JPH07323327A - Extrusion device of extrusion press - Google Patents

Abstract

PURPOSE:To prevent the enclosure of the outer shell of a rear end part of a billet into the billet at the time of upsetting and to obtain an extruded shape having good quality without blister by connecting a core block with radiating cooling holes through a cooling passage arranged in the same axial direction with a connection rod near the outer periphery of the core block. CONSTITUTION:Since the radiating cooling holes 74 are arranged in the radiating state outward from the center part near the outer surface 85 of the core block 70, the temp. of the outer surface 85 of a dummy block 2 at the time of upsetting can be cooled to 200-230 deg.C by passing the cooling water.Further, since pool type cooling grooves 73 are arranged to the outer peripheral part of the core block 70, the passage value can be made to be comparatively large. In this result, the heat in the inner part of a container 1 is restrained to be conducted to the outer peripheral surface of an outer ring 71 to promote the cooling of the inner part of core block 70. Therefore, the temp. of the core block 70 is made to be low and acted to be profitable to the strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion press for extruding an aluminum alloy or the like by extruding the billet in a container so that the skin of the rear end of the billet and the air inside the rear end of the billet are not caught. The present invention relates to an extrusion device.

[0002]

2. Description of the Related Art Conventionally, when starting extrusion molding, a billet having a diameter slightly smaller than the inner diameter of the container is loaded into the container, and the billet is pushed by an extrusion stem to perform an upset work for filling the billet into the container first. . At this time,
The air between the container and the billet is exhausted from the die side to the outside to prevent air from entering the billet.
It has also been considered to obtain an extruded product that is free of blisters.

That is, in order to sufficiently deaerate the inside of the container before the start of extrusion, for example, as described in Japanese Patent Application No. 5-60621 and Japanese Patent Application No. 5-190340, the container is Before contacting the die, the container is temporarily stopped by the temporary stop mechanism, and the die outer surface is sealed by the front part of the die ring seal attached to the front of the container, and the end surface of the die contacts the end surface of the die side of the container. It has been considered that the air accumulated in the container is vacuum-sucked through the deaeration hole of the die ring seal from the gap created so as not to allow it.

However, even with this, a sufficient effect was not always obtained. That is, in the device in such a case, as shown in FIG.
As shown in (a), since there is a gap d of, for example, about 0.1 to 0.3 mm between the container 1 and the dami block 2, the die ring seal 3 attached to the front part of the container 1
Even if an attempt is made to deaerate the air in the space S between the container 1 and the billet 4 from the outside, the outside air enters the space S through the gap d between the rear part of the container 1 and the dami block 2 and is deaerated. Cannot be achieved, or the ultimate vacuum is close. In the figure, 5 is a die and 6 is an extrusion stem.

Therefore, as shown in FIG. 5 (b), by slightly upsetting the billet 4, the rear portion of the billet 4 is located within a certain dimension h from the damy block 2 side, for example, 50 to 100 mm. The outer peripheral surface is brought into close contact with the inner peripheral surface of the container 1, and after completely sealing, deaeration is started.

[0006]

However, at this time, the area h of the rear portion of the billet 4 is upset in the atmospheric state, and at the same time, the air on the surface is caught in the billet 4. Then, it becomes a blister of an extruded profile extruded from the die 5.

On the other hand, at the time of upset after this state, slippage occurs between the relatively hot Damii block and the billet, and as a result, the skin at the rear end of the billet 4 is billet 4.
Get caught in the inside of. This wrapping occurs as shown by the arrow in FIG. 5 (c) and starts when the rear end of the billet 4 contacts the inner surface of the container 1 during upset, and the space S
Completely disappears and until the filling is completed and the upset is completed,
Continue in sequence. Therefore, the range of the seal portion indicated by h in FIG. 5B enters the inside of the billet 4.

Therefore, in the present invention, as a solution to these problems, as in Japanese Utility Model Laid-Open No. 3-81214 and Japanese Utility Model Laid-Open No. 4-197514, a cooling device for a fixed damy block is provided between the container and the extrusion stem. Is provided so that the cooling medium is sprayed or abuts against the extrusion action surface of the fixed damy block. However, the extrusion action surface of the fixed damy block is exposed during the idle time (about 15 to 25 seconds) of the extrusion press. About 450 to 250
There was a problem that it was difficult to lower the temperature until the temperature fell below ℃.

