JP4857559B2 - Rollability roll inspection device - Google Patents

Description

  The present invention relates to a steel sheet surface inspection apparatus, and more particularly to a rollability roll defect inspection apparatus for detecting a rollability roll defect in a rolling process of a steel sheet.

Rollability rolls in the steel sheet rolling process are roughly classified into the following.
(1) Indented ridges on the roll, which are transferred as convex ridges on the plate (Type 1)
(2) A foreign matter adheres to the roll, and the foreign matter is pushed directly into the plate during rolling, so that it is transferred to the plate as a concave wrinkle (Type 2)
(3) Due to rough skin of roll (Type 3)
Furthermore, among the types 1 in (1) above, the cause of the dents in the roll is that the tip of the plate hits the roll (type 1a), or that the roll is rolled with a bevel / foreign material in between. There are a wide variety of shapes and degrees, such as (Type 1b), rolled by sandwiching the plate (Type 1c).

  Once such rolls are generated, they are continuously generated until the rolls are replaced, and a large number of defective coils are generated. Therefore, it is very important to quickly find and treat rollable rolls in the rolling process.

  Therefore, after being wound up by a downcoiler, visual inspection is usually performed by sampling. The visual inspection is performed by opening the outermost circumference on the conveyor line by the conveyor, or by paying out only a part of the coil in the inspection line beside the hot rolling line. In the visual inspection, along with full-length wrinkles such as sleeve wrinkles, periodic roll wrinkles are inspected, and when a wrinkle is found, its grade (degree) is determined, and the period is measured. Usually, the grade of the kite is classified into several stages (for example, from the lightest grade A to the heaviest grade D), and if the grade of the grade that is determined is not acceptable for the coil currently rolled, Identify the roll that causes wrinkles, and implement measures such as roll replacement.

  As a method for automatically detecting roll wrinkles, for example, there is a method disclosed in JP-A-6-294759 (Patent Document 1). As shown in FIG. 2, the image of the surface of the metal band 1 captured by the area camera 3 synchronized with the strobe illumination 2 is processed by the image processing device 4 and the arithmetic device 5, thereby causing periodicity defects. Is automatically detected.

Further, in the apparatus disclosed in Japanese Patent Laid-Open No. 2001-221745 (Patent Document 2), as shown in FIG. 3, an optical system is proposed in which the strobe illumination 2 and the area camera 3 are arranged at regular reflection positions. .
JP-A-6-294759 JP 2001-221745 A

  However, in the techniques shown in Patent Document 1 and Patent Document 2, among the grades A to D that have been discovered by the conventional visual inspection, actually, the C to D grades are relatively heavy. There is a problem that it can only be applied to wrinkles, and mild wrinkles of class A to B can hardly be detected. In addition, the detection rate of C-D class soot was not sufficient.

  Further, although Patent Document 1 and Patent Document 2 propose an optical system, the surface properties of the detected wrinkles, the inspection device installation position in the line, etc. are not clarified.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rollability roll defect inspection apparatus that accurately detects a roll defect in a rolling process of a steel sheet from a mild one to a heavy one.

In order to solve the above problems, the present invention has the following configuration.
[1] A rolling roll that includes a light projecting unit that irradiates light on the inspection target surface of the object to be inspected and a light receiving unit that receives reflected light, and the light projecting unit and the light receiving unit cause rolls to be detected. It is a rollability roll wrinkle inspection device that is installed at the rear stage of the roll that rolls down or clamps the object to be inspected in which the roll wrinkle occurs.
Wherein the light projecting section and a light receiving portion disposed downstream of the roll to reduction or clamping the object to be tested is rolling roll flaw inspection apparatus characterized by being arranged in the specular reflection of each other.

[2] In the rollability roll defect inspection apparatus according to [1 ] above,
Further comprising a light projecting unit and a light receiving unit installed in a preceding stage of a roll for pressing or clamping the object to be inspected,
Light projecting portion in-projecting optical unit and a light receiving unit, the rolling roll flaw inspection apparatus and irradiating the light onto the inspection target surface in the width direction oblique from the device under test of the device under test.

[3] In the rollability roll defect inspection apparatus according to [1] or [2] above ,
The rollable roll wrinkle inspection device according to claim 1, wherein the roll to be pressed or pinched is a pinch roll disposed before a downcoiler.

  According to the present invention, it is possible to accurately detect a roll wrinkle in a rolling process of a steel sheet from a mild one to a heavy one.

  The inventors constructed an optical system similar to that shown in FIGS. 2 and 3 as a device for detecting the rollability of roll rolls, and further conducted a roll roll roll detection performance on-line test with the arrangement shown in FIG. Conducted for a period. That is, by using the optical system in which the strobe illumination 2 and the area camera 3 are arranged at regular reflection positions, processing is performed by the image processing device 4 and the arithmetic device 5, thereby confirming whether or not the periodic flaws can be automatically detected. . On the run-out table after the cooling zone 12 between the final stand of the finish rolling mill 11 of the hot rolling line (usually 6 to 8 stands, but only the subsequent 3 stands) and the pinch roll 13 before the downcoiler 14 In addition, a rollability roll flaw detector 15 was installed. The results of this online test were able to detect all D-class and many C-class kites, but the detection rates for A and B were not high.

