JP2002028764A - Method and device for observing break-out in continuous casting of steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an observing method and its device for surely predicting break-out by continuously observing a surface temperature and a surface characteristic of a slab drawn out from a mold, in a continuous casting of steel. SOLUTION: The surface temperature and/or the surface characteristic of the slab drawn out from the mold, are continuously observed with a CCD camera fitted with a relay lens having a pin hole at the tip part and the break-out is peculiarly produced by detecting an abnormality in the detected surface temperature and/or the surface characteristic. This device is constituted by containing a picture monitor displaying a video signal showing the surface characteristic of the slab separated from the video signal obtained with the CCD camera disposed just below the mold, a picture processor converting a luminance signal for measuring the surface temperature separated from the video signal obtained with the above CCD camera into a temperature picture, a picture monitor displaying a temperature picture and a picture recording device for continuously recording by inputting the temperature picture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for monitoring breakout in continuous casting of steel.

[0002]

2. Description of the Related Art As shown in FIG.
The molten steel flows from the ladle through the tundish into the mold, cools in the mold (mold), and is cooled by spraying cooling water from a cooling water spray tube below the mold,
This is performed by pulling out the formed slab with a pinch roll. Normally, the slab drawn directly below the mold has a solidified surface, as shown in FIG. 9, but unsolidified molten steel exists inside the slab. If the shell is pulled out while the shell is not yet developed, or if the friction between the mold and the shell is large and an excessive frictional force acts on the shell, the shell often breaks and molten steel flows out, so-called breakout occurs.

[0003] When a breakout occurs, a large amount of molten steel flows around the continuous casting machine, which hinders the operation. For this reason, there has been a demand for the establishment of technology for predicting breakouts in continuous casting of steel.
The environment directly below the mold where the breakout occurs is high temperature and a large amount of cooling water is injected into the slab, and it is difficult to attach a monitoring device to such a part. It has not been developed yet.

Until now, attempts have been made to foresee a breakout by mounting a large number of radiation thermometers and measuring the temperature of the slab. However, it is difficult to manage the thermometer, and only the temperature at a point is measured. It is difficult to put it into practical use due to insufficient prediction data, and attempts were made to apply an ultrasonic sensor to measure the thickness of the shell.
Similarly, in the measurement of points, there was insufficient data for predicting breakout, and it had not been put to practical use.

[0005] In an environment immediately below a mold in a high-temperature atmosphere and a large amount of cooling water is injected into a slab,
As a result of various tests and examinations on a measurement method that can accurately measure the surface temperature of the slab drawn from the mold and clearly capture the surface properties of the slab, a CCD camera with a relay lens with a pinhole at the tip It has been found that the use of the slab enables accurate monitoring of the surface of the slab even in an environment with a poor view of water and smoke.

[0006]

SUMMARY OF THE INVENTION The present invention has been made as a result of further study of the device configuration based on the above-mentioned findings, and an object of the present invention is to accurately set a breakout in continuous casting of steel. It is an object of the present invention to provide a method and an apparatus for monitoring breakout in continuous casting of steel, which enable prediction.

[0007]

According to a first aspect of the present invention, there is provided a method for monitoring breakout in continuous casting of steel according to the present invention, wherein a relay lens having a pinhole at a tip is provided in continuous casting of steel. CC attached
The D camera continuously monitors the surface temperature and surface properties of the slab drawn from the mold, and predicts a breakout by detecting the detected surface temperature and / or surface property abnormality. And

According to a second aspect of the present invention, there is provided a method for monitoring breakout in continuous casting of steel according to the first aspect, wherein the temporal change of the surface temperature is compared with a previously detected surface temperature change with time in normal casting. By doing so, a breakout is predicted.

According to the third aspect of the present invention, there is provided a method for monitoring breakout in continuous casting of steel.
A luminance signal separated from a video signal obtained by the CCD camera is converted into a temperature image by image processing, and a specific temperature is selected from the temperature image as a breakout signal, and a change in the selected specific temperature is changed. And predicting a breakout by monitoring.

According to a fourth aspect of the present invention, there is provided an apparatus for monitoring breakout in continuous casting of steel, which predicts a breakout in continuous casting of steel. CCD camera equipped with a relay lens having a pinhole at the tip for continuously monitoring the surface texture,
An image monitor for displaying a video signal indicating a surface property of the slab separated from a video signal obtained by a CD camera; a luminance signal for measuring the surface temperature separated from the video signal obtained by the CCD camera to a temperature image; It is characterized by including an image processing device for conversion, an image monitor for displaying a temperature image, and an image recording device for inputting and continuously recording a temperature image.

