JP2021050865A - Arc melting furnace device and arc melting method for object to be melted - Google Patents

Abstract

To provide an arc melting furnace and a melting method for the object to be melted having Lorentz force acted on the object to be melted suppressed by making magnetic field intensity by a magnet variable.SOLUTION: An arc melting furnace device 1 comprises a mold 3 with a recessed part 3a installed in a melting chamber 2 and an arc electrode 5 heating and melting the object to be melted stored in the recessed part 3 and comprises a permanent magnet 20 arranged at the lower part of the mold 3 for applying a magnetic field in a crossed direction to the direction of an electric current flowing through the inside of the object to be melted by arc discharge from the arc electrode 5 and a permanent magnet advance/retreat mechanism 21 advancing/retreating the permanent magnet 20 to the mold 3 for changing a magnetic flux density in the mold recessed part 3a by the permanent magnet 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to an arc melting furnace apparatus and an arc melting method of an object to be dissolved, and for example, an arc melting furnace apparatus and an arc melting method of an object to be dissolved, to which the substance to be dissolved can be preferably applied to an alloy or the like.

Conventionally, the arc melting method has been used to obtain a substance to be dissolved such as a pure metal ingot, an alloy ingot composed of a plurality of metal elements, and an alloy ingot composed of a metal element and a non-metal element with high purity. There is.
However, in this arc melting method, it is difficult to stir the molten material, so that there is a problem that a metal ingot of uniform quality cannot be obtained, especially in an alloy composed of a plurality of elements in which the material to be dissolved is difficult to be mixed uniformly. It was.

As an apparatus for solving this problem, Patent Document 1 proposes an apparatus for melting a metal material using an arc melting furnace that melts the metal material by an arc discharge. Specifically, this melting device includes a magnet for applying a magnetic field in a direction intersecting the direction of the current flowing through the metal material by arc discharge.

The reason why the metal material melting apparatus shown in Patent Document 1 stirs the melted material to be dissolved will be described with reference to FIGS. 6 and 7.
As shown in FIGS. 6 and 7, the hearth 50 of the melting device is made of a water-cooled copper hearth, and the hearth 50 is provided with a ring-shaped permanent magnet (Magnet ring) 51 whose magnet is made of samarium-cobalt (SmCo) or the like. ing.
As shown in FIGS. 6A and 7, when the metal material M is put into the hearth 50 and an arc is generated from the arc electrode arranged above the hearth, the heat of the arc causes the metal material M to move from the upper part to the lower part. The metal material M melts. At this time, since the electric resistance of the molten metal (Molten allloy) increases as the temperature increases, the arc current (Arc DC current) first moves toward the bottom of the molten metal in which an undissolved region (Insufficient metal region) having a small electric resistance can be seen. Further there, towards the adhesion formed between the bottom edge of the molten metal M and the hearth 50. That is, at the bottom of the molten metal M, it is considered that the molten metal M flows in a substantially horizontal direction from the center to the peripheral edge.

Further, at this time, since the ring-shaped magnet 51 arranged below the hearth 50 applies an upward magnetic field (Magnetic Field) inside the molten metal M, electromagnetic induction is applied to the molten metal M carrying an arc current. Electromagnetic force is generated by this.
This force has a direction perpendicular to each of the arc current flowing almost horizontally from the center of the molten metal M toward the periphery and the upward magnetic field at the bottom of the molten metal M, and the molten metal in the horizontal plane. Acts to rotate.
The stronger the arc current and the stronger the magnet, the stronger this force.

By this horizontal rotation, the undissolved portion is involved and the bottom portion of the molten metal M is agitated, and the vertical rotation in the vertical direction due to heat convection is added, so that the entire molten metal becomes uniform as shown in FIG. 6 (b). It can be dissolved in and stirred (Homogenization).

