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 reflected light area is divided into j divided zones in the sheet width direction, and the upstream-most and downstream-most positions of the upstream boundary line position and the upstream-most and downstream-most positions of the downstream boundary line position of the reflected light area are obtained. For each of the acquired images, the difference between the fluctuation width of the upstream-most boundary line position and the fluctuation width of the downstream-most boundary line position is calculated for each divided zone. This is regarded as information corresponding to the maximum fluctuation amplitude of the reflected light area in the (k)th image and corresponds to the central position in the sheet width direction of divided zone i. When a value indicating the position in the sheet width direction is designated as a variable x, the sheet width direction position within the sheet width range of the area in the image is normalized to the range of -1≦x≦1. The value of the information 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 coefficients are determined by fitting the information to a Chebyshev polynomial. The coefficient C1' of the first-order term is transmitted as a detection result signal of the rolled sheet elongation distribution of the first-order component in the sheet 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 plurality 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 an area in which a strip-shaped area, called a reflected light area, transverse to the strip width direction where illumination light is reflected 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 detecting the strip shape of the metal strip based on the images captured by the camera in the order of the acquired images 1, 2, 3, . . . , k,In the (k)th image, within each divided area (i) (i = 1 to j) into which the reflected light area is divided into j areas in the sheet width direction, in the rolling direction of pixel coordinates, the most upstream position Pumin(k)i among pixel positions constituting the upstream boundary line of the reflected light area, the most downstream position Pumax(k)i among pixel positions constituting the upstream boundary line of the reflected light area, the most upstream position Pdmin(k)i among pixel positions constituting the downstream boundary line of the reflected light area, and the most downstream position Pdmin(k)i among pixel positions constituting the downstream boundary line of the reflected light area are The position Pdmax(k)i is calculated, and for each of the F images from image number (k-F+1) to image number (k), which are two or more images acquired, data indicating the most upstream position is extracted from the F pieces of data from Pumin(k-F+1)i to Pumin(k)i as first position data, and this is reset as Pure_min(k)i as the data of the (k)th image, and data indicating the most downstream position is extracted from the F pieces of data from Pumax(k-F+1)i to Pumax(k)i as second position data, and this is reset as the data of the (k)th image. The data representing the most upstream position is extracted from the F pieces of data from Pdmin(k-F+1)i to Pdmin(k)i as the third position data, and this is reset as Pdre_min(k)i as the data of the (k)th image. The data representing the most downstream position is extracted from the F pieces of data from Pdmax(k-F+1)i to Pdmax(k)i as the fourth position data, and this is reset as Pdre_max(k)i as the data of the (k)th image. The difference in the position data in the rolling direction [ The average value of [Pure_max(k)i-Pure_min(k)i] and [Pdre_max(k)i-Pdre_min(k)i] is calculated for each divided area (i), the average value is set as information A(k)i corresponding to the maximum fluctuation amplitude of the upstream boundary position and the downstream boundary position of the reflected light area in the (k)th image, the value of the information A(k)i is made to correspond to the central position in the width direction of the divided area (i), and a value indicating the width direction position is set as a variable (x), and the width direction position within the width range of the reflected light area in the image is normalized to the range of -1≦x≦1,j pcs The above The value of the information A(k)i is used as an index corresponding to the distribution of elongation in the strip width direction obtained from the (k)th image, and the notation of the strip width direction position is changed to (x), so that A(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 distribution of elongation of the rolled strip 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. 1 is a diagram showing an example of the relationship between the Chebyshev coefficient first-order component (C1') and the leveling amount using "index A" obtained by the conventional technology. [Figure 7] FIG. 13 is a graph showing an example of the relationship between the Chebyshev coefficient first-order component (C1') and the leveling amount, using the "index B" obtained by the present invention. [Figure 8] FIG. 13 is a diagram showing an example of how to calculate the average value "A(k)i" of the maximum fluctuation amplitude in the rolling direction of the reflected light region from the (k)th image, taking into account fluctuations of the upstream boundary line and downstream boundary line of the reflected light region in the plate shape detection device for a metal strip plate of an embodiment. [Figure 9] 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 10] 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 11] 4 is a part of a flowchart for detecting a plate shape in the plate shape detection device for a metal strip plate according to the embodiment. [Figure 12] 4 is a part of a flowchart for detecting a plate shape in the plate shape detection device for a metal strip plate according to the embodiment. [Figure 13] 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. 13. 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] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] Here, in the reflected light region 2 in which a band-like reflected light is seen transversely to the width direction of the metal band 1, if the distribution of elongation in the rolling direction (longitudinal direction of the band) at each position in the width direction of the metal band 1 is uniform, the surface of the metal band 1 is flat, the shape is good, and the steepness in the width direction is similar and small, so that the distribution difference in the length in the rolling direction of the reflected light region 2 at each position in the width direction is small, as shown in Fig. 2. For this reason, the boundary of the reflected light region 2 by illumination is such that the distance between the upstream boundary line 2A and the downstream boundary line 2B is roughly uniform and roughly parallel in the width direction, and parameters such as the area value of each zone and the average length in the rolling direction when the reflected light region 2 is equally divided into a plurality of zones in the width direction are roughly uniform in all zones.

