JPH01321032A - Manufacture of multi-core superconducting wire - Google Patents

Abstract

PURPOSE:To improve current density and to better workability by arranging polygonal element wires so that the geometrical center of gravity of the cross section of an element wire is positioned concentrically and each cross section takes the same direction to the center of the concentric circle and inserting them into a metallic pipe. CONSTITUTION:The diameter of the element wire is reduced to manufacture a rectangular wire and this rectangular wire is cut to a prescribed length to obtain an element wire. The element wires 32 are inserted into a silver pipe 42 while arranged concentrically around a silver bar 6C and reduced in diameter to obtain a round wire. In this way, since polygonal element wires are arranged isotropically to the concentric circles, this round wire is free from unshaped void and shaped voids are berried by element wires of different shapes arranged concentrically and the space factor of superconductors in the complex can be intensified. Further, since, in a compression time, an equal working strain is given on a concentrical circle, accidents such as disconnection are reduced and working yield and productivity are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in a method for manufacturing a multicore superconducting wire using a composite processing method.

[Conventional technology]

The manufacturing method of multi-core superconducting wire using the conventional composite processing method is as follows:
First, as shown in FIG. 3(d), a large number of superconductors (1) such as NbTi are formed in a base material (2) of Cu or Cu alloy.
As shown in FIG. 4, the hexagonal wires (34) dispersed and embedded in the metal tube (41) are inserted into hexagonal metal rods (6a).
densely arranged around. Alternatively, as shown in FIG. 5, a round metal rod (6b) is placed in the center of the metal tube (41), and hexagonal wires (34) are arranged closely around it. ) and a metal tube (41) is extruded and reduced in diameter by drawing, wire drawing, rolling, etc., and processed into a composite multifilamentary superconducting wire of a desired shape.

[Problem to be solved by the invention]

However, the above manufacturing method has the following problems. That is, a) As shown in Figures 4 and 5, metal tubes (41
) and a group of hexagonal wires (34) inserted and arranged in the metal tube,
Alternatively, irregularly shaped voids (51) and (52) are generated between the inserted and arranged hexagonal wires (34) and the round metal rod (6b), and the superconductor in the composite wire obtained due to these voids. There is a limit to the space factor.

During diameter reduction processing, the thickness of the metal tube that forms the outer skin of the composite becomes uneven, and the processing rate of the wire that is the base material wrapped in the outer skin also becomes uneven, resulting in a decrease in processing yield. , productivity does not increase.

The present invention has been made in view of the above points.
The aim is to improve the shape and arrangement of the superconducting wires in the metal tube to increase the density of the superconducting wire, and to provide a method for manufacturing multicore superconducting wires with high critical current density with good workability. be.

[Means for Solving the Problems and Their Effects] That is, the method of the present invention is a method of manufacturing a multicore superconducting wire by inserting a plurality of strands containing a superconductor into a metal tube and subjecting the metal tube to compression processing. , polygonal wires are arranged and inserted into a metal tube so that the geometric centers of gravity of the cross sections of the wires are located in concentric circles, and the cross sections are oriented in the same direction with respect to the center of the concentric circles. It is characterized by:

In the manufacturing method of the present invention, polygonal wires are arranged isotropically with respect to concentric circles, so there are no irregularly shaped voids, and regular voids are replaced by wires of different shapes arranged concentrically. This can increase the space factor of the superconductor in the composite. Furthermore, during compression processing, uniform processing strain is applied on the concentric circles, which reduces accidents such as wire breakage and improves processing yield and productivity.

〔Example〕

The present invention will be described below based on embodiments shown in the drawings.

Example 1 A hole with an inner diameter of 18M was made in a silver rod with an outer diameter of 25III11, and an oxide superconductor raw material powder containing Y:B'a:Cu=1:2:3 was filled in the hole, and this Cut the wire into a length of 50cm and reduce the diameter of the wire to 2.5mm.
It was made into a square wire of m x 2.5 m. Draw this square line about 5
The wire was cut into a length of 0 m, and as shown in Figure 1, it was cut into a silver tube (42
) were inserted and arranged concentrically around a silver rod (6C) with a diameter of 13 m5, and this was subjected to diameter reduction processing to obtain a round wire with an outer diameter of 0.5 mm. For comparison, the cross-sectional area of the wire is 2. of the above example.
A hexagonal wire, which is the same as the square wire of 5 ym
, a silver rod with a diameter of 13 cm (6
b), and densely arrange this hexagonal wire around it,
The void was filled with a silver rod having a diameter of 1ffi11, and the diameter of the rod was reduced to obtain a round wire with an outer diameter of 0.5-. The multicore superconducting wires of the above Examples and Comparative Examples were each taken in lengths of 150 cm, heated in an oxygen atmosphere at 850° C. for 15 hours, and then cooled to room temperature to prepare measurement samples. Current terminals on these samples,
A voltage terminal was attached, and the critical current and critical current density were measured in liquid nitrogen. The results are shown in Table 1.

