KR20090060737A - Method and device for reducing edge skull formation in twin roll strip casting using electromagnetic field - Google Patents

Abstract

An edge skull production reduction method and apparatus of a twin roll strip caster using an electromagnetic field are provided to suppress the production of edge skull due to the congestion and coagulation of molten steel and reduce the mixing of edge skull into a slab. An edge skull production reduction apparatus of a twin roll strip caster using an electromagnetic field comprises an electromagnet(8) which is installed on the top of molten steel between a nozzle(5) and an edge dam(3) to create an electromagnetic field in the surface of the molten steel, and a power supply unit which supplies AC power to the electromagnet through a power supply line(15) and adjusts the intensity of the electromagnetic field. The electromagnet includes electromagnetic cores(9) arranged at regular intervals in the width direction of the edge dam at the certain height from the molten steel surface, and copper tubes(10) arranged inside the respective electromagnetic cores and provided with power from the power supply unit.

Description

Method and device for reducing edge skull generation in twin roll strip casting machine using electromagnetic field

The present invention relates to a method and apparatus for reducing edge scull generation of a twin roll sheet metal casting machine using an electromagnetic field, in particular, solidification of molten steel due to stagnation or heat loss of molten steel in the hot water surface of an edge dam refractory in a twin roll sheet metal casting process. The present invention relates to a method and an apparatus capable of reducing edge skulls generated by mixing into an edge portion of a slab by using an electromagnetic field.

In general, twin roll type strip casting processes molten steel through a molten steel supply nozzle between a pair of casting rolls being cooled to maintain a constant height of the molten steel pool and rotate in a direction facing the casting roll. It is a method of continuously producing a thin plate directly from molten steel by forming a cast slab by coalescing a solidified shell formed on the surface of the casting roll in the proximity between the casting rolls.

FIG. 1 is a configuration diagram schematically showing an edge dam of a conventional twin roll sheet caster, and FIG. 2 is a cross-sectional view for explaining generation of edge sculls in FIG. 1.

As shown in FIG. 1, a pair of edge dam refractories 3 are installed at both sides of the pair of casting rolls 1 of the twin roll type sheet casting machine to block molten steel outflow, and the edge dams preheated before casting. During the casting, the refractory 3 is brought into contact with the hot molten steel supplied between the casting rolls 1 and the casting roll 1 which is water-cooled at the same time on the movable surface thereof. Therefore, the refractory of the edge dam refractory 3 surface is cooled by the contact with the casting roll 1, and the heat loss of molten steel generate | occur | produces around the contact part of the casting roll 1, and it becomes a condition in which molten steel can be easily solidified.

As shown in FIG. 2, the edge scull 7 in which molten steel solidifies is produced on the movable surface of the edge dam refractory 3, and is grown on the surface of the edge dam refractory 3. These edge sculls 7 are incorporated into the edge part by repeating growth and dropping during casting, thus degrading the caster edge part quality and affecting the casting stability, and when the skull is hardened, it is pressed between the casting rolls 1. This results in damage of the casting roll 1, which is a serious problem.

In order to solve the problem of the edge scull 7, conventionally, in the construction of the edge dam refractory 3, by using a material having a low thermal conductivity below a certain level, the heat loss of the molten steel is reduced and the solidification is reduced or the Japanese patent In Japanese Patent Laid-Open No. 2001-150106, a method of preventing the solidification of molten steel by installing a thin metal tube at the lower end of the edge dam refractory 3 and blowing an inert gas into the molten steel at the lower end of the edge dam is provided through the tube.

However, in the conventional skull reduction method, the former method has a small effect of preventing the generation and growth of the skull from the edge dam material having low thermal conductivity when the flow of molten steel is stagnant. Although it is effective to reduce the scull at the bottom of the scull, it does not solve the problem of the scull becoming larger in the case of stagnation of molten steel flow in the edge dam water surface part, especially in the corner of the water surface where the casting roll and the edge dam contact. There is a problem that does not reduce the growth of the edge skull, which is greatly grown and becomes a more serious problem.