As described above, since the metal material melting device is provided with a magnet and applies a magnetic field in a direction intersecting the direction of the current flowing in the metal material by arc discharge, the direction of the current and the direction of the magnetic field. A force is generated in the direction perpendicular to.
Then, a flow is generated in the metal material melted by the arc discharge along the direction of the force, so that the metal material can be agitated. As described above, this melting device can agitate a metal material with a relatively simple structure in which a magnetic field is applied together with an arc discharge.

Japanese Unexamined Patent Publication No. 2013-245354

As described above, in the metal material melting apparatus proposed in Patent Document 1, a magnet is arranged in the hearth and is oriented in a direction intersecting the direction of the current flowing through the metal material due to arc discharge. Since a magnetic field is applied, a so-called Lorentz force is generated, and this force acts on the molten metal to stir it.
However, this Lorentz force becomes stronger as the arc current is stronger and as the magnet is stronger.
Therefore, when a current required for melting is applied to the arc electrode, an excessive Lorentz force may act on the molten metal in combination with the magnetic flux density of the magnet. Therefore, there is a technical problem that the molten material is scattered as droplets from the molten metal surface of the melted material to be dissolved, and an alloy (dissolved material) having a predetermined amount and a target mixing ratio cannot be obtained.

In addition, when the melted material solidifies while the Lorentz force acts on the melted material, the solidified material does not have an ellipsoidal shape but a rough spherical cap or annulus (torus) shape on the upper surface. There is a technical problem that the distorted shape such as the above affects the reversal failure of the rotation at the time of reversing the object to be dissolved in the subsequent process and the vacuum holding failure at the time of vacuum suction transfer.

On the other hand, by weakening the magnetic field strength of the magnet and reducing the magnetic flux density, the Lorentz force can be reduced, and it is possible to suppress the molten matter from being scattered as droplets from the molten metal surface.
However, when the Lorentz force acting on the melted substance to be dissolved is reduced, there is a technical problem that the melted substance to be dissolved cannot be sufficiently agitated and a uniform substance to be dissolved cannot be obtained.

The present inventors have found that the Lorentz force acting on a substance to be dissolved can be controlled by changing the magnetic field strength to solve the above technical problems, and have completed the present invention.
That is, by increasing the magnetic field strength of the magnet, the Lorentz force acting on the molten material to be dissolved is increased, and the molten material is sufficiently agitated.
On the other hand, by reducing the magnetic field strength of the magnet, the Lorentz force acting on the molten material to be dissolved is reduced, and the dissolved material is suppressed from being scattered as droplets from the surface of the molten material. Further, by reducing the Lorentz force acting on the molten material to be dissolved and solidifying the molten material to be dissolved, the material to be dissolved can be formed into an ellipsoidal shape.

As described above, it is an object of the present invention to provide an arc melting furnace apparatus and a method for melting an object to be melted, in which the Lorentz force acting on the melt is controlled by varying the magnetic field strength by a magnet.

In the arc melting furnace apparatus according to the present invention, which has been made to achieve the above object, a mold having a recess installed inside the melting chamber and an arc electrode for heating and melting the material to be melted contained in the recess are provided. An arc melting furnace device provided, which is arranged below the mold in order to apply a magnetic field in a direction intersecting the direction of the current flowing in the object to be melted by an arc discharge from the arc electrode. It is characterized by comprising a permanent magnet and a permanent magnet advancing / retreating mechanism for advancing / retracting the permanent magnet with respect to the mold in order to change the magnetic current density in the mold recess due to the permanent magnet.

As described above, since the arc melting furnace apparatus according to the present invention is provided with the permanent magnet advancing / retreating mechanism for advancing / retracting the permanent magnet with respect to the mold, the magnetic flux density in the mold recess due to the permanent magnet is changed. It is possible to control the Lorentz force acting on the object to be dissolved.
As a result, the dissolved product can be more agitated by applying a large Lorentz force, while the scattering of the dissolved product from the molten metal surface can be suppressed by applying a small Lorentz force. Further, the action of the Lorentz force is made smaller to solidify the melted substance to be dissolved, so that the substance to be dissolved can be formed into an ellipsoidal shape.

