JP3805410B2 - Flotation melting furnace - Google Patents

Description

[0001]
[Industrial application fields]
In this invention, a conductive material to be melted is placed in an alternating magnetic field and is induction-heated by electromagnetic induction action, and a magnetic field having a predetermined distribution is generated to give the material to be melted a levitation force due to electromagnetic force. The present invention relates to a flotation melting furnace.
[0002]
[Prior art]
FIG. 4 shows a configuration diagram of a conventional example. In FIG. 4, 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 tapping hole of the crucible 1, and 6 is a tapping pipe section following the tapping hole 5 of the crucible 1. 8 is a molten metal, 11 is a segment constituting the crucible 1, and 12 is an insulator for insulating the segments 11. In FIG. 3, a crucible 1 is formed in a cylindrical shape having a bottom by laminating a segment 11 made of a highly conductive metal having a cooling water passage 4 and an insulator 12 that insulates the segments in the circumferential direction. The hot water discharge hole 5 for discharging the molten metal and the hot water discharge pipe portion 6 having a larger inner diameter than the subsequent hot water discharge hole 5 are configured. 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 the molten metal 8 and stabilizes the molten metal 8 floated by applying a horizontal electromagnetic force to the side surface of the molten metal 8. I am letting. The lower induction coil 3 gives a large levitation force to float the molten metal 8. The example shown in FIG. 4 in which the hole diameter is narrowed at the portion of the tap hole 5 and the hole diameter is widened at the tap pipe portion 6 and the levitation force is given 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.
[0003]
FIG. 5 shows an external view of a conventional segment. In FIG. 5, 4 is a cooling water passage, 9 is a cooling water connection pipe, 10 is a cooling water connection port, and 11 is a segment. In FIG. 5, since the induction coil must be mounted from the lower side due to the difference in diameter with the crucible, and since it is difficult to connect the cooling water pipe in the space below the segment, the cooling water connecting pipe is initially used. 9 and the cooling water connection port 10 are arranged on the extension line of the segment, the upper induction coil 2 and the lower induction coil 3 are mounted on the crucible body, and then the cooling water connection pipe 9 is bent outward. It is connected to the cooling water piping.
[0004]
FIG. 6 shows a case where the hole diameter is reduced at the portion of the hot water outlet hole 5, and the current is passed through the lower induction coil 3 of the floating melting furnace in which the diameter of the hot water outlet pipe portion 6 is widened to give the molten metal a levitation force. The crucible 1 induced current distribution, (b) molten metal 8 induced current distribution, and (c) the distribution of force acting on the molten metal 8 are shown. The symbols ◯ and □ in the figure indicate the current induced in the crucible 1 and the molten metal 8 by the lower induction coil 3, and the size of the symbols is proportional to the magnitude of the current. Shows that the current direction is reversed. Further, the force acting on the molten metal is indicated by the length of the arrow.
[0005]
Since the direction of the current of the molten metal 8 and the portion of the crucible 1 facing the molten metal 8 is opposite, an electromagnetic force repelling between the molten metal 8 and the crucible 1 works, and if this electromagnetic force is greater than the gravity of the molten metal 8, Even if there is a tapping hole 5, the molten metal 8 does not pour out. When the electromagnetic force in the vicinity of the tap hole 5 is small, the molten metal 8 cannot withstand its own weight, and the hot water is discharged from the tap hole 5.
In this example in which the hole diameter is reduced at the portion of 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 becomes large. The levitation force acting on the molten metal bottom is 4 to 4 in comparison with the levitation force when the inner diameter of the tapping pipe portion 6 is the same as the inner diameter of the tapping hole 5 and the same current is applied to the lower induction coil 3. Since it becomes five times, the levitation force to the molten metal 8 is sufficiently maintained even if the current flowing through the lower induction coil 3 is reduced.
[0006]
The heat generated by the crucible itself due to the induction current to 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 cooled via the cooling water passage 4 in the segment 11. Cooled by.