  Therefore, further investigation was conducted to confirm what kind of rolls could not be detected in the online test. After rolling with a downcoiler, take a sample of the cut surface of the roll wall existing in the outermost part, and perform an offline test by placing the sample on the line-out table during the line pause. It was investigated whether roll wrinkles could be detected under optical conditions.

However, as a result of this investigation, it was found that there was a contradiction in the following points between the on-line measurement result and the off-line measurement result of the cut plate sample that had been cooled and the black skin (oxide film) was formed on the surface. FIG. 9 is a diagram showing an example of the results, which are an offline image (a) and an online image (b) of a cut plate sample.
(1) In the cut plate sample, even if it is slight, wrinkles can be clearly confirmed visually, and even though it can be sufficiently detected by the optical system in FIG. There are cases where is not shown. In the black skin sample, it is roughly divided into a case where the buttocks is “smooth” and a case where it is “smooth”, but the above phenomenon was observed in the “smooth” type.

Among them, in black skin, two types of roll wrinkles, “Smooth” (Class C in FIG. 9A) and “Rough” (Class A in FIG. 9A), are visually and offline images. In some cases, however, only the wrinkles corresponding to “smooth” (class C in FIG. 9B) are observed in the online image.
(2) As for the images that are visible online, the contours of the buttocks appear dark in the black skin sample, and the other central part appears equally bright, whereas the online images appear to be contours. The part located in the light irradiation direction including the light part is bright, and the part opposite to the irradiation direction appears dark (FIG. 9).
(3) Regarding (1) above, it may be possible to see the skin by removing the black skin (oxide film) of the buttocks, so there are two types of “smooth” and “rough” A black skin sample containing roll wrinkles was pickled, and a sample with no black skin was prepared and confirmed. As a result, contrary to the online image, the “smooth” sample became difficult to see, and the “rough” sample remained visible, and the above contradiction could not be explained.

  Therefore, the black skin sample was further observed with an optical microscope. As the observation method, both bright field conditions (normal epi-illumination) and dark fields (side illumination with external light irradiated from the side) were performed. As is well known, a horizontal surface is brightly observed under the bright field condition, and an oblique surface where the light source position and the observation position are in a regular reflection relationship is brightly observed under the dark field condition.

  An example of the result is shown in FIG. The heel part of the “smooth” sample was observed to be uniformly bright with epi-illumination and uniformly dark with side-illumination, and it was found that the heel part was composed of a surface having an angle close to horizontal. In addition, the bright part of the sample of “Zaraza” has bright stripes observed in both the epi-illumination and the side-illumination, so that it can be seen that it is composed of jagged surfaces continuous in the longitudinal direction.

  From the above, although it has a convex shape on the run-out table, it is considered that the surface is crushed for some reason when it is wound by a downcoiler. And it also occurs on the outermost front surface wound by the downcoiler (that is, it does not rub against the plate) and between the downcoilers from the equipment installation position after the final finishing roll The reason is considered to be the pinch roll before the downcoiler because there is no contact with the surface other than the pinch roll before the downcoiler.

    FIG. 4 shows a soot generation model that can be considered from the above consideration. Immediately after rolling with a rolling roll formed with a dent for some reason, it has a mountain shape as shown in FIG. And when passing through the pinch roll before the downcoiler, the roll eyes are transferred by rubbing against the pinch roll. If the unevenness is low, only the highest part of the roll eyes hits and the roll eyes remain clearly. However, if the unevenness is high, various roll eyes hit randomly, resulting in a flat surface (b). It is just like the situation observed in a thin wheel grinding test.

  Further, when pickling, all black skin is removed and the influence of the color of the surface is removed, but the shape is basically the shape of (b) although it is slightly damaged by acid. As a result, on the contrary, the case of “low convexity” in which the roughness of the collar portion / base material portion is greatly different becomes more conspicuous (c), and the above-described phenomenon can also be explained.

  From the above, when considering an optical system for detecting these wrinkles, first, when installing after a pinch roll before downcoiler, the presence or absence of wrinkles can be determined by whether or not there is a flat portion. It is considered that the specular reflection optical system that can detect the most part most easily is the optical system that is most likely to detect wrinkles.

  Also, when installing an optical system between the final stand of the finish rolling mill and the pinch roll before the downcoiler, the diffuse reflection optical system that detects the convex slope is removed from the regular reflection for the presence or absence of wrinkles. Is considered desirable. However, how much or in which direction it should be excluded from regular reflection depends on the shape of the target population to be detected.

In order to confirm the above fact, a confirmation experiment was conducted.

