JP2573942B2 - Superconducting wire twist processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an AC superconducting wire used for a superconducting generator or the like.

"Conventional technology" Superconducting wires are used in experimental reactors for fusion reactors, magnetic levitation trains, and superconducting tomographic diagnostic equipment (MRI). Recently, superconducting wires such as superconducting generators are used. As the demands have increased.

Important techniques in this type of AC superconducting wire manufacturing method are a technique for reducing the hysteresis loss by making the superconducting filament extremely fine, and a technique for reducing the hysteresis loss by twisting the superconducting filament at the shortest possible pitch. And a technique for increasing the electrical resistance of the base material between the superconducting filaments to reduce the electrical coupling loss between the superconducting filaments.

Among the above-mentioned techniques, with regard to the technique of shortening the twist pitch length, conventionally, it is possible to process the wire to a pitch length several times to about 10 times the wire diameter by alternately performing intermediate annealing and wire drawing. That is, after the drawing process is stopped at a diameter just before the final wire diameter, an intermediate annealing process is performed, a twist process is performed at a working degree of 5 to 10%, and a further intermediate annealing process is performed, and then the final drawing process is performed. Pull) to obtain the product.

"Problems to be Solved by the Invention" By the way, it is desirable to shorten the twist pitch length as much as possible in order to reduce the loss as the length becomes shorter. However, if the twist pitch length is excessively shortened, there is a problem that the superconducting wire is broken during the twisting process.When the superconducting wire is twisted by the conventional method, the twist pitch length is about several mm to 10 mm. Is the limit. The twist pitch length of several mm to 10 mm can be said to be a small twist pitch length for a superconducting wire having a large wire diameter.However, when a superconducting wire having a wire diameter of about 0.1 to 0.5 mm is manufactured, a wire pitch of 10 mm is used. The twist pitch length is about twice as large. Therefore, it is desired to further shorten the twist pitch length. It is considered that the reason why the twist pitch length is limited as described above in the conventional method is that only the effect of increasing the workability by softening the stabilized base material by the annealing treatment can be expected.

The present invention has been made in view of the above problems, and can reduce the twist pitch length of a superconducting wire as compared with the related art.
It is an object of the present invention to provide a method for twisting a superconducting wire capable of obtaining a superconducting wire having a small hysteresis loss when an alternating current is used.

"Means for Solving the Problems" The present invention provides a method for twisting a superconducting wire formed by embedding a superconducting conductor inside a base material, in order to solve the above-mentioned problems. It is installed in a housing, and the inside of the housing is heated to form a hot heating zone, and the superconducting wire is fed from the outside of the housing to the inside to draw the superconducting wire into the hot heating zone. The twisting process is performed by passing through a die, and after the twisting process, the superconducting wire is again passed through the hot heating zone inside the housing and then drawn out of the housing.

[Function] In order to apply twist processing to a superconducting wire by a die in a hot heating zone, even if the processing rate causes a disconnection in the conventional method, twist processing is performed without disconnection by performing the method of the present invention. And a superconducting wire having a small twist pitch length can be manufactured. Also,
The inside of the housing is heated to form a hot heating zone, a die for twisting is provided here, the superconducting wire is drawn into the hot heating zone in the housing, and then twisted with a die. Since the wire is drawn after passing through the heating zone, the diffusion time of metal atoms inside the superconducting wire is suppressed by shortening the time of passing through the hot heating zone, and contamination of the stabilized base material by the metal element is prevented.

 Hereinafter, the present invention will be described in more detail.

The drawings are for describing the present invention. In order to obtain a superconducting wire for AC by performing a twisting process, first, Nb-Ti
A superconducting wire 1 having a three-layer structure in which a superconducting conductor such as a superconducting filament is disposed in a Cu-Ni preform and a composite material in which a superconducting conductor such as a superconducting filament is disposed inside a Cu-Ni preform is prepared. Wrap around.

The superconducting wire is fed out of the delivery bobbin 2 as shown in the drawing, passes through the guide tube 3, and is drawn into the housing 4.

The housing 4 has an airtight structure and is provided with a heating device so that the inside can be heated to a temperature of about 800 ° C. Further, the housing 4 is connected to an inert gas supply device such as nitrogen gas or argon gas, so that the inside can be maintained in an inert gas atmosphere. A die 5 for twisting is provided inside the housing 4.

On the other hand, a water tank 6 is installed on the side of the housing 4, and a take-off capstan 7 is installed on the side,
Further, a winding bobbin 8 is provided on the side. Prior to the operation of drawing in the superconducting wire 1, the inside of the housing 4 is filled with an inert gas, heated to a temperature of about 800 ° C., and the inside is set as a hot heating zone.

