JPH05123833A - Method and device for preventing leakage of molten metal in twin roll type continuous casting - Google Patents

Abstract

PURPOSE:To prevent the leakage of molten metal from a pouring basin part formed at the upper part of twin rolls in a twin roll type continuous casting. CONSTITUTION:In the twin roll type continuous casting, side weirs embedding the electrodes 9a, 9b to both sides of the cooling rolls 1a, 1b are arranged. In the upper part of the molten metal pool, DC current is conducted between the electrodes 9a, 9b and the cooling rolls 1a, 1b, and in the lower part of the molten metal pool, DC current is conducted between the cooling rolls 1a, 1b, and further, DC magnet flux is energized at the right angle to the DC current with a magnet 3 and electromagnetic force is acted to the inner direction in the molten metal. By this method, the leakage of the molten metal can be prevented and the stable continuous casting in the long time can be obtd., and the production efficiency and the casting yield are drastically improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing molten metal from leaking out from a pool formed above a twin roll when directly manufacturing a thin metal sheet from a molten metal by a twin roll type continuous casting facility. Regarding the device.

[0002]

2. Description of the Related Art In recent years, in the field of continuous casting of steel and special steel in which a large amount of nickel, cobalt, manganese, chrome, silicon, copper, etc. are added to the steel, the development of casting technology for thin cast slabs is strongly desired, Various methods have been proposed, and some of them have reached the level of industrial production, but have not yet reached the stage of completion in terms of productivity, operational stability, and the like.

[0003]

[Problems to be Solved by the Invention]
For example, there are vertical or inclined twin roll type continuous casting equipment,
In these cases, there is a problem in operation where durability is the main factor.
The problems are abrasion of the part where the side weir slides in contact with the surface of the cooling roll, casting of molten steel alloy into the side weir wear part, and rapid damage to the side weir. ..

As a measure for preventing such wear and damage of the side weir, supply of a sealant or a lubricant to the sliding portion of the side weir is disclosed in, for example, JP-A-60-21159 and JP-A-60-2.
It is disclosed in Japanese Patent No. 1154. In the continuous casting apparatus for thin plates described in these publications, a liquid for slab width regulation fixed wall corresponding to a side dam, and a liquid or semi-liquid sealing substance are caused to flow into a gap between the surface of a rotating roll, and a pressure-controlled gas. To prevent the molten metal from being inserted.

However, according to the experiments conducted by the present inventors, since the temperature of the part where the side dam and the roll are close to each other is 1000 ° C. or higher in the case of a device for casting steel, not only ordinary lubricants, Even with a molten salt lubricant, a part of it decomposes to generate gas, and there is a great risk of impairing the quality of steel that originally requires a high degree of cleanliness.

Due to such a problem, a method using electromagnetic force has been considered in addition to the mechanical method. For example, there is a method of arranging a coil outside the side weir and passing a strong high frequency current. Then, the electric thrust is not concentrated on the important portion to be sealed, and only the roll or the molten steel is heated at high frequency or the molten steel is electromagnetically stirred, which is not practical.

Among these techniques, there is an invention disclosed in Japanese Unexamined Patent Publication No. 62-104653 as a practical technique with limited use. In the molten metal end face shape control method and apparatus disclosed herein, a direct current is applied between the rolls facing each other to form a molten metal pool, and a direct current magnetic flux is applied at a right angle to this direct current, The molten metal is held by the electromagnetic force generated from the end of the roll toward the inner side in the axial direction of the roll to adjust the shape of the end face of the molten metal.

However, in this method, when the molten metal pool is deepened in order to increase the casting speed, the direct current to be passed through the pool is concentrated in the lower part of the molten metal pool, and the electromagnetic force required in all the height direction of the molten metal pool is obtained. For this reason, the density of the direct current in the lower part of the molten metal pool becomes very large, and the damage of the part of the roll that contacts the pool is not negligible. Further, when casting a wide slab, the width of the pool becomes large, and a strong current cannot be collected at both ends of the essential pool unless special measures are taken. It is also conceivable to coat or spray a highly insulating material other than both ends of the pool so that only the both ends of the pool are energized, but casting efficiency is impaired, and slabs due to uneven coating thickness It is hard to say that it is practical because there is a risk of cracking.

