Metal strip shape detection device, rolling mill, and detection method

Abstract

This enables highly accurate evaluation of changes in the distribution of sheet elongation even when vibration is occurring in the metal strip. [Solution] In an acquired image, the movement distances in the rolling direction of upstream pixel points and downstream pixel points that form the upstream boundary line of a reflected light area are determined, the reflected light area is divided into j divided areas in the plate width direction to form j divided areas, the average movement speed and the number of sign reversals thereof, as well as the fluctuation frequency are determined for each divided area, and the average value of the fluctuation frequency of the upstream pixel points and the downstream pixel points is regarded as information corresponding to the average fluctuation frequency of the upstream pixel points and downstream pixel points of the reflected light area and is made to correspond to the center position in the plate width direction of divided area i. When a value indicating the position in the plate width direction is made a variable x, the position in the plate width direction within the plate width range of an area in the image is normalized to the range of -1≦x≦1, and the value of the information is used as an index corresponding to the rolled plate elongation distribution in the plate width direction obtained from the (k)th image, and the coefficients are determined by fitting the information value to a Chebyshev polynomial. The coefficient C1' of the first-order term is transmitted as a detection result signal of the rolled plate elongation distribution of the first-order component in the plate width direction of the (k)th image.

Description

[Technical field]

[0001] The present invention relates to a metal strip shape detection device, a rolling mill, and a detection method. [Background technology]

[0002] Patent Document 1 describes a defect judgment device and method that can easily judge defects in the plate surface shape of a metal strip without using a special light source such as a rod-shaped light source, and includes a roll that is installed with a rotating axis extending in the width direction of the rolled steel plate and lifts the rolled steel plate upward, a camera that takes an image including the lifted area of ​​the rolled steel plate lifted upward by the roll, and a control device that judges defects in the plate surface shape of the metal strip based on the image taken by the camera.

[0003] Patent Document 2 describes a metal strip shape determination device, rolling mill, and method that are less susceptible to the effects of slight disturbances or suddenly appearing small obstacles than conventional devices, and describes the device and rolling mill comprising: a camera installed to capture an image including an area in which a strip of reflected light is visible across the width of the rolled metal strip; and an image processing computer that determines the shape of the metal strip based on the image captured by the camera, and the image processing computer divides the area in the image into a plurality of areas in the width direction of the metal strip, and transmits information corresponding to the distribution of the strip elongation in the rolling direction in the width direction as a signal, based on index information indicating the size of the area in each divided area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6808888 [Patent Document 2] Patent No. 7130350 Summary of the Invention [Problem to be solved by the invention]

[0005] There are many known techniques for detecting the quality of the shape of a metal strip rolled by a rolling mill, for example the presence or absence of elongation, based on long linear or rod-shaped reflected light in the width direction of the metal strip.

[0006] This detection method is based on the fact that when a part of the plate stretches and the shape of the plate changes, the reflected light no longer has a regular line or rod shape, and part of the plate moves or becomes displaced.

[0007] However, with linear or rod-shaped illumination, the reflected light area in the rolling direction at each position in the plate width direction reflected on the plate surface is narrow, so there is a problem that it is significantly affected by slight disturbances, such as small obstacles, and is prone to false detection.

[0008] The inventors discovered that the effects of external disturbances can be reduced by detecting changes in the band-shaped reflected light area on the plate surface near the curved portion of a metal band plate lifted by a tension control looper installed between rolling mill stands on a rolling line using ordinary lighting, as disclosed in Patent Document 1, and came up with the technology disclosed in Patent Document 2 as a technology that makes better use of the characteristics of the band-shaped reflected light area.

[0009] In the technology described in Patent Document 2, the strip elongation distribution in the strip width direction, such as the length in the rolling direction and area of ​​a strip-like reflected light area reflected on the strip surface near the curved part of the metal strip lifted by a tension control looper installed between rolling mill stands in a rolling line, is applied to a Chebyshev polynomial to find the coefficients of the Chebyshev polynomial and to determine the strip elongation distribution in the strip width direction.

[0010] In actual rolling, the metal strip may vibrate in the looper section, and the position, length in the rolling direction, area, etc. of the reflected light area reflected on the surface of the metal strip being rolled are constantly changing, and a phenomenon is observed in which the reflected light area does not remain stably in the same position.

[0011] As a result of extensive investigations by the inventors into the technology described in Patent Document 2 mentioned above, it became clear that there are cases in which the technology described in Patent Document 2 is unable to deal with such fluctuations in the reflected light area.

[0012] The present invention provides a metal strip shape detection device, a rolling mill, and a detection method that are capable of evaluating changes in strip elongation distribution with high accuracy even when vibrations are occurring in the metal strip. [Means for solving the problem]

[0013] The present invention includes a number of means for solving the above-mentioned problems. One example of the present invention is a strip shape detection device for a rolled metal strip, comprising: a camera installed in a rolling facility so as to capture an image including a range in which a strip-shaped area where illumination light is reflected transversely in the strip width direction, called a reflected light area, can be confirmed on the surface of a metal strip lifted by a looper; and an image processing unit that detects the strip shape of the metal strip based on the image captured by the camera, the image processing unit numbering the images acquired in the order of 1, 2, 3, . . . , k, . . . and detecting the (k)th image. In the image, the pixel position Pu(k)p (p=1 to Ru, where Ru is the number of pixel points constituting the upstream boundary of the reflected light region) in the rolling direction of the pixel point constituting the downstream boundary of the reflected light region and the pixel position Pd(k)q (q=1 to Rd, where Rd is the number of pixel points constituting the downstream boundary of the reflected light region) in the rolling direction of the pixel point constituting the downstream boundary of the reflected light region are obtained, and the moving distance Mu(k)p in the rolling direction of the pixel point on the upstream boundary is calculated from the difference between the pixel position Pu(k-1)p of image number (k-1) and the pixel position Pu(k)p of image number (k). a moving distance Md(k)q in the rolling direction of the pixel point on the downstream boundary line is calculated from the difference between the pixel position Pd(k-1)q of image number (k-1) and the pixel position Pd(k)q of image number (k); a divided area (i) (i = 1 to j) is formed by dividing the reflected light area into j areas in the strip width direction; when the (k)th image is captured, an average moving distance Mu(k)i of the moving distances Mu(k)p of the pixel points on the upstream boundary line and an average moving distance Md(k)i of the moving distances Md(k)q of the pixel points on the downstream boundary line are calculated for the pixel points present within the divided area (i) at the time of capturing the (k)th image; ) and the image acquisition time of image number (k), and for each divided area (i), an average moving speed Vu(k)i of pixel points on the upstream boundary line is calculated from the time Ts and the average moving distance Mu(k)i, and for each divided area (i), an average moving speed Vd(k)i of pixel points on the downstream boundary line is calculated from the time Ts and the average moving distance Md(k)i, and for each divided area (i), a number Nu(k)i of positive and negative sign inversions of the average moving speed Vu(k)i of pixel points on the upstream boundary line between acquisition of the (k-F+1)th image to the (k)th image;A number Nd(k)i of positive and negative sign reversals of an average moving speed Vd(k)i of pixel points on the downstream boundary line is calculated, a time Tf between image number (k-F+1) and the image acquisition time of image number (k) is calculated, and an average fluctuation frequency Qu(k)i of pixel points constituting the upstream boundary line is calculated for each divided area (i) from the time Tf and the number Nu(k)i of sign reversals, and an average fluctuation frequency Qd(k)i of pixel points constituting the downstream boundary line is calculated for each divided area (i) from the time Tf and the number Nd(k)i of sign reversals, and the average fluctuation frequency Qu the average value of the two, Qd(k)i and the average fluctuation frequency Qd(k)i, is calculated for each divided area (i), and the obtained average value is regarded as information Q(k)i corresponding to the two average fluctuation frequencies of the pixel points constituting the upstream boundary line and the pixel points constituting the downstream boundary line of the reflected light area of ​​the (k)th image, the value of the information Q(k)i is made to correspond to the central position in the sheet width direction of the divided area (i), and a value indicating the position in the sheet width direction is made a variable (x), and the position in the sheet width direction within the sheet width range of the reflected light area in the image is normalized to the range of -1≦x≦1, j pcs The above information The value of Q(k)i is an index corresponding to the distribution of elongation in the width direction of the rolled strip obtained from the (k)th image, and the notation of the position in the width direction is changed to (x), so that Q(k)i = E(xi). E(x) = C0' + C1' × x + C2' × (2x 2 -1)+C4'×(8x 4 -8x 2 +1) (where -1≦x≦1) to find the coefficients (C0', C1', C2', C4') of the Chebyshev polynomial from E(xi) having j x values ​​(xi), and transmit the coefficient (C1') of the first-order term as a detection result signal of the rolled strip elongation distribution of the first-order component in the strip width direction of the (k)th image. Here, xi is the (x) notation indicating the center position in the strip width direction of the divided area (i) obtained by dividing the reflected light area into j in the strip width direction. Note that F, i, j, and k are integers. Effect of the Invention

