Methods for calculating steel bending, steel manufacturing methods, methods for determining steel bending, and devices for calculating steel bending.

Abstract

This invention provides a method for calculating the bending amount of steel, which can measure the bending amount of steel even under conditions where the equipment has a narrow settable range, thereby enabling accurate determination of the bending amount of steel with a simple equipment structure. A method for calculating the bending amount of steel rolled by a rolling mill includes: an imaging step, using an imaging device to photograph the front end of the steel on the exit side of the rolling mill from above or below, capturing the long side direction of the steel; an extraction step, extracting shapes related to the left and right ends of the front end of the long side direction from the captured image of the front end of the steel; and a calculation step, calculating the difference in long side direction position and / or the difference in left and right position of the left and right ends based on the extracted shapes.

Description

Technical Field

[0001] This invention relates to a method for calculating the bending amount of steel, a method for manufacturing steel, a method for determining the bending amount of steel, and a device for calculating the bending amount of steel. Prior Technology

[0002] In the past, steel bending sometimes occurred during the rolling process. This bending can affect product yield and productivity, and therefore needs to be suppressed. To control steel bending, it is essential to accurately detect it.

[0003] For example, Patent Document 1 discloses a method for calculating the bending amount of a steel plate as follows. In Patent Document 1, a two-dimensional imaging element such as a charge-coupled device (CCD) camera is installed above the exit side of the rolling mill to capture an image of the hot steel plate. Various image processing techniques are applied to the steel plate image to extract its outline. Furthermore, the coordinates of the center position of the steel plate in the width direction are determined along the long side direction of the steel plate (see Figure 2 of Patent Document 1), and this coordinate data is used to calculate the bending amount.

[0004] Furthermore, as a method for measuring the bending amount of H-beams, Patent Document 2 discloses, for example, the following method: a pair of distance sensors are arranged in a horizontal direction orthogonal to the walking direction of the H-beam, and for the H-beam in motion, the distance up to the outer surface of the flange is measured using each sensor, and the bending amount is detected based on these measured values.

[0005] Furthermore, as a method for measuring the bending of structural steel, for example, Patent Document 3 discloses a method as follows. In this method, the brightness distribution in the width direction on multiple cross-sections at fixed intervals along the long side is calculated based on an image of the structural steel taken from above, thereby detecting bending portions on each cross-section. Subsequently, the width direction positions of the bending portions are connected along the long side to calculate the bending distribution along the long side. [Existing Technical Documents] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 1999-28510 [Patent Document 2] Japanese Patent Application Publication No. 2006-234540 [Patent Document 3] Japanese Patent Application Publication No. 2019-178901 Summary of the Invention

[0007] [The problem that the invention aims to solve] However, the prior art has the following problems that need to be solved. That is, the technology disclosed in Patent Document 1 is a bending measurement technology related to steel plates, and not a technology for all types of steel, including sheet piles. Moreover, it is impossible to determine the amount of bending based on an image of only the front end of the steel plate, and the calculation of the amount of bending requires mapping an image of the steel plate over a certain range along the long side.

[0008] Furthermore, the technology disclosed in Patent Document 2 requires a special measuring device with a distance sensor. Moreover, data from the distance sensor is needed along the long side of the steel section, but if the steel section is warped vertically during the measurement, it cannot be measured accurately.

[0009] Moreover, the technology disclosed in Patent Document 3 accurately measures the curvature along the long side by taking pictures of the rolled material over a wide range, which is not suitable for places where pictures can only be taken in a limited range, such as between rolling stands in tandem rolling.

[0010] Based on the aforementioned situation, the object of the present invention is to provide a method and apparatus for calculating the bending amount of steel, which can measure the bending amount of steel even under conditions where the range of equipment settings is narrow, thereby enabling accurate determination of the bending amount of steel with a simple equipment structure. Furthermore, the object of the present invention is to provide a method for manufacturing steel and a method for determining the bending amount of steel, using the steel bending calculation method described above. [Methods for solving problems]

[0011] One aspect of the present invention provides a method for calculating the bending amount of steel after it has been rolled by a rolling mill. The method includes: The shooting step involves using a shooting device to photograph the steel from above or below the outlet side of the rolling mill, capturing the front end of the steel in the long side direction at the outlet side of the rolling mill. The extraction step involves extracting the shapes related to the left and right ends of the front end along the long side of the steel from an image of the front end along the long side obtained by photography; and The calculation step involves calculating the difference in the long side position and / or the difference in the left and right positions of the extracted shape to calculate the bending amount (first structure).

[0012] Furthermore, the first structure can also be configured such that, in the shooting step, a first reference object is photographed that is perpendicular to the long side and extends in the left-right direction. The method for calculating the bending amount of steel further includes a determination step, which is based on the image of the first reference object to determine a first reference line (second structure) for determining the position of the long side in the left and right ends.

[0013] Furthermore, in the first structure, it can also be configured such that, in the shooting step, a second reference object used to determine the left and right center positions of the roll pass is photographed. The method for calculating the bending amount of steel further includes a determination step, which is based on the image of the second reference object to determine a second reference line (third structure) for determining the left and right positions of the left and right ends.

