JPH0817487A - Superconducting wire connecting method - Google Patents

Abstract

PURPOSE:To simply connect together superconducting strands of Nb3Sn with easiness in works, with a high reliance upon the performance, and in a compacted configuration of the connection part. CONSTITUTION:The ends of at least two strands 2 are connected with each other, wherein each strand is formed by twining together a number of superconducting element wires 1 made of Nb3Sn before being subjected to a heat treatment. Therein connecting blocks 6, 7 made of Nb3Sn are fixed to the ends of the strands, put in pressure attachment to the strands in order to eliminate the gap between the strands, followed by a heat treatment, and are connected together by soldering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting wire made of Nb ₃ Sn used for a large-sized and large-current superconducting magnet such as a superconducting magnet used in a nuclear fusion device or a superconducting magnet used as an energy storage device. Regarding connection method.

[0002]

Nb ₃ S used in conventional superconducting magnets
As a method of connecting the superconducting wires made of n, the superconducting wires made of heat-treated Nb ₃ Sn are twisted together by tens or hundreds of wires and the ends of the two twisted wires are butted against each other and pressed. A connection method is adopted in which the portions are electrically heated and fused.

FIG. 6 shows a connection structure of such a conventional superconducting wire. 1 is a superconducting element wire made of Nb ₃ Sn, 2 is a stranded wire in which several tens to several hundreds of the superconducting element wires 1 are twisted,
Reference numeral 3 is a pipe called a conduit for accommodating the twisted wire 2. In addition, 4 is after pressing the connection end of the two twisted wires 2,
A burr 5 is formed on the peripheral portion of the abutting surface of the connecting portion 4 in the connecting portion formed by electric heating.

[0004]

However, such a superconducting wire connecting method has the following problems. That is, the twisted wires handled during the connection work are Nb ₃ Sn after heat treatment.
It is very brittle and easily broken. For this reason, when pressing the ends of the twisted wires, the handling work is very troublesome.
Also, in order to perform pressing and electric heating in a limited space,
Special equipment is required. Further, it is necessary to remove the burrs formed at the time of pressing.

[0005] If such work is captured as a whole,
Even if they are connected under the same connection conditions, it is expected that the fine structures of the connection portions will not necessarily be the same. That is, the reliability of the performance such as the electric resistance and the connection strength of the connection portion is not always sufficient.

According to the present invention, the workability is high, the reliability regarding the performance is high, and the shape of the connecting portion is compact.
It is an object of the present invention to provide a method for connecting superconducting wires, which enables superconducting stranded wires made of b ₃ Sn to be easily connected to each other.

[0007]

In order to achieve the above object, the present invention connects superconducting wires to each other by the following connecting method. The invention corresponding to claim 1 is that at least two bundle-type superconducting wires formed by twisting a plurality of superconducting element wires made of Nb ₃ Sn before heat treatment have N
b ₃ a gap between the mounting and the twisted wire connecting block mating structure consisting Sn heat treatment after crimping the stranded wire and the connecting block so as to eliminate, the superconducting wire after which the connection between blocks by soldering Connect the ends of.

The invention corresponding to claim 2 is the N before heat treatment.
When connecting the ends of at least two bundle-type superconducting wires in which a large number of superconducting wires made of b ₃ Sn are twisted together, the ends of the superconducting wires are crimped to form a fitting part. After heat treatment, the fitting portions are soldered to connect the ends of the superconducting wires.

The invention corresponding to claim 3 is N before heat treatment.
b ₃ Sn, the ends of at least two bundle-type superconducting wires formed by twisting together the superconducting wires are flatly compression-molded, then heat-treated, and then the flat parts are polymerized to solder the joint surface. Attach and connect the ends of the superconducting wires.

[0010]

In the method for connecting superconducting wires according to the present invention, the connecting block having a fitting structure made of Nb ₃ Sn is attached to the ends of the two bundle type superconducting wires before heat treatment. After heat treatment, the superconducting wires are aligned with each other and the joint surfaces are connected by soldering.
The work after the heat treatment is simplified and the workability is improved, and the variations in the electrical resistance of the connection portion and the strength of the connection portion are reduced, and the reliability regarding the performance is improved. Further, since the work before the heat treatment is handled as an alloy, the work of pressing and attaching the connecting block is easy and the workability is improved.

