WO2025022937A1 - Heating device, aluminum melting device, and die heating device - Google Patents

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

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

Today, aluminum and aluminum alloys, which are lightweight and highly corrosion-resistant, are used as structural materials in a variety of products. Casting has the advantage of being a method for 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 aluminum alloy is first melted to form molten metal, which is then injected into a mold (metal mold, sand mold) to obtain the molded product.

In these casting processes, heating is required to melt the raw materials and preheat the dies, etc., and is done using gas or electricity, but the aluminum rolling industry is also working towards 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.

However, it is difficult to achieve uniform heating with heating methods that use combustion gas to heat the surface of the object to be heated. Also, with high-frequency induction heating, the surface tends to heat up just like with gas, resulting in large Joule losses in the coil (electromagnet) and conductor used to generate the high-frequency magnetic field. For this reason, Patent Document 1 and Non-Patent Document 1 listed below describe technology related to induction heating devices that use superconducting magnets. The descriptions in these documents are incorporated as part of the present specification.

Special Publication No. 2010-537376

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 〉

However, in the above-mentioned technology, there is a demand for realizing more appropriate induction heating.
The present invention has been made in consideration 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.

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 made of wound superconducting wire, and is characterized in that it is equipped with a magnetic field generating source that moves relative to the working area, and that 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.

The present invention makes it possible to achieve appropriate induction heating.

FIG. 2 is a schematic cross-sectional view of the heating device according to the first embodiment. FIG. 2 is a schematic perspective view of a superconducting coil. FIG. 13 is a schematic perspective view of a superconducting coil in Modification 1-1. FIG. 2 is a schematic plan view of the superconducting coil. FIG. 13 is a schematic cross-sectional view of a superconducting coil in a 1-2 modified example. FIG. 13 is a schematic perspective view of a superconducting coil in a 1-3 modified example. FIG. 13 is a schematic perspective view of a main part of a 1-4th modified example. FIG. 13 is a schematic cross-sectional view of a superconducting coil in a 1-5th modified example. FIG. 13 is a schematic cross-sectional view of a superconducting coil in a 1-6th modified example. FIG. 13 is a schematic cross-sectional view of a superconducting coil in Modification Example 1-7. FIG. 6 is a schematic cross-sectional view of a heating device according to a second embodiment. FIG. 11 is a schematic perspective view of a superconducting coil in a second embodiment. FIG. 11 is a schematic side view of a superconducting coil in a second embodiment. FIG. 11 is a schematic perspective view of a superconducting coil applied to a heating device of a third embodiment. FIG. 13 is a schematic side view of four stages of superconducting coils in a heating device according to a third embodiment. FIG. 13 is a schematic cross-sectional view of a heating device according to a fourth embodiment. FIG. 2 is a schematic perspective view of a magnetic field generating source. FIG. 13 is a schematic cross-sectional view of a heating device according to a fifth embodiment. FIG. 13 is a schematic diagram of a vacuum die casting apparatus according to a sixth embodiment.

[Overview of the embodiment]
Heating can be achieved by utilizing the strong magnetic field of a superconducting magnet by applying the technology described in Non-Patent Document 1. This method involves inserting and rotating 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 by using this current.

In the method of rotating an aluminum billet in a superconducting DC magnetic field, the rotation frequency can be reduced due to the high magnetic field strength, and uniform heating is possible by allowing the magnetic field to penetrate into the inside of the billet without being affected by the skin effect. Furthermore, most of the energy input to mechanically rotate the aluminum billet can be converted into heat generation in the aluminum billet. This reduces Joule loss and greatly improves efficiency. In this way, heating methods using a strong superconducting magnetic field are attracting attention because they contribute to low carbonization.

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 places restrictions on the shape of the object to be heated. In addition, 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 cannot 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.

