JPH09148120A - Superconductive magnet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the movement of a superconductive wire by electromagnetic force thereby suppressing the cracking in an impregnated material by a method wherein a superconductive magnet is constituted to be capable of avoiding release.cracking in the impregnated material between a winding part and a bobbin by electromagnetic stress providing no bobbin inside the winding part requiring no specific device as well as capable of easily forming the solenoid type winding part furthermore stably holding the winding part. SOLUTION: A superconductive wire 1 is wound up around a tack bobbin 7 in a solenoid type disconnectably attaching flanges 5 to both ends of the bobbin 7 to form a winding part 2 and after constituting a winding holding frame 3 by integrally connecting a holding cylinder 4 fitted to the outer periphery of the winding part 2 and both end flanges 5, the tack bobbin 7 is separated from both flanges 5 to be pulled out from the side of the winding part 2 in the axial direction. Finally, a superconductive magnet is constituted by impregnating the winding part 2 inside the winding holding frame 3 with an impregnant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet which has a winding portion formed by winding a superconducting wire in a solenoid shape and which is excited at an extremely low temperature to generate a large electromagnetic force.
In particular, it relates to a superconducting magnet having no structure on the inner diameter side of a winding portion and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a superconducting magnet having a solenoid-shaped superconducting winding portion, a superconducting wire wound due to strong electromagnetic stress during excitation moves from the superconducting state to the normal conducting state due to frictional heat generated at that time. There is a phenomenon (quenching) in which a large accumulated energy is released as heat due to the decay of the magnetic field in a short time. Then, conventionally, as a means for preventing this quenching, a method of impregnating a winding portion of a superconducting wire with an impregnating material such as an epoxy resin and filling and fixing a gap between the wires has been adopted. However, by using the impregnating material, the movement of the superconducting wires is suppressed, but as shown in [Fig. 2], the winding part (1) of the superconducting wire (12) is provided on the outer circumference of the cylindrical bobbin (11).
In a superconducting magnet that forms 3) and is operated at a high current density, electromagnetic force is applied to the winding part (13) in the axial direction and the radial direction indicated by the arrows in the figure. A stress equal to or higher than the breaking stress of the impregnated material acts between the winding and the winding frame, causing cracking of the impregnated material between the winding part and the winding frame.The mechanical energy released by this crack is converted into heat energy and quenched. cause.

Therefore, in order to prevent this, a method has been proposed in which the winding frame causing peeling and cracking is removed in advance.
For example, in the superconducting coil disclosed in Japanese Patent Laid-Open No. 4-102304, as shown in [FIG. 3], flanges (22) are provided on the outer circumferences of both ends of a winding cylinder (21) divided into a plurality in the circumferential direction. In addition to fitting, a pair of nuts (23) are fitted to both ends of the inner circumference through holding bolts (24) with opposite screws on both sides to form a winding frame (20). A superconducting wire (25) is wound in multiple layers around the outer circumference of the reel cylinder (21) of the frame (20) to form a solenoid-shaped superconducting coil, and the superconducting coil is impregnated and fixed with a synthetic resin, and then the pair of nuts ( 23) is removed and the reel cylinder (21) is removed. Further, as shown in FIG. 4, the solenoid coil disclosed in Japanese Patent Laid-Open No. 59-111317 has a structure in which a rotating inner cylinder (3) is provided in a reinforcing cylinder (31) attached to a rotating device (30).
A temporary coil (34) formed by winding a superconducting wire around the outer periphery of 3) is concentrically arranged so as to be movable up and down, and through a guide device (35) provided on the outer peripheral portion of the temporary coil (34), The superconducting wire is extended in the radial direction from the temporary coil (34) while applying a compressive force in the lengthwise direction, and closely wound around the inner surface of the rotating reinforcing cylinder (31) to form a solenoidal winding (32). However, the winding portion (32) is held from the outside by the reinforcing cylinder (31).

