JP2003071548A - Continuous casting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous casting device for a metallic slab capable of giving a DC parallel magnetic field little in leakage flux to only a molten metal current in the metallic slab. SOLUTION: In the continuous casting device provided with a mold 3 provided with an immersion nozzle for pouring a molten metal on the upper part, containing a solidified shell which is formed by cooling gradually the molten metal poured from the immersion nozzle from the inner wall, and forming a metallic slab when the solidified shell is drawn out, a pair of coil members for giving an opposing DC parallel magnetic field between the long sides of the mold, and a DC current source for generating the DC parallel magnetic field by making flow a predetermined current in the coil part, the coil part is formed with rectangular laminate cores 42, 52 disposed parallel on the long sides of the mold, and coils 41, 51 formed by a conductor wound on the laminate cores parallel with the long sides of the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to continuous casting of metal slabs, and more particularly to a continuous casting apparatus used in a continuous casting machine and equipped with a molten metal flow control device for suppressing molten metal flow.

[0002]

2. Description of the Related Art In the conventional continuous casting of metal slabs, molten metal is injected into a rectangular mold from an immersion nozzle,
The molten metal is gradually cooled from the walls of the cooled mold to form a solidified shell, which is drawn downwards into a metal slab. The immersion nozzle is provided in the center of the horizontal surface of the mold, and the molten metal in the mold is discharged from the nozzle ejection port and flows, so that a reverse flow from the short side of the mold toward the immersion nozzle occurs in the meniscus surface. On the other hand, if the temperature of the molten metal is not uniform on the wall surfaces of the mold having the same height, vertical cracking of the solidified shell is likely to occur. In order to prevent this, the molten metal is made to flow within the meniscus surface by a known electromagnetic stirring method.

On the other hand, an immersion nozzle for injecting molten metal is provided in the upper part of the mold, and the molten metal injected from the immersion nozzle is gradually cooled from the cooled inner wall surface to form a solidified shell. . The solidified shell is contained on the inner wall surface in the mold, and a metal slab is generated when the solidified shell is drawn out. Therefore, when the molten metal is injected into the mold from the jet nozzle of the immersion nozzle, the molten metal moves in the mold by the flow of the metal accompanying the injection and the driving force for moving the molten metal by the electromagnetic stirring device. When the molten metal is drawn obliquely downward from the bottom of the mold, the flow of the molten metal does not stop even when the metal slab is formed.

[0004]

As described above, when the molten metal in the mold is caused to flow by the electromagnetic stirrer, it is possible to prevent vertical cracks from occurring in the metal slab when the molten metal is drawn out of the mold. However, excessive metal migration remains in the metal slab, causing cracking or hindering solidification and compromising the quality of the metal slab. It is an object of the present invention to brake the movement of the molten metal remaining in the metal slab as the metal slab is being drawn from the mold.

[0005]

A continuous casting apparatus according to the present invention has an immersion nozzle for injecting molten metal at its upper part, and the molten metal injected from the immersion nozzle is gradually cooled from a cooled inner wall surface. The inner wall surface contains the solidified shell formed by the above process, and a mold for producing a metal slab when the pseudo-solid shell is being drawn out, and a pair of a pair for applying a direct current parallel magnetic field between the long sides of the mold. In a continuous casting apparatus comprising a coil part and a direct current source for generating a direct parallel magnetic field by applying a predetermined direct current to the pair of coil parts, the coil part is parallel to the long side of the mold. And a coil made of a conductor wound on the laminated core.

Further, in the above continuous casting apparatus according to the present invention, the laminated core is made of a grain-oriented electrical steel sheet having a high magnetic permeability in the direction of the parallel magnetic field and a low magnetic permeability in the direction perpendicular to the direction of the magnetic field. It is configured by.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a continuous casting apparatus according to the present invention. In FIG.
1 is a molten metal injection port, 2 is a dipping nozzle, 3 is a mold, 4 and 5 are coil portions for suppressing the flow of molten metal, 41 and 51 are coils of the coil portions 4 and 5, 42 and 52 are These are laminated cores of the coil portions 4 and 5, respectively. The laminated cores 42 and 52 are formed by vertically arranging rectangular electromagnetic steel plates and laminating them in the horizontal direction. The magnetic steel sheets are arranged in the direction of the mold 3, and the magnetic flux penetrates the region where the metal slab is formed immediately below the mold 3, so that the laminated core 4 of the coil portions 4 and 5 is formed.
The structure is such that a magnetic flux can be obtained between 2 and 52.