[0009] Further, some attempts have been made that the internal temperature of the fixed damy block itself (internally cooled type fixed damy block) may cause a large drop due to the temperature drop of the extrusion working surface. In the extrusion press, higher productivity is required, and idle time is also required to be 15 seconds or less. Under these conditions, the temperature does not drop to the desired temperature (for example, 250 ° C or less), and due to the structure, metal touch or metal seal The cooling medium communicating from the inside of the extrusion stem leaks between the core block and the outer ring that make up the Damii block, which leads to a deterioration of the operation and working environment.Especially during extrusion, the leaked cooling medium scatters and drip into the container. There was a problem.

The present invention has been made in view of the above problems, and at the time of upsetting, it is possible to prevent the outer skin of the billet rear end from being caught in the billet, and obtain a good quality extruded profile without blisters. To provide an extrusion device for an extrusion press.

[0011]

Therefore, in the present invention, as a solution to these problems, in the first invention, the dami block is cooled to reduce the slippage with the billet, and after the billet at the time of upset. The end part is prevented from being rolled up, and the leakage of the cooling medium is completely prevented.
That is, in the present invention, in the extrusion device of the extrusion press having the extrusion stem that pushes the billet inserted into the container toward the die side and the fixed type Damii block provided at the tip of the extrusion stem, the Damii block is provided on the core block and the outer periphery. Connection rod for connecting the Damii block, which has a hollow shape and extends in the axial direction inside the extruding stem, and a supply pipe and a discharge pipe for the cooling medium that extends in the axial direction inside the connection rod. Providing a plurality of radial cooling holes in the vicinity of the tip inside the core block from the tip of the supply pipe and the discharge pipe to the outer periphery of the core block, and in the vicinity of the outer periphery of the core block in the coaxial direction with the connection rod. The radial cooling holes are connected to the radial cooling holes via the cooling passages provided in. In the second invention, a ring-shaped sealing material is provided on the outer peripheral portion of the core block between the radial cooling holes and the pool groove.

[0012]

In the present invention, when upsetting, the damii block cooled from the inside is used for upsetting. Therefore, sliding between the billet rear end inner surface of the container rear end and the front end surface of the dami block is reduced. Therefore, at the time of upsetting, air is prevented from being entrained in the outer skin of the billet rear end portion and the portion thereof, and a good-quality extruded shape material in which blisters are prevented can be easily obtained.

Further, by sealing the front part between the core block and the outer ring with the seal material, it is possible to prevent the cooling medium from leaking from the damy block at the time of upsetting, and the life of the container is extended.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to one embodiment shown in FIGS. In FIG. 1, a container liner 1
On the die 5 side of the container 1 composed of a and the container tire 1b, an outer ring 15 concentric with the container 1 is fixed by bolts to the end surface of the container tire 1b on the die 5 side as shown in FIG. In addition, a seal ring 16 is provided on the inner peripheral surface side of the outer ring 15 so as to be able to move forward and backward, but not to be disengaged in a stepwise manner. A part of the seal ring 16 has a structure having a protrusion 16a protruding in the center direction, and when the container 1 is temporarily stopped with a gap of, for example, 2-3 mm left between the container 1 and the die 5, the die ring The protrusion 16a of the seal ring 16 is provided on the end face of the container 5a on the side of the container 5a by the spring 17 (in this embodiment, eight springs 17 are mounted at equal intervals between the container tire 1b and the seal ring 16). It is pressed and abutted in the extrusion direction (face seal) to make the clearance zero.

A deaeration hole 18 is provided above the seal ring 16.
There are two (in this embodiment), and from there are connected to a vacuum tank 11 and a vacuum pump 12 via a pipe 9 and an electromagnetic switching valve 10. 13 is a motor, 19 is an outer ring 1
5 is a heat-resistant sealing material that prevents air from entering between the seal ring 16 and the seal ring 16, and 20 is the outer ring 15 and the container tire 1.
Metal hollow ring to prevent air from entering between b, 21
Is a replaceable seal plate that prevents direct abrasion and air intrusion of the protrusion 16a of the seal ring 16 by repeated contact with the die ring 5a. Also, 4 is a billet, 6
Reference numeral 2 denotes an extruding stem, 2 is a fixed damy block which is attached to the tip of the extruding stem 6 and which is in close contact with the inner surface of the container 1 and pushes the rear end surface of the billet 4.

