JP2003225731A - Forging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forging apparatus capable of reliably knocking out a forged product in a stable condition, and ensuring a smooth forging work. <P>SOLUTION: During the knocking out in which a product 101 is formed out of a material 100 by an upper die and a lower die 1, and abutted on a sacrificed shaft part 104 formed by a shaft hole 3c in a counter punch 3 by elevating a knock-out pin 4 to extrude the product 101, the counter punch 3 is integrally elevated together with the knock-out pin 4, the counter punch 3 is elevated to the elevation end, and stopped, and a top end part 4b of the knock-out pin 4 is protruded from the shaft hole 3c of the counter punch 3 to knock out the product. The knock-out pin 4 is protected by the counter punch 3, and any buckling deformation or breakage occurred in the knock-out pin 4 can be effectively avoided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging device for producing a forged product by compression molding a material with an upper die and a lower die.

[0002]

2. Description of the Related Art Relatively small products, such as machine parts, which are required to have high dimensional accuracy, are widely manufactured by cold forging because they are excellent in productivity and can ensure dimensional accuracy and strength of products.

For example, a hollow cylindrical portion 1 having a relatively small diameter in which a deep hole 103 having a bottom is formed in the axial direction as shown in FIG. 9 from a cylindrical material 100 having a sectional shape shown in FIG.
Forged product 101 having a discarding shaft portion 104 protruding from the base end of 02
For example, a forging device whose structure is schematically shown in FIG.

That is, the forging device shown in FIG. 10 has a die 11 for forming the outer periphery of the hollow cylindrical portion 102 shown in FIG.
2 and the base end of the material 100, and a lower die 111 provided with a counter punch 113 for pushing the molded product 101 from the die 112, and the distal end of the product 101 and the deep hole 103 are molded at the distal end of the material 100 Dice 1
12 and an upper die 117 having a punch 118 for pressing against the counter punch 113.

This counter punch 113 is a die 1
12 includes a sliding portion 113a that moves in the axial direction, a discarding shaft forming portion 113c that is recessed in a top end surface 113b of the sliding portion 113a, and a base portion 113d that has a larger diameter than the sliding portion 113a. The lower end surface of the base 113d of the punch 113 abuts on the load supporting portion 114 fixed to the lower die 111 to receive the load from the punch 118 of the upper die 117. The load support 114 also serves as a support for the ejector pin 116 that pushes up the lower end surface of the counter punch 113, and the load support 114 is provided with a hole for inserting the ejector pin 116. A drive mechanism (not shown) that drives the ejector pin 116 is disposed below the ejector pin 116.

Then, as shown by the alternate long and short dash line in FIG. 10, the material 100 is set in the lower mold 111, then the upper mold 117 is lowered, and the hollow mold of the product 101 is concentrically aligned with the lower mold 111 by the die 112. Molding the outer periphery of the part 102,
And punch 118 of upper mold 117 and counter punch 11
3 and the raw material 100 is compression-molded to a prescribed length, and the deep hole 103 and the discarding shaft portion 104 are formed.

When the upper die 117 rises after the completion of compression molding by lowering the upper die 117, the ejector pin 116 rises and pushes up the counter punch 113 to knock out the product 101 from the die 112, as shown in FIG.

Further, there is a forging device whose structure is schematically shown in FIG. This forging device includes a lower die 121 having a die 122 for forming the outer periphery of the hollow cylindrical portion 102 and a counter punch 123 for regulating the base end of the material 100,
Punch 1 for forming the tip of the product 101 and the deep hole 103 on the tip of the material 100 and pressing it against the die 122.
The upper mold 130 having 31 is provided.

The counter punch 123 is a die 122.
The counter 123 includes a shaft portion 123a inserted therein and a base portion 123b having a diameter larger than that of the shaft portion 123a. The lower end surface of the base portion 123b of the counter punch 123 abuts the load supporting portion 125, and the load from the punch 131 of the upper die 130. Is configured to accept.

Further, a shaft hole 123c having a small diameter portion 123d is formed at the lower end of the shaft center of the counter punch 123, and a knockout pin 127 is axially movably fitted in the shaft hole 123c. Knockout pin 12
7, the shaft portion 127a penetrates the small diameter portion 123d, and the top end portion 127b formed to have a large diameter is locked to the small diameter portion 123d so that the descending movement end is regulated.

