JPS63276886A - Connecting method for superconductive wire - Google Patents

Abstract

PURPOSE:To make a superconductive wire connectible at zero resistance by projecting a filament of a superconductor from a stabilizing material, butting both projected joining surfaces to each other, while clamping these joining surfaces in the radial direction with a split jig, and pressurizing and heating them. CONSTITUTION:The end of a superconductive wire 3 consisting of a superconductor filament 1 and a stabilizing material 2 is cut diagonally, forming a scarf joint surface 12 making the connecting surface larger. Next, the scarf joint surface 12 is degreased with a solution of alcohol or the like, and further it is etched by a solution of nitric acid or the like, than the superconductor filament 1 is projected out. The superconductive wire 3 provided with the scarf joint surface 12 like this is superposed and fixed by a collet chuck-form pressure jig 14 and clamping jigs 25 and 16 being tripartile in the same direction. Then, clamping and pressurizing are carried out with these jigs, and successively it is heated by a cartridge heater 18.

Description

[Detailed Description of the Invention] (Objective of the Invention) (Industrial Application Field) The present invention relates to a method for connecting superconducting wires, and in particular, to connecting superconducting wires made of superconducting filaments and stabilizing materials without causing characteristic deterioration. The present invention relates to a connection method suitable for

(Prior art) As a connection technology for superconducting wires, Japanese Patent Application Laid-Open No. 57-154385
As described in the above publication, there is a method for connecting superconducting wires made of ultrafine multifilamentary Nb T+ alloy wires. The principle diagram is shown in FIG. 11 and FIG. 12.

According to this method, as shown in Figure 11, the two joints to be connected are formed in a diagonal shape, overlapped, inserted into a copper vibrator, and pressed vertically using a jig. Pressure is applied only in one direction, downward, and the copper vibrator (27) is compressed into a flat shape.
It is difficult to apply uniform pressure to the cut surface (25) shown in the figure, that is, the joint surface. This tendency is particularly likely to occur at the ends of the joint surfaces.

As a result, looking at the electrical characteristics of the superconducting wire, the current -
The voltage characteristics will have a certain value of resistance, as shown in curve a shown in Figure 13, and will be significantly different from the zero resistance curve that is characteristic of original superconducting wires, and will no longer exhibit superconducting characteristics. There is a problem.

(Problems to be Solved by the Invention) In this conventional method, the resistance of the connection part does not become zero, and this is not preferable as a connection part of superconducting wires.

An object of the present invention is to provide a method for connecting superconducting wires that makes it possible to connect superconducting wires made of superconducting filaments and stabilizing materials with zero resistance.

(Structure of the Invention) (Means for Solving the Problems) In order to achieve the above object, in the present invention, both connecting portions of a superconducting wire composed of a superconducting wire filament and a stabilizing material are connected. The first step is to process the diagonal-shaped spliced surfaces to increase the connection area, remove the stabilizing material on both processed surfaces to make the superconducting filament protrude, and overlap the two spliced surfaces. It is housed in a one-knot l-jack-shaped pressure jig divided into three or more parts in the circumferential direction of the cylinder,
A method for connecting superconducting wires is provided, characterized in that the double tightening that opens on the tapered surface includes a jig, and the second step of applying pressure to the radial side tightening and heating with a heater is provided.

(Function) With this structure, the protruding superconducting filaments are first pressed together, and then the stabilizing material is pressed, so that the superconducting filaments are reliably connected.

Pressure was applied in the radial direction using a collet chuck-like press jig, and the stabilizing material was elongated to ensure a secure connection.

(Examples) Example 1 Hereinafter, a first example of the method for connecting superconducting wires according to the present invention will be described with reference to FIGS. 1 to 6.

The ends of the superconducting filament ■ and the stabilizing material ■ and the superconducting wire ■ are processed diagonally to form a scarf joint shape to form a spliced surface ■ with a larger connecting surface. When connecting the stiffness, first, as shown in Figure 3 @ and υ,
To form a spliced surface 0, use an emery vapor or a file to cut the spliced surface of both wires at 1/1 of the twist pitch where the superconducting filament ■ is twisted.
Process it to length H of 2 or less. The final finishing process using emery vapor or a file is done with a fine emery vapor grain of about 1000.

Next, the spliced surface (2) is degreased with a solution such as alcohol, and then etched for several seconds with a solution such as nitric acid to cause the superconductor filament (2) to protrude. Figure 3 (2).