The present invention has been proposed to solve the above problems, the edge scull of the twin roll type sheet casting machine using an electromagnetic field capable of continuously promoting the flow of molten steel at the contact boundary between the molten surface and the edge dam refractory using a non-contact electromagnet It is an object to provide a production reduction method and an apparatus thereof.

The present invention for achieving the above object is characterized by flowing the molten steel of the boundary portion by forming a moving magnetic field by the electromagnetic field in the boundary portion of the edge dam refractory and the molten steel of the twin-roll thin sheet casting machine contact.

Preferably, the electromagnetic field may be formed from the boundary between the edge dam and the molten steel to the vicinity of the nozzle of the twin roll type sheet casting machine.

An apparatus for preventing edge scull of a twin-roll thin sheet casting machine using an electromagnetic field according to another aspect of the present invention includes: an electromagnet installed on the molten steel between an edge dam and a nozzle to form an electromagnetic field on the molten steel surface; And a power supply for supplying AC power through the power supply line to the electromagnet and adjusting the strength of the formed electromagnetic field.

Preferably, the electromagnet may be installed so that an electromagnetic field is generated on the hot water surface of the molten steel between the edge dam and the nozzle.

Preferably, the electromagnet comprises: a plurality of electromagnet cores arranged at regular intervals in the width direction of the edge dam and disposed at a predetermined height from the bath surface; A plurality of copper tubes are installed in each of the electromagnet cores, and a plurality of copper tubes supplied with current from the power supply unit.

Preferably, each of the electromagnet cores may be applied an AC power source having a phase difference of 2π / n (n: is the number of electromagnet cores).

Preferably, the power supply unit includes: a moving field generating unit for forming a phase difference of an AC power source applied to the plurality of electromagnet cores; A current variable for varying the magnitude of the current applied to the electromagnet; And a power supply controller for controlling the moving magnetic field generating unit so that each of the electromagnet cores has a constant phase difference, and controlling the flow rate of the molten steel by controlling the current variable to control the strength of the electromagnetic field formed on the water surface. have.

The method and apparatus for reducing edge scull generation of a twin-roll thin sheet casting machine using electromagnetic fields according to the present invention generate an electromagnetic field in the edge scull forming portion of the surface of the molten steel where the edge dam refractory is in contact with the molten steel to generate a molten steel flow, thereby causing stagnation and solidification of the molten steel. It is possible to reduce the generation of edge scull by the edge and reduce the mixing of edge scull in the cast steel, thereby improving the quality and casting stability of the cast steel edge, and protecting the facilities such as casting rolls.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is an edge dam refractories used for the purpose of blocking the molten steel outflow of the casting roll short side portion in the twin-roll thin sheet casting process, the solidification of the molten steel is generated due to stagnation or heat loss of the molten steel on the surface to form the edge scull As a method of preventing and mixing, it is possible to cast high quality sheet steel by stably and easily reducing edge sculls generated at the surface and corners of the edge dam by generating an electromagnetic field using a non-contact electromagnet core. And a device.

More specifically, the present invention provides a moving magnetic field generating means such as an electromagnet on the edge dam refractory and the hot water contact portion in order to continuously promote the flow of the molten steel at the interface where the edge dam refractory and the molten steel contact the molten steel of the twin roll type sheet casting machine. To form an electromagnetic field.

Here, it is preferable to form the electromagnetic field from the boundary between the edge dam and the molten steel to the vicinity of the nozzle of the twin roll type sheet casting machine.

In this way, the molten steel is flowed using the electromagnetic field to eliminate the stagnation of the molten steel to prevent edge sculls generated at the beginning of casting, and in particular, by maintaining a constant molten steel flow caused by the electromagnetic field during casting, it is possible to reduce the scull growth due to the stagnation of the molten steel in the hot water surface part. Can be.

FIG. 3 is a schematic configuration diagram of an edge scull prevention apparatus of a twin roll thin plate casting machine using an electromagnetic field according to an exemplary embodiment of the present invention, and FIG. 4 is a configuration diagram for explaining a main part of FIG. 3.