[0007]
[Problems to be solved by the invention]
In the above configuration, in order to increase the furnace capacity or shorten the melting time and improve productivity, either the upper induction coil and the lower induction coil, or the upper induction coil or the lower induction coil. When the electric power to be input is increased, the current concentrated in the vicinity of the tapping hole in the current induced in the crucible by the upper induction coil and the lower induction coil increases, and the vicinity of the tapping hole is overheated. There is a problem that the maximum value of electric power that can be supplied to the coil or any one of the upper induction coil and the lower induction coil is limited.
[0008]
In addition, if the power supplied to the lower induction coil is limited in order to suppress overheating in the vicinity of the tapping hole, there is a problem that sufficient levitation force cannot be given when the furnace capacity is increased.
In order to prevent overheating in the vicinity of the tap hole with the cooling method of the conventional example, 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, it is necessary to increase the circumferential length of the segment. However, this reduces the levitation force applied to the entire molten metal, and thus there is a problem that the molten metal is difficult to float.
[0009]
The method of increasing the water flow rate by increasing the flow rate of the cooling water is that the pressure loss of the cooling water is proportional to the square of the flow rate, and the flow rate of the cooling water in this seed furnace is 13 to 15 m / sec. There is a problem because the pressure loss at the furnace entrance and exit is already close to the limit.
In addition, since the upper and lower induction coils are removed from the crucible after the cooling water pipe at the lower part of the segment is heated and bent back, there is a problem that it takes time to replace the upper and lower induction coils.
[0010]
The object of the present invention is to improve the cooling of the tap hole and increase the power that can be supplied to the upper induction coil and the lower induction coil to increase the capacity and melt at high speed. It is an object of the present invention to provide a flotation melting furnace that can be easily replaced even when replacing.
[0011]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the floatation melting furnace of the present invention has a bottomed structure in which segments made of a highly conductive metal having a cooling water passage for passing cooling water in the longitudinal direction are laminated via an insulator in the circumferential direction. A crucible having a tapping hole that is formed in a cylindrical shape and discharges the molten metal to the bottom thereof, and a tapping pipe portion that has a larger inner diameter than the tapping hole, an upper induction coil provided on the outer diameter side of the crucible, and an outer diameter of the tapping pipe portion In the levitation melting furnace with the lower induction coil provided on the side, the cooling water flow path is formed by detouring to the inner diameter side at the tap hole, and the detour part of this cooling water flow path is drilled from the outside of the segment And a trapezoidal plug that is mounted from the outside of the segment and welded and sealed at the outer diameter portion of the segment so as to form a bypass portion of the cooling water passage in the groove.
[0012]
Moreover, in the above, the tip part of the trapezoidal plug is configured to be closer to the inner diameter side than the cooling water passage of the hot water discharge pipe part.
[0013]
In addition, in the above, the contact surface with the fluid of the trapezoidal plug is not less than a highly conductive metal material by any one of ceramic spraying, adhesion of wear resistant metal, and adhesion of wear resistant metal to the highly conductive metal. It shall have the wear resistance of
[0014]
In the above description, the bypass portion of the cooling water passage is formed so that the sectional area of the outlet side portion of the cooling water is larger than the sectional area of the inlet portion of the cooling water.
[0015]
In addition, in the above, a horizontal hole leading from the outer diameter part to the cooling water passage in the segment is provided in at least one of the upper part or the lower part of the segment, and an O-ring groove is provided on the outer peripheral side of the horizontal hole, A retrofit cooling pipe for connecting and supplying cooling water is provided, and a vertical induction coil is attached to the crucible, and then the retrofit cooling pipe is attached to the segment to form a cooling water circuit.
[0016]
[Action]
The part corresponding to the tapping hole of the segment is pointed toward the inner diameter side of the tapping hole, a groove is dug from the outer diameter side to the inner diameter side, and a trapezoidal plug with a sharp tip is attached to the groove, and the tip of the plug So that it is closer to the inner diameter side than the water passage of the tap pipe. In this way, the heat conduction distance between the cooling water passage and the inner portion of the tap hole is shortened by bypassing the cooling water passage to the inner diameter side of the tap hole. Further, the stagnation of water in the detoured waterway is eliminated by making the tip of the stopper closer to the inner diameter side than the water passage of the tap water pipe part.