In order to introduce a strong magnetic field source such as a superconducting magnet into a production process, it is preferable to prevent the leakage magnetic field from leaking. 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 thought that it is possible to use the leakage magnetic field generated by the superconducting magnet to the outside and provide a driving force to the superconducting magnet using a coil installed outside the superconducting magnet. If a shielding effect is to be obtained 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 on the object to be heated. In addition, a yoke is installed on the outer coil, and it seems that the magnetic field can be shielded by this yoke. However, this yoke is subjected to the strong rotating magnetic field generated by the superconducting coil, and a large amount of heat is generated.

The embodiment described below provides a heating device using a superconducting magnet with a small leakage magnetic field. In the embodiment 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 to 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.

[First embodiment]
Overall Structure of the First Embodiment
FIG. 1 is a schematic cross-sectional view of a heating device 100 according to a 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.

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 section 25 is formed in an approximately cylindrical shape, and a part of its internal space, which is an approximately cylindrical space, becomes a working area SP for heating the metallic object to be heated 12. An insulating layer 28 is provided between the power shaft section 25 and the magnetic field generating source 24 and the insulating load support 26.

<Rotary magnet 20>
(Superconducting coil 7)
FIG. 2 is a schematic perspective view of the superconducting coil 7. As shown in FIG.
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 a 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.

However, the shape of the superconducting coil 7 is arbitrary, and for example, it can be configured with racetrack coils facing each other on either side of the working area SP. In such a method of facing racetrack coils, the magnetic field generated outside the coil is used, so the utilization efficiency of the coil (magnetomotive force) is poor. Therefore, it is preferable to use a saddle-type coil as shown in Figure 2, although the winding work becomes more complicated.

(Iron pole 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 pole 8, and is disposed coaxially with the power shaft section 25. The return yoke 9 has a 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 pole 8 protrudes from the return yoke 9 to the inner periphery and passes 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 section 25.

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

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

(Rotation axis L1 and conveying axis L2)
Here, the rotation axis of the power shaft unit 25 is called L1 (first axis), and the flow line for inserting the object to be heated 12 into the power shaft unit 25 is called the conveying axis L2 (second axis). In the illustrated example, the rotation axis L1 and the conveying axis L2 are aligned, but they do not necessarily have to be aligned. However, in this embodiment, the rotation axis L1 and the conveying axis L2 are approximately parallel to each other.

The magnetic field source 24 generates a magnetic field in a direction roughly perpendicular to the transport axis L2. When the rotating magnet 20 rotates, the positional relationship of the magnetic field source 24 with respect to the object to be heated 12 changes, which induces eddy currents inside the metallic object to be heated 12, heating the object to be heated 12. In other words, when the magnetic field source 24 rotates around the rotation axis L1, a rotating magnetic field is applied to the working area 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.

(Rotational speed of the rotating magnet 20)
Next, the rotation speed of the rotary magnet 20 will be described.
Generally, when a fluctuating magnetic field is applied to a metal body, the depth to which the fluctuating magnetic field penetrates into the metal body changes depending on the frequency f at which the applied magnetic field changes and the properties of the metal body (electrical conductivity σ, relative permeability _μr ). The depth at which the strength of the fluctuating magnetic field that has penetrated into the metal body is "1/e" (e is Napier's number = 0.2718...) of the strength of the applied external fluctuating magnetic field 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.

If the frequency f becomes too high, the skin depth δ becomes small, so that eddy currents flow almost exclusively on the surface of the heated object 12. Therefore, although it depends on the material and shape of the heated object 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 realizes the frequency f is 60·f/p [rpm]. On the other hand, since the current induced inside the heated object 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 heated object 12.

In order to induce a current in the heated object 12 large enough to heat it, 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 a temperature well below the critical temperature of the superconducting material (the temperature at which superconducting properties are expressed), and are usually housed inside a vacuum insulated container (cryostat) and cooled and operated using a refrigerator or refrigerant.

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

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 area 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.

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 this way, 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, match.

<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 an annular shape. 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 portion of the 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.

