JPH04259709A - Superconductive wire manufacture method - Google Patents

Abstract

PURPOSE:To provide a superconductive wire manufacturing method with little loss of a superconductive alloy material. CONSTITUTION:Both ends of a metal pipe 1 filled with a superconductive alloy material 2 are covered with metal covers 3 whose thickness is 20-100% of the thickness of the metal pipe 1 to give a composite billet 4. In the extrusion- processed material obtained by extruding the composite billet, the tip part and the rear end part having a high advancing ratio are located in the metal covers and the superconductive alloy material located part has a low advancing ratio and thus an inferior part lacking the superconductive alloy material is lessened and as a result, the superconductive alloy material loss is lowered.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a superconducting wire with little loss of superconducting alloy material.

[Prior Art] Superconducting wires are made of Nb-Ti to prevent rapid temperature rises, that is, quenching, caused by flux flow.
It is constructed by combining superconducting alloy material such as alloy with copper or copper alloy, etc., which has excellent thermal conductivity. To manufacture a superconducting wire with such a configuration, for example, a copper pipe is filled with one Nb-Ti superconducting alloy wire, the inside of the pipe is vacuum degassed, and copper caps are fixed to both ends of the pipe to form a composite. It is produced by forming a billet, extruding this composite billet into a desired shape, and subjecting the extruded material to surface reduction processing such as drawing. The superconducting wire manufactured in this way is a single-core superconducting wire in which one superconducting alloy wire is composited in a copper matrix, but in reality, many of these single-core superconducting wires are filled into a copper pipe. This wire is processed to reduce its area to form a multicore superconducting wire, and the superconducting alloy material, that is, the superconducting filament is dispersed as finely as possible, and is used as a wire with good heat dissipation.

0002

[Problems to be Solved by the Invention] Generally speaking, as shown in FIG. 3, the metal flow of extruded materials is such that due to the influence of frictional resistance between the extruded billet 5 and the inner surface of an extrusion die (not shown), the extruded billet It has a shape in which the deformation of the portion corresponding to the surface of No. 5 is delayed, and this tendency of delay is noticeable at the front end and rear end portions of the extruded material. On the other hand, the composite billet used in the production of superconducting wire is
As shown in the longitudinal cross-sectional view of Fig. 4, the thickness of the metal lid 3 is made thin so that the good part filled with the superconducting alloy material 2 can be kept as long as possible during extrusion processing. As a result, the extruded material obtained by extruding this composite billet 4 has a large number of defective parts where the superconducting alloy material 2 is insufficient at its leading and trailing ends, as shown in the longitudinal cross-sectional view of FIG. However, since these defective parts are removed by cutting, there is a problem in that a large amount of expensive superconducting alloy material is lost.

0003

[Means and effects for solving the problems] The present invention was made as a result of intensive research under these circumstances, and its purpose is to manufacture superconducting wires with less loss of superconducting alloy materials. The purpose is to provide a method. That is, the present invention provides a composite billet by fixing metal lids to both ends of a metal pipe filled with one superconducting alloy wire, multiple single-core superconducting wires, or multiple multi-core superconducting wires, The method for manufacturing a superconducting wire in which the composite billet is then subjected to area reduction processing including extrusion processing is characterized in that the thickness of the metal lid is 20% to 100% of the diameter of the metal pipe. It is something to do.

In the method of the present invention, the material of the metal pipe filled with superconducting alloy material such as superconducting alloy wire, single-core superconducting wire, multi-core superconducting wire, etc. mainly includes oxygen-free copper, tough pitch copper, copper-tin alloy, etc. Copper or copper alloy is used, but any metal material can be used as long as it has excellent thermal conductivity. Also, the metal lid that covers the metal pipe is usually made of the same material as the metal pipe. In addition, in the method of the present invention, the reason why the thickness of the metal lid is limited to 20% to 100% of the diameter of the metal pipe used is that if the thickness is less than 20%, defective parts where the superconducting alloy material of the extruded material is insufficient This is because the length becomes longer, and when it exceeds 100%, the yield length of a good part filled with superconducting alloy material obtained by one extrusion becomes shorter, both of which reduce cost or productivity. The method for manufacturing a superconducting wire of the present invention will be specifically explained below with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view showing an example of an embodiment of a composite billet used in the method of the present invention, and FIG. 2 is a longitudinal cross-sectional explanatory view showing an example of a metal flow of an extruded material of the composite billet. The composite billet is produced by filling a metal pipe 1 with a superconducting alloy material 2 as shown in Fig. 1, then vacuum degassing the metal pipe 1, and then welding metal lids 3 to both ends. be done. Next, the composite billet 4 produced in this way is subjected to tapping or HI process as necessary.
After P treatment or the like is performed to improve the adhesion between the outer circumferential metal pipe 1 and the inner superconducting alloy material 2, the tube is hot extruded into a desired shape. As shown in FIG. 2, the obtained extruded material has a leading end portion and a trailing end portion with a high advancement rate located in the metal lid 3, and a portion where the superconducting alloy material 2 is arranged has a small advancement rate, so The number of defective parts due to lack of superconducting alloy material is reduced. The extruded material thus obtained is then cut and removed to remove defective portions, and then processed into a superconducting wire of a predetermined shape by an area-reducing method such as swaging or drawing.

