JPS5952490B2 - Manufacturing method of ultrafine multicore superconducting tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the manufacturing method of an alloy or compound-based ultrafine multicore twisted tape, and aims to improve the finished dimensional accuracy of the tape.

Conventional superconducting tapes include single-core superconducting tape and multi-core superconducting tape.

In the case of a single-core superconducting tape, superconductors 2, 2' are placed on both sides of a wide bus alloy board 1, as shown in FIG.
For example, after Nb and Sn are deposited by vapor deposition, solder is poured on the outside of the metal matrix 3, 3', and a pot is attached, the superconducting tape 4 is cut into extremely thin parallel lines. This is what you are getting. However, in the case of a multi-core superconducting tape, as shown in FIG. It is something that exists.

This tape is made by rolling a large or rectangular multicore superconductor into a tape shape, and both ends 5, 5' of the tape
Due to the rolling process, bends and cracks inevitably occur along the longitudinal direction, and if left in this state, the packing factor (pac
hing factor), which in turn causes a decrease in the total current density of the magnets in which these are stacked, or a decrease in the magnetic field uniformity. Therefore, in order to improve this problem, it is possible to correct the bending by cutting the ends 5, 5' as described above. ``...'' is embedded in a spiral shape, so if the ends are simply cut, the superconducting wire will also be cut, making it impossible to achieve its purpose at all as a superconducting tape. In view of the current situation, the present invention has conducted intensive research and has discovered a method for manufacturing a superconducting tape that can be cut with confidence.

That is, the method of the present invention includes the steps of incorporating a large number of alloy superconducting strands or metal strands that become compound superconductors through heat treatment into a portion of the metal matrix other than the vicinity thereof, and rolling this into a tape shape. step, a step of linearly cutting only the matrix metal portions at both left and right ends of the tape formed by this rolling step, and a step of further diffusion in the case of metal wires that will become compound superconductors. This process consists of a step called heat treatment to turn the metal wire into a compound superconductor. An example of the present invention will be explained in detail with reference to the drawings.

A large number of alloy superconductor wires such as Nb-Ti or metal wires that become compound superconductors such as Nb3Sn through heat treatment are gathered near the center of a metal matrix such as copper to form a composite wire, which is then drawn and twisted. After processing and further rolling, it has a thickness T as shown in FIG. 3a. rt]
It is a tape-shaped multicore composite of WO. Furthermore, W as shown in FIG. 3b. Cut both ends of the tape to a thickness of T.
il]Wc superconducting tape. At this time, the finished tape width W is determined from the collective maximum width Wf of the superconducting wires. needs to be wider. In the case of a metal wire that will become a compound superconductor, it is then further heat treated at 600 to 800°C in an atmosphere of an inert gas, such as nitrogen gas, for 20°C.
Heating is carried out for 100 hours to convert the metal wires in the metal matrix into a compound conductor to obtain a superconducting tape according to the present invention. On the other hand, in the case of an alloy superconductor, it is preferable to perform heat treatment to improve superconducting properties either before or after the cutting process. In addition, as a method for performing the cutting process in the above, a tape-shaped multicore composite 4 is used as shown in FIG.
A groove designed to have the same width as the finished tape width WO. W from the top.

A tape of a constant width Wc can be continuously obtained by lowering a smooth roll 7, which is slightly narrower than the width of Wc, while rotating it around an axis, and feeding out the tape while shearing the ends of the tape. However, since this method requires a pair of grooved plates 6 and rolls 7 corresponding to the tape width, it requires complicated steps and costs each time the tape width is changed. Therefore, as shown in FIG. 4b, the tape-like multicore composite 4 is wound spirally around the shaft, and after mounting it on a lathe, cutting the both sides or one side thereof with a cutting tool 8,8'' is performed. A superconducting tape having a width Wc is obtained.Next, examples of the present invention will be described.Example 1 Oxygen-free copper with an outer diameter of 3 mmφ is attached to a quenched Nb-Ti alloy rod with an outer diameter of 2.5 mmφ. (0FHC) coated length 600
2000 mm composite wires were prepared.

On the other hand, the outer diameter is 300mmφ, the inner diameter is 250mmφ, and the length is 600mm.
A mm-thick oxygen-free copper tube was prepared, and the composite wire was embedded in it and drawn to an outer diameter of 3 mmφ. After that, the 8mm pitch was twisted and cold rolled to a thickness of 0.
．． A tape-shaped composite having a size of 26 mm and a width of 15 mm was obtained. This tape has a bend of 1 mm/m along the longitudinal direction.
f was 11.5 mm5. Then, this tape (referred to as comparative tape) was cut in half, and one half was cut into a fourth length.
As shown in Figure a, the tape W is made using the minimum groove width WO=12±0.01 mm and the grooved plate and roll width 11.96±0.01 mm.

