JPS61293642A - Level measuring instrument for continuous casting installation by vacuum melting - Google Patents

Abstract

PURPOSE:To exactly measure the level of the molten steel in the continuous casting mold in a vacuum melting furnace in the stage of measuring the level of the molten metal in said mold by scanning the casting mold contg. the molten metal through a rotary plate having a slit through the peep window of the furnace and measuring the time for brightness and darkness by means of a sensor. CONSTITUTION:The molten metal to be continuously cast is put into the continuous casting mold in the vacuum melting furnace 1 and the bright part of the molten metal surface and the dark part of the casting mold 2 are projected through the peep window 1a onto the sensor array 5b of the linear sensor 5 through the rotary disk which is provided in the furnace 1 and has the slit 3 in the radial direction. The signals H, L corresponding to the brightness and darkness are outputted from the sensor 5 and are inputted to a min. value storage circuit 6 and a max. value storage circuit 7. The min. value is subtracted from the max. value stored in the storage circuit by an arithmetic circuit 8 and the result thereof is outputted as the level signal of the molten steel in the casting mold, by which the level of the molten steel in the mold 2 is exactly measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] This invention relates to a device for measuring the level of molten metal in a mold in a vacuum melting furnace.

[Prior art and its problems 1 In equipment that performs continuous casting, it is necessary to automatically detect the level of molten metal poured into the mold.When the temperature of the molten metal is high and it emits light, such as cast steel, the surface of the molten metal and the mold The molten metal level is measured using the brightness and darkness of the molten metal. The principle is that the mold is scanned using an optical sensor installed at a predetermined position that distinguishes between brightness and darkness, and the level of the molten metal is indirectly detected based on the scanning time of the bright areas of the molten metal. Detection of the molten metal level is also necessary in continuous casting equipment using a vacuum melting furnace, and in this case, the sensor is installed outside the vacuum melting furnace, so detection is carried out through a peephole provided in the vacuum melting furnace. However, in order to prevent metal vapor from adhering to the glass of this peephole, a disc with a slit is rotated inside the peephole so that it faces the glass of the peephole. Therefore, in the above-mentioned measuring method, when the part without a slit faces the sensor, the path is optically blocked by the disk (I), making it impossible to measure the molten metal level. For this purpose, it is necessary to synchronize the scanning and the rotation of the slit, which has the disadvantage of complicating the measuring device.

[Object of the Invention] This invention was made to eliminate the above-mentioned problems, and an object thereof is to provide a level measuring device that can be used in a conventional vacuum furnace.

[Structure of the Invention] The level measuring device for continuous casting equipment using a vacuum melting furnace of the present invention measures the level of molten metal in a mold provided in the vacuum melting furnace using a peephole provided in the vacuum melting furnace and a peephole provided in the vacuum melting furnace. It is a device that measures through a rotary plate with slits provided inside the furnace, and has a plurality of light receiving elements arranged in a straight line.The scanning of each light receiving element detects the molten metal on the upper surface of the mold inside the furnace. a sensor for detecting light and dark areas by scanning the light and dark areas between the mold and the mold; a minimum value storage means for storing the minimum value t1 at the time of detection when the dark state changes to the light state in each scan of the plurality of rows by the sensor; maximum value storage means for storing the maximum value L2 at the time of detection when the state changes from the dark state; The present invention is characterized in that it is equipped with an arithmetic means for outputting one value.

[Example 1 FIG. 1 shows one embodiment according to the invention.

1 is a vacuum melting furnace, and 2 is a mold provided in the vacuum melting furnace 1. 1a is a peephole provided at the top of the side wall of the vacuum melting furnace 1 for internal confirmation; 3 is the peephole 1
A rotating disk 3 is provided to prevent metal vapor from adhering to the glass 3a, and on this disk 3 is provided a ring 3a which is long in the diametrical direction and is symmetrical with respect to the center. The disc 3 is located almost parallel to the glass surface of the peephole 1a, and is provided so that the upper half of the disc 3 faces the peephole 1a. 3a alternately pass through the peephole 1a, and an optical image of the molten metal or the mold can be seen intermittently through the peephole 1a through the peephole 1a. 4 is a motor that rotates the disc 3.