Note that the external magnetic field during the measurement was zero.

From the results shown in Table 1, the critical current density of the superconductor is almost the same in this example and the comparative example, but the current density of the entire superconducting wire is superior in this example.

The reason for this is thought to be that the superconductor was uniformly processed and the fiber density of the superconducting wire was higher in this example.

Example 2 FIG. 2 is a cross-sectional view showing the arrangement of superconducting strands in a metal tube in this example. That is, the outer diameter is 36Ii
II, Fig. 3 (
Centering on one hexagonal element wire (35) with the opposite side of 8m shown in e), the opposite side 6III1 shown in Fig. 3(d) is placed on the outside.
Eight hexagonal strands (34) of No. 1 are arranged, and further outside the hexagonal strands (34) of 8 are the triangular strands (33) of six opposite sides shown in Fig. 3 (C).
book and the square element tIA (3
2) Place 8 pieces. Furthermore, on the outside of this metal tube (43), there are 28 square wires (32) with opposite sides of 4 cm, as shown in Fig. 3(a).
), 24 triangular wires (31) each 6 mm on a side, and 24 inverted triangular wires (31) with 6 mm on each side are arranged at the outermost side, and are stored in a steel pipe (44) with an outer diameter of 62 mm and an inner diameter of 59 mm. did. These polygonal wires are composed of a plurality of NbTi filament superconductors (1) with a diameter of about 120 PM embedded in a copper base material (2), as shown in Figures 3(a) to (e). be. On the other hand, as a comparative example, as shown in FIG.
21111. Fifty-five hexagonal wires (34) each having an opposite side of 6 circles were placed in a copper tube (41) with an inner diameter of 59 m+*, and the void (51) was filled with copper wires with a diameter of 1+ m. These outer diameters are 62ffI
After processing the 11 metal tubes with a swager to an outer diameter of 50 mm,
After drawing and making the outer diameter 0.5, it was heated at 350°C12
Heat treatment was performed for 4 hours, and then the outer diameter of the porcelain was 0.3. The workability and superconducting properties of these wires were as shown in Table 2.

From the above results, in this example, there was almost no wire breakage during wire drawing and almost no wire breakage of the NbTi filament.
It can be seen that the diameter variation of the i-filament is also extremely small, indicating good workability. Further, in this example, since the number of combined NbTi filaments is larger, the Jc of the superconducting wire is higher, and the J of the NbTi filament itself is also higher.

〔Effect of the invention〕

As explained above, according to the present invention, polygonal superconducting strands are arranged so that the geometric centers of gravity of their cross sections are located in concentric circles, and the cross sections are oriented in the same direction with respect to the center of the concentric circles. Since they are arranged in a metal tube and subjected to compression processing, they have the excellent effect of improving current density and workability.

A cross-sectional view of an example of the initial processing state of a superconducting wire in
Figure 2 is a cross-sectional view of another embodiment, Figures 3(a) to (e) are cross-sectional views of a polygonal superconducting wire, and Figures 4 and 5 are of a conventional example of the initial state of superconducting wire processing. FIG.

■...Superconductor, 2...Base material, 6a, 6b, 6
C... Rod, 31... Triangular wire, 32F... Square wire, 33... Triangular wire, 34... Hexagonal wire,
35...Hexagonal wire, 41,42,43.44...
・Pipe, 51°52... air gap.

Claims (1)

[Claims] In a method of manufacturing a multicore superconducting wire by inserting a plurality of strands containing a superconductor into a metal tube and subjecting the metal tube to compression processing, polygonal strands are 1. A method for producing a multicore superconducting wire, which comprises arranging and inserting the superconducting wire into a metal tube so that the centers of gravity of the wires are located in concentric circles and the cross sections are oriented in the same direction with respect to the center of the concentric circles.