JPH08327244A - Floating melting furnace - Google Patents

Abstract

PURPOSE: To improve the cooling of a tapping hole, to increase the power applied to an induction coil, to increase the capacity and to be able to melt at a high speed by forming a cooling water passage by passing to the bore side at the tapping hole. CONSTITUTION: The part corresponding to the tapping hole 5 of a segment 11 is converged toward the inside of the hole 5, a groove 1 is dug from the outer peripheral side to the bore side, a converged end trapezoidal plug 7 is put in the groove 10, and the end of the plug 7 s disposed at the bore side from the passage of a tapping tube 6. Thus, a cooling water passage 41 bypasses to the bore side of the hole 5 to shorten the thermal conduction distance between the passage 41 ad the bore part of the hole 5. The end of the plug 7 is disposed at the bore side from the passage of the tube 6 to eliminate the stagnation of water in the by pass. Thus, the cooling of the hole 5 is improved to increase the power applied to induction coils 2, 3, the capacity can be increased, and high speed melting can be conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention places a conductive material to be melted in an alternating magnetic field for induction heating by an electromagnetic induction action, and generates a magnetic field having a predetermined distribution to levitate the material to be melted by electromagnetic force. The present invention relates to a levitation melting furnace that melts in a levitation state by applying force.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional example. This Figure 4
In FIG. 1, 1 is a crucible, 2 is an upper induction coil, 3 is a lower induction coil, 4 is a cooling water passage, 5 is a tap hole of the crucible 1, 6
A tapping pipe portion following the tapping hole 5 of the crucible 1, 8 is molten metal, 11
Segments constituting the crucible 1, 12 is a segment 1
The insulator which insulates between 1 is shown. In FIG. 3, the crucible 1 is formed into a bottomed cylindrical shape by circumferentially stacking a segment 11 made of a good conductive metal having a cooling water passage 4 and an insulator 12 that insulates the segments from each other. It is configured to have a tap hole 5 for letting out molten metal and a tap pipe portion 6 having a larger inner diameter than the tap hole 5 that follows. Further, the upper induction coil 2 wound around the outer diameter side of the crucible 1 melts the metal in the crucible 1 to form a molten metal 8 and stabilizes the levitated molten metal 8 by applying a horizontal electromagnetic force to the side surface of the molten metal 8. I am letting you. The lower induction coil 3 gives a large levitation force to levitate the molten metal 8. The example of FIG. 4 in which the hole diameter is narrowed in the tap hole 5 and the hole diameter is widened in the tap pipe portion 6 to give the levitation force to the molten metal 8 by the lower induction coil 3 is shown in Japanese Patent Application No. 6-41660 by the present applicant. Already proposed in the issue.

FIG. 5 shows an outline view of a conventional segment. In FIG. 5, 4 is a cooling water passage, 9 is a cooling water connecting pipe, 10 is a cooling water connecting port, and 11 is a segment. In FIG. 5, the induction coil must be mounted from the lower side due to the difference in diameter with the crucible, and the connection of the cooling water pipe is difficult in the space below the segment. 9, and cooling water connection port 10
Is placed on the extension line of the segment, and the upper induction coil 2 and the lower induction coil 3 are attached to the crucible body,
The cooling water connection pipe 9 is bent outward so as to be connected to the cooling water pipe.

In FIG. 6, the hole diameter is narrowed at the tap hole 5,
In the tapping pipe section 6, when a current is passed through the lower induction coil 3 of the levitation melting furnace which widens the hole diameter and gives a levitation force to the molten metal, (a)
Crucible 1 induced current distribution, (b) molten metal 8 induced current distribution,
(C) The distribution of the force acting on the molten metal 8 is shown. The symbols ○ and □ in the figure indicate that the lower induction coil 3 indicates the crucible 1
Shows the current induced in the molten metal 8 and the magnitude of the symbol is proportional to the magnitude of the current, and ○ and □ indicate that the directions of the currents are opposite. The force acting on the molten metal is indicated by the length of the arrow.

