JPS5941828B2 - Mold liquid level detection method in continuous casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for non-contact detection of mold liquid level in continuous casting equipment.

Conventional mold liquid level detection methods include methods that use radiation, methods that embed thermocouples in the mold, and methods that use eddy current, but the methods that use radiation have safety issues for workers. The method of embedding the thermocouple in the mold has the problem of inconvenience in replacing the thermocouple and slow response, while the method of using eddy current requires a sufficient distance from the liquid surface. There is a problem with workability.

Therefore, the present invention proposes a mold liquid level detection method that solves these problems. 5 Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Figure 1, 1 is a mold, 2 is a tundish,
Reference numeral 3 denotes molten steel being poured into the mold 1 from the tundish 2, and 4 a television camera disposed at a predetermined position, which photographs the inside of the mold 110 from diagonally above. This camera 4 is accurately positioned with respect to the mold 1, and its scanning line is parallel to the liquid level A. 5 is a signal processing device that processes the video signal of the television camera 4; 6 is a monitor 15;
As shown in FIG. 2, the entire upper part of the mold 1 is shown.

To explain the above-mentioned signal processing device 5, T is a signal cutting circuit that cuts out the part B in FIG. 9 is a threshold circuit that performs threshold processing on the signal compressed by the integration circuit 8 in the scanning direction to detect the scanning line number corresponding to the location corresponding to the liquid level A; 1
0 is a control circuit that controls the operation timing of each of the circuits 1, 8, and 9, and 11 is a scanning signal obtained by the threshold circuit 9 via the control circuit 10 for the video signal of the television camera 4. This is a video addition circuit that superimposes line information.
A method for detecting the mold liquid level A will be explained based on the above configuration.

First, the liquid level inside the mold 1 is photographed by a television camera 4 accurately positioned with respect to the mold 1. As a result, mold 1 is displayed on the screen of monitor 6 as shown in Figure 2.
The entire upper part of the image is displayed. Next, this picture 3
The liquid level A is detected by focusing on the fact that the amount of light emitted from the molten steel 3 is much larger than the amount of light reflected from the mold wall from the 5th side. is shown, so avoiding this, only the portion B in FIG. 2 is extracted by the signal extraction circuit 7. In the cut out part B, if the scanning line direction (width direction) is x and the direction perpendicular to it (height direction) is y, the liquid level A is the size YA in the y direction, as shown in Figure 3. It is indicated by. Next, the integration circuit 8 converts the video signal of the cut out portion B into the section (
XL and XR) to compress the two-dimensional signal into a one-dimensional signal. The compressed signal [g(y)] is as shown in FIG. Here, the size of the video signal of the cut out part B is f
(X.y), the compressed signal [g(y)] is expressed by the following equation. In Fig. 4, when scanning from the top along the -y direction, the integral value A is small in the part corresponding to the mold wall because the amount of reflected light from this mold wall is small, and C in Fig. 3 is shown. As shown in the figure, the integral value is slightly larger in areas where molten steel 3 adheres to the mold wall or where molten steel droplets are scattered due to injection of molten steel. When scanning further and reaching a portion corresponding to the molten steel 3, the integral value suddenly increases because the amount of emitted light from the molten steel 3 is large.
Therefore, the point YA where the integral value suddenly changes is the liquid level A. Therefore, the threshold value C is set at an appropriate location between the above-mentioned A and the mouth, and the threshold value C is compared with the integral value obtained by scanning in the threshold value circuit 9.
The scanning line number where the integrated value exceeds the threshold C (that is, YA) is detected, and the mold liquid level A is detected based on this detected value. Further, information on the scanning line number corresponding to the liquid level A obtained by the threshold circuit 9 is sent to the video addition circuit 1 via the control circuit 10.
1, and this video addition circuit 11 draws a scanning line corresponding to the liquid level A on the screen of the monitor 6.
The worker observes whether the drawn scanning line matches the liquid level A actually displayed on the monitor 6. If they match, it means that the detection action is being performed normally. It is also possible to control the mold liquid level using information on the scanning line number. In the above embodiment, the liquid level A is detected using the threshold value C, but other methods such as a matched filter method may also be used. As described above, according to the mold liquid level detection method in continuous casting equipment of the present invention, an appropriate part of the photographic screen is cut out, so it is possible to select the most suitable part for detecting the liquid level. It is possible.

Similarly, the entire upper part of the mold can also be observed. Furthermore, since the video signal of the cut out part is integrated in the scanning direction to compress the signal, the compressed signal changes rapidly from the part corresponding to the mold wall to the part corresponding to the molten steel. Become. Therefore, the rapidly changing portion can be detected very easily, and thereby the liquid level can be easily detected without contact.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is a schematic explanatory diagram, Fig. 2 is a perspective view of the upper part of the mold displayed on a monitor, Fig. 3 is a front view of the cut out part, and Fig. 4 is a cutout. This is a graph obtained by integrating the part. 1...mold, 3...molten steel, 4...
...TV camera, 6...monitor,
7...Signal extraction circuit, 8...Integrator circuit, 9...Threshold circuit, 10...Control circuit, 11...Video addition circuit.

Claims (1)

[Claims] 1 Photograph the liquid level inside the mold using a television camera placed at a predetermined position so that its scanning line is parallel to the liquid level, cut out an appropriate part of the photographed screen, and
The video signal of the cut out part is integrated in the scanning direction to perform signal compression, and the scanning line number corresponding to the part corresponding to the liquid level in the compressed signal is detected, and based on the detected value, the mold liquid A mold liquid level detection method in continuous casting equipment characterized by detecting the surface level.