Inspection apparatus, inspection method, and method for manufacturing steel plates

Abstract

The present invention provides an inspection device that improves the degree of freedom in arranging the optical system used to inspect surface defects of steel plates. [Solution] The inspection device 10 for inspecting the surface A of a steel plate S comprises a first robot 11 having a first arm 112 to which a grinding wheel 111 is attached, which automatically grinds an inspection range R corresponding to the plate width W on the surface A of the stopped steel plate S; a second robot 12 having a second arm 123 to which a light source 121 and an imaging device 122 are attached, which automatically images the inspection range R; a control unit 131 that controls the operation of the first robot 11 and the second robot 12, respectively; and an image analysis unit 132 that performs image processing on the image captured by the imaging device 122 and determines whether or not there are defects on the surface A of the steel plate S. The control unit 131 adjusts the distance and angle to the surface A of the steel plate S for the light source 121 and the imaging device 122, respectively.

Description

[Technical Field]

[0001] This disclosure relates to an inspection device, an inspection method, and a method for manufacturing steel sheets. For example, this disclosure relates to an inspection device and an inspection method for automatically detecting the presence or absence of surface defects in steel sheets, such as cold-rolled steel sheets and surface-treated steel sheets that have undergone a rolling process, and to a method for manufacturing steel sheets that includes inspecting steel sheets using the inspection method. [Background technology]

[0002] Conventionally, automation technologies are known for operations such as grinding steel plates and inspecting surface defects of steel plates, which are performed on inspection lines in rolling processes. For example, Patent Document 1 discloses a grinding wheel handle for inspecting the surface of steel plates that eliminates the need for break-in grinding to optimize the grinding wheel shape, enables continuous, stable, and uniform grinding, and can be incorporated into an automated inspection device. For example, Patent Document 2 discloses a detection method that calculates the coordinates of all detected defects, including roll transfer defects and over-detection due to disturbances such as rolling oil droplets and water droplets, and calculates the longitudinal spacing of the steel plate, thereby enabling the online determination of only perfectly periodic roll transfer defects, regardless of the presence or absence of disturbance factors. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-155716 [Patent Document 2] Japanese Patent Application Publication No. 6-294759 [Overview of the project] [Problems that the invention aims to solve]

[0004] Neither of the prior art described in Patent Documents 1 and 2 adequately considered how to improve the degree of freedom in arranging the optical system used to inspect surface defects of steel plates.

[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide an inspection device, an inspection method, and a method for manufacturing steel sheets that improve the degree of freedom in arranging the optical system used to inspect defects on the surface of steel sheets. [Means for solving the problem]

[0006] (1) An inspection apparatus according to one embodiment of the present disclosure An inspection device for inspecting the surface of a steel plate, A first robot having a first arm to which a grinding wheel is attached, which automatically grinds an inspection area on the surface of the stopped steel plate corresponding to the plate width, A second robot having a second arm to which a light source and an imaging device are attached, and which automatically images the inspection area, A control unit that controls the operation of the first robot and the second robot, An image analysis unit performs image processing on the image captured by the imaging device and determines whether or not there are defects on the surface of the steel plate. Equipped with, The control unit adjusts the distance and angle to the surface of the steel plate for each of the light source and the imaging device.

[0007] (2) As one embodiment of the present disclosure, in (1), The control unit adjusts the distance and angle of the light source and the distance and angle of the imaging device along concentric circles centered on the imaging point on the surface of the steel plate.

[0008] (3) In one embodiment of the present disclosure, in (1) or (2), The control unit adjusts the distance according to the thickness of the steel plate.

[0009] (4) In one embodiment of the present disclosure, in any of (1) to (3), The control unit adjusts the angle according to the type of steel plate.

[0010] (5) In one embodiment of the present disclosure, in any of (1) to (4), The control unit adjusts the angle according to the type of flaw on the surface of the steel plate.

[0011] (6) As one embodiment of the present disclosure, in any one of (1) to (5), The image analysis unit executes texture analysis as the image processing.

[0012] (7) The inspection method according to one embodiment of the present disclosure is An inspection method for inspecting the surface of a steel plate, automatically grinding the inspection range corresponding to the plate width on the surface of the stopped steel plate with a first robot having a first arm to which a grindstone is attached; automatically imaging the inspection range with a second robot having a second arm to which a light source and an imaging device are attached; controlling the operations of each of the first robot and the second robot; executing image processing on the image captured by the imaging device to determine the presence or absence of flaws on the surface of the steel plate; including Automatically imaging the inspection range includes adjusting the distance and angle of each of the light source and the imaging device with respect to the surface of the steel plate.

[0013] (8) The manufacturing method of a steel plate according to one embodiment of the present disclosure is including inspecting the steel plate using the inspection method of (7).

Advantages of the Invention

[0014] According to the inspection apparatus, inspection method, and manufacturing method of a steel plate according to one embodiment of the present disclosure, the degree of freedom in arranging the optical system used for inspecting flaws on the surface of the steel plate is improved.