Since the directions of the electric currents in the molten metal 8 and the portion of the crucible 1 facing the molten metal 8 are opposite, an electromagnetic repulsive force acts between the molten metal 8 and the crucible 1, and this electromagnetic force is caused by the gravity of the molten metal 8. If it is large, even if there is a tap hole 5, the molten metal 8 will not be tapped. If the electromagnetic force in the vicinity of the tap hole 5 is small, the molten metal 8 cannot bear the weight of the molten metal, and taps from the tap hole 5. In this example in which the hole diameter is narrowed in the tap hole 5, the induced current is concentrated on the inner surface of the tap hole 5, and the current induced in the melt 8 is also large at the bottom of the melt, The power to work on 8 also increases. The levitation force acting on the bottom of the molten metal is 4 to 4 as compared with the levitation force in the case where the inner diameter of the molten metal outlet pipe portion 6 is made the same as the inner diameter of the molten metal outlet hole 5 and the same amount of current is applied to the lower induction coil 3. Since it is five times, the levitation force to the molten metal 8 can be sufficiently maintained even if the current flowing through the lower induction coil 3 is reduced.

[0006] The heat generated by the crucible self-heating due to the current induced in the crucible by the upper induction coil 2 and the lower induction coil 3 and the heat generated by the radiation from the molten metal to the crucible are in segment 11.
It is cooled by cooling water through the cooling water passage 4 inside.

[0007]

In the above configuration,
To increase the furnace capacity or shorten the melting time to improve productivity, increase the power input to the upper induction coil and lower induction coil, or the upper induction coil or lower induction coil. Then, among the currents induced in the crucible by the upper induction coil and the lower induction coil, the current concentrated in the vicinity of the tap hole increases and overheats the vicinity of the tap hole. There is a problem that the maximum value of electric power that can be applied to either the induction coil or the lower induction coil is limited.

Further, if the electric power supplied to the lower induction coil is limited in order to suppress overheating in the vicinity of the tap hole, there is a problem that sufficient levitation force cannot be applied when increasing the furnace capacity. In order to prevent overheating near the tap hole with the conventional cooling method, it is necessary to increase the diameter of the cooling water passage, but the diameter of the cooling water passage without changing the relative distance between the upper induction coil and the molten metal. In order to increase, the length of the segment in the circumferential direction needs to be increased, but this reduces the levitation force applied to the entire molten metal, which causes a problem that the molten metal is difficult to float.

Further, in the method of increasing the flow rate by increasing the flow rate of the cooling water, the pressure loss of the cooling water is proportional to the square of the flow rate, and the flow rate of the cooling water of this type of reactor is 13 to 15 m /
There is a problem because the pressure loss at the furnace entrance and exit is already close to the limit. Further, since the cooling water pipe in the lower portion of the segment is heated and bent back and then the upper and lower induction coils are detached from the crucible, there is a problem that it takes time to replace the upper and lower induction coils.

An object of the present invention is to improve the cooling of the tap hole and increase the electric power that can be supplied to the upper induction coil and the lower induction coil to increase the capacity and melt at a high speed. It is to provide a levitation melting furnace in which the upper induction coil can be easily replaced even when it is replaced.

[0011]

According to a first aspect of the present invention, a segment made of a good conductive metal having a cooling water passage for passing cooling water in the longitudinal direction is laminated in the circumferential direction with an insulator interposed between the segments. A crucible having a tap hole that is formed in a cylindrical shape and through which molten metal exits at the bottom and a tap pipe portion that has a larger inner diameter than the tap hole that follows, an upper induction coil that is provided on the outer diameter side of the crucible, and the outside diameter of the tap pipe portion. In the levitation melting furnace provided with the lower induction coil provided on the side, the cooling water passage is a levitation melting furnace formed by detouring to the inner diameter side at the tap hole.

According to a second aspect of the present invention, in the levitation melting furnace according to the first aspect, the bypass portion of the cooling water passage is formed with a groove portion drilled from the outside of the segment and the bypass portion of the cooling water passage is formed in the groove portion. As described above, the levitation melting furnace is composed of a trapezoidal plug that is attached from the outside of the segment and is welded and sealed at the outer diameter portion of the segment. The invention of claim 3 is the levitation melting furnace according to claim 1 or 2, wherein the tip of the trapezoidal plug is arranged on the inner diameter side of the cooling water passage of the tap pipe part. And

According to a fourth aspect of the present invention, in the levitation melting furnace according to any of the first to third aspects, the contact surface of the trapezoidal plug with the fluid is made of a good conductive metal, ceramic sprayed, and wear-resistant. A levitation melting furnace with abrasion resistance higher than that of a good conductive metal material by either sticking a resistant metal or adhering a wear resistant metal. According to a fifth aspect of the present invention, in the levitation melting furnace according to any one of the first to fourth aspects, in the bypass portion of the cooling water passage, the cross-sectional area of the cooling water outlet side portion is the cooling water inlet side portion. The levitation melting furnace is formed to have a larger cross-sectional area.

