JPH02199806A - Superconducting coil and prepreg semicured tape - Google Patents

Abstract

PURPOSE:To prevent a cracking of an impregnated resin from being produced by a method wherein a fiberlike filler is mixed with a resin layer between coil conductors. CONSTITUTION:In a superconducting coil 1, a superconducting wire 2 constituted of an NbTi superconducting filament and of stabilized copper is wound in a racetrack shape, and a prepreg semicured tape 5 is wound in one turn at a half-hooked manner between individual layers and on the surface of the coil. This superconducting coil 1 is put in a molding metal mold; while it is being heated, it is molded by executing a three-dimensional pressurization operation. By this pressurization molding operation, a fiberlike filler 6 is extruded, from the prepreg semicured tape 5 wound between coil conductors and on the surface of the coil, between the coil conductors and on the surface of the coil in a state that it is mixed with an epoxy resin 7, and through thermosetting a resin layer 8 is formed. The prepreg semicured tape 5 uses a polyimide film 9 as a base material; both faces are coated with the glass-fiberlike filler 6 to which the epoxy resin 7 mixed with a hardening agent and a solvent has been added; this assembly is heated; the epoxy resin is matured; a resin layer 10 is formed. Thereby, it is possible to prevent a crack of the impregnated resin layer from being produced and to obtain the superconducting coil whose reliability is high and whose current density is high.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a superconducting coil impregnated with a synthetic resin, and particularly to a superconducting coil that prevents cracks from forming in the impregnated resin.

[Conventional technology]

Fig. 21iii is a perspective view of a superconducting coil for a magnetically levitated vehicle, and Fig. 3 is a sectional view taken along the line ■-■ in Fig. 2.

The conventional resin-impregnated superconducting coil 1 shown in FIG.
As shown in Publication No. 3904, between the coil layers,
Then, a glass tape was wrapped around the coil surface, a synthetic resin was vacuum injected from the outside of the coil, and the resin was heated and cured under pressure to form the coil. The coil manufactured in this way has a thick layer of only synthetic resin between the coil conductors 2, as shown in Figure 3.

Cracks 4 occur in the resin layer 3 due to thermal contraction force when cooling to an extremely low temperature and electromagnetic force due to excitation of the superconducting coil, and the superconducting coil has the drawback of causing quenching.

It is known that it is effective to mix the coil into the impregnated resin to prevent the occurrence of racking, but in coils where the conductor is tightly wound, such as superconducting coils, the filler accumulates on the surface of the coil and the conductor Do not intrude into the space. Therefore, cracks were likely to occur in the resin layer between the coil conductors.

The above is a case where resin is impregnated from the coil surface to the inside of the coil by vacuum impregnation, and a resin-impregnated prepreg semicure tape is wound around the surface of the superconducting wire, and this is wound many times to form a coil.

There is a method of impregnating the inside of the coil with resin extruded from prepreg semi-cured tape by applying heat and pressure. The coil manufactured by this method also has the disadvantage that the resin layer between the coil conductors is thick, as in the case of vacuum impregnation, and cracks are likely to occur in the impregnated resin as described above.

[Problem to be solved by the invention]

The above conventional technology does not give sufficient consideration to the occurrence of cracks in the interconductor resin layer of the superconducting coil, and cracks occur in the impregnated resin layer due to electromagnetic stress and thermal shrinkage stress applied to the superconducting coil. There was a problem that caused quenching.

An object of the present invention is to provide a highly reliable superconducting coil with high current density that prevents cracks in the impregnated resin layer of a superconducting coil and does not cause quenching.

[Means to solve the problem]

In order to achieve the above object, the present invention manufactures a prepreg semi-cured tape in which a fibrous filler is mixed into a resin, and uses this tape between the layers of a superconducting coil, on the surface, or on the surface of a superconducting coil.
The conductor is wound, heated, and pressurized to impregnate the space between the coil conductors and the coil surface with a resin mixed with a fibrous filler that is extruded from the prepreg semi-cured tape.

[Effect]

The prepreg semi-cured cheese of the present invention allows fibrous filler to be impregnated between coil conductors.

In the superconducting coil using the tape of the present invention, the fibrous filler is entangled and dispersed in the resin layer between the conductors, so the mechanical strength of the resin layer is enhanced. Thereby, the interconductor resin layer of the superconducting coil can withstand thermal shrinkage stress and electromagnetic stress that occur when the superconducting coil is cooled and energized once, and can prevent cracks from occurring.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG. 1 and FIGS. 4 to 6.

In Fig. 1, a superconducting coil 1 consists of a superconducting wire 2 with a diameter of 1.5 m made of NbTi superconducting filament and stabilizing steel, which is wound in a racetrack shape with more than 1,000 turns. The prepreg semi-cured tape 5 of the present invention is wrapped once in half. This superconducting coil 1 is placed in a mold, and is molded by applying three-dimensional pressure from three directions using a press while heating. By this pressure forming, the coil conductor is formed with the fibrous filler 6 mixed into the epoxy resin 7 from the prepreg semi-cured tape 5 wound between the coil conductors and on the coil surface.
A resin layer 8 is formed by extruding the resin layer 8 between the layers and onto the surface of the coil and heating and curing the resin layer 8 . Since the fibrous filler and resin are intertwined, the mechanical strength of this resin layer is approximately doubled compared to the conventional method.

