Heating device, aluminum melting device, and die heating device

Abstract

Provided is a heating device capable of achieving appropriate induction heating. For this purpose, a heating device (100) is provided with a magnetic field source (24) that heats an object to be heated (12) which contains a metal by applying a magnetic field to a work region (SP), which is a region for heating the object to be heated (12), via a superconducting coil (7) obtained by winding a superconducting wire, and that moves relative to the work region (SP). The magnetic field source (24) comprises a magnetic shield (9) that suppresses a leakage field, from among the magnetic field generated by the magnetic field source (24), which leaks externally, and that moves at the same speed as the magnetic field source (24).

Description

Heating equipment, aluminum melting equipment and mold heating equipment

[0001] The present invention relates to a heating device, an aluminum melting device, and a mold heating device.

[0002] Today, lightweight and corrosion-resistant aluminum and aluminum alloys are used as structural materials in a variety of products. Casting has advantages when it comes to forming complex three-dimensional shapes, and aluminum die casting is used to create precision products. Aluminum die casting is a casting method in which molten metal, such as an aluminum alloy, is injected into a mold and shaped under pressure, making it possible to mass-produce high-precision, high-quality castings. In casting methods such as aluminum die casting, the raw material aluminum alloy is first melted to form a molten metal, which is then poured into a mold (metal mold, sand mold) to produce the molded product.

[0003] These casting processes require heating to melt the raw materials and preheat the molds, etc., and heating is done using gas, electricity, etc., but the aluminum rolling industry is also working toward becoming carbon neutral, and there is a demand for more efficient heating processes to reduce CO2 emissions. Billet heaters are used to preheat aluminum billets in the aluminum extrusion process, and methods such as combustion gas and high-frequency induction heating are commonly used for preheating.

[0004] However, heating methods using combustion gas to heat the surface of an object to be heated are difficult to achieve uniform heating. Furthermore, high-frequency induction heating methods tend to heat the surface side, just like gas, resulting in increased Joule loss in the coil (electromagnet) and conductor used to generate the high-frequency magnetic field. Therefore, Patent Document 1 and Non-Patent Document 1 listed below describe technology related to induction heating devices using superconducting magnets. The descriptions in these documents are incorporated herein by reference.

[0005] Special Publication No. 2010-537376

[0006] Werner Prusseit, "Superconductor Industry in Germany: Status and Perspectives," IEEE / CSC & ESASEUROPEAN SUPERCONDUCTIVITY NEWS FORUM, No. 4, April 2008 [online], [Retrieved July 11, 2023], Internet <URL: https: / / snf.ieeecsc.org / sites / ieeecsc.org / files / RN6_Final_042108.pdf >

[0007] However, there is a demand for more appropriate induction heating in the above-mentioned technology. The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a heating device, an aluminum melting device, and a mold heating device that can achieve appropriate induction heating.

[0008] In order to solve the above problems, the heating device of the present invention heats an object to be heated, including metal, by applying a magnetic field to a working area, which is an area where the object to be heated is heated, using a superconducting coil wound with superconducting wire, and is characterized in that it is equipped with a magnetic field generating source that moves relative to the working area, and the magnetic field generating source suppresses leakage magnetic field of the magnetic field generated by the magnetic field generating source that leaks to the outside, and is equipped with a magnetic shield that moves at the same speed as the superconducting coil.

[0009] According to the present invention, appropriate induction heating can be achieved.

[0010] It is a schematic cross-sectional view of a heating device according to the first embodiment. It is a schematic perspective view of a superconducting coil. It is a schematic perspective view of the superconducting coil in the first - 1 modification. It is a schematic plan view of the same superconducting coil. It is a schematic cross-sectional view of the superconducting coil in the first - 2 modification. It is a schematic perspective view of the superconducting coil in the first - 3 modification. It is a schematic perspective view of the main part of the first - 4 modification. It is a schematic cross-sectional view of the superconducting coil in the first - 5 modification. It is a schematic cross-sectional view of the superconducting coil in the first - 6 modification. It is a schematic cross-sectional view of the superconducting coil in the first - 7 modification. It is a schematic cross-sectional view of a heating device according to the second embodiment. It is a schematic perspective view of the superconducting coil in the second embodiment. It is a schematic side view of the superconducting coil in the second embodiment. It is a schematic perspective view of a superconducting coil applied to the heating device of the third embodiment. It is a schematic side view of a four-stage superconducting coil in the heating device of the third embodiment. It is a schematic cross-sectional view of a heating device according to the fourth embodiment. It is a schematic perspective view of a magnetic field generation source. It is a schematic cross-sectional view of a heating device according to the fifth embodiment. It is a schematic diagram of a vacuum die-casting device according to the sixth embodiment.

[0011] [Overview of the Embodiment] When applying the technology described in Non-Patent Document 1, heating using the strong magnetic field of a superconducting magnet can be realized. This method inserts and rotates an aluminum billet in a strong DC magnetic field created by a superconducting magnet, and by moving the metal (aluminum billet) in the magnetic field, an induced current is generated in the metal, and heating is performed with that current.

[0012] In the method of rotating an aluminum billet in a superconducting DC magnetic field, since the magnetic field strength is large, the rotation frequency can be made small, and by allowing the magnetic field to penetrate to the inside of the billet without being affected by the skin effect, uniform heating can be achieved. Furthermore, almost all of the energy input for mechanically rotating the aluminum billet can be converted into heat generation of the aluminum billet. Thereby, Joule loss can be reduced and the efficiency can be significantly improved. Thus, the heating method using a strong superconducting magnetic field has attracted attention because it contributes to carbon reduction.

[0013] However, in order to heat an object to be heated in a fixed DC magnetic field created by a superconductor, the object must be rotated, which limits the shape of the object to be heated. Furthermore, because the object to be heated must be rotated, if the object to be heated melts, it will be deformed by centrifugal force and the rotational force itself will not be applied. Therefore, in order to heat an object of any shape, it is necessary to fix the object to be heated and rotate the magnet side. For example, by applying the technology described in Patent Document 1, it is thought that a magnetic field can be applied by rotating a superconducting magnet around the object to be heated.

[0014] When introducing a strong magnetic field source such as a superconducting magnet into a production process, it is preferable to prevent leakage of the magnetic field. To achieve this, measures such as a passive magnetic shield using a magnetic material or a shield coil that generates a reverse magnetic field can be considered. By applying the technology of Patent Document 1, it is possible to utilize the external magnetic field generated by the superconducting magnet and apply a driving force to the superconducting magnet using a coil installed outside the superconducting magnet. To obtain a shielding effect using an electromagnet to rotate the superconducting magnet, it is necessary to generate a magnetic field as strong as the magnetic field generated by the superconducting magnet. This is not realistic because it weakens the magnetic field in the heated object. Furthermore, a yoke is installed on the outer coil, and it may appear that this yoke can shield the magnetic field. However, this yoke is subjected to the strong rotating magnetic field generated by the superconducting coil, resulting in significant heat generation.

