Method for calculating amount of curvature of steel material, method for manufacturing steel material, method for determining curvature of steel material, and device for calculating amount of curvature of steel material

Abstract

To provide a method for calculating an amount of curvature of steel material, the method enabling an amount of curvature of steel material even under conditions in which the installation range for equipment is narrow, and the method enabling accurate recognition of an amount of curvature of steel material using simple equipment configuration.SOLUTION: There is provided a method for calculating an amount of curvature of steel material rolled by a rolling mill, the method includes: a photographing step in which a leading end portion in the longitudinal direction of the steel material on a delivery side of the rolling mill is photographed by a photographing device that photographs the steel material from above or from below on the delivery side of the rolling mill; an extraction step in which shape related to left and right end portions of the leading end portion in the longitudinal direction is extracted from an image of the leading end portion in the longitudinal direction of the steel material obtained by the photographing; and a calculation step in which a difference in position in the longitudinal direction and / or a difference in lateral position between the left and right end portions are calculated on the basis of the extracted shape.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for calculating the amount of bending of a steel material, a method for manufacturing a steel material, a method for determining the bending of a steel material, and an apparatus for calculating the amount of bending of a steel material. [Background technology]

[0002] In the past, bending of steel materials sometimes occurred during the rolling process of steel materials. Since such bending of steel materials affects product yield and productivity, it is desirable to suppress it. In order to perform control to suppress bending of steel materials, it is necessary to accurately detect bending of steel materials.

[0003] For example, Patent Document 1 discloses the following method for calculating the amount of bending of a steel plate. In Patent Document 1, a two-dimensional imaging element such as a CCD camera is provided above the delivery side of a rolling mill, and an image of the hot steel plate is taken. Various image processing operations are performed on this steel plate image to extract the outline of the steel plate. Then, coordinates of the center position in the width direction of the steel plate are obtained along the longitudinal direction of the steel plate (see Figure 2 of Patent Document 1), and the amount of bending is calculated using this coordinate data.

[0004] Furthermore, as a method for measuring the amount of bending of structural steel, for example, Patent Document 2 discloses a method in which a pair of distance sensors are arranged in a horizontal direction perpendicular to the direction of travel of the H-shaped steel, and each sensor measures the distance to the outer surface of the flange of the H-shaped steel while it is traveling, and the amount of bending is detected from these measured values.

[0005] Furthermore, as a method for measuring the bending of structural steel, for example, Patent Document 3 discloses a method in which the widthwise brightness distribution is calculated in multiple cross sections at regular intervals in the longitudinal direction from an image of the structural steel taken from above, the bending portion in each cross section is detected, and then the widthwise positions of the bending portions are connected in the longitudinal direction to calculate a bending profile along the longitudinal direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 1999-28510 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-234540 [Patent Document 3] Japanese Patent Application Publication No. 2019-178901 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the above-mentioned conventional techniques have the following problems to be solved. That is, the technique disclosed in Patent Document 1 is a bending measurement technique for steel plates, and is not a technique applicable to steel materials in general, including steel sheet piles. In addition, the amount of bending cannot be determined from an image of only the tip of the steel plate, and an image of the steel plate that captures a certain range in the longitudinal direction is required to calculate the amount of bending.

[0008] Furthermore, the technology disclosed in Patent Document 2 requires a special measuring device with a distance sensor. Furthermore, distance sensor data is required along the longitudinal direction of the structural steel, but accurate measurement is not possible if the structural steel is warped in the vertical direction during measurement.

[0009] Furthermore, the technology disclosed in Patent Document 3 accurately measures bending along the longitudinal direction by capturing images of the rolled material over a wide range, and is not suitable for locations where only a limited range can be captured, such as between rolling stands in tandem rolling.

[0010] In view of the above circumstances, the present invention aims to provide a steel material bending amount calculation method and a steel material bending amount calculation device that can measure the amount of bending of a steel material even under conditions where the area in which the equipment can be installed is narrow and that can accurately grasp the amount of bending of a steel material with a simple equipment configuration. It is also an object of the present invention to provide a steel material manufacturing method and a steel material bending determination method that use the above steel material bending calculation method. [Means for solving the problem]

[0011] A steel material bending amount calculation method according to one aspect of the present invention is a steel material bending amount calculation method for calculating a bending amount of a steel material rolled by a rolling mill, an imaging step of imaging a longitudinal tip end portion of the steel material at the delivery side of the rolling mill by an imaging device that images the steel material from above or below at the delivery side of the rolling mill; An extraction step of extracting shapes relating to left and right ends of the longitudinal tip portion from an image of the longitudinal tip portion of the steel material obtained by photographing; and a calculation step of calculating the difference in longitudinal position of the left and right end portions and / or the difference in left and right position based on the extracted shape to calculate the amount of bending (first configuration).