[0033] In contrast, if 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 strip shape is poor, and due to the difference in steepness in the strip width direction, the area reflected on the strip surface by the reflected light differs, and as shown in Figure 3, the boundary line of the reflected light area 2 caused by illumination is wavy at either the upstream boundary line 2A or the downstream boundary line 2B, or both, and the distance between the upstream boundary line 2A and the downstream boundary line 2B of the reflected light area 2 becomes non-uniform in the strip width direction. For this reason, when the reflected light area 2 is equally divided into a plurality of zones in the strip width direction, parameters such as the area value of each zone, the average length in the rolling direction, etc. become non-uniform in each zone.

[0034] 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 is performed using the Chebyshev polynomial of the following equation (1).

[0035] 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.

[0036] The leveling amount is defined as follows.

[0037] 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).

[0038] 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 working side (WS) becomes thinner, and the plate elongation on the working side (WS) becomes larger. When the value (C1') of the first-order component of the Chebyshev coefficient obtained by this method is positive, it indicates that the plate elongation on the working side (WS) is large, and when it is negative, it indicates that the plate elongation on the drive side (DS) is large.

[0039] The reflected light region 2 is divided into a specific number in the sheet width direction, and for example, the rolling direction length of the reflected light region 2, which is used as an index of the sheet elongation distribution in the sheet width direction in each divided region, is averaged within the divided region, and this averaged value is set as the Chebyshev polynomial E(x) which is assumed to represent a magnitude corresponding to the sheet elongation distribution in the sheet width direction. The E(x) obtained here is referred to as "index A", and this Chebyshev coefficient is assumed to have been obtained by conventional technology.

[0040] In a situation where the leveling amount of the rolling mill is intentionally changed during actual hot rolling, and the first-order component (C1'), which is the coefficient of the Chebyshev polynomial, is considered to change obviously, the relationship between the leveling amount and the Chebyshev coefficient first-order component (C1') to which the index A obtained by the index extraction method of the conventional technology is applied is shown in FIG. 6.

[0041] As shown in FIG. 6, it can be confirmed that there is almost no correlation between the change in the leveling amount and the first-order component of the Chebyshev coefficient (C1') obtained by index A.

[0042] Therefore, it was presumed that there might be cases where the actual change in plate shape could not be measured using the extraction method in which the length in the rolling direction in each divided area of ​​the reflected light region 2 was averaged to obtain index A. As a result, the inventors considered that there might be room for improvement in the method for selecting the index.

[0043] Vibrations of the metal strip 1 are observed at the positions of the loopers 71, 72, 73, and 74. It was inferred that by averaging the fluctuation data such as the position, length in the rolling direction, and area of ​​the reflected light area 2 reflected on the surface of the metal strip being rolled, the obtained Chebyshev coefficients are smoothed, and it becomes difficult to clearly obtain a correlation between the change in the leveling amount and the first-order component of the Chebyshev coefficient (C1') to which index A is applied.

[0044] In other words, the vibration of the metal strip 1 is affected by the strip elongation caused by rolling, and we thought that by extracting this effect, we could reflect the distribution of strip elongation caused by rolling in the Chebyshev coefficients. After extensive research, we devised a new method for extracting an index as follows. This new index obtained in the present invention is called "Index B".

[0045] Similarly, in the case where the leveling amount of the rolling mill is intentionally changed during actual hot rolling, and the first-order component (C1'), which is the coefficient of the Chebyshev polynomial, is considered to change, the relationship between the first-order component (C1') of the Chebyshev coefficient obtained by this embodiment and the leveling amount is shown in FIG. 7.

[0046] As shown in Fig. 7, it can be confirmed that there is a certain degree of correlation between the change in the leveling amount and the change in the Chebyshev coefficient first-order component (C1') obtained by the processing of this embodiment described above. In other words, it is considered that the method for extracting index B was able to extract the effect of sheet elongation due to rolling.

[0047] Therefore, when applying the distribution in the strip width direction of the maximum length in the rolling direction 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, 74 installed between the rolling mill stands of the rolling line to the Chebyshev polynomial to judge the distribution of strip elongation due to rolling in the strip width direction, it is found to be good to adopt the index B obtained by the processing of this embodiment. The method of extracting the index B will be described below.

