JPH081299A - Extrusion pin and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an extrusion pin having good gas venting function. CONSTITUTION:The extrusion pin 1 is formed of a pin body part 4 and a flange part 2 arrange at the rear end of the pin body part 4. A center hole 3 allowing the front end part to communicate with the rear end part of the pin 1 is penetrated in the longitudinal direction of the pin and a porous body having many fine holes 5 extended in parallel to the longitudinal direction of the center hole 3 is fitted to at least the front end part of the center hole 3. The extrusion pin having good gas venting function is obtd. by providing the fine holes 5 extended in the longitudinal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion pin and a method for manufacturing the same, and more particularly to an extrusion pin having a gas releasing function and a method for manufacturing the same.

[0002]

2. Description of the Related Art Molds used for casting metal, molding resin, molding shell cores with shell mold sand, etc.
Extrusion pins are provided for extruding the molded product from the mold.

The conventional push-out pin has a cylindrical rod shape with a flange portion formed on the rear end side.

By the way, when casting a metal, molding a resin, or molding a core using shell mold sand, when the molten metal, molten resin, and shell mold sand are filled in the mold, air remaining in the mold The generated gas loses its place of escape and reacts with the molten metal, or remains as bubbles or voids in the molded product, resulting in product defects.

With a sand mold, ventilation can be achieved through the gaps between the sand grains, and such a problem can be solved. However, when a mold is used, it is an important issue to ensure the air permeability of the mold. .

Conventionally, various methods have been adopted to impart air permeability to a mold, and one example thereof is a method in which a porous member called a vent hole is provided at a local part of the mold.

[0007]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a mold provided with an extrusion pin, if the extrusion pin itself has a gas venting function, the mold is provided with good air permeability and residual air in the mold is provided. Although it is possible to more effectively remove the generated gas and the generated gas, hitherto, an extruding pin having a good gas releasing function has not been provided.

In some cases, residual air and generated gas in the mold may spontaneously escape from the slight gap between the extrusion pin and the inner wall surface of the extrusion pin insertion hole of the mold at the extrusion pin installation portion. However, in order to promote this gas escape, some devices have been devised to provide several grooves on the outer peripheral surface of the extrusion pin in the lengthwise direction, but sufficient degassing effect was obtained. I can't say that

On the other hand, a vent hole made of a porous sintered metal is known, and it is conceivable that the extruded pin is fired with such a sintered metal to give air permeability to the extruded pin. With a binder metal, sufficient strength as an extrusion pin cannot be obtained, which is not practical.

The present invention has been made in view of the above conventional circumstances, and an object thereof is to provide an extrusion pin having a good gas venting function and a method for manufacturing the same.

[0011]

According to a first aspect of the present invention, there is provided an extruding pin having a pin main body and a flange portion provided at a rear end of the pin main body. A push-out pin having a center hole communicating with the end face, which penetrates in the longitudinal direction of the pin, and in which a porous body is attached to at least the tip end portion of the center hole, wherein the porous body has a longitudinal direction of the center hole. It is characterized by having a large number of pores extending in a direction parallel to the direction.

According to a second aspect of the present invention, there is provided the extruding pin according to the first aspect, wherein the porous body is made of a metal wire material which is bundled and bonded so as to extend in a longitudinal direction of the central hole. The pores are formed between the wire rods.

According to a third aspect of the present invention, there is provided the push pin according to the second aspect, wherein the porous body is disposed only at a tip portion of the pin body portion, and the pin body portion has an inner peripheral surface of the porous body. It is characterized in that it is composed of a tip portion joined to the body and a hollow tube portion joined to the tip portion.

