JPS6025846B2 - Manufacturing method of single-core superconducting wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a single-core composite superconducting wire, particularly a method using hydrostatic extrusion.

Conventionally, as shown in Fig. 1, a method for producing a single-core composite superconducting wire involves separately processing a superconducting material as a core material and a stabilizing material such as copper or copper alloy as a covering layer. A method is known in which the wire is made into a relatively thin wire or tubular shape, and then the former is inserted into the latter to form a single composite wire.

Regarding the disadvantages and problems of this method, each constituent material is processed and manufactured separately as described above, but among these, for tubes made of steel or copper alloy stabilizing materials, generally melted and cast cylindrical blocks are used. The billet for extrusion made from is rough-processed in the cold using a reducer for hot extrusion or a drawing bench, and then processed to have a smooth surface using a coiled tube, etc., to a specified size, and then straightened. Straighten and cut to required length. This processing method is industrially well-established and produces high-quality small pipes very efficiently.

However, on the other hand, the superconducting material that is the core material is, for example, N
Taking the case of b-Ti alloy as an example, in the case of this alloy, a melted and cast mirror ingot is heated to 800 to 100 by a method such as forging.
000, followed by rough processing by rolling swaging, and after smoothing the surface, drawing and wire drawing are performed to reduce the area and finish. However, in the case of this conventional process, surface oxidation is severe during hot working, and there is a risk that oxides of the material generated at that time or peeled off pieces of the processing tool may be pushed into or caught up in the workpiece as foreign matter.

These foreign substances cause wire breakage during subsequent cold working, such as drawing and wire drawing.

In addition, this material has greater reactivity with tools than steel, etc., and for example, tends to cause friction with the die during wire drawing, reducing the surface quality of the wire drawing material, or in extreme cases. This often leads to wire breakage, and therefore wire drawing requires careful attention to maintain its lubricity.

Surface and internal defects in single-filament wires cause non-uniform deformation (waisting) and wire breakage during processing of multi-filament wires, for example during drawing.

Therefore, when inserting a separately prepared Nb-Ti wire into a steel pipe, a surface inspection is required in advance over an enormous length, which requires an immeasurably large amount of work. Not limited to Nb-Ti, many superconducting materials are generally more difficult to process than copper and aluminum, and have similar problems in terms of manufacturing and quality control.

It should be noted that the surface of superconducting materials needs to be subjected to a considerable amount of surface cutting to remove defects such as surface indentation and entrainment of the oxide layer after hot working, which significantly reduces material yield. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a superconducting wire, which eliminates the drawbacks of the prior art described above, allows efficient manufacturing operations, and provides a high-quality composite wire.

The gist of the present invention is to insert a solid billet made of a superconducting material into a previously prepared hollow pellet made of a stabilizing material such as copper or copper alloy, cover both ends with plugs, and vacuum degas the hollow billet. In a method for manufacturing a single-core composite superconducting wire by isostatically extruding a composite billet obtained by sealing a billet and a plug by welding, and further drawing if necessary,
A method for manufacturing a single-core superconducting wire, characterized in that a solid billet made of the above-mentioned superconducting material is melted and cast or forged and used as it is.

Therefore, in this method, the superconducting material that is the core material and the stabilizing material such as copper or copper alloy that is the coating material are separately rough-processed from the raw materials, finished, and then joined together. By combining materials and isostatic extrusion,
This is a method of manufacturing a single-fiber composite wire of a predetermined size by integrating, flattening, and then performing drawing, wire drawing, etc., if necessary.

FIG. 2 shows a process diagram of the present invention in which a copper tube (hollow billet) is used as a stabilizing material. In the present invention,
As the stabilizing material, in addition to knots or copper alloys, aluminum or its alloys, which have lower magnetic and electrical resistance than copper at cryogenic temperatures, can be used; examples of copper or copper alloys include electrical steel, oxygen-free steel, etc. In addition to pure steel with high electrical and thermal conductivity, copper alloys containing components such as Sn and Ga that mainly constitute a compound superconductor are used.

In addition, examples of superconducting materials include Nb-Ti alloy, Nb
- Alloys that exhibit superconductivity such as Zr-based alloys or N
Metals such as B and V, which are constituents of compound superconductors, are used.

Next, embodiments of the present invention will be described.

Example 1 In Fig. 3, a hollow billet steel pipe 1 made of stabilizing material with an outer diameter of 1600 mm, a wall thickness of 6 mm, and a length of 120 mm was prepared in advance.
A Nb-Ti alloy ingot 2 with an outer diameter of 1,460 mm and a length of 1,100 mm is inserted inside, and both ends are covered with copper plugs 3, 3', and after vacuum degassing, it is sealed by electron beam welding. In Fig. 5, the single-○ composite billet 4 is extruded using castor oil 10 as a force medium at an extrusion temperature of 30,000 and a final extrusion pressure of 1,400.
A single-fiber composite wire 5 having a core material of Nb-Tj with a copper ratio of 0.2 was obtained by isostatically extruding a wire having an outer diameter of 2,501 mm at a temperature of 0 k9/ground.

