JP2014034046A - Measuring method of molten metal surface level and mold powder thickness of molten metal in casting mold for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of continuously measuring a molten metal surface level of molten metal in a casting mold for continuous casting from an initial stage of injecting the molten metal, and capable of also continuously measuring a mold powder thickness.SOLUTION: A method according to the present invention calculates a thickness of mold powder P inputted on molten metal based on a measured value of s first level gauge and a measured value of a second level gauge, by outputting a molten metal surface level measured value measured by the first level gauge as a molten metal surface level, after the molten metal surface level reaches the lower limit, by outputting the molten metal surface level measured value measured by the second level gauge as the molten metal surface level until the molten metal surface level reaches the lower limit of a measurement range set in the first level gauge, by using the electromagnetic type first level gauge 10 for measuring the molten metal surface level of the molten metal S in the casting mold 50 for the continuous casting and the microwave type second level gauge 20 capable of measuring the molten metal surface level of a range overlapping with a measurement range set in the first level gauge and a range lower than this range.

Description

  The present invention relates to a method for measuring a molten metal level and mold powder thickness in a continuous casting mold.

  In the continuous casting process of steel, molten steel is poured into a mold and cooled, a solidified shell is generated, and a slab is manufactured by continuously drawing out below the mold. In this continuous casting process, the molten steel level in the mold is conventionally controlled by measuring the molten metal level using an electromagnetic level meter (such as a vortex sensor). The measurement range of the electromagnetic level meter is about 150 to 200 mm from the lower surface of the electromagnetic level meter from the viewpoint of obtaining necessary measurement accuracy.

  Further, in recent years, development of mold powders to be put on molten steel for the purpose of lubrication between a mold and a solidified shell has been carried out to cope with a wide variety of steel types. The thickness of the mold powder in the continuous casting process of steel has been an important factor for operation management. However, a method of continuously measuring the thickness of the mold powder that can be an index of operational stability during operation has not been put into practical use.

  As a method for measuring the thickness of the mold powder molten layer in the continuous casting process of steel, a measuring method using a measuring rod (for example, Patent Document 1) or a multi-frequency eddy current type measuring method (for example, Patent Documents 2 to 4). Etc. have been proposed.

  As described in the prior art section of Patent Document 1, the method using an iron wire measuring rod and a metal aluminum wire measuring rod having a melting point lower than the melting point of the mold powder does not melt at the melting point of the mold powder. Since the melting loss difference between the bar and the molten metal aluminum wire measuring bar is the thickness of the powder melt layer, it is difficult to measure the low melting point mold powder. Moreover, when measuring continuously, since a metal aluminum wire measuring rod melt | dissolves in molten steel, an impurity will be added to a slab and there existed a problem in practical use. In view of the above prior art, in Patent Document 1, using a measuring bar in which a copper plating part is formed on the surface of the iron bar part, the thickness of the mold powder molten layer is accurately measured by melting or discoloring the copper plating part. is suggesting. However, it is the same as the prior art that there is a problem that copper plating is dissolved in molten steel.

  On the other hand, as a non-contact measurement method that does not affect the quality of the slab, there is a method of measuring the thickness of the mold powder molten layer using a plurality of frequencies and using both phase information and absolute value information at each frequency. Patent Documents 2 and 3 propose. In these multi-frequency eddy current measurement methods, the measurement accuracy may deteriorate depending on the type of mold powder and the temperature of the molten steel surface. For this reason, Patent Document 4 proposes a method of correcting the error due to the influence of the type of mold powder and the temperature of the molten steel surface and measuring with high accuracy. However, the multi-frequency eddy current sensor used in the multi-frequency eddy current measurement method is large in size and difficult to apply to a molten steel surface with a small area. It was. In addition, the multi-frequency eddy current sensor cannot measure the upper surface level of the powder layer necessary to grasp the total thickness of the mold powder (the sum of the thickness of the molten layer and the thickness of the powder layer above it). There was also a problem.