  First, assuming that it was installed after the pinch roll, using a cut plate sample collected with a downcoiler, using the optical system of the configuration shown in FIG. 2, the projection angle is set to 20 °, the light reception angle is changed S / N was evaluated. FIG. 5 is a diagram showing this result. Confirm that the S / N is good when the receiving angle is 20 °, which is the same as the projection angle, that is, the specularly reflected light receiving optical system has the best S / N. Confirmed that it was possible to do.

  Next, a conventional optical system as shown in FIG. 6A (light projection angle: 20 ° in the longitudinal direction, light receiving angle: 0 °), and a diffused light receiving optical system as shown in FIG. Light projection angle: 20 ° in the width direction, light reception angle: 0 °), a specular reflection light receiving optical system (light projection angle: 20 ° in the longitudinal direction, light reception angle: 20 °) as shown in FIG. They were constructed and installed for a certain period of time, and an online roll flaw detection performance evaluation was conducted.

  At that time, the resolution in the width direction is unified to 0.5 mm and the resolution in the longitudinal direction is unified to 1 mm, and the light source is a xenon strobe light source with a light emission time of 20 μsec, and an image is captured every 1/120 sec with a quadruple speed area camera. So, the conditions were unified.

  The detection result is shown in FIG. As is apparent from the figure, the detection performance is best when irradiation is performed in the width direction of (b), and it can be seen that almost all wrinkles can be detected for class B to class D. In addition, the class A wrinkles that could not be detected were recognized by visually observing the images.

  In addition, in each case of FIG. 7, comparing the detected wrinkles with the wrinkles that could not be detected, type 1a (due to the tip of the plate hitting the roll) and type 2 (foreign matter adhering to the roll) In addition, it was found that in any case, the foreign matter was transferred to the plate as a concave wrinkle when the foreign matter was pushed directly into the plate during rolling. Since these wrinkles have a relatively large unevenness, it is considered that they were detectable under any conditions.

  Conversely, the wrinkles that could not be detected in FIGS. 6 (a) and 6 (c) are type 1b (due to rolling with a bevel / foreign material etc.) and type 1c (with a plate aperture in between). It belongs to the thing by rolling. As shown in FIG. 8, these scissors have the feature that the convex amount is relatively small, and the causative one (heuge or aperture) is long in the longitudinal direction. Therefore, it is considered effective to illuminate in the width direction where the shape change is relatively large.

  In addition, while the projection and reception angles were swung in the longitudinal direction in the range of 0 to 10 ° under the conditions of FIG. 6B, there was no significant difference in detection performance, and it was essential to project in the width direction. It was confirmed that Further, when the light receiving angle was set to 20 ° and the specular reflection condition was obtained, the same result as in FIG. 7C was obtained, and it was confirmed that the diffuse reflection condition was important.

  As described above, the description has been made on the hot rolling of the steel sheet, but the present invention is applicable to the entire rolling process regardless of the material and hot / cold.

It is a figure which shows an example of arrangement | positioning of the apparatus for implementing this invention. It is a figure which shows schematic structure for enforcing the method disclosed by patent document 1. FIG. It is a figure which shows schematic structure of the apparatus disclosed by patent document 2. FIG. It is a figure explaining the production | generation model of a cocoon. It is a figure which shows the S / N evaluation result at the time of changing a light-receiving angle. It is a figure which shows the difference in the optical system used by roll wrinkle detection performance evaluation. It is a figure which shows the wrinkle detection result by the difference in an optical system. It is a figure explaining the profile of a heel (thing derived from a baldness or a diaphragm). It is a figure which shows an example of the offline image (a) and online image (b) of a cutting board sample. It is a figure which shows an example of the observation result by the optical microscope of a black skin sample.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal strip 2 Strobe illumination 3 Area camera 4 Image processing device 5 Arithmetic device 11 Finishing rolling mill 12 Cooling zone 13 Pinch roll 14 Downcoiler 15 Rollability roll defect inspection device

Claims (3)

Provided with a light projecting unit for irradiating light on the surface to be inspected of the object to be inspected and a light receiving unit for receiving the reflected light, the light projecting unit and the light receiving unit are located after the rolling roll causing the roll wrinkle to be detected. And, it is a rollable roll wrinkle inspection device installed at the subsequent stage of the roll that rolls down or clamps the object to be inspected in which roll wrinkles have occurred,
Wherein the light projecting section and a light receiving portion disposed downstream of the roll to reduction or clamping the object to be tested is rolling roll flaw inspection apparatus characterized by being arranged in the specular reflection of each other. In the rolling roll roll inspection apparatus according to claim 1,
Further comprising a light projecting unit and a light receiving unit installed in a preceding stage of a roll for pressing or clamping the object to be inspected,
Light projecting portion in-projecting optical unit and a light receiving unit, the rolling roll flaw inspection apparatus and irradiating the light onto the inspection target surface in the width direction oblique from the device under test of the device under test. In the rollability roll wrinkle inspection device according to claim 1 or 2,
The rollable roll wrinkle inspection device according to claim 1, wherein the roll to be pressed or pinched is a pinch roll disposed before a downcoiler.