Here, when the permanent magnet is closest to the lower side of the mold by the permanent magnet advance / retreat mechanism, it is desirable that the absolute value of the magnetic flux density at the lowest bottom surface of the recess is within the range of 5 mT or more and 200 mT or less.
When the absolute value of the magnetic flux density at the lowest bottom surface of the recess is less than 5 mT, the magnetic field strength is small and the molten material to be melted cannot be sufficiently agitated, which is not preferable.
Further, when the absolute value of the magnetic flux density at the lowest bottom surface of the recess exceeds 200 mT, it is not preferable because the scattering of the melted material to be dissolved cannot be suppressed.

Further, when the permanent magnet is farthest from the lower part of the mold by the permanent magnet advance / retreat mechanism, it is desirable that the absolute value of the magnetic flux density at the lowest bottom surface of the recess is less than 5 mT.
By setting the absolute value of the magnetic flux density at the lowest bottom surface of the recess to less than 5 mT, the melted material can be formed into an ellipsoidal shape when the melted material is solidified.

Further, it is desirable that the permanent magnet advance / retreat mechanism controls the permanent magnet so as to be closest to the lower side of the mold and the permanent magnet to be farthest from the lower side of the mold. It is desirable that the closest state and the farthest state are repeated.
In this way, the permanent magnet is placed closest to the underside of the mold and the permanent magnet is placed farthest from the bottom of the mold, so that the substance to be dissolved can be more agitated and dissolved. It is possible to prevent the dissolved substances from splashing from the surface of the hot water of the object. Further, the material to be dissolved can be further agitated by repeating the process in which the permanent magnet is closest to the lower side of the mold and the permanent magnet is farthest from the lower side of the mold.

When the molten material is solidified, it is preferable that the permanent magnet advance / retreat mechanism is in a state where the permanent magnet is farthest from the lower part of the mold. By reducing the Lorentz force acting on the substance to be dissolved and solidifying the melted substance to be dissolved, the substance to be dissolved can be formed into an ellipsoidal shape.

The method for dissolving the material to be dissolved according to the present invention, which has been made to achieve the above object, is a mold having a recess installed inside the melting chamber and an arc electrode for heating and melting the material to be dissolved contained in the recess. A method of melting an object to be melted using an arc melting furnace device provided with the above, wherein the arc melting furnace device refers to the direction of an electric current flowing through the object to be melted by an arc discharge from the arc electrode. A permanent magnet placed below the mold to apply a magnetic field in the intersecting direction and a permanent magnet advancing and retreating to advance and retreat the permanent magnet with respect to the mold in order to change the magnetic flux density in the mold recess due to the permanent magnet. The permanent magnet is controlled by the permanent magnet advance / retreat mechanism at a position closest to the lower side of the mold and a position farthest from the lower part of the mold, and the permanent magnet is farthest from the lower part of the mold. It is characterized in that the molten material is solidified in the state.

As described above, in the method for dissolving the material to be dissolved according to the present invention, the permanent magnet is controlled to the position closest to the lower side of the mold and the position farthest from the lower side of the mold by the permanent magnet advance / retreat mechanism. In addition, since the position closest to the lower side of the mold and the position farthest from the lower side of the mold are repeated as necessary, the magnetic flux density (magnetic field strength) in the concave portion of the mold by the permanent magnet is changed. The Lorentz force acting on the material to be dissolved can be controlled.
As a result, by increasing the Lorentz force, the material to be dissolved can be more agitated, while by reducing the Lorentz force acting on the material to be dissolved, the melted material is melted from the molten metal surface. It is possible to suppress the scattering of the substance to be dissolved. Finally, the permanent magnet is placed farthest from the bottom of the mold, the Lorentz force acting on the material to be dissolved is reduced, and the material to be dissolved is solidified, so that the shape of the material to be dissolved is adjusted. And the object to be dissolved can be made into an ellipsoidal shape.