In view of the above problems, the present invention prevents the molten metal from leaking from between the cooling roll and the side weir by exerting an electromagnetic force in a concentrated manner only on a necessary portion of the side weir when casting a thin cast piece. It is an object of the present invention to provide a method and an apparatus having a structure that efficiently and surely prevents them.

[0010]

The method for preventing molten metal leakage according to the present invention is a twin roll for casting a thin cast piece by storing molten metal in a mold constituted by a pair of cooling rolls and a pair of side dams. In continuous die casting equipment, a direct current is applied between the electrode installed on the side dam and the cooling roll in the upper part of the molten metal, and a direct current is applied between the cooling rolls in the lower part of the molten metal. Is a molten metal leakage preventing method in twin roll type continuous casting, characterized in that an electromagnetic force is generated from the end of the cooling roll toward the inner side in the cooling roll axial direction by applying Is an electrode for applying a direct current to the surface of the pair of cooling rolls or a current collecting ring on the outer portion, an electrode for applying two direct currents to one side dam attached to the pair of side dams, and a cooling roll. A hot water leakage prevention apparatus in twin roll type continuous casting comprising a pair of DC magnetic flux generating device disposed in the vicinity gap of the side weir.

[0011]

The present invention provides a twin roll type continuous casting facility for casting a thin cast piece by storing molten metal in a mold constituted by a pair of cooling rolls and a pair of side dams.
As shown in Fig. 5, a direct current is applied between the electrodes 9a, 9b provided on the side dam and the cooling rolls 1a, 1b in the upper part of the molten metal pool, and the lower part of the molten metal pool in which the electrodes 9a, 9b cannot be installed is the cooling rolls 1a, 1b. A minimum necessary direct current is applied between them, and a direct current magnetic flux is applied to these direct currents by the magnet 3 at right angles to the cooling roll 1.
A method for preventing molten metal leakage is characterized in that an electromagnetic force is generated from the ends of a and 1b inward in the axial direction of the cooling roll. According to this method, since a high current density can be efficiently applied to the molten metal in the vicinity of the gap between the cooling rolls 1a, 1b and the side dams 2a, 2b where leakage of the molten metal is likely to occur, the temperature of the surface layer of the molten metal does not increase, In addition, pool and cooling roll 1a,
It is possible to prevent molten metal leakage without applying a large current that damages the contact portion of 1b.

In the method and apparatus for preventing molten metal leakage in twin roll type continuous casting according to the present invention, side dams 2a and 2b having electrodes 9a to 9b embedded therein are provided so as to approach or lightly contact the body surfaces of the cooling rolls 1a and 1b. As shown in FIG. 2, a direct current is passed from the cooling roll 1a to the electrode 9a provided on the side weir in the upper part of the molten metal pool, and a direct current is passed between the cooling rolls 1a and 1b in the lower part of the molten metal pool by the magnet 3. By applying a DC magnetic flux at a right angle,
As shown in FIGS. 3 and 4, an electromagnetic force inward is applied to the molten metal to adjust the shape of the molten metal and prevent leakage of the molten metal.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a view showing the appearance of the apparatus of the present invention, FIG.
Is a side view thereof. 20 in a mold composed of a pair of cooling rolls 1a and 1b and a pair of side dams 2a and 2b.
Pool the molten metal with a depth of ~ 50 cm, and use the cooling rolls 1a, 1
It is cooled in b and solidifies to cast a thin plate.

Using the pair of magnets 3a and 3b and the pair of magnet power supplies 7, the molten metal in contact with the pair of side dams 2a and 2b has a different direction parallel to the casting direction as shown in FIGS. By generating the magnetic fluxes H ₁ and H ₂ , electromagnetic forces F ₁ and F ₂ in opposite directions are generated by the side dams 2 a and 2 b facing the electrode current i ₁ and the inter-roll current i ₂ .

The pair of side weirs 2a, 2b has two electrodes 9a, 9b per side weir. Electrode 9a
The electric current flowing in the molten metal from the cooling roll 1a to the cooling roll 1a constitutes an electric circuit with the electrode 9a, the cooling roll 1a and the current collecting ring 4a as shown in FIG. Controlled by.