[0015] Therefore, the embodiments described below provide a heating device using a superconducting magnet with a small leakage magnetic field. In the embodiments described below, in order to reduce the leakage magnetic field, a magnetic circuit (yoke) is formed using a magnetic material, and the speed of this magnetic circuit is matched with the speed of the moving superconducting magnet. This makes it possible to realize an induction heating device with a rotating superconducting magnet that has a small leakage magnetic field.

[0016] [First Embodiment] <Overall Structure of First Embodiment> Figure 1 is a schematic cross-sectional view of a heating device 100 according to the first embodiment. The heating device 100 is a rotary magnet type heating device and includes a rotary magnet 20, a vessel 30, and a motor 40. The rotary magnet 20 includes a magnetic field generating source 24, a power shaft portion 25, an insulating load support 26, and an insulating layer 28. The vessel 30 functions as a cryostat and includes a housing 32 and an insulating layer 34.

[0017] The motor 40 drives the rotary magnet 20 to rotate. The magnetic field generating source 24 includes a superconducting coil 7, an iron magnetic pole 8, and a return yoke 9. The power shaft 25 is formed in a substantially cylindrical shape, and a substantially cylindrical space that is a part of its internal space forms a working area SP where the metallic object to be heated 12 is heated. A heat insulating layer 28 is provided between the power shaft 25 and the magnetic field generating source 24 and heat insulating load support 26.

[0018] <Rotary magnet 20> (Superconducting coil 7) Figure 2 is a schematic perspective view of the superconducting coil 7. The superconducting coil 7 includes windings 161 and 162. The winding 161 is generally called a saddle coil, and has a shape in which a rectangular frame is curved approximately halfway around the cylindrical circumferential surface (not shown). In other words, the superconducting wire is wound around this shape. The winding 162 is formed in the same shape as the winding 161 and is disposed opposite the winding 161.

[0019] However, the superconducting coil 7 may take any form, and may be configured, for example, by placing racetrack coils facing each other across the working area SP. In this type of racetrack coil configuration, the magnetic field generated outside the coil is used, resulting in poor utilization of the coil (magnetomotive force). Therefore, it is preferable to use a saddle-type coil, as shown in FIG. 2, even though the winding process is more complicated.

[0020] (Iron poles 8 and return yoke 9) Returning to Fig. 1 , the return yoke 9 is formed in a substantially cylindrical shape so as to surround the superconducting coil 7 and the iron poles 8, and is disposed coaxially with the power shaft portion 25. The return yoke 9 has the function of returning the magnetic flux generated by the superconducting coil 7 to the superconducting coil 7 so as to minimize leakage to the outside. The iron poles 8 protrude inward from the return yoke 9 and pass through the hollow portion of the superconducting coil 7. As a result, the magnetic field generating source 24 is formed in a substantially cylindrical shape that surrounds the outer periphery of the power shaft portion 25.

[0021] (Adiabatic Load Support 26) The adiabatic load support 26 is attached to the power shaft 25 and supports while insulating the magnetic field generation source 24. This allows the rotary magnet 20, which includes the magnetic field generation source 24, the power shaft 25, and the adiabatic load support 26, to rotate relative to the vessel 30.

[0022] When using the heating device 100 to melt the object 12 to be heated, the object 12 is placed into the working area SP from one end (e.g., the upper end in the figure) of the power shaft 25. The object 12 is then heated and melted by the rotating magnet 20, and the molten object 12 is removed from the other end (e.g., the lower end) of the power shaft 25. This allows the heating device 100 to continuously melt the object 12 to be heated.

[0023] (Rotation axis L1 and transport axis L2) Here, the rotation axis of the power shaft unit 25 is referred to as L1 (first axis), and the flow line along which the object to be heated 12 is inserted into the power shaft unit 25 is referred to as the transport axis L2 (second axis). In the illustrated example, the rotation axis L1 and the transport axis L2 coincide, but they do not necessarily have to coincide. However, in this embodiment, the rotation axis L1 and the transport axis L2 are approximately parallel to each other.

[0024] The magnetic field generator 24 generates a magnetic field in a direction generally perpendicular to the transport axis L2. As the rotary magnet 20 rotates, the positional relationship of the magnetic field generator 24 with respect to the object to be heated 12 changes, thereby inducing eddy currents inside the metallic object to be heated 12 and heating the object to be heated 12. In other words, as the magnetic field generator 24 rotates around the rotation axis L1, a rotating magnetic field is applied to the working space SP, and an induced current that shields this rotating magnetic field is induced inside the object to be heated 12. The object to be heated 12 is then heated from within by Joule heating due to the electrical resistance of the object to be heated 12.

[0025] (Rotational Speed ​​of Rotary Magnet 20) Next, the rotational speed of the rotary magnet 20 will be described. Generally, when a fluctuating magnetic field is applied to a metal body, the frequency f at which the applied magnetic field changes and the characteristics of the metal body (electrical conductivity σ, relative permeability μ r ), the depth to which the fluctuating magnetic field penetrates into the metal body changes depending on the fluctuating magnetic field. The depth at which the strength of the fluctuating magnetic field that has penetrated into the metal body becomes "1 / e" (e is Napier's number = 0.2718...) of the strength of the external fluctuating magnetic field that has been applied is called the skin depth δ, and is expressed by the following formula (1). In the following formula (1), μ0 is the magnetic permeability in a vacuum.

[0026]

[0027] If the frequency f becomes too high, the skin depth δ becomes small, resulting in eddy currents flowing almost exclusively on the surface of the object to be heated 12. Therefore, although depending on the material and shape of the object to be heated 12, it is desirable to set the frequency f to 10 Hz or less. Here, if the number of pole pairs of the rotating magnet 20 is p, the rotation speed of the rotating magnet 20 that achieves the frequency f is 60 f / p rpm. Meanwhile, since the current induced inside the object to be heated 12 is proportional to the rate of change (dB / dt) of the magnetic field B (not shown), it is desirable to increase the rate of change (dB / dt) in order to heat the object to be heated 12.

[0028] In order to induce a current large enough to heat the object 12, it is preferable to increase the amplitude of the fluctuating magnetic field, and a superconducting magnet is used to obtain this magnetic field. Superconducting magnets must be operated at temperatures sufficiently lower than the critical temperature of the superconducting material (the temperature at which superconductivity is exhibited), and are usually housed inside a vacuum insulated container (cryostat) and cooled and operated using a refrigerator or refrigerant.