According to the present invention, by varying the magnetic field strength of the magnet as described above, it is possible to obtain an arc melting furnace device and a method for melting an object to be melted, in which the Lorentz force acting on the melt is controlled.

It is sectional drawing which shows the schematic structure of the embodiment which concerns on the arc melting furnace apparatus of this invention. It is a schematic block diagram which shows an example of the permanent magnet advance / retreat mechanism shown in FIG. In the embodiment of the present invention, it is a schematic block diagram showing a state in which the permanent magnet is closest to the lower side of the mold by the permanent magnet advancing / retreating mechanism. In the embodiment of the present invention, it is a schematic block diagram showing a state in which the permanent magnet is farthest from the bottom of the mold by the permanent magnet advance / retreat mechanism. It is a figure which showed the degree of change of the magnetic flux density by the distance from the permanent magnet surface. The operating principle of the metal material melting apparatus and the metal material melting method described in Patent Document 1 is (a) a cross-sectional view showing the directions of arc current, magnetic field, and force applied to the molten metal, and (b) the molten metal after stirring. It is sectional drawing which shows. It is a perspective view which shows the arc current and the force applied to the molten metal of the operation principle of the metal material melting apparatus and the metal material melting method described in Patent Document 1. FIG.

Hereinafter, the arc melting furnace apparatus according to the embodiment of the present invention will be described with reference to the drawings.
First, the overall configuration of the arc melting furnace device 1 according to the embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, in the arc melting furnace device 1, the copper mold 3 is in close contact with the lower surface of the melting chamber 2, and the melting chamber 2 is a closed container.
Further, below the copper mold 3, a cooling body 4 having a water flow path 4a through which cooling water circulates is provided, and by arranging the copper mold 3 on the cooling body 4, the copper mold 3 is made into a water-cooled mold. ing.

Further, reference numeral 5 in the drawing is a rod-shaped water-cooled electrode (arc electrode), and the water-cooled electrode (arc electrode) 5 is provided with a tungsten tip as a cathode and is inserted into the room from above the melting chamber 2. Has been done.
The tungsten tip of the water-cooled electrode (arc electrode) 5 is arranged at a position facing the upper surface (recessed portion 3a) of the copper mold 3. Further, the tip of the water-cooled electrode (arc electrode) 5 can be moved up and down, front and back, and left and right in the melting chamber 2 by operating a handle portion (not shown).
Further, the water-cooled electrode 5 is electrically connected to the cathode of the power supply unit 10 to supply electric power to the water-cooled electrode 5. Further, the anode side of the power supply unit 10 is grounded together with the melting chamber 2 and the copper mold 3.

Further, a vacuum pump (not shown) is attached to the melting chamber 2, and the melting chamber 2 can be evacuated to a vacuum by this vacuum pump.
An inert gas supply unit (not shown) is provided, and after the dissolution chamber 2 is exhausted to a vacuum, the inert gas is supplied and sealed inside the dissolution chamber 2 from the inert gas supply unit, and the dissolution chamber 2 is sealed. The inside of 2 is an inert gas atmosphere.

Further, a permanent magnet 20 is arranged below the mold 3 in order to apply a magnetic field in a direction intersecting the direction of the current flowing in the object M due to the arc discharge from the water-cooled electrode (arc electrode) 5. Has been done.

The permanent magnet 20 is, for example, a neodymium magnet, which is a disk-shaped magnet having a magnetic flux density of 430 mT and an outer diameter of 30 mm, and is configured to have an S pole on the upper surface side and an N pole on the lower surface side. The effect is the same even if the upper surface side has an N pole and the lower surface side has an S pole.
Further, the permanent magnet 20 is not limited to a disk shape, and may be a ring-shaped magnet. As an example, a ring-shaped magnet having an outer diameter of 30 mm, an inner diameter of 6 mm, and a thickness of 10 mm may be used.

