JP2003305545A - Continuous casting apparatus and method for controlling flow of molten metal in mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce weight of a flow control apparatus for controlling flow of molten metal in a mold of a continuous casting apparatus. <P>SOLUTION: The mold 1 of the continuous casting apparatus is composed of a pair of long side walls 2 opposed to each other and a pair of short side walls 3 opposed to each other. Molten steel 5 is discharged from the tip end of the immersed nozzle 4, arranged at the central portion inside the mold 1, toward both short walls 3 in the downward direction of about 45°. The flow control apparatus 7 is composed of a coil 7a wound around the mold 1 so as to form a solenoid. When electric current is supplied to the coil 7a, a magnetic field directed vertically upward is generated within the molten steel in the mold 1. Thus, the flow control can be carried out such that the flow speed of the molten steel discharged from the immersed nozzle 4 is decreased because of generation of the vertically upward magnetic field within the molten steel in the mold 1. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting apparatus for controlling the flow of molten metal in a mold and a flow control method therefor.

[0002]

2. Description of the Related Art In a continuous casting apparatus, as shown in FIG. 8, molten steel 103 discharged from a dipping nozzle 101 into a mold 102 collides with short side walls on both sides and then onto the molten steel surface in the mold 102. The flow is divided into an upflow 104 and a downflow 105 to the lower part of the mold 102.

For example, if the downflow 105 is too strong, inclusions in the molten steel and gas bubbles blown from the immersion nozzle 101 or the like to prevent clogging of the immersion nozzle 101 are caught in the downflow 105 and the mold is cast. It penetrates deep into the bottom of 102. In this case, these inclusions and bubbles are not floated and separated, and remain in the slab and are unevenly distributed.
This is a factor that adversely affects the quality characteristics of the product.

As a method for preventing inclusions and bubbles from being trapped in the cast slab, as shown in FIG. 9, the iron core 106 and the coil are provided at predetermined height positions outside both long side walls of the mold 102. An electromagnet composed of 107 is provided, and a static magnetic field or a low-frequency AC magnetic field horizontal in the thickness direction of the mold 102 is generated in the vicinity of the molten steel 103 discharged from the immersion nozzle 101 (see the arrow in the figure) to melt the molten steel 103. The flow of water is controlled.

[0005]

However, when the electromagnet including the iron core 106 and the coil 107 is arranged outside the long side walls of the mold 102 as described above,
There is a problem that the size becomes large and the weight becomes large. In particular, since it is necessary to generate a magnetic field in the mold 102 via the mold 102, it is necessary to increase the size of the electromagnet in order to obtain the required magnetic force. Therefore, the mold 102
In some cases, the supporting mechanism for supporting the electromagnet and the electromagnet may be increased in size, or when the mold 102 is slightly vibrated, it is necessary to modify and increase the vibrating mechanism.

The present invention has been made in view of the above points, and an object thereof is to reduce the weight of a flow control device for controlling the flow of molten metal in a mold in a continuous casting device.

[0007]

A continuous casting apparatus according to the present invention comprises a mold comprising a pair of long side walls facing each other and a pair of short side walls facing each other, and both short side walls in the mold. It is characterized in that it is provided with a dipping nozzle for discharging molten metal in a predetermined direction and a flow control device for generating a magnetic field in the molten metal in the mold in the vertical direction.

Another feature of the continuous casting apparatus of the present invention is that the flow control device is constituted by a coil wound around the mold, or a core is provided around the mold, The point is that the coil is wound around the core.

The method for controlling the flow of molten metal in a mold according to the present invention is a mold comprising a pair of long side walls facing each other and a pair of short side walls facing each other, and both short side walls in the mold. A method for controlling the flow of molten metal in the mold in a continuous casting facility equipped with a dipping nozzle for discharging molten metal in the direction, in which a magnetic field is generated in the vertical direction in the molten metal in the mold. It has characteristics.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a continuous continuous casting apparatus and a molten metal flow control method in a mold according to the present invention will be described below with reference to the drawings.