[0014] Furthermore, in any of the first to third structures, the structure can also be configured such that the steel is a sheet pile with a web and joints at both ends in the width direction. The left and right ends are the ends (fourth structure) that include the left and right connector portions.

[0015] Furthermore, in any of the first to fourth structures, the following structure can also be configured, in which the imaging device is positioned between the rolling mill used for tandem rolling and a different rolling mill (fifth structure).

[0016] Furthermore, the steel manufacturing method disclosed herein is based on the calculated value obtained by the steel bending amount calculation method of any of the first to fifth structures. In the next steel rolling, the skewness of the rolling mill rolls and / or the relative axial positions of the upper and lower rolls are changed to perform rolling (sixth structure).

[0017] Furthermore, the steel bending determination method disclosed herein is based on the calculated value obtained by using the steel bending amount calculation method of any of the first to fifth structures to determine the bending of the steel (seventh structure).

[0018] Furthermore, the steel bending amount calculation device disclosed herein is a steel bending amount calculation device that calculates the bending amount of steel rolled by a rolling mill, the steel bending amount calculation device comprising: A camera is positioned on the outlet side of the rolling mill and photographs the steel from above or below. The image processing unit extracts the shapes related to the left and right ends of the front end along the long side of the steel from an image of the front end along the long side obtained by photography; and The calculation unit calculates the bending amount (eighth structure) based on the extracted shape by calculating the difference in the rolling long side position of the left and right ends and / or the difference in the left and right position. [The effects of the invention]

[0019] According to the present invention, even under conditions where the range of equipment settings is narrow, the amount of bending of steel can be measured, thereby enabling accurate control of the amount of bending of steel with a simple equipment structure. Simple Explanation of the Diagram

[0020] Figure 1A is a diagram showing the cross-sectional shape of a cap-shaped sheet pile. Figure 1B is a diagram showing the cross-sectional shape of a U-shaped steel sheet pile. Figure 1C is a diagram showing the cross-sectional shape of a straight steel sheet pile. Figure 2 is a diagram showing an example of the schematic structure of a hot rolling equipment for steel sheet piles. Figure 3 is a diagram showing an example of a pass pattern used in a roughing mill. Figure 4A is a diagram showing an example of a pass pattern used in an intermediate rolling mill. Figure 4B is a diagram showing an example of a pass pattern used in an intermediate rolling mill. Figure 5 is a diagram showing an example of a pass pattern used in a finishing mill. Figure 6 is a structural diagram showing an example of a rolling control device. Figure 7A is a diagram showing the upper and lower rolls in an intermediate rolling mill. Figure 7B is a diagram showing the upper and lower rolls in an intermediate rolling mill. Figure 8 is a side view showing the camera's position relative to the intermediate rolling mill. Figure 9 is a top view showing the camera's position relative to the intermediate rolling mill. Figure 10 is a front view showing the camera's position relative to the intermediate rolling mill. Figure 11 is a flowchart illustrating the process flow for bending control. Figure 12 is a diagram showing the structure of the image analysis device. Figure 13 is an example of a captured image containing a front-end image. Figure 14 is a diagram showing the contour lines extracted by contour line processing. Figure 15 is a diagram showing the definition of the amount of bending in the product (hat-shaped sheet pile). Figure 16 is a table showing the results of the embodiment. Figure 17 is a graph showing the relationship between the difference in position along the long side in Figure 16 and the leveling amount. Figure 18 is a graph showing the relationship between the difference in left and right positions in Figure 16 and the leveling amount. Figure 19 is a top view showing the camera's position relative to the intermediate rolling mill. Figure 20 is a diagram showing the structure of the rolling control device in the modified example. Implementation

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Furthermore, the embodiments shown below are illustrative of apparatus and methods for embodying the technical concept of the present invention; the technical concept of the present invention does not specify the material, shape, structure, arrangement, etc., of the constituent parts in the following embodiments. Moreover, the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc., differ from reality, and the drawings also include portions with different dimensional relationships and ratios.

[0022] <An Overview of Steel Sheet Piles and Their Rolling Manufacturing Methods> Figures 1A, 1B, and 1C are diagrams showing the cross-sectional shapes of various sheet piles. The cap-shaped sheet pile 1 manufactured in this embodiment, as shown in Figure 1A, has a cap-shaped cross-section orthogonal to its long side. As a cross-sectional shape, the cap-shaped sheet pile 1 has a web 11, a pair of flanges 12, a pair of arms 13, and a mating head 14. The web 11 extends in the left-right direction. The pair of flanges 12 are connected to both ends of the web 11 in the left-right direction and extend obliquely relative to the left-right direction. In the example shown in Figure 1A, the pair of flanges 12 extend obliquely with their ends opposite to the web 11 facing downwards in the vertical direction (orthogonal to the left-right direction). The pair of arms 13 are connected to the side of the pair of flanges 12 that is not connected to the web 11 and extend in the left-right direction. A pair of head 14 is a portion connected to one side of the unconnected flange 12 of a pair of arms 13, and has a hook-shaped shape that opens upwards or downwards. The pair of head 14 is a portion used for connection with other sheet piles when used as a sheet pile, where it is fitted into the joint of other sheet piles.