The permanent magnet 20 is configured to be able to move up and down by a permanent magnet advancing / retreating mechanism 21, and is configured so that the magnetic flux density (magnetic field strength) in the mold recess 3a changes by advancing / retracting the permanent magnet 20 with respect to the mold 3. ing.

An example of the permanent magnet advance / retreat mechanism 21 will be described with reference to FIG.
The permanent magnet advance / retreat mechanism 21 includes a piston rod 21a to which the permanent magnet 20 is attached to the tip, a piston 21b attached to the rear end of the piston rod 21a, and a cylinder 21c to which the piston 21b slides. ..

Further, a chamber 21d and a chamber 21e are provided in the cylinder 21c. The chambers 21d and 21e are formed by partitioning the inside of the cylinder 21c with a piston 21b.
The chambers 21d and 21e are provided with air introduction / discharge ports 21f and 21g. The air introduction / discharge ports 21f and 21g are connected to the compressor 21h. Further, the compressor 21h is connected to an advancing / retreating mechanism control unit 22 that controls a switching valve or the like (not shown).

Then, when air is introduced into the chamber 21d from the air introduction / discharge port 21f and the piston 21b slides, the air in the chamber 21e is discharged from the air introduction / discharge port 21g.
Similarly, when air is introduced into the chamber 21e from the air introduction / discharge port 21g and the piston 21b slides, the air in the chamber 21d is discharged from the air introduction / discharge port 21f. That is, by operating a switching valve (not shown), the air from the compressor 21h is introduced into either the air introduction / discharge port 21f or the air introduction / discharge port 21g.

In this way, when air is introduced into either the air introduction / discharge port 21f or the air introduction / discharge port 21g, the piston rod 21a to which the permanent magnet 20 is attached to the tip moves back and forth (moves up and down). ).
Then, by advancing and retreating the permanent magnet 20 with respect to the mold 3, the magnetic flux density (magnetic field strength) in the mold recess 3a changes.

FIG. 5 shows an example of the rate at which the magnetic field strength (magnetic field density) changes depending on the distance from the magnet surface. As shown in FIG. 5, in a permanent magnet having a magnetic flux density of 186 mT at 2 mm from the surface, it becomes 104 mT at a distance of 10 mm from the surface and 14 mT at a distance of 40 mm.
Therefore, by moving the permanent magnet 20 back and forth with respect to the mold 3, the magnetic flux density (magnetic field strength) in the mold recess 3a changes. The Lorentz force acting on the substance to be dissolved becomes stronger as the magnetic flux density (magnetic field strength) in the mold recess 3a is stronger.

As a result, the Lorentz force can be increased to stir the substance to be dissolved more, while the Lorentz force acting on the substance to be dissolved can be reduced to suppress the scattering of the substance to be dissolved from the surface of the molten metal. be able to.
Further, by reducing the Lorentz force acting on the substance to be dissolved and solidifying the melted substance to be dissolved, the substance to be dissolved can be formed into an ellipsoidal shape.

Specifically, when the permanent magnet 20 is closest to the lower side of the mold 3 by the permanent magnet advance / retreat mechanism 21, the absolute value of the magnetic flux density (magnetic field strength) at the lowest bottom surface of the recess 3a is in the range of 5 mT or more and 200 mT or less. The magnetic flux density of the magnet is selected so that it is inside.
When the absolute value of the magnetic flux density at the lowest bottom surface of the recess 3a is less than 5 mT, the magnetic field strength is small and the substance M to be dissolved cannot be sufficiently agitated, which is not preferable.
Further, when the absolute value of the magnetic flux density at the lowest bottom surface of the recess 3a exceeds 200 mT, the scattering of the melted substance M cannot be suppressed, which is not preferable.

Preferably, when the permanent magnet 20 is closest to the lower side of the mold 3, the absolute value of the magnetic flux density (magnetic field strength) of the lowest bottom surface of the recess 3a is within the range of 5 mT or more and 200 mT or less, and further, the recess 3a. The absolute value of the magnetic flux density (magnetic field strength) at the upper end is within the range of 1 mT or more and 50 mT or less. This is because a sufficient magnetic flux density is secured even at the upper end portion of the recess 3a, and the object to be dissolved M in the recess 3a is sufficiently agitated.

