JPS5936806B2 - Superconducting coil winding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for winding a superconducting coil having a complex shape, particularly a portion with a small bending radius.

Generally, when stress is applied to superconducting wires, there is a phenomenon called "stress effect" in which the superconducting properties deteriorate, so the permissible bending diameter of the wires is 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000.
4% or less, 1.0% in terms of strain for Nb-Ti wires
It is limited under the following conditions.

Therefore, in conventional winding methods, when manufacturing a coil with a complex curved surface such as a saddle-shaped coil or a baseball coil, once the wire size is determined, it is necessary to make the coil more compact than a certain limit or It was not possible to wind the wire into any shape. Therefore, in order to obtain the desired generated magnetic field precision and magnetic field uniformity, the conductor size has been reduced and the wires have been wound. However, reducing the conductor size increases the number of coil turns and inductance, which increases the cost of wire, power supply, and coil processing, and also deteriorates the stability of the magnet. Particularly when edgewise bending is required, the conditions for the allowable bending diameter are strict, and for this reason, it has sometimes become impossible to design an appropriate conductor using compound wire. The present invention has been made as a result of intensive research in view of the current situation, and has been developed as a result of a superconducting coil that can be wound on a curved surface with a particularly small bending diameter in a superconducting coil made by winding a superconducting wire material in which a superconducting wire and a normal conductive metal wire are twisted. The present invention provides a method.

That is, the method of the present invention is a method for winding a wire made by twisting a superconducting wire and a normal conductive metal wire into a coil, in which the internal characteristics of the wire to be wound over part or all of the curved surface of the coil are A wire is wound by removing part or all of the conductive metal wire, and an appropriate number of normal conductive metal wires are removed over a predetermined length from the wire to be wound, and the wire is wound along a predetermined bending radius. It is used to wind wires. In this way, in the method of the present invention, the allowable bending diameter is set to form a space in which the portion corresponding to the cross-sectional area of the removed normal conductive metal wire can move relative to the remaining wires in response to bending. It can be made much smaller.

Specifically, the normal conductive metal wire is a stabilizing material, a reinforcing material, or a mere dummy metal. Furthermore, in the method of the present invention, the stranded wire structure of the superconducting wire material and the normal conductive metal wire is not particularly limited, and any structure may be used. It has a remarkable effect when

There are no particular limitations on the number or length of the normal conductive metal wires to be removed, but it is usually possible to reduce them gradually in accordance with the bending diameter as the wires move from the inner layer to the outer layer of the coil. preferable. Note that the method of the present invention may partially impair the functions of the normal conducting metal strands, such as stabilization and mechanical strength, but it is possible that the portion of the normal conducting metal strands to be removed is the bent portion of the coil. Since it is often removed from the inner layer of the coil where the bending conditions are severe, it does not particularly affect the overall superconducting coil.

Next, one embodiment of the method of the present invention will be described in detail based on the drawings.

Nb-Ti superconducting wire 2 (Cul.5, NB
- A wire rod 1 with a width of 3.17 m and a thickness of 0.9 m is made by forming 12 Ti filaments (85 pieces) and 34 high-purity copper wires of 0.5φ into a rectangular shape as shown in Fig. 1. A saddle-shaped coil 4 having a shape as shown in FIG. 2 was manufactured.

In this coil, any wire material may be used for the straight portion 5, but the curved portions 6 and 7 must be made as compact as possible from the viewpoint of magnetic field precision. When this curved surface is enlarged, it becomes as shown in FIG. 3, and in the part 8 in the figure the wire is bent flatly, and in the part 9 it is bent edgewise. In addition, according to the conventional winding method, the bending radius is 7 m with a flat weiss and the bending radius is 2 m with an edge wise.
It is possible to wind up to 5 m without any significant change in the appearance of the wire. The method of the present invention is to remove one 0.5φ copper wire 10 corresponding to the bent portion of the coil from the wire 1 as shown in FIG. Bending radius 12? Now it is possible to wind wires with wire.

Furthermore, when winding was performed by removing two 0.5φ copper wires, it was possible to wind the wire up to a bending radius of 6 m with a flat wire wire and 10 m with an edge wire wire. However, when three or more 0.5(X) copper wires were removed, the gaps between the strands were not filled, making it impossible to form an appropriate winding. FIG. 5 shows the results of measuring the superconducting critical current characteristics of wires wound in a bent state using the method of the present invention and the conventional method.

Note that in the figure, 1c0 is a current value measured in an unstrained state, and Ic is a current value measured in a bent state. As is clear from FIG. 5, there is almost no difference in the critical current value between the method of the present invention and the conventional method when it comes to flat wire bending, but when it comes to edge wire bending, the method of the present invention is far more effective than the conventional method. showed superiority in

As detailed above, according to the method of the present invention, it is possible to wind the wire with a much smaller bending radius than in the conventional method.
It becomes possible to compactly manufacture coils with complex shapes.

Therefore, the cost for processing wires and coils can be reduced, and a high-performance superconducting magnet with excellent stability and high precision of the generated magnetic field can be obtained.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a wire made by twisting a superconducting wire and a normal conductive metal wire, Figure 2 is an explanatory diagram for forming the wire into a saddle-shaped coil, and Figure 3 is a diagram of the bent portion of the saddle-shaped coil. 4 is an enlarged view of the curved surface of the winding obtained by the method of the present invention, and FIG. 5 is the relationship between the bending radius and Ic/IcO when wire rods obtained by the method of the present invention and the conventional method are bent. It is a diagram. DESCRIPTION OF SYMBOLS 1...Twisted wire material, 2...Superconducting wire, 3...Normal conductive metal wire, 4...Saddle-shaped coil, 5...Straight portion, 6
, 7...Curved part, 8...Flat weiss, 9...
・Edgewise, 10...Removed portion of normal conductive metal wire.

Claims (1)

[Claims] 1. In a method of winding a wire made by twisting a superconducting wire and a normal conductive metal wire into a coil, the normal conductive metal element in the wire to be wound over a part or all of the curved surface of the coil. A method for winding a superconducting coil, which comprises removing part or all of the wire before winding.