[0029] (Adiabatic Load Support 26) Because the power shaft section 25 is in the normal temperature (room temperature) range and the superconducting coil 7 needs to be maintained at an extremely low temperature, a sufficient insulating distance is required between the power shaft section 25 and the superconducting coil 7. For this reason, the adiabatic load support 26 is configured to be zigzag and made of a material with low thermal conductivity, such as alumina FRP or stainless steel.

[0030] In this embodiment, by providing the iron magnetic pole 8 and the return yoke 9, the magnetomotive force of the superconducting coil 7 is effectively utilized, and the magnetic field strength in the working region SP can be increased. Furthermore, the magnetic shielding effect of the return yoke 9 makes it possible to reduce the leakage magnetic field of the heating device 100. In this way, by including the return yoke 9 in the magnetic field generating source 24 and moving it integrally with the superconducting coil 7, the return yoke 9 is not subjected to a fluctuating magnetic field.

[0031] As a result, almost no current is induced in the return yoke 9, and heat generation due to the induced current is extremely small. In order to realize a rotary heating device 100 with a small leakage magnetic field, it is most preferable that the rotation speed of the return yoke 9 and the rotation speed of the superconducting coil 7, which is the source of the magnetic field, are the same.

[0032] <Container 30> The housing 32 of the container 30 includes a cylindrical portion 32a formed in a substantially cylindrical shape and a pair of annular portions 32b formed in annular shapes. The cylindrical portion 32a is formed in a substantially cylindrical shape so as to surround the outer periphery of the magnetic field generating source 24. A pair of annular portions 32b are joined to both ends of the cylindrical portion 32a, and the power shaft portion 25 of the rotary magnet 20 is inserted into the hollow portions of these annular portions 32b. The heat insulating layer 34 is formed so as to cover the inner surfaces of the cylindrical portion 32a and the annular portions 32b.

[0033] Because the rotary magnet 20 includes the superconducting coil 7, a cryostat is required that can rotate the superconducting coil 7 while cooling it and maintaining a low temperature. As described above, in this embodiment, the vessel 30 functions as the cryostat. An insulating vacuum layer, insulating foam, or the like can be used as the insulating layer 34 formed on the vessel 30. In this way, the insulating layer 34 provided on the vessel 30 and the insulating layer 28 provided on the power shaft portion 25 reduce heat penetration from the outside into the vessel 30.

[0034] The inside of the container 30 is filled with a refrigerant gas (not shown) such as helium gas, and the superconducting coil 7 is cooled via this refrigerant gas. Various specific cooling methods are possible, and the cooling method is not particularly limited. For example, it is possible to directly introduce the refrigerant gas from a port (not shown) provided in the stationary container 30. As another example, it is also possible to attach a refrigerator (not shown) to the container 30 and cool the refrigerant gas via a heat exchanger.

[0035] Because the rotary magnet 20 rotates relative to the stationary container 30 filled with refrigerant gas, a rotatable seal (not shown) is enclosed between the power shaft 25 and the container 30. A magnetic fluid seal is preferably used as the seal between the container 30 filled with refrigerant gas and the power shaft 25. However, an elastomer seal may also be used depending on the seal dimensions and rotation speed.

[0036] <Operation Method (Excitation Method) of Superconducting Coil 7> The operation method of the superconducting coil 7 is preferably persistent current mode operation. Persistent current mode operation is one of the operation (excitation) methods of the superconducting coil 7, in which the superconducting coil 7 and an excitation circuit (not shown) are constructed of superconducting wire, and a superconducting closed circuit is formed including the connection parts. In other words, this operation method utilizes the fact that the current injected into the superconducting closed circuit does not decay to the extent that it can be considered to flow permanently. To inject current into the superconducting closed circuit, it is preferable to use a persistent current switch (PCS) (not shown). When injecting or emitting current into or from the superconducting closed circuit, this persistent current switch is in a normal conducting state. After that, once current is injected into the superconducting closed circuit, the current continues to flow permanently, eliminating the need for an external current supply.

[0037] 1, an excitation circuit for the superconducting coil 7 is not shown. This excitation circuit is, for example, an excitation cable laid along the power shaft portion 25, and supplies current to the superconducting coil 7. In persistent current mode operation, once current is supplied to the superconducting coil, the power supply can be disconnected. Therefore, it is advisable to connect an external power supply to the rotating magnet 20 while it is stationary, and then disconnect the power supply after exciting the superconducting coil 7.

[0038] This eliminates the need to provide a special current introduction rotary terminal for the rotating magnetic field generating source 24. However, the operation method of the superconducting coil 7 is not limited to the persistent current mode operation, and the rotating magnet 20 may be operated by constantly supplying current from an external power source when it is rotating. In this case, it is preferable to install a slip ring (not shown) on the power shaft portion 25 to supply current.

[0039] <Method for Reducing Leakage Magnetic Field> Reducing the leakage magnetic field is preferable when deploying a rotary magnet heating device 100 at a manufacturing site. If the heating device 100 is brought into a manufacturing site without limiting the leakage magnetic field, an accident such as attraction to nearby magnetic materials may occur. Furthermore, the fluctuating leakage magnetic field may generate eddy currents in the surrounding metal, causing it to heat up. Therefore, it is preferable to provide a magnetic shield to reduce the leakage magnetic field. One possible form of magnetic shield is to place a ferromagnetic material around the superconducting coil 7 so that the magnetic flux generated by the superconducting coil 7 is closed. This is called a passive shield. Another possible form is to place an electromagnet, i.e., a shield coil, around the coil to generate a magnetic field opposite to the magnetic field generated by the superconducting coil 7 outside. This is called an active shield.

[0040] When a passive shield is applied, a substantially continuous iron is arranged so as to close the magnetic flux leaking outside the superconducting coil 7, but the shape of the shield is arbitrary. The shield is preferably installed so that it moves (rotates) at the same speed as the rotating superconducting coil 7. This is because, if the passive shield is stationary and is exposed to a fluctuating magnetic field by the rotating superconducting coil 7, the passive shield will be heated by this fluctuating magnetic field.

[0041] The passive shield may be installed either inside the vessel 30, i.e., in the low-temperature region, or outside in the room-temperature region. However, it is preferable that the shield move synchronously so as not to sense changes in the magnetic field generated by the rotating superconducting coil 7. The simplest implementation is to configure the passive shield so that it is supported integrally with the superconducting coil 7 and the power shaft section 25. In the configuration shown in FIG. 1, an iron magnetic pole 8 and a return yoke 9 are provided for the superconducting coil 7, which function as a passive shield, reducing the leakage magnetic field and strengthening the magnetic field in the working region SP.

