JP4559834B2 - Manufacturing method of heat conductor - Google Patents

Description

The present invention relates to a method of manufacturing a heat conductor used for cooling the object to be cooled for use under cryogenic conditions.

  In general, in devices that are cooled to cryogenic conditions, such as superconducting magnets, a cooling object is placed in a vacuum-insulated space, and a cooling source such as a refrigerator and the cooling object are thermally connected to cool. Alternatively, a method of cooling by immersing in a refrigerant such as liquid helium is used.

  Among these, the cooling method for thermally connecting the cooling source and the object to be cooled uses a heat conductor typified by a metal material such as copper or aluminum as means for thermally connecting (thermal bridge). It is done. On the other hand, in the case of the immersion cooling method using a refrigerant, a heat conductor may be used to improve the cooling efficiency of a portion that does not come into direct contact with liquid helium, such as the inside of a superconducting coil. Therefore, a material having a high thermal conductivity is used as a heat conductor to improve heat transfer characteristics.

However, when the heat conductor having the above-described configuration is used in an alternating magnetic field, an eddy current is generated, resulting in a problem that the heat conductor itself generates heat due to eddy current loss. In general, this eddy current loss Q _eddy is expressed by the following (formula 1) in an infinite length model. Here, ρ: specific resistance, B: magnetic field, W: plate width.

  As shown in (Equation 1), heat generation due to eddy current increases in proportion to the square of the magnetic field change (dB / dt), and as a result, heat generation exceeding the freezing capacity of the refrigerator is generated in the heat conductor. In some cases, this heat is transferred to the superconducting coil and the temperature of the superconducting coil rises. Further, when the temperature exceeds the critical temperature, quenching (normal conduction transition phenomenon) occurs. When a quench occurs, it is necessary to cool the superconducting coil again and perform excitation again. In some cases, the superconducting coil may be damaged by heat generation.

  For this reason, conventionally, in order to prevent the occurrence of quenching caused by a large magnetic field change, the magnetic field change is reduced by slowing the speed of excitation and demagnetization. Therefore, there is a problem that it takes a long time for excitation and demagnetization. In order to prevent damage to the superconducting coil, it is important to suppress eddy current loss from the viewpoint of improving the device performance.

In order to deal with such problems, as a conventional technique, there is a technique for preventing heat generation due to eddy current loss in a configuration for cooling a superconducting magnet, and a method of dividing a heat conductor into strips as a countermeasure for the above heat generation is known. (For example, refer to Patent Document 1).
JP 2001-244109 A

  Conventionally, the heat conductor constituting the most common thermal bridge has been composed of a single-plate metal material. The thermal bridge preferably has a large cross-sectional area and a large surface area in order to improve heat transfer. However, there is a problem of generating eddy currents in the heat conductor having such a configuration.

  Therefore, the heat conductor as disclosed in the above document is made by coating a wire made of a metal material such as aluminum or copper with a coating of an insulating resin to form a covering material, and joining a plurality of the covering materials. It constitutes a heat conductor. Since the size of the eddy current loop is larger than the cross-sectional area of the heat conductor, eddy current loss can be suppressed by reducing the diameter of the conductor portion of the heat conductor.

  However, narrowing the division width of the heat conductor is accompanied by difficulties in machining, and there is a problem that the manufacturing cost increases due to an increase in manufacturing steps. Therefore, the practical division width is limited to about several mm.

  Thus, although making the conductor part of a heat conductor small diameter is an effective means for suppression of an eddy current, the manufacturing method of a heat conductor still needed improvement. At the same time, a heat conductor having a structure excellent in machinability and handling at the time of manufacture and use of the product has been expected.

  In other words, it is a material that has good thermal conductivity under cryogenic conditions, has excellent workability and handleability, can effectively dissipate the heat of the heating element under cryogenic conditions, There has been a demand for a heat conductor that suppresses the generation of current and its influence, and a method for reducing the manufacturing cost of the heat conductor.

The present invention has been made to solve the problems described above, while providing good thermal conductivity, and an object thereof is to provide a method of manufacturing a heat conductor to reduce the heat generation due to eddy current loss.

In order to solve the above-described problems, the method of manufacturing a heat conductor according to the present invention winds a covering material formed by applying an insulation coating to a wire made of a heat conduction material around a cylindrical mold in a coil shape. A molding material is fixed and integrated to form a cylindrical body, and at least one portion of the cylindrical body is cut at a point on the circumference of the cylindrical body to obtain a belt-shaped heat conductor It is a method to do.