Since the rotating magnet 20 includes the superconducting coil 7, a cryostat is required that can rotate the superconducting coil 7 while cooling it and keeping it cool. As described above, in this embodiment, the container 30 functions as a cryostat. As the insulating layer 34 formed on the container 30, an insulating vacuum layer, insulating foam, or the like can be used. In this way, the insulating layer 34 provided on the container 30 and the insulating layer 28 provided on the power shaft section 25 reduce the intrusion of heat from the outside into the inside of the container 30.

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. There are various possible specific cooling methods, and the cooling method is not particularly limited. For example, it is possible to directly introduce the cooling gas from a port (not shown) provided in the stationary container 30. Another example is a method in which a refrigerator (not shown) is attached to the container 30 and the refrigerant gas is cooled via a heat exchanger.

Since the rotating magnet 20 rotates relative to the stationary container 30 filled with refrigerant gas, a rotatable seal is enclosed between the power shaft section 25 and the container 30 (not shown). It is preferable to use a magnetic fluid as a seal between the container 30 filled with refrigerant gas and the power shaft section 25. However, depending on the dimensions of the seal and the rotation speed, it is also possible to use an elastomer seal.

<Method of operating the superconducting coil 7 (method of exciting the coil)>
The operation method of the superconducting coil 7 is preferably a persistent current mode operation. The persistent current mode operation is one of the operation (excitation) methods of the superconducting coil 7, in which the superconducting coil 7 and the excitation circuit (not shown) are made of superconducting wires, and a superconducting closed circuit is formed including the connection part and operated. That is, this operation method utilizes the fact that the current inputted into the superconducting closed circuit does not decay so much that it can be considered to flow forever. In order to input a current into the superconducting closed circuit, it is preferable to apply a persistent current switch (PCS) not shown. When inputting or outputting a current into or from the superconducting closed circuit, the persistent current switch is in a normal conducting state to input or output the current. After that, once a current is inputted into the superconducting closed circuit, the current continues to flow forever, so there is no need to supply a current from an outside source.

In FIG. 1, the excitation circuit for the superconducting coil 7 is omitted. This excitation circuit is, for example, an excitation cable laid along the power shaft section 25, and supplies current to the superconducting coil 7. In persistent current mode operation, once current has been 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 remove the power supply after exciting the superconducting coil 7.

As a result, there is no need to provide a special current-introducing rotating terminal for the rotating magnetic field generating source 24. However, the method of operation 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 rotating. In this case, it is recommended to install a slip ring (not shown) on the power shaft portion 25 to supply current.

<Methods for reducing leakage magnetic fields>
In order to deploy the rotating magnet type heating device 100 at a manufacturing site, it is preferable to reduce the leakage magnetic field. If the heating device 100 is brought into a manufacturing site without limiting the leakage magnetic field, an accident may occur in which the surrounding magnetic material is attracted. In addition, 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. As a form of the magnetic shield, it is possible to place a ferromagnetic material around the periphery of the superconducting coil 7 so that the magnetic flux created by the superconducting coil 7 is closed. This is called a passive shield. It is also possible to place an electromagnet, i.e., a shield coil, on the outside of the coil so that the magnetic field created by the superconducting coil 7 is opposite to the magnetic field created outside the coil. This is called an active shield.

When applying a passive shield, a generally continuous piece of iron is placed so that the magnetic flux leaking outside the superconducting coil 7 is closed, 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 exposed to the fluctuating magnetic field caused by the rotating superconducting coil 7, the passive shield will be heated by this fluctuating magnetic field.

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 moves 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 as to be supported integrally with the superconducting coil 7 and the power shaft section 25.
In the configuration shown in FIG. 1, an iron pole 8 and a return yoke 9 are provided for the superconducting coil 7, which function as a passive shield to reduce leakage magnetic fields and to enhance the magnetic field in the working region SP.

<Other uses of this embodiment>
The heating device 100 of the present embodiment is not only useful for melting the object to be heated 12 but can also be used for various other purposes, for example, as described below. The same applies to the modified examples and other embodiments described later.
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, thereby making it possible to heat the object to be heated 12 rapidly and uniformly, and can be applied as a billet heater for aluminum extrusion molding.