  By the way, as described above, it is within the range of about 150 to 200 mm from the lower surface of the electromagnetic level meter that the molten metal level can be accurately and stably measured by the electromagnetic level meter (vortex sensor or the like). On the other hand, the casting mold of the continuous casting equipment, particularly the casting mold of the slab continuous casting machine, has a height of about 900 mm. When casting is started in a continuous casting facility, a dummy bar is inserted into the mold from below to prevent the molten metal from leaking downward, but the upper end of the dummy bar is usually just in the middle of the mold height. It is positioned at a certain position. Therefore, if the lower surface of the electromagnetic level meter and the upper end of the mold are flush with each other, the molten metal starts to be injected into the mold from the tundish through the immersion nozzle, and the molten metal begins to accumulate in the mold. In the process of gradually rising the molten metal level, the molten metal level cannot be measured with the electromagnetic level meter for the molten metal level rise of about 300 to 250 mm from the lower surface of the electromagnetic level meter. On the other hand, it is important to measure the molten metal level from the initial stage of molten metal injection from the immersion nozzle in order to anticipate initial nozzle clogging or excessive injection, so measurement of the molten metal level over a wide range is desired. It was.

  In view of the above problems, Patent Documents 5 and 6 disclose that a thermocouple type is used until the molten metal level at the start of casting starts to rise and the molten metal level can be measured with an electromagnetic level meter. While measuring the molten metal level using a level meter, if the molten metal level reaches the measurable range of the electromagnetic level meter, switch the thermocouple level meter used to the electromagnetic level meter. Has been proposed. However, since the thermocouple type level meter is used by being embedded in a mold, there is a problem that the responsiveness is poor. Further, the thickness of the mold powder (the total thickness of the mold powder and the thickness of the mold powder molten layer) cannot be measured.

Japanese Patent Laid-Open No. 9-79805 JP 2005-221282 A JP 2006-205227 A JP 2007-21529 A Japanese Patent No. 3221990 Japanese Patent No. 3832358

  The present invention has been made in view of such prior art, and can continuously measure the molten metal level in a continuous casting mold from the beginning of molten metal injection, and the mold powder thickness can be measured. It is an object to provide a method capable of continuous measurement.

In order to solve the above-mentioned problems, the present invention has been intensively studied, and as a result, a microwave level meter has been put to practical use as a device for measuring the distance to the interface between powders and solids. Although it is inferior, we focused on the fact that the measurable range is wider than the eddy current sensor. In addition, microwaves are not affected by temperature changes in the air, and have the property of passing through an object. Therefore, it may be possible to detect the two interfaces between the upper surface of the mold powder and the molten metal surface separately. It was. Furthermore, it was considered that three interfaces of the upper surface of the mold powder, the upper surface of the mold powder molten layer, and the molten metal surface could be detected separately.
And measure the surface level outside the measuring range with an electromagnetic level meter, such as a conventional overflow sensor, with the microwave level meter, and the level is within the measuring range of the electromagnetic level meter. After reaching the mold level, the mold level is measured using the measured value of the microwave level meter and the measured value of the electromagnetic level meter that can detect the separation of two or three interfaces. I came up with the idea of measuring the thickness.
Based on the above idea, as a result of repeatedly performing various experiments and the like to be described later, a microwave level meter that transmits a microwave having a center frequency exceeding 20 GHz and not exceeding 32 GHz and a frequency modulation width exceeding 4 GHz and not exceeding 8 GHz. If so, the present inventors have found that the above-described idea can be realized and completed the present invention.

