JPS63295048A - Apparatus for controlling variation of molten surface - Google Patents

Abstract

PURPOSE:To prevent development of surface defect caused by including powder and occurrence of breakout caused by remelting solidified shell by arranging a controlling device controlling distance of a shifting device of colliding plates by transmitting output from a molten surface leveller to control variation of the molten surface into the suitable range. CONSTITUTION:The molten steel 15 in a tundish 10 is poured into a mold 20 from discharging holes 22 through a sliding nozzle 25 and submerged nozzle 21. The discharged flow 23 of the molten steel 15 from the discharging hole 22 is flowed toward short side wall through hole 31 in the colliding plates 30 and collides with the short side wall and divides into streams upward and downward. In the case of detecting the stream of the molten steel 15 with the molten surface leveller 40 as abnormal variation of the molten surface, which the variation degree of the molten surface is out of the suitable range, the colliding plates 30 are pulled up with supporting rod shifting devices 33 through the supporting rods 32. By this method, the lower side of the discharged flow 23 collides with the lower side of the hole 31 in the colliding plate 30 and changes its flowing direction and does not come to the short side of a mold. Therefore, the flow toward the molten surface 24 caused to much variation of the molten surface is weakened, and the variation thereof is made to little.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a mold level fluctuation control device in continuous slab casting.

[Conventional technology]

Figure 3 shows the main parts of the continuous slab casting machine near the mold. The prior art will be explained with reference to this figure.

Above scene 8 in the mold is to prevent oxidation of molten steel and keep it warm.

A layer 5 of molding powder is formed which functions as lubrication between the slab and the mold and traps non-metallic inclusions.

The scene side of this layer becomes molten due to the heat of the molten steel, and the upper side becomes a powder 7 that covers the scene. The molten powder 6 flows down between the solidified shell 9 and the inner wall of the mold 1 and plays the role of a lubricant. Therefore, since the powder is consumed, it is necessary to maintain a constant thickness of the powder N5 in order to compensate for the amount of consumption. will be replenished accordingly.

As shown in Fig. 3, molten steel is discharged from an immersion nozzle 2 provided vertically in the center of the mold, and discharge ports 3 provided at the tip of the immersion nozzle face each other in the short side direction of the mold. There is one opening in each. Molten steel is discharged into the mold from this discharge port.

It is cooled by the mold 1 and a solidified shell 9 is formed.

[Problem that the invention seeks to solve]

However, this discharge flow 4 collides with the short side and is divided into two flows, an upper and lower flow, and the upward flow causes a fluctuation in the melt level.

Flow rate of molten steel injected into the mold, mold size, discharge ff1
The magnitude of the fluctuation in the hot water level changes depending on the angle in step 4.
The upper part of the immersion nozzle 2 is connected to the tundish via a sliding nozzle (not shown), but when the sliding nozzle is used to adjust the flow rate, the opening of the sliding nozzle is eccentric to the molten steel flow path of the immersion nozzle 2, as shown in FIG. In this case, the flow rate of the molten steel from the two left and right discharge ports 3 may be different, which may cause a so-called uneven flow. Furthermore, when alumina adheres to the inside of the immersion nozzle 2, the molten steel flow inside the immersion nozzle is disturbed and the aforementioned drifting may cause azuki beans, but such drifting also causes asymmetrical molten metal level fluctuations with respect to the immersion nozzle as shown in Fig. 3. There is a risk that this may occur.

When the melt level fluctuates greatly, the molten steel scene is stirred and the powder layer 5 covering the scene is rolled up, causing surface defects due to powder entrainment, and the solidified shell 9 is remelted, causing breakout.

The present invention has been made in view of the above circumstances, and is a molten WJ that realizes an appropriate level fluctuation regardless of whether the level fluctuation is symmetrical or asymmetrical as shown in Fig. 2.
It is intended to provide a flow device.

[Means for solving problems]

A hot water level fluctuation control device according to the present invention includes a collision plate movably provided in a direction across a flow path of a discharge passage from a discharge port of a submerged nozzle in a hot water level fluctuation control device used in a continuous slab casting device. , characterized in that it comprises a moving device that moves the collision plate, and a plurality of water level gauges that measure the magnitude of fluctuations in the water level.

[For production]

In the hot water level fluctuation control device according to the present invention.

If a hot water level gauge that measures the magnitude of the hot water level fluctuation detects that the hot water level fluctuation has exceeded the magnitude, for example, if the hot water level fluctuation is excessive, the collision plate moving device is used to remove the immersion. The position of the collision plate is adjusted to a position where it blocks a portion of the discharge flow of molten steel discharged from the discharge port of the nozzle. In this way, part of the discharge flow hits the collision plate and its strength is reduced, and therefore the upward flow that hits the short length of the mold is also relaxed, so the magnitude of the fluctuation in the melt level is improved from excessive to appropriate. Ru.

Fluctuations in the hot water level are normally approximately symmetrical around the immersion nozzle, but if this becomes even more unbalanced and this is detected by multiple level gauges placed above the hot water level, the fluctuations on the left and right sides will occur. By adjusting the positions of the collision plates facing the discharge ports individually as described above using a moving device to alleviate the strength of the discharge flow, the unbalance of the fluid level fluctuation can be improved, and the proper level can be maintained. Fluctuations in hot water level can be obtained.