[0048] In the image processing computer 80 in this embodiment, the following two analytical processes are carried out for each of the acquired images using the acquired images.

[0049] The first analysis process performed by the image processing computer 80 numbers the images in the order of acquisition as 1, 2, 3, . . . , k, . . . and in the (k)th image, within each divided area (i) (i = 1 to j) obtained by dividing the reflected light area 2 into j areas in the sheet width direction, calculates the rolling direction position Pumin(k)i of the pixel constituting the upstream boundary line 2A of the reflected light area 2 that is the most upstream in the rolling direction, calculates the rolling direction position Pumax(k)i of the pixel constituting the upstream boundary line 2A of the reflected light area 2 that is the most downstream in the rolling direction, calculates the rolling direction position Pdmin(k)i of the pixel constituting the downstream boundary line 2B of the reflected light area 2 that is the most upstream in the rolling direction, and calculates the rolling direction position Pdmax(k)i of the pixel constituting the downstream boundary line 2B of the reflected light area 2 that is the most downstream in the rolling direction. This data is stored in the database 81.

[0050] The second analysis process performed by the image processing computer 80 is to extract, for each of the F images from image number (k-F+1) to image number (k) stored in the database 81, first position data that is the most upstream position in the rolling direction within the division area (i) from the F pieces of data from Pumin(k-F+1)i to Pumin(k)i, and set this as the (k)th image data Pure_min(k)i. Also, from the F pieces of data from Pumax(k-F+1)i to Pumax(k)i, second position data that is the most downstream position in the rolling direction within the division area (i) is extracted, and set this as the (k)th image data Pure_min(k)i. The data for the (k)th image is designated as Pure_max(k)i, and third position data which is the most upstream position in the rolling direction within the division area (i) is extracted from the F pieces of data from Pdmin(k-F+1)i to Pdmin(k)i and this is designated as Pdre_min(k)i, and fourth position data which is the most downstream position in the rolling direction within the division area (i) is extracted from the F pieces of data from Pdmax(k-F+1)i to Pdmax(k)i and this is designated as Pdre_max(k)i, and these are stored in the database 81.

[0051] Furthermore, the image processing computer 80 calculates the difference [Pure_max(k)i-Pure_min(k)i] in the position data in the rolling direction of the upstream boundary line 2A in the (k)th image for each divided area (i) and obtains the obtained j values ​​of [Pure_max(k)i-Pure_min(k)i] as the maximum fluctuation amplitude "Au(k)i" of the upstream boundary line 2A in the (k)th image, and calculates the difference [Pdre_max(k)i-Pdre_min(k)i] in the position data in the rolling direction of the downstream boundary line 2B in the (k)th image for each divided area (i) and obtains the obtained j values ​​of [Pure_max(k)i-Pure_min(k)i] as the maximum fluctuation amplitude "Ad(k)i" of the downstream boundary line 2B in the (k)th image. Thereafter, the average value of the maximum fluctuation amplitudes "Au(k)i" and "Ad(k)i" in the rolling direction of the upstream boundary line 2A and the downstream boundary line 2B is calculated for each divided area (i) and expressed as A(k)i. A(k)i is set as the index B of the (k)th image (the average maximum fluctuation amplitude in the divided area (i) of the upstream boundary line 2A and the downstream boundary line 2B of the reflected light region 2). The value of A(k)i is made to correspond to the central position in the strip width direction of the divided area (i) and the value indicating the strip width direction position is set as the variable (x). A(k)i corresponding to the position x normalized to the range of -1≦x≦1 within the strip width range is set as E(xi) of the (k)th image. Note that xi indicates the central position in the strip width direction of the divided area (i) in the strip width direction in the (x) notation.

[0052] FIG. 8 is an image diagram showing the maximum fluctuation amplitudes in the rolling direction, “Au(k)i” and “Ad(k)i”, of the boundary between the upstream and downstream sides of the reflected light area 2 in the (k)th image before the averaged maximum fluctuation amplitude, “A(k)i”, is calculated. The average of these two values ​​is A(k)i (A(k)i=[Au(k)i+Ad(k)i] / 2).

[0053] The image processing computer 80 fits the center position xi in the sheet width direction of each divided area (i) of the (k)th image and the value of E(xi) (E(xi) = A(k)i) to the Chebyshev polynomial of equation (1) for each divided area (i), determines the coefficients (C0', C1', C2', C4') of the Chebyshev polynomial from the equation of the approximation curve using the least squares method, and transmits the first-order coefficient (C1') as a detection result signal of the rolled sheet elongation distribution of the first-order component in the sheet width direction.