Brief Description of the Drawings

[0015] [Figure 1] It is a configuration diagram illustrating a part of the configuration of an inspection apparatus according to one embodiment of the present disclosure. [Figure 2]This is a block diagram showing an example of the configuration of an inspection system including an inspection device according to one embodiment of the present disclosure. [Figure 3] Figure 2 is a first schematic diagram illustrating an example of the operation of the inspection device. [Figure 4] This is a second schematic diagram illustrating an example of the operation of the inspection device shown in Figure 2. [Figure 5] Figure 2 is a flowchart illustrating an example of the operation of the inspection device. [Figure 6] This is a first schematic diagram illustrating an example of the operation of the inspection apparatus according to the embodiment of this disclosure. [Figure 7A] This is a second schematic diagram illustrating an example of the operation of the inspection apparatus according to the embodiment of this disclosure. [Figure 7B] This is a third schematic diagram illustrating an example of the operation of the inspection apparatus according to the embodiment of this disclosure. [Figure 8] This is a fourth schematic diagram illustrating an example of the operation of the inspection apparatus according to the embodiment of this disclosure. [Modes for carrying out the invention]

[0016] This section provides a more detailed explanation of the background and problems of conventional technologies.

[0017] In the steel sheet rolling process, foreign matter adhering to the rolls, or irregularities created on the rolls themselves due to foreign matter getting caught in them, can be transferred to the steel sheet, resulting in surface defects. Such irregular defects are extremely small, with a height of only a few micrometers, and are not easily detected by visual inspection in their current state. However, when the surface of the steel sheet is painted in a later process, and the surface roughness of the steel sheet becomes smooth, these irregular defects become clearly visible, resulting in appearance problems.

[0018] Unevenness defects are caused by faulty rolls. Therefore, once unevenness defects occur, they will recur periodically and continuously until the rolls are replaced. For this reason, it is extremely important to detect and address such unevenness defects before shipment.

[0019] To detect surface irregularities, the inspection line in the rolling process temporarily stops the movement of the steel plates during operation, grinds the surface of the steel plates with a grinding wheel, and then performs a visual inspection. Since the grinding wheel grips the micro-concave areas more strongly than the normal areas, and the grinding wheel grips the micro-concave areas less strongly than the normal areas, grinding makes the difference in surface irregularities clear, making them easier to detect visually.

[0020] However, such inspections are performed manually. The uniform grinding and visual inspection required to detect minute defects heavily depend on the skill of the worker. Furthermore, because workers come into contact with the steel plates during inspection, they risk cuts to their hands and feet on the edges. Given the wide inspection area and the physically demanding nature of the work, automation was highly desired.

[0021] As an automation technology for such tasks, Patent Document 1 discloses an invention relating to an apparatus that automatically performs grinding and defect inspection of the surface of a steel plate. In addition, as a technology for detecting roll-type irregularities, Patent Document 2 discloses a method for detecting irregularities from image data captured of the surface of a steel plate illuminated by strobe lighting.

[0022] However, the prior art described in Patent Document 1 had the problem that the automating the grinding process increased the variability in grinding unevenness. In addition, there was a problem that the conditions for defects that could be recognized by image recognition in the automated inspection process were limited, resulting in a decrease in detection performance.

[0023] The conventional optical system described in Patent Document 2 has a fixed positional relationship between the light source and the camera, making it difficult to reproduce the observations of steel plates from various directions that workers had previously performed. In addition, when it is necessary to combine multiple optical system conditions to cover all defects in the target object, it is necessary to install a number of light source and camera sets corresponding to the multiple optical system conditions, which presents challenges in terms of installation space and cost.

[0024] This disclosure has been made in view of the above-mentioned problems and aims to provide an inspection device, an inspection method, and a method for manufacturing steel sheets that improve the degree of freedom in arranging the optical system used to inspect defects on the surface of steel sheets. For example, this disclosure provides a technology that allows imaging of minute surface defects from various distances and angles using a single optical system by attaching a light source and an imaging device to the tip of a robot arm. For example, this disclosure provides a technology that can detect minute surface defects caused by grinding by focusing on differences in the pattern (texture) of steel sheets and using texture analysis, an image analysis method that mimics human visual perception.

[0025] The following description will primarily focus on one embodiment of the present disclosure with reference to the attached drawings. The following description also applies to an inspection system 1 including an inspection device 10, an inspection method performed by the inspection device 10, and a method for manufacturing a steel sheet S, including inspecting the steel sheet S using the inspection method, to which the present disclosure is applied.

[0026] Figure 1 is a diagram illustrating a part of the configuration of an inspection apparatus 10 according to one embodiment of the present disclosure. Referring to Figure 1, the configuration and functions of the inspection apparatus 10 according to one embodiment of the present disclosure will be mainly described. The inspection apparatus 10 has a first robot 11 and a second robot 12.