1 and 2 show a schematic structure of a continuous casting apparatus according to this embodiment. As shown in the figure, the mold 1 of the continuous casting apparatus is composed of a pair of long side walls 2 facing each other and a pair of short side walls 3 facing each other. Mold 1
Is a method in which molten steel is cooled, shaped into a predetermined shape and solidified, while being drawn from below at a predetermined speed. In this case, the long side wall 2 direction of the mold 1 is the width direction of the slab,
The direction of the short side wall 3 is the thickness direction of the cast piece.

An immersion nozzle 4 for discharging molten steel supplied from a tundish (not shown) is arranged in the center of the mold 1. A pair of discharge holes 4a is formed at the tip of the immersion nozzle 4, and the short side walls 3 on both sides from these discharge holes 4a are formed.
The molten steel 5 is discharged downward about 45 degrees toward the side.

An electromagnetic stirrer 6 having a pair of cores and the like arranged so as to face each other with the mold 1 sandwiched therebetween is disposed outside both long side walls 2 on the upper part of the mold 1. Electromagnetic stirrer 6
Is molten steel filled in the upper part of the mold 1 (unsolidified portion)
It is a device that stirs molten steel by applying electromagnetic force to. Note that the illustration of the electromagnetic stirring device 6 is omitted in FIG.

Below the electromagnetic stirring device 6, a flow control device 7 for generating a magnetic field vertically upward in the molten steel in the mold 1 is arranged. The flow control device 7 is composed of a coil 7a wound around the mold 1 in a solenoid shape, and when a current is applied to the coil 7a, a magnetic field is generated in the molten steel in the mold 1 in a vertically upward direction. By thus generating a magnetic field vertically upward in the molten steel in the mold 1, the flow control can be performed so as to reduce the flow velocity of the molten steel discharged from the immersion nozzle 4. In contrast to the conventional horizontal magnetic field, the vertical upward magnetic field has the effect of suppressing the flow and fluctuation of the horizontal flow, but since the fluid is continuous, if the horizontal component is suppressed, As a result, the flow velocity of the vertical component can also be suppressed, so that flow control similar to that of the horizontal magnetic field becomes possible.

FIG. 3 shows a flow control device 7 of this embodiment.
The drawing shows the magnetic flux density distribution in the drawing direction at the center of the molten steel in the mold 1. Since the coils of the flow control device 7 have a finite length in the vertical direction, they are distributed in the vertical direction. As shown in the figure, in the area near the meniscus,
A magnetic flux density of about 0.4 [T], here about 0.4 [T], is generated. Immersion nozzle position (discharge position)
It is desirable that the peak of this magnetic field comes near

FIG. 4 shows magnetic flux densities of 0.0, 0.1, 0.2, in the region near the meniscus described in FIG.
The average flow velocity and the flow velocity standard deviation of the molten steel in the mold 1 near one short side wall 3 of the mold 1 when changed to 0.3 and 0.4 [T] are shown as a graph. For each magnetic flux density, the average flow velocity and the flow velocity standard deviation on one long side wall 2 (F face) side, thickness center, and the other long side wall 2 side (L face) were determined. As shown in the figure, the average flow velocity decreases as the magnetic flux density increases, and it can be seen that the flow velocity can be reduced by generating a magnetic field in the vertical direction.

FIG. 5 shows that the magnetic flux density of the vertically upward magnetic field is 0.
FIG. 6 is a diagram in which the average flow velocity in the area near the meniscus in the case of [T] is analyzed. FIG.
It is the figure which analyzed the average flow velocity in the vicinity area of a meniscus in the case of 4 [T]. As shown in FIG. 5, when the magnetic field is not generated in the vertically upward direction, the fluctuation of the flow of the molten steel is large, whereas as shown in FIG. You can see that it is suppressed.