The edge scull preventing device of the twin-roll thin plate casting machine using an electromagnetic field according to an embodiment of the present invention is installed on the molten steel between the edge dam (3) and the nozzle (5) to form an electromagnetic field on the hot water surface of the molten steel and And an electric power supply unit for supplying AC power through the power supply line 15 to the electromagnet 8 and adjusting the strength of the formed electromagnetic field.

The power supply unit includes a moving magnetic field generating unit 11 for forming a phase difference of AC power applied to the plurality of electromagnet cores 9, a current transformer 12 for varying the magnitude of the current applied to the electromagnet 8, It is composed of a power supply controller 13 for controlling the moving magnetic field generating unit 11 and the current transformer 12 to control the strength of the electromagnetic field formed on the water surface between the edge dam 3 and the nozzle (5).

As described later, the power supply controller 13 controls the moving field generator 11 so that each of the electromagnet cores 9 has a constant phase difference, and controls the strength of the electromagnetic field formed on the surface of the current transformer 12. Control the flow rate of molten steel.

The electromagnet 8 is preferably installed at a position where the generated electromagnetic field affects the entire upper surface of the molten steel between the edge dam 3 and the nozzle 5, and at least from a portion where the edge dam 3 and the molten steel contact each other. The nozzle 5 is installed so that an electromagnetic field can be formed in a proper region.

These electromagnets 8 are arranged at regular intervals in the width direction of the edge dam 3, and are arranged in a plurality of electromagnet cores 9A, 9B, 9C, and 9D at a predetermined height from the water surface, and inside each of the electromagnet cores 9. It is installed in a plurality, and is composed of a plurality of copper tubes (10) receiving current from the moving field generating unit (11).

In each of the electromagnet cores 9, AC power having a phase difference of 2π / n (n: is the number of electromagnet cores) is applied from the moving field generating unit 11.

That is, when the alternating currents are simultaneously supplied and the phases between the electromagnet cores 9 are the same, the flow of molten steel by the electromagnet cores 9 cancels each other, so that the molten steel flow to the nozzle 5 side is impossible, so that the nozzle 5 In order to promote the flow of molten steel in the direction, a phase difference occurs in the alternating current supplied to each of the electromagnet cores 9.

More specifically, the phase difference of the AC power supplied from the moving field generator 11 to the electromagnet core 9 is configured to be generated by 2π / n (n: number of electromagnet cores) for t time, for example, As shown in FIG. 4, when the electromagnet cores 9A, 9B, 9C, and 9D are four, t, t + π / 2, t + π, and t + 2π are respectively applied to the electromagnet cores 9A, 9B, 9C, and 9D. AC power having a phase difference of / 3 is applied from the moving field generating unit 11.

At this time, by sequentially applying to the electromagnet cores 9A, 9B, 9C, and 9D disposed on the nozzle 5 side from the edge dam 3 side, continuous molten steel flow occurs in the nozzle 5 direction.

The electromagnet 8 can control the strength of the molten steel flow in the front portion of the edge dam 3 by varying the amount of current supplied from the current transformer 12 under the control of the power supply controller 13, It also has the effect of suppressing scull formation by Joule heat of induced electromotive force generated on the surface of molten steel.

The copper tube 10 receives a current from the moving field generator 11 through the connection mechanism 17 and the power supply line 15.

Since the joule heat may be generated by the electric current supply, the power supply line 15 is preferably prevented from being damaged by the joule heat generated by supplying the cooling water from the cooling water supply through the cooling water supply pipe.

Hereinafter, the principle of forming an electromagnetic field by the electromagnet 8 will be described with reference to FIGS. 5 and 6.

5 is a configuration diagram illustrating the molten steel flow of FIG. 3, and FIG. 6 is a view for explaining the principle of operation of the edge sculpting prevention device of the twin roll type sheet casting machine using the electromagnetic field according to the embodiment of the present invention.

As shown in FIG. 6, when an alternating current is supplied to the copper tube 10 installed at the upper predetermined height of the molten steel, the direction of arrangement of the copper tube 10, that is, the edge dam 3, is in accordance with Enfer's right screw law. The magnetic field is formed at right angles to the flow direction of the current, which is parallel to), and in the case of supplying alternating current, the direction of the magnetic field is changed by the frequency period of alternating current and induced electromotive force is generated in a direction that resists changes in the magnetic field.