  In addition, in order to solve the above-described problems, the method of manufacturing a heat conductor according to the present invention includes a wire formed of a heat conductive material and an insulating material in a coil shape in a cylindrical mold so that the wire does not short-circuit. Are alternately wound around, and a molding material is fixed and integrated to form a cylindrical body, and the cylindrical body is cut at least at one point on the circumference of the cylindrical body to form a belt-like heat conduction A method characterized by obtaining a body.

According to the method for producing a thermal conductor of the present invention, heat having high thermal conductivity that is excellent in workability and handleability, and can effectively dissipate heat of an object to be cooled under extremely low temperature conditions. It is possible to provide a conductor and a method for manufacturing the conductor, and it is possible to suppress the generation of eddy current and the influence thereof when the object to be cooled is radiated.

Embodiments of a method for manufacturing a heat conductor according to the present invention and a heat conductor obtained by the method will be described in detail below with reference to the drawings. In the following examples, the longitudinal direction of the heat conductor indicates the direction along the wiring direction of the heat conductor that connects the object to be cooled and the refrigerator, and the long side of the heat conductor formed into a substantially rectangular shape The direction of is not necessarily meant.

[Example 1]
The thermal conductor of Example 1 of this invention is demonstrated using FIGS. 1-3.

  In FIG. 1, the structure of the superconducting coil apparatus 10 using the heat conductor of this invention is shown. In this superconducting coil device 10, the superconducting coil 1 is thermally connected to the refrigerator 3 by a heat conductor 2. All these components are enclosed in a vacuum insulation container 4. The superconducting coil 1 and the refrigerator 3 are connected to a power source outside the vacuum heat insulating container 4 by electrode leads (not shown).

  The superconducting coil 1 is excited by supplying power from an external power source, and is operated up to the rated magnetic field. After the operation is completed, the current is gradually decreased to demagnetize. At this time, the superconducting coil 1 generates heat due to heat flowing from outside and heat generated by AC loss. When this heat flows into the refrigerator 3 by the heat conductor 2, the temperature of the superconducting coil 1 is maintained at minus 200 tens of degrees. Thus, the superconducting coil 1 is cooled by the refrigerator 3 via the heat conductor 2 in the heat insulating vacuum vessel 4.

  FIG. 2 is a cross-sectional view in the width direction showing the detailed structure of the heat conductor 2. FIG. 3 is a longitudinal sectional view taken along line III-III of the heat conductor 2 shown in FIG.

  As shown in FIGS. 2 and 3, the heat conductor 2 is formed in a sheet shape by applying an insulating coating 16 to a wire 15 made of high purity aluminum having high thermal conductivity and bundling the thus configured coating material 17. The whole is integrated with the molding material 18.

  The wire 15 may be made of a material having excellent thermal conductivity other than high-purity aluminum. For example, a metal material such as high-purity copper can be used. The wire 15 is provided with a diameter of about 1 mm, for example, and the surface of the wire 15 is coated with an insulating coating 16 so as to have a thickness of about 0.1 mm. The material used for the insulating coating 16 is preferably a material having good electrical insulation. On the other hand, as the molding material 18, an epoxy resin excellent in electrical insulation and mechanical strength characteristics is preferably used. Further, as the molding material 18, a material such as varnish may be used instead of the epoxy resin which is an insulating material.

  In the heat conductor 2 of the present embodiment configured as described above, the heat generated in the superconducting coil 1 is transferred to the refrigerator 3 by conduction heat transfer via the high purity aluminum wire 15 having high thermal conductivity. Therefore, the temperature difference between the superconducting coil 1 and the refrigerator 3 is suppressed to be small. On the other hand, even if a fluctuating magnetic field is generated by applying alternating current to the superconducting coil 1, the eddy current in the heat conductor 2 has a sufficiently small amount of heat generation because the size of the loop is suppressed to about the diameter of the wire 15. It is suppressed.

  The manufacturing method of the thermal conductor of a present Example is demonstrated using sectional drawing in alignment with the VV line | wire in FIG. 4 and the side view of FIG.

  First, a covering material 17 formed by applying an insulating coating 16 to a wire 15 is wound around a cylindrical forming die 19 in a spiral shape and formed like a coil. At this time, it winds up densely so that the gap | interval of coating | covering materials 17 may not be vacant. Next, the molding material 18 is fixed to the wound coil-shaped molded body by means such as coating. The wire rods 15 are tightly fixed to each other by the molding material 18 to form an integrated cylindrical tubular body. This cylindrical body is cut at an arbitrary point in at least one place in the circumferential direction.

