JPH11251133A - Manufacture of superconducting coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting coil which is stable for cooling and electromagnetic force of it while easy to manufacture. SOLUTION: A superconducting body is wound, by specified turns, outside a cylindrical bobbin 1 which is possible to be divided into plural sections in radial direction to form a coil 2, then, a reinforcing cylinder 3, wherein, of a material whose thermal expansion factor is equal to or higher than the coil 2, outside diameter is worked to a dimension slightly larger than the outside diameter of the coil 2, is coaxially provided outside the coil 2, and the gaps are filled with a resin of normal-temperature setting type for integral for impregnation and setting, and then a bobbin 1 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a superconducting coil having no support inside a coil used for a superconducting magnet for detecting a particle beam, a superconducting magnet for a crystal pulling apparatus, and the like.

[0002]

2. Description of the Related Art In recent years, superconducting electromagnets have been increasingly used in various fields. In particular, it has come to be used in a way that makes full use of the features of extremely high superconducting stability and energy saving, and further reduction in weight and size is required for various applications.

For these purposes, a structure without a support inside the coil, that is, a so-called inner-wound coil has been required for the reason that aluminum is frequently used as a material of the superconducting coil.
That is, since a coil is made of aluminum material, a reinforcing cylinder is provided outside the coil as an electromagnetic force support, and the coil is cooled by heat conduction between the reinforcing cylinder and the coil.

[0004] As a method of cooling the reinforcing cylinder, there are forced indirect cooling in which a cooling pipe is installed on the surface of the reinforcing cylinder or static indirect cooling in which a reservoir tank is installed at one end of the reinforcing cylinder. It is necessary that the adhesion to the reinforcing cylinder is strong and that no peeling occurs during production or operation.

Conventionally, as a method for manufacturing this type of coil, as shown in FIG. 5, a superconducting coil 1 formed by winding a superconducting conductor and a reinforcing cylinder 2 are formed by adjusting the inner diameter of the reinforcing cylinder to the size of the superconducting coil. There is a method in which the reinforcing cylinder and the coil are integrated by a so-called shrink-fitting method in which the reinforcing cylinder and the coil are processed so as to be smaller than the outer diameter and a temperature difference is generated between the reinforcing cylinder and the coil.

[0006] In the indirect cooling usually employed in this type of coil, since the superconducting coil is placed in a vacuum,
It is desirable that the interface between the coil and the reinforcing cylinder be bonded with a resin or the like, and a method of vacuum impregnation with an epoxy resin or the like is used for the fitting surface. That is, as shown in FIG. 5, the superconducting coil and the reinforcing cylinder are coaxially arranged with a certain finite gap. Then, the resin in this gap,
Alternatively, there is a method in which the impregnated resin 4 is injected and filled, and the resin is heated and hardened to integrally fix the superconducting coil and the reinforcing cylinder 2 to form an inner winding coil.

However, when the superconducting coil is manufactured by such a method, the resin layer has a large dimension in the thickness direction between the reinforcing cylinder and the superconducting coil, and when the resin layer is strongly subjected to a stress caused by a cooling / heating cycle or an electromagnetic force, Cracking of itself or separation at the interface is likely to occur. Further, the heat transfer between the coil and the reinforcing cylinder decreases in proportion to the thickness of the resin layer.

On the other hand, there is a method in which the fitting dimension is set to the tight fitting side. In this case, when the temperature of the reinforcing cylinder and that of the coil become the same, prestress is generated from the reinforcing cylinder to the coil, and The force for fixing the superconducting conductor becomes stronger.

However, in the step of impregnating the epoxy resin, the epoxy resin is usually heated to about 120 ° C. in order to accelerate the curing of the epoxy. At this point, the superconducting coil wound around the aluminum reinforcing cylinder and the winding jig is tensioned. A gap is formed again between the two. Therefore, in the process of curing the resin impregnated in the gap, since the curing shrinkage due to the chemical reaction usually generates about 2%, there is a possibility that the adhesive strength between the completed coil and the reinforcing cylinder is reduced.

