JPH09201618A - Hollow product extrusion die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the development of uneven thickness caused by disturbance of metal flow and obtain a hollow extrusion shape material having uniform quality by forming the billet pressing surface of a die for extruding as a recessed conical surface. SOLUTION: The die 3 for extruding the hollow extrusion product forms the recessed conical surface 20 to the pressing surface 30 for the billet. An angle forming the conical surface 20 with the plane 21 crossing at the right angle to the die 3 axial line, i.e., a die angle θ is desirable to set to 5-15 deg.. Further, the conical surface 20 is desirable to be formed so that a projected area to the plane 21 crossing at the right angle to the die 3 axial line becomes 50-100% of a projected area to the plane 21 of the whole pressing surface 3a for the billet in the die 3. Both metal flows 2a, 2b form laminated flows having the orientation and centripetal property toward a die hole 11 and do not collide by forming this conical surface 20. Therefore, the disturbance in the metal flows 2a, 2b is not developed and the hollow extrusion shape material 10 having uniform thickness size can be extruded.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a die for a hot extruder for continuously extruding hollow products such as seamless alloy pipes.

[0002]

2. Description of the Related Art Generally, in extrusion processing of hollow metal products such as aluminum alloys, an extrusion tool consisting of a die for defining the outer surface shape of the product and a mandrel for defining the inner surface shape of the product is mounted in a container B, This is done by pressing the billet and pushing it out of the die. There are two pressurizing methods: a direct extrusion method in which the die is fixed and the loose dummy is moved toward the die, and an indirect extrusion method in which the loose dummy is fixed and the die and mandrel are moved toward the loose dummy. There is. Among them, the indirect extrusion method is the mainstream because the frictional resistance between the inner diameter of the container and the billet is small and the pushing and pushing pressure can be reduced.

FIG. 4 is a sectional view showing a conventional example of a hot indirect extruder. In the figure, 1 is a container, 2 is aluminum which is heated to a predetermined temperature and filled in the container 1,
Billet made of metal material such as aluminum alloy, 3,
Reference numeral 4 denotes a die and a mandrel, which form an extrusion tool 5. 6 is a loose dummy which is arranged inside the container 1 so as to face the die 3, and 7 and 8 are stems. The die 3 is fitted into the container 1 and has a die hole 11 formed at the center thereof and having a diameter increased in the extrusion direction which defines the outer surface shape of the extrusion profile 10. The material of the die 3 is hot tool steel, for example, JIS G4404 (1983) SK.
D61 or the like is used. The mandrel 4 that defines the inner surface shape of the extruded shape member 10 is attached to the tip of a holding member 12 that slidably penetrates the loose dummy 6. The tip surface of the mandrel body 13 has a die hole 11 for the billet 2.
A tapered surface 16 is formed in order to facilitate the inflow into.

To perform the extrusion process, the die 3 and the mandrel 4 are integrally moved forward to the right in the figure to pressurize the billet 2 in the container 1 and push it out from the gap between the die hole 11 and the bearing 14. Hollow extrusion profile 10
Can be manufactured.

[0005]

However, in the above-described conventional hot indirect extrusion processing machine, the surface of the die 3 for pressing the billet 2, that is, the billet pressing surface 3a is a surface perpendicular to the axis of the die 3. To form
There is a problem that the flow of the billet 2 becomes non-uniform near the die hole 11. That is, when the billet near the inner peripheral surface of the container 1 hits the billet pressing surface 3a, the billet is diverted to the center direction of the container 1 at a substantially right angle.
The billet near the center of the container 1 becomes a metal flow 2b flowing along the outer periphery of the mandrel 4. Of these, the metal flow 2b is the billet pressing surface 3a.
The metal flow 2a, which has been changed in direction, collides with the metal flow 2a at a substantially right angle, so that the flow is disturbed. for that reason,
The wall thickness dimension of the hollow extruded profile 10 changes (uneven thickness), and a product of uniform quality cannot be obtained.

