Method for measuring the shape of a strip-shaped substrate, a quality control method, and a manufacturing method; as well as a device for measuring the shape of a strip-shaped substrate and a manufacturing facility.

Abstract

To provide a technique that allows easy and stable operation of shape determination and can reduce maintenance cost.SOLUTION: A shape measurement method for a belt-like substrate includes: an imaging step of picking up images of both sides of a belt-like substrate; an image processing step of calculating a shape index of the belt-like substrate from the obtained images; and a determination step of performing shape quality determination for the belt-like substrate on the basis of the obtained shape index. A quality management method includes, by using the method, cutting and removing a section determined to have a defective shape in a longitudinal direction of the belt-like substrate. A manufacturing method includes, by using the shape measurement method, changing the manufacturing specifications of the belt-like substrate so that the obtained shape index falls within a range of a predetermined shape index determined in advance. A shape measurement device of a belt-like substrate comprises: imaging means that continuously picks up images of both sides of a belt-like substrate being conveyed; image processing means that calculates a shape index of the belt-like substrate from the obtained images; and determination means that performs shape quality determination for the belt-like substrate on the basis of the obtained shape index.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for measuring the shape of a strip-shaped base material such as a hot-rolled steel sheet, a quality control method, a manufacturing method, a shape measuring device for a strip-shaped base material, and manufacturing equipment.

Background Art

[0002] In the raw material industry, shape control of strip-shaped base materials is important, and quantification of product shapes has been demanded. For example, there is a high need for measuring the shape of steel materials in the steel process from the viewpoints of operation stability, product quality assurance, etc. In particular, shape measurement during rolling for making a product into a target shape is important because it leads to improvement of product quality and stabilization of operation by performing initial setting of rolling conditions and feedback for rolling control during rolling.

[0003] For example, in a production line of a hot-rolled steel sheet as shown in FIG. 1, that is, in hot rolling equipment 100, it is manufactured as follows. First, a rectangular semi-finished product called a slab in a high-temperature state extracted from a heating furnace is processed into a sheet-shaped hot-rolled steel sheet S through processes such as width widening by a sizing mill, rough rolling by a rough rolling mill, and finish rolling by a finishing mill 1. Then, after the temperature is adjusted in a cooling zone 2, it is wound up by a coiler 4 to be made into a hot-rolled steel strip coil as a product. At this time, depending on the rolling state, the reduction amount in the width direction of the steel sheet S may become uneven and it may partially stretch, which is one of the causes of shape defects of the steel sheet S.

[0004] For example, when the edge portion (width direction end portion) is stretched more compared to the central portion (width direction central portion) of the steel sheet, the edge portion has a wavy shape. Conversely, when the central portion is stretched more, the central portion has a wavy shape. Such shape defects not only become defective as products but also deteriorate the passing property in subsequent processes such as pickling and cold rolling, causing operation troubles. Therefore, it is strongly required not to generate shape defects in hot-rolled steel sheets.

[0005] However, accurately measuring the shape of steel plates is difficult, and disturbances such as meandering, bouncing, and waving during steel plate rolling often prevent accurate measurements.

[0006] Various techniques have been proposed in the past for measuring the shape of steel sheets immediately after the finishing rolling process, including methods using rod-shaped light sources and magnetic sensors. Among these, a particularly promising method is disclosed in Patent Documents 1 to 3, which involves using a laser to irradiate the target surface with a point-shaped or linear light beam and measuring the reflected light to measure the shape of the steel sheet.

[0007] Furthermore, Patent Document 4 discloses a laser irradiation method that uses three line lasers such that the longitudinal direction of the lines is perpendicular to the conveying direction of the steel plate. In the technology disclosed in Patent Document 4, line lasers are irradiated parallel to the longitudinal direction of the steel plate so as to form three lines at equal intervals, and the influence of vertical vibration of the steel plate is eliminated by acquiring the reflected images and comparing the profiles of each laser.

