JPH05318070A - Continuous casting apparatus - Google Patents

Abstract

PURPOSE:To obtain a cast billet having high cleanliness by controlling flow rate of molten steel at the time of pouring the molten steel into a mold with the shape of a pouring nozzle and the arrangement of an electromagnetic brake. CONSTITUTION:The pouring nozzle 9 is formed with a horizontal part 9A connected with a tundish 1 and a vertical part inserted into the mold 5, and the cross-sectional shape of the molten steel passage 9a in the horizontal part 9A is formed so that the width direction becomes large to the height (h) direction. By the electromagnetic brake 8 arranging magnetic poles so as to hold the horizontal part 9A of the pouring nozzle 9 from the vertical direction thereof, static magnetic field is impressed to the fluidized molten steel in the pouring nozzle 9 to control the flow rate of the molten steel 2 in the pouring nozzle 1 to the flow rate having the prescribed value or lower.

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 injecting molten steel in a tundish into a mold to produce a slab, and more specifically to controlling the flow rate of the molten steel injected into the mold by an electromagnetic brake. The present invention relates to a continuous casting device.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a conventional continuous casting apparatus for producing molten slab by injecting molten steel in a tundish into a mold. In FIG. 8, the molten steel 2 transferred from the ladle into the tundish 1 floats the inclusions contained in the molten steel in the tundish 1, then opens the sliding nozzle 7, and passes through the immersion nozzle 3 to pass the mold 5
Is injected into. Here, the mold powder 4 floating on the surface of the molten steel 2 in the mold 5 is, as is well known,
It functions to prevent oxidation of the molten steel 2, keep it warm, and adsorb nonmetallic inclusions.

[0003]

By the way, in the recent continuous casting process, in order to improve the productivity of the slab, the casting rate of molten steel may exceed Vc = 2.0 m / min. However, in the conventional continuous casting apparatus, as shown in FIG. 8, since the immersion nozzle 3 is vertically arranged in the center of the mold 5, the molten steel 2 poured into the mold 5 is cast in the casting direction 6. Of the molten steel 2 tended to increase in proportion to the casting speed Vc of the molten steel 2.

Therefore, in the conventional continuous casting apparatus, the inclusions contained in the molten steel (in particular, the inclusions having a size of 100 μm or less) are injected into the mold 5 without floating during the floating in the tundish 1, Further, there is a problem that the inclusions are trapped in the slab as they are, and a slab with defects is produced.

In order to prevent the occurrence of defects due to the trapping of such inclusions, conventionally, as shown in FIG. 8, an electromagnetic brake 8 disposed on the outer side of the mold 5 is used.
An apparatus configured to suppress the downward flow of the molten steel 2 in the mold 5 as much as possible, a method of using a large tundish 1 to promote floating of inclusions in the tundish 1, and the like have been proposed.

However, in the former case, it is difficult to float inclusions in the mold 5 at the time of high-speed casting such that the casting speed of the molten steel exceeds Vc = 2.0 m / min, and a great effect is not obtained. ..

Further, in the latter case, the tundish 1 is increased in size, so that the equipment is increased in size and the refractory basic unit is increased, which leads to an increase in the cost of the apparatus.

An object of the present invention is to control a flow rate of molten steel at the time of injecting molten steel into a mold by controlling a shape of a pouring nozzle and an arrangement of an electromagnetic brake to obtain a slab with high cleanliness. To provide.

[0009]

In order to solve the above problems, the present invention provides a continuous casting apparatus for injecting molten steel in a tundish into a mold to produce a slab, wherein the tundish and the mold are A pouring nozzle that is disposed between the tundish and a horizontal portion connected to the tundish and a vertical portion that is inserted into the mold. The horizontal section of the pouring nozzle is formed as an actuator for controlling the flow velocity of the molten steel in the pouring nozzle by decelerating the cross-sectional shape of the flow path of the horizontal section of the pouring nozzle so that the width direction is larger than the height direction. Is configured so that a static magnetic field is applied to the molten steel flow in the pouring nozzle by an electromagnetic brake in which magnetic poles are arranged so as to hold it from above and below.

[0010]

According to the present invention, the portion of the pouring nozzle connected to the tundish forms a horizontal portion, and the cross-sectional shape of the flow passage is larger in the width direction than in the height direction. Since the molten steel discharge velocity is slowed down, the flow in the pouring nozzle is reduced by the electromagnetic brake that has magnetic poles that hold the horizontal part of the pouring nozzle from the vertical direction. By applying a static magnetic field to the molten steel, the flow velocity of the molten steel in the pouring nozzle is controlled to a predetermined flow velocity.

