Steel material bending amount calculation method, steel material production method, steel material bending determination method, and steel material bending amount calculation device

Abstract

A steel material bending amount calculation method for calculating the bending amount of a steel material rolled by a rolling machine, the method comprising: an imaging step for imaging a longitudinal tip section of the steel material on the exit side of the rolling machine by using an imaging device for imaging the steel material from above or below at the exit side of the rolling machine; an extraction step for extracting a shape related to left and right ends at the longitudinal direction tip section from the image of the longitudinal tip section of the steel material obtained through imaging; and a calculation step for calculating the difference in the longitudinal position and / or the difference in the left-right position between the left and right ends on the basis of the extracted shape.

Description

Steel bending amount calculation method, steel manufacturing method, steel bending determination method, and steel bending amount calculation device

[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.

[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 image pickup 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 these 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, Patent Document 3, for example, discloses the following method for measuring the bending of structural steel. In this method, the widthwise brightness distribution is calculated for multiple cross sections at regular intervals in the longitudinal direction from an image of the structural steel captured from above, and the bent portion in each cross section is detected. Then, the widthwise positions of the bent portions are connected in the longitudinal direction to calculate a bending profile along the longitudinal direction.

[0006] JP 1999-28510 A JP 2006-234540 A JP 2019-178901 A

[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, but 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.

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

[0012] Furthermore, in the first configuration, the photographing step may further include a determination step of photographing a first reference object that is perpendicular to the longitudinal direction and extends in the left-right direction, and determining a first reference line for identifying the longitudinal positions of the left and right ends based on the image of the first reference object (second configuration).

[0013] Furthermore, in the first configuration, the photographing step may further include a determination step of photographing a second reference object for identifying the left-right center position of the rolling roll groove, and determining a second reference line for identifying the left-right positions of the left and right end portions based on the image of the second reference object (third configuration).

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

[0015] In addition, in any of the 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, in a method for manufacturing a steel material according to one embodiment of the present disclosure, 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 are changed in the next rolling of the steel material based on the calculated value calculated using the steel material 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 aspect 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] Furthermore, a steel material bending amount calculation device according to one aspect of the present disclosure is a steel material bending amount calculation device that calculates the amount of bending of a steel material rolled by a rolling mill, and includes: an imaging device that is installed on the outlet side of the rolling mill and photographs the steel material from above or below; an image processing unit that extracts shapes relating to the left and right ends of the longitudinal tip of the steel material from an image of the longitudinal tip of the steel material obtained by photographing the image; and a calculation unit that calculates the amount of bending by calculating a difference in the longitudinal position of the left and right ends and / or a difference in the left and right positions based on the extracted shapes (eighth configuration).

[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.

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

[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 Pile and Rolling Manufacturing Method Thereof> Figures 1A, 1B, and 1C are diagrams showing the cross-sectional shapes of various steel sheet piles. As shown in Figure 1A, the 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 arms 13, and a pair of joints 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 inclination with respect to the left-right direction. In the example shown in Figure 1A, the pair of flanges 12 extend at an inclination so that the end opposite to the web 11 side is lower in the up-down direction (direction perpendicular to the left-right direction). The pair of arms 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 portions 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 portions used for connecting to other steel sheet piles by fitting into joints of other steel sheet piles.

[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. In addition, a pair of joint portions 14 in the U-shaped steel sheet pile 1X both open upward. 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 on the left and right, the calculation of the bending amount and the rolling manufacturing based on the calculation can be performed in the same way 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-shaped 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-shaped 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 progress direction.

[0026] The heating furnace 3 heats a slab or bloom, which is a continuously cast raw steel billet, to a predetermined temperature. The raw steel billet heated in the heating furnace 3 is used as a rolling target material and is hot-rolled using a plurality of 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 rolled material 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, a Box groove, a K8 groove, and a K7 groove, are formed in the upper roll 41 and the lower roll 42.