[0012] In the first configuration, in the photographing step, a first reference object extending in the left-right direction and perpendicular to the longitudinal direction is photographed; The method may further include a determining step of determining, based on an image of the first reference object, a first reference line for identifying the longitudinal positions of the left and right ends (second configuration).

[0013] In the first configuration, in the photographing step, a second reference object for specifying the left-right center position of the roll groove is photographed, The method may further include a determining step of determining, based on an image of the second reference object, second reference lines for identifying the left-right positions of the left and right ends (third configuration).

[0014] In addition, in any one of the first to third configurations, the steel material is a steel sheet pile having a web and joint portions at both left and right ends in the width direction, The left and right end portions may be end portions including the left and right joint portions (fourth configuration).

[0015] In addition, in any of the above first to fourth configurations, the photographing device may be configured to be placed between the rolling mill and another rolling mill to perform tandem rolling (fifth configuration).

[0016] In addition, a method for manufacturing steel according to one embodiment of the present disclosure involves changing the inclination of the rolls of the rolling mill and / or the relative axial positions of the upper and lower rolls of the rolling mill in the next rolling of the steel based on the calculated value calculated using the steel bending amount calculation method of any one of the first to fifth configurations (sixth configuration).

[0017] In addition, a method for determining the bending of steel material according to one embodiment of the present disclosure determines the bending of the steel material based on a calculated value calculated using a steel material bending amount calculation method of any one of the first to fifth configurations described above (seventh configuration).

[0018] Further, a steel material bending amount calculation device according to an aspect of the present disclosure is a steel material bending amount calculation device that calculates a bending amount of a steel material rolled by a rolling mill, an imaging device that is installed on the delivery side of the rolling mill and that images the steel material from above or below; an image processing unit that extracts shapes of left and right ends of the longitudinal tip portion of the steel material from an image of the longitudinal tip portion obtained by photographing the steel material; and a calculation unit that calculates the amount of bending by calculating the difference in the rolling direction positions of the left and right end portions and / or the difference in the left and right direction positions based on the extracted shape (eighth configuration). [Effects of the Invention]

[0019] According to the present invention, it is possible to measure the amount of bending of steel materials even under conditions where the area in which equipment can be installed is narrow, and the amount of bending of steel materials can be accurately determined with a simple equipment configuration. [Brief explanation of the drawings]

[0020] [Figure 1A] FIG. 1A is a diagram showing the cross-sectional shape of a hat-shaped steel sheet pile. [Figure 1B] FIG. 1B is a diagram showing the cross-sectional shape of a U-shaped steel sheet pile. [Figure 1C] FIG. 1C is a diagram showing a cross-sectional shape of a straight steel sheet pile. [Figure 2]FIG. 2 is a diagram showing an example of a schematic configuration of hot rolling equipment for steel sheet piles. [Figure 3] FIG. 3 is a diagram showing an example of a groove used in a roughing mill. [Figure 4A] FIG. 4A is a diagram showing an example of a groove used in an intermediate rolling mill. [Figure 4B] FIG. 4B is a diagram showing an example of a groove used in an intermediate rolling mill. [Figure 5] FIG. 5 is a diagram showing an example of a groove used in a finishing rolling mill. [Figure 6] FIG. 6 is a configuration diagram showing an example of a rolling control device. [Figure 7A] FIG. 7A is a diagram showing the top roll and bottom roll of an intermediate rolling mill. [Figure 7B] FIG. 7B is a diagram showing the top roll and bottom roll of the intermediate rolling mill. [Figure 8] FIG. 8 is a side view showing the installation position of the camera relative to the intermediate rolling mill. [Figure 9] FIG. 9 is a top view showing the installation position of the camera relative to the intermediate rolling mill. [Figure 10] FIG. 10 is a front view showing the installation position of the camera relative to the intermediate rolling mill. [Figure 11] FIG. 11 is a flowchart showing the flow of the curve control process. [Figure 12] FIG. 12 is a diagram showing the configuration of an image analysis device. [Figure 13] FIG. 13 is a diagram showing an example of a captured image including a tip image. [Figure 14] FIG. 14 is a diagram showing contours extracted by the contour line processing. [Figure 15] FIG. 15 is a diagram showing the definition of the amount of bending in a product (hat-shaped steel sheet pile). [Figure 16] FIG. 16 is a table showing the results of the example. [Figure 17] FIG. 17 is a graph showing the relationship between the difference in longitudinal position and the leveling amount in FIG. [Figure 18]FIG. 18 is a graph showing the relationship between the difference in left-right direction position and the leveling amount in FIG. [Figure 19] FIG. 19 is a top view showing the installation positions of the cameras relative to the intermediate rolling mill. [Figure 20] FIG. 20 is a diagram showing the configuration of a rolling control device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that 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 does not limit the materials, shapes, structures, arrangements, etc. of component parts to the following embodiments. Also, the drawings are schematic. Therefore, it should be noted that the relationships and ratios between thicknesses and planar dimensions differ from the actual ones, and the drawings also include portions where the relationships and ratios of dimensions differ from each other.

