JP2004125653A - Process for removing defect of steel plate on pickling acid entrance side - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing defects of a steel plate on a pickling acid entrance side which avoids a trouble such as a plate break in a process after pickling and achieves a high productivity. <P>SOLUTION: A defect inspection apparatus 4 obtains an image as a state of a surface of the steel plate on an exiting side of a hot stretching, finishing and rolling machine. The obtained image is stored in an image storage apparatus 12 and transmitted to a pickling terminal 8 on a pickling acid entrance side based on pickling acid passage plate schedule information. An image display apparatus 9 displays the image on a screen on the pickling acid entrance side along with defect candidate information. An operator detects the defects on the steel plate based on an guidance and cuts the defects of the steel plate. Or the defects on the steel plate can be automatically cut based on the defect candidate information. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for removing a defective portion of a steel sheet on the entry side of a pickling process.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-242089
Generally, various defects (flaws) exist on the surface of a hot-rolled steel sheet. If pickling and cold rolling are performed while leaving the defect, the sheet may be broken, and the production line is stopped for a long time to significantly reduce the production efficiency. Therefore, it is required to remove a harmful defect before entering the pickling process.
[0004]
However, scale is formed on the surface of the hot-rolled steel sheet that has reached the entry side of the pickling step, which hinders detection of defects. Therefore, the operator cuts all of the tip and tail ends of the coil where harmful defects occur frequently by a certain length, and welds and connects the tail end of the previous coil and the tip of the next coil to form a harmful defect. The defective portion was prevented from flowing to the process after pickling.
[0005]
However, in such a method in which the leading end and the trailing end of the coil are all cut to a fixed length, a portion having no defect is always discarded, resulting in a decrease in production efficiency. Further, even if a defect exists in a portion other than the tip end portion and the tail end portion of the coil, it cannot be eliminated on the entrance side of the pickling process, and a harmful defective portion flows to a subsequent process.
[0006]
Patent Document 1 discloses a technique for inspecting the surface of a steel sheet before scale is formed immediately after hot rolling. However, there is no description on how to use the inspection result, and there is no description on the input side of the pickling process. In Japanese Patent Application Laid-Open No. H08-157, there is no description of removing a defective portion of a steel sheet.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problems, and reliably detects a harmful defect in the hot-rolled steel sheet that has reached the entrance side of the pickling process and removes only the defective portion. The present invention has been made to provide a method for removing a defective portion of a steel plate on the pickling side, which can avoid troubles such as plate breakage in the step of (1) and can achieve high production efficiency.
[0008]
[Means for Solving the Problems]
The invention of claim 1 made in order to solve the above-mentioned problem acquires the state of the steel sheet surface as an image at the exit side of the hot rolling finishing rolling mill, accumulates the acquired image, and accumulates the acquired image according to the pickling plate schedule information. It is transmitted to the pickling side and displayed on the screen of the pickling side together with the defect candidate information obtained by calculating the image, and based on this guidance, the operator detects a steel plate defect and cuts the defective part of the steel plate. It is characterized by doing.
[0009]
In order to solve the same problem, the invention of claim 2 obtains an image of the state of the surface of the steel sheet as an image on the exit side of the hot-rolling finishing rolling mill, accumulates the obtained image, and stores the information on the pickling plate schedule information. Is displayed on the screen of the pickling side together with the defect candidate information obtained by calculating the image according to the above, and the defective portion of the steel sheet is automatically cut based on the defect candidate information. It is assumed that.
[0010]
According to these inventions, in the pickling step or the cold rolling step, a defect that causes a sheet break can be accurately detected on the pickling side and only that part can be removed. Stopping can be prevented beforehand, and a healthy part is not removed as in the conventional case, so that high production efficiency can be achieved. Further, if the defective portion is automatically removed as in the second aspect of the present invention, the work load on the operator can be remarkably reduced, and the labor and the unmanned pickling process can be realized. Become.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a diagram showing the entire system of the embodiment, wherein 1 is a hot rolling line, 2 is an operation room installed on the picking process entry side, and 3 is a communication line such as a local LAN connecting these. The hot rolling line is provided with a defect inspection device 4 and a server 5, and image information is transmitted to a pickling terminal 8 provided in an operation room of the pickling process via a router 6, a communication line 3, and a router 7. You. Reference numeral 9 denotes an image display device such as a CRT connected to the pickling terminal 8.
[0012]
First, the defect inspection device 4 for a hot-rolled line includes a rod-shaped light source 10, a CCD line sensor 11, and an image storage device 12, as shown in FIG. On the exit side of the hot rolling finishing rolling mill, the surface of the steel sheet is irradiated with a high-intensity light beam from the rod-shaped light source 10 at an incident angle of preferably 5 degrees, and the steel sheet is preferably irradiated with a high-resolution CCD line sensor 11 installed at an angle of 10 degrees. The surface condition of both the front and back surfaces is obtained as an image. In this embodiment, a steel plate having a width of 1700 mm is photographed using one CCD line sensor 11 having 2048 pixels. Since continuity of images can be ensured as compared with the case where a plurality of cameras are used, visibility and defect inspection accuracy can be improved. Immediately after leaving the hot rolling mill, since no scale is formed on the surface of the steel sheet, defects on the surface of the steel sheet can be captured as images.
[0013]
The acquired image is stored in the image storage device 12 using a hard disk. The image storage device 12 compresses the image data and stores it together with the serial number. In this embodiment, it is possible to accumulate images of 10,000 coils corresponding to the production amount for two weeks.
[0014]
