JP7772022B2 - Winding position control method, winding device, and steel sheet manufacturing method - Google Patents

Description

The present invention relates to a winding position control method for controlling the stopping position of the tail end when winding a steel sheet to form a coil, as well as to a winding device and a method for manufacturing a steel sheet using the winding position control method.

In the coiler of a hot strip mill, the finished rolled steel strip, which is the hot rolled steel strip fed from the pinch rolls, is typically wound around a mandrel to form a coil, and at the end of the winding, a fixed position stopping control is performed on the tail end of the finished rolled steel strip.

Without this type of tail end fixed position stopping control, the position of the tail end of the finish-rolled steel strip on the outer circumference of the coil will not be aligned for each coil, and if the coil is simply unwound from the coiler mandrel and transported to the coil yard, the tail end may come into contact with other equipment or coils during transport, which could, in the worst case scenario, result in damage to the equipment or the coil itself. For this reason, without tail end fixed position stopping control, manual intervention by the coiler operator is required from the end of coiling until the start of unwinding, leading to an increased workload.

Therefore, in order to solve these problems, a tail end stopping technique for coil winding has been proposed.
Patent Document 1 discloses a technology for determining the tail end position by grasping and controlling the shape of the tail end using sensors installed in front of a winding device, one at the center in the width direction and one or more on both sides. Specifically, the objective of the present invention is to provide a method and device for detecting the tail end of a rolled material that can accurately detect the tail end regardless of the tail end shape of the rolled material. The method for detecting the tail end of a rolled material involves arranging HMDs (thermal mass detectors) in a line in the width direction of the rolled material being wound onto a winding machine of a rolling mill at the center and on both sides of the conveying path, and detecting the tail end position of the rolled material based on the timing at which all of the HMDs switch from ON to OFF during conveyance of the rolled material.

Patent Document 2 also discloses a technology for correcting and controlling the tail end detected by a laser sensor inside the winding device backward using the coordinates of a two-dimensional shape meter installed in a hot strip mill. Specifically, the objective is to provide a winding control method and winding control device that can perform high-precision, inexpensive tail end fixed-position stopping control by referencing the two-dimensional shapes of the leading and trailing ends of a roughly rolled steel strip output by a crop shape meter. The tail end position at the width center in the two-dimensional shape of the tail end of the roughly rolled steel strip output by the hot strip crop shape meter is compared with the crop cut position. If the tail end position at the width center is closer to the leading end of the rough rolled steel strip than the crop cut position, the tail end position at the width center detected by an on-board laser sensor on the pinch roll outlet side of the hot strip mill is corrected backward from that position, and the tail end of the finish rolled steel strip is stopped in a fixed position based on the corrected tail end position.

Japanese Patent Application Publication No. 11-254034 JP 2013-94798 A

However, when attempting to apply the above-mentioned conventional technology to tail end stop control during coil winding of steel strips, the following problems arise:

The technologies described in Patent Documents 1 and 2 utilize a sensor installed upstream of the winding device in the direction of steel strip travel to predict the tail end shape and are capable of stopping the tail end at a target angle. However, they do not have a function to correct the tail end shape prediction if it is incorrect due to the sensor position, strip deflection, strip warp, steam, etc.
Therefore, if the steel strip stops at a position other than the target position, the cost of modifying the equipment becomes high, and the operation of the steel heating furnace must be stopped while the equipment is being modified, which results in a large opportunity loss and is not economical.

The present invention was developed in consideration of the above-mentioned problems with the prior art, and its purpose is to provide a winding position control method, a winding device, and a steel sheet manufacturing method using this control method, which installs a video camera on the winding device side and uses image analysis to output information about the moment the tail end of the steel strip separates from the wrapper roll to a tail end stop controller, thereby stopping the winding coil at a specified rotation and rotation angle, thereby improving the accuracy of winding position control.

The winding position control method of the present invention, which advantageously solves the above problem, is configured as follows.