[0010] There is also a method of impregnating a room-temperature-curable epoxy resin in an interference-fit state, but impregnation of the resin is difficult due to high pressure between the coil and the reinforcing cylinder, and the impregnation step is completed in a short time. Otherwise, the curing of the resin will proceed and impregnation failure may occur, and when shear stress occurs due to the difference in heat shrinkage between the reinforcing cylinder and the winding jig in the longitudinal direction of the solenoid coil, the adhesive strength is insufficient. Crack.

[0011]

As described above, in the conventional method of manufacturing a superconducting coil, it is necessary to heat the gap between the superconducting coil and the reinforcing cylinder to about 120 ° C. and bond the resin to the resin when the inner coil is manufactured. It has been difficult to minimize the possibility of cracking or peeling during the cooling operation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a superconducting coil which has good stability for cooling and electromagnetic force of the superconducting coil and is easy to manufacture, in order to solve the above problems.

[0013]

According to a first aspect of the present invention, a coil is formed by winding a superconducting conductor a predetermined number of times around a cylindrical bobbin which can be divided into a plurality of pieces in a radial direction, and thereafter forming the coil. A coaxial reinforcing cylinder made of a material whose outer diameter is slightly larger than the outer diameter of the coil and whose coefficient of thermal expansion is equal to or greater than that of the coil is coaxially provided on the outside of the coil. After filling and integrally impregnating and curing,
The bobbin is removed.

According to a second aspect of the present invention, a coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical bobbin which can be divided into a plurality of pieces in the radial direction, and thereafter, an outer diameter is formed outside the coil. When a reinforcing cylinder made of a material having a slightly larger outer diameter than the coil and having a thermal expansion coefficient equal to or larger than that of the coil is fitted at room temperature, the gap between the coil and the reinforcing cylinder is filled. The resin is filled in while sequentially applying the resin, and after the resin filled in the gap is cured, the reel is removed.

According to a third aspect of the present invention, a coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical bobbin that can be divided into a plurality of pieces in the radial direction, and thereafter, an outer diameter is formed outside the coil. A reinforcing cylinder made of a material having a size slightly larger than the outer diameter of the coil and having a thermal expansion coefficient equal to or greater than that of the coil is fitted at room temperature to seal the gap between the coil and the reinforcing cylinder and to apply vacuum pressure. In this state, a cold-setting impregnated resin is introduced into the gap, and after the resin filled in the gap is cured, the bobbin is removed.

According to a fourth aspect of the present invention, a coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical winding frame that can be divided into a plurality of pieces in the radial direction, and thereafter, an outer diameter is formed outside the coil. A reinforcing cylinder made of a material having a size slightly larger than the outer diameter of the coil and having a thermal expansion coefficient equal to or greater than that of the coil is previously fitted at normal temperature and normal pressure to partially seal a gap between the coil and the reinforcing cylinder. In this state, a cold-setting impregnated resin is injected into the gap under pressure, and after the resin filled in the gap is cured, the reel is removed.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a superconducting coil according to any one of the first to fourth aspects, wherein a fine filler is mixed as a cold-setting resin. Use a highly viscous epoxy resin.

In the method for manufacturing a superconducting coil according to the present invention, the gap between the superconducting coil wound on the bobbin and the reinforcing cylinder disposed on the outer periphery of the coil is provided. Since there is no heating for filling the resin, there is no stress generated in the resin layer due to the difference in thermal expansion between the winding frame and the reinforcing cylinder.Therefore, the heat stress before cooling to cryogenic temperature for superconducting operation is also reduced. Can be reduced by about 40% as compared with the case of impregnation.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing, as a first embodiment for explaining a method of manufacturing a superconducting coil according to the present invention, a state in which fitting has been completed in a manufacturing process of an inner winding type superconducting coil.

In FIG. 1, a bobbin 1 disposed inside as a jig is divided into a plurality of pieces by a material such as iron (mild steel) so that it can be disassembled to the inner diameter side. A superconducting conductor is wound a predetermined number of times after applying a release material to the outer peripheral surface of the winding frame 1 to form a superconducting coil 2.

