JP3333295B2 - Bonding method of stranded superconducting conductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining a plurality of superconducting strands of one superconducting conductor and the other superconducting conductor, which are connected together.

[0002]

2. Description of the Related Art For example, a method for joining a stranded superconducting conductor used for a pulse magnet or a superconducting generator for the purpose of AC excitation is to peel off an insulator coated on the conductor and directly solder the conductors to each other. In this method, the connection is made by soldering, or the superconducting strands are twisted and twisted together and soldered.

[0003] However, this joining method not only requires much labor and time, but also increases the connection length. Therefore,
Recently, an ultrasonic bonding method has been adopted in which the contact portions of the stranded superconducting conductors are directly vibrated by ultrasonic waves, and the contact portions are melted and connected by frictional heat generated by the vibration.

[0004]

In superconducting conductors used in alternating current, element wires are insulated so that no coupling current flows between the conductors. Therefore, when ultrasonic bonding is performed, the connecting portions of the superconducting wires are in point contact, and the area of the connecting portion is reduced, so that the connection resistance of this portion is increased, causing heat generation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for joining a stranded superconducting conductor which can increase the area of a connection portion by ultrasonic joining of a superconducting conductor used in alternating current and reduce the connection resistance. .

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of joining the connection ends of a pair of superconducting conductors in which a plurality of superconducting wires are twisted. A copper foil of the same length as the connection length is wrapped around the connection end, overlaps the connection end of the other superconducting conductor, and the superimposed portion is vibrated by ultrasonic waves generated by an ultrasonic generator to generate frictional heat. Thus, the copper foil is melted to connect the connection end portions of the superconducting conductor.

[0007]

In such a method of joining a stranded superconducting conductor, the contact between the copper foil and the superconducting wire is melted by frictional heat due to ultrasonic vibration, and the copper melted in the gap between the superconducting wires. Since the foil flows, the area of the connection portion is increased, and the connection resistance at this portion can be reduced.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a structural example for explaining a method for joining a stranded superconducting conductor according to the present invention.

In FIG. 1, 1 and 3 are superconducting conductors formed by twisting superconducting wires 2. When connecting the connection ends of such superconducting conductors 1 and 2, the insulator at the connection end of one superconducting conductor 1 is first peeled off, and a copper foil 4 is wound around this portion. Further, the copper foil is not wound around the connection end of the other superconducting conductor 3 but is superposed on the copper foil 4 wound around the connection end of the one superconducting conductor 1. In this case, the connection ends of the superconducting conductors 1 and 3 are not twisted at all.

Further, these superconducting conductors 1, 1
The diaphragm 5 is provided so as to be in contact with the end of the diaphragm 3 therebetween. An ultrasonic generator (not shown) is connected to the diaphragm 5,
The ultrasonic vibration is transmitted to the connection portion through the diaphragm 5.

Next, when an ultrasonic device (not shown) is operated in such a state, the vibration plate 5 is vibrated by the ultrasonic waves, and this vibration is transmitted to the above-described connection end. Then, the contact between the copper foil 4 and the superconducting wires 2 is melted by frictional heat due to the ultrasonic vibration, and the superconducting wires 2 and the copper foil 4 are separated from each other as shown in FIG.
And the molten copper foil flows into the gaps 6 between the superconducting wires.

Accordingly, the area of the connection portion 8 between the superconducting wires 2 is increased, and the connection resistance at this portion is reduced. On the other hand, when the copper foil is not used, the contact portions of the superconducting wires 2 are melted and connected as shown in FIG. 3, so that the area of the connection portion 9 is small.

As described above, in the above embodiment, the copper foil 4 is wound around the connection end of one superconducting conductor 1 with the same length as the connection length, and is superimposed on the connection end of the other superconducting conductor 3. Ultrasonic vibration through the vibration plate 5 connected to the ultrasonic generator causes the contact portion between the copper foil 4 and the superconducting wires to melt by frictional heat and flows into the gaps between the superconducting wires. The contact portion is wider than in the case of ultrasonic bonding without wire connection, so that a connection portion of the AC stranded superconducting conductor having a low connection resistance can be obtained.

[0014]

As described above, according to the present invention, the joining of the stranded superconducting conductor which can reduce the connection resistance by increasing the area of the joining portion of the ultrasonic joining of the superconducting conductor used in the alternating current. Can provide a method.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment for explaining a method for joining a stranded superconducting conductor according to the present invention.

FIG. 2 is a sectional view showing a part of a connection end in the embodiment.

FIG. 3 is a cross-sectional view showing a part of a connection end of a stranded superconducting conductor connected without using a copper foil.

[Explanation of symbols]

1, 3 ... superconducting conductor, 2 ... superconducting wire, 4 ... copper foil, 5 ... vibrating plate, 6 ... gap, 7 ... connecting part.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01R 43/00 H01B 12/02 H01R 4/68 H01R 43/02

Claims (1)

(57) [Claims] 1. A method of joining connection ends of a pair of superconducting conductors in which a plurality of superconducting wires are twisted,
A copper foil of the same length as the connection length is wrapped around the connection end of one superconducting conductor and overlapped with the connection end of the other superconducting conductor, and this superimposed portion is vibrated by the ultrasonic waves generated by the ultrasonic generator. And joining the connection ends of the superconducting conductors by melting the copper foil by the frictional heat.