JPH0658674A - Remelting device and operating method thereof - Google Patents

Abstract

PURPOSE: To provide a remelting apparatus capable of controlling an outflow speed of a molten metal jet stream flowing out from a hot water outlet up to complete interruption with reduced inertia possibly perfectly. CONSTITUTION: A pressure tank 2 is disposed above a melting bath 7 on a crucible 2, and a controller 12 is provided for controlling pressure in the pressure tank 9 other than a current controller for a coil located at a hot water outlet 5 in order to control the amount of outflow of molten metal from the hot water outlet 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a melting bath heated by an electric heating device, and has a tap hole surrounded by an electric coil at the bottom, and remelted through the tap hole. Remelting device and remelting device for remelting an electrode in a crucible in which the coil is configured to controllably generate a magnetic field that slows down the outflow velocity of the jet It is related to the operating method for.

[0002]

2. Description of the Prior Art Electrodes manufactured in a vacuum induction furnace and cast in the form of a cylindrical ingot have the harmful components removed by remelting. For this, the electroslag melting (ESU) method is adopted, in which the electrode is slightly immersed in the slag bath in the crucible, the slag bath having a temperature higher than the temperature corresponding to the melting temperature of the electrode. Have The molten metal droplets to be blown move through the slag, in which case in particular the ceramic constituents are removed. At the end of the remelting operation when the electrodes are completely blown, the molten metal bath collected in the crucible is solidified to obtain new metal ingots. If the molten metal is to be made to flow out of the crucible as a molten metal jet while the metal is melted by the electrodes, it is necessary to accurately control the amount of the molten metal flowing out. For this purpose, it is possible to guide the tap hole through the coil, and when the tap hole is made of a ceramic material, it is possible to generate a sufficient magnetic holding force by the coil. However, when it is important to cast a metal that does not contain ceramics as much as possible, it is necessary to abandon the ceramic outlet, and to configure the outlet with metal, especially copper, which causes a magnetic field. Shielded. Nevertheless, in order to allow the magnetic field to act on the outflowing molten metal jet, the taps can be formed by fences with a slight gap between them. However, it has been found that the magnetic force in this case is often insufficient to control the outflow rate of the molten metal jet and to completely stop the molten metal jet. Further, the control operation by such magnetic force is slow and is not desirable.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve the remelting apparatus of the type described at the beginning so that the outflow velocity of a molten metal jet flowing out of a taphole until it is completely stopped is It is an object of the present invention to provide a remelting device which can be controlled as perfectly as possible and with less inertia, and a method of operating the remelting device which enables optimum control of the jet flow of molten metal.

[0004]

The constituent means of the remelting apparatus of the present invention for solving the above-mentioned problems is such that a pressure tank is arranged above the melting bath on the crucible, and the molten metal from the tap hole is melted. In order to control the outflow amount of the water, a controller for adjusting the pressure in the pressure tank is provided in addition to the current controller for the coil at the tap hole.

The second means, namely, the means for solving the problem that the molten metal jet in the remelting apparatus can be optimally controlled, is constituted by an operating method, in which the flow rate of the molten metal jet from the taphole of the crucible is determined. In order to control the above, in addition to controlling the current of the coil at the tap hole, the pressure in the upper part of the molten bath in the pressure tank is controlled.

[0006]

Based on the structure of the remelting apparatus of the present invention as described above, a positive pressure or a negative pressure is generated in the pressure tank depending on whether the outflow speed is increased or decreased. It becomes possible to tighten.

Moreover, by changing the pressure in the pressure tank, it is possible to change the outflow rate of the molten metal jet very rapidly and even until the outflow is stopped. This allows optimal control of the outflow of molten metal and thus the level of the molten bath in the crucible, in which case it is not necessary to generate a high magnetic force by the coil surrounding the tap. Absent.

The relatively large level fluctuations of the molten bath in the crucible, which would result in different outflow rates without outflow control and therefore would have to be compensated by the outflow control, caused the molten bath level in the crucible to change. It is prevented in a simple manner by a level detection device for detecting and a current controller for controlling the heating power of the molten bath in relation to the level of the molten bath.

