Method for measuring the external dimensions of a metal material and method for calibrating a device for measuring the external dimensions of a metal material.

Abstract

To provide a device for measuring the shape of a metallic material which can measure the accurate shape of a metallic material.SOLUTION: The device for measuring the shape of a metallic material of present invention includes: a plurality of two-dimensional imaging devices set above the entrance side of a roughing mill; and image processing means for determining the outer size of a metallic material 15 as a measurement material on the basis of imaging data output from the two-dimensional imaging devices 2. The two-dimensional imaging devices 2 are overlapped at the peripheral parts of imaging ranges 2A to 2D, and a corner part 15a of the metallic material 15 is located in the center region of the imaging ranges 2A to 2D of at least a part of the two-dimensional imaging devices 2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to Method for measuring the external dimensions of a metal material and method for calibrating a device for measuring the external dimensions of a metal material. .

Background Art

[0002] For thick steel plates (hereinafter referred to as thick plates), the width dimension is adjusted by performing width-expanding rolling on the heated steel material by a roughing mill and an edging mill, and then the plate thickness is adjusted by performing finishing rolling by a finishing mill. Thereafter, the thick plate product is obtained by air cooling. In some cases, controlled cooling is performed after the finishing rolling and then air cooling is carried out. In the width-expanding rolling, the steel material extracted from the heating furnace is rotated 90° in front of the roughing mill, and reverse rolling is performed a plurality of times with the width direction of the steel material as the rolling direction. Before the completion of the width-expanding rolling, the plate width of the steel material being rolled is measured, and an operation is performed to check whether the plate width has reached the target value.

[0003] Conventional shape measurement of steel materials has been performed by photographing the steel material before the completion of rolling using an imaging camera and measuring the plate width from the photographed image. That is, in the conventional shape measurement of steel materials, two one-dimensional cameras having a linear field of view are installed directly above the steel material rotating mechanism in front of the roughing mill, and further, reflecting mirrors are installed between each one-dimensional camera and the steel material rotating mechanism. Then, while driving the reflecting mirror to scan the field of view of one one-dimensional camera in the width direction of the steel material, the steel material on the steel material rotating mechanism is photographed, and also, while using another reflecting mirror to scan the field of view of the other one-dimensional camera in the longitudinal direction of the steel material, the steel material on the steel material rotating mechanism is photographed. Then, based on the obtained image data, the dimensions in the width direction and the longitudinal direction of the steel material are measured.

[0004] In the conventional plate width measurement using a one-dimensional camera, a reflecting mirror for scanning the field of view of the camera is installed between the one-dimensional camera and the steel material, but this reflecting mirror becomes a factor of error in shape measurement, and there has been a problem that accurate shape measurement cannot be performed.

[0005] Therefore, in recent years, a planar shape measuring device has been developed that uses a two-dimensional camera with a planar field of view instead of a one-dimensional camera with a linear field of view, directly photographs the planar shape of steel material with the two-dimensional camera, and performs shape measurement based on the obtained image data (Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-194489 [Overview of the project] [Problems that the invention aims to solve]

[0007] Here, a lens is attached to the 2D camera for taking pictures, but lenses generally produce a distortion called aberration. Distortion has the characteristic of being small at the center of the lens and increasing as you approach the periphery of the lens. Distortion aberration also occurs in the two-dimensional camera equipped in the planar shape measuring device described in Patent Document 1. In Patent Document 1, since the entire planar shape of the steel material being rolled is captured by a single two-dimensional camera, the light reflected from the edge of the steel material passes through the peripheral part of the lens and reaches the image sensor of the camera. As a result, the image of the edge of the steel material may be distorted due to the effects of distortion aberration. Since the image of the edge of the steel material serves as the reference position when measuring the dimensions of the steel material, if the image of this edge is distorted, it becomes difficult to accurately measure the dimensions of the steel material. These problems are not limited to steel; they also apply to other metal materials manufactured through the rolling process. Furthermore, there is a demand for accurate measurement of plate length, not just width.

[0008] This invention has been made in view of the above circumstances, and is capable of accurately measuring the shape of a metal material. Method for measuring the external dimensions of a metal material and method for calibrating a device for measuring the external dimensions of a metal material. The objective is to provide this. [Means for solving the problem]