In the superconducting wire connecting method according to the second aspect of the present invention, the ends of the superconducting wires are crimped to form a fitting portion, heat treatment is performed, and then the fitting portion is connected by soldering. By doing so, the same effect as the above can be obtained, and since the connecting block is not used, the electric resistance of the connecting portion can be reduced.

In the superconducting wire connecting method according to the third aspect of the present invention, the end portions of the superconducting wire are compression-molded into a flat shape, the flat portions are superposed, and the joint surfaces thereof are connected by soldering. Therefore, in addition to the above function and effect, the contact area can be increased, and the electric resistance of the connection portion can be reduced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a superconducting wire connection structure according to a first embodiment of the present invention. The same parts as those in FIG. 6 are designated by the same reference numerals.

In FIG. 1, 2 is Nb ₃ Sn before heat treatment.
Two superconducting strands 1 consisting of several tens to several hundreds are twisted together and housed in a conduit 3, and the end portions 2a, 2b of the two stranded wires 2 led out from the conduit 3
The connection blocks 6 and 7 made of unheated Nb ₃ Sn material are attached to the respective parts.

In this case, one connecting block 6 is formed in a cylindrical shape, and the other connecting block 7 is formed in a bottomed cylindrical shape having a projecting portion 7a inserted into the hollow portion of the connecting block 6. ing.

At the end of the twisted wire 2, a connecting block 6,
When inserting 7, the ends 2a, 2b of the twisted wire 2 are narrowed down so that the radial dimension thereof is smaller than that of the twisted wire 2 in the conduit 3 and the wire is inserted in the hollow portion of the connecting blocks 6, 7. Then, attach each by caulking so that no voids remain between the twisted wires.

At this stage, since the stranded wire 2 and the connecting blocks 6 and 7 have not yet been heat-treated, they have the ductility of the metal, and the caulking work does not adversely affect the performance. After attaching the connecting blocks 6 and 7 to the ends of the two twisted wires 2 in this manner, heat treatment is performed, and thereafter, the protruding portion 7a of the connecting block 7 is placed in the hollow portion of the connecting block 6.
Insert and align the blocks to each other, and then solder the joint surface to connect them.

According to such a superconducting wire connecting method,
Before heat-treating Nb ₃ Sn, connect Nb ₃ Sn to the connection end of stranded wire 2.
The connecting blocks 6 and 7 made of material are attached by a method such as caulking so that no voids remain between the twisted wires, and after heat treatment, the protruding portions 7 of the connecting block 7 are placed in the hollow portions of the connecting block 6.
After inserting a and aligning the two twisted wires 2, the joining surface was soldered for connection, so there is a restriction on the connection work due to the brittleness of Nb ₃ Sn after heat treatment. Can also easily connect superconducting wires. Therefore, the connection is improved, and at the same time, the reliability regarding the performance is improved.

FIG. 2 shows a superconducting wire connection structure according to a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and their explanations are omitted. Describe.

In the second embodiment, as shown in FIG. 2, one end 2a of one stranded wire 2 is formed in a conical shape, and the other end 2b of the other stranded wire 2 is formed in a conical recess. , Stranded wire 2
One end 2 of one stranded wire 2 is used as a pair of connecting blocks 8 made of Nb ₃ Sn material attached to the ends 2a, 2b of the
Each of the end portions 2a of the twisted wire 2 is formed into a shape having a concave portion into which the conical convex portion formed in a is inserted and a convex portion to be inserted into the concave portion of the end portion 2b of the other twisted wire 2. The convex portion of the other connecting block 8 is inserted into the concave portion of the connecting block 8 in the concave portion of the end portion 2b of the stranded wire 2 and attached by caulking. It is similar to the first embodiment.

In such a superconducting wire connecting method, the same operation and effect as in the first embodiment can be obtained, and the contact area between the twisted wire 2 and the connecting block 8 can be increased, so that the connection can be improved. The electrical resistance of the portion 4 can be reduced and the outer diameter dimension can be reduced.

FIG. 3 shows a superconducting wire connection structure according to a third embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Describe.

