JPH0374010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a superconducting cylindrical coil, and particularly to a method suitable for manufacturing a large cylindrical coil.

[Prior art and its problems]

Generally, superconducting cylindrical coils are formed by tightly wrapping an insulated conductor in a spiral around the outer circumference of a cylindrical winding frame, or by tightly winding an insulated conductor around the inner circumference of a cylindrical winding frame. .

In this case, the insulated conductor is, for example, a rectangular superconducting wire 1 and a prepreg tape 2 as shown in FIG.
It is wound and insulated. The superconducting wire 1 has, for example, an Nb-Ti superconducting wire 1a inside, and a stabilizing material 1b made of high purity aluminum of 99.99% or more is provided around the superconducting wire 1a. Further, the prepreg tape 2 is made by impregnating a woven fabric made of glass fiber or the like with a thermosetting resin such as an epoxy resin in liquid form, and then bringing it into a semi-cured state (B stage).

Such an insulated conductor 3 is wound to form a cylindrical coil, and then heated to a temperature and time necessary for curing the prepreg tape to cause a curing reaction.
Adjacent insulated conductors are integrated with each other to form a finished product.

However, when the insulated conductor is spirally wound, the insulated conductor may meander or return due to its springiness, resulting in uneven gaps between the insulated conductors. For this reason, conventionally, when the prepreg tape is cured by heating (150 to 160° C.) in the final step, pressure is applied in the axial direction so that the coil length is within a predetermined dimension to eliminate the gap. However, with this method, when the coil length is long and the number of turns in the axial direction is large, the axial pressing force gradually increases as the distance from the end pressurizing part increases due to the frictional resistance between the insulated conductor and the winding frame. This makes it difficult to make the axial conductor density uniform.

For this reason, the cylindrical coil manufactured by the conventional method has a problem in that a homogeneous magnetic field cannot be obtained inside the cylindrical coil. In addition, this type of cylindrical coil is used when inserted into an external magnetic path member so that the geometric centers coincide, but if the conductor density is uneven as described above, the cylindrical coil Since there is a misalignment between the electromagnetic center and the geometric center, there is a problem in that when the coil is excited, a strong electromagnetic force acts on the coil and destroys the coil.

[Means for solving problems and their effects]

In order to solve the above-mentioned problems of the prior art, the present invention provides an insulated conductor made by wrapping a prepreg tape around a superconducting wire to insulate it, and tightly winding it in a spiral shape on the inner or outer circumferential surface of a winding frame. In a method for manufacturing a superconducting cylindrical coil in which a cylindrical coil is formed and then the prepreg tape is cured by heating, the coil is heated at a temperature sufficiently lower than the curing temperature of the prepreg tape, and The method is characterized in that the resin of the prepreg tape is heated to a temperature at which it softens from a semi-hardened state and flows, and is pressurized in the axial direction to adjust the conductor arrangement within the coil.

In this way, the conductor arrangement is corrected while the resin of the prepreg tape is soft.
There is little frictional resistance between the winding frame and the insulated conductor, and the conductor density in the axial direction can be easily made uniform.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1 FIG. 1 shows a cross section of a superconducting cylindrical coil manufactured by the method of the present invention. This cylindrical coil is, for example, a large coil with a diameter of about 3 m and an axial length of about 5 m. In the figure, 4 is a cylindrical winding frame;
is an insulated conductor as shown in FIG. 4 which is wound around the inner peripheral surface of the winding frame 4 to form a coil. Note that the inner peripheral surface of the winding frame 4 is lined with an insulating material 5 in advance. 6a and 6b are insulating rings, 7a and 7b are holding rings, and 8 is a bolt nut for tightening.

When manufacturing such a cylindrical coil, first, the holding ring 7a is fixed to the lower end of the winding frame 4, and the insulating ring 6a is installed. In this state, the insulated conductor 3 is wound around the inner peripheral surface of the winding frame 4 to form the coil 9. At this stage, uneven gaps are created between the insulated conductors 3 due to meandering of the insulated conductors 3 or return due to their spring properties.

In order to eliminate this gap and make the conductor density uniform in the axial direction, next, pressure is applied in the axial direction while heating at a temperature sufficiently lower than the curing temperature. The heating temperature at this time is the temperature at which the resin of the prepreg tape softens from a semi-cured state and can easily flow under pressure, and the performance of the prepreg tape, such as adhesive strength, will be affected when the prepreg tape is heated and cured in the subsequent process. Keep the temperature at a level that does not cause any problems.

Figure 3 shows 100 turns, axial pressure 1.5
This shows the relationship between coil temperature and displacement when Kg/mm ² . At approximately 50℃, the resin of the prepreg tape softens and a displacement close to the maximum can be obtained. The prepreg tape used was epoxy resin CY175 (CIBA-
5 parts of monomethylamine complex (BF ₃ -ME) was mixed into 100 parts of GIGEY Co., Ltd. to form a varnish, which was impregnated into a glass tape and semi-cured. The curing temperature of this prepreg tape is 150℃
However, if heated at a temperature below 60°C, there is no risk of performance deterioration. Therefore, heating for adjusting the conductor arrangement is preferably performed at a temperature of about 50 to 60°C.