[0009] To solve the above problems, the present invention employs the following means. [A] Multiple two-dimensional imaging devices installed above the metal material to be measured, The system includes an image processing means that determines the external dimensions of a metal material to be measured based on the imaging data output from the two-dimensional imaging device, The plurality of two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of any of the imaging ranges of the two-dimensional imaging devices. A device for measuring the external dimensions of metal materials. [B] The image processing means identifies the position of the long side or short side of the metal material in the imaging range from the imaging data of the metal material to be measured, which has been captured by the plurality of two-dimensional imaging devices, and determines the distance between the long sides or short sides of the metal material, as described in [A]. [C] The metal material external dimension measuring device according to [A] or [B], characterized in that the plurality of two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward. [D] A metal material external dimension measuring device according to any one of [A] to [C], wherein the plurality of two-dimensional imaging devices are mounted on a single support. [E] The external dimension measuring device for a metal material according to any one of [A] to [D], wherein the central region of the imaging range is a region with a distortion amount of 3% or less. [F] The external dimensions measuring device for a metal material according to any one of [A] to [E], wherein the central region of the imaging range is an area of ​​50% or more of the total area of ​​the imaging range. [G] The external dimension measuring device for metal materials according to any one of [A] to [F], wherein the two-dimensional imaging device is an infrared camera. [H] A metal material external dimension measuring device according to any one of [A] to [G], wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device. [1] A method for measuring the external dimensions of a metal material to be measured using a two-dimensional imaging device installed above the metal material to be measured, Multiple two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of one of the imaging ranges of the two-dimensional imaging devices. A calibration jig having multiple point light sources arranged at predetermined intervals from each other is placed in the two-dimensional imaging device. imaging range Calibration step: Arrange the calibration jig such that a portion of the point light source is located at its periphery, capture images of the point light source of the calibration jig using the plurality of two-dimensional imaging devices, determine the difference between the distance between two points of the point light source in the imaging data of the point light source and the distance between two points of the point light source in the calibration jig as an error, determine whether the error is less than or equal to a preset threshold, and adjust the orientation of the two-dimensional imaging device if the error exceeds the threshold. The imaging step involves imaging the metal material to be measured using the plurality of two-dimensional imaging devices to obtain imaging data of the metal material, A method for measuring the external dimensions of a metal material, comprising: a measurement step of determining the distance between the long sides or short sides of a metal material from the position of the long side or short side of the metal material in imaging data of the metal material. [2] The method for measuring the external dimensions of a metal material according to [1], wherein the frequency of the calibration step is less than the frequency of the imaging step and the measurement step. [3] A method for measuring the external dimensions of a metal material according to either [1] or [2], characterized in that the plurality of two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward. [4] A method for measuring the external dimensions of a metal material according to any one of [1] to [3], characterized in that a verification step is performed to verify the dimensional measurements obtained by the plurality of two-dimensional imaging devices before the imaging step. [5] The central region of the imaging range is The aforementioned Target of measurement metal material A method for measuring the external dimensions of a metal material as described in any one of [1] to [4], wherein the amount of distortion in the image when the material is captured is in the region of 3% or less. [6] The method for measuring the external dimensions of a metal material according to any one of [1] to [6], wherein the central region of the imaging range is an area of ​​50% or more of the total area of ​​the imaging range. [7] The method for measuring the external dimensions of a metal material according to any one of [1] to [6], wherein the two-dimensional imaging device is an infrared camera. [8] A method for measuring the external dimensions of a metal material according to any one of [1] to [7], wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device and imaging is performed. [9] Multiple two-dimensional imaging devices installed above the metal material to be measured, The system includes an image processing means that determines the external dimensions of a metal material to be measured based on the imaging data output from the two-dimensional imaging device, A calibration method for measuring the external dimensions of a metal material, wherein the plurality of two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of any of the imaging ranges of the two-dimensional imaging devices, A first step is to position a calibration jig having a plurality of point light sources arranged at predetermined intervals from each other, such that a portion of the point light sources are located at the periphery of the imaging range of the two-dimensional imaging device, A second step involves imaging the point light source of the calibration jig using the plurality of two-dimensional imaging devices, Image acquired in the first step 2 In the imaging data of the point light source A third step involves determining the difference between the distance between two points of the point light source and the distance between two points of the point light source in the calibration jig as an error, determining whether the error is below a predetermined threshold, and adjusting the orientation of the two-dimensional imaging device if the error exceeds the threshold. A calibration method for a metal material external dimension measuring device comprising the above.

[10] A calibration method for measuring the external dimensions of a metal material according to [9], wherein the point light source is an LED light source.

[11] The image processing means identifies the position of the long side or short side of the metal material in the imaging range from the imaging data of the metal material to be measured captured by the plurality of two-dimensional imaging devices, and determines the distance between the long sides or short sides of the metal material, the calibration method for the external dimensions measuring device of a metal material as described in [9].

[12] The calibration method for measuring the external dimensions of a metal material according to [9] or

[11] , characterized in that the plurality of two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward.

[13] A calibration method for measuring the external dimensions of a metal material according to any one of [9] to

[12] , wherein the plurality of two-dimensional imaging devices are mounted on a single support.

[14] The central region of the imaging range is The aforementioned Target of measurement metal material A calibration method for measuring the external dimensions of a metal material as described in any one of [9] to

[13] , wherein the amount of distortion in the image when capturing the material is in the region of 3% or less.

[15] The calibration method for measuring the external dimensions of a metal material according to any one of [9] to

[14] , wherein the central region of the imaging range is an area of ​​50% or more of the total area of ​​the imaging range.

[16] A calibration method for measuring the external dimensions of a metal material according to any one of [9] to

[15] , wherein the two-dimensional imaging device is an infrared camera.

[17] A calibration method for measuring the external dimensions of a metal material according to any one of [9] to

[16] , wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device. [Effects of the Invention]

[0010] Metal material of the present invention External dimensions measuring deviceAccording to this method, by arranging multiple two-dimensional imaging devices so that the periphery of each imaging range overlaps with one another, and so that all corners of the metal material to be measured are located within the central region of one of the imaging ranges of the two-dimensional imaging devices, the corners of the metal material can be imaged by each two-dimensional imaging device, and the corners can be imaged in the region where the distortion aberration of each two-dimensional imaging device is small. As a result, the contours near the corners of the metal material can be imaged without distortion, and the external dimensions of the metal material can be accurately measured. Furthermore, according to the metal material external dimension measuring device of the present invention, by arranging multiple two-dimensional imaging devices within the projection area when the metal material to be measured is projected upward, the side end surfaces between the top and bottom surfaces of the metal material are not captured in the imaging range of the two-dimensional imaging devices. As a result, the position of the long or short side of the top surface of the metal material can be accurately determined, and the dimensions of the metal material in the width direction or length direction can be measured more accurately. Furthermore, according to the metal material external dimension measuring device of the present invention, by mounting multiple two-dimensional imaging devices on a single support, the relative positions of the two-dimensional imaging devices can be fixed, and the external dimensions of the metal material can be measured more accurately. Furthermore, by using an infrared camera as the two-dimensional imaging device, it is possible to receive infrared light emitted from the heated metal material, allowing for more accurate measurement of the shape of the heated metal material. Furthermore, by attaching a filter that transmits near-infrared light to the two-dimensional imaging device, infrared light emitted from the heated metal material can be transmitted through the filter and received by the two-dimensional imaging device, allowing for more accurate measurement of the shape of the heated metal material.