  In addition, the heat conductor 2 of desired length can be obtained by changing the cutting position of a cylindrical cylinder, or the diameter of the shaping | molding die 19 with the length of a heat conductor. For example, if the circumference of the mold 19 is made equal to the length necessary for the heat conductor 2, the heat conductor 2 can be obtained by cutting one place in the circumferential direction. Further, the width of the heat conductor 2 can be adjusted by the number of times the covering material 17 is wound around the mold 19. Further, the mold 19 may be a bobbin type as shown in FIG. 4 or a simple columnar shape.

  On the other hand, in addition to the manufacturing method by winding around the molding die 19, the coating material 17 is arranged on an arbitrary number of flat surfaces, and the molding material 18 is fixed thereto by means such as coating, whereby the heat conductor 2 is manufactured. It is also possible.

  2 and FIG. 3, the covering material 17 has a structure in which the covering materials 17 are in close contact with each other. For example, the covering material 17 and the covering material 17 are separated from each other, and the gap is formed between the molding materials 18. However, considering the heat transfer performance of the heat conductor 2, a structure in which the covering materials 17 are in close contact with each other is preferable.

  According to the heat conductor 2 of the present embodiment, eddy current heat generation can be suppressed to a small value while maintaining good heat transfer characteristics. That is, since the diameter of the wire 15 corresponds to the plate width W in (Expression 1), the eddy current loss caused by the generation of the eddy current in the heat conductor 2 due to the magnetic field change in the superconducting coil 3 can be kept low. Heat generation in the heat conductor 2 can be suppressed.

  Thus, the heat conductor 2 of the present embodiment can be easily molded by being wound around the cylindrical mold 19, and can be very easily configured to have an arbitrary length and width. It is. Therefore, it is possible to obtain the heat conductor 2 having good heat conductivity and having the optimum length for the apparatus to be used at a low cost.

[Example 2]
Next, the heat conductor of Example 2 of this invention is demonstrated using FIG. In addition, about the structure same as the heat conductor of Example 1 in a following example, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In the heat conductor 21 showing the cross section in the width direction in FIG. 6, the insulating material sheet 22, which is an insulating material, is disposed between the wire materials 15 without insulatingly covering the wire material 15, and this is integrated with the molding material 18. It is configured in a band shape.

  That is, in the heat conductor of the present invention, the wire 15 having a small cross-sectional area may be electrically insulated from each other, and the entire surface area of the wire 15 may not be previously coated. Therefore, the heat conductor 21 of the present embodiment is configured by electrically insulating the wire 15 and the wire 15 by the insulating material sheet 22.

  A method for manufacturing the heat conductor 21 will be described below with reference to FIG.

  First, the wire 15 and the insulating material sheet 22 are wound up on the mold 19 so that they are alternately wound without any gap. At this time, in order to prevent a short circuit, it winds up so that the wire 15 may not contact. In this way, the molding material 18 is fixed to the surface of the molded body wound up in a coil shape by means such as coating and integrated, and then cut into a desired length to obtain the heat conductor 21.

  Since the heat conductor 21 of the present embodiment can omit the step of covering the surface of the wire 15 with an insulating material in the manufacturing process, the heat conductor is manufactured by a more simplified manufacturing process. Is possible.

[Example 3]
In FIG. 8, sectional drawing of the width direction of the heat conductor of Example 3 of this invention is shown.

  The heat conductor 31 shown in FIG. 8 is configured to ensure insulation between the high-purity aluminum wires 15 by alternately arranging the wires 15 and the threads 32 of the insulating material that is an insulating material.

  Moreover, the manufacturing method of the heat conductor 31 of a present Example replaces the insulating material sheet 22 in Example 2 with the thread | yarn 32 of an insulating material, and the manufacturing method is illustrated in FIG.

  That is, as shown in FIG. 9, the wire 15 and the insulating material thread 32 are wound around the forming die 19 so as to be alternately wound without any gap. At this time, the wires 15 are wound up so as not to contact each other. Next, the insulating material thread 32 is further wound around the portion where the insulating material thread 32 is wound to ensure electrical insulation between the wires 15.

