Apparatus and method for controlling bending of slab

Abstract

A slab bending control device and method are disclosed. A slab bending control device according to one aspect of the present invention includes a plurality of capturing units for capturing an image of a slab within a strand in a continuous casting process, and a processor for distinguishing an upper region and a lower region in each slab image captured through the plurality of capturing units, and controlling the amount of cooling water sprayed onto the slab through a spray means based on the similarity between the upper region and the lower region.

Description

Technology Field

[0001] The present invention relates to a slab bending control device and method, and more specifically, to a slab bending control device and method that can control downward bending of a slab by controlling the amount of cooling water sprayed onto the slab based on the similarity between the upper region and the lower region of an image of a short side of a slab within a strand during a continuous casting process. Background Technology

[0003] Generally, a continuous casting machine is a facility that receives molten steel produced in a steelmaking furnace and transferred to a ladle into a tundish, and then supplies it to a mold for the continuous casting machine to produce a cast billet of a certain size.

[0004] A continuous casting machine includes a ladle for storing molten steel, a tundish, a mold for the continuous casting machine that first cools the molten steel discharged from the tundish to form a slab having a predetermined shape, and a plurality of pinch rolls connected to the mold to move the slab formed in the mold.

[0005] In other words, molten steel discharged from a ladle and a tundish is formed into a slab having a predetermined width, thickness, and shape in a mold and is conveyed through pinch rolls, and the slab conveyed through pinch rolls is cut by a cutter to be manufactured into a cast slab, bloom, billet, etc., having a predetermined shape.

[0006] A cooling water spray means is installed between the pinch rolls, and cooling water and air are sprayed onto the slab through the spray means to lower the temperature of the slab.

[0007] However, in the spray means mounted on the lower part of the horizontal segment of the strand, impurities generated during continuous casting fall downward due to gravity, causing nozzle clogging. Due to this nozzle clogging at the lower part of the horizontal segment, the lower surface of the slab is not reached by cooling water and is not cooled relatively compared to the upper surface of the slab, resulting in a temperature difference where the lower surface of the slab becomes hotter than the upper surface of the slab.

[0008] The temperature difference between the upper and lower surfaces of the slab causes a difference in shrinkage force between the upper and lower surfaces of the slab, and this results in a problem of downward bending where the slab bends downward.

[0009] The background technology of the present invention is disclosed in Korean Registered Patent Publication No. 10-1360510 (published on February 10, 2014, performance equipment and method of performance thereof). The problem to be solved

[0011] The present invention has been devised to improve the above-mentioned problems, and the objective of the present invention is to provide a slab bending control device and method that can control the downward bending of a slab by controlling the amount of cooling water sprayed onto the slab based on the similarity between the upper region and the lower region of the short side image of the slab within the strand during a continuous casting process.

[0012] The problems that the present invention aims to solve are not limited to the problem(s) mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0014] A slab bending control device according to one aspect of the present invention may include a plurality of capturing units for capturing images of slabs within a strand in a continuous casting process, and a processor for distinguishing an upper region and a lower region in each slab image captured through the plurality of capturing units, and controlling the amount of cooling water sprayed onto the slab through a spray means based on the similarity between the upper region and the lower region.

[0015] In the present invention, the strand is characterized by including a curvature section, a straightening section, and at least one horizontal section.

[0016] In the present invention, the slab image is characterized as being an image of a short side of a slab.

[0017] In the present invention, the imaging unit is characterized by capturing an image of the short side of the slab in each section of the strand.

[0018] In the present invention, the processor is characterized by classifying an area corresponding to a certain distance below the upper end of the slab short side image as an upper area, and an area corresponding to a certain distance above the lower end of the slab short side image as a lower area.

[0019] In the present invention, the processor calculates the similarity between the upper region and the lower region of the short side image of the slab of each section, compares the calculated similarity between the upper region and the lower region of the short side image of the slab of each section with a preset threshold range, and controls the amount of cooling water sprayed on the lower surface of the slab of each section according to the comparison result.

[0020] In the present invention, the processor is characterized by calculating the similarity between the upper region and the lower region of the slab short side image using Euclidean distance.

[0021] In the present invention, the processor is characterized by extracting the HSV (Hue Saturation Value) value of the upper region and the HSV value of the lower region, and calculating the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region.

[0022] In the present invention, the processor is characterized by increasing the amount of cooling water sprayed on the lower surface of the slab in the section where there is a section where the Euclidean distance exceeds the critical range.

[0023] In the present invention, the processor is characterized by increasing the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value when the section exceeding the threshold range is a horizontal section.

[0024] In the present invention, the processor is characterized by increasing the amount of cooling water sprayed on the lower surface of the slab in the section exceeding the threshold range by a certain ratio of a preset lower surface cooling water amount setting value when the section exceeding the threshold range is at least one of the curvature section and the correction section.

[0025] In the present invention, the processor is characterized by increasing the amount of cooling water sprayed onto the lower surface of the slab in the corresponding section by 50% compared to the lower surface cooling water amount setting value.

[0026] In the present invention, the processor determines whether the number of times the Euclidean distance of the horizontal section exceeds the threshold range is greater than a certain number of times when the section exceeding the threshold range is a horizontal section, and if it is greater than a certain number of times, performs quality tracking designation indicating that a problem may occur in the quality of the slab, and increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value.

[0027] A slab bending control method according to another aspect of the present invention comprises the steps of: a processor acquiring a slab image of each section through a plurality of imaging units installed in each section of a strand; and the processor distinguishing an upper region and a lower region in the slab image of each section and controlling the amount of cooling water sprayed onto the slab through a spray means based on the similarity between the upper region and the lower region.

[0028] In the present invention, the slab image is characterized as being an image of a short side of a slab.

[0029] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor classifies an area corresponding to a certain distance below the upper end of the slab short side image as an upper area, and an area corresponding to a certain distance above the lower end of the slab short side image as a lower area.

[0030] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor calculates the similarity between the upper region and the lower region of the image of the short side of the slab in each section, compares the calculated similarity between the upper region and the lower region of the image of the short side of the slab in each section with a preset threshold range, and controls the amount of cooling water sprayed on the lower surface of the slab in each section according to the comparison result.

[0031] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor calculates the similarity between the upper region and the lower region of the slab short side image using a Euclidean distance, wherein the processor extracts the HSV value of the upper region and the HSV value of the lower region, and calculates the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region.

[0032] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor increases the amount of cooling water sprayed on the lower surface of the slab in the section where there is a section where the Euclidean distance exceeds the critical range.

[0033] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value when the section exceeding the threshold range is a horizontal section.

[0034] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor increases the amount of cooling water sprayed on the lower surface of the slab in the section by a certain ratio of a preset lower surface cooling water amount setting value when the section exceeding the threshold range is at least one of the curvature section and the correction section.

[0035] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor determines whether the number of times the Euclidean distance of the horizontal section exceeds the threshold range is greater than a certain number of times when the section exceeding the threshold range is a horizontal section, and if it is greater than a certain number of times, performs quality tracking designation indicating that a problem may occur in the quality of the slab, and increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value.

[0036] The present invention is characterized in that, in the step of controlling the amount of cooling water, the processor increases the amount of cooling water sprayed on the lower surface of the slab of the horizontal section by a preset lower surface cooling water amount setting value when the number of times the Euclidean distance of the horizontal section exceeds a critical range is not greater than a certain number.

[0037] In addition to this, other methods for implementing the present invention, other systems, and computer programs for executing said methods may be further provided. Effects of the invention

[0039] According to the present invention, by controlling the amount of cooling water sprayed on the lower surface of the slab in each section based on the similarity between the upper and lower regions of the short-side images of the slab taken for each section of the strand during the continuous casting process, downward bending of the slab can be prevented, thereby improving the quality of the electrical steel sheet (product).

