WO2016017028A1 - Eddy current-type mold level measurement device and mold level measurement method - Google Patents

Eddy current-type mold level measurement device and mold level measurement method Download PDF

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Publication number
WO2016017028A1
WO2016017028A1 PCT/JP2014/070340 JP2014070340W WO2016017028A1 WO 2016017028 A1 WO2016017028 A1 WO 2016017028A1 JP 2014070340 W JP2014070340 W JP 2014070340W WO 2016017028 A1 WO2016017028 A1 WO 2016017028A1
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Prior art keywords
mold
oscillation
eddy current
level
mold oscillation
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PCT/JP2014/070340
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French (fr)
Japanese (ja)
Inventor
文雄 小山
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株式会社ニレコ
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Application filed by 株式会社ニレコ filed Critical 株式会社ニレコ
Priority to PCT/JP2014/070340 priority Critical patent/WO2016017028A1/en
Priority to JP2015024950A priority patent/JP5782202B1/en
Priority to EP15176759.7A priority patent/EP2980538B1/en
Priority to US14/809,582 priority patent/US9816851B2/en
Priority to TW104124326A priority patent/TW201606270A/en
Priority to CN201510459980.6A priority patent/CN105312510B/en
Priority to KR1020150108511A priority patent/KR102242430B1/en
Publication of WO2016017028A1 publication Critical patent/WO2016017028A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields

Definitions

  • the present invention relates to an eddy current mold level measuring device and a mold level measuring method used in a continuous casting facility.
  • the continuous casting equipment is equipment for producing a slab of a predetermined shape by continuously injecting molten metal into a mold, cooling and solidifying it.
  • measuring and controlling the level of the surface of the molten metal in the mold, that is, the mold level, is very important for improving the quality of the slab to be produced.
  • the eddy current mold level measuring device indicates that the strength of the voltage induced in the detection coil by the eddy current generated on the surface of the molten metal in the mold varies depending on the distance between the detection coil and the surface of the molten metal. It is used to measure the level of the surface of the molten metal in the mold.
  • the eddy current mold level measuring apparatus is excellent in responsiveness and suitable for high-precision control of the level of the surface of the molten metal in the mold, but is easily affected by the ambient temperature and electromagnetic environment. Therefore, in the eddy current mold level measuring apparatus, calibration is very important.
  • JP 61-239120 A JP-A-2-140621 JP-A-8-233632
  • the eddy current mold level measuring apparatus measures a level of molten metal in a mold, and includes a detection unit including a coil for detecting a change in impedance value due to a change in mold level; The amplification unit that amplifies the output of the detection unit and the amplification so that the difference between the maximum value and the minimum value of the output of the measuring device at the time of mold oscillation indicates the amplitude value of the mold oscillation And a mold oscillation calibration unit configured to calibrate the positive feedback rate of the unit.
  • the eddy current mold level measuring apparatus of this aspect performs calibration using the change in the output of the eddy current mold level measuring apparatus and the known amplitude value of the mold oscillation, so that high accuracy is achieved.
  • other types of level meters such as a thermocouple type mold level meter and an electrode type level meter are not required for the calibration.
  • the mold oscillation calibration unit is configured to provide a maximum value and a minimum value of the output of the measurement device during a mold oscillation period. Are sequentially obtained, and the positive feedback rate of the amplifying unit is sequentially calibrated.
  • the eddy current mold level measuring apparatus of the present embodiment calibration can be performed sequentially throughout the drawing period. Therefore, it is possible to sufficiently cope with dynamic disturbance factors such as tundish up / down during casting and width change in the slab mold.
  • the mold oscillation calibration unit receives a signal representing a mold oscillation cycle from the outside, and the mold oscillation A period for performing calibration by mold oscillation is determined according to a signal representing a cycle.
  • the eddy current mold level measuring apparatus of the present embodiment appropriately determines the start and end times of calibration during the mold oscillation period by referring to a signal representing the mold oscillation cycle received from the outside.
  • the signal representing the mold oscillation cycle includes a signal proportional to the mold oscillation cycle and a signal having a phase opposite to that of the mold oscillation.
  • the mold oscillation calibration unit determines the amplitude value of the mold oscillation based on an external input, The amplitude value is used to calibrate the positive feedback factor of the amplifying unit.
  • the eddy current mold level measuring apparatus of the present embodiment achieves high accuracy by determining the amplitude value of the mold oscillation based on the input from the outside and performing calibration using the amplitude value. Can do.
  • the eddy current mold level measuring apparatus further includes a filter set to detect only components due to mold oscillation, and the mold oscillation calibration unit includes: When the difference between the maximum value and the minimum value of the output of the measuring device during mold oscillation is obtained, the signal that has passed through the filter is used.
  • the eddy current mold level measuring apparatus uses a signal that has passed through a filter that is set to detect only the component due to mold oscillation, thereby causing fluctuations in the molten metal surface other than mold oscillation. The influence of disturbance can be eliminated.
  • the mold level measuring method is a method for measuring the level of molten metal in a mold by means of an eddy current mold level measuring device.
  • the mold level measuring method of this aspect calibration is performed using the change in the output of the eddy current mold level measuring apparatus and the known amplitude value of the mold oscillation, so that high accuracy is achieved.
  • other types of level meters such as a thermocouple type mold level meter and an electrode type level meter are not required for the calibration.
  • the difference between the maximum value and the minimum value of the output of the measuring device is sequentially obtained during the mold oscillation period,
  • the positive feedback factor of the amplifier is calibrated sequentially.
  • the mold level measurement method of the present embodiment calibration can be performed sequentially throughout the drawing period. Therefore, it is possible to sufficiently cope with dynamic disturbance factors such as tundish up / down during casting and width change in the slab mold.
  • FIG. 1 is a diagram showing a configuration of a continuous casting facility.
  • Molten metal such as molten steel stored in the tundish 210 is injected into the mold 310 through the immersion nozzle 220, cooled and solidified in the mold 310, and sent out from the mold 310 by the pinch roll 330.
  • the mold 310 is provided with a mold oscillation device 320 that generates mold oscillation. Mold oscillation will be described later.
  • the eddy current mold level measuring device measures the level of the surface 400 of the molten metal in the mold.
  • the eddy current mold level measuring apparatus includes a detection unit 105 and a signal processing unit 110.
  • the detection unit 105 and the signal processing unit 110 are connected by a cable 1055. Since the detection unit 105 is located near the molten metal, a joint unit 1053 and an air pipe 1051 are installed to send cooling air to the detection unit 105.
  • FIG. 2 is a diagram showing a configuration of the eddy current mold level measuring apparatus 100 according to an embodiment of the present invention.
  • the eddy current mold level measuring apparatus 100 includes the detection unit 105 and the signal processing unit 110.
  • the detection unit 105 includes a drive coil 105C1, a detection coil 105C2, and a reference coil 105C3.
  • the signal processing unit 110 includes a signal amplification unit 120, an output generation unit 130, a mold / oscillation calibration unit 140, and a pre-pouring calibration unit 150.
  • a current having a constant frequency is applied to the drive coil 105C1, and the drive coil 105C1 generates an alternating magnetic field.
  • This AC magnetic field passes through the detection coil 105C2 and the reference coil 105C3.
  • an eddy current is generated in the molten metal, and the impedance of the detection coil 105C2 changes as a reaction.
  • the change in impedance of the detection coil 105C2 changes according to the distance between the detection coil 105C2 and the molten metal surface.
  • the distance between the detection coil 105C2 and the molten metal surface can be measured by measuring the change in impedance of the detection coil 105C2.
  • the signal amplification unit 120 uses a difference between the impedance of the detection coil 105C2 and the impedance of the reference coil 105C3.
  • the present invention can be applied to any type of eddy current mold level measuring device other than the differential type of the present embodiment.
  • the signal amplifying unit 120 includes a reference oscillator 1201 that generates an AC voltage having a constant frequency and a constant amplitude, a feedback amplifier 1203, a feedback impedance 1205 having a variable positive feedback rate K, an impedance of the detection coil 105C2, and a reference coil 105C3.
  • a differential amplifier 1207 that receives the difference from the impedance as an input, and an amplitude modulator 1209 that amplitude-modulates the AC voltage output from the feedback amplifier 1203 are included.
