KR101277701B1 - Device for controlling level of molten steel in mold and method therefor - Google Patents

Abstract

The present invention relates to an apparatus and method for controlling the level of water in a mold, comprising: first measuring means for measuring a level of water level on an immersion nozzle side of molten steel contained in a mold; Second measuring means positioned on the same horizontal axis as the first measuring means to measure the level of the hot water on the side of the short side of the mold; And a control unit for controlling the electromagnetic unit to stabilize the level of the water level by comparing the deviation of the level of the water level obtained by the first measuring means and the second measuring means with a set reference value.

Description

DEVICE FOR CONTROLLING LEVEL OF MOLTEN STEEL IN MOLD AND METHOD THEREFOR}

The present invention is directed to an apparatus and method for controlling the level of water surface in a mold to prevent defects such as falling off or cracking of coil edges generated in the slab.

In general, a continuous casting machine is a facility for producing cast steel of a certain size by receiving a molten steel produced in a steelmaking furnace and transferred to a ladle (Tundish) and then supplied to a continuous casting machine mold.

The continuous casting machine includes a ladle for storing molten steel, a playing mold for cooling the tundish and the molten steel discharged from the tundish for the first time to form a casting cast having a predetermined shape, and the casting cast formed in the mold connected to the mold. It includes a plurality of pinch rolls.

In other words, the molten steel tapping out of the ladle and tundish is formed as a cast piece having a predetermined width, thickness and shape in a mold and is transferred through a pinch roll, and the cast piece transferred through the pinch roll is cut by a cutter. It is made of slabs (Slab), Bloom (Bloom), Billet (Billet) and the like having a predetermined shape.

The present invention provides a surface level control apparatus and method in a mold for controlling the surface level to improve the quality of the slab by predicting the level of the slab due to the level fluctuation by measuring the level of the surface of the center and short sides of the surface.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular embodiments that are described. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, There will be.

In the mold according to the present invention for realizing the above object, the molten metal level control apparatus comprises: first measuring means for measuring the molten metal level of the immersion nozzle side of molten steel accommodated in the mold; Second measuring means positioned on the same horizontal axis as the first measuring means to measure the level of the hot water on the side of the short side of the mold; And a control unit for controlling the electromagnetic unit to stabilize the level of fluctuations by comparing the deviation of the level of the level obtained by the first and second measurement means with a reference value.

The second measuring means is preferably installed on the left and right of the immersion nozzle, respectively.

In addition, the controller controls the electromagnetic unit when edge defects are detected in the surface defect detection apparatus.

In addition, the second measuring means is to measure the level of the water level of the short side portion, respectively, it is preferable that the electromagnetic units on both sides are individually controlled in accordance with the deviation of the level.

Another embodiment of the present invention provides a method for controlling the level of a floor in a mold, the method comprising: calculating a level of a floor level by measuring a level of a floor level of a center surface and a short side of a mold; Comparing the deviation with a set reference value; And if the deviation is greater than the reference value, increasing the current of the electromagnetic unit to reduce the flow rate of the molten steel to lower the deviation.

If the deviation is less than the reference value, transferring the formed slab to a surface defect detection device to check whether edge edges are generated, and if edge defects occur, updating the reference deviation with an average value of the deviations and the reference value; It includes.

In addition, if the deviation is less than the reference value, by transmitting the formed slab to the surface defect detection device to check whether the edge defects occur, increasing the current of the electromagnetic unit to reduce the flow rate of the molten steel to reduce the deviation; includes; do.

As described above, the present invention can prevent the phenomenon that the slag lim (Slag Lim) fall into the molten steel by controlling the level of the hot water surface has the effect of reducing the turn edge defects that fall and crack the coil edge portion.

Therefore, the present invention has the effect of ultimately raising the quality of the slabs.

1 is a conceptual diagram illustrating a continuous casting machine mainly on the flow of molten steel according to an embodiment of the present invention.
FIG. 2 is a conceptual view illustrating a distribution form of molten steel in the mold of FIG. 1 and an adjacent portion thereof.
Figure 3 is a long side cross-sectional view showing the water level control apparatus in the mold according to an embodiment of the present invention.
Figure 4 is a short side cross-sectional view showing a water level control apparatus in the mold according to an embodiment of the present invention.
5 is a flowchart illustrating a method of controlling the level of water in the mold according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Like elements in the figures are denoted by the same reference numerals wherever possible. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a conceptual diagram illustrating a continuous casting machine mainly on the flow of molten steel according to an embodiment of the present invention.