- 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 itself is not moving. This makes it possible to avoid a state in which the object to be heated 12 becomes unable to be heated even if it softens due to a rise in temperature and is deformed by 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.

- Mold heater, sand mold heater: The rotating 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 to have the object to be heated 12 extend along the transport axis L2. In other words, in the heating device 100, the object to be heated 12 may be transported along the transport axis L2, or the object to be heated 12 may simply extend along the transport axis L2 without being transported.

In particular, the fifth embodiment (see FIG. 18) described below has a magnetic field generating source on one side, which provides excellent access to the work area. This allows the heated object 12 to be heated efficiently. As a result, the fifth embodiment in particular can be used in aluminum casting processes that use metal molds and sand molds. In addition, since it is possible to heat the molten metal poured into sand molds, which previously had no heating means, a manufacturing process can be provided that is high quality and has an excellent yield, even for products with complex shapes.

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

FIG. 4 is a schematic plan view of superconducting coil 7b in the 1-1 modified example.
In Fig. 4, the open arrows (without a symbol) indicate the direction of the magnetic field formed by the windings 165, 166. As shown in the figure, in a plan view of the superconducting coil 7b, a dipole magnetic field that is also used for beam transportation and the like is formed in the portion where the windings 165, 166 overlap. As a result, based on the same principle as beam transportation and the like, the object to be heated 12 can be urged in the direction of the rotation axis L1, and the object to be heated 12 can be transported along the rotation axis L1.

<Modification 1-2>
5 is a schematic cross-sectional view of a superconducting coil 7c in the modified example 1-2. In this modified example, a superconducting coil 7c is used instead of the superconducting coil 7, but the other configurations are the same as those in the first embodiment (see FIG. 1).
The superconducting coil 7c is formed by winding a superconducting wire in an annular 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 12 to be heated 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 the direction of the magnetic field.

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

Referring again to FIG. 4, the magnetic field at the center of superconducting coil 7b is oriented perpendicular to rotation axis L1 and transport axis L2. Although the magnetic field is strengthened by overlapping windings 165, 166, the magnetic flux in the direction of rotation axis L1 cancels each other out, so the magnetic field is weaker at the end of superconducting coil 7b. In this way, when rotating magnet 20 is formed by crossing two windings 165, 166, the magnetic flux cancels out, so the utilization efficiency of the coil magnetomotive force is reduced.

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

<Modification 1-3>
FIG. 6 is a schematic perspective view of a superconducting coil 7a in the first modified example.
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, the superconducting coil 7a is used instead of the superconducting coil 7, but the other configurations are similar to those of the first embodiment (see Fig. 1).

By using the superconducting coil 7a, the generated magnetic field can be strengthened in comparison with the superconducting coil 7c shown in FIG.
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.

<Modification 1-4>
7 is a schematic perspective view of a main part of the 1-4th modified example. The main part includes the superconducting coil 7a and the passive shield 50 in the 1-3th modified example. In this modified example, the superconducting coil 7a and the passive shield 50 are applied instead of the superconducting coil 7, but the other configurations are the same as those in the first embodiment (see FIG. 1).
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 in the working area, i.e., in the area inside the superconducting coil 7a, while keeping the leakage magnetic field at a point about 2 m away from the center of the magnet to 5 Gauss or less.

If the leakage magnetic field from the superconducting coil 7a is to be reduced by only a passive shield 50 (magnetic shield), a large amount of iron is required to construct the passive shield 50. Depending on the application of the heating device 100, this may be too heavy to be tolerated. In that case, it is better to apply an active shield in which a coil (not shown) is placed to create a magnetic field in the opposite direction to the magnetic field created 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 modified example.

<Modification 1-5>
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).
8, the superconducting coil 61 includes two opposing main coils 17 and shield coils 18 disposed on both sides thereof. Both the main coils 17 and the shield coils 18 are racetrack coils.
As shown in FIG. 1, a rotary magnet 20 applied to the heating device 100 is a magnetic field generation source that generates a magnetic field transverse to the conveying axis L2 (see FIG. 1).