[0022] <Outline of steel sheet piles and their rolling manufacturing methods> 1A, 1B, and 1C are diagrams showing the cross-sectional shapes of various steel sheet piles. As shown in FIG. 1A, a hat-shaped steel sheet pile 1 manufactured in this embodiment has a uniform hat-shaped cross-sectional shape perpendicular to the longitudinal direction. The hat-shaped steel sheet pile 1 has a cross-sectional shape including a web 11, a pair of flanges 12, a pair of arm portions 13, and a pair of joint portions 14. The web 11 is a portion extending 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 at an angle relative to the left-right direction. In the example shown in FIG. 1A, the pair of flanges 12 extend at an angle so that the ends opposite to the web 11 side are lower in the up-down direction (direction perpendicular to the left-right direction). The pair of arm portions 13 are connected to the sides of the pair of flanges 12 to which the web 11 is not connected and extend in the left-right direction. The pair of joints 14 are connected to the sides of the pair of arm portions 13 to which the flanges 12 are not connected, and have a hook-like shape that opens upward or downward in the vertical direction. When used as a steel sheet pile, the pair of joints 14 are fitted into joints of another steel sheet pile, thereby being used to connect to another steel sheet pile.

[0023] The present invention is also applicable to the manufacture of steel sheet piles other than hat-shaped steel sheet piles. Fig. 1B shows a U-shaped steel sheet pile 1X. The U-shaped steel sheet pile 1X has a configuration in which the arm portion 13 is omitted from the hat-shaped steel sheet pile 1. Furthermore, a pair of joint portions 14 in the U-shaped steel sheet pile 1X both open upward. Furthermore, Fig. 1C shows a straight steel sheet pile 1Y. The straight steel sheet pile 1Y has a configuration in which a pair of joint portions 14 are connected to both ends of a web 11 extending in the left-right direction. The pair of joint portions 14 open in the left-right direction.

[0024] Furthermore, the steel material to which the present invention is applicable is not limited to steel sheet piles. As long as the cross-sectional shape of the steel material can be considered to be approximately symmetrical, the bending amount can be calculated and the steel material can be rolled based on the calculated bending amount, as in the case of steel sheet piles. For example, steel materials other than steel sheet piles include H-beams, I-beams, channel steel, and flat steel.

[0025] Next, a rolling line used for manufacturing the hat-type steel sheet pile 1 will be described. FIG. 2 is a diagram showing an example of a schematic configuration of a hot rolling facility for a steel sheet pile, which is a manufacturing device for a steel sheet pile according to an embodiment of the present invention. The hot rolling facility 2 manufactures the hat-type steel sheet pile 1 by hot rolling. This hot rolling facility 2 is equipped with, from the upstream side to the downstream side, a heating furnace 3, a roughing mill 4, an intermediate rolling mill 5, and a finishing rolling mill 6. The intermediate rolling mill 5 is configured by arranging two rolling stands 5A and 5B in tandem. The direction of the arrow in FIG. 2 indicates the rolling direction.

[0026] The heating furnace 3 heats the slab or bloom, which is the continuously cast raw steel billet, to a predetermined temperature. The raw steel billet heated in the heating furnace 3 is used as the rolling target material and is hot-rolled using multiple grooves in the roughing mill 4, intermediate mill 5, and finishing mill 6 in this order, and is finished into the product shape of the hat-type steel sheet pile 1 shown in Fig. 1A. In these rolling mills, grooves called calibers are formed on the top roll and the bottom roll.

[0027] The roughing mill 4 uses a plurality of grooves to roughly shape the material to be rolled into a cross-sectional shape similar to the product shape. In this roughing rolling process, multiple passes of reverse rolling are performed. Here, FIG. 3 is a diagram showing an example of grooves used in the roughing mill 4. Three grooves, namely, a Box groove, a K8 groove, and a K7 groove, are formed in the top roll 41 and the bottom roll 42.

[0028] In the rough rolling of this embodiment, first, the width of the material to be rolled is reduced in the box groove. Next, the material to be rolled is bent into a hat shape and reduced in thickness in the K8 groove. Furthermore, the thickness is further reduced in the K7 groove, and the material is shaped into a shape close to the cross-sectional shape of the product. In the K8 groove and the K7 groove of the rough rolling, multiple passes of rolling are performed. Note that the material to be rolled is moved left and right between the K8 groove and the K7 groove at the entry side of the rolling mill by a shift device (parallel guide or dog). Such left and right movement of the material to be rolled is also performed in the intermediate rolling mill 5 and the finishing rolling mill 6.