[0008] Furthermore, Patent Documents 5 to 7 disclose techniques such as using a powerful LED light source to irradiate a target surface with a striped pattern consisting of multiple lines, thereby increasing the number of lines irradiated at a lower cost than a laser, and stably measuring the shape regardless of the surface quality or inclination of the target.

[0009] Currently, the most widely used method for measuring the shape of steel sheets in hot rolling is the technology disclosed in Patent Document 8, which involves measuring the inclination of the steel sheet using a laser distance meter and calculating the elongation rate of the steel sheet by converting the inclination to the wavelength of the steel sheet. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Unexamined Patent Publication No. 56-124006 [Patent Document 2] Japanese Patent Application Publication No. 55-40924 [Patent Document 3] Japanese Patent Application Publication No. 58-11708 [Patent Document 4] Japanese Patent Publication No. 61-40503 [Patent Document 5] Japanese Patent Publication No. 2008-58036 [Patent Document 6] Japanese Patent Publication No. 2011-99821 [Patent Document 7] Japanese Patent Publication No. 2016-65863 [Patent Document 8] Japanese Patent Application Publication No. 8-29147 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, conventional technology had the following problems: The technologies disclosed in Patent Documents 1 to 7 all involve measuring the shape of a hot-rolled steel sheet by irradiating it with light from a light source and capturing the reflected light with a camera. However, considering factors such as the effects of high temperatures due to radiant heat, and the adhesion of steam, dust, oil, etc., to the steel sheet, advanced technology is required to perform long-term and stable measurements with the light source and sensors close to the steel sheet during transport, resulting in high maintenance costs. Furthermore, because the shape measurement is performed within a relatively narrow field of view, it is difficult to distinguish between waves caused by shape defects, such as the weaving phenomenon of the steel sheet, and waves caused by shape defects. In addition, there are challenges such as the difficulty in stably measuring the shape due to the influence of meandering of the steel sheet.

[0012] The technology disclosed in Patent Document 8 is a technique for calculating the elongation of a steel sheet and measuring its shape using a rangefinder, but like the technologies in Patent Documents 1 to 7, it is greatly affected by weaving and steel sheet meandering. Problems exist in that these measurement methods can lead to incorrect judgments when determining the quality of the shape, and can cause problems in subsequent processes such as pickling and cold rolling. To prevent this, one could consider moving the light source away from the object, but this would cause the light to diffuse and the light intensity to decrease, making it difficult to design an optical system that can stably focus the light to ensure sufficient light intensity. With rangefinder methods, even if measures such as moving the light source away from the object are taken, the field of view does not change, making it difficult to improve these problems.

[0013] The present invention has been made in view of the above circumstances, and aims to provide a method for measuring the shape of a strip-shaped substrate, a quality control method, and a manufacturing method, as well as a shape measuring apparatus and manufacturing equipment for a strip-shaped substrate, that can easily and stably determine the shape of the surface of the strip-shaped substrate and can also suppress maintenance costs. [Means for solving the problem]

[0014] The present invention provides a method for measuring the shape of a strip-shaped substrate, which advantageously solves the above problems, and is characterized by comprising: an imaging step of capturing images of both sides of the strip-shaped substrate; an image processing step of calculating a shape index of the strip-shaped substrate from the obtained images; and a determination step of determining whether the shape of the strip-shaped substrate is good or bad based on the obtained shape index.

[0015] Furthermore, the method for measuring the shape of a strip-shaped substrate according to the present invention is as follows: (a) In the image processing step, multiple images overlapping in the width and longitudinal directions of the strip-shaped substrate are concatenated, the displacement amounts at both ends and the center in the width direction of the strip-shaped substrate are calculated, a predetermined region of the strip-shaped substrate is extracted, multiple division sections are set in the width and longitudinal directions, and the shape index is calculated using the luminance distribution and luminance standard deviation of multiple pixels within each division section. (b) In the determination step, in accordance with a determination criterion of a predetermined shape index, determine the quality of the shape in the longitudinal direction of the strip-shaped base material from the shape indices of each divided section. Solutions such as the above can be more preferable solutions.