[0027] The inspection device 10 inspects the surface A of the steel sheet S. The inspection device 10 is placed, for example, on an inspection line for the rolling process of the steel sheet S, and detects irregular defects that occur on the surface A of the steel sheet S during the rolling process as defects on the surface A of the steel sheet S. In this disclosure, "defect" includes, for example, irregular defects. The inspection device 10, for example, in an inspection line for the rolling process, temporarily stops the movement of the steel sheet S during operation and grinds the surface A of the steel sheet S. The inspection device 10 takes an image of the surface A of the steel sheet S after the grinding work has been done and performs image processing to determine whether or not there are defects on the surface A of the steel sheet S.

[0028] The inspection device 10 automatically performs grinding and defect inspection of the surface A of the steel plate S. The inspection device 10 has two types of robots, including a first robot 11 and a second robot 12, to automate the grinding and visual inspection of defects that would otherwise be done manually.

[0029] The first robot 11 includes, for example, a grinding robot. The first robot 11 performs grinding work. The first robot 11 has a first arm 112 to which a grinding wheel 111 is attached, and automatically grinds an inspection area on the surface A of a stopped steel plate S corresponding to the plate width W. For example, with the grinding wheel 111 attached to the tip of the first arm 112, the first robot 11 performs grinding work on the surface A of a stopped steel plate S on the inspection line.

[0030] In the first robot 11, the grinding wheel 111 may be directly attached to the first arm 112 by any means such as screwing, joining, engaging, and fitting. In the first robot 11, the grinding wheel 111 may also be attached to the first arm 112 by being gripped by an end effector including a robot hand and a robot gripper.

[0031] The second robot 12 includes, for example, an optical robot. The second robot 12 performs defect inspection work. The second robot 12 has a second arm 123 to which a light source 121 and an imaging device 122 are attached, and automatically images an inspection range corresponding to the width W of the steel plate S on the surface A of the stopped steel plate S. For example, with the light source 121 and imaging device 122 attached to the tip of the second arm 123, the second robot 12 follows behind the first robot 11 to image the surface A of the steel plate S after the grinding work has been performed.

[0032] The light source 121 includes, for example, an illumination light source that illuminates the surface A of the steel plate S so that the imaging device 122 can clearly image defects on the surface A of the steel plate S. The imaging device 122 includes, for example, a camera. In the second robot 12, each of the light source 121 and the imaging device 122 may be directly attached to the second arm 123 by any means such as screwing, joining, engaging, and fitting. In the second robot 12, each of the light source 121 and the imaging device 122 may be attached to the second arm 123 by being gripped by an end effector including a robot hand and a robot gripper.

[0033] Figure 2 is a block diagram showing an example of the configuration of an inspection system 1 including an inspection device 10 according to one embodiment of the present disclosure. An example of the configuration and function of the inspection system 1 including the inspection device 10 according to one embodiment of the present disclosure will be mainly described with reference to Figure 2. In addition to the inspection device 10, the inspection system 1 includes a line control device 20.

[0034] In addition to the first robot 11 and the second robot 12 shown in Figure 1, the inspection device 10 further includes a computer 13. The computer 13 includes a control unit 131, an image analysis unit 132, and a storage unit 133.

[0035] The computer 13 may be a general-purpose electronic device, such as a PC (Personal Computer), tablet PC, smartphone, or wearable device. The computer 13 is not limited to these, and may be one or more server devices that can communicate with each other, or other electronic devices dedicated to the inspection device 10.

[0036] The control unit 131 includes one or more processors, one or more programmable circuits, one or more dedicated circuits, or a combination thereof. In this disclosure, "processor" refers to, but is not limited to, a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for a specific process. "Programmable circuit" refers to, but is not limited to, an FPGA (Field-Programmable Gate Array). "Dedicated circuit" refers to, but is not limited to, an ASIC (Application Specific Integrated Circuit).

[0037] The control unit 131 is connected to the first robot 11 and the second robot 12 in a communication manner. The control unit 131 outputs operation commands to the first robot 11 and the second robot 12. The control unit 131 controls the operation of the first robot 11 and the second robot 12.

[0038] The image analysis unit 132 includes one or more processors, one or more programmable circuits, one or more dedicated circuits, or a combination thereof. The processor of the image analysis unit 132 may be the same as or different from the processor of the control unit 131. The programmable circuits of the image analysis unit 132 may be the same as or different from the programmable circuits of the control unit 131. The dedicated circuits of the image analysis unit 132 may be the same as or different from the dedicated circuits of the control unit 131.

[0039] The image analysis unit 132 is communicatively connected to the imaging device 122 attached to the second robot 12. The image analysis unit 132 acquires images captured by the imaging device 122 from the imaging device 122. The image analysis unit 132 performs image processing on the images captured by the imaging device 122 to determine whether or not there are defects on the surface A of the steel plate S.

[0040] The storage unit 133 includes storage modules such as HDD (Hard Disk Drive), SSD (Solid State Drive), EEPROM (Electrically Erasable Programmable Read-Only Memory), ROM (Read-Only Memory), and RAM (Random Access Memory). The storage unit 133 may function as a main memory module, an auxiliary memory module, or a cache memory. The storage unit 133 is not limited to those built into the computer 13 of the inspection device 10, and may include storage media such as removable media. Such removable media include USB (Universal Serial Bus) memory, CD (Compact Disc), DVD (Digital Versatile Disc), and BD (Blu-ray® Disc).