[0004]

However, in the configuration of the former of the above-mentioned prior art (Japanese Patent Laid-Open No. 4-102304), since there is no winding frame on the inner diameter side of the winding portion, the impregnation material on the inner diameter side is Although cracking can be suppressed, by simply fixing the flanges to both ends of the winding part, the shape of the winding part is held only by the impregnated material, which makes it difficult to support the winding part, and also the flange and winding Since winding stress is applied between the wire parts, if electromagnetic stress is further applied to the wire part, cracking of the impregnated material will occur between the wire winding part and the flange, and this crack will open Mechanical energy can be converted into heat energy and cause quenching. On the other hand, in the configuration of the latter of the above-mentioned prior art (Japanese Patent Laid-Open No. 59-111317), since the winding frame does not exist on the inner diameter side as in the above case, cracking of the impregnating material can be suppressed, and the winding portion is made of a reinforcing cylinder. Since it is held from the outside, the movement of the superconducting wire due to electromagnetic force can be suppressed and the entire support is easy, but a special device is required to wind the winding part and the process is complicated. There is a problem that

The present invention has been made in order to solve the above-mentioned problems of the prior art. It removes the winding frame on the inner diameter side of the winding portion of the superconducting wire, and impregnates between the winding portion and the winding frame during excitation. Assuming that the superconducting magnet has a structure that avoids peeling and cracking, it is possible to easily wind and form a solenoidal winding part without the need for a special device, and to stably hold the winding part. It is an object of the present invention to provide a superconducting magnet having a structure in which the whole is easily supported and a method for manufacturing the same.

[0006]

In order to achieve the above object, the present invention has the following arrangement. That is, the superconducting magnet according to the present invention, after the superconducting wire is wound in a solenoid shape on the outer periphery of the cylindrical temporary winding frame that is detachably attached to both ends of the flat annular flange, the inner temporary winding frame is The winding portion of the superconducting wire obtained by pulling out, the flanges at both ends of the winding portion separated from the temporary winding frame, and the holding cylinder fitted on the outer periphery of the winding portion are integrally connected. A winding holding frame is provided.

In the method for manufacturing a superconducting magnet according to the present invention, a superconducting wire is wound in multiple layers on the outer circumference of a cylindrical temporary winding frame having separable flat annular flanges attached to the outer circumferences of both ends to form a solenoidal shape. A first step of forming the winding portion, a second step of fitting a holding cylinder having a length covering the entire length of the winding portion in the axial direction on the outer periphery of the winding portion, and both end portions of the holding cylinder. A third step of connecting to the outer peripheral portions of both the flanges to form a winding holding frame in which the holding cylinder and the both flanges are integrated; and separating the temporary winding frame and both flanges from each other, And a fourth step of axially extracting from the line portion.

In the second step, the holding cylinder may be fitted to the outer circumference of the winding part in a state where the inner diameter of the holding cylinder is expanded by thermal expansion. Further, in the fourth step, the temporary winding frame may be cooled and the outer diameter may be reduced by heat shrinkage, and the temporary winding frame may be extracted from the winding part. Furthermore, a material having a small friction coefficient is applied to the outer peripheral surface of the temporary reel in advance,
Alternatively, a sheet made of the material may be wound around.