[0014] According to the present invention, even when vibration occurs in the metal strip, the change in strip elongation distribution during rolling can be evaluated with high accuracy. Other objects, configurations and effects than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing an example of an outline of a rolling facility equipped with a metal strip shape detection device according to an embodiment of the present invention; [Diagram 2] FIG. 13 is a diagram showing an example of how reflected light from an illumination is projected in a roughly rectangular band shape in the strip width direction on the surface of a metal strip in a looper section between stands during operation in a rolling facility. [Diagram 3] FIG. 13 is a diagram showing an example of how reflected light from an illumination is reflected in an irregular band shape in the width direction of a metal strip plate at a looper section between stands during operation of a rolling facility. [Figure 4] This is a diagram showing the definition of the leveling amount (Gd-Gw) when Gd=Gw. [Diagram 5] This is a diagram showing the definition of the leveling amount (Gd-Gw) when Gd>Gw. [Figure 6] FIG. 13 shows an example of the relationship between the (k-1)th image and the rolling direction movement distance Mu(k)p when the rolling direction position Pu(k-1)p of the pixel constituting the upstream boundary line of the reflected light area from the (k)th image moves to Pu(k)p in the plate shape detection device for a metal strip plate of the embodiment. [Figure 7] FIG. 13 shows an example in which the movement distance of each pixel moved in the rolling direction as Mu(k)p from the (k-1)th image and the (k)th image in the plate shape detection device for a metal strip plate of an embodiment is averaged for each divided area (i) obtained by dividing the reflected light area in the plate width direction, and the averaged movement distance in the rolling direction is re-expressed as Mu(k)i. [Figure 8] FIG. 4 is a diagram showing an example of a method for equally dividing the sheet width direction in the sheet shape detection device for a metal strip sheet according to the embodiment. [Figure 9] 1 is a diagram showing an example of a method for unequally dividing the sheet width direction in the sheet shape detection device for a metal strip sheet according to an embodiment; [Figure 10]FIG. 13 shows an example in which average moving speeds Vu(k)i and Vd(k)i in divided area (i) of pixels constituting the upstream boundary line and pixels constituting the downstream boundary line of the reflected light area from the (k)th image are divided by the elapsed time Ts between the (k-1)th image and the (k)th image in the plate shape detection device for a metal strip plate of the embodiment to determine the moving distances Mu(k)i and Md(k)i in the rolling direction for each divided area (i) of pixels constituting the upstream boundary line and pixels constituting the downstream boundary line of the reflected light area from the (k)th image. [Figure 11] FIG. 13 shows an example of the number of positive and negative sign reversals Nu(k)i and Nd(k)i of the average moving speeds Vu(k)i and Vd(k)i calculated for each divided area (i) of the pixels constituting the upstream boundary line and the pixels constituting the downstream boundary line of the reflected light area during the time Tf between the (k+F-1)th image and the (k)th image in the plate shape detection device for a metal strip plate of an embodiment. [Figure 12] FIG. 13 shows an example of two average fluctuation frequencies Q(k)i, the average fluctuation frequency Qu(k)i of the pixels constituting the upstream boundary line in the rolling direction of the reflected light area and the average fluctuation frequency Qd(k)i of the pixels constituting the downstream boundary line, calculated from the number of positive and negative sign reversals Nu(k)i and Nd(k)i for each divided area (i) calculated from the (k+F-1)th image to the (k)th image in the plate shape detection device for a metal strip plate of an embodiment. [Figure 13] 4 is a first half of a flowchart for detecting the plate shape in the plate shape detection device for a metal strip plate according to the embodiment. [Figure 14] 11 is a second half of a flow chart showing detection of a plate shape in the plate shape detection device for a metal strip plate according to the embodiment. [Figure 15] FIG. 2 is a diagram showing an example of a monitor display screen showing the 0th-order component, 1st-order component, 2nd-order component, and 4th-order component of x of a Chebyshev polynomial in the plate shape detection device for a metal strip plate of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The plate shape detection device for a metal strip, the rolling mill, and the detection method according to the present invention will be described with reference to Fig. 1 to Fig. 15. In the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated explanations of these components may be omitted.

[0017] First, the overall configuration of the rolling facility including the metal strip shape detection device will be described with reference to Figures 1 to 3. Figure 1 is a schematic diagram showing the configuration of the metal strip shape detection device of this embodiment and the rolling facility equipped with it, and Figures 2 and 3 are diagrams showing an example of the state in which reflected light from an illumination is reflected in a strip shape on the surface of the metal strip in the looper section between stands during operation in the rolling facility.

[0018] The rolling equipment 100 for rolling a metal strip 1 shown in FIG. 1 includes an F1 stand 10, an F2 stand 20, an F3 stand 30, an F4 stand 40, an F5 stand 50, cameras 61, 62, 63, 64, loopers 71, 72, 73, 74 for tension control, an image processing computer 80, a database 81, a control device 82, a monitor 85, etc.

[0019] The F1 stand 10, F2 stand 20, F3 stand 30, F4 stand 40, F5 stand 50, cameras 61, 62, 63, 64, image processing computer 80, database 81, control device 82, and monitor 85 are connected by a communication line 90.

[0020] Of these, the cameras 61, 62, 63, and 64, the loopers 71, 72, 73, and 74, the image processing computer 80, and the database 81 constitute the plate shape detection device for the metal strip 1 of the present invention.

[0021] The rolling facility 100 is not limited to a configuration in which five rolling stands are installed as shown in FIG. 1, but may have at least two stands.