According to a sixth aspect of the present invention, segments of a good conductive metal having a cooling water passage for passing cooling water in the longitudinal direction are laminated in the circumferential direction with an insulator interposed therebetween to form a bottomed cylindrical shape. A crucible having a tap hole for letting out molten metal at the bottom and a tap pipe part having a larger inner diameter than the tap holes that follow it, an upper induction coil provided on the outer diameter side of the crucible, and a lower part provided on the outer diameter side of the tap pipe part. In a levitation melting furnace equipped with an induction coil, a lateral hole communicating from the outer diameter part of the lower part of the segment to the cooling water passage in the segment is provided, and an O-ring groove is provided on the outer peripheral side of the lateral hole and connected to the lateral hole. Then, a retrofitting cooling pipe for supplying and draining the cooling water is provided, and the upper and lower induction coils are mounted on the crucible, and then the retrofitting cooling pipe is attached to the segment to form a cooling water circuit, thereby forming a levitation melting furnace.

According to a seventh aspect of the present invention, segments of a good conductive metal having a cooling water passage for passing cooling water in the longitudinal direction are laminated in the circumferential direction with an insulator interposed therebetween to form a bottomed cylindrical shape. A crucible having a tap hole for letting out molten metal at the bottom and a tap pipe part having a larger inner diameter than the tap holes that follow it, an upper induction coil provided on the outer diameter side of the crucible, and a lower part provided on the outer diameter side of the tap pipe part. In a levitation melting furnace equipped with an induction coil, a lateral hole communicating from the outer diameter portion of the upper part of the segment to the cooling water passage in the segment is provided, and an O-ring groove is provided on the outer peripheral side of the lateral hole and connected to the lateral hole. Then, a retrofitting cooling pipe for supplying and draining the cooling water is provided, and the upper and lower induction coils are mounted on the crucible, and then the retrofitting cooling pipe is attached to the segment to form a cooling water circuit, thereby forming a levitation melting furnace.

[0016]

[Function] The portion of the segment corresponding to the tap hole is sharpened toward the inner diameter side of the tap hole. A groove is dug from the outer diameter side to the inner diameter side, and a trapezoidal stopper with a sharp tip is inserted into the groove. Make sure that the tip end of is on the inner diameter side of the water passage of the tap pipe. By thus bypassing the cooling water passage to the inner diameter side of the tap hole, the heat conduction distance between the cooling water passage and the tap hole inner diameter portion is shortened. In addition, the tip of the plug is located on the inner diameter side of the water passage of the tap pipe, so that the stagnation of water in the bypassed water passage is eliminated.

Further, if the cross-sectional area of the bypass side on the entry side is made smaller than the cross-sectional area on the exit side, the exit side portion becomes a turbulent flow region,
The heat transfer coefficient of the water passage in that portion is improved. In addition, since the part of the stopper in the water passage is not heated by induction due to the skin effect, if the hardness of the part is made higher than that of the good conductive metal (copper), abrasion due to sand etc. contained in the cooling water can be prevented. it can.

Since the O-rings are sandwiched between the post-installed cooling pipes and the segments are fastened to the segments with screws, they can be easily attached and detached.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of the essential parts of an embodiment of the present invention. In FIG. 1, members given the same reference numerals as those in the conventional example have approximately the same functions, and therefore their explanations are omitted. In FIG. 1, 1 is a crucible, 2 is an upper induction coil, 3 is a lower induction coil, 41 is a cooling water passage, 5 is a hot water outlet hole of the crucible 1, 6 is a hot water outlet pipe portion following the hot water outlet hole 5 of the crucible 1, 7 is a stopper forming a bypass for cooling water, 8 is a molten metal, 11 is a segment constituting the crucible 1, 12 is a segment 11
An insulator that insulates between the two is shown. In FIG. 1, a crucible 1 includes a segment 11 made of a good conductive metal having a cooling water passage 4 in the longitudinal direction, and an insulator 12 for insulating between the segments.
And are formed in a cylindrical shape having a bottom by laminating in the circumferential direction, and have a tap hole 5 through which molten metal is discharged and a tap hole 6 having a larger inner diameter than the tap hole 5 that follows. Further, the upper induction coil 2 wound on the outer diameter side of the crucible 1 melts the metal in the crucible 1 into a molten metal 8 and
A horizontal electromagnetic force is applied to the side surface of the molten metal to stabilize the floated molten metal 8. The lower induction coil 3 gives a large levitation force to levitate the molten metal 8.