[0042] <Other Applications of This Embodiment> The heating device 100 of this embodiment can be used not only to melt the object to be heated 12, but also for various other applications, for example, as follows. The same applies to the modified examples and other embodiments described below. Aluminum billet heater: The rotating superconducting magnet type heating device 100 of this embodiment can apply a rotating strong magnetic field to the object to be heated 12, so it can heat the object to be heated 12 quickly and uniformly, and can be used as a billet heater for aluminum extrusion molding.

[0043] Aluminum melting heater: Unlike heating methods in which the object to be heated 12 moves in a static magnetic field, the rotating superconducting magnet type heating device 100 of this embodiment can move the magnetic field generating source 24 even when the object to be heated 12 is not moving. This makes it possible to avoid a situation in which the object to be heated 12 becomes unable to be heated even if it softens due to a temperature rise and deforms due to centrifugal force, and it is possible to melt the object to be heated 12. This makes it possible to directly supply molten aluminum to a die-casting machine, etc.

[0044] Mold heater, sand mold heater: The rotary superconducting magnet type heating device 100 according to this embodiment can also be used as a mold heater or a sand mold heater. In this case, it is preferable that the object 12 to be heated extends along the transport axis L2. In other words, in the heating device 100, the object 12 to be heated may be transported along the transport axis L2, or may simply extend along the transport axis L2 without being transported.

[0045] In particular, the fifth embodiment (see FIG. 18 ), which will be described later, has a magnetic field generating source on one side, which allows for particularly excellent access to the work area. This allows for efficient heating of the object 12 to be heated. This makes the fifth embodiment particularly applicable to, for example, aluminum casting processes that use metal molds or sand molds. Furthermore, since it is possible to heat the molten metal poured into sand molds, which previously lacked heating means, it is possible to provide a manufacturing process that produces high-quality products with excellent yields, even for products with complex shapes.

[0046] <Modification 1-1> The configuration of superconducting coil 7 is not limited to that shown in FIG. 2, and various modifications are applicable. FIG. 3 is a schematic perspective view of superconducting coil 7b in Modification 1-1. In this modification, superconducting coil 7b is used instead of superconducting coil 7, but the other configuration is the same as that of the first embodiment (see FIG. 1). Superconducting coil 7b includes windings 165 and 166 called "CCT (canted cosine theta) coils." These are formed by winding superconducting wire obliquely around a cylindrical shape (no reference numeral) indicated by a dashed line.

[0047] Figure 4 is a schematic plan view of superconducting coil 7b in Modification 1-1. In Figure 4, the open arrows (without symbols) indicate the direction of the magnetic field formed by windings 165 and 166. As shown in the figure, in a plan view of superconducting coil 7b, a dipole magnetic field, which is also used for beam transportation, is formed in the area where windings 165 and 166 overlap. As a result, based on the same principle as beam transportation, object 12 to be heated can be urged in the direction of rotation axis L1, and object 12 to be heated can be transported along rotation axis L1.

[0048] <Modification 1-2> Fig. 5 is a schematic cross-sectional view of a superconducting coil 7c in Modification 1-2. In this modification, a superconducting coil 7c is used instead of the superconducting coil 7, but the other configurations are the same as those of the first embodiment (see Fig. 1). The superconducting coil 7c is formed by winding a superconducting wire in a circular shape, and its winding central axis L3 (third axis) is inclined and intersects with the rotation axis L1 and the transport axis L2. Assuming that the object to be heated 12 is subjected to magnetic field fluctuations due to the movement of the rotating magnet 20 (see Fig. 1), there is less need to impose restrictions on the magnetic field distribution shape and direction.

[0049] In this case, a strict magnetic field distribution like that of a dipole magnet for beam transport is not necessarily required, and there is no need to combine two obliquely wound coils (CCT coils) as shown in Fig. 4. Therefore, as shown in Fig. 5, a magnetic field oblique to the rotation axis L1 may be formed using a single obliquely wound superconducting coil 7c.

[0050] 4, the direction of the magnetic field at the center of superconducting coil 7b is perpendicular to rotation axis L1 and transport axis L2. Although the magnetic field is strengthened by overlapping windings 165 and 166, the magnetic fluxes in the direction of rotation axis L1 cancel each other out, resulting in a weaker magnetic field at the end of superconducting coil 7b. Thus, when rotating magnet 20 is configured by crossing two windings 165 and 166, the magnetic fluxes cancel out, resulting in a lower utilization efficiency of the coil magnetomotive force.

[0051] In contrast to this, by using a superconducting coil 7c, which is a single obliquely wound coil, as shown in Fig. 5, the cancellation of magnetic flux as shown in Fig. 4 does not occur. This increases the utilization efficiency of the coil magnetomotive force, and makes it possible to enlarge the working area SP (see Fig. 1) where the magnetic field acts.

[0052] <Modification 1-3> Fig. 6 is a schematic perspective view of a superconducting coil 7a in Modification 1-3. In Fig. 6, the superconducting coil 7a is provided along the rotation axis L1 and includes three superconducting coils 7c arranged in parallel. Each of these superconducting coils 7c is similar to that shown in Fig. 5. The winding central axes L3 (see Fig. 5) of these superconducting coils 7c are inclined obliquely with respect to the rotation axis L1, similar to that of Fig. 5. In this modification, a superconducting coil 7a is used instead of the superconducting coil 7, but the other configuration is similar to that of the first embodiment (see Fig. 1).

[0053] By applying the superconducting coil 7a, the generated magnetic field can be strengthened compared to the superconducting coil 7c shown in Fig. 5. As described above, in the configuration shown in Fig. 1, the iron pole 8 and the return yoke 9 are provided for the superconducting coil 7, which reduces the leakage magnetic field and strengthens the magnetic field in the working region SP. However, when the superconducting coil 7a shown in Fig. 6 is applied, a configuration suitable for this is desired.

[0054] <Modification 1-4> Fig. 7 is a schematic perspective view of a main part of Modification 1-4. This main part includes the superconducting coil 7a and the passive shield 50 of Modification 1-3. In this modification, the superconducting coil 7a and the passive shield 50 are used instead of the superconducting coil 7, but the other configuration is the same as that of the first embodiment (see Fig. 1). In Fig. 7, the passive shield 50 is formed in a substantially cylindrical shape, and the superconducting coil 7a is inserted on its inner periphery. With this configuration, it is possible to generate a magnetic field of 1.5 to 3.0 T within the working area, i.e., the area inside the superconducting coil 7a, while keeping the leakage magnetic field at a point approximately 2 m away from the center of the magnet to 5 gauss or less.

[0055] If the leakage magnetic field from the superconducting coil 7a were to be reduced solely by a passive shield 50 (magnetic shield), a large amount of iron would be required to construct the passive shield 50. This would result in an unacceptably large weight depending on the application of the heating device 100. In that case, it would be better to apply an active shield, in which a coil (not shown) is arranged to generate a magnetic field in the opposite direction to the magnetic field generated outside the working area by the superconducting coil 7a. Methods for constructing an active shield are generally well known and will not be described in detail here, but any active shield can be used in this modification.