Further, if the pressing force in the axial direction is about 1.5 Kg/mm ² , the superconducting wire and the insulating layer will not be damaged. This axial pressure is applied to the insulated conductor 3 due to the pressure.
Even if the coil is displaced, until the coil length reaches the specified dimension,
It is best to use a hydraulic device to maintain almost constant pressure. Furthermore, when applying pressure in the axial direction, it is preferable to apply a force in the radial direction to press the coil 9 against the inner surface of the winding frame 4 in order to improve the adhesion between the coil 9 and the winding frame 4. .

After heating at the above softening temperature and axial pressure are completed, the insulating ring 6b is installed on the upper end of the winding frame 4, the presser ring 7b is fixed, and the whole is heated at the curing temperature (150°C, 16 hours) to cure the prepreg tape insulation layer. This completes the superconducting cylindrical coil.

Example 2 FIG. 2 shows another example of a superconducting cylindrical coil manufactured by the method of the present invention. Components corresponding to those in FIG. 1 are given the same reference numerals.

In this example, when manufacturing a cylindrical coil,
The coil is divided into four blocks 9a to 9d, and the first
Blocks are formed in order starting from block 9a. First, reel frame 4
The insulated conductor 3 is wound inside to form the first block 9a of the coil. Thereafter, conductor arrangement is adjusted by heating at a low temperature that softens the resin of the prepreg tape and applying pressure in the axial direction. The conditions at this time are the same as in Example 1. After this is completed, the temperature is returned to room temperature, the pressure is removed, and the formation of the first block 9a is completed.

Next, an insulated conductor is connected to the winding end of the first block 9a and wound into the winding frame 4 to form the second block 9b. After that, the first block 9a
Heating and pressurizing are performed in the same manner as described above to complete the formation of the second block 9b. At this time, it is preferable that the first block 9a is not heated. Thereafter, similar operations are repeated to form up to the fourth block 9d.

When heating and pressurizing each block at the softening temperature in this way, each block has a small number of turns and the frictional resistance with the winding frame 4 is small, so the axial pressing force is compared to that of the insulated conductor 3 of each turn. As a result, the axial density of the insulated conductor 3 within the coil 9 can be made more uniform.

Note that the steps of attaching the presser rings 7a, 7b and the insulating rings 6a, 6b, and finally heating the whole at the curing temperature of the prepreg tape are the same as in Example 1.

The above are examples of the present invention, and the present invention is not limited thereto. For example, in Example 2,
Although the coil is divided into four blocks, the number of blocks may be determined as appropriate depending on the length of the coil and the number of turns. Further, in each of the above embodiments, the case where the insulated conductor is wound around the inner peripheral surface of the cylindrical winding frame is shown, but the present invention is similarly applicable to the case where the insulated conductor is wound around the outer peripheral surface of the winding frame.

〔Effect of the invention〕

As explained above, according to the present invention, heating is performed at a temperature at which the prepreg tape becomes soft and pressure is applied in the axial direction before heating and hardening the prepreg tape. Due to the softening and flow of the resin, the frictional resistance between the insulated conductor and the winding frame becomes smaller, and the axial pressing force is applied evenly to both the ends and the middle of the coil, resulting in a cylindrical shape. This has the advantage that the conductor density in the axial direction of the coil can be made uniform, and a homogeneous magnetic field can be obtained. Furthermore, if the conductor density in the axial direction becomes uniform, the coincidence between the geometric center and the electromagnetic center of the cylindrical coil increases, so even if the cylindrical coil is inserted into an external magnetic path member, The electromagnetic force acting on it can be small, reducing the risk of destruction. At the same time, it is also possible to reduce the strength of the coil support member, so less heat is transmitted from the outside through the support member, and the amount of refrigerant (liquefied helium, etc.) used can be reduced.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are cross-sectional views showing superconducting cylindrical coils manufactured by the method of the present invention, respectively;
Fig. 3 is a graph showing the relationship between temperature and displacement when a coil insulated with prepreg tape is pressurized in the axial direction, and Fig. 4 is a perspective view showing an example of an insulated conductor for forming a superconducting cylindrical coil. . 1 - superconducting wire, 2 - prepreg tape, 3 - insulated conductor, 4 - winding frame, 9 - coil.

Claims (1)

[Claims] 1. An insulated conductor made by wrapping a prepreg tape around a superconducting wire to insulate it is tightly wound spirally around the inner or outer circumferential surface of a winding frame to form a cylindrical coil, and then heated to insulate the prepreg tape. In the method for manufacturing a superconducting cylindrical coil to be cured, before performing the heat curing, the coil is heated to a temperature sufficiently lower than the curing temperature of the prepreg tape and at a temperature at which the resin of the prepreg tape softens from a semi-cured state and flows. A method for manufacturing a superconducting cylindrical coil, which comprises heating the coil and applying pressure in the axial direction to adjust the conductor arrangement within the coil.