JP2013205381A - Method and system for detecting defect of steel tape threaded into cold rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more surely prevent rupture of a steel tape in cold rolling by increasing a detection rate of a defect of the steel tape threaded into a cold rolling mill.SOLUTION: A predetermined range from both edges of a steel tape flowing on a line of a step before a cold rolling step is completely and continuously imaged by a camera (S1) and position information of an image obtained by imaging is allowed to correspond to the image by data processing means (S2). By using an image analysis apparatus, the image picked up by the camera is divided into grating-like segments, and an average concentration of each segment and a difference of average concentrations between adjacent segments are calculated. When any of average concentration differences exceeds a predetermined threshold, inclusion of a defect in the image is determined (S3: YES), and based on the determination, detection of the defect is reported by notification means (S5).

Description

  The present invention relates to a defect detection method and a defect detection system for a steel strip that passes through a cold rolling mill. In particular, a method for preventing the steel strip from breaking during cold rolling due to the presence of defects such as wrinkles and inclusions in the steel strip before passing through the cold rolling mill, and About the system.

  As is well known, in the manufacturing process of a cold-rolled steel strip in which a hot coil is rolled to a product thickness at room temperature, first, the oxide scale generated on the surface of the hot coil (steel strip) is pickled with pickling equipment, Next, the edge of the steel strip is cut by the side trimmer equipment and adjusted to a predetermined product width. And the steel strip from which the edge was cut is further thinly rolled with a cold rolling mill, and it is set as a cold-rolled steel strip (cold-rolled coil).

  When a steel strip is rolled by a cold rolling mill, tension is applied to the steel strip. If there are defects such as wrinkles and inclusions in the steel strip, the steel strip may break due to the defects. is there.

JP 2010-91460 A

  It is known that the steel strip breakage during cold rolling is caused by many defects within a predetermined range from the tip and tail ends of the hot coil, and the defects contribute to the breakage. Based on this, before extending the hot coil to the pickling / cold rolling equipment, by pre-cutting the predetermined range from the leading end of the hot coil in advance, fracture near the leading end of the steel strip during cold rolling However, there was a problem that the yield was greatly deteriorated. There is also a problem in that the steel strip cannot be prevented from breaking during cold rolling due to defects existing at the ends other than the leading end of the steel strip.

  Therefore, while illuminating the lower surface of the steel strip with a fluorescent lamp with a light transmission type defect detector, the amount of light entering the camera installed above the steel strip is monitored, and the light projected from below is the defect of the steel strip. Techniques have been proposed to prevent steel strip breakage during cold rolling by detecting defects in the steel strip when it passes through (holes, cracks, wrinkles, etc.) and enters the camera (for example, patent documents) 1).

  However, some defects that cause steel strip breakage during cold rolling do not transmit light. For such defects, a light transmission type defect detector has been ineffective. As described above, defects that do not transmit light include cracks formed obliquely to the thickness direction of the steel strip, linear wrinkles in the width direction of the steel strip, and gouges.

  Other problems caused by the steel strip breaking during cold rolling include a reduction in production efficiency due to the need to stop the cold rolling mill when the steel strip breaks, and an increase in the load on the operator.

  The present invention was devised in view of the above-described problems, and by increasing the detection rate of defects in the steel strip that passes through the cold rolling mill, the steel strip is more easily broken during cold rolling. It is an object of the present invention to provide a method and a system that can be surely prevented.

  In order to achieve the above object, the “defect detection method for a steel strip that passes through a cold rolling mill” according to the present invention is within a predetermined range from both side edges of a steel strip flowing on a line preceding the cold rolling step. An image capturing step for continuously capturing images with a camera without omission, and an image analysis device that divides the image captured by the camera into grid-like segments, and the average density in each segment and between adjacent segments A defect determination step for calculating a difference in average density of the images and determining that the image includes a defect if any of the average density differences exceeds a predetermined threshold; A defect notifying step for notifying by a notifying means that a defect has been detected when it is determined that a defect is included.

