STEEL PLATE BENDING MEASUREMENT EQUIPMENT, STEEL PLATE BENDING MEASUREMENT METHODS, HOT ROLLING EQUIPMENT FOR HOT-ROLLED STEEL STRIPS AND HOT ROLLING METHODS FOR HOT-ROLLED STEEL STRIPS

Abstract

The invention relates to a steel plate bending measuring device capable of accurately measuring the bending of a steel plate during rolling, a method for measuring the bending of a steel plate during rolling, a hot rolling device, and a hot rolling method. The bending arithmetic calculation device (6) of the bending measuring device (4) calculates the bending of a steel plate (10) using the driving edge position zds(N) and the operating edge position zws(N) at the present time when the measurement reliability determiner (64) determines that both the driving edge position zds(N) and the operating edge positions zws(N) at the present time are highly reliable. When only one of the driving edge position zds(N) and operating edge position zws(N) at the current time is determined to be highly reliable, the other edge position is calculated by interpolation using the number of pixels W from the plate width updater (65) with the operating edge position zds(N) or operating edge position zws(N) at the current time being highly reliable as a reference.

Description

Apparatus for measuring the amount of meandering of a steel plate, method for measuring the amount of meandering of a steel plate, hot rolling equipment for hot-rolled steel strip, and method for hot-rolling a hot-rolled steel strip

[0001] The present invention relates to a steel plate meandering amount measuring device that measures the meandering amount of a steel plate during rolling by a rolling mill having a plurality of rolling stands, a steel plate meandering amount measuring method, hot rolling equipment for hot-rolled steel strips, and a hot rolling method for hot-rolled steel strips.

[0002] Generally, during the rolling of steel sheets using a hot finishing mill with multiple rolling stands, a phenomenon called "snaking" can occur, in which the width center of the steel sheet is rolled out of alignment with the center of the work rolls of the rolling stands. If the amount of meandering of the steel sheet becomes too great, the steel sheet may come into contact with the side guides installed on the entry side of the rolling mill and buckle. If the steel sheet is rolled in this state, it can cause a roll breakage problem called "squeezing." Therefore, in steel sheet rolling operations, it is necessary to appropriately set the rolling conditions and control the amount of meandering of the steel sheet as small as possible.

[0003] Conventionally, two known methods for controlling the meandering amount of a steel sheet are "differential load type meandering control" and "sensor type meandering control." "Differential load type meandering control" changes the leveling amount of a rolling mill stand to be controlled (the roll gap difference, which is the difference in the roll gap gap between the operating side and the driving side in the rolling stand to be controlled) so that it is proportional to the differential load between the operating side and the driving side detected by a load detector provided in the rolling stand. "Sensor type meandering control" changes the leveling amount of a rolling mill stand to be controlled so that it is proportional to the meandering amount measured by a meander amount measuring device installed between the rolling stand immediately preceding the rolling stand to be controlled and the rolling stand to be controlled.

[0004] Conventionally, Non-Patent Document 1 points out that "differential load type meandering control" is not an effective control method because the wider the strip width, the smaller the effect of suppressing meandering within a practical control gain setting range. To solve this problem, a control system is proposed that employs "meandering control using a meandering meter type," in which the amount of meandering between the rolling stand immediately preceding the rolling stand to be controlled and the rolling stand to be controlled is periodically measured by a meandering amount measuring device, and the amount of leveling of the rolling mill stand to be controlled is adjusted.

[0005] However, a large amount of steam and fumes are generated between rolling stands in a hot finishing mill, and these steam and fumes obstruct the measurement field of view of a camera in a meandering amount measuring device, making it impossible to accurately measure the meandering amount of the steel sheet. To solve this problem, the above-mentioned Non-Patent Document 1 has conventionally proposed a method in which the point (corresponding to the edge of the steel sheet) at which the differential intensity is maximum is calculated for each scanning line of the camera, and then the edge line is estimated by a weighted least squares method using the differential intensity as a weight.

[0006] Furthermore, in order to solve the above-mentioned problems, a method for measuring the meandering of a plate material has been proposed in the past, as shown in Patent Document 1. The method for measuring the meandering of a plate material shown in Patent Document 1 includes the steps of: capturing an image of the surface of the plate material by a two-dimensional imaging device from a direction inclined in the rolling direction with respect to a perpendicular line of the pass line; detecting an edge position of the plate material for each scanning line by detecting a change in density value for each scanning line in the plate width direction in the captured image; calculating an approximate straight line by applying the least squares method to each edge position detected for each scanning line; calculating the position of an intersection between the approximate straight line and a predetermined scanning line; and calculating the amount of meandering based on the position of the intersection.

[0007] To solve the above-mentioned problems, an edge detection method disclosed in Patent Document 2 has also been proposed. The edge detection method disclosed in Patent Document 2 includes an imaging step of capturing multiple images of an area including an edge line of a traveling member using an imaging device, a differential image generating step of generating a differential image by calculating the differential intensity of pixels in each of the multiple temporally consecutive images obtained in the imaging step, and a composite differential image generating step of synthesizing the multiple temporally consecutive differential images obtained in the differential image generating step to generate a composite partial image. The edge detection method also includes a line identifying step of identifying a line in the composite differential image obtained in the composite differential image generating step that maximizes the sum of differential intensities of pixels existing on the line, and a determination step of determining whether the differential intensity of the pixel is greater than a threshold value.

[0008] Development of Steel Plate Snake Movement Control Technology in Hot Strip Rolling, Tetsu-to-Hagané, Vol. 95 (2009), No. 1, pp. 43-50

[0009] Japanese Patent Application Publication No. 2004-141956 Patent No. 5454404

[0010] However, a large amount of steam and fumes are generated between rolling stands in a hot finishing mill, and there are cases where only one edge of a steel sheet is covered by the steam or fumes and cannot be detected, while the other edge is not covered by the steam or fumes and can be detected. Here, in all of the conventional methods, the plate material meandering measurement method disclosed in Non-Patent Document 1 and Patent Document 1, and the edge detection method disclosed in Patent Document 2, the amount of meandering is calculated only when both edges of the steel sheet can be detected, and therefore there is a problem that the amount of meandering of the steel sheet cannot be detected when one edge cannot be detected but the other edge can be detected.

[0011] Therefore, the present invention has been made to solve the conventional problems, and an object of the present invention is to provide a device for measuring the meandering amount of a steel plate, a method for measuring the meandering amount of a steel plate, hot rolling equipment for hot rolled steel strips, and a hot rolling method for hot rolled steel strips that are capable of accurately measuring the meandering amount of a steel plate not only when both edges of the steel plate can be detected, but also when one edge of the steel plate is covered with steam or the like and therefore cannot be detected, and the other edge is not covered with steam or the like and therefore can be detected.