[0041] The storage unit 133 stores information necessary to realize the operation of the inspection device 10. The storage unit 133 stores information obtained through the operation of the inspection device 10. For example, the storage unit 133 can store an operating system (OS), various programs, and various data. For example, the storage unit 133 stores a database that stores the determination results of whether or not there are defects on the surface A of the steel plate S by the image analysis unit 132. This database stores data of normal analysis images in which the image analysis unit 132 determined that there are no defects on the surface A of the steel plate S, and data of abnormal analysis images in which the image analysis unit 132 determined that there are defects on the surface A of the steel plate S.

[0042] The line control device 20 is any computer that functions as a higher-level computer in the inspection system 1. The line control device 20 may be a general-purpose electronic device, such as a PC, tablet PC, smartphone, or wearable device. The line control device 20 is not limited to these, and may be one or more server devices that can communicate with each other, or other electronic devices dedicated to the inspection system 1.

[0043] The line control device 20 is communicatively connected to the computer 13. The line control device 20 provides the computer 13 with information necessary to realize the operation of the inspection device 10. For example, the line control device 20 provides the control unit 131 of the computer 13 with specification data of the steel plate S. In this disclosure, "specification data" includes, for example, data such as plate width, plate thickness, and steel type. In addition, the line control device 20 provides the storage unit 133 of the computer 13 with information such as, for example, the coil number of the steel plate S to be inspected by the inspection device 10 and the longitudinal position of the steel plate S.

[0044] Figure 3 is a first schematic diagram illustrating an example of the operation of the inspection device 10 shown in Figure 2.

[0045] The control unit 131 of the inspection device 10 determines the inspection range R based on, for example, the width W of the steel plate S to be inspected and the length L of the steel plate S in the longitudinal direction D1, which are obtained from the line control device 20, which is higher in power than the inspection device 10. The control unit 131 divides the inspection range R along the longitudinal direction D1 of the steel plate S into at least one section and controls the first robot 11 to perform grinding work sequentially for each section.

[0046] For example, the control unit 131 divides the inspection range R into five sections R1, R2, R3, R4, and R5, and causes the first robot 11 to perform grinding operations sequentially from section R1 to section R5. The control unit 131 controls the first arm 112 of the first robot 11 so that the grinding wheel 111 attached to the tip of the first arm 112 of the first robot 11 moves along the path T in relation to the inspection range R corresponding to the plate width W on the surface A of the stopped steel plate S.

[0047] The control unit 131 of the inspection device 10 controls the second arm 123 of the second robot 12 so that the light source 121 and imaging device 122, which are attached to the tip of the second arm 123 of the second robot 12, follow behind the first arm 112 of the first robot 11 along the movement line T. As a result, the control unit 131 uses the light source 121 and imaging device 122 to image the surface A of the steel plate S after it has been ground by the grinding wheel 111 using the first arm 112 of the first robot 11.

[0048] At this time, the control unit 131 sets the interval width L0 of the inspection range R to be the same as the inspection width of the imaging device 122, thereby allowing the imaging device 122 to sequentially image the surface A of the steel plate S after grinding by the first robot 11, and minimizing the time required for inspection. The control unit 131 sets the interval width L0 according to the resolution of the imaging device 122 and causes the imaging device 122 to image the entirety of each interval as one image for each interval width L0. For example, the control unit 131 causes the imaging device 122 to image the entirety of each of the five intervals R1, R2, R3, R4, and R5, and acquires five images.

[0049] Figure 4 is a second schematic diagram illustrating an example of the operation of the inspection device 10 shown in Figure 2.

[0050] The control unit 131 of the inspection device 10 adjusts the distance and angle of the light source 121 and the imaging device 122, each attached to the tip of the second arm 123 of the second robot 12, relative to the surface A of the steel plate S. In other words, the second robot 12 can change the distance and angle of the light source 121 and the imaging device 122 relative to the surface A of the steel plate S at the second arm 123.

[0051] At this time, the control unit 131 adjusts the distance and angle of the light source 121 and the distance and angle of the imaging device 122 along concentric circles centered on the imaging point P on the surface A of the steel plate S. For example, the control unit 131 positions the light source 121 on a first arc C1 with a first radius L1 centered on the imaging point P, sets the distance of the light source 121 to the surface A as the first radius L1, and adjusts the angle of the light source 121 to the surface A on the first arc C1. For example, the control unit 131 positions the imaging device 122 on a second arc C2 with a second radius L2 centered on the imaging point P, sets the distance of the imaging device 122 to the surface A as the second radius L2, and adjusts the angle of the imaging device 122 to the surface A on the second arc C2.

[0052] As described above, the light source 121 and imaging device 122 attached to the second arm 123 of the second robot 12 can be arranged in concentric circles around the imaging point P. The inspection device 10 can perform imaging at various light source angles and camera angles using a single optical system including the light source 121 and imaging device 122.