In the superconducting magnet according to the present invention,
Since there is no winding frame inside the winding part, exfoliation / cracking of the impregnated material does not occur between the winding part and winding frame during excitation, unlike conventional superconducting magnets, and does not cause quenching. . In addition, the superconducting wire is wound around the outer circumference of the temporary winding frame with the flanges separably attached at both ends to form a winding portion, and the winding portion is separated from the temporary winding frame by both flanges. And a holding cylinder fitted on the outer circumference of the winding portion, which are integrally connected to each other, hold the winding holding frame from above and below and on the outer circumference side, and then remove the temporary winding frame inside Therefore, the solenoidal winding portion can be easily formed without requiring a special device as in the prior art. Moreover, since the winding portion is held from the upper and lower sides and the outer peripheral side by the winding holding frame in which the flanges at both ends in the axial direction and the holding cylinder on the outer periphery are integrated, the whole can be easily and firmly supported. It is possible to suppress the movement of the superconducting wire due to the electromagnetic force during excitation, thereby suppressing the cracking of the impregnated material and suppressing the occurrence of quench.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. [FIG. 1] is a drawing showing a structure and a manufacturing procedure of one embodiment of a superconducting magnet according to the present invention, in which (a) is a front sectional view showing a schematic structure, and (b) is a diagram-
FIG. 7E is an explanatory sectional view of an example of the manufacturing procedure.

The superconducting magnet of this example shown in (a) of FIG. 1 has a winding portion (2) formed by winding the superconducting wire (1) in a solenoid shape, and a winding portion (2) of this winding portion (2). Flange on both ends
A winding holding frame (3) formed by integrally connecting (5) and a holding cylinder (4) fitted on the outer circumference of the winding portion (2), and a winding holding frame (3) The winding part (2) is made of an impregnating material (6) impregnated in the winding part (2) and has no structure such as a winding frame on the inner diameter side of the winding part (2).

The manufacturing procedure of the superconducting magnet of this example will be described below with reference to FIGS. First, a cylindrical temporary reel (7) and a pair of flat annular flanges (5) having an inner diameter that fits the outer diameter of the temporary reel (7) are prepared, as shown in (b). As described above, the pair of flanges (5) are fitted to the outer peripheries of both ends of the temporary winding frame (7), and are separably connected via fastening means such as bolts. Then, as shown in Fig. (C), the superconducting wire (1) is wound in multiple layers around the outer periphery of the temporary winding frame (7) between the flanges (5) to form a solenoidal winding part (2). .

Here, in this example, a copper-stabilized NbTi superconducting wire is used as the superconducting wire (1), while the temporary bobbin (7) has a heat shrinkage ratio from room temperature to 77 K from that of the superconducting wire (1). Also large Al
The flange (5) is made of stainless steel whose thermal contraction rate from room temperature to 4.2K is similar to that of the superconducting wire (1), and the flange (5) is approximately the same as the outer diameter of the winding part (2). They have the same outer diameter. Further, for winding the superconducting wire (1), a very general winding device / method applied to a superconducting magnet having an ordinary winding frame was used.

Next, an inner diameter that is prepared in advance and is approximately equal to the outer diameter of the winding portion (2), and the winding portion (2) and both flanges.
A cylindrical holding cylinder (4) having an inner length substantially equal to the axial length added with (5) is added to the winding part as shown in (d).
Fit it on the outer circumference of (2). Then, this holding cylinder (4)
Connect both ends to the outer periphery of both flanges (5) by fastening means such as bolts or spot welding, and thereby hold the windings by integrating both flanges (5) and holding cylinder (4). Make up frame (3).

Here, in this embodiment, the holding cylinder (4) is made of the same stainless steel material as the flange (5).
In addition, when fitting the winding part (2), the holding cylinder (4) is heated to expand the inner diameter by thermal expansion, so that the fitting on the outer circumference of the winding part (2) is smooth. And

Then, the fastening between the temporary winding frame (7) and both flanges (5) is released, and the temporary winding frame (7) is wound on the winding part (7) as shown in FIG. 2) Pull out from the inside in the axial direction. Then, the winding portion (2) in the winding holding frame (3) is impregnated with the impregnating material (6), and the superconducting magnet having the configuration shown in FIG.

Here, in this example, the temporary bobbin (7) is attached to the winding portion.
(2) When removing the temporary reel (7) from the inside, cool the temporary reel (7) to a low temperature from the inside using liquid nitrogen, and change the outer diameter of the temporary reel (7) to the winding part (2) due to the difference in heat shrinkage. ), Which is smaller than the inner diameter, so that it can be smoothly extracted from the winding part (2).