[0012] In order to solve the above-mentioned problems, a meandering amount measuring device for a steel sheet according to one aspect of the present invention is a device for measuring the meandering amount of a steel sheet during rolling by a rolling mill having a plurality of rolling stands, and includes an imaging device that is installed between adjacent rolling stands and periodically images the surface of the steel sheet traveling during rolling, and a meandering amount calculation device that calculates the meandering amount of the steel sheet based on a plurality of images taken by the imaging device, and the meandering amount calculation device calculates a brightness difference between adjacent images in the width direction of each of the plurality of images taken periodically by the imaging device, and determines a location where the absolute value of the brightness difference is maximum on the drive side in the width direction of the steel sheet as a drive side edge location z of the steel sheet. ｄｓ and the location where the absolute value of the brightness difference is maximum on the work side in the width direction of the steel plate is determined as the work side edge location z ｗｓ a pre-correction edge detection unit that detects a plurality of drive side edge locations z ｄｓ and work side edge location z ｗｓ The past N drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... N), the sum α of the absolute values ​​of the change amounts shown in the following equations (1) and (2) ｄｓ , α ｗｓ If each of these is equal to or greater than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ(N) is determined to be unreliable, and if it is less than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ a measurement reliability determination unit that determines that the drive side edge location z (N) is highly reliable; ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ The number of pixels W' corresponding to the plate width calculated from both (N) is calculated, and the number of pixels W corresponding to the plate width is updated to this calculated W'. ｄｓ (N) and work side edge location z ｗｓ When it is determined that at least one of (N) is unreliable, a plate width update unit keeps the number of pixels W corresponding to the plate width as this number of pixels W, and a measurement reliability determination unit determines the drive side edge position z at the current time. ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is used to calculate the amount of meandering of the steel plate, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ If only one of the two is determined to be highly reliable, the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ (N) as a reference, the edge location on the other side is interpolated using the number of pixels W from the plate width update unit, and the highly reliable current drive side edge location z ｄｓ (N) or work side edge location z ｗｓ (N) and the edge location on the other side calculated by interpolation are used to calculate the amount of meandering of the steel plate, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ(N) is determined to be unreliable, the meandering amount calculation unit does not calculate the meandering amount of the steel sheet.

[0013]

[0014]

[0015] A hot rolling facility for hot rolled steel strips according to another aspect of the present invention is characterized in that it includes the above-mentioned device for measuring the amount of meandering of a steel plate.

[0016] Further, a method for measuring the meandering amount of a steel sheet according to another aspect of the present invention is a method for measuring the meandering amount of a steel sheet during rolling by a rolling mill having a plurality of rolling stands, the method comprising: an imaging step of periodically imaging the surface of the steel sheet traveling during rolling by an imaging device installed between adjacent rolling stands; calculating a brightness difference between adjacent images in the width direction of each of the plurality of images periodically imaged in the imaging step; and determining a location where the absolute value of the brightness difference is maximum on the drive side in the width direction of the steel sheet as a drive side edge location z of the steel sheet. ｄｓ and the location where the absolute value of the brightness difference is maximum on the work side in the width direction of the steel plate is determined as the work side edge location z ｗｓ a pre-correction edge detection step for detecting a plurality of drive side edge locations z ｄｓ and work side edge location z ｗｓ The past N drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... N) The sum α of the absolute values ​​of the change amounts shown in the above equations (1) and (2) ｄｓ , α ｗｓ If each of these is equal to or greater than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓa measurement reliability determination step of determining that (N) is highly reliable; and ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ The number of pixels W' corresponding to the plate width calculated from both (N) is calculated, and the number of pixels W corresponding to the plate width is updated to this calculated W'. ｄｓ (N) and work side edge location z ｗｓ When it is determined that at least one of (N) is unreliable, a plate width updating step is performed in which the number of pixels W corresponding to the plate width is left as this number of pixels W; and in the measurement reliability determination step, the drive side edge position z ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is used to calculate the amount of meandering of the steel plate, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ If only one of the two is determined to be highly reliable, the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ Using (N) as a reference, the edge location on the other side is interpolated using the number of pixels W from the plate width update step, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ (N) and the edge location on the other side calculated by interpolation are used to calculate the amount of meandering of the steel plate, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is determined to be unreliable, the method further comprising the step of not calculating the amount of meandering of the steel sheet.

[0017] Furthermore, a hot rolling method for hot-rolled steel strip according to another aspect of the present invention is summarized as including a step of measuring the meandering amount of a steel sheet during rolling using a rolling mill having a plurality of rolling stands by the above-mentioned method for measuring the meandering amount of a steel sheet.

[0018] According to the device for measuring the amount of meandering of a steel plate, the method for measuring the amount of meandering of a steel plate, the hot rolling facility for a hot rolled steel strip, and the hot rolling method for a hot rolled steel strip of the present invention, it is possible to provide a device for measuring the amount of meandering of a steel plate, the method for measuring the amount of meandering of a steel plate, the hot rolling facility for a hot rolled steel strip, and the hot rolling method for a hot rolled steel strip that can accurately measure the amount of meandering of a steel plate not only when both edges of the steel plate can be detected when measuring the amount of meandering of a steel plate during rolling, but also when one edge of the steel plate is covered with steam or the like and therefore cannot be detected, and the other edge is not covered with steam or the like and therefore can be detected.

[0019] 7 is a schematic configuration diagram of a hot rolling facility equipped with a meandering amount measurement device according to an embodiment of the present invention. FIG. 1 is a functional block diagram of a meandering amount calculation device constituting the meandering amount measurement device shown in FIG. 1. FIG. 2 is a flowchart showing the flow of processing by the meandering amount measurement device shown in FIG. 1. FIG. 3 is a diagram for explaining an image captured by a line sensor camera as an imaging device for the meandering amount measurement device shown in FIG. 1. FIG. 4 is a diagram for explaining detection of drive side edge locations and work side edge locations of a steel sheet in an environment without steam or fumes. FIG. 5 is a diagram for explaining detection of drive side edge locations and work side edge locations of a steel sheet in an environment with steam or fumes. FIG. 6 is a diagram showing a two-dimensional image obtained by connecting a plurality of captured images periodically captured by a line sensor camera along the longitudinal direction of the steel sheet in an example of the present invention and a comparative example. FIG. 7 is a diagram showing a state in which the brightness difference between adjacent pixels in the width direction of the steel sheet is calculated from the state shown in FIG. 7, and the locations where the absolute value of the brightness difference is maximum are detected as the drive side edge locations and work side edge locations of the steel sheet in an example of the present invention and a comparative example. 1 is an explanatory diagram showing a case where the drive side edge portion and work side edge portion of a steel plate are estimated by a comparative example, and the amount of meandering of the steel plate is calculated using the estimated drive side edge portion and work side edge portion, where (a) shows the estimated value of the work side edge portion, (b) shows the estimated value of the drive side edge portion, and (c) shows the calculated value of the amount of meandering of the steel plate. 1 is an explanatory diagram showing a case where the drive side edge portion and work side edge portion of a steel plate are detected and judged by an example of the present invention, and the amount of meandering of the steel plate is calculated using the judged drive side edge portion and work side edge portion, where (a) shows the judged value of the work side edge portion, (b) shows the judged value of the drive side edge portion, and (c) shows the calculated value of the amount of meandering of the steel plate. 1 is a graph showing a comparison of the calculated values ​​of the amount of meandering of the steel plate calculated by an example of the present invention and a comparative example.

