JPH07126766A - Electromagnetic float-up melting furnace - Google Patents

Abstract

PURPOSE:To improve the heating efficiency by winding a heating coil applying water- proof insulated coating on the outer periphery of a segment as a melting chamber, surrounding this segment with an outer frame for circulating cooling water and dipping this heating coil into the cooling water to narrow the interval between the heating coil and molten metal. CONSTITUTION:The outer periphery of the segment 14 to be as the melting chamber 2 formed of a copper-made cylinder 13 whose upper part is open is surrounded integrally with the outer frame 16 circulating the cooling water 15 and formed of a water-tight structure. This segment 14 is arranged with plural slits 17 radially in the longitudinal direction at an interval along the peripheral direction on the outer wall of the copper- made cylinder 13. This segment 14 has the structure with a formed ceramic thermal- spraying layer 19 on the inner wall and closed with embedded small ceramics 18 so that the cooling water 15 does not flow out into the segment 14. The heating coils 1 applied with the water-proof insulated coating 27 on the outer peripheries of their water-cooling copper pipes 26, are wound on the outer periphery of the segment 26 and dipped into the cooling water 15. By this constitution, the interval delta between the heating coil 1 and the molten metal 12, is narrowed and the heating efficiency of the heating coil 1 is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic levitation melting furnace in which a heating coil is immersed in cooling water.

[0002]

2. Description of the Related Art Instead of a conventional induction melting furnace in which a heat-insulating refractory material is lined to form a melting chamber, the melting chamber is made of metal, and the molten metal is floated in the melting chamber to clean a high-temperature, high-purity cleaner. An electromagnetic levitation melting furnace for melting is being developed.
In the structure of this electromagnetic levitation melting furnace, as shown in FIG. 6, for example, a water cooling segment 3 serving as a melting chamber 2 is provided inside a heating coil 1 in which a water cooling copper tube is spirally wound. The water-cooling segment 3 is formed by cutting a copper block to form a crucible-shaped copper tube having an upper opening, and a water passage 4 is formed in the vertical direction inside the side wall.

A copper hearth 5 is connected to the lower portion of the water cooling segment 3, and a water passage 6 on the water supply side is formed inside the copper hearth 5. The upper portion of the water passage 6 communicates with the water passage 4 formed inside the water cooling segment 3. A shield ring 8 having an annular water passage 7 formed therein is joined to the outer periphery of the upper side wall of the water cooling segment 3 serving as the melting chamber 2, and the annular water passage 7 is located above the water passage 7 of the water cooling segment 3. The cooling water 9 that has been communicated with and has risen here flows through the annular water passage 7 and reaches the water passage 10 on the drain side.
It is designed to be drained from the outside.

In the electromagnetic levitation melting furnace having the above-described structure, when a high-frequency alternating current of large power is supplied to the heating coil 1 while the cooling water 9 is being supplied, the alternating current induces the molten metal 12 in the melting chamber 2. The molten metal 12 has a levitation force due to the interaction with the counter electromotive current, and is heated and melted by the resistance of the molten metal itself and the counter electromotive current flowing there.
Since the molten metal 12 is floated and melted by heating in this manner, it does not come into contact with the side wall of the melting chamber 2 and high-temperature melting is possible and high-purity melting can be performed. Further, even if the molten metal 12 comes into contact with the side wall, the molten metal 12 is immediately rapidly cooled by the water-cooled segment 3 to protect the heating coil 1.

A water-cooled segment 3 which constitutes the melting chamber 2
A current is induced by the magnetic flux penetrating therethrough, a turn in which this induced current flows is formed, and the segment itself is overheated by the resistance of the segment itself, so it is necessary to have a water cooling structure. Therefore, it is necessary to widen the distance δ between the heating coil 1 and the molten metal 12, and there is a problem that the heating efficiency of the coil decreases when the distance δ becomes wide. Further, since a large current is passed through the heating coil 1 itself, it is also overheated. Therefore, the amount of current to be applied is regulated by the amount of water flowing through the cooling water 9 for cooling it, and there is a limit to adding large power. . Moreover, the conventional water-cooled segment 3 is made by processing a copper pipe and has a water passage 4 inside.
However, there is a problem in that the processing is troublesome and the apparatus becomes expensive because of the formation. Further, since a large current is applied to the heating coil 1, there is a problem that the peripheral equipment is overheated due to the leaked magnetic flux, and there is a drawback that the apparatus becomes large as a whole.

[0006]

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks and narrows the gap between the heating coil and the molten metal to improve the heating efficiency of the coil, and at the same time enhances the cooling property of the heating coil to generate a large current. (EN) Provided is an electromagnetic levitation melting furnace which can be energized, can be easily processed at low cost, and can be manufactured at a low cost while preventing overheating of a peripheral outer frame to downsize the apparatus.