[0016] The quality control method for a strip-shaped base material according to the present invention that advantageously solves the above problems uses the shape measurement method for a strip-shaped base material according to any of the above, and cuts and removes a section determined to have a defective shape in the longitudinal direction of the strip-shaped base material.

[0017] The manufacturing method for a strip-shaped base material according to the present invention that advantageously solves the above problems uses the shape measurement method for a strip-shaped base material according to any of the above, and changes the manufacturing specifications of the strip-shaped base material so that the obtained shape index falls within a range of a predetermined shape index.

[0018] In addition, the manufacturing method for a strip-shaped base material according to the present invention can be a more preferable solution in that the strip-shaped base material is a steel strip and the manufacturing specifications are rolling conditions.

[0019] The shape measurement device for a strip-shaped base material according to the present invention that advantageously solves the above problems is a device that measures the shape of a strip-shaped base material during conveyance, and includes an imaging means that continuously captures images of both surfaces of the strip-shaped base material, an image processing means that calculates a shape index of the strip-shaped base material from the obtained images, and a determination means that determines the quality of the shape of the strip-shaped base material based on the obtained shape index.

[0020] In addition, the shape measurement device for a strip-shaped base material according to the present invention (c) The image processing means calculates the displacement amounts at both end positions and the center in the width direction of the strip-shaped base material after connecting a plurality of overlapping images in the width direction and the longitudinal direction of the strip-shaped base material, extracts a predetermined region of the strip-shaped base material, sets a plurality of divided sections divided in the width direction and the longitudinal direction, and has a function of calculating the shape index using the luminance distribution and the luminance standard deviation of a plurality of pixels in each divided section. (d) The determination means has a function of determining the quality of the shape in the longitudinal direction of the strip-shaped base material from the shape indexes of each divided section according to a preset determination criterion for the shape index. etc. can be more preferable solution means.

[0021] The manufacturing equipment for the strip-shaped base material according to the present invention that advantageously solves the above problems includes the shape measuring device for the strip-shaped base material according to any of the above, and using the obtained shape index or the determination result of the shape quality, means for cutting and removing the section determined to have a poor shape, and control means for changing the manufacturing specifications of the strip-shaped base material so that the obtained shape index falls within a preset range of a predetermined shape index. It is characterized by including either one or both of them.

Effect of the Invention

[0022] According to the present invention, for the surface of the strip-shaped base material, it can be easily and stably operated, and the imaging device of the shape measuring device itself can be used in combination with a surface defect detection device, so the maintenance cost can also be suppressed. Furthermore, since it is a method targeting a wide field of view and the entire width of the strip-shaped base material, it is possible to calculate the shape index without being affected by the meandering of the strip-shaped base material. The waving phenomenon of the strip-shaped base material can also be solved by the present invention. For example, although the wavelength of waving reaches dozens of meters, the wavelength due to shape defects such as stretching or bulging is about 600 mm. Therefore, if the shape index is calculated from the luminance standard deviation every 1 m in the longitudinal direction, the shape can be determined without being affected by waving.

Brief Description of the Drawings

[0023] [Figure 1] It is a schematic perspective view showing a configuration in which the shape measuring device for the strip-shaped base material according to an embodiment of the present invention is arranged on the manufacturing line of the strip-shaped base material. [Figure 2] It is an enlarged schematic view of the shape measuring device for the strip-shaped base material according to the above embodiment, where (a) is a schematic side view and (b) is a schematic front view. [Figure 3] It is a view showing an example of an image of the surface of the strip-shaped base material after imaging. [Figure 4]This flowchart illustrates each step of a method for measuring the shape of a strip-shaped substrate according to another embodiment of the present invention, where (a) shows an imaging step, (b) shows an example of an image processing step, and (c) shows an example of a shape determination step. [Figure 5] This is a schematic diagram showing an overview of the image processing steps for the shape measurement method described above, where (a) shows an example of an image to be processed, (b) shows the procedure for setting the division interval, and (c) shows an example of an image in the division interval. [Figure 6] This is an example of calculating the luminance distribution of a single divided section, where (a) represents the image of the target divided section and (b) is a graph representing the calculated luminance distribution. [Figure 7] This is a schematic diagram illustrating the determination of shape defects on the tail end of a steel plate, where (a) shows an example image of the target section, (b) is a graph showing the brightness standard deviation of the divided section, and (c) is a graph that determines shape defects from the longitudinal change of the shape index. [Modes for carrying out the invention]

