JPH0485903A - Manufacture of superconducting magnet coil - Google Patents

Abstract

PURPOSE:To enable preventing the generation of quench by winding a coil round a spool while causing a superconducting wire to deviate by every 1/2 pitch of a superconducting wire width in the winding direction repeatedly for every one layer and while inserting a spacer with specific compression modulus of elasticity alternately at the start and end of winding in the winding direction. CONSTITUTION:A coil is wound round a spool 1 while a superconducting wire 2 is caused to deviate by every 1/2 pitch of a superconducting wire width in the winding direction repeatedly for every one layer and while a spacer 7 with compression modulus of elasticity of 2000-40000kg/mm<2> alternately at the start and end of winding in the winding direction is inserted. Then, the coil wound around the spool 1 is received in a vacuum pressurized impregnation tank 8 together with the spool and is vacuum-impregnated with an acid anhydride- hardened epoxy resin 4 through a filler hole 9, an inert gas (N2 gas) is enclosed in the impregnation tank 8, and the whole impregnation tank 8 is heated by the use of a steam heater 12 under an applied pressure of 2-500kg/cm<2> to harden the impregnation resin 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a superconducting magnet coil.

[Conventional technology]

A superconducting magnet coil is formed by winding superconducting wire around a winding frame and impregnating it with resin. 5 It is usually cooled to an extremely low temperature with liquid helium, and by reducing the electrical resistance of the superconducting wire to zero, it is possible to conduct large currents. generates a strong magnetic field. However, when electricity is applied, a large electromagnetic force is generated in the superconducting wire, and if this large electromagnetic force causes a slight displacement of the superconducting wire, that is, a movement of magnetic flux, the work of movement (heat) is generated.
occurs, the temperature of the superconducting wire in that part rises, and the superconducting state transitions from the superconducting state to the normal conducting state, and a part of the electromagnetic energy of the coil is converted into heat, which melts the superconducting wire and destroys the superconducting magnet coil. It becomes like this.

If such superconducting wire moves, it will have a significant effect on the superconducting magnet coil. For example, maximum magnetic flux B ll&!
5,9 In the estimated value at Te5la and current I = 800 A, the temperature of the superconducting wire is T(k), and the helium temperature is ro.
(k), the Debye temperature of copper as H(k), and the gap as G(
m), the number of atoms in copper Igr is N, and the weight of the unit length wire is ρ
(gr), and the Boltzmann constant is K, then from the following equation, when the gap G (movement amount) becomes equal to or more than 6 μm, it enters the normal conduction transition region and normal conduction breakdown (quench) occurs.

For these reasons, conventionally, in manufacturing superconducting magnet coils, the winding tension of the superconducting wire on the winding frame,
Various methods are being considered, including the positional relationship of the conductors, a well-balanced winding method, and impregnating and fixing with resin.

That is, conventionally, as shown in FIG. 6, superconductors [2] were placed in multiple stages on a winding frame 1 that was later removed.

The superconducting wire 2 is wound in multiple layers in alignment with the width pitch of the superconducting wire 2, and then the coil thus wound is set in a resin impregnator 3, and the resin 4 is impregnated and hardened to form a superconducting magnet coil 5.
was manufacturing.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not have sufficient rigidity in the winding direction (stacking, stacking direction) of the superconducting magnet coil, and displacement occurs due to the shear force difference between the superconducting wires due to the electromagnetic force when a large current is applied. Alternatively, a difference may occur in the amount of resin impregnated between the superconducting wires, and as shown in FIG. There was a problem that b occurred.

If peeling a or crack b occurs in this way, it will adversely affect the characteristics of the 5 superconducting magnet coil, and it will eventually quench. In addition, in the same figure, 28 is the superconducting wire 2
It is an insulating coating material that insulates the

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a superconducting magnet coil that makes it possible to prevent the occurrence of quench.

[Means to solve the problem]

The above purpose is to shift the coil by 1/2 pitch of the superconducting wire width in the winding direction by repeating each layer of superconducting wire on the winding frame.
The winding is achieved by alternately inserting spacers having a compressive elastic modulus of 2,000 to 40,000 kg/rrn2 at the beginning and end of the winding in the winding direction.

[Effect]

By providing the above means, the rigidity of the coil in the winding direction is greater than before, and the amount of resin impregnated between the superconducting wires is smaller than before, preventing peeling of the resin-filled portion and occurrence of cranks. Become so.