[0054] Preferably, the image processing computer 80 can further transmit, in addition to the first-order coefficient (C1'), one or more of the second-order coefficient (C2') or the fourth-order coefficient (C4') 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.

[0055] The database 81 also functions as a recording medium in which various parameters used when operating the rolling equipment 100 are recorded.

[0056] In this embodiment, when k≧F, where k and F are integers, the database 81 can store first position data Pure_min(k)i, second position data Pure_max(k)i, third position data Pdre_min(k)i, and fourth position data Pdre_max(k)i (where i=1 to j, respectively) in the rolling direction for each of the F images acquired consecutively from the (k-F+1)th image to the (k)th image, and for each of the sections (i) obtained by dividing the reflected light area 2 reflected on the surface of the metal strip into j sections in the strip width direction.

[0057] Regarding the 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 areas as shown in FIG. 9, or each of the j areas may be unequally divided into any width as shown in FIG. 10.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 .

[0063] 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.

[0064] 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.

[0065] Next, the flow of the plate shape detection device and detection method for the rolled metal strip 1 according to the present invention will be described with reference to Figures 11 and 12. Figures 11 and 12 show a flow chart of the index calculation method according to the present invention.

[0066] As shown in FIG. 11, before the start of rolling or during rolling, the image processing computer 80 sets the number of images F (e.g., F=20) for judging the maximum fluctuation amplitude 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.

[0067] Thereafter, the image processing computer 80 acquires surface images (image number 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, taken by the cameras 61, 62, 63, 64 (step S203). Here, the acquired images are numbered 1, 2, 3, . . . , k, . . . in the order of acquisition.

[0068] Next, the image processing computer 80 processes the images (image number 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).

[0069] 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.

[0070] Next, the image processing computer 80 divides the reflected light region 2 extracted from the image (k) captured by the cameras 61, 62, 63, and 64 into j (for example, j=7) in the plate width direction (step S205).

[0071] Next, within the range of each divided area (i) (i = 1 to j) of the reflected light area 2 extracted from the images (image number k) captured by the cameras 61, 62, 63, 64, the image processing computer 80 selects the pixel with the most upstream rolling direction position among the positions of the pixels constituting the upstream boundary line 2A of the reflected light area 2, sets the rolling direction pixel position as "Pumin(k)i", selects the pixel with the most downstream rolling direction position among the positions of the pixels constituting the upstream boundary line 2A of the reflected light area 2, sets the rolling direction pixel position as "Pumax(k)i", and preferably stores those positions in the database 81 (step S206). At the same time, within the range of each divided area (i) (i = 1 to j) of the reflected light area 2, the image processing computer 80 selects the pixel with the most upstream rolling direction position among the positions of the pixels constituting the downstream boundary line 2B of the reflected light area 2, sets the rolling direction pixel position as "Pdmin(k)i", selects the pixel with the most downstream rolling direction position among the pixel positions of the downstream boundary line 2B of the reflected light area 2, sets the rolling direction pixel position as "Pdmax(k)i", and preferably stores those positions in the database 81 (step S207). These steps S206 and S207 can be in any order, and they may be processed in parallel, or step S207 may be processed prior to step S206.

[0072] Furthermore, the image processing computer 80 determines whether the image number k < F (step S208). When it is determined that the image number k < F, the process proceeds to step S209, where the image number k is updated (k = k + 1) (step S209), and the process proceeds to step S203, where it waits for the processing of a predetermined number of images to be completed. In contrast, when it is determined in step S208 that the image number k ≧ F, the process proceeds to step S210.

[0073] Next, for each divided area (i) of the reflected light region 2, the image processing computer 80 compares "Pumin(k)i" and "Pumax(k)i" stored in the above step S206 among the images of F from image number (k-F+1) to image number (k), and re-extracts the pixel position indicating the most upstream position and stores it preferably in the database 81 as "Pure_min(k)i" (step S210), and also re-extracts the pixel position indicating the most downstream position and stores it preferably in the database 81 as "Pure_max(k)i" (step S211).

[0074] Similarly, as shown in FIG. 12, the image processing computer 80 compares "Pdmin(k)i" and "Pdmax(k)i" stored in step S207 above among F images from image number (k-F+1) to image number (k), and re-extracts the pixel position indicating the most upstream position and stores it preferably in database 81 as "Pdre_min(k)i" (step S212), and also re-extracts the pixel position indicating the most downstream position and stores it preferably in database 81 as "Pdre_max(k)i" (step S213).

[0075] Here, since the rolling direction position of pixel coordinates in the image increases from the upstream side to the downstream side, in the divided area (i), the most upstream position among the upstream boundary positions is expressed as "Pure_min(k)i", the most downstream position among the upstream boundary positions is expressed as "Pure_max(k)i", the most upstream position among the downstream boundary positions is expressed as "Pdre_min(k)i", and the most downstream position among the downstream boundary positions is expressed as "Pdre_max(k)i".