Further, an ejector pin 128 for pushing up the lower end surface of the knockout pin 127 is provided, and the load support portion 125 also serves as a support for the ejector pin 128.

Then, as shown by the alternate long and short dash line in FIG. 12, the material 100 is set in the lower die 121, the upper die 130 is lowered and aligned concentrically with the lower die 121, and the outer periphery of the hollow cylindrical portion 102 is made by a die 122. The material 10 is formed between the punch 131 of the upper mold 130 and the counter punch 123.
0 is compression molded, and the discarding shaft portion 104 is molded by the deep hole 123 and the shaft hole 123c.

When the upper die 130 rises after the completion of molding by lowering the upper die 130, the ejector pins 128 rise,
Next, as shown in FIG. 13, the knockout pin 127 is pushed up, and the product 101 is knocked out of the die 122 by the top end 127b of the knockout pin 127 protruding from the shaft hole 123c of the counter punch 123.

[0014]

[Problems to be Solved by the Invention]
According to the former forging device shown in FIG. 2, the punch 118 and the counter punch 11 of the upper die 117 are lowered by lowering the upper die 117.
The entire length of the material 100 is compression molded by 3 and the die 1
The outer periphery of the hollow cylindrical portion 102 is molded by 12, and the deep hole 103 and the discarding shaft portion 104 are molded. When the upper die 117 rises after the molding is completed, the ejector pin 116 rises and the counter punch 113 is pushed up, and the product 1
01 is knocked out of the dice 112.

However, although the draft axis is formed in the discard shaft forming portion 113c, the discard shaft portion 104 press-fitted into the discard shaft forming portion 113c of the counter punch 113 along with the compression molding of the material 100 is discarded. Shaft forming part 113
Stick to the inner surface of c by pressing. Due to this sticking, when the counter punch 113 knocks out the product 101 from the die 112 after the completion of molding, smooth removal of the product 110 from the counter punch 113 is hindered, and efficient forging work is hindered. Is concerned.

On the other hand, according to the latter forging device shown in FIGS. 12 and 13, the punch 13 is moved by lowering the upper die 130.
The material 100 is compression-molded by 1 and the counter punch 123, the outer periphery of the hollow cylindrical portion 102 is molded by the die 122, and the deep hole 103 and the discarding shaft portion 104 are molded. When the upper die 130 rises after the completion of molding, the knockout pin 127 rises and the product 101 becomes a die 122.
Be knocked out by.

However, after the molding is completed, the counter punch 1
Die 1 of the product 101 protruding from the shaft hole 123c of 23
Since the knockout pin 127 extruded from 22 is formed to have a small diameter and a relatively long length, the knockout pin 12
The buckling deformation of 7 may hinder smooth forging work. Further, repairing such as replacement of the damaged knockout pin 127 requires a lot of man-hours, which may cause an increase in running cost.

Therefore, an object of the present invention made in view of the above point is to provide a forging device capable of reliably knocking out a product after completion of molding in a stable state and ensuring a smooth forging operation. .

[0019]

The forging device according to claim 1 for achieving the above object is a forging device for producing a forged product by compressing and molding a material by an upper die and a lower die, wherein the lower die is A cylindrical die for molding the outer periphery of the material, a sliding portion that moves in the axial direction with a top end surface that fits in the die and molds the base end of the material, and a shaft hole that penetrates in the axial direction. The formed counter punch, the counter punch ascending end restricting means and the counter punch descending end restricting means for respectively restricting the ascending moving end and the descending moving end of the counter punch, and being axially movable in the shaft hole of the counter punch. A knockout pin to be inserted and a knockout pin descending end regulating hand that regulates the descending moving end of the knockout pin at a position where the top end of the knockout pin is below the top end face of the counter punch. And an ejector pin that abuts on the lower end surface of the knockout pin to raise the knockout pin, and compresses the product from the material by the lower mold and the upper mold in a state where the counter punch and the knockout pin are respectively located at the lowering movement end. By molding and by raising the pin, it abuts the protruding portion formed by the shaft hole of the counter punch and pushes up the product, and also the counter punch is raised to the ascending moving end via the protruding portion, and the knockout pin is further attached. It is characterized in that the product is knocked out by ascending from the descending moving end.