As described above, when an alternating current passes through the copper tube 10, induced electromotive force in a direction parallel to the copper tube 10 is generated in the molten steel directly below the copper tube 10. For example, when the alternating current passing direction of the copper tube 10 faces downward in the drawing, induction electromotive force in the same direction as that of the copper tube 10 is generated in the molten steel, which is generated by the induced current and the copper tube 10. The molten steel flows under the action of the applied magnetic field.

That is, since the molten steel acts downward on the copper tube 10 in the direct direction of the copper tube 10 arrangement direction, and in all directions, the force in the normal direction of the concentric circles acts on the molten steel. The molten steel of the hot water surface flows toward the edge dam 3 and the nozzle 5 as shown in FIG.

This flow of molten steel can generate a continuous flow of molten steel because the force in the same direction is generated even if the direction of the alternating current is reversed.

By maintaining the flow of molten steel by such a structure, scull growth by the molten steel stagnation of a hot water surface can be reduced.

1 is a schematic view showing an edge dam of a conventional twin roll sheet casting machine.

FIG. 2 is a cross-sectional view illustrating the generation of edge sculls in FIG. 1. FIG.

3 is a schematic configuration diagram of an edge scull preventing device of a twin-roll thin-plate casting machine using an electromagnetic field according to an embodiment of the present invention.

4 is a configuration diagram for explaining a main part of FIG. 3.

5 is a configuration diagram for explaining the flow of molten steel of FIG.

Figure 6 is a view for explaining the principle of operation of the edge curl prevention device of a twin-roll thin plate casting machine using an electromagnetic field according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: casting roll 2: edge dam refractory

3: edge dam 4: thin plate

5: Nozzle 7: Edge scull

8: electromagnet 9: electromagnet core

10 copper tube 11 moving field generating unit

12 current converter 13 power supply controller

15: power supply line

Claims (7)

An edge field generation reduction method of a twin roll sheet metal casting machine using an electromagnetic field is formed by forming a moving magnetic field due to an electromagnetic field at a boundary portion where the edge dam refractory of the twin roll type sheet casting machine and the molten steel are in contact with each other. The method of claim 1, The electromagnetic field is formed from the boundary between the edge dam and the molten steel to the vicinity of the nozzle of the thin roll type sheet casting machine, characterized in that the edge scull generation reduction method of the double roll type sheet casting machine using the electromagnetic field. An electromagnet disposed on the molten steel between the edge dam and the nozzle to form an electromagnetic field on the molten steel; Supplying an AC power through the power supply line to the electromagnet and the power supply for adjusting the strength of the electromagnetic field formed; edge curl prevention device of a twin roll type sheet casting machine using an electromagnetic field comprising a. The method of claim 3, wherein The electromagnet is an edge curl prevention device of the pre-roll roll thin sheet using the electromagnetic field, characterized in that the electromagnetic field is installed on the hot water surface of the molten steel between the edge dam and the nozzle. The method of claim 3, wherein The electromagnets include: a plurality of electromagnet cores arranged at regular intervals in the width direction of the edge dam and arranged at a predetermined height from the bath surface; A plurality of copper tubes are installed in each of the electromagnet cores, a plurality of copper tubes receiving a current from the power supply unit; Edges curl prevention apparatus of a twin roll type sheet casting machine using an electromagnetic field comprising a. The method of claim 5, wherein Each of the electromagnet cores is applied to the AC power having a phase difference of 2π / n (n: the number of the electromagnet core) is applied to the edge curl prevention device of a twin roll type sheet casting machine using an electromagnetic field. The method of claim 5, wherein The power supply unit includes: a moving field generating unit for forming a phase difference of AC power applied to the plurality of electromagnet cores; A current variable for varying the magnitude of the current applied to the electromagnet; And a power supply controller controlling the moving magnetic field generating unit so that each of the electromagnet cores has a constant phase difference, and controlling the flow rate of the molten steel by controlling the current variable to control the strength of the electromagnetic field formed on the water surface. Edge curl prevention device of a twin roll sheet metal casting machine using an electromagnetic field characterized in that.

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