  That is, in order to solve the above-mentioned problems, the present invention provides an electromagnetic first level meter for measuring a molten metal surface level in a continuous casting mold and a frequency modulation with a center frequency exceeding 20 GHz and not exceeding 32 GHz. A microwave type level meter that transmits a microwave having a width of more than 4 GHz and not more than 8 GHz, wherein a range that overlaps with the measurement range set in the first level meter and a surface level in a range lower than this range. Using a measurable second level meter, the molten metal level measured value measured by the second level meter is used until the molten metal level reaches the lower limit of the measurement range set in the first level meter. After outputting the surface level, and the molten metal level reaches the lower limit of the measurement range set in the first level meter, the measured value of the molten metal level measured by the first level meter is output as the molten metal level. In addition The thickness of the mold powder charged on the molten metal is calculated based on the measured value of the first level meter and the measured value of the second level meter. A method for measuring a molten metal level and mold powder thickness is provided.

  According to the present invention, the molten metal level in the continuous casting mold can be continuously measured from the initial stage of the molten metal injection by the microwave second level meter having a wide measurable range, and Based on the measured value of the electromagnetic first level meter and the measured value of the second level meter, the mold powder thickness can be continuously measured.

  Regarding the measurement of the mold powder thickness in the present invention, specifically, the mold level is measured based on the measured value of the molten metal level measured by the first level meter and the measured value of the upper surface level of the mold powder measured by the second level meter. Calculate the total thickness of the powder, measure the upper surface level of the mold powder melt layer measured with the second level meter, measure the melt level measured with the second level meter, and the relative dielectric constant of the mold powder melt layer Based on the above, it is possible to calculate the thickness of the mold powder molten layer.

  According to the present invention, the molten metal level in the continuous casting mold can be continuously measured from the beginning of the molten metal injection, and the mold powder thickness can be continuously measured.

FIG. 1 is an explanatory diagram for explaining an outline of a first preliminary test performed when the present invention is completed. FIG. 2 uses a general-purpose microwave level meter (transmitting a microwave with a center frequency of 20 GHz and a frequency modulation width of 4 GHz) used for detecting the slag level of a converter as a microwave level meter. The test results are shown. FIG. 3 shows a test result when a microwave level meter that transmits a microwave having a center frequency of 32 GHz and a frequency modulation width of 8 GHz is used. FIG. 4 is a diagram showing an example of a spectrum waveform (obtained by performing FFT processing on the detected reflected wave) obtained from the detected reflected wave (the thickness of the mold powder P is 40 mm) with respect to the test result shown in FIG. is there. FIG. 5 is a diagram showing the results of the second preliminary test performed when the present invention is completed. FIG. 6 is a diagram schematically showing a configuration example of a measuring apparatus for carrying out a method for measuring a molten metal surface level and mold powder thickness in a continuous casting mold according to an embodiment of the present invention. FIG. 7 is a diagram illustrating an example of a result obtained by continuously measuring the molten steel surface level from the initial stage of molten steel injection using the measurement apparatus illustrated in FIG. 6.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings as appropriate.
First, a preliminary test performed when the present invention is completed will be described.
<First preliminary test>
FIG. 1 is an explanatory diagram for explaining an outline of a first preliminary test performed when the present invention is completed. FIG. 1A shows a schematic configuration of the apparatus used in the first preliminary test, and FIG. 1B shows the components of the mold powder used in the first preliminary test. In order to measure the molten metal level with a microwave level meter and to measure the total thickness of the mold powder, it is possible to detect the two interfaces between the upper surface of the mold powder and the molten metal level separately. is necessary. Moreover, the measurement resolution of 100 mm or less which is the mold powder thickness in actual operation is also required.

  As shown in FIG. 1A, in the first preliminary test, a microwave level meter including an antenna 1 for transmitting / receiving microwaves, an amplifier 2 and a personal computer 3 for data collection, and a mold powder are used. The apparatus provided with the metal housing | casing 4 to accommodate was used. Then, mold powder (room temperature powder) P having the components shown in FIG. 1B was accommodated in the casing 4 while changing its thickness, and the reflected wave of the microwave transmitted from the antenna 1 was detected. Then, the distance was measured from the detected reflected wave using an FMCW (Frequency Modulation Continuous Wave) method. The FMCW method is a method of transmitting a frequency-modulated continuous wave and obtaining a distance from a frequency difference (beat frequency) between the transmitted wave and the reflected wave.

