JPH03198912A - Extrusion molding method for combined billet - Google Patents

Abstract

PURPOSE:To prevent the crack from generating in inside layer of the combined billet and to improve the manufacturing yield by forming the lubricating layer on the surface of combined billet and extruding it with the indirect extruding method. CONSTITUTION:The combined billet 1 is extruded by the indirect extrusion method to move the container 2 to be charged with the combined billet 1 with the same speed as the stem 3 to extrude the combined billet 1. Therefore, because the relative displacement between the extruding blank material and the inside surface of the container is not generated, the lubricating layer formed on the extruding blank material surface is not stripped in the extruding. And the lubricant on the surface of the extruding blank material is supplied to the inside surface of dies 4 successively, and the lubricant is supplied to the inside surface of the dies by a fixed quantity from the beginning of extrusion to the finish.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for extruding a composite billet made of at least two metal materials, such as a superconducting billet composited with a stabilizing material.

[Conventional technology and its issues]

Extrusion methods include direct extrusion and indirect extrusion. In the former, friction occurs between the billet surface and the inner surface of the container and die, leading to an increase in extrusion pressure and uneven metal flow. Improvements have been made by applying lubricant to the inner surface of the die.

On the other hand, in the latter indirect extrusion method, the container and the extruded material move together, eliminating friction with the container, but when extruding materials with poor extrudability such as composite billets, a die is used instead of a flat die to resist deformation. A tapered die is used to reduce the friction, but in this case the contact area with the die increases and the frictional force increases, so lubricant is applied to the inner surface of the die even in indirect extrusion, and the inner surface of the container is also lubricated to prevent seizure. agent is applied.

However, since the lubricant is not replenished during the extrusion process, the lubricant on the inner surface of the die gradually disappears, and in the latter half of the extrusion process, the frictional force between the extruded material and the inner surface of the die increases, slowing down the flow of the material in the outer layer. As a result, the material in the inner layer flows before the material in the outer layer. In this way, when the flow rate of the material in the inner layer is faster than that of the material in the outer layer, tension is applied to the inner layer. There was a problem in that the cracked part was cut off as a defective material and the manufacturing yield was significantly lowered.

[Means and actions to solve the problem]

The present invention was made as a result of intensive research in view of the above situation, and its purpose is to supply a lubricant at a high temperature during rolling to the inner surface of the die without interruption throughout the rolling process, thereby making it possible to manufacture high-quality extruded materials over the entire length. An object of the present invention is to provide a method for extruding a composite billet.

That is, the present invention is a method for extruding a composite billet made of at least two types of metal materials, characterized in that the composite billet is extruded by an indirect extrusion method with a lubricant layer formed on the surface of the composite billet. It is something to do.

As mentioned above, the extrusion processing method includes, for example, a container 2 loaded with a composite billet 1 as shown in FIG. There is an indirect extrusion method and a direct extrusion method in which only the stem 3 moves in the direction of the die 4 as shown in Fig. 2, and in the former there is no relative displacement between the inner surface of the container 2 and the composite billet l; Therefore, no frictional force is generated between the two and the extrusion pressure can be lowered, and the latter has the advantage that the apparatus can be simplified.

In the method of the present invention, a lubricant layer is formed on the surface of the composite billet, and this is extruded using an indirect extrusion method. As mentioned above, in the extrusion method, there is no relative displacement between the extruded material and the inner surface of the container, so the lubricant layer formed on the surface of the extruded material does not peel off during extrusion, and the extruded material remains on the inner surface of the die. This is because the lubricant on the surface is supplied one after another, and the lubricant is quantitatively supplied to the inner surface of the die from the start to the end of extrusion.

In the method of the present invention, the lubricant layer formed on the surface of the composite billet may include a lubricant containing carbon dissolved in water glass or sulfurized M
It is formed by applying a normal lubricant such as a lubricant containing O dissolved in oil, but these lubricants can be applied to a composite billet and then heated at a low temperature to evaporate water, etc. to improve adhesion. This is preferable because the lubricant is not heated in the container and is not peeled off.

