cutting a wire and correcting both end faces of cut surfaces of the cut raw material, and molding in the form of a glass by forward extrusion and punching a glass-shaped bottom of the raw material so as to provide a pipe material and working the pipe material into small size with the punched side as a reference. CONSTITUTION: A wire 11 is cut in a specified length. After the cut surfaces of a raw material 12 thus provided are pressed and corrected, a hollow 43 is forwardly extruded from the other end face 32 with a shallow center hole 33 made in one end face 31 as a guide. Then, the bottom 44a of the hole 43 is punched with a center hole as a dice. After the formation of a hole 53, the inner surface 53a of the hole 53 is drawn to obtain a pipe material 60 having an uniform thickness. Then, a mandrel is inserted and extrusion-worked and then the mandrel worked thinner at the forward side of a hole 73 is inserted and forwardly extruded to contact a narrow diameter port 84c. The end face 9 of a second narrow diameter part thus provided is cut in a specified length, and the cut end face is beveled on both inner and outer faces, thereby finishing a product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glow plug for a diesel engine, and more particularly to a method for manufacturing a glow plug housing.

[0002]

2. Description of the Related Art A method for manufacturing a glow plug housing has been developed and implemented by the present applicant, as disclosed in Japanese Patent Publication No. 2-6412. According to this publication, a step of cutting a pipe material into a constant length to obtain a raw material, and a primary drawing step of inserting a core metal into the raw material and extruding forward to handle a small diameter Further, a secondary drawing step of inserting a cored bar that is thinner than the hole and extruding forward to perform a contraction process, a forming step of forming a tool locking part on the head, and And extruding the holes rearward into a tubular shape.

That is, Japanese Patent Publication No. 2-6412 discloses a method of manufacturing a housing by using a hollow pipe material as a raw material. Further, as an improvement to this, after forming a concave portion from both ends of the cut metal solid body, a hole is formed in the axial direction to obtain a cylindrical body (pipe material), which is then sequentially molded. A manufacturing method is disclosed in Japanese Patent Application Laid-Open No. 4-236010. Furthermore, JP-A-3-8531 and JP-A-4-20714.
According to Japanese Patent Laid-Open No. 4-371336, the outer shape is formed by axially forming a recess from both ends of a round bar-shaped material, and a shaft hole is formed by penetrating the recess formed from both ends to form a housing. A method of manufacturing is disclosed.

By the way, the general shearing is shown in FIG. 3 and the fractured part in the case where the flat plate is sheared is explained in FIG. 4. As shown in FIG. 3, the wire rod 11 such as a round bar is sheared to a predetermined length. When the material 12 is obtained by the above method, it is difficult to determine a proper clearance on the center line, and the clearance is often too small on the center line. The upper blade 15 is the wire rod 11
When it begins to bite into the cracks a, i
With that, tongues b and j are generated, the upper blade 15 descends downward, and the tongue j receives the secondary shear c. Due to the crack a generated by this shearing, the tongue b remains as burrs on the fracture surface f. d is the sag.

As shown in FIG. 4, sagging d, shear surface e, fracture surface f, burrs g on the lower side in the shearing direction, and indentations contacting the lower blade 16 remain on the lower surface. On the sheared surface e, the scratches of the upper blade 15 that are rubbed slightly remain, but the surface is smooth.
The fracture surface f is a surface in which small rough burrs are scattered in a rough state when cracks a and i are generated as if the tissue was destroyed by the biting of the upper blade 15 and torn off.

[0006]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 2-641
When the hollow pipe material described in Japanese Patent Laid-Open No. 2 is used, the pipe material is found in the processing step when it has uneven wall thickness or uneven thickness, but many quality defects occur. Resulting in. When the wall thickness is uneven, it is found that the volume (volume) is poor and thus the molding is not sufficiently performed or the molded product has an insufficient length. Further, in the case of uneven thickness, the molding process is quite severe, but the uneven thickness state may be processed without being completely corrected, and it is rarely found that the punch of the processing die is damaged. In some cases, the process lacks stability.

