JPH05325666A - Complex multi-conductor superconductive wire - Google Patents

Abstract

PURPOSE:To provide a complex multi-conductor superconductive wire which is excellent in processability and superconductivity. CONSTITUTION:In a complex multi-conductor superconductive wire obtained in such a way that a multi-conductor superconductive wire rod 5 is molded/ processed into a hexagonal cross sectional shape to form a hexagonal element wire 1, and this hexagonal element wire 1 is filled densely in a Cu or Cu alloy pipe 6 to form a complex billet, and a drawing processing is carried out on this complex billet, a material being molded/processed into the hexagonal cross sectional shape after a twist processing is carried out on the multi-conductor superconductive wire rod 5, is used as the hexagonal element wire 1. Thereby, since an abnormally deformed length of a superconductive material filament 3 can be reduced when being molded/processed into a hexagonal shape, the complex multi-conductor superconductive wire which is excellent in processability and superconductivity, can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite multifilamentary superconducting wire having excellent workability and superconducting properties.

[0002]

2. Description of the Related Art In recent years, superconducting wires of Nb--Ti alloys and Nb ₃ Sn compounds have been put to practical use in magnetic levitation trains, high energy particle accelerators, nuclear magnetic resonance imaging devices for medical diagnosis and the like. Superconducting wire is intended in a Cu or Cu alloy matrix of Nb-Ti and Nb ₃ superconducting filaments of Sn or the like many be incorporated present embedded structure, the manufacture of such superconducting wire, for example, Nb in the Cu tube -Ti-based superconducting alloy material is filled and drawn to form a single-core superconducting wire, and a large number of this single-core superconducting wire is again filled in a Cu pipe to form a composite billet. The stretching process is repeated a desired number of times. By the way, in order to increase the packing density of the superconducting wire in the composite billet, as shown in FIG. 4, a superconducting wire 5 having a circular cross section in which a large number of superconducting material filaments 3 are embedded in a Cu or Cu alloy matrix 2 ( (A) was formed into a hexagonal cross section to form a hexagonal wire 11 (figure b), and the hexagonal wire 11 was assembled by a method of densely filling the tube 6 made of Cu or Cu alloy (figure B). C).

[0003]

However, as described above, in the case where the superconducting wire is a multi-core superconducting wire in which a large number of filaments of the superconducting material are combined, if this is directly processed into a hexagonal cross section, it is possible to obtain the structure shown in FIG. As you can see,
The superconducting filament 3 located at the corner 4 of the hexagonal wire 11 has an elongated cross-section that is abnormally deformed toward the corner 4, and this abnormally deformed portion appears over the entire length of the corner 4 of the hexagonal wire 11. The composite billet produced by using the hexagonal element wire 11 is likely to be broken during processing in the case of Nb-Ti superconducting wire, and the superconducting material filament in the bronze in case of manufacturing the Nb ₃ Sn superconducting wire by the bronze method. That is N
Since the b filaments have a non-uniform spacing, the Sn supplied to the Nb filaments may be excessive or deficient depending on the location, and the resulting composite multifilamentary superconducting wire may have Sn remaining in the matox or a Nb ₃ Sn compound. There is a problem that the reaction becomes insufficient and high superconducting properties cannot be obtained.

[0004]

The present invention has been made as a result of intensive studies in view of such a situation, and an object thereof is to provide a composite multicore superconducting wire excellent in workability and superconducting properties. To provide. That is, the present invention, a multi-core superconducting wire rod is formed into a hexagonal cross section to form a hexagonal element wire, the hexagonal element wire is densely packed in a metal tube to form a composite billet, and this composite billet is drawn. In the composite multifilamentary superconducting wire obtained by subjecting the multifilamentary superconducting wire, the hexagonal wire is formed by twisting a multifilamentary superconducting wire and then forming it into a hexagonal cross section.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional explanatory view showing an example of a hexagonal element wire used for manufacturing the composite multicore superconducting wire of the present invention. Reference numeral 1 is a hexagonal element wire, in which 19 superconducting material filaments 3 are embedded in a Cu or Cu alloy matrix 2. Twelve superconducting material filaments 3 on the outer periphery face the corner portion 4 of the hexagonal wire 1 one after another, but the length of the superconducting material filament 3 located at the corner portion 4 is short, and therefore the superconducting material filament 3 The abnormal deformation length that occurs at the corners of is reduced in total. FIG. 2 is an explanatory view showing another example of the hexagonal element wire used in the production of the composite multicore superconducting wire of the present invention.
This hexagonal wire has 31 superconducting material filaments 3 embedded in the Cu matrix 2, and the abnormal deformation length of the superconducting material filaments is reduced similarly to that shown in FIG.

The hexagonal wire as described above is manufactured, for example, according to the process shown in FIG. That is, 19 superconducting material filaments 3 are embedded in a Cu matrix 2, and each superconducting material filament 3 is embedded at the apex of an equilateral triangle so as to form a regular hexagon. (Fig. A) is twisted (Fig. B) and then processed into a hexagonal cross section to form a hexagonal element wire 1 (Fig. C). In the composite multicore superconducting wire of the present invention, the twist pitch of the multicore superconducting wire is not particularly limited, but if the pitch is too long, its abnormal deformation preventing effect is not sufficiently expressed,
If it is too short, the superconducting filament will be damaged. Therefore, the range of 5 to 30 times the wire diameter of the multifilamentary superconducting wire is preferable. Further the composite multifilamentary superconducting wire of the present invention, other superconducting wire, such as Nb-Ti alloy and Nb ₃ Sn compound oxide superconducting wire or the like is applied.