Further, when the permanent magnet 20 is farthest from the lower part of the mold 3 by the permanent magnet advance / retreat mechanism 21, it is desirable that the absolute value of the magnetic flux density at the lowest bottom surface of the recess 3a is less than 5 mT.
By setting the absolute value of the magnetic flux density at the lowest bottom surface of the recess 3a to less than 5 mT and solidifying the melted substance to be dissolved, the object to be dissolved can be formed into an ellipsoidal shape.

Further, the permanent magnet advancing / retreating mechanism 21 controls the permanent magnet 20 to be closest to the lower side of the mold 3 and the permanent magnet 20 to be farthest from the lower side of the mold 3.
That is, the permanent magnet 20 is controlled between the state shown in FIG. 3 and the state shown in FIG. 4, or the permanent magnet 20 is repeatedly repeated in the state shown in FIG. 3 and the state shown in FIG.
In this way, the state in which the permanent magnet 20 is closest to the lower part of the mold 3 and the state in which the magnetic field source 20 is farthest from the lower part of the mold 3 are controlled or repeated as necessary. The lysate M can be more agitated.

When the molten material M is solidified, the permanent magnet advancing / retreating mechanism 21 is preferably in a state where the permanent magnet 20 is farthest from the lower part of the mold 3.
By reducing the Lorentz force acting on the substance to be dissolved M and solidifying the melted substance M to be dissolved, the surface tension of the substance to be dissolved can cause the substance to be dissolved to have an ellipsoidal shape.

Further, in the arc melting furnace device 1, as shown in FIG. 1, the shape change of the molten metal of the material to be melted is measured, and the detection signal corresponding to the measured shape of the molten metal is output to the control device 11. The molten metal measuring means 12 is provided.
Specifically, the shape of the molten metal is image-analyzed by a CCD camera or the like, and a detection signal corresponding to the image change (shape change) is sent to the control device. Then, the control device 11 controls the output current (current intensity) from the power supply unit 10 and the current frequency, and is configured to add strength to the output intensity of the arc discharge from the water-cooled electrode 5.
In this way, by adding strength to the output strength of the arc discharge, it is possible to add strength to the Lorentz force acting on the substance M to be dissolved.

Further, the control device 11 sends a control signal to the advancing / retreating mechanism control unit 22 that controls the permanent magnet advancing / retreating mechanism 21 so as to perform a predetermined ascending / descending operation. Upon receiving the control signal, the advancing / retreating mechanism control unit 22 controls a switching valve (not shown), introduces air from the compressor 21h into either the air introduction / discharge port 21f or the air introduction / discharge port 21g, and causes the piston rod 21a. Move the permanent magnet 20 up and down.
The permanent magnet advance / retreat mechanism 21 is provided with a sensor (not shown) for detecting the position of the piston rod 21a, a signal from the sensor is sent to the advance / retreat mechanism control unit 22, and air from the compressor 21h is introduced. The air inlet / outlet is selected. Further, the movement of the piston rod 21a is stopped by a signal from the sensor.

In this way, the control device 11 controls the advancing / retreating mechanism control unit 22 of the permanent magnet advancing / retreating mechanism 21.
In addition to the advancing / retreating operation of the permanent magnet advancing / retreating mechanism 21, as described above, the control device 11 controls the Lorentz force acting on the object M by adding strength to the output intensity of the arc discharge. Is also good.

Further, a reversing rod 6 operated from the outside of the melting chamber 2 is provided, and after cooling the melted material to be melted, the material (dissolved) is placed on the copper mold 3 (recess 3a) by the reversing rod 6 from the outside of the melting chamber 2. Thing) M is made to be able to be inverted.
In FIG. 1, reference numeral 7 is a lever for operating the lower surface portion of the melting chamber 2, and the copper mold 3 on the lower surface portion can be removed from the melting chamber 2 by operating the lever 7. The material to be dissolved can be stored on the copper mold 3 (inside the recess 3a), and the material to be dissolved can be taken out from the inside of the recess 3a.

