TWI533950B - Method for checking a terminal of a metal plate and a rolling method using the same - Google Patents

Description

Metal sheet head end detection method and metal sheet Rolling method

The invention relates to a metal sheet head end detecting method and a metal sheet rolling method, in particular to a metal sheet head end detecting method and a metal sheet rolling method suitable for a rolling mill.

In the current steel sheet production process, the steel blank is first heated by a heating furnace and then rolled by a rolling mill to obtain a steel sheet having a desired thickness. During the rolling process, the steel sheet sometimes causes a bending of the head end. When the head end of the steel plate is severely upturned, the steel plate will hit the auxiliary equipment of the upper rolling mill. Conversely, when the head end of the steel plate is bent downward, it will hit the roll of the conveying table. Therefore, for the rolling process, it is very important to reduce the amount of bending of the steel sheet at the end of the rolling delay to avoid the loss of rolling delay caused by equipment damage.

The conventional steel plate squeezing sensing system utilizes an occlusion photoelectric signal sensor or a contact sensor bar for wig detection. However, it can not be determined as a quantitative basis for the process improvement work because it can only determine whether the steel plate exceeds a certain height during the transportation process.

Therefore, there is a need for a sheet metal end detection method and a sheet metal rolling method which can provide specific information on the steel plate screed to help improve the rolling process.

One aspect of the present invention provides a method for detecting a tip end of a metal sheet and a method for rolling a sheet metal, which can determine the amount of tilting of the sheet metal and the direction of the head, and the method of rolling the sheet can be based on the amount of the head. Information on the direction of the squat head to adjust the rolling process to achieve the goal of improving the flatness of the head end of the sheet metal.

According to an embodiment of the present invention, in the method for detecting the tip end of the metal sheet, the image capturing device is first used to capture a plurality of roll images. Then, these roll images are subjected to a binarization process to obtain a plurality of binarized images. Then, based on the grayscale threshold, the image of the head end of the panel is determined from the binarized image. Next, the head end region of the panel is defined from the image of the head end of the panel. Then, according to the head end region of the sheet, the amount of the head end of the sheet and the direction of the head end of the sheet are determined. Next, it is judged whether the head end of the metal sheet is abnormally bent according to the amount of the head end of the sheet and the direction of the head end of the sheet.

According to another embodiment of the present invention, in the metal sheet rolling method, an image capturing device is first used to capture a plurality of roll images. Then, these roll images are subjected to a binarization process to obtain a plurality of binarized images. Then, based on the grayscale threshold, the image of the head end of the panel is determined from the binarized image. Next, the head end region of the panel is defined from the image of the head end of the panel. Then, according to the head end region of the sheet, the amount of head tilt of the sheet is determined. And the direction of the head end of the plate. Next, it is judged whether the head end of the metal sheet is abnormally bent according to the amount of the head end of the sheet and the direction of the head end of the sheet. Then, when the tip end of the metal sheet is judged to be abnormally bent, the rolling process is adjusted according to the amount of the head end of the sheet and the direction of the head end of the sheet.

100‧‧‧Rolling system

110‧‧‧roll

120‧‧‧Image capture device

130‧‧‧Laser projection device

140‧‧‧Computer host

200‧‧‧Metal sheet end detection method

210-270‧‧‧Steps

262-266‧‧‧Steps

900‧‧‧Offline calibration steps

910-930‧‧‧Steps

1200‧‧‧Metal sheet rolling method

1220‧‧‧Steps

CH‧‧‧ convex hull

CHO‧‧ ‧ gap

CS‧‧‧ calibration ruler

CO‧‧‧ hole

L‧‧‧Image capture device and plate center distance

T‧‧‧Sheet thickness

M‧‧‧metal sheet

MH‧‧‧ plate head end area

MHL‧‧‧ sheet end line

O1~O4‧‧‧Image Objects

PL‧‧‧projection light

W‧‧‧ plate width

x ₁ , x ₂ , x ₃ ‧‧‧ standard position

z ₁ , z ₂ ‧‧‧ Height values corresponding to the standard position

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

1 is a schematic structural view of a rolling system according to an embodiment of the present invention.

2 is a flow chart showing a method for detecting a tip end of a metal sheet used in a rolling system according to an embodiment of the present invention.