According to a fourth aspect of the present invention, there is provided the push pin according to the second aspect, wherein the porous body bundles a large number of metal wire rods and connects the metal wire rods to each other, and fits into a hollow hole of the pin body. It is characterized by being cut out into a size that

According to a fifth aspect of the present invention, there is provided a method for producing an extrusion pin according to the second aspect, wherein the metal tube is filled with a large number of metal wire rods, the space between the metal wire rods and between the metal wire rods. Characterized in that the metal pipe and the metal wire are integrated so that a gap remains between the metal pipe and the metal wire, and the metal pipe is cut in the thickness direction while leaving one end side of the obtained composite material. And

According to a sixth aspect of the present invention, there is provided a method for producing an extrusion pin according to the third aspect, wherein the metal pipe is filled with a large number of metal wire rods, and the metal wire rods are provided between the metal wire rods and between the metal wire rods. The metal tube and the metal wire are integrated so that a gap remains between the metal wire and the metal wire, and the obtained composite material is cut in a direction orthogonal to its axial direction, and then the outer diameter of the composite material It is characterized in that it is joined to one end side of a hollow tube having substantially the same outer diameter.

According to a seventh aspect of the present invention, there is provided a method for producing an extrusion pin according to the fourth aspect, wherein a large number of metal wire rods are bundled so that voids remain between the metal wire rods. A columnar body is cut out coaxially with the axial direction of the metal wire rod by integrating the metal wire rod, and the columnar body is attached to one end side of a hollow tube having an inner diameter substantially equal to the outer diameter of the columnar body. It is characterized by fitting.

[0018]

According to the extruding pin of the first aspect, the extruding pin exhibiting a good degassing function is provided by the pores extending substantially parallel to the longitudinal direction of the extruding pin.

According to the extruding pin of the second aspect, the extruding pin having the directionality formed between the metal wire rods and having uniform and good air permeability by the uniform pores existing at equal intervals is provided. To be done. The pores of this extrusion pin are
Since the inner surface is smooth and formed linearly, it can be easily removed even if foreign matter enters, and it can be used even for long-term use without lowering the air permeability.

Moreover, by appropriately selecting the diameter and shape of the metal wire to be used, it is possible to freely adjust the size and distribution state of the formed pores, the porosity, etc., and obtain the desired air permeability. You can

According to the extruding pin of the third aspect, the extruding pin having a gas venting function can be easily obtained by joining the distal end portion and the hollow tube portion.

According to the extruding pin of the fourth aspect, the extruding pin having a gas venting function can be easily obtained by fitting the cut out one into the pin main body.

According to the method for producing an extrusion pin of claim 5, the extrusion pin of claim 2 can be easily produced.

According to the method for producing an extrusion pin of claim 6, the extrusion pin of claim 3 can be easily produced.

According to the method for producing an extrusion pin of claim 7, the extrusion pin of claim 4 can be easily produced.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 (a) is a perspective view showing an embodiment of the push-out pin of the present invention, and FIG. 1 (b) is B- in FIG. 1 (a).
It is sectional drawing which follows the B line.

The push-out pin 1 of this embodiment has a collar portion 2 at the rear end.
Is provided, and in the central hole 3 of the pin main body portion 4 through which the central hole 3 that communicates the front end surface and the rear end surface of the pin is provided,
The metal wire rods 10 which are bundled so as to extend in the longitudinal direction of the center hole 3 and are coupled to each other are inserted, and a large number of metal wire rods 10 extending in the longitudinal direction of the center hole 3 are provided between the metal wire rods 10. The pores 5 are formed.

FIG. 4 shows the push-out pin 1 shown in FIG.
FIG. 4 is a perspective view showing an example of the manufacturing method of FIG. 1 in which a thick metal tube 11 and a large number of metal wire rods 10 as shown in FIG. Metal wire rod 1
After inserting and filling 0 (FIG. 4 (b)), the metal tube 11
An external force is applied from the outer circumference of the metal pipe 11 to plastically deform it so that voids remain between the metal pipe 11 and the metal wire rod 10 and between the metal wire rods 10. The metal tube 11 and the metal wire 10 are fixedly integrated by the processing strain and the frictional force generated at the interface between the metal tube 11 and the metal wire 10 and the interface between the metal wires 10 by the plastic deformation.