Electrodes 9 embedded in the side weirs 2a, 2b
Each of a and 9b is made of a heat resistant conductive material, and a heat resistant insulating material 13 is inserted between the electrodes to have an electric resistance. Further, the heat-resistant insulating material 13 is also provided between the electrodes 9a and 9b and the cooling rolls 1a and 1b to form an electric circuit through the molten metal. When the casting width is constant, the side dams 2a and 2b are fixedly installed outside the cooling rolls 1a and 1b and slide on the sides of the cooling rolls 1a and 1b. When the casting width is variable, it is installed on the cooling rolls 1a and 1b and slides on the roll surface. Electrodes 9a, 9b and cooling roll 1a,
The amount of current flowing between 1b is proportional to the interval, and is constant when the interval is constant, and the electromagnetic force is also constant. On the other hand, the electrode 9
If the space between a and 9b and the cooling rolls 1a and 1b is widened in the upper part of the molten metal and narrowed in the lower part of the molten metal, the energizing current and electromagnetic force are small in the upper part of the molten metal and large in the lower part of the molten metal, which is proportional to the static pressure of the molten metal and is efficient. Electromagnetic force is obtained.

The electric current between the cooling rolls 1a and 1b is controlled by the inter-roll DC power source 6 in an electric circuit composed of the pair of cooling rolls 1a and 1b and the current collecting rings 4a and 4b.

FIG. 5 is a diagram showing an example of sharing of the electromagnetic force by the electrode current and the roll-to-roll current. Electromagnetic force between rolls 10
Is set to be larger than the molten metal static pressure 12 within a range in which an electromagnetic force inversely proportional to the interval between the cooling rolls 1a and 1b is generated and the electrode electromagnetic force 11 does not act. Electrode electromagnetic force 11 is set to be larger than molten metal static pressure 12 as combined electromagnetic force 14 with roll-to-roll electromagnetic force 10.

[0020]

In the method and apparatus for preventing molten metal leakage in twin roll type continuous casting according to the present invention, the electromagnetic force is concentrated on a predetermined portion of the molten metal in contact with the side dam to effectively prevent leakage of molten metal. In addition to preventing this, the side weir seals are not in contact with the cooling rolls or are used with a lighter contact pressure than conventional ones, which not only enables stable operation for a long time, but also makes it possible to use cooling rolls with long body lengths. By combining the above, it is possible to continuously change the casting width of a wide range of slabs, and the production efficiency and the casting yield are greatly improved. In addition, since solidification progresses in the lower part of the molten metal pool, there are many areas in the height direction where molten metal is likely to leak, and it is possible to partially seal only the easily leaked portion of the molten metal only by the electromagnetic force of the electrode without using the electromagnetic force of the drum. .. Furthermore, it is also possible to apply it to the prevention of molten metal leakage in twin belt type continuous casting having the same function as twin roll type continuous casting.

[Brief description of drawings]

FIG. 1 is a diagram showing an external appearance of a molten metal leak prevention device of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is an explanatory diagram showing a generation principle of an electrode current electromagnetic force due to a current flowing between an electrode attached to a side dam and a cooling roll.

FIG. 4 is an explanatory diagram showing a principle of generating a current electromagnetic force between rolls by a current flowing between cooling rolls.

FIG. 5 is a characteristic diagram showing the electrode electromagnetic force, the roll-to-roll electromagnetic force, the combined electromagnetic force, and the molten steel static pressure.

[Explanation of symbols]

 1a, 1b Cooling roll 2a, 2b Side weir 3, 3a, 3b Magnet 4a, 4b Current collecting ring 5a, 5b DC power supply for electrode 6 DC power between rolls 7 Magnet power supply 8 Molten metal injection nozzle 9a-9d Electrode 10 Electromagnetic force between rolls 11 Electrode Electromagnetic Force 12 Molten Metal Static Pressure 13 Heat Resistant Insulating Material 14 Synthetic Electromagnetic Force

Claims (2)

[Claims] 1. A twin-roll type continuous casting facility for casting a thin-walled slab by storing molten metal in a mold composed of a pair of cooling rolls and a pair of side dams. A direct current is applied between the electrode and the cooling roll, and a direct current is applied between the cooling rolls in the lower part of the molten metal. A method for preventing molten metal leakage in twin roll type continuous casting, characterized in that an electromagnetic force is generated inwardly of the direction. 2. An electrode for applying a direct current to the surface of the pair of cooling rolls or a current collecting ring on the outer portion, an electrode for applying two direct currents to one side dam attached to the pair of side dams, and cooling. A twin-roll continuous casting molten metal leak prevention device comprising a pair of DC magnetic flux generators arranged near the gap between the roll and the side dam.