[0053] As described above, the control unit 131 of the inspection device 10 acquires specification data of the steel plate S from the line control device 20. The control unit 131 adjusts the distance of the light source 121 and the imaging device 122 to each surface A according to the thickness of the steel plate S included in the acquired specification data of the steel plate S. At this time, the control unit 131 may store data relating the thickness of the steel plate S and the distance of the light source 121 and the imaging device 122 to each surface A in the storage unit 133 in advance, and read out this data from the storage unit 133 when adjusting the distance during the actual inspection.

[0054] In addition, the control unit 131 of the inspection device 10 adjusts the angles of the light source 121 and the imaging device 122 with respect to the respective surface A, according to the steel type of the steel plate S included in the acquired specification data of the steel plate S. At this time, the control unit 131 may pre-store data in the storage unit 133 that associates the steel type of the steel plate S with the angles of the light source 121 and the imaging device 122 with respect to the respective surface A, and then read this data from the storage unit 133 when adjusting the angles during the actual inspection.

[0055] In addition to, or instead of, the control unit 131 of the inspection device 10 may adjust the angles of the light source 121 and the imaging device 122 with respect to surface A, according to the type of defect on surface A of the steel plate S. For example, the control unit 131 may adjust the angles of the light source 121 and the imaging device 122 with respect to surface A, according to the type of defect on surface A of the steel plate S, which corresponds to the type of steel plate S included in the acquired specifications data of the steel plate S. In this case, the control unit 131 may store data in the storage unit 133 in advance that associates the type of defect on surface A of the steel plate S with the angles of the light source 121 and the imaging device 122 with respect to surface A, and read this data from the storage unit 133 when adjusting the angles during the actual inspection.

[0056] For example, the control unit 131 of the inspection device 10 may adjust the angles of the light source 121 and the imaging device 122 with respect to the surface A of the steel plate S according to the type of defect to be detected, thereby changing the optical system conditions. The control unit 131 may repeat the process of changing the optical system conditions as many times as there are types of defects to be detected by scanning.

[0057] For example, the control unit 131 of the inspection device 10 may adjust the angles of the light source 121 and the imaging device 122 with respect to the surface A under first optical system conditions for detecting a first type of defect, and cause the imaging device 122 to image the inspection range R. Once the imaging device 122 has finished imaging the inspection range R, the control unit 131 may adjust the angles of the light source 121 and the imaging device 122 with respect to the surface A under second optical system conditions for detecting a second type of defect, and cause the imaging device 122 to image the inspection range R again. The control unit 131 may repeat the angle adjustment and imaging process for as many times as there are types of defects to be detected by scanning.

[0058] The image analysis unit 132 may perform image processing on each of the multiple images obtained when the imaging device 122 captures the inspection area R for each of the multiple types of defects, and determine whether or not there are defects on the surface A of the steel plate S. In this way, the inspection device 10 can accurately determine whether or not there are defects on the surface A of the steel plate S.

[0059] The control unit 131 of the inspection device 10 operates the second robot 12 to inspect the inspection range R corresponding to the plate width W using an optical system arrangement preset for each specification data of the steel plate S. The image analysis unit 132 of the inspection device 10 performs image processing on the image of the surface A captured using the light source 121 and imaging device 122 included in the optical system, and determines whether or not there are defects on the surface A of the steel plate S.

[0060] As described later, the image analysis unit 132 may perform texture analysis as image processing. The image analysis unit 132 may use the image captured by the second robot 12 to inspect the surface A of the steel plate S for defects, i.e., flaws, by texture analysis. The image analysis unit 132 associates the judgment result based on the analysis and the analyzed image with the coil number and the longitudinal position of the steel plate S obtained as information from the line control device 20, and stores them in the database stored in the storage unit 133.

[0061] Figure 5 is a flowchart illustrating an example of the operation of the inspection device 10 shown in Figure 2. Referring to Figure 5, we will primarily describe an example of an inspection method performed by the computer 13 of the inspection device 10 shown in Figure 2. The inspection method performed by the inspection device 10 is an inspection method for inspecting the surface A of the steel plate S.

[0062] In step S101, the control unit 131 of the computer 13 stores data in the storage unit 133 in advance. This data includes, for example, first data relating the thickness of the steel plate S to the respective distances of the light source 121 and the imaging device 122 to surface A. This data also includes, for example, second data relating the type of steel of the steel plate S to the respective angles of the light source 121 and the imaging device 122 to surface A.

[0063] In step S102, the control unit 131 of the computer 13 controls the operation of the first robot 11 and the second robot 12, respectively.

[0064] In step S103, the first robot 11, under the control of the control unit 131 in step S102, automatically grinds the surface A of the stopped steel plate S within an inspection range R corresponding to the plate width W, using the first arm 112 to which the grinding wheel 111 is attached.

[0065] In step S104, the second robot 12, under the control of the control unit 131 in step S102, automatically images an inspection range R corresponding to the plate width W on the surface A of the stopped steel plate S using the second arm 123 to which the light source 121 and imaging device 122 are attached. Automatically imaging the inspection range R in step S104 includes adjusting the distance and angle between the light source 121 and the imaging device 122 and the surface A of the steel plate S.