In this type of magnetic field source, one magnet configuration method that can efficiently generate a magnetic field, easily configure a magnet, and provide a magnetic shielding effect is a magnet configuration method with coils arranged as shown in Figure 8. The working area 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-sectional shape with the transverse section of the coil arrangement as the cutting surface. The white arrow (without a symbol) indicates the direction of the magnetic field.

In FIG. 8, two opposing main coils 17 apply a magnetic field to the working area SP. The shield coils 18 arranged on either side 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 to the side of the working area SP, and the current on the working area SP side of the shield coils 18 creates a magnetic field in the working area SP that is in the same direction as the main coils 17.

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, while the current close to the working area SP of each coil generates an effective magnetic field for the working area SP, making it the most efficient configuration. Furthermore, by balancing the amount of magnetic flux in the main coil 17 and the amount of magnetic flux in 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.

<Modification 1-6>
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).
9, the superconducting coil 62 includes two opposing main coils 17 and shield coils 18 arranged on both sides thereof. The main coils 17 and the shield coils 18 are both configured in the same manner as 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.

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 described 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 an active shield and a passive shield together, a magnetic field can be generated in the working area SP at low cost.

Furthermore, by adding the yoke 92 and magnetic pole 82 to the configuration shown in FIG. 8, not only is it possible to obtain a magnetic shielding effect, but it is also possible to effectively utilize the magnetic flux. In other words, by utilizing the magnetization of iron in the yoke 92 and magnetic pole 82, it is possible to increase the magnetic field strength in the working area SP.

<Modification No. 1-7>
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 similar to 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 .

The configuration shown in FIG. 9 required a total of four coils, but the configuration shown in FIG. 10 can generate a magnetic field in the working area SP using two coils, i.e., the main coil 17. In the configuration shown in FIG. 9, the amount of iron used in the yoke 92 can be reduced compared to the yoke 93 in FIG. 10, making it possible to reduce the overall weight. On the other hand, the configuration shown in FIG. 10 can reduce the number of coils. Therefore, it is advisable to select the optimal configuration depending on the required size and magnetic field strength of the working area SP, the allowable weight of the rotating magnet 20 (see FIG. 1), the allowable amount of leakage magnetic field, etc.

[Second embodiment]
Overall structure of the second embodiment
11 is a schematic cross-sectional view of a heating device 150 according to the second embodiment. In the following description, parts corresponding to those in the first embodiment described above are denoted by the same reference numerals, and the description thereof 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 FIG. 1), 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 portion 25, and a heat-insulating load support 26. The container 30 includes a housing 32 and a heat-insulating layer 34.

The motor 40 drives the rotary magnet 20 to rotate. The magnetic field generating source 24 also 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 section 25 is formed in a roughly cylindrical shape, and a roughly cylindrical space that is part of the internal space thereof becomes a working area SP that heats the metallic object to be heated 12.

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

FIG. 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 respectively include windings 161 and 162. The configurations of the windings 161 and 162 are similar to those in the first embodiment (see FIG. 2). The superconducting coils 7-1 and 7-2 are arranged such that their central axes coincide with the rotation axis L1 (see FIG. 11).

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 direction of the magnetic field generated by the superconducting coils 7-1 and 7-2. As shown in the figure, the directions of the magnetic fields generated by the 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 a magnetic field with the direction shown in the figure. Since the directions of the magnetic fields generated by the 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 (a point at infinity), this is equivalent to there being no magnetic field source, and the leakage magnetic field can be reduced.

<Modification No. 2-1>
Here, although not shown, a modified example in which the heating devices 150 of the second embodiment are connected in cascade will be described.
A plurality of cascaded 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.

The temperature of the heated object 12 increases as it moves inside the heating device assembly. In general metal materials, the higher the temperature, the higher the resistance temperature coefficient. In the 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), and decreases in inverse proportion to the electrical resistance of the heated object 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 heated object 12 increases. The above-mentioned formula (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.