  According to the “defect detection method of a steel strip that passes through a cold rolling mill” including such a configuration, when a defect is included in the imaging range of the steel strip, before the defect is sent to the cold rolling mill. Since the fact that a defect has been detected is notified, it is possible to prevent the steel strip passed through the cold rolling mill from breaking. In addition, since the defect is detected based on the density difference between the segments obtained by dividing the image into a lattice pattern, not only the defect that transmits light but also the defect that does not transmit light is detected. As a result, the defect detection rate is improved, and the steel strip is more reliably prevented from being broken during cold rolling.

  In the "steel strip defect detecting method for passing through a cold rolling mill" including the above configuration, a position information associating step of associating position information of an image obtained by imaging by the camera with the image by means of data processing means In addition, it is preferable that in the defect detection and notification step, the notification means notifies the fact that a defect has been detected and position information associated with an image including the defect.

  According to the “defect detection method of a steel strip that passes through a cold rolling mill” including such a configuration, when the detection of the defect is notified, the positional information of the defect is also notified. It is possible to easily identify the site where the.

  In the “defect detection method for a steel strip that passes through a cold rolling mill” including the above-described configuration, a pickling process, a rinsing process, a drying process, and a side trimming process are included in the processes preceding the cold rolling process. In the imaging step, the camera continuously images within a predetermined range from both side edges of the steel strip flowing on the line between the drying step and the side trimming step without omission. It is desirable.

  According to the “defect detection method of a steel strip that passes through a cold rolling mill” including such a configuration, the camera images the steel strip that flows on the line between the drying step and the side trimming step. The image analysis of the steel strip can be performed without being affected by the lubricating oil (cutting oil) adhering to the steel strip in the trimming process. As a result, it is possible to prevent erroneous detection of an oil pattern or the like as a defect.

  The “defect detection system for a steel strip that passes through a cold rolling mill” of the present invention continuously images within a predetermined range from both side edges of the steel strip flowing on the line preceding the cold rolling process without omission. Divide the camera and the image captured by the camera into grid-like segments, calculate the average density in each segment and the average density difference between adjacent segments, An image analysis device that determines that the image includes a defect when the image exceeds a predetermined threshold, and the image analysis device determines that a defect is included in any of the images. And a notifying means for notifying that it has been detected.

  According to the “defect detection system for a steel strip that passes through a cold rolling mill” having such a configuration, if a defect is included in the imaging range of the steel strip, before the defect is sent to the cold rolling mill Since the fact that a defect has been detected is notified, it is possible to prevent the steel strip passed through the cold rolling mill from breaking. In addition, since the defect is detected based on the density difference between the segments obtained by dividing the image into a lattice pattern, not only the defect that transmits light but also the defect that does not transmit light is detected. As a result, the defect detection rate is improved, and the steel strip is more reliably prevented from being broken during cold rolling.

  In the "steel strip defect detection system that passes through a cold rolling mill" having the above-described configuration, the image processing apparatus further includes data processing means for associating position information in the steel strip of the image obtained by imaging the camera with the image, When the image analysis apparatus determines that any of the images includes a defect, the notification unit notifies that the defect has been detected and position information associated with the image including the defect. Is desirable.

  According to the “defect detection system for a steel strip that passes through a cold rolling mill” having such a configuration, when the detection of the defect is notified, the position information of the defect is also notified. It is possible to easily identify the site where the.

  In the “steel strip defect detection system that passes through a cold rolling mill” having the above-described configuration, the processes preceding the cold rolling process include a pickling process, a rinsing process, a drying process, and a side trimming process. The camera is intended to continuously capture within a predetermined range without omission from both side edges of the steel strip flowing on the line between the drying step and the side trimming step. desirable.

  According to the “defect detection system for a steel strip that passes through a cold rolling mill” having such a configuration, the camera images the steel strip that flows on the line between the drying step and the side trimming step. The image analysis of the steel strip can be performed without being affected by the lubricating oil (cutting oil) adhering to the steel strip in the trimming process. As a result, it is possible to prevent erroneous detection of an oil pattern or the like as a defect.