[0011] Next, the metal material of the present invention External dimensionsAccording to the measurement method, multiple two-dimensional imaging devices are arranged so that the periphery of their respective imaging ranges overlap, and all corners of the metal material to be measured are located within the central region of one of the imaging ranges of the two-dimensional imaging devices. By imaging the metal material in this manner, the corners of the metal material can be imaged by the two-dimensional imaging devices, and the corners can be imaged in the region where the distortion aberration of each two-dimensional imaging device is small. As a result, the contours near the corners of the metal material can be imaged without distortion, enabling accurate measurement of the external dimensions of the metal material. Furthermore, by calibrating the orientation of each of the multiple two-dimensional imaging devices using a calibration jig with a point light source, the measurement error of the external dimensions of metal materials can be significantly reduced. In addition, by positioning the calibration jig so that a part of the point light source is located at the periphery of the imaging range of the two-dimensional imaging device, the relative positions of adjacent imaging ranges can be accurately calibrated. Furthermore, by determining the distance between the long sides or short sides of the metal material from the position of the long or short sides of the metal material in the imaging data of the metal material, the distance between the long sides or short sides of the metal material, i.e., the width or length of the metal material, can be accurately measured. Furthermore, since the calibration step is performed less frequently than the imaging and measurement steps, and there is no need to perform a calibration step for each metal material shape measurement, the efficiency of metal material shape measurement can be improved. Furthermore, the metal material of the present invention External dimensions According to the measurement method, by arranging multiple two-dimensional imaging devices within the projection area when the metal material to be measured is projected upwards, the side edges between the top and bottom surfaces of the metal material are prevented from being captured within the imaging range of the two-dimensional imaging devices. This allows for the precise identification of the position of the long or short side of the top surface of the metal material, and enables more accurate measurement of the dimensions of the metal material in the width or length direction. Furthermore, by using an infrared camera as the two-dimensional imaging device, it is possible to receive infrared light emitted from the heated metal material, allowing for more accurate measurement of the shape of the heated metal material. Furthermore, by attaching a filter that transmits near-infrared light to the two-dimensional imaging device, infrared light emitted from the heated metal material can be transmitted through the filter and received by the two-dimensional imaging device, allowing for more accurate measurement of the shape of the heated metal material.

[0012] Next, the metal material of the present invention External dimensions According to the calibration method for the measuring device, the orientation of each of the multiple two-dimensional imaging devices is calibrated using a calibration jig with a point light source, thereby significantly reducing the measurement error of the external dimensions of metal materials. Furthermore, by positioning the calibration jig so that a portion of the point light source is located at the periphery of the imaging range of the two-dimensional imaging device, the relative positions of adjacent imaging ranges can be accurately calibrated. Furthermore, the metal material of the present invention External dimensions According to the calibration method for the measuring device, by using an LED light source as the point light source, the spread of the point light source that serves as the calibration reference can be reduced, allowing for more precise alignment of the orientation of each two-dimensional imaging device. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram showing a part of a manufacturing line for thick plates equipped with the metal material external dimension measuring device of the present invention, where (a) is a side view and (b) is a top view. [Figure 2] Figure 2 is a perspective view showing the main parts of the metal material external dimension measuring device of the present invention. [Figure 3] Figure 3 is a schematic plan view showing the positional relationship between the steel material to be measured, the four two-dimensional imaging devices, and the imaging ranges of the four two-dimensional imaging devices. [Figure 4] Figure 4 is a schematic diagram illustrating the distortion aberration in the imaging range of the two-dimensional imaging device according to the present invention. [Figure 5] Figure 5 is a schematic plan view of the calibration jig according to this embodiment. [Figure 6] Figure 6 is a schematic plan view illustrating the point light source and the distance between the point light sources of the calibration jig shown in Figure 5. [Figure 7]Figure 7 is a schematic plan view illustrating the first step of the calibration method, showing the positional relationship between the imaging range of the two-dimensional imaging device and the calibration jig. [Figure 8] Figure 8 is a schematic plan view illustrating the second step of the calibration method, showing the position of the calibration jig in the image captured by the two-dimensional imaging device. [Figure 9] Figure 9 is a flowchart showing the flow of the external dimension measurement method and calibration method for metal materials when performing the verification step. [Figure 10] Figure 10 is a schematic plan view of the inspection jig according to this embodiment. [Figure 11] Figure 11 is a schematic plan view showing an example of imaging of a calibration jig using four two-dimensional imaging devices. [Figure 12] Figure 12 is a schematic plan view showing the positional relationship between the steel material to be measured, the two two-dimensional imaging devices, and the imaging ranges of the two two-dimensional imaging devices. [Figure 13] Figure 13 is a schematic plan view showing the positional relationship between the steel material to be measured, the six two-dimensional imaging devices, and the imaging ranges of the six two-dimensional imaging devices. [Modes for carrying out the invention]

[0014] The following describes the metal material which is an embodiment of the present invention. External dimensions Measuring device (Hereafter referred to as the metal material shape measuring device) metal materials External dimensions Measurement method (Hereafter referred to as the method for measuring the shape of metal materials) and metal materials External dimensions Calibration method for measuring devices (Hereinafter referred to as the calibration method for metal material shape measuring devices) This will be explained using a thick plate slab (hereinafter referred to as "steel material") as an example of a metal material, with reference to the drawings.

[0015] (Metal material shape measuring device) An embodiment of the present invention, the metal material shape measuring device 1, is installed, for example, in a thick steel plate manufacturing line 10 shown in Figures 1(a) and 1(b). The arrow H in Figure 1(a) indicates the direction of transport of the thick plate. The thick plate manufacturing line 10 shown in Figures 1(a) and 1(b) is equipped with a roughing mill 11, a finishing mill 12 installed downstream of the roughing mill 11 in the transport direction of the thick plate, and a control cooling system 13 installed downstream of the finishing mill 12 in the transport direction of the thick plate. The roughing mill 11 is equipped with a horizontal roll 11a and a vertical roll 11b, and is capable of widthening the steel material 15 (slab). In addition, a steel material rotation mechanism 14 is provided on the entry side of the roughing mill 11, which can change the orientation of the steel material 15 (metal material) with respect to the transport direction. The metal material shape measuring device 1 of this embodiment consists of four two-dimensional imaging devices 2 installed above the steel material rotation mechanism 14 on the entry side of the roughing mill 11, and an image processing means 3 that determines the external dimensions of the steel material 15 to be measured based on the imaging data output from the two-dimensional imaging devices 2.