The superconducting wires are shown enlarged in υ, so the amount of protrusion is large, but the actual amount of protrusion is small and can be connected to the stabilizing material by rolling.

Next, the two superconducting wires (■) are placed one on top of the other as shown in Figure 4, and the pressure jig (B) shown in Figures 5 and 6 is used to tighten the jigs O1 and Of! Fix it to l.

A collet chuck-shaped pressure jig (b) divided into three parts in the same direction and a tightening jig () combined with a taper O$
A superconducting wire fixed at 60 mm is inserted into the chamber (7) of the connecting device shown in FIG.

The superconducting wire (2) inserted into the chamber @ is held by a fixture (to) equipped with a cartridge heater (to). (
19a) is a leg plate that supports the fixing jig. Three cartridge heaters are arranged on each of the upper and lower sides to heat the superconducting wire (2) from the upper and lower sides. On the other hand, the pressure cylinder So is arranged to push the tightening jig C◇ in the axial direction, generate a force component in the radial direction on the tapered surface, and apply radial pressure to the superconducting wire ■.

Inside the chamber @, the connection part is heated to a temperature of about 400℃ to 500℃, so the structure is such that the atmosphere is maintained at 1 x 1O-3 Torr or less using an exhaust system ■ to prevent the seamed surface ■ from oxidizing. ing. In addition, the chamber (b)
In addition to keeping the interior in a vacuum state, we also installed an inert gas supply device (
21a) is also provided.

When connecting superconducting wires (2) having a cross-sectional diameter of approximately 2Φ using a connecting device such as that shown in FIGS. 5, 6, and 1, it is carried out, for example, as follows.

As mentioned above, the superconducting wires (2) with the spliced surface (2) formed thereon are superimposed and fixed using a pressing jig (b) and tightening jigs CΦ, 0Φ.

After fixing, use a pressure jig (b) and tighten with jig 09,01S.
Tighten and pressurize the spliced surface 0 of the superconducting wire (2) in the radial direction using the Next, use the cartridge heater (to) to
Heat at a temperature of 0°C to 500°C for about 10-30 minutes.

FIG. 21 schematically shows the appearance after in-phase connection of the superconducting wires (3) under such connection conditions.

That is, when connecting two superconducting wires, the cross-sectional area of the part to be connected by processing the end face of the superconducting wire ■° into the shape shown in Figure 3 (c), υ is:
For example, if the machining allowance H for the end face is 15M and the radius of the superconducting wire including the stabilizing material is r, then the formula for calculating the cross-sectional area (πX
rX15IIm>, it becomes 7.5 times the cross-sectional area. Considering that the superconducting filament ω has an extremely thin cross-sectional diameter of several micrometers, and is multi-core with hundreds of filaments, it is possible to increase the reliability of the connection by increasing the facing area of the connection. It is obvious that this will happen.

By the way, it is necessary to limit the length of the processed part of the end face to 1/2 length of the twist processing pitch or less;
If the length exceeds /2, one superconducting filament■
This is because the number of wire connections increases to several locations, which increases the electrical connection resistance and impairs the properties of the superconducting wire. Then, since the superconductor filament ω protrudes from the stabilizing material ■, it is securely connected, and the stabilizing material ■
As shown in Figure 2, although it is a little messy, this is also an in-phase connection, which is a major factor in further increasing reliability.2 Figure 7 shows the connection in the connection device shown in Figure 1. It shows a characteristic diagram of the relationship between temperature and allowable current. As shown in the figure, the lower the connection temperature, the greater the allowable current flow. Then, the resistance value approaches zero as shown by the curve shown in FIG.

Therefore, in order to create good connection conditions, it is necessary to reliably control the connection temperature within the range of 400°C to 500°C.

As described above, according to the first embodiment, since the joint surfaces are tightened and pressurized in the radial direction, uniform pressure is applied to the joint surfaces, and a sound joint surface without variations can be obtained.

In addition, by obtaining a sound joint surface, it is possible to prevent the mechanical or electrical properties of the base material from being damaged, which is effective in streamlining work and improving product quality.

Example 2 Next, regarding the second example of the present invention, FIGS.
This will be explained with reference to the figures.

In this Example 2, as shown in Fig. 8, a spacer made of copper or copper alloy, which is a material of the same type as the stabilizing material ■, is placed above, below, or around the part where the superconducting wires overlap each other.
Add. For this spacer, a thin plate or a half pipe corresponding to the shape of the superconducting wire (2) is used. The thickness of the thin plate or half pipe is approximately 10 to 20% of the superconducting wire diameter.
It is desirable that the thickness be approximately the same.