In addition, in FIG. 5, 11 is a container, 12 is a stem,
13 is a die.

The cross section of this extruded material was examined, and no oxides or foreign matter were found, and no reaction products were generated at the copper/Nb-Ti interface, indicating that both constituent materials were bonded extremely strongly. I found out that there is.

This extrusion was then carried out by drawing to draw the wire to a wire size of 100 mm. However, there were no problems such as die burning or wire breakage that are currently a concern with Nb-Ti single wires, and the area reduction process was carried out very smoothly.

Example 2 In Fig. 3, the outer diameter 1600 and the inner diameter 91 prepared in advance are
0. Length 120cm Hollow billet barrel made of stabilizing material Cu
- A Nb coin coin 7 with an outer diameter of 900 mm and a length of 110 mm is inserted and bonded into the cast raw tube 6 of 13% Sn, and both ends are covered with plugs, and after vacuum degassing, it is sealed by electron beam welding. The single-fiber composite billet 8 prepared by
0 as the pressure medium, extrusion temperature 370oo, technical high output 1
A single-fiber composite wire 9 with an outer diameter of 290 mm was obtained by hydrostatic extrusion at 4000 k9/ground.

The cross section of this extruded material was investigated in the same manner as in Example 1, but oxides,
No foreign matter was observed, and there was no compound layer at the Cu-Sn/Nb interface, indicating an extremely clean interface, indicating that both constituent materials were strongly bonded.

This extruded material was then drawn to a wire diameter of 200 by repeating drawing and intermediate anchoring, but there were no problems such as die competition or wire breakage that were worried about when drawing Nb single wire, and extremely smooth surface processing was achieved. did it.

Comparative Example A composite billet prepared in the same manner as in Example 1 was hot extruded using a hot extruder at a temperature of 75,000 tons and a maximum output pressure of 2,500 tons, and a single-core composite wire with an outer diameter of 500 mm was obtained. 7 or more reaction products were generated at the Cu/Nb-Ti interface of this material, and after that, attempts were made to pull it out to 100, but wire breakage occurred in a narrow size range.

In addition, in order to avoid the formation of reaction products, the exit temperature was 600%.
Attempts were made to extrude the material at a lower temperature of 0.00, but the extrudable size in this case was as much as 80J, and due to the large size and the power of the processing equipment, it was actually possible to carry out subsequent surface processing. still,
The conventional method shown in FIG. 1 gave even more unfavorable results.

As is clear from the above description, the method of the present invention has the following effects. '1} The hot working process of superconducting materials can be omitted, the risk of oxides and foreign material indentation is eliminated, and high quality composite wire rods can be obtained. can be omitted, greatly improving material yield.

Of course, work efficiency will also improve. ■ Since the superconducting material is coated with a stabilizing material during the rough processing of the material, the stabilizing material serves as a protective layer during the subsequent area reduction processing, facilitating quality control during manufacturing.

{3' Compared to conventional processing of a single superconducting material, since the wire is covered with a stabilizing material, there is no seizure with the die during drawing, for example, and smooth wire drawing can be performed.

[4] During isostatic extrusion, the material undergoes extremely large processing at low temperatures at once, so the constituent materials become metallically bonded to each other, and this single-core composite wire is then used to manufacture multi-core composite wire. In this case, the bond is strong, so processing can be carried out very smoothly and stably.

As described above, the present invention provides a new and extremely excellent method for producing a single-core superconducting wire, and has great industrial value.

[Brief explanation of the drawing]

Fig. 1 is a process diagram of the conventional method, Fig. 2 is a process diagram of the method according to the present invention, Fig. 3 is a front sectional view of a composite billet, Fig. 4 is a sectional view taken along line A-A' in Fig. 3, and Fig. 5 is a process diagram of the method according to the present invention. FIG. 3 is a diagram showing a state of hydrostatic extrusion of a composite billet. 1... Steel pipe, 2... Nb-Ti alloy ingot, 3...
...Cu-13%Sn gun tube, 7...
・Nb Zentama. Dimension 3 Dimension 4 Dimension Spear - Zu Zuzu Otsu Zujiru; Figure

Claims (1)

[Claims] 1. A solid billet made of a superconducting material is inserted into a hollow billet made of a stabilizing material prepared in advance, its ends are covered with plugs, and after vacuum degassing, the hollow billet and the plug are welded. In the method of manufacturing a single-fiber composite superconducting wire by hydrostatically extruding the composite billet obtained by sealing and, if necessary, further drawing, the solid billet made of the above-mentioned superconducting material is melted or cast. A method for manufacturing a single-core superconducting wire, characterized in that a forged single-core superconducting wire is used as is. 2. The method for producing a single-core superconducting wire according to claim 1, characterized in that the hollow billet made of a stabilizing material is melted and cast or forged and used as it is. Method.