FIG. 4 shows a cross section of the prepreg semi-cure tape 5 of the present invention.
m-thick polyimide film 9, with 10 μm on both sides.
A fibrous filler 6 obtained by cutting a glass fiber with a diameter of about 1 m into a length of about 1 m is mixed with an epoxy resin 7 mixed with a hardening agent and a solvent.
The epoxy resin is coated with 20% (wt%) mixed therein and heated at 90 to 100° C. for about an hour to age the epoxy resin, thereby providing a resin layer 10 having a thickness of 50 μm and containing the fibrous filler 6.

In this example, polyimide film, which has good electrical insulation and high mechanical strength at extremely low temperatures, was used as the base material, but other synthetic films such as polyvinyl formal, polyester, polyamide, and aramid also have the same properties as polyimide film. Therefore, similar effects can be obtained. If emphasis is placed on preventing the occurrence of cracks in the impregnated resin, fiber cloth such as glass cloth is also suitable as the base material. In addition, synthetic fiber cloths such as polyimide, polyvinyl formal, polyester, polyamide, and aramid, which have high mechanical strength at extremely low temperatures, are also suitable.9 They are generally used to improve the mechanical strength of the resin layer between the coil conductors. Powder fillers are ineffective, while fibrous fillers are highly effective. As a fibrous filler to be impregnated into a synthetic resin, a material that has good adhesion with synthetic resins such as epoxy resin and has high mechanical strength at extremely low temperatures is suitable.6 Glass fiber fillers have good adhesion with synthetic resins. This is preferable because it improves the mechanical strength of the resin layer containing it. In addition, the aforementioned synthetic fibers are suitable because they have good adhesion to synthetic resins and have high mechanical strength at extremely low temperatures.

The impregnating resin is preferably an epoxy resin or a polyester resin, which has good mechanical strength and electrical properties, has a large adhesive force, and has a low heat shrinkage rate compared to other resins.

FIG. 5 shows a modification of the present invention, in which prepreg semi-cured chives 5 containing fibrous filler shown in FIG. A coil is formed, and heated and three-dimensionally pressurized to extrude and impregnate the fibrous filler-containing resin between the coil conductors and onto the coil surface. As a result, the resin layer 8
The mechanical strength of the coil is approximately twice that of the conventional one, and the insulation between the coil conductors can be improved.

Figure 6 compares the effects of the present invention with the conventional example. The vertical axis shows the coil current density when the conventional example is set to 1.0, and the horizontal axis shows the magnetic field when the conventional example is set to 1.0. The relationship between the coil current density and the magnetic field was shown.

That is, the characteristic P of the superconducting coil of this example is as follows.

The coil current density is greatly superior to the characteristic Q of the conventional example, and the characteristic is close to the characteristic R of a short wire. That is, while the conventional superconducting coil quenches when the coil current density is 1 bar unit (P, U), the superconducting coil of this embodiment causes quenching when the coil current density reaches 1.2 bar units.

〔Effect of the invention〕

According to the present invention, fibrous filler is mixed into the inside of the superconducting coil mounted on the magnetically levitated vehicle and into the resin layer on the surface to make it difficult for cracks to occur. Furthermore, it is possible to provide a superconducting coil for a magnetically levitated vehicle that can withstand electromagnetic force, has a high current density, and is highly reliable.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a superconducting coil according to an embodiment of the present invention;
The figure is a perspective view of a conventional superconducting coil for a magnetic levitation vehicle, FIG. 3 is a sectional view of a conventional superconducting coil for a magnetic levitation vehicle, and FIG. 4 is a sectional view of a prepreg semicured tape used in the superconducting coil of the present invention. FIG. 5 is a sectional view of a superconducting coil according to another embodiment of the present invention, and FIG. 6 is a characteristic diagram showing the relationship between coil current density and magnetic field of one embodiment of the superconducting coil of the present invention and a conventional example. DESCRIPTION OF SYMBOLS 1... Superconducting coil, 2... Superconducting wire, 5... Prepreg semi-cured tape, 6... Fibrous filler,
1st degree! Kuchicha No. 3 Prisoner No. 41iJ Cha 5

Claims (5)

[Claims] 1. A tightly wound superconducting coil made by winding a superconducting wire many times and impregnating it with synthetic resin, which is characterized by having a fibrous filler mixed into the resin layer between the coil conductors. 2. The superconducting coil according to claim 1, wherein the prepreg semi-cure tape containing the fibrous filler is wound between the layers of the superconducting coil, and the coil is formed by heating and pressurizing. 3. A prepreg semi-cure tape containing a fibrous filler is wound on the surface of the superconducting wire, the superconducting wire is wound many times to form the conductive coil, and the coil is formed by heating and pressurizing. A superconducting coil according to claim 1. 4. A prepreg semi-cure tape according to claim 2 or 3, characterized in that a synthetic film or fiber cloth is used as a base material and is coated or impregnated with a synthetic resin mixed with a fibrous filler. 5. In claim 4, the tape base material is a synthetic film of polyimide, polyvinyl formal, polyester, polyamide, or aramid, or synthetic fiber cloth, or glass fiber cloth, and the fibrous filler is made of a material of the tape base material. A prepreg semi-cure tape characterized in that it uses a filler that is , and an epoxy resin or a polyester resin is used as the synthetic resin.