[1] A winding position control method for controlling the winding position of the tail end of a steel strip when the steel strip is wound into a coil on a mandrel, the winding position control method including: a camera photographing step for photographing the winding of the steel strip in a winding device with a camera; an image analysis step for analyzing the photographed image; a tail end position determination step for identifying the moment when the tail end of the steel strip separates from the wrapper roll by analyzing the image; and a winding position control step for outputting information obtained from the tail end position determination step to a stop controller and controlling the rotation and rotation angle of the winding coil so that the rotating winding coil stops at a target position after the tail end of the steel strip separates from the wrapper roll.
[2] In the above [1], the image analysis step is a winding position control method in which analysis is performed based on color differences in the captured image.

A method for manufacturing a steel sheet using a winding device and a winding position control method according to the present invention, which advantageously solves the above problems, is configured as follows.
[3] A winding device for winding a steel strip around a mandrel into a coil, the winding device comprising: a camera photographing unit that photographs the winding of the steel strip in the winding device with a camera; and an image analysis unit that analyzes the photographed image.
This winding device is equipped with a tail end position determination unit that identifies the moment when the tail end of the steel strip separates from the wrapper roll by analyzing an image, and a winding position control unit that controls the rotation and rotation angle of the winding coil based on the information obtained by the tail end position determination unit so that the rotating winding coil stops at a target position after the tail end of the steel strip separates from the wrapper roll.
[4] In the above [3], the image analysis unit is a winding device that performs analysis based on color differences in the captured image.
[5] A method for producing a steel sheet, including a hot rolling step using the coiling position control method according to [1] or [2] above.

This invention makes it possible to identify and stop the tail end position of a steel strip during coil winding without being affected by the tail end shape of the steel strip, the running conditions inside the winding machine, or the atmosphere, thereby reducing the risk of the tail end of the steel strip interfering with other equipment when the coil is removed from the mandrel.

1 is a schematic diagram illustrating an example of an outline of a hot rolling line equipped with a winding machine (winding device) for a hot rolled steel strip according to the present invention. 1 is a structural diagram of a winding device for the tail end of a steel strip according to one embodiment. FIG. (a) is a schematic diagram of the camera photographing method before image analysis before the tail end of the steel strip passes through the wrapper roll, and (b) is a schematic diagram of the camera photographing method during image analysis after the tail end of the steel strip passes through the wrapper roll. FIG. 10 is an explanatory diagram of the coiler angle as viewed from the side of the coil in controlling the winding position of the tail end of the steel strip.

An outline of the hot rolled coil manufacturing method according to this embodiment will be described.
The hot strip mill of this embodiment shown in Figure 1 is a schematic diagram showing the outline from the heating furnace 1 to the coiling device. A rough bar 20 rolled by a roughing mill 2 is rolled by a finishing mill 4. A steel strip 21 rolled by the finishing mill is sprayed with cooling water on a hot run table, and while sufficient tension is applied in a coiler 4, the tail end of the steel strip is detected by a laser meter 5 installed in the coiler, and the tail end 6 is stopped at approximately the 9 o'clock position, and calculations for tail end control are performed. After calculations are completed, the coil is rotated again, and fixed-position stopping control is performed so that the tail end is stopped at the target coiling position.

First, the steel strip winding device according to this embodiment will be described.
<Take-up device>
The steel strip winding device of this embodiment is a winding device that includes a camera photographing unit that photographs the winding of the steel strip inside the winding device with a camera, an image analysis unit that analyzes the photographed image, a tail end position determination unit that identifies the moment when the tail end of the steel strip separates from the wrapper roll through image analysis, and a winding position control unit that controls the rotation and rotation angle of the winding coil based on the information obtained by the tail end position determination unit so that the rotating winding coil stops at the target position after the tail end of the steel strip separates from the wrapper roll.