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below are examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention is not limited to the materials, shapes, structures, arrangements, etc. of the components in the embodiments described below. Furthermore, the drawings are schematic. Therefore, it should be noted that the relationships and ratios between thicknesses and planar dimensions may differ from the actual ones, and the drawings may also contain portions where the relationships and ratios of dimensions differ from one another.

[0021] 1 shows a schematic configuration of a hot rolling facility equipped with a meandering amount measuring device according to one embodiment of the present invention. In a hot rolling facility 1 for hot-rolled steel strips, a slab heated in a heating furnace (not shown) undergoes a roughing rolling process, a finish rolling process, and a cooling process to produce a steel plate of a predetermined width and thickness, which is then coiled. That is, the hot rolling facility 1 includes a heating furnace, a roughing mill (not shown), a finishing mill 2 (see FIG. 1), a cooling facility (not shown), a coiling facility (not shown), and a meandering amount measuring device 4 provided in the finishing mill 2.

[0022] In the finish rolling process, tandem rolling is performed in which the steel sheet 10 is simultaneously finish-rolled in a finish rolling mill 2 shown in FIG. 1. The finish rolling mill 2 is equipped with a plurality of (n units: n≧3) rolling stands F1 to Fn that finish roll the steel sheet 10. Each of the rolling stands F1 to Fn is provided with a leveling device 3 that adjusts the amount of reduction on the operation side and the drive side. Each leveling device 3 adjusts the amount of reduction by a reduction device (not shown) attached to the operation side of each of the rolling stands F1 to Fn and the amount of reduction by a reduction device (not shown) attached to the drive side of each of the rolling stands F1 to Fn.

[0023] Furthermore, in order to perform "sensor-based meandering control", the finishing rolling mill 2 is equipped with a meandering amount measuring device 4 that measures the amount of meandering of the steel sheet 10 during finish rolling by the finishing rolling mill 2, and a meandering control device 7 that calculates a roll opening difference, which is the difference in the opening of the roll gap between the operating side and the drive side in the rolling stand Fn to be controlled, based on the meandering amount of the steel sheet 10 calculated by the meandering amount measuring device 4, and sends the calculated roll opening difference to a leveling device 3 provided in the rolling stand Fn to be controlled.

[0024] The meandering amount measuring device 4 includes a line sensor camera 5 as an imaging device that periodically images the surface of the steel sheet 10 during finish rolling, and a meandering amount calculating device 6 that calculates the meandering amount of the steel sheet 10 based on a plurality of images taken by the line sensor camera 5. In this embodiment, the rolling stand to be controlled is the final rolling stand Fn, and the line sensor camera 5 is installed between this rolling stand Fn to be controlled and rolling stand Fn-1 that is one stand upstream of this rolling stand Fn.

[0025] The line sensor camera 5 is a one-dimensional imaging device composed of a CCD imaging sensor element or the like, and images the surface of the steel sheet 10 traveling during rolling across the width direction of the steel sheet 10 as shown in Fig. 4. Fig. 4 shows an image 20 captured by the line sensor camera 5. The line sensor camera 5 periodically images the surface of the steel sheet 10 traveling from the upstream stand side to the downstream stand side, and obtains a plurality of images 20 over a predetermined period of time.

[0026] The meandering amount calculation device 6 calculates the meandering amount of the steel sheet 10 based on a plurality of captured images 20 captured by the line sensor camera 5, and as shown in Figure 2, includes an image acquisition unit 61, a pre-correction edge detection unit 62, a pre-correction edge holding unit 63, a measurement reliability determination unit 64, a plate width update unit 65, a meandering amount calculation unit 66, and an output unit 67. The meandering amount calculation device 6 is a computer system having a calculation processing function, and by executing various dedicated computer programs pre-stored in the hardware, each function of the image acquisition unit 61, the pre-correction edge detection unit 62, the pre-correction edge holding unit 63, the measurement reliability determination unit 64, the plate width update unit 65, the meandering amount calculation unit 66, and the output unit 67 (steps S3 to S9 described later) can be realized on software.

[0027] The image acquisition unit 61 of the meandering amount calculation device 6 acquires a plurality of images 20 of the surface of the steel sheet 10 periodically captured by the line sensor camera 5. The pre-correction edge detection unit 62 calculates the brightness difference between adjacent images in the width direction of each of the plurality of images 20 acquired by the image acquisition unit 61, and identifies the location where the brightness difference is greatest on the drive side in the width direction of the steel sheet 10 as the drive side edge location z of the steel sheet 10. ｄｓ The location where the brightness difference is greatest on the work side in the width direction of the steel plate 10 is determined as the work side edge location z ｗｓ Detect multiple as.

[0028] Specifically, the pre-correction edge detection unit 62 calculates the brightness difference between adjacent pixels from the center in the width direction of each captured image 20 (the center line CL in the steel plate width direction of the captured image 20 shown in FIG. 4 ) to each of the drive side and work side at both ends in the width direction, and determines the location of the drive side where the absolute value of the brightness difference is maximum as the drive side edge location z of the steel plate 10. ｄｓ The part of the work side where the absolute value of the brightness difference is the largest is determined as the work side edge part z ｗｓ Detect multiple as.

[0029] If the area between the rolling stands Fn and Fn-1 where the line sensor camera 5 is installed is an environment free of steam and fumes, as shown in FIG. 5, the absolute value of the brightness difference between adjacent pixels in the width direction is maximized at the drive side location indicated by P1 (drive side edge location z ｄｓ ) coincides with the actual drive side edge portion d of the steel sheet 10. In addition, the work side portion indicated by P2 (work side edge portion z ｗｓ ) coincides with the edge location w of the actual work side of the steel plate 10.