[0016] As shown in Figure 1(a), the two-dimensional imaging device 2 is installed, for example, above the metal material rotation mechanism 14 on the entry side of the roughing mill 11. The distance between the steel material 15 being transported on the metal material rotation mechanism 14 and the two-dimensional imaging device 2 is set to 10m or more, for example, about 15m. Four two-dimensional imaging devices 2 are mounted on a single support 4. For example, as shown in Figure 2, four two-dimensional imaging devices 2 are fixed on a flat support 4. The two-dimensional imaging device 2 is equipped with a lens (not shown), and the lens of the two-dimensional imaging device 2 is positioned in an opening 4a provided in the flat support 4. This allows the two-dimensional imaging device 2 to image the steel material 15 on the metal material rotation mechanism 14 on the entry side of the roughing mill 11 from above.

[0017] The two-dimensional imaging device 2 is an imaging device having a planar field of view. The two-dimensional imaging device 2 includes an image sensor that converts an image, which is an optical signal, into an electrical signal. The image sensor can be, for example, a CCD sensor, a CMOS sensor, etc. The electrical signal converted by the image sensor is sent to the image processing means 3 as image data. The two-dimensional imaging device 2 further includes an optical lens (not shown). The optical lens collects light reflected by the subject or emitted by the subject itself and forms an image in the light-receiving area of ​​the image sensor. There may be multiple two-dimensional imaging devices 4. For example, there may be two, four, six, or any other number.

[0018] Figure 2 shows a perspective view of four two-dimensional imaging devices 2 and the steel material 15 to be measured. In Figure 2, the imaging range of each two-dimensional imaging device 2 is indicated by a dotted line. The four two-dimensional imaging devices 2 are used to image the entire steel material 15.

[0019] Figure 3 shows a schematic plan view illustrating the relationship between the steel material 15 to be measured, the four two-dimensional imaging devices 2, and the imaging ranges 2A to 2D of each two-dimensional imaging device 2. As shown in Figure 3, the four two-dimensional imaging devices 2 are positioned within the projection area when the steel material 15 to be measured on the metal material rotation mechanism 14 is projected upward. In Figure 3, the outline of the rectangular steel material 15 in plan view indicates the projection area. By automatically adjusting the imaging timing of the four two-dimensional imaging devices 2 using the steel material speed or the center of gravity of the steel material as a parameter, and positioning the four two-dimensional imaging devices 2 within the projection area when the steel material 15 to be measured on the metal material rotation mechanism 14 is projected upward, only the top surface of the steel material 15 is included in the imaging range of the two-dimensional imaging devices 2, and the side end surfaces between the top and back surfaces of the steel material 15 are not included in the imaging range.

[0020] Furthermore, the four two-dimensional imaging devices 2 are arranged such that the peripheral edges 2E of their respective imaging ranges 2A to 2D overlap with each other, and all of the corners 15a of the steel material 15 are located within the central region 2F of any of the imaging ranges 2A to 2D of the two-dimensional imaging devices 2. In other words, the four corners 15a of the steel material 15 to be measured are located within the central region 2F of each imaging range 2A to 2D. By arranging the four two-dimensional imaging devices 2 so that the peripheral edges 2E of their imaging ranges 2A to 2D overlap with each other, the four two-dimensional imaging devices 2 can be calibrated, as will be described later.

[0021] Figure 4 shows the distortion characteristics of the two-dimensional imaging device 4 in the imaging range 2A to 2E. Distortion is an optical characteristic of the optical lens provided in the two-dimensional imaging device 2, where distortion is small at the center of the optical lens and increases as you approach the periphery of the lens. The metal material shape measuring device 1 of this embodiment measures the plate width or plate length of the steel material 15 by identifying the position of the long or short side of the steel material 15 based on the captured image data. Therefore, in order to accurately determine the position of the long or short side, it is necessary to minimize the influence of distortion. In this embodiment, four two-dimensional imaging devices 2 are arranged such that the four corners 15a of the steel material 15 to be measured are located in the central region 2F of the imaging range 2A to 2D where distortion is small. The range in which the influence of the measurement accuracy of the plate width or plate length of the steel material 15 is small differs for each optical lens, but it is sufficient to position the corners 15a of the steel material 15 in the central region 2F of the imaging range 2A to 2F.

[0022] The central region of the imaging ranges 2A to 2E refers to the area that occupies the central portion in a plan view of each imaging range 2A to 2E, and is the region where the amount of distortion in the image when imaging steel materials is 3% or less, more preferably 1% or less. Therefore, the central region is, depending on the performance of the lens of the two-dimensional imaging device 4, for example, an area of ​​50% or more, 60% or more, or 80% or more of the area of ​​each imaging range 2A to 2E.

[0023] Furthermore, if only one two-dimensional imaging device 4 is used instead of multiple devices, the position of the corner 15a of the steel material 15 in the imaging range will be outside the central region 2F and will be located in the peripheral region where distortion aberration is large. In this case, due to the influence of distortion aberration, it will be difficult to accurately determine the position of the long or short side of the steel material, making it difficult to accurately measure the plate width or plate length.

[0024] Furthermore, the two-dimensional imaging device 4 may be a conventional optical camera or an infrared camera. As an infrared camera, for example, a camera that exhibits 10% or more sensitivity to a general optical camera in the near-infrared region with a wavelength of 750 nm or more is preferable. If the steel material 15 to be measured is, for example, steel that has been heated in a heating furnace for hot rolling, near-infrared light is emitted from the steel material. In this case, by using an infrared camera as the two-dimensional imaging device 4, the infrared light emitted from the heated steel material can be received, and the shape of the heated steel material can be accurately measured.

[0025] Furthermore, the two-dimensional imaging device 4 may be fitted with a filter that transmits near-infrared light. Such a filter should have a relatively high transmittance for light with a wavelength of 720 nm or longer, and a relatively low transmittance for light with a wavelength of less than 720 nm. By fitting the filter, the infrared light emitted from the heated steel material can be transmitted through the filter and received by the two-dimensional imaging device, enabling accurate measurement of the shape of the heated steel material.

