JP2006319189A - Superconducting magnet and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting magnet, having high precision for coil profile where ample bonding strength is attained between a spool or an interlayer sheet and a superconductor in a short time, and to provide its production method. <P>SOLUTION: The superconducting magnet comprises an interlayer sheet 3 of fiber-reinforced resin, produced by cleaning a roughened surface with organic agent and then forming a fusing agent layer 4 of self-fusing resin on the surface, and a superconductor 2 having the fusing agent layer 4 of self-fusing resin on the surface. The superconductor 2 is wound around a spool, in a plurality of layers with the interlayer sheet 3 interposed in-between, and the fusing agent layers of the interlayer sheet 3 and the superconductor 2 are fused with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a superconducting magnet used for a particle accelerator, a nuclear magnetic resonance imaging apparatus, and the like, and a method for manufacturing the same.

  In a superconducting magnet used for a particle accelerator or the like, a coil tends to have a high current density and a large size in order to generate a magnetic field having a necessary strength. As the generated magnetic field increases, a large electromagnetic force is generated, and structural support and fixing are important. If the coil is not sufficiently fixed, a quench phenomenon may occur in which the superconducting state is broken when the conductor is slightly moved due to disturbance such as electromagnetic force, and the performance of the device cannot be exhibited.

  In the case of a superconducting magnet with two or more poles generally used for large particle accelerators, a cable called Rutherford type is formed by gathering several single-conductor superconducting conductors, twisting them, and then forming them into a trapezoid shape with a die. Use a conductor. In the case of coil molding, the cable conductor is formed into a bowl shape and is assembled around the beam through-hole to generate a necessary magnetic field (see Non-Patent Document 1 below). However, since the cable conductor is a conductor in which a plurality of single wires are stranded, the cross-sectional area becomes large and it is applied to a superconducting magnet that is inevitably used at a large current.

  On the other hand, in the case of a superconducting magnet used at a small current, a round wire or a single wire of a square wire is used. However, it is more efficient to form a saddle coil and to further improve the conductor positioning accuracy. There is currently no established way to do this. However, although it is not efficient, as a method of winding a single superconducting wire with high positional accuracy, the superconducting wire is directly bonded and fixed to the structure around the beam through-hole with a winding machine capable of coordinate control. There is a way. In this winding method, an acrylic instantaneous adhesive or an epoxy thermosetting resin is used as an adhesive.

In addition, although it is not a method of directly bonding and fixing a conductor on a winding machine, for example, in Patent Document 1 below, a conductor covered with a self-bonding material is wound around a cylindrical winding frame while applying tension. A method of forming a coil by making it cylindrical and later heating is disclosed.
"Superconducting Engineering", published by Ohmsha 1991 Japanese Patent No. 2597724

  When adopting the above-mentioned method of winding the superconducting conductor while directly bonding and fixing it to the structure around the beam through-hole with a winding machine capable of coordinate control, the position accuracy of the superconducting conductor is the mechanical property of the winding machine. Although it can be ensured by the control accuracy, when an instantaneous adhesive is used for fixing the superconducting conductor, the adhesive strength decreases at a very low temperature, and sufficient strength cannot be obtained. In addition, when bonded and fixed with an epoxy-based thermosetting resin, the strength at extremely low temperatures can be ensured, but a certain thermosetting time is required. Due to the stagnation, the winding work speed is significantly reduced. This is the same even in the case of a multi-layer coil in which a coil is further formed on the conductor coil that has been produced by covering it with an interlayer sheet such as a fiber reinforced resin.

  Further, as described in Patent Document 1, a cylindrical coil is formed by winding a conductor in which a self-bonding material is applied to a cylindrical winding frame while applying tension, and then heating the coil. In the method of forming the coil, since the coil can be continuously formed, a high winding working speed can be obtained. However, in order to obtain sufficient adhesion in the subsequent heat-sealing step, it is necessary to wind the conductor around the winding frame while applying tension. For this reason, the coil shape is limited to a shape that can be tensioned during winding, such as a cylindrical solenoid coil, and a saddle-shaped coil or the like is difficult to manufacture. In addition, in the case of a multi-layered coil, if the conductor is wound with tension, the conductor position accuracy of the upper layer deteriorates due to dropping of the interlayer sheet, etc., so that the conductor position accuracy cannot be ensured as the winding proceeds to the upper layer. There is a problem.