  In this way, the molding material 18 is fixed to the material wound up in a coil shape by means such as coating, integrated, and cut into a desired length to obtain the heat conductor 31.

  As described above, in the manufacturing process of the heat conductor 31, the insulating yarn 32 may be wound twice, and the two yarns 32 may be interposed in the gap between the wires 15. The diameter of each of the yarns 32 may be increased, or the like may be arranged one by one in the gap between the wires 15. In this case, the manufacturing process can be further simplified.

  Since the heat conductor 31 of the present embodiment can omit the step of covering the wire 15 in the manufacturing process, the heat conductor can be manufactured by a more simplified process.

[Example 4]
In FIG. 10, sectional drawing of the longitudinal direction of the heat conductor of Example 4 of this invention is shown.

  The heat conductor 41 of Example 4 is obtained by twisting a coating material 17 obtained by applying an insulating coating 16 to a wire 15 in a double spiral shape and fixing the coating material 17 to a mold 18.

  In the heat conductor constituted by arranging the covering materials 17 in a straight line, electrical insulation may be impaired by a short circuit between the wire materials 15 rarely at the end in the longitudinal direction. In such a case, a loop having a large diameter is formed, which may cause a large eddy current loss and generate heat.

  In order to prevent such an inconvenience, the heat conductor of the present embodiment twists the covering materials 17 two by two to form a double helix. Thus, the following effects can be acquired by twisting the coating | covering material 17. FIG. That is, the twisted covering material 17 forms a loop having a small diameter in the longitudinal direction by the two covering materials 17. As a result, the induced voltage is lowered and heat generation due to eddy current loss can be reduced.

  The manufacturing method of the heat conductor 41 of a present Example is demonstrated. The manufacturing method of this heat conductor 41 is substantially the same as the manufacturing method of the heat conductor 2 of Example 1, and in the case of the heat conductor 2, the coating | covering material 17 is wound around the shaping | molding die 19 independently. On the other hand, the heat conductor 41 differs only in that it is manufactured by the following process.

  First, the two covering materials 17 are twisted together to form a double helix. Next, the two covering materials 17 twisted together are wound around the mold 19. The molding material 18 is fixed thereto by means such as coating, and a cylindrical body is molded. The cylindrical body is cut into a desired length to obtain the heat conductor 41.

  Moreover, you may manufacture the heat conductor 41 of a present Example as follows. That is, first, the covering materials 17 twisted together are arranged on a flat surface, and the molding material 18 is fixed thereto by means such as coating or the like.

[Example 5]
In FIG. 11, sectional drawing of the longitudinal direction of the heat conductor of Example 5 of this invention is shown.

  The heat conductor 51 of the present embodiment is configured such that only a part thereof is integrated with the molding material 18 in the longitudinal direction of the covering material 17.

  As described above, by alternately providing the portion fixed by the molding material 18 and the portion not integrated in the longitudinal direction of the heat conductor 51, the flexibility of the heat conductor 51 is improved, and the superconducting coil 1 or the like. The construction for thermally connecting the object to be cooled and the refrigerator 3 is simplified. In addition, the layout of the components in the apparatus is facilitated, and the flexibility of the apparatus design can be improved.

  The manufacturing method of the thermal conductor 51 of the present embodiment is almost the same as the manufacturing method of the thermal conductor 2 of the first embodiment shown in FIG. 4, but after the coating material 17 is wound around the molding die 19, the molding material is 18 is manufactured by partially fixing the mold 19 in the circumferential direction, and the portions fixed by the molding material 18 and the portions where the covering material 17 is exposed are alternately provided.

[Example 6]
In FIG. 12, sectional drawing of the longitudinal direction of the heat conductor of Example 6 of this invention is shown.

  The heat conductor 61 of the present embodiment has a contact heat resistance between the covering material 17, the superconducting coil 1, and the refrigerator 3 by providing a terminal plate 62 at the end of the wire 15 to increase the heat transfer area. The configuration is reduced.

  The manufacturing method of the heat conductor 61 is substantially the same as that of the heat conductor 2 of the first embodiment. That is, after cutting the cylindrical body obtained by the same method as the heat conductor 2 of Example 1 to a desired length, the molding material 18 at the end in the longitudinal direction is removed by an appropriate length, The insulation coating 16 of the coating material 17 in this portion is peeled off to expose the wire 15 and the terminal board 62 is fixed thereto.

  Alternatively, the terminal plate 62 may be formed by processing and deforming the end of the wire 15.