The cooling water passage 41 has a groove 10 formed in the segment 11 from the outside of the segment 11 in the tap hole 5 and a trapezoidal plug welded to seal the groove 10 from the outer diameter side of the segment 11. It is formed by detouring to the inner diameter side of the tap hole 5. The tip of the trapezoidal plug 7 is configured to be on the inner diameter side of the cooling water passage 41 of the hot water outlet pipe 6. According to the experiment, the cooling water passage 41
When the bypass is bypassed (the embodiment shown in FIG. 1) and when the bypass is not bypassed (the proposed proposal shown in FIG. 3), the same power is applied to the hot water outlet hole 5 of the crucible connected to the bottom of the crucible. The temperature rise near the bottom was 70 ° C. when the cooling water passage 41 was bypassed, whereas it was 170 ° C. when the cooling water passage 41 was not bypassed. Bypassing the cooling water passage 41 is about 2. when the amount of heat input to this portion is not bypassed.
It is possible to increase either the input power to the lower induction coil 3 that gives the levitation force, the melting power to the upper induction coil 2, or the total power of both until the quadruple. In addition, the trapezoidal plug 7 collides with the cooling water flowing at a high speed. Therefore, in order to increase the wear resistance of the contact surface with the cooling water, the plug 7 is formed by means of ceramic spraying, abrasion-resistant metal attachment, or abrasion-resistant metal adhesion to a good conductive metal. Has been applied.

By narrowing the hole diameter at the tap hole 5 and widening the hole diameter at the tap portion, a large levitation force is given to the molten metal 8.
Since the description of floating the molten metal 8 is as described in the conventional example, the description thereof is omitted. FIG. 2 is a block diagram of the essential parts of another embodiment of the present invention. The difference between FIG. 2 and FIG.
This is because the cross-sectional area on the outlet side of the bypass of the cooling water passage 42 is made larger than the cross-sectional area on the inlet side by shifting the inside of the cooling water to the inlet side. As a result, the cooling water becomes a turbulent flow on the outlet side of the detour and has the effect of improving the heat transfer in the tap hole 5. The arrows indicate the flow direction of the cooling water.

FIG. 3 is a block diagram showing the main part of another embodiment of the present invention. In FIG. 3, 2 is an upper induction coil, 3
Is a lower induction coil, 4 is a cooling water passage of segment 11,
Reference numeral 10 is a cooling water connection port, 13 is a retrofitting cooling pipe, and 14 is an O-ring groove. In FIG. 3, a lateral hole communicating from the upper and lower outer diameter portions of the segment 11 to the cooling water passage 4 in the segment 11 is formed, and the O-ring groove 14 and the segment 11 are formed on the outer peripheral side of the lateral hole. A screw hole (not shown) for attaching a post-installed cooling pipe is opened, an O-ring (not shown) is inserted into the O-ring groove 14, and the post-installed cooling pipe 13 sandwiches the post-installed cooling pipe. The cooling water connection port 10 is attached to 13, and the cooling water circuit is connected by piping to the cooling water connection port 10. The retrofitting cooling pipe 13 is attached after the upper and lower induction coils 2 and 3 are attached to the crucible. The post-cooling pipe 13 is used only in the lower part of the segment 11 or only in the upper part, and is used in the upper part of the segment, or
The lower part may be the same as the conventional example.

[0023]

According to the present invention, since the cooling effect of the tap hole portion where the induction current is concentrated is enhanced, the electric power supplied to the upper induction coil is increased correspondingly to increase the capacity of the furnace and the melting time. Has the effect of shortening the productivity and improving productivity. Further, since the O-ring is sandwiched between the post-installed cooling pipes and the segments are fastened to the segments with screws, the post-installed cooling pipes can be easily attached and detached, and the exchange time can be shortened when the induction coil is exchanged.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example

FIG. 5 is an outline view of a conventional segment of the conventional example.