The outer diameter of the superconducting coil 2 is shown in FIG.
As shown in (a), the reinforcing cylinder 3 is coaxially arranged in the next step and is fitted with a gap of about 1 mm. The reinforcing cylinder 3 is usually made of aluminum, and is provided with a ground insulation having good permeability of a resin including a glass tape or the like in a gap between the superconducting coil and the epoxy resin, as shown in FIG. The fitting is performed while applying.

The epoxy resin 4 is disclosed in Japanese Patent Application No. Hei 7-224.
No. 231, a filler called a resin coat, which is made of a high-viscosity room-temperature-curable resin, is used.

Further, in order to prevent air from being caught in the epoxy resin in the space between the coil 2 and the reinforcing cylinder 3, the space is always filled with the resin during the fitting operation.

The superconducting coil that has been fitted is sealed in the direction of gravity until the resin hardens (usually 10 hours or more). A superconducting coil in a state of being in contact with and fixed is manufactured.

In such a method for manufacturing a superconducting coil, the bobbin 1 is made of a material such as iron so that it can be disassembled.
The superconducting coil 2 in which the superconducting conductor is wound a predetermined number of times around its outer periphery and the reinforcing cylinder 3 fitted and coaxially arranged with a minute gap are filled with resin and cured at room temperature. .

Therefore, the epoxy resin is cured at normal temperature and the superconducting coil and the reinforcing cylinder are impregnated and fixed.
There is no occurrence of shear stress due to mutual displacement after curing of the resin due to the difference in thermal expansion between the resin and the reinforcing cylinder 3.

Next, while these members are cooled to an extremely low temperature, which is the operating temperature of the superconducting coil, a stress is applied to the cured resin due to a difference in thermal contraction between the superconducting coil and the reinforcing cylinder. When the shear bond strength of this resin layer is evaluated by an experiment, the larger the thickness of the resin layer, the stronger it tends to be.
To obtain the required 5MPa or more under general design conditions,
We are satisfied with 0.5 mm or more.

On the other hand, since the heat transfer from the coil to the reinforcing cylinder decreases in proportion to the thickness of the resin layer, the thickness of the resin layer is desirably as small as the adhesive force allows, for example, about 1 m in diameter. For the coil, about 1 mm is optimal considering the work accuracy of fitting.

A glass tape is provided on the outer periphery of the superconducting coil, and a sufficient ratio of filler is mixed with the epoxy resin injected into a small gap.
As described in the specification of Japanese Patent No. 24231, the difference in heat shrinkage from the coil is small, and the resin itself is a reinforced plastic composition that is less likely to crack or peel.

According to the method of manufacturing a superconducting coil as described in the first embodiment, the superconducting coil 2 and the reinforcing cylinder 3
This means that the stress acting between the superconducting coil and the reinforcing cylinder in a room temperature or low temperature region can be reduced by about 40% as compared with the impregnation method using a thermosetting resin. In addition, since the resin layer has almost no void due to the curing shrinkage of the resin, a good adhesion state can be maintained, and the superconducting coil has good heat transfer with the reinforcing cylinder and is sufficiently cooled. Therefore, the superconducting coil can be operated with good stability, and a compact superconducting electromagnet system having good characteristics can be constructed. In addition, this manufacturing method does not require equipment such as a vacuum impregnation tank, and can easily integrate the superconducting coil and the reinforcing cylinder.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view showing a state in which fitting has been completed in the manufacturing process of the inner winding type superconducting coil, and the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only mentioned.

In the first embodiment, the resin is injected while being applied when the reinforcing cylinder 3 and the superconducting coil 2 are fitted. However, in the second embodiment, as shown in FIG. Both are arranged coaxially in advance, the resin storage tank 6 prepared in advance is connected to the lower part of the reinforcing cylinder 3, and the resin is injected under pressure from the resin storage tank 6 into the gap between the superconducting coil 2 and the reinforcing cylinder 3, Thereafter, it is cured at room temperature.

In the method of manufacturing the superconducting coil, the same operation and effect as those of the first embodiment can be obtained. Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a cross-sectional view showing a state in which fitting has been completed in the manufacturing process of the inner winding type superconducting coil. The same parts as those in FIG. Only the differences will be described.

