Rotational state evaluation method, method for manufacturing hot-rolled steel sheet, and rotational state evaluation device

Abstract

To provide a technique capable of stably detecting a rotation state of a looper roll 10.SOLUTION: A method for evaluating a rotation state of a looper roll 10 that is a non-driven rotating body arranged between stands of a hot rolling mill 1 to perform tension control of a hot-rolled steel sheet, the method comprising: providing a marking 11 on an end surface of the looper roll 10; continuously imaging a region including the end surface of the looper roll 10; and determining whether the looper roll 10 is in a non-rotation state from two or more images captured at different imaging times during a predetermined time after a tail end portion of the hot-rolled steel sheet passes on the looper roll 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technique for evaluating the rotation state of looper rolls arranged between stands of a hot rolling mill in a hot rolling line. The present invention also relates to a technique for manufacturing a hot-rolled steel sheet that includes the technique for evaluating the rotation state of the looper rolls. [Background technology]

[0002] As a technique for detecting the rotation state of a roll as a non-driven rotating body that rotates at high speed, for example, there is a technique described in Patent Document 1. In Patent Document 1, rolling sounds generated from a rolling mill are collected by a sound collector, and the rolling sound signals converted by the sound collector are passed through an amplifier and a noise removal filter to detect the rotation state of the rolling rolls. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-34147 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 is a technology for detecting the rotation state of a roll in a harsh environment where water, rolling oil, etc. are scattered, but a simpler configuration is desired. Also, the method described in Patent Document 1 cannot be directly adopted to detect the rotation state of a looper roll. Furthermore, the environment of the looper rolls arranged between the stands of the hot rolling mill is also filled with mist-like water droplets and fumes due to the hot-rolled steel sheet being transported.

[0005] The present invention has been made in view of the above points, and one of its objects is to provide a technique that can stably detect the rotation state of a looper roll. [Means for solving the problem]

[0006] In order to solve the problems, one aspect of the present invention is a method for evaluating the rotational state of a looper roll, which is a non-driven rotating body that is arranged between stands of a hot rolling mill and that controls the tension of a hot-rolled steel sheet. The method includes providing a marking on an end face of the looper roll, continuously capturing images of an area including the end face of the looper roll, and determining whether or not the looper roll is in a non-rotating state when the hot-rolled steel sheet is passed from two or more images captured at different times during a predetermined time period after the tail end of the hot-rolled steel sheet has passed over the looper roll. [Effects of the Invention]

[0007] According to an aspect of the present invention, even in an environment filled with mist-like droplets and fumes, the evaluation of the rotation state of a hot-rolled steel sheet during threading is determined based on the roll state of the hot-rolled steel sheet after threading, which is the main cause of these conditions, so that the rotation state of the looper roll can be stably evaluated.

[0008] That is, while a hot-rolled steel sheet is passing over the looper rolls, it is difficult to visually confirm the rotation state due to the presence of mist-like water droplets and fumes. However, after the hot-rolled steel sheet has passed through, the effects of mist-like water droplets and fumes are alleviated. Furthermore, since the looper rolls, which have a smaller diameter than the rolling rolls, rotate at high speed during sheet passing, there is a risk that the position of the marking on the roll end surface cannot be easily and accurately determined. In contrast, according to an aspect of the present invention, under normal conditions, the position of the marking is detected when the non-driven looper roll rotates by inertia after the sheet has passed through. This makes it possible to easily and accurately detect the position of the marking. As a result, according to this aspect of the present invention, it is possible to more stably detect the rotation state of the looper roll. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view showing a hot rolling mill. [Figure 2] FIG. 1 is a side view showing a looper roll disposed between stands of a hot rolling mill. [Figure 3] 1 is a diagram illustrating an example of the configuration of a rotation state evaluation device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a looper roll of a hot finish rolling line will be described as an example. Hot-rolled steel sheets are produced by rolling high-temperature steel materials on a hot finishing rolling line. The hot rolling mill 1 of the hot finishing rolling line of this embodiment is a tandem hot rolling mill, and is configured with a plurality of rows of stands each having a pair of rolls aligned along a pass line PL, as shown in Fig. 1. Fig. 1 illustrates an example in which the mill is configured with seven stands STD1 to STD7.

[0011] Furthermore, as shown in FIG. 2, a looper roll 10 is disposed between each stand. The looper roll 10 adjusts the tension applied to the hot-rolled steel sheet between the stands by rotating and displacing in the vertical direction. In this way, the looper roll 10 controls the tension applied to the hot-rolled steel sheet. The looper roll 10 is a non-driven roll (non-driven rotating body). The looper roll 10 rotates in accordance with the movement (conveyance) of the hot-rolled steel sheet that comes into contact with it. In FIG. 2, reference numeral 12 denotes a looper apron that guides the hot-rolled steel sheet to the looper roll 10. Reference numeral 13 denotes a shaft center, and the looper roll 10 rotates and displaces up and down around this shaft center 13 as the center of rotation. Furthermore, a marking 11 is provided on the outer circumferential side of the end face of the looper roll 10. The marking 11 may be provided at a location where the position along the circumferential direction changes as the looper roll 10 rotates around its axis.