Further, as disclosed in Japanese Patent Application Laid-Open No. 4-236010, in a method of obtaining a pipe material by cutting a solid body, forming recesses from both ends thereof, and then forming axial holes. As described above, the fracture surface (f) remains at both ends of the solid body, and the fracture surface (f) or the crack (a, i).
May grow by contracting or expanding, and likewise, since the axial hole is punched at approximately the center of the body, the punched fracture surface (f) remains. Since it is processed, the fracture surface (f) is inside the shaft hole, so it is difficult to visually grasp the state.

Further, the round rod-shaped material disclosed in Japanese Patent Laid-Open No. 20714/1992 is extruded forward, backward extruded or forward rear extruded while forming concave portions from both ends, and the concave portion formed at the center is formed. In the manufacturing method of penetrating, the fracture surface (f) left when the round bar-shaped material is cut as described above may grow in the subsequent processing, and because the recess penetrates after the extrusion processing. The fracture surface (f) remains in the penetrated hole portion, and small cracks or burrs or metal powder adheres to the fracture surface. It is not preferable from a safety point of view because it may induce a spark and conduct an abnormal current.

The present invention aims to eliminate the above-mentioned drawbacks by cutting the wire (11) and correcting both end surfaces of the cut surfaces (13, 13) of the cut material (12). ,
Also, a glow plug is formed into a cup shape by forward extrusion processing, the bottom surface (44a) of the cup shape is punched out to obtain a pipe material, and the pipe side is processed into a thin diameter based on the stamped side. The present invention proposes a method for manufacturing a housing for automobiles.

[0010]

According to the present invention for solving the above problems, a wire rod (11) having a constant thickness is cut into a constant length, and both ends of the cut first raw material (12) are While pressing the cut surface (13) from one side to straighten it,
The corrected first end face (21) has a shallow first center hole (3
The second material (30) is formed by pressing 3) with a punch (35).
The second material is formed by forming the first (33) into the molding pin (49).
To form a deep cup-shaped hole (43) and a shallow second center hole (44) by facing forward with
The thin bottom surface (44a) between the hole bottom (43a) and the second center hole formed by the molding is punched with a molding pin (49) using the second center hole as a die, and the punching hole is further formed. The first feature is that the pipe material (60) is formed by a step of smoothing the inner surface (54a) and the inner surface (53a) of the hole by forward extrusion.

Then, a metal core (7) is attached to the pipe material (60).
5) through which the first small diameter portion (74
In the primary drawing process (G) in which the outer diameter is handled in b), the second feature is that the punching hole (64) side is processed forward.

Next, a cored bar (8) thinner than the hole (73) formed in the primary drawing step (G) is used.
The third feature is that the secondary drawing process (H) is performed by inserting 5) and subjecting the punched hole (64) side to a forward process of contracting the tube so as to be forward.

Further, after passing through the drawing process (G, H), the punching hole (64) portion forms a second thin diameter portion end portion (84c), but the thin diameter portion end is formed. The fourth feature is that the product is cut (10) to a predetermined length and chamfered (4, 5) for finishing.

[0014]

According to the first aspect of the present invention, since the cut surface (13, 13) of the first material (12) is pressed and corrected, the burr on the outer surface of the cut surface is eliminated, and the cut surface (13) is further removed. ) Makes the surface with cracks and rough skin latent in) a glossy and smooth surface. Then, using the shallow first center hole (33) as a guide on the one end face (31), the hole (43) extruded forward from the end face (32) on the opposite side of the center hole.
And the bottom surface (44a) of the hole is punched out by using the second center hole (44) as a die in the same manner as the forward extrusion processing,
Moreover, since the hole (53) is machined from one side, the fractured part (54a) in the hole (53) is of course the end face (5).
2) It becomes the side. Since the inner surface of the hole (53a) is processed, a pipe material (60) having a uniform wall thickness is obtained by a die (die, punch), and a smooth cylinder is formed on the inner surface of the hole (63). That is, the roughened state of the cut surface (13) of the first material (12) is corrected by pressing,
Since the hole (43) is extruded by the extrusion perforation method and then the hole is handled together with the break portion (54a), the pipe material (60) is finished as a smooth hole (63), and the cut surface (13) and The growth of cracks at the break (54a) is suppressed.