According to the invention of claim 1, after the product is compression-molded from the material by the upper mold and the lower mold, the product is extruded by being brought into contact with the protruding portion formed by the shaft hole of the counter punch by the rise of the knockout pin. At the time of knockout, the counter punch rises together with the knockout pin, and after the counter punch rises to the rising movement end, the knockout pin is protected by the counter punch because the product is knocked out by the further rise of the knockout pin. Moreover, the amount of protrusion of the knockout pin protruding from the counter punch is extremely small, and buckling deformation and damage that occur in the knockout pin are effectively avoided. As a result, the product can be reliably knocked out in a stable state, and a smooth forging operation can be secured. In addition, repairing such as replacement of a broken knockout pin is not required, and a reduction in running cost can be expected. .

According to a second aspect of the present invention, in the forging device according to the first aspect, the knockout pin has a length dimension larger than a length dimension of the shaft hole.

According to the second aspect of the present invention, since the length dimension of the knockout pin is set larger than the length dimension of the shaft hole, the knockout pin is pushed up by the ejector pin and the knockout pin is pushed from the top end surface of the counter punch. The top end can be easily projected, and it is not necessary to insert the ejector pin into the shaft hole when knocking out the product, so that the ejector pin can be simplified in shape.

According to a third aspect of the present invention, in the forging device according to the first or second aspect, the counter punch lowering end regulating means is brought into contact with the lower end surface of the counter punch at the lowering movement end, and the load from the upper die is applied. It is characterized in that it is a load support portion that receives the load.

According to the third aspect of the present invention, the counter punch lowering edge regulating means is constituted by a load supporting portion for receiving the load from the upper die by abutting the lower end surface of the counter punch, and the counter punch lowering edge regulating means is separately provided. Simplification of the structure can be obtained without the need for disposing.

The invention according to claim 4 is the forging device according to any one of claims 1 to 3, wherein the counter punch upper end regulating means is a base end formed by expanding the diameter of the lower end of the sliding portion of the counter punch. And a counter punch guide portion that slides in contact with the sliding portion of the counter punch to guide the movement of the counter punch and that the base end abuts from below.

According to the invention of claim 4, the counter punch can be constituted by a base end having a diameter enlarged and formed on the counter punch, and a counter punch guide portion, and it is not necessary to provide a counter punch ascending end regulating means. Simplification is obtained.

According to a fifth aspect of the present invention, in the forging device according to any of the first to fourth aspects, the knockout pin descending end regulating means has a small diameter portion formed in the shaft hole of the counter punch and the small diameter portion. It is characterized in that it is a top end portion of which the diameter is formed to the knockout pin that can be engaged with the above portion from above.

According to the invention of claim 5, the knockout pin descending end regulating means can be formed by a simple structure including a small diameter portion formed in the shaft hole of the counter punch and a top end portion formed by expanding the diameter of the knockout pin.

According to a sixth aspect of the present invention, in the forging device according to any of the first to sixth aspects, the projecting portion is a discarding shaft portion.

According to the sixth aspect of the present invention, the projecting portion is constituted by the discarding shaft portion that is cut out after being knocked out, and the product is free from scratches and the like due to knockout, and a high quality forged product can be obtained. .

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a forging device according to the present invention will be described with reference to FIGS.
The case of manufacturing the forged product 101 shown in FIGS. 0 to 9 will be described as an example.

FIG. 1 is a schematic diagram showing the structure of a forging device according to this embodiment. The forging device has a hollow cylindrical portion 10 shown in FIG. 8 as shown in FIG. 2 and an enlarged view of a portion A of FIG.
A cylindrical die 2 and a material 10 for molding the outer periphery of
The lower end 1 is provided with a counter punch 3 and a knockout pin 4 that push out the molded product 101 from the die 2 while controlling the base end of 0 and the material 100 that is vertically moved by, for example, a single-acting cylinder (not shown). In addition, the upper die 10 having a punch 11 for molding the tip of the product 101 and the deep hole 103 and applying compression to the material 100 is provided.