[0026] The image processing means 3 identifies the positions of a pair of long sides or a pair of short sides of the steel material 15 within the imaging range 2A to 2D using coordinates, based on the imaging data of the steel material 15 to be measured, captured by the four two-dimensional imaging devices 2. It then determines the distance between the pair of long sides or the pair of short sides and uses this as the plate width or plate length of the steel material. The operation of the image processing means 3 will be described later. The image processing means 3 is implemented as a function of the central processing unit of a computer.

[0027] (Method for measuring the shape of metal materials and calibration method for metal material shape measuring devices) Next, a method for measuring the shape of a metal material and a method for calibrating the metal material shape measuring apparatus using the metal material shape measuring apparatus 1 shown in FIGS. 1 to 2 will be described.

[0028] First, the calibration jig 31 used in the shape measurement method and the calibration method will be described. As shown in FIG. 5, the calibration jig 31 has a plurality of point light sources 32 arranged at a predetermined interval from each other, and is composed of a grid-shaped frame 33 and point light sources 32 provided at positions corresponding to the grid points of the frame 33. The grid-shaped frame 33 is composed of a plurality of rod-shaped frame members 34 combined in a grid pattern vertically and horizontally. At positions corresponding to the grid points where the frame members 34 intersect, light emitting diode light sources (LED light sources) are installed as the point light sources 32. In the example shown in FIG. 5, one point light source 32 is installed at each grid point, but the present embodiment is not limited to this, and a plurality of point light sources 32 may be installed at each grid point. Further, the point light source 32 may be installed at an intermediate position between the grid points of the frame members 34 instead of at the grid points. The calibration jig 31 having the grid-shaped frame 33 is lightweight and advantageous for handling. Although FIG. 5 illustrates a calibration jig provided with point light sources 32 on a grid-shaped frame 33, the present invention is not limited to this, and a calibration jig in which point light sources are arranged on a plate-like substrate may also be used.

[0029] Measure in advance the distance between two point light sources 32 of the calibration jig 31. Since the calibration jig shown in FIG. 5 arranges 25 point light sources 32 at equal intervals in a grid pattern, there are a total of 300 combinations of the distances between any two point light sources 32. In FIG. 6, the distance between two point light sources 32 is indicated by a one-dot chain line. In FIG. 6, each point light source 32 is respectively, a 21 , 55 , 11 , 22 , 54 , 11 , 21 , 11 , 55 , 11 , 31 、a 21 、a 31 、…、a 21 、a 22 、…、a 54 、a 55 When set as, a 11 [[ID=2 / 4]]、a 21 ), the distances between the point light sources are represented as L(a 11 , a <000,0011>), L(a 11 , a 55 ). For example, L(a 11,a 21 ) is a 11 and a 21 It means the distance to L(a 11 ,a 55 ) is a 11 and a 55 This represents the distance to [the specified location]. In Figure 6, there are a total of 300 such combinations.

[0030] Next, we will explain the first to third steps of the calibration method in order. Note that the first to third steps of the calibration method correspond to the calibration steps of the shape measurement method. In the first step, as shown in Figure 7, the calibration jig 31 is placed on the metal material rotation mechanism. The calibration jig 31 is positioned so that a portion of the point light source 32 is located at the overlapping peripheral area 2E of the imaging ranges 2A to 2D of the two-dimensional imaging device 2. By positioning a portion of the point light source 32 at the overlapping peripheral area 2E, the relative positions of the imaging ranges 2A to 2D of the four two-dimensional imaging devices 2 can be calibrated.

[0031] Next, in the second step, as shown in Figure 7, with the calibration jig 31 placed on the metal material rotation mechanism, the point light source 32 of the calibration jig 31 is imaged by four two-dimensional imaging devices 2. Here, the two-dimensional imaging device 2 in this embodiment is installed on the support 4 as shown in Figure 2, and its orientation is adjustable in three axes: the horizontal direction (X-axis direction), the vertical direction (Y-axis direction), and the rotational direction around an axis that passes through the center of the imaging range 2A to 2D. The imaging of the calibration jig 31 is performed with the two-dimensional imaging device 2 adjusted to a specific orientation. The orientation parameter that defines the orientation of the two-dimensional imaging device 2 is defined as (α,β,θ), which is a set of three parameters: α (X-axis direction), β (Y-axis direction), and θ (rotational direction). In this embodiment, the orientation parameter of the two-dimensional imaging device 2 when imaging the calibration jig 31 is kept track of. Let the orientation parameter at this time be (α1,β1,θ1).

[0032] Next, in the third step, the distance of the captured point light source 32 is measured from the image of the point light source 32 of the calibration jig 31. In Figure 8, the distance of the point light source 32 in the imaging of the calibration jig 31 is shown by a dashed line. In Figure 8, the captured point light source 32 is shown as b 11 , b 21 , b 31 , ..., b 21 , b 22 , ..., b 54 , b 55 When this is the case, the distance between the point light sources is L(b 11 ,b 21 ), L(b 11 ,b 31 |, L(b 11 ,b 55 It is expressed as ). For example, L(b 11 ,b 21 ) is b 11 and b 21 This means the distance to L(b 11 ,b 55 ) is a 11 and a 55 This represents the distance between two points. In Figure 8, there are a total of 100 such combinations.

[0033] Next, the actual distance of the light source 32 of the calibration jig 31 and the distance of the light source 32 in the imaging of the calibration jig 31 are extracted as the difference in deviation. That is, for example, L(a 11 ,a 21 ) and L(b 11 ,b 21 The difference between ) and e(a 11 a 21 b 11 b 21 ) and L(a 11 ,a 55 ) and L(b 11 ,b 55 The difference between ) and e(a 11 a 55 b 11 b 55 Let's assume that... In this way, we determine the actual distance between the light sources 32 and the difference between the distance and the distance between the light sources 32 in the image. Furthermore, we calculate the sum of the obtained differences Σe1. Let the sum Σe1 be the error. For example, e(a 11 a 21 b11 b 21 ) is e(a 11 a 21 b 11 b 21 ) = L(a 11 , a 21 ) - L(b 11 , b 21 ) and e(a 11 a 55 b 11 b 55 ) is e(a 11 a 55 b 11 b 55 ) = L(a 11 , a 55 ) - L(b 11 , b 55 ) is obtained.