[0007]

In the composite multicore superconducting wire of the present invention, since the hexagonal wire used for assembling the composite billet is twisted with the multicore superconducting wire, the hexagonal wire formed into a hexagonal cross section is used. cross-sectional shape of the superconducting material filaments in hexagonal wire is good and therefore Nb-Ti in the superconducting wire has an improved its processability, and Nb ₃ Sn in the superconducting wire Sn and Nb filaments in the bronze And the superconducting characteristics are improved.

[0008]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 A 6 mmφ multifilamentary superconducting wire in which 19 Nb-Ti filaments were embedded in a Cu matrix was twisted at a pitch of 60 mm, and this was groove-rolled to obtain a structure with a distance between opposite sides of 4.9. It was formed into a hexagonal element wire of mm. Next, use this hexagonal wire with an outer diameter of 200 mmφ, an inner diameter of 170 mmφ, and a length of 500
A Cu bill tube of 1000 mm was densely packed, and after degassing, Cu lids were electron beam welded to both ends of the Cu tube to prepare a composite billet. Next, this composite billet is hot extruded,
Next, this hot extruded material was swaged and drawn to form a wire having a wire diameter of 1 mmφ, and heat-treated to produce a Nb-Ti-based composite multicore superconducting wire.

Comparative Example 1 In Example 1, the same procedure as in Example 1 was repeated except that the multifilamentary superconducting wire rod was groove-rolled into a hexagonal element wire without being twisted. A core superconducting wire was manufactured. With respect to each of the composite multifilamentary superconducting wires thus obtained, the state of disconnection during the drawing process was examined. The results are shown in Table 1.

[0010]

[Table 1]

As is clear from Table 1, the products of the present invention (No.
In 1), the wire was not broken even during wire drawing and showed good workability. Incidentally, the superconducting property was sufficiently satisfied with the standard value. On the other hand, in the comparative example product (No. 2), the breakage occurred frequently because the superconducting material filament of the hexagonal wire used was abnormally deformed.

Example 2 A 2.5 mmφ multifilamentary superconducting wire in which 31 Nb filaments were embedded in a Cu-Sn alloy (bronze) matrix.
After twisting at a pitch of 30 mm, this was groove-rolled and formed into a hexagonal wire having a structure shown in FIG. Next, 1300 hexagonal wires with a thickness of 1 mm
The Nb tube is inscribed in an outer diameter of 107 mmφ, inner diameter of 79 mmφ, and length of 200 mm, and is closely packed in a Cu tube. After degassing, Cu lids are electron beam welded to both ends of the Cu tube to form a composite billet. I said. Next, this composite billet was hot extruded, and then this hot extruded material was swaged and drawn to obtain a wire rod having a diameter of 1.5 mm. Finally, this wire was subjected to a predetermined heat treatment to produce a Nb ₃ Sn-based composite multicore superconducting wire.

Comparative Example 2 A Nb ₃ Sn-based composite of 1.5 mmφ was prepared in the same manner as in Example 2 except that the multifilamentary superconducting wire rod was groove-rolled into a hexagonal wire without twisting in Example 2. A multifilamentary superconducting wire was manufactured. The critical current value of each composite multicore superconducting wire thus obtained was measured in liquid He (4.2 K) under a magnetic field of 12 T (Tessler). The results are shown in Table 1.

[0014]

[Table 2]

As is clear from Table 1, the products of the present invention (No.
In 3), the critical current value was high. During the wire drawing process, there was no breakage. On the other hand, in the comparative example product (No. 4), the Nb filament of the hexagonal wire used was abnormally deformed, so that Nb ₃ Sn was not sufficiently generated by reaction,
Further, Sn remained in the matrix, and the critical current value was low.

[0016]

As described above, since the composite multifilamentary superconducting wire of the present invention has a good shape of the superconducting material filament, it is excellent in workability and superconducting properties and has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an example of a hexagonal element wire used to manufacture a composite multicore superconducting wire of the present invention.

FIG. 2 is a cross-sectional explanatory view showing another embodiment of the hexagonal element wire used for manufacturing the composite multicore superconducting wire of the present invention.

FIG. 3 is a process explanatory view illustrating the method for producing a hexagonal element wire used in the production of the composite multicore superconducting wire of the present invention.

FIG. 4 is an explanatory view showing a method of assembling a composite billet used for manufacturing a conventional composite multicore superconducting wire.

[Explanation of symbols]

 1,11 Hexagonal wire 2 Cu or Cu alloy matrix 3 Superconducting material filament 4 Hexagonal wire corner 5 Multi-core superconducting wire 6 Cu or Cu alloy tube

Claims (1)

[Claims] 1. A multifilamentary superconducting wire rod is formed into a hexagonal cross section to form a hexagonal element wire. The hexagonal element wire is densely packed in a metal tube to form a composite billet, and the composite billet is stretched. In the composite multicore superconducting wire obtained as described above, the hexagonal element wire is formed by twisting a multicore superconducting wire and then forming it into a hexagonal cross section.