Then, the inventors of the present invention conducted various experiments to examine the influence of the angle of the billet pressing surface 3a (hereinafter referred to as die angle) on the metal flow and uneven thickness, and found that the die angle was within a certain angle range. It was confirmed that when set, the disorder of metal flow can be reduced and the occurrence of uneven thickness can be reduced. This is a metal flow 2 depending on the die angle.
It is presumed that this is because a and 2b can be provided with directionality and centripetality, and no turbulence occurs in the flow that causes uneven thickness.

Therefore, the present invention has been made on the basis of the above-mentioned conventional problems and experimental results. The object of the present invention is to prevent the occurrence of uneven thickness due to turbulence of the flow and to provide a uniform quality hollow extrusion. It is an object of the present invention to provide a die for hollow product extrusion capable of manufacturing a profile.

[0008]

In order to achieve the above object, the present invention provides a hollow product extruding die that defines the outer surface shape of an extruded profile, in which the billet pressing surface of the die is formed into a concave conical surface. Characterize. In the present invention, the angle formed by the conical surface and the surface orthogonal to the die axis is 5 ° to 1
The feature is that it is set to 5 °. Further, the present invention provides
The projected area of the conical surface on the surface orthogonal to the die axis is
It is characterized in that it is set to 50% to 100% of the projected area of the entire billet pressing surface.

If the angle between the conical surface and the surface orthogonal to the die axis (die angle) is less than 5 °, the directionality and centripetality of the metal flow are small, and flow turbulence occurs, and the effect of the present invention is remarkably exhibited. Absent. Further, if it exceeds 15 °, it is considered that the resistance between the metal and the billet pressing surface of the die and the resistance between the metal and the loose dummy are reversed when the extrusion residual billet becomes small, but the flow of metal during extrusion is A backflow easily flows from the flow along the billet pressing surface to the mandrel side along the inner surface of the loose dummy, and the metal structure of the extruded hollow product becomes nonuniform. When the projected area of the conical surface with respect to the surface orthogonal to the die axis is less than 50% of the projected area of the entire billet pressing surface, the effect of the present invention in which the conical surface is formed is small when the die angle is small, As seen in the conventional product of FIG. 4, turbulence occurs in the aluminum flow, and the product tends to have uneven thickness.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the drawings. FIG. 1 is a cross-sectional view of a hot indirect extruder using a die for hollow product extrusion according to the present invention. The same members as those shown in the section of the prior art are designated by the same reference numerals and the description thereof will be omitted. In the figure, the die 3 is a metal flow 2a, 2
The billet pressing surface 3 is provided so that b has directionality and centripetality.
A concave conical surface 20 is formed on a. This conical surface 20
The angle between the surface 21 and the surface 21 orthogonal to the die axis, that is, the die angle θ is set to 5 ° to 15 °. Further, the conical surface 20 has a projected area with respect to the surface 21 orthogonal to the die axis, and the surface of the entire billet pressing surface 3a of the die 3 is the surface 21.
Is formed to be 50% to 100% of the projected area.

When the die angle θ is less than 5 °, the directionality and centripetality of the metal flow are small and the flow is disturbed, so that the effect of the present invention is not remarkable. Further, if it exceeds 15 °, it is considered that the resistance between the metal and the billet pressing surface 3a of the die 3 and the resistance between the metal and the loose dummy 6 are reversed when the extrusion residual billet becomes small. The flow is likely to cause a reverse flow from the flow along the billet pressing surface 3a to the mandrel side along the inner surface of the loose dummy 6, and the metal structure of the extruded hollow product becomes nonuniform. If the projected area of the conical surface 20 is less than 50% of the projected area of the entire billet pressing surface 3a, the effect of the present invention in which the conical surface is formed is small when the die angle θ is small. As can be seen, turbulence occurs in the flow of aluminum and the product tends to have uneven thickness, which is not preferable.