[0034] The error Σe1 obtained as described above is the value when the posture of the two-dimensional imaging device 2 is represented by the posture parameters (α1, β1, θ1). It is determined whether this error Σe1 is within the management range. If the error value Σe1 is within the management range, adjustment of the posture of the two-dimensional imaging device 2 is not required. On the other hand, if the total error value Σe1 is out of the management range, the posture of the two-dimensional imaging device 2 is readjusted.

[0035] Also, in this embodiment, the posture of the two-dimensional imaging device 2 may be adjusted as follows. This method is to obtain the posture parameters when minimizing the total error value Σe1 by a minimization problem. That is, the posture of the two-dimensional imaging device 2 is changed over at least two or more times, and for each posture of the two-dimensional imaging device 2, the above steps from the first step to the third step are performed, so that the error Σe i , β i , θ i ) for each is obtained. i is the number of times the posture of the two-dimensional imaging device 2 is changed and is a natural number of 2 or more. And the posture parameters (α i such that the error Σe i becomes the minimum value i , β i , θ iThe ) is determined by convergence calculation. Based on the obtained attitude parameters, the attitude of the two-dimensional imaging device 2 is adjusted to complete the calibration.

[0036] Furthermore, the attitude control parameters are not limited to (α,β,θ); they may also be (α,β), or other parameters may be used.

[0037] Furthermore, the size of the point light source 32 as viewed from the installation position of the two-dimensional imaging device 2 corresponds to the size of several pixels in the imaging data of each two-dimensional imaging device 2. Therefore, the position of the point light source 32 in the imaging data is determined by identifying the pixel corresponding to the centroid of the image of the point light source 32 in the imaging data, and the position of this pixel is taken as the position of the point light source 32 in the imaging data.

[0038] Next, we will explain how to measure the shape of a steel material using the steel material shape measuring device 1, which has been calibrated.

[0039] In the method for measuring the shape of a metal material, the following steps are sequentially performed: an imaging step in which the steel material 15 to be measured, which is transported on a metal material rotation mechanism, is imaged by four two-dimensional imaging devices 4 to obtain imaging data of the steel material 15; and a measurement step in which the distance between the long sides or short sides of the steel material is determined from the position of the long sides or short sides of the steel material in the imaging data of the steel material 15.

[0040] Figure 3 shows the steel material as imaged by the four calibrated two-dimensional imaging devices 2 during the imaging step. As shown in Figure 3, the four two-dimensional imaging devices 2 are positioned within the projection area when the steel material 15 to be measured is projected upwards. Therefore, only the top surface of the steel material 15 is imaged, and the side end surfaces between the top and bottom surfaces are not imaged. This allows the contour of the top surface of the steel material 15 to be clearly distinguishable. In addition, the steel material 15 is at a high temperature of over 800°C and is in a red-hot state, with significantly increased brightness compared to the surrounding background. Therefore, the contour of the top surface of the steel material 15 is even easier to distinguish.

[0041] Next, in the measurement step, as shown in Figure 13, the position coordinates A and B of the long sides of the steel material in the imaging range 2A to 2D are identified, and the distance W between these coordinates A and B is calculated, making it possible to measure the distance between the long sides of the steel material 15, i.e., the plate width of the steel material 15. Similarly, it becomes possible to measure the distance between the short sides of the steel material 15, i.e., the plate length of the steel material 15.

[0042] This measurement step can be performed as a function of the computer's central processing unit.

[0043] Furthermore, the frequency of the calibration step does not need to be as high as the frequency of the imaging and measurement steps. For example, once the calibration step is sufficient for several hundred consecutive imaging and measurement steps.

[0044] In the above embodiment, a slab (steel material 15) for manufacturing thick plates was used as an example of the metal material, but this embodiment may be applied not only to slabs for manufacturing thick steel plates, but also to slabs for manufacturing thin steel plates. It may also be applied to billets, blooms, etc. Furthermore, it may be applied to steel materials undergoing hot rolling. More preferably, steel materials that have been heated and are emitting infrared light are preferred. It may also be applied to other metal materials other than steel.

[0045] According to the metal material shape measuring device 1 of this embodiment, by arranging four two-dimensional imaging devices 2 such that the peripheral portions 2E of their respective imaging ranges 2A to 2D overlap each other, and that all of the corners 15a of the steel material 15 are located within the central region 2F of any of the imaging ranges 2A to 2D of the two-dimensional imaging devices 2, the four corners 15a of the steel material 15 are each imaged by the four two-dimensional imaging devices 2, and the corners 15a can be imaged in the region where the distortion aberration of each two-dimensional imaging device 2 is small. As a result, the contours near the corners 15a of the steel material 15 can be imaged without distortion, and the external dimensions of the steel material 15 can be accurately measured. Furthermore, according to the metal material shape measuring device 1 of this embodiment, by arranging four two-dimensional imaging devices 2 within the projection area when the steel material 15 to be measured on the metal material rotation mechanism 14 is projected upward, the side end surfaces between the top and bottom surfaces of the steel material 15 are not captured in the imaging range 2A to 2D of the two-dimensional imaging devices 2. As a result, the position of the long or short side of the top surface of the steel material 15 can be accurately identified, and the dimensions of the steel material 15 in the plate width direction or plate length direction can be measured more accurately. Furthermore, according to the metal material shape measuring device 1 of this embodiment, since four two-dimensional imaging devices 2 are attached to a single support 4, the relative positions of the four two-dimensional imaging devices 2 can be fixed, and the external dimensions of the steel material 15 can be measured more accurately.