In the superconducting magnet of this example having the above structure,
Since there is no winding frame inside the winding part, exfoliation or cracking of the impregnating material does not occur between the winding part and the winding frame during excitation, unlike the conventional superconducting magnet, and it does not cause quenching. . Further, without using a special device like the above-mentioned prior art, by using a very general winding device / method applied to a superconducting magnet having an ordinary winding frame,
A solenoid-shaped winding part can be easily formed. Moreover, since the winding part is held from the upper and lower sides and the outer peripheral side by the winding holding frame in which the flanges at both ends and the holding cylinder on the outer peripheral side are integrated, the whole can be easily and firmly supported and at the time of excitation. It is possible to suppress the movement of the superconducting wire due to the electromagnetic force, and thereby to suppress the cracking of the impregnated material and suppress the occurrence of quench.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. Under the above configuration, a copper-stabilized NbTi superconducting wire with an outer diameter of 0.45 mm is wound 1400 times to form a solenoidal winding part with an inner diameter of 14 Omm, an outer diameter of 146 mm, and an axial length of 100 mm. A superconducting magnet was manufactured by forming a winding holding frame, extracting an inner temporary winding frame, and then impregnating it with an epoxy resin. Also, for comparison, the same winding part as above is formed on the outer circumference of the temporary winding frame between both flanges, and the winding part is impregnated with epoxy resin without forming a winding holding frame on the outer circumference side. We also prepared a conventional superconducting magnet. In addition,
The rated current value of these superconducting coils is 250A. Then, each of the above superconducting magnets was excited in a backup magnetic field, and the quench currents were compared and examined. The results are shown in [Table 1].

[0020]

[Table 1]

As shown in [Table 1], the superconducting magnet of the comparative example having the winding frame on the inner diameter side is repeated three times or less than the rating, but the superconducting magnet of this example is rated without quenching. It has been confirmed that the excellent effect of the present invention can be confirmed.

The above embodiment is an example of using a copper-stabilized NbTi superconducting wire, but the present invention is a copper-stabilized NbTi superconducting wire.
The present invention is not limited to superconducting wires, but can be applied to superconducting magnets using all kinds of superconducting wires.

In the above-mentioned embodiment, the temporary winding frame made of Al alloy is used, but this is an example of utilizing the difference in heat shrinkage rate during extraction, and for example, from the brittle surface, the winding is used. In the case of a superconducting magnet that uses Nb3Sn superconducting wire that needs to be subjected to a prescribed heat treatment afterwards, use heat-resistant stainless steel for the temporary reel, and perform heat treatment to secure the characteristics before removing the temporary reel. Give. Further, in this case, since the tension at the time of winding is released by the heat treatment, the temporary winding frame can be easily pulled out from the inside of the winding portion. In any case, the temporary reel can be pulled out more easily by applying a material having a small coefficient of friction such as Teflon to the outer peripheral surface of the temporary reel or winding a sheet made of the material in advance. it can.

Further, in the above-described embodiment, both flanges constituting the winding holding frame have an outer diameter substantially equal to the outer diameter of the winding portion, while the holding cylinder has the outer diameter of the winding portion. A flat ring-shaped protrusion having a substantially equal inner diameter, an inner length substantially equal to the axial length of the winding portion and both flanges, and projecting like a flange inward of one end was provided. I decided to
The present invention is not limited to this, and as long as it is possible to secure the connection and fixing of both flanges and the holding cylinder and the holding of the winding portion, for example, the holding cylinder has a flat annular protrusion at one end. Alternatively, the inner diameter may be slightly larger than the outer diameter of the winding portion to facilitate the fitting on the outer circumference of the winding portion. Further, not only fastening means such as bolts or spot welding but also seam welding or an adhesive may be used to integrally connect both flanges and the holding cylinder.