In the die 3 having such a structure, since the conical surface 20 allows the metal flows 2a and 2b to have directionality and centripetality, it is possible to prevent turbulence of the flow. That is, when the conical surface 20 is provided, the metal flow 2a on the outer peripheral side is turned by the die pressing surface 3a and then forms a flow along the conical surface 20 toward the die hole 11. This conical surface 20
The metal flow along is at the same angle as the die angle θ,
It is inclined with respect to the die axis. The metal flow 2b on the inner peripheral side is turned toward the die hole 11 along the metal flow 2a because the metal flow 2a along the conical surface 20 is inclined with respect to the die axis. . Therefore, the two metal flows 2a and 2b form a laminar flow having directivity and centripetality, head for the die hole 11, and do not collide with each other. Therefore, the metal flows 2a and 2b are not disturbed, and the hollow extruded profile 10 having a uniform wall thickness can be extruded.

[0013]

EXAMPLES Next, the inventors of the present invention conducted experiments to see how changing the die angle θ affects the thickness deviation value. [Embodiment 1] FIG. 2 shows that the die angle θ of the conical surface 20 is 10 °.
It is a figure which shows the relationship between the thickness deviation value and extrusion amount when the projected area of the conical surface 20 is 70% of the projected area of the entire billet pressing surface. In the figure, a broken line 30 indicates an eccentricity value of an extruded profile produced using a conventional die in which the billet pressing surface is perpendicular to the die axis, and a solid line 31 indicates a billet pressing surface on the conical surface 20.
The eccentricity value of the extruded profile produced by using the die according to the present invention in which is formed is shown. As an extruded alloy, JIS 50
Extruded with 56. The outer diameter of the extruded shape is 45φ mm,
The wall thickness was 6 mm.

[Embodiment 2] FIG. 3 shows the relationship between the thickness deviation and the extrusion amount when the die angle θ of the conical surface 20 is 5 ° and the projected area of the conical surface 20 is 60% of the projected area of the entire billet pressing surface. FIG. JIS 6061 was used as the extruded alloy, and the extruded profile had an outer diameter of 100 mm and a wall thickness of 5 mm.

As is apparent from FIGS. 2 and 3, when the conical surface 20 is formed on the billet pressing surface 3a, the uneven thickness value becomes smaller than that of the conventional die in which the billet pressing surface is orthogonal to the die axis. Further, this result shows a common tendency when the die angle θ is 5 ° or more and the projected area is 50% to 100%. However, the die angle θ is preferably 15 ° or less as described above.

[0016]

As described above, in the hollow product extruding die according to the present invention, the billet pressing surface is formed as a concave conical surface, so that the metal flow can be provided with directionality and centripetal property. It is possible to prevent the occurrence of disorder.
Therefore, uneven thickness does not occur in the product, a product of uniform quality can be manufactured, and the yield can be improved.
Further, according to the present invention, the angle of the conical surface is set to 5 ° to 15 ° with respect to the surface orthogonal to the die axis, and the projection area of the conical surface with respect to the surface orthogonal to the die axis is projected on the entire billet pressing surface of the die. Since it was set to 50% to 100% of the area,
The occurrence of turbulence in the flow is small, and the amount of pressing at the end of extrusion can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a hot indirect extruder using a die for hollow product extrusion according to the present invention.

FIG. 2 is a diagram showing a relationship between a thickness deviation value and an extrusion length when a conventional die is used and when a die according to the present invention is used.

FIG. 3 is a diagram showing a relationship between a thickness deviation value and an extrusion length when a conventional die is used and when a die according to the present invention is used.

FIG. 4 is a cross-sectional view of a conventional hot extruder.

[Explanation of symbols]

1 ... Container, 2 ... Billet, 2a, 2b ... Metal flow, 3 ... Die, 3a ... Billet pressing surface, 4 ... Mandrel, 5 ... Extrusion tool, 6 ... Loose dummy, 20 ... Cone surface, .theta .... Die angle, 21 ... A plane orthogonal to the die axis.

Claims (3)

[Claims] 1. A hollow product extruding die for defining an outer surface shape of an extruded profile, wherein a billet pressing surface of the die is formed as a concave conical surface. 2. The hollow product extruding die according to claim 1, wherein the angle formed by the conical surface and the surface orthogonal to the die axis is set to 5 ° to 15 °. 3. The hollow product extruding die according to claim 1, wherein the projected area of the conical surface with respect to the surface orthogonal to the die axis is 50 times the projected area of the entire billet pressing surface.
% To 100%, which is a die for hollow product extrusion.