  Alternatively, in the step of applying the molding material 18, the exposed portion of the wire 15 is provided in advance as in the thermal conductor 51 of Example 5, and the cylindrical body is cut in accordance with this portion to manufacture the thermal conductor 61. You may do it.

[Example 7]
In FIG. 13, sectional drawing of the longitudinal direction of the heat conductor of Example 7 of this invention is shown.

  The thermal conductor 71 of the present embodiment peels off the insulating coating 16 at the end of the coating material 17, and all the wires 15 are directly combined into aluminum nitride 72 which is a good electrical insulation material while having a high thermal conductivity. By making it contact, it is set as the structure which reduces the contact thermal resistance of a connection part.

  The method for manufacturing the heat conductor 71 is substantially the same as the method for manufacturing the heat conductor 61 of the sixth embodiment. That is, after the coating material 17 is wound around the molding die 19, the molding material 18 is fixed by means such as coating, but at this time, a portion where the molding material 18 is not fixed is formed in part, and at this portion, a cylindrical shape is formed. Cut the body. The insulating material 16 of the covering material 17 at the end of the obtained material is peeled off, and the exposed wire 15 is covered with the aluminum nitride 72, whereby the heat conductor 71 can be obtained.

  Alternatively, the wire 15 is exposed at the end of the heat conductor 2 manufactured as in Example 1.

  Compared with the manufacturing method of the heat conductor 61 of Example 6, the heat conductor 71 by such a structure and manufacturing method can simplify a process more.

The block diagram which shows the general cooling structure of the superconducting coil apparatus using the heat conductor of this invention. Sectional drawing of the width direction of the heat conductor of Example 1. FIG. Sectional drawing of the longitudinal direction of the heat conductor of Example 1 which follows the III-III line of FIG. The side view which shows the manufacturing method of the heat conductor of Example 1. FIG. Sectional drawing which follows the VV line of the side view of FIG. Sectional drawing of the width direction of the heat conductor of Example 2. FIG. The side view which shows the manufacturing method of the heat conductor of Example 2. FIG. Sectional drawing of the width direction of the heat conductor of Example 3. FIG. The side view which shows the manufacturing method of the heat conductor of Example 3. FIG. Sectional drawing of the longitudinal direction of the heat conductor of Example 4. FIG. Sectional drawing of the longitudinal direction of the heat conductor of Example 5. FIG. Sectional drawing of the longitudinal direction of the heat conductor of Example 6. FIG. Sectional drawing of the longitudinal direction of the heat conductor of Example 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Superconducting coil 2 Thermal conductor 3 Refrigerator 4 Vacuum insulation container 15 Wire material 17 Molding material 16 Insulation coating 18 Molding material 19 Molding die 21 Thermal conductor 22 Insulating material sheet 31 Thermal conductor 32 Insulating material thread 41 Thermal conductor 51 Thermal conductor 61 Thermal conductor 62 Terminal plate 71 Thermal conductor 72 Aluminum nitride plate

Claims (5)

A coating material formed by applying an insulating coating to a wire made of a heat conductive material is wound around a cylindrical mold in a coil shape, and the molding material is fixed and integrated to form a cylindrical body. A method for producing a thermal conductor, comprising: cutting the cylindrical body at a point on the circumference of the substrate to obtain a strip-shaped thermal conductor. Two coating materials are twisted together to form a double helix, the double helix coating material is wound around the mold, and the molding material is fixed and integrated to form a cylindrical body. The method for producing a heat conductor according to claim 1, wherein the tubular body is cut at least at one point at a point on the circumference of the tubular body to obtain a belt-like heat conductor. After the covering material is wound around the molding die in a coil shape, the molding material is partially fixed in the circumferential direction of the molding die to form a cylindrical body, and a point on the circumference of the cylindrical body is formed. The heat conductor in which the portion fixed by the molding material and the portion where the covering material is exposed is obtained by cutting the cylindrical body at least at one place. Of manufacturing a thermal conductor. A wire made of a heat-conducting material and an insulating material are alternately wound in a coil shape around a cylindrical mold so that the wire does not short-circuit, and the molding material is fixed and integrated to form a cylindrical body. A method for producing a heat conductor, characterized in that a strip-shaped heat conductor is obtained by cutting at least one portion of the cylindrical body at a point on the circumference of the cylindrical body. 5. The method of manufacturing a heat conductor according to claim 4, wherein the insulating material is in a sheet form or a thread form.

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