JPH05299235A - Helical coil and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To enable the large helical coil in high quality to be manufactured by a method wherein the coil, upper and lower press cylinders are couple-part structured having powerful strength. CONSTITUTION:Within the helical coil to be integrated by coupling the helical part of a coil 7, upper and lower press cylinders 8a, 8b with one another, the initial turn and the final turn of the coil 7 are coupled with the upper and lower press cylinders 8a, 8b simultaneously coupling the initial turn and the next turn as well as the final turn and the turn exceeding one this side to be integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a normal-conducting helical coil for generating a strong magnetic field, and more particularly to a helical coil having high strength and high conductivity, which can be made large in size, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In a nuclear fusion device, the magnetic field strength required to confine generated plasma is 10 to 2
The number of terraces is expected to be 0 or more, and the development of a coil made of a conductive conductor that can withstand such a strong magnetic field is urgent. In the various fusion experimental devices so far, the normal conductor (copper wire)
It consumes a huge amount of power because it uses the coil. Therefore, it is essential to develop a coil made of superconducting wire that does not consume power.

By the way, in order to develop a high-performance superconducting conductor capable of withstanding a strong magnetic field, various conductors are developed and placed in a strong magnetic field generator, and the critical current density (Jc), upper critical magnetic field, and AC loss Etc. need to be checked.

The above-mentioned strong magnetic field generator is generally constructed by arranging a superconducting magnet coil 2 concentrically outside a water-cooled magnet coil 1 as shown in FIG. In such a device, the sum of the magnetic fields generated by the magnets 1 and 2 is maximized at the central portion 3 of the magnetic field of the water-cooled magnet coil 1, and a strong magnetic field of, for example, 30 terraces or more can be generated. This water-cooled magnet coil has 3 types of poly-helix type, bitter type and mono-helix type.
There are two types.

Of the above three types, the polyhelix type coil which is the object of the present invention is a combination of a plurality of single-layer helical coils formed of rectangular wires in a concentric ring shape, and the single-layer coils are electrically connected to each other. Is a multi-layer helical coil connected in parallel and in series. Then, a structure is generally adopted in which cooling water is caused to flow in the gap between adjacent layers to cool it.

Assuming that the multi-layer helical coils are independently supported, the circumferential tensile stress generated in each coil is proportional to the product of the current density, the coil radius and the magnetic field. Therefore, as the conductor of the helical coil, a conductor having high strength in the circumferential direction, particularly high yield strength and high conductivity is required, and Cu or Cu alloy is used, for example.

That is, in a hybrid magnet, when an attempt is made to obtain a strong magnetic field, for example, 40 to 50 terraces, the stress in the circumferential direction acting on the water-cooled magnet becomes extremely high, so that the yield strength of the helical coil conductor is 45 kg / m.
m ² The above must be satisfied. Furthermore, in order to make it compact, a conductivity of 90% (IACS) or higher is required.

Conventionally, in order to manufacture such a helical coil conductor, the helical coil conductor has been manufactured by the steps shown in FIGS. 4A, 4B and 4C, for example. That is, the solid cylindrical material 4 made of copper or copper alloy is processed into the hollow cylindrical material 5 by machining or electric discharge machining.
To produce. After that, the spiral slit 6 is processed along the outer circumference of the hollow cylinder 5 to form a spiral helical coil 7, and the helical coil 7 is prevented from bulging outward, and at the same time, between the coil layers. For the purpose of integration, cylinders 8a and 8b for pressing the respective turn coils and the insulating material between the turns are provided from above and below.

Further, in the case where a hollow cylinder material 5 satisfying the specified characteristics, for example, the physical properties and strength, cannot be obtained, FIG.
As shown in (A) and (B), upper and lower presser cylinders 8a ', 8
b'and the helical coil are separately manufactured, and the stepped portions 9 of the upper and lower presser cylinders 8a ', 8b' and the helical coil 7 are coupled and integrated.

As a method for manufacturing the helical coil, there are a method of processing from a hollow cylinder and a method of winding a rectangular drawn wire in a spiral shape. Also, as a method of combining, FIG.
There is a butt joint 10a of the step portion 9 or a side joint 10b for joining the coil side surface and the hollow pressing cylinder side surface by brazing or welding as shown in FIG.

[0011]

However, in the conventional method of connecting the upper and lower pressing cylinders to the helical coil, there is a problem that the circumferential tensile force generated in the helical coil conductor by the electromagnetic force cannot be sufficiently endured.