[0028] In the rough rolling of this embodiment, first, the width of the workpiece to be rolled is reduced in the Box groove. Next, the workpiece 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 workpiece 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 workpiece to be rolled is moved left and right between the K8 groove and the K7 groove at the inlet side of the rolling mill by a shift device (parallel guide or dog). Such left and right movement of the workpiece 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 product shape with a cross section that meets the target product dimensions. FIG. 5 is a diagram showing an example of grooves used in the finishing rolling mill 6. Two grooves, a K1 groove and a 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 claw portions are performed. The final rolling 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 finish rolling 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 finish 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. 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, within 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 described. Note that although the intermediate rolling mill 5 will be described as an example here, 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 Figures 7A and 7B, if the axial right side of the upper and lower rolls 51, 52 is the OP (operating) side (also called the work side) and the axial left side is the DR (drive) side, the OP-side pressure position S2 is the opening degree at the OP-side chock position (or roll collar position). The DR-side pressure position S1 is the opening degree at the DR-side chock position (or roll collar position). The leveling amount Lv is the difference between the DR-side pressure position S1 and the OP-side pressure position S2, and is expressed as Lv = S1 - S2. That is, when the upper roll 51 and the lower roll 52 are parallel as shown in Figure 7A, the leveling amount Lv = 0. When the upper roll is tilted toward the DR side as shown in Figure 7B, S1 < S2, and the leveling amount Lv is a negative value. On the other hand, when the upper roll is tilted toward the OP side, S1 > S2, and the leveling amount Lv is 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 to grasp the bending of the material to be rolled between the rolling stands 5A and 5B. The installation position of the camera 71 will be explained using Figures 8, 9, and 10. Figures 8, 9, and 10 are a side view, a top view, and a front view, respectively, showing the installation position of the camera 71 relative to the intermediate rolling mill 5. Note that Figures 8 and 9 show the upstream side US and the downstream side DS.

[0041] As shown in FIG. 8, the camera 71 is disposed above the intermediate rolling mill 5. The height direction distance L1 from the photographing position of the camera 71 to the production line ML is, for example, 4 to 5 m. As shown in FIG. 9, the intermediate rolling mill 5 is provided with guides 8A, 8B, 8C, and 8D. A guide 8A and a guide 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 groove formed in the rolls 51A and 52A, and the guide 8C is arranged corresponding to the K6 groove formed in 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 to correspond to the K4 groove formed in rolls 51B and 52B, and guide 8D is arranged to correspond to the K5 groove formed in rolls 51B and 52B.

[0043] As shown in Figure 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 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 exit side of the rolling mill guides the material to be rolled while restricting warping and bending of the material. The guide on the entry side of the rolling mill guides the material to be rolled in alignment with the roll grooves. The guides are installed so that the lateral center of the guide passage coincides with the lateral center of the corresponding groove. The longitudinal (rolling direction) ends of the guides are installed so that their lateral directions are parallel to the axial centers of the corresponding rolls extending in the lateral direction. For example, the longitudinal ends 85 ( FIG. 9 ) of guides 8A and 8B are installed 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 (e.g., L2 = 200 mm). This makes it possible to use the camera 71 to photograph an image of the longitudinal leading end 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] <Curve Control> Next, curve control using the camera 71 will be described. FIG. 11 is a flowchart showing the flow of curve control processing. 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] <<Method of Calculating the Amount of Bend>> The bending control process will be described with reference to Figure 11. First, when the process of Figure 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 imaging 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 imaging range of the camera 71, a brightness change 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 brightness change in the image data IMD.

[0049] If the workpiece 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. This causes the image storage unit 72B to store 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 workpiece 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 and A1, the longitudinal end portion of the guide 8B (first reference object extending in the left-right direction) is photographed by a 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 and Pdr from the first reference line BL1 as the longitudinal positions A2 and 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 centerline (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 centerline is photographed by the camera 71. FIG. 13 shows a centerline image IM_CL obtained by photographing the centerline. The image processing unit 72C determines a second reference line BL2 extending in the rolling direction (longitudinal direction) based on the centerline image IM_CL (FIG. 14). The image processing unit 72C then identifies the lateral positions of the left and right joints at the longitudinal leading end of the rolling target material and calculates the amount of bend. 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 from the representative point Pop 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 bend.