Next, a method of melting the material to be dissolved in the arc melting furnace will be described with reference to FIGS. 1 to 4.
First, the weighed material to be dissolved is placed on the copper mold 3 (accommodated in the recess 3a). Then, after the inside of the melting chamber 2 is made into an inert gas, usually an argon gas atmosphere, an arc discharge is generated between the tungsten electrode (cathode) of the water-cooled electrode 5 and the object to be dissolved M (anode) on the copper mold 3. To dissolve the object to be dissolved M.
In the production of the alloy, a plurality of metal materials are weighed and placed on the copper mold 3 (accommodated in the recess 3a). Then, as in the above case, after the inside of the dissolution chamber 2 is made into an inert gas, usually an argon gas atmosphere, between the tungsten electrode (catalyst) of the water-cooled electrode 5 and the alloy material M (anode) on the copper mold 3. An arc discharge is generated at the above, and a plurality of different alloy materials M are melted and alloyed by the thermal energy.

At this time, a magnetic field in the vertical direction is applied to the object M to be dissolved in the copper mold 3 by the permanent magnet 20 having the S pole arranged at the upper part and the N pole arranged at the lower part. Therefore, stirring is performed according to the basic principle shown in FIGS. 6 and 7.
By the way, in reality, the liquefaction of the bottom surface of the object to be dissolved in contact with the water-cooled copper mold is slow, the dissolution starts from the upper part, and the rotation starts from the melted portion as shown in FIG. 3A. Then, as the melting progresses, the rotation of the molten metal becomes violent, and as shown in FIG. 3 (b), the molten metal rises along the slope of the recess due to the centrifugal force, and the raised molten metal falls toward the central portion. Effective stirring is performed by such movement.

Then, when the substance to be dissolved is dissolved, the permanent magnet 20 is located at the position closest to the lower side of the mold 3 by the permanent magnet advancing / retreating mechanism 21 as shown in FIG. 3 (b), and is shown in FIG. 4 (b). As described above, the position farthest from the lower part of the mold 3 can be taken.

As shown in FIG. 3B, when the permanent magnet 20 is located closest to the lower side of the mold 3 by the permanent magnet advancing / retreating mechanism 21, the magnetic flux density at the lowest bottom surface of the recess 3a becomes the largest.
That is, when the permanent magnet 20 is located closest to the lower side of the mold 3, the Lorentz force acting on the object to be dissolved M becomes the strongest, and as shown in FIG. 3A, the molten object to be dissolved is dissolved. The object M rotates. At this time, as shown in FIG. 3B, the molten material spreads outward in the radial direction of the recess 3a due to the rotation.
The material to be dissolved M is agitated by such a rotating operation and a spreading operation of the material to be dissolved.

Further, according to the permanent magnet advancing / retreating mechanism 21 shown in FIG. 4B, when the permanent magnet 20 is located at the farthest position below the mold 3, the magnetic flux density at the lowest bottom surface of the recess 3a becomes the smallest.
That is, when the permanent magnet 20 is located at the farthest position below the mold 3, the Lorentz force acting on the object to be dissolved M becomes small, and the rotation of the molten object M becomes slow or rotates. As shown in FIGS. 4A and 4B, the melted object has an ellipsoidal shape due to its own weight and surface tension.

Therefore, the permanent magnet advancing / retreating mechanism 21 controls the permanent magnet 20 to be closest to the lower side of the mold 3 and the permanent magnet 20 to be farthest from the lower side of the mold 3. Stirring of the molten material M is further enhanced by repeating the two states as necessary.
As already described, when the permanent magnet 20 is closest to the lower side of the mold 3 by the permanent magnet advance / retreat mechanism 21, the absolute value of the magnetic flux density at the lowest bottom surface of the recess 3a is within the range of 5 mT or more and 200 mT or less. Is desirable. Further, it is desirable that the absolute value of the magnetic flux density at the lowest bottom surface of the recess 3a is less than 5 mT when the permanent magnet 20 is farthest from the lower part of the mold 3 by the permanent magnet advance / retreat mechanism 21.