In the third embodiment, as shown in FIG. 3, the connecting end portions 2a and 2b of the two twisted wires 2 are pressed to form a circular hole in one connecting end portion 2a and the other connecting end portion 2a is pressed. The connection end portion 2b is formed with a columnar protruding portion to be inserted into a circular hole so as to have a function as a connection block, and the connection work after the heat treatment is the same as that of the first embodiment.

In such a superconducting wire connecting method, the same effect as that of the first embodiment can be obtained, and since the connecting block is not used, the electric resistance in the connecting portion 4 can be reduced. it can.

FIG. 4 shows a superconducting wire connection structure according to a fourth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Describe.

In the fourth embodiment, as shown in FIG. 4, the connecting ends 2a and 2b of the two twisted wires 2 are pressed to form a conical projection on one of the connecting ends 2a. A conical concave portion into which this convex portion is inserted is formed in the other connecting end portion 2b to have a function as a connecting block, and the connecting work after the heat treatment is the same as that of the first embodiment. is there.

Even in such a superconducting wire connecting method, the same effects as those of the first embodiment can be obtained, and since no connecting block is used, the electrical resistance at the connecting portion 4 can be reduced to zero. it can.

FIG. 5 shows a superconducting wire connection structure according to a fifth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Describe.

In the fifth embodiment, as shown in FIG. 5, the connecting ends 2a, 2b of the two twisted wires 2 are pressed to form a flat shape, and after the heat treatment, these connecting ends 2a, 2b are pressed. 2b
The flat parts of the above are polymerized and connected by soldering.

Even in such a superconducting wire connecting method, the same effect as that of the first embodiment can be obtained, and since the contact area of the connecting portion 4 can be increased, the electric resistance can be reduced. At the same time, since the dimension in one direction can be reduced, it is effective in the case where the connection portion 4 has to be accommodated in a flat space even if the shape becomes slightly large.

[0031]

As described above, according to the present invention, the workability is high, the reliability regarding the performance is high, the shape of the connecting portion is compact, and the superconducting stranded wires made of Nb ₃ Sn are easily connected to each other. It is possible to provide a superconducting wire connection method that can be performed.

[Brief description of drawings]

FIG. 1 is a structural diagram of a connecting portion showing a first embodiment for explaining a method of connecting a superconducting wire according to the present invention.

FIG. 2 is a structural diagram of a connecting portion of a superconducting wire showing a second embodiment of the present invention.

FIG. 3 is a structural diagram of a connecting portion of a superconducting wire showing a third embodiment of the present invention.

FIG. 4 is a structural diagram of a connecting portion of a superconducting wire showing a fourth embodiment of the present invention.

FIG. 5 is a structural diagram of a connecting portion of a superconducting wire showing a fifth embodiment of the present invention.

FIG. 6 is a structural diagram of a connecting portion for explaining a conventional superconducting wire connecting method.

[Explanation of symbols]

1 ... Nb ₃ Sn superconducting element wire, 2 ... Stranded wire, 3 ... Conduit, 4 ... Connection part, 6, 7, 8 ... Connection block.

Claims (3)

[Claims] 1. A connection block having a fitting structure made of Nb ₃ Sn is attached to an end of at least two bundle type superconducting wires formed by twisting a plurality of superconducting element wires made of Nb ₃ Sn before heat treatment. In order to eliminate the voids between the twisted wires, the twisted wires and the connecting blocks are crimped and then heat treated, and then the connecting blocks are soldered together to connect the ends of the superconducting wires. How to connect. 2. A bundle-type superconducting wire obtained by twisting a plurality of Nb ₃ Sn superconducting wires before heat treatment is crimped to form a fitting portion, heat-treated, and then the fitting portion is formed. A method of connecting superconducting wires, characterized in that the ends of the superconducting wires are connected by soldering. 3. An end portion of a bundle type superconducting wire obtained by twisting a plurality of Nb ₃ Sn superconducting element wires before heat treatment is compression-molded into a flat shape, then heat-treated, and then the flat portion is polymerized to form A method for connecting superconducting wires, characterized in that ends of the superconducting wires are connected to each other by soldering joint surfaces.