[0056] <Modification 1-5> Fig. 8 is a schematic cross-sectional view of a superconducting coil 61 in Modification 1-5. In this modification, a superconducting coil 61 is used instead of the superconducting coil 7, but the other configuration is the same as that of the first embodiment (see Fig. 1). In Fig. 8, the superconducting coil 61 includes two opposing main coils 17 and shield coils 18 arranged on both sides thereof. Both the main coils 17 and the shield coils 18 are racetrack coils. As shown in Fig. 1, the rotary magnet 20 used in the heating device 100 is a magnetic field generation source that generates a magnetic field transverse to the transport axis L2 (see Fig. 1).

[0057] In this type of magnetic field generator, one magnet configuration method that can efficiently generate a magnetic field, easily configure the magnet, and provide a magnetic shielding effect is a magnet configuration method with coils arranged as shown in Figure 8. The working space SP is the area surrounded by the main coil 17 and shield coil 18. In Figure 8, the main coil 17 and shield coil 18 are shown in cross section, with the cross section of the coil arrangement as the cutting plane. The white arrow (without a symbol) indicates the direction of the magnetic field.

[0058] 8, two opposing main coils 17 apply a magnetic field to the working area SP. The shield coils 18 arranged on both sides apply a magnetic field in the opposite direction to the main coils 17 to the external space. This allows the shield coils 18 to act as an active shield, blocking out leakage magnetic fields. The shield coils 18 are arranged laterally to the working area SP, and the current in the shield coils 18 on the working area SP side creates a magnetic field in the working area SP that is in the same direction as the main coils 17.

[0059] The magnet configuration shown in Figure 8 can be realized with a simple racetrack coil rather than a three-dimensional coil such as a saddle coil. This makes it easy to manufacture the magnet, and the current close to the working area SP of each coil generates a magnetic field that is effective in the working area SP, making it the most efficient configuration. Furthermore, by balancing the magnetic flux of the main coil 17 and the magnetic flux of the shield coil 18, the sum of the magnetic moments of the superconducting coil 61 as viewed from a distance can be made zero, making it possible to reduce the leakage magnetic field.

[0060] <Modification 1-6> Fig. 9 is a schematic cross-sectional view of a superconducting coil 62 in Modification 1-6. In this modification, a superconducting coil 62 is used instead of the superconducting coil 7, but the other configuration is the same as that of the first embodiment (see Fig. 1). In Fig. 9, the superconducting coil 62 includes two opposing main coils 17 and shield coils 18 arranged on both sides thereof. These main coils 17 and shield coils 18 are both configured in the same manner as those shown in Fig. 8. Furthermore, the superconducting coil 62 includes a rectangular frame-shaped yoke 92 (magnetic shield) and a pair of magnetic poles 82 formed integrally with the yoke 92.

[0061] The functions of the main coil 17 and the shield coil 18 are the same as those of the first to fifth modified examples (see FIG. 8). As explained in FIG. 8, the shield coil 18 functions as an active shield. Furthermore, the yoke 92 and the magnetic pole 82 function as a passive shield. In this way, by using both an active shield and a passive shield, a magnetic field can be generated in the working area SP at low cost.

[0062] 8, the addition of yoke 92 and magnetic pole 82 not only provides a magnetic shielding effect but also makes effective use of magnetic flux. That is, by utilizing the magnetization of iron in yoke 92 and magnetic pole 82, the magnetic field strength in working region SP can be increased.

[0063] <Modification 1-7> Fig. 10 is a schematic cross-sectional view of a superconducting coil 63 in Modification 1-7. In this modification, a superconducting coil 63 is used instead of the superconducting coil 7, but the other configuration is the same as that of the first embodiment (see Fig. 1). In Fig. 10, the superconducting coil 63 includes a pair of main coils 17, an octagonal frame-shaped yoke 93 (magnetic shield), and a pair of magnetic poles 83 formed integrally with the yoke 93.

[0064] While the configuration shown in Fig. 9 required a total of four coils, the configuration shown in Fig. 10 requires only two coils, i.e., main coil 17, to generate a magnetic field in the working space SP. In the configuration shown in Fig. 9, the amount of iron used in yoke 92 can be reduced compared to yoke 93 in Fig. 10, making it possible to reduce the overall weight. On the other hand, the configuration shown in Fig. 10 allows for a smaller number of coils. Therefore, it is advisable to select an optimal configuration depending on the required size and magnetic field strength of the working space SP, the allowable weight of rotary magnet 20 (see Fig. 1), the allowable amount of leakage magnetic field, etc.

[0065] Second Embodiment Overall Structure of Second Embodiment Figure 11 is a schematic cross-sectional view of a heating device 150 according to a second embodiment. In the following description, parts corresponding to those in the first embodiment described above are denoted by the same reference numerals, and their description may be omitted. The heating device 150 is a rotary magnet type heating device, and similar to the heating device 100 of the first embodiment (see Figure 1), it includes a rotary magnet 20, a container 30, and a motor 40. The rotary magnet 20 includes a magnetic field generating source 24, a power shaft 25, and an insulating load support 26. The container 30 includes a housing 32 and an insulating layer 34.

[0066] The motor 40 drives the rotary magnet 20 to rotate. The magnetic field generating source 24 includes a superconducting coil 7-1 (first coil), a superconducting coil 7-2 (second coil), an iron pole 8, and a return yoke 9. The power shaft portion 25 is formed in a substantially cylindrical shape, and a substantially cylindrical space that is a part of the internal space thereof becomes a working area SP where the metallic object to be heated 12 is heated.

[0067] <Superconducting coils 7-1, 7-2> In the second embodiment, a pair of superconducting coils 7-1, 7-2 are used in addition to the iron magnetic pole 8 and the return yoke 9 (magnetic shield) in order to reduce the leakage magnetic field that leaks outside the heating device 150. That is, the superconducting coils 7-1, 7-2 are configured so that the magnetic fields of the superconducting coils 7-1, 7-2 are opposite in direction so that the sum of the magnetic moments of the rotary magnet 20 becomes zero.

[0068] 12 is a schematic perspective view of superconducting coils 7-1 and 7-2 in the second embodiment. The superconducting coils 7-1 and 7-2 include windings 161 and 162, respectively. The configuration of these windings 161 and 162 is the same as that of the first embodiment (see FIG. 2). The superconducting coils 7-1 and 7-2 are arranged so that their central axes coincide with the rotation axis L1 (see FIG. 11).