[0024] The embodiments of the present invention will be described in detail below. Note that the drawings are schematic and may differ from actual examples. Furthermore, the following embodiments are illustrative examples of devices and methods for realizing the technical concept of the present invention, and do not limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0025] (Shape measuring device for strip-shaped substrates) Figure 1 shows an example of a shape measuring device being placed in a hot-rolled steel sheet manufacturing line as a manufacturing apparatus for strip-shaped substrates. In the hot-rolling equipment 1, after the steel sheet S is finish-rolled in the finishing rolling mill train 2, it passes through a cooling zone 2 where laminar cooling is performed, and is then wound into a hot-rolled steel strip coil by a coiler 4. In the example in Figure 1, a shape measuring device 3, which also serves as a surface inspection device, is installed downstream of the cooling zone 2 in the steel sheet conveying direction PL. Shape measuring devices for strip-shaped substrates are suitable for use in equipment that conveys strip-shaped substrates, such as cold-rolling equipment, annealing equipment, and strip-shaped substrate straightening equipment.

[0026] Figure 2(a) is a schematic enlarged side view showing the arrangement of the shape measuring device 3 in the hot rolling equipment. Figure 2(b) is a schematic front view, similarly viewed facing the transport direction PL of the steel plate S. Table 1 shows an example of specification information for the shape measuring device of the above embodiment. In the example in Figure 2, the upper surface of the steel plate S is measured by the upper surface shape measuring device 3A, and the lower surface of the steel plate S is measured by the lower surface shape measuring device 3B. For both the upper and lower surfaces, seven 2D area CCD cameras 3A1 and 3B1 and three strobe lights 3A2 and 3B2 are installed in a row in the width direction as imaging means. The area CCD cameras 3A1 and 3B1 are configured to capture the entire width of the steel plate S while overlapping their fields of view in the width direction. The strobe lights 3A2 and 3B2 are oriented inward so that the optical axes of the lights on both sides intersect with each other. The optical axes of the area CCD cameras 3A1 and 3B1 and the strobe lights 3A2 and 3B2 are inclined so that, in a side view, their optical axes intersect on the steel plate surface. Preferably, the optical axis CA of the area CCD cameras 3A1 and 3B1 and the optical axis LA of the strobe lights 3A2 and 3B2 are not in a specular reflection position, and are inclined to the same side with respect to the vertical plane perpendicular to the steel plate surface S and the transport direction PL. Preferably, both optical axes CA and LA are inclined towards the upstream side in the steel plate transport direction PL, and the optical axis LA of the illumination is inclined more than the optical axis CA of the camera. On the bottom side, in order to secure the field of view, a portion of the transport roll 6 is removed and a gate 6A is provided that is opened only during imaging. Preferably, a water drainage means (not shown) is provided upstream of the shape measuring device 3A on the top side. Examples of water drainage means include a high-speed water spray and an air compressor.

[0027] [Table 1]

[0028] The captured images are accumulated, for example, as a result of 50 to 200 strobe illuminations and captures per second, synchronized with seven cameras in each width direction of the steel plate S. Approximately 100 captures per second are preferred. Figure 3 shows multiple captured images joined together, taking into account overlapping portions. The images are arranged in the transport direction PL of the steel plate, from the leading edge LE to the trailing edge TE, with a portion of the section at the trailing edge TE shown.

[0029] The shape measuring device 3 includes, in addition to the imaging means described above, an image analysis means for analyzing the captured image and a determination means for determining whether the shape of the steel plate is good or bad, and may include, for example, a computer (not shown). The shape measuring device 3 may be connected to, for example, a higher-level computer that manages the rolling equipment and transmit the determination results of the steel plate shape.