FIG. 2 uses a general-purpose microwave level meter (transmitting a microwave with a center frequency of 20 GHz and a frequency modulation width of 4 GHz) used for detecting the slag level of a converter as a microwave level meter. The test results are shown. FIG. 2 shows the distance calculated based on the reflected wave on the bottom surface 41 of the housing 4 and the distance calculated based on the reflected wave on the upper surface of the mold powder P. The reflected wave at the bottom surface 41 of the housing 4 can be said to be a simulation of the reflected wave from the molten metal surface in actual operation since the housing 4 is made of metal.
As shown in FIG. 2, when the thickness of the mold powder P is 150 mm, the reflected wave on the upper surface of the mold powder P can be detected, and the distance can be calculated from the detected reflected wave. However, the thickness of the mold powder P Was 100 mm, the reflected wave on the upper surface of the mold powder P could not be detected, and the distance could not be calculated. Further, when the thickness of the mold powder P was 50 mm, the reflected wave on the upper surface of the mold powder P could be detected a little and the distance could be calculated, but it was not a clear reflected wave. This is considered to be caused by the fact that the wavelength of the general-purpose microwave becomes as long as a few tens of millimeters.

  Further, as shown in FIG. 2, the reflected wave at the bottom surface of the housing 4 can be detected, and the distance can be calculated from the detected reflected wave. It was found that the calculated distance has a correlation with the thickness of the mold powder P (the calculated distance increases as the thickness of the mold powder P increases). The calculated distance has a correlation with the thickness of the mold powder P. When the microwave passes through the mold powder P, it is influenced by the relative dielectric constant and thickness of the mold powder P, and the distance at the bottom surface of the housing 4 is reduced. This is considered to be caused by a delay in the detection time of the reflected wave.

Next, the same test was performed using a microwave level meter (wavelength of the microwave at this time is about 5 mm) that transmits a microwave having a center frequency of 32 GHz and a frequency modulation width of 8 GHz.
FIG. 3 shows a test result when a microwave level meter that transmits a microwave having a center frequency of 32 GHz and a frequency modulation width of 8 GHz is used. FIG. 3 shows the distance calculated based on the reflected wave on the bottom surface 4 of the housing 4 and the distance calculated based on the reflected wave on the upper surface of the mold powder P. FIG. 4 shows an example of a spectrum waveform (obtained by subjecting the detected reflected wave to the FFT processing) obtained from the detected reflected wave (the thickness of the mold powder P is 40 mm) for the test result shown in FIG. FIG. The horizontal axis in FIG. 4 represents the calculated distance, and the vertical axis represents the spectrum intensity of the reflected wave corresponding to each distance.
As shown in FIG. 4, in the case of the above microwave, even when the thickness of the mold powder P is 40 mm, the spectral intensity of the reflected wave on the upper surface of the mold powder P and the bottom surface 4 of the housing 4 Both of the reflected wave spectral intensities had a peak, and they could be detected separately.

  Similarly, the reflected wave on the upper surface of the mold powder P and the reflected wave on the bottom surface 4 of the housing 4 could be detected separately within a thickness range of 15 to 40 mm. That is, as shown in FIG. 3, the reflected wave on the upper surface of the mold powder P could be detected in the range of the thickness of the mold powder P from 15 to 40 mm, and the distance could be calculated from the detected reflected wave. In addition, as shown in FIG. 3, when the thickness of the mold powder P is in the range of 15 to 40 mm, the reflected wave on the bottom surface of the housing 4 can be detected, and the distance can be calculated from the detected reflected wave. Met.

