JPH0220614A - Bridge type extrusion die - Google Patents

Abstract

PURPOSE:To wholly remove residual billets in the die and to prevent a poor press-fit by forming both side faces of the front end of the bridge part in the extrusion direction into an inclined face part having a restricted tilt angle and by restricting the front end width of the both inclined face part. CONSTITUTION:The tilt angle theta of the inclined face parts 12, 12 of the both front end sides in the extrusion direction of the bridge part 9 of the bridge type extrusion working die 6 equipped with plural bridge part 9 supporting the core 10 on the male die 7 is made to be in the range of 20-30 deg.. At this case, when it is under 20 deg., the intensity of the front end part of the bridge part becomes difficult to keep, and if it exceeds 30 deg., the billet is not pulled out sufficiently. Further, the width (l) of the front end face is set in the range of 0.5-4mm. At this case, when the width (l) is under 0.5mm, the crack is apt to generate during the extrusion working and if it exceeds over 4mm, the billet is possible to remain.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a bridge type extrusion die, particularly to a bridge type extrusion die used for extrusion of metal materials such as aluminum.

2. Description of the Related Art In general, extrusion processing methods for hollow extruded materials include a mandrel method and a combination die method.

Furthermore, the combination dice method is classified into those using boathole dice, those using spider dice, and those using bridge dice. - Inside the shell, boathole dies are often used for extruding hollow shapes, especially hollow extrusions made of high strength aluminum alloys (e.g. 7000 series aluminum alloys) such as rear hawks, hollow rims of motorcycles, etc. A bridge die is used to extrude the material in order to withstand high extrusion pressure, avoid joint effects between old and new billets, and avoid poor crimping of the extruded material. In other words, the support beam part that supports the male core that defines the inner surface shape of the hollow extruded material is formed in a bridge shape, and when the bridge die is placed on the front surface of the container, the bridge part partially enters the billet hole. A bridge die is used which is designed to be set in a deep position.

By the way, in the extrusion process using the bridge die, after extruding one billet, the remaining portion of the billet remaining around the bridge portion in the bridge die, that is, the portion called press waste is removed. This is due to the following reasons. That is, impurities such as oxides are inevitably attached to the surface of the billet, and due to the nature of the metal flow of the billet, these impurities move into the bridge die at the final stage of extrusion. Therefore, if the next billet is extruded as it is, the residual portion of the previous billet containing many of the above-mentioned impurities will be extruded from the die, and the extruded material of this billet and the extruded material of the next billet will be different. Second, when the next billet passes through the bridge and is crimped together, impurities from the remaining billet may intervene in the crimped area, resulting in poor crimping. This is because the quality of the material will deteriorate.

Usually, the above-mentioned residual billet is removed as follows. First, after extrusion is started, extrusion is stopped while the rear end side of the billet remains within the billet hole of the container for a predetermined length. At this time, the rear end side of the billet is held by the container side due to the frictional force of the peripheral wall surface of the billet hole.

The container is then retracted from the bridge die. Then, due to the frictional force, the billet also retreats from the bridge die together with the container, the billet is pulled out from inside the bridge die, and the remaining billet is removed.

Problems to be Solved by the Invention However, in the conventional bridge die, when the residual billet is removed by the method described above, a part of the extruded material due to the billet remains particularly near the front end face of the bridge part. Therefore, there was a problem in that it was extremely difficult to completely remove the pressed debris from this part. After various investigations into the cause of this problem, it was discovered that the conventional bridge die had a problem with the shape of the front end of the bridge section. In other words, in the conventional bridge die, the front end of the bridge part in the extrusion direction is tapered with a slight slope on both sides, and the width of the front end face is also relatively wide. When pulling out the remaining billet, it is difficult to apply force in the pulling direction to the pressed scum located on the front end surface of the bridge part, and the billet is torn off near both side edges of the front end surface. However, it has been found that this method still causes problems such as poor crimping in extruded materials.

The purpose of the present invention is based on the above-mentioned findings, and in the above-mentioned residual billet removal work, removes the residual billet from the bridge die, including the pressed billet residue remaining inside the bridge die, especially on the front end surface side of the bridge part. It is an object of the present invention to provide a bridge type extrusion die that can be completely removed and thereby prevent the occurrence of poor crimping and the like in the next billet extrusion.

Means for Solving the Problems Therefore, the bridge type extrusion die of the present invention is a bridge type extrusion die including a plurality of bridge parts supporting a core in a male mold, in which the front end of the bridge part in the extrusion direction is Both sides of the part are formed as slope parts with an inclination angle θ in the range of 20 to 300, and the width Ω of the front end face between the tips of the rainforest face part is 0.5 to 4. The gist is that it is set within a range of 0m11.

Effect As a result of the above, when a force is applied to the remaining billet to pull it out from the die backwards after extrusion, the remaining billet located on the slope at the front end of the bridge part will be pulled in the direction along the slope. receives power from This force is effective for pulling out the billet because the inclination angle of the slope part is set within the above range, and therefore the billet is pulled out along the slope part. Moreover, since the width of the front end surface of the billet located at the front end surface of the bridge section is set to be narrow as described above, the billet is pulled out following the billet that is being pulled out along the slope section. It turns out.

As a result, the billet located on the front end side of the bridge portion is almost completely removed.

In the bridge-type extrusion die described above, the width ρ of the front end face is set in the range of 0.5 to 4II1m, which is 0.5m.
If it is less than 111, there is a high risk of damage such as cracks occurring on the front end surface during extrusion, and if it exceeds 4 m, billet may remain on the front end surface. Moreover, the reason why the slope angle θ of the slope part is set in the range of 20 to 300 is because
If it is less than 200, it will be difficult to maintain sufficient strength at the front end of the bridge, and if it exceeds 300, the billet cannot be drawn out sufficiently.