According to a fifth aspect of the present invention, there is provided a breakout monitoring apparatus for continuous casting of steel according to the fourth aspect, wherein the image monitor for displaying the temperature image comprises: It is characterized by comprising an image monitor for displaying a specific temperature in time series.

According to a sixth aspect of the present invention, there is provided a breakout monitoring device for continuous casting of steel according to the fourth or fifth aspect, wherein a purge gas is jetted from the pinhole to prevent contamination of a relay lens lens and cool the lens. Thus, a clear image of the slab surface can always be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the important components of the breakout monitoring system in the continuous casting of steel according to the present invention is that a relay having a pinhole at a tip for monitoring the surface of a slab to be cast. The point is that a CCD camera equipped with a lens is used. In the chamber just below the bad mold (mold), the above-mentioned black-and-white or color CCD camera, preferably a color CCD camera, is installed to accurately measure the surface temperature by monitoring the surface of the slab drawn from the mold; The surface properties can be grasped.

[0014] Immediately below the mold, a pinch roll roll stand and a water cooling pipe intersect in a complicated manner, and cooling water is sprayed on the rolls and the slab, so that smoke is trapped in the chamber, so that the field of view is extremely poor. In such an environment,
If the surveillance camera is placed away from the surface of the slab, the piping will obstruct the view, and a large amount of cooling water will obstruct the view. Therefore, to monitor the slab surface, the camera must be brought close to the slab surface.

For this purpose, a surveillance camera in which a relay lens having a pinhole at the tip is attached to the CCD camera is preferable, and both protection of the camera and securing of the field of view can be achieved. As shown in FIG. 1, a relay lens 10 attached to a CCD camera 2 obtains an image of an object through a small pinhole 11 provided at the tip.
Since a wide viewing angle of about 100 deg can be obtained by designing the objective lens 12, even if the tip of the relay lens 10 is brought close to the slab surface, a wide area of the surface can be included in the field of view. Therefore, it is preferable to use a wide-angle lens as the objective lens 12. 13 is a relay lens 10
Protection pipe.

FIG. 2 shows the above C for monitoring the slab surface.
This shows an example of the arrangement of the CD camera 2, wherein a gas introduction hole 14 is provided in the relay lens 10, and a purge gas is ejected from a pinhole at the tip of the relay lens 10.
Even when the tip of the lens is brought close to the slab, the cooling effect of the relay lens 10 is maintained, and at the same time, dust and water drops around the relay lens are blown off, so that the lens can always be kept clean.

Since the relay lens 10 is thin, the relay lens can be inserted through a narrow gap between hoses and pipes in the chamber, and the main body of the CCD camera 2 is separated from the slab surface as shown in FIG. The camera body can be protected even if a breakout occurs.

Another important configuration in the present invention is a CCD.
A luminance signal and a video signal, preferably a color video signal from a color CCD camera, are separated from the video signal of the camera, and the surface properties of the slab are detected from the video signal, and the surface temperature (distribution) of the slab is measured from the luminance signal. That's what we did.

When the CCD camera 2 is, for example, of the NTSC standard, as shown in FIG. 3, an RGB signal, which is a color video signal, is output by a Y / C separation function.
A Y / C luminance signal, which is a luminance signal, can be taken out simultaneously.

The RGB signals are used as signals for monitoring the slab surface, and are displayed on an image monitor as they are. From the image of the slab surface, it is possible to monitor the powder flowing down on the slab surface and the degree of cooling water applied.If the powder flowing down is uneven, the contact state between the mold inner wall and the slab is not stable and excessive tensile force is applied. Is acting on the shell of the solidified slab, which is a warning signal for breakout.

The Y / C luminance signal is a signal for temperature measurement,
Input to the image processing device. In the image processing device, the Y / C
The luminance signal changes to a temperature (distribution) image of the slab surface.
From the temperature distribution on the slab surface, it is possible to monitor the thickness of the shell formed by solidification of the molten steel.If the temperature on the slab surface is locally high, the shell thickness is insufficient at that part In addition, there is a danger of breakout at high temperatures due to the low strength of the shell. Specifically, attention is paid to a specific temperature in the temperature image, for example, a temperature corresponding to the highest luminance, a temperature of a slab edge portion where breakout is likely to occur, and one or two of these specific temperatures
One or more can be used as a breakout signal and the change can be monitored to predict a breakout.

In the present invention, a breakout can be predicted from the surface temperature distribution of the slab. That is, as described above, the luminance signal is used as a temperature measurement signal, which is image-processed into a temperature (distribution) image,
This temperature distribution is continuously recorded, the temperature distribution before the current time and the temperature distribution before a certain time are compared, and the part where the current temperature distribution rises by a certain level or more from the temperature distribution image before the certain time before is extracted. Predict breakouts from the degree of climb.