FIG. 2 is an explanatory view showing a mounting position of a coil portion for suppressing the flow of molten metal. However, in this figure, rectangular electromagnetic steel plates are arranged side by side and stacked vertically. Figure 2
Then, the direction of the magnetic flux is x, and the directions perpendicular thereto are y and z as shown in the figure. In FIG. 2, 3 is a mold, 31 is a mold wall surface, and 4 and 5 are coil portions. The coils 41 and 51 are
They are formed by surrounding the laminated cores 42 and 52, respectively. DC power is supplied to the coils 41 and 51 from a DC current source (not shown), and a DC parallel magnetic field is generated. Here, the coils 41 and 51 are arranged on the yz plane in parallel with the long sides of the mold 3 so that the generated magnetic field is parallel to the short sides of the mold 3 in the x direction.
Rectangular laminate cores 42 and 52 are inserted in the interior of the. The cross sections forming the magnetic poles of the laminate cores 42 and 52 are formed parallel to the long sides of the mold 3, and the generated magnetic fields are precisely opposed to the opposed coil portions 4 and 5, respectively.

The magnetic steel sheet constituting the laminate core is a grain-oriented magnetic steel sheet, and its easy axis of magnetization (rolling directio).
n: RD) is arranged so as to face the direction of the DC parallel magnetic field of the coil portions 4 and 5, and the transverse direction (TD) perpendicular to the easy axis of the electromagnetic steel sheet faces the direction perpendicular to the DC parallel magnetic field. Are arranged as follows. Electrical steel sheet
For example, the permeability of the easy axis (RD) has a value of 30,000, and the permeability of the transverse axis (TD) has a value of 1,000. On the other hand, a magnetic steel sheet having a normal non-directional magnetic permeability has, for example, a magnetic permeability of RD and TD of 10,000.
It has a value of ˜17,000. Even with a non-oriented electrical steel sheet, the magnetic permeability in the thickness direction of the electrical steel sheet can be kept small, but with a magnetic steel sheet having a high directional magnetic permeability, the magnetic permeability in the transverse axis direction can be reduced. Therefore,
It is an essential point of the present invention to use a laminated core and also an electromagnetic steel sheet having a high magnetic permeability with directionality. By arranging the laminated cores as described above, the laminated cores 42, 52 in the coil portions 4, 5 are arranged.
It is possible to prevent the magnetic flux from leaking out of the facing space between them. In the present invention, since the magnetic flux does not leak from the space that requires the DC parallel magnetic field, for example, even when the electromagnetic stirrer is used together, the working magnetic flux is not adversely affected.

In any case, the laminated cores 42, 5
No. 2 is capable of generating a DC parallel magnetic field by laminating and forming a grain-oriented electrical steel sheet having a high magnetic permeability with directivity.
There are two methods as shown in (a) and (b).
In FIG. 3, 41 is a coil and 42 is a laminate core. FIG. 3 (a) shows a case where electromagnetic steel sheets are arranged in the vertical direction and are laminated in the horizontal direction, and FIG. 3 (b) shows a case where electromagnetic steel sheets are arranged in the horizontal direction and are laminated in the vertical direction. Figure 3
In (a) and (b), the arrangement of the electromagnetic steel sheets is RD in the direction of the DC parallel magnetic field, and TD is the direction perpendicular to the parallel magnetic field on the electromagnetic steel sheets. FIG. 4 is an explanatory diagram showing the relationship between the magnetic field H and the magnetic flux B in the grain-oriented electrical steel sheet. Easy axis (R
In the direction D), even if the magnitude of the magnetic field is small, the proportional relationship is satisfied between the magnetic field and the magnetic flux, and a large magnetic flux is obtained.
On the other hand, in the transverse axis (TD) direction, the increase in magnetic flux is small with respect to the increase in magnetic field until the magnetic field reaches the threshold value. Therefore, the directionality of the magnetic flux is maintained in the range where the magnetic field is sufficiently smaller than the threshold value.