[0030] On the other hand, if the environment between the rolling stand Fn and the rolling stand Fn-1 where the line sensor camera 5 is installed is one in which steam or fumes are present, as shown in FIG. 6, the absolute value of the brightness difference between adjacent pixels in the width direction is maximized at the drive side location indicated by P1 (drive side edge location z ｄｓ) may not coincide with the actual drive side edge portion d of the steel sheet 10. In addition, the work side portion indicated by P2 (work side edge portion z ｗｓ ) may not coincide with the actual work side edge portion w of the steel sheet 10. This is because electromagnetic waves including visible light and infrared rays are scattered by steam and fumes.

[0031] Further, the pre-correction edge holding unit 63 detects the drive side edge locations z of the plurality of steel plates 10 detected by the pre-correction edge detecting unit 62. ｄｓ and work side edge location z ｗｓ The measurement reliability determination unit 64 also determines the drive side edge locations z of the plurality of steel plates 10 held by the pre-correction edge holding unit 63. ｄｓ and work side edge location z ｗｓ The drive side edge location (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... N), the sum α of the absolute values ​​of the change amounts shown in the following equations (1) and (2) ｄｓ , α ｗｓ When each of these is equal to or greater than a predetermined threshold value β, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold value β, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is judged to be highly reliable.

[0032]

[0033]

[0034] That is, the measurement reliability determination unit 64 determines the drive side edge locations z of the plurality of steel plates 10 held by the pre-correction edge holding unit 63. ｄｓ and work side edge location z ｗｓThen, the measurement reliability determination unit 64 acquires the data of the drive side edge locations z ｄｓ The past N drive side edge locations (z ｄｓ (i, i=1, 2, . . . N) are extracted, and the drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) the sum α of the absolute values ​​of the change amounts shown in the above formula (1) ｄｓ Similarly, the measurement reliability determination unit 64 calculates the workpiece side edge locations z ｗｓ The work side edge position (z ｗｓ (i, i = 1, 2, ... N) are extracted, and the extracted work side edge locations (z ｗｓ (i), i = 1, 2, ... N) the sum α of the absolute values ​​of the change amounts shown in the above equation (2) ｗｓ Calculate.

[0035] Then, the measurement reliability determination unit 64 calculates the sum α of the absolute values ​​of the change amounts at the drive side edge locations. ｄｓ and the sum of the absolute values ​​of the changes in the workpiece side edge location α ｗｓ is equal to or greater than a predetermined threshold B. The value of this threshold β is set to an empirically acceptable value for a normal steel sheet 10 as the amount of change between one edge (drive side edge) and the other edge (work side edge) in the width direction of the steel sheet 10. Then, the measurement reliability determination unit 64 calculates the sum α of the absolute values ​​of the amount of change at the drive side edge location. ｄｓ is equal to or greater than a predetermined threshold value β, the drive side edge location z ｄｓ (N) is judged to be unreliable, and the sum of absolute values ​​of the change amount at the work side edge portion α ｗｓ is equal to or greater than a predetermined threshold value β, the work side edge location z ｗｓ (N) is determined to be unreliable. ｄｓ is less than the predetermined threshold value β, the drive side edge location z ｄｓ(N) is judged to be highly reliable, and the sum of the absolute values ​​of the change amounts at the work side edge portions α ｗｓ If is less than the predetermined threshold value β, the work side edge location z ｗｓ (N) is judged to be highly reliable.

[0036] Furthermore, the strip width update unit 65 of the meandering amount calculation device 6 determines the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N), and updates the number of pixels W corresponding to the plate width (the initial value of W is the number of pixels for the set plate width) to this calculated W'. ｄｓ (N) and work side edge location z ｗｓ If it is determined that at least one of (N) is unreliable, the number of pixels W corresponding to the plate width is left as this number of pixels W. The number of pixels for the set plate width, which is the initial value of W, is sent from a higher-level computer (not shown) to the plate width update unit 65 of the meander amount calculation device 6.

[0037] The meandering amount calculation unit 66 also calculates the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N), the drive side edge location z at the current time in the measurement reliability determination unit 64 ｄｓ (N) and work side edge location z ｗｓ The meandering amount of the steel sheet 10 is calculated using the reliability evaluation result of (N) and the number of pixels W corresponding to the sheet width stored in the sheet width update unit 65. Specifically, as shown in Table 1, the meandering amount calculation unit 66 calculates the meandering amount of the steel sheet 10 by using the reliability evaluation result of (N) and the number of pixels W corresponding to the sheet width stored in the sheet width update unit 65. ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable (Case 1), the drive side edge location z ｄｓ(N) and work side edge location z ｗｓ Specifically, in the case of Case 1, if the mill center coordinate is set to 0, the meandering amount of the steel sheet 10 is calculated by the coordinate amount of the center of the steel sheet 10. ｄｓ (N) and z ｗｓ Average value of (N) = (z ｄｓ (N) + z ｗｓ (N)) / 2 is calculated as the amount of meandering of the steel sheet 10.

[0038]

[0039] Furthermore, as shown in Table 1, the meandering amount calculation unit 66 calculates the drive side edge position z ｄｓ (N) and work side edge location z ｗｓ If only one of the two (N) is determined to be highly reliable (cases 2 and 3), the highly reliable current drive side edge location z ｄｓ (N) or work side edge location z ｗｓ Using (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the plate width update unit 65, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ The amount of meandering of the steel plate 10 is calculated using (N) and the edge location on the other side calculated by interpolation.

[0040] That is, as shown in Table 1, the meandering amount calculation unit 66 calculates the drive side edge position z ｄｓ If only (N) is judged to be highly reliable (case 2), the highly reliable drive side edge location z ｄｓ (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the plate width update unit 65, and the highly reliable drive side edge location z ｄｓ In case 2, the amount of meandering of the steel plate 10 is calculated using the drive side edge location z ｄｓ(N) is the center of the steel plate 10, and the point where 1 / 2 of the value obtained by multiplying the number of pixels W corresponding to the plate width by the length x per pixel is added is z ｄｓ (N) + W × x / 2 is calculated as the meandering amount of the steel sheet 10. The mill center coordinate is 0.