  • the output voltage of the reference oscillator 1201 is V in
  • the output voltage of the feedback amplifier 1203 is V out
  • the amplification factor of the feedback amplifier 1203 is G1
  • the amplification factor of the differential amplifier 1207 is G2
  • the positive feedback factor is K
  • the molten metal level is Assuming h, the following equation is established.
  • f is a function of the level h of the molten metal.
  • f (h) increases in Equation (1). Therefore, when the level h of the molten metal increases, the absolute value
  • the eddy current mold level measuring device detects a change in impedance of the detection coil 105C2 due to a change in the level h of the molten metal surface in the mold 310 according to the equation (1).
  • the impedance of the detection coil 105C2 varies depending not only on the level of the molten metal surface in the mold 310 but also on the temperature and the surrounding electromagnetic environment. Therefore, in the measurement by the eddy current mold level measuring device, the eddy current mold level measuring device needs to be calibrated.
  • FIG. 3 is a diagram for explaining a calibration method of the eddy current mold level measuring apparatus.
  • Calibration of the eddy current mold level measuring device includes calibration by a calibration plate and calibration before pouring the mold.
  • Calibration with a calibration plate is performed independently of the continuous casting process.
  • the output voltage of the feedback amplifier 1203 is measured and recorded while changing the distance between the detection coil 105C2 and the metal calibration plate.
  • the horizontal axis in FIG. 3 represents the level of the molten metal surface or calibration plate. The level is indicated by the distance between the detection coil 105C2 and the molten metal surface or the calibration plate. Level 0 is a state in which the distance between the detection coil 105C2 and the molten metal surface or the calibration plate is zero.
  • the vertical axis in FIG. 3 represents the output voltage of the feedback amplifier 1203.
  • a solid line R1 in FIG. 3 indicates the result of calibration by the calibration plate.
  • the output voltage corresponding to the distance between the detection coil 105C2 and the calibration plate within this range is measured. Furthermore, when removing the calibration plate, i.e., the output voltage V 01 where the distance between the calibration plate and the detection coil 105C2 is infinite is measured. This output voltage V 01 is referred to as a reference voltage.
  • the positive feedback rate K is adjusted as necessary so as to appropriately determine the shape of the solid line R1.
  • Calibration before pouring into the mold is performed by the pre-pouring calibration unit 150 in the continuous casting process.
  • the pre-pouring calibration unit 150 records a value obtained by processing the output voltage of the feedback amplifier 1203 by the linearizer 1305 before pouring into the mold.
  • Calibration before pouring may be performed according to an operator command.
  • the state before pouring corresponds to the state where the distance between the detection coil 105C2 and the calibration plate is infinite. Therefore, the output voltage of the feedback amplifier 1203 measured before pouring into the mold should be equal to the reference voltage V 01 described above. However, in practice, the measured voltage may not be equal to the reference voltage V 01 because the temperature and surrounding electromagnetic environment vary with casting conditions.
  • one-dot chain line A1 shows a case where the output voltage V measured before pouring is greater than V 01, two-dot chain line B1, when the output voltage V measured before pouring is less than V 01 Indicates.
  • the pre-pouring calibration unit 150 adjusts the positive feedback rate K in Expression (1) so that the output voltage V of the feedback amplifier 1203 becomes equal to the reference voltage V 01 .
  • one-dot chain line A1 increases the positive feedback ratio K so as to match the V 01 to reduce the V level meter output.
  • two-dot chain line B1 decreases the positive feedback ratio K so as to match the V 01 to increase the level meter output V. Calibration before pouring the mold is performed for each casting.
  • FIG. 4 is a diagram showing the relationship between the mold level and the output voltage of the feedback amplifier 1203. 3 represents the mold level, and the vertical axis in FIG. 4 represents the output voltage of the feedback amplifier 1203.
  • the position of the detection coil 105C2 is set to a mold level 0.
  • the output generation unit 130 illustrated in FIG. 2 includes a mold oscillation filter (MOF) 1301 that removes the influence of the fluctuation of the molten metal surface due to mold oscillation, which will be described later, an analog-digital converter 1303, A linearizer 1305.
  • the linearizer 1305 performs linearization so that the ratio between the change amount of the level meter output and the change amount of the mold level becomes a constant value.
  • Two types of signals, a signal that has not passed through the mold oscillation filter 1301 and a signal that has passed through the mold oscillation filter 1301, are input to the analog-to-digital converter 1303.
  • the output of the analog / digital converter 1303 is input to the linearizer 1305.
  • the output corresponding to the signal that has passed through the mold oscillation filter 1301 is the output of the eddy current mold level measuring device.
  • the output corresponding to the signal not passing through the mold oscillation filter 1301 is used by the mold oscillation calibration unit 140.
  • the function of the mold oscillation calibration unit 140 including the mold oscillation filter 1301 will be described later.
  • FIG. 5 is a diagram showing the relationship between the mold level and the level meter output.
  • the level meter output is obtained by linearizing the output of the feedback amplifier 1203 by the linearizer 1305.
  • the horizontal axis in FIG. 5 represents the mold level, and the vertical axis in FIG. 5 represents the output of the eddy current mold level measuring apparatus.
  • FIG. 6 is a diagram for explaining the continuous casting process.
  • the continuous casting process includes a pouring stage for supplying molten metal from the tundish 210 to the mold 310 until the molten metal surface 400 in the mold 310 rises to a certain level, and the molten metal from the tundish 210 to the mold 310. And a drawing step of drawing the solidified metal from the mold 310 while supplying.
  • a dummy bar forming the bottom is installed in the mold 310, and the molten metal is accumulated while solidifying in the area surrounded by the mold 310 and the dummy bar, and the surface of the molten metal, that is, the mold level is increased. I will do it.
  • the process proceeds to the drawing stage.
  • Pulling out means that a metal having a shape such as a plate shape or a bar shape solidified in the mold 310 is taken out of the mold by the pinch roll 330 below the mold 310.
  • the surface of the molten metal Prior to the start of drawing, the surface of the molten metal is sprayed onto the surface of the molten metal, preventing oxidation of the surface of the molten metal and acting as a lubricant between the solidified metal and the mold.
  • mold oscillation MOS
  • the amplitude stroke of mold oscillation is 2 to 6 millimeters, and the period of mold oscillation is 30 to 450 cycles per minute. Drawing is started after the start of mold oscillation, and the mold oscillation is continuously performed while the drawing is performed.
  • the above-described calibration before pouring of the vortex mold level measuring device 100 is performed before the pouring of the mold 310 is started.
  • the level of molten metal in the mold 310 increases.
  • mold level measurement by the eddy current mold level measuring device 100 is performed.
  • mold oscillation calibration (MOSC) described below is performed during the mold oscillation period.
  • the output generation unit 130 receives a signal proportional to the mold oscillation cycle from the control device (not shown in FIG. 1) of the mold oscillation device 320 in FIG.
  • the output generation unit 130 changes the stop band of the mold oscillation filter 1301 according to the cycle value (frequency) of this signal.
  • the mold oscillation filter 130 removes the influence of the fluctuation of the molten metal surface due to mold oscillation in the level meter output by removing the component of mold oscillation from the output of the signal amplification unit 120.
  • an adder that adds a signal of the opposite phase of the mold oscillation received from the above-described control device to the output of the signal amplification unit 120 is provided.
  • FIG. 7 is a flowchart for explaining the mold oscillation calibration function performed by the mold oscillation calibration unit 140 of the eddy current mold level measuring apparatus 100.
  • step S1010 the mold oscillation calibration unit 140 determines whether to start MOSC. If so, the process proceeds to step S1020. If not, wait.
  • the mold oscillation calibration unit 140 determines a time point at which the MOSC is started by a signal proportional to the above-described mold oscillation cycle or a signal having a phase opposite to that of the mold oscillation.
  • the fluctuation cycle of the molten metal surface (molten metal surface) in a steady state is 0.1 to 0.5 hertz.
  • the mold oscillation calibration unit 140 is provided with a filter such as a high-pass filter or a band-pass filter having a pass band corresponding to the mold oscillation period, detects the component of the mold oscillation, and the size thereof is You may make it start MOSC when it becomes more than predetermined value. In the following steps, the output of the above filter may be used.