[0040] Meanwhile, the effects of the present invention are not limited to those mentioned above, and various effects may be included within the scope obvious to a person skilled in the art from the contents described below. Brief explanation of the drawing

[0042] FIG. 1 is a schematic diagram showing a continuous casting apparatus according to one embodiment of the present invention. FIG. 2 is a drawing for explaining a strand according to an embodiment of the present invention. FIG. 3 is an illustrative diagram for explaining the change in length of a slab according to a temperature change in one embodiment of the present invention. Figure 4 is a graph showing the change in volume per unit volume according to temperature of an electrical steel sheet according to one embodiment of the present invention. Figure 5 is a graph showing the shrinkage rate of electrical steel sheets by grade during cooling according to one embodiment of the present invention. FIG. 6 is a block diagram schematically showing the configuration of a slab bending control device according to one embodiment of the present invention. FIG. 7 is an illustrative diagram for explaining a short side portion of a slab according to one embodiment of the present invention. FIG. 8 is an illustrative diagram for explaining the installation location of a shooting unit according to one embodiment of the present invention. FIG. 9 is an illustrative diagram for explaining the upper and lower regions of a slab short side image according to one embodiment of the present invention. FIG. 10 is an illustrative diagram for explaining the color difference according to the temperature difference between the upper region and the lower region of a slab short side image according to one embodiment of the present invention. FIG. 11 is an illustrative diagram for explaining an HSV histogram according to the temperature difference of a short side of a slab according to one embodiment of the present invention. FIG. 12 is a graph for explaining the Euclidean distance between the upper and lower regions of an image of a slab short side according to one embodiment of the present invention and the temperature difference between the upper and lower temperatures of the slab short side. FIG. 13 is a graph illustrating the Euclidean distance and bending amount between the upper region and the lower region of a slab short side image according to one embodiment of the present invention. FIG. 14 is a flowchart illustrating a slab bending control method according to an embodiment of the present invention. FIG. 15 is a flowchart illustrating a slab bending control method according to another embodiment of the present invention. FIG. 16 is an illustrative diagram for explaining the relationship between Euclidean distance and increase in cooling water according to one embodiment of the present invention. FIG. 17 is a graph illustrating the amount of downward bending according to the Euclidean distance of each section of a strand according to one embodiment of the present invention. Specific details for implementing the invention

[0043] Hereinafter, a slab bending control device and method according to an embodiment of the present invention will be described with reference to the attached drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation.

[0044] Furthermore, the terms described below are defined in consideration of their functions within the present invention, and these may vary depending on the intent or practice of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0045] Additionally, the implementations described herein may be implemented, for example, as methods or processes, devices, software programs, data streams, or signals. Even if discussed only in the context of a single form of implementation (e.g., discussed only as a method), implementations of the discussed features may also be implemented in other forms (e.g., devices or programs). Devices may be implemented in appropriate hardware, software, and firmware, etc. Methods may be implemented in devices such as processors, which generally refer to processing devices including, for example, computers, microprocessors, integrated circuits, or programmable logic devices. Processors also include communication devices such as computers, cell phones, portable / personal digital assistants ("PDAs"), and other devices that facilitate the communication of information between end-users.

[0047] FIG. 1 is a schematic diagram showing a continuous casting apparatus according to an embodiment of the present invention, FIG. 2 is a diagram explaining a strand according to an embodiment of the present invention, FIG. 3 is an illustrative diagram explaining the change in length according to a temperature change of a slab according to an embodiment of the present invention, FIG. 4 is a graph showing the change in volume per unit volume according to the temperature of an electrical steel sheet according to an embodiment of the present invention, and FIG. 5 is a graph showing the shrinkage rate of an electrical steel sheet by grade when cooling according to an embodiment of the present invention.

[0048] Referring to FIG. 1, a continuous casting apparatus according to one embodiment of the present invention may include a ladle (10), a tundish (20), a mold (30), a secondary cooling bed (60 and 65), a pinch roll (not shown), and a cutter (not shown).

[0049] Ladles (10) are provided in pairs to alternately receive molten steel (M) and alternately supply it to the tundish (20). The molten steel (M) contained in the ladle (10) flows into the tundish (20) through a shroud nozzle (15) that extends toward the tundish (20). The shroud nozzle (15) is extended so as to be submerged in the molten steel (M) in the tundish (20) so that the molten steel (M) is not exposed to air and oxidized or nitrided. For reference, the case where the molten steel (M) is exposed to air due to damage to the shroud nozzle (15) is referred to as open casting.

[0050] The tundish (20) receives molten steel (M) from the ladle (10) and supplies the molten steel (M) to the mold (30). The tundish (20) controls the supply speed of the molten steel (M), distributes the molten steel (M) to the mold (30), stores the molten steel (M), and separates slag and non-metallic inclusions. The molten steel (M) contained in the tundish (20) flows through the mold (30) via a submerged entry nozzle (SEN) (25) that extends into the mold (30). The submerged entry nozzle (25) is positioned in the center of the mold (30) to ensure that the flow of molten steel (M) discharged from both discharge ports of the submerged entry nozzle (25) is symmetrical. The start, stop, and discharge speed of the molten steel (M) through the immersion nozzle (25) are determined by a stopper (21) installed in the tundish (20) corresponding to the immersion nozzle (25). The stopper (21) can be moved vertically along the same line as the immersion nozzle (25) to open and close the inlet of the immersion nozzle (25). Control of the flow of molten steel (M) through the immersion nozzle (25) may also be achieved using a slide gate method, which is different from the stopper method described above. The slide gate can control the discharge flow rate of the molten steel (M) through the immersion nozzle (25) as the plate slides horizontally within the tundish (20).

[0051] The mold (30) is typically made of water-cooled copper material and cools the molten steel (M) first. The mold (30) is structurally formed with a pair of facing faces that are open, forming a hollow portion that receives the molten steel (M). The degree of solidification of the molten steel (M) varies depending on the carbon content according to the steel type, the type of powder, the casting speed, etc. The molten steel (M) discharged into the mold (30) solidifies starting from the part in contact with the wall of the mold (30). This is because the periphery of the molten steel (M) loses heat due to the water-cooled mold (30) rather than the center. In this way, depending on the method in which the periphery of the molten steel (M) solidifies first, the rear part of the strand (80) along the casting direction forms a shape in which the unsolidified molten steel (82) is wrapped in a solidified shell (81) in which the molten steel (M) has solidified.

[0052] The mold (30) is reciprocated to prevent the molten steel from sticking to the walls of the mold. During reciprocating motion, a lubricant is used to reduce friction between the mold (30) and the strand (80) and to prevent burning. The lubricants include sprayed flat oil and mold powder added to the surface of the molten steel inside the mold (30). The mold powder is added to the molten steel inside the mold (30) to form slag, and performs the functions of lubricating the mold (30) and the strand (80), as well as preventing oxidation and nitriding of the molten steel inside the mold (30), maintaining heat, and absorbing non-metallic inclusions that rise to the surface of the molten metal.

[0053] The secondary cooling zone (60 and 65) further cools the molten steel that has been cooled first in the mold (30). The molten steel that has been cooled first is directly cooled by a spray means (65) that sprays water, while the solidification angle is maintained so as not to be deformed by the support roll (60). Solidification of the slab is mostly achieved by the secondary cooling.

[0054] The spray means (65) includes a plurality of nozzles arranged in a row in the width direction of the strand (80), and the plurality of nozzles spray a predetermined amount of cooling water in the width direction of the strand (80).