[0029] The intermediate rolling mill 5 uses a plurality of grooves to perform intermediate rolling on the roughly shaped rolling target material. The intermediate rolling is performed by reverse rolling. As an example of the intermediate rolling in this embodiment, tandem rolling is performed using two rolling stands 5A and 5B in the second and third passes. Tandem rolling has the advantage of shortening the rolling time compared to rolling with a single mill.

[0030] Here, FIG. 4A is a diagram showing an example of a groove used in the rolling stand 5A. The rolling stand 5A is arranged downstream of the rolling stand 5B. Two grooves, a K6 groove and a K3 groove, are formed in the upper roll 51A and the lower roll 52A. Also, FIG. 4B is a diagram showing an example of a groove used in the rolling stand 5B. Two grooves, a K5 groove and a K4 groove, are formed in the upper roll 51B and the lower roll 52B.

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

[0032] The finishing rolling mill 6 uses a plurality of grooves to finish-roll the intermediately rolled material to be rolled into a hat-shaped steel sheet pile 1 having a cross section with the target product dimensions. Figure 5 is a diagram showing an example of grooves used in the finishing rolling mill 6. Two grooves, K1 groove and K2 groove, are formed on the top roll 61 and the bottom roll 62. In the finishing rolling, three reverse passes are performed. In the first pass (from upstream to downstream), horizontal rolling is performed using the K2 groove, and in the second pass (from downstream to upstream), horizontal rolling using the K1 groove and bending of the claws are performed. The final third pass (from upstream to downstream) is skin-pass rolling using the K1 groove.

[0033] <Rolling control device> Here, a rolling control device for controlling the roughing mill 4, the intermediate rolling mill 5, and the finishing mill 6 will be described. Fig. 6 is a configuration diagram showing an example of a rolling control device. The rolling control device 7 shown in Fig. 6 has a camera 71, an image analysis device 72, a process computer 73, a roughing rolling control unit 74, an intermediate rolling control unit 75, and a finishing rolling control unit 76.

[0034] The camera 71 is an imaging device for photographing the material to be rolled, and in the example of FIG. 6 is installed on the intermediate rolling mill 5. The image analysis device 72 takes in image data IMD of the material to be rolled photographed by the camera 71 and calculates the amount of bending of the material to be rolled. The bending amount calculation data BCD, which is the calculation result of the amount of bending, is sent from the image analysis device 72 to a process computer 73.

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

[0036] FIG. 6 shows a functional block for controlling the bending of the material to be rolled, which is one of the controls performed by the intermediate rolling control unit 75, inside the intermediate rolling control unit 75. The bending control is a control to suppress bending of the material to be rolled. The intermediate rolling control unit 75 has, as its functional blocks, a leveling amount correction value determination unit 75A, a leveling amount setting unit 75B, and a roll gap control unit 75C. The leveling amount correction value determination unit 75A calculates a correction value for correcting the leveling amount based on the bending amount calculation data BCD sent from the process computer 73. The leveling amount setting unit 75B sets the leveling amount based on the calculated correction value. The roll gap control unit 75C controls the roll gap device provided in the intermediate rolling mill 5 based on the set leveling amount. The leveling amount is controlled by controlling the roll gap device.

[0037] <Leveling amount> Here, the leveling amount will be explained. Here, the intermediate rolling mill 5 will be explained as an example, but the same applies to the roughing mill 4 and the finishing rolling mill 6. The intermediate rolling mill 5 (specifically, each of the rolling stands 5A and 5B) is equipped with a reduction device that can adjust the leveling amount. The leveling amount is the difference in opening between the left and right reduction positions in the rolling mill.

[0038] 7A and 7B are diagrams showing the upper roll 51 and the lower roll 52 in the intermediate rolling mill 5. 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 in the axial direction of the upper and lower rolls 51 and 52 is the OP (operation) side (also called the work side), and the left side in the axial direction is the DR (drive) side, the OP side reduction position S2 is the opening degree at the chuck position (or roll collar position) on the OP side. Also, the DR side reduction position S1 is the opening degree at the chuck position (or roll collar position) on the DR side. And the leveling amount Lv is the difference between the DR side reduction position S1 and the OP side reduction position S2, and 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] <Camera installation position> In this embodiment, as an example, a camera 71 is installed between the rolling stands 5A and 5B in the intermediate rolling mill 5 in order to grasp the bending of the rolling target material between the rolling stands 5A and 5B. The installation 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 showing the installation position of the camera 71 with respect to the intermediate rolling mill 5, respectively. In FIGS. 8 and FIG. 9, the upstream side US and the downstream side DS are shown.

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

[0042] Guide 8B and guide 8D are provided on the downstream side DS of rolls 51B and 52B in rolling stand 5B. Guides 8B and 8D are arranged side by side in the left-right direction. Guide 8B is arranged corresponding to the K4 groove formed in rolls 51B and 52B, and guide 8D is arranged corresponding to the K5 groove formed in rolls 51B and 52B.