[0041] Furthermore, as shown in Table 1, the meandering amount calculation unit 66 calculates the work side edge position z ｗｓ When only (N) is judged to be highly reliable (in the case of Case 3), the work side edge position z at the current time is highly reliable. ｗｓ (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the workpiece width update unit 65, and the highly reliable workpiece side edge location z ｗｓ (N) and the edge location on the other side calculated by interpolation are used to calculate the meandering amount of the steel plate 10. In case 3, the highly reliable work side edge location z ｗｓ The center of the steel plate 10 is determined by subtracting 1 / 2 of the value obtained by multiplying the number of pixels W corresponding to the plate width by the length x per pixel from (N). ｗｓ (N)-W×x / 2 is calculated as the meandering amount of the steel sheet 10. The mill center coordinate is 0. As shown in Table 1, the meandering amount calculation unit 66 calculates the meandering amount of the steel sheet 10 by the measurement reliability determination unit 64. ｄｓ (N) and work side edge location z ｗｓ If it is determined that both of (N) and (N) are unreliable (case 4), the amount of meandering of the steel plate 10 is not calculated.

[0042] Furthermore, the output section 67 of the meandering amount calculation device 6 sends the meandering amount of the steel sheet 10 calculated by the meandering amount calculation section 66 to the meandering control device 7. The meandering control device 7 calculates a roll opening difference, which is the difference in roll gap opening between the operating side and the driving side in the rolling stand Fn to be controlled, based on the meandering amount of the steel sheet 10 from the output section 67 of the meandering amount calculation device 6, and sends the calculated roll opening difference to the leveling device 3 provided in the rolling stand Fn to be controlled.

[0043] Based on the roll gap difference sent from the meandering control device 7, the leveling device 3 adjusts the reduction amount by the screw down device attached to the operation side of the rolling stand Fn to be controlled and the reduction amount by the screw down device attached to the drive side of the rolling stand Fn so that the roll gap difference of the rolling stand Fn to be controlled becomes the roll gap difference sent from the meandering control device 7. As a result, the leveling amount of the rolling stand Fn to be controlled is changed in proportion to the meandering amount of the steel sheet 10, and the meandering amount of the steel sheet 10 is suppressed.

[0044] In this way, according to the steel sheet meandering amount measuring device 4 of this embodiment, the meandering amount calculating device 6 measures the drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... N) The sum α of the absolute values ​​of the change amounts shown in the above equations (1) and (2) ｄｓ , α ｗｓ If each of these is equal to or greater than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ The meandering amount calculation device 6 also includes a measurement reliability determination unit 64 that determines that the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is used to calculate the amount of meandering of the steel plate 10, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ If only one of the two is determined to be highly reliable, the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓUsing (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the plate width update unit 65, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ (N) and the edge location on the other side calculated by interpolation are used to calculate the amount of meandering of the steel plate 10, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ and a meandering amount calculation unit 66 that does not calculate the meandering amount of the steel sheet 10 when both of (N) and (N) are determined to be unreliable.

[0045] This makes it possible to provide a steel plate meandering amount measuring device 4 that can accurately measure the meandering amount of a steel plate 10 not only when both edges of the steel plate 10 can be detected, but also when one edge of the steel plate 10 is covered with steam or fumes and cannot be detected, and the other edge is not covered with steam or fumes and can be detected. Furthermore, the meandering amount computing device 6 is equipped with an output unit 67 that outputs the meandering amount of the steel plate 10 calculated by the meandering amount calculating unit 66 to the meandering control device 7. This allows the meandering control device 7 to appropriately control the leveling of the rolling stand Fn to be controlled, based on the meandering amount measured by the meandering amount measuring device 4.

[0046] Furthermore, the hot rolling equipment 1 for hot rolled steel strips according to this embodiment is equipped with a meandering amount measuring device 4. This makes it possible to provide a hot rolling equipment 1 for hot rolled steel strips that can accurately measure the meandering amount of the steel sheet 10 when measuring the meandering amount of the steel sheet 10 during rolling not only when both edges of the steel sheet 10 can be detected, but also when one edge of the steel sheet 10 is covered with steam or fumes and cannot be detected, and the other edge is not covered with steam or fumes and can be detected.

[0047] Next, a processing flow by the meandering amount measuring device 4, which shows a meandering amount measuring method according to one embodiment of the present invention, will be described with reference to the flowchart shown in Figure 3. First, finish rolling of the steel sheet 10 is started, and in step S1, it is determined whether the line sensor camera 5 has detected the leading edge of the steel sheet 10. The line sensor camera 5 is equipped with a steel sheet detection sensor (not shown) that detects the leading and trailing edges of the steel sheet 10. If the determination result by the line sensor camera 5 is YES (if the leading edge has been detected), the process proceeds to step S2, and if the determination result is NO (if the leading edge has not been detected), the process returns to step S1. In step S2, the line sensor camera 5 periodically images the surface of the traveling steel sheet 10 during rolling, across the width direction of the steel sheet 10 (imaging step).

[0048] Next, the process proceeds to step S3, where the captured image acquisition unit 61 of the meandering amount calculation device 6 acquires a plurality of captured images 20 of the surface of the steel sheet 10 periodically captured by the line sensor camera 5 (captured image acquisition step). Next, the process proceeds to step S4, where the pre-correction edge detection unit 62 calculates the brightness difference between adjacent images in the width direction of each of the plurality of captured images 20 acquired in step S3, and identifies the location where the brightness difference is greatest on the drive side in the width direction of the steel sheet 10 as the drive side edge location z of the steel sheet 10. ｄｓ The location where the brightness difference is greatest on the work side in the width direction of the steel plate 10 is determined as the work side edge location z ｗｓ (pre-correction edge detection step).

[0049] Next, the process proceeds to step S5, in which the pre-correction edge holding unit 63 calculates the drive side edge positions z detected in step S4. ｄｓ and work side edge location z ｗｓ Next, the process proceeds to step S6, where the measurement reliability determination unit 64 determines the drive side edge locations z of the plurality of steel plates 10 held in step S4. ｄｓ and work side edge location z ｗｓ The drive side edge location (z ｄｓ(i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... N) The sum α of the absolute values ​​of the change amounts shown in the above equations (1) and (2) ｄｓ , α ｗｓ When each of these is equal to or greater than a predetermined threshold value β, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold value β, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be highly reliable (measurement reliability determination step).

[0050] Next, the process proceeds to step S7, and the strip width update unit 65 calculates the drive side edge position z ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N), and updates the number of pixels W corresponding to the plate width (the initial value of W is the number of pixels for the set plate width) to this calculated W'. ｄｓ (N) and work side edge location z ｗｓ If at least one of (N) is determined to be unreliable, the number of pixels W corresponding to the board width is left as it is (board width update step).