With respect to this integrated composite material 12 (FIG. 4 (c)), the metal pipe 11 is cut in the thickness direction thereof, that is, at the position of the broken line, leaving the collar forming portion, The extrusion pin 1 as shown in FIGS.

FIG. 2 (a) is a perspective view showing another embodiment of the push-out pin of the present invention, and FIG. 2 (b) is B of FIG. 2 (a).
It is sectional drawing which follows the -B line.

In the push-out pin 1A of this embodiment, the metal wire rod 10A is coaxially inserted and filled in the metal tube at the tip of the hollow tube 6 having the flange portion 2 on the rear end surface, and the pores 5 are left. The tip member 7 thus integrated is joined to form the pin body 4.

FIG. 5 shows the push-out pin 1 shown in FIG.
It is a perspective view showing an example of a manufacturing method of A,
A metal tube 11A and a large number of metal wire rods 10A as shown in FIG. 4A are prepared, and the metal wire rods 10 are placed in the metal tube 11A.
After inserting and filling A (FIG. 5 (b)), the metal pipe 11
An external force is applied from the outer circumference of A to the metal tube 11A and the metal wire rod 1
It is plastically deformed so that a void remains between the metal wire rod 10A and the metal wire rod 10A. Metal tube 1 due to plastic deformation
The metal pipe 11A and the metal wire 10A are fixedly integrated by the processing strain and the frictional force generated at the interface between 1A and the metal wire 10A and the interface between the metal wires 10A.

The integrated composite material 12A (FIG. 5 (c)) is cut to an appropriate length at the position of the broken line to obtain the tip member 7.

The extruding pin 1A as shown in FIGS. 2 (a) and 2 (b) is formed by joining the tip member 7 to the tip of the hollow tube 6 having the collar 2 at the rear end. obtain.

FIG. 3 (a) is a perspective view showing another embodiment of the push-out pin of the present invention, and FIG. 3 (b) is B of FIG. 3 (a).
It is sectional drawing which follows the -B line.

The extruding pin 1B of this embodiment has a metal wire rod 1 inside the tip of a pin body 4 having a collar 2 on its rear end face.
The porous member 8 in which 0B is coaxially bundled and integrated so as to leave the pores 5 is fitted.

FIG. 6 shows the push-out pin 1 shown in FIG.
It is a perspective view showing an example of a manufacturing method of B,
As shown in FIG. 6A, a large number of metal wire rods 10B are bundled and joined, and from this joined body, as shown in FIG. The member 8 is cut out and the porous member 8 is fitted to the tip of the center hole 3 of the pin body 4. As a result, the extrusion pin 1B as shown in FIGS. 3 (a) and 3 (b) is manufactured.

In the manufacturing method shown in FIGS. 4 and 5, a method for inserting and filling the metal wire rod 10 or 10A into the metal pipe 11 or 11A for plastic deformation is described with reference to FIGS.
This will be described with reference to FIG. In addition, in FIG.
8A is a horizontal sectional view, and FIG. 8B is a vertical sectional view.
In FIG. 12, (a) is a side view, (b) is a horizontal cross-sectional view, and (c) is a vertical cross-sectional view (cross-sectional view taken along line C-C of (b)).

In the present invention, as shown in FIG. 7, the plastic deformation is caused by the metal wire 10 inside the metal pipe 11 (or 11A).
(Or 10A) inserted and filled so that the voids remain, and the metal tube 11 and the metal wire rod 10 and the metal wire rods 10 can be plastically deformed so as to be fixed and integrated by the processing strain and friction. However, the method shown in FIGS. 8 to 12 can be used, for example, although there is no particular limitation.