[0043] As shown in Fig. 10, each of the guides 8A and 8B has 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 in the left-right direction by the pair of side guides 83. A passage 84 is formed between the upper guide 81 and the lower guide 82 to allow the material to be rolled MR to pass through. Note that the guides 8C and 8D are configured in the same manner as the guides 8A and 8B.

[0044] Here, the guide on the rolling exit side guides the material to be rolled while restricting warping and bending of the material. The guide on the rolling entry side guides the material to be rolled so that it fits into the roll grooves. The guides are positioned left and right so that the left and right center of the guide passage coincides with the left and right center of the corresponding groove. The longitudinal (rolling direction) ends of the guides are positioned so that their left and right directions are parallel to the axial centers of the corresponding rolls extending in the left and right directions. For example, the longitudinal ends 85 (FIG. 9) of guides 8A and 8B are positioned so that they are parallel to the axial centers of rolls 51A and 52A and rolls 51B and 52B, respectively.

[0045] As shown in Fig. 9, the camera 71 is disposed between the guides 8A and 8B when viewed from above. As shown in Fig. 8, the camera 71 photographs the longitudinal gap L2 between the guides 8A and 8B (for example, L2 = 200 mm). This makes it possible for the camera 71 to photograph an image of the longitudinal leading edge of the material being rolled as it is sent from the guide 8B, which is the rolling exit side, to the downstream DS in rolling with a K4 groove, for example.

[0046] The camera 71 may be disposed below the intermediate rolling mill 5.

[0047] <Bending control> Next, curve control using the camera 71 will be described. FIG. 11 is a flowchart showing the flow of curve control processing. Here, FIG. 12 shows the configuration of the image analysis device 72 (FIG. 6). The image analysis device 72 has 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 the 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 amount of curve based on the image processing results, and outputs curve amount calculation data BCD. The control unit 72E controls the image analysis device 72.

[0048] <<How to calculate the amount of bending>> The bending control process will be described with reference to FIG. 11. First, when the process of FIG. 11 is started, the camera 71 has already started capturing images, and the image acquisition unit 72A is sequentially acquiring image data IMD. In this state, the control unit 72E monitors whether the workpiece to be rolled has reached the image capturing range of the camera 71 based on the acquired image data IMD (step S1). For example, when the workpiece to be rolled, having been rolled with a K4 groove in the rolling stand 5B, passes through the guide 8B on the rolling exit side and reaches the image capturing range of the camera 71, a change in brightness occurs due to the self-luminescence of the workpiece during hot rolling. Therefore, the control unit 72E detects the workpiece to be rolled by detecting a change in brightness in the image data IMD.

[0049] If the material to be rolled is detected (Yes in step S1), the control unit 72E outputs a trigger signal to the image storage unit 72B in step S2. As a result, the image storage unit 72B stores image data IMD for a predetermined period of time before and after that timing. Therefore, a leading end image of the longitudinal leading end of the material to be rolled is acquired (step S3).

[0050] Next, the process proceeds to step S4, where the image processing unit 72C performs image processing on the acquired tip image. Fig. 13 is a diagram showing an example of a captured image including a tip image IM_MR. The captured image also includes a guide image IM_GD obtained by capturing an image of the guide 8B. Note that Figs. 13 and 14 also show the OP side and the DR side. The image processing unit 72C extracts a bright portion of the captured image as the tip 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. Of the contour line L_MR, the points where the lines of the left and right width direction ends Lop, Ldr disappear at the longitudinal tip end are defined as the end representative point Pop of the Op-side joint and the end representative point Pdr of the Dr-side joint. The longitudinal positions of these representative points are defined as A2 and A1, respectively, and the difference between these (A1 - A2) is defined as the longitudinal position difference ΔA. The longitudinal position difference ΔA represents the amount of bending of the material to be rolled. The calculation unit 72D calculates the longitudinal position difference ΔA and outputs the calculation result as bending amount calculation data BCD. The longitudinal position difference ΔA can also be referred to as the difference in elongation amount.

[0052] Furthermore, as a specific method for accurately determining the longitudinal positions A2, A1, the longitudinal end portion of the guide 8B (first reference object extending in the left-right direction) extending in the left-right direction is photographed by the camera 71. FIG. 13 shows an image IM_GT of the longitudinal end portion. Based on the image IM_GT of the longitudinal end portion, the image processing unit 72C determines a first reference line BL1 extending in the left-right direction perpendicular to the rolling direction (longitudinal direction). FIG. 14 illustrates the first reference line BL1. The image processing unit 72C identifies the longitudinal lengths of the representative points Pop, Pdr from the first reference line BL1 as the longitudinal positions A2, A1, respectively.

[0053] The first reference object does not necessarily have to be a guide, but it is preferable and simple to use a guide provided on the rolling exit side.