In this state, the superconducting wire 1 drawn into the housing 4 is passed through a die 5 for twisting to perform twisting, and then pulled out of the housing 4 and rapidly cooled in a water tank 6. Here, if the superconducting wire 1 is heated to a high temperature of about 800 ° C. for a long time, the metal elements in the wire may diffuse into each other and contaminate the stabilizing base material made of Cu. Since the element passes through the housing 4 in a short time and is rapidly cooled, the diffusion of the element does not proceed, thereby preventing deterioration of superconducting characteristics.

The superconducting wire 1 cooled in the water tank 6 is taken up by a take-up capstan 7 and finally wound up on a winding bobbin 8.

In the above method, since the superconducting wire 1 is hot-worked at the time of twisting, the superconducting wire 1 can be worked at a larger working ratio than before without breaking, and a twisting process with a shorter pitch than before can be performed. Accordingly, there is an effect that an AC superconducting wire with a small loss can be obtained.

By the way, in the above example, the inside of the housing 4 is
Although heated to 800 ° C., the heating temperature may be any temperature as long as it is higher than the temperature at which hot working is possible (about 400 to 500 ° C.). However, when the temperature is lower than 800 ° C., the speed at which the superconducting wire 1 passes through the housing 4 needs to be set low so that the superconducting wire 1 can be sufficiently heated to a temperature at which hot working is possible. Further, setting the temperature of the housing 4 to 800 ° C. or higher is not preferable because the superconducting filament is damaged by heat.

"Example" A three-layer superconducting wire formed by disposing a composite wire in which a Nb-Ti superconducting filament is disposed inside a stabilized preform made of Cu and disposed inside a Cu-Ni preform is drawn to 0.22 mm. And wound it around a delivery bobbin. In addition, use an apparatus equivalent to the apparatus shown in the drawing, and set the inside of the
Heat to In this state, the superconducting wire was drawn into the inside of the housing, and was passed through a twisting die (inner diameter of a die hole: 0.21 mm) provided in the inside of the housing to perform twisting. Subsequently, the superconducting wire was pulled out of the housing, rapidly cooled in a water tank, and wound up on a winding bobbin via a take-up capstan. In the above-described process, the rotation speed of the delivery bobbin is 1200 rpm, and the take-off speed is 1
000 mm / min and the superconducting wire twist pitch length is 0.8
mm.

The superconducting wire wound on the winding bobbin was further reduced in diameter and drawn to a diameter of 0.2 mm. When the twist pitch length of the superconducting wire after the drawing was measured, it was about 1.0 mm. Therefore, a superconducting wire having a shorter pitch than before can be obtained without disconnection.

In addition, a superconducting wire having a structure equivalent to the three-layer superconducting wire used in the above operation was prepared, and a twist process for setting the housing temperature to 500 ° C. and performing the same operation as the above operation was performed. This superconducting wire broke during the twisting. This is presumably because when the superconducting wire was passed through the housing at the above-described take-up speed, the take-up speed was too high, and the inside of the superconducting wire was subjected to excessive twisting before it was not sufficiently heated.

[Effects of the Invention] As described above, the present invention performs the hot working by using a die to perform the twist working of the superconducting wire in the hot heating zone. Pitch twisting can be performed, and a superconducting wire with low loss for AC can be obtained. Also, since the superconducting wire is twisted by passing through the hot heating zone in the housing and the time for heating the superconducting wire can be adjusted, the diffusion of the metal element inside the superconducting wire is reduced by shortening the heating time. This makes it possible to obtain a short-pitch superconducting wire without causing contamination of the stabilizing base material. Furthermore, the inside of the housing is heated to form a hot heating zone, a die for twisting is provided here, the superconducting wire is fed into the hot heating zone in the housing, and then twisted with a die. Once the superconducting wire is heated to the hot working temperature, twisted, and then heated to the hot working temperature again after working, and then pulled out of the housing, the wire is pulled out after passing through the heating zone. The steps of heating, processing, and heating can be sequentially and continuously performed only by passing through the housing and the die inside the housing. Therefore, a superconducting wire having a small twist pitch can be obtained without disconnection.

[Brief description of the drawings]

The drawing is a block diagram showing an example of an apparatus used for carrying out the method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Superconducting wire, 2 ... Delivery bobbin, 3 ... Guide tube, 4 ... Housing, 5 ... Dies, 6 ... Water tank, 7 ... Capstan, 8 ... Winding bobbin.

Claims (1)

(57) [Claims] 1. A method for twisting a superconducting wire in which a superconducting conductor is embedded in a stabilizing base material, comprising: installing a die for twisting in a housing; Along with the zone, the superconducting wire is sent from the outside of the housing to the inside, the superconducting wire is drawn into the hot heating zone, and then passed through a die in the hot heating zone to perform a twisting process. A method for twisting a superconducting wire, wherein the superconducting wire is drawn out of the housing after passing through a hot heating zone inside the housing again.