[0022] Each of the F1 stand 10, F2 stand 20, F3 stand 30, F4 stand 40, and F5 stand 50 is equipped with an upper work roll, a lower work roll, an upper backup roll which supports the upper and lower work rolls by contacting them, respectively, a lower backup roll, pressure reduction cylinders 11, 21, 31, 41, 51 provided above the upper backup rolls, and load detectors 12, 22, 32, 42, 52. Note that a six-stage configuration can be made by further providing intermediate rolls between each work roll and each backup roll.

[0023] The looper 71 is a roll for tension control installed between the F1 stand 10 and the F2 stand 20. The looper 71 is disposed with its rotation axis extending in the width direction of the metal strip 1 so that the traveling metal strip 1 rests on the roll, and is installed so as to lift and hold the metal strip 1 upward. The looper 71 may be, for example, one that is biased upward by a spring or the like, or one that is lifted by a hydraulic cylinder or motor drive, etc.

[0024] Similarly, a tension control looper 72 is installed between the F2 stand 20 and the F3 stand 30, a tension control looper 73 is installed between the F3 stand 30 and the F4 stand 40, and a tension control looper 74 is installed between the F4 stand 40 and the F5 stand 50.

[0025] The camera 61 is installed so as to capture an image of the surface of the metal band 1 including a range in which a strip-shaped area where illumination light is reflected transversely in the strip width direction, called a reflected light area 2, can be confirmed on the surface of the curved metal band 1 that has been rolled and lifted by the looper 71. The camera 61 can be preferably installed on the outer side in the strip width direction of the metal band 1 when the metal band 1 is viewed from above. Data of the image captured by the camera 61 is transmitted to the image processing computer 80 via a communication line 90.

[0026] It is preferable to use a high-speed camera for this camera 61. The image acquisition speed can be, for example, 1000 to 2000000 frames per second (FPS), but these specific upper and lower limits are merely examples and are not limited to these values. It is preferable to use high-speed cameras for cameras 62, 63, and 64, which will be described later, as well as camera 61.

[0027] Camera 62 is installed at a position to capture an image of the surface of metal band 1 including a range where a strip-like area called reflected light area 2, which is transverse to the strip width direction and reflects illumination light, can be confirmed on the surface of metal band 1 after it has been rolled and lifted by looper 72; camera 63 is installed at a position to capture an image of the surface of metal band 1 including a range where a strip-like area called reflected light area 2, which is transverse to the strip width direction and reflects illumination light, can be confirmed on the surface of metal band 1 after it has been rolled and lifted by looper 73; and camera 64 is installed at a position to capture an image of the surface of metal band 1 including a range where a strip-like area called reflected light area 2, which is transverse to the strip width direction and reflects illumination light, can be confirmed on the surface of metal band 1 after it has been rolled and lifted by looper 74. Data of the images captured by cameras 62, 63, 64 are transmitted to image processing computer 80 via communication line 90.

[0028] Similarly to the camera 61, the cameras 62, 63, and 64 are preferably installed on the outer sides of the metal band 1 in the width direction when the metal band 1 is viewed from above.

[0029] A photographing step is executed in which the cameras 61, 62, 63, 64 photograph an image including an area in which strip-shaped reflected light that crosses the rolled metal strip 1 in the strip width direction is captured.

[0030] It is possible to further provide lighting for illuminating the lifted photographing area of ​​the metal strip 1 lifted upward by the rolls, which is mainly photographed by the cameras 61, 62, 63, and 64. This lighting may be general lighting appropriately arranged on the ceiling of the rolling factory where the rolling equipment 100 is installed, and no special new lighting equipment is required in the present invention, but dedicated lighting may be provided.

[0031] The image processing computer 80 is a device that executes various processes (including image processing steps) for detecting the plate shape of the metal strip 1 based on the images captured by the cameras 61, 62, 63, and 64, and preferably, this image processing computer 80 is the main entity that executes the image processing steps.

[0032] For example, an image including the lifted area, which is near the curve of the metal strip 1 being rolled as shown in Figure 2 or Figure 3 and lifted by loopers 71, 72, 73, and 74, is processed to identify, as reflected light area 2, an area including the upstream and downstream boundaries of a point in the image where the brightness of the reflected light on the surface of the metal strip 1 is greater than a specific brightness value.

[0033] Here, if the elongation in the rolling direction (longitudinal direction of the strip) at each position in the width direction of the metal strip 1 is uniform, the surface of the metal strip 1 is flat and has small plate waves, so that the difference in distribution due to the illumination is small, as shown in Figure 2. For this reason, the boundary line of the reflected light region 2 due to illumination is approximately parallel with an approximately uniform distance between the upstream boundary line 2A and the downstream boundary line 2B, and when the reflected light region 2 is divided into multiple zones in the width direction, parameters such as the area value of each zone and the average length in the rolling direction are approximately uniform in all zones.

[0034] In contrast, when there is a difference in elongation in the rolling direction depending on the position in the strip width direction (e.g., end elongation, center elongation), the metal strip is not flat, and the lighting hits it differently due to differences in steepness caused by strip waves, etc., so that the boundary line of the reflected light area 2 caused by the lighting is wavy at either the upstream boundary line 2A or the downstream boundary line 2B, or both, as shown in Figure 3, and the distance between the upstream boundary line 2A and the downstream boundary line 2B of the reflected light area 2 becomes uneven. For this reason, when the metal strip-shaped reflected light area 2 is divided into multiple zones in the strip width direction, parameters such as the area value of each zone and the average length in the rolling direction become uneven for each zone.

[0035] In the above-mentioned Patent Document 1, the sheet width direction distribution such as the rolling direction length and area of ​​the reflected light area 2 reflected on the surface of the metal strip 1 near the curved portion of the metal strip 1 lifted by the loopers 71, 72, 73, and 74 is used as an index of the sheet elongation distribution due to rolling, and curve fitting (curve approximation) is performed using the Chebyshev polynomial of the following equation (1).

[0036] E(x) = C0'+C1'×x+C2'×(2x 2 -1)+C4'×(8x 4 -8x 2 +1) (where -1≦x≦1) (1) In the Chebyshev polynomial, for example, as an index of the distribution of elongation in the strip width direction due to rolling, the length in the rolling direction of the reflected light area 2 on the surface of the metal strip 1 at the loopers 71, 72, 73, 74 is assumed to be E(x), which indicates the length in the rolling direction of the reflected light area 2 on the surface of the metal strip 1 at the loopers 71, 72, 73, 74 and also indicates the magnitude corresponding to the strip elongation due to rolling. Note that C0', C1', C2', and C4' indicate the values ​​of the coefficients when the Chebyshev polynomial, which is assumed to indicate the magnitude corresponding to the distribution of elongation in the strip width direction, is separated into the 0th, 1st, 2nd, and 4th order components of x. x indicates the normalized position in the strip width direction, for example, x=-1 indicates the strip width end position on the driving side (DS), and x=1 indicates the strip width end position on the working side (WS). In other words, in this case, if the coefficient (C1') of the first-order component of x in the Chebyshev polynomial is a positive value, it indicates that the strip elongation on the working side (WS) is large. Also, if the coefficient (C2') of the second-order component of x is a positive value, it indicates that the elongation at the strip width ends is larger than that at the strip width center. Also, if the coefficient (C4') of the fourth-order component of x is a negative value, it indicates that the quarter elongation in the strip width direction is large.

[0037] The leveling amount is defined as follows.