Below the lower mold 1, a counter punch 3 is fitted in the die 2 and inserted movably in the axial direction. The counter punch 3 includes a sliding portion 3a that moves in the die 2 in the axial direction and a base portion 3b having a diameter larger than that of the sliding portion 3a.
The counter punch 3 has a shaft hole 3c having a small diameter portion 3d formed at the lower end at the center of the shaft, and an ejector pin insertion hole 3e having a diameter larger than that of the shaft hole 3c is continuous below the shaft hole 3c via a step. Has been formed.

The knockout pin 4 has a shaft portion 4a which moves axially in the shaft hole 3c of the counter punch 3, and a shaft portion 4a.
a top end portion 4b is formed continuously at the upper end of a and has a relatively large diameter so that the lower end surface can be locked at the upper end of the small diameter portion 3d,
The lower end surface of the top end portion 4b is engaged with the small diameter portion 3d to form knockout pin descending end regulating means for regulating the descending movement end of the knockout pin 4. That is, the knockout pin descending end regulating means includes the small diameter portion 3d formed in the shaft hole 3c of the counter punch 3 and the knockout pin 4.
It is formed by a simple structure with the top end portion 4b having the enlarged diameter.

This knockout pin 4 has a length dimension slightly larger than the length dimension of the shaft hole 3c of the counter punch 3, and at the descending movement end where the top end portion 4b is locked to the small diameter portion 3d, The top end 4b is retracted into the shaft hole 3c so as to be lower than the top end surface 3f of the counter punch 3 by a predetermined dimension, and the top end 8b of the ejector pin 8 is an ejector pin insertion hole of the counter punch 3 as described later. 3e
When the lower end surface of the knockout pin 4 is pushed up, the top end portion 8b of the ejector pin 8 is not inserted into the shaft hole 3c, and the top end portion 4b of the knockout pin 4 is inserted into the top end surface 3f of the counter punch 3. It is formed so as to project from. Therefore, it is not necessary to insert the top end 8b of the ejector pin 8 into the shaft hole 3c, and the top end 8b of the ejector pin 8 can be formed with a simple shape.

Further, below the die 2, there is provided a counter punch guide portion 5 having an insertion hole 5a slidably contacting the sliding portion 3a of the counter punch 3, and the counter punch guide portion 5 is used to pivot the counter punch 3 therethrough. Holds movably in any direction. The upper surface of the base portion 3b of the counter punch 3 has a counter punch guide portion 5 as shown in FIG.
When the counter punch 3 comes into contact with the lower surface of the die, it has a function as a counter punch ascending end regulating means for regulating the ascending movement end of the counter punch 3, that is, the amount of insertion into the die 2.

Further, a load supporting portion 7 disposed below the counter punch guide portion 5 with a spacer member 6 interposed therebetween.
Is configured so as to contact the lower end surface of the base end 3b to function as a counter punch descending end regulating means for regulating the descending moving end of the counter punch 3 and receive the load from the punch 11 of the upper die 10. .

The load support portion 7 also serves as a support for the ejector pin 8 whose top end portion 8b is inserted into the ejector punch insertion hole 3e of the counter punch 3 and pushes up the lower end surface of the knockout pin 4. Is provided with a hole 7a through which the ejector pin 8 is inserted.

The ejector pin 8 has a shaft portion 8a which is vertically movably fitted into the hole 7a, and a large-diameter top end portion 8b formed on the upper end of the shaft portion 8a. The lower end of the large-diameter portion 7b of the hole 7a. The lower end surface of the top end portion 8b is locked to the stepped portion 7c formed on the lower end of the ejector pin 8 so that the lower end of the ejector pin 8 is restricted.
Further, a drive mechanism (not shown) for driving the ejector pin 8 is arranged below the ejector pin 8.

Next, a forging method using the thus constructed forging device will be described with reference to the operation explanatory views shown in FIGS. 3 to 7. The upper mold 10 and the punch 11 are omitted in FIGS. 3 to 7.

First, as shown in FIG. 3, the ejector pin 8 of the lower mold 1 is at the lowering movement end, and the base portion 3 of the counter punch 3 is moved.
While the lower end surface of b is in contact with the load support portion 7 and the knockout pin 4 is held at the downward movement end, the upper mold 10
In the state in which is raised, the material 100 is set in the lower mold 1 as shown by the chain line.