[0046] Next, according to the metal material shape measurement method of this embodiment, the steel material 15 is imaged with four two-dimensional imaging devices 2 positioned so that the peripheral portions 2E of their respective imaging ranges 2A to 2D overlap each other, and all of the corners 15a of the steel material 15 are located within the central region 2F of any of the imaging ranges 2A to 2D of the two-dimensional imaging devices 2. This allows each of the four corners 15a of the steel material 15 to be imaged by the four two-dimensional imaging devices 2, and the corners 15a can be imaged in the region where the distortion aberration of each two-dimensional imaging device 2 is small. As a result, the contours near the corners 15a of the steel material 15 can be imaged without distortion, and the external dimensions of the steel material 15 can be accurately measured. Furthermore, since the orientation of each of the four two-dimensional imaging devices 2 is calibrated using a calibration jig 31 having a point light source 32, the measurement error of the external dimensions of the steel material 15 can be significantly reduced. In particular, the size of the point light source 32 as seen from the installation position of the two-dimensional imaging device 2 corresponds to the size of several pixels in the imaging data of each two-dimensional imaging device 2. During calibration, the position of the pixel corresponding to the centroid of the point light source 32 is calculated, so the position of the point light source in the imaging data can be precisely determined, thereby enabling high-precision calibration of the orientation of the two-dimensional imaging device. In addition, by positioning the calibration jig 31 so that a part of the point light source 32 is located at the periphery 2E of the imaging range 2A to 2D of the two-dimensional imaging device 2, the relative positions of adjacent imaging ranges 2A to 2D can be accurately calibrated. Furthermore, by determining the distance between the long sides or short sides of the steel material 15 from the position of the long or short sides of the steel material 15 in the imaging data, the distance between the long sides or short sides of the steel material 15, i.e., the plate width or plate length of the steel material 15, can be accurately measured. Furthermore, since the calibration step is performed less frequently than the imaging and measurement steps, and there is no need to perform a calibration step each time the shape of the steel material 15 is measured, the efficiency of shape measurement of the steel material 15 can be improved. Furthermore, according to the metal material shape measurement method of this embodiment, by arranging four two-dimensional imaging devices 2 within the projection area when the steel material 15 to be measured on the metal material rotation mechanism 14 is projected upward, the side end surfaces between the top and bottom surfaces of the steel material 15 are not captured in the imaging range 2A to 2D of the two-dimensional imaging devices 2. As a result, the position of the long or short side of the top surface of the steel material 15 can be accurately identified, and the dimensions of the steel material 15 in the width direction or length direction can be measured more accurately.

[0047] Next, according to the calibration method for the metal material shape measuring device 1 of this embodiment, the orientation of each of the four two-dimensional imaging devices 2 is calibrated using a calibration jig 31 having a point light source 32, so that the measurement error of the external dimensions of the steel material 15 can be significantly reduced. In particular, the size of the point light source 32 as seen from the installation position of the two-dimensional imaging device 2 corresponds to one pixel of the imaging range 2A to 2D of each two-dimensional imaging device 2, so the orientation of the two-dimensional imaging device 2 can be calibrated at the level of one pixel. Furthermore, by arranging the calibration jig 31 so that a part of the point light source 32 is located at the peripheral edge 2E of the imaging range 2A to 2D of the two-dimensional imaging device 2, the relative positions of adjacent imaging ranges 2A to 2D can be accurately calibrated. Furthermore, according to the calibration method for the metal material shape measuring device 1 of this embodiment, by using an LED light source for the point light source 32, the spread of the point light source 32 that serves as the calibration reference can be reduced, and the orientation of each two-dimensional imaging device 2 can be aligned more precisely.

[0048] Furthermore, the metal material shape measurement method of this embodiment may include a verification step before the imaging step in which the dimensional measurements obtained by four two-dimensional imaging devices are verified. In other words, as shown in Figure 9, in addition to the calibration step of the shape measuring device and the shape measuring step of the steel material, a verification step may be performed to verify the dimensional measurements obtained by four two-dimensional imaging devices.

[0049] In the calibration step, a calibration jig is used in addition to the calibration jig 31. As shown in Figure 10, the calibration jig 131 consists of a grid-like frame 133 with a rectangular outer shape and four point light sources 132 positioned at the corners of the frame 133. The frame 133 is constructed by combining multiple rod-shaped frame materials 134 vertically and horizontally in a grid pattern. Light-emitting diode light sources (LED light sources) are used for the point light sources 132.

[0050] Next, the verification step will be explained. In the verification step, first, in step S1 in Figure 9, the verification jig 131 is placed on the metal material rotation mechanism and the verification jig 131 is photographed by four two-dimensional imaging devices 2. Figure 11 shows an example of the verification jig 131 being photographed. Next, in step S2 in Figure 9, the distance between the four point light sources 132 of the verification jig 131 is measured during the imaging of the verification jig 131. If the distance between the point light sources 132 meets the standard, the process proceeds to step S3, where the steel material shape measurement step is performed. If the distance between the point light sources 132 does not meet the standard, the process proceeds to step S4, where the shape measuring device is calibrated using the calibration jig 31.

[0051] After the steel material shape measurement step is completed, the verification step is performed again, but it is not necessary to alternate between the steel material shape measurement step and the verification step. The frequency of the verification step can be set arbitrarily; for example, the four-point verification step can be performed once every few months, and the steel material shape measurement step can be repeated many times in between.

[0052] The calibration step of the shape measuring device using the calibration jig 31 (step S4) is performed by sequentially carrying out steps 1 to 3, as described above. If, as a result of readjusting the orientation of the two-dimensional imaging device 2 in step S5, the total error value Σe1 falls within the control range, the process returns to the four-point verification step in step S1. On the other hand, if, even after readjusting the orientation of the two-dimensional imaging device 2 in step S5, the total error value Σe1 falls outside the control range, it is assumed that there is another failure factor other than the orientation of the two-dimensional imaging device 2, and the process proceeds to step S6 to analyze and improve the other failure factor. After the completion of step S6, the process returns to step S4 again and the calibration step of the shape measuring device is performed again.

[0053] As described above, by performing a verification using the verification jig 131, it is possible to confirm whether the dimensions of the steel material to be measured are being correctly measured by the two-dimensional imaging device 2, whose orientation has been adjusted by the calibration jig 31.