  According to the defect detection method and defect detection system for a steel strip that passes through the cold rolling mill of the present invention, the detection rate of the defects in the steel strip that passes through the cold rolling mill increases, and the steel during cold rolling is improved. The breakage of the band can be prevented more reliably. As a result, it can be expected to improve the yield of the steel strip, improve the production efficiency, and reduce the load on the operator.

It is a schematic diagram which shows a pickling and cold rolling line. It is a figure which shows the structural example of "the defect detection system of the steel strip which passes along a cold rolling mill." It is a flowchart which shows the procedure of the processing operation which the "defect detection system of the steel strip which passes along a cold rolling mill" performs. It is a figure which shows the image-analysis procedure which an image-analysis apparatus performs.

  Hereinafter, a “defect detection method and defect detection system for a steel strip passed through a cold rolling mill” according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a pickling / cold rolling line 1. In this pickling / cold rolling line 1, in order from the upstream side, pickling equipment 2 for performing pickling process for pickling and removing oxide scale on the surface of the steel strip, rinsing equipment 3 for performing rinsing process for washing away hydrochloric acid, steel Dryer equipment 4 for performing the drying process for drying the strip, first exit louver 5, side trimmer facility 6 for performing the side trimming process for cutting both sides of the steel strip, second exit louver 7, etc. are installed. A cold rolling mill 8 is installed.

  A high-speed CCD camera 10 (hereinafter simply referred to as “camera 10”) is provided at a position between the dryer equipment 4 and the side trimmer equipment 6 (more precisely, a position between the dryer equipment 4 and the first exit louver 5). .) Is installed. As shown in FIG. 2, the camera 10 is connected to an image analysis device 11 and sequentially transfers captured images to the image analysis device 11. The image analysis apparatus 11 is connected to an operator operation panel 12, a monitoring monitor 13, and a line control computer 14 that controls the pickling / cold rolling line 1. The “defect detection system for a steel strip passing through a cold rolling mill” according to the present embodiment is configured. The line control computer 14 manages the position information (tracking data) of the leading end of the steel strip 9 drawn out on the line.

  The “defect detection method for a steel strip passed through a cold rolling mill” according to the present embodiment is performed according to the procedure shown in FIG. First, in step S1, the upper and lower surfaces of the steel strip 9 flowing on the pickling / cold rolling line 1 are each illuminated with predetermined illumination by two upper and lower lights 15 (only one is shown in FIG. 2). By two upper and lower cameras 10 (only one is shown in FIG. 2), within a predetermined range from both side edges of the upper and lower surfaces of the steel strip 9 (in this embodiment, within a range of 50 mm from both side edges of the steel strip 9). Each is continuously imaged. Images captured by the camera 10 are sequentially transferred to the image analysis device 11.

  The time interval at which the steel strip 9 is imaged by the camera 10 is set in consideration of the moving speed of the steel strip 9 so as not to cause imaging omission in the entire longitudinal direction of the steel strip 9. For example, when the moving speed of the steel strip 9 is 480000 mm per minute and the imaging range in the flow direction of the steel strip 9 by the camera 10 is 40 mm, it is necessary to image 12000 times per minute (= 480000 mm / 40 mm) or more. That is, by imaging 12000 times or more per minute, the predetermined range of the steel strip 9 flowing on the line 1 can be continuously imaged without omission. Note that the imaging range of the camera 10 is within the range of 50 mm from both side edges of the steel strip 9. As a result of investigating the steel strip that has been fractured during cold rolling, the fractured steel strip is defective to 50 mm from both side edges. This is because the steel sheet in which defects were present near the center of the steel strip and the statistical result that almost no fracture occurred was obtained.

  The image analysis apparatus 11 is an arithmetic processing apparatus mainly composed of a CPU, a RAM, a ROM, a hard disk, and the like, and executes an image analysis program incorporated in the ROM to perform the following processing operations. Functions as a device.