The surface temperature of the slab is as shown in FIG.
It is highest immediately after starting the injection from the ladle through the tundish into the mold, and then gradually decreases. Since the injection temperature into the mold differs depending on the steel type, the temperature change of the slab surface temperature is different depending on the steel type, but in the normal state, the surface temperature is the same in that it has a temperature change pattern that decreases over time, If the current temperature (distribution) is higher than the temperature (distribution) before a certain time, a breakout alarm may be issued, and the change in the slab surface temperature over time and the temperature change pattern due to the steel type are detected in advance. You can know the abnormal temperature without leaving.

Further, in the present invention, it is an important feature that the surface image and / or the temperature image of the slab are repeatedly recorded at a constant period. If a breakout occurs due to the recording of this surface image or temperature image,
The surface properties and temperature distribution of the slab can be accurately reproduced by going back to a certain time in the past corresponding to one cycle from that point, and it is possible to know a predictive phenomenon of breakout.

[0025]

Embodiments will be described below. This example shows one embodiment of the present invention, and the present invention is not limited to this.

Embodiment 1 An embodiment of a breakout monitoring device which mounts a monitoring camera immediately below a mold of a continuous casting machine, detects a surface temperature distribution and surface properties of a slab, and predicts a breakout will be described.

As shown in FIG. 5, two color CCD cameras 2A and 2B with a relay lens for monitoring the slab S descending from the mold from both sides are provided immediately below the mold. The length of the relay lens is 900 mm, the distance from the lens tip to the slab surface is 150 mm, and the diameter of the relay lens is 4
A protective pipe having a diameter of 5 mm and a diameter of 65 mm is attached to the outside thereof. RGB3CCD as CCD camera
Use the element type. The three-element CCD camera
The image is beautiful, and the dynamic range of the luminance signal (the ratio between the minimum value and the maximum value of the luminance signal voltage) is about 60 dB (more than 10 dB wider than that of a normal CCD camera), and a level equivalent to that of a monochrome camera can be obtained. Therefore, it is suitable for temperature distribution measurement.

The CCD cameras 2A and 2B are attached to a support of a roll stand of a pinch roll of a continuous casting machine (details of attachment are not shown). The CCD camera can be easily attached and detached when maintenance, inspection, and repair of the roll stand are performed. Also, C
In the CD cameras 2A and 2B, a purge gas is blown out from a pinhole to prevent the lens of the relay lens from being stained, and a clear image of the slab surface can always be obtained by cooling the lens.

FIG. 6 shows the configuration of the monitoring device. As shown in FIG. 6, video signals from the two CCD cameras 2A and 2B are introduced into the monitoring device 1 through a terminal block 9 and a video cable, and RGB signals among the video signals are connected to the image monitor 4, Used for video surveillance of slab surface. The Y / C signal is input to the image processing device 3 and converted into a temperature distribution image. The temperature distribution image is further converted into a pseudo color signal and displayed on the image monitor 4.

The temperature distribution image is displayed on the image monitor 4 as described above, and is further inputted and recorded in the image recording device 5. Reference numerals 6 and 7 denote an image distributor and an image division display for distributing and dividing the temperature distribution image to the image monitor 4 and the image recording device 5.

In the image recording device 5, the old image is overwritten and replaced with the latest image, and all the temperature distribution images that are past a certain time from the present are always recorded. In the present embodiment, the image recording device 5 records temperature distribution images for 5 hours at intervals of 30 seconds. From the image recording device 5,
The current temperature distribution image and the temperature distribution image one hour before are always output on the image monitor 4 as a four-split screen.

Further, a time-series change in temperature corresponding to the highest luminance position is represented by P in the temperature distribution image via the image processing device 3.
It is displayed on a C / CRT (CRT display of a personal computer) 8. When the image on the slab surface is obstructed by water vapor or a water film, the temperature at the highest luminance position drops rapidly as shown in FIG. 7, but such a temperature drop is ignored and as shown in FIG. Attention is paid to the envelope of the maximum temperature T, and the temperature change over time is displayed.

As a time series change of the slab surface temperature,
As shown in FIG. 7, a temperature difference signal (difference of the maximum temperature T) between the current temperature signal and the temperature signal one hour ago is displayed at the same time. Normally, the surface temperature of the slab is highest immediately after starting the injection of molten steel from the ladle through the tundish into the mold, and then gradually decreases, and under normal operating conditions, the temperature one hour ago and the current temperature 1 for temperature
There is a difference of about 0 ° C to several tens ° C. If the current temperature falls below this value, a breakout alarm will be issued,
If the temperature becomes higher than one hour ago, it is determined to be dangerous, and measures such as slowing down the slab withdrawal speed are taken to return the temperature difference to a normal value.