[0066] At this time, the control unit 131 of the computer 13 adjusts the distance of the light source 121 and the imaging device 122 to the respective surfaces A according to the thickness of the steel plate S included in the specification data of the steel plate S acquired from the line control device 20. At this time, the control unit 131 may read out and use the first data that was previously stored in the storage unit 133 in step S101.

[0067] In addition, the control unit 131 of the computer 13 adjusts the angles of the light source 121 and the imaging device 122 with respect to the respective surfaces A, according to the type of steel of the steel plate S included in the specification data of the steel plate S acquired from the line control device 20. At this time, the control unit 131 may read out and use the second data that was previously stored in the storage unit 133 in step S101.

[0068] In step S105, the image analysis unit 132 of the computer 13 performs image processing on the image captured by the imaging device 122 to determine whether or not there are defects on the surface A of the steel plate S. At this time, the image analysis unit 132 may perform texture analysis as part of the image processing.

[0069] The steel sheet S may be manufactured using the inspection method described above. In other words, it should be noted that a method for manufacturing the steel sheet S, which includes inspecting the steel sheet S using the inspection method described above, is also included in the scope of this disclosure.

[0070] According to the inspection apparatus 10 of the above embodiment, the degree of freedom in arranging the optical system used to inspect defects on the surface A of the steel plate S is improved. The inspection apparatus 10 adjusts the distance and angle of the light source 121 and the imaging device 122 relative to the surface A of the steel plate S. As a result, the inspection apparatus 10 can perform imaging at various light source angles and camera angles with a single set of optical systems including the light source 121 and the imaging device 122. Even when the inspection apparatus 10 is configured with a single set of optical systems, the positions of the light source 121 and the imaging device 122 can be flexibly changed by adjusting the second arm 123 of the second robot 12 when imaging under multiple optical system conditions is required. Therefore, the inspection apparatus 10 does not require the arrangement of multiple sets of optical systems in the second robot 12, and the installation space and equipment costs of the second robot 12 can be reduced.

[0071] The inspection device 10 adjusts the distance and angle of the light source 121 and the distance and angle of the imaging device 122 along concentric circles centered on the imaging point P on the surface A of the steel plate S. This allows the inspection device 10 to easily adjust the angle of the imaging device 122 relative to the imaging point P while maintaining the optimal distance at which the imaging device 122 is in focus relative to the imaging point P. In addition, the inspection device 10 can also easily adjust the position of the light source 121 in accordance with the optimized position of the imaging device 122.

[0072] The inspection device 10 is designed to handle defects on the surface A of a steel plate S. For example, if the imaging device 122 is positioned at a first angle, the defect may not be recognizable in image processing. However, if it is positioned at a second angle different from the first angle, the defect may be recognizable in image processing. Even in such cases, the inspection device 10 can optimize the angle for each defect on the surface A of the steel plate S and image the defect with an appropriate optical system configuration. Therefore, the inspection device 10 can clearly acquire an analysis image for each defect on the surface A of the steel plate S and accurately determine whether or not there is a defect on the surface A of the steel plate S.

[0073] The inspection device 10 adjusts the distance according to the thickness of the steel plate S. This makes it possible for the inspection device 10 to position the imaging device 122 at the optimal distance so that the imaging device 122 is in focus on the surface A of the steel plate S having a predetermined thickness.

[0074] The inspection device 10 adjusts its angle according to the steel type of the steel plate S. This allows the inspection device 10 to optimize the angle for each defect on the surface A of the steel plate S, corresponding to the steel type of the steel plate S, and to image the defects with an appropriate optical system configuration. Therefore, the inspection device 10 can clearly acquire an analysis image for each defect on the surface A of the steel plate S, and accurately determine whether or not there are defects on the surface A of the steel plate S.

[0075] The inspection device 10 adjusts its angle according to the type of defect on the surface A of the steel plate S. This allows the inspection device 10 to optimize the angle for each type of defect on the surface A of the steel plate S and image the defect with an appropriate optical system configuration. Therefore, the inspection device 10 can clearly acquire analytical images for each type of defect on the surface A of the steel plate S and accurately determine whether or not there is a defect on the surface A of the steel plate S.

[0076] The inspection device 10 performs texture analysis as an image processing step. For example, in automating the inspection of roll-type irregularities, the inspection device 10 uses texture analysis for image processing of captured images. This allows the inspection device 10 to detect defects that were difficult to detect using conventional methods, such as defects where the brightness difference between the base portion of the steel plate S (i.e., the normal portion) and the defective portion is small. By using texture analysis as a defect detection method, the inspection device 10 can accurately detect roll-type irregularities.

[0077] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples. The numerical values ​​described in the examples are merely examples and do not limit the scope of the present disclosure. The scope of the present disclosure should be determined based on the claims. [Examples]

[0078] Figure 6 is a first schematic diagram illustrating an example of the operation of the inspection apparatus 10 according to an embodiment of this disclosure. Referring to Figure 6, a texture analysis by frequency analysis using a Gabor filter will be described as an embodiment.