[0007]

In the electromagnetic levitation melting furnace of the present invention, a plurality of vertical slits are provided radially at intervals along the circumferential direction on the side wall of a metal cylinder having an upper opening,
A segment serving as a melting chamber is formed by closing the slit with a ceramic, and the outer periphery of this segment is integrally surrounded by an outer frame having a watertight structure in which cooling water circulates, and a heating coil having a waterproof insulation coating on the outer periphery is formed. The heating coil is wound around the outer periphery of the segment and immersed in cooling water.

[0008]

In the electromagnetic levitation melting furnace of the present invention, cooling water is circulated in the outer frame to cool the heating coil and the segment. When a high-frequency alternating current of large power is passed through the heating coil in this state, the alternating current produces a levitation force in the molten metal by interaction with the counter electromotive current induced in the molten metal in the melting chamber, It is heated and melted by the resistance of the metal itself and the counter electromotive current that flows through it.

In this case, the outer periphery of the segment is surrounded by an outer frame having a watertight structure in which cooling water circulates and is in contact with a large amount of cooling water, so that the cooling property is excellent and the heating coil and the molten metal are Since the interval can be narrowed, the heating efficiency of the coil can be improved. Further, the segment is provided with a plurality of vertical slits radially on the side wall thereof at intervals along the circumferential direction, and the slits are closed with a ceramic to be electrically insulated along the circumferential direction. A loop of current induced by the magnetic flux penetrating through is not formed, so that loss due to overheating can be reduced and efficiency can be further improved. Further, since the cooling water flows inside the heating coil and the outer periphery covered with the waterproof insulating coating is immersed in the cooling water to be cooled from the inside and outside, a large current can be passed and it can be floated and melted with a large power.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIGS. This electromagnetic levitation melting furnace has a structure in which an outer circumference of a segment 14 which is a melting chamber 2 formed by a copper cylinder 13 having an open upper part is integrally surrounded by an outer frame 16 having a watertight structure in which cooling water 15 circulates. There is. As shown in FIG. 2, the segment 14 is provided with a plurality of vertical slits radially on the side wall of the copper cylinder 13 at intervals along the circumferential direction, and a ceramic 18 having a very low mechanical ratio is embedded in the slit 17. The cooling water 15 is prevented from flowing out into the segment and the ceramic sprayed layer 19 is formed on the inner wall of the segment to increase the heat resistance.

A shield ring 21 is provided on the upper portion of the outer frame 16 via an insulating ring 20 as shown in FIG. 1, and constitutes the upper portion of the melting chamber 2. Further, since the upper portion of the segment 14 which constitutes the melting chamber 2 is separated, as shown in FIG. 3, the insulating ring 20 and the screw 25 on the upper portion are connected and fixed.

The shield ring 21 has an annular water passage 22 formed therein as shown in FIG.
The cooling water in the outer frame 16 is connected to the outer frame 16 by 23, 23.
15 are circulated. Pure water having an insulating property is used as the cooling water 15. The cooling water 15 flows into the inside from the water passage 6 on the water supply side attached to the lower side of the outer frame 16, and the water passage 10 on the drain side attached to the upper side. It is designed to be drained from. Further, the heating coil 1 is wound around the outer periphery of the segment 14 serving as the melting chamber 2 and immersed in the cooling water 15. As shown in FIG. 4, the heating coil 1 is formed by winding a water-cooled copper pipe 26 around an outer periphery of the water-cooled copper pipe, for example, and vacuum impregnating a varnish with a waterproof insulating coating 27.

In the electromagnetic levitation melting furnace having the above-mentioned structure, the pure water cooling water 15 is supplied from the water passage 6 on the water supply side into the outer frame 16 to cool the heating coil 1 and the segment 14, and part of the insulating hose. It circulates through the annular water passage 22 of the shield ring 21 through 23 and is discharged from the water passage 10 on the drain side. In this state, when a high-frequency alternating current of large power is applied to the heating coil 1, the levitation force is exerted on the molten metal 12 by the interaction with the counter electromotive current induced in the molten metal 12 in the melting chamber 2 by this alternating current. While being obtained, it is heated and melted by the resistance of the molten metal itself and the counter electromotive current flowing there. Since the molten metal 12 floats and is heated and melted, it does not come into contact with the side wall of the melting chamber 2, and even if it comes in contact with it, the ceramic sprayed layer 19 having excellent heat resistance is formed, so that high-temperature melting becomes possible. , High-purity dissolution is possible.