A superconducting tape was obtained by the method of the present invention having a bending width of 12±0.01 mm/m and a bending length of 0.1 mm/m along the longitudinal direction. The thus obtained superconducting tape of the present invention and the tape of the comparative example were each heat-treated at 370° C. for 72 hours, and then a spiral coil was produced and the tape width was measured. The results are as follows. Inventive tape
12.05mm comparative example tape 15
．． Critical current value (70KG) of 5mm and both types of short samples
) were consistent within the range of 650±5A.

Therefore, according to the method of the present invention, the packing factor of the coil was improved by 28.7%. Example 2 A niobium tube with an inner diameter of 30.5 mmφ was inserted into an oxygen-free copper tube with an outer diameter of 45 mmφ and an inner diameter of 35 mmφ, and 1,960 pieces of pure vanadium were placed inside the Cu-Ga alloy matrix with an outer diameter of 30 mmφ in advance. Insert the implanted complex,
An aggregate having a length of 105 mm was formed, and this was wire-drawn to a diameter of 2.5 mm.

After that, it was twisted at a pitch of 5 mm, and then rolled to a thickness of 0.2 mm ± 0.01 mm and a width of 8.8 mm.
A tape-shaped multicore composite with ±0.1 mm and bending of 0.6 mm/m was obtained. The Wf of this composite was 5.1 mm.
This composite (referred to as the comparative example tape) was then cut in half, wound in a spiral as shown in Figure 4b, and cut after setting the cutting tool spacing to 6.8 mm. A superconducting tape having a width of 6.8±0.01 m by the method of the present invention was obtained.

The thus obtained tape of the present invention and comparative tape were heated at 625°C.
A diffusion heat treatment was carried out for 30 hours to form a 3Ga compound superconductor at the interface between the Cu-Ga alloy matrix and the core, and the core was re-wound and an insulating coating of about 7 mm thick was applied to the surface with polyvinyl butyral.

In addition, the critical current value (70K) of short samples of these two types of tapes
G) agreed within the range of 530±3A. Furthermore, when a spiral coil was made using these two types of tape and its thickness was measured, the dimensional accuracy of the tape of the present invention was improved by 48 times compared to the comparative example tape, and the total current density of the coil was improved by 23%. . Furthermore, as a result of conducting current in liquid helium, the critical currents of these two types of coils coincided within the range of 528 ± 2 A, and upon transition to normal conduction, reversible voltage generation was observed in the 1-V characteristic, resulting in stable It was verified that electricity could be applied. As detailed above, the method of the present invention has the following effects.

(1) The finishing accuracy of the width of the tape dimension can be significantly improved, which increases the packing factor of the coil and the total current density by more than 20%. (2) The coil thickness of the pancake coil can be controlled with precision. The movement of the tape during excitation is reduced, and the operation of the magnet is stabilized.

(3) When it is desired to change the current capacity, by using a stabilizing metal suitable for the current capacity as the outermost layer, this layer can be cut and controlled freely.

(4) Applicable to alloy-based and compound-based superconducting tapes.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway perspective view of a conventional single-core superconducting tape, Figure 2 is a partially cutaway perspective view of a conventional multicore superconducting tape, and Figure 3 is a partially cutaway perspective view of a conventional multicore superconducting tape.
Figure a is a perspective view of a superconducting tape before cutting by the method of the present invention, Figure 3 b is a perspective view after cutting, Figures 4 a and b.
FIG. 2 is an explanatory diagram showing an example of cutting in the method of the present invention. 1... core body, 2, 2'', 2''''... superconductor, 3,
3''...Metal matrix, 4...Tape-shaped multicore composite, 5,5''...End portion, 6...Grooved substrate, 7...
・Roll, 8,8″...Bite.

Claims (1)

[Claims] 1. After incorporating a large number of alloy superconducting strands in a part of the metal matrix other than the vicinity thereof, this is rolled into a tape shape, and then the tape formed by this rolling is A method for manufacturing an ultra-fine multicore superconducting tape, characterized by cutting matrix metal at both left and right ends of the tape into a straight line. 2. After incorporating a large number of metal wires that will become a compound superconductor through heat treatment into a portion of the metal matrix other than the vicinity of the wafer, this is rolled into a tape shape, and then, by this rolling, An ultrafine multifilamentary superconducting tape characterized in that the matrix metal at both left and right ends of the formed tape is cut into a straight line, and then heat treated to turn the metal wires in the matrix into a compound superconductor. Production method.