  • the mold oscillation calibration unit 140 acquires and updates the maximum value and the minimum value of the output of the signal amplification unit 120.
  • the mold oscillation calibration unit 140 determines a predetermined period that is equal to or greater than the mold oscillation cycle, and the maximum value and the minimum value of the period from the time point that precedes the predetermined time period from the update time point to the update time point. May be requested. In this way, when at least one of the maximum value and the minimum value changes, the mold oscillation calibration unit 140 can sequentially measure the maximum value and the minimum value while grasping the change. .
  • the mold oscillation calibration unit 140 obtains a difference between the maximum value and the minimum value of the output of the signal amplification unit 120, and the difference is a value of the known amplitude stroke of the mold oscillation. As shown, the positive feedback factor K of the signal amplifier 120 is determined. As described above, the value of the amplitude stroke of the mold oscillation is in the range of 2 to 6 millimeters and varies depending on the object to be cast. Therefore, the mold oscillation calibration unit 140 may determine the value of the amplitude stroke by using a signal proportional to the mold oscillation cycle described above or a signal having a phase opposite to that of the mold oscillation. Or you may make it receive the value of an amplitude stroke for every casting from the outside, such as a control apparatus and an operator.
  • FIG. 8 is a diagram for explaining a method of determining the positive feedback rate K in step S1030 of FIG.
  • S 0 be the known value of the amplitude stroke.
  • the level meter output difference ⁇ V 0 corresponding to the known value S 0 of the amplitude stroke is obtained.
  • the level meter output difference ⁇ V corresponding to the known value S 0 of the amplitude stroke is equal to ⁇ V 0 .
  • the difference [Delta] V of the level meter output corresponding to a known value S 0 of the amplitude stroke is greater than the [Delta] V 0.
  • the difference [Delta] V of the level meter output corresponding to a known value S 0 of the amplitude stroke is smaller than [Delta] V 0.
  • one-dot chain line A2 is to reduce the difference [Delta] V of the level meter output to increase the positive feedback ratio K so as to coincide with the [Delta] V 0.
  • two-dot chain line B2 is to increase the difference [Delta] V of the level meter output to reduce the positive feedback ratio K so as to coincide with the [Delta] V 0.
  • step S1040 the mold oscillation calibration unit 140 sets the newly determined positive feedback rate K to the feedback impedance 1205.
  • step S1050 of FIG. 7 the mold oscillation calibration unit 140 determines whether to end the MOSC.
  • the mold oscillation calibration unit 140 determines a time point at which the MOSC is terminated by the above-described mold oscillation cycle signal. If the process is to be terminated, the process is terminated. If not finished, the process returns to step S1020.
  • the MOSC since the calibration is performed using the change in the output of the eddy current mold level measuring device and the known amplitude stroke value of the mold oscillation, high accuracy is achieved. Further, as shown in FIG. 6, according to the MOSC, calibration can be performed sequentially throughout the drawing period. Therefore, it is possible to sufficiently cope with dynamic disturbance factors such as tundish up / down during casting and width change in the slab mold. As described above, the MOSC can realize an eddy current mold level measuring apparatus having sufficiently high accuracy and capable of dealing with a dynamic disturbance factor. Further, since the calibration is performed using the output of the eddy current mold level measuring device itself, other types of level meters such as a thermocouple type mold level meter and an electrode type level meter are not required for the calibration.

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Abstract

Provided is an eddy current-type mold level measurement device which has sufficiently high accuracy and which can handle dynamic disturbance factors. This eddy current-type mold level measurement device measures the level of molten metal in a mold, and is provided with: a detection unit having a coil for detecting change in the impedance value, which depends on change in the mold level; an amplification unit which amplifies output of the detection unit; and a mold oscillation calibration unit which calibrates the positive feedback rate of the amplification unit such that during mold oscillation, the difference between the maximum value and the minimum value of the output of said measurement device exhibits the amplitude value of the mold oscillation.

Description

渦流式モールドレベル測定装置及びモールドレベル測定方法Eddy current mold level measuring apparatus and mold level measuring method
　本発明は、連続鋳造設備において使用される渦流式モールドレベル測定装置及びモールドレベル測定方法に関する。 The present invention relates to an eddy current mold level measuring device and a mold level measuring method used in a continuous casting facility.
　連続鋳造設備は、溶融金属を連続的にモールドに注入し、冷却・凝固させて所定の形状の鋳片を製造するための設備ある。連続鋳造設備において、モールド内の溶融金属の表面のレベル、すなわちモールドレベルを測定し、制御することは、製造される鋳片の品質を向上させる上で非常に重要である。 The continuous casting equipment is equipment for producing a slab of a predetermined shape by continuously injecting molten metal into a mold, cooling and solidifying it. In a continuous casting facility, measuring and controlling the level of the surface of the molten metal in the mold, that is, the mold level, is very important for improving the quality of the slab to be produced.
　渦流式モールドレベル測定装置は、モールド内の溶融金属の表面に発生させた渦電流によって検出コイルに誘起される電圧の強さが検出コイルと溶融金属の表面との間の距離によって変化することを利用して、モールド内の溶融金属の表面のレベルを測定するものである。渦流式モールドレベル測定装置は、応答性に優れ、モールド内の溶融金属の表面のレベルの高精度の制御に適するが、周囲の温度、及び電磁的環境の影響を受けやすい。したがって、渦流式モールドレベル測定装置においては、較正（キャリブレーション）が非常に重要である。従来の渦流式モールドレベル測定装置の較正方法としては、オペレータの目視による測定値などを利用するもの（たとえば、特許文献１）、熱電対式のモールドレベル計を利用するもの（たとえば、特許文献２）、電極式レベル計を利用するもの（たとえば、特許文献３）などが開発されていた。しかし、いずれの方法によるものも、精度が十分ではなく、また、鋳造中におけるタンディッシュの上下降やスラブモールドにおける幅替えなどの動的外乱要因に対応することはできなかった。特に、ブルーム・ビレットなど小断面モールドの場合には、タンディッシュの上下降の、渦流式モールドレベル測定装置による測定への影響が顕著であり、測定精度を向上させる障害となっていた。換言すれば、従来のいずれの方法も精度、動的外乱要因への対応などに問題があった。 The eddy current mold level measuring device indicates that the strength of the voltage induced in the detection coil by the eddy current generated on the surface of the molten metal in the mold varies depending on the distance between the detection coil and the surface of the molten metal. It is used to measure the level of the surface of the molten metal in the mold. The eddy current mold level measuring apparatus is excellent in responsiveness and suitable for high-precision control of the level of the surface of the molten metal in the mold, but is easily affected by the ambient temperature and electromagnetic environment. Therefore, in the eddy current mold level measuring apparatus, calibration is very important. As a calibration method of a conventional eddy current mold level measuring device, a method using an operator's visual measurement value (for example, Patent Document 1) or a method using a thermocouple type mold level meter (for example, Patent Document 2). ) And those using an electrode type level meter (for example, Patent Document 3) have been developed. However, the accuracy of either method is not sufficient, and it has not been possible to cope with dynamic disturbance factors such as tundish up and down during casting and width change in a slab mold. In particular, in the case of a small-section mold such as a bloom billet, the influence of the tundish up and down on the measurement by the eddy current mold level measuring device is remarkable, which has been an obstacle to improve the measurement accuracy. In other words, any of the conventional methods has problems in accuracy, response to dynamic disturbance factors, and the like.
特開昭６１－２３９１２０号公報JP 61-239120 A 特開平２－１４０６２１号公報JP-A-2-140621 特開平８－２３３６３２号公報JP-A-8-233632
　したがって、十分に高い精度を有し、動的外乱要因へ対応することのできる渦流式モールドレベル測定装置に対するニーズがある。 Therefore, there is a need for an eddy current mold level measuring device that has sufficiently high accuracy and can cope with dynamic disturbance factors.