3 is a diagram showing a histogram of a histogram according to an embodiment of the present invention.

4 is a view showing a head end image of a sheet material according to an embodiment of the present invention.

FIG. 5 is a flow chart showing the step of judging the direction of the tilting head according to an embodiment of the present invention.

Figures 6a-6d illustrate the orientation of the head of the sheet end region in accordance with an embodiment of the present invention.

7a-7d illustrate the thinned front end regions of the panel in accordance with an embodiment of the present invention.

8a-8d illustrate a convex envelope (Convex Hull) of a head end region of a panel according to an embodiment of the present invention.

FIG. 9 is a flow chart showing an offline calibration step according to an embodiment of the present invention.

Figure 10 is a front elevational view of a roll in accordance with an embodiment of the present invention.

Figure 11 is a schematic diagram showing the calibration of a calibration ruler in accordance with an embodiment of the present invention.

FIG. 12 is a schematic flow chart showing a method for rolling a metal sheet according to an embodiment of the present invention.

Please refer to FIG. 1. FIG. 1 is a schematic structural view of a rolling system 100 according to an embodiment of the present invention. The rolling system 100 includes a roll 110, an image capturing device 120, a laser projection device 130, and a computer host 140. The roll 110 is used to roll the sheet metal M to roll the sheet M to a predetermined thickness. In the present embodiment, the metal sheet M is a steel sheet, but the embodiment of the invention is not limited thereto. The image capturing device 120 and the laser projection device 130 are disposed on the side of the metal sheet M and on the same level as the metal sheet M. The image capturing device 120 picks up the rolled image of the metal sheet M from the side of the roll 110 to monitor the tilting direction and the amount of curling of the sheet metal M, wherein the direction of the head is toward the upper roll or toward the lower roll. The computer host 140 is electrically connected to the image capturing device 120 to determine whether the metal sheet M is bent according to the roll image obtained by the image capturing device 120. In an embodiment of the present invention, the rolling system 100 may further include an alignment laser device to facilitate field personnel to know whether the current image capturing device 120 is located near the surface of the roller 110. Image capture device 120 is on the same plane as the alignment laser device, so that the reference or the image capturing device 120 can be used to observe whether the reference is run away. However, embodiments of the invention are not limited thereto. In other embodiments of the invention, the rolling system 100 can also utilize other means to assist in the alignment of the image capturing device 120.

Please refer to FIG. 2 , which is a schematic flow chart of a method for detecting the tip end of a metal sheet used in the rolling system 100 according to an embodiment of the invention. In the sheet metal tip end detecting method 200, step 210 is first performed to capture a plurality of roll images of the roll 110 by the image capturing device 120. In the present embodiment, the image capturing device 120 is a camera that continuously captures an image of the roll 110 from the side of the roll 110. Then, step 220 is performed to binarize the roll image captured by the image capturing device 120 to obtain a plurality of binarized images. In the present embodiment, the binarization processing is performed by the Otsu method, but the embodiment of the present invention is not limited thereto.

As shown in Figure 3, the Otsu algorithm performs an image histogram on the entire roll image (or a custom region of interest (ROI) in the image) and the difference between the foreground and background gray scales. The maximum threshold is set to the target threshold. Thus, after the processing of step 220, each binarized image corresponds to a target threshold. In order to speed up the operation, the following steps are all performed on the image in the region of interest, but the embodiment of the present invention is not limited thereto.

After step 220, step 230 is performed to determine the head end shadow from the binarized image according to the preset gray scale threshold. image. Step 230 is to continuously compare two consecutive time binarized images to determine whether the target threshold has a significantly increased (smaller) change, thereby determining whether the head end of the metal sheet M enters the region of interest. For example, for two consecutive time binarized images, it is judged that the target threshold is changed from small to large or from large to small. When the target threshold becomes smaller from time to time and the magnitude of the change exceeds the preset grayscale threshold, then the binarized image with the later time is determined as the image of the head end of the sheet. Conversely, when the target threshold changes from large to large and the magnitude of the change exceeds the preset grayscale threshold, the binarized image with the earlier time is determined as the head end image. In the present embodiment, the preset grayscale threshold is 100 gray scales, but the embodiment of the present invention is not limited thereto.