[0054] Furthermore, a center line (second reference object) extending in the longitudinal direction may be marked on the upper portion of the guide 8B to identify the lateral center position of the K4 hole. In this case, the center line is photographed by the camera 71. FIG. 13 shows a center line image IM_CL obtained by photographing the center line. The image processing unit 72C determines a second reference line BL2 extending in the rolling direction (longitudinal direction) based on the center line image IM_CL (FIG. 14). Then, the lateral positions of the left and right joints at the longitudinal leading end of the rolling target material can be identified and the amount of bending can be calculated. Specifically, as shown in FIG. 14, the image processing unit 72C identifies the length from the second reference line BL2 to the representative point Pdr as the lateral position C1, and the length to the representative point Pop as the lateral position C2. The calculation unit 72D then calculates the difference ΔC between the lateral positions as ΔC = C1 - C2 to calculate the amount of bending.

[0055] The amount of bending may be calculated by calculating either the difference ΔA in the longitudinal direction position or the difference ΔC in the left-right direction position, or by calculating both. When both are calculated, the bending amount calculation data BCD will be data indicating both ΔA and ΔC.

[0056] <<Modifications regarding the representative points of the left and right joints>> The representative points of the left and right joints may be obtained by the following method. Here, the image processing unit 72C extracts the contour lines LTdr and LTop at the longitudinal tip sides of the left and right joints by performing image processing on the tip image IM_MR (FIG. 14). Then, the image processing unit 72C identifies the center points of the contour lines LTdr and LTop as the representative points PCdr and PCop. Since the size of the joint and arm of the material to be rolled is determined by the size (series) of the steel sheet pile, if the installation conditions of the camera 71 are fixed, the range in the left and right direction in the captured image that corresponds to the left and right end portions consisting of the joint and arm can be determined in advance based on the size of the steel sheet pile. Therefore, of the leading edge line of the contour line L_MR of the rolling target material, a certain range from the Op-side end can be determined to be the Op-side end, and the center point of that range can be set as the representative point PCop of the Op-side end, and a certain range from the Dr-side end can be determined to be the Dr-side end of the rolling target material, and the center point of that range can be set as the representative point PCdr of the Dr-side end. This method is particularly effective when the disappearance points of the width direction ends Lop, Ldr on the contour line L_MR of the leading edge portion image IM_MR are not clear.

[0057] In addition, the point on the leading edge line of the contour line L_MR where the direction of extension from the Op side end or the Dr side end to the left and right changes midway can be detected as a bending point (the point where the arm portion and the flange are connected), and the bending point can be used as the representative point of each of the Op side end and the Dr side end.

[0058] <<Representative points for other steel materials>> If the steel material is not a steel sheet pile but, for example, flat steel, the points at which the lines at the left and right widthwise ends of the contour line of the longitudinal tip of the material to be rolled disappear at the longitudinal tip side can be used as the representative point of the end on the Op side and the representative point of the end on the Dr side, respectively.

[0059] Furthermore, when the steel material is, for example, an H-shaped steel, an I-shaped steel, or a channel steel, the left and right flange portions can be used as the left and right ends of the longitudinal leading edge of the material to be rolled. That is, within the portion that forms the leading edge line of the contour line of the longitudinal leading edge, a certain range from the Op-side end can be determined to be the Op-side flange end, and the center point of that range can be used as the representative point of the Op-side flange portion, and a certain range from the Dr-side end can be determined to be the Dr-side flange end, and the center point of that range can be used as the representative point of the Dr-side flange portion.

[0060] <<Leveling adjustment>> Now, returning to the explanation using Fig. 11, after the amount of bow is calculated as described above, the process proceeds to step S5. Here, bow amount calculation data BCD is sent to the intermediate rolling control unit 75 via the process computer 73, and a leveling amount correction value determination unit 75A (Fig. 6) calculates a leveling amount correction value based on the bow amount calculation data BCD. That is, a leveling amount correction value ΔLv is calculated based on the difference ΔA in the longitudinal direction position calculated above. The relationship between the leveling amount correction value ΔLv and the difference ΔA in the longitudinal direction position is expressed as ΔLv = K ΔA using a proportionality constant K.

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

[0062] When the elongation on the OP side is large, that is, when A2 > A1, before rolling the material to be rolled in the next rolling, the upper roll 51B in the rolling stand 5B is tilted to the DR side or the lower roll 52B is tilted to 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 in the next rolling, the upper roll 51B in the rolling stand 5B is tilted to the OP side or the lower roll 52B is tilted to the DR side in advance. Thereby, the difference in elongation between the left and right can be reduced, and the 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 as ΔLv = M·ΔC by using the proportionality constant M. Or, both ΔA and ΔC can be used, and it may be set as ΔLv = K’·ΔA + M’·ΔC (K’ and M’ are proportionality constants).