Reference numeral 5 denotes a linear sensor for light detection having a scanning function, in which a large number of light-receiving elements are arranged in a straight line and each light-receiving element outputs a voltage representing the amount of light received.
The brightness and darkness of the mold 2 and the molten metal in the mold 2 are detected by the sensor array 5 through the lens 5a of the linear sensor 5.
It is projected as an image on b. The bright and dark areas are detected by scanning, and a signal of "H"1ll-'' is output from the linear sensor 5 corresponding to the brightness and darkness.This output signal is input to the minimum value storage circuit 6 and the maximum value storage circuit 7. The minimum value storage circuit 6 stores the minimum value at the time when the signal sent from the linear sensor 5 changes from L to H every time scanning is performed, and the maximum value storage circuit 7 similarly stores the minimum value when the signal sent from the linear sensor 5 changes from L to H. The maximum value at the time of the change is stored. 8 is a W circuit that subtracts the minimum value from the maximum value stored in the storage circuit and outputs the result as a level signal.

Next, the functions of the device configured as described above will be explained.

Figure @2 is an enlarged view of the rotating disk 3, and the linear sensor 5
The direction of scanning is such that when the slit 3a of this disk 3 is in a vertical position, it is in the direction of a certain angle α with respect to the direction of the slit 3a.
This prevents the light from being optically cut off.

In the projection through the sulin) 3a as described above, the mold 2
Not all of it is projected, but only a part of it is projected, and the projected area is not the same as the one at the time of scanning) 3a
It varies depending on the location. Therefore, in this embodiment, the predetermined time 1. is an integral multiple of the rotation period of Surin 3a. The linear sensor is scanned multiple times within the process, and the output signals obtained from each scan are combined and restored.

FIG. 3 shows an example in which scanning is performed, for example, three times within the predetermined time t1, and when the detection signal changes from dark to bright, the minimum of the time t+ and L3+t, is stored in the minimum value storage circuit 6, and the time point h+L4, which is the maximum of b when the light changes from bright to dark, is stored in the maximum value storage circuit 7. Therefore,
After the predetermined time 11, the arithmetic circuit 8 calculates and outputs L=ts. Also, at this time, the minimum value storage circuit 6
And the numerical value stored in the maximum value storage circuit 7 is cleared by the reset signal. 1. -15 signal is mold 2
The value of this output signal corresponds to the molten metal level H since it shows the length of the molten metal when the top is scanned linearly and is the part that can be seen through the peephole 1a.

FIGS. 4(A) and 4(B) show the output signal of the linear sensor 5 when scanning is performed n times during the predetermined time t, and
This shows a signal in which the minimum value and maximum value of the output signal are stored by the minimum value storage circuit 6 and the maximum value storage circuit 7. The third scan was when nothing was detected from position a1 of pickpocket 7) 3a, and the intermittent "H" in the output waveform of the linear sensor 5 during the fourth and fifth scans was due to the molten metal surface. The insoluble matter floating in the water was detected as ff8 part, but according to the method described above, it was found that
The discontinuities in the signal are ignored, as shown in FIG. In addition, since the molten metal level is detected by scanning multiple times, there is no need to synchronize the rotational speed of the disk 3 with the scanning, and the molten metal level can be detected by simply adding a linear sensor 5 etc. to a conventional vacuum melting furnace. can be detected. In addition, using the above-mentioned measuring device as a level measuring device for a melting furnace other than a vacuum melting furnace,
By providing a rotating plate with slits, it is possible to prevent dust from adhering to the lens portion of the sensor.

[Effect of the invention 1 As detailed above, this invention performs multiple scans to detect the molten metal level, and combines the signals obtained from each scan to restore a single signal. If there is a rotating plate that interrupts the optical path intermittently, the molten metal level can be measured accurately.

[Brief explanation of drawings]

Figure 1 is a block diagram showing one embodiment of the present invention, Figure 2 is an enlarged plan view of the rotating disk in Figure 1, and Figures 3 and 4 (A) are outputs from the linear sensor for each scan. The signal waveform diagram shown in FIG. 4(B) is a waveform diagram obtained by combining the respective output signals in FIG. 4(A). 5... Linear sensor, 6... Minimum value storage circuit,
7...Maximum value storage circuit,...Arithmetic circuit.

Claims (1)

[Claims] (1) A device that measures the level of molten metal in a mold provided in a vacuum melting furnace through a viewing window provided in the vacuum melting furnace and a rotary plate having a slit provided inside the viewing window. There is a sensor that has a plurality of light receiving elements arranged in a straight line and detects bright and dark areas between the molten metal part on the upper surface of the mold inside the furnace and the mold part by scanning each light receiving element; minimum value storage means for storing the minimum value t_1 at the time of detection when changing from the dark state to the bright state in each scan; and maximum value storage means for storing the maximum value t_2 at the time of detection when changing from the bright state to the dark state. and the scanning time t_2-t_ in the bright state from the time points t_1 and t_2 stored by the storage means.
1. A level measuring device for continuous casting equipment using vacuum melting, characterized in that it is equipped with a calculation means for outputting a molten metal level signal from 1 to 1.