[0023] Furthermore, the present invention can also be applied to the manufacture of sheet piles other than cap-shaped sheet piles. Figure 1B shows a U-shaped sheet pile 1X. The U-shaped sheet pile 1X is a structure in the cap-shaped sheet pile 1 where the arm portion 13 is omitted. Moreover, both the butt joints 14 in the U-shaped sheet pile 1X open upwards. Furthermore, Figure 1C shows a straight sheet pile 1Y. The straight sheet pile 1Y has a structure in which a butt joint 14 is connected to both ends of the web 11 extending in the left-right direction. The butt joint 14 opens in the left-right direction.

[0024] Furthermore, the steel to which this invention is applicable is not limited to sheet piles. As long as the cross-sectional shape can be considered approximately symmetrical from left to right, the bending amount can be calculated and the rolling process based on this can be performed in the same manner as for sheet piles. Examples of steel materials other than sheet piles include H-beams, I-beams, channel steel, and flat steel.

[0025] Next, the rolling line used for manufacturing the cap-shaped sheet pile 1 will be described. Figure 2 is a diagram showing an example of the schematic structure of the sheet pile manufacturing apparatus, i.e., the hot rolling mill for sheet piles, according to an embodiment of the present invention. The hot rolling mill 2 is the equipment for hot rolling the cap-shaped sheet pile 1. The hot rolling mill 2 includes, in sequence from upstream to downstream, a heating furnace 3, a roughing mill 4, an intermediate rolling mill 5, and a finishing mill 6. The intermediate rolling mill 5 is configured by cascading two rolling mills 5A and 5B. The arrows in Figure 2 indicate the rolling advance direction.

[0026] The heating furnace 3 heats the continuously cast slabs or blooms, which are used as raw material steel sheets, to a specified temperature. The raw material steel sheets, heated in the heating furnace 3, are then rolled using multiple passes in the sequence of roughing mill 4, intermediate mill 5, and finishing mill 6, to achieve the finished product shape of the cap-shaped steel sheet pile 1 shown in Figure 1A. In these rolling mills, passes called calibers are formed on the upper and lower rolls.

[0027] The roughing mill 4 uses multiple passes to rough-form the rolled material into a cross-sectional shape similar to the product shape. In this roughing step, multiple reverse rolling passes are performed. Here, Figure 3 shows an example of the passes used in the roughing mill 4. Three passes—Box, K8, and K7—are formed in the upper roll 41 and lower roll 42.

[0028] In the roughing process of this embodiment, firstly, the width of the workpiece is rolled using a Box pass. Then, the workpiece is bent into a cap shape and rolled for thickness using a K8 pass. Next, the thickness is further rolled using a K7 pass, shaping it into a shape close to the product's cross-sectional shape. The K8 and K7 passes used in the roughing process are used for multi-pass rolling. Furthermore, the lateral movement of the workpiece between the K8 and K7 passes on the mill inlet side is achieved by a displacement device (parallel guide or dog). This lateral movement of the workpiece is also performed in the intermediate mill 5 and the finishing mill 6.

[0029] The intermediate rolling mill 5 uses multiple passes to perform intermediate rolling on the rough-formed workpiece. Intermediate rolling is performed by return rolling. In this embodiment, as an example, intermediate rolling is performed in tandem using two rolling mills 5A and 5B in the second and third passes. Tandem rolling has the advantage of shorter rolling time compared to rolling using a single mill.

[0030] Here, Figure 4A shows an example of the pass pattern used in rolling mill 5A. Rolling mill 5A is located further downstream than rolling mill 5B. Pass patterns K6 and K3 are formed in the upper roll 51A and lower roll 52A. Furthermore, Figure 4B shows an example of the pass pattern used in rolling mill 5B. Pass patterns K5 and K4 are formed in the upper roll 51B and lower roll 52B.

[0031] In the intermediate rolling process of this embodiment, rolling is performed using a K6 pass in the first intermediate rolling pass (from upstream to downstream) (K5 rolling is optional and no rolling is applied). In the second pass, which is the opposite direction of rolling to the first pass, tandem rolling is performed using the K6 and K5 passes. Furthermore, in the third pass (from upstream to downstream), tandem rolling is performed using the K4 and K3 passes.

[0032] The finishing mill 6 uses multiple passes to finish-roll the intermediate-rolled material into a cap-shaped sheet pile 1 with a cross-section that achieves the target product dimensions. Figure 5 shows an example of the passes used in the finishing mill 6. Two passes, K1 and K2, are formed in the upper roll 61 and lower roll 62. In the finishing rolling, a three-way return rolling process is performed. In the first pass (from upstream to downstream), horizontal rolling is performed using the K2 pass; in the second pass (from downstream to upstream), horizontal rolling and claw bending are performed using the K1 pass. The final third pass (from upstream to downstream) is a surface finishing roll using the K1 pass.

[0033] <Rolling Control Device> Here, the rolling control device used to control the roughing mill 4, the intermediate mill 5, and the finishing mill 6 will be described. Figure 6 is a structural diagram showing an example of the rolling control device. The rolling control device 7 shown in Figure 6 includes a camera 71, an image analysis device 72, a process computer 73, a roughing control unit 74, an intermediate rolling control unit 75, and a finishing control unit 76.