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 heated 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 further downstream. This allows the heating device assembly to heat and melt the heated object 12 in a short period of time.

[Third embodiment]
Next, a third embodiment will be described. In the following description, the same reference numerals are used to designate parts corresponding to those in the other embodiments described above, and the description thereof may be omitted.
Although not shown in the figure, the overall configuration of the heating device in the third embodiment is similar to that in the second embodiment (see FIG. 11). However, while in the second embodiment, two stages of superconducting coils 7-1 and 7-2 are applied as superconducting coils in the direction of the rotation axis L1, 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.

FIG. 14 is a schematic perspective view of superconducting coils 7d-1 and 7d-2 applied to a heating device 160 of the third embodiment.
The superconducting coils 7d-1 and 7d-2 each have windings 181, 182, 183, and 184. These windings are saddle-shaped coils, and have a shape in which a rectangular frame is curved about 1/4 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 the superconducting coils 7d-1 and 7d-2 is "4".

FIG. 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.

The reason why the number of poles of the upstream superconducting coils 7-1, 7-2 is set to "2" and the number of poles of the downstream superconducting coils 7d-1, 7d-2 is set to "4" will now be explained. As described in the above-mentioned Modification 2-1, when the heating device assembly is formed by cascading the heating devices 150 of the second embodiment, it is preferable to increase the rotation speed of the heating device 150 located downstream. However, in order to give different rotation speeds to multiple heating devices in this way, a motor 40 (see FIG. 11) for giving a driving force to each heating device and its control device are required.

In order to increase the rate of change (dB/dt) of the magnetic field B (not shown) toward the downstream while using a common driving device such as the motor 40, it is considered preferable to increase the number of poles of the superconducting coils. 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 is increased toward the downstream. 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.

[Fourth embodiment]
Next, a fourth embodiment will be described. In the following description, the same reference numerals are used to designate parts corresponding to those in the other embodiments described above, and the description thereof 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 magnetic field generating sources 120A and 120B, which are a pair of upper and lower rotary magnets, a magnetic field generating source support 130, a frame 140, and a motor 40. The magnetic field generating source support 130 is formed in a substantially cylindrical shape and supports the magnetic field generating sources 120A and 120B. That is, the magnetic field generating sources 120A and 120B are rotatably supported at the upper and lower ends of the magnetic field generating source support 130 via conical roller bearings (not shown). The motor 40 rotates the magnetic field generating sources 120A and 120B at the same speed. The frame 140 includes legs 141 and supports the magnetic field generating source support 130.

In this embodiment, the rotation axis L1 is an axis that passes through the center of the magnetic field generating sources 120A and 120B. On the other hand, the transport axis L2 is an axis that is approximately perpendicular to the rotation axis L1. In the illustrated example, the direction of the transport axis L2 is from the front side to the back side, but this is not limited to this, and another axis that is approximately perpendicular to the rotation axis L1 can be the transport axis L2. The magnetic field generating sources 120A and 120B will be described in detail later, but the magnetic field generating sources 120A and 120B generate a magnetic field in the direction indicated by the white arrows (no symbol). In this embodiment, the working area SP is a flat area sandwiched between the magnetic field generating sources 120A and 120B as illustrated. The heated object 12 is inserted into the heating device 170 along the transport axis L2, and the heated object 12 is heated.

In the first to third embodiments described above, the rotation axis L1 and the transport axis L2 are approximately parallel. When the heated object 12 is an elongated object such as a cylinder, or when the difference in size between the long and short axes of the cross-sectional shape of the heated object 12 is not large, it is preferable to apply the configurations of the first to third embodiments. On the other hand, when the heated object 12 is flat, for example as shown in FIG. 16, or when the difference in size between the long and short axes of the cross-sectional shape of the heated object 12 is large, it is preferable to apply the heating device 170 of this embodiment. This is because the shape of the working area SP can be ensured to be close to the shape of the heated object 12.