After finding the image of the head end of the sheet, step 240 is performed to find the head end region of the sheet metal M in the image of the head end of the sheet. In the present embodiment, step 240 utilizes the maximum area characteristic to find the head end region of the sheet metal M. As shown in FIG. 4, four image objects O1 to O4 can be defined in the image of the head end of the sheet, wherein the image object O1 has the largest area, so step 240 defines the image object O1 as the head end region of the sheet.

After the head end region of the sheet is found, step 250 is then performed to determine the amount of head end tilt of the sheet metal M based on the sheet end region. For example, step 250 obtains the head end height of the metal sheet M according to the pixel position of the upper edge of the image object O1 and its corresponding actual height value, to obtain the head end tilt amount of the metal sheet M. In this embodiment, the sheet metal head end detecting method 200 may further include an offline performing calibration step to obtain an image pixel position and an actual height value corresponding thereto. This correction step will be described in detail later in this article.

After the amount of curl is obtained, the slanting direction determining step 260 is next performed to determine the slanting direction of the sheet metal M. Please refer to FIG. 5 , which is a flow chart of the slanting direction determining step 260 according to an embodiment of the present invention. In the slanting direction determining step 260, step 262 is first performed to thin the tip end region of the sheet in the head end image. In general, the direction of the head of the sheet head end region MH can be divided into several types such as simple upward (or downward), upward tilting, downward tilting, and downward tilting, as shown in Figures 6a-6d. . In order to facilitate the subsequent steps of processing the sheet head end region MH, this embodiment utilizes step 262 to thin the sheet head end region MH to obtain the sheet head end fine line MHL, as shown in Figures 7a-7d. However, embodiments of the invention are not limited thereto. In other embodiments of the invention, skeltonization may also be utilized in place of thinning.

Next, step 264 is performed to perform a convex hull calculation on the thinned sheet end region MH. As shown in Figures 8a-8d. In this embodiment, step 264 establishes a convex hull CH on the thin end line MHL of the sheet, so that the notch CHO can be defined by the convex hull CH, wherein the notch CHO is surrounded by the thin end line MHL and the convex hull CH. region. Next, step 266 is performed to determine the tilting direction of the metal sheet M according to the area and position of the notch CHO.

For example, when the area of the notch CHO is not greater than the preset area threshold (for example, 50 image pixels), it means that the metal sheet M is simply upward (or downward). More specifically, when the vertical value (v-axis coordinate value) of the tail end of the thin wire MHL of the sheet end is larger than the vertical value of the head end of the fine line MHL of the sheet end, it is judged that the metal sheet M is simply upward. Conversely, when the sheet ends are thin line MHL tail When the vertical value of the end is smaller than the vertical value of the head end of the thin line MHL of the sheet end, it is judged that the metal sheet M is simply facing downward.

For another example, when the area of the notch CHO is larger than the preset area threshold, and the position of the notch CHO is above the sheet end end fine line MHL, it means that the metal sheet M is upturned.

For another example, when the area of the notch CHO is greater than the preset area threshold, and the position of the notch CHO is below the sheet end end fine line MHL, it represents that the metal sheet M is tilted downward. In addition, if there are two or more notches CHO, it is necessary to use the horizontal coordinates of the notch CHO to determine whether the metal sheet M is up and then upturned or up and then tilted up.

In step 266, the relative positional relationship between the notch CHO and the sheet end end fine line MHL can be judged by the vertical coordinate of the convex hull CH. For example, when the vertical coordinates of the convex hull CH are both larger than the vertical coordinates of the thin line MHL of the sheet end, the position representing the notch CHO is above the sheet end end fine line MHL. On the other hand, when the vertical coordinates of the convex hull CH are smaller than the vertical coordinates of the thin line MHL of the sheet end, the position of the notch CHO is below the thin line MHL of the sheet end.

After judging the bending direction of the metal sheet M, an abnormality judging step 270 is next performed to determine whether or not the sheet metal M is abnormally bent based on the tilting direction of the sheet metal M and the amount of warping. In the present embodiment, the metal sheet M is somewhat warped and can be tolerated. For example, when the metal sheet M is judged to be simply tilted and the amount of tilt does not exceed a predetermined threshold, it is judged to be normal. However, when the metal sheet M is judged to be simply tilted and the amount of warping exceeds a predetermined threshold, or the sheet metal M is judged to be another headwise direction, for example, Simply upturning, upturning, going down, going up and then going up, going up and then going up and down, etc., are all judged to be abnormal. When the metal sheet M is detected to be abnormal, the line personnel can adjust the process parameters of the roll 110 according to the amount of the tilt of the metal sheet M and the direction of the slanting head to improve the abnormal condition.