The container 1 is attached to a piston rod 25 of a container cylinder 24 attached to the end platen 23. Reference numeral 28 is a piston, and 29 is a cylinder tube forming a cylinder body. Container cylinder 2
The portion B on the piston head side of No. 4 is composed of a movement stopper block 26, a head block 27 that also serves as a stopper, and the like, and the piston 28 can be rapidly stopped at the maximum distance of the movement range of the movement stopper block 26. . When the piston 28 is temporarily stopped just before the rear end, the container 1 is stopped just before it hits the die 5. 37 is a plug on the rear part.

A hollow rod 31 having a plurality of communication holes for oil passage arranged in a zigzag pattern in the axial direction is integrally attached to the shaft core on the rear side, which is the head side of the piston 28, by a screw or the like. When 28 is retracted, the hollow rod 31 enters into the hole on the front end side of the movement stopper block 26.

The structure on the side of the extrusion stem 6 is as shown in FIG. In FIG. 2, 1 is a container, 6 is a tubular extrusion stem, 2 is fixedly provided on the front surface of the extrusion stem 6,
Further, it is a fixed type damy block slidably provided in the container 1. The rear end of the extrusion stem 6 is shown in FIG.
As shown in, the stem holder 53 and the pressure ring 5
It is fixed to the main crosshead 55 via the No. 4.

A tubular dami boss 56 is attached to the front face of the extruding stem 6 by pressing the rear end face thereof. The tip of a connection rod 57 having a circular outer cross section is screwed to the rear half of the dami boss 56. It is installed by installation. The rear end portion of the connection rod 57 is a large diameter portion 57a as shown in FIG. 1, and is engaged and fixed with a tapered surface in the hole at the rear end portion of the extrusion stem 6. In the connection rod 57, two parallel holes 57b and 57c are provided so as to penetrate in the axial direction.
A water supply pipe 58 and a drain pipe 59 are provided in b and 57c. The tips of the water supply pipe 58 and the drainage pipe 59 are firmly mounted in the holes 57b and 57c by interference fit, and the rear ends thereof extend into the pressure ring 54.

The end of the water supply pipe 58 has a pressure ring 5
A cooling medium supply device 62 is connected via a passage 60 formed by a pipe in 4 and an opening / closing valve 61. The end of the drainage pipe 59 is connected to the drainage port 64 through a pipe passage 63 in the pressure ring 54. A slight gap is provided between the inner peripheral surface of the extrusion stem 6 and the outer peripheral surface of the connection rod 57 in order to keep the core of the connection rod 57 in a flexible state. In addition, a slight gap is provided between the inner peripheral surfaces of the holes 57b and 57c and the outer peripheral surfaces of the water supply pipe 58 and the drain pipe 59 so that the connection rod 57 is not directly cooled.

In this case, since the water supply pipe 58 and the drainage pipe 59 are passed through the connection rod 57 with a clearance provided therebetween, the connection rod 57 is not directly cooled, and therefore, the temperature difference between the extrusion stem 6 and the connection rod 57 is reduced. The flexibility of the core of the dami block 2 is not impaired. Although the hole 57b in the connection rod 57 is provided so as to penetrate therethrough, the front end of the hole 57c is closed by the plug 65, and the opening 6 in the outer peripheral direction is formed.
It communicates with 6. 67 is an extrusion stem 6 and a dami boss 5
6 is a heat resistant packing, and 68 is a heat resistant packing between the holes 57b and 57c and the water supply pipe 58 and the drain pipe 59.

A tubular connection bolt 69 is arranged in the front half of the dami boss 56, and a core block 70 is fixed to the front side of the connection bolt 69 by screw mounting. A ring-shaped outer ring 71 is fixed to the front side of the dami boss 56 by screw mounting. The outer peripheral surface of the core block 70 is in contact with the inner peripheral surface of the outer ring 71, but a gap is provided between the rear end surface of the core block 70 and the front end surface of the dami boss 56, and the core block 70 is extruded during extrusion. Even if 70 is pushed a little backward, the rear end surface of the core block 70 is dami boss 56.
It does not hit the front end face of the.