[0005]

[Examples] The present invention will be explained in detail below using examples. Example 1 An oxygen-free copper pipe with an outer diameter of 250 mm and an inner diameter of 150 mm was filled with a Nb-Ti superconducting alloy material wrapped in one layer using a 1.7 mm thick Nb plate as a barrier, and then the inside of the pipe was vacuum degassed. Thereafter, caps made of oxygen-free copper of various thicknesses were electron beam welded to both ends of this pipe to produce composite billets. The length of this composite billet is 900 mm including the lid.
Standardized to mm. Next, this composite billet was subjected to HIP treatment and compressed to an outer diameter of 245 mm, and then compressed to 850 mm.
It was heated to ℃ and extruded into a wire rod with a diameter of 25 mm. For the extruded material obtained in this way, the length (yield length) of the non-defective part filled with Nb-Ti superconducting alloy material with a predetermined diameter inside was measured, and The ratio of the length of the non-defective part (defective product rate) was determined. The results are shown in Table 1.

[0006]

[Table 1]

As is clear from Table 1, the method of the present invention (
Nos. 1 to 5) all showed high values of yield length and/or good product rate. If the sum of the thicknesses of the lids at the tip and rear end are the same, the one with the thicker lid at the leading end during extrusion (No. 2) is the one with the same thickness at the front end and the rear end (No. 3). The yield length and non-defective rate are both higher, but this is because the leading edge rate of the extruded material is greater at the leading end than at the trailing end. On the other hand, the N of the comparative example product
o6 had a thin lid, so the rate of good products was extremely low, and N
In o7, the lid was too thick, so the yield length was extremely short.

Example 2 A 25 mmφ extruded material obtained under the conditions No. 2 of Example 1 was subjected to drawing and wire drawing to produce a 2.5 mmφ single-core superconducting wire. Next, 7,000 of these single-core superconducting wires were prepared using the same outer diameter of 250 mm and inner diameter of 15 mm as used in Example 1.
After filling a 0 mm oxygen-free copper pipe and evacuating the inside of the pipe, oxygen-free copper lids of various thicknesses were electron beam welded to both ends of the pipe to form a composite billet. The length of the above composite billet including the lid was 1200 mm. The composite billet thus produced was compressed to an outer diameter of 240 mm by HIP treatment, and then this composite billet was heated to 500° C. and hot extruded into a wire rod of 45 mmφ. Regarding the extruded material thus obtained, the length of the non-defective part in which the inside was filled with 7000 single-core superconducting wires was measured, and the non-defective product rate was determined. The results are shown in Table 2.

[0009]

[Table 2]

As is clear from Table 2, the method of the present invention (
Nos. 8 to 12) showed high values of yield length and/or good product rate. If the sum of the lengths of the pipe tip and rear end caps is the same, choose the one with the thicker tip cap (No. 9).
) was the same as in Example 1 in that the yield length and non-defective rate were higher than those of the same length (No. 10). On the other hand, Comparative Example Product No. 13 had a thin lid, so the rate of non-defective products was extremely low. In addition, since the lid of No. 14 was too thick, the yield length was extremely short. Above, an example was explained in which a superconducting wire was manufactured using a composite billet in which a metal pipe was filled with one superconducting alloy wire or a large number of single-core superconducting wires. A similar effect can be obtained when billet is used. Furthermore, although an example was explained in which Nb-Ti superconducting alloy was used as the superconducting alloy material, the method of the present invention is applicable to Nb3Sn
Similar effects can be obtained even when applied to the production of other superconducting wires such as superconducting wires.

[0011]

[Effects] As described above, according to the method of the present invention, it is possible to reduce the loss of expensive superconducting alloy material that occurs during extrusion processing, so that it has a significant industrial effect.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a composite billet used in the method of the present invention.

FIG. 2 is an explanatory diagram of a metal flow of an extruded material in the method of the present invention.

FIG. 3 is an explanatory diagram of metal flow of extruded material.

FIG. 4 is a longitudinal cross-sectional view of a conventional composite billet.

FIG. 5 is a metal flow explanatory diagram of a conventional composite billet extruded material.

[Explanation of symbols]

1 Metal pipe 2 Superconducting alloy material 3 Metal lid 4 Composite billet 5 Extrusion billet

Claims (1)

[Claims] Claim 1: A metal pipe filled with one superconducting alloy wire, multiple single-core superconducting wires, or multiple multi-core superconducting wires is fixed with metal lids at both ends to form a composite billet, and then The method for manufacturing a superconducting wire in which the composite billet is subjected to area reduction processing including extrusion processing is characterized in that the thickness of the metal lid is 20% to 100% of the diameter of the metal pipe. Method of manufacturing superconducting wire.