[0034] Camera 71 is a photographing device used to photograph the workpiece being rolled; in the example of Figure 6, it is set in the intermediate rolling mill 5. Image analysis device 72 imports the image data IMD of the workpiece being rolled captured by camera 71 and calculates the bending amount of the workpiece. The bending amount calculation data BCD, as the bending amount calculation result, is sent from image analysis device 72 to process computer 73.

[0035] The process computer 73 comprehensively controls the roughing rolling control unit 74, the intermediate rolling control unit 75, and the finishing rolling control unit 76. The roughing rolling control unit 74 controls the roughing mill 4. Specifically, it controls the rolling position and speed of the rolls in the roughing mill 4. The intermediate rolling control unit 75 controls the intermediate rolling mill 5. Specifically, it controls the rolling position and speed of the rolls in the intermediate rolling mill 5. The finishing rolling control unit 76 controls the finishing mill 6. Specifically, it controls the rolling position and speed of the rolls in the finishing mill 6.

[0036] Figure 6 shows a functional block inside the intermediate rolling control unit 75 for controlling the bending of the workpiece being rolled. This bending control is one of the controls performed by the intermediate rolling control unit 75. Bending control is the control that suppresses bending of the workpiece being rolled. As this functional block, the intermediate rolling control unit 75 includes a leveling amount correction value determination unit 75A, a leveling amount setting unit 75B, and a rolling control unit 75C. The leveling amount correction value determination unit 75A calculates a correction value for the leveling amount based on the bending amount calculation data BCD sent by the self-developed process computer 73. The leveling amount setting unit 75B sets the leveling amount based on the calculated correction value. The rolling control unit 75C controls the rolling device installed in the intermediate rolling mill 5 based on the set leveling amount. The leveling amount is controlled by controlling the rolling device.

[0037] <Regarding the leveling amount> Here, the leveling amount will be described. Furthermore, here, the intermediate rolling mill 5 is taken as an example for the description, but the same also applies to the rough rolling mill 4 and the finishing rolling mill 6. In the intermediate rolling mill 5 (specifically, in each of the rolling stands 5A and 5B), a rolling pressure device capable of adjusting the leveling amount is provided. The so-called leveling amount refers to the opening difference between the left and right rolling pressure positions in the rolling mill.

[0038] Here, FIGS. 7A and 7B are diagrams showing the upper roll 51 and the lower roll 52 in the intermediate rolling mill 5. Furthermore, the upper roll 51 and the lower roll 52 represent the rolls of the rolling stands 5A and 5B, respectively.

[0039] As shown in FIGS. 7A and 7B, when the right side of the axes of the upper and lower rolls 51 and 52 is set as the OP (operation) side (also referred to as the work side), and the left side of the axes is set as the DR (drive) side, the OP-side rolling pressure position S2 is the opening of the chock position (or roll collar position) on the OP side. Moreover, the DR-side rolling pressure position S1 is the opening at the chock position (or roll collar position) on the DR side. And the so-called leveling amount Lv refers to the difference between the DR-side rolling pressure position S1 and the OP-side rolling pressure position S2, which is expressed as Lv = S1 - S2. That is, as shown in FIG. 7A, when the upper roll 51 and the lower roll 52 are parallel, the leveling amount Lv = 0. As shown in FIG. 7B, when the upper roll is inclined toward the DR side, S1 < S2, and the leveling amount Lv becomes a negative value. On the other hand, when the upper roll is inclined toward the OP side, S1 > S2, and the leveling amount Lv becomes a positive value.

[0040] <Setting position of the camera> In the present embodiment, as an example, in order to grasp the bending of the material to be rolled between the rolling stands 5A and 5B in the intermediate rolling mill 5, a camera 71 is provided between the rolling stands 5A and 5B. The setting position of the camera 71 will be described using FIGS. 8, FIG. 9, and FIG. 10. FIGS. 8, FIG. 9, and FIG. 10 are side view, top view, and front view, respectively, showing the setting position of the camera 71 relative to the intermediate rolling mill 5. Furthermore, the upstream side US and the downstream side DS are shown in FIGS. 8 and FIG. 9.

[0041] As shown in Figure 8, camera 71 is positioned above intermediate rolling mill 5. The vertical distance L1 from the shooting position of camera 71 to the manufacturing line ML is, for example, 4 m to 5 m. As shown in Figure 9, guides 8A, 8B, 8C, and 8D are provided in intermediate rolling mill 5. Guides 8A and 8C are provided on the upstream side US of rolls 51A and 52A in rolling mill 5A. Guides 8A and 8C are arranged in a left-right direction. Guide 8A is configured corresponding to the K3 pass formed on rolls 51A and 52A, and guide 8C is configured corresponding to the K6 pass formed on rolls 51A and 52A.

[0042] Downstream of rolls 51B and 52B in the rolling mill 5B, guides 8B and 8D are provided. Guides 8B and 8D are arranged in a left-right direction. Guide 8B is arranged corresponding to the K4 pass formed on rolls 51B and 52B, and guide 8D is arranged corresponding to the K5 pass formed on rolls 51B and 52B.