[0038] As shown in Figs. 4 and 5, the leveling amount is defined as the value (Gd - Gw) obtained by subtracting the distance Gw between the axial centers of the upper and lower work rolls at the position of the reduction cylinder on the work side (WS) from the distance Gd between the axial centers of the upper and lower work rolls at the position of the reduction cylinder on the drive side (DS).

[0039] When the leveling amount is changed, the plate thickness at the center of the plate width is not changed. Therefore, as shown in Fig. 5, when the leveling amount is increased compared to the state shown in Fig. 4, the plate thickness on the drive side (DS) becomes thicker and the plate thickness on the work side (WS) becomes thinner, and the plate elongation on the work side (WS) becomes larger. When the value of the Chebyshev first-order component (C1') obtained by this method is positive, it indicates that the plate elongation on the work side (WS) is large, and when it is negative, it indicates that the plate elongation on the drive side (DS) is large.

[0040] In the image processing computer 80 in this embodiment, the following five analysis processes are carried out for each of the acquired images using the acquired images.

[0041] In the first analysis process performed by the image processing computer 80, as shown in Fig. 6, the images are numbered in the order of acquisition as 1, 2, 3, . . . , k, and in the (k)th image, pixel positions Pu(k)p (p = 1 to Ru, where Ru is the number of pixels constituting the upstream boundary 2A of the reflected light area 2) in the rolling direction of the upstream pixel point constituting the upstream boundary 2A of the reflected light area 2 and pixel positions Pd(k)q (q = 1 to Rd, where Rd is the number of pixels constituting the downstream boundary 2B of the reflected light area 2) in the rolling direction of the downstream pixel point constituting the downstream boundary 2B of the reflected light area 2, which are not shown in Fig. 6, are obtained. This data is preferably stored in a database 81.

[0042] Here, as described above, since the boundary line of the reflected light region 2 fluctuates during rolling, in this embodiment, as a second analysis process performed by the image processing computer 80, a moving distance Mu(k)p (=Pu(k)p-Pu(k-1)p) of a pixel point on the upstream boundary line 2A of the reflected light region 2 is calculated in the rolling direction from the pixel position Pu(k-1)p of image number (k-1) and the pixel position Pu(k)p of image number (k) stored in the database 81, as shown in FIG. 6, and also a moving distance Md(k)q (=Pd(k)q-Pd(k-1)q) of a pixel point on the downstream boundary line 2B of the reflected light region 2 in the rolling direction is calculated from the pixel position Pd(k-1)q of image number (k-1) and the pixel position Pd(k)q of image number (k), although not shown in FIG. 6.

[0043] Furthermore, in the second analysis process performed by the image processing computer 80, as shown in FIG. 7, the moving distance Mu(k)p in the rolling direction of the pixel points on the upstream boundary line 2A of the reflected light region 2 is reconsidered within the range of divided regions (i) (i = 1 to j) obtained by dividing the reflected light region 2 into j regions in the plate width direction, the average value of the moving distances Mu(k)p in the rolling direction of the pixel points on the upstream boundary line 2A present within the divided region (i) is calculated, and this is set as the average moving distance Mu(k)i for the pixel points that constitute the upstream boundary line 2A of the reflected light region 2 in the divided region (i). Similarly, although not shown in FIG. 7, the moving distance Md(k)q in the rolling direction of the pixel points on the downstream boundary line 2B is calculated as the average value of Md(k)q present within the divided region (i), and this is set as the average moving distance Md(k)i for the pixel points that constitute the downstream boundary line 2B of the reflected light region 2 in the divided region (i).

[0044] As a method of dividing the reflected light region 2, each divided area (i) (i = 1 to j) divided into j areas in the plate width direction may be equally divided into j equal widths as shown in FIG. 8, or each of the j areas may be unequally divided into any width as shown in FIG. 9.

[0045] Next, the third analysis process performed by the image processing computer 80 is to divide the average movement distance Mu(k)i of the pixel points that constitute the upstream boundary line 2A of the reflected light area 2 in the divided area (i) into j divisions of the reflected light area 2 in the plate width direction, and the average movement distance Md(k)i of the pixel points that constitute the downstream boundary line 2B of the reflected light area 2 in the divided area (i) by the time Ts required from the acquisition of the (k-1)th image to the acquisition of the (k)th image, to calculate the average movement speed Vu(k)i (=Mu(k)i / Ts) of the pixel points that constitute the upstream boundary line 2A and the average movement speed Vd(k)i (=Md(k)i / Ts) of the pixel points that constitute the downstream boundary line 2B for each divided area (i) of the reflected light area 2.

[0046] Next, the fourth analysis process performed by the image processing computer 80, as shown in Figure 11, is to determine how many times the positive and negative signs (+ / -) of the average movement speed Vu(k)i of the pixel points that constitute the upstream boundary 2A and the average movement speed Vd(k)i of the pixel points that constitute the downstream boundary 2B have reversed during the time Tf required from the acquisition of the (k-F+1)th image to the acquisition of the (k)th image, and to obtain the number of sign reversals Nu(k)i of the average movement speed Vu(k)i of the pixel points that constitute the upstream boundary 2A of the reflected light area 2 in the divided area (i) and the number of sign reversals Nd(k)i of the average movement speed Vd(k)i of the pixel points that constitute the downstream boundary 2B of the reflected light area 2.

[0047] Then, in the fifth analysis process performed by the image processing computer 80, as shown in FIG. 12, the average fluctuation frequency Qu(k)i (=[Nu(k)i / Tf] / 2) of the pixel points that constitute the upstream boundary line 2A of the reflected light area 2 and the average fluctuation frequency Qd(k)i (=[Nd(k)i / Tf] / 2) of the pixel points that constitute the downstream boundary line 2B are calculated from the number of sign reversals Nu(k)i and Nd(k)i, and further, Q(k)i (=[Qu(k)i+Qd(k)i] / 2) is calculated as the average fluctuation frequency of the pixel points that constitute the upstream and downstream boundaries (2A, 2B) that form the reflected light area 2 for each divided area (i).

[0048] Furthermore, as a continuation of the fifth analysis process performed by the image processing computer 80, the value of the obtained information Q(k)i is an index corresponding to the elongation of the rolled plate in the (k)th image, and a value indicating the position in the plate width direction is a variable (x). The position in the plate width direction within the plate width range is normalized to the range of -1≦x≦1, the central position of each divided area (i) in the plate width direction is made to correspond to xi, and Q(k)i is made the Chebyshev polynomial E(xi)=Q(k)i of Equation (1) at the time of the (k)th image.

[0049] Then, the j values ​​of E(xi) (i.e., E(xi) = Q(k)i) obtained at the central position xi of each divided area (i) (i = 1 to j) in the sheet width direction of the reflected light area 2 of the (k)th image are applied to the Chebyshev polynomial in equation (1) for each divided area (i) to perform curve fitting using the least squares method, and the coefficients (C0', C1', C2', C4') of the Chebyshev polynomial are found from the equation of the approximation curve. The first-order coefficient (C1') is transmitted as a detection result signal of the rolled sheet elongation distribution of the first-order component in the sheet width direction.

[0050] Preferably, the image processing computer 80 can further transmit at least one of the quadratic coefficient of x (C2') or the fourth-order coefficient of x (C4') in addition to the first-order coefficient of x (C1') of the Chebyshev polynomial as a detection result signal of the second-order or fourth-order component of the elongation distribution of the rolled sheet in the sheet width direction.