That is, as shown in FIG. 8 (a), the metal pipe 11 having the metal wire rod 10 inserted therein is swaged.
8 (b), (c) by applying pressure to the entire outer peripheral surface of
As shown in FIG. 8, the diameter is reduced as a whole (in FIG. 8 (b), the broken line indicates the diameter before plastic deformation processing), and the composite material 12 in which the metal tube 11 and the metal wire rod 10 are fixedly integrated is formed. To get

Further, as shown in FIG. 9 (a), the roller 1
By rolling using No. 6, pressure is applied to the outer peripheral surface of the metal tube 11 into which the metal wire rod 10 has been inserted from above and below to deform it into an elliptical cross section as shown in FIGS. 9 (b) and 9 (c). 9 (b), the broken line shows the diameter before the plastic deformation process), and the composite material 12a in which the metal tube 11 and the metal wire rod 10 are fixedly integrated is obtained.

Further, as shown in FIG. 10 (a), the jig 1
By pressing using No. 7, pressure is applied from above and below to the outer peripheral surface of the metal tube 11 into which the metal wire rod 10 has been inserted.
As shown in FIGS. (B) and (c), the metal tube 11 and the metal wire rod 10 are fixed and integrated by deforming into an elliptical cross-section (in FIG. 10 (b), the broken line shows the diameter before plastic deformation processing). The compounded composite member 12b is obtained.

Further, as shown in FIG. 11 (a), the jig 1
8 by drawing, a partial pressure is applied to the outer peripheral surface of the metal tube 11 in which the metal wire rod 10 is inserted, and the diameter is partially reduced as shown in FIGS. 11 (b) and (c). Then, the composite member 12c in which the metal tube 11 and the metal wire rod 10 are fixedly integrated is obtained.

Further, as shown in FIG. 12 (a), one end of the metal tube 11 in which the metal wire 10 is inserted is fixed by a jig 19, and the other end is twisted by applying a force in the rotational direction to the first end.
As shown in FIGS. 2B and 2C, the metal pipe 11 and the metal wire rod 10 are twisted to obtain a composite member 12d in which the metal pipe 11 and the metal wire rod 10 are fixedly integrated.

In the present invention, the degree of plastic deformation is not particularly limited as long as the voids, that is, the pores remain, and the metal tube, the metal wire and the metal wire are stably fixed and integrated. Although there is no limitation, for example, when performing plastic deformation that reduces the cross-sectional area in the cross section by swaging, rolling, pressing, drawing, etc., the reduction rate of the cross-sectional area (before and after plastic deformation It is preferable that the difference between the cross-sectional areas divided by the cross-sectional area before plastic deformation) be about 10 to 70%.

In the present invention, in addition to plastic deformation, the metal tube and the metal wire may be integrated by joining.

In this case, the following can be adopted as a concrete joining method.

The metal wire rod and the metal tube are bonded to each other by using a synthetic adhesive such as cyan or polyester.

The metal wire rods and the metal tube are joined to each other by thermal stress such as shrink fit and shrink fit.

A brazing material such as silver or brazing is used to join the metal wire rods and the metal tube to the metal wire rod by brazing.

The metal wire rods and the metal pipes are bonded to each other by high-temperature diffusion bonding under conditions such as vacuum or in an inert atmosphere.

Further, in the method shown in FIG. 6, diffusion bonding under the following conditions is suitable as a method for bonding the metal wires 10B to each other.

Joining condition Temperature: 600 to 1400 ° C. Pressure: 5 to 1000 kg / cm ² Atmosphere: In inert gas or in vacuum As the metal tube used in the method shown in FIGS.
Hollow cross-section, hollow cross-section ellipse, hollow cross-section, and other hollow cross-section shapes, the size of which is
It depends on the size of the extrusion pin to be manufactured, etc., but in the normal case, the outer diameter (or the length of one side of the outside) is 5 to 1,000.
mm, inner diameter (or inner side length) 3 to 900 mm
In the method shown in FIG. 4, the wall thickness is 5.0 to 10.0.
mm, wall thickness 0.5-in the method shown in FIG.
It is about 2.0 mm.