[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 Representative Points of the Left and Right Joints>> The representative points of the left and right joints may be determined by the following method. Here, the image processing unit 72C extracts the contour lines LTdr and LTop at the longitudinal tip ends of the left and right joints by performing image processing on the tip end image IM_MR ( FIG. 14 ). The image processing unit 72C then identifies the center points of the contour lines LTdr and LTop as the representative points PCdr and PCop. The size of the joint and arm of the material to be rolled is determined by the size (series) of the steel sheet pile. Therefore, if the installation conditions of the camera 71 are fixed, the range of the left and right ends of the joint and arm in the captured image can be determined in advance based on the size of the steel sheet pile. Therefore, a certain range from the Op-side end of the leading edge line of the contour line L_MR of the material to be rolled from the Op-side end can be determined as the Op-side end, and the center point of that range can be determined as the representative point PCop of the Op-side end. Furthermore, a certain range from the dry-side end can be determined as the dry-side end of the material to be rolled, and the center point of that range can be set as the representative point PCdr of the dry-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 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 where 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 end representative point on the Op side and the end representative point on the Dr side, respectively.

[0059] Furthermore, when the steel material is, for example, an H-beam, an I-beam, 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 leading edge line of the contour line of the longitudinal leading edge, a certain range from the Op-side end can be determined as 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. Also, a certain range from the Dr-side end can be determined as 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) 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 for the next rolling, and Lv is the set value of the leveling amount for the current rolling.

[0062] When the amount of elongation on the OP side is large, i.e., when A2 > A1, before rolling the material to be rolled in the next rolling run, 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 amount of elongation on the DR side is large, i.e., when A2 < A1, before rolling the material to be rolled in the next rolling run, 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. This reduces the difference in elongation between the left and right sides, making it possible to suppress bending.

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

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

[0065] <<Setting the proportionality constant>> Here, an example of setting the proportionality constant K will be described. Photographs were taken with a camera for 10H, one series of hat-type steel sheet piles. The photographs were taken between tandems (the exit side of the K4 groove and the entry side of the K3 groove) during the third pass of intermediate rolling. In this example, the longitudinal position A1 of the joint part on the DR side was 30 mm, and the longitudinal position A2 of the joint part on the OP side was 90 mm. Therefore, the difference in longitudinal position ΔA was -60 mm. Since the bending was improved with a leveling amount correction value ΔLv = -0.6 mm, the proportionality constant K can be set as ΔLv / ΔA = 0.01 for the above hat-type steel sheet pile.

[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, making it possible to adjust the bending of the steel sheet pile with joints.

[0067] <<Applicable Targets>> 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. That is, it can also be applied to the above-mentioned U-shaped steel sheet piles (FIG. 1B) or straight steel sheet piles (FIG. 1C).

[0068] <Example> This example shows a 10H hat-type steel sheet pile, which is one size. Images were taken between the tandem sections (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 leveling amount was adjusted according to the amount of bending to confirm the occurrence of bending. The methods for confirming the occurrence of bending are as follows: (a) Whether or not finish rolling is possible depending on the state of bending after intermediate rolling; (b) Evaluation of the amount of bending in a 10-m length product sampled from the tip side in the longitudinal direction. Regarding (b), the bending during intermediate rolling remains in the product, and a bending amount of 10 mm / 10 m or less is considered acceptable. Figure 15 shows the definition of the amount of bending BD in the product (hat-type 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] Furthermore, for the sixth to ninth rolls in the rolling order, the leveling amount for the sixth and subsequent rolls was set by the operator based on visual confirmation 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 in 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] In addition, 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. 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] <<Locations where bow amount calculation is applied>> In the above example, the camera 71 was installed between the rolling stands 5A and 5B of the intermediate rolling mill 5, and the bow amount at the K4 groove rolling exit side was calculated. The present invention is not limited to this, and the camera may be installed, for example, downstream of the rolling stand 5A. In this case, for example, the bow amount at the K3 groove rolling exit side in the third pass of intermediate rolling can be calculated. Alternatively, the present invention can be applied to a single rolling stand such as the roughing mill 4 or the finishing mill 6. However, the conditions for installation of equipment between rolling stands in tandem rolling, such as between the rolling stands 5A and 5B, are more stringent. Therefore, there is great significance in applying the present invention, which enables the bow amount to be calculated with simple equipment.