Further, in the second aspect, with the side of the push-out hole (54) as the front, the core metal (69) is inserted to perform the forward extrusion process. When the processed article is cut along the center line in the longitudinal direction and the change in the material structure is observed, the outer diameter is processed by the first small diameter portion (74b), while the hole (73) is compressed. Therefore, the fractured portion (54a) of the punched hole (54) is slightly changed to move to the end face (72) side. Further, since the hole (63) is handled and smoothed, the hole (73) is smooth as a whole even in the primary drawing process.

Further, according to a second aspect of the present invention, the core metal (85) which is narrower than the hole (73) is inserted through the core metal (85) to be extruded forward to reduce the second small diameter portion (84c). In the secondary drawing step (H), the punching hole (5
Since the extrusion is performed with the 4) side as the front, the fractured part (54
In (a), it is moved so as to be slightly compressed toward the end face (2) side as if it was compressed more than in the primary drawing step (G).

Then, the end face (9) of the second small-diameter portion (8) obtained through the primary and secondary drawing processes (G, H) is cut to a predetermined length by cutting (10). The cutting end face is processed by finishing the outer chamfer (4) and the inner chamfer (5) to finish the fractured portion (54) of the punched hole (54).
The a) is shaved off, and the feared fracture surface (f) is not left on the inner surfaces of the center insertion hole (7) and the cap fitting hole (8).

The numbers in parentheses are for the purpose of contrasting with the drawings, but do not limit the structure of the invention.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacturing process in FIG. 1 and the relationship with a mold based on the manufacturing process in FIG. 2 will be described in detail below with reference to the drawings.

First, in FIG. 1 and FIG. 2, the capital letters A, B ... I on the left side in parentheses are, for example, (A)
Indicates the first step (correction / cutting of the wire rod), (B) means the second step (correction of the first end face), and (I) means the ninth step (formation of the tool engaging portion). Further, in the steps (A) to (H), the reference numerals of the products formed in the steps and the molds used are 1 in place of (A) in the order of the steps, and 8 in place of (H). The numbers are displayed as two digits. For example, the end faces are displayed as 21 to 81 and 22 to 82 to distinguish which process is performed.

Further, the arrows in FIG. 1 are shown in FIG.
85 shows the forward direction of the punches 25, 35 ... 85, that is, the direction of forward extrusion. In addition, FIG. 2 illustrates respective half-sections formed by extruding the material on the upper side of the center line of each step and extruding the material on the lower side of the center line so that the insertion side of the material in each step can be understood. . Further, in FIG. 2, it is assumed that the progressive feeding is performed linearly, and the die holes 27, 37, 47, 57 and 6 are formed on the same table 100.
In the case where 7, 77 and 87 are arranged side by side, the feeding device will be omitted.

In the first step (A), a wire rod 11 having a constant thickness wound into a coil is straightened by a straightening machine (not shown in FIG. 2) and cut into a constant length. Obtain a material 12. As described in the conventional example, the end faces 13 and 13 have the fracture surface f and the shear surface e (hereinafter, the end face 13 is referred to as a cut surface).

The first blank 12 is inserted into the first die hole 27 and is pushed and pressed into the die hole 27 by the first punch 25 having the low conical surface 26, and the chamfered end face 21 is formed on one side. A low concave portion 22 is formed on the pressed side. The concave portion 22 is necessarily formed because it is pressed by the conical surface 26, but it is formed in order to make the cut surface 13 of the end surface 21 a glossy surface by reducing the pressing force as much as possible. Reference numeral 28 denotes a projecting pin that projects the material 20 in the direction opposite to the pressing direction when the first end surface correction is completed. Further, in the correction of the end face 13, there is a possibility that burrs on the end face may remain in the die hole 27, but although not shown, for example, by extruding the material 20 and blowing air at the same time, Can be cleaned and removed.