　本発明の第１の態様の渦流式モールドレベル測定装置は、モールド内の溶融金属のレベルを測定するものであって、モールドレベルの変化によるインピーダンス値の変化を検出するコイルを備えた検出部と、該検出部の出力を増幅する増幅部と、モールド・オシレーションの際の該測定装置の出力の最大値と最小値との差が、モールド・オシレーションの振幅の値を示すように該増幅部の正帰還率を較正するように構成されたモールド・オシレーション較正部と、を備えている。 The eddy current mold level measuring apparatus according to the first aspect of the present invention measures a level of molten metal in a mold, and includes a detection unit including a coil for detecting a change in impedance value due to a change in mold level; The amplification unit that amplifies the output of the detection unit and the amplification so that the difference between the maximum value and the minimum value of the output of the measuring device at the time of mold oscillation indicates the amplitude value of the mold oscillation And a mold oscillation calibration unit configured to calibrate the positive feedback rate of the unit.
　本態様の渦流式モールドレベル測定装置は、渦流式モールドレベル測定装置の出力の変化分、及びモールド・オシレーションの既知の振幅の値を使用して較正を行うので、高精度が達成される。また、渦流式モールドレベル測定装置自身の出力を使用して較正を行うので、較正に、熱電対式のモールドレベル計や電極式レベル計などの他のタイプのレベル計を必要としない。 The eddy current mold level measuring apparatus of this aspect performs calibration using the change in the output of the eddy current mold level measuring apparatus and the known amplitude value of the mold oscillation, so that high accuracy is achieved. In addition, since the calibration is performed using the output of the eddy current mold level measuring apparatus itself, other types of level meters such as a thermocouple type mold level meter and an electrode type level meter are not required for the calibration.
　本発明の第１の態様の第１の実施形態の渦流式モールドレベル測定装置において、該モールド・オシレーション較正部は、モールド・オシレーションの期間中に該測定装置の出力の最大値と最小値との差を逐次的に求め、該増幅部の正帰還率を逐次的に較正するように構成されている。 In the eddy current mold level measurement device according to the first embodiment of the first aspect of the present invention, the mold oscillation calibration unit is configured to provide a maximum value and a minimum value of the output of the measurement device during a mold oscillation period. Are sequentially obtained, and the positive feedback rate of the amplifying unit is sequentially calibrated.
　本実施形態の渦流式モールドレベル測定装置によれば、引き抜き期間を通して逐次的に較正を実施することができる。したがって、鋳造中におけるタンディッシュの上下降やスラブモールドにおける幅替えなどの動的外乱要因に十分に対応することができる。 According to the eddy current mold level measuring apparatus of the present embodiment, calibration can be performed sequentially throughout the drawing period. Therefore, it is possible to sufficiently cope with dynamic disturbance factors such as tundish up / down during casting and width change in the slab mold.
　本発明の第１の態様の第２の実施形態の渦流式モールドレベル測定装置において、該モールド・オシレーション較正部は、モールド・オシレーション・サイクルを表す信号を外部から受け取り、該モールド・オシレーション・サイクルを表す信号にしたがって、モールド・オシレーションによる較正を行う期間を定めるように構成されている。 In the eddy current mold level measuring apparatus according to the second embodiment of the first aspect of the present invention, the mold oscillation calibration unit receives a signal representing a mold oscillation cycle from the outside, and the mold oscillation A period for performing calibration by mold oscillation is determined according to a signal representing a cycle.
　本実施形態の渦流式モールドレベル測定装置は、外部から受け取ったモールド・オシレーション・サイクルを表す信号を参照することにより、モールド・オシレーション期間中の較正の開始及び終了時期を適切に判断することができる。ここで、モールド・オシレーション・サイクルを表す信号は、モールド・オシレーション・サイクルに比例した信号、及びモールド・オシレーションの逆位相の信号を含む。 The eddy current mold level measuring apparatus of the present embodiment appropriately determines the start and end times of calibration during the mold oscillation period by referring to a signal representing the mold oscillation cycle received from the outside. Can do. Here, the signal representing the mold oscillation cycle includes a signal proportional to the mold oscillation cycle and a signal having a phase opposite to that of the mold oscillation.
　本発明の第１の態様の第３の実施形態の渦流式モールドレベル測定装置において、該モールド・オシレーション較正部は、外部からの入力に基づいてモールド・オシレーションの振幅の値を定め、該振幅の値を使用して該増幅部の正帰還率を較正するように構成されている。 In the eddy current mold level measuring apparatus according to the third embodiment of the first aspect of the present invention, the mold oscillation calibration unit determines the amplitude value of the mold oscillation based on an external input, The amplitude value is used to calibrate the positive feedback factor of the amplifying unit.
　本実施形態の渦流式モールドレベル測定装置は、外部からの入力に基づいてモールド・オシレーションの振幅の値を定め、該振幅の値を使用して較正を行うことにより、高い精度を実現することができる。 The eddy current mold level measuring apparatus of the present embodiment achieves high accuracy by determining the amplitude value of the mold oscillation based on the input from the outside and performing calibration using the amplitude value. Can do.
　本発明の第１の態様の第４の実施形態の渦流式モールドレベル測定装置は、モールド・オシレーションによる成分のみを検出するように設定されたフィルタをさらに備え、該モールド・オシレーション較正部は、モールド・オシレーションの際の該測定装置の出力の最大値と最小値との差を求める際に、該フィルタを通した信号を使用するように構成されている。 The eddy current mold level measuring apparatus according to the fourth embodiment of the first aspect of the present invention further includes a filter set to detect only components due to mold oscillation, and the mold oscillation calibration unit includes: When the difference between the maximum value and the minimum value of the output of the measuring device during mold oscillation is obtained, the signal that has passed through the filter is used.
　本実施形態の渦流式モールドレベル測定装置は、モールド・オシレーションによる成分のみを検出するように設定されたフィルタを通した信号を使用することにより、モールド・オシレーション以外の溶融金属面の変動による外乱の影響を除去することができる。 The eddy current mold level measuring apparatus according to the present embodiment uses a signal that has passed through a filter that is set to detect only the component due to mold oscillation, thereby causing fluctuations in the molten metal surface other than mold oscillation. The influence of disturbance can be eliminated.
　本発明の第２の態様のモールドレベル測定方法は、渦流式モールドレベル測定装置によって、モールド内の溶融金属のレベルを測定するものであって、コイルによって、モールドレベルの変化によるインピーダンス値の変化を検出するステップと、増幅部によって、該インピーダンス値の変化に対応する電圧を増幅するステップと、該モールド・オシレーション較正部によって、モールド・オシレーションの際の該測定装置の出力の最大値と最小値との差が、モールド・オシレーションの振幅の値を示すように該増幅部の正帰還率を較正するステップと、を含む。 The mold level measuring method according to the second aspect of the present invention is a method for measuring the level of molten metal in a mold by means of an eddy current mold level measuring device. A step of detecting, amplifying a voltage corresponding to the change in the impedance value by an amplifying unit, and a maximum value and a minimum value of the output of the measuring apparatus during mold oscillation by the mold oscillation calibration unit. Calibrating the positive feedback factor of the amplifier so that the difference from the value indicates the value of the amplitude of the mold oscillation.
　本態様のモールドレベル測定方法は、渦流式モールドレベル測定装置の出力の変化分、及びモールド・オシレーションの既知の振幅の値を使用して較正を行うので、高精度が達成される。また、渦流式モールドレベル測定装置自身の出力を使用して較正を行うので、較正に、熱電対式のモールドレベル計や電極式レベル計などの他のタイプのレベル計を必要としない。 In the mold level measuring method of this aspect, calibration is performed using the change in the output of the eddy current mold level measuring apparatus and the known amplitude value of the mold oscillation, so that high accuracy is achieved. In addition, since the calibration is performed using the output of the eddy current mold level measuring apparatus itself, other types of level meters such as a thermocouple type mold level meter and an electrode type level meter are not required for the calibration.
　本発明の第２の態様の第１の実施形態のモールドレベル測定方法においては、モールド・オシレーションの期間中に該測定装置の出力の最大値と最小値との差を逐次的に求め、該増幅部の正帰還率を逐次的に較正する。 In the mold level measuring method according to the first embodiment of the second aspect of the present invention, the difference between the maximum value and the minimum value of the output of the measuring device is sequentially obtained during the mold oscillation period, The positive feedback factor of the amplifier is calibrated sequentially.