[0055] The spray means (65) is installed at the upper and lower ends of the strand (80), respectively, and the upper nozzle and the lower nozzle are installed such that their installation positions and spray angles have an arbitrary deviation from each other. The spray angle of each nozzle of the spray means (65) is set to approximately 110˚, and the spray angle of each nozzle is set to overlap with adjacent nozzles. In addition, the spray angle of each nozzle is set to a constant spray angle regardless of the width of the strand (80). The spray means (65) sprays cooling water in the width direction of the strand (80) to the left edge, the center, and the right edge, respectively, and the amount of sprayed from each nozzle may vary depending on the control.

[0056] The drawing device employs a multi-drive method using several sets of pinch rolls (70) to pull out the slab without it slipping. The pinch rolls (70) pull the solidified leading edge of the molten steel in the casting direction, thereby allowing the molten steel passing through the mold (30) to move continuously in the casting direction.

[0057] The strand (80) is supported by a support roll (60) so that the solidification angle does not change, and when the leading edge (83) of the strand (80) is pulled by a pinch roll, the unsolidified molten steel (82) moves in the casting direction together with the solidified shell (81). During the above movement process, the unsolidified molten steel (82) is cooled by a spray means (65) that sprays cooling water. This causes the thickness of the unsolidified molten steel (82) in the strand (80) to gradually decrease. When the strand (80) reaches a point (85), the entire thickness of the strand (80) is filled with the solidified shell (81). The strand (80) that has completed solidification is cut into a certain size at a cutting point (91) and divided into a casting (P) such as a slab.

[0058] A cutter (not shown) is formed to cut the continuously produced slabs into a uniform size. A gas torch or a hydraulic shearer may be used as the cutter (not shown).

[0059] A device including a support roll (60) and a pinch roll is called a strand (80), and the strand (80) has a curved section (Bow segment) formed as a curved surface when viewed from the side, a straight section (Straight segment) where the curved surface changes back to a straight line, and a horizontal section (Horizontal segment).

[0060] Accordingly, the slab discharged from the mold (30) is also deformed from a curved surface to a horizontal shape according to the curved portion and the straightening portion of the strand (80). Generally, the slab that moves between the mold and the cutter is also referred to as a strand (80), but in the present invention, segments (curved portion, straightening portion and horizontal portion) including the support roll (60) and the pinch roll are referred to as a strand (80).

[0061] The strand (80) may be composed of a bender, a curved segment, a straightened segment, and a horizontal segment as shown in FIG. 2.

[0062] In the spray means (65) mounted on the lower part of the horizontal segment in the strand (80), impurities generated during continuous casting fall downward due to gravity, causing nozzle clogging. As impurities such as dust accumulate on the lower part of the horizontal segment, adverse conditions occur for the spraying of cooling water.

[0063] Due to nozzle blockage at the bottom of the horizontal segment, the lower surface of the slab is not reached by cooling water and is not cooled relatively compared to the upper surface of the slab, resulting in a temperature difference where the lower surface of the slab becomes hotter than the upper surface of the slab.

[0064] When a slab that has an upper / lower temperature difference while held in the segment comes out of the segment, the upper roll that holds the shape is removed. In other words, the shape is fixed because the roll surrounds the slab inside the segment, but when the slab comes out of the segment and moves to the ROT (Run Out Table), the upper roll is removed.

[0065] When the slab comes out of the segment, there is no upper roll, so the upper surface of the slab is cooled by radiation and convection due to contact with the atmosphere, and the lower surface of the slab can be cooled by conduction due to contact with the lower roll (ROT roll) as well as radiation and convection due to contact with the atmosphere. As a result, the cooling rate of the lower surface of the slab can be faster than the cooling rate of the upper surface of the slab.

[0066] When a slab moves from a segment to a ROT, the cooling rate of the lower surface of the slab is faster than the cooling rate of the upper surface of the slab, and as a result, the shrinkage force of the lower surface of the slab becomes greater than the shrinkage force of the upper surface of the slab.

[0067] Due to the difference in shrinkage force between the upper and lower surfaces of the slab, the slab bends downward in an 'n-shaped' downward bending problem.

[0068] When a slab receives heat, there is a change in temperature, and due to this temperature change, there is a change in length. The change in length due to the temperature change can be defined as shown in Equation 1 below.

[0069] [Mathematical Formula 1]

[0070]

[0071] Here, is the change in length, is the coefficient of linear expansion, Lo is the initial length, can represent the amount of temperature change. The coefficient of linear expansion can be a predefined value.

[0072] Referring to mathematical equation 1, it can be seen that the change in length is proportional to the change in temperature.

[0073] For example, as shown in FIG. 3, when a slab with an upper surface temperature of 710°C and a lower surface temperature of 790°C moves to the ROT, the slab is cooled so that the upper surface temperature of the slab becomes 670°C and the lower surface temperature of the slab becomes 680°C.

[0074] The temperature change on the upper surface of the slab can be -40℃, and the temperature change on the lower surface of the slab can be -110℃. These temperature changes on the upper and lower surfaces of the slab can cause different changes in length as shown in Equation 1.

[0075] Since the change in length is proportional to the change in temperature, the change in length of the upper surface of the slab may be smaller than the change in length of the lower surface of the slab. Therefore, a slab like (a) in FIG. 3 can be bent downward as in (b).

[0076] If the slabs are of the same material and the temperature change at the top is smaller than the temperature change at the bottom, the change in length of the upper surface of the slab may be smaller than the change in length of the lower surface of the slab. Therefore, the slab may bend downward.

[0077] If downward bending occurs in the ROT (Run Out Table) section after cutting by the TCM (Torch Cutting Machine) to the extent that the slab gets stuck between the rolls, process delays occur due to the inability to move the slab, and in severe cases, problems such as reduced production volume due to the suspension of casting may arise. In this case, since operators manually cut the slab with a torch and remove it with a crane, the work becomes very dangerous.

[0078] In addition, since slabs that have undergone downward bending cannot be fed into hot rolling, a normal slab must be placed on top to flatten and correct the bending before feeding. During this process, stress is generated inside the slab, which poses a risk of additional slab defects or operational accidents during the hot rolling process.

[0079] In addition, electrical steel sheets susceptible to room temperature brittleness are at risk of breakage during crane transport and straightening of slabs that undergo bending.

[0080] Electrical steel sheets frequently experience downward bending due to slow casting speeds, single-rolling, and limitations on the number of continuous rolls. While attaching a large number of continuous rolls could resolve downward bending, electrical steel sheets actually exhibit more such bending because the number of continuous rolls is limited (e.g., 3, maximum 5). Since electrical steel sheets contain a large amount of alloying elements, they require extensive refining during steelmaking as ultra-low carbon steel. Furthermore, there are equipment limitations regarding the charging of alloying elements, and the number of continuous rolls may be restricted because a large number of continuous rolls can degrade product quality due to modification by mold powder mixed with oxides. Consequently, electrical steel sheets may experience significant downward bending when moving from the segment to the ROT.

[0081] When downward-bent electrical steel sheets enter the hot rolling process, the slab may split.

[0082] In other words, hot rolling facilities that receive downwardly bent slabs perform a straightening process, and during straightening, a heavy object must be placed on top of the slab to apply stress. Forcibly applying stress to the slab can cause problems such as the slab breaking due to the stress, which may lead to a deterioration in the quality of the electrical steel sheet. Since electrical steel sheets consist of ultra-low carbon steel with a large amount of alloying elements such as aluminum and silicon added, they are highly brittle at room temperature. Due to these properties of electrical steel sheets, problems such as the sheets breaking due to stress may occur during straightening or crane movement.