Then, the upper die 10 is lowered to be concentrically aligned with the lower die 1 and the hollow cylindrical portion 1 of the product 101 is formed by the die 2.
02, the outer circumference of 02 is molded, and the entire length of the material 100 is compression-molded between the punch 11 of the upper die 10 and the top end surface 3f of the counter punch 3 to a prescribed length, and the punch 11 allows deep holes 103 to be formed. And, the product 101 in which the discarding shaft portion 104 as the protruding portion is molded by the shaft hole 3c of the counter punch 3 is forged. After the molding of the product 101 by the lowering of the upper mold 10, the upper mold 10 rises.

Thereafter, the load supporting portion 7 is driven by the driving device.
The ejector pin 8 is raised along the hole 7a of FIG.
The top end 8b of the ejector pin 8 is brought into contact with the lower end of the knockout pin 4 as shown in FIG.

Further, the ejector pin 8 is raised and the knockout pin 4 is pushed up. The knocked-out pin 4 pushed up moves upward in the shaft hole 3c of the counter punch 3, and the top end 4b contacts the lower end of the discarding shaft 104 of the product 101 as shown in FIG.

When the ejector pin 8 is further raised and the knockout pin 4 is pushed up, the top end 4b of the knockout pin 4 pushes up the discarding shaft 104 and the die 2
The product 101 moves upward inside. Here, since the discarding shaft portion 104, which is press-fitted into the shaft hole 3c of the counter punch 3 and formed by compression molding, comes into pressure contact with the inner peripheral surface of the shaft hole 3c to cause sticking, as shown in FIG. As the knockout pin 4 rises, the counter punch 3 ascends from the descending moving end, and the knockout pin 4, the counter punch 3 and the product 101 simultaneously rise together by the ejector pin 8 and the upper surface portion of the base portion 3b of the counter punch 3. Comes into contact with the lower surface of the counter punch guide portion 5.

The base end 3b of the counter punch 3 comes into contact with the lower surface of the counter punch guide portion 5 to stop the rise of the counter punch 3. When the lift of the counter punch 3 is held by the counter punch guide portion 5 at the rising moving end, and the knockout pin 4 is further pushed up by the ejector pin 8, the top end 4b of the knockout pin 4 is pushed.
The discarding shaft 104 is pushed up by the discarding shaft 10
The sticking is released by the shear stress generated between the shaft 4 and the shaft hole 3c, and as shown in FIG. 7, the knockout pin 4 is pushed up from the descending moving end to further push up the discarding shaft portion 104, and the product 102 is removed from the lower mold 1. Be knocked out.

Therefore, according to the present embodiment, the upper mold 10
, The product 101 is compressed from the material 100 and forged, and then the ejector pin 8 is lifted to push up the knockout pin 4 and the top end 4b of the knockout pin 4 pushes up the product 101. At the same time, the counter punch 3 is integrally pushed up by the ejector pin 8 and the base end 3b of the counter punch 3 comes into contact with the lower surface of the counter punch guide part 5 to stop the rise of the counter punch 3 and then the top end of the knockout pin 4 is stopped. Since the portion 4b projects from the counter punch 3 to knock out the product 101,
The knockout pin 4 is protected by the counter punch 3, and the protrusion amount of the knockout pin 4 protruding from the counter punch 3 is extremely small.
Buckling deformation and damage that occur in the can be effectively avoided. As a result, the product after the molding can be surely pushed out in a stable state from the die 2, and a smooth forging operation can be secured.

Further, since damage to the knockout pin 4 is effectively avoided, repair such as replacement of the damaged knockout pin becomes unnecessary, and a reduction in running cost can be expected.

Furthermore, since the product 101 is knocked out by bringing the knockout pin 4 into contact with the discarding shaft portion 104 that is cut off after being knocked out, the hollow columnar portion 102 or the like required as the product 101 is damaged by the knockout. Is effectively prevented and a high-quality forged product can be obtained.

The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the spirit of the invention. For example, in the above-described embodiment, when knocking out a hollow cylindrical product, the knockout pin 4 is brought into contact with the discarding shaft portion 104 and pushed up. However, depending on the product shape, the knockout pin 4 is brought into contact with the knockout pin 4 and knocked out. You can also do it.