Then, the state in which the permanent magnet 20 is closest to the lower side of the mold 3 and the state in which the permanent magnet 20 is farthest from the lower side of the mold 3 are repeated, and finally, the permanent magnet 20 is closest to the lower side of the mold 3. The material to be dissolved M is solidified in a separated state.
By reducing the Lorentz force acting on the substance M to be dissolved and solidifying it, the shape of the substance M to be dissolved can be adjusted, and the melted substance M to be dissolved can be formed into an ellipsoidal shape.

1 Arc melting furnace device 2 Melting chamber 3 Copper mold 3a Recess 4 Cooler 4a Water flow path 5 Water cooling electrode (arc electrode)
6 Reversing rod 7 Lower surface operation lever 10 Power supply unit 11 Control device 12 Molten metal measuring means 20 Permanent magnet 21 Permanent magnet advance / retreat mechanism 21a Piston rod 21b Piston 21c Cylinder 21d Room 21e Room 21f Air introduction / discharge port 21g Air introduction / discharge port 21h Compressor 22 Advance / retreat mechanism control unit

Claims (6)

An arc melting furnace device including a mold having a recess installed inside the melting chamber and an arc electrode for heating and melting the material to be melted contained in the recess.
A permanent magnet arranged below the mold to apply a magnetic field in a direction intersecting the direction of the current flowing in the object to be dissolved by the arc discharge from the arc electrode.
In order to change the magnetic flux density in the concave portion of the mold by the permanent magnet, a permanent magnet advancing / retreating mechanism for advancing / retreating the permanent magnet with respect to the mold,
An arc melting furnace apparatus comprising. The arc according to claim 1, wherein when the permanent magnet is closest to the lower side of the mold by the permanent magnet advance / retreat mechanism, the absolute value of the magnetic flux density at the lowest bottom surface of the recess is in the range of 5 mT or more and 200 mT or less. Melting furnace equipment. The arc melting furnace according to claim 1 or 2, wherein when the permanent magnet is farthest from the lower part of the mold by the permanent magnet advance / retreat mechanism, the absolute value of the magnetic flux density at the lowest bottom surface of the recess is less than 5 mT. apparatus. The permanent magnet advance / retreat mechanism controls the permanent magnet to be closest to the lower side of the mold and the permanent magnet to be farthest from the lower side of the mold.
The arc melting furnace apparatus according to claim 1, wherein the permanent magnets are repeatedly formed in the closest state and the farthest state. The method according to any one of claims 1 to 4, wherein when the melted substance to be melted solidifies, the permanent magnet advancing / retreating mechanism is set so that the permanent magnet is in the state farthest from the lower part of the mold. Arc melting furnace equipment. A method for melting an object to be dissolved, which comprises an arc melting furnace apparatus provided with a mold having a recess installed inside the dissolution chamber and an arc electrode for heating and dissolving the substance to be dissolved contained in the recess.
The arc melting furnace device includes a permanent magnet arranged below the mold in order to apply a magnetic field in a direction intersecting the direction of the current flowing in the object to be melted by the arc discharge from the arc electrode. ,
A permanent magnet advancing / retreating mechanism that advances and retreats the permanent magnet with respect to the mold in order to change the magnetic flux density in the mold recess due to the permanent magnet.
With
The permanent magnet is controlled by the permanent magnet advance / retreat mechanism to the position closest to the lower side of the mold and the position farthest from the lower side of the mold.
Alternatively, the permanent magnets are repeatedly placed in the closest state and the farthest state.
A method for dissolving a melted product, which comprises solidifying the melted product in a state where the permanent magnet is farthest from the bottom of the mold.

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