  Here, as shown in FIG. 3, the distance calculated from the reflected wave at the bottom surface of the housing 4 has a correlation with the thickness of the mold powder P as in the case shown in FIG. It was found that the calculated distance increases as the number increases. For example, when the thickness of the mold powder P is 40 mm, the distance calculated from the reflected wave on the upper surface of the mold powder P is 484 mm and the distance calculated from the reflected wave on the bottom surface 4 of the housing 4 as shown in FIG. Is 545 mm, and the difference is 61 mm, which does not match the actual thickness 40 mm of the molding powder P. When the thickness of the mold powder P is 20 mm, the distance calculated from the reflected wave on the upper surface of the mold powder P is 500 mm, and the distance calculated from the reflected wave on the bottom surface 41 of the housing 4 is 532 mm. Is 32 mm and does not match the actual thickness 20 mm of the mold powder P. Since the reflected wave on the upper surface of the mold powder P propagates in the air, the distance calculated from the reflected wave on the upper surface of the mold powder P is close to the true value, while the reflected wave on the bottom surface 41 of the housing 4 is As described above, when the microwave passes through the mold powder P, the detection time is delayed due to the influence of the relative dielectric constant and thickness of the mold powder P. This is considered to be because the distance calculated from is larger than the true value.

If the measurement distance from the antenna 1 to the upper surface of the mold powder P is L ₂ , the measurement distance from the antenna 1 to the bottom surface 41 of the housing 4 is L ₁ , and the relative dielectric constant of the mold powder P is ε, the mold powder P It is considered that the thickness X can be expressed not by L ₁ -L ₂ but by the following formula (1).

Since the dielectric constant ε of the powder of the mold powder P is about 1.85, when the thickness of the molding powder P is 20 mm, L ₁ = 532 mm, L ₂ = 500 mm, ε = 1 in the above formula (1). Substituting .85 results in X = 23.5 mm. When the thickness of the molding powder P is 40 mm, substituting L ₁ = 545 mm, L ₂ = 484 mm, and ε = 1.85 into the above formula (1) yields X = 44.9 mm. Therefore, if the relative dielectric constant of the mold powder P is constant in the mold powder P, it can be said that the thickness of the mold powder P can be measured with an accuracy of ± 5 mm by the above formula (1).
The housing of the measurement distance L ₂ from the antenna 1 to the upper surface of the mold powder P was determined in order to be considered to be close to the true value, similarly considered close to the true value electromagnetic level meter (vortex sensor or the like) 4 of the measured distance to the bottom surface 41 is L, if aligned with the reference point of the measurement distance of the reference point and the microwave type level meter measuring the distance of the electromagnetic type level gauge, the mold powder P by L-L ₂ It is thought that the thickness of can be measured.

<Second preliminary test>
Unlike the first preliminary test in which the entire mold powder P is powder, in the actual operation, the part in contact with the molten metal and its vicinity are melted in the entire mold powder P (total thickness). . Since the relative dielectric constant of the powder mold powder P is different from the relative dielectric constant of the molten mold powder P, there is an error in the measurement result of the mold powder thickness (total thickness) based on the above formula (1). become.
Therefore, the present inventor confirmed whether or not the reflected wave from the upper surface of the mold powder molten layer can be detected using a microwave level meter that transmits a microwave having a center frequency of 32 GHz and a frequency modulation width of 8 GHz. A second preliminary test was conducted. Specifically, a steel material is melted in a high-frequency heating furnace, and mold powder P (thickness: about 20 mm, mass: 1.3 kg) is poured into the molten metal (molten steel) in 7 portions, and the mold is molded each time the material is fed. It was confirmed whether or not a reflected wave from the upper surface of the powder melt layer could be detected. From the same idea as the above-described formula (1), the measurement distance from the antenna 1 to the molten metal is L ₁ , the measurement distance from the antenna 1 to the upper surface of the mold powder molten layer is L ₃ , and the ratio of the mold powder molten layer When the dielectric constant was ε _L , it was confirmed whether or not the thickness X _L of the mold powder melt layer can be expressed by the following formula (2).