[0074] Furthermore, when performing reverse rolling as in intermediate rolling, it is preferable to be able to adjust the bending at as many intermediate stages of rolling as possible. Therefore, 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] <<Regarding bending judgment>> Figure 20 is a diagram showing the configuration of a rolling control device 7 according to a modified example of the configuration shown in Figure 6. In this example, in addition to the configuration of Figure 6, a judgment unit 73A is provided in a process computer 73, and a monitor device 78 is also provided.

[0076] The determination unit 73A determines whether or not there is a skew based on the skew amount calculation data BCD. Specifically, the determination unit 73A compares the difference ΔA in the longitudinal position or the difference ΔC in the left-right position with a predetermined threshold. If the determination unit 73A determines that the amount of skew 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.

[0077] 1 Hat-shaped steel sheet pile 1X U-shaped steel sheet pile 1Y Linear steel sheet pile 2 Hot rolling equipment 3 Heating furnace 4 Roughing rolling mill 5 Intermediate rolling mill 5A, 5B Rolling stand 6 Finishing rolling mill 7 Rolling control device 8A to 8D Guide 11 Web 12 Flange 13 Arm portion 14 Joint portion 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 device 72A Image acquisition unit 72B Image storage unit 72C Image processing unit 72D Calculation unit 72E Control unit 73 Process computer 73A Determination unit 74 Roughing rolling control unit 75 Intermediate rolling control unit 75A Leveling amount correction value determination unit 75B Leveling amount setting unit 75C Rolling gap control unit 76 Finish rolling control unit 77 Camera 78 Monitor device 81 Upper guide 82 Lower guide 83 Side guide 84 Passage 85 Longitudinal end BL1 First reference line BL2 Second reference line DS Downstream side H Groove IM_CL Center line 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, comprising: an imaging step of photographing the longitudinal tip of the steel material at the exit side of the rolling mill using an imaging device that photographs the steel material from above or below at the exit side of the rolling mill; an extraction step of extracting shapes related to the left and right ends of the longitudinal tip from the image of the longitudinal tip of the steel material obtained by imaging; and a calculation step of calculating the amount of bending by calculating the difference in longitudinal position and / or the difference in left and right position of the left and right ends based on the extracted shape.

2. A method for calculating the amount of bending of steel material as described in claim 1, further comprising a determination step of photographing a first reference object that is perpendicular to the longitudinal direction and extends in the left-right direction in the photographing step, and determining a first reference line for identifying the longitudinal positions of the left and right ends based on the image of the first reference object.

3. A method for calculating the amount of bending of steel material as described in claim 1, further comprising a determination step of photographing a second reference object for identifying the left and right center position of the rolling roll groove in the photographing step, and determining a second reference line for identifying the left and right positions of the left and right ends based on the image of the second reference object.

4. A method for calculating the amount of bending of steel material according to any one of claims 1 to 3, wherein the steel material is a steel sheet pile having a web and joint portions at both left and right ends in the width direction, and the left and right ends are ends that include the left and right joint portions.

5. A method for calculating the amount of bending of steel material as described in any one of claims 1 to 4, wherein the photographing device is arranged between the rolling mill and another rolling mill for performing tandem rolling.

6. A method for manufacturing steel material, in which the inclination of the rolls of the rolling mill and / or the relative axial positions of the upper and lower rolls are changed in the next rolling of the steel material based on the calculated value calculated using the method for calculating the amount of bending of steel material described in any one of claims 1 to 5.

7. A method for determining the bending of steel material, which determines the bending of the steel material based on a calculated value calculated using the method for calculating the amount of bending of steel material described in any one of claims 1 to 5.

8. A steel material bending amount calculation device for calculating the amount of bending of steel material rolled by a rolling mill, comprising: a photographing device installed on the delivery side of the rolling mill for photographing the steel material from above or below; an image processing unit for extracting shapes relating to the left and right ends of the longitudinal tip of the steel material from an image of the longitudinal tip of the steel material obtained by photographing the tip; and a calculation unit for calculating the amount of bending by calculating the difference in the longitudinal position of the left and right ends and / or the difference in left and right positions based on the extracted shapes.

Images