[0069] FIG. 13 is a schematic side view of superconducting coils 7-1 and 7-2 in the second embodiment. In FIG. 13, the open arrows (without symbols) indicate the directions of the magnetic fields generated by superconducting coils 7-1 and 7-2. As shown in the figure, the directions of the magnetic fields generated by superconducting coils 7-1 and 7-2 are both perpendicular to the rotation axis L1 and opposite to each other. That is, the excitation circuit (not shown) in this embodiment is configured to generate magnetic fields oriented as shown. Because the directions of the magnetic fields generated by superconducting coils 7-1 and 7-2 are opposite to each other, the sum of the magnetic moments is zero. Therefore, when viewed from a distance (at infinity), this is equivalent to the absence of a magnetic field source, and the leakage magnetic field can be reduced.

[0070] <Modification 2-1> Although not shown in the drawings, a modification of the second embodiment in which the heating devices 150 are connected in cascade will be described below. A plurality of cascade-connected heating devices 150 are referred to herein as a "heating device assembly." The heating device assembly heats the object 12, which is a metal material, quickly and uniformly by gradually increasing the temperature of the object 12. That is, the object 12 can be continuously fed into one end of the heating device assembly, and the molten object 12 can be continuously removed from the other end.

[0071] The temperature of the object to be heated 12 increases as it moves through the heating device assembly. For typical metallic materials, the higher the temperature, the higher the temperature of the material. In a heating device assembly, the amount of heat generated increases in proportion to the square of the rate of change of the magnetic field (dB / dt), while the amount of heat generated decreases in inverse proportion to the electrical resistance of the object to be heated 12. Therefore, in order to maintain the amount of heat generated, it is preferable to increase the rate of change of the magnetic field as the temperature of the object to be heated 12 increases. The aforementioned equation (1) for calculating the skin depth δ includes the product of the electrical conductivity σ, i.e., the reciprocal of the electrical resistance, and the frequency f.

[0072] Therefore, even if the frequency is increased by the amount of increase in electrical resistance, the skin depth δ does not change. The amount of heat generated by the object 12 increases in proportion to the square of the rotation speed of the magnetic field. Therefore, in a heating device assembly, it is preferable to increase the rotation speed of the heating device 150 located downstream. This allows the heating device assembly to heat and melt the object 12 in a short time.

[0073] [Third Embodiment] Next, a third embodiment will be described. Note that in the following description, parts corresponding to those of the other embodiments described above will be assigned the same reference numerals, and their description may be omitted. The overall configuration of the heating device in the third embodiment is not specifically illustrated, but is similar to that of the second embodiment (see FIG. 11). However, while two stages of superconducting coils 7-1 and 7-2 were applied as superconducting coils in the direction of the rotation axis L1 in the second embodiment, in this embodiment, four stages of superconducting coils are applied. The superconducting coils 7-1 and 7-2 similar to those in the second embodiment are applied to the two upstream stages of the four stages. Furthermore, in this embodiment, two stages of superconducting coils 7d-1 (first coil) and 7d-2 (second coil) shown in FIG. 14 are applied to the downstream side.

[0074] 14 is a schematic perspective view of superconducting coils 7d-1 and 7d-2 applied to heating device 160 of the third embodiment. Superconducting coils 7d-1 and 7d-2 have windings 181, 182, 183, and 184, respectively. These windings are saddle-shaped coils having a shape in which a rectangular frame is curved approximately one-quarter of the way around the cylindrical circumferential surface (not shown). These windings are arranged at equal intervals along the cylindrical circumferential surface. In other words, the number of poles of superconducting coils 7d-1 and 7d-2 is four.

[0075] 15 is a schematic side view of four stages of superconducting coils 7-1, 7-2, 7d-1, and 7d-2 in a heating device 160 of the third embodiment. The object to be heated 12 (see FIG. 11) is inserted from the left side of the superconducting coil 7-1 in FIG. 15. Then, the molten object to be heated 12 is discharged to the right side of the superconducting coil 7d-2.

[0076] Here, the reason why the number of poles of the upstream superconducting coils 7-1 and 7-2 is set to "2" and the number of poles of the downstream superconducting coils 7d-1 and 7d-2 is set to "4" will be explained. As described in the above-mentioned Modification 2-1, when the heating device assembly is configured by cascade-connecting the heating devices 150 of the second embodiment, it is preferable to increase the rotation speed of the heating device 150 located more downstream. However, in order to impart different rotation speeds to a plurality of heating devices in this way, a motor 40 (see FIG. 11) for imparting a driving force to each heating device and a control device for the motor 40 are required.

[0077] It is considered preferable to increase the number of poles of the superconducting coils in order to increase the rate of change (dB / dt) of the magnetic field B (not shown) toward the downstream side while using a common driving device such as the motor 40. Therefore, in this embodiment, the number of poles of the upstream superconducting coils 7-1 and 7-2 is set to "2," and the number of poles of the downstream superconducting coils 7d-1 and 7d-2 is set to "4," thereby changing the magnetic field at different speeds. In other words, the rate of change of the magnetic field increases toward the downstream side. Note that the number of poles of the superconducting coils is not limited to the above, and various combinations of the number of poles can be applied as long as the number of poles increases toward the downstream side.

[0078] [Fourth Embodiment] Next, a fourth embodiment will be described. Note that in the following description, parts corresponding to those of the other embodiments described above will be assigned the same reference numerals, and their description may be omitted. FIG. 16 is a schematic cross-sectional view of a heating device 170 according to the fourth embodiment. The heating device 170 is a rotary magnet type heating device and includes a pair of upper and lower rotary magnets, i.e., magnetic field generators 120A and 120B, a magnetic field generator support 130, a frame 140, and a motor 40. The magnetic field generator support 130 is formed in a substantially cylindrical shape and supports the magnetic field generators 120A and 120B. That is, the magnetic field generators 120A and 120B are rotatably supported at the upper and lower ends of the magnetic field generator support 130 via conical roller bearings (not shown). The motor 40 rotates the magnetic field generators 120A and 120B at the same speed. The frame 140 includes legs 141 and supports the magnetic field generator support 130.

[0079] In this embodiment, the rotation axis L1 is an axis passing through the centers of the magnetic field generating sources 120A and 120B. Meanwhile, the transport axis L2 is an axis substantially perpendicular to the rotation axis L1. In the illustrated example, the direction of the transport axis L2 is from the front to the back, but this is not limited thereto. The transport axis L2 can also be another axis substantially perpendicular to the rotation axis L1. Details of the magnetic field generating sources 120A and 120B will be described later. The magnetic field generating sources 120A and 120B generate magnetic fields in the directions indicated by the white arrows (without symbols). In this embodiment, the working area SP is a flat area sandwiched between the magnetic field generating sources 120A and 120B, as illustrated. The object 12 to be heated is inserted into the heating device 170 along the transport axis L2, and the object 12 to be heated is heated.