[0083] As such, electrical steel sheets are produced by adding a large amount of Si and Al alloys to the molten steel, and it can be seen that the volume change of the slab becomes greater depending on the amount of Si / Al alloy added.

[0084] By increasing the amount of Si / Al alloy added to the molten steel, electrical steel sheets can be classified into general, high-grade, and premium grades. In other words, as the grade changes from general to high-grade to premium, the amount of Si / Al alloy added to the molten steel increases. As the amount of Si / Al alloy added to the electrical steel sheet increases, the volume per unit weight increases.

[0085] As shown in Fig. 4, it can be seen that the highest quality electrical steel sheet exhibits a greater volume change with temperature changes.

[0086] In addition, as shown in Fig. 5, it can be seen that as the amount of Si / Al alloy added to the electrical steel sheet increases, the volume per unit weight increases, and the shrinkage rate due to slab cooling also increases.

[0087] Through this, it can be seen that the deformation caused by the temperature difference of the electrical steel slab is severe.

[0088] To solve this problem, it is necessary to control slab bending during continuous casting.

[0089] Bending of the slab during continuous casting occurs due to the temperature difference between the upper and lower surfaces of the slab within the strand (80). To predict the occurrence of bending of the slab, the temperature of the upper surface of the long side of the slab within the strand (80) and the temperature of the lower surface of the long side must be compared.

[0090] However, since the upper and lower surfaces of the slab are held by segment rolls during continuous casting, it is impossible to measure the upper and lower surface temperatures of the long side of the slab within the strand (80) during continuous casting. Additionally, since a person cannot enter the lower part of the strand (80) and even if a person enters the upper part of the strand (80), the gap is very narrow, it is impossible to measure the temperature using a thermal imaging camera or the like. As such, it is impossible to measure the upper and lower surface temperatures of the long side of the slab within the strand (80) during continuous casting.

[0091] Accordingly, the present invention aims to control downward bending of the slab by using a shooting unit (120) to capture a short-side image of the slab in real time, which can indirectly compare the temperatures of the upper and lower surfaces of the slab, and by controlling the amount of cooling water based on the similarity between the upper and lower regions of the short-side image of the slab.

[0093] FIG. 6 is a block diagram schematically showing the configuration of a slab bending control device according to an embodiment of the present invention; FIG. 7 is an illustrative diagram for explaining a short side of a slab according to an embodiment of the present invention; FIG. 8 is an illustrative diagram for explaining the installation location of a shooting unit according to an embodiment of the present invention; FIG. 9 is an illustrative diagram for explaining the upper region and the lower region of an image of a short side of a slab according to an embodiment of the present invention; FIG. 10 is an illustrative diagram for explaining the color difference according to the temperature difference between the upper region and the lower region of an image of a short side of a slab according to an embodiment of the present invention; FIG. 11 is an illustrative diagram for explaining the HSV histogram according to the temperature difference of a short side of a slab according to an embodiment of the present invention; FIG. 12 is a graph for explaining the Euclidean distance between the upper region and the lower region of an image of a short side of a slab according to an embodiment of the present invention and the temperature difference between the upper temperature and the lower temperature of the short side of the slab; FIG. 13 is a graph for explaining the Euclidean distance between the upper region and the lower region of an image of a short side of a slab and the amount of bending according to an embodiment of the present invention.

[0094] Referring to FIG. 6, a slab bending control device (100) according to one embodiment of the present invention includes a memory (110), a shooting unit (120), an output module (130), and a processor (140).

[0095] The memory (110) is configured to store data related to the operation of the slab bending control device (100). In particular, the memory (110) may store an application (program or applet) that controls the amount of cooling water sprayed onto the slab through the spray means (65) based on the similarity between the upper and lower regions of the short-side image of the slab, and the stored information may be selected by the processor (140) as needed. That is, the memory (110) stores various types of data generated during the execution of an operating system or an application (program or applet) for driving the slab bending control device (100). At this time, the memory (110) is a general term for a non-volatile storage device that continues to maintain stored information even when power is not supplied, and a volatile storage device that requires power to maintain stored information.

[0096] The output module (130) can output images of the slab short side captured in each section of the strand (80), the amount of cooling water in each section of the strand (80), etc., according to the control of the processor (140). Such an output device can be implemented, for example, as a TFT-LCD (thin film transistor-liquid crystal display) panel, an LED (light emitting diode) panel, an OLED (organic LED) panel, an AMOLED (active matrix OLED) panel, or a flexible panel.

[0097] The imaging unit (120) can capture an image of the short side of a slab within a strand (80) in a continuous casting process. Here, the slab may be a slab for electrical steel sheets. The short side of the slab may represent the thickness side in the longitudinal direction of the slab as shown in FIG. 7.

[0098] The shooting unit (120) can be installed at specific locations, such as the midpoint of each section, to photograph the short side of the slab in each section of the strand (80).

[0099] Generally, the strand (80) is composed of 11 sections (segments), and each section can be individually controlled, so that the amount of cooling water and air value can be adjusted for each section to cool the slab. In the embodiment of the present invention, the strand (80) is described as being composed of 5 sections (curvature section, straightening section, and 3 horizontal sections) that are judged to have the most influence among the 11 sections.

[0100] For example, the strand (80) may be composed of a curvature section (P1), a straightening section (P2), a first horizontal section (P3), a second horizontal section (P4), and a third horizontal section (P5), as shown in FIG. 8.

[0101] Accordingly, the imaging unit (120) can be installed in each of the curvature section (P1), the correction section (P2), the first horizontal section (P3), the second horizontal section (P4), and the third horizontal section (P5). That is, a curvature imaging unit (121) is installed in the curvature section (P1), and the curvature imaging unit (121) can capture an image of the short side of the slab within the curvature section. A correction imaging unit (122) is installed in the correction section (P2), and the correction imaging unit (122) can capture an image of the short side of the slab within the correction section. A first horizontal section imaging unit (123) is installed in the first horizontal section (P3), and the first horizontal section imaging unit (123) can capture an image of the short side of the slab within the first horizontal section. A second horizontal section shooting unit (124) is installed in the second horizontal section (P4), and the second horizontal section shooting unit (124) can capture an image of the short side of the slab within the second horizontal section. A third horizontal section shooting unit (125) is installed in the third horizontal section (P5), and the third horizontal section shooting unit (125) can capture an image of the short side of the slab within the third horizontal section.

[0102] This shooting unit (120) may include, for example, a camera.

[0103] The processor (140) can be operatively connected to the memory (110), the imaging unit (120), and the output module (130). The processor (140) can be implemented as a Central Processing Unit (CPU), a Digital Signal Processor (DSP), a Micro Controller Unit (MCU), or a System on Chip (SoC), and can control multiple hardware or software components connected to the processor (140) by running an operating system or application, perform various data processing and calculations, execute at least one command stored in the memory (110), and be configured to store the execution result data in the memory (110).

[0104] The processor (140) can distinguish between an upper region and a lower region in each slab image captured through a plurality of capturing units (120), and control the amount of cooling water sprayed onto the slab through a spray means (165) based on the similarity between the upper region and the lower region.

[0105] The operation of the processor (140) will be described in detail below.

[0106] The processor (140) can receive images of the slab short side within the corresponding section in real time from each shooting unit (120) installed in each section of the strand (80).

[0107] The processor (140) can receive an image of a slab short side within a curvature section from a curvature section capturing unit (121), receive an image of a slab short side within a correction section from a correction section capturing unit (122), receive an image of a slab short side within a first horizontal section from a first horizontal section capturing unit (123), receive an image of a slab short side within a second horizontal section from a second horizontal section capturing unit (124), and receive an image of a slab short side within a third horizontal section from a third horizontal section capturing unit (125).