Figure 2 shows a schematic diagram of the coiling device of a hot strip mill.
A camera 9 is positioned facing the inside of the winding device. The image from the camera is analyzed by an image analysis unit. A tail end position determination unit is provided that identifies the moment when the tail end of the steel strip separates from the wrapper roll 7 through image analysis. The image analysis unit and the tail end position determination unit can utilize, for example, an analytical PC 10. The winding position control unit is composed of a process computer 12 that performs calculations to control the stopping position of the tail end of the steel strip based on the image analysis results, a PLC 13 that performs control to wind the tail end of the steel strip and stop it at the target position, and a rotary motor 14. Note that the components of the winding device according to the present invention are not limited to these devices, and may be any device that has the function of implementing the present invention.

<Winding position control method>
The method for controlling the winding position of the tail end of a steel strip according to this embodiment includes a camera photographing step of photographing the winding of the steel strip in the winding device with a camera, an image analysis step of analyzing the photographed image, a tail end position determination step of identifying the moment when the tail end of the steel strip separates from the wrapper roll through image analysis, and a winding position control step of outputting information obtained from the tail end position determination step to a stop controller and controlling the rotation and rotation angle of the winding coil so that the rotating winding coil stops at the target position after the tail end of the steel strip separates from the wrapper roll.

As shown in Figure 2, the winding of the steel strip is controlled by turning on/off a laser meter 5 installed in the winding device M to temporarily detect the tail end of the steel strip, and the tail end 6 of the steel strip is controlled to stop, for example, at approximately the 4 o'clock position in Figure 4.
Here, once the tail end of the steel strip passes through the pinch roll (not shown) located before being wound by the winding machine, the door-type arm covering the side of the coil (coil end surface) is opened so that images can be taken inside the winding device.

[Camera shooting steps]
When the tail end of the steel strip passes through the wrapper roll 7 and falls away from the coil surface, the inside of the winding device is photographed with a video camera 9 in an environment sufficiently illuminated by lighting 8. It is preferable to photograph the coil surface portion from the side of the coil (coil end surface).

[Image analysis step]
The video image is taken into the image analysis PC 10 and image analysis is performed.
The image is preferably of the side surface of the coil (coil end surface), includes the coil surface layer, and has a field of view that is 1/4 of the entire field of view of the coil side surface.

[Tail tip position determination step]
The image captured by the image analysis PC 10 is quantified in the L*a*b* color system. The falling of the coil tail end is determined based on the color difference between the color of the winder housing 11 before the tail end separates from the coil surface and opens, and the color of the coil tail end 6 that blocks the housing after separation, and a fall determination signal is output to the process computer 12.
Here, the color difference is determined based on the luminance.
If the difference in brightness between the brightness of the winder housing before the tail end opens and the brightness of the coil tail end blocking the housing after it separates is 0.1 cd/ ^m2 or more, it is determined that the coil tail end is present at that position.

In addition to image analysis based on color differences in the video camera's L*a*b* color system, other image analysis methods may also be used, such as RGB color differences using a video camera, binarization, identifying the tail tip position using machine learning, and identifying the tail tip based on brightness differences as the tail tip blocks light by drooping.

[Winding position control step]
The process computer 12 outputs a signal for determining whether the tail end of the coil has fallen to a PLC (stop controller) 13. After receiving the fall determination signal, the PLC (stop controller) 13 calculates the rotation and rotation angle of the coil to the target position where it will rotate and stop, and controls the position of the motor 14 based on the winding speed and the number of motor pulses, thereby stopping the tail end at the target position.

Figure 3 shows a schematic diagram of the moment when the tail end separates from the coil surface. The side of the coil (coil end surface) is viewed obliquely. (a) shows the subject photographed by the camera before the tail end of the steel strip passes through the wrapper roll (before image analysis), and (b) shows the subject photographed by the camera after the tail end of the steel strip has passed through the wrapper roll (during image analysis).
Before analysis (a), the video camera captured the housing inside the winding machine, but during analysis (b), the tail end of the coil hides the housing, so the video camera captures the inside of the coil. The coil falling is determined by judging the color difference between the housing and the inside of the coil from the image.