In the third embodiment, as shown in FIG. 4, the superconducting coil 2 and the reinforcing cylinder 3 are arranged coaxially in advance, and the upper part of the gap existing between the superconducting coil 2 and the reinforcing cylinder 3 is formed. And the lower part is sealed with a vacuum sealing material 7 to a vacuum pressure, and in this state, the resin is sucked and injected into the gap from the lower part of the reinforcing disk 3 from the resin storage tank 6 placed outside (atmospheric pressure). It is made to cure at room temperature.

In the method of manufacturing a superconducting coil, the same operation and effect as those of the first embodiment can be obtained. In the first to third embodiments, the material of the reinforcing cylinder is aluminum. However, since the construction method does not depend on the difference in the coefficient of thermal expansion from the material of the bobbin, the same applies even when stainless steel or copper is used. According to the principle described above, the manufacturing method according to the present invention can be applied, and the same function and effect can be obtained.

[0037]

As described above, according to the present invention, in the indirectly cooled inner winding coil which needs good heat transfer characteristics, the superconducting coil has good cooling and current conduction stability against electromagnetic force, and the manufacturing efficiency is improved. An easy manufacturing method of a superconducting coil can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a stage after a resin fitting step of an inner winding superconducting coil in a first embodiment of the present invention.

2 (a) and 2 (b) show the same embodiment as FIG.
Sectional drawing for demonstrating the earlier manufacturing process.

FIG. 3 is a partial cross-sectional view for explaining a method for manufacturing a superconducting coil according to a second embodiment of the present invention.

FIG. 4 is a partial cross-sectional view for explaining a method for manufacturing a superconducting coil according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view for explaining a conventional method for manufacturing a superconducting coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reel 2 ... Coil 3 ... Reinforcement cylinder 4 ... Epoxy resin 5 ... Impregnation tank 6 ... Resin storage tank 7 ... Vacuum sealing material

Claims (5)

[Claims] 1. A coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical bobbin that can be divided into a plurality of pieces in the radial direction, and thereafter, the outside diameter is outside the coil outside the outside diameter of the coil. A coaxial reinforcing cylinder made of a material that is slightly larger in size and has a thermal expansion coefficient equal to or greater than that of the coil,
A method for manufacturing a superconducting coil, characterized in that the gap is filled with a room-temperature-curable resin, which is impregnated and cured integrally, and then the winding frame is removed. 2. A coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical winding frame that can be divided into a plurality of pieces in the radial direction, and thereafter, the outside diameter is outside the coil outside the coil. When a reinforcing cylinder made of a material having a slightly larger size and a thermal expansion coefficient equal to or greater than that of the coil is fitted at room temperature, the resin is successively applied so as to fill the gap between the coil and the reinforcing cylinder. And removing the bobbin after the resin filled in the gap is cured. 3. A coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical bobbin which can be divided into a plurality of pieces in the radial direction, and thereafter, the outside diameter is outside the coil by the outside diameter of the coil. A reinforcing cylinder made of a material having a slightly larger size and having a thermal expansion coefficient equal to or greater than that of the coil is fitted at room temperature, and the gap between the coil and the reinforcing cylinder is sealed and a vacuum pressure is applied. A method for manufacturing a superconducting coil, comprising: introducing a cold-setting impregnated resin, and curing the resin filled in the gap, and then removing the winding frame. 4. A coil is formed by winding a superconducting conductor a predetermined number of times outside a cylindrical bobbin which can be divided into a plurality of pieces in the radial direction, and thereafter the outside diameter of the coil is outside the outside diameter of the coil. A reinforcing cylinder made of a material having a slightly larger size and a thermal expansion coefficient equal to or greater than that of the coil is fitted at room temperature and normal pressure in advance, and a part of the gap between the coil and the reinforcing cylinder is sealed, and the gap is inserted into the gap. A method of manufacturing a superconducting coil, comprising: injecting a cold-setting type impregnated resin under pressure, and curing the resin filled in the gap, and then removing the bobbin. 5. The method of manufacturing a superconducting coil according to claim 1, wherein an epoxy resin mixed with a fine filler and having a high viscosity is used as the room-temperature-curable resin. Method.