Next, in the second end face straightening step (C), the raw material 20 obtained in the first end face straightening step (B) is processed into 180
The punch 35, which is inserted into the second die hole 37 in a rotated state and has a first center 36 with a conical tip shape,
Is pressed to correct the concave portion 22 on the opposite side to a flat end face 32 and the outer periphery into a chamfered shape. The end face 21 on the pressing side has a flat end face 31 and the first center 36 that serves as a guide in the next step.
To form a shallow first center hole 33. Due to the formation of the first center hole, the meat is slightly moved to the opposite end face 32 side, so that a flat face is formed and both end faces 31, 32 are formed.
Is a glossy end face, and the roundness of the outer shape of the second material 30 is improved. Reference numeral 38 denotes a projecting pin, which projects the second material 30 after the step is completed.

Subsequently, in the first molding step (D), the second die material 30 is rotated 180 ° again and the third die hole 47 is formed.
Is inserted into. In this second die hole 47, the sleeve 4
8 and a pair of molding pins 49 projecting forward from the sleeve stand by as one set, and a punch 45 having a low trapezoidal tip 46 presses the end face 32 from the other to perform forward extrusion. Then, the tip of the forming pin 49 is first guided to the first center hole 33, the forming pin is pushed into the second blank 30, and the trapezoidal tip 46 is pushed into the end face 32 so as to bite, and the stroke end of the punch 45 is reached. Then, a deep hole 43 having a cup shape is formed on the end surface 41 on one side, and a shallow second center hole 44 is formed on the end surface 42 on the other side, and a thin bottom surface 44a is formed between the end surface 41 and the hole bottom 43a. When this molding is over, punch 45
Moves backward, the sleeve 48 moves forward, the third material 40 is pulled out from the molding pin 49, and the third die hole 47
The raw material 40 is extruded from and is sequentially fed to the next step.

In the second end face straightening step (C) and the main forming step (D), the materials 20 and 30 are rotated by 180 ° when they are inserted, respectively. , 47 on the same table 100 so that the punches 35, 45 are oriented in the same direction. In the second end face straightening step (C), the punch 35, the second die hole 37,
If the pushing pin 38 is pressed or pushed in a direction opposite to that shown in the drawing, the material 20 can be rotated without rotating.

Then, the third material 40 is moved in parallel and sent to the punching process (E) and inserted into the fourth die hole 57. In the die hole 57, a pipe-shaped sleeve 58 and a hole pin 59 inserted in the sleeve 58 are waiting as a set. The tip of the perforating pin 59 is formed by a cylindrical portion having the same diameter as the hole 43 following the low conical surface, and a connecting portion having a diameter slightly smaller than the cylindrical portion. On the other side, a punch punch 55 having a blade portion 56 stands by, and the third material 40 is inserted into the fourth die hole 57.
After the insertion, the end face 42 is pushed by the punching punch 55 to be extruded forward, the bottom face 44a is crushed by the stroke end of the punching punch 55 while the hole 43 is handled and processed, and the second center The hole 44 is punched out as a die, and the punched scrap 54b is pushed into the blade portion 56. At the same time as the punching punch 55 retreats, the sleeve 58 also moves forward, causing the fourth material 50 to escape from the fourth die hole 57, and moves parallel to the hole inner surface leveling process (F) by a feeding device (not shown). Let

In the punching process (E), the end surface 5
A hole 53 that penetrates from the 1 side to the end face 52 side is formed,
The inner surface 53a of the hole 53 is processed. Then, a hole 54 slightly remains as a trace of the second center hole 44 on the end face 52 side, and a punched hole 54a (hereinafter, referred to as a breakage portion) is formed inside thereof. If the punching process is performed without forming the second center hole 44, the fracture surface f described in the conventional example is formed at the hole 54 portion, and therefore the fracture surface f is on the end face 52 side. In the above, since it is a portion that cannot be corrected or corrected even in the step described later, the formation of the second center hole 44 in the first molding (D) is also an important step. Further, the punched scraps 54b generated in this step are pushed into the blade portion 56 and then the blade portion 56
Since a large hole is formed on the rear side, the punching scraps 54b that are sequentially processed and pushed in automatically push and discharge the scraps.