[0017]
Furthermore, when the cross-sectional area on the entry side of the detour is made smaller than the cross-sectional area on the exit side, the exit side part becomes a turbulent flow region, and the heat transfer coefficient of the water passage in that part is improved.
In addition, since the part in the water passage of the plug is hardly induction-heated due to the skin effect, if the part is made harder than the hardness of the good conductive metal (copper), it can prevent wear due to sand contained in the cooling water. it can.
[0018]
The retrofitted cooling pipe is easy to attach and detach because the O-ring is sandwiched and fastened to the segment with screws.
[0019]
【Example】
FIG. 1 is a block diagram showing the main part of an embodiment of the present invention. In FIG. 1, members denoted by the same reference numerals as those in the conventional example have approximately the same functions, and thus description thereof is 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 tapping hole of the crucible 1, 6 is a tapping pipe section following the tapping hole 5 of the crucible 1, 7 is a plug forming a cooling water bypass, 8 is a molten metal, 11 is a segment constituting the crucible 1, and 12 is an insulator for insulating the segments 11 from each other. In FIG. 1, a crucible 1 is formed in a bottomed cylindrical shape by laminating a highly conductive metal segment 11 having a cooling water passage 4 in the longitudinal direction and an insulator 12 that insulates the segments in the circumferential direction. In addition, it is configured to have a hot water outlet hole 5 for discharging the molten metal at the bottom and a hot water outlet pipe part 6 having a larger inner diameter than the subsequent hot water outlet hole 5. 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 the molten metal 8 and stabilizes the molten metal 8 floated by applying a horizontal electromagnetic force to the side surface of the molten metal 8. I am letting. The lower induction coil 3 gives a large levitation force to float the molten metal 8.
[0020]
The cooling water passage 41 is composed of a groove 10 formed in the segment 11 from the outside of the segment 11 in the tap hole 5 portion, and a trapezoidal plug 7 welded so as to seal the groove 10 from the outer diameter side of the segment 11. It is formed around the inner diameter side of the tap hole 5. The distal end portion of the trapezoidal plug 7 is configured to be closer to the inner diameter side than the cooling water passage 41 of the hot water discharge pipe portion 6. According to the experiment, when the cooling water passage 41 is bypassed (the embodiment shown in FIG. 1) and when it is not bypassed (the previously proposed proposal shown in FIG. 3), the same electric power is supplied to The temperature increase in the vicinity of the bottom of the crucible where the hole 5 is connected to the bottom of the crucible was 70 ° C. when the cooling water passage 41 was bypassed, whereas it was 170 ° C. when the bypass was not bypassed. The fact that the cooling water passage 41 is bypassed means that the input power to the lower induction coil 3 that gives levitation force to the upper induction coil 2 until the amount of heat input to this portion is about 2.4 times that in the case where the heat input is not bypassed. It is possible to increase either the melting power or the total power of both. The trapezoidal plug 7 collides with cooling water flowing at high speed. Therefore, in order to increase the wear resistance of the contact surface with the cooling water, the plug 7 is any means of ceramic spraying, adhesion of the wear resistant metal, and adhesion of the wear resistant metal to the highly conductive metal. Is given.
[0021]
Since the hole diameter is reduced at the tap hole 5 and the hole diameter is widened at the tap pipe portion to give a large levitation force to the molten metal 8 and the explanation that the molten metal 8 floats is omitted as it has been described in the prior art.
FIG. 2 is a block diagram showing the main part of another embodiment of the present invention. 2 differs from FIG. 1 in that the plug 7 is shifted to the inlet side of the cooling water into the groove 10 to change the sectional area of the outlet side of the bypass of the cooling water passage 42 into the sectional area of the inlet side. It is a larger point. As a result, the cooling water becomes turbulent on the exit side of the detour and has an effect of improving the heat transfer in the hot water outlet 5 part. The arrows indicate the flow direction of the cooling water.