[0080] In the first to third embodiments described above, the rotation axis L1 and the transport axis L2 are substantially parallel. When the object 12 to be heated is elongated, such as a cylindrical object, or when the difference in the dimensions between the major axis and the minor axis in the cross-sectional shape of the object 12 is not large, it is preferable to apply the configurations of the first to third embodiments. On the other hand, when the object 12 to be heated is flat, as shown in FIG. 16 , or when the difference in the dimensions between the major axis and the minor axis in the cross-sectional shape of the object 12 to be heated is large, it is preferable to apply the heating device 170 according to this embodiment. This is because the shape of the working area SP can be ensured to be close to the shape of the object 12 to be heated.

[0081] 17 is a schematic perspective view of a magnetic field generation source 120. The magnetic field generation source 120 is used as the magnetic field generation sources 120A and 120B in FIG. 16. The magnetic field generation source 120 includes an iron yoke 99 (magnetic shield), magnetic poles 88a, 88b, 88c, and 88d, and superconducting coils 77a (first coil), 77b (second coil), 77c (first coil), and 77d (second coil). The iron yoke 99 is formed in a substantially disk shape, and the magnetic poles 88a, 88b, 88c, and 88d are formed in a disk or column shape protruding from four equal positions around the iron yoke 99. The superconducting coils 77a, 77b, 77c, and 77d are formed by winding superconducting wire in an annular shape around the circumferential surfaces of the magnetic poles 88a, 88b, 88c, and 88d, respectively.

[0082] Fifth Embodiment Next, a fifth embodiment will be described. In the following description, parts corresponding to those of the other embodiments described above will be designated by the same reference numerals, and their description may be omitted. FIG. 18 is a schematic cross-sectional view of a heating device 180 according to the fifth embodiment. The heating device 180 is a rotary magnet type heating device and includes a magnetic field generation source 120A, a magnetic field generation source support 132, a frame 142, and a motor 40. The magnetic field generation source support 132 is formed in a substantially cylindrical shape and supports the magnetic field generation source 120A. That is, the magnetic field generation source 120A is rotatably supported at the upper end of the magnetic field generation source support 132 via a conical roller bearing (not shown). The motor 40 drives the magnetic field generation source 120A to rotate. The frame 142 supports the magnetic field generation source support 132.

[0083] As such, the heating device 180 according to the fifth embodiment is similar to the heating device 170 according to the fourth embodiment in that the magnetic field generation source 120B has been removed. In the fifth embodiment, the magnetic field generation source 120A is provided on only one side of the magnetic field generation source support 132, which allows for a high degree of freedom in the installation method of the heating device 180 (the positional relationship between the work area SP and the magnetic field generation source 120A). For example, it is also possible to heat the object 12 to be heated by moving the heating device 180 itself. Furthermore, the heating device 180 can be used in various forms, such as by placing the heating device 180 on the floor and using the space above it as the work area SP.

[0084] [Sixth Embodiment] Next, a sixth embodiment will be described. In the following description, parts corresponding to those of the other embodiments described above will be designated by the same reference numerals, and their description may be omitted. Figure 19 is a schematic diagram of a vacuum die-casting apparatus 200 according to the sixth embodiment. The vacuum die-casting apparatus 200 includes an injection sleeve 211, a plunger 212, a holding furnace 213, a molten metal supply pipe 214, a lifting table 215, a coating device 220, a spraying device 230, a mold cavity 250, metal rods 272 and 274, mold heating devices 282 and 284, and an aluminum melting device 286.

[0085] The mold cavity 250 includes a fixed mold 256 and a movable mold 258 which are molds for a metal product (not shown), a fixed platen 252 which mounts and supports the fixed mold 256, and a movable platen 254 which mounts and supports the movable mold 258. The injection sleeve 211 is formed in a substantially cylindrical shape and is mounted on the fixed mold 256 so as to communicate with the opposing surfaces of the fixed mold 256 and the movable mold 258. The plunger 212 is formed in a substantially cylindrical shape and moves back and forth within the injection sleeve 211.

[0086] The metal rods 272, 274 are formed in a cylindrical shape, with one end of each embedded in the fixed mold 256 and the movable mold 258 and the other end protruding from the fixed platen 252 and the movable platen 254. The mold heating devices 282, 284 are heating devices according to any of the first to fifth embodiments described above, and heat the metal rods 272, 274, respectively, to heat the fixed mold 256 and the movable mold 258.

[0087] The holding furnace 213 is disposed below the injection sleeve 211 and contains molten metal M obtained by melting a metallic material. The upper end of the molten metal supply pipe 214 communicates with a molten metal supply port 211a formed in the injection sleeve 211. The lower end 214a of the molten metal supply pipe 214 is immersed in the molten metal M in the holding furnace 213. The aluminum melting apparatus 286 is a heating apparatus according to any one of the first to fifth embodiments described above, and melts the object to be heated 12, which is aluminum or an aluminum alloy, to form molten metal M, which is then poured into the holding furnace 213.

[0088] The vacuum pump 240 is connected to a cutoff valve 242 via a pipe 244. The cutoff valve 242 is in communication with a mold cavity 250. As a result, the vacuum pump 240 reduces the pressure inside the mold cavity 250 to a vacuum state and sucks the molten metal M inside the holding furnace 213 into the injection sleeve 211.

[0089] The holding furnace 213 is placed on a lifting platform 215, and the level of the molten metal M is kept constant by raising and lowering the lifting platform 215. The molten metal supply pipe 214 is made of ceramic with a BN coating on the inner surface to prevent reaction with the molten metal M, and its lower end 214a is orifice-shaped. The outer periphery of the molten metal supply pipe 214 is surrounded by a heater (not shown), which maintains the molten metal supply pipe 214 at a temperature close to that of the molten metal M.

[0090] The application device 220 includes an arm 222 and a nozzle 221, and applies a release agent made of a water-free synthetic oil to the mold cavity 250. The spraying device 230 includes a powder lubricant tank 231 and a nozzle 232, and sprays the powder lubricant onto the injection sleeve 211.

[0091] [Effects of the embodiment] According to the above-described embodiment, the heating devices 100, 150, 160, 170, 180 heat the object to be heated 12 by applying a magnetic field to the working area SP, which is an area where the object to be heated 12 containing metal is heated, using superconducting coils 7, 7a, 7b, 7c, 7-1, 7-2, 7d-1, 7d-2, 61, 62, 63, 77a, 77b, 77c, 77d, each having a superconducting wire wound therearound, and are provided with a magnetic field generation source 24, 120 that moves relative to the working area SP, and the magnetic field generation source 24, 120 suppresses leakage magnetic field of the magnetic field generated by the magnetic field generation source 24, 120 that leaks to the outside, and are provided with a magnetic shield (9, 50, 92, 93, 99) that moves at the same speed as the magnetic field generation source 24, 120.