We investigated how to prevent the peeling of the injected resin and the occurrence of cranks, which cause quenching. It was confirmed that peeling and cracking occur in the resin between superconducting wires in the early stages of production because the resin filled areas concentrate between the superconducting wires and the amount of resin filled increases. That is, when the amount of resin filled increases, peeling or cracking occurs in the injected resin due to internal residual stress caused by total contraction of the resin. Therefore, in order to prevent the injected resin from peeling off and causing cranks, the resin filled portion should not be concentrated between the superconducting wires.
In addition, it was found that it would be better to increase the rigidity of the coil in the winding direction and reduce the amount of resin filled. Therefore, in the present invention, in the coil, six superconducting wires are placed on a winding frame, and each layer is shifted by 172 pinches of the superconducting wire width in the winding direction, and compressive elasticity is applied alternately at the beginning of winding and at the end of the winding. rate is 2
,000 to 40,000 kg/m+2 while inserting a spacer. By doing so, it is possible to obtain a method for manufacturing a superconducting magnet coil that makes it possible to prevent the occurrence of quenching.

〔Example〕

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 1-3.

It should be noted that the same parts as in the prior art have been given the same reference numerals, so their explanation will be omitted. In this embodiment, a coil is placed on a winding frame 1 with a superconducting wire 2
is repeated for each layer by 1/2 pitch of the superconducting wire width in the winding direction, and the compressive elastic modulus is 2,000-40,000 kg/mm alternately at the beginning of winding and at the winding wire.
The winding was formed while inserting the spacer 7 of No. 2. By doing this, the rigidity of the coil in the winding direction is increased compared to the conventional method, and the amount of resin impregnated between the superconducting wires is reduced compared to the conventional method. Thus, it is possible to obtain a method for manufacturing a superconducting magnet coil that makes it possible to prevent the occurrence of quench.

That is, the superconducting wire (polyvinyl formal coated NbT+) 2 is placed on the winding frame 1 a predetermined number of times, as shown in Fig. 1, by shifting the width of the superconducting wire by 172 pinches, and compressive elasticity is applied alternately to the beginning of the winding and the end of the winding in the winding direction. A GFRP spacer 7 having a rate of 4.000 kg/mm2 is inserted and wound. The winding tension of the superconducting wire 2 at this time is 1 to 60 kg10n2 (10
~600MPa). This is the internal residual stress of 80 to 90 kg/cJ (
This is to apply a winding stress of 8 to 9 MPa or more to prevent peeling and cranking caused by shrinkage of the resin 4.

The coil thus wound around the winding frame 1 is housed together with the winding frame in a vacuum pressurized impregnation tank 8 shown in FIG. mm
Vacuum impregnation is carried out through the injection port 9 at a temperature below Hg.

After completion of impregnation, stop the vacuum evacuation system 1o, fill the impregnation tank 8 with inert gas (NZ gas) using the high-pressure pump 11, and increase the pressure to 100 kg/cx& (], OM P
a), and in this pressurized state, the entire impregnation tank 8 is heated using the steam heater 12 attached to the impregnation tank 8, and the impregnated resin 4 is cured. After curing, the winding frame 1 is removed to complete the superconducting magnet coil 5a. As shown in FIG. 2, no peeling or cracking was observed in the resin-filled portion 6 of this magnet coil 5a.

An excitation test was conducted in which an excitation current was applied to the superconducting magnet coil 5a manufactured in this manner, and the number of repeated quenching cycles until a predetermined current could be applied was evaluated to confirm the superconducting properties. As a result, the number of times of quenching to reach 100% of the predetermined current was once, and the quenching did not occur the second time even at 105% of the predetermined current. This is a marked improvement in characteristics compared to conventional superconducting magnet coils manufactured by aligned winding, which require three to four or more machining cycles to reach a predetermined current flow.

In this way, according to this embodiment, the superconducting wire is repeatedly shifted by 1/2 pitch of the superconducting wire width in the winding direction, and the compressive elastic modulus is alternately changed at the beginning of the winding and at the end of the winding in the winding direction. By inserting and winding a spacer that has a higher equivalent compressive elastic modulus in the same direction as the superconducting magnet coil, it was possible to increase the compressive elastic modulus in the stacking and stacking direction of the superconducting magnet coil and achieve integral rigidity. Furthermore, since the structure is such that the amount of resin filled between the superconducting wires is small, a coil without peeling or cracking between the superconducting wires inside the superconducting magnet coil can be obtained. In addition, galling at the corners between the superconducting wires due to collapse of the superconducting wires is difficult to occur, and it is effective in preventing the occurrence of layer shorts. A superconducting magnet coil (which does not shift in the shear direction) is obtained. In this way, a coil that is resistant to torsion without peeling or cranking can be obtained, thereby preventing the occurrence of quenching at extremely low temperatures even when a large current is applied.

A superconducting magnet coil with extremely excellent superconducting properties can be obtained.