  For example, FIG. 6 is a detailed cross-sectional view showing a coil portion, and the interlayer sheet 3 and the superconducting conductor 2 are bonded and fixed by an instantaneous adhesive 6 applied between the superconducting conductor 2 and the interlayer sheet 3. In the superconducting magnet configured as described above, when the upper layer conductor is disposed on the portion without the lower layer conductor, the space immediately below the upper layer conductor becomes a space, so that the interlayer sheet 3 is It may fall into the lower layer side and the upper layer conductor position accuracy may deteriorate. In addition, when the adhesive is applied without applying tension, there is a problem that the adhesive strength cannot be sufficiently secured because the instantaneous adhesive 6 adheres the interlayer sheet 3 and the superconducting conductor 2 in a state close to point contact.

  Accordingly, an object of the present invention is to provide a superconducting magnet having a sufficient adhesive strength between a winding frame or an interlayer sheet and a superconducting conductor in a short time and having a good coil shape accuracy, and a method for manufacturing the same.

  In order to solve the above-mentioned problem, claim 1 of the present invention comprises a reel formed of a fiber reinforced resin and having a surface formed with a fusing agent layer made of a self-fusing resin after roughening the surface and washing with an organic solvent. And a superconducting conductor wound around the reel having a fusing layer made of a self-fusing resin, the fuser layer of the reel and the fusing agent layer of the superconducting conductor being fused. It is assumed that it is worn.

  Further, the present invention provides an interlayer sheet comprising a fiber reinforced resin, the surface of which is roughened and cleaned with an organic solvent, and a fusion agent layer comprising a self-fusing resin formed on the surface, and a fusion comprising a self-fusing resin. A superconducting conductor having an agent layer on its surface, and a plurality of layers of the superconducting conductor are wound around the winding frame with the interlayer sheet interposed therebetween, and the fusion agent layer of the interlayer sheet and the superconducting conductor are fused. The agent layer is fused.

  ADVANTAGE OF THE INVENTION According to this invention, sufficient adhesive strength can be obtained between a winding frame or an interlayer sheet, and a superconducting conductor in a short time, and a superconducting magnet with a sufficient coil shape accuracy and its manufacturing method can be provided.

An embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a superconducting conductor 2 is wound around a beam through-hole surrounding structure 1, which is a winding frame, by a winding machine capable of coordinate control (not shown). As shown in FIG. 2, the superconducting conductor 2 is wound in multiple layers with an interlayer sheet 3 interposed therebetween. Also, as shown in FIG. 3, the superconducting conductor 2 is formed between the superconducting conductor 2 and the interlayer sheet 3 by pressurizing and vibrating the superconducting conductor 2 to the interlayer sheet 3 from above the superconducting conductor 2 using the ultrasonic vibrator 5. Is heated by vibrational friction. In addition, the surface of the beam through-hole surrounding structure 1 and the interlayer sheet 3 is roughened, and a fusing agent layer 4 made of a self-fusing resin is provided thereon. A fusing agent layer 4 is also provided on the surface of the superconducting conductor 2. A phenoxy resin is used as the self-fusing resin constituting the fusing agent layer 4.

  In the superconducting magnet configured as described above, the adhesive layer 4 made of phenoxy resin is applied to the periphery of the superconducting conductor 2 and the interlayer sheet 3, and the ultrasonic transducer 5 is pressed against the superconducting conductor 2. Melting and resolidification by melting the fusing agent layer 4 with frictional heat generated by applying pressure vibration and passing the ultrasonic transducer 5 in the direction of the arrow while pressing it against the superconducting conductor 2. In this process, the fusing agent layer 4 is integrated, and the superconducting conductor 2 is fixed firmly and accurately at a predetermined position. Since the phenoxy resin forming the fusing agent layer 4 is thermoplastic, it can be re-melted unlike a thermosetting resin, so that the work of correcting the winding can be performed and workability can be improved. Moreover, the melting and re-solidification of the phenoxy resin converges in a short time, so that the winding work can be speeded up. Moreover, since the phenoxy resin has a high adhesive strength and has a sufficient adhesive strength even at an extremely low temperature, the conductor does not peel off due to a decrease in the adhesive strength caused by cooling to an extremely low temperature.

  As described above, the superconducting magnet and the manufacturing method thereof according to the present embodiment use a magnetic field generated in a through hole having a through hole in the center and a superconducting conductor wound around the through hole. A superconducting coil manufacturing method in which a coil is formed by winding a superconducting conductor 2 on a structure 1 that is a winding frame around a through-hole in a magnet, and the surface of the superconducting conductor 2 is self-fused. The structure 1 is coated with a fiber reinforced resin that is prepared in advance and is coated with the adhesive layer 4 after roughening the surface and washing it with an organic solvent. Further, after the produced conductor coil is covered with the fiber reinforced resin interlayer sheet 3, the superconducting conductor 2 is wound on the superconducting conductor 2 while being fused and fixed thereon to form a coil. The surface of the conductor 2 is covered with the fusing agent layer 4, and a fiber reinforced resin prepared in advance and coated with the fusing agent layer 4 after roughening the surface and washing with an organic solvent is used for the interlayer sheet 3.