FIG. 5 is a diagram showing the results of the second preliminary test performed when the present invention is completed. The horizontal axis in FIG. 5 indicates the number of times the mold powder is charged, and the vertical axis indicates the measured thickness value of the mold powder molten layer. In FIG. 5, the data plotted with ▲ is calculated by the formula (2) using a microwave level meter (with relative dielectric constant ε _L = 35), and the data plotted with ■ is the data plotted with ■ The thickness of the mold powder molten layer measured using the measuring rod is shown.
As shown in FIG. 5, a microwave level meter can detect a reflected wave from the upper surface of the mold powder molten layer. It has a good correlation with the measured mold powder melt layer thickness. That is, it was found that the thickness of the mold powder melt layer can be measured using a microwave level meter.

  In addition to the first and second preliminary tests described above, through various preliminary tests, the present inventor applied a microwave having a center frequency exceeding 20 GHz and not exceeding 32 GHz and a frequency modulation width exceeding 4 GHz and not exceeding 8 GHz. It was conceived that the thickness of the mold powder (the total thickness of the mold powder and the thickness of the mold powder molten layer) can be measured with sufficient accuracy by using the microwave level meter to be transmitted.

<One Embodiment of the Present Invention>
Based on the preliminary test described above, the present invention has been completed. Hereinafter, an embodiment of the present invention will be described.
FIG. 6 is a diagram schematically showing a configuration example of a measuring apparatus for carrying out a method for measuring a molten metal surface level and mold powder thickness in a continuous casting mold according to an embodiment of the present invention.
As shown in FIG. 6, the measuring apparatus 100 of the present embodiment includes an electromagnetic first level meter 10 for measuring the molten metal surface level of the molten metal S in the continuous casting mold 50 and a center frequency of 20 GHz. A microwave type level meter for transmitting microwaves having a frequency modulation width of more than 32 GHz and a frequency modulation width of more than 4 GHz and less than 8 GHz, which overlaps the measurement range set in the first level meter 10 and lower than this And a second level meter 20 capable of measuring the hot water level in the range. In addition, the measuring apparatus 100 of this embodiment includes a determination device 40 to which the output of the first level meter 10 and the output of the amplifier 30 connected to the second level meter 20 are input.

  The molten metal S supplied from the immersion nozzle 60 is injected into the mold 50, a solidified shell S <b> 1 is generated by cooling from the mold 50, and is drawn out below the mold 50. Powder mold powder P is introduced into the mold 50 for the purpose of keeping the coated molten metal S warm and covering, lubricating the mold 50 and the solidified shell S1, and the like. A molding powder molten layer P1 is formed at and near the portion of the mold powder P that is in contact with the molten metal S, and the powder layer P2 remains on the molding powder P1.

The determination device 40 of the present embodiment is configured to measure the molten metal level measured by the second level meter 20 until the molten metal level reaches the lower limit of the measurement range set in the first level meter 10 ( the level measurement value) calculated from the measured distance L ₁ to the molten metal surface from the second level meter 20 outputs a bath level level. On the other hand, after the molten metal level reaches the lower limit of the measurement range set in the first level meter 10, the determination device 40 determines the molten metal level measured value (first value) measured by the first level meter 10. The level measurement value calculated from the measurement distance L from the level meter 10 to the molten metal surface is output as the molten metal surface level. Further, the determination device 40 determines the thickness of the mold powder P put on the molten metal S (the total thickness of the mold powder P and the mold powder based on the measured value of the first level meter 10 and the measured value of the second level meter 20. The thickness of the molten layer P1) is calculated.