[0030] (Method for measuring the shape of a strip-shaped substrate) Figure 4 is a flowchart illustrating a method for measuring the shape of a strip-shaped substrate using the shape measuring device described above. This embodiment includes an imaging step (Figure 4(a)), an image processing step (Figure 4(b)), and a determination step (Figure 4(c)) for determining whether the shape of the strip-shaped substrate is good or bad.

[0031] Figure 4 illustrates a method for measuring the shape of a steel sheet when manufacturing a hot-rolled steel sheet using the hot-rolling equipment shown in Figure 1. First, before starting the imaging step (S10), steel plate information is acquired (S11). The steel plate information acquired includes manufacturing specifications such as steel plate specifications, plate thickness, plate width, total length, total weight, and component composition, as well as operating conditions such as the reduction conditions of each rolling mill, the measured plate width, and the conveying speed. Next, when the leading edge (LE) of the steel plate reaches the imaging position of the shape measuring device 3, continuous imaging of the upper and lower surfaces of the steel plate S is started while strobe illumination is performed (S12). When the trailing edge (TE) of the steel plate passes the imaging position of the shape measuring device 3, imaging is stopped (S13). Then, the image of the predetermined section that was captured is saved (S14), and the imaging step is terminated (S15). In the example in Figure 4(a), the section from the front end to the tail end, 100m, is saved as a predetermined longitudinal length L1.

[0032] Next, the image processing step is started (S20). Figure 5 shows an overview of the image processing step. As shown in Figure 5(a), the edges of the steel plate S are detected from the image obtained for a predetermined section (S21). The edge EDR of the prime mover side DR and the edge EOP of the operator side OP are detected, respectively. Next, the widthwise center line CL of the steel plate S is drawn based on the detected edges, and the amount of center displacement is calculated. Then, as shown in Figure 5(b) as an example, the obtained image is divided equally in the width direction (S23). In Figure 5(b), the image is divided into 7 sections, dividing the total width W of the steel plate S into lengths of W / 7, but the number of divisions is arbitrary. Considering the accuracy of the analysis and the complexity of the calculation, the number of divisions in the width direction is preferably between 5 and 10. Then, the longitudinal length L1 to be analyzed is divided equally (S24). In the example in Figure 5(b), the section L1 = 100m is divided into 100 sections of 1m each. An example of an image of a divided section is shown in Figure 5(c). By making the longitudinal division section about 1m, shape defects such as elongation on one side and elongation on the other can be detected without the influence of long-wavelength waving. Next, the image is analyzed for each individual segment and the brightness distribution is calculated (S25). Figure 6 shows an example of the brightness distribution. In Figure 6(a), the segment has 546 pixels and the brightness is measured in grayscale with 256 levels. Figure 6(b) is a graph showing the number of pixels for each brightness level on the vertical axis. The standard deviation of brightness is calculated as a shape index from the brightness distribution of each segment (S26). Then, the image analysis step is completed (S27). Here, the number of pixels and the number of brightness levels are arbitrary, but it is preferable to determine them considering the analysis accuracy and computation time.

[0033] Then, the step of determining the shape of the steel plate is started (S30). First, for each steel sheet standard obtained in step S11, a threshold for the luminance standard deviation used to determine the quality of the shape is obtained (S31). For example, the threshold for the luminance standard deviation may be determined based on past manufacturing results, such as the relationship between shape defects and operational problems. Next, the luminance standard deviation of each segment obtained in the image analysis step is subjected to a moving average process over an arbitrary interval in the longitudinal direction (S32). Next, for example, starting from the tail end TE, the interval is calculated until the moving average luminance standard deviation in the transport direction PL falls below the acquired threshold (S33). Then, the interval from the tail end TE until the luminance standard deviation falls below the acquired threshold is sent to the higher-level computer as the shape defect interval (S34). Finally, the judgment step ends (S35).