The metal tube may have a groove formed in the longitudinal direction of the inner peripheral surface or the outer peripheral surface thereof.

In the method shown in FIGS. 4 to 6, the metal wire rod may have a circular cross section, an elliptical cross section, a rectangular cross section, or other irregular cross section, and the size thereof is a fine shape formed on the extruding pin. Normally, the diameter (outer diameter or the length of one side) is 0.1, although it depends on the size of the pores and the porosity.
It is about 5 mm.

As the metal wire rod, two different diameters are used.
You may use more than one kind.

The metal wire is not limited to the solid wire but may be a tubular material. In this case, the metal wire rod may have a hollow hollow circular shape, a hollow hollow elliptical shape, a hollow hollow rectangular shape, or another hollow hollow modified shape, and the outer diameter or the length of one side thereof is 0.1 to 10 mm, and the meat Thickness is 0.01
It can be set to about 8 mm.

Further, the metal wire may have a groove formed in the longitudinal direction of the outer peripheral surface thereof.

The extrusion pin of the present invention has an inscribed circle diameter of 0.0 by appropriately selecting the size and shape of the metal tube and the metal wire and the plastic working ratio and the joining conditions.
It is preferable that pores of about 5 to 0.5 mm are formed.

In the usual case, it is preferable to fill the metal tube with about 3 to 100,000 wires.

The metal constituting the metal pipe and the metal wire is a metal in a broad sense including an alloy, and specifically, alloy steel for machine structure (JIS standard SNC, SNCM, SCr,
SCM system, Tool steel (JIS standard SK, SKH, SK)
S, SKD, SKT series, stainless steel (JIS standard S
US), carbon steel, copper or copper alloy, aluminum or aluminum alloy, nickel or nickel alloy, titanium or titanium alloy are preferably used. The constituent metal of such a metal tube and the constituent metal of the metal wire may be the same or different, but preferably the same material is suitable.

Further, as the material of the pin body, the same material as described above can be used, and it is preferable that the metal tube, the metal wire and the material of the pin body are all the same.

In the extruding pin of the present invention, as shown in FIG. 13, in the flange portion, the hollow tube 21 forming the pin body and the hollow tube 22 forming the flange portion are integrally joined. It is also easy to form by.

The present invention will be described in more detail with reference to specific examples.

Example 1 The extrusion pin shown in FIG. 1 was manufactured according to the method shown in FIG.

Thirty-one SKD61 metal wires having the following dimensions were inserted into SKD61 metal pipes having the following dimensions, which were plastically deformed and integrated by swaging under the following conditions to produce a composite material having the following dimensions.

This composite material was subjected to a cutting process to manufacture an extrusion pin having the following size.

This extruding pin has an inscribed circle diameter of 0.1 mm.
A large number of pores were uniformly formed in the longitudinal direction, and when used in a mold, they had sufficient strength as an extrusion pin and also had a gas venting function.

Metal tube dimensions Outer diameter: 18 mm Inner diameter: 10 mm Length: 300 mm Metal wire rod dimension Straight diameter: 2 mm and 1 mm (19 2 mm and 1 mm
Length: 300 mm Swaging processing conditions I. Swaging machine Model: Rotary swaging machine Pressure: 30,000Kg Rotation speed: 370RPM Die: 4 directions II. Construction conditions (using lubricating oil at room temperature) Die diameter: φ20 mm Pressure: Total pressure = 30,000 Kg, per die =
7,500Kg Rotational speed: 370RPM Composite material size Outer diameter: 8.6mm Length: 340mm Extrusion pin size Tip outer diameter: 12mm Total length: 299mm Collar outer diameter: 17mm Collar length: 8mm Example 2 Fig. 5 The extrusion pin shown in FIG. 2 was manufactured according to the method shown in FIG. Thirty-one SKD61 metal wire rods having the following dimensions were inserted into SKD61 metal pipes having the following dimensions, and swaging was performed under the same conditions as in Example 1 to obtain a composite material having the following dimensions.

