JPH10158717A - Detection of slag when tapping molten steel in converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve such a problem that the sure detection of slag is difficult, caused by the disturbance due to fuming and splashing, etc., from a ladle and the difference in kind of steel in the conventional slag detecting method at the time of tapping molten steel from a converter, and by such improvement, it becomes possible that the visial observation by an operator is executed or molten steel image is analyzed into each pixel and the variation in white-image elements, i.e., the variation in density level in the image compared to the difference from the moving average value until the last time is observed. SOLUTION: This slag detecting method used when tapping the molten steel from the converter 1 detects the flow-out of slag without being affected with the conventional various kinds of disturbances, etc., by previously determing a threshold value based on the max. value and the min. value of the brightness or the color unevenness in the image 4 of molten steel tapping stream 2, fetching the actual molten steel tapping stream 2 into an image processor to compare it with the threshold value, and judging that it is flowing out of the slag when this actual value becomes less than the threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting slag when tapping steel from a converter, and more particularly to a novel improvement for facilitating the determination of slag flowing out of a converter by performing image processing on the slag. It is.

[0002]

2. Description of the Related Art In general, when molten steel is discharged from a converter to a ladle after being blown in a converter, when slag floating on the molten steel in the converter flows into the ladle, the slag flows into the ladle. Rephosphorization occurs,
The refractory lining of the ladle is eroded. In order to prevent slag that has these adverse effects from being mixed in the next process, it is necessary to accurately identify molten steel and slag at the time of tapping, and to ensure that the slag starts flowing at a short time when slag starts to flow without lowering the yield of molten steel. Need to be stopped. For this reason, conventionally, there is a method of detecting the outflow of slag in order to minimize the amount of outflow of slag to the ladle. For example, the first conventional method in which an operator visually detects the flow of tapping and detects the outflow of slag from the brightness and color, and starts the outflow of the slag and simultaneously returns the tilting converter to prevent the outflow of the slag. There is a way. Further, as a method of detecting slag by image processing, Japanese Patent Application Laid-Open No. 1-215 discloses a method in which molten steel discharged from a converter is received in a ladle and the molten steel surface in the ladle can be adjusted in position by a motor. Shoot continuously with a TV camera. The image is input to the image processing device, the input image is decomposed into pixels, and each pixel is selected and binarized by selecting a predetermined threshold to obtain the number of white-pixels. There is a second conventional method for detecting the inflow of slag from the converter into the ladle from the change over time in the number of white-pixels. Also, Japanese Patent Application Laid-Open No. Hei 7-260696 describes that a tapping flow from a converter is photographed by a CCD camera and input to an image processing / analyzing device at regular intervals.
In the image processing analysis device, in each of a plurality of monitoring areas set in the image, a gray level corresponding to the luminance is obtained for each pixel, an average gray level between the monitoring areas is calculated, and an average gray level for each fixed period is calculated. Each time a level is determined, there is a third conventional method in which a difference from the previous moving average value is calculated, and when the difference exceeds a set value, slag outflow is determined and output to the converter tilting device. .

[0003]

First, in the first conventional method, there is an individual difference in the judgment, and considerable variation occurs, so that it was not always possible to judge the outflow of the slag properly. Further, as described in Japanese Patent Laid-Open No. 1-2
In the second conventional method disclosed in Japanese Patent Publication No. 15, the outflow of slag is reliably detected based on disturbances such as smoke and splash from the ladle, differences in steel types to be tapped, tapping temperature, and the like. It was extremely difficult. Also, in the third conventional method disclosed in Japanese Patent Application Laid-Open No. Hei 7-260696, outflow of slag is surely detected from the above-mentioned difference in the type of smoke, the type of steel and the temperature of tapping from the ladle. It was extremely difficult to do.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. In particular, it is expected that brightness or color unevenness will be different between when molten steel flows and when slag flows. According to the image analysis, when the molten steel flows, the difference in luminance and color unevenness is large, and when the slag flows, the difference in luminance and color unevenness is small. And the difference in brightness or color unevenness when slag is mixed into the molten steel flow,
An object of the present invention is to provide a method for detecting slag at the time of converter tapping, which can detect slag outflow based on the difference and can appropriately prevent slag outflow.