[0064] Then, based on the set leveling amount, the roll gap control unit 75C controls the roll gap device in the rolling stand 5B to adjust the bending of the material to be rolled.

[0065] <<Setting of Proportionality Constant>> Here, an example of setting the proportionality constant K will be described. In 10H, which is one series of hat - shaped steel sheeting, photography was carried out by a camera. Note that it is the photography at 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 position A1 of the joint part on the DR side = 30 mm, and the longitudinal position A2 of the joint part on the OP side = 90 mm. Therefore, the difference in longitudinal position ΔA = - 60 mm. At this time, since the bending was improved with the leveling amount correction value ΔLv = - 0.6 mm, in the case of the above - mentioned hat - shaped steel sheeting, the proportionality constant K = ΔLv / ΔA = 0.01 can be set.

[0066] <<Thrust Adjustment>> In addition to leveling adjustment, roll thrust adjustment can also be performed. Roll thrust adjustment is a method of adjusting the axial position of one of the upper and lower rolls relative to the other roll. Thrust adjustment changes the roll gap that rolls the left and right flanges and joints, allowing for adjustment of the bending of the steel sheet pile with joints.

[0067] <<Applies to>> The bending control according to the present invention is not limited to hat-shaped steel sheet piles, but can be applied to steel sheet piles having joints on the left and right sides, i.e., the U-shaped steel sheet piles (FIG. 1B) and straight steel sheet piles (FIG. 1C) described above.

[0068] <<Example>> This shows an example of a 10H hat-type steel sheet pile, which is one size. Images were taken between the tandems (the exit side of the K4 groove rolling and the entry side of the K3 groove rolling) for the third pass of intermediate rolling, the amount of bending was calculated, and the amount of leveling was adjusted according to the amount of bending to confirm the occurrence of bending. The method for confirming the occurrence of bending is as follows. (a) Whether or not finish rolling is possible depending on the bending condition after intermediate rolling (b) Evaluation of the amount of bending in a 10m product taken from the longitudinal tip Regarding (b) above, the bending during intermediate rolling remains in the product, and the product passes if the amount of bending is 10 mm / 10 m or less. Figure 15 shows the definition of the amount of bending BD in the product (hat-shaped steel sheet pile 1).

[0069] The results of this example are shown in a table in Figure 16. For the first roll in the rolling sequence, final rolling (rolling under the initial setting conditions) was performed, and the bending was evaluated. In this case, the bending after intermediate rolling was too large, and finish rolling was not possible.

[0070] For the second to fifth rolls in the rolling sequence, the bow control according to the embodiment of the present invention was applied. That is, the leveling in the K4 groove rolling was adjusted based on the calculated amount of bow (difference ΔA in longitudinal position) (proportionality constant K = 0.01). As a result, the bow after intermediate rolling was improved for the second and subsequent rolls, and the bow of the product was within the allowable range.

[0071] In addition, for the sixth to ninth rolls in the rolling sequence, the operator set the leveling amount for the sixth roll onwards based on a visual check of the bending after intermediate rolling of the first roll. Because the operator could not visually determine the bending at the exit side of the K4 groove rolling, the leveling amount for the sixth roll at the K4 groove rolling was set to 0 mm. For the seventh roll, the condition of the sixth roll was taken into account, and for the eighth roll, the condition of the seventh roll was also taken into account to adjust the leveling amount. As a result, the bending of the product finally fell within the allowable range for the eighth roll.

[0072] The table in Fig. 16 also displays ΔC as a calculated value of the amount of bending. Fig. 17 shows a graph illustrating the relationship between the difference ΔA in the longitudinal direction position in Fig. 16 and the leveling amount Lv, and Fig. 18 shows a graph illustrating the relationship between the difference ΔC in the left-right direction position in Fig. 16 and the leveling amount Lv. It can be seen that the leveling amount can be determined using ΔC as well as ΔA.

[0073] <<Applicable areas for calculating bending amount>> In the above example, the camera 71 was installed between the rolling stands 5A and 5B in the intermediate rolling mill 5 to calculate the amount of bow at the K4 groove rolling exit side, but the camera may also be installed downstream of the rolling stand 5A, for example. In this case, it is possible to calculate the amount of bow at the K3 groove rolling exit side in the third pass of intermediate rolling, for example. Alternatively, the present invention can be applied to a single rolling stand such as the roughing mill 4 or the finishing mill 6. However, since the conditions for the equipment to be installed between rolling stands in tandem rolling, such as between the rolling stands 5A and 5B, are stricter, there is greater significance in applying the present invention, which allows the amount of bow to be calculated with simple equipment.

[0074] Furthermore, when performing reverse rolling like intermediate rolling, it is preferable to be able to adjust the bending in as many intermediate stages of rolling as possible, so for example, as shown in Fig. 19, in addition to the camera 71, a camera 77 may be installed between the guides 8C and 8D in the intermediate rolling mill 5. In this case, for example, the amount of bending at the K6 groove rolling exit side (upstream side of the guide 8C) in the second pass can be calculated, and the bending in the K6 groove rolling can be adjusted.