Referring to this figure, the molten steel M flows into the tundish 20 while being accommodated in the ladle 10. For this flow, the ladle 10 is provided with a shroud nozzle 15 extending toward the tundish 20. The shroud nozzle 15 extends so as to be submerged in the molten steel in the tundish 20 so that the molten steel M is not exposed to the air and oxidized and nitrided. The case where the molten steel M is exposed to air due to breakage of the shroud nozzle 15 or the like is referred to as open casting.

The molten steel M in the tundish 20 is caused to flow into the mold 30 by the submerged entry nozzle 25 extending into the mold 30. The immersion nozzle 25 is disposed in the center of the mold 30 so that the flow of the molten steel M discharged from both discharge ports 25a of the immersion nozzle 25 can be symmetrical. The start, the discharge speed and the interruption of the discharge of the molten steel M through the immersion nozzle 25 are determined by a stopper 21 provided on the tundish 20 in correspondence with the immersion nozzle 25. Specifically, the stopper 21 can be vertically moved along the same line as that of the immersion nozzle 25 so as to open and close the inlet of the immersion nozzle 25. The control of the flow of the molten steel M through the immersion nozzle 25 may use a slide gate method different from the stopper method. The slide gate controls the discharge flow rate of the molten steel (M) through the immersion nozzle (25) while the plate material slides horizontally in the tundish (20).

Molten steel (M) in the mold (30) starts to solidify from a portion in contact with the wall surface of the mold (30). This is because the periphery of the molten steel M is liable to lose heat by the water-cooled mold 30. By the way that the periphery is first solidified, the back portion along the casting direction of the casting cast piece 80 forms a shape in which the unsolidified molten steel 82 is wrapped in the solidified shell 81.

The unsolidified molten steel 82 is moved together with the solidified shell 81 in the casting direction. The non-solidified molten steel (82) is cooled by the spraying means (65) for spraying the cooling water in the up-shifting process. This causes the thickness of the non-solidified molten steel (82) to gradually decrease in the cast steel (80). When the cast steel 80 reaches one point 85, the cast steel 80 is filled with the solidification shell 81 of the entire thickness. The solidification casting 80 having been solidified is cut to a predetermined size at the cutting point 91 and is divided into a slab P such as a slab or the like.

Cast steel (P) is made of a hot rolled coil, a thick plate, or the like as a final product through a rolling process. The thickness of the thin slabs produced through the playing process may be about 40 to 100mm, and the thickness of the coils produced through the rolling process may be about 1.5 to 20mm.

Hereinafter will be described as a thin slab in place of the cast.

Referring to FIG. 2, a pair of discharge ports 25a are typically formed on the end side of the immersion nozzle 25 on the left and right in the drawing. The shapes of the mold 30 and the immersion nozzle 25 are assumed to be symmetrical with respect to the center line C, and thus only the left side is shown in this drawing.

The molten steel M discharged together with the argon (Ar) gas from the discharge port 25a draws a trajectory flowing in the upward direction A1 and downward direction A2 as indicated by arrows A1 and A2. do.

The powder layer 51 is formed on the upper part of the mold 30 by powder supplied from a powder feeder (not shown). The powder layer 51 may include a layer existing in a form in which the powder is supplied and a layer sintered by the heat of the molten steel M (sintered layer is formed closer to the unsolidified molten steel 82). Below the powder layer 51, a slag layer or a liquid fluidized layer 52 formed by melting powder by molten steel M is present. The liquid fluidized bed 52 maintains the temperature of the molten steel M in the mold 30 and blocks the penetration of foreign matter. A portion of the powder layer 51 solidifies at the wall surface of the mold 30 to form the lubrication layer 53. The lubrication layer 53 functions to lubricate the solidified shell 81 so as not to stick to the mold 30.