[0051] Next, the process proceeds to step S8. The meandering amount calculation unit 66 calculates the drive side edge position z ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ(N) to calculate the meandering amount of the steel sheet 10. In step S7, the meandering amount calculation unit 66 calculates the meandering amount of the steel sheet 10 by calculating the drive side edge position z ｄｓ (N) and work side edge location z ｗｓ If only one of the two is determined to be highly reliable, the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ Using (N) as a reference, the edge location on the other side is interpolated using the number of pixels W from step S7, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ (N) and the edge location on the other side calculated by interpolation, the meandering amount of the steel sheet 10 is calculated. ｄｓ (N) and work side edge location z ｗｓ If both of (N) are determined to be unreliable, the meandering amount of the steel plate 10 is not calculated (meandering amount calculation step).

[0052] Next, the process proceeds to step S9, where the output unit 67 of the meandering amount calculation device 6 sends the meandering amount of the steel sheet 10 calculated in step S8 to the meandering control device 7 (output step). Finally, the process proceeds to step S10, where the line sensor camera 5 determines whether or not it has detected the leading end of the steel sheet 10. If the determination result by the line sensor camera 5 is YES (if the tail end has been detected), the process ends, and if the determination result is NO (if the tail end has not been detected), the process returns to step S2. This ends the process by the meandering amount measurement device 4.

[0053] As described above, according to the meandering amount measuring method of this embodiment, in the measurement reliability determining step (step S6), the drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... N) The sum α of the absolute values ​​of the change amounts shown in the above equations (1) and (2) ｄｓ , α ｗｓIf each of these is equal to or greater than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ In the meandering amount calculation step (step S8), the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is used to calculate the amount of meandering of the steel plate 10. ｄｓ (N) and work side edge location z ｗｓ If only one of the two is determined to be highly reliable, the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ Using (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the plate width update unit 65, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ (N) and the edge location on the other side calculated by interpolation are used to calculate the amount of meandering of the steel plate 10. Furthermore, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ If both of (N) are determined to be unreliable, the amount of meandering of the steel sheet 10 is not calculated.

[0054] This provides a method for measuring the meandering amount of a steel sheet 10 that can accurately measure the meandering amount of the steel sheet 10 during rolling not only when both edges of the steel sheet 10 can be detected, but also when one edge of the steel sheet 10 is covered with steam or fumes and cannot be detected, and the other edge is covered with steam or fumes and can be detected. The meandering amount measuring method according to this embodiment also includes an output step (step S9) of outputting the meandering amount of the steel sheet 10 calculated in the meandering amount calculation step (step S8) to the meandering control device. This allows the meandering control device 7 to appropriately control the leveling of the rolling stand Fn to be controlled, based on the meandering amount measured in the meandering amount measurement step.

[0055] Furthermore, the hot rolling method for a hot rolled steel strip according to this embodiment includes a step of measuring the meandering amount of the steel sheet 10 during rolling by a finishing mill 2 having a plurality of rolling stands F1 to Fn using this meandering amount measurement method. This makes it possible to provide a hot rolling method for a hot rolled steel strip that can accurately measure the meandering amount of the steel sheet 10 not only when both edges of the steel sheet 10 can be detected when measuring the meandering amount of the steel sheet during rolling, but also when one edge of the steel sheet 10 is covered with steam or fumes and cannot be detected, and the other edge is covered with steam or fumes and can be detected.

[0056] Although the embodiments of the present invention have been described above, the present invention is not limited thereto and various modifications and improvements can be made. For example, the imaging device does not need to be a line sensor camera 5 and may be an area sensor camera. Furthermore, when the pre-correction edge detection unit 62 (pre-correction detection step) calculates the luminance difference between adjacent pixels in the width direction of the captured image 20, it may not only calculate the luminance difference between adjacent pixels from the center of the width direction of the captured image 20 to each of the drive side and work side at both ends in the width direction, but may also calculate the luminance difference between adjacent pixels from the work side at one end of the width direction of the captured image 20 to the center of the width direction and to the drive side at one end of the width direction of the captured image 20.

[0057] In addition, the strip width update unit (strip width update step) 65 updates the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ When the number of pixels W' corresponding to the plate width calculated from both (N) is calculated, if this calculated W' is within a preset upper and lower limit range, the number of pixels W corresponding to the plate width may be updated to this calculated W'. If the calculated W' is outside the preset upper and lower limit range, the number of pixels W corresponding to the plate width may be left as is. In this way, if the number of pixels W' calculated by the plate width update unit (plate width update step) 65 deviates from the number of pixels corresponding to the normal plate width of the steel plate 10, the plate width update operation is not required, and the processing time for the meander amount calculation process can be shortened. Note that the "preset upper and lower limit range" means the upper and lower limit range of the number of pixels corresponding to the normal plate width of the steel plate 10.

[0058] Furthermore, the line sensor camera 5 as an imaging device is installed between the rolling stand Fn to be controlled and the rolling stand Fn-1 one stand upstream thereof, but is not limited to this and may be installed between any of the adjacent rolling stands F1 and F2, F2 and F3, ..., Fn-1 and Fn. Furthermore, the meandering amount measuring device 4 and the meandering amount measuring method according to the first and second embodiments are applied to measuring the meandering amount of the steel sheet 10 being rolled by the finishing mill 2 of the hot rolling facility 1, but may also be applied when measuring the meandering amount of the steel sheet being rolled by a continuous cold rolling mill of the cold rolling facility.

[0059] The inventors finish-rolled a steel sheet 10 using a finishing rolling facility 1 having seven rolling stands F1 to F7, and during this process, periodically captured images of the surface of the steel sheet 10 using a line sensor camera 5 installed between the rolling stand F6 and the rolling stand F7 to be controlled.Based on the multiple captured images 20 captured by the line sensor camera 5, a meandering amount calculation device 6 calculated the amount of meandering of the steel sheet 10 in the comparative example and the example of the present invention.

[0060] 7 shows a two-dimensional image in which a plurality of captured images 20 periodically captured by the line sensor camera 5 are joined along the longitudinal direction of the steel sheet 10. In the two-dimensional image shown in FIG. 7, the cloud-like objects are water vapor present on the surface of the steel sheet 10. Water vapor and fumes may be present on the surface of the steel sheet 10 not only in winter but also in summer. In the present invention, even in cases where one edge of the steel sheet 10 is covered with steam or the like and edge detection is not possible, and the other edge is not covered with steam or the like and edge detection is possible, the amount of meandering of the steel sheet can be accurately measured not only in winter but also in summer.