[0043] As shown in Figure 10, guides 8A and 8B each have an upper guide 81, a lower guide 82, and a pair of side guides 83. The upper guide 81 and the lower guide 82 are sandwiched between the pair of side guides 83 in the left-right direction. A passage 84 is formed between the upper guide 81 and the lower guide 82 for the rolling material MR to pass through. Furthermore, guides 8C and 8D are constructed in the same manner as guides 8A and 8B.

[0044] Here, the guide on the rolling exit side restricts the warping and bending of the workpiece while guiding it. Furthermore, the guide on the rolling inlet side guides the workpiece in conjunction with the roll pass. The left-right positions of the guides are configured such that the center position of the guide's passage in the left-right direction coincides with the center position of the corresponding roll pass in the left-right direction. Moreover, the long side (rolling direction) end of the guide is configured such that its left-right direction is parallel to the axis extending in the left-right direction of the corresponding roll. For example, the long side end 85 (Fig. 9) of each guide 8A and guide 8B is configured to be parallel to the axes of rolls 51A and 52A, and the axes of rolls 51B and 52B, respectively.

[0045] Furthermore, as shown in Figure 9, the camera 71 is positioned between guides 8A and 8B when viewed from above. As shown in Figure 8, the camera 71 captures the long-side gap L2 (e.g., L2 = 200 mm) between guides 8A and 8B. This allows the camera 71 to capture images of the leading edge of the rolled material in the long-side direction, for example, on the rolled-out side during rolling using a K4 pass, i.e., the material being fed downstream from guide 8B to the downstream side DS.

[0046] Furthermore, the camera 71 can also be positioned below the intermediate rolling mill 5.

[0047] <Bending Control> Next, the bending control using camera 71 will be explained. Figure 11 is a flowchart showing the bending control processing flow. Here, Figure 12 shows the structure of the image analysis device 72 (Figure 6). The image analysis device 72 includes an image acquisition unit 72A, an image storage unit 72B, an image processing unit 72C, a calculation unit 72D, and a control unit 72E. The image acquisition unit 72A acquires image data IMD captured by camera 71. The image storage unit 72B stores the acquired image data IMD. The image processing unit 72C performs image processing on the stored image data IMD. The calculation unit 72D calculates the bending amount based on the image processing results and outputs bending amount calculation data BCD. The control unit 72E controls the image analysis device 72.

[0048] <<Methods for Calculating Bending Amount>> The bending control process will be explained along with Figure 11. First, when the process in Figure 11 begins, the camera 71 starts capturing images, and the image acquisition unit 72A acquires image data IMD sequentially. In this state, the control unit 72E monitors whether the workpiece has entered the shooting range of the camera 71 based on the acquired image data IMD (step S1). For example, when the workpiece rolled through the K4 pass in the rolling mill 5B enters the shooting range of the camera 71 via the guide 8B on the rolling end side, a brightness change occurs due to the self-illumination of the workpiece during hot rolling. Therefore, the control unit 72E detects the workpiece by detecting the brightness change of the image data IMD.

[0049] If a piece of material to be rolled is detected (yes in step S1), then in step S2, the control unit 72E outputs a trigger signal to the image storage unit 72B. Thereby, the image storage unit 72B stores image data IMD covering a predetermined period before and after the detected event. Thus, an image of the front end of the piece of material to be rolled, obtained by photographing the front end along its long side, is acquired (step S3).

[0050] Next, proceeding to step S4, the image processing unit 72C performs image processing on the acquired front-end image. Figure 13 is a diagram showing an example of an image containing the front-end image IM_MR. The captured image also includes the guide image IM_GD obtained by capturing the guide 8B. Furthermore, Figures 13 and 14 also illustrate the OP side and the DR side. The image processing unit 72C extracts the brightest portion of the captured image as the front-end image IM_MR and performs contour processing on it.

[0051] The contour line L_MR extracted by contour line processing is shown in Figure 14. The points where the lines of the left and right width directions Lop and Ldr in the contour line L_MR disappear at the front end in the long side direction are designated as the end representative points Pop on the Op side and Pdr on the Dr side, respectively. The long side positions of these representative points are designated as A2 and A1, respectively, and their difference (A1-A2) is designated as the long side position difference ΔA. The long side position difference ΔA represents the bending amount of the rolled material. The calculation unit 72D calculates the long side position difference ΔA and outputs the calculation result as bending amount calculation data BCD. Furthermore, the long side position difference ΔA can also be called the difference in extension amount.

[0052] Furthermore, as a specific method for accurately determining the long-side direction positions A2 and A1, the camera 71 captures images of the long-side end of the guide 8B (a first reference object extending in the left-right direction). Figure 13 shows the image IM_GT of the long-side direction end. Based on the image IM_GT of the long-side direction end, the image processing unit 72C determines a first reference line BL1 that is perpendicular to the rolling direction (long-side direction) and extends in the left-right direction. The first reference line BL1 is illustrated in Figure 14. The image processing unit 72C determines the long-side direction positions A2 and A1, respectively, based on the long-side direction lengths of the representative point Pop and the representative point Pdr from the first reference line BL1.

[0053] Furthermore, the first reference object does not necessarily need to be a guide, but it is simpler and better to use the guide provided on the rolling end.

