JPS61132250A - Molten steel level detector - Google Patents

Abstract

PURPOSE:To provide a molten steel level detector which can detect continuously the level of a molten steel surface with high accuracy by using a special improved beam attenuating filter by noticing that the level of the molten steel surface is usually controlled near the center of an image and that the decrease in the illuminance of the molten steel surface by the beam attenuating filter appears before the mold. CONSTITUTION:The above-mentioned detector is provided with a television camera 10 which picks up the image of the region in the mold 30 including the molten steel 32 surface and a signal processing part 11 for detecting the level of the molten steel surface from the temp. difference between the molten steel surface and the wall surface of the mold by detecting the illuminance on the straight line (a) in the vertical direction preset in the image thereof. A control part 12 which controls the quantity of casting according to the level of the molten metal surface on the basis of the signal from the processing part 11 is provided and further the beam attenuating filter 13 of which the quantity of the beam attenuation in the upper half with respect to the visual field of the front face of the camera 10 is larger than the quantity of the beam attenuation in the lower half part is further provided. The molten steel 32 surface under automatic control is in the upper half in the above-mentioned constitution and therefore the flame appearing in the upper half is cut by the beam attenuation by the filter 13 so that the image of the camera 10 may be approximated to the ideal image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a molten steel level detection device for detecting the molten steel surface level in a casting utensil used in continuous casting.

[Conventional technology]

Generally, in continuous casting equipment that performs casting continuously.

Molds are used to store molten steel as casting equipment. When molten steel is stored in a mold, it is extremely important to detect the level of the molten steel surface within the mold and maintain the molten steel surface level within a predetermined range. For example, if the molten steel surface level is too high, the molten steel may overflow from the mold, while if it is too low, the mold shell may rupture during withdrawal of the molten steel. In either case,
There is a risk of causing a major accident.

An example of a conventional method using a television camera to detect the level of molten steel will be described with reference to FIG.

Molten steel 32 is fed into the mold 30 including a metal 31. Level detection device is TV camera 10
and a molten steel surface inside the mold 30.

It is arranged so that the inner wall surface of the mold 30 can be seen in the field of view. Inside the mold 30, reso-do oil or the like is usually floated on the molten steel surface to prevent oxidation of the molten steel surface and to lubricate between the mold 30 and the slab. Therefore, smoke or flame 33 due to the reso/do oil is generated on the molten steel surface of the mold 30.

FIG. 4 shows an ideal, disturbance-free image seen by the television camera 10. However, as shown in FIG. 5, the actual image shows that a flame is generated on the surface of the molten steel by the above-mentioned reso-do oil, and disturbances such as an increase in the brightness of the mold wall surface occur.

On the other hand, the level of the molten steel surface is detected on a predetermined vertical straight line within one image (indicated by a in Fig. 4), assuming that the black and white signal level in the image signal from the television camera 10 is proportional to the illuminance. This is done by detecting the illuminance at the location. Namely.

The molten steel surface is brighter than the mold wall surface, and the illuminance on the straight line a in the image of FIG. 4 changes as shown in FIG. 6. As is clear from FIG. 6, there is a clear difference in illuminance between the molten steel surface and the mold wall surface, and this height is detected as the molten steel surface level by setting the light/dark binary level as A.

However, due to the disturbance caused by the flame 33, the illuminance on the straight line in Fig. 5 becomes as shown in Fig. 7, and since the bright/dark binary level RO is close to the level of the disturbance part, the molten steel surface level may be incorrectly detected. was there.

[Problem that the invention seeks to solve]

In response, attempts have been made to place a neutral density filter in front of the television camera to remove the flame from the image, which is darker than the molten steel surface but brighter than the mold wall surface. However, the problem here is that, as shown in Figure 7, the brightness of the molten steel surface near the front of the mold is about the same as the brightness of the flame part due to the influence of the air nozzle inside the mold. That's what it means. For this reason, if the brightness of the flame is cut with a neutral density filter, the image of the lower part of the molten steel surface will also be cut off, which is inconvenient for level detection, as shown in FIG.