[0092] This allows the magnitude of the magnetic flux flowing through the magnetic shield (9, 50, 92, 93, 99) to be approximately constant, thereby suppressing the current induced in the magnetic shield and suppressing heat generation due to the induced current.

[0093] Furthermore, it is more preferable that the superconducting coil operates in a persistent current mode, and that the motion of the magnetic field generator 24, 120 is rotational about the first axis (L1), thereby allowing a continuously changing magnetic field to be applied to the working region SP.

[0094] Furthermore, the object to be heated 12 extends or is transported along the second axis (L2), and it is more preferable that the first axis (L1) and the second axis (L2) are substantially parallel to each other, which makes it easier to handle the object to be heated 12, for example, when the object to be heated 12 is long.

[0095] Furthermore, it is more preferable that the superconducting coils 7a, 7b, and 7c are formed by winding superconducting wire around the third axis (L3) as the central axis of the winding, and that the magnetic field generating source 24 includes superconducting coils 7a, 7b, and 7c whose third axis (L3) and first axis (L1) are not orthogonal to each other. This causes the object 12 to be heated to be biased in the direction of the first axis (L1), and the object 12 to be heated can be transported by the superconducting coils 7a, 7b, and 7c.

[0096] Furthermore, it is more preferable that a plurality of superconducting coils 7c whose third axis (L3) and first axis (L1) are not orthogonal to each other are provided along the first axis (L1), thereby strengthening the magnetic field generated by the superconducting coils (7c).

[0097] Furthermore, as in the second to fifth embodiments, it is more preferable that the superconducting coils 7-1, 7-2, 7d-1, 7d-2, 77a, 77b, 77c, and 77d include a first coil (7-1, 7d-1, 77a, and 77c) that generates a first magnetic field and a second coil (7-2, 7d-2, 77b, and 77d) that generates a magnetic field in the opposite direction to the first magnetic field. This makes it possible to make the magnetic field source appear as if it were not present when viewed from a distance (a point at infinity), thereby reducing the leakage magnetic field.

[0098] Furthermore, as in the third embodiment, it is more preferable that the superconducting coils 7-1, 7-2, 7d-1, 7d-2, 77a, 77b, 77c, and 77d include a plurality of coils that change the magnetic field at different speeds in response to the movement of the magnetic field generating source 24. This allows the object 12 to be heated more appropriately depending on the state of the object 12.

[0099] Furthermore, as in the fourth to sixth embodiments, the object to be heated 12 extends or is transported along the second axis (L2), and it is more preferable that the first axis (L1) and the second axis (L2) are substantially perpendicular to each other, which makes it easier to handle the object to be heated 12, for example, when the object to be heated 12 is flat.

[0100] Furthermore, as in the fourth embodiment, it is more preferable that the magnetic field generating sources 120A and 120B are arranged opposite each other across the working area SP and are provided in plurality so as to move at the same speed, thereby enabling the magnetic field between the magnetic field generating sources 120A and 120B to rotate stably.

[0101] [Modifications] The present invention is not limited to the above-described embodiment, and various modifications are possible. The above-described embodiment is provided as an example to facilitate understanding of the present invention, and is not necessarily limited to an embodiment including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Furthermore, the control lines and information lines shown in the figures are those considered necessary for explanation, and do not necessarily represent all control lines and information lines necessary for the product. In reality, it is possible to consider that almost all components are interconnected. Possible modifications of the above-described embodiment include, for example, the following.

[0102] (1) In each of the above embodiments, the motor 40 is provided outside the magnetic field generation source 24, 120 to rotate the magnetic field generation source 24, 120. However, a coil (not shown) that generates a rotating magnetic field may be provided in the container 30 or the magnetic field generation source support 130, 132, thereby generating a rotational force in the return yoke 9 or the iron yoke 99 of the magnetic field generation source 24, 120.

[0103] (2) In the above embodiment, the magnetic field generating sources 24 and 120 rotate, but they may also reciprocate.

[0104] 7, 7a, 7b, 7c, 61, 62, 63 Superconducting coils 7-1, 7d-1, 77a, 77c Superconducting coils (first coils) 7-2, 7d-2, 77b, 77d Superconducting coils (second coils) 9 Return yoke (magnetic shield) 12 Object to be heated 24, 120 Magnetic field generation source 50 Passive shield (magnetic shield) 92, 93, 99 Yoke (magnetic shield) 100, 150, 160, 170, 180 Heating device 120, 120A, 120B Magnetic field generation source 282, 284 Mold heating device 286 Aluminum melting device L1 Rotation axis (first axis) L2 Transfer axis (second axis) L3 Winding center axis (third axis) SP Working area

Claims

1. A heating device that heats an object to be heated, including metal, by applying a magnetic field to a working area, which is an area where the object to be heated is heated, using a superconducting coil formed by winding superconducting wire, and that is equipped with a magnetic field generating source that moves relative to the working area, wherein the magnetic field generating source suppresses leakage magnetic field that leaks to the outside from the magnetic field generated by the magnetic field generating source, and is equipped with a magnetic shield that moves at the same speed as the superconducting coil.

2. The heating device according to claim 1, characterized in that the superconducting coil is operated in a persistent current mode, and the motion of the magnetic field generating source is a rotational motion about a first axis.

3. The heating device according to claim 2, characterized in that the object to be heated extends or is transported along a second axis, and the first axis and the second axis are substantially parallel.

4. The heating device according to claim 3, characterized in that the superconducting coil is made by winding a superconducting wire around a third axis as a central axis of winding, and the magnetic field generating source includes the superconducting coil in which the third axis and the first axis are not perpendicular to each other.

5. The heating device according to claim 4, characterized in that the superconducting coil, in which the third axis and the first axis are not perpendicular to each other, is provided in plurality along the first axis.

6. The heating device according to claim 1, characterized in that the superconducting coil comprises: a first coil that generates a first magnetic field; and a second coil that generates a magnetic field in an opposite direction to the first magnetic field.

7. The heating device according to claim 1, characterized in that the superconducting coil includes a plurality of superconducting coils that change the magnetic field at different speeds in response to the movement of the magnetic field generating source.

8. The heating device according to claim 2, characterized in that the object to be heated extends or is transported along a second axis, and the first axis and the second axis are substantially perpendicular to each other.

9. The heating device according to claim 8, characterized in that the magnetic field generating sources are provided in plurality, arranged opposite each other across the working area and moving at the same speed.

10. An aluminum melting apparatus comprising the heating device according to any one of claims 1 to 9.

11. A mold heating device comprising the heating device according to any one of claims 1 to 9.

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