[0022]
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 for the segment 11, 10 is a cooling water connection port, 13 is a retrofit cooling pipe, and 14 is an O-ring groove. In FIG. 3, a horizontal hole leading from the upper and lower outer diameter portions of the segment 11 to the cooling water passage 4 in the segment 11 is opened, and an O-ring groove 14 and a segment 11 are formed on the outer peripheral side of the horizontal hole. A screw hole (not shown) for attaching a retrofitting cooling pipe is opened, an O-ring (not shown) is inserted into the O-ring groove 14, and sandwiched by the retrofitting cooling pipe 13. The cooling water connection port 10 is attached to 13, and the cooling water connection port 10 is piped to connect the cooling water circuit. The retrofitting cooling pipe 13 is attached after the upper and lower induction coils 2 and 3 are attached to the crucible. The retrofitted cooling pipe 13 may be used only in the lower part or the upper part of the segment 11, and the upper part or the lower part of the segment may be the same as the conventional example.
[0023]
【The invention's effect】
According to the present invention, since the cooling effect of the tap hole portion where the induced current is concentrated is increased, the power to be input to the upper induction coil is increased accordingly, the furnace capacity is increased, the melting time is shortened, and the production Has the effect of improving the performance. Further, since the retrofitted cooling pipe is fastened to the segment with an O-ring sandwiched between them, it is easy to attach and detach, and there is an effect that the exchange time can be shortened when exchanging the induction coil.
[Brief description of the drawings]
FIG. 1 is a block diagram of the main part of another embodiment of the present invention. FIG. 2 is a block diagram of the main part of another embodiment of the present invention. [Fig. 4] Configuration diagram of the conventional example [Fig. 5] Outline drawing of the segment of the conventional example of the conventional example [Fig. 6] (a), (b), (c) of the induced current generated in the crucible and the molten metal of the conventional example Diagram showing distribution and distribution of electromagnetic force on molten metal 【Explanation of symbols】
1 Crucible 2 Upper induction coil 3 Lower induction coil 4 Cooling water passage 5 Outlet hole 6 Outlet pipe portion 7 Plug 8 Molten metal 11 Segment 12 Insulator 13 Retrofitting cooling pipes 41 and 42 Cooling water passage

Claims (4)

A segment made of a highly conductive metal having a cooling water passage for passing cooling water in the longitudinal direction is laminated with an insulator in the circumferential direction to form a bottomed cylindrical shape, followed by a tapping hole for discharging molten metal to the bottom. In a levitation melting furnace comprising a crucible having a tapping pipe portion having an inner diameter larger than a tapping 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 tapping pipe portion The cooling water passageway is formed by detouring to the inner diameter side at the outlet hole, and the bypassing portion of the cooling water passageway is formed with a groove perforated from the outside of the segment, and a bypassing portion of the cooling water passageway in the groove portion. The trapezoidal plug is attached from the outside of the segment and welded and sealed at the outer diameter of the segment so as to form, and the tip of the trapezoidal plug is located on the inner diameter side of the cooling water passage of the outlet pipe portion. flotation solvent, characterized in that configured in The furnace. 2. The levitation melting furnace according to claim 1, wherein the contact surface of the trapezoidal plug with the fluid is any one of ceramic spraying, adhesion of wear-resistant metal, and adhesion of wear-resistant metal to a highly conductive metal. A floatation melting furnace characterized by having wear resistance higher than that of a highly conductive metal material. 3. The levitation melting furnace according to claim 1 or 2, wherein the detour portion of the cooling water passage is formed such that the cross-sectional area of the cooling water outlet side portion is larger than the cross-sectional area of the cooling water inlet side portion. A floating smelting furnace. 4. The floating melting furnace according to claim 1, wherein a horizontal hole is provided in at least one of an upper part and a lower part of the segment from the outer diameter part to the cooling water passage in the segment, and the outer peripheral side of the horizontal hole. In addition to providing an O-ring groove, a retrofitting cooling pipe for supplying and draining cooling water by connecting to a horizontal hole is provided, and an upper and lower induction coil is attached to the crucible, and then the retrofitting cooling pipe is attached to the segment to form a cooling water circuit. A levitation melting furnace characterized in that

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