Please refer to FIG. 9 , which is a schematic flowchart of an offline calibration step 900 according to an embodiment of the present invention. The offline calibration step 900 is used to obtain an image pixel position and an actual height value corresponding thereto. In the offline correction step 900, step 910 is first performed to obtain a representative equation for the pixel height. When calculating the height of the image pixel, the step 910 of the embodiment may obtain the distance L between the image capturing device 120 and the center of the production line, the width value W of the sheet, and the thickness value T through the process control computer to calculate the image pixel. the height of. As shown in Fig. 10, when the edge position of the metal sheet M (i.e., the half width value W) is at the standard position x ₁ or x ₂ on the roll plane, the representative equation of the image pixel height can be expressed by regression calculation as follows:

Where z ₁ and z ₂ are the height values corresponding to the standard positions x ₁ and x ₂ respectively, a _x1ij and a _x2ij are equation coefficients, and (u, v) is the pixel coordinates of the image captured by the image capturing device 120. . In addition, considering the half width (W/2) of the metal sheet M between the standard positions x ₁ and x ₂ , the corresponding height equation is obtained by interpolation as follows: among them, For location The corresponding height value, x ₁ L - W x ₂ .

Next, step 920, to scale the correction and laser projection device 130 CS acquires the standard position x ₁ and x ₂ corresponding to the height value z ₁ and z _2, as shown in FIG. In step 920, a correction is first disposed in the standard position CS feet x ₁ or x _2, and by a laser projection device 130 to correct the light projected onto the foot CS. Since the calibration ruler CS has a plurality of holes CO, when the laser projection device 130 projects light to the correction ruler CS, the projection light PL appears between the holes CO. Next, step 930 is performed to calculate the equation coefficients in the above equations (1) and (2). In step 930, since the size of the hole CO of the calibration ruler CS is known, the actual height value of the center of gravity of all the projected light beams PL can be calculated first, and then the image pixels corresponding to the actual height values (u _k , v _k ). Thus, when the calibration ruler CS is moved to the standard position x _n on the roll plane (n=1, 2 in the present embodiment), the least square method can be used to evaluate the actual height value and the errors of equations (1) and (2). To calculate the equation coefficients in equations (1) and (2) above, the formula is as follows: Where z _k is the actual height value corresponding to the standard position x _n and the image pixels (u _k , v _k ); E _xn is the error; a _{xn , 00} , a _{xn , 01} , a _{xn , 10} ,.... , a _{xn , pq} is the coefficient.

As can be seen from the above description, the offline correction step 900 of the present embodiment sequentially moves the calibration ruler CS to each standard position x _n to thereby calculate the coefficient of the equations in the above equations (1) and (2), thereby obtaining The representative equation of the pixel height of the image.

It is worth mentioning that, in the embodiment of the present invention, the offline correction step 900 uses the interpolation method to calculate the pixel height value between the standard positions x ₁ and x ₂ , so in other embodiments of the present invention, it may also be set. Multiple standard positions (eg, n=1~8) to utilize multiple standard positions to improve the accuracy of pixel height value calculations.

Please refer to FIG. 12 , which is a schematic flow chart of a metal sheet rolling method 1200 according to an embodiment of the invention. In the sheet metal rolling method 1200, the above-described sheet metal tip end detecting method 200 is first performed to find the amount of the head of the sheet metal M and the direction of the head, and to determine whether or not the sheet is abnormally bent. If the metal sheet M is abnormally bent, then step 1220 is performed to adjust the rolling process according to the amount of the tilting of the metal sheet M and the direction of the tilting head, for example, watering down, or changing the rolling parameters of the upper and lower rolls, so that The head end of the metal sheet M returns to normal. The sheet metal rolling method 1200 can be automatically performed through the process control system, for example, performing the above steps 210-270 to automatically determine whether the sheet metal is abnormally bent, and then performing step 1220 to adjust the rolling process to restore the head end of the metal sheet. normal.