The core block 70, the outer ring 71, the dami boss 56 and the like constitute the dami block 2 as one body. Therefore, the outer peripheral surface of the outer ring 71 on the front end side is sized to substantially contact the outer peripheral surface of the container 1. Further, the outer peripheral portion of the front end of the core block 70 has a tapered surface portion 70a that widens to the front side, and the outer ring 71
The taper surface portion of the inner peripheral portion of the front end can be closely attached.

The shaft core hole of the connection bolt 69 serves as a passage 72 for the cooling water, and the rear half or more of the outer peripheral surface of the core block 70, that is, the outer ring 71 and the inner and outer diameters of the core block 70. A ring-shaped pool groove 73 for cooling is provided in the fitting portion, and the tip end portion of the passage 72 extends to the vicinity of the outer surface 85 of the core block 70.

As shown in FIG. 3, a plurality of radial cooling holes 74 (8 in this embodiment) extending radially from the tip of the passage 72 to the outer ring 71 are provided.

The rear portion of the pool groove 73 is provided with a passage 75 provided in the core block 70 and the dami boss 56, and one end of this passage 75 has a connection rod 5
7 and the other end is connected to the radial cooling holes 74. The passage 75 is connected to the front portion and the rear portion of the pool groove 73 on the way, and the plugs 79, 80, 81, 82 are provided at the locations shown in FIG. 2 so that the cooling water in the reciprocating path always passes through the pool groove 73. Is installed. 76 is a plug, and 77 and 78 are packings such as heat resistant O-rings.

Next, the operation of the device will be described.
First, pressure oil is supplied to the rod side of the container cylinder 24, the piston 28 is moved leftward, and the container 1 separated from the die 5 is advanced. At this time, piston 2
While the distal end of the hollow rod 31 attached to 8 moves to the distal end of the stopper block 26, the piston 28
The retreat speed of is relatively high. Eventually, the hollow rod 31 begins to enter the hole of the stopper block 26, and the piston 28 decelerates.

In this state, the piston 28 continues to retract,
The tip surface portion of the piston 28 contacts the tip portion of the stopper block 26. At this time, the piston 28 completes stopping at an intermediate position due to the action of the stopper block 26. Then, due to the action of the stopper block 26, the accuracy of the stop position in the middle of the stroke is sufficiently ensured. At this time, the protrusion 16a of the seal ring 16 contacts the die ring 5a, and the gap 7 between the container 1 and the die 5 is, for example, 2 to 3 mm. The state at this time is shown in FIG.

When this operation is completed, the billet 4
When a billet loader (not shown) in a state where the bill is placed is lifted and the extrusion stem 6 is moved forward, the billet 4 is pushed into the container 1 and the billet 4 comes into contact with the end surface of the die 5 side, as shown in FIG. Like Further, the extrusion stem 6 advances to start upset.

However, before starting the upset, the cooling medium supply device 62 is operated to introduce a cooling medium such as cooling water into the radial cooling holes 74 and the pool groove 73 to cool the damii block 2 from the inside. deep. At this time, the cooling water enters from the rear of the extrusion stem 6, passes through the water supply pipe 58 in the connection rod 57 in the extrusion stem 6, passes through the passage 72, the radial cooling holes 74, and the passage 75, and the pool groove 73. And is discharged from the rear of the extrusion stem 6 through the passage 75 and the drainage pipe 59. In the present invention, the radial cooling holes 74 are formed on the outer surface 85 of the core block 70.
Since it is provided radially from the center to the outside in the vicinity, the temperature of the outer surface 85 of the damii block 2 at the time of upsetting can be cooled to 200 to 230 ° C. by passing cooling water. Further, since the pool-type cooling groove is provided on the outer peripheral portion of the core block 70, the volume of the passage can be made relatively large, and as a result, the heat inside the container 1 is protected by the outer ring 7.
Heat transfer to the outer peripheral surface of No. 1 is suppressed, and cooling of the inside of the core block 70 is promoted. Therefore, the temperature of the core block 70 is lowered, which is advantageous in terms of strength.
However, in this example, the idle time was 15 seconds. Similar to the pool groove 73, the radial cooling holes 74 do not easily vaporize cooling water and have a simple structure.

Therefore, when the upset is started in such a state, the rear end of the billet 4 in contact with the damee block 2 is cooled. When you start upset,
The outer peripheral end of the billet 4 on the extrusion stem 6 side rises and comes into close contact with the inner peripheral surface of the container 1. This close width is, for example, 20-
When it becomes 50 mm, a vacuum suction device such as a vacuum pump 12 is actuated to suck the air in the container 1 through the gap 7 between the container 1 and the die 5 to sufficiently bring the inside of the container 1 into a vacuum state.