[0108] The processor (140) can distinguish between an upper region and a lower region in the slab short side image of each section. Here, the upper region may refer to an area located a certain distance (e.g., 30 mm) below the upper end of the slab short side image, and the lower region may refer to an area located a certain distance (e.g., 30 mm) above the lower end of the slab short side image. For example, the processor (140) can distinguish between an upper region (B) and a lower region (C) in the slab short side image (A) as shown in FIG. 9.

[0109] When looking at the image (A) of the slab's short side captured by the capturing unit (120), if the temperature difference (e.g., 2°C) between the upper temperature of the short side and the lower temperature of the short side is small, the colors of the upper area (B) and the lower area (C) of the short side are similar as shown in FIG. 10 (a), and if the temperature difference (e.g., 34°C) between the upper temperature of the short side and the lower temperature of the short side is large, it can be seen that there is a difference in color between the upper area (B) and the lower area (C) of the short side as shown in FIG. 10 (b). That is, if the temperature difference between the upper part of the slab's short side and the lower part of the slab is large, it can be seen that there is a large difference in color between the upper part of the short side and the lower part of the short side. Through this, it can be seen that the color difference between the upper area (B) and the lower area (C) of the short side of the slab is proportional to the temperature difference between the upper temperature of the short side and the lower temperature of the short side.

[0110] Accordingly, the present invention aims to utilize the similarity between the upper and lower regions of a slab short side image without measuring the upper and lower temperatures of the short side. Here, similarity may refer to the similarity between the color of the upper region and the color of the lower region, and the color may include RGB, HSV (Hue Saturation Value), etc. Preferably, the present invention aims to utilize the similarity between the HSV value of the upper region and the HSV value of the lower region of a slab short side image.

[0111] The image of the slab's short side may be an RGB image composed of red, green, and blue. Since the slab in the strand (80) has a high temperature, the image of the slab's short side may consist mostly of red and may not include green and blue. That is, the RGB image often does not clearly show the difference between the upper and lower regions of the short side.

[0112] HSV is a color model that represents colors in computer graphics based on hue, saturation, and value, consisting of three components: hue, saturation, and value. Hue (h) is one of the three attributes of color, along with saturation (s) and value (v), referring to the distinguishing characteristic that allows chromatic colors such as red, yellow, green, blue, and purple to be classified by type. Hue values ​​range from 0° to 360°. Saturation (s) refers to the intensity or lightness of a hue. Saturation values ​​are higher the closer a color is to a primary color. In other words, pure colors have the highest saturation within the same hue. Meanwhile, white and black are called 'achromatic' because they lack saturation. Saturation values ​​range from 0% to 100%. Value (v) is the value that provides the impression of darkness or brightness in a hue. Values ​​range from 0% to 100%.

[0113] When comparing histogram similarity based on the HSV (Hue Saturation Value) color space of the upper and lower regions of the slab short-side image, it may be as shown in Fig. 11.

[0114] When the temperature difference (e.g., 2°C) between the upper temperature of the short side and the lower temperature of the short side is small, the HSV histogram of the upper region and the HSV histogram of the lower region of the slab short side image may be as shown in Fig. 11 (a). Looking at Fig. 11 (a), it can be seen that the HSV histogram of the upper region and the HSV histogram of the lower region of the slab short side image are similar.

[0115] When there is a large temperature difference (e.g., 34°C) between the upper temperature of the slab and the lower temperature of the slab, the HSV histogram of the upper region and the HSV histogram of the lower region of the slab slab image may be as shown in Fig. 11 (b). Looking at Fig. 11 (b), it can be seen that the HSV histogram of the upper region and the HSV histogram of the lower region of the slab slab image are different. That is, looking at the HSV histogram of the upper region of the slab slab image, it can be seen that Hue (H) appears more when the pixel value is low, while Saturation (S) and Brightness (V) appear when the pixel value is 130 to 210. Looking at the HSV histogram of the lower region of the slab slab image, it can be seen that Hue (H) appears more when the pixel value is high, while Saturation (S) and Brightness (V) appear when the pixel value is 180 or higher. Through this, it can be confirmed that when the temperature difference between the upper temperature of the short side and the lower temperature of the short side (e.g., 34℃) is large, the HSV histogram of the upper region of the short side and the HSV histogram of the lower region of the short side are different.

[0116] As such, when comparing histogram similarity based on the HSV color space of the upper region of the short side and the lower region of the short side, it can be seen that if the temperature difference between the upper temperature of the short side and the lower temperature of the short side is small, the HSV histogram of the upper region of the short side and the HSV histogram of the lower region of the short side are similar, and if the temperature difference between the upper temperature of the short side and the lower temperature of the short side is large, the HSV histogram of the upper region of the short side and the HSV histogram of the lower region of the short side are not similar.

[0117] Accordingly, the present invention aims to control the amount of cooling water sprayed onto the slab based on the similarity between the HSV value of the upper region and the HSV value of the lower region in the short side image of the slab.

[0118] To this end, the processor (140) can extract HSV values ​​for the upper region of the slab short side image and extract HSV values ​​for the lower region of the slab short side image. At this time, the processor (140) can extract HSV values ​​for each of the multiple pixels constituting the upper region of the short side and extract the average value of the extracted HSV values ​​as the HSV value of the upper region of the short side. The processor (140) can extract HSV values ​​for each of the multiple pixels constituting the lower region of the short side and extract the average value of the extracted HSV values ​​as the HSV value of the lower region of the short side.

[0119] When the HSV values ​​of the upper region of the short side and the lower region of the short side are extracted, the processor (140) can calculate the similarity between the HSV values ​​of the upper region of the short side and the HSV values ​​of the lower region of the short side. At this time, the processor (140) can calculate the similarity using various methods such as Euclidean distance, Manhattan distance, and Mahalanobis distance, but in this embodiment, it may be preferable to use Euclidean distance. For convenience of explanation, it will be described below that the similarity between the HSV values ​​of the upper region of the short side and the HSV values ​​of the lower region of the short side is calculated using Euclidean distance.

[0120] The processor (140) can calculate the similarity between the HSV value of the upper region of the short side and the HSV value of the lower region of the short side using Euclidean distance. That is, the processor (140) can calculate the Euclidean distance between the upper HSV of the short side and the lower HSV of the short side using the following mathematical formula 2.

[0121] [Mathematical Formula 2]

[0122]

[0123] Here, H1 may represent the H value of the upper region of the short side, H2 the H value of the lower region of the short side, S1 the S value of the upper region of the short side, S2 the S value of the lower region of the short side, V1 the V value of the upper region of the short side, and V2 the V value of the lower region of the short side.

[0124] The processor (140) can calculate the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within each section. That is, the processor (140) can calculate at least one of the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within the curvature section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within the correction section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within the first horizontal section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within the second horizontal section, and the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within the third horizontal section.

[0125] When the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image within each section is calculated, the processor (140) can compare the calculated Euclidean distance of the slab short side image within each section with a preset threshold range to determine whether there is a section that exceeds the threshold range. Here, the threshold range is a preset range, for example, 60 to 70.

[0126] If there is a section where the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image exceeds a critical range, the processor (140) can increase the amount of cooling water sprayed on the lower surface of the slab in that section.

[0127] If the section where the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short-side image exceeds the threshold range is a horizontal section, the processor (140) can increase the amount of cooling water sprayed on the lower surface of the slab in the corresponding horizontal section.