　本実施形態のモールドレベル測定方法によれば、引き抜き期間を通して逐次的に較正を実施することができる。したがって、鋳造中におけるタンディッシュの上下降やスラブモールドにおける幅替えなどの動的外乱要因に十分に対応することができる。 According to the mold level measurement method of the present embodiment, calibration can be performed sequentially throughout the drawing period. Therefore, it is possible to sufficiently cope with dynamic disturbance factors such as tundish up / down during casting and width change in the slab mold.
連続鋳造設備の構成を示す図である。It is a figure which shows the structure of a continuous casting installation. 本発明の一実施形態による渦流式モールドレベル測定装置の構成を示す図である。It is a figure which shows the structure of the eddy current type mold level measuring apparatus by one Embodiment of this invention. 渦流式モールドレベル測定装置の較正方法を説明するための図である。It is a figure for demonstrating the calibration method of an eddy current type mold level measuring apparatus. モールドレベルと帰還増幅器の出力電圧との関係を示す図である。It is a figure which shows the relationship between a mold level and the output voltage of a feedback amplifier. モールドレベルとレベル計出力との関係を示す図である。It is a figure which shows the relationship between a mold level and a level meter output. 連続鋳造プロセスを説明するための図である。It is a figure for demonstrating a continuous casting process. モールド・オシレーション較正（ＭＯＳＣ）機能を説明するための流れ図である。5 is a flowchart for explaining a mold oscillation calibration (MOSC) function. 図７のステップＳ１０３０において正帰還率Ｋを定める方法を説明するための図である。It is a figure for demonstrating the method of determining the positive feedback factor K in step S1030 of FIG.
　図１は、連続鋳造設備の構成を示す図である。 FIG. 1 is a diagram showing a configuration of a continuous casting facility.
　タンディッシュ２１０内に蓄えられた溶鋼などの溶融金属は、浸漬ノズル２２０を介して、モールド３１０内に注入され、モールド３１０内で冷却されて凝固し、ピンチロール３３０によってモールド３１０から送り出される。また、モールド３１０には、モールド・オシレーションを生じさせるモールド・オシレーション装置３２０が設置されている。モールド・オシレーションについては後で説明する。 Molten metal such as molten steel stored in the tundish 210 is injected into the mold 310 through the immersion nozzle 220, cooled and solidified in the mold 310, and sent out from the mold 310 by the pinch roll 330. The mold 310 is provided with a mold oscillation device 320 that generates mold oscillation. Mold oscillation will be described later.
　一定時間において、モールド３１０へ注入される溶融金属の量がモールド３１０から送り出される金属の量よりも多い場合には、モールド３１０内の溶融金属の面のレベルが上昇し、一定時間において、モールド３１０から送り出される金属の量がモールド３１０へ注入される溶融金属の量がよりも多い場合には、モールド３１０内の溶融金属の面４００のレベルが下降する。本発明の実施形態による渦流式モールドレベル測定装置は、このような状況において、モールド内の溶融金属の面４００のレベルを測定する。本実施形態による渦流式モールドレベル測定装置は、検出部１０５と信号処理部１１０とを含む。検出部１０５と信号処理部１１０とは、ケーブル１０５５によって接続されている。検出部１０５は、溶融金属の近くに位置するので、検出部１０５に冷却用空気を送るために、ジョイント部１０５３及び空気配管１０５１が設置されている。 When the amount of molten metal injected into the mold 310 is larger than the amount of metal delivered from the mold 310 at a certain time, the level of the surface of the molten metal in the mold 310 increases, and at a certain time, the mold 310 When the amount of metal delivered from the mold 310 is greater than the amount of molten metal injected into the mold 310, the level of the molten metal surface 400 in the mold 310 decreases. In such a situation, the eddy current mold level measuring device according to the embodiment of the present invention measures the level of the surface 400 of the molten metal in the mold. The eddy current mold level measuring apparatus according to the present embodiment includes a detection unit 105 and a signal processing unit 110. The detection unit 105 and the signal processing unit 110 are connected by a cable 1055. Since the detection unit 105 is located near the molten metal, a joint unit 1053 and an air pipe 1051 are installed to send cooling air to the detection unit 105.
　図２は、本発明の一実施形態による渦流式モールドレベル測定装置１００の構成を示す図である。上述のように、渦流式モールドレベル測定装置１００は、検出部１０５と信号処理部１１０とを含む。検出部１０５は、駆動コイル１０５Ｃ１と、検出コイル１０５Ｃ２と、参照コイル１０５Ｃ３と、を含む。信号処理部１１０は、信号増幅部１２０と、出力生成部１３０と、モールド・オシレーション較正部１４０と、注湯前較正部１５０と、を含む。 FIG. 2 is a diagram showing a configuration of the eddy current mold level measuring apparatus 100 according to an embodiment of the present invention. As described above, the eddy current mold level measuring apparatus 100 includes the detection unit 105 and the signal processing unit 110. The detection unit 105 includes a drive coil 105C1, a detection coil 105C2, and a reference coil 105C3. The signal processing unit 110 includes a signal amplification unit 120, an output generation unit 130, a mold / oscillation calibration unit 140, and a pre-pouring calibration unit 150.
　検出部１０５において、駆動コイル１０５Ｃ１には一定周波数の電流が加えられ、駆動コイル１０５Ｃ１は交流磁界を発生する。この交流磁界は、検出コイル１０５Ｃ２、及び参照コイル１０５Ｃ３を通過する。また、この交流磁界が、駆動コイル１０５Ｃ１から所定の距離範囲内の溶融金属と交差すると、溶融金属に渦電流が発生し、その反作用として検出コイル１０５Ｃ２のインピーダンスが変化する。この検出コイル１０５Ｃ２のインピーダンスの変化は、検出コイル１０５Ｃ２と溶融金属面との間の距離に応じて変化する。したがって、この検出コイル１０５Ｃ２のインピーダンスの変化を測定することによって、検出コイル１０５Ｃ２と溶融金属面との間の距離を測定することができる。なお、検出コイル１０５Ｃ２のインピーダンスの変化の代わりに、検出コイル１０５Ｃ２のインピーダンスと参照コイル１０５Ｃ３のインピーダンスとの差の変化を使用することにより、温度及び周囲の電磁的環境による影響を小さくすることができる。本実施形態において、信号増幅部１２０は、検出コイル１０５Ｃ２のインピーダンスと参照コイル１０５Ｃ３のインピーダンスとの差を使用している。しかし、本発明は、本実施形態の差動式以外のいずれのタイプの渦流式モールドレベル測定装置にも適用することができる。 In the detection unit 105, a current having a constant frequency is applied to the drive coil 105C1, and the drive coil 105C1 generates an alternating magnetic field. This AC magnetic field passes through the detection coil 105C2 and the reference coil 105C3. When this AC magnetic field intersects with the molten metal within a predetermined distance range from the drive coil 105C1, an eddy current is generated in the molten metal, and the impedance of the detection coil 105C2 changes as a reaction. The change in impedance of the detection coil 105C2 changes according to the distance between the detection coil 105C2 and the molten metal surface. Therefore, the distance between the detection coil 105C2 and the molten metal surface can be measured by measuring the change in impedance of the detection coil 105C2. Note that, by using the change in the difference between the impedance of the detection coil 105C2 and the impedance of the reference coil 105C3 instead of the change in the impedance of the detection coil 105C2, the influence of the temperature and the surrounding electromagnetic environment can be reduced. . In the present embodiment, the signal amplification unit 120 uses a difference between the impedance of the detection coil 105C2 and the impedance of the reference coil 105C3. However, the present invention can be applied to any type of eddy current mold level measuring device other than the differential type of the present embodiment.