[0051] The database 81 also functions as a recording medium in which various parameters used when operating the rolling equipment 100 are recorded.

[0052] Returning to FIG. 1, the control device 82 is a device that controls the operation of each piece of equipment in the rolling equipment 100, and in this embodiment, is a device that executes various controls in response to detection of the plate shape of the metal strip 1 by the image processing computer 80.

[0053] The image processing computer 80, database 81, and control device 82 can be configured as a computer having a monitor 85 such as a liquid crystal display described later, an input device, a storage device, a CPU, memory, etc., and these may be configured as a single computer, or each may be configured as a separate computer, and are not particularly limited.

[0054] The control of the operation of each device by the image processing computer 80 and the control device 82 is executed based on various programs recorded in the storage device. The control processing of the operation executed by the image processing computer 80 and the control device 82 may be integrated into one program, or each may be separated into multiple programs, or a combination of these. Also, some or all of the programs may be realized by dedicated hardware, or may be modularized.

[0055] The monitor 85 is a display device such as a display or an audio device such as an alarm. Since the monitor 85 is a device for informing an operator of the corrective action to be taken when, for example, the image processing computer 80 detects that a problem has occurred in the plate shape, a display is often used as such a monitor 85.

[0056] Here, the image processing computer 80 described above includes a display signal section, and transmits signals relating to the contents to be displayed on the monitor 85 to the control device 82 and the monitor 85 .

[0057] During operation, the operator can check the state of the strip shape by visually checking the display screen of the monitor 85, each stand itself, and spaces between each stand.

[0058] In addition, the present invention is not limited to a configuration in which the control device 82 automatically notifies the operator of the occurrence of a problem in the plate shape and performs operations to improve the plate shape problem, but may be a configuration in which the control device 82 only displays the information on the monitor 85, or a configuration in which the display on the monitor 85 is omitted and the control device 82 only automatically performs operations to improve the plate shape problem.

[0059] Next, the flow of the plate shape detection device and detection method for the rolled metal strip 1 in the present invention will be described with reference to Figures 13 and 14. Figures 13 and 14 show a flow chart of a method for calculating the average fluctuation frequency Q(k)i of the upstream and downstream boundary lines (2A, 2B) forming the reflected light region 2, which serves as an index of the present invention.

[0060] As shown in FIG. 13, before the start of rolling or during rolling, the image processing computer 80 sets the number of images F (e.g., F=1000) for judging the average fluctuation frequency of the boundary line of the reflected light region 2 (step S201), and also sets the image number k (step S202).Here, the initial value of the image number is k=1.

[0061] Thereafter, the image processing computer 80 acquires surface images (k) of the metal strip 1 in the vicinity of the curved portion of the metal strip 1 lifted by the loopers 71, 72, 73, 74, photographed by the cameras 61, 62, 63, 64 (step S203). Here, the acquired images are numbered in the order of acquisition, such as 1, 2, 3, . . . , k, . . .

[0062] Next, the image processing computer 80 processes the images (k) taken by the cameras 61, 62, 63, and 64 to extract the reflected light region 2 on the surface of the metal band 1 in the vicinity of the curved portion of the metal band 1 (step S204).

[0063] For example, the image processing computer 80 performs binarization processing on all pixels (picture elements) captured in a selected rolled surface image range among the images captured by the cameras 61, 62, 63, and 64, and obtains an appropriate brightness threshold value, thereby obtaining pixel coordinates constituting the upstream boundary line 2A and downstream boundary line 2B seen in the strip width direction on the upstream and downstream sides of the reflected light area 2 projected on the surface of the metal strip, and identifying the reflected light area 2. The details can be a known method.

[0064] Next, the image processing computer 80 stores the position Pu(k)p in the rolling direction of the pixel points constituting the upstream boundary line 2A of the reflected light region 2 for the image acquired (k)-th among the images captured by the cameras 61, 62, 63, 64 (step S205), and stores the position Pd(k)q in the rolling direction of the pixel position of the downstream boundary line 2B of the reflected light region 2 (step S206). Here, p is the pixel number constituting the upstream boundary line 2A, representing p = 1 to (the number of pixels Ru constituting the upstream boundary line), q is the pixel number constituting the downstream boundary line 2B, representing q = 1 to (the number of pixels Rd constituting the downstream boundary line). These steps S205 and S206 may be in any order, may be processed in parallel, or step S206 may be processed prior to step S205.

[0065] Next, the image processing computer 80 determines whether the image number k < F (step S207). When it is determined that the image number k < F, the process proceeds to step S208, where the image number k is updated (k = k + 1) (step S208), and the process proceeds to step S203, waiting for the processing of a predetermined number of images. On the other hand, when it is determined in step S207 that the image number k ≧ F, the process proceeds to step S209.

[0066] Next, the image processing computer 80 calculates the moving distance Mu(k)p (= Pu(k)p - Pu(k - 1)p) from the pixel position Pu(k - 1)p of the upstream boundary line 2A of the image number (k - 1) and the pixel position Pu(k)p of the upstream boundary line 2A of the image number (k) (step S209), and calculates the moving distance Md(k)q (= Pd(k)q - Pd(k - 1)q) from the pixel position Pd(k - 1)q of the downstream boundary line 2B of the image number (k - 1) and the pixel position Pd(k)q of the downstream boundary line 2B of the image number (k) (step S210).

[0067] Next, the image processing computer 80 divides the reflected light region 2 extracted from the image (k) captured by the cameras 61, 62, 63, 64 into j parts in the plate width direction (for example, j = 7) (step S211).

[0068] Next, as shown in FIG. 14, at the time of camera image (k), the image processing computer 80 uses the movement distance Mu(k)p of the pixel point on the upstream boundary line 2A obtained in step S209 to calculate the average movement distance Mu(k)i (=average [Mu(k)p]i (i=1 to j)) in each divided area (i) (i=1 to j) of the reflected light area divided into j parts in the plate width direction, and also uses the movement distance Md(k)q of the pixel point on the downstream boundary line 2B obtained in step S210 to calculate the average movement distance Md(k)i (=average [Md(k)q]i) (i=1 to j) in each divided area (i) (i=1 to j) of the reflected light area divided into j parts in the plate width direction (step S212).

[0069] Next, the image processing computer 80 calculates the time Ts (=T(k)-T(k-1)) between the image acquisition times T(k-1) and T(k) of image number (k-1) and image number (k), and calculates the average moving speed Vu(k)i (=Mu(k)i / Ts) (i=1 to j) of pixel points on the upstream boundary line 2A from the average moving distance Mu(k)i that they have moved in the time Ts between image number (k-1) and image number (k) in each divided section (i) (i=1 to j) of the reflected light area divided into j sections in the plate width direction, and calculates the average moving speed Vd(k)i (=Md(k)i / Ts) (i=1 to j) of pixel points on the downstream boundary line 2B from the average moving distance Md(k)i that they have moved in the time Ts between image number (k-1) and image number (k) (step S213).

[0070] Next, the image processing computer 80 calculates the number of times that the average moving velocities Vu(k)i and Vd(k)i in the rolling direction of the pixel points constituting the upstream boundary line 2A and the downstream boundary line 2B in each divided section (i) (i = 1 to j) of the reflected light area divided into j sections in the plate width direction, that is, the number of times that the sign reversals have occurred (+ / -), that is, the number Nu(k)i and Nd(k)i (step S214).