It can be seen from the above description that the metal sheet tip end detecting method 200 of the embodiment of the present invention can determine the tilting direction and the amount of tilting of the metal sheet M, and the sheet metal rolling method 1200 can utilize the tilting direction and the amount of tilting. Adjusting the rolling process, so as to achieve the goal of improving the flatness of the head end of the sheet metal.

While the present invention has been described above by way of example, it is not intended to be construed as a limitation of the scope of the invention. because The scope of the present invention is defined by the scope of the appended claims.

200‧‧‧Metal sheet end detection method

210-270‧‧‧Steps

Claims (10)

A metal sheet head end detecting method for detecting whether a head end of a metal sheet on a rolling mill is abnormally bent, and the sheet metal head end detecting method comprises: using an image capturing device to extract a plurality of roll images; The roll image is subjected to a binarization process to obtain a plurality of binarized images; a head end image is determined from the binarized images according to a gray scale threshold; and the head end image is defined from the image a head end region of the sheet; determining a head end amount of the sheet according to the head end region of the sheet; determining a head end slanting direction according to the head end region of the sheet, wherein the head end of the sheet head is oriented upwardly Rolling or facing the next roll; and judging whether the head end of the metal sheet is abnormally bent according to the amount of the head end of the sheet and the direction of the head end of the sheet. The metal sheet tip end detecting method of claim 1, wherein the binarization processing is performed by an Ostu method. The method for detecting a tip end of a metal sheet according to Item 1 of the claim, wherein the step of defining a head end region of the sheet comprises: defining a plurality of objects in the image of the head end of the sheet; and having a maximum area among the objects It is defined as the head end region of the sheet. The method for detecting the tip end of the metal sheet according to Item 1 of the claim further comprises performing a correcting step to determine a plurality of actual height values corresponding to the plurality of pixel positions of the image of the head end of the sheet, and determining the tip end of the sheet. The step of the first amount determines the amount of tilting of the head end of the sheet according to the plurality of head end pixels included in the head end region of the sheet and the actual height values. The method for detecting a tip end of a metal sheet according to Item 4, wherein the correcting step comprises: setting a calibration ruler on a conveying plane of the rolling mill, wherein the calibration ruler has a plurality of holes; projecting the light to the calibration ruler And generating a plurality of projection rays between the holes of the calibration ruler; and determining the actual height values corresponding to the pixel positions according to the center of gravity of the projection rays. A sheet metal rolling method for producing a metal sheet by using a rolling mill, wherein the rolling method comprises: performing a rolling delay on the rolling mill to perform a metal sheet head end detecting method to detect whether the head end of the metal sheet is abnormally bent The method for detecting the head end of the metal sheet comprises: using an image capturing device to capture a plurality of image of the roll; performing a binarization process on the roll images to obtain a plurality of binarized images; a threshold to determine a head end image from the binarized images; Defining a head end region from the head end image of the sheet; determining a head end amount of the sheet according to the head end region of the sheet; determining a head end slanting direction according to the head end region of the sheet, wherein the sheet The head end slanting direction is toward an upper roll or toward a lower roll; and determining whether the head end of the metal plate is abnormally bent according to the amount of the head end of the plate and the direction of the head end of the plate; and when the metal plate is When the head end is judged to be abnormally bent, the rolling process is adjusted according to the amount of the head end of the sheet and the direction of the head end of the sheet. The sheet metal rolling method of claim 6, wherein the binarization treatment is performed by an Ostu method. The metal sheet rolling method of claim 6, wherein the step of defining the head end region of the sheet comprises: defining a plurality of objects in the image of the head end of the sheet; and having the largest area among the objects Defined as the head end region of the sheet. The metal sheet rolling method of claim 6 further includes performing a correcting step to determine a plurality of actual height values corresponding to a plurality of pixel positions of the head end image of the sheet, and determining the head end of the sheet The step of determining the amount of tilting of the head end of the sheet is determined according to a plurality of panel head end pixels included in the head end region of the sheet and the actual height values. The sheet metal rolling method of claim 9, wherein the correcting step comprises: setting a calibration ruler on a conveying plane of the rolling mill, wherein the calibration ruler has a plurality of holes; projecting light onto the calibration ruler And generating a plurality of projection rays between the holes of the calibration ruler; and determining the actual height values corresponding to the pixel positions according to the center of gravity of the projection rays.