[0034] Figure 7 illustrates an overview of the judgment steps. The image in Figure 7(a) is analyzed, and the luminance standard deviation for each divided section is shown graphically in Figure 7(b). The longitudinal moving average uses OP2 and DR2 (see Figure 5(b)) including 1 / 4 in the width direction, and is averaged over 5 points to become AOP and ADR. Figure 5(c) is a graph showing the sum of the moving averaged AOP and ADR as "OP2+DR2" and the difference as "OP2-DR2". As is clear from Figure 7(a), the operator-side OP of the steel plate extends at the tail end TE, causing it to undulate, and the luminance standard deviation on the operator side is large. In this example, the judgment was made when the shape index, defined as "OP2-DR2" for the degree of shape defect, falls below the threshold of 30. The section from the tail end TE to 17m was defined as the shape defect section due to the uneven elongation. The threshold of the shape index described above can be changed from 10 to 50 depending on the tolerance for steel strip passage in the next process, and is preferably 20 to 40.

[0035] The quality control method for a strip-shaped substrate according to this embodiment further includes a step of using the above-described shape measurement method for the strip-shaped substrate to cut and remove sections of the strip-shaped substrate that are determined to have a defective shape in the longitudinal direction. For example, in the above determination step, based on the section of defective shape transmitted to the host computer, the shear equipment is operated on the finishing line to cut and remove a section of defective shape of a predetermined length from the tail end TE. By doing so, for example, when the tail end TE of the preceding material and the leading end LE of the following material are joined and continuously rolled in the cold rolling equipment of the next process, it is possible to suppress the meandering of the steel plate S due to the defective shape, preventing the edge from colliding with the guide and causing scratches or damage to the equipment.

[0036] The method for manufacturing a strip-shaped substrate according to this embodiment includes the step of changing the manufacturing specifications of the strip-shaped substrate using the above-described method for measuring the shape of the strip-shaped substrate, so that the obtained shape index falls within a predetermined range of shape indexes. For example, if the shape defect is a one-sided elongation where one edge is stretched, the reduction force between the motor-side DR and the operator-side OP of the hot rolling mill can be changed. Also, if the shape defect is an elongation in the widthwise center, so-called belly elongation, it is possible to change the effect of the roll crown by shifting the work roll of the hot rolling mill axially. [Industrial applicability]

[0037] According to the method and apparatus of the present invention, shape determination can be easily and stably performed on the surface of a strip-shaped substrate, and maintenance costs can be reduced, thus contributing to improved productivity and being industrially useful. [Explanation of Symbols]

[0038] 100 Hot rolling equipment 1. Finishing rolling mill train 2 Cooling Zones 3. Shape measuring device (surface inspection device) 3A (Top side) Shape measuring device 3A1 Area CCD Camera 3A2 Strobe lighting 3B (Bottom side) Shape measuring device 3B1 Area CCD Camera 3B2 Strobe lighting 3C Gate 4 Coira 6 Conveyor Rolls 6A Gate S Steel plate (strip-shaped base material) PL steel plate transport direction (pass line) LE tip side TE caudal side DR (Driver side) OP operator side CA (Optical axis of area CCD camera) LA (optical axis of strobe lighting) EDR (End-Driver Edge) of Steel Plate EOP (Steel Plate Operator Side) Edge CL (center line in the width direction of the steel plate) L1 (Length to be analyzed)

Claims

1. A method for measuring the shape of a strip-shaped substrate, An imaging step in which images are captured from both sides of a strip-shaped substrate, An image processing step for calculating the shape index of the strip-shaped substrate from the obtained image, A determination step in which the quality of the shape of the strip-shaped substrate is determined based on the obtained shape index, Includes, In the aforementioned image processing step, After concatenating multiple images that overlap in the width and longitudinal directions of the strip-shaped substrate, the displacement amounts at both ends and the center of the strip-shaped substrate in the width direction are calculated. A predetermined region of the strip-shaped substrate is extracted, and multiple divided sections are set by dividing it in the width direction and the length direction. A method for measuring the shape of a strip-shaped substrate, comprising calculating the shape index using the luminance distribution and luminance standard deviation of multiple pixels within each divided section.