[0061] The amount of meandering of the steel sheet 10 was calculated for the comparative example and the example of the present invention using this two-dimensional image. In the comparative example, the amount of meandering of the steel sheet 10 was calculated in the following steps: Step 1: The brightness difference between adjacent areas in the width direction of the two-dimensional image was calculated, and the location where the absolute value of the brightness difference was maximum on the drive side in the width direction of the steel sheet 10 was determined as the drive side edge location z of the steel sheet 10. ｄｓ The position where the absolute value of the brightness difference is maximum on the work side in the width direction of the steel plate 10 is determined as the work side edge position z ｗｓ Step 2: The drive side edge locations (z ｄｓ (i), i = 1, 2, ... 100) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... 100) are regressed and the drive side edge location (z ｄｓ (i), i = 1, 2, ... 100) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ... 100), and the drive side edge location and work side edge location at the current time were estimated from these approximate lines. Step 3: The amount of meandering of the steel plate 10 was calculated using the drive side edge location and work side edge location at the current time estimated in Step 2.

[0062] In the present invention, the meandering amount of the steel sheet 10 was calculated in the following steps: Step 1: The brightness difference between adjacent two points in the width direction of the two-dimensional image was calculated, and the point where the absolute value of the brightness difference was maximum on the drive side in the width direction of the steel sheet 10 was determined as the drive side edge point z ｄｓ The position where the absolute value of the brightness difference is maximum on the work side in the width direction of the steel plate 10 is determined as the work side edge position z ｗｓ Multiple cases were detected.

[0063] Step 2: The drive side edge location (z ｄｓ (i), i = 1, 2, ... N = 20) and the workpiece side edge location (z ｗｓ (i), i = 1, 2, ..., N = 20), the sum α of the absolute values ​​of the change amounts shown in the above equations (1) and (2) ｄｓ , α ｗｓ If each of these is equal to or greater than a predetermined threshold value β, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold value β, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) was judged to have high reliability. Here, β was set to 30px (number of pixels) x 1px (length per pixel) (2 mm) = 60 mm. Note that for β, the preferred number of pixels is 5 to 100, and more preferably 10 to 50.

[0064] Step 3: In step 2, the drive side edge location z ｄｓ (20) and work side edge location z ｗｓ If both of (20) are judged to be highly reliable, the drive side edge location z ｄｓ (20) and work side edge location z ｗｓ The number of pixels W' corresponding to the plate width calculated from both (20) is calculated, and the number of pixels W corresponding to the plate width is updated to this calculated W'. ｄｓ (20) and work side edge location z ｗｓIf at least one of the above (20) is determined to be unreliable, the number of pixels W corresponding to the plate width is left as it is.

[0065] Step 4: In step 2, the drive side edge location z ｄｓ (20) and work side edge location z ｗｓ If both of (20) are judged to be highly reliable, the drive side edge location z ｄｓ (20) and work side edge location z ｗｓ (20) is used to calculate the meandering amount of the steel plate 10, and the drive side edge location z ｄｓ (20) and work side edge location z ｗｓ When only one of the two (20) is determined to be highly reliable, the current drive side edge location z ｄｓ (20) or work side edge location z ｗｓ Using (20) as a reference, the edge location on the other side is interpolated using the number of pixels W from step 3, and the highly reliable drive side edge location z ｄｓ (20) or work side edge location z ｗｓ (20) and the interpolated edge location on the other side are used to calculate the meandering amount of the steel plate 10, and the drive side edge location z ｄｓ (20) and work side edge location z ｗｓ If both of (20) were determined to be unreliable, the amount of meandering of the steel plate 10 was not calculated.

[0066] In the comparative example and the inventive example, step 1 was performed to detect the drive side edge portion and the work side edge portion of the steel plate 10, and the drive side edge portion was shown by a solid line and the work side edge portion was shown by a dashed line, as shown in Figure 8. As can be seen from Figure 8, the detected drive side edge portion and work side edge portion are not necessarily the edge of the steel plate 10, and may be located inside the steel plate 10, because they are strongly affected by steam.

[0067] FIG. 9 shows the results of calculating the meandering amount of the steel sheet 10 using the comparative example. In FIG. 9, the drive side edge location, work side edge location, and meandering amount are displayed in units of px (pixels). As shown in FIG. 9(c), in the comparative example, the measured meandering amount fluctuated by approximately 50 px around data order 4000. This is because, as shown in FIG. 9(b), the estimation of the drive side edge location of the steel sheet 10 around data order 4000 was poor. If this fluctuating meandering amount is output to the meandering control device 7 and leveling control is performed, the leveling setting for the controlled rolling stand F7 will be poor, and meandering of the steel sheet 10 will be accelerated. Note that changing the number of past data used for regression from 100 to another value did not produce good results. Note that the tail end, where data order is 14000 and beyond, is also strongly affected by steam.

[0068] Therefore, in the comparative example, when measuring the meandering amount of the steel sheet 10 during rolling, if one edge of the steel sheet 10 was covered with steam or fumes, preventing detection of the edge (drive side edge), and the other edge (work side edge) was covered with steam or fumes, allowing edge detection, the meandering amount of the steel sheet 10 could not be accurately measured. On the other hand, Figure 10 shows the results of calculating the meandering amount of the steel sheet 10 using the example of the present invention. In Figure 10, the units of the drive side edge location, work side edge location, and meandering amount are also displayed in px (number of pixels). As shown in Figure 10(c), in the example of the present invention, the measured meandering amount is almost uniform, and the measured meandering amount due to steam is alleviated. Looking at the comparative example, the drive side of the steel sheet 10 is covered with steam or fumes at around data order 4000, preventing detection of the drive side edge.

[0069] Therefore, in the present invention, when measuring the meandering amount of the steel sheet 10 during rolling, if one edge of the steel sheet 10 is covered with steam or fumes and the edge (drive side edge) cannot be detected, and the other edge (work side edge) is covered with steam or fumes and the edge can be detected, it is possible to accurately measure the meandering amount of the steel sheet 10. Note that in the present invention, the locations where the meandering amount is 0 px for data sequences after 14000 are locations where the reliability of both edge locations is low, and no control output is given to the meandering control device 7, so no actual harm occurs.

[0070] 11 shows a comparison of the calculated values ​​of the meandering amount of the steel sheet calculated by the example of the present invention and the comparative example. Referring to Fig. 11, in the example of the present invention, the meandering amount of the steel sheet 10 is almost uniform from the data order 0 (the leading end of the steel sheet 10) to 14,000 (the tail end of the steel sheet 10) compared to the comparative example, and it is expected that the meandering amount can be measured appropriately and that the leveling operation for meander control using this will also be optimized.