[0054] Furthermore, a center line (second reference object) extending along the long side direction can be drawn on the upper part of the guide 8B to determine the center position of the K4 die in the left and right directions. At this time, the center line is captured by the camera 71. Figure 13 shows the center line image IM_CL obtained by capturing the center line. The image processing unit 72C determines the second reference line BL2 extending along the rolling direction (long side direction) (Figure 14) based on the center line image IM_CL. Furthermore, the left and right positions of the left and right joints in the front end of the long side direction of the rolled material can be determined, and the bending amount can be calculated. Specifically, as shown in Figure 14, the image processing unit 72C determines the length from the second reference line BL2 to the representative point Pdr as the left and right position C1, and the length from the second reference line BL2 to the representative point Pop as the left and right position C2. Furthermore, the calculation unit 72D calculates the difference ΔC between the left and right positions as ΔC=C1-C2, thereby calculating the bending amount.

[0055] Furthermore, the calculation of the bending amount can be performed by calculating either the difference in position along the long side ΔA or the difference in position along the left and right sides ΔC, or by calculating both. In the case of calculating both, the bending amount calculation data BCD becomes the data representing both ΔA and ΔC.

[0056] <<Variations related to representative points of the left and right joints>> The representative points of the left and right joints can also be determined using the following method. Here, the image processing unit 72C performs image processing on the front end image IM_MR to extract the contour lines LTdr and LTop (Fig. 14) of the front end side in the long side direction of the left and right joints. Furthermore, the image processing unit 72C determines the center points of the contour lines LTdr and LTop as representative points PCdr and PCop, respectively. The size of the joint and arm of the rolled material is determined by the size (series) of the sheet pile. Therefore, if the camera 71 is fixed, the extent to which the left and right ends of the joint and arm are included in the captured image can be predetermined according to the size of the sheet pile. Therefore, a fixed range from the Op side end in the leading edge line of the contour line L_MR of the rolled material can be determined as the Op side end, and the center point of this range can be set as the representative point PCop of the Op side end. Furthermore, a fixed range starting from the Dr side end can be defined as the Dr side end of the rolled material, and the center point of this range can be set as the representative point PCdr of the Dr side end. This method is particularly effective when the disappearance locations of the width direction end Lop and width direction end Ldr in the contour line L_MR of the front end image IM_MR are unclear.

[0057] Furthermore, points in the leading edge of the contour line L_MR where the direction of extension from the Op or Dr side changes midway can be detected as bending points (points connecting the arm and the flange), and these bending points can be set as representative points for the Op and Dr sides respectively.

[0058] <<Representative Points in the Case of Other Steels>> If the steel is not sheet pile but flat steel, simply set the points where the lines at the ends of the outline of the front end of the long side of the rolled material disappear at the front end of the long side as the end representative points on the Op side and the Dr side, respectively.

[0059] Furthermore, when the steel is, for example, H-beams, I-beams, or channel steel, the left and right flange portions can be used as the left and right ends of the front end portion along the long side of the rolled material. That is, a fixed range from the Op side end of the portion of the outline of the front end portion along the long side, which becomes the leading edge line, can be defined as the Op side flange end, and the center point of this range can be set as the representative point of the Op side flange portion. Similarly, a fixed range from the Dr side end can be defined as the Dr side flange end, and the center point of this range can be set as the representative point of the Dr side flange portion.

[0060] <<Leveling and Adjustment>> Here, we return to the explanation using Figure 11. After calculating the bending amount as described above, we proceed to step S5. Here, the bending amount calculation data BCD is sent to the intermediate rolling control unit 75 via the process computer 73, and the leveling amount correction value determination unit 75A (Figure 6) calculates the leveling amount correction value based on the bending amount calculation data BCD. That is, the leveling amount correction value ΔLv is calculated based on the difference in position along the long side calculated above. The relationship between the leveling amount correction value ΔLv and the difference in position along the long side ΔA is expressed using a proportionality constant K as ΔLv = K·ΔA.

[0061] Then, proceeding to step S6, the leveling amount setting unit 75B determines the leveling amount setting value for the next rolling (specifically, the next rolling by the K4 pass) based on the leveling amount correction value ΔLv calculated above using the following formula. Lv'=Lv+ΔLv Where Lv' is the set value of the leveling amount in the next rolling, and Lv is the set value of the leveling amount in this rolling.

[0062] When the elongation on the OP side is large, that is, when A2 > A1, before rolling the material to be rolled using the next rolling pass, the upper roll 51B in the rolling stand 5B is tilted toward the DR side or the lower roll 52B is tilted toward the OP side in advance. On the other hand, when the elongation on the DR side is large, that is, when A2 < A1, before rolling the material to be rolled using the next rolling pass, the upper roll 51B in the rolling stand 5B is tilted toward the OP side or the lower roll 52B is tilted toward the DR side in advance. Thereby, the difference in elongation between the left and right can be reduced, and bending can be suppressed.

[0063] Similarly, when using the difference ΔC in the left - right direction position, the leveling amount correction value can be determined by setting ΔLv = M·ΔC using the proportional constant M. Alternatively, both ΔA and ΔC can be used and set as ΔLv = K'·ΔA + M'·ΔC (K' and M' are proportional constants).