This composite material is sliced into a height (length)
A 15 mm tip member was manufactured, and this tip member was joined to an SKD61 hollow tube having the following dimensions by brazing to manufacture an extrusion pin.

This extruding pin has an inscribed circle diameter of 0.2 mm.
A large number of pores were uniformly formed in the longitudinal direction, and when used in a mold, they had sufficient strength as an extrusion pin and also had a gas venting function.

Metal tube dimensions Outer diameter: 13 mm Inner diameter: 10 mm Length: 200 mm Metal wire rod dimension Straight diameter: 2 mm and 1 mm (19 mm 2 mm and 1 mm
Length: 200 mm Composite material dimensions Outer diameter: 12 mm Length: 220 mm Hollow tube dimensions Overall length: 201 mm Inner diameter: 9 mm Tip outer diameter: 12 mm Collar outer diameter: 17 mm Collar length: 8 mm Example 3 The extrusion pin shown in FIG. 3 was manufactured according to the method shown in FIG.

Thousands of SKD61 metal wire rods having the following dimensions were bundled, sealed in a metal container under vacuum, and joined by the HIP (hot isostatic pressing) method under the following conditions. A cylindrical porous member having a size was cut out.

Metal wire rod dimensional diameter: 1.0 mm Length: 300 mm Welding condition Welding temperature: 1000 ° C. Welding pressure: 100 kg / cm ² Atmosphere: Inert gas Porous member Dimensional diameter: 7 mm Length: 10 mm The extruded pin was obtained by fitting the tip of the pin body having the following dimensions.

This extrusion pin has an inscribed circle diameter of 0.1 mm.
A large number of pores were uniformly formed in the longitudinal direction, and when used in a mold, they had sufficient strength as an extrusion pin and also had a gas venting function.

Pin body dimensions Overall length: 200 mm Inner diameter: 7 mm Tip outer diameter: 10 mm Collar outer diameter: 15 mm Collar length: 8 mm

[0078]

As described in detail above, according to the extruding pin of the present invention, an extruding pin having a gas venting function is provided, which prevents product defects due to residual air and generated gas in the mold, and is excellent. It is possible to obtain the product.

In particular, according to the extruding pin of the second aspect, it is possible to arbitrarily design the size, the porosity, and the distribution state of the pores for ventilation, and the optimum shape and size for the application place can be obtained. An extruded pin having air permeability can be obtained. In addition, the formed pores have a directionality and can be present at equal intervals, and uniform and good ventilation can be performed. In addition, the inner surfaces of the pores are smooth and linear, the foreign matter that has entered can be easily removed, and long-term use can be endured without reducing the air permeability. Therefore, it is possible to prevent the molten metal, the molten resin, and the shell mold sand from entering the pores of the mold, and to control the air permeability well.

According to the extrusion pins of claims 3 and 4, the extrusion pin which can be easily manufactured is provided.

Such an extruding pin of the present invention can be easily manufactured by the methods of claims 5 to 7.

[Brief description of drawings]

FIG. 1 shows an embodiment of an extrusion pin of the present invention, (a)
Is a perspective view, and (b) is a sectional view taken along the line BB of (a).

FIG. 2 shows another embodiment of the extrusion pin of the present invention,
(A) is a perspective view, (b) is sectional drawing which follows the BB line of (a).

FIG. 3 shows another embodiment of the extrusion pin of the present invention,
(A) is a perspective view, (b) is sectional drawing which follows the BB line of (a).

FIG. 4 is a perspective view showing an embodiment of a method for manufacturing the extrusion pin shown in FIG.

5 is a perspective view showing an embodiment of a method for manufacturing the extrusion pin shown in FIG.

6 is a perspective view showing an embodiment of a method for manufacturing the extrusion pin shown in FIG.

7 shows a state before plastic deformation in the method shown in FIG. 4, (a) is a transverse sectional view, and (b) is a longitudinal sectional view thereof.