Figure 4 shows the coiler angle position. Angle α is the angle at which the tail end opens from the wrapper roll when the top surface of the coil is set as the reference angle of 0 degrees. Angle β is the angle rotated during the combined image analysis processing time and transmission time to the PLC (stop controller). Angle θ is the equipment position angle from the wrapper roll to the target position.

A chart of tail end control is shown in Figure 5. The angle β is expressed by the following formula, where t is the total time of image analysis processing time and transmission time, and ω is the angular velocity of the coiler.
Since the angle θ is a known equipment position angle from the wrapper roll to the target position, the mandrel is rotated by (θ-β) degrees from the time the tail end stop controller receives the signal, thereby controlling it to the target equipment position angle θ.

The effects of this embodiment will be specifically described below based on examples, but the present invention is not limited to these examples.
As an embodiment of the present invention, an example in which the present invention is applied to a coiler of a hot rolling line for producing hot-rolled steel sheets as shown in FIG. 1 will be described.
The slabs were heated to a predetermined extraction temperature in a heating furnace, and then rough rolled and finish rolled in a hot rolling line to produce hot rolled steel strips.
The hot-rolled steel strip was then wound around a mandrel to form a coil. The winding of the steel strip in the winding device was photographed with a camera, and the color difference of the photographed image was analyzed to identify the moment when the tail end of the steel strip separated from the wrapper roll.
Image analysis information at the moment the steel strip separated from the wrapper roll was output to a stop controller, and the rotation and rotation angle of the winding coil were controlled so that the tail end of the steel strip would stop at the target coiler angle position (α = 40°, θ = 95°).

As a comparative example, a sensor installed upstream of the winding device was used to predict the tail end shape and control the tail end of the steel strip to stop at the target coiler angle position (α = 40°, θ = 95°).

The standard deviation of the final tail end stop angle for the example of the present invention improved from 25 degrees to 10 degrees compared to the comparative example.

M Winding device D Winding rotation direction 1 Heating furnace 2 Roughing rolling mill 3 Finishing rolling mill 4 Winding machine 5 Laser meter 6 Coil tail end 7 Wrapper roll 8 Lighting 9 Video camera 10 Image analysis PC
11 Housing 12 Process computer 13 PLC (stop controller)
14 Motor 15 Mandrel 21 Steel strip

Claims (5)

A winding position control method for controlling the winding position of a tail end of a hot rolled steel strip when winding the steel strip around a mandrel to form a coil, comprising:
a start step of opening the side so that images inside the winding device can be taken from the time when the tail end of the steel strip passes through a pinch roll arranged before winding by a winding machine;
a camera photographing step of photographing the winding of the steel strip in the winding device with a camera;
an image analysis step of analyzing the captured image;
a tail end position determining step of identifying the moment when the tail end of the steel strip separates from the wrapper roll by analyzing the image;
a winding position control step of outputting information obtained from the tail end position determination step to a stop controller and controlling the rotation and rotation angle of the winding coil so that the rotating winding coil stops at a target position after the tail end of the steel strip has separated from the wrapper roll;
A winding position control method comprising: The winding position control method described in claim 1, characterized in that the image analysis step performs analysis based on color differences in the captured image. A winding device for winding a hot-rolled steel strip around a mandrel into a coil,
a camera photographing unit that photographs the winding of the steel strip in the winding device with a camera;
an image analysis unit that analyzes the captured image;
a tail end position determining unit that identifies the moment when the tail end of the steel strip separates from the wrapper roll by analyzing the image;
a winding position control unit that controls the rotation and rotation angle of the winding coil based on the information obtained by the tail end position determination unit so that the rotating winding coil stops at a target position after the tail end of the steel strip has separated from the wrapper roll;
Equipped with
The winding device is configured so that the side of the winding device opens so that images of the inside of the winding device can be taken from a camera unit arranged outside the winding device . The winding device described in claim 3, wherein the image analysis unit performs analysis based on color differences in the captured image. A steel sheet manufacturing method including a hot rolling process using the winding position control method described in claim 1 or 2.