[0128] At this time, the processor (140) can increase the amount of cooling water sprayed on the lower surface of the slab in the horizontal section where the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image exceeds a threshold range by a preset lower surface cooling water amount setting value. That is, in the case of the horizontal section where the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image exceeds a threshold range, the processor (140) can increase the amount of cooling water sprayed on the lower surface by 100% compared to the lower surface cooling water amount setting value.

[0129] Since the continuous casting device sprays cooling water in the order of the curvature section, the straightening section, and the horizontal section, if the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image exceeds a critical range in the horizontal section where the amount of cooling water is relatively low, the amount of cooling water on the lower surface of the slab can be increased by 100% compared to the existing setting value for the amount of cooling water on the lower surface of the slab to reduce the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region. If the amount of cooling water on the lower surface is increased excessively, upward bending may occur instead of downward bending, so the amount of cooling water on the lower surface of the slab can be increased by 100% compared to the existing setting value for the amount of cooling water on the lower surface of the slab. Here, reducing the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region may mean reducing the temperature difference between the upper temperature of the short side and the lower temperature of the short side.

[0130] If the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image of at least one of the curvature section and the correction section exceeds a threshold range, the processor (140) can increase the amount of cooling water sprayed on the lower surface of the slab in the corresponding section by a certain ratio of a preset lower surface cooling water amount setting value. At this time, the processor (140) can increase the amount of cooling water by 50% compared to the existing lower surface cooling water amount setting value.

[0131] Since the continuous casting device sprays cooling water in the order of the curved section, the straightened section, and the horizontal section, if the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image exceeds a critical range in the curved section and the straightened section where more cooling water is sprayed, the amount of cooling water on the lower surface of the slab can be increased by 50% compared to the existing cooling water amount setting value to reduce the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region. If the amount of cooling water on the lower surface is increased excessively, upward bending may occur instead of downward bending, so the amount of cooling water on the lower surface of the slab can be increased by 50% compared to the existing cooling water amount setting value.

[0133] Meanwhile, the Euclidean distance between the HSV values ​​of the upper region and the lower region of the slab short side image, and the temperature difference between the upper and lower parts of the short side, can be measured as shown in Table 1 below. Here, the upper temperature of the slab short side may be a temperature value measured at a location corresponding to a certain distance (e.g., 30 mm) below the upper end of the slab short side, and the lower temperature of the slab short side may be a temperature value measured at a location corresponding to a certain distance (e.g., 30 mm) above the lower end of the slab short side.

[0134] [Table 1]

[0135]

[0136] Referring to Table 1, it can be seen that the greater the temperature difference between the upper and lower parts of the slab, the larger the Euclidean distance.

[0137] Through these experiments, the Euclidean distance (x) and the temperature difference between the upper and lower parts of the short side (y) can have a relationship as shown in Equation 3 below.

[0138] [Mathematical Formula 3]

[0139] y = 0.5356x - 2.4023

[0140] Equation 3 may be an equation generated using a regression model (regression equation). Equation 3 may be an equation derived from the fact that testing using Euclidean distance confirmed a correlation between Euclidean distance and temperature difference.

[0141] Figure 12 illustrates the Euclidean distance between the HSV of the upper region of the short side and the HSV of the lower region of the short side in Table 1, as well as the temperature difference between the upper and lower regions of the short side. Referring to Figure 12, it can be seen that slab downward bending did not occur when the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region of the slab short side image was in the range of 60 or more to 70 or less.

[0142] Accordingly, in the present invention, a critical range is set from 60 to 70, and it can be said that there is a high possibility of slab downward bending occurring when the Euclidean distance exceeds the critical range.

[0143] For example, we will explain the change in length (bending amount) according to the Euclidean distance when downward bending of a slab occurs.

[0144] When the upper temperature of the short side changes from 770℃ (last segment) to 730℃ (ROT) and the lower temperature of the short side changes from 862℃ (last segment) to 730℃ (ROT), the upper temperature deviation of the short side may be 40℃ and the lower temperature deviation of the short side may be 132℃. The coefficient of linear expansion is 12.3 x 10⁻⁶ -6 Assuming / ℃ and Lo (initial slab length) is 10,000 mm, applying this to Equation 1, the change in upper length is (12.3 x 10 -6 / ℃ * 10000mm * 40℃) = 4.92 mm, and the change in lower length is (12.3 x 10 -6 / ℃ * 10000mm * 132℃) = 16.24 mm. The bending amount (change in lower length / change in upper length) can be 3.3.

[0145] At this time, the temperature difference between the upper and lower temperatures of the short side of the last segment can be 92°C. By applying 92°C to Equation 3 to calculate the Euclidean distance between the HSV values ​​of the upper and lower regions of the slab short side image, the result can be 174.9. Since the Euclidean distance is 174.9, it exceeds the critical range, indicating that downward bending of the slab occurs.

[0146] Next, we will explain the change in length (bending amount) according to the Euclidean distance when downward bending of the slab does not occur.

[0147] If the upper temperature of the short side changes from 770℃ (last segment) to 730℃ (ROT) and the lower temperature of the short side changes from 801℃ (last segment) to 730℃ (ROT), the temperature deviation of the upper short side may be 40℃ and the temperature deviation of the lower short side may be 71℃. Applying this to Equation 1, the change in upper length is (12.3 x 10 -6 / ℃ * 10000mm * 40℃) = 4.92 mm, and the change in lower length is (12.3 x 10 -6 / ℃ * 10000mm * 71℃) = 8.733 mm. The bending amount (change in lower length / change in upper length) can be 1.775.

[0148] This refers to an ideal state, and there may be a risk of downward bending from the moment the bending amount, which represents the change in lower length / change in upper length, exceeds 1.775. It can be seen that downward bending does not occur when the bending amount is 1.775 or less.

[0149] At this time, the temperature difference between the upper and lower temperatures of the short side of the last segment may be 31℃. By applying 31℃ to Equation 3 to calculate the Euclidean distance between the HSV values ​​of the upper and lower regions of the slab short side image, the value may be 62.4. Since the Euclidean distance is 62.4, it exceeds the critical range, so slab downward bending does not occur.

[0150] The amount of downward bending according to the Euclidean distance prior to ROT may be as shown in Table 2 below.

[0151] [Table 2]

[0152]

[0153] Table 2 can be represented as a graph as in Figure 13. Referring to Table 2 and Figure 13, it can be seen that the amount of bending increases as the Euclidean distance increases. Additionally, it can be seen that if the amount of bending exceeds 1.775, there is a high probability that downward bending will occur.

[0155] FIG. 14 is a flowchart illustrating a slab bending control method according to an embodiment of the present invention.

[0156] Referring to FIG. 14, the processor (140) obtains an image of the slab short side of each section through each shooting unit (120) installed in each section of the strand (80) (S1402).

[0157] The processor (140) can acquire an image of the short side of the slab within the curvature section through the curvature section capturing unit (121), acquire an image of the short side of the slab within the correction section through the correction section capturing unit (122), acquire an image of the short side of the slab within the first horizontal section through the first horizontal section capturing unit (123), acquire an image of the short side of the slab within the second horizontal section through the second horizontal section capturing unit (124), and acquire an image of the short side of the slab within the third horizontal section through the third horizontal section capturing unit (125).

[0158] When step S1402 is performed, the processor (140) distinguishes between an upper region and a lower region in the slab short side image of each section (S1404). Here, the upper region may refer to an area corresponding to a certain distance (e.g., 30 mm) below the upper end of the slab short side image, and the lower region may refer to an area corresponding to a certain distance (e.g., 30 mm) above the lower end of the slab short side image.