Then, the fourth material 50 inserted into the fifth die hole 67 is the end portion of the hollow punch 65 and the end surface 52.
Is pressed, and is extruded forward toward the handle pin 69. The tip of the handle pin is slightly larger than the hole 53,
Not only the hole 53 but also the hole 54 and the fractured portion 54a are smoothed to form a smooth hole 63 from the end face 61 side to the end face 62 side. 64 is a chamfered mark by the tip 46 of the punch 45 when the second center hole 44 is formed.

The pipe member 60 is formed by the above steps, and a cylindrical body whose hole 63 and its outer shape coincide with each other in the center is obtained. Further, the cylindrical body is molded into a glow plug housing, and the molding process is described in JP-B-2-641.
As described in detail in Japanese Patent Publication No. 2, the molding method using the pipe material 60 will be described.

After the pipe material 60 has been molded by the hole inner surface smoothing step (F), it is inserted into the sixth die hole 77 by the feeding device and formed by the outer punch 76 and the core metal 75. With a punch, a tip-shaped round metal core 75 protruding from the outer punch is inserted into the hole 63, and when the tip of the outer punch 76 comes into contact with the end surface 62 and presses it, the protrusion-shaped first bar formed in the die hole 77. Since the first narrowed portion 77a is pushed in from the end face 61 side and processed, the first narrow diameter portion 74b having a reduced outer diameter is formed. Therefore, the diameter of the hole 73 is the same as the diameter of the previously processed hole 63, but the first thin portion 74b is long by the amount processed, and the remaining portion 74a that has not been processed is included. become longer. Then, since the first small-diameter portion 74b is extruded in the direction of 74a, the outer side to be handled moves the tissue in the direction opposite to the extruding direction and receives the compressive force in the hole 73, so that the hole 54a portion in which the fracture portion is formed Is molded so as to slightly move toward the end face 72 side. In addition, since a pressing force is applied to the end face 61 during this extrusion process, the end face 61 is formed into a more semi-sliding end face 71. When the first punch retracts, the end face 72 is pushed by the knockout pin 79, the primary molded product 70 is ejected, and it is held by a chuck device (not shown) waiting in the sixth die hole 77. It is inserted into the seventh die hole 87 of the process.

In the second drawing step (H), the outer punch 86 and the core bar 85 whose tip is thinner than the hole 73 are combined to form a second punch, and the tip of the core bar 85 is a hole. When the outer punch 86 is inserted into the end 73, the end of the outer punch 86 comes into contact with the end surface 71 and presses it. Then, the second narrowed portion 87a formed in the seventh die hole 87 is pushed from the end surface 72, and the first narrowed diameter portion 74b is formed with the second narrowed diameter portion 84c. That is,
The end portions 81, 82, the first small diameter portion 84b (2), the second small diameter portion 84c (3), the tool locking portion (1) described later, and the remaining portion 84.
A secondary molded product 80 consisting of a and the end surface 8 is obtained.
The knock-out pin 89 projects from the second side to the second narrowed portion 87a, is held by a chuck device that is on standby, and is further sent to the tool locking portion forming step (I). As will be described later, the hole 83a is formed in the center insertion hole 7 and the hole 8 is formed.
3b is the cap fitting hole 8, the first small diameter portion 84b is the screw portion 2, and the second small diameter portion 84c is the small diameter portion 3.

In the tool engaging portion forming step (I), a die relationship diagram is not shown, but the primary drawing step (G) is performed.
As described in the second drawing process (H), a hexagonal hole is formed in the die hole, and the end face 81 is pressed against the core metal having the same shape as the center fixing hole 6 from the end face 81 side. The tool engaging portion 1 can be molded by pressing with an outer punch to apply a pressing force so as to expand the tube, and performing backward extrusion processing.