[0064] And, the rolling pressure control unit 75C controls the rolling pressure device in the rolling stand 5B based on the set leveling amount, thereby adjusting the bending of the material to be rolled

[0065] <<Setting of Proportional Constant>> Here, an example of setting the proportional constant K will be described. In the case of 10H of Series 1 of the hat - shaped steel sheet pile, it is photographed by a camera. Furthermore, this is the photographing during the third pass in the intermediate rolling (on the exit side of the K4 pass and the entrance side of the K3 pass). In this example, the longitudinal direction position A1 of the joint part on the DR side = 30 mm, and the longitudinal direction position A2 of the joint part on the OP side = 90 mm. Therefore, the difference in the longitudinal direction position ΔA = - 60 mm. At this time, the bending was improved with the leveling amount correction value ΔLv = - 0.6 mm. Therefore, in the case of the hat - shaped steel sheet pile, the proportional constant K can be set as K = ΔLv / ΔA = 0.01.

[0066] <<Thrust Adjustment>> In addition to the leveling adjustment, the thrust adjustment of the roll can also be performed. The thrust adjustment of the roll refers to a method of relatively adjusting the axial position of one of the upper and lower rolls with respect to the other roll. By the thrust adjustment, the roll gap for rolling the left and right flange parts and the joint part changes left and right, so that the bending of the steel sheet pile having a joint part can be adjusted.

[0067] <<Applicable Object>> Furthermore, the bending control of the present invention is not limited to cap-shaped sheet piles, but can be applied to sheet piles with joints on the left and right sides. That is, it can also be applied to the aforementioned U-shaped sheet piles (Figure 1B) or straight sheet piles (Figure 1C).

[0068] <Example> This example illustrates a 10H dimension of a cap-type sheet pile. For the intermediate rolled third pass, images are taken between the rows (the exit side of the K4 pass and the entry side of the K3 pass), the bending amount is calculated, and the leveling amount is adjusted based on the bending amount to confirm the bending condition. The method for confirming the bending is as follows. (a) Determine whether finish rolling is possible based on the bending condition after intermediate rolling. (b) Evaluate the amount of bending over a 10 m product length selected from the front end along the long side. Furthermore, regarding (b), there is still some bending residue from intermediate rolling in the product, and a bending amount of less than 10 mm / 10 m is considered acceptable. Figure 15 shows the definition of the bending amount BD in the product (cap-shaped sheet pile 1).

[0069] Figure 16 shows the results of this embodiment in the table. In the first rolling pass, shape rolling (rolling under initial conditions) is performed, and bending is evaluated. At this time, the bending after intermediate rolling is too large to perform finish rolling.

[0070] In the second to fifth rolling passes, the bending control method of this invention is applied. That is, the leveling in the K4 pass rolling is adjusted based on the calculated bending amount (the difference in position along the long side ΔA) (assuming a proportional constant K=0.01). As a result, after the second pass, the bending after intermediate rolling is improved, and the bending of the product is within acceptable limits.

[0071] Furthermore, an example was given: For the sixth to ninth rolling passes, the operator set the leveling amount for passes six onwards based on a visual assessment of the bending after the intermediate rolling of the first pass. Since the bending on the K4 pass side was unknown to the operator, the leveling amount for the sixth pass was set to 0 mm. For the seventh pass, the condition of the sixth pass was also taken into account, and similarly, for the eighth pass, the condition of the seventh pass was also considered when adjusting the leveling amount. As a result, by the eighth pass, the bending in the product was finally within acceptable limits.

[0072] Furthermore, the table in Figure 16 also shows ΔC as the calculated value for the bending amount. Figure 17 shows the following graph, which illustrates the relationship between the difference in position along the long side of Figure 16, ΔA, and the leveling amount, Lv. Figure 18 shows the following graph, which illustrates the relationship between the difference in position along the left and right sides of Figure 16, ΔC, and the leveling amount, Lv. It can be seen that, similar to ΔA, ΔC can also be used to determine the leveling amount.

[0073] <<Applicable Parts for Bending Calculation>> In the example described, a camera 71 is installed between rolling mills 5A and 5B in the intermediate rolling mill 5 to calculate the bending amount on the K4 pass exit side. This invention is not limited to this; the camera can also be installed downstream of rolling mill 5A, for example. In this case, the bending amount on the K3 pass exit side in the third pass of intermediate rolling can be calculated, for example. Alternatively, the invention can be applied to a single rolling mill such as a roughing mill 4 or a finishing mill 6. However, for rolling mills in tandem rolling, such as between rolling mills 5A and 5B, the requirements for the equipment are more stringent. Therefore, it is significant to apply the invention, which allows for the calculation of bending amount using simple equipment.

[0074] Furthermore, when re-rolling is performed as in intermediate rolling, it is preferable to utilize as many intermediate rolling stages as possible to adjust the bending. Therefore, for example, as shown in FIG19, in addition to camera 71, camera 77 can also be installed between guides 8C and 8D in the intermediate rolling mill 5. At this time, for example, the amount of bending on the K6 pass rollout side (upstream side of guide 8C) in the second pass can be calculated, and the bending in the K6 pass rolling can be adjusted.