The time lag until the steel sheet manufactured in the hot rolling step is passed through the pickling step is one day for a short one and one to two weeks for a long one. During this time, the surface of the steel sheet is oxidized to form scale, and when reaching the entrance of the pickling process, the surface defect of the steel sheet is buried in the scale and becomes difficult to identify. Therefore, in the present invention, the image data obtained in the hot rolling step 1 is transmitted to the pickling side via the communication line 3 and used. For this reason, the pickling terminal 8 receives the passing schedule information for the pickling process from the process computer, and, based on the serial number, images of the steel plate scheduled to pass through the image storage device 12 via the communication line 3. receive.
[0015]
As described above, the surface defects of the steel sheet tend to concentrate at the tip and tail ends of the coil. Then, the pickling terminal 8 displays the image received from the image storage device 12 on the image display device 9 such as a CRT over the 6 m of the tail end of the previous coil and the 6 m of the end of the next coil. It is preferable that the image to be displayed is subjected to image luminance correction with emphasis on visibility.
[0016]
The image luminance correction is specifically shading correction and average luminance correction. Shading correction refers to increasing the luminance at the end using a correction curve as shown in FIG. 3 and making the luminance in the width direction uniform, since the luminance at the end is lower than that at the center of the camera. The average luminance correction is a correction for eliminating a difference in luminance of an image due to a difference in surface reflectance due to various factors such as a steel type of a hot-rolled steel sheet and a rolling temperature. In this embodiment, a five-stage correction curve shown in FIG. 4 is set, and the correction curve is automatically selected from the average luminance of the image to perform the correction.
[0017]
It is possible for the operator in the pickling process to visually determine the defective part by visually observing the image processed in this manner. However, in the present invention, one step is taken, and the defect candidate information obtained by calculating the image is used. Provide guidance to the operator. Image calculation for obtaining defect candidate information is performed, for example, as follows.
[0018]
As shown in FIG. 5, first, the edge of the steel sheet is detected from the image, and the luminance is corrected as described above, and then binarized at an appropriate level. Extract the lower part. Further, after performing a process of removing an isolated black point as noise, the degree of harm is determined based on feature amounts such as the area, perimeter, aspect ratio, and luminance of the extracted portion. When it is determined that the defect is a harmful defect, a marking 13 is applied to the defect position of the image as shown in FIG. 1, and guidance is provided to the operator as defect candidate information. When this image is displayed, a warning can be given by a buzzer, a patrol light, or the like. FIG. 6 shows an original image and an image after image processing.
[0019]
The operator can enlarge and display the image by operating the switch to check the defect. The operator who has detected a harmful defect on the screen based on the guidance operates the shear device to cut the defective portion of the steel plate.
[0020]
According to the second aspect of the present invention, the defective portion of the steel plate is automatically cut based on the defect candidate information without the intervention of an operator. In this case, the distance from the coil end to the harmful defect is calculated based on the actual size of the steel plate per pixel on the screen, and a cutting command is input to the line controller so that the portion is cut. Good.
[0021]
Since the steel plates from which the defective portions have been removed in this way are connected by welding and passed through the pickling and cold rolling processes, it is possible to reliably prevent the occurrence of serious troubles such as plate breakage. In the above embodiment, the image processing and the defect detection are performed only on the leading end and the tail end of the coil. However, the same processing can be performed on the entire length of the coil.
[0022]
【The invention's effect】
As described above, according to the method for removing a defective portion of a steel sheet on the pickling side of the present invention, a defect causing a sheet break is pickled on the basis of an image acquired on the output side of the hot-rolling finishing mill. Since the detection is accurately performed on the entry side and the portion is removed, it is possible to prevent the production line from being stopped due to the plate breakage. Further, according to the present invention, since a healthy portion is not mechanically removed as in the related art, loss of a steel plate is reduced, and high production efficiency can be achieved.
[0023]
According to the second aspect of the present invention, since the defective portion of the steel sheet is automatically cut based on the defect candidate information, the work load on the operator can be significantly reduced, and the pickling process can be labor-saving and unmanned. Can also be realized.
[Brief description of the drawings]
FIG. 1 is an overall view of a system according to an embodiment.
FIG. 2 is a front view of a hot-rolling line defect inspection apparatus.
FIG. 3 is a graph of a correction curve for shading correction.
FIG. 4 is a graph of a correction curve for correcting average luminance.
FIG. 5 is a block diagram illustrating an image processing process.
FIG. 6 shows an original image and an image after image processing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hot-rolling line 2 Operator's cab 3 installed on the picking side of pickling process 3 Communication line 4 Defect inspection device 5 Server 6 Router 7 Router 8 Pickling terminal 9 Image display device 10 Bar light source 11 CCD line sensor 12 Image storage device 13 Marking

Claims (2)

It was obtained by acquiring the state of the steel sheet surface as an image on the exit side of the hot rolling finishing rolling mill, storing the acquired image, transmitting the image to the pickling side according to the pickling passing plate schedule information, and calculating the image. A method for removing a steel plate defect on the pickling side, wherein the defect is displayed on the screen on the pickling side together with the defect candidate information, and based on this guidance, the operator detects a steel plate defect and cuts the defective part on the steel plate. . It was obtained by acquiring the state of the steel sheet surface as an image on the exit side of the hot rolling finishing rolling mill, storing the acquired image, transmitting the image to the pickling side according to the pickling passing plate schedule information, and calculating the image. A method for removing a defective portion of a steel sheet on the pickling side, comprising displaying on a screen on the pickling side together with the defect candidate information and automatically cutting the defective portion of the steel sheet based on the defect candidate information.

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