[0159] When step S1404 is performed, the processor (140) extracts the HSV values ​​of the upper region and the lower region within the slab short side image of each section (S1406). At this time, the processor (140) can extract HSV values ​​for each of the multiple pixels constituting the upper region of the slab short side image and extract the average value of the extracted HSV values ​​as the HSV value of the upper region. The processor (140) can extract HSV values ​​for each of the multiple pixels constituting the lower region of the slab short side image and extract the average value of the extracted HSV values ​​as the HSV value of the lower region.

[0160] When step S1406 is performed, the processor (140) calculates the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of each section (S1408). That is, the processor (140) can calculate at least one of the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the curvature section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the correction section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the first horizontal section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the second horizontal section, and the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the third horizontal section.

[0161] When step S1408 is performed, the processor (140) compares the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of each section with a preset threshold range to determine whether there is a section that exceeds the threshold range (S1410).

[0162] If, as a result of the determination of step S1410, there exists a section where the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image exceeds a threshold range, the processor (140) determines whether the section where the Euclidean distance exceeds the threshold range is at least one of the curvature section and the correction section (S1412).

[0163] If, as a result of the judgment in step S1412, the section where the Euclidean distance exceeds the critical range is at least one of the curvature section and the correction section, the processor (140) increases the amount of cooling water sprayed on the lower surface of the slab in the corresponding section by 50% compared to the preset lower surface cooling water amount setting value (S1414).

[0164] Since the continuous casting device sprays cooling water in the order of the curved section, the straightened section, and the horizontal section, if the Euclidean distance between the upper and lower regions of the short side exceeds a critical range in the curved section and the straightened section where more cooling water is sprayed, the amount of cooling water on the underside of the slab can be increased by 50% compared to the existing setting value for the amount of cooling water on the underside to reduce the Euclidean distance (temperature difference) between the upper and lower regions of the short side. If the amount of cooling water on the underside is increased excessively, upward bending may occur instead of downward bending, so the amount of cooling water on the underside of the slab can be increased by 50% compared to the existing setting value for the amount of cooling water.

[0165] If, as a result of the judgment in step S1412, the section where the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image exceeds the threshold range is not a curvature section or a correction section, the processor (140) determines that the section where the Euclidean distance exceeds the threshold range is a horizontal section (S1416).

[0166] That is, the processor (140) determines the section that exceeds the threshold range among the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the image of the short side of the slab in the curvature section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the image of the short side of the slab in the correction section, and the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the image of the short side of the slab in the horizontal section. Therefore, if the section where the Euclidean distance exceeds the threshold range is not the curvature section or the correction section, it can be determined as the horizontal section.

[0167] When step S1416 is performed, the processor (140) increases the amount of cooling water sprayed onto the lower surface of the slab in the corresponding horizontal section by 100% compared to the preset amount of lower surface cooling water (S1418).

[0168] Since the continuous casting device sprays cooling water in the order of the curved section, the straightened section, and the horizontal section, in the horizontal section where the amount of cooling water is relatively low, if the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the image of the short side of the slab exceeds a critical ratio, the amount of cooling water on the lower surface of the slab can be increased by 100% compared to the existing setting value for the amount of cooling water on the lower surface to reduce the Euclidean distance (temperature difference) between the upper and lower parts of the short side. If the amount of cooling water on the lower surface is increased excessively, upward bending may occur instead of downward bending, so the amount of cooling water on the lower surface of the slab can be increased by 100% compared to the existing setting value for the amount of cooling water on the lower surface.

[0170] FIG. 15 is a flowchart illustrating a slab bending control method according to another embodiment of the present invention.

[0171] Referring to FIG. 15, the processor (140) obtains an image of the slab short side of each section through each shooting unit (120) installed in each section of the strand (80) (S1502).

[0172] When step S1502 is performed, the processor (140) distinguishes between the upper region of the short side and the lower region of the short side in the image of the short side of each section of the slab (S1304). Here, the upper region of the short side may refer to an area corresponding to a certain distance (e.g., 30 mm) below the upper end of the image of the short side of the slab, and the lower region of the short side may refer to an area corresponding to a certain distance (e.g., 30 mm) above the lower end of the image of the short side of the slab.

[0173] When step S1504 is performed, the processor (140) extracts the HSV values ​​of the upper region and the lower region within the slab short side image of each section (S1506).

[0174] When step S1506 is performed, the processor (140) calculates the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of each section (S1508). That is, the processor (140) can calculate at least one of the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the curvature section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the correction section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the first horizontal section, the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the second horizontal section, and the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region within the slab short side image of the third horizontal section.

[0175] When step S1508 is performed, the processor (140) compares the Euclidean distance of the slab short side image of each section with a preset threshold range and determines whether there is a section that exceeds the threshold range (S1510).

[0176] If, as a result of the judgment in step S1510, there exists a section where the Euclidean distance of the slab short side image exceeds a threshold range, the processor (140) determines whether the section where the Euclidean distance of the slab short side image exceeds the threshold range is at least one of the curvature section and the correction section (S1512).

[0177] If, as a result of the judgment in step S1512, the section where the Euclidean distance of the short side image of the slab exceeds the critical range is at least one of the curvature section and the correction section, the processor (140) increases the amount of cooling water sprayed on the lower surface of the slab in the corresponding section by 50% compared to the preset lower surface cooling water amount setting value (S1514).

[0178] If, as a result of the judgment in step S1512, the section where the Euclidean distance of the short side image of the slab exceeds the threshold range is not a curvature section or a correction section, the processor (140) determines that the section where the Euclidean distance of the short side image of the slab exceeds the threshold range is a horizontal section (S1516).

[0179] When step S1516 is performed, the processor (140) determines whether the number of times the Euclidean distance of the short side image of the slab in the corresponding horizontal section exceeds a threshold range is greater than or equal to a preset number of times (S1518).

[0180] If, as a result of the judgment in step S1518, the number of times the Euclidean distance of the short side image of the slab in the horizontal section exceeds a threshold range is greater than a certain number, the processor (140) performs a quality tracking designation indicating that a problem may occur in the quality of the slab (S1520). The quality tracking designation may indicate that there is a problem with the slab and that additional bending should be corrected.

[0181] After performing step S1520, the processor (140) increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section where the Euclidean distance of the short side image of the slab exceeds the critical range by 100% compared to the preset amount of lower surface cooling water (S1522).

[0182] If, as a result of the judgment in step S1518, the number of times the Euclidean distance of the short side of the slab in the horizontal section exceeds the threshold range is not greater than a certain number, the processor (140) performs step S1522.

[0184] FIG. 16 is an illustrative diagram for explaining the relationship between the Euclidean distance and the increase in cooling water according to an embodiment of the present invention. FIG. 16 (a) shows the Euclidean distance when the cooling water in each section within the strand (80) is not increased, and (b) shows the Euclidean distance when the cooling water in each section within the strand (80) is increased.

[0185] Comparing Figure 16 (a) and (b), it can be seen that the Euclidean distance is smaller when the amount of cooling water sprayed onto the underside of the slab is increased compared to when the amount of cooling water is not increased. This indicates that the upper region of the short side image of the slab and the lower region of the short side are similar, which may imply that the temperature difference between the upper and lower parts of the short side is small. Through this, it can be seen that increasing the amount of cooling water sprayed onto the underside of each section can prevent downward bending of the slab.

[0187] FIG. 17 is a graph illustrating the amount of downward bending according to the Euclidean distance of each section of a strand according to one embodiment of the present invention.