〔Example〕

An embodiment of the present invention will be described with reference to the accompanying drawings.

Figure 1 shows the hot water level fluctuation system of the present invention? FIG. 2 is a sectional view showing the main parts near the mold showing the II+ device.

In the mold, a tundish 10 is arranged above the mold 20, and a sliding nozzle 25 and an immersion nozzle 21 connected thereto are provided at the bottom thereof. One discharge port 22 provided at the tip of the immersion nozzle 21 is opened on each side of the immersion nozzle, facing the short length direction of the mold 20. One collision plate 30 is disposed opposite the discharge ports 22 provided on both sides of the immersion nozzle.

FIG. 2 is a front view of the collision plate 30.
A hole 31 having a sufficient size through which the discharge flow 23 of molten steel from the discharge port 22 passes is provided in the center.

A support rod 32 is attached to the upper part of the collision plate 30 for moving it, and the support rod 32 is connected to a collision plate moving device 33 attached to the bottom of the tundish 10 so as to be easily attached and detached. .

Further, above the hot water level in the mold, hot water level gauges 40 for measuring the magnitude of the hot water level fluctuation are provided so that the measuring position can be moved one by one on either side of the immersion nozzle.

The operation of the hot water level fluctuation control device configured as described above will be explained.

The /8E15 in the kundish 10 is injected from the sliding nozzle 25 through the immersion nozzle 21 and into the mold from the discharge port 22. A discharge flow 23 of molten steel from the discharge port 22 passes through the hole 31 of the collision plate, heads in the direction of the short side, hits the short side, and is divided into upward and downward flows.

Of these, the molten steel flow that heads upward toward the hot water level 24 is a major factor in the hot water level fluctuation.

When such a flow of molten steel causes the level gauge 40 to detect a level fluctuation that is beyond the appropriate range, for example, when the level fluctuation is equally large on both sides of the immersion nozzle 21. In this case, the collision plate 30 is pulled up via the support rod 32 by the support rod moving device.

In this way, the lower side of the discharge flow 23 collides with the lower side of the hole 31 of the collision plate 30 and is changed in direction, and does not reach the short side of the mold.
Therefore, the flow toward the hot water level 24, which is a major cause of the hot water level fluctuations, is weakened, and the hot water level fluctuations are reduced.

As mentioned above, in order to weaken the same magnitude of melt level fluctuation on both sides of the immersion nozzle 21, the two collision plate moving devices 33 are used.
The magnitude of the level fluctuation is adjusted by raising the same distance at the same time. However, in the case of the level fluctuation due to so-called drifting, where the strength of the discharge flow on both sides of the immersion nozzle 21 is different, the two moving devices 33 are used to adjust the level fluctuation. The position of the collision plate is moved to adjust the level fluctuation so that it is the same on both sides of the immersion nozzle and has an appropriate magnitude.

When lowering the first projecting plate 30 in order to weaken the discharge flow 23, the upper side of the discharge flow 23 will collide with the upper side of the hole 31 of the collision plate 30, so that the flow of molten steel reversed by the collision will come out near the scene. Since there is a strong possibility that this will occur and cause fluctuations in the hot water level, it is desirable to adjust by raising the collision plate.

In response to the output from the hot water level gauge, a control device is provided to control the moving distance of the collision plate moving device 33, and the magnitude of the fluctuation in the hot water level is measured by the hot water level gauge 40, and the magnitude of the fluctuation in the hot water level is determined to be appropriate. detects the difference between the two and inputs it to the control device of the collision plate moving device,
It is easy to use so-called feedback control to keep the difference within an allowable range.

〔Effect of the invention〕

According to the present invention, the above-described fluctuations in the hot water level can be detected by the hot water level gauge, and the strength of the two discharge streams from the immersion nozzle can be adjusted individually by the collision plate and the collision plate moving device. By controlling the fluctuation of the hot water level within an appropriate range, it is possible to prevent surface defects due to powder entrainment and breakouts due to remelting of the solidified shell.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the vicinity of a mold showing a hot water level fluctuation control device of the present invention, FIG. 2 is an enlarged front view of the collision plate according to the present invention shown in FIG. FIG. 3 is a vertical cross-sectional view showing the western style near the mold in the prior art. lO... Tanditshu, 15... Molten steel, 20.
... Mold 21 ... Immersion nozzle, 22 ... Discharge 0.2
3... Discharge flow 124... Hot water level, 25... Sliding nozzle. 30... Collision plate, 31... Hole opened in the collision plate. 32... Support rod, 33... Moving device 34... Immersion nozzle discharge port. Patent applicant Nippon Kokan Co., Ltd. Figure 1-2

Claims (1)

[Claims] A hot water level fluctuation control device used in a continuous slab casting device includes: a collision plate movable in a direction across a molten steel flow path from a discharge port of an immersion nozzle; a moving device for moving the collision plate; A hot water level fluctuation control device characterized by comprising a plurality of hot water level gauges that measure the magnitude of surface fluctuation.