　信号増幅部１２０は、一定周波数、かつ一定振幅の交流電圧を生成する基準発振器１２０１と、帰還増幅器１２０３と、可変の正帰還率Ｋの帰還インピーダンス１２０５と、検出コイル１０５Ｃ２のインピーダンスと参照コイル１０５Ｃ３のインピーダンスとの差を入力とする差動増幅器１２０７と、帰還増幅器１２０３の出力の交流電圧を振幅変調する振幅変調器１２０９とを含む。基準発振器１２０１の出力電圧をＶｉｎ、帰還増幅器１２０３の出力電圧をＶｏｕｔ、帰還増幅器１２０３の増幅度をＧ１、差動増幅器１２０７の増幅度をＧ２、正帰還率をＫ、溶融金属のレベルをｈとすると、以下の式が成立する。
Figure JPOXMLDOC01-appb-M000001
 ここで、ｆは溶融金属のレベルｈの関数である。溶融金属のレベルｈが上昇して、検出コイル１０５Ｃ２と溶融金属面との間の距離が小さくなると、式（１）において、ｆ（ｈ）は大きくなる。したがって、溶融金属のレベルｈが上昇すると、式（１）にしたがって、帰還増幅器１２０３の出力電圧の絶対値｜Ｖｏｕｔ｜は小さくなる。 The signal amplifying unit 120 includes a reference oscillator 1201 that generates an AC voltage having a constant frequency and a constant amplitude, a feedback amplifier 1203, a feedback impedance 1205 having a variable positive feedback rate K, an impedance of the detection coil 105C2, and a reference coil 105C3. A differential amplifier 1207 that receives the difference from the impedance as an input, and an amplitude modulator 1209 that amplitude-modulates the AC voltage output from the feedback amplifier 1203 are included. The output voltage of the reference oscillator 1201 is V in , the output voltage of the feedback amplifier 1203 is V out , the amplification factor of the feedback amplifier 1203 is G1, the amplification factor of the differential amplifier 1207 is G2, the positive feedback factor is K, and the molten metal level is Assuming h, the following equation is established.
Figure JPOXMLDOC01-appb-M000001
 Here, f is a function of the level h of the molten metal. When the level h of the molten metal rises and the distance between the detection coil 105C2 and the molten metal surface decreases, f (h) increases in Equation (1). Therefore, when the level h of the molten metal increases, the absolute value | V out | of the output voltage of the feedback amplifier 1203 decreases according to the equation (1).
　つぎに、渦流式モールドレベル測定装置の較正（キャリブレーション）について説明する。上述のように、渦流式モールドレベル測定装置は、式（１）にしたがって、モールド３１０内の溶融金属面のレベルｈの変化による検出コイル１０５Ｃ２のインピーダンスの変化を検出する。しかし、検出コイル１０５Ｃ２のインピーダンスは、モールド３１０内の溶融金属面のレベルだけではなく、温度及び周囲の電磁的環境によっても変化する。したがって、渦流式モールドレベル測定装置による測定の際には、渦流式モールドレベル測定装置の較正が必要となる。 Next, calibration of the eddy current mold level measuring apparatus will be described. As described above, the eddy current mold level measuring device detects a change in impedance of the detection coil 105C2 due to a change in the level h of the molten metal surface in the mold 310 according to the equation (1). However, the impedance of the detection coil 105C2 varies depending not only on the level of the molten metal surface in the mold 310 but also on the temperature and the surrounding electromagnetic environment. Therefore, in the measurement by the eddy current mold level measuring device, the eddy current mold level measuring device needs to be calibrated.
　図３は、渦流式モールドレベル測定装置の較正方法を説明するための図である。渦流式モールドレベル測定装置の較正は、較正板による校正と、モールドへの注湯前の較正とを含む。 FIG. 3 is a diagram for explaining a calibration method of the eddy current mold level measuring apparatus. Calibration of the eddy current mold level measuring device includes calibration by a calibration plate and calibration before pouring the mold.
　較正板による較正は、連続鋳造プロセスから独立して実施される。較正板による較正においては、検出コイル１０５Ｃ２と金属製の較正板との距離を変化させながら、帰還増幅器１２０３の出力電圧を測定し記録する。図３の横軸は、溶融金属面または較正板のレベルを表す。レベルは、検出コイル１０５Ｃ２と溶融金属面または較正板との距離で示す。レベル０は、検出コイル１０５Ｃ２と溶融金属面または較正板との距離が０の状態である。図３の縦軸は、帰還増幅器１２０３の出力電圧を表す。図３の実線Ｒ１は、較正板による校正の結果を示す。図３において、渦流式モールドレベル測定装置の測定範囲は０から１５０ミリメータであるとして、検出コイル１０５Ｃ２と較正板との距離がこの範囲の値に対応する出力電圧が測定される。さらに、較正板を除去した場合、すなわち、検出コイル１０５Ｃ２と較正板との距離が無限大である場合の出力電圧Ｖ０１が測定される。この出力電圧Ｖ０１を基準電圧と呼称する。実線Ｒ１の形状を適切に定めるように、必要に応じて正帰還率Ｋを調整する。 Calibration with a calibration plate is performed independently of the continuous casting process. In calibration using the calibration plate, the output voltage of the feedback amplifier 1203 is measured and recorded while changing the distance between the detection coil 105C2 and the metal calibration plate. The horizontal axis in FIG. 3 represents the level of the molten metal surface or calibration plate. The level is indicated by the distance between the detection coil 105C2 and the molten metal surface or the calibration plate. Level 0 is a state in which the distance between the detection coil 105C2 and the molten metal surface or the calibration plate is zero. The vertical axis in FIG. 3 represents the output voltage of the feedback amplifier 1203. A solid line R1 in FIG. 3 indicates the result of calibration by the calibration plate. In FIG. 3, assuming that the measurement range of the eddy current mold level measuring apparatus is 0 to 150 millimeters, the output voltage corresponding to the distance between the detection coil 105C2 and the calibration plate within this range is measured. Furthermore, when removing the calibration plate, i.e., the output voltage V 01 where the distance between the calibration plate and the detection coil 105C2 is infinite is measured. This output voltage V 01 is referred to as a reference voltage. The positive feedback rate K is adjusted as necessary so as to appropriately determine the shape of the solid line R1.
　モールドへの注湯前の較正は、連続鋳造プロセスにおいて注湯前較正部１５０によって実施される。注湯前較正部１５０は、モールドへの注湯前に、帰還増幅器１２０３の出力電圧をリニアライザ１３０５で処理した値を記録する。注湯前の較正は、オペレータの指令によって行ってもよい。注湯前の状態は、検出コイル１０５Ｃ２と較正板との距離が無限大である状態に対応する。したがって、モールドへの注湯前に測定された帰還増幅器１２０３の出力電圧は、上述の基準電圧Ｖ０１と等しくなるはずである。しかし、実際には、温度及び周囲の電磁的環境が鋳造条件によって異なるので、測定された電圧は基準電圧Ｖ０１と等しくならない場合がある。図３において、一点鎖線Ａ１は、注湯前に測定された出力電圧ＶがＶ０１よりも大きい場合を示し、二点鎖線Ｂ１は、注湯前に測定された出力電圧ＶがＶ０１よりも小さい場合を示す。このような場合に、注湯前較正部１５０は、帰還増幅器１２０３の出力電圧Ｖが、基準電圧Ｖ０１に等しくなるように、式（１）の正帰還率Ｋを調整する。具体的に、一点鎖線Ａ１の場合には、レベル計出力のＶを小さくしてＶ０１と一致させるように正帰還率Ｋを大きくする。二点鎖線Ｂ１の場合には、レベル計出力Ｖを大きくしてＶ０１と一致させるように正帰還率Ｋを小さくする。モールドへの注湯前の較正は、鋳造ごとに行われる。 Calibration before pouring into the mold is performed by the pre-pouring calibration unit 150 in the continuous casting process. The pre-pouring calibration unit 150 records a value obtained by processing the output voltage of the feedback amplifier 1203 by the linearizer 1305 before pouring into the mold. Calibration before pouring may be performed according to an operator command. The state before pouring corresponds to the state where the distance between the detection coil 105C2 and the calibration plate is infinite. Therefore, the output voltage of the feedback amplifier 1203 measured before pouring into the mold should be equal to the reference voltage V 01 described above. However, in practice, the measured voltage may not be equal to the reference voltage V 01 because the temperature and surrounding electromagnetic environment vary with casting conditions. 3, one-dot chain line A1 shows a case where the output voltage V measured before pouring is greater than V 01, two-dot chain line B1, when the output voltage V measured before pouring is less than V 01 Indicates. In such a case, the pre-pouring calibration unit 150 adjusts the positive feedback rate K in Expression (1) so that the output voltage V of the feedback amplifier 1203 becomes equal to the reference voltage V 01 . Specifically, in the case of one-dot chain line A1 increases the positive feedback ratio K so as to match the V 01 to reduce the V level meter output. In the case of two-dot chain line B1 decreases the positive feedback ratio K so as to match the V 01 to increase the level meter output V. Calibration before pouring the mold is performed for each casting.