Figure 17 is a schematic perspective view of magnetic field generating source 120. Note that magnetic field generating source 120 is applied as magnetic field generating sources 120A and 120B in Figure 16. Magnetic field generating source 120 comprises 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). Iron yoke 99 is formed in an approximately disk shape, and magnetic poles 88a, 88b, 88c and 88d are formed in a disk or cylinder shape protruding from four equal positions around the circumference of iron yoke 99. Superconducting coils 77a, 77b, 77c, and 77d are made by winding superconducting wire in an annular shape around the circumferential surfaces of magnetic poles 88a, 88b, 88c, and 88d, respectively.

[Fifth embodiment]
Next, a fifth embodiment will be described. In the following description, the same reference numerals are used to designate parts corresponding to those in the other embodiments described above, and the description thereof 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.

In this way, the heating device 180 according to the fifth embodiment is similar to the heating device 170 according to the fourth embodiment with the magnetic field generating source 120B removed. In the fifth embodiment, the magnetic field generating source 120A is provided on only one side of the magnetic field generating source support 132, so a high degree of freedom is obtained in the installation method of the heating device 180 (the positional relationship between the working area SP and the magnetic field generating source 120A). For example, it is possible to heat the object 12 to be heated by moving the heating device 180 itself. In addition, it is possible to use the heating device 180 in various forms, for example by placing the heating device 180 on the floor surface and using the space above it as the working area SP.

Sixth Embodiment
Next, a sixth embodiment will be described. In the following description, the same reference numerals are used to designate parts corresponding to those in the other embodiments described above, and the description thereof may be omitted.
FIG. 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 hot water supply pipe 214, a lifting table 215, a coating device 220, an ejection device 230, a mold cavity 250, metal rods 272, 274, mold heating devices 282, 284, and an aluminum melting device 286.

The mold cavity 250 includes a fixed mold 256 and a movable mold 258, which are molds for metal products (not shown), a fixed platen 252 that mounts and supports the fixed mold 256, and a movable platen 254 that mounts and supports the movable mold 258. The injection sleeve 211 is formed in a roughly cylindrical shape and is attached to 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 roughly cylindrical shape and moves back and forth within the injection sleeve 211.

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.

The holding furnace 213 is disposed below the injection sleeve 211 and contains molten metal M. The upper end of the supply pipe 214 is connected to a supply port 211a formed in the injection sleeve 211. The lower end 214a of the supply pipe 214 is immersed in the molten metal M in the holding furnace 213. The aluminum melting device 286 is a heating device according to any one of the first to fifth embodiments described above, and melts the heated object 12, which is aluminum or an aluminum alloy, to produce molten metal M, which is then poured into the holding furnace 213.

The vacuum pump 240 is connected to the cutoff valve 242 via a pipe 244. The cutoff valve 242 is connected to the mold cavity 250. This allows the vacuum pump 240 to reduce the pressure inside the mold cavity 250 to a vacuum state and suck the molten metal M in the holding furnace 213 into the injection sleeve 211.

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 supply pipe 214 is made of ceramic with a BN coating on the inside to prevent reaction with the molten metal M, and the lower end 214a is orifice-shaped. The outer periphery of the supply pipe 214 is surrounded by a heater (not shown), which keeps the supply pipe 214 close to the temperature of the molten metal M.

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.

[Effects of the embodiment]
According to the above-described embodiment, the heating devices 100, 150, 160, 170, 180 heat the heated object 12 by applying a magnetic field to the working area SP, which is an area where the heated object 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 wound with superconducting wire, and are provided with a magnetic field generating source 24, 120 that moves relative to the working area SP, and the magnetic field generating source 24, 120 suppresses leakage magnetic field generated by the magnetic field generating source 24, 120 that leaks to the outside, and is provided with a magnetic shield (9, 50, 92, 93, 99) that moves at the same speed as the magnetic field generating source 24, 120.

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

Furthermore, the superconducting coil operates in a persistent current mode, and it is even more preferable that the motion of the magnetic field generating source 24, 120 is a rotational motion about the first axis (L1). This allows a changing magnetic field to be continuously applied to the working area SP.