FIG. 5 is a perspective view showing a pattern in which the coil portion is arranged immediately below the mold. In FIG. 5, AA corresponds to the cross section shown in FIG. Here, an electromagnetic stirrer (not shown) is arranged along the long side of the mold to apply electromagnetic induction entirely or selectively in the meniscus plane of the molten metal, and melts it by the action of its linear motor. Flow the metal clockwise or counterclockwise. Coil portions 4 and 5 are provided immediately below the mold 3. Therefore, it is necessary to configure the magnetic flux generated from the coil portions 4 and 5 so as not to adversely affect the operation of the device that controls and suppresses the movement of the other molten metal. Is used for the laminated core.

Next, the operation of suppressing the molten metal flow will be described. FIG. 6 is an explanatory diagram showing the principle of suppressing the molten metal flow in which the magnetic flux B generated in the coil section flows at the speed v. When the magnetic flux density B is applied to the molten metal particles when the molten metal particles move at a velocity v at an arbitrary position immediately below the mold 3, a current density j given by the following equation (1) in the vertical direction is given. Current flows. That is, j = σ (v × B) (1) Where σ is the conductivity. A force f given by the following equation (2) is generated by the current density j. f = j × B = σ (v × B) × B (2) where

[Equation 1] Assuming that

[Equation 2] Next, v fluidized deterrent to _y (one B _x ² v _y) are added.

[0013]

As described above, according to the present invention, in a continuous casting machine for metal slabs, a pair of coil portions for applying a DC parallel magnetic field which opposes the long sides of the mold to a rectangular mold, and the coil portion A coil portion is provided with a direct current source for passing a direct current, and a grain-oriented electrical steel sheet having a high magnetic permeability with directionality is used for the laminate core constituting the coil portion, and its easy axis is By matching the direction of the DC parallel magnetic field, the directivity of the DC parallel magnetic field can be improved and a high magnetic flux can be obtained in a predetermined direction. Therefore, since the leakage electromagnetic force is not given to the operation of the electromagnetic stirring device or the device for controlling and suppressing the molten metal by the electromagnetic force provided by being placed close to the coil portion, the operation thereof is adversely affected. The effect is that giving can be avoided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a coil portion of a continuous casting apparatus according to the present invention.

FIG. 2 is an explanatory view showing a mounting position of a coil portion of the continuous casting device according to the present invention.

FIG. 3 is an explanatory view showing lamination of electromagnetic steel sheets in the laminate core of the coil portion of the continuous casting device according to the present invention.

FIG. 4 is an explanatory diagram showing the relationship between magnetic field and magnetic flux of a grain-oriented electrical steel sheet.

FIG. 5 is a perspective view showing a position where a coil unit according to the present invention is installed in a continuous casting machine for metal slabs.

FIG. 6 is an explanatory diagram showing a relationship among a velocity, a magnetic flux density, a current density, and a force vector.

[Explanation of symbols]

1. Molten metal injection port 2. Immersion nozzle 2a, 2b ... Nozzle jet 3 ... Mold 31: Mold side wall 4, 5 ... Coil part 41, 51 ... Coil 42, 52 ... Laminated core

Claims (2)

[Claims] 1. A solidified shell, which is provided with an immersion nozzle for injecting a molten metal in an upper part thereof, and is formed by gradually cooling the molten metal injected from the immersion nozzle from a cooled inner wall surface, on the inner wall surface. Including, a mold for producing a metal slab when the solidified shell is being pulled out, a pair of coil portions for giving a DC parallel magnetic field facing each other between the long sides of the mold, and the pair of coil portions. A continuous casting apparatus comprising a direct current source for applying a predetermined direct current to generate the direct parallel magnetic field, wherein the coil portion is a rectangular laminate arranged parallel to a long side of the mold. A continuous casting apparatus comprising a core and a coil of a conductor wound on the laminate core in parallel with a long side of the mold. 2. The continuous casting apparatus according to claim 1, wherein the laminate core has a high magnetic permeability in the direction of the parallel magnetic field and a low magnetic permeability in a direction perpendicular to the direction of the magnetic field. A continuous casting device characterized by being constructed using electromagnetic steel sheets.