JPH05190034A - Superconducting wire manufacturing method - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for easily manufacturing a high-quality long superconducting wire. [Constitution] Superconducting wire coated with copper is filled into a copper pipe to form a composite billet, and the composite billet is subjected to prescribed surface reduction processing to form a superconducting wire rod. In the wire manufacturing method, a superconducting wire having a diameter of 2 mmφ or less, which is easy to be broken, is drawn by using a water-soluble lubricating oil having both an oil content concentration of 5 to 20% and improved lubrication performance and cooling performance. It is possible to efficiently produce a long superconducting wire having a low filament breakage rate and excellent surface quality.

Description

Detailed Description of the Invention

[0001]

The present invention relates to superconducting power generation, MRI,
Nb-T with excellent superconducting properties used in particle accelerators, etc.
The present invention relates to a method for manufacturing a superconducting wire such as an i alloy.

[0002]

2. Description of the Related Art In recent years, in Nb-Ti alloy-based superconducting wires, etc., ultrafine N of 30 μmφ or less is used for the purpose of improving superconducting characteristics.
There has been a demand for the development of a long material, which is an ultrafine multi-core material in which 2000 to 8000 b-Ti filaments are embedded and which has as few connections as possible that cause permanent current to be attenuated.
By the way, in manufacturing such Nb-Ti alloy superconducting wire, a Nb-Ti alloy ingot conventionally cast by an arc melting method is formed into a round bar material by a surface-reduction processing method such as extrusion and rolling, and this is used as a copper pipe. Insert it, reduce the surface to make a composite wire, then immediately cut this composite wire, cut it to a fixed length, bundle a large number of this fixed size wire into a copper pipe and make a composite billet, Next, the composite billet is densified by HIP treatment or the like, and then subjected to surface-reducing processing such as hot extrusion, drawing processing, wire drawing processing or the like to obtain Nb having a predetermined shape.
-Ti superconducting wire is used, and when the Nb-Ti filament is further made into a multi-filamentary core, a large number of this superconducting wire is filled in a copper pipe again, and this is manufactured by reducing the surface area. ..

[0003]

However, in such a conventional manufacturing method, the wire diameter of the superconducting wire is 2 mmφ.
If it becomes thin to a certain extent, there is a problem that the wire breakage easily occurs during the wire drawing process, a long superconducting wire cannot be obtained, and further, the wire breakage rate of the internal filament also increases and the superconducting property is significantly deteriorated. It was

[0004]

In the present invention, as a result of intensive studies in view of the above situation, the wire drawing workability of a superconducting wire is significantly affected by the type of lubricant used, for example, the oil concentration of a water-soluble lubricating oil. The present invention has been completed, and further research has been conducted to complete the present invention. That is, the present invention, a superconducting wire coated with copper is filled into a copper pipe to form a composite billet, the composite billet is subjected to predetermined surface-reduction processing to form a superconducting wire, and this superconducting wire is drawn. In the method of manufacturing a superconducting wire, the wire drawing of a superconducting wire having a diameter of 2 mm or less is performed by using a lubricant with an oil content of 5 to 20%.
The method for producing a superconducting wire is characterized in that the above water-soluble lubricating oil is used.

In the method of the present invention, the water-soluble lubricating oil contains
Any water-soluble lubricating oil such as emulsion type, soluble type and chemical solution type can be applied. The reason for limiting the oil concentration of the water-soluble lubricating oil to 5 to 20% is that if it is less than 5%, the oil content is not sufficiently applied to the surface of the wire and the lubrication performance is lowered, and the filament breakage rate increases.
This is because the wire itself is broken, and the die is burned, causing the surface of the wire to become rough and causing troubles in the subsequent surface treatment process.If the oil content exceeds 20%, the cooling performance will increase. This is because the wire drawing speed cannot be increased and the wire drawing speed cannot be increased, and moreover the oil remains in the form of a film on the surface of the wire, which interferes with the subsequent steps such as enamel coating. Thus, with respect to a superconducting wire having a smaller diameter with more cores, the oil concentration is 10 to 18
It is preferable to limit to the range of%. The method of the present invention is
The effect is sufficiently exerted when applied to the production of —Ti alloy superconducting wire and Nb ₃ Sn compound superconducting wire. In addition to the circular shape, the cross-sectional shape of the superconducting element wire filled in the copper pipe during the production of the composite billet is mainly a hexagonal shape, which is excellent in the packing density.

[0006]

In the method of the present invention, the wire drawing of a superconducting wire having a wire diameter of 2 mmφ or less is performed by using a water-soluble lubricating oil having an oil concentration limited to 5 to 20% to improve both lubricating performance and cooling performance. Since this is performed, a long superconducting wire having a low filament breakage rate and excellent surface quality can be manufactured.

[0007]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 A composite billet was prepared by filling 8,000 copper-coated Nb-Ti alloy-based superconducting hexagonal wires with opposite sides of 2.38 mm into a copper pipe having an outer diameter of 260 mmφ and an inner diameter of 224 mmφ. Next, this composite billet is compression-molded by a hot isostatic press (HIP) to densify it, then the composite billet is chamfered and then hot extruded to form a 30 mmφ composite rod.
Then, the composite rod was groove-rolled while being appropriately heat-treated to form a 1.5 mmφ Nb-Ti superconducting wire. Next, this Nb-Ti superconducting wire was continuously drawn at a speed of 500 m / min to form a 0.221 mmφ fine wire. Soluble oil was used as the lubricant for the wire drawing, and the oil concentration was variously changed. The number of wire breakages at the time of wire drawing, and the obtained superconducting wire was immersed in an aqueous nitric acid solution to dissolve and remove copper, and the wire breakage rate of the filament was examined. In addition, the surface of the wire drawing material is S
It was observed by EM. The results are shown in Table 1 together with the oil concentration of the water-soluble lubricating oil.

[0008]

[Table 1]

As is clear from Table 1, the method products of the present invention (Nos. 1 to 9) were capable of being drawn without breaks and had excellent surface quality. Among them, the filament breakage rate was particularly low in those drawn by using a water-soluble lubricating oil having an oil concentration of 10 to 18% (No. 4 to 8). On the other hand, No.
No. 10 used a lubricating oil with a low oil content, so its lubrication performance was poor, wire breakage occurred frequently, surface quality deteriorated, and the wire breakage rate of the filament exceeded 10%. In Nos. 11 to 13, the oil content of the lubricating oil was high, so the wire drawing temperature increased and the speed decreased somewhat to draw the wire. Further, an oil film remained on the surface of the wire drawn material, and the enamel could not be uniformly coated. Has been described above Nb-Ti alloy-based superconducting wire, the method of the present invention is that the same effect can be obtained by applying to the production of Nb ₃ Sn compound superconducting wire.

[0010]

As described above, according to the method of the present invention, it is possible to easily produce a long superconducting wire having a small filament breakage rate and an excellent surface quality, and to exert a remarkable industrial effect.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyota Suita 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A superconducting element wire coated with copper is filled in a copper pipe to form a composite billet, and the composite billet is subjected to predetermined surface-reduction processing to form a superconducting wire material. This superconducting wire material is drawn. In the manufacturing method of the superconducting wire to be applied, 2 m
A method for producing a superconducting wire, which comprises drawing a superconducting wire having a diameter of mφ or less using a water-soluble lubricating oil having an oil concentration of 5 to 20% as a lubricant.