[0071] REFERENCE SIGNS LIST 1 Hot rolling equipment 2 Finishing rolling mill (rolling mill) 3 Leveling device 4 Meandering amount measuring device 5 Line sensor camera (imaging device) 6 Meandering amount calculation device 7 Meandering control device 10 Steel plate 20 Photographed image 61 Photographed image acquisition unit 62 Pre-correction edge detection unit 63 Pre-correction edge holding unit 64 Measurement reliability determination unit 65 Plate width update unit 66 Meandering amount calculation unit 67 Output unit F1 to Fn Rolling stand

Claims

1. A steel plate meandering amount measuring device for measuring the meandering amount of a steel plate being rolled by a rolling mill having a plurality of rolling stands, comprising: an imaging device that is installed between adjacent rolling stands and periodically images the surface of the steel plate traveling during rolling; and a meandering amount calculating device that calculates the meandering amount of the steel plate based on a plurality of images taken by the imaging device, the meandering amount calculating device calculates the brightness difference between adjacent images in the width direction of each of the plurality of images taken periodically by the imaging device, and determines the location where the absolute value of the brightness difference is maximum on the drive side in the width direction of the steel plate as the drive side edge location z of the steel plate. ｄｓ The location where the absolute value of the brightness difference is maximum on the work side in the width direction of the steel plate is defined as the work side edge location z ｗｓ a pre-correction edge detection unit that detects a plurality of drive side edge locations z ｄｓ and work side edge location z ｗｓ The past N drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ The sum α of the absolute values ​​of the change amounts shown in the following equations (1) and (2) for (i), i = 1, 2, ..., N ｄｓ , α ｗｓ If each of the above is equal to or greater than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ A measurement reliability determination unit that determines that the drive side edge location z (N) at the current time is highly reliable. ｄｓ (N) and work side edge location z ｗｓ If both of (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ The number of pixels W' corresponding to the plate width calculated from both (N) is calculated, the number of pixels W corresponding to the plate width is updated to this calculated W', and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is determined to be unreliable, a plate width update unit that keeps the number of pixels W corresponding to the plate width as this number of pixels W; ｄｓ (N) and work side edge location z ｗｓ If both of (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is used to calculate the amount of meandering of the steel plate, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ If only one of the drive side edge locations z ｄｓ (N) or work side edge location z ｗｓ Using (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the plate width update unit, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ The amount of meandering of the steel plate is calculated using (N) and the edge location on the other side calculated by interpolation, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ and (N) a meandering amount calculation unit that does not calculate the meandering amount of the steel sheet when both of the above-mentioned reliability are determined to be low.

2. In the strip width update unit, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ the number of pixels W corresponding to the plate width is updated to the calculated W' when the calculated W' is within a preset upper and lower limit range, and the number of pixels W corresponding to the plate width is left unchanged when the calculated W' is outside the preset upper and lower limit range.

3. The meandering amount calculation device detects the drive side edge locations z of the plurality of the steel plates detected by the pre-correction edge detection unit. ｄｓ and work side edge location z ｗｓ The measurement reliability determination unit is provided with a pre-correction edge holding unit that holds the drive side edge locations z of the plurality of steel plates held by the pre-correction edge holding unit. ｄｓ and work side edge location z ｗｓ 3. The steel plate meandering amount measuring device according to claim 1, wherein each of the above is acquired.

4. A steel plate meandering amount measuring device as described in any one of claims 1 to 3, characterized in that the meandering amount calculation device is provided with an output section which outputs the meandering amount of the steel plate calculated by the meandering amount calculation section to a meandering control device.

5. A hot rolling facility for hot rolled steel strip, comprising the device for measuring the amount of meandering of a steel plate according to any one of claims 1 to 4.

6. A method for measuring the meandering amount of a steel plate during rolling by a rolling mill having a plurality of rolling stands, comprising: an imaging step of periodically imaging the surface of the steel plate traveling during rolling by an imaging device installed between adjacent rolling stands; a brightness difference between adjacent images in the width direction of each of the plurality of images periodically captured in the imaging step is calculated; and a location where the absolute value of the brightness difference is maximum on the drive side in the width direction of the steel plate is defined as a drive side edge location z of the steel plate. ｄｓ The location where the absolute value of the brightness difference is maximum on the work side in the width direction of the steel plate is defined as the work side edge location z ｗｓ a pre-correction edge detection step of detecting a plurality of drive side edge locations z ｄｓ and work side edge location z ｗｓ The past N drive side edge locations (z ｄｓ (i), i = 1, 2, ... N) and the workpiece side edge location (z ｗｓ The sum α of the absolute values ​​of the change amounts shown in the following equations (1) and (2) for (i), i = 1, 2, ..., N ｄｓ , α ｗｓ If each of the above is equal to or greater than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be unreliable, and if it is less than a predetermined threshold, the drive side edge location z ｄｓ (N), work side edge location z ｗｓ (N) is determined to be highly reliable; and ｄｓ (N) and work side edge location z ｗｓ If both of (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ The number of pixels W' corresponding to the plate width calculated from both (N) is calculated, the number of pixels W corresponding to the plate width is updated to this calculated W', and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is determined to be unreliable, a plate width update step of keeping the number of pixels W corresponding to the plate width as this number of pixels W; ｄｓ (N) and work side edge location z ｗｓ If both of (N) are judged to be highly reliable, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ (N) is used to calculate the amount of meandering of the steel plate, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ If only one of the drive side edge locations z ｄｓ (N) or work side edge location z ｗｓ Using (N) as a reference, the edge location on the other side is calculated by interpolation using the number of pixels W from the board width update step, and the highly reliable drive side edge location z ｄｓ (N) or work side edge location z ｗｓ The amount of meandering of the steel plate is calculated using (N) and the edge location on the other side calculated by interpolation, and the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ and (N) a meandering amount calculation step of not calculating the meandering amount of the steel sheet if both of the above are determined to be unreliable.

7. In the strip width update step, the drive side edge location z ｄｓ (N) and work side edge location z ｗｓ the number of pixels W corresponding to the plate width is updated to the calculated W' when the calculated W' is within a preset upper and lower limit range, and the number of pixels W corresponding to the plate width is left unchanged when the calculated W' is outside the preset upper and lower limit range.

8. The drive side edge locations z of the plurality of steel plates detected in the uncorrected edge detection step ｄｓ and work side edge location z ｗｓ The measurement reliability determination step includes a pre-correction edge holding step of holding the drive side edge portions z ｄｓ The method for measuring the amount of meandering of a steel plate according to claim 6 or 7, further comprising the step of acquiring the position of the workpiece side edge and the position of the workpiece side edge.

9. A method for measuring the amount of meandering of a steel plate according to any one of claims 6 to 8, further comprising an output step of outputting the amount of meandering of the steel plate calculated in the amount of meandering calculation step to a meandering control device.

10. A method for hot rolling a hot rolled steel strip, comprising a step of measuring the amount of meandering of a steel plate during rolling using a rolling mill having a plurality of rolling stands, by the method for measuring the amount of meandering of a steel plate as claimed in any one of claims 6 to 9.

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