[0076] Specifically, in the following Table 1 (example of resetting the first position data (Pure_min(k)i) and the second position data (Pure_max(k)i)) and Table 2 (example of resetting the third position data (Pdre_min(k)i) and the fourth position data (Pdre_max(k)i)), if the number of images is f, the upstream data and downstream data for each image are stored when the reflected light area 2 is divided into j areas from the (k-f+1)th image to the consecutive (k)th image. The database 81 shows that, in each area, the first position data and the second position data are reset from among f images, and the first position data is subtracted from the second position data to obtain Au(k)i=[Pure_max(k)i]-[Pure_min(k)i], and the third position data and the fourth position data are reset, and the third position data is subtracted from the fourth position data to obtain Ad(k)i=[Pdre_max(k)i]-[Pdre_min(k)i]. Furthermore, in the present invention, the average value A(k)i of Au(k)i and Ad(k)i (A(k)i=[Au(k)i+Ad(k)i] / 2) is set as the index B for the kth image. Note that the display in the table of Pure_min(k)i and the like is merely an example. In Table 1, Pumin in bold represents the data at the most upstream position among Pumin of the f images from the (k-f+1)th image to the (k)th image, Pumax in bold represents the data at the most downstream position among Pumax of the f images from the (k-f+1)th image to the (k)th image, Pdmin in bold in Table 2 represents the data at the most upstream position among Pdmin of the f images from the (k-f+1)th image to the (k)th image, and Pdmax in bold represents the data at the most downstream position among Pdmax of the f images from the (k-f+1)th image to the (k)th image.

[0077] [Table 1]

[0078] [Table 2]

[0079] For example, as shown in Table 1, the reflected light region 2 is divided into j regions in the sheet width direction, and in the first region of the divided region i=1, the pixel in the rolling direction that is the most upstream of the pixels constituting the upstream boundary line 2A of the reflected light region 2 is selected, and the rolling direction position is Pumin(k)1 in the kth image. In the f images to be evaluated, the pixel in the rolling direction is Pumin(1)1 in the (k-f+1)th image, Pumin(2)1 in the (k-f+2)th image, and Pumin(3)1 in the (k-f+3)th image. When the notation is changed to Pumin(3)1, ···, in the (-f+3)th image, and Pumin(f)1 in the kth image, if the most upstream position of Pumin(1 / ··· / f)1 in these f images is Pumin(1)1 in the (k-f+1)th image, then this most upstream rolling direction position Pumin(1)1 is reset to “Pure_min(k)1” as the rolling direction position indicating the most upstream at the time of image number k, and saved.

[0080] Similarly, in the first area of ​​the divided area i=1, the most downstream pixel in the rolling direction is selected from the positions of the pixels constituting the upstream boundary line 2A of the reflected light area 2, and the rolling direction position is set to Pumax(k)1 in the k-th image. However, in the f images to be evaluated, when the notation is changed to Pumax(1)1 in the (k-f+1)-th image, Pumax(2)1 in the (k-f+2)-th image, Pumax(3)1... in the (k-f+3)-th image, and Pumax(f)1 in the k-th image, if the most downstream position of Pumax(1 / ... / f)1 in these f images is Pumax(3)1 in the (k-f+3)-th image, then this most downstream rolling direction position, Pumax(3)1, is reset to "Pure_max(k)1" as the rolling direction position indicating the most downstream at the time of image number k, and saved.

[0081] Similarly, in the second section of the divided section i=2, the most upstream pixel in the rolling direction is selected from the positions of the pixels constituting the upstream boundary line 2A of the reflected light region 2, and the rolling direction position is designated as Pumin(k)2 in the kth image. However, in the f images to be evaluated, when the notation is changed to Pumin(1)2 in the (k-f+1)th image, Pumin(2)2 in the (k-f+2)th image, Pumin(3)2 in the (k-f+3)th image, ..., Pumin(f)2 in the kth image, the most upstream position of Pumin(1 / ... / f)2 in these f images is the (k-f+1)th image. When the most downstream position of the pixel position Pumax(1 / ··· / f)2 in the rolling direction that is the most downstream among the pixel positions constituting the upstream boundary line 2A of the reflected light area 2 is Pumax(2)2 in the (k-f+2)th image, this most downstream position Pumax(2)2 is reset to “Pure_max(k)2” as the rolling direction position indicating the most downstream at the time of image number k and saved.