Furthermore, the heated object 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 approximately parallel. This makes it easier to handle the heated object 12, for example, when the heated object 12 is a long object.

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

Moreover, it is more preferable that the superconducting coil 7c, in which the third axis (L3) and the first axis (L1) are not perpendicular to each other, is provided in multiple locations along the first axis (L1). This makes it possible to strengthen the magnetic field generated by the superconducting coil (7c).

Furthermore, as in the second to fifth embodiments, it is even 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 it equivalent to having no magnetic field source when viewed from a distance (a point at infinity), and to reduce the leakage magnetic field.

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

Furthermore, as in the fourth to sixth embodiments, the heated object 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. This makes it easier to handle the heated object 12, for example, when the heated object 12 is flat.

Furthermore, as in the fourth embodiment, it is even 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 multiple locations so as to move at the same speed. This allows the magnetic field between the magnetic field generating sources 120A and 120B to rotate stably.

[Modification]
The present invention is not limited to the above-mentioned embodiment, and various modifications are possible. The above-mentioned embodiment is exemplified to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to delete a part of the configuration of each embodiment, or to add or replace other configurations. In addition, the control lines and information lines shown in the figure show those that are considered necessary for explanation, and do not necessarily show all the control lines and information lines necessary on the product. In reality, it may be considered that almost all the configurations are connected to each other. Possible modifications of the above-mentioned embodiment are, for example, as follows.

(1) In each of the above embodiments, a motor 40 is provided outside the magnetic field generating source 24, 120 to rotate the magnetic field generating 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 generating source support 130, 132, thereby generating a rotational force in the return yoke 9 or iron yoke 99 of the magnetic field generating source 24, 120.

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

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 coil (second coil)
9 Return yoke (magnetic shield)
12 object to be heated 24, 120 magnetic field source 50 passive shield (magnetic shield)
92, 93, 99 Yoke (magnetic shield)
100, 150, 160, 170, 180 Heating device 120, 120A, 120B Magnetic field generating source 282, 284 Mold heating device 286 Aluminum melting device L1 Rotation axis (first axis)
L2 conveying axis (second axis)
L3: winding central axis (third axis)
SP Working Area

Claims (11)

The heating device heats an object to be heated, including a metal, by applying a magnetic field to the working area, which is an area where the object to be heated includes a metal, using a superconducting coil having a superconducting wire wound therearound, and the heating device is provided with a magnetic field generating source that moves relative to the working area;
A heating device characterized in that the magnetic field generating source is provided with a magnetic shield that suppresses leakage magnetic field from the magnetic field generated by the magnetic field generating source that leaks to the outside and moves at the same speed as the superconducting coil. The superconducting coil is operated in a persistent current mode,
2. The heating device according to claim 1, wherein the motion of the magnetic field generating source is a rotational motion about a first axis. the object to be heated extends or is conveyed along a second axis;
The heating device according to claim 2 , wherein the first axis and the second axis are substantially parallel to each other. 4. The heating device according to claim 3, wherein the superconducting coil is formed by winding a superconducting wire around a third axis as a central winding axis, 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. The heating device according to claim 4 , wherein the superconducting coil, the third axis of which is not perpendicular to the first axis, is provided in plurality along the first axis. The superconducting coil comprises:
a first coil generating a first magnetic field;
The heating device according to claim 1 , further comprising: a second coil generating a magnetic field in a direction opposite to that of the first magnetic field. The superconducting coil comprises:
The heating device according to claim 1 , further comprising a plurality of magnetic field generating sources that change the magnetic field at different speeds in response to the movement of the magnetic field generating source. the object to be heated extends or is conveyed along a second axis;
The heating device according to claim 2 , wherein the first axis and the second axis are substantially perpendicular to each other. The heating device according to claim 8 , wherein a plurality of the magnetic field generating sources are provided so as to be opposed to each other across a working area and move at the same speed. An aluminum melting apparatus comprising the heating device according to any one of claims 1 to 9. A mold heating device comprising the heating device according to any one of claims 1 to 9.

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