  In step S <b> 2, the image analysis apparatus 11 temporarily stores the images sequentially transferred from the camera 10 and the positional information of the images in the RAM in association with the operation of the pickling / cold rolling line 1 (“ Function as data processing means). The image analysis apparatus 11 calculates the position information of each image from the tracking data (the leading end position of the steel strip 9) acquired from the line control computer 14 and the imaging position (fixed value) of the camera 10.

  In step S3, the image analysis apparatus 11 divides the sequentially transferred image (see FIG. 4A) into grid-like segments (see FIG. 4B), and calculates the average density in each segment. Then, an average density difference between adjacent segments is calculated, and when any of the average density differences exceeds a predetermined threshold, it is determined that the image includes a defect, and any average If the density difference does not exceed the predetermined threshold, it is determined that the image does not contain a defect. Note that the density of the image captured by the camera 10 depends on the luminance in the imaging region of the steel strip 9 that is the imaging target. When defects such as wrinkles appear on the surface of the steel strip 9, the luminance of the defective portion is lower than the surroundings, and the density of the defective portion in the image is increased.

  In the example shown in FIG. 4, 疵 16 is included in the image, and the average density of the segment including 疵 16 (the segment indicated by hatching in FIGS. 4C and 4D) is higher than the average density of the surrounding segments. It becomes high and the difference exceeds a predetermined threshold value, and it is determined that the image contains a defect. If it is determined in this step that the image includes a defect, the process proceeds to step S4. If it is determined that the image does not include a defect, the process proceeds to step S6.

  In step S4, the image analysis apparatus 11 stores the image and its position information in association with each other in the hard disk. In step S5, the image analysis apparatus 11 informs the monitoring monitor 13 that the defect has been detected and the position information associated with the image including the defect. An output is displayed and an alarm is sounded by an alarm sound generator (not shown). These indications and ringing alert the line operator that a defect has been detected. On the other hand, in step S6, the image analysis apparatus 11 erases the image determined not to contain a defect from the temporarily stored RAM to save storage resources.

  In step S5, when the line operator is notified of the fact that the defect has been detected and the positional information associated with the image including the defect, the pickling and re-washing is performed by the lie operator before the defect reaches the cold rolling mill 8. The cold rolling line 1 is stopped. And if the defect displayed on the monitoring monitor 13 is confirmed by the line operator and there is a possibility that the confirmed defect may lead to the fracture of the steel strip 9, the site where the defect exists by this line operation (this site is notified). Can be easily identified from the position information) is advanced to the side trimmer facility 6 and the part detected as a defect is visually confirmed. If the cold-rolled steel strip to be produced in the pickling / cold rolling line 1 is to be subjected to side trimming using the side trimmer equipment 6, it is visually inspected whether the defects are removed by the side trimming. If the defect is removed, the operation of the pickling / cold rolling line 1 is resumed. On the other hand, if the defects are not removed by side trimming, and if the cold-rolled steel strip to be produced in the pickling / cold rolling line 1 does not need to be side trimmed, the line operator After only the portion where the defect exists is removed by a hand shear or the like, the operation of the pickling / cold rolling line 1 is resumed.

  Thus, according to the “defect detection method and defect detection system for a steel strip that passes through a cold rolling mill” according to the present embodiment, if the predetermined range of the steel strip 9 includes a defect, Before the defect reaches the cold rolling mill 8, the line operator is informed that the defect is included in the steel strip 9, so that the steel strip 9 is prevented from breaking during cold rolling. can do. Moreover, not only light-transmitting defects but also light-transmitting defects (for example, cracks formed obliquely to the thickness direction of the steel strip, and linear wrinkles in the width direction of the steel strip inside the rolling mill) In this case, defects and gouges that develop into holes due to differences in ductility are also detected and reported, which improves the defect detection rate compared to using a light transmission type defect detector and breaks the steel strip during cold rolling. Can be prevented more reliably.

  In addition, according to the “defect detection method and defect detection system for a steel strip that passes through a cold rolling mill” according to the present embodiment, when defect detection is notified, defect position information is also notified. Therefore, the line operator can easily identify the site where the defect exists. As a result, operations for removing defects can be performed efficiently.