[0011]

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

As shown in FIG. 1, the continuous casting apparatus according to the present invention includes a tundish 1, a mold 5, an electromagnetic brake 8, a pouring nozzle 9, a stopper 10, a DC power supply 13, a controller 14, a mold level gauge detector. 15 and a mold level meter amplifier 16 and the like.

As shown in FIG. 2, the pouring nozzle 9 is of a completely closed type having a horizontal portion 9A connected to the tundish 1 and a vertical portion 9B inserted into the mold 5. The molten steel flow path 9 in the horizontal portion 9A
As shown in FIG. 3, the sectional shape of a is formed so that the width w direction is larger than the height h direction.

Further, in the vertical portion 9B of the pouring nozzle 9 in this embodiment, the discharge port of the molten steel flow path 9b is, as shown in FIG. 4, a conventional round dipping nozzle 3 (see FIG. 8). Instead, it is formed in a flat shape. The molten steel discharge area of the horizontal portion 9A and the vertical portion 9B of the pouring nozzle 9 is larger than the discharge area of the conventional immersion nozzle. Therefore, according to the pouring nozzle 9 of the present embodiment, the discharge flow velocity of the molten steel 2 into the mold 5 can be suppressed low. Further, the pouring nozzle 9 in this embodiment has the horizontal portion 9A.
Has a length L of 300 mm or more.
An electromagnetic brake 8 is provided on the horizontal portion 9A of the pouring nozzle 9.

As shown in FIG. 5, the electromagnetic brake 8 of this embodiment has a coil 12 wound around the outer circumference of a U-shaped iron core 11.
A direct current is applied from the direct current power supply 13 to the magnetic core 11 to generate a static magnetic field between the magnetic poles 11a of the iron core 11 facing each other.

Both magnetic poles 11a of the electromagnetic brake 8 are arranged so as to sandwich the horizontal portion of the pouring nozzle from above and below, and the electromagnetic brake 8 keeps the molten molten steel in the pouring nozzle 9 stationary. It functions as an actuator that applies a magnetic field to control the flow velocity of the molten steel 2 in the pouring nozzle 9 to a predetermined flow velocity of 0.5 m / sec or less.

On the other hand, a mold level gauge detector 15 is attached to the mold 5, and the level of the molten steel 2 in the mold 5 is detected by the mold level gauge detector 15. The mold level meter detector 15 is configured to output a mold level signal when the level of the molten steel 2 in the mold 5 reaches a predetermined level, and the mold level signal is shown in FIG. As described above, it is input to the control device 14 as a control signal through the mold level meter amplifier 16.

The control device 14 changes the applied current to the coil 12 of the electromagnetic brake 8 via the DC power source 13 according to the presence or absence of the mold level signal from the mold level meter detecting section 15 to change the molten steel 2 in the mold 5. The flow rate of the molten steel 2 in the pouring nozzle 9 is controlled to a predetermined flow rate so that the above level is always kept at a predetermined level.

Here, in this embodiment, the height h of the molten steel flow passage 9a in the horizontal portion 9A of the pouring nozzle 9 is 60 to 80.
mm, the width w is 300 to 400 mm, the length L of the horizontal portion 9A is about 300 mm, and the flow velocity Vc of the molten steel 2 is 0.5.
To control between ~ 0.2 m / sec, about 10,0
The coil 12 having a magnetomotive force of 00 (AT) was required.

Further, in this embodiment, in order to take out as much as possible the braking force by the "eddy current" generated by the electromagnetic brake 8 in the molten steel flow, the two magnetic poles 1 of the iron core 11 are taken out.
The horizontal portion 9A of the pouring nozzle 9 held by 1a is formed so that the flow direction of the "eddy current" generated by the electromagnetic brake 8 in the molten steel flow is the direction in which the braking force is generated according to Faraday's law. ing.

In the present embodiment, the method of controlling the flow velocity of the molten steel 2 by the electromagnetic brake 8 is adopted. However, as another method of controlling the flow velocity of the molten steel 2, the molten steel flow is controlled by the moving magnetic field. You can However, when this moving magnetic field system is adopted, the pole pitch in the coil 12 needs to be large in the flow direction of the molten steel 2, so that the space limitation becomes large and the power supply equipment becomes complicated. There is.

As described above, according to the present embodiment, the pouring of the tundish 1 is controlled by the stopper 10 (or the sliding nozzle 7 as shown in FIG. 8) as shown in FIG. With the electromagnetic brake 8
The flow velocity of the molten steel 2 in the pouring nozzle 9 is suppressed to a flow velocity of 0.5 m / sec or less by the electromagnetic force braking the molten steel 2 flowing in the horizontal portion 9A of the pouring nozzle 9.