[0082] As shown in Table 2, the reflected light region 2 is divided into j regions in the plate width direction, and in the first region of the divided region i=1, the most upstream pixel in the rolling direction is selected from the positions of the pixels constituting the downstream boundary line 2B of the reflected light region 2, and its rolling direction position is set to Pdmin(k)1 in the kth image. However, in the f images to be evaluated, when the notation is changed to Pdmin(1)1 in the (k-f+1)th image, Pdmin(2)1 in the (k-f+2)th image, Pdmin(3)1 in the (k-f+3)th image, ..., Pdmin(f)1 in the kth image, if the most upstream position of Pdmin(1 / ... / f)1 in these f images is Pdmin(f)1 in the (k)th image, then this most upstream rolling direction position Pdmin(f)1 is reset to "Pdre_min(k)1" as the rolling direction position indicating the most upstream at the time of image number k, and saved.

[0083] Similarly, in the first section of the divided section i=1, the most downstream pixel in the rolling direction is selected from the positions of the pixels constituting the downstream boundary line 2B of the reflected light region 2, and its rolling direction position is set to Pdmax(k)1 in the k-th image. However, in the f images to be evaluated, when the notation is changed to Pdmax(1)1 in the (k-f+1)th image, Pdmax(2)1 in the (k-f+2)th image, Pdmax(3)1... in the (k-f+3)th image, and Pdmax(f)1 in the k-th image, if the most downstream position of Pdmax(1 / ... / f)1 in these f images is Pdmax(2)1 in the (k-f+2)th image, then this most downstream rolling direction position Pdmax(2)1 is reset to "Pdre_max(k)1" as the rolling direction position indicating the most downstream at the time of image number k, and saved.

[0084] Similarly, in the second section of divided section i=2, the most upstream pixel in the rolling direction is selected from the positions of the pixels constituting the downstream boundary line 2B of the reflected light region 2, and the rolling direction position is designated as Pdmin(k)2 in the kth image. However, in the f images to be evaluated, when the notation is changed to Pdmin(1)2 in the (k-f+1)th image, Pdmin(2)2 in the (k-f+2)th image, Pdmin(3)2 in the (k-f+3)th image, ..., and Pdmin(f)2 in the kth image, the most upstream position of Pdmin(1 / ... / f)2 in these f images is the (k-f+3)th image. When the most downstream position of the most downstream pixel position Pdmax(1 / ··· / f)2 in the rolling direction among the positions of the pixels constituting the downstream boundary line 2B of the reflected light area 2 is Pdmax(3)2 in the (k-f+3)th image, this most downstream position Pdmax(3)2 is reset to “Pdre_max(k)2” as the rolling direction position indicating the most downstream at image number k and saved.

[0085] The resetting of "Pure_min(k)i", "Pure_max(k)i", "Pdre_min(k)i", and "Pdre_max(k)i" is performed from divided area i=1 to divided area i=j.

[0086] Next, the image processing computer 80 calculates the difference ([Pure_max(k)i]-[Pure_min(k)i]) between the most upstream pixel position "Pure_min(k)i" and the most downstream pixel position "Pure_max(k)i" in the divided area (i) re-extracted from the position of the upstream boundary line 2A of the reflected light area 2 at the time of the camera image (k) obtained in steps S210 and S211 above, and stores this as the maximum fluctuation amplitude "Au(k)i" of the position of the upstream boundary line 2A, preferably in the database 81 (step S214).

[0087] Similarly, the image processing computer 80 calculates the difference ([Pdre_max(k)i]-[Pdre_min(k)i]) between the most upstream pixel position "Pdre_min(k)i" and the most downstream pixel position "Pdre_max(k)i" in the divided area (i) re-extracted from the position of the downstream boundary line 2B of the reflected light area 2 at the time of the camera image (k) obtained in steps S212 and S213 above, and stores this as the maximum fluctuation amplitude "Ad(k)i" of the position of the downstream boundary line 2B, preferably in the database 81 (step S215).

[0088] Next, the image processing computer 80 calculates the average value "A(k)i=[Au(k)i+Ad(k)i] / 2" of the maximum fluctuation amplitude "Au(k)i" of the upstream boundary line 2A and the maximum fluctuation amplitude "Ad(k)i" of the downstream boundary line 2B of the reflected light area 2 in each divided area (i) obtained at the time of the camera image (k) in the above steps S214 and S216 (step S216).

[0089] Next, the image processing computer 80 assigns the average value "A(k)i" of the maximum fluctuation amplitude of the two boundary lines (2A, 2B) on the upstream and downstream sides in each divided area (i) when the reflected light area 2 is divided in the width direction to the central position in the width direction of each divided area (i), re-expresses the central position in the width direction of each divided area (i) as (x), assigns the average value "A(k)i" of the maximum fluctuation amplitude of the two boundary lines (2A, 2B) on the upstream and downstream sides 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 central position in the width direction of the divided area (i) as (xi), curve fits E(xi) expressed as (x) to the Chebyshev polynomial of equation (1) as E(xi)=A(k)i, and calculates the Chebyshev coefficients (C0', C1', C2', C4') from the obtained approximation equation (step S217).