The thickness of the solidification shell 81 becomes thicker as it progresses along the casting direction. The portion of the solidification shell 81 located in the mold 30 is thin, and an oscillation mark 87 may be formed by oscillation of the mold 30. The solidification shell 81 is supported by the support roll 60, the thickness thereof is thickened by the spray means 65 for spraying water. The solidification shell 81 may be thickened and a bulging region 88 may be formed in which a portion protrudes convexly.

As shown in FIGS. 3 and 4, in the mold level control apparatus in the mold according to the embodiment of the present invention, the first measuring means 110, the second measuring means 120a and 120b, and the electromagnetic units 130a and 130b are provided. ), The controller 140, and the surface defect detection means 150.

The first measuring means 110 measures the level of the immersion nozzle 25 side of the molten steel 82 of the molten steel accommodated in the mold 30.

At this time, the first measuring means 110 may be provided on both sides with respect to the immersion nozzle 25, but the level of fluctuation of the water level in the center is not largely different. desirable.

The second measuring means (120a, 120b) is located on the same horizontal axis as the first measuring means 110 to measure the water level at the end of the short side of the mold (30). In this case, since the trajectories of the molten steel M discharged to the short sides are different from each other, the second measuring means 120a and 120b are installed on the left and right sides of the immersion nozzle 2, respectively, and the water level of the short sides of the mold is respectively set. It is preferable to measure.

The molten steel M flows by the molten steel M discharged from the discharge port 25a of the immersion nozzle 25 formed in the direction of the short side, as shown in FIG. 2, and the discharge port 25a of the immersion nozzle 25. The variation of the center portion and the short side portion of the mold 30 occurs according to the discharge rate at which the molten steel M discharged to the discharged portion is discharged, and the deviation of the water level of the center portion and the short side portion of the mold 30 occurs.

The electromagnetic units 130a and 130b are located outside the long sides of the mold 30 and flow of the molten steel M using the hot water level measured by the first and second measuring means 110 and 120a and 120b. Adjust the speed.

That is, the larger the current of the electromagnetic units 130a and 130b, the smaller the flow rate discharged to the discharge port 25a, and the smaller the current, the higher the flow rate of the molten steel.

If the flow rate of the molten steel is faster, the fluctuation of the surface of the molten metal is large, and the variation of the surface of the molten steel becomes larger, and the variation of the surface of the molten steel becomes larger, so that the occurrence of cracks in the mold 30 increases.

The controller 140 controls the electromagnetic units 130a and 130b by comparing the deviation of the water level obtained by the first measuring means 110 and the second measuring means 120a and 120b with the set reference value. The electromagnetic units 130a and 130b on both sides are individually controlled in accordance with the level deviation.

The reference value can be obtained as an average of deviations or deviations at the time when no crack is generated in the slag. In this case, the reference value may be fixed within an appropriate range and may be updated by a feedback of the deviation.

The surface defect detecting unit 150 inspects the defect of the surface of the finally formed thin slab and feeds back the measured deviation and the reference value when the defect is detected.

As a result, the present invention can prevent the phenomenon of slag falling into the molten steel by controlling the level of the hot water, thereby improving the quality of the thin slab produced next.

4 is a flowchart illustrating a method for controlling the level of water in a mold according to an embodiment of the present invention, which will be described in detail with reference to the accompanying drawings.

First, using the first measuring means 110 and the second measuring means (120a, 120b) to measure the water level corresponding to each position (S10).

That is, the level of the water level is determined by measuring the level of the bottom surface of the center portion of the mold 30 having the first measuring means 110 and the short side portion of the mold having the second measuring means 120a and 120b.

At this time, it is preferable that the second measuring means 120a and 120b measure the water level on the left and right sides of the center portion.

Subsequently, the deviation of each of the water level is compared with the magnitude of the reference value (S20). At this time, the deviation of each water level can be derived as follows.

Equation 1

1st measurement-2a measurement | = Deviation of first water level

Here, the first measurement value represents the water level level measured by the first measuring means 110, and the second measurement value represents the water level level measured by the second measuring means 120a.

Equation 2

| First measured value-second measured value | = second deviation level

Here, the first measurement value represents the level of the water surface measured by the first measuring means 110, and the second measurement value represents the level of the water surface measured by the second measuring means 120b.