Further, according to this embodiment, since the width w of the molten steel flow passage 9a in the horizontal portion 9A of the pouring nozzle 9 is formed relatively large, small inclusions are formed in the top plate of the molten steel flow passage 9a. It is also possible to improve the cleanliness of the molten steel 2 by adhering.

FIG. 6 shows the molten steel passage 9a (9
This is an embodiment in which a corrugated groove is formed on the wall surface of b), and according to this embodiment, the contact area between the molten steel 2 and the wall surface in the pouring nozzle 9 is increased, and inclusions on the wall surface are increased. The adhesion was further promoted, and the removal efficiency of inclusions in the molten steel was improved.

Further, the pouring nozzle 9 in this embodiment is
Since the mounting direction with respect to the tundish 1 is horizontal, it is possible to smoothly perform the replacement work of the pouring nozzle 9 during the casting of the molten steel 2. Here, as shown in FIG. 7, the vertical portion 9B is configured to be detachable from the horizontal portion 9A of the pouring nozzle 9, and the vertical portion 9B can be attached as required.
By exchanging only one, the operation of exchanging the pouring nozzle 9 can be performed more smoothly. In the pouring nozzle 9 shown in FIG. 7, the joining portion 9c of the horizontal portion 9A and the vertical portion 9B is formed in a tapered shape, and the molten steel flow passage 9a (9b) is formed.
It is configured to prevent air from entering the inside.

As described above, according to this embodiment, the molten steel 2
Since the flow path of is a completely closed type and the flow velocity of the molten steel 2 is maintained substantially constant, in the flow path of the molten steel 2,
Inclusions in molten steel can be removed.

Further, in this embodiment, as the flow rate control actuator for the molten steel 2, since the electromagnetic brake 8 such as the stopper 10 or the sliding nozzle 7 which does not fluctuate in the flow coefficient due to clogging of the molten steel 2 is used, the tundish is adopted. It is possible to perform stable molten steel flow rate control even with respect to disturbances such as fluctuations in the molten steel amount and the molten steel temperature within 1.

Therefore, according to the present embodiment, the control accuracy of the mold level of the molten steel 2 in the mold 5 is improved, and it is possible to obtain a slab having a good surface quality and internal quality and a high cleanliness.

[0029]

According to the present invention, since the flow rate of molten steel in the pouring nozzle can be suppressed to a predetermined value or less, inclusions in the molten steel can be largely removed. Further, according to the present invention,
Since the molten steel passage of the pouring nozzle is formed horizontally and flatly, the cleanliness of the molten steel can be improved by adhering inclusions to the wall surface of the molten steel passage of the pouring nozzle. Further, according to the present invention, the gap between both magnetic poles of the electromagnetic brake can be narrowed, so that the power consumption thereof can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic side view of a continuous casting apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view of a pouring nozzle in the continuous casting device.

FIG. 3 is a sectional view of a horizontal portion of the pouring nozzle.

FIG. 4 is a sectional view of a vertical portion of the pouring nozzle.

FIG. 5 is a schematic cross-sectional view of an electromagnetic brake disposition part of a pouring nozzle in the continuous casting device.

FIG. 6 is a schematic cross-sectional view of another pouring nozzle in the continuous casting device.

FIG. 7 is a schematic cross-sectional view of still another pouring nozzle in the continuous casting device.

FIG. 8 is a schematic sectional view of a conventional continuous casting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tundish 2 Molten steel 5 Mold 8 Electromagnetic brake 9 Pouring nozzle 9A Horizontal part of pouring nozzle 9B Vertical part of pouring nozzle 9a, 9b Molten steel flow path 10 Stopper 11 Iron core 11a Magnetic pole 12 Coil 13 DC power supply 14 Control device 15 Mold level meter detector 16 Mold level meter amplifier

Claims (1)

[Claims] 1. A continuous casting apparatus for injecting molten steel in a tundish into a mold to produce a slab, which is disposed between the tundish and the mold to form a channel for the molten steel. The hot water nozzle is formed of a horizontal part connected to the tundish and a vertical part inserted into the mold, and the cross-sectional shape of the flow path of the horizontal part of the pouring nozzle is set with respect to the height direction. As an actuator for controlling the flow velocity of molten steel in the pouring nozzle to be decelerated in a widthwise direction, an electromagnetic brake with magnetic poles arranged so as to hold the horizontal part of the pouring nozzle from above and below A continuous casting apparatus, wherein a static magnetic field is applied to the liquid molten steel in the pouring nozzle.