[0051]

According to the forging device of the present invention described above, the product is compression-molded from the raw material by the upper die and the lower die, and then the knockout pin is raised to abut on the protruding portion formed by the shaft hole of the counter punch. Then, when knocking out the forged product, the counter punch rises together with the knockout pin, and after the counter punch rises to the ascending moving end, the product is knocked out from the lower mold by further raising the knockout pin. The knockout pin is protected by the counter punch, and the protrusion amount of the knockout pin protruding from the counter punch is extremely small, so that the buckling deformation and damage occurring in the knockout pin are effectively avoided.
As a result, the product can be reliably knocked out of the lower die in a stable state, and a smooth forging operation can be secured.
Further, repairing such as replacement of a broken knockout pin is not necessary, and a reduction in running cost can be expected.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a forging device according to the present invention.

FIG. 2 is likewise an enlarged view of a portion A of FIG.

FIG. 3 is likewise a schematic view showing an operation state of the forging device.

FIG. 4 is a schematic diagram showing the operation of the forging device.

FIG. 5 is a schematic view showing the operation of the forging device.

FIG. 6 is a schematic diagram showing the operation of the forging device.

FIG. 7 is a schematic diagram showing the operation of the forging device.

FIG. 8 is a cross-sectional view illustrating the shape of a material.

FIG. 9 is a cross-sectional view illustrating the shape of a forged product.

FIG. 10 is a schematic diagram showing an outline of a conventional forging device.

FIG. 11 is a schematic diagram showing the operation of the forging device.

FIG. 12 is a schematic view showing the outline of another conventional forging device.

FIG. 13 is a schematic view showing a state of the operation of the forging device.

[Explanation of symbols]

1 Lower die 2 Die 3 Counter punch 3a Sliding part 3b Base part 3d Small diameter part (knockout pin descending end regulating means) 3c Shaft hole 3e Ejector pin insertion hole 3f Top end surface 4 Knockout pin 4a Shaft part 4b Top end (knockout pin descending end Regulation means) 5 Counter punch guide part (counter punch rising end regulating means) 5a Insertion hole 7 Load supporting part (counter punch descending end regulating means) 7a Hole 7b Large diameter portion 8 Ejector pin 8a Shaft portion 8b Top end portion 10 Upper mold 11 Punch 100 Material 101 Forged product 104 Discard shaft (protruding part)

Claims (6)

[Claims] 1. A forging apparatus for producing a forged product by compression-molding a material with an upper die and a lower die, wherein the lower die is a cylindrical die for molding the outer periphery of the material, and is fitted in the die. A counter punch having a top end surface for forming the base end of the material and having an axially moving sliding portion and an axial hole penetrating in the axial direction; and an ascending moving end and a descending moving end of the counter punch. Counter punch rising end regulating means and counter punch descending end regulating means for respectively regulating, a knockout pin that is movably inserted in the axial hole of the counter punch in the axial direction, and the top end of the knockout pin from the top end surface of the counter punch. Knockout pin descending end regulating means for regulating the descending moving end of the knockout pin at a lower position, and knocking out by abutting on the lower end surface of the knockout pin. And a knockout pin located at the descending moving end, the lower punch and the upper die are used to compression-mold a product from the material, and the lift of the pin causes the counter punch to move. It is possible to push up the product by abutting the protruding portion formed by the shaft hole, raise the counter punch to the ascending moving end through the protruding portion, and further raise the knockout pin from the descending moving end to knock out the product. Characteristic forging device. 2. The forging device according to claim 1, wherein the knockout pin has a length dimension larger than a length dimension of the shaft hole. 3. The counter punch lowering end regulating means is a load supporting portion for contacting a lower end surface of the counter punch at a lowering moving end and receiving a load from the upper die. Forging device described in. 4. The counter punch upper end regulating means guides the movement of the counter punch by slidingly contacting a base end of the counter punch whose diameter is formed at the lower end of the sliding portion and a sliding portion of the counter punch. The forging device according to any one of claims 1 to 3, wherein the base end is a counter punch guide part that abuts from below. 5. The knockout pin descending end restricting means includes a small diameter portion formed in a shaft hole of the counter punch and a top end portion formed by expanding the diameter of the knockout pin engageable with the small diameter portion from above. Claim 1 characterized by the above.
The forging device according to any one of to 4. 6. The forging device according to claim 1, wherein the protruding portion is a discarding shaft portion.