[0012] (Rotational condition evaluation device) As shown in FIG. 3, the rotation state evaluation device of this embodiment includes an imaging unit S1, a tail end passage detection unit S2, a rotation state determination unit S3, and an abnormality notification unit S4.

[0013] <Imaging unit S1> The imaging unit S1 is composed of a camera that continuously captures an image of an area including the end surface of the looper roll 10. In this example, the imaging unit S1 captures an image between the stands so that the entire area of ​​the end surface of the looper roll 10 is positioned therein. As shown in Fig. 1, the imaging unit S1 is provided corresponding to each looper roll 10. The imaging unit S1 continuously captures images at a preset sampling period (imaging period) and outputs the captured images. In this example, it is assumed that the imaging unit S1 continuously captures images at 0.2 second intervals.

[0014] Although the multiple image capturing units S1 do not need to capture images in synchronization, this embodiment assumes that they do. The captured images can also be used for purposes other than the present invention, such as monitoring the status between stands. For example, images captured in synchronization at six locations can be combined into a single image, and the combined image can be displayed on a display in the operator's room. In this embodiment, the imaging unit S1 continuously captures images of the leading edge of the hot-rolled steel sheet from the time it enters the hot rolling mill 1 until it leaves the mill.

[0015] <Tail end passage detection unit S2> The tail end passage detection unit S2 detects that the tail end of the hot-rolled steel sheet has passed over the target looper roll 10 from the image captured by the imaging unit S1. Here, the hot-rolled steel sheet can be identified as an object that is heated and has a red color or the like (hereinafter referred to as red). Therefore, by determining the color of the looper roll 10 in the images continuously supplied from the imaging unit S1, it can be determined that the tail end of the hot-rolled steel sheet has passed over the looper roll 10 when the color changes from red to no longer red.

[0016] <Rotation state determination unit S3> Based on the detection by the tail end passage detection unit S2, the rotation state determination unit S3 acquires images captured by the imaging unit S1 at a determination time, which is a preset time period after the tail end of the hot-rolled steel sheet has passed over the looper roll 10. Then, based on two or more images captured at different times, it is determined whether the looper roll 10 is in a non-rotating state when the hot-rolled steel sheet passes over the looper roll 10. In this example, the determination time is set to a time range from 2 seconds to 5 seconds after the hot-rolled steel sheet has passed over the looper roll 10. Then, it is determined whether or not the looper roll 10 is in a non-rotating state from two or more images captured during that determination time.

[0017] The reason for specifying "up to 5 seconds later" here is that it has been confirmed that when the looper roll 10 is rotating normally, it does not stop rotating by inertia for 5 seconds after the hot-rolled steel sheet has passed. In an actual rolling line, the time during which the looper roll 10 can rotate by inertia after the hot-rolled steel sheet being transported has passed through is determined, and the end time of the judgment time is set within the range in which the looper roll 10 can rotate by inertia. Furthermore, the last image of the two or more images may be the image when the looper roll 10, which had been rotating by inertia, has stopped. However, the images other than the last image of the two or more images are set so that the looper roll 10 is definitely rotating by inertia.

[0018] The reason for the "after 2 seconds" is that, under normal circumstances, the looper roll 10 rotates at a high speed immediately after the hot-rolled steel sheet has passed. If the looper roll 10 rotates at a high speed, there is a risk that the position of the marking 11 cannot be detected accurately.

[0019] The determination of whether the looper roll 10 is in a non-rotating state is made by determining whether the positions of the markings 11 affixed to the looper roll 10 in the end face region of the looper roll 10 differ in the circumferential direction in two images taken within the determination time. However, since it is conceivable that the positions of the markings 11 in the two images may coincide with each other but are shifted by 360 degrees, it is preferable to make the determination using three or more images within the determination time. However, the time intervals for capturing the three or more images are set to be equal.

[0020] In this example, the imaging unit S1 captures images at 0.2 second intervals. However, at 0.2 second intervals, the time intervals between target images are too close. For this reason, in this example, captured images are extracted and used every 0.6 seconds. Note that in this example, the imaging interval itself is not changed to 0.6 seconds because the imaging is also used for purposes other than the present invention. Here, an operator in the operator's room may determine whether the looper roll 10 is rotating or not from the position of the marking 11 on the end face of the looper roll 10, which should be rotating by inertia in the image displayed on the display.

[0021] <Abnormality notification unit S4> When it is determined that the looper roll 10 is not rotating based on the determination by the rotation state determination section S3, the abnormality notification section S4 notifies the detection of an abnormality. The abnormality detection unit notifies an operator in the operator room of the detected abnormality by, for example, displaying a warning on a display or outputting a warning sound. When a warning is displayed on the display, the warning is displayed in the portion of the composite image that captures the looper roll 10 in which the abnormality has been detected.