[0071] Next, the image processing computer 80 calculates the time Tf (seconds) (=T(k)-T(k-F+1)) required from acquisition of the (k-F+1)th image to acquisition of the (k)th image, and divides the number of sign reversals Nu(k)i of the average moving speed Vu(k)i of the pixel points constituting the upstream boundary line 2A calculated in step S214 by the time Tf seconds and then divides it by 2 to calculate the average fluctuation frequency Qu(k)i (=[Nu(k)i / Tf] / 2) of the pixel points on the upstream boundary line 2A in each of the j divided divided areas (i), and also divides the number of sign reversals Nd(k)i of the average moving speed Vd(k)i of the pixel points constituting the downstream boundary line 2B by the time Tf seconds and then divides it by 2 (step S215).

[0072] Next, in the (k)th acquired image, the image processing computer 80 calculates the average fluctuation frequency Q(k)i (=[Qu(k)i + Qd(k)i] / 2) (i=1 to j) (unit: Hz) of the pixel points constituting the upstream boundary 2A and the downstream boundary 2B in each of the j divided division areas (i) from the average fluctuation frequency Qu(k)i of the pixel points on the upstream boundary 2A calculated in step S215 and the average fluctuation frequency Qd(k)i of the pixel points on the downstream boundary 2B (step S216).

[0073] Next, the image processing computer 80 rewrites the center position in the width direction of each divided area (i) when the reflected light area 2 is divided in the width direction as a variable (x) of the width direction position in each divided area (i), and corresponds the average fluctuation frequency Q(k)i of the two boundaries of the reflected light area 2 in each divided area (i) obtained at the time of the camera image (k) obtained in step S216 to the width direction center position of the divided area (i) as (x), and curve-fits E(xi) expressed as (x) as E(xi)=Q(k)i to the Chebyshev polynomial of equation (1), and calculates the Chebyshev coefficients (C0', C1', C2', C4') from the obtained approximation equation (step S217). Note that xi represents the center position of the divided area (i) when the reflected light area 2 is divided in the width direction when the width direction position is expressed as x.

[0074] The average fluctuation frequency Q(k)i (E(xi)=Q(k)i) of the upstream and downstream boundary lines (2A, 2B) forming the reflected light region 2, which is an index corresponding to the distribution of strip elongation in the rolling direction relative to the strip width direction, is approximated by a Chebyshev polynomial. This approximation has the following features: (1) the strip width range (x-axis) is normalized in the range from -1 to +1, and (2) the first-order component (single elongation), second-order component (center elongation, edge elongation), and fourth-order component (quarter elongation) of x are separated, making it easy to estimate the rolling control operation method for each component.

[0075] Next, the image processing computer 80 transmits the Chebyshev coefficients (C1', C2', C4') determined in step S213 as a detection result signal of the plate elongation distribution in the (k)th image to, for example, the control device 82 or the monitor 85 (step S218).

[0076] Thereafter, the image processing computer 80 judges whether or not the rolling is continuing (step S219), and if it is judged that the rolling is continuing, the process returns to step S208, the image number (k) is updated to (k=k+1), and the plate shape detection process is continued. On the other hand, if it is judged that the rolling is completed, the process is terminated.

[0077] In this embodiment, the third-order component is not adopted in the Chebyshev polynomial. This is because the rolling control mechanism of the rolling mill is not adapted to correct strip elongation of the third-order component, and by omitting the calculation processing and corresponding means of the third-order component, it becomes easier to judge the state of the rolled strip shape of the separated first-order component, second-order component, and fourth-order component and to correct strip elongation.

[0078] The image processing computer 80 can output a control command signal to the control device 82 to correct the leveling, bending force, pair cross angle, etc., based on the polynomial approximation result in the strip width direction obtained by using the Chebyshev polynomial of equation (1). Furthermore, instead of or in addition to this, it can output a display command signal to the monitor 85 to display guidance required for correcting the leveling, bending force, pair cross angle, etc., to convey correction information for the leveling, bending force, pair cross angle, etc. to the operator.

[0079] Preferably, the image processing computer 80 calculates the 0th component [C0'] of x, the 1st component [C1'×x] of x, the 2nd component [C2'×(2x 2 -1)], the fourth component of x [C4'×(8x 4 -8x 2 A signal can be sent to the monitor 85 to display a graph of each component term of (1 + 1). The screen displayed on the monitor 85 is, for example, as shown in FIG.

[0080] Fig. 15 is a diagram showing an example of the display screen of the monitor 85. Fig. 15 shows an example of the distribution display of each of the 0th, 1st, 2nd and 4th order components of x of the Chebyshev polynomial at the strip width direction position (-1≦x≦1) within the strip width. The operator can check the display screen of the monitor 85 shown in Fig. 15 and perform operations to correct, for example, the leveling, bending force, pair cross angle (in the case of a pair cross rolling mill), etc.

[0081] Among the Chebyshev polynomial coefficients, the coefficient (C1') of the first-order component of x indicates an index of one-sided elongation, so an operation command signal is output to the control device 82 to normalize the first-order component (within the target range) by operating the leveling of the driving side (DS) and working side (WS) pressing cylinders 41 upstream of the corresponding camera 64, and / or the driving side (DS) and working side (WS) pressing cylinders 51 downstream.

[0082] The coefficient (C2') of the second-order component of x among the Chebyshev polynomial coefficients indicates an index of edge or middle buckling. Therefore, one or more of the following operations are performed. An operation command signal is output to the control device 82 to operate the bending device of the work rolls / intermediate rolls of the F4 stand 40, which is the rolling mill upstream of the camera 64, and / or the F5 stand 50, which is the rolling mill downstream of the camera 64, to operate the pair cross angle in the case of a pair cross rolling mill, and to shift the work rolls / intermediate rolls in the case of a work roll shift / intermediate roll shift rolling mill, since it is difficult to shift during rolling, by predicting the middle buckling / edge buckling in advance, thereby normalizing the second-order component (within the target range).

[0083] The coefficient (C4') of the fourth-order component of x among the Chebyshev polynomial coefficients indicates an index of quarter elongation. Therefore, in order to correct the quarter elongation, one or more of the following operations are performed. The bending operation of the work roll bending device of the F4 stand 40, which is the rolling mill upstream of the camera 64, and / or the F5 stand 50, which is the rolling mill downstream of the camera 64, is performed, and further, in the case of a pair cross mill, the pair cross angle is operated together with the bending operation or alone. In the case of a six-stage intermediate roll shift rolling mill, the quarter elongation is predicted in advance and the intermediate rolls are shifted to an appropriate position. By outputting an operation command signal to the control device 82 to perform the bending operation and the pair cross angle operation, the fourth-order component indicating the quarter elongation is normalized (within the target range so as to obtain the target plate shape). Note that the smaller the roll diameter is relative to the roll length, the easier the roll is to bend in the region of the roll width end by the bending operation, and the more likely the quarter elongation is to occur, but it can be normalized by the above operation.

[0084] Next, the effects of this embodiment will be described.