In this case, the outer periphery of the segment 14 comes into contact with a large amount of cooling water 15 circulating in the outer frame 16 having a watertight structure and is excellent in cooling property, and the interval δ between the heating coil 1 and the molten metal 12 is set. Since it can be narrowed, the heating efficiency of the coil can be improved. Further, as shown in FIG. 2, the segment 14 is provided with slits 17 on its side wall in a radial direction in the circumferential direction, and the slits 17 are closed by a ceramic 18 to be electrically insulated in the circumferential direction. Since the turn of the current induced by the magnetic flux penetrating 14 is not formed and the insulating ring 20 is interposed between the shield ring 21 and the upper shield ring 21, the turn of the current flowing in the circumferential direction is formed. Therefore, the loss due to overheating of the segment 14 can be reduced, and the efficiency can be further improved.

Further, since the cooling water 9 flows through the heating coil 1 and the outer periphery provided with the waterproof insulating coating 27 is immersed in the cooling water 15 to be cooled from the inside and outside, a large current can flow.
It can be floated and melted with great power. In addition, the conventional water-cooled segment 3 had to be complicatedly machined by forming a large number of water passages 4 inside the copper pipe, but the segment 14 of the present invention has the slit 17 formed on the side wall of the copper pipe. Then, only by filling the ceramic 18 here, the processing is easy and the device can be manufactured at low cost. Also the outer frame
Since the inside of 16 is cooled by the cooling water 15, it is possible to prevent overheating of the outer frame 16 due to the leakage magnetic flux, and it is possible to reduce the size of the device as a whole.

Further, since a shield ring 21 is provided on the upper portion of the melting chamber 2 via an insulating ring 20 to form a continuous short-circuit ring, the magnetic flux leaked from the heating coil 1 to the upper portion of the melting chamber 2 is generated. , The shield ring 21 is linked, and a short circuit current flows there due to the counter electromotive force. The magnetic flux induced by the short-circuit current can cancel the magnetic flux from the heating coil 1 and prevent the magnetic flux from leaking above the melting chamber 2.

Therefore, the molten metal 12 that is trying to rise from the upper portion of the melting chamber 2 is pressed down so that it is not exposed from the melting chamber 2, and even if an unnecessarily large amount of power is applied, it is proportional to this. Since the pressing force is increased, the molten metal 12 is prevented from jumping out. Further, by disposing the shield ring 21 on the upper portion of the melting chamber 2 as described above, it is possible to prevent thermal influence on peripheral devices. Shield ring
Heat is generated when a short-circuit current flows through 21, but there is an annular water passage inside.
22 is formed and sufficiently cooled here, and since the shield ring 21 has a large cross-sectional area and a small resistance, the heat generated can be reduced and the melting furnace can have a large capacity.

FIG. 5 shows another embodiment of the present invention.
The whole of the heating coil 1 in which a water-cooled copper tube is spirally wound,
A cylindrical waterproof insulating coating 27 is formed by placing it in a molding die and fixing the surface with a resin. The cylindrical waterproof insulating coating 27 is arranged on the outer periphery of the segment 14 and immersed in the cooling water 15. This structure facilitates waterproof insulation of the heating coil 1.

[0019]

As described above, according to the present invention, the outer periphery of the segment serving as the melting chamber is integrally surrounded by the outer frame having the watertight structure in which the cooling water circulates, and the outer periphery of the segment is provided with the waterproof insulating coating. Since the heated heating coil is soaked in the cooling water and wound, the gap between the heating coil and the molten metal can be narrowed to improve the heating efficiency of the coil, and the cooling performance of the heating coil can be improved to supply a large current. In addition, it is possible to obtain an electromagnetic levitation melting furnace in which the apparatus can be processed easily and can be manufactured at low cost, and at the same time, the outer frame can be prevented from overheating and the apparatus can be downsized.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electromagnetic levitation melting furnace according to an embodiment of the present invention.

FIG. 2 is a horizontal sectional view of a segment serving as a melting chamber.

FIG. 3 is a vertical sectional view showing a fixing structure of an upper portion of a segment and an insulating ring.

FIG. 4 is an enlarged sectional view showing the heating coil of FIG.

FIG. 5 is a cutaway perspective view of a heating coil according to another embodiment of the present invention.

FIG. 6 is a sectional view showing a conventional electromagnetic levitation melting furnace.

[Explanation of signs] 1 heating coil 2 melting chamber 3 water cooling segment 4 water passage 8 shield ring 9 cooling water 12 molten metal 14 segment 15 cooling water 16 outer frame 17 slit 18 ceramic 20 insulating ring 21 shield ring 22 annular water passage 23 insulation Hose 27 waterproof insulation

Claims (1)

[Claims] 1. A metal cylinder having an open upper portion is provided with a plurality of vertical slits radially at intervals along a circumferential direction, and the slits are closed by a ceramic to form a segment serving as a melting chamber. The outer circumference of this segment,
It is characterized in that a heating coil having a watertight structure in which cooling water circulates is integrally surrounded, and a heating coil having a waterproof insulation coating on the outer periphery is wound around the outer periphery of the segment, and the heating coil is immersed in cooling water. Electromagnetic levitation melting furnace.