As described above, by generating a magnetic field in the vertically upward direction, flow control can be performed so as to reduce the flow velocity. For example, the descending flow is too strong and inclusions and bubbles are floated and separated. It is possible to prevent the residual or uneven distribution in the cast piece. When performing this flow control, the coil 7a may be wound around the mold 1, so that it is significantly lighter than the case where an electromagnet composed of an iron core and a coil is arranged outside both long side walls of the mold. Can be realized.

In practice, when the mold has a weight of about 20 tons, the iron core 10 is placed outside both long side walls of the mold 102 as in the conventional example.
When disposing an electromagnet composed of 6 and the coil 107,
In order to generate a magnetic field having a magnetic flux density of 0.4 [T], the flow controller alone may produce about 20 tons,
It was found that when a magnetic field is generated in the vertically upward direction, about 2 tons is required to generate a magnetic field of the same degree.

It should be noted that the shapes and structures of the respective portions shown in the above-mentioned embodiments are merely examples of the embodiment in carrying out the present invention, and the technical scope of the present invention is thereby provided. It should not be construed as limiting. That is, the present invention can be implemented in various forms without departing from the spirit or the main features thereof.

For example, in the above-described embodiment, the coil 7a is wound directly around the mold 1. However, as shown in FIG. 7, a core (iron core) 7b is provided around the mold 1 and the core 7b is attached to the core 7b. The coil 7a may be wound around. With such a configuration, although the weight of the flow control device 7 is somewhat increased, it is possible to eliminate magnetic flux leakage and perform flow control more efficiently.

[0022]

As described above, according to the present invention, flow control can be performed so as to reduce the flow velocity by generating a magnetic field in the vertically upward direction. For example, the descending flow is too strong and inclusions are included. It is possible to prevent air bubbles and the like from remaining and unevenly distributed in the slab without being floated and separated. And
When performing this flow control, the weight can be significantly reduced as compared with the case where the electromagnets including the iron core and the coils are arranged outside the long side walls of the mold.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a continuous casting apparatus of the present embodiment.

FIG. 2 is a diagram showing a schematic configuration of a continuous casting apparatus of the present embodiment.

FIG. 3 is a diagram showing a magnetic flux density distribution in a drawing direction at a molten steel center in a mold 1.

FIG. 4 is a diagram showing an average flow velocity and a flow velocity standard deviation of molten steel in the mold 1 in the vicinity of one short side wall 3 of the mold 1 at each magnetic flux density.

FIG. 5 is a diagram in which an average flow velocity in a region near a meniscus when a magnetic flux density of a vertically upward magnetic field is 0 [T] is analyzed.

FIG. 6 is a diagram in which an average flow velocity in a region near a meniscus when a magnetic flux density of a vertical magnetic field is 0.4 [T] is analyzed.

FIG. 7 is a diagram showing a schematic configuration of a continuous casting device of another example.

FIG. 8 is a diagram for explaining molten steel flow in a mold.

FIG. 9 is a diagram showing a schematic configuration of a conventional continuous casting apparatus.

[Explanation of symbols]

1 mold 2 Long side wall 3 short side walls 4 immersion nozzle 5 Molten steel 6 Electromagnetic stirrer 7 Flow control device 7a coil 7b core

Claims (4)

[Claims] 1. A mold comprising a pair of long side walls facing each other and a pair of short side walls facing each other; an immersion nozzle for discharging molten metal in the mold in the direction of the both short side walls; A continuous casting apparatus comprising: a flow control device that generates a magnetic field in a vertical direction in molten metal in a mold. 2. The continuous casting apparatus according to claim 1, wherein the flow control device is constituted by a coil wound around the mold. 3. The continuous casting apparatus according to claim 2, wherein a core is provided around the mold, and the coil is wound around the core. 4. A mold comprising a pair of long side walls facing each other and a pair of short side walls facing each other, and an immersion nozzle for discharging molten metal toward the both short side walls in the mold. A method for controlling the flow of molten metal in the mold in a continuous casting facility, wherein the method for controlling the flow of molten metal in the mold is characterized in that a magnetic field is generated vertically in the molten metal in the mold. .