[0085] In the plate shape detection device for the metal strip plate 1 in the rolling facility of this embodiment described above, the image processing computer 80 numbers the acquired images in the order of 1, 2, 3, . . . , k, . . . , and in the (k)th image, pixel positions Pu(k)p (p=1 to Ru, where Ru is the number of pixel points constituting the upstream boundary line 2A of the reflected light area 2) in the rolling direction of the pixel coordinates of the pixel points constituting the upstream boundary line 2A of the reflected light area 2 and pixel positions Pd(k)q (q=1 to Rd, where R d is the number of pixel points constituting the downstream boundary line 2B of the reflected light area 2), the moving distance Mu(k)p (=Pu(k)p-Pu(k-1)p) in the rolling direction of the pixel point on the upstream boundary line 2A is calculated from the difference between the pixel position Pu(k-1)p of image number (k-1) and the pixel position Pu(k)p of image number (k), and the moving distance Md(k)q (=Pd(k)q-Pd(k-1)q) in the rolling direction of the pixel point on the downstream boundary line 2B is calculated from the difference between the pixel position Pd(k-1)q of image number (k-1) and the pixel position Pd(k)q of image number (k), and the reflected light area 2 is moved in the plate width direction by j A divided divided area (i) (i = 1 to j) is formed, and when the (k)th image is captured, for pixel points present within the divided area (i), an average movement distance Mu(k)i of the movement distance Mu(k)p of the pixel points on the upstream boundary line 2A and an average movement distance Md(k)i of the movement distance Md(k)q of the pixel points on the downstream boundary line 2B are calculated, and a time Ts between the image acquisition time of image number (k-1) and the image acquisition time of image number (k) is calculated, and an average movement speed Vu(k)i of the pixel points on the upstream boundary line 2A is calculated from the time Ts and the average movement distance Mu(k)i for each divided area (i), and For each divided area (i), the average moving speed Vd(k)i of the pixel points on the downstream boundary line 2B is calculated from the time Ts and the average moving distance Md(k)i, and for each divided area (i), the number of positive and negative sign inversions Nu(k)i of the average moving speed Vu(k)i of the pixel points on the upstream boundary line 2A and the number of positive and negative sign inversions Nd(k)i of the average moving speed Vd(k)i of the pixel points on the downstream boundary line 2B between the acquisition of the (k-F+1)th image and the (k)th image is calculated, and the time Tf between the image acquisition time of image number (k-F+1) and image number (k) is calculated, and for each divided area (i),The average fluctuation frequency Qu(k)i (=[Nu(k)i / Tf] / 2) of the pixel points constituting the upstream boundary line 2A is calculated from the time Tf and the number of sign reversals Nu(k)i, and the average fluctuation frequency Qd(k)i (=[Nd(k)i / Tf] / 2) of the pixel points constituting the downstream boundary line 2B is calculated for each divided area (i) from the time Tf and the number of sign reversals Nd(k)i. The average value of the two average fluctuation frequencies Qu(k)i and Qd(k)i is calculated for each divided area (i), and the obtained average value is used as the average frequency of the pixel points constituting the upstream boundary line 2A and the pixel points constituting the downstream boundary line 2B in the reflected light area 2 of the (k)th image. The information corresponding to the two average fluctuation frequencies of the pixel points is Q(k)i (=[Qu(k)i+Qd(k)i] / 2), the value of the information Q(k)i is made to correspond to the central position in the width direction of the divided area (i), and the value indicating the position in the width direction is made a variable (x). The position in the width direction within the width range of the reflected light area 2 in the image is normalized to the range of -1≦x≦1, and the j values ​​of Q(k)i are made into an index corresponding to the distribution of elongation of the rolled strip in the width direction obtained from the (k)th image. The notation of the position in the width direction is changed to (x), and Q(k)i=E(xi). E(x)=C0'+C1'×x+C2'×(2x, 2 -1)+C4'×(8x 4 -8x 2 The coefficients (C0', C1', C2', C4') of the Chebyshev polynomial are determined from E(xi) with j x values ​​(xi) by fitting the (k)th image to a Chebyshev polynomial with x=0, +1) (where -1≦x≦1), and the coefficients (C0', C1', C2', C4') of the Chebyshev polynomial are determined from E(xi) with j x values ​​(xi). The coefficient (C1') of the first-order term is then transmitted as a detection result signal for the distribution of elongation of the rolled sheet for the first-order component in the sheet width direction of the (k)th image.

[0086] This makes it possible to evaluate with high accuracy the change in sheet elongation distribution, which could not be addressed by the above-mentioned Patent Document 1.

[0087] In addition, the image processing computer 80 further transmits at least one of the first-order coefficient (C1'), the second-order coefficient (C2') and the fourth-order coefficient (C4') as a detection result signal of the first-order component, second-order component or fourth-order component of the rolled sheet elongation distribution in the sheet width direction, thereby becoming able to respond to more changes in the sheet shape.

[0088] <Other> The present invention is not limited to the above-mentioned embodiment, and various modifications and applications are possible. The above-mentioned embodiment has been described in detail to explain the present invention in an easily understandable manner, and the present invention is not necessarily limited to having all of the described configurations. [Explanation of symbols]

[0089] 1...Metal strip 2...Reflected light area 2A…Upstream boundary of reflected light area 2B: downstream boundary of reflected light area 10…F1 Stand 11, 21, 31, 41, 51...Pressure cylinder 12, 22, 32, 42, 52...Load detector 20…F2 Stand 30…F3 Stand 40…F4 Stand 50…F5 Stand 61, 62, 63, 64…Camera 71, 72, 73, 74…Looper 80...Image processing computer (image processing section) 81…Database 82...Control device 85…Monitor 90…Communication line 100...Rolling equipment