That is, the helical conductor itself has sufficient strength to withstand the circumferential force generated in the conductor, but the upper and lower holding cylinders do not have sufficient strength, so Deformation or breakage of parts occurs. For this reason, side joints may be used together with butt joints, but since the strength of the upper and lower presser cylinders, especially the joint strength for brazing or welding, is basically low, the circumferential direction of the helical coil conductor is limited. I can't stand my strength.

By the way, as the material for the upper and lower presser cylinders,
Generally copper and copper alloys such as Cu-Cr, Cu-Cr
Although -Zr alloy or the like is used, the vicinity of the joint is softened and recrystallized by heating at the time of joining, so that the strength is remarkably lowered, resulting in poor joint strength with the helical coil conductor.

Therefore, it is possible to use alumina dispersion strengthened copper having high strength and high conductivity. However, although the wire drawing, which is the main wire of the helical coil conductor, can be easily obtained, it is difficult to manufacture a large cylinder such as an upper and lower pressing cylinder. For this reason, the helical coil is manufactured by a winding method in which a coil conductor is wound around a cylindrical body, and a method in which the upper and lower holding cylinders are coupled to each other is adopted.

As described above, since the strength of the joint between the spiral coil and the lower pressing cylinder is not sufficient, it is difficult to manufacture a large-sized helical coil of high quality.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to provide a large-sized and high-strength structure by forming a spiral coil and a lower pressing cylinder with a high-strength joint structure. It is an object of the present invention to provide a helical coil that can be manufactured with high quality and a manufacturing method thereof.

[0017]

In order to achieve the above object, the present invention relates to a helical coil in which a spiral coil and an upper and lower pressing cylinder are combined and integrated with each other, and a first turn and a final turn of the coil are provided. Is connected to the upper and lower presser cylinders, and the coil is integrated with the upper and lower presser cylinders by connecting the first turn and the next turn of the coil and the final turn and one or more turns before this. It constitutes a helical coil.

Further, in the method for manufacturing a helical coil in which the spiral coil and the upper and lower pressing cylinders are combined and integrated, a spiral coil is formed from a coil conductor having high strength and high conductivity, and this coil is formed. When the upper and lower presser cylinders are combined to integrate them, the first turn and the final turn of the coil are connected to the upper and lower presser cylinders, and between the first turn and the next turn of the coil and the final turn. A turn is connected to one or more turns before the turn to manufacture a helical coil.

[0019]

In the helical coil having such a structure and the method for manufacturing the helical coil, the first turn and the next turn of the spiral coil and the last turn and one or more turns before the turn are connected to each other. The circumferential force of the coil is concentrated on the latter joint portion, and the circumferential force applied to the former joint portion becomes very small. For this reason, there is no problem even if the strength of the former joint is low, and for the latter joint, use a coil conductor with high strength conductivity that is excellent in brazing or welding, and provide a sufficient joint area. Provides sufficient strength to withstand the circumferential direction.

Therefore, it is possible to use a high-strength, high-conductivity, high-quality coil conductor using cold-drawn wire, and manufacturing efficiency and material yield are also greatly improved. Also,
Since it is possible to use a low-cost copper alloy as the upper and lower presser cylinders, the manufacturing cost can be significantly reduced.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a manufacturing process of a helical coil according to an embodiment of the present invention. In this embodiment, FIG.
As shown in (A), the upper and lower presser cylinders 8a and 8b are made of Cu-
It was cut out from a solid cylindrical material of Cr alloy by machining and manufactured, and then the step portions 9a and 9b were processed on the coil bonding side using an NC processing machine. The spiral coil is formed by winding a wire drawing of alumina dispersion strengthened copper around a cylindrical body,
Made by machine finishing. Thereafter, as shown in FIG. 1B, the connecting portions 10a, 1b between the first turn of the coil 7 and the butt end face side of the upper pressing cylinder 8a and the disconnecting portion 9a.
0b and the joint 10 between the first turn and the next turn
c, the joints 10a and 10b between the last turn of the coil 7 and the butt end face side of the lower presser cylinder 8b and the step 9b, and the joint 10c between the last turn and the previous turn. Insert a brazing foil made of Cu-Ag-In having a thickness of 2 mm as shown in the enlarged view of FIG.
Bonding was performed in a vacuum at 0 ° C.

In this case, the connection 10a between the upper pressing cylinder 8a and the first turn of the coil and between the lower pressing cylinder 8b and the final turn of the coil and between the first and the next turn and the final turn. The joint length of the joint portion 10c between the turn and the previous turn is set to 5 times the coil height. In addition, in order to improve the bondability, the pre-brazing treatment and load pressure brazing conditions were adopted.