[0090] Next, the image processing computer 80 transmits the Chebyshev coefficients (C1', C2', C4') determined in step S217 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).

[0091] 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 S209 in Fig. 11 to continue the plate shape detection process. On the other hand, if it is judged that the rolling is completed, the process ends.

[0092] 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.

[0093] 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.

[0094] Preferably, the image processing computer 80 calculates the zeroth component [C0'], the first component [C1'×x], the second component [C2'×(2x 2 -1)], 4th order component [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.

[0095] Fig. 13 is a diagram showing an example of the display screen of the monitor 85. Fig. 13 shows an example of the distribution display of each of the 0th, 1st, 2nd and 4th order components 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. 13 and perform operations to correct, for example, the leveling, bending force, pair cross angle (in the case of a pair cross rolling mill), etc.

[0096] Among the Chebyshev polynomial coefficients in equation (1), the coefficient (C1') of the first-order component 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.

[0097] The coefficient (C2') of the second-order component among the Chebyshev polynomial coefficients in equation (1) indicates the 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).

[0098] The coefficient (C4') of the fourth-order component among the Chebyshev polynomial coefficients in equation (1) 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.

[0099] Next, the effects of this embodiment will be described.

[0100] In the plate shape detection device for the metal strip 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, within each of the divided regions (i) (i = 1 to j) into which the reflected light region 2 is divided in the plate width direction, the image processing computer 80 calculates the following in the rolling direction of the pixel coordinates: the most upstream position Pumin(k)i among the pixel positions constituting the upstream boundary line 2A of the reflected light region 2, the most downstream position Pumax(k)i among the pixel positions constituting the upstream boundary line 2A of the reflected light region 2, the most downstream position Pumax(k)i among the pixel positions constituting the upstream boundary line 2A of the reflected light region 2, the most downstream position Pumax(k)i among the pixel positions constituting the downstream boundary line 2A of the reflected light region 2, the most upstream position Pumax(k)i among the pixel positions constituting the upstream boundary line 2A of the reflected light region 2, the most downstream position Pumax(k)i among the pixel positions constituting the downstream ... The most upstream position Pdmin(k)i among the pixel positions constituting the line 2B and the most downstream position Pdmax(k)i among the pixel positions constituting the boundary line 2B on the downstream side of the reflected light region 2 are obtained, and for each of the F images from image number (k-F+1) to image number (k), which are two or more images acquired, data indicating the most upstream position is extracted from the F data from Pumin(k-F+1)i to Pumin(k)i as the first position data, and this is reset as the data of the (k)th image as Pure_min(k)i, and Pumax(k-F+1)i to P The data indicating the most downstream position is extracted from the F pieces of data from umax(k)i as the second position data, and this is reset as the data of the (k)th image to Pure_max(k)i. The data indicating the most upstream position is extracted from the F pieces of data from Pdmin(k-F+1)i to Pdmin(k)i as the third position data, and this is reset as the data of the (k)th image to Pdre_min(k)i. The data indicating the most downstream position is extracted from the F pieces of data from Pdmax(k-F+1)i to Pdmax(k)i as the third position data. The fourth position data is extracted, and this is reset as Pdre_max(k)i as the data of the (k)th image. The average value of the differences in the position data in the rolling direction [Pure_max(k)i - Pure_min(k)i] and [Pdre_max(k)i - Pdre_min(k)i] is calculated for each divided area (i). This value is set as information A(k)i corresponding to the average maximum fluctuation amplitude of the position of the upstream boundary 2A and the position of the downstream boundary 2B of the reflected light area 2 in the (k)th image, and corresponds to the central position in the strip width direction of the divided area (i). When the value indicating the strip width direction position is set as a variable (x),The position in the strip width direction within the strip width range of the reflected light area 2 in the image is normalized to the range of -1≦x≦1, and the average maximum amplitude A(k)i=([Pure_max(k)i-Pure_min(k)i]+[Pdre_max(k)i-Pdre_min(k)i]) / 2 of the boundary line between the upstream and downstream sides of the reflected light area 2 is used as an index corresponding to the rolled strip elongation distribution in the strip width direction obtained from the (k)th image, and the notation of the strip width direction position is changed to (x), and A(k)i=E(xi). Equation (1) consisting of only the 0th, 1st, 2nd, and 4th order terms of x is E(x)=C0'+C1'×x+C2'×(2x, 2 -1)+C4'×(8x 4 -8x 2 +1) (where -1≦x≦1) to fit E(xi) having j x values ​​(xi), the coefficients (C0', C1', C2', C4') of the Chebyshev polynomial are found by curve fitting (curve approximation) from E(xi) having j x values ​​(xi), and the coefficient (C1') of the first-order term 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 (x) notation indicating the center position in the strip width direction of the divided area (i) obtained by dividing the reflected light area 2 into j in the strip width direction. For example, in the case of -1≦x≦1 of the normalized strip width direction position (x), for example, x=-1 indicates the drive side strip width end position, x=0 indicates the strip width center position, and x=1 indicates the work side strip width end position. Also, F, i, j, and k are integers.