[0079] The image analysis unit 132 of the inspection device 10 performs convolutional calculations on the defective image IM to be inspected by applying filters of various wavelengths and orientations. For example, the wavelengths include four types: 1 mm, 2 mm, 4 mm, and 8 mm. For example, the orientations include four types: 0°, 45°, 90°, and 135°. As a result, the image analysis unit 132 calculates feature images by extracting the frequency components of the defective image IM. For example, the image analysis unit 132 calculates feature images F1, F2, F3, F4, F5, F6, F7, F8, F9, F 10 F 11 F 12 F 13 F 14 F 15 , and F 16 Calculate 16 feature images that include [the specified element].

[0080] The feature image can be considered as a multidimensional feature vector corresponding to the number of patterns for each wavelength and direction of the filter. The image analysis unit 132 statistically analyzes the distribution of the feature vectors in multidimensional space to calculate the anomaly score for each pixel of the original defective image IM containing the defect, and generates an anomaly score image. The anomaly score is expressed by the distance from the normalized distribution mean in multidimensional space, i.e., the Mahalanobis distance. The image analysis unit 132 detects the portion of the anomaly score image where the anomaly score is greater than an arbitrarily defined threshold as a defect.

[0081] Figure 7A is a second schematic diagram illustrating an example of the operation of the inspection apparatus 10 according to an embodiment of the present disclosure. Figure 7B is a third schematic diagram illustrating an example of the operation of the inspection apparatus 10 according to an embodiment of the present disclosure. In both Figure 7A and Figure 7B, the horizontal direction of the image corresponds to the longitudinal direction D1 of the steel plate S. The vertical direction of the image corresponds to the width direction D2 of the steel plate S.

[0082] Figures 7A and 7B show an example of how an image of the surface A of a steel plate S having minor surface irregularities with a low degree of severity is processed by the texture analysis shown in this disclosure. Figure 7A is an image of the surface A of the steel plate S including the surface irregularities Df, and shows the image as it was captured by the imaging device 122 before texture analysis was performed. Figure 7B shows the abnormality level image when texture analysis is performed on the image shown in Figure 7A by the image analysis unit 132. In both images, the surface irregularities Df are located in the area enclosed by a solid line on the left side of the image.

[0083] At the bottom of each of Figures 7A and 7B, a graph is shown in which the brightness value is plotted pixel by pixel along the dashed line in the longitudinal direction D1, in the central part of the image in the width direction D2. In the image shown in Figure 7A, the uneven defect Df of the steel plate S is blended in with the surrounding pattern, which is the base material of the steel plate S. The signal-to-noise ratio (S / N ratio), which is the ratio of the uneven defect Df to the surrounding noise, is 0.8, making detection difficult. On the other hand, in the image shown in Figure 7B, the uneven defect Df of the steel plate S has been extracted as an abnormal feature compared to the surrounding pattern, which is the base material of the steel plate S. The S / N ratio, which is the ratio of the uneven defect Df to the surrounding noise, is 12.0, which is an improvement. The image analysis unit 132 detects the portion of the abnormality image shown in Figure 7B where the S / N ratio is greater than an arbitrarily defined threshold as the uneven defect Df.

[0084] Figure 8 is a fourth schematic diagram illustrating an example of the operation of the inspection apparatus 10 according to an embodiment of the present disclosure. The images shown in Figures 7A and 7B were obtained based on the optical system arrangement shown in Figure 8. In this optical system arrangement, the light source 121 is positioned at an angle of 20°, with 0° defined as the point directly above the imaging point P on the surface A of the steel plate S. The imaging device 122 is positioned at an angle of 40° on the same side as the light source 121. In other words, this optical system arrangement corresponds to back-diffusion conditions.

[0085] While this disclosure has been described based on the drawings, embodiments, and examples, it should be noted that those skilled in the art can make various modifications and alterations based on this disclosure. Therefore, it should be noted that these modifications and alterations are within the scope of this disclosure. For example, the functions included in each configuration or step can be rearranged in a logically consistent manner, and multiple configurations or steps can be combined into one or divided.

[0086] For example, the shape, size, pattern, arrangement, orientation, type, and number of each component described above are not limited to those shown in the above description and drawings. The shape, size, pattern, arrangement, orientation, type, and number of each component may be configured arbitrarily as long as they can achieve their function. Each component of the illustrated inspection device 10 is a functional concept. The specific form of each component is not limited to those shown.

[0087] For example, it is also possible to configure a general-purpose electronic device such as a server, smartphone, or computer to function as the inspection device 10 according to the above embodiment. Specifically, a program describing the processing content that realizes each function of the inspection device 10 according to the embodiment is stored in the memory of the electronic device, and the processor of the electronic device reads and executes the program. Therefore, this disclosure can also be implemented as a program that can be executed by a processor.

[0088] Alternatively, the disclosure may also be implemented as a non-temporary computer-readable medium storing a program executable by one or more processors for causing an inspection device 10 or the like to perform each function according to one embodiment. These are also to be understood as being included within the scope of the disclosure.