6 (a), (b) and (c) are views showing distribution of an induced current generated in a crucible and a molten metal and distribution of an electromagnetic force to the molten metal in a conventional example.

[Explanation of symbols]

 1 Crucible 2 Upper Induction Coil 3 Lower Induction Coil 4 Cooling Water Channel 5 Outlet Hole 6 Outlet Pipe Section 7 Plug 8 Molten Metal 11 Segment 12 Insulator 13 Retrofit Cooling Pipe 41, 42 Cooling Water Channel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kengo Kainuma 1-1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Masaki Sakuma 1-Tanabe Nitta, Kawasaki-ku, Kanagawa No. 1 inside Fuji Electric Co., Ltd.

Claims (7)

[Claims] 1. A segment made of a good conductive metal having a cooling water passage for passing cooling water in the longitudinal direction is laminated in the circumferential direction via an insulator to form a bottomed cylindrical shape, and the molten metal is discharged to the bottom part. A crucible having a tap hole and a tap pipe portion having a larger inner diameter than the tap hole, an upper induction coil provided on the outer diameter side of the crucible, and a lower induction coil provided on the outer diameter side of the tap pipe portion. In the levitation melting furnace, the cooling water passage is formed so as to bypass the inner diameter side at the tap hole. 2. The levitation melting furnace according to claim 1, wherein the bypass portion of the cooling water passage is a groove portion drilled from the outside of the segment, and the bypass portion of the segment is formed in the groove portion to form the bypass portion of the cooling water passage. A levitation melting furnace, comprising: a trapezoidal plug that is mounted from the outside and is welded and sealed at the outer diameter portion of the segment. 3. The levitation melting furnace according to claim 1 or 2, wherein the trapezoidal stopper is configured such that a tip portion thereof is located on the inner diameter side of the cooling water passage of the tap pipe portion. Floating melting furnace. 4. The levitation melting furnace according to claim 1, wherein the contact surface of the trapezoidal stopper with the fluid is
A levitation melting furnace characterized by having a wear resistance higher than that of a good conductive metal material by one of ceramic spraying, wear resistant metal attachment, and wear resistant metal adhesion to a good conductive metal. 5. The levitation melting furnace according to claim 1 or 4, wherein the bypass portion of the cooling water passage has a cross-sectional area of a cooling water outlet side portion which is a disconnection of the cooling water inlet side portion. A levitation melting furnace characterized by being formed to be larger than the area. 6. A segment made of a good conductive metal having a cooling water passage for passing cooling water in a longitudinal direction is laminated in the circumferential direction via an insulator to form a bottomed cylindrical shape, and the molten metal is discharged to the bottom portion. A crucible having a tap hole and a tap pipe portion having a larger inner diameter than the tap hole, an upper induction coil provided on the outer diameter side of the crucible, and a lower induction coil provided on the outer diameter side of the tap pipe portion. In the levitation melting furnace, a horizontal hole communicating from the outer diameter part of the lower part of the segment to the cooling water passage in the segment is provided, and an O-ring groove is provided on the outer peripheral side of the horizontal hole, and the cooling water is connected to the horizontal hole for cooling water. A levitation melting furnace characterized in that a retrofitting cooling pipe for water supply and drainage is provided, upper and lower induction coils are attached to a crucible, and then the retrofitting cooling pipe is attached to a segment to form a cooling water circuit. 7. A segment made of a good conductive metal having a cooling water passage for passing cooling water in the longitudinal direction is laminated in the circumferential direction via an insulator to form a bottomed cylindrical shape, and the molten metal is discharged to the bottom part. A crucible having a tap hole and a tap pipe portion having a larger inner diameter than the tap hole, an upper induction coil provided on the outer diameter side of the crucible, and a lower induction coil provided on the outer diameter side of the tap pipe portion. In the levitation melting furnace, a horizontal hole communicating from the outer diameter portion of the upper part of the segment to the cooling water passage in the segment is provided, and an O-ring groove is provided on the outer peripheral side of the horizontal hole, and the cooling water is connected to the horizontal hole for cooling water. A levitation melting furnace characterized in that a retrofitting cooling pipe for water supply and drainage is provided, upper and lower induction coils are attached to a crucible, and then the retrofitting cooling pipe is attached to a segment to form a cooling water circuit.