At the time of performing the upset, the rear end of the billet 4 is cooled and the fluidity is considerably deteriorated. Therefore, the friction degree between the billet 4 and the front end face of the damy block 2 is increased, and the rear end of the billet 4 is increased. It is possible to prevent the end portion from being entangled in the outer skin, and to prevent air from being simultaneously entangled in the billet 4 due to the entanglement. Only the rear end of the billet 4 expands to seal the Damii block 2 Done. In this way, the air that causes blisters is prevented by cooling the damii block 2 to prevent the trailing end skin of the billet 4 and the air from being entrained inside and degassing the surface of the billet 4 on the front die 5 side. Can be fully removed.

Particularly, in this embodiment, various experiments were carried out, and if the front end face of the damy block 2 was 250 ° C. or lower, the billet 4
The fluidity on the rear end side is deteriorated, and the billet 4 is prevented from being caught in the outer skin of the rear end portion, and the formation of blisters in the extruded product profile can be prevented.

During the upset, the extrusion stem 6 continues advancing without a break, the billet 4 is crushed, and when the end surface of the billet 4 on the die 5 side begins to deform, the container 1 is advanced to the die 5 side to move to the container 1. The gap 7 of the die 5 becomes zero. The reduction of the gap 7 is performed by the backward movement of the movement stopper block 26.

Even in the process of decreasing the gap 7, the deaeration hole 8 of the die ring seal 3 is evacuated, and the deaeration space is immediately before the billet 4 is completely upset on the inner surface of the container 1. However, the gap S portion is, for example, 20 to
It is evacuated to 60 torr. When the billet 4 starts to be extruded from the die 5, the electromagnetic switching valve 10 is closed and the vacuum drawing from the die 5 side is stopped. However, the evacuation may be continued as it is.

In the above embodiment, the dami boss 56 and the outer ring 71 are separately formed and integrated with each other by screws, but this can be manufactured integrally from the beginning. Further, in the above embodiment, the water supply pipe 58 and the drain pipe 5 are provided inside the connection rod 57.
Although an example in which two 9 are provided apart from each other is shown, this is, for example, one cooling pipe having two vertically divided passages having a semicircular cross section, and two passages serving as water supply passages. It can also be used by dividing it into a drainage channel.

In this embodiment, the temporary stop mechanism is provided in the container cylinder 24 for temporarily stopping the container 1. However, the present invention is not limited to this, and the container 1 can be stopped by another method.
May be suspended.

Further, in this embodiment, even when the fixed damy block 2 having the structure of the present invention is used, it is further effective to provide a cooling device separately and inject the cooling water to the outer surface 85 (extrusion working surface) of the damy block 2. If there is a jet cooling for about 3 seconds within the idle time, 160-18
It is possible to reduce the temperature to 0 ° C.

Further, in the present embodiment, even when the fixed type Damii block 2 having the structure of the present invention is used, the billet 4 is placed on the billet loader (not shown) and positioned between the container 1 and the extrusion stem 6. In this state, the cooling water is sprayed using a cooling device and sprayed on the rear end of the billet 4 for about 3 to 5 seconds.
The temperature drops to 0 to 300 ° C.

After that, when the extrusion stem 6 is advanced to load the billet 4 into the container 1, the billet 4 of the billet 4 is synergistically combined with the cooling of the outer surface 85 by the cooling device provided in the extrusion stem 6 of the present invention. Since the rear end portion is cooled more and the fluidity of the rear end portion of the billet 4 can be suppressed, it is possible to prevent the rear end portion of the billet 4 from being caught in the outer skin.