[0101] 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.

[0102] 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.

[0103] <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]

[0104] 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 that crosses the strip width direction and reflects illumination light, 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 1, 2, 3, ..., k, ... in the order they were acquired. In the (k)th image, within each of the divided sections (i) (i = 1 to j) into which the reflected light region is divided in the sheet width direction, the most upstream position Pumin(k)i among the pixel positions constituting the upstream boundary line of the reflected light region, the most downstream position Pumax(k)i among the pixel positions constituting the upstream boundary line of the reflected light region, the most upstream position Pdmin(k)i among the pixel positions constituting the downstream boundary line of the reflected light region, and the most downstream position Pdmax(k)i among the pixel positions constituting the downstream boundary line of the reflected light region are obtained in the rolling direction of pixel coordinates; For each of the F images from image number (k-F+1) to image number (k), which are two or more images acquired, extract data indicating the most upstream position from the F pieces of data from Pumin(k-F+1)i to Pumin(k)i as first position data, and reset this as the data of the (k)th image as Pure_min(k)i; Among the F pieces of data from Pumax(k-F+1)i to Pumax(k)i, data indicating the most downstream position is extracted as second position data, and this is reset as Pure_max(k)i as data of the (k)th image; Among the F pieces of data from Pdmin(k-F+1)i to Pdmin(k)i, data indicating the most upstream position is extracted as third position data, and this is reset as data of the (k)th image to Pdre_min(k)i; Among the F pieces of data from Pdmax(k-F+1)i to Pdmax(k)i, data indicating the most downstream position is extracted as fourth position data, and this is reset as data of the (k)th image to Pdre_max(k)i; The average value of the differences in position data in the rolling direction, [Pure_max(k)i-Pure_min(k)i] and [Pdre_max(k)i-Pdre_min(k)i], is calculated for each divided area (i), and the average value is set as information A(k)i corresponding to the maximum fluctuation amplitude of the upstream boundary position and the downstream boundary position of the reflected light region in the (k)th image, and the value of the information A(k)i is made to correspond to the center 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 A(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 A(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 plate shape detection device for a metal strip plate 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 1, 2, 3, ..., k, ... in the order they were acquired. In the (k)th image, within each of the divided sections (i) (i = 1 to j) into which the reflected light region is divided in the sheet width direction, the most upstream position Pumin(k)i among the pixel positions constituting the upstream boundary line of the reflected light region, the most downstream position Pumax(k)i among the pixel positions constituting the upstream boundary line of the reflected light region, the most upstream position Pdmin(k)i among the pixel positions constituting the downstream boundary line of the reflected light region, and the most downstream position Pdmax(k)i among the pixel positions constituting the downstream boundary line of the reflected light region are obtained in the rolling direction of pixel coordinates; For each of the F images from image number (k-F+1) to image number (k), which are two or more images acquired, extract data indicating the most upstream position from the F pieces of data from Pumin(k-F+1)i to Pumin(k)i as first position data, and reset this as the data of the (k)th image as Pure_min(k)i; Among the F pieces of data from Pumax(k-F+1)i to Pumax(k)i, data indicating the most downstream position is extracted as second position data, and this is reset as Pure_max(k)i as data of the (k)th image; Among the F pieces of data from Pdmin(k-F+1)i to Pdmin(k)i, data indicating the most upstream position is extracted as third position data, and this is reset as data of the (k)th image to Pdre_min(k)i; Among the F pieces of data from Pdmax(k-F+1)i to Pdmax(k)i, data indicating the most downstream position is extracted as fourth position data, and this is reset as data of the (k)th image to Pdre_max(k)i; The average value of the differences in position data in the rolling direction, [Pure_max(k)i-Pure_min(k)i] and [Pdre_max(k)i-Pdre_min(k)i], is calculated for each divided area (i), and the average value is set as information A(k)i corresponding to the maximum fluctuation amplitude of the upstream boundary position and the downstream boundary position of the reflected light region in the (k)th image, and the value of the information A(k)i is made to correspond to the center 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 A(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 A(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) However, by fitting the Chebyshev polynomial with -1≦x≦1, 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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