EXAMPLE Next, an example of the bridge type extrusion die of the present invention will be explained based on the drawings.

1 to 3 show an embodiment of the present invention.

In Figure 1, (1) is a container, and a billet (3) made of 7000 series aluminum alloy is placed in the billet hole (2) inside. Stem (5) through block (4)
) to push it forward (to the right in the figure). The front end opening of the billet hole (2) of the container (1) is equipped with a bridge-type extrusion die (
(hereinafter simply referred to as a "bridge die") (6) is provided. This bridge die (6) consists of a male die (7) and a female die (8). That is, as shown in Figs. 1 and 3, the male die (7) is configured to support the core (10) at the axial center position by four bridge parts (9)... The core (lO) is inserted into the molding hole (11) of the female mold (8).
). As a result, the billet (3) is extruded from the billet hole (2).
is divided into four parts at the bridge part (9), which are further crimped together at the front end side of the bridge part (9), and then connected to the peripheral surface of the core (10) and the molded hole (11). ) is formed into an extruded material (14) of a predetermined shape by being extruded from a forming gap (13) between the peripheral surface of the material and the peripheral surface of the material.

By the way, FIG. 2 shows a cross-sectional view taken along the line ■-■ in FIG. 1, that is, a cross-section of the bridge portion (9).

As shown in the figure, the bridge portion (9) has sloped portions (12) (12) formed on both sides of the front end portion in the extrusion direction, respectively. In this case, the inclination angle θ of the slope portions (12) (12) with respect to the extrusion direction is set in the range of 20 to 30 degrees, and the width Ω of the front end surface between the tips of the rainforest surface portions (12) (12) is 0.5. It is set in the range of ~4°Os. The reason for this is as described above. In particular, the inclination angle θ
is in the range of 23 to 270, and the width ρ of the front end face is in the range of 1 to 3 mIn.
It is preferable to set it within the range of .

Next, the operating state of the above embodiment will be explained.

After the stem (5) is operated in the direction of the arrow (A) in Fig. 1 to start extruding the billet (3), the front end surface of the dummy block (4) is aligned with the rear end surface of the bridge portion (9). distance e
, for example, stop extrusion when it moves to the 25# position. One reason for this is that in subsequent extrusion, due to the nature of the metal flow, the billet portion with many impurities will be extruded, and second, there is a gap between the peripheral wall of the billet hole (2) and the billet (3). This is to keep the frictional force above a certain level.

Next, the container (1) is moved backward in the direction of the arrow (B) in FIG. 1, and the container (1) is separated from the bridge die (6). Then billet (3) becomes billet hole (2)
It retreats together with the container (1) while being gripped by the container (1) due to the frictional force with the surrounding wall surface of the container (1).

This causes the billet (3) to receive a force in the direction of being drawn out from within the bridge die (6). that time,
The billet (3) located on the slope part (12) (12) of the bridge part (9) has its slope part (12) (
A force acts in the direction along 12). This force is applied to the slope (1
2) Since the inclination angle of (12) is set within the above range, there is sufficient force for pulling out, and therefore the slope part (1
2) It will be drawn out along (12). Moreover, the billet (
3), since the width of this front end face is set narrow as described above, the billet (3) is pulled out following the billet (3) that is being pulled out along the sloped portion (12) (12). become. As a result, the remaining billet (3) in the bridge die (6) is almost completely removed, including the billet (3) remaining on the front end side of the bridge portion (9).

As described above, in the above embodiment, the bridge portion (9
) on both sides of the front end in the extrusion direction.
), and the inclination angle θ of these slope portions (12) (12) and the width Q of the front end surface between the tips of both slope portions (12) (12) are set within the above ranges, respectively. Therefore, in the billet removal work, it is possible to almost completely remove the billet (3), including the billet (3) located on the front end side of the bridge part (9), and therefore, when extruding the next billet, the extruded material It is possible to prevent poor crimping and the like from occurring.

Table 1 below shows the extruded materials obtained by extrusion using the conventional bridge die and the extruded materials obtained by extrusion using the bridge die (6
) shows a comparison of the incidence of crimping defects (tube expansion cracks) with extruded materials obtained by extrusion processing. As is clear from the table, the bridge die (6
), it is possible to completely prevent the occurrence of crimping defects.

Table 1 Effects of the Invention As explained above, in the bridge type extrusion die of the present invention, both sides of the front end in the extrusion direction of the bridge portion are formed into sloped portions with an inclination angle θ in the range of 20 to 30°. and the width ρ of the front end surface between the tips of both slope parts is 0.5.
〜4.0 layers, so during the residual billet removal work, the residual billet inside the die, including the billet residue located on the front end side of the bridge part, can be almost completely removed. Therefore, it is possible to prevent crimping defects and the like from occurring in the extruded material during the next extrusion process of the billet.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the bridge type extrusion die of the present invention (cross-sectional view taken along line II in FIG. 3), FIG. 2 is a cross-sectional view taken along line ■-■ in FIG. 1, and FIG. The figure is a view taken along the line ■-■ in FIG. (6)... Bridge type extrusion die, (7)...
・Male mold, (9)...bridge part, (10)...core, (12)...slope part. Above Figure 1 Figure 2

Claims (1)

[Claims] In a bridge type extrusion die having a plurality of bridge parts supporting a core in the male die, both sides of the front end in the extrusion direction of the bridge part are sloped parts with an inclination angle θ in the range of 20 to 30 degrees. A bridge-type extrusion die characterized in that the width l of the front end face between the tips of both inclined surfaces is set in a range of 0.5 to 4.0 mm.