The second thin portion 84c is formed in the second drawing step (H) as described above. The second thin portion 84c is most contracted together with the hole 83b so that work hardening easily occurs. , As described in the primary drawing process (G),
The second small-diameter portion 84c is processed on the first small-diameter portion 84b side, and is contracted in the hole 83b, so that the length thereof extends in the direction of the end face 82 and is broken by the punching process (E). The portion 54a moves to the vicinity of the end surface 82 side of the hole 83b. That is, since the fractured portion 54a that has been sheared by punching comes close to the hole 83b of the end face 82, the feared fractured portion 54a is finished by cutting 10, and the end of the cap fitting hole 8 is chamfered on the outside 4 and chamfered on the inside. 5 Processed and finished. The finishing process (J)
Then, a male screw is engraved on the first small-diameter portion 84b to form the screw portion 2
The end surface of the tool engaging portion 1 may be cut to have the same height if necessary, but other than that, the small diameter portion 3, the center fixing hole 6, the center insertion hole 7, the cap fitting hole 8 is processed by the above-described processing process.

In the above-mentioned manufacturing process, either hot working or cold working can be performed, but it goes without saying that annealing or phosphoric acid film (bonderite) treatment is appropriately performed in cold working. Moreover, although each process is described in detail, for example,
It is also possible to shorten the process by simultaneously performing the first end face correction process (B) and the second end face correction process (C).

[0036]

According to the present invention, since the steps are configured as described above, in the invention of claim 1, the center line of the pipe material is consistently uniform, and the wall thickness is accordingly uniform. Therefore, since the completed housing is assembled with the center of the cap aligned with the center of the housing, the ignition is averaged and the heating property is improved. In addition, since the cut surface obtained by cutting the wire is pressed and straightened to make it flat, growth due to cracks and tissue destruction on the cut surface is suppressed. Then, the inner surface of the hole is smooth, and a deep cup-shaped hole is formed on one side by the front extrusion process, and the front end punching process is performed on the one end face side. Located in.

Next, in the invention of claim 2, since the first small-diameter portion is extruded forward in the same direction as that in which the pipe material is formed, the broken portion of the hole located on the one end face side is Move to the end face side.

Further, in the invention of claim 3, the second thin portion smaller than the first thin portion is treated on the outer diameter side and contracted on the inner diameter side in the same direction as the pipe material forming process. Because of the forward extrusion process, the fractured part of the hole moves to the vicinity of the one end face.

Further, in the invention of claim 4, since the fractured portion of the hole moves to the vicinity of the one end surface, cracks and burrs on the fractured surface or fractured portion most feared for the housing are completely removed by cutting, and the shrinkage is reduced. Since the one end surface where work hardening is likely to appear due to the pipe and the handling process is cut off, when used as a glow plug, the stability of ignition and the heating property can be improved.

[Brief description of drawings]

FIG. 1 is a process diagram showing a molding process of the present invention and a molded product thereof.

FIG. 2 is a schematic view showing a relationship between a molding process of the present invention and a molding die thereof.

FIG. 3 is a schematic diagram of material shearing that is conventionally generally performed.

FIG. 4 is a schematic view showing a fracture surface of a sheared material and its surface.

[Code]

 1 Tool Locking Part 2 Screw Part 3 Small Diameter Part (First Small Diameter Part) 4 External Chamfer 5 Inner Chamfer 6 Center Fixing Hole 7 Center Inserting Hole 8 Cap Fitting Hole 9 End Face 10 Cutting 11 Wire Rod 12 First Material 13 End Face (Cutting surface) 21 End surface 30 Second material 32 End surface 33 First center hole 43 (Cup-shaped) hole 43a Hole bottom 44 Second center hole 44a Bottom 49 Molding pin 53 Hole 53a Hole inner surface 54a Punch hole (breaking part) 60 Pipe Material 64a Push-out Hole (Break) 73 Hole 74b First Small Diameter Section 75 Core Bar 84c Second Small Diameter Section 85 Core Bar A Wire Rod Straightening / Cutting (First) Step B First End Face Correction (Second) Process C Second end face straightening (third) process D First forming (fourth) process E Punching (fifth) process F Hole inner surface leveling (sixth) process G Primary drawing (seventh) Process H Secondary diaphragm Re-machining (8th) process I Tool locking part forming (9th) process J Finishing process (10th) process