Specifically, the determination device 40 determines the total amount of the mold powder P based on the molten metal level measurement value measured by the first level meter 10 and the upper surface level measurement value of the mold powder P measured by the second level meter 20. Calculate the thickness. More specifically, the reference point of the measurement distance of the first level meter 10 and the reference point of the measurement distance of the second level meter 20 are aligned, and the measurement distance to the molten metal surface measured by the first level meter 10 Is L, and the measurement distance to the upper surface of the mold powder P measured by the second level meter 20 is L ₂ , the determination device 40 calculates L−L ₂ as the total thickness of the mold powder P.
The determination device 40 also measures the upper surface level measurement value of the mold powder molten layer P1 measured by the second level meter 20, the molten metal surface level measurement value measured by the second level meter 20, and the relative dielectric constant of the mold powder molten layer P1. based on the rate epsilon _L, calculates the thickness X _L of mold powder melting layer P1. More specifically, if the measured distance L ₃ to the upper surface of the mold powder melting layer P1 measured at a second level meter 20, the measurement distance to the molten metal surface was measured at the second level meter 20 and the L _1, by the aforementioned equations (2) to calculate the thickness X _L of mold powder melting layer P1.

  FIG. 7 is a diagram showing an example of a result obtained by continuously measuring the molten steel level from the initial stage of molten steel injection using the measuring apparatus 100 according to the present embodiment. In FIG. 7, a dummy bar D is inserted into the mold 50 from below, and injection of the molten steel S from the immersion nozzle 60 into the mold 50 is started. After the start of pouring, the level of the molten steel S in the mold 50 gradually increases and reaches the measurement range of the first level meter 10 (150 mm in the example shown in FIG. 7). Accordingly, immediately after the start of injection, the level level is outside the measurement range of the first level meter 10, so the molten metal level is measured by the second level meter 20. After the molten metal level reaches the measurement range of the first level meter 10, the molten metal surface level is controlled according to the molten metal surface level measured by the first level meter 10, and casting is started. Normally, when the molten metal surface rises higher than the discharge hole of the immersion nozzle 60 and the mold powder P is not caught in the discharge hole, the mold powder P is put on the molten metal surface and casting is started. While the measurement of the molten metal surface level by the second level meter 20 is continued as it is, after the mold powder P is charged, the upper surface level of the mold powder P and the upper surface level of the mold powder molten layer P1 are further measured (FIG. 7). , The portion surrounded by a broken line indicates a state in which three levels are measured), and the total thickness of the mold powder P and the thickness of the mold powder molten layer P1 are continuously measured.

DESCRIPTION OF SYMBOLS 10 ... 1st level meter 20 ... 2nd level meter 50 ... Mold S ... Molten metal 100 ... Measuring apparatus

Claims (2)

Electromagnetic first level meter for measuring the level of molten metal in a continuous casting mold and a microwave with a center frequency exceeding 20 GHz and 32 GHz or less and a frequency modulation width exceeding 4 GHz and 8 GHz or less. A microwave type level meter using a second level meter capable of measuring a range overlapping with a measurement range set in the first level meter and a level level lower than the measurement range,
Until the molten metal level reaches the lower limit of the measurement range set in the first level meter, the molten metal level measured value measured by the second level meter is output as the molten metal level.
After the molten metal level reaches the lower limit of the measurement range set in the first level meter, the measured value of the molten metal level measured by the first level meter is output as the molten metal level, and the first level is measured. The molten metal surface level and mold in the continuous casting mold, wherein the thickness of the mold powder charged on the molten metal is calculated based on the measured value of the level meter and the measured value of the second level meter. Powder thickness measurement method. Based on the molten metal level measurement value measured with the first level meter and the upper surface level measurement value of the mold powder measured with the second level meter, the total thickness of the mold powder is calculated,
Based on the measured value of the upper surface level of the mold powder molten layer measured by the second level meter, the measured value of the molten metal surface level measured by the second level meter, and the relative dielectric constant of the mold powder molten layer, The method for measuring a molten metal surface level and mold powder thickness in a continuous casting mold according to claim 1, wherein the thickness of the mold is calculated.

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