  When only the surface of the superconducting conductor 2 is covered with the fusing agent layer 4, in order to increase the adhesive strength with the structure 1, the fusing agent layer 4 on the surface of the superconducting conductor 2 is deformed to change the surface of the structure 1. It is necessary to adhere to. For this purpose, tension or pressure perpendicular to the superconducting conductor 2 is required.

  In the present embodiment, since the bonding agent layer 4 is applied to both surfaces of the superconducting conductor 2 and the structure 1, even if there is no high tension or pressure, both can be bonded by simply contacting them. By heating, both can be integrated and high adhesive strength can be obtained. As a result, the speed of forming the coil can be increased by winding the superconducting conductor 2 while being fused and fixed to the structure 1 around the through-hole, thereby facilitating the manufacture of a large coil. In addition, since the superconducting conductor 2 and the structure 1 can be fixed without high tension or pressure, it is possible to produce a coil shape that is difficult to apply tension or pressure.

  Since fiber reinforced resin uses fibers such as glass fiber, it has high mechanical strength and can be bent flexibly when processed thinly. In the superconducting magnet, the structure 1 needs to have mechanical strength in order to withstand electromagnetic force generated during operation. On the other hand, the interlayer sheet 3 used in the case of a multilayer coil needs to be bent according to the curved surface of the structure 1. A fiber reinforced resin, in particular a glass fiber reinforced resin having insulating properties, can satisfy such a requirement, and is suitable as the structure 1 and the interlayer sheet 3 in the superconducting magnet of the present embodiment.

  When using a fiber reinforced resin as the structure 1 and the interlayer sheet 3, it is important to ensure adhesion between the fiber reinforced resin and the fusing agent layer 4. There are various methods for improving the adhesiveness. As a result of the investigation experiment, the surface of the fiber reinforced resin is roughened with sandpaper or sandblast, washed with a solvent, and then the fusion agent layer 4 is formed. Has found that the adhesion between the glass fiber reinforced resin and the fusing agent layer 4 can be enhanced most.

  As an example, the adhesion evaluation result of the glass fiber reinforced resin and the fusing agent layer 4 produced on various conditions is shown in FIG. As the surface treatment of glass fiber reinforced resin, surface roughening by sandblasting, application of primer agent (silane treatment system) to improve adhesion, and solvent cleaning were selected, and the glass fiber reinforced resin surface was treated by combining these methods. . A phenoxy resin was used as a fusing agent, and a phenoxy resin varnish was applied to form a fusing agent layer having a thickness of about 50 μm. A tape adhesion test was performed on the sample thus prepared.

  The tape adhesion test is a cross-cut cut with a cutter knife for the coating film to be evaluated, and the cellophane tape is rubbed with a round stick etc. Is strongly peeled off at an angle of about 45 °, and the adhesive strength between the coating film and the substrate is evaluated by the degree of coating film peeling at that time. Typical standards include JIS K5400 8.5.2 cross-cut test and ISO4624 Pull-off Adhesion Test. In this evaluation test, a 10 mm square size was cut in a grid pattern at 1 mm intervals, and the peeled area ratio after peeling the tape was evaluated. As shown in FIG. 4, the best results were obtained by the combination of surface roughening by blasting and solvent cleaning. In this way, by using a fiber reinforced resin that has been prepared in advance, roughened the surface, washed with an organic solvent, and then formed with a fusing agent layer, the complexity of the work process is reduced, and the adhesiveness variation is reduced. The quality can be reduced to stabilize the quality.

  In addition, the superconducting magnet and the manufacturing method thereof according to the present embodiment apply a self-fusible resin dissolved in a solvent to the surface of the fiber reinforced resin constituting the structure 1 and the interlayer sheet 3 and dry it to form a fusion agent layer. 4 is formed. In this method, by adjusting the dilution ratio of the self-fusing resin with the solvent and the number of times of application of the self-fusing resin dissolved in the solvent, a fusing agent of any thickness can be used without using a large-scale apparatus. The layer 4 can be easily formed. In particular, by increasing the solvent dilution ratio, it is possible to produce a thin resin layer of several μm to several tens of μm.