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[Procedure amendment]

[Submission date] May 10, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

The present invention relates to relates to a glow plug diesel engine, more particularly to a manufacturing method of Haujin <br/> grayed glow plugs.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

Further, as disclosed in Japanese Patent Laid-Open No. 4-236010, in a method of cutting a solid body, forming recesses from both ends thereof, and then forming axial holes to obtain a pipe material. As described above, the fracture surface (f) remains at both ends of the solid body, and the fracture surface (f) or the crack (a,
i) is Ru Kotogaa to grow by reduced pipe processing or pipe expanding. Similarly, since the axial hole is punched almost in the center of the body, the punched fractured surface (f) is processed while leaving the punched fractured surface (f).
Since it is left inside the narrow shaft hole, it is difficult to grasp the condition visually.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

Means for Solving the Problems According to the present invention for solving the above-mentioned problems, a certain wire material (11) is cut into a certain length, and both ends of the cut first material (12) are cut from one side. The cut surface (13) is pressed to be straightened, and a shallow first center hole (33) is pressed and formed on the straightened one end surface (21) with a punch (35) to form a second material (30). ,
The second material has the first center hole (33) and the molding pin (4).
Extruded forward to face 9) and deep cobbed
The hole (43) of the shallow second center molding a hole (44), a thin bottom (44a) of said second center hole of the hole bottom formed by molding and (43a) and said second center hole To form a pipe material (60) by a step of punching with a molding pin (49) as a die and further smoothing the punching hole (54a) and the inner surface (53a) of the hole by forward extrusion. The first feature is that

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011] Then, the core metal pipe material (60) (75) and forward extruded by inserting the first drawing step of processing squeezing the outer diameter of the first small-diameter portion (74b) (G) Then, the second feature is that the punching hole (64) side is processed forward.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

First, in FIG. 1 and FIG. 2, A, B ... I are shown on the left side.
The parentheses are attached to the English letters, for example, (A)
Indicates the first step (straightening / cutting of the wire), (B) indicates the second step (first end surface straightening) , ... (I) indicates the ninth step (tool locking portion forming). Further, in the steps (A) to (H), each part code of the product formed in the step and the mold used is displayed as two digits. For example, the end faces 21 to 81
And 22 to 82 are used to distinguish which process has been performed.

Claims (4)

[Claims] 1. A primary drawing process and a secondary drawing process in which a core metal is inserted into a pipe material having a constant thickness, a hole and a length and extruded forward, and a tool locking portion on the head side. In a method for manufacturing a glow plug housing, which comprises a forming step for forming a hollow plug and a step for backwardly extruding a hole in the head into a tubular shape, a wire having a certain thickness is cut into a certain length and the cut Both ends of the first material are pressed from one side to straighten the cut surface and straightened, and a shallow first center hole is punched by punching on the straightened one end surface to form a second material. The first center hole is extruded so as to face the molding pin to form a deep cup-shaped hole and a shallow second center hole, and the bottom and second center holes formed by the molding are formed. Use the thin bottom surface as the die for the second center hole. Punching in the forming pin and processed further to form the pipe material by the step of processing Shi become the punching hole and the hole inner surface pressing by the forward extrusion, and wherein the method of manufacturing a housing for a glow plug. 2. The manufacturing of a glow plug housing according to claim 1, wherein, in the primary drawing step, the push-out hole side is forward and a core metal is inserted to perform forward extrusion. Method. 3. The secondary drawing process according to claim 1, wherein the push-out hole side which is the front side in the primary drawing process is extruded forward to perform a contraction process. A method for manufacturing a glow plug housing according to claim 2. 4. The chamfering process according to claim 3, wherein the end portion of the second extruded small-diameter portion which has been extruded and contracted to have a predetermined length is chamfered. A method for manufacturing the glow plug housing described above.