In view of the above drawbacks, it is an object of the present invention to provide a molten steel level detection device that can continuously detect the level of a molten steel surface with high accuracy.

[Means for solving problems]

The present invention focuses on the following: 1. Normally, the molten steel surface level is controlled near the center of the image, and the reduction in molten steel surface illumination due to a neutral density filter appears in the front of the mold, that is, at the bottom of the image. It is characterized by using an improved version.

The level detection device according to the present invention has a field of view that is an area within the mold that includes the surface of the molten steel, a means for capturing an image within this field of view, and a means for detecting the illuminance on a predetermined straight line in the vertical direction within the captured image to detect the molten steel. means for detecting the level of the molten steel surface based on the difference in illumination between the surface and the mold wall surface, and the imaging means captures the image through filter means having different amounts of light attenuation in the upper half and lower half with respect to the field of view. Features.

〔Example〕

The present invention will be explained below with reference to one drawing.

FIG. 1 shows a level detection device according to an embodiment of the present invention, which includes a television camera 10 that images an area in the mold including the steel surface, and a level detection device that is set in advance in the image from the image signal of this television camera 10. A signal processing unit 11 detects the illuminance on a straight line in the vertical direction and detects the molten steel surface level based on the difference in illuminance between the molten steel surface and the mold wall surface, and a signal processing unit 11 that detects the molten steel surface level based on the signal from the signal processing unit 11. It has a casting amount control unit 12 that controls the casting amount accordingly, and a neutral density filter 13 is provided in front of the television camera 10 in which the amount of light attenuation in the upper half of the field of view is larger than the amount of light attenuation in the lower half. . Such a neutral density filter can be easily obtained by, for example, a combination of two filters having different light attenuation amounts.

By using such a dark filter 13, the molten steel surface during automatic control is within the upper half of the steady poem image, so
In the case of the state shown in FIG. 5, the flame that appears in the upper half of the image is cut off by the attenuation by the attenuation filter, and the image obtained by the television camera 10 can be made closer to the ideal image as shown in FIG. 4. But 2. Since the lower part of the image is hardly attenuated, there is no shadowing. Also.

The illuminance has a distribution as shown in FIG. 2, and by adjusting the bright and dark binary levels to C, disturbances can be completely removed and highly reliable level detection can be performed. In the above-mentioned example, a mold is shown as a casting instrument, but the present invention can also be applied to detecting the level of molten steel in a ladle or tandem. Also, in the example.

Although a television camera is used, signals for illuminance detection can also be extracted by using photo arrays arranged in one plane and scanning these photo arrays electronically.

〔Effect of the invention〕

As explained above, according to the present invention, the level of the molten steel surface can be detected continuously with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention, and FIG.
The figure shows the illuminance characteristics of a specific area of the television camera image obtained by the present invention, Figure 3 is a diagram for explaining the principle of detecting the molten steel surface level using a television camera,
(Figures 6 and 7 show the ideal and actual images of the inside of the mold, respectively, taken by a television camera. Figures 6 and 7 show the illuminance characteristics obtained from the images in Figures 4 and 5, respectively. 8 is a diagram showing an example of an image of a television camera to explain the drawbacks of the conventional example. In the figure, 10 is a television camera, 30 is a mold, 31 is a tap/di/yu, and 32 is a Pouring. Fig. 1 Fig. 3 Cause Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (1)

[Claims] 1. In a molten steel level detection device for detecting the level of a molten steel surface in a casting utensil containing molten steel, a field of view is an area within the utensil that includes the molten steel surface, and means for capturing an image within the field of view, and a captured image. means for detecting the illuminance on a predetermined straight line in the vertical direction, and detecting the level of the molten steel surface based on the difference in illuminance between the molten steel surface and the inner wall surface of the vessel; A molten steel level detection device characterized in that an image is captured through filter means having different amounts of light attenuation in a predetermined area and other areas.