[0041]

As is apparent from the above description, in the first invention of the present invention, the extruding stem for pushing the billet inserted in the container to the die side and the fixed type dami block provided at the tip of the extruding stem. In an extrusion device of an extrusion press having, a dami block is constituted by a core block and an outer ring provided on the outer periphery,
Provided inside the extruding stem is a hollow connection-shaped connection rod for damai block connection, and inside the connection rod is an axially extending cooling medium supply pipe and discharge pipe for the cooling medium. A plurality of radial cooling holes extending from the tip of the supply pipe and the discharge pipe to the outer peripheral portion of the core block are provided in the vicinity, and a cooling passage provided coaxially with the connection rod in the vicinity of the outer periphery of the core block. The radial block is connected to the radial cooling hole via the radial cooling hole, and in the second invention, a ring-shaped sealing material is provided on the outer peripheral portion of the core block between the radial cooling hole and the pool groove, so that the damy block is in contact with the billet. Can be upset in a state where it is cooled by the radial cooling holes having a large cooling ability close to the outer surface (extrusion surface). That is, the plurality of radial cooling holes has a relatively large volume, cooling water is less likely to be vaporized, and effective cooling is obtained. As a result, at the time of upset, the rear end of the billet can be appropriately cooled to prevent slippage on the Damii block, and it is possible to prevent the billet rear end skin and the air from being trapped inside the rear end. It is possible to prevent blister from occurring in the extruded profile.

Further, in the present invention, since the connection rod is provided in the extrusion stem and the supply pipe and the discharge pipe for the cooling medium are provided in parallel in this connection rod, the cooling medium passes inside. However, the external extrusion stem and connection rod are appropriately heated from the outside, and structurally unreasonable force does not act. That is, since the Damii block and the extrusion stem are contained in the container which is heated for about 80 to 90% during one cycle of the extrusion process, they are heated by the container. As a result, the extrusion stem extends in the axial direction, but at this time, if the connection rod is cooled directly and strongly from the inside, the connection rod does not extend in the axial direction. Then, the fixed type Damii block attached to the tip of the connection rod is strongly tightened by the extrusion stem, and as a result, the flexibility of the core is lost. Further, depending on the case, it may be broken from the threaded portion which is the connecting portion between the damey block and the connection rod.

However, in the present invention, since the pipe for the cooling medium is separately provided in the connection rod, the connection rod is not cooled so much from the inside,
The temperature difference between the extruding stem and the connection rod is small, and the connection rod also expands somewhat like the extruding stem, so the fixed damy block attached to the tip of the connecting rod is not tightened so much by the extruding stem. The flexibility of the damii block core is not impaired. The damy block does not need to be loosened because it tends to be slightly lightly tightened. Since the damai block is appropriately cooled, the hot strength does not decrease and the life is extended.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is an enlarged view of the extrusion stem side of FIG.

FIG. 3 is a front view seen from CC of FIG.

FIG. 4 is an enlarged cross-sectional view of a main part of a suction unit that sucks air through a minute gap between a die and a container.

FIG. 5 is an explanatory diagram showing, in chronological order, a working state at the time of upset in the conventional method.

[Explanation of symbols]

 1 Container 2 Damii Block 3 Die Ring Seal 4 Billet 5 Die 6 Extrusion Stem 7 Gap 8 Degassing Hole 12 Vacuum Pump 15 Outer Ring 16 Seal Ring 16a Projection 17 Spring 18 Degassing Hole 23 End Platen 24 Container Cylinder 25 Piston Rod 26 Stopper Block 27 Head block 28 Piston 31 Hollow rod 56 Damii boss 57 Connection rod 58 Water supply pipe 59 Drain pipe 62 Cooling medium supply device 69 Connection bolt 70 Core block 71 Outer ring 72, 75 Passage 73 Pool groove 74 Radial cooling hole 85 Outer surface (Extrusion) (Action surface)

Claims (2)

[Claims] 1. In an extrusion device of an extrusion press having an extrusion stem for pushing a billet inserted into a container toward a die side and a fixed type Damii block provided at a tip portion of the extrusion stem, an outer machine provided with a Damii block on a core block and an outer periphery thereof. A ring-shaped connection rod for connecting Damii block that has a hollow shape and extends in the axial direction inside the extrusion stem, and a supply pipe and a discharge pipe for the cooling medium that extends in the axial direction inside the connection rod. A plurality of radial cooling holes extending from the tip of the supply pipe and the discharge pipe to the outer periphery of the core block are provided in the vicinity of the tip inside the core block, and are provided coaxially with the connection rod in the vicinity of the outer periphery of the core block. Of an extrusion press characterized in that it is connected to the radial cooling holes through a cooling passage Extruder. 2. The extrusion device for an extrusion press according to claim 1, wherein a ring-shaped sealing material is provided on an outer peripheral portion of the core block between the radial cooling holes and the pool groove.