Claims

1. In the rolling equipment, a camera is installed so as to capture an image including an area in which a strip-shaped area where illumination light is reflected transversely in the strip width direction, called a reflected light area, can be confirmed on the surface of the metal strip lifted by a looper; and an image processing unit that detects a plate shape of the metal band plate based on the image captured by the camera. The image processing unit includes: The images are numbered in the order of acquisition: 1, 2, 3, ..., k, ... In the (k)th image, pixel positions Pu(k)p (p=1 to Ru, where Ru is the number of pixel points constituting the upstream boundary line of the reflected light region) in the rolling direction of pixel points constituting the downstream boundary line of the reflected light region and pixel positions Pd(k)q (q=1 to Rd, where Rd is the number of pixel points constituting the downstream boundary line of the reflected light region) in the rolling direction of pixel points constituting the downstream boundary line of the reflected light region are obtained; A moving distance Mu(k)p in the rolling direction of the pixel point on the upstream boundary line is calculated from a difference between a pixel position Pu(k-1)p of the image number (k-1) and a pixel position Pu(k)p of the image number (k); A moving distance Md(k)q in the rolling direction of the pixel point on the downstream boundary line is calculated from a difference between a pixel position Pd(k−1)q of the image number (k−1) and a pixel position Pd(k)q of the image number (k); The reflection light region is divided into j divided regions (i) (i = 1 to j) in the plate width direction, When capturing the (k)th image, for pixel points present within the range of the divided area (i), an average movement distance Mu(k)i of the movement distance Mu(k)p of the pixel points on the upstream boundary line and an average movement distance Md(k)i of the movement distance Md(k)q of the pixel points on the downstream boundary line are calculated; Calculate the time Ts between the image capture times of image numbers (k-1) and (k); For each divided area (i), an average moving speed Vu(k)i of pixel points on the upstream boundary line is calculated from the time Ts and the average moving distance Mu(k)i; For each divided area (i), an average moving speed Vd(k)i of pixel points on the downstream boundary line is calculated from the time Ts and the average moving distance Md(k)i; For each divided area (i), a number Nu(k)i of positive and negative sign inversions of an average moving speed Vu(k)i of pixel points on the upstream boundary line and a number Nd(k)i of positive and negative sign inversions of an average moving speed Vd(k)i of pixel points on the downstream boundary line are calculated during acquisition of the (k-F+1)th image to the (k)th image; Calculate the time Tf between the image acquisition time of image number (k-F+1) and image number (k), For each divided area (i), an average fluctuation frequency Qu(k)i of pixel points constituting the upstream boundary line is calculated from the time Tf and the number of sign inversions Nu(k)i; For each divided area (i), an average fluctuation frequency Qd(k)i of pixel points constituting the downstream boundary line is calculated from the time Tf and the number of sign inversions Nd(k)i; an average value of the two average fluctuation frequencies Qu(k)i and Qd(k)i is calculated for each divided area (i), the obtained average value is regarded as information Q(k)i corresponding to the two average fluctuation frequencies of the pixel points constituting the upstream boundary line and the pixel points constituting the downstream boundary line of the reflected light region of the (k)th image, and the value of the information Q(k)i is made to correspond to the central position in the sheet width direction of the divided area (i); When a value indicating the position in the sheet width direction is a variable (x), the position in the sheet width direction within the sheet width range of the reflected light region in the image is normalized to the range of -1≦x≦1, and the value of the j pieces of information Q(k)i is used as an index corresponding to the rolled sheet elongation distribution in the sheet width direction obtained from the (k)th image, and the notation of the sheet width direction position is changed to (x), and Q(k)i=E(xi), which consists only of the 0th, 1st, 2nd, and 4th order terms of x. E(x) = C ０ '+C １ '×x+C ２ '×(2x ２ -1) + C ４ '×(8x ４ -8x ２ +1) (where -1≦x≦1) and fitting it to the Chebyshev polynomial, from E(xi) with j x values ​​(xi), The coefficients of the Chebyshev polynomial (C ０ ', C １ ', C ２ ', C ４ ') and calculate the coefficient of the first-order term (C １ ') is transmitted as a detection result signal of the rolled strip elongation distribution of the first-order component in the strip width direction of the (k)th image. Here, xi is the center position in the sheet width direction of the divided area (i) obtained by dividing the reflection light area into j parts in the sheet width direction, expressed as (x). Note that F, i, j, and k are integers. Metal strip shape detection device.

2. The plate shape detection device for a metal strip according to claim 1, The image processing unit further transmits at least one of the coefficients of the second-order term (C2') or the coefficients of the fourth-order term (C4') as a detection result signal of the rolled sheet elongation distribution of the second-order component or the fourth-order component in the sheet width direction. Metal strip shape detection device.

3. The metal strip shape detection device according to claim 1 or 2, A rolling mill equipped with a control device, The control device transmits one or more operation signals related to the leveling amount, bending force, or pair cross angle of the rolling mill based on the detection result signal. Rolling machine.

4. a photographing step of photographing an image including a range in which a strip-shaped area where illumination light is reflected transversely in the strip width direction, called a reflected light area, can be confirmed on the surface of the metal strip lifted by the looper in the rolling equipment; and an image processing step of detecting a shape of the metal band based on the image captured in the photographing step, In the image processing step, The images are numbered in the order of acquisition: 1, 2, 3, ..., k, ... In the (k)th image, pixel positions Pu(k)p (p=1 to Ru, where Ru is the number of pixel points constituting the upstream boundary line of the reflected light region) in the rolling direction of pixel points constituting the downstream boundary line of the reflected light region and pixel positions Pd(k)q (q=1 to Rd, where Rd is the number of pixel points constituting the downstream boundary line of the reflected light region) in the rolling direction of pixel points constituting the downstream boundary line of the reflected light region are obtained; A moving distance Mu(k)p in the rolling direction of the pixel point on the upstream boundary line is calculated from a difference between a pixel position Pu(k-1)p of the image number (k-1) and a pixel position Pu(k)p of the image number (k); A moving distance Md(k)q in the rolling direction of the pixel point on the downstream boundary line is calculated from a difference between a pixel position Pd(k−1)q of the image number (k−1) and a pixel position Pd(k)q of the image number (k); The reflection light region is divided into j divided regions (i) (i = 1 to j) in the plate width direction, When capturing the (k)th image, for pixel points present within the range of the divided area (i), an average movement distance Mu(k)i of the movement distance Mu(k)p of the pixel points on the upstream boundary line and an average movement distance Md(k)i of the movement distance Md(k)q of the pixel points on the downstream boundary line are calculated; Calculate the time Ts between the image capture times of image numbers (k-1) and (k); For each divided area (i), an average moving speed Vu(k)i of pixel points on the upstream boundary line is calculated from the time Ts and the average moving distance Mu(k)i; For each divided area (i), an average moving speed Vd(k)i of pixel points on the downstream boundary line is calculated from the time Ts and the average moving distance Md(k)i; For each divided area (i), a number Nu(k)i of positive and negative sign inversions of an average moving speed Vu(k)i of pixel points on the upstream boundary line and a number Nd(k)i of positive and negative sign inversions of an average moving speed Vd(k)i of pixel points on the downstream boundary line are calculated during acquisition of the (k-F+1)th image to the (k)th image; Calculate the time Tf between the image acquisition time of image number (k-F+1) and image number (k), For each divided area (i), an average fluctuation frequency Qu(k)i of pixel points constituting the upstream boundary line is calculated from the time Tf and the number of sign inversions Nu(k)i; For each divided area (i), an average fluctuation frequency Qd(k)i of pixel points constituting the downstream boundary line is calculated from the time Tf and the number of sign inversions Nd(k)i; an average value of the two average fluctuation frequencies Qu(k)i and Qd(k)i is calculated for each divided area (i), the obtained average value is regarded as information Q(k)i corresponding to the two average fluctuation frequencies of the pixel points constituting the upstream boundary line and the pixel points constituting the downstream boundary line of the reflected light region of the (k)th image, and the value of the information Q(k)i is made to correspond to the central position in the sheet width direction of the divided area (i); When a value indicating the position in the sheet width direction is a variable (x), the position in the sheet width direction within the sheet width range of the reflected light region in the image is normalized to the range of -1≦x≦1, and the value of the j pieces of information Q(k)i is used as an index corresponding to the rolled sheet elongation distribution in the sheet width direction obtained from the (k)th image, and the notation of the sheet width direction position is changed to (x), and Q(k)i=E(xi), which consists only of the 0th, 1st, 2nd, and 4th order terms of x. E(x) = C ０ '+C １ '×x+C ２ '×(2x ２ -1) + C ４ '×(8x ４ -8x ２ +1) (where -1≦x≦1) and fitting it to the Chebyshev polynomial, from E(xi) with j x values ​​(xi), The coefficients of the Chebyshev polynomial (C ０ ', C １ ', C ２ ', C ４ ') and calculate the coefficient of the first-order term (C １ ') is transmitted as a detection result signal of the rolled strip elongation distribution of the first-order component in the strip width direction of the (k)th image. Here, xi is the center position in the sheet width direction of the divided area (i) obtained by dividing the reflection light area into j parts in the sheet width direction, expressed as (x). Note that F, i, j, and k are integers. A method for detecting the shape of a metal strip.

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