[0005]

A method for detecting slag during tapping of a converter according to the present invention is characterized in that a tapping flow of a converter is imaged in advance, and the maximum and minimum values of brightness or color unevenness are obtained and accumulated. One step, a second step of determining a threshold for determining molten steel and slag from the frequency distribution of the difference between the maximum value and the minimum value of luminance or color unevenness, and then, the actual steel tapping flow of the converter to the image processing device. The method comprises a third step of comparing with the threshold value obtained in advance, and a third step of determining that slag has flowed out when the threshold value is smaller than the threshold value.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method for detecting slag during tapping of a converter according to the present invention will be described below with reference to the drawings. First, although not shown in the figure, when discharging the refined molten steel from the converter, the flow of tapping was photographed from the lateral direction using a CCD camera or the like, and the brightness between when the molten steel flow alone and when the slag flowed was measured. Level difference 2 minus the minimum value from the maximum value of
The distribution of 00 is obtained. This distribution, as shown in FIG.
It is clear that the brightness level difference 200 obtained by subtracting the minimum value from the maximum value of the brightness by imaging the molten steel flow is large in molten steel and small in slag. Therefore, by this, the molten steel exiting from the converter is imaged in advance and the image processing apparatus 10 shown in FIG.
An image is calculated by a well-known image output device 10a, an image calculation device 10b, a calculator 10c, and an output device 10d as an example, and the above-described luminance level difference 200 is obtained to obtain a threshold value for determining molten steel and slag. It is configured to be able to.

Next, an operation for detecting slag outflow by the image processing apparatus 10 will be described with reference to a processing flow shown in FIG. Image input obtained by continuously capturing the molten steel flow from the start of tapping with the CCD camera or the like (first step 10
0) is subjected to image analysis (second step 101) as a signal 100a obtained by converting the imaging signal. That is, the first and second steps 100 and 101 correspond to the image output device 1.
0a. This image-analyzed signal 101a
Is the luminance level difference 20 of the luminance by the image arithmetic device 10b.
0 is calculated, and the luminance level difference 200 is calculated by the arithmetic unit 10c.
Is compared with a threshold value obtained in advance (third step 102). If the value is larger than the threshold value, it is determined that only molten steel is out. If the value is smaller than the threshold value, it is determined that slag is flowing out, and the slag is determined by the output device 10d. Outflow detection output 30
Outputting 0 (fourth step 103), a signal is sent to a drive device (not shown) for tilting the converter, and the converter is rotated back to stop slag outflow.

(Embodiment) Next, an embodiment of the present invention will be described. FIG. 3 is an image in which the state of tapping from the converter 1 is imaged. That is, an image 4 obtained by previously capturing the tapping stream 2 from the converter 1 with a CCD camera or the like is taken into the image processing apparatus 10 as an image signal. The analysis range 3 is set for the image signal input to the image processing apparatus 10, the maximum value and the minimum value of the luminance level within the range are analyzed, and the difference between the maximum value and the minimum value of the luminance level is obtained. As shown in FIG. 4, a threshold L1 for determining molten steel and slag between a distribution A of molten steel luminance level difference and a distribution B of slag luminance level difference is set and stored based on a frequency distribution of luminance level difference between molten steel and slag. . This threshold L1
Varies depending on the camera or the like used, so that a constant K based on individual characteristics is determined in advance. Next, the tapping flow 2 from the converter 1 is continuously imaged with a CCD camera or the like until the tapping is completed, the captured image is taken into the image processing device 10, and the imaging is continued while comparing with a previously obtained threshold value. At the moment when the threshold value from the image becomes smaller than the preset threshold value, a slag outflow detection output 300 is output to send a reverse rotation signal to a drive device that tilts the converter 1 to reverse the rotation. In the present embodiment, the difference between the maximum value and the minimum value of the luminance is obtained. However, the present invention can be implemented even with color unevenness.

[0009]

The method for detecting slag during tapping of a converter according to the present invention has the following effects because it is configured as described above. In other words, since the threshold for determining molten steel and slag is determined using the brightness or color unevenness of the captured image, and the slag outflow detection output is obtained by comparing the threshold with a previously obtained threshold,
Since the detector has high reliability and monitors the tapping surface, the outflow of slag can be detected quickly, and since there is no delay, the outflow of slag can be reduced, thereby contributing to stable operation. In addition, since slag can be detected without being affected by the tapping steel type and tapping temperature, it is not affected by differences in operations.

[Brief description of the drawings]

FIG. 1 is a process flow chart showing a slag detection method at the time of converter tapping according to the present invention.

FIG. 2 is a configuration diagram of an image processing apparatus that detects slag.

FIG. 3 is an explanatory diagram showing an image.

FIG. 4 is an explanatory diagram illustrating distribution of luminance levels of molten steel and slag.

[Explanation of symbols]

 Reference Signs List 1 converter 2 tapping flow 3 analysis range 4 image 10 image processing device

Claims (1)

[Claims] 1. A first step in which a tapping flow (2) of a converter (1) is imaged in advance, and a maximum value and a minimum value of brightness or color unevenness are obtained and accumulated, and a maximum value of brightness or color unevenness is obtained. A second step of determining a threshold for discriminating molten steel and slag from the frequency distribution of the difference between the minimum values, and then, the actual tapping flow (2) of the converter (1) is converted to an image processing device (1
A slag detection method at the time of converter tapping, comprising: a third step of comparing the threshold value obtained in advance in step 0) with the predetermined threshold value;