According to another embodiment of the present invention, the tap is movable from a position where the tap is completely shut off to a position where the tap is released and ceramic-free induction heating. With a mechanical closing mechanism, it is possible at the beginning of the process to close the magnetic holding force and the holding force due to the negative pressure in the pressure tank. This closure prevents air from passing upwards through the tap through the molten bath during the start phase of the process and thus into the pressure tank under negative pressure.

The heat loss of the remelting device can be reduced by constructing the peripheral wall of the crucible from ceramic. As a result, it becomes possible to increase the fusing output of the electrode without fear of the ceramic component reaching the molten metal. This is because in this area there is always a scull that prevents the ceramic from entering the molten metal.
Is caused.

The risk of entraining the slag in the outflow of molten metal can be prevented in a very simple manner by shifting the axis of the tap hole laterally with respect to the axis of the electrode.

In order to separate the slag even better, a slag barrier is provided in the crucible.

Further, based on the operating method of the present invention comprising the above-mentioned means, it is possible to change the outflow of the molten metal quickly and by changing the pressure in the pressure tank until the operation is stopped. Therefore, since the coil system surrounding the tap does not need to generate such a strong magnetic force that acts on the molten metal jet, the problem caused by the ceramic-free tap must be stopped solely by the magnetic force. Less than in such cases.

In order to control the heating power of the melting bath, it is advantageous to detect and consider the level of the melting bath in the crucible. This precisely controls the fusing rate of the electrodes, resulting in a constant melt bath level and thus a constant melt bath pressure at the tap.

First, the heating power of the melting bath is reduced or cut off,
And stopping the outflow of molten metal jet by increasing the electromagnetic force generated by the coil and / or increasing the negative pressure in the pressure tank at the tap, then mechanically blocking the tap by a closing mechanism The process ends in a more advantageous way.

At the start of the process, first, the molten metal droplets formed in the tap hole are melted in the area of the electromagnetic guide system, and the power is supplied to the heating device of the molten bath for the first time, so that the slag flows out at the start of the process. Can be avoided. With the actuation method of the present invention, the taphole is filled with molten metal before the slag melts, so that the slag no longer floats above the molten metal and flows out together.

In the case of cold starting with a scull present in the crucible, in order to prevent an electrical short circuit between the circumferential wall of the electrode and the crucible wall via the edge of the scull, the operating method according to the invention is used. According to an advantageous embodiment, it is possible to use an electrode with a reduced lower end when starting the process in the presence of a scull. This results in a relatively large radial spacing between the electrode and the scull.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention allows numerous embodiments,
In order to further clarify the basic principle of the present invention, two particularly preferred embodiments of the remelting device according to the present invention will be described in detail below with reference to the drawings.

The upper area of the cradle 1 shown in FIG. 1 supports a copper crucible 2. The crucible 2 has a bottom 3 provided with a jet guide system 4, which has a tap hole 5. Inside the crucible 2, as can be seen from the drawing, the lower end of the electrode 6 to be remelted is immersed in the melting bath 7. The remelting energy required for the remelting method is supplied to the remelting device via a power supply section 8, which is composed of two coaxial conductive tubes. A pressure tank 9, which is important for the invention, is mounted on the crucible 2 and surrounds the electrode 6 in a pressure-tight manner. Exhaust gas is sucked from the pressure tank 9 by the fan 10 through the outlet connecting pipe portion 11. The controller 12 makes it possible to change the pressure in the pressure tank 9 and in particular to generate a negative pressure in the pressure tank. Since this negative pressure acts on the surface of the melting bath 7, the negative pressure delays or prevents the outflow of the molten metal at the tapping port 5. On the contrary, it is possible to accelerate the outflow of the molten metal by the positive pressure (overpressure) in the pressure tank.

A level detector 13 is arranged in the crucible 2 and detects the level of the melting bath 7 and then controls the electrical energy for the remelting process by means of a current controller 14. it can.

As can be seen from the enlarged view of the jet guide system 4 shown in FIG. 1 in a sectional view in the left part and a side view in the right part of FIG. 2, the tap hole 5 is formed in a hopper shape. And consists of individual fences 15, 16. The tap hole 5 is surrounded by a coil 17, and the coil damps the molten metal jet flowing out to some extent by a magnetic force when power is supplied. A closing mechanism 18 capable of mechanical induction heating is arranged at the lower end of the tapping port 5, and the closing mechanism mechanically shuts off the tapping port 5, but when the remelting device is in operation, The mouth 5 can be moved to a position where it is released.