  Further, the superconducting magnet and the manufacturing method thereof according to the present embodiment are prepared by attaching a self-adhesive resin film to the surface of the fiber reinforced resin constituting the structure 1 and the interlayer sheet 3 and heating and pressurizing the adhesive. The layer 4 may be formed. If a film having an appropriate thickness is obtained, a film having a predetermined thickness can be applied to produce the fusing agent layer 4 having a uniform thickness on the surface of the structure 1 and the interlayer sheet 3. it can. Moreover, a large area can be processed at once, and the structure 1 and the interlayer sheet 3 having the fusing agent layer 4 can be produced in a short time.

  Further, in the superconducting magnet and the manufacturing method thereof according to the present embodiment, the surface of the fiber reinforced resin may be covered with the self-bonding resin powder, and heated and melted to form the bonding agent layer 4. . After self-adhesive resin powder is sprayed and fixed on fiber reinforced resin that has been heated in advance, the resin powder is adhered using static electricity, and then heated and melted to melt the self-adhesive resin. The fusing agent layer 4 is formed on the surface of the fiber reinforced resin. In this method, since the powder overlaps and adheres to the surface of the fiber reinforced resin, it is possible to form a thick adhesive layer 4 having a thickness of 100 μm by a single operation.

  Further, the superconducting magnet and the manufacturing method thereof according to the present embodiment are a superconducting magnet that uses a magnetic field generated in the through-hole by a coil having a through-hole in the center and wound with the superconducting conductor 2 around the through-hole. A superconducting coil manufacturing method in which a coil is formed by winding a superconducting conductor 2 while being fused and fixed to a structure 1 around a through-hole. On the surface of the fiber reinforced resin constituting the structure 1 and the interlayer sheet 3 The thickness of the fusion agent layer 4 to be formed is set to 10 μm to 100 μm.

  When the fusing agent layer is thin, the absolute amount of the resin involved in the adhesion between the fiber reinforced resin and the superconducting conductor is reduced, and it is easy to be affected by smears, so the adhesive strength is reduced. FIG. 5 shows the relationship between the thickness of the adhesive layer and the adhesive strength. The surface of the fiber reinforced resin, which has been sandblasted and washed with an organic solvent, is coated with a phenoxy resin diluted with a solvent, and samples with different resin layer thicknesses are prepared by changing the number of coatings. A superconducting wire coated with a thickness of 15 μm was fused. At this time, the fusion length of the fiber reinforced resin and the superconducting wire was unified at 30 mm. Then, the end of the fiber reinforced resin side and the end of the superconducting wire were pulled, and the value when the adhesion was peeled was read as the adhesive strength. As shown in FIG. 5, when the thickness is 5 μm, the strength is remarkably low, and it can be said that a thickness of 10 μm or more is necessary to obtain stable adhesion.

  On the other hand, when the fusing agent layer is thick, the accuracy as described above is required, so that it is difficult to maintain the dimensional accuracy of the coil. Furthermore, in a multilayer coil, an interlayer sheet provided with a pre-adhesive layer is bent and fixed along the lower layer. Therefore, if the adhesive layer is thick, excessive stress is generated in the adhesive layer, and in some cases bending occurs. There is a possibility that the fusing agent layer may break without being able to follow. As a result of considering the above matters, it has been found that the thickness of the fusion agent layer provided on the surface of the fiber reinforced resin is preferably 100 μm or less. Accordingly, an appropriate value is 10 μm or more and 100 μm or less for the thickness of the fusing agent layer provided on the surface of the fiber reinforced resin.

  In addition, the superconducting magnet and the manufacturing method thereof according to the present embodiment use a phenoxy resin, an epoxy resin, a thermoplastic polyimide resin, or a polyamide resin as the self-fusing resin constituting the fusing agent layer 4. The self-bonding resin used in this embodiment is desirably dilutable with a solvent, capable of producing a resin film, or powderable. From this point of view, phenoxy resin, epoxy resin, thermoplastic polyimide resin, and polyamide resin are suitable as the self-bonding resin.

  In addition, the superconducting magnet and the manufacturing method thereof according to the present embodiment are characterized in that superconducting conductor 2, structure 1, and interlayer sheet 3 are fused by ultrasonic fusion. As a method for fusing, a method capable of heating the fusing agent on the surface of the superconducting conductor 2, the structure 1, and the interlayer sheet 3 locally and continuously is preferable because the superconducting conductor needs to be bent at the time of manufacturing the coil. Is the method. The ultrasonic fusion method is a method in which heat is generated by impact between an object that is ultrasonically vibrated and an object that is in contact with the object, and is thus fused. Since it is possible to realize the adhesion, this is a fusion method that can obtain the most excellent characteristics in the coil production of the present embodiment.