[0075] <<About Bending Determination>> Figure 20 is a diagram showing the structure of a modified example of the rolling control device 7 shown in Figure 6. Here, in addition to the structure in Figure 6, a determination unit 73A is also provided in the process computer 73, and a monitor device 78 is further provided.

[0076] The determination unit 73A performs a bending determination based on the bending amount calculation data BCD. Specifically, it compares the difference in position along the long side ΔA or the difference in position along the left and right sides ΔC with a predetermined threshold value. If the bending amount is determined to be large, the determination unit 73A causes the monitoring device 78 to issue a warning. Alternatively, ΔA and ΔC can also be compared with their respective threshold values.

[0077] 1: Hat-shaped steel sheet piles 1X: U-shaped steel sheet piles 1Y: Straight Steel Sheet Piles 2: Hot rolling equipment 3: Heating furnace 4: Roughing rolling mill 5: Intermediate rolling mill 5A, 5B: Rolling Mill 6: Finishing rolling mill 7: Rolling control device 8A~8D: Guide 11: Web 12: Flange 13: Arms 14: Connector 41, 51, 51A, 51B, 61: Upper roller 42, 52, 52A, 52B, 62: Lower roller 71: Camera 72: Image Analysis Device 72A: Image Acquisition Unit 72B: Image Storage Unit 72C: Image Processing Unit 72D: Arithmetic Unit 72E: Control Unit 73: Process Computer 73A: Judgment Department 74: Rough Rolling Control Department 75: Intermediate Rolling Control Section 75A: Leveling Adjustment Correction Value Determination Department 75B: Leveling Amount Setting Section 75C: Rolling Control Section 76: Finishing Rolling Control Department 77: Camera 78: Monitoring device 81: Upper guide 82: Lower guide 83: Side guide 84:Pathway 85: End of the long side A1, A2: Position along the longer side BCD: Bending Amount Calculation Data BD: Bending amount BL1: First baseline BL2: Second baseline C1, C2: Left and right position DR: Axial left side DS: Downstream side H: Hole type IM_CL: Centerline image IM_GD: Guide image IM_MR: Front end image IM_GT: Image at the end of the longer side IMD: Image Data L1: Distance in the vertical direction L2: Gap in the long side direction L_MR, Tdr, LTop: Contour lines Lop, Ldr: End points in the width direction ML: Manufacturing line MR: Rolled material OP: Axial right side PCdr, PCop: Represents points Pdr, Pop: Endpoints representing points S1: DR side rolling position S2: OP side rolling position S1~S6: Steps US: Upstream side ΔA: Difference in position along the longer side

Claims

1. A method for calculating the bending amount of steel, comprising: calculating the bending amount of steel rolled by a rolling mill, the method comprising: The method includes a shooting step, in which the front end of the steel on the exit side of the rolling mill is photographed from above or below using a shooting device; an extraction step, in which the shape related to the left and right ends of the front end of the steel on the exit side of the rolling mill is extracted from the image of the front end of the steel on the exit side of the rolling mill; and a calculation step, in which the difference in the long-side position and / or the difference in the left and right positions of the left and right ends is calculated based on the extracted shape, thereby calculating the bending amount. In the shooting step, a second reference object is photographed to determine the left and right center positions of the roll pass. The method for calculating the bending amount of the steel further includes a determination step, in which a second reference line for determining the left and right positions of the left and right ends is determined based on the image of the second reference object.

2. The steel bending amount calculation method as described in claim 1, wherein in the shooting step, a first reference object is photographed perpendicular to the long side direction and extending in the left-right direction, and the steel bending amount calculation method further includes a determination step, wherein the determination step is based on the image of the first reference object to determine a first reference line for determining the long side direction position of the left and right ends.

3. The method for calculating the bending amount of steel as described in claim 1 or 2, wherein the steel is a sheet pile having a web and joints at both ends in the width direction, and the left and right ends are the ends including the left and right joints.

4. The method for calculating the bending amount of steel as described in claim 1 or 2, wherein the imaging device is configured between the rolling mill used for tandem rolling and a rolling mill different from the rolling mill.

5. A method for manufacturing steel, wherein, based on a calculated value obtained using the steel bending amount calculation method as described in claim 1 or 2, the rolls of the rolling mill are rolled by changing the skewness of the rolls and / or the relative axial positions of the upper and lower rolls in the next rolling of the steel.

6. A method for determining the bending of steel, wherein the bending of the steel is determined based on a calculated value obtained using the steel bending amount calculation method as described in claim 1 or 2.

7. A steel bending amount calculation device for calculating the bending amount of steel rolled by a rolling mill, the steel bending amount calculation device comprising: A camera is positioned on the outlet side of the rolling mill and takes pictures of the steel from above or below. The image processing unit extracts the shape related to the left and right ends of the front end of the long side direction from the image of the front end of the steel obtained by taking a picture, and determines the second reference line for determining the left and right position of the left and right ends based on the image of the second reference object used to determine the left and right center position of the roll pass obtained by taking a picture; and the calculation unit calculates the difference between the rolling long side position of the left and right ends and / or the difference between the left and right positions based on the extracted shape, thereby calculating the bending amount.

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