　図４は、モールドレベルと帰還増幅器１２０３の出力電圧との関係を示す図である。図３の横軸は、モールドレベルを表し、図４の縦軸は、帰還増幅器１２０３の出力電圧を表す。ここで、検出コイル１０５Ｃ２の位置をモールドレベル０としている。 FIG. 4 is a diagram showing the relationship between the mold level and the output voltage of the feedback amplifier 1203. 3 represents the mold level, and the vertical axis in FIG. 4 represents the output voltage of the feedback amplifier 1203. Here, the position of the detection coil 105C2 is set to a mold level 0.
　図２に示す出力生成部１３０は、後で説明する、モールド・オシレーションによる溶融金属面の変動の影響を除去するモールド・オシレーション・フィルタ（ＭＯＦ）１３０１と、アナログ・デジタル変換器１３０３と、リニアライザ１３０５と、を含む。リニアライザ１３０５は、レベル計出力の変化量とモールドレベルの変化量との比が一定値となるように線形化を行う。モールド・オシレーション・フィルタ１３０１を通過していない信号と、モールド・オシレーション・フィルタ１３０１を通過した信号と、の２種類の信号が、アナログ・デジタル変換器１３０３に入力され、該２種類の信号のアナログ・デジタル変換器１３０３の出力は、リニアライザ１３０５に入力される。該２種類の信号のリニアライザ１３０５の出力のうち、モールド・オシレーション・フィルタ１３０１を通過した信号に対応する出力は、渦流式モールドレベル測定装置の出力となる。該２種類の信号のリニアライザ１３０５の出力のうち、モールド・オシレーション・フィルタ１３０１を通過していない信号に対応する出力は、モールド・オシレーション較正部１４０によって使用される。モールド・オシレーション・フィルタ１３０１を含むモールド・オシレーション較正部１４０の機能については後で説明する。 The output generation unit 130 illustrated in FIG. 2 includes a mold oscillation filter (MOF) 1301 that removes the influence of the fluctuation of the molten metal surface due to mold oscillation, which will be described later, an analog-digital converter 1303, A linearizer 1305. The linearizer 1305 performs linearization so that the ratio between the change amount of the level meter output and the change amount of the mold level becomes a constant value. Two types of signals, a signal that has not passed through the mold oscillation filter 1301 and a signal that has passed through the mold oscillation filter 1301, are input to the analog-to-digital converter 1303. The output of the analog / digital converter 1303 is input to the linearizer 1305. Of the outputs of the linearizer 1305 for the two types of signals, the output corresponding to the signal that has passed through the mold oscillation filter 1301 is the output of the eddy current mold level measuring device. Of the outputs of the linearizer 1305 of the two types of signals, the output corresponding to the signal not passing through the mold oscillation filter 1301 is used by the mold oscillation calibration unit 140. The function of the mold oscillation calibration unit 140 including the mold oscillation filter 1301 will be described later.
　図５は、モールドレベルとレベル計出力との関係を示す図である。レベル計出力は、帰還増幅器１２０３の出力をリニアライザ１３０５によって線形化したものである。図５の横軸は、モールドレベルを表し、図５の縦軸は、渦流式モールドレベル測定装置の出力を表す。 FIG. 5 is a diagram showing the relationship between the mold level and the level meter output. The level meter output is obtained by linearizing the output of the feedback amplifier 1203 by the linearizer 1305. The horizontal axis in FIG. 5 represents the mold level, and the vertical axis in FIG. 5 represents the output of the eddy current mold level measuring apparatus.
　図６は、連続鋳造プロセスを説明するための図である。連続鋳造プロセスは、モールド３１０内の溶融金属面４００のが一定のレベルに上昇するまで、タンディッシュ２１０からモールド３１０へ溶融金属を供給する注湯段階と、タンディッシュ２１０からモールド３１０へ溶融金属を供給しながら、モールド３１０から凝固した金属の引き抜きを行う引き抜き段階と、を含む。注湯段階において、モールド３１０内には底部を形成するダミーバーが設置されており、溶融金属はモールド３１０及びダミーバーに囲まれた領域に凝固しながら蓄積され、溶融金属の表面、すなわちモールドレベルが上昇してゆく。モールドレベルが、所定の水準に達すると引き抜き段階へ移行する。引き抜きとは、モールド３１０内で凝固した、板状、棒状などの形状の金属を、モールド３１０の下部のピンチロール３３０によってモールドから外に出すことをいう。引き抜きの開始前に、溶融金属の表面の酸化を防止し、凝固した金属とモールドとの間の潤滑剤として機能するパウダーが溶融金属の表面に散布される。また、図１のモールド・オシレーション装置３２０によって、凝固した金属をモールド３１０から引き抜くために、モールド３１０を鉛直方向に振動させるモールド・オシレーション（ＭＯＳ）が開始される。モールド・オシレーションの振幅ストロークは、２ミリメータ乃至６ミリメータであり、モールド・オシレーションの周期は、毎分３０サイクル乃至４５０サイクルである。モールド・オシレーションの開始後に引き抜きが開始され、モールド・オシレーションは、引き抜きが行われている間は継続して行われる。 FIG. 6 is a diagram for explaining the continuous casting process. The continuous casting process includes a pouring stage for supplying molten metal from the tundish 210 to the mold 310 until the molten metal surface 400 in the mold 310 rises to a certain level, and the molten metal from the tundish 210 to the mold 310. And a drawing step of drawing the solidified metal from the mold 310 while supplying. In the pouring stage, a dummy bar forming the bottom is installed in the mold 310, and the molten metal is accumulated while solidifying in the area surrounded by the mold 310 and the dummy bar, and the surface of the molten metal, that is, the mold level is increased. I will do it. When the mold level reaches a predetermined level, the process proceeds to the drawing stage. Pulling out means that a metal having a shape such as a plate shape or a bar shape solidified in the mold 310 is taken out of the mold by the pinch roll 330 below the mold 310. Prior to the start of drawing, the surface of the molten metal is sprayed onto the surface of the molten metal, preventing oxidation of the surface of the molten metal and acting as a lubricant between the solidified metal and the mold. Further, mold oscillation (MOS) is started to vibrate the mold 310 in the vertical direction in order to draw the solidified metal from the mold 310 by the mold oscillation device 320 of FIG. The amplitude stroke of mold oscillation is 2 to 6 millimeters, and the period of mold oscillation is 30 to 450 cycles per minute. Drawing is started after the start of mold oscillation, and the mold oscillation is continuously performed while the drawing is performed.
　図６に示すように、モールド３１０への注湯開始前に、渦流式モールドレベル測定装置１００の、上述の注湯前の較正が行われる。注湯開始後にモールド３１０内の溶融金属のレベルが上昇する。溶融金属のレベルが渦流式モールドレベル測定装置１００の測定範囲に到達すると、渦流式モールドレベル測定装置１００によるモールドレベル測定が行われる。また、モールド・オシレーションの期間に以下に説明するモールド・オシレーション較正（ＭＯＳＣ）が行われる。 As shown in FIG. 6, before the pouring of the mold 310 is started, the above-described calibration before pouring of the vortex mold level measuring device 100 is performed. After the start of pouring, the level of molten metal in the mold 310 increases. When the level of the molten metal reaches the measurement range of the eddy current mold level measuring device 100, mold level measurement by the eddy current mold level measuring device 100 is performed. Further, mold oscillation calibration (MOSC) described below is performed during the mold oscillation period.