  As described above, in the present embodiment, a self-fusing resin such as phenoxy resin is applied to the periphery of the superconducting conductor 2, the outer periphery of the structure 1 around the beam through-hole, and the surface of the interlayer sheet 3, and then fusion-fixed. Thus, the coil is molded, and the positional accuracy of the superconducting conductor 2 at the time of winding can be ensured, the workability can be improved, and the adhesive strength can be secured. Further, the superconducting conductor 2 is vibrated by the ultrasonic vibrator 5, and the fusing agent 4 is fused by utilizing the frictional heat generated between the superconducting conductor 2 and the interlayer sheet 3 to be bonded. This makes it possible to perform local heat-sealing at a high speed without exerting a thermal effect on this portion, to ensure stable superconducting conductor position accuracy, and to improve workability.

  The self-bonding resin constituting the fusing agent layer 4 on the surface of the structure 1 and the self-fusing resin constituting the fusing agent layer 4 on the surface of the interlayer sheet 3 and the surface of the superconducting conductor 2 are fused. The self-bonding resin constituting the agent layer 4 is the same in many cases, but may be different as long as workability, adhesive strength and the like are obtained. Further, the above description has been made with respect to the superconducting magnet of the saddle coil, but the present invention can also be applied to a superconducting magnet of a solenoid type or the like.

The perspective view which shows the superconducting magnet of embodiment of this invention. FIG. 3 is a detailed cross-sectional view of a winding portion of the superconducting magnet according to the embodiment of the present invention. The figure which shows the melt | fusion process by the ultrasonic heating in the manufacturing method of the superconducting magnet of embodiment of this invention. The table | surface which shows the result of the surface treatment of fiber reinforced resin, and the adhesive evaluation test of a binder layer, and demonstrates the effect of the superconducting magnet of embodiment of this invention. The table | surface which shows the evaluation test result of the thickness of a binder layer, and the adhesive strength of a fiber reinforced resin, and demonstrates the effect of the superconducting magnet of embodiment of this invention. Detailed sectional view of a winding portion of a conventional superconducting magnet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Beam through-hole surrounding structure, 2 ... Superconducting conductor, 3 ... Interlayer sheet, 4 ... Fusing agent layer, 5 ... Ultrasonic vibrator, 6 ... Instant adhesive.

Claims (8)

  A winding frame made of a fiber-reinforced resin, roughened on the surface, washed with an organic solvent, and then formed with a fusing agent layer made of a self-fusing resin on the surface, and a fusing agent layer made of a self-fusing resin on the surface. And a superconducting conductor wound around the winding frame, wherein the fusing agent layer of the winding frame and the fusing agent layer of the superconducting conductor are fused.   Interlayer sheet made of fiber reinforced resin, roughened on the surface and washed with an organic solvent, and then formed on the surface with an adhesive sheet made of self-fusible resin, and a fuser layer made of self-fusible resin on the surface A superconducting conductor, and a plurality of layers of the superconducting conductor are wound around the winding frame with the interlayer sheet interposed therebetween, and the fusion agent layer of the interlayer sheet and the fusion agent layer of the superconducting conductor are fused. A superconducting magnet characterized by   The superconducting magnet according to claim 1 or 2, wherein the thickness of the fusing agent layer of the winding frame and the thickness of the fusing agent layer of the interlayer sheet are 10 µm to 100 µm.   Self-fusible resin constituting the fusible layer of the reel, self-fusing resin constituting the fusible layer of the interlayer sheet, and self-fusing resin constituting the fusible agent layer of the superconducting conductor The superconducting magnet according to claim 1 or 2, which is any one of phenoxy resin, epoxy resin, thermoplastic polyimide resin, and polyamide resin.   2. The fusing agent layer of the winding frame or the fusing agent layer of the interlayer sheet is formed by applying a self-fusing resin dissolved in a solvent to the surface of a fiber reinforced resin and drying it. 2. A method for producing a superconducting magnet according to 2.   The fusion agent layer of the winding frame or the fusion agent layer of the interlayer sheet is formed by attaching a self-adhesive resin film to the surface of a fiber reinforced resin and heating and pressing. 2. A method for producing a superconducting magnet according to 2.   2. The fusing agent layer of the winding frame or the fusing agent layer of the interlayer sheet is formed by covering the surface of the fiber reinforced resin with a self-fusing resin powder, heating and melting. Or the manufacturing method of the superconducting magnet of 2. The superconducting magnet according to claim 1 or 2, wherein the superconducting conductor fusion agent layer and the winding frame fusion agent layer or the interlayer sheet fusion agent layer are fused together by ultrasonic fusion. Production method.

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