FIG. 8 shows a time-series change of the temperature difference signal when a breakout occurs in the continuous casting machine for experiments. As shown in FIG. 8, it can be seen that the difference in the maximum brightness temperature starts to increase sharply about 10 minutes before the breakout occurs. From such experimental examples, it is understood that the occurrence of breakout can be sharply predicted by extracting the highest temperature from the slab surface temperature distribution and comparing the current temperature with the temperature one hour before. From the temperature distribution image recorded on the image recording device 5 hours before the occurrence of the breakout, it was confirmed that the temperature rise started from the corner of the slab and reached the breakout in less than 30 seconds.

[0035]

As described above, according to the present invention, in the continuous casting of steel, the surface temperature and surface properties of the slab drawn from the mold are continuously measured by a CCD camera equipped with a relay lens having a pinhole at the tip. A method and apparatus for monitoring a breakout that accurately predicts a breakout by monitoring the breakout are provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a CCD camera with a relay lens according to the present invention.

FIG. 2 is a view showing a CCD camera with a relay lens arranged to monitor a slab surface in the present invention.

FIG. 3 is a diagram showing a mode of dividing and extracting a video signal of a CCD camera in the present invention.

FIG. 4 is a diagram showing a change in slab surface temperature with the passage of time.

FIG. 5 is a specific layout diagram of a CCD camera with a relay lens according to the present invention.

FIG. 6 is a diagram showing a configuration of a monitoring device according to the present invention.

FIG. 7 is a diagram showing a change with time of a slab surface temperature immediately below a mold.

FIG. 8 is a diagram illustrating a change in a temperature difference signal when a breakout occurs.

FIG. 9 is a view schematically showing continuous casting of steel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Monitoring device 2 CCD camera 3 Image processing device 4 Image monitor 5 Image recording device 6 Image distributor 7 Image division display 8 PC / CRT (personal computer / CRT display) 9 Terminal block 10 Relay lens 11 Pinhole 12 Objective lens 13 Protective pipe 14 Gas inlet S slab

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidehiko Masasho 1-3-2 Kitaaoyama, Minato-ku, Tokyo Inside Tokai Carbon Co., Ltd. (72) Inventor Kang Yongzhong, Republic of Korea F-term (reference) 4E004 MC11 in Pohang Sogo Steel Co., Ltd.

Claims (6)

[Claims] 1. In continuous casting of steel, the surface temperature and surface properties of a slab drawn from a mold are continuously monitored by a CCD camera equipped with a relay lens having a pinhole at the tip, and the detected surface temperature and /
Alternatively, a breakout monitoring method in continuous casting of steel, wherein a breakout is predicted by detecting an abnormality in surface properties. 2. A breakout is predicted by comparing a temporal change of the surface temperature with a previously detected surface temperature change with time during normal casting, which is detected in advance. A method for monitoring breakout in continuous casting of steel. 3. A luminance signal separated from a video signal obtained by the CCD camera is converted into a temperature image by image processing, and a specific temperature is selected from the temperature image to be a breakout signal. 3. The method of monitoring a breakout in continuous casting of steel according to claim 1, wherein a breakout is predicted by monitoring a change in a specific temperature. 4. A device for predicting breakout in continuous casting of steel, having a pinhole at a tip for continuously monitoring the surface temperature and surface properties of a slab placed immediately below a mold and drawn from the mold. A CCD camera equipped with a relay lens, an image monitor displaying a video signal indicating a surface property of the slab separated from a video signal obtained by the CCD camera, the surface temperature separated from a video signal obtained by the CCD camera A steel processing apparatus comprising: an image processing device that converts a luminance signal for measurement into a temperature image; an image monitor that displays a temperature image; and an image recording device that inputs and continuously records a temperature image. Breakout monitoring device in continuous casting. 5. An image monitor for displaying a temperature image, comprising: an image monitor for displaying a temperature image at a current time and a predetermined time before; and an image monitor for displaying a specific temperature in the temperature image in a time-series manner. The apparatus for monitoring breakout in continuous casting of steel according to claim 4, characterized in that: 6. A clear image of the slab surface can be always obtained by blowing a purge gas from the pinhole to prevent contamination of the relay lens and cool the lens. The apparatus for monitoring breakout in continuous casting of steel according to claim 4.