[0054] The above explanation assumes the use of four two-dimensional imaging devices 2, but the number of two or more two-dimensional imaging devices 2 is not limited to four. For example, as shown in Figure 12, when using two two-dimensional imaging devices 2, the imaging range of each two-dimensional imaging device 2 should be adjusted so that two corners 15a of the steel material 2 fit within the central region 2F of each two-dimensional imaging device 2. Also, as shown in Figure 13, when using six two-dimensional imaging devices, the imaging range of four of the six two-dimensional imaging devices 2 should be adjusted so that one corner 15a of the steel material 2 fits within the central region 2F of each two-dimensional imaging device 2.

[0055] In other words, the multiple two-dimensional imaging devices 2 should be arranged such that the peripheral edges 2E of their respective imaging ranges overlap each other, and the corner portion 15a of the steel material 15 to be measured is located within the central region 2F of the imaging ranges of all or some of the two-dimensional imaging devices 2. [Explanation of symbols]

[0056] 1...Metal material shape measuring device, 2...Two-dimensional imaging device, 2A~2D...Imaging range, 2E...Peripheral area, 2F...Central area, 3...Image processing means, 11...Rough rolling mill, 14...Metal material rotation mechanism, 15...Steel material (metal material), 15a...Corner, 31...Calibration jig, 32...Point light source, X...Reference position.

Claims

1. A method for measuring the external dimensions of a metal material to be measured using a two-dimensional imaging device installed above the metal material to be measured, Multiple two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of one of the imaging ranges of the two-dimensional imaging devices. Calibration step: A calibration jig having multiple point light sources arranged at predetermined intervals from each other is positioned such that a portion of the point light sources are located at the periphery of the imaging range of the two-dimensional imaging device; the multiple two-dimensional imaging devices image the point light sources of the calibration jig; the difference between the distance between two points of the point light sources in the imaging data of the point light sources and the distance between two points of the point light sources in the calibration jig is determined as an error; it is determined whether the error is less than or equal to a preset threshold; and if the error exceeds the threshold, the orientation of the two-dimensional imaging device is adjusted. The imaging step involves imaging the metal material to be measured using the plurality of two-dimensional imaging devices to obtain imaging data of the metal material, A method for measuring the external dimensions of a metal material, comprising: a measurement step of determining the distance between the long sides or short sides of a metal material from the position of the long side or short side of the metal material in imaging data of the metal material.

2. The method for measuring the external dimensions of a metal material according to claim 1, wherein the frequency of the calibration step is less than the frequency of the imaging step and the measurement step.

3. The method for measuring the external dimensions of a metal material according to claim 1 or 2, characterized in that the plurality of two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward.

4. A method for measuring the external dimensions of a metal material according to any one of claims 1 to 3, characterized in that a verification step is performed to verify the dimensional measurements obtained by the plurality of two-dimensional imaging devices before the imaging step.

5. The method for measuring the external dimensions of a metal material according to any one of claims 1 to 4, wherein the central region of the imaging range is a region in which the amount of distortion in the image when the metal material to be measured is imaged is 3% or less.

6. The method for measuring the external dimensions of a metal material according to any one of claims 1 to 5, wherein the central region of the imaging range is an area of ​​50% or more of the total area of ​​the imaging range.

7. The method for measuring the external dimensions of a metal material according to any one of claims 1 to 6, wherein the two-dimensional imaging device is an infrared camera.

8. A method for measuring the external dimensions of a metal material according to any one of claims 1 to 7, wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device and imaging is performed.

9. Multiple two-dimensional imaging devices are installed above the metal material to be measured, The system includes an image processing means that determines the external dimensions of a metal material to be measured based on the imaging data output from the two-dimensional imaging device, A calibration method for measuring the external dimensions of a metal material, wherein the plurality of two-dimensional imaging devices are arranged such that the peripheral edges of their respective imaging ranges overlap each other, and all corners of the metal material to be measured are located within the central region of any of the imaging ranges of the two-dimensional imaging devices, The first step is to position a calibration jig having a plurality of point light sources arranged at predetermined intervals from each other, such that a portion of the point light sources are located at the periphery of the imaging range of the two-dimensional imaging device, A second step involves imaging the point light source of the calibration jig using the plurality of two-dimensional imaging devices, In the second step, the difference between the distance between two points of the point light source in the image data of the point light source captured and the distance between two points of the point light source in the calibration jig is determined as an error, it is determined whether the error is less than or equal to a preset threshold, and if the error exceeds the threshold, the orientation of the two-dimensional imaging device is adjusted in the third step. A calibration method for a metal material external dimension measuring device comprising the above.

10. The calibration method for a metal material external dimension measuring device according to claim 9, wherein the point light source is an LED light source.

11. The calibration method for measuring the external dimensions of a metal material according to claim 9, wherein the image processing means identifies the position of the long side or short side of the metal material in the imaging range from the imaging data of the metal material to be measured, which is captured by the plurality of two-dimensional imaging devices, and determines the distance between the long sides or short sides of the metal material.

12. The calibration method for measuring the external dimensions of a metal material according to claim 9 or 11, characterized in that the plurality of two-dimensional imaging devices are arranged within the projection area when the metal material to be measured is projected upward.

13. A calibration method for measuring the external dimensions of a metal material according to any one of claims 9 to 12, wherein the plurality of two-dimensional imaging devices are mounted on a single support.

14. Calibration method for measuring the external dimensions of a metal material according to any one of claims 9 to 13, wherein the central region of the imaging range is a region in which the amount of distortion in the image when the metal material to be measured is imaged is 3% or less.

15. A calibration method for measuring the external dimensions of a metal material according to any one of claims 9 to 14, wherein the central region of the imaging range is an area of ​​50% or more of the total area of ​​the imaging range.

16. A calibration method for a metal material external dimension measuring device according to any one of claims 9 to 15, wherein the two-dimensional imaging device is an infrared camera.

17. A calibration method for measuring the external dimensions of a metal material according to any one of claims 9 to 16, wherein a filter that transmits near-infrared light is attached to the two-dimensional imaging device.

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