FIGS. 4 and 5 show other different embodiments of the present invention. FIG. 4 shows the case where an inorganic or organic filling auxiliary material 13 is inserted into the resin filling part 6 when the superconducting wire 2 is wound, and FIG. 5 shows the curvature of the four corners of the superconducting wire 2 and the insulating coating 2a This is a case where the occupancy rate of the resin filling part 6 is made small by making it as small as possible. In any of these cases, the amount of injected resin impregnated is smaller than in the above case, and the superconducting properties can be improved more than in the above case. In other words, in these embodiments, the filling auxiliary material 13 is placed during winding, or the curvature of the four corners of the superconducting wire 2 and the insulating coating material 2a is minimized to minimize the occupation rate of the resin filling portion 6, that is, the superconducting wire 2 It can be adjusted as necessary, such as by increasing the filling rate inside the coil.

In addition, the compressive elastic modulus of the spacer is 2,000 to 40.00.
The reason for selecting 0 kg/mm2 is as follows. Equivalent modulus of elasticity of laminated superconducting wires (modulus of elasticity including insulation coating of superconducting wires) based on past empirical knowledge
is approximately 2,000 kg/rm2 (2x 10'
rvi Pa), so the compression modulus is 2,000k
This is because if it is less than 2X I O'~1Pa, the force from the superconducting wire to the outer frame (winding frame case, etc.) may not be transmitted. The larger the value is than 2,000 kg/an2, the better. This is because materials having a compressive modulus of elasticity of 40,000 kg/nu2 are currently at a stage where they can be put to practical use. In addition, during heat curing after vacuum impregnation of the resin, it is effective to apply a pressure greater than the internal residual stress at the time of full contraction of the resin to increase the integral rigidity of the superconducting wire.

Further, the resin is a thermosetting resin such as epoxy resin, silicone resin, polyimide resin, polyurethane resin, or a modified resin that imparts flexibility to reduce internal residual stress at the time of full contraction.

In addition, the spacer has a compression modulus of 2.000 as described above.
It is necessary to select materials of kg/w+2 or more, such as epoxy resin, silicone resin, boimide resin, polyurethane resin, modified resin, silicon carbide fiber, carbon fiber, glass fiber, aramid fiber, boron fiber, alumina fiber, etc. Composite materials impregnated and cured with organic or inorganic fibers, or ceramic materials such as silicon carbide, alumina, silicon tinide, etc. alone, or cured by appropriately blending the above resins, etc. can be used as necessary. Just use it.

In addition, in this example, the case where the superconducting wire is wound by shifting 1/2 pitch of the superconducting wire width, but the superconducting wire is wound by shifting 1/3 and 1/4 pitch of the superconducting wire width. can also produce similar effects.

〔Effect of the invention〕

As described above, the present invention prevents the occurrence of quenching in the superconducting magnet coil, thereby providing a method for manufacturing a superconducting magnet coil that can prevent the occurrence of quenching.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of an embodiment of the method for manufacturing a superconducting magnet coil of the present invention, FIG. 2 is an enlarged longitudinal sectional side view of the B frame portion of FIG. 1, and FIG. 4 and 5 are enlarged longitudinal sectional side views of main parts of magnet coils according to different embodiments of the method of manufacturing a superconducting magnet coil of the present invention, and FIG. 6 is a longitudinal sectional side view of a pressure impregnation tank, and FIG. 6 is a conventional superconducting magnet coil. FIG. 7 is an enlarged vertical side view of the A-frame portion of FIG. 6. 1. Winding frame, 2. Superconducting wire, 4. Resin, 5a superconducting magnet coil, 7. Spacer, 13. Filling auxiliary material.

Claims (5)

[Claims] 1. A method for manufacturing a superconducting magnet coil in which a coil formed by winding a superconducting wire in multiple layers and stages around a winding frame that is later removed is impregnated with a resin and hardened. is repeatedly shifted by 1/2 pitch of the superconducting wire width in the winding direction, and the compressive elastic modulus is alternately 2,000 to 40,000 kg/at the beginning and end of the winding in the winding direction. A method for manufacturing a superconducting magnet coil, characterized in that the coil is formed by winding it while inserting a spacer of mm^2. 2. 2. The method of manufacturing a superconducting magnet coil according to claim 1, wherein the coil has a filling auxiliary material filled between the superconducting wires. 3. The coil carries the superconducting wire at a weight of 1 to 60 kg/mm.
2. The method of manufacturing a superconducting magnet coil according to claim 1, wherein the superconducting magnet coil is wound with a winding tension of ^2. 4. The coil has a weight of 2 to 500 kg/cm after being impregnated with resin.
2. The method of manufacturing a superconducting magnet coil according to claim 1, wherein the superconducting magnet coil is hardened by heating under a pressure of ^2. 5. A method for manufacturing a superconducting magnet coil in which a coil formed by winding a superconducting wire in multiple layers and stages around a winding frame that is later removed is impregnated with a resin and hardened. is repeated for each layer by 1/3 or 1/4 pitch of the superconducting wire width in the winding direction, and the compressive elastic modulus is 2,000 to 40,000 kg/mm^2 at a predetermined position in the winding direction. A method for manufacturing a superconducting magnet coil, characterized in that the coil is formed by winding it while inserting a spacer.