In this way, by connecting the superconducting wires with the connecting device shown in Figure 1 with the spacer @ added, the external shape after connection is schematically shown in Figure 9, which has a uniform diameter. Become.

In addition, the length of the spacer @ shown in Fig. 8 and the superconducting wire ■
Regarding the relationship between the length H of the connecting portion and the length H of the connecting portion, it is preferable that the length of the spacer @ is longer than the length H of the connecting portion, and the length is approximately the same as that of the pressing jig (b).

By adding the spacer 0 in this manner, the external shape after connection becomes the same as the shape before connection, eliminating the need for finishing work such as rework. In addition, since there is no change in shape, it is easy to set up the coil winder on the winder during on-site work, and it can withstand the tension of the winder, which greatly improves work efficiency. The same effects as in Example 1 can be obtained.

Embodiment 3 It should be noted that the implementation of the present invention is not limited to the connection method of Embodiments 1 and 2 as described above. For example, as shown in FIG. It is also possible to connect the wires by applying heat and pressure, and if the other parts are as in Example 1 or 2, the same effects as in Example 1 or 2 can be obtained. .

〔Effect of the invention〕

As described above, according to the present invention, when connecting superconducting wires composed of superconducting filaments and stabilizing materials, the connecting portions of the two to be connected are formed in advance into a scarf joint shape that can be spliced. After that, the stabilizing material on both machined surfaces is removed, the superconducting filament is made to protrude from the stabilizing material, the protruding joint surfaces of both sides are brought together, and the joint surfaces are collet chucked. The superconducting wire retains its superconductivity and can easily obtain excellent connection characteristics by tightening it in the radial direction with a dividing jig such as the above, applying pressure and heating, and joining the superconducting filaments and the stabilizing materials in the same phase. connection method can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the state in which the method of the first embodiment of the present invention is applied, FIG. 2 is an elevational view showing the connection part of the product according to FIG. 1, and FIG. and υ are j incorporated in Fig. 1
Figure 4 is an elevation view showing the superconducting wires pressed together before reaching Figure 2, and Figure 5 is Figure 1. Fig. 6 is a longitudinal cross-sectional view showing a state in which the jigs are combined; Fig. 6 is a cross-sectional view taken along the line Vl-Vl in Fig. 5; Fig. 7 is a permissible connection temperature when applying the method of the present invention A curve diagram showing changes in current, Fig. 8 is an exploded perspective view of parts around the connection part when constructing the method of the second embodiment, and Fig. 9 is a connection part manufactured using the parts shown in Fig. 8. FIG. 10 is an elevational view showing the connection part when constructing the third embodiment, FIG. 11 is a longitudinal cross-sectional view showing the state in which the conventional method is being constructed, and FIG. 12 11 is a sectional view taken along the line XI-XI in FIG. 11, and FIG. 13 is a curve diagram showing the voltage-current characteristics of the connection portion according to the conventional method and the method of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Superconductor filament, 2... Stabilizing material, 3... Superconducting wire, 12
...Saw joint surface, 14...Pressure jig, 15
, 16...Jig for tightening, 17...Chamber, 1
8... Heater, 19... Fixing jig, 2
0... Pressure cylinder, 21... Exhaust device, 2
1a...Inert gas supply device. Agent Patent Attorney Inoue - Male 3rd 1m Figure 4 Figure 1 Figure 2
Figure 9 Figure 10 Figure 5 Figure 6 Figure 12 Figure 13

Claims (2)

[Claims] (1) Both connecting parts of the superconducting wire composed of the superconducting filament and the stabilizing material are processed into diagonal-shaped joint surfaces that increase the connection area, and both processed surfaces are stabilized. The first step is to remove a small amount of the superconducting material to protrude the superconducting filament, and then overlap the two spliced surfaces, place the cylinder in a collet chuck-like pressing jig that divides the cylinder into three or more pieces in the circumferential direction, and then taper the cylinder. A second tightening jig that tightens and pressurizes in the radial direction with a double tightening jig that slides on the surface and heats it with a heater.
A method for connecting superconducting wires, comprising the steps of: (2) The method for connecting superconducting wires according to claim 1, wherein the heating temperature is 400°C to 500°C.