Further, since the winding portion holds the flanges on both ends and the holding cylinder on the outer peripheral side integrally from the upper and lower sides and the outer peripheral side by means of the winding holding frame, for example, superconducting wires are adjacent to each other between two winding layers. In the case of a superconducting magnet in which the winding is formed by closely winding each of the two superconducting wires in point contact with each other, the movement of the superconducting wire due to the electromagnetic force during excitation can be effectively controlled by the winding holding frame outside the winding. Since it is suppressed, the impregnating material can be omitted.

[0026]

As described above, in the superconducting magnet of the present invention, the winding frame on the inner diameter side of the winding portion of the superconducting wire is removed,
Assuming a structure that prevents the impregnating material from peeling or cracking between the winding wire and the winding frame during excitation, a solenoidal winding wire can be easily wound and formed without the need for a special device. Moreover, the winding portion can be stably held from the upper and lower sides and the outer peripheral side by the winding holding frame, so that the whole can be easily and firmly supported, and the movement of the superconducting wire due to the electromagnetic force at the time of excitation can be suppressed. Thus, cracking of the impregnated material can be suppressed, and the occurrence of quench can be suppressed more effectively.

[Brief description of the drawings]

FIG. 1 is a drawing showing a structure and a manufacturing procedure of an embodiment of a superconducting magnet according to the present invention, wherein (a) is a front sectional view showing a schematic structure, and (b) to (e) are its drawings. It is an explanatory sectional view of an example of a manufacturing procedure.

FIG. 2 is a schematic cross-sectional view of a conventional superconducting magnet having a winding frame inside a winding portion and an electromagnetic force acting on the winding portion.

FIG. 3 is an explanatory cross-sectional view of a conventional superconducting magnet for removing a winding frame inside a winding portion.

FIG. 4 is an explanatory cross-sectional view of a conventional superconducting magnet having no winding frame inside the winding portion.

[Explanation of symbols]

(1)-Superconducting wire, (2)-Winding part, (3)-Winding holding frame,
(4) --Holding cylinder, (5) --Flange (6) --Impregnated material, (7)
--Temporary reel.

Claims (5)

[Claims] 1. A superconducting wire is solenoidally wound around the outer circumference of a cylindrical temporary winding frame having separable flat annular flanges attached to both ends thereof, and then the temporary winding frame inside is obtained. And a winding holding frame formed by integrally connecting a winding portion of the superconducting wire, flanges at both ends of the winding portion separated from the temporary winding frame, and a holding cylinder fitted on the outer periphery of the winding portion. A superconducting magnet characterized by comprising: 2. A first step of forming a solenoidal winding part by winding multiple layers of superconducting wires on the outer periphery of a cylindrical temporary winding frame having separable flat annular flanges attached to the outer periphery of both ends. And a second step of fitting a holding cylinder having a length covering the entire axial length of the winding part on the outer circumference of the winding part, and connecting both ends of the holding cylinder to the outer peripheral parts of the flanges. A third step of forming a winding holding frame in which the holding cylinder and both flanges are integrated, and a fourth step of separating the temporary winding frame and both flanges and axially extracting the temporary winding frame from the inside of the winding portion A method of manufacturing a superconducting magnet, comprising: 3. The method for manufacturing a superconducting magnet according to claim 2, wherein, in the second step, the holding cylinder is fitted to the outer circumference of the winding portion in a state where the holding cylinder is heated to have an inner diameter enlarged by thermal expansion. 4. The method for producing a superconducting magnet according to claim 2, wherein, in the fourth step, the temporary winding frame is cooled and the outer diameter is reduced by heat shrinkage, and the temporary winding frame is withdrawn from the winding portion. 5. The method for manufacturing a superconducting magnet according to claim 2, wherein a material having a small friction coefficient is applied in advance or a sheet made of the material is wound around the outer peripheral surface of the temporary winding frame.