[0075] <<About bending judgment>> Fig. 20 is a diagram showing the configuration of a rolling control device 7 according to a modified example of the configuration shown in Fig. 6. In this example, in addition to the configuration of Fig. 6, a determination unit 73A is provided in a process computer 73, and further a monitor device 78 is provided.

[0076] The determination unit 73A determines whether or not the bending has occurred based on the bending amount calculation data BCD. Specifically, the determination unit 73A compares the difference ΔA in the longitudinal direction position or the difference ΔC in the left-right direction position with a predetermined threshold, and if it determines that the bending amount is large, it causes the monitor device 78 to issue a warning. Note that both ΔA and ΔC may be compared with their corresponding thresholds. [Explanation of symbols]

[0077] 1 Hat-shaped steel sheet pile 1X U-shaped steel sheet pile 1Y Straight steel sheet pile 2. Hot rolling equipment 3 Heating furnace 4 Roughing mill 5 Intermediate rolling mill 5A, 5B rolling stands 6 Finishing rolling mill 7. Rolling control device 8A~8D Guide 11. Web 12 flange 13 Arm 14 Joint 41 Upper Roll 42 Lower roll 51 Upper Roll 51A, 51B upper roll 52 Lower Roll 52A, 52B lower roll 61 Upper Roll 62 Lower Roll 71 Camera 72 Image analysis equipment 72A Image acquisition unit 72B Image storage section 72C Image processing unit 72D Calculation Unit 72E Control Unit 73 Process Computer 73A Judgment section 74 Rough rolling control section 75 Intermediate Rolling Control Unit 75A Leveling amount correction value determination unit 75B Leveling amount setting section 75C rolling control unit 76 Finishing Rolling Control Unit 77 Camera 78 Monitor Device 81 Upper guide 82 Lower guide 83 Side guide 84 Passage 85 Longitudinal end BL1 First Baseline BL2 Second Baseline DS downstream H hole type IM_CL Centerline image IM_GD Guide image IM_MR tip image L_MR contour line Lop, Ldr Width direction end LTdr, LTop contour line ML production line MR rolling target material PCdr, PCop representative point Pdr, Pop end representative point US upstream side

Claims

1. A method for calculating the amount of bending of a steel material rolled by a rolling mill, an imaging step of imaging a longitudinal tip end portion of the steel material at the delivery side of the rolling mill by an imaging device that images the steel material from above or below at the delivery side of the rolling mill; An extraction step of extracting shapes relating to left and right ends of the longitudinal tip portion from an image of the longitudinal tip portion of the steel material obtained by photographing; a calculation step of calculating the amount of bending by calculating a difference in longitudinal position and / or a difference in left and right position at the left and right end portions based on the extracted shape; A method for calculating the amount of bending of steel material.

2. In the photographing step, a first reference object extending in the left-right direction and perpendicular to the longitudinal direction is photographed; 2. The steel material bending amount calculation method according to claim 1, further comprising a determination step of determining a first reference line for identifying the longitudinal positions of the left and right ends based on an image of the first reference object.

3. In the photographing step, a second reference object for specifying the left-right center position of the rolling roll groove is photographed, 2. The steel material bending amount calculation method according to claim 1, further comprising a determination step of determining a second reference line for identifying the left-right positions of the left and right ends based on an image of the second reference object.

4. The steel material is a steel sheet pile having a web and joint portions at both left and right ends in a width direction, The steel material bending amount calculation method according to claim 1 , wherein the left and right end portions are end portions including the left and right joint portions.

5. 4. The steel material bending amount calculation method according to claim 1, wherein the photographing device is arranged between the rolling mill and another rolling mill for performing tandem rolling.

6. 4. A method for manufacturing a steel material, wherein, in the next rolling of the steel material, the inclination of the rolls of the rolling mill and / or the relative positions in the axial direction of the upper and lower rolls are changed based on a calculated value calculated using the steel material bending amount calculation method according to any one of claims 1 to 3.

7. A method for determining a bending of a steel material, comprising: determining a bending of the steel material based on a calculated value calculated using the method for calculating a bending amount of the steel material according to any one of claims 1 to 3.

8. A steel material bending amount calculation device that calculates the bending amount of a steel material rolled by a rolling mill, an imaging device that is installed on the delivery side of the rolling mill and that images the steel material from above or below; an image processing unit that extracts shapes of left and right ends of the longitudinal tip portion of the steel material from an image of the longitudinal tip portion obtained by photographing the steel material; a calculation unit that calculates the amount of bending by calculating a difference in the rolling direction positions of the left and right end portions and / or a difference in the left and right direction positions based on the extracted shape; A steel bending amount calculation device having the above.

Images