[0188] First, when the present invention is applied to the second horizontal section (P4) and the third horizontal section (P5), the Euclidean distance of the short side at the last segment may be 128.96. If the Euclidean distance is 128.96, a bending amount of 3.854 corresponding to 128.96 can be obtained from a pre-set table (e.g., Table 2). Through this, when the present invention is applied to the second horizontal section (P4) and the third horizontal section (P5), the bending amount (change in lower length / change in upper length) may be -3.854. Here, '-' may indicate downward bending.

[0189] Next, when the present invention is applied to the third horizontal section (P5), the Euclidean distance of the short side at the last segment may be 163. If the Euclidean distance is 163, a bending amount of 4.01 corresponding to 163 can be obtained from a pre-set table (e.g., Table 2). Through this, when the present invention is applied to the third horizontal section (P5), the bending amount (change in lower length / change in upper length) may be -4.01.

[0190] Next, when the present invention is applied to the straightening section (P2), the first horizontal section (P3), the second horizontal section (P4), and the third horizontal section (P5), the Euclidean distance of the short side at the last segment may be 76. If the Euclidean distance is 76, a bending amount of 2.134 corresponding to 76 can be obtained from a pre-set table (e.g., Table 2). Through this, when the present invention is applied to the straightening section (P2), the first horizontal section (P3), the second horizontal section (P4), and the third horizontal section (P5), the bending amount (change in lower length / change in upper length) may be -2.134.

[0191] Finally, when the present invention is applied to the curvature section (P1), the straightening section (P2), the first horizontal section (P3), the second horizontal section (P4), and the third horizontal section (P5), the Euclidean distance of the short side in the last segment may be 43. If the Euclidean distance is 43, a bending amount of 1.735 corresponding to 43 can be obtained from a pre-set table (e.g., Table 2). Through this, when the present invention is applied to the curvature section (P1), the straightening section (P2), the first horizontal section (P3), the second horizontal section (P4), and the third horizontal section (P5), the bending amount (change in lower length / change in upper length) may be -1.735.

[0192] When the present invention is applied to the curvature section (P1), the correction section (P2), the first horizontal section (P3), the second horizontal section (P4), and the third horizontal section (P5), the bending amount is -1.25, and since this is less than or equal to the reference bending amount of -1.777, it can be seen that downward bending does not occur.

[0194] As described above, according to the present embodiment, by controlling the amount of cooling water sprayed on the lower surface of the slab in each section based on the similarity between the upper and lower regions of the short-side images of the slab taken for each section of the strand during the continuous casting process, downward bending of the slab can be prevented, and thereby the quality of the electrical steel sheet (product) can be improved.

[0195] Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom.

[0196] Therefore, the true technical scope of protection of the present invention should be determined by the claims below. Explanation of the symbols

[0198] 10 : Radle 20 : Tundish 30 : Mold 60 : Support Roll 65 : Spray means 80 : Strand 100 : Slab bending control device 110 : Memory 120 : Filming Department 130 : Output module 140 : Processor

Claims

Claim 1 A slab bending control device comprising: a plurality of capturing units for capturing images of the short side of a slab within a strand in a continuous casting process; and a processor for distinguishing an upper region and a lower region in each slab short side image captured through the plurality of capturing units, calculating a similarity between the color value of the upper region and the color value of the lower region of the slab short side image, and controlling the amount of cooling water sprayed onto the slab through a spray means based on the similarity. Claim 2 A slab bending control device according to claim 1, characterized in that the strand comprises a curvature section, a straightening section, and at least one horizontal section. Claim 3 delete Claim 4 A slab bending control device according to paragraph 2, wherein the imaging unit captures an image of the short side of the slab in each section of the strand. Claim 5 A slab bending control device according to claim 4, wherein the processor classifies an area corresponding to a certain distance below the upper end of the slab short side image as an upper area, and an area corresponding to a certain distance above the lower end of the slab short side image as a lower area. Claim 6 A slab bending control device according to claim 5, wherein the processor calculates the similarity between the color value of the upper region and the color value of the lower region of the slab short side image of each section, compares the calculated similarity between the color value of the upper region and the color value of the lower region of the slab short side image of each section with a preset threshold range, and controls the amount of cooling water sprayed on the lower surface of the slab of each section according to the comparison result. Claim 7 A slab bending control device according to claim 6, wherein the processor calculates the similarity between the color value of the upper region and the color value of the lower region of the slab short side image using Euclidean distance. Claim 8 A slab bending control device according to claim 7, wherein the processor extracts the HSV (Hue Saturation Value) value of the upper region and the HSV value of the lower region, and calculates the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region. Claim 9 A slab bending control device according to claim 8, wherein the processor increases the amount of cooling water sprayed on the lower surface of the slab in the section where there exists a section where the Euclidean distance exceeds the critical range. Claim 10 A slab bending control device according to claim 9, wherein the processor increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value when the section exceeding the threshold range is a horizontal section. Claim 11 A slab bending control device according to claim 9, wherein the processor increases the amount of cooling water sprayed on the lower surface of the slab in the said section by a certain ratio of a preset lower surface cooling water amount setting value when the section exceeding the threshold range is at least one of the curvature section and the correction section. Claim 12 A slab bending control device according to claim 11, wherein the processor increases the amount of cooling water sprayed onto the lower surface of the slab in the corresponding section by 50% compared to the lower surface cooling water amount setting value. Claim 13 A slab bending control device according to claim 9, wherein the processor determines whether the number of times the Euclidean distance of the horizontal section exceeds the threshold range is greater than a certain number of times when the section exceeding the threshold range is a horizontal section, and if it is greater than the certain number of times, performs quality tracking designation indicating that a problem may occur in the quality of the slab, and increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value. Claim 14 A slab bending control method comprising: a step in which a processor acquires an image of a slab short side of each section through a plurality of imaging units installed in each section of a strand; and a step in which the processor distinguishes an upper region and a lower region in each slab short side image, calculates a similarity between the color value of the upper region and the color value of the lower region of the slab short side image, and controls the amount of cooling water sprayed onto the slab through a spray means based on the calculated similarity. Claim 15 delete Claim 16 A slab bending control method according to claim 14, wherein, in the step of controlling the amount of cooling water, the processor classifies an area corresponding to a certain distance below the upper end of the slab short side image as an upper area, and an area corresponding to a certain distance above the lower end of the slab short side image as a lower area. Claim 17 A slab bending control method according to claim 16, wherein, in the step of controlling the amount of cooling water, the processor calculates the similarity between the color value of the upper region and the color value of the lower region of the image of the short side of the slab in each section, compares the calculated similarity between the color value of the upper region and the color value of the lower region of the image of the short side of the slab in each section with a preset threshold range, and controls the amount of cooling water sprayed on the lower surface of the slab in each section according to the comparison result. Claim 18 A slab bending control method according to claim 17, wherein, in the step of controlling the amount of cooling water, the processor calculates the similarity between the color value of the upper region and the color value of the lower region of the slab short side image using a Euclidean distance, wherein the processor extracts the HSV value of the upper region and the HSV value of the lower region, and calculates the Euclidean distance between the HSV value of the upper region and the HSV value of the lower region. Claim 19 A slab bending control method according to claim 18, wherein, in the step of controlling the amount of cooling water, the processor increases the amount of cooling water sprayed on the lower surface of the slab in the section where there exists a section where the Euclidean distance exceeds the critical range. Claim 20 A slab bending control method according to claim 19, wherein, in the step of controlling the amount of cooling water, the processor increases the amount of cooling water sprayed on the lower surface of the slab in the horizontal section by a preset lower surface cooling water amount setting value when the section exceeding the threshold range is a horizontal section, and increases the amount of cooling water sprayed on the lower surface of the slab in the section by a certain ratio of the preset lower surface cooling water amount setting value when the section exceeding the threshold range is at least one of a curved section and a straightened section.

Images