[0022] (Operation etc.) The non-driven looper roll 10 rotates in accordance with the movement of the steel sheet in contact with it when the steel sheet is threaded. Note that the rotation speed of the looper roll 10 does not have to be the same as the conveying speed of the steel sheet. If the looper roll 10 does not rotate while applying tension to the steel sheet, scratches will continue to be transferred to the lower surface (back surface) of the steel sheet, resulting in scrap being generated from the hot-rolled steel sheet. Therefore, whether the looper roll 10 is rotating or not when the hot-rolled steel sheet is threaded is an important factor in the production of the hot-rolled steel sheet.

[0023] In contrast to this, in the present embodiment, the rotation state of the looper roll 10 is evaluated from changes in a plurality of continuous still images. This makes it possible to suppress the generation of scrap of the hot-rolled steel sheet caused by scratches being continuously transferred to the back surface of the material due to non-rotation of the looper roll 10.

[0024] Furthermore, there is a risk that the position of the marking 11 provided on the end face of the looper roll 10 cannot be accurately detected while the hot-rolled steel sheet is passing over the looper roll 10. In contrast, in this embodiment, the position of the marking 11 in each image is detected when the rotation speed of the looper roll 10 slows down as the hot-rolled steel sheet rotates by inertia after passing over it. This makes it possible to detect the rotation state more accurately.

[0025] (others) The present disclosure may also be configured as follows. (1) Disclosure 1 is a method for evaluating the rotational state of a looper roll, which is a non-driven rotating body arranged between stands of a hot rolling mill to control the tension of a hot-rolled steel sheet, and includes: A marking is applied to the end surface of the looper roll, determining whether or not the looper roll is in a non-rotating state when the hot-rolled steel sheet is threaded based on a circumferential displacement of the position of the marking during a predetermined time period after the tail end of the hot-rolled steel sheet has passed over the looper roll; Rotation condition evaluation method.

[0026] (2) Disclosure 2 continuously captures images of an area including the end surface of the looper roll, determining whether the looper roll is in a non-rotating state from two or more images captured at different times by the imaging; Rotation condition evaluation method. (3) Disclosure 3 reports an abnormality when it is determined that the looper roll is not rotating. Rotation condition evaluation method. (4) Disclosure 4 includes any of the rotation state evaluation methods described above. A manufacturing method for hot-rolled steel sheets.

[0027] (5) Disclosure 5 is a looper roll rotation state evaluation device that evaluates the rotation state of a looper roll, which is a non-driven rotating body, arranged between stands of a hot rolling mill to control the tension of a hot-rolled steel sheet, and includes: A marking provided on the end surface of the looper roll; an imaging unit that continuously images an area including the end surface of the looper roll; a tail end passage detection unit that detects that a tail end of the hot-rolled steel sheet has passed over the looper roll from the image captured by the imaging unit; a rotation state determination unit that determines whether the looper roll is in a non-rotating state or not from two or more images among images captured by the imaging unit during a preset time period after the tail end of the hot-rolled steel sheet has passed over the looper roll based on the detection by the tail end passage detection unit; A rotation state evaluation device comprising: (6) Disclosure 6 further includes an abnormality notification unit that notifies an abnormality detection when the rotation state determination unit determines that the looper roll is in a non-rotating state. Rotational condition evaluation device. [Explanation of symbols]

[0028] 1. Hot rolling mill 10 Looper Roll 11 Marking PL Pass Line S1 imaging unit S2 Tail end passage detection unit S3 Rotation state determination unit S4 Abnormality notification section STD1~STD7 Stands

Claims

1. A method for evaluating the rotational state of a looper roll, which is a non-driven rotating body arranged between stands of a hot rolling mill to control the tension of a hot-rolled steel sheet, comprising: A marking is applied to the end surface of the looper roll, determining whether or not the looper roll is in a non-rotating state when the hot-rolled steel sheet is threaded based on a circumferential displacement of the position of the marking during a predetermined time period after the tail end of the hot-rolled steel sheet has passed over the looper roll; Rotation condition evaluation method.

2. continuously capturing images of an area including the end surface of the looper roll; determining whether the looper roll is in a non-rotating state from two or more images captured at different times by the imaging; The rotation state evaluation method according to claim 1.

3. When it is determined that the looper roll is not rotating, an abnormality detection is notified.

3. The rotation state evaluation method according to claim 2.

4. A rotation state evaluation method according to any one of claims 1 to 3 is provided. A manufacturing method for hot-rolled steel sheets.

5. A looper roll rotation state evaluation device for evaluating the rotation state of a looper roll, which is a non-driven rotating body arranged between stands of a hot rolling mill to control the tension of a hot-rolled steel sheet, comprising: A marking provided on the end surface of the looper roll; an imaging unit that continuously images an area including the end surface of the looper roll; a tail end passage detection unit that detects that a tail end of the hot-rolled steel sheet has passed over the looper roll from the image captured by the imaging unit; a rotation state determination unit that determines whether the looper roll is in a non-rotating state or not from two or more images among images captured by the imaging unit during a preset time period after the tail end of the hot-rolled steel sheet has passed over the looper roll based on detection by the tail end passage detection unit; A rotation state evaluation device comprising:

6. and an abnormality notification unit that notifies of abnormality detection when the rotation state determination unit determines that the looper roll is in a non-rotating state.

6. The rotation state evaluation device according to claim 5.

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