FIG. 8 shows an embodiment of a plastic deformation method according to the present invention,
(A) is a side view, (b) is a cross-sectional view showing a state after plastic deformation, (c) is a vertical cross-sectional view.

FIG. 9 shows an embodiment of the plastic deformation method according to the present invention,
(A) is a side view, (b) is a cross-sectional view showing a state after plastic deformation, (c) is a vertical cross-sectional view.

10A and 10B show an embodiment of a plastic deformation method according to the present invention, in which FIG. 10A is a side view, FIG. 10B is a cross sectional view showing a state after plastic deformation, and FIG. .

11A and 11B show an embodiment of a plastic deformation method according to the present invention, FIG. 11A is a side view, FIG. 11B is a cross-sectional view showing a state after plastic deformation, and FIG. .

12A and 12B show an embodiment of a plastic deformation method according to the present invention, in which FIG. 12A is a side view, FIG. 12B is a cross sectional view showing a state after plastic deformation, and FIG. .

FIG. 13 is a perspective view showing a method of forming a collar portion.

[Explanation of symbols]

 1, 1A, 1B Extruded pin 2 Collar part 3 Center hole 4 Pin body part 5 Pore 6 Hollow tube 7 Tip member 8 Porous member 10, 10A, 10B Metal wire rod 11 Metal tube 12, 12A Composite member

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B22C 9/06 P B23K 20/00 360 G B29C 33/10 8823-4F 33/44 8823-4F 45 / 34 9350-4F 45/40 7639-4F

Claims (7)

[Claims] 1. A push-out pin having a pin body and a flange portion provided at a rear end of the pin body, wherein a center hole communicating the front end face and the rear end face of the push-out pin is formed in the pin longitudinal direction. An extrusion pin having a porous body attached to at least a tip portion of the central hole, the porous body comprising a large number of fine particles extending in a direction substantially parallel to a longitudinal direction of the central hole. An extrusion pin having a hole. 2. The extrusion pin according to claim 1, wherein the porous body is made of metal wire rods that are bundled and joined so as to extend in the longitudinal direction of the center hole, and the metal wire rods are provided between the metal wire rods. An extruded pin characterized by having pores formed therein. 3. The extruding pin according to claim 2, wherein the porous body is arranged only at the tip of the pin body, and the tip of the pin body has an inner peripheral surface joined to the porous body. An extruding pin comprising a hollow portion and a hollow tube portion to which the tip portion is joined. 4. The push-out pin according to claim 2, wherein the porous body is cut out to a size such that a large number of metal wires are bundled and connected to each other, and the hollow body of the pin main body is fitted. Extrusion pin characterized in that it is 5. The method for manufacturing an extrusion pin according to claim 2, wherein a metal tube is filled with a large number of metal wire rods, and voids are provided between the metal wire rods and between the metal tube and the metal wire rod. A method for producing an extrusion pin, characterized in that the metal tube and the metal wire are integrated so as to remain, and the metal tube is cut in the thickness direction while leaving one end side of the obtained composite material. 6. The method for manufacturing an extrusion pin according to claim 3, wherein a metal tube is filled with a large number of metal wire rods, and voids are formed between the metal wire rods and between the metal pipe and the metal wire rod. The metal tube and the metal wire are integrated so as to remain, and the obtained composite material is cut in a direction orthogonal to the axial direction thereof, and then a hollow tube having an outer diameter substantially equal to the outer diameter of the composite material is formed. A method for manufacturing an extrusion pin, characterized in that the extrusion pin is joined to one end side. 7. The method for manufacturing an extrusion pin according to claim 4, wherein a large number of metal wire rods are bundled and the metal wire rods are integrated so that voids remain between the metal wire rods. Extruding the composite material, the columnar body is cut out coaxially with the axial direction of the metal wire, and the columnar body is fitted to one end side of a hollow tube having an inner diameter substantially equal to the outer diameter of the columnar body. Pin manufacturing method.