Subsequently, if the deviation of the water level is greater than the reference value, the current of the electromagnetic units 130a and 130b is increased to decrease the flow rate of the molten steel discharged through the immersion nozzle 25 (S30).

That is, if the deviation of the first water level is greater than the reference value, the flow rate of the molten steel on the second measuring means 120a side is controlled by the electromagnetic unit 130a. If the deviation of the second water level is greater than the reference value, the electromagnetic unit 130b. It is preferable to control the flow rate of the molten steel on the second measuring means (120b) side of the molten steel (M).

In addition, if the deviation of the water surface level is smaller than the reference value, the formed thin slab is transferred to the surface defect detection means 150 (S50) to check whether or not the occurrence of the edge defect (Torn Edge), if the edge defect occurs (S60) After the reference deviation is updated with the average value of the deviation and the reference value, the coil is wound (S40), or the formed thin slab is transferred to the surface defect detection device 150 to check whether edge edges are generated, and then edge defects are generated. The lower surface (S60) reduces the flow rate of the molten steel by increasing the current of the electromagnetic unit (130a, 130b) to lower the deviation and wind the coil (S40).

 In this way, the surface level of the slab can be stabilized to prevent the slag dropout, thereby improving the quality of the thin slab.

If the formed thin slab is transferred to the surface defect detection device 150 (S50) and no defect is generated on the surface of the thin slab, the thin slab winds up the coil and does not feed back the electromagnetic units 130a and 130b or the reference value.

The surface level control apparatus and method in such a mold is not limited to the configuration and operation of the embodiments described above. The above embodiments may be configured such that various modifications may be made by selectively combining all or part of the embodiments.

10: Ladle 15: Shroud nozzle
20: Tundish 25: Immersion Nozzle
25a: Discharge port 30: Mold
51: Powder layer 52: liquid flowing layer
53: Lubrication layer 60: Support roll
65: spray 80: playing cast
81: Solidification shell 82: Non-solidified molten steel
83: tip portion 85: solidified point
87: oscillation trace 88: bulging zone
90: Cutter 91: Cutting point
110: first measuring means 120a, 120b: second measuring means
130a, 130b: electric machine induction control unit 140: control unit
150: surface defect detection device

Claims (7)

First measuring means for measuring the level of the immersion nozzle side of the molten steel accommodated in the mold;
Second measuring means positioned on the same horizontal axis as the first measuring means to measure the level of the hot water on the side of the short side of the mold; And
And a control unit for controlling the electromagnetic unit to stabilize the level of fluctuations by comparing the deviation of the level of the level obtained by the first and second measurement means with a reference value.
The control unit,
If the deviation is greater than the reference value, the current of the electromagnetic unit is increased to decrease the flow rate of the molten steel to lower the deviation,
When the deviation is smaller than the reference value, the formed slab is transferred to a surface defect detection device to check whether or not to generate a torn edge, and if an edge defect occurs, updating the reference deviation with the average value of the deviation and the reference value.
Surface level control device in the mold.
The method according to claim 1,
The second measuring means is the level of the water level control apparatus in the mold, respectively installed on the left and right with respect to the immersion nozzle.
The method according to claim 1,
The controller is a level surface control device in the mold to control the electromagnetic unit, if the edge defect is detected by the surface defect detection device.
The method according to claim 1,
And the second measuring means measures the level of the bottom surface of the short side, respectively, and the surface level control device in the mold in which electromagnetic units on both sides are individually controlled in accordance with the deviation of the level of the level of water.
Calculating a deviation of the level of the level of the water by measuring the level of the level of the surface of the mold at the center and the short sides of the mold;
Comparing the deviation with a set reference value; And
If the deviation is greater than the reference value, the current of the electromagnetic unit is increased to decrease the flow rate of the molten steel to reduce the deviation. If the deviation is less than the reference value, the formed slab is transferred to the surface defect detection device to detect the edge defects. And a step of updating a reference deviation with an average value of the deviation and the reference value when an edge defect occurs after checking whether there is an occurrence.
delete The method according to claim 5,
If the deviation is less than the reference value, by transmitting the formed slab to the surface defect detection device to check whether the edge defects occur, increasing the current of the electromagnetic unit to reduce the flow rate of the molten steel to reduce the deviation; Method of controlling the level of water in the body.

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