[0089] In the above embodiment, the inspection device 10 was described as adjusting the distance and angle of the light source 121 and the distance and angle of the imaging device 122 along concentric circles centered on the imaging point P on the surface A of the steel plate S, but it is not limited to this. The inspection device 10 may adjust the distance and angle of the light source 121 and the distance and angle of the imaging device 122 based on any other arrangement relationship that does not follow concentric circles centered on the imaging point P on the surface A of the steel plate S.

[0090] In the above embodiment, the inspection device 10 was described as adjusting the distance between the light source 121 and the imaging device 122 and the surface A of the steel plate S according to the thickness of the steel plate S, but it is not limited to this. The inspection device 10 may adjust the distance based on any other parameter related to the steel plate S, instead of or in addition to the thickness of the steel plate S.

[0091] In the above embodiment, the inspection device 10 was described as adjusting the angle of the light source 121 and the imaging device 122 with respect to the surface A of the steel plate S according to the steel grade of the steel plate S, but it is not limited to this. The inspection device 10 may adjust the angle based on any other parameter related to the steel plate S, in addition to or instead of the steel grade of the steel plate S.

[0092] In the above embodiment, the inspection device 10 was described as adjusting the angle of the light source 121 and the imaging device 122 relative to the surface A of the steel plate S according to the type of defect on the surface A of the steel plate S, but it is not limited to this. The inspection device 10 may adjust the angle based on any other parameter related to the steel plate S, instead of, or in addition to, the type of defect on the surface A of the steel plate S.

[0093] In the above embodiment, the inspection device 10 was described as performing texture analysis as image processing, but it is not limited to this. The inspection device 10 may perform image processing in any other way, either in lieu of or in addition to texture analysis.

[0094] In the above embodiment, it was described that the inspection apparatus 10 causes the imaging apparatus 122 to image the entirety of each of the five sections of sections R1, R2, R3, R4, and R5, and acquires five images. However, the present invention is not limited to this. The inspection apparatus 10 may further subdivide one section to acquire a plurality of images for one section, and acquire an overall image of the one section by synthesizing the plurality of acquired images. Alternatively, the inspection apparatus 10 may acquire an overall image of the inspection range R by synthesizing five images respectively corresponding to the five sections of sections R1, R2, R3, R4, and R5.

Explanation of Signs

[0095] 1 Inspection system 10 Inspection apparatus 11 First robot 111 Grinding wheel 112 First arm 12 Second robot 121 Light source 122 Imaging apparatus 123 Second arm 13 Computer 131 Control unit 132 Image analysis unit [[ID=3憨31 Memory unit 20 Line control device A Surface C1 First arc C2 Second arc D1 Longitudinal direction D2 Width direction Df Concavo-convex defect portion F1, F2, F3, F4, F5, F6, F7, F8, F9, F 10 、F 11 、F 12 、F 13 、F 14 、F 15 、and F 16 Characteristic image IM Defect image L Length L0 Section width L1 First radius L2 Second radius P Imaging location R Inspection range Intervals R1, R2, R3, R4, R5 S steel plate T-shaped movement line W plate width

Claims

1. An inspection device for inspecting the surface of a steel plate, A first robot having a first arm to which a grinding wheel is attached, which automatically grinds an inspection area on the surface of the stopped steel plate corresponding to the plate width, A second robot having a second arm to which a light source and an imaging device are attached, and which automatically images the inspection area, A control unit that controls the operation of the first robot and the second robot, An image analysis unit performs image processing on the image captured by the imaging device and determines whether or not there are defects on the surface of the steel plate. Equipped with, The control unit adjusts the distance and angle to the surface of the steel plate for each of the light source and the imaging device. Inspection device.

2. An inspection apparatus according to claim 1, The control unit adjusts the distance and angle of the light source and the distance and angle of the imaging device along concentric circles centered on the imaging point on the surface of the steel plate. Inspection device.

3. An inspection apparatus according to claim 1 or 2, The control unit adjusts the distance according to the thickness of the steel plate. Inspection device.

4. An inspection apparatus according to claim 1 or 2, The control unit adjusts the angle according to the type of steel plate. Inspection device.

5. An inspection apparatus according to claim 1 or 2, The control unit adjusts the angle according to the type of defect on the surface of the steel plate. Inspection device.

6. An inspection apparatus according to claim 1 or 2, The image analysis unit performs texture analysis as the image processing. Inspection device.

7. An inspection method for inspecting the surface of a steel plate, The inspection area on the surface of the stopped steel plate, corresponding to the plate width, is automatically ground using a first robot having a first arm to which a grinding wheel is attached. The inspection area is automatically imaged by a second robot having a second arm to which a light source and an imaging device are attached. Controlling the movements of the first robot and the second robot, Image processing is performed on the image captured by the aforementioned imaging device to determine whether or not there are defects on the surface of the steel plate. Includes, Automatically imaging the inspection area includes adjusting the distance and angle to the surface of the steel plate for each of the light source and the imaging device. Testing method.

8. A method for manufacturing a steel plate, comprising inspecting the steel plate using the inspection method described in claim 7.

Images