According to the above embodiment, since the alumina dispersion strengthened copper can be used as the helical coil conductor,
During brazing, the strength of the conductor is not significantly reduced by brazing even if the entire heating is performed, and at the same time, the first turn and the next turn of the coil as well as the last turn of the coil and the previous turn of the coil are joined. Therefore, the coupling strength between the turns is high, and the conductor is not broken by the circumferential force of the conductor due to the electromagnetic force.

That is, in the conventional method, only the coil side surface and the cylindrical side surface are joined, so that the CU-Cr alloy is softened by the overall heating during brazing,
The shear strength of the joint decreased. At this time, the strength against shearing force was limited because the strength of the holding cylinder was reduced due to the heat treatment, so there was a limit to the bond length between cylinders, that is, the strength obtained even if the bond area was increased. ..

On the other hand, in this embodiment, since the coupling strength between the turns of the coil is large, the upper and lower pressing cylinders 8a, 8
Even if the length of the joint between b and the coil 7 is minimized, the shear strength of the joint can be increased. Table 1 compares the strength of the joint portion according to this example with the conventional joint method.

[0027]

[Table 1] In this case, the length of the joint was set to 5 times the coil height in order to reach the optimum strength.

Only the butt-coupling of the conventional method can obtain only about 1/4 of the tensile strength of the coil conductor. Also, by combining this with the coupling between the cylinders,
Since it has not reached the strength of about 2/3, it is meaningless to use a high quality material as the coil conductor. On the other hand, by coupling the coil turns as in this example, the coil conductor was fractured without fracture at the coupling portion.

Further, by using alumina dispersion strengthened copper as the coil conductor and connecting the coil turns, it becomes possible to use a low-cost Cu-Cr alloy holding cylinder, and to make the performance of the coil conductor sufficiently effective. Can be utilized. Also, because the joint strength between the coil conductors is excellent,
The joint length may be short, resulting in low cost.

In the above embodiment, the number of joints is minimized as shown in FIG. 2, but by providing the joints on the entire circumference between turns and the entire circumference between cylinders, more excellent characteristics can be obtained. Further, although the brazing method is used in the above embodiment, the same effect can be obtained by performing electron beam welding, TiG welding, and diffusion bonding.

Although a cylinder of alumina dispersion strengthened copper and Cu-Cr alloy is used as a coil material in FIG. 1,
Other coil materials such as copper alloy mixed with short fibers, whiskers, particles and the like may be used.

[0032]

As described above, according to the present invention, since the connection between the spiral coil and the upper and lower pressing cylinders becomes strong, the performance of the coil conductor can be effectively used, and as a result, the coil conductor can be used more effectively than before. It is possible to manufacture a large helical coil with high strength and high quality. Especially for coupling between coil conductors,
Since the strength required for the upper and lower presser cylinders may be small, not only the material restrictions are eliminated but also the shape restrictions are removed, the use of a spiral coil formed from cold pressed wire drawing. It becomes possible to manufacture a larger and lower cost helical coil.

[Brief description of drawings]

FIG. 1 is a diagram showing a process of manufacturing a helical coil according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a coupling portion between the upper pressing cylinder and the spiral coil shown in FIG.

FIG. 3 is a cross-sectional view showing the configuration of a strong magnetic field generator.

FIG. 4 is a diagram for explaining an example of a conventional helical coil.

FIG. 5 is a diagram for explaining another example of a conventional helical coil.

FIG. 6 is an enlarged view of the connecting portion shown in FIG.

[Explanation of symbols]

7 ... spiral coil, 8a, 8b ... upper and lower pressing cylinders, 9a, 9b ... step portion, 10a ... inter-cylinder coupling portion,
10b ... Butt joint, 10c ... Inter-turn joint.

Claims (2)

[Claims] 1. A helical coil in which a spiral coil and an upper and lower pressing cylinder are combined and integrated with each other, wherein a first turn and a final turn of the coil are connected to the upper and lower pressing cylinders, and A helical coil characterized in that the first turn and the next turn, and the last turn and one or more turns before that are connected to each other to integrate the coil and the upper and lower presser cylinders. 2. A method for manufacturing a helical coil in which a spiral coil and an upper and lower pressing cylinder are combined and integrated with each other,
When forming a spiral coil with a coil conductor of high strength and high conductivity, and connecting the upper and lower presser cylinders to this coil to integrate them, the first turn and the final turn of the coil are A method for manufacturing a helical coil, characterized in that the helical coil is connected to a holding cylinder, and the first turn and the next turn of the coil and the final turn and one or more turns before the turn are connected.