〔Example〕

The present invention will be explained in detail below using examples.

Example 1 A Nb-Ti alloy bar of 180111111φ was prepared with an inner diameter of 1
It was charged into a hollow billet of oxygen-free copper with an outer diameter of 82+mmφ and an outer diameter of 280mm+φ, and both ends of the hollow billet were covered with disk-shaped lids made of oxygen-free copper, the inside was evacuated, and then welded and sealed to form a composite billet. . Thereafter, this composite billet was heated to 800°C and extruded into a single-core superconducting wire material of 50 mmφ by the indirect extrusion method shown in FIG.

During extrusion, a lubricant containing carbon dissolved in water glass was applied to the container, the inner surface of the die, and the surface of the composite billet. The composite billet was coated with lubricant, heated to 100°C and baked, and then loaded into a container.

In addition, when we investigated the change in extrusion pressure over time, it was suggested that a constant extrusion pressure was maintained even in the latter half of the extrusion process, as shown in Figure 1, and lubricant was smoothly supplied to the inner surface of the die. .

Comparative Example 1 A single-core superconducting wire material was manufactured in the same manner as in Example 1 except that no lubricant was applied to the surface of the composite billet.

When the change in extrusion pressure over time was investigated in the same manner as in Example 1,
As shown in FIG. 4, the extrusion pressure increased in the latter half of extrusion, suggesting that the supply of lubricant to the inner surface of the die was interrupted.

Comparative Example 2 A single-core superconducting wire material was manufactured by the same method as in Example 1 except that the composite billet was extruded by the direct extrusion method shown in Figure 2. The change was the same as that of the comparative example, suggesting that the supply of lubricant to the inner surface of the die was interrupted in the second half.

Each single-core superconducting wire material thus obtained was examined for the presence or absence of internal defects by ultrasonic flaw detection.

The results are shown in Table 1.

As is clear from Table 1, no defects were detected over the entire length of the product manufactured using the method of the present invention.

This superconducting wire material was drawn to a diameter of 1.0 am by heating and annealing during the drawing process, but no cracks occurred and a sound wire material was obtained.

On the other hand, in the comparison method product (Comparative Example 1.2), cracks were detected at the end 1/4 and beyond. This is because in Comparative Example 1, no lubricant layer was formed on the surface of the extruded material, and in Comparative Example 2, due to the direct extrusion method, the lubricant layer formed on the surface of the composite billet rubbed against the inner surface of the container and peeled off. In both cases, the cause was an interruption in the supply of lubricant to the inner surface of the die.

The case of extrusion manufacturing a single-core superconducting wire material has been described above, but the method of the present invention involves drawing the above-mentioned single-core superconducting wire material into a superconducting wire material, and filling a Cu pipe with a large number of these wire materials to form a composite. It can also be applied to the production of a multicore superconducting wire material by forming a billet and extruding it.

Furthermore, the method of the present invention is applicable not only to the extrusion production of superconducting wire materials but also to the production of Ag
It can also be applied to the production of composite materials etc. coated with Cu.

〔effect〕

As described above, according to the method of the present invention, lubricant is supplied quantitatively to the inner surface of the die from start to finish, so cracks do not occur in the inner layer of the composite billet, and therefore the manufacturing yield is improved and industrial It has a remarkable effect.

[Brief explanation of drawings]

Fig. 1 is an explanatory longitudinal cross-sectional view showing an example of the indirect extrusion method used in the method of the present invention, Fig. 2 is an explanatory longitudinal cross-sectional view of the direct extrusion method, and Fig. 3 is a temporal change in extrusion pressure in the method of the present invention. FIG. 4 is an explanatory diagram showing a change in extrusion pressure over time in a conventional method. 1--Composite billet, 2--Container, 3--Stem, 4--Dice. Composite billet No. 1 Composite billet diagram Figure 2

Claims (1)

[Claims] A method for extruding a composite billet made of at least two types of metal materials, characterized in that the composite billet is extruded by an indirect extrusion method after forming a lubricant layer on the surface of the composite billet. Processing method.