In the embodiment shown in FIG. 3, unlike the above-mentioned embodiment, the axis of the electrode 6 and the axis of the tap hole 5 are laterally offset from each other. As a result, it is possible to arrange the slag barriers 19 and 20 in the melting bath 7,
The slag barrier additionally prevents slag from reaching the taphole 5.

Finally, as a reminder, the individually claimed components of the remelter and the means of operating the remelter are advantageous independently of the other components. .
For example, in a remelter, it is also possible to control the electroslag melting (ESU) energy through the level of the melt bath without working in a pressure tank to suppress the molten metal jet.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a remelting device of the present invention.

FIG. 2 is an enlarged cross-sectional view of a left portion and an enlarged side view of a right portion of the jet guide system of the remelting device shown in FIG.

FIG. 3 is a principle view of a lower portion of a remelting device of an embodiment different from that of FIG.

[Explanation of symbols]

1 mount, 2 crucible, 3 bottom part, 4 jet guide system, 5 hot water outlet, 6 electrodes, 7 molten bath, 8 power supply part, 9 pressure tank, 10
Fan, 11 outlet connection pipe part, 12 controller, level detection device, current controller, 15, 16
Fence, 17 coils, 18 closing mechanism, 19, 2
0 Slug barrier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norbert Ludwig Niedernberg Northlink 5 Ar (72) Inventor Michael Protzmann Federal Republic of Germany Wechtersbach 2 Rankgasse 28 (72) Inventor Haldi Weissweiler Germany Federal Republic of Hanau 7 Hermann-Ehrers-Strasse 64 Base

Claims (11)

[Claims] 1. A melting bath (7) heated by an electric heating device, and a bottom (3) having a tap (5) surrounded by an electric coil, via which tap. For remelting the electrode (6) in the crucible (2) in which the coil is constructed so as to controllably generate a magnetic field that decelerates the outflow velocity of the jet stream In the remelting device, the pressure tank (2) is arranged above the melting bath (7) on the crucible (2),
In addition to the current controller for the coil of the tap (5) in order to control the amount of molten metal flowing out from the tap (5), a controller (1) for adjusting the pressure in the pressure tank (9).
2) is provided, The remelting apparatus characterized by the above-mentioned. 2. A level detection device (13) for detecting the level of the melting bath (7) in the crucible (2) and for controlling the heating power of the melting bath (7) in relation to said level. 2. The remelting device according to claim 1, further comprising a current controller (14). 3. Mechanical induction free of ceramics, wherein the tap (5) is movable from a position where the tap (5) is completely shut off to a position where the tap is released. Remelting device according to claim 1 or 2, comprising a closing mechanism (18) that is heated. 4. The remelting device according to claim 1, wherein the peripheral wall surface of the crucible (2) is made of ceramic. 5. Remelting device according to any one of claims 1 to 4, wherein the axis of the tap hole (5) is laterally offset with respect to the axis of the electrode (2). 6. A slag barrier (19, 2) is provided in the crucible (2).
0) is provided, The remelting device according to any one of claims 1 to 5. 7. In order to control the outflow velocity of the molten metal jet from the tap of the crucible, in addition to controlling the current of the coil of the tap, controlling the pressure above the molten bath in the pressure tank An operating method for a remelting apparatus according to claim 1, characterized in that 8. A method according to claim 7, wherein the level of the molten bath in the crucible is detected and taken into account for controlling the heating power of the heating device for the molten bath. 9. At the end of the process, first, the electric power for heating the molten bath is reduced or cut off, and the electromagnetic force generated at the tapping port by the coil and / or the negative pressure in the pressure tank is increased, so that the molten metal jet flows out. And then mechanically shutting off the tap by a closing mechanism.
8 is the operating method described. 10. The heating device for the molten bath is supplied with electric power only after the molten metal droplets formed in the tap at the start of the process are melted in the region of the electromagnetic guide system. The operating method described. 11. The actuation method according to claim 7, wherein an electrode having a reduced diameter lower end is used when starting the process in the presence of a scull.