2. In the determination step, A method for measuring the shape of a strip-shaped substrate according to claim 1, wherein the quality of the shape of the strip-shaped substrate in the longitudinal direction is determined from the shape index of each divided section according to predetermined criteria for determining the shape index.

3. A method for measuring the shape of a strip-shaped substrate, An imaging step in which images are captured from both sides of a strip-shaped substrate, An image processing step for calculating the shape index of the strip-shaped substrate from the obtained image, A determination step in which the quality of the shape of the strip-shaped substrate is determined based on the obtained shape index, Includes, In the image processing step, a predetermined area of ​​the strip-shaped substrate is extracted, and a plurality of divided sections are set by dividing it in the width direction and the longitudinal direction. In the aforementioned determination step, A method for measuring the shape of a strip-shaped substrate, which determines the quality of the shape in the longitudinal direction of the strip-shaped substrate from the shape index of each divided section, according to predetermined criteria for determining shape indexes.

4. A method for quality control of a strip-shaped substrate, comprising using the shape measurement method for the strip-shaped substrate described in any one of claims 1 to 3, and cutting and removing a section of the strip-shaped substrate in the longitudinal direction that is determined to have a defective shape.

5. A method for manufacturing a strip-shaped substrate, comprising using the shape measurement method for the strip-shaped substrate described in any one of claims 1 to 3, and modifying the manufacturing specifications of the strip-shaped substrate so that the obtained shape index falls within a predetermined range of shape indexes.

6. The method for manufacturing a strip-shaped substrate according to claim 5, wherein the strip-shaped substrate is a steel strip and the manufacturing specification is rolling conditions.

7. An apparatus for measuring the shape of a strip-shaped substrate while it is being transported, An imaging means for continuously capturing images of both sides of the strip-shaped substrate, Image processing means for calculating a shape index of the strip-shaped substrate from the obtained image, A determination means for determining the quality of the shape of the strip-shaped substrate based on the obtained shape index, Equipped with, The aforementioned image processing means is After concatenating multiple images that overlap in the width and longitudinal directions of the strip-shaped substrate, the displacement amounts at both ends and the center of the strip-shaped substrate in the width direction are calculated. A predetermined region of the strip-shaped substrate is extracted, and multiple divided sections are set by dividing it in the width direction and the length direction. A shape measuring device for a strip-shaped substrate, having the function of calculating the shape index using the luminance distribution and luminance standard deviation of multiple pixels within each divided section.

8. The determination means is It has a function to determine the quality of the shape of the strip-shaped substrate in the longitudinal direction from the shape index of each divided section, according to predetermined criteria for shape index determination. The shape measuring device for a strip-shaped substrate according to claim 7.

9. An apparatus for measuring the shape of a strip-shaped substrate while it is being transported, An imaging means for continuously capturing images of both sides of the strip-shaped substrate, Image processing means for calculating a shape index of the strip-shaped substrate from the obtained image, A determination means for determining the quality of the shape of the strip-shaped substrate based on the obtained shape index, Equipped with, The aforementioned image processing means is A predetermined region of the strip-shaped substrate is extracted, and multiple divided sections are set by dividing it in the width direction and the length direction. The determination means is, A shape measuring device for a strip-shaped substrate, having the function of determining the quality of the longitudinal shape of the strip-shaped substrate from the shape indicators of each divided section, according to predetermined criteria for determining shape indicators.

10. A shape measuring device for a strip-shaped substrate according to any one of claims 7 to 9, A manufacturing apparatus for a strip-shaped substrate, comprising either or both of the following: a means for cutting and removing sections determined to have a defective shape using the obtained shape index or the result of determining whether the shape is good or bad; and a control means for changing the manufacturing specifications of the strip-shaped substrate so that the obtained shape index falls within a predetermined range of shape indexes.

Images