  In addition, according to the “defect detection method and defect detection system for a steel strip that passes through a cold rolling mill” according to the present embodiment, the camera 10 flows on a line between the dryer facility 4 and the side trimmer facility 6. By being installed so as to image the steel strip 9, the image analysis of the steel strip 9 can be performed without being affected by the lubricating oil (cutting oil) adhering to the steel strip 9 in the side trimming process. For example, when an image of the steel strip 9 is taken on the downstream side of the side trimming process and the above-described image analysis is performed based on the image, there is a possibility that the oil adhering to the steel strip 9 is erroneously detected as a defect. However, in this embodiment, since the camera 10 is installed between the dryer facility 4 and the side trimmer facility 6, it is possible to prevent such erroneous detection.

  In the above-described embodiment, the continuous pickling / rolling line of the hot-rolled steel strip has been described as an example. However, the present invention is also applicable when the pickling equipment and the cold rolling equipment are separate lines. The invention can be applied. In this case, it is desirable to install the camera 10 immediately after the dryer facility of the pickling facility line.

  The present invention can be applied to, for example, a pickling / cold rolling line.

DESCRIPTION OF SYMBOLS 1 Pickling / cold rolling line 2 Pickling equipment 3 Rinsing equipment 4 Dryer equipment 6 Side trimmer equipment 8 Cold rolling mill 9 Steel strip 10 High-speed CCD camera 11 Image analyzer 13 Monitor monitor 14 Line control computer 16 制 御 (defect)

Claims (6)

An imaging step of continuously capturing images within the predetermined range from the both side edges of the steel strip flowing on the line of the preceding process from the cold rolling process without omission, and
An image analysis device divides the image obtained by the camera into grid-like segments, calculates the average density in each segment and the difference in average density between adjacent segments, A defect determination step for determining that the image includes a defect when the difference exceeds a predetermined threshold;
A defect notifying step for notifying by the notifying means that a defect has been detected when it is determined by the image analysis device that the image contains a defect;
A method for detecting defects in a steel strip that passes through a cold rolling mill. In the method for detecting defects in a steel strip that passes through the cold rolling mill according to claim 1,
A position information associating step of associating the position information of the image obtained by the camera with the image by the data processing means;
In the defect detection notification step, the notification means notifies the fact that a defect has been detected and the positional information associated with the image including the defect, and the defect of the steel strip that passes through the cold rolling mill, Detection method. In the method for detecting defects in a steel strip that passes through the cold rolling mill according to claim 1 or 2,
The process preceding the cold rolling process includes a pickling process, a rinsing process, a drying process and a side trimming process,
In the imaging step, the camera continuously captures a predetermined range from both side edges of a steel strip flowing on a line between the drying step and the side trimming step without omission. A method for detecting defects in a steel strip that passes through a cold rolling mill. A camera that continuously images within a predetermined range from both side edges of the steel strip flowing on the line of the previous process from the cold rolling process without omission,
The image captured by the camera is divided into grid-like segments, and the average density in each segment and the average density difference between adjacent segments are calculated. An image analysis device that determines that a defect is included in the image when the threshold is exceeded;
Informing means for notifying that a defect has been detected when the image analysis apparatus determines that any image contains a defect;
A defect detection system for a steel strip that passes through a cold rolling mill. In the steel strip defect detection system for passing through the cold rolling mill according to claim 4,
Further comprising data processing means for associating position information in the steel strip of the image obtained by the camera with the image;
When the image analysis apparatus determines that any of the images includes a defect, the notification unit notifies that the defect has been detected and position information associated with the image including the defect; Defect detection system for steel strip passing through a cold rolling mill. In the defect detection system of the steel strip that passes through the cold rolling mill according to claim 4 or 5,
The process preceding the cold rolling process includes a pickling process, a rinsing process, a drying process and a side trimming process,
The cold rolling mill characterized in that the camera continuously images a predetermined range from both side edges of a steel strip flowing on a line between the drying step and the side trimming step without omission. Steel strip defect detection system.