　出力生成部１３０は、図１のモールド・オシレーション装置３２０の、図１に図示しない制御装置から、モールド・オシレーション・サイクルに比例した信号を受け取る。出力生成部１３０は、この信号のサイクル値（周波数）に応じてモールド・オシレーション・フィルタ１３０１の阻止域を変化させる。モールド・オシレーション・フィルタ１３０は、信号増幅部１２０の出力からモールド・オシレーションの成分を除去することによって、レベル計出力におけるモールド・オシレーションによる溶融金属面の変動の影響を除去する。なお、モールド・オシレーション・フィルタ１３０１の代わりに、信号増幅部１２０の出力に、上述の制御装置から受け取ったモールド・オシレーションの逆位相の信号を加算する加算器を設け、信号増幅部１２０の出力にモールド・オシレーションの逆位相の信号を加算することによってモールド・オシレーションの成分を除去することによって、レベル計出力におけるモールド・オシレーションによる溶融金属面の変動の影響を除去するようにしてもよい。このように、本実施形態において使用されるモールド・オシレーション・サイクルに比例した信号の代わりに、他の実施形態においてモールド・オシレーションの逆位相の信号を使用することもできる。 The output generation unit 130 receives a signal proportional to the mold oscillation cycle from the control device (not shown in FIG. 1) of the mold oscillation device 320 in FIG. The output generation unit 130 changes the stop band of the mold oscillation filter 1301 according to the cycle value (frequency) of this signal. The mold oscillation filter 130 removes the influence of the fluctuation of the molten metal surface due to mold oscillation in the level meter output by removing the component of mold oscillation from the output of the signal amplification unit 120. Instead of the mold oscillation filter 1301, an adder that adds a signal of the opposite phase of the mold oscillation received from the above-described control device to the output of the signal amplification unit 120 is provided. By removing the component of the mold oscillation by adding the signal of the opposite phase of the mold oscillation to the output, the influence of the fluctuation of the molten metal surface due to the mold oscillation in the level meter output is removed. Also good. Thus, in place of the signal proportional to the mold oscillation cycle used in the present embodiment, a signal having a phase opposite to that of the mold oscillation can be used in another embodiment.
　図７は、渦流式モールドレベル測定装置１００のモールド・オシレーション較正部１４０によって実施される、モールド・オシレーション較正機能を説明するための流れ図である。 FIG. 7 is a flowchart for explaining the mold oscillation calibration function performed by the mold oscillation calibration unit 140 of the eddy current mold level measuring apparatus 100.
　図７のステップＳ１０１０において、モールド・オシレーション較正部１４０は、ＭＯＳＣを開始するか判断する。開始する場合には、ステップＳ１０２０に進む。開始しない場合には、待機する。モールド・オシレーション較正部１４０は、上述のモールド・オシレーション・サイクルに比例した信号、またはモールド・オシレーションの逆位相の信号によりＭＯＳＣを開始する時点を定める。定常状態における湯面（溶融金属の面）の変動周期は、０．１ヘルツ乃至０．５ヘルツである。したがって、モールド・オシレーション較正部１４０において、モールド・オシレーションの周期に対応した通過域を有するハイパスフィルタやバンドパスフィルタなどのフィルタを設け、モールド・オシレーションの成分を検出し、その大きさが所定値以上となったときにＭＯＳＣを開始するようにしてもよい。また、以下のステップにおいて、上記のフィルタの出力を使用してもよい。 7, in step S1010, the mold oscillation calibration unit 140 determines whether to start MOSC. If so, the process proceeds to step S1020. If not, wait. The mold oscillation calibration unit 140 determines a time point at which the MOSC is started by a signal proportional to the above-described mold oscillation cycle or a signal having a phase opposite to that of the mold oscillation. The fluctuation cycle of the molten metal surface (molten metal surface) in a steady state is 0.1 to 0.5 hertz. Therefore, the mold oscillation calibration unit 140 is provided with a filter such as a high-pass filter or a band-pass filter having a pass band corresponding to the mold oscillation period, detects the component of the mold oscillation, and the size thereof is You may make it start MOSC when it becomes more than predetermined value. In the following steps, the output of the above filter may be used.
　図７のステップＳ１０２０において、モールド・オシレーション較正部１４０は、信号増幅部１２０の出力の最大値及び最小値を取得し更新する。一例として、モールド・オシレーション較正部１４０は、モールド・オシレーションの周期以上の所定の期間を定め、更新時点から該所定の期間だけ先行する時点から該更新時点までの期間の最大値と最小値とを求めるようにしてもよい。このようにすれば、最大値及び最小値の少なくとも一方が変化した場合に、モールド・オシレーション較正部１４０は、その変化を把握しながら、逐次的に最大値及び最小値を測定することができる。 7, in step S1020, the mold oscillation calibration unit 140 acquires and updates the maximum value and the minimum value of the output of the signal amplification unit 120. As an example, the mold oscillation calibration unit 140 determines a predetermined period that is equal to or greater than the mold oscillation cycle, and the maximum value and the minimum value of the period from the time point that precedes the predetermined time period from the update time point to the update time point. May be requested. In this way, when at least one of the maximum value and the minimum value changes, the mold oscillation calibration unit 140 can sequentially measure the maximum value and the minimum value while grasping the change. .
　図７のステップＳ１０３０において、モールド・オシレーション較正部１４０は、信号増幅部１２０の出力の最大値と最小値との差を求め、その差が、モールド・オシレーションの既知の振幅ストロークの値を示すように、信号増幅部１２０の正帰還率Ｋを定める。モールド・オシレーションの振幅ストロークの値は、上述のように、２ミリメータ乃至６ミリメータの範囲であり、鋳造される対象によって異なる。したがって、モールド・オシレーション較正部１４０は、上述のモールド・オシレーション・サイクルに比例した信号、またはモールド・オシレーションの逆位相の信号を使用して振幅ストロークの値を定めてもよい。あるいは、振幅ストロークの値を、制御装置やオペレータなど外部から、鋳造ごとに受け取るようにしてもよい。 In step S1030 of FIG. 7, the mold oscillation calibration unit 140 obtains a difference between the maximum value and the minimum value of the output of the signal amplification unit 120, and the difference is a value of the known amplitude stroke of the mold oscillation. As shown, the positive feedback factor K of the signal amplifier 120 is determined. As described above, the value of the amplitude stroke of the mold oscillation is in the range of 2 to 6 millimeters and varies depending on the object to be cast. Therefore, the mold oscillation calibration unit 140 may determine the value of the amplitude stroke by using a signal proportional to the mold oscillation cycle described above or a signal having a phase opposite to that of the mold oscillation. Or you may make it receive the value of an amplitude stroke for every casting from the outside, such as a control apparatus and an operator.
　図８は、図７のステップＳ１０３０において正帰還率Ｋを定める方法を説明するための図である。振幅ストロークの既知の値をＳ０とする。図５に示したモールドレベルとレベル計出力との関係から、振幅ストロークの既知の値Ｓ０に対応するレベル計出力の差分ΔＶ０が求まる。図８の実線Ｒ２について、振幅ストロークの既知の値Ｓ０に対応するレベル計出力の差分ΔＶはΔＶ０に等しい。図８の一点鎖線Ａ２について、振幅ストロークの既知の値Ｓ０に対応するレベル計出力の差分ΔＶはΔＶ０よりも大きい。図８の二点鎖線Ｂ２について、振幅ストロークの既知の値Ｓ０に対応するレベル計出力の差分ΔＶはΔＶ０よりも小さい。一点鎖線Ａ２の場合には、レベル計出力の差分ΔＶを小さくしてΔＶ０と一致させるように正帰還率Ｋを大きくする。二点鎖線Ｂ２の場合には、レベル計出力の差分ΔＶを大きくしてΔＶ０と一致させるように正帰還率Ｋを小さくする。 FIG. 8 is a diagram for explaining a method of determining the positive feedback rate K in step S1030 of FIG. Let S 0 be the known value of the amplitude stroke. From the relationship between the mold level and the level meter output shown in FIG. 5, the level meter output difference ΔV 0 corresponding to the known value S 0 of the amplitude stroke is obtained. For the solid line R2 in FIG. 8, the level meter output difference ΔV corresponding to the known value S 0 of the amplitude stroke is equal to ΔV 0 . About one-dot chain line A2 in FIG 8, the difference [Delta] V of the level meter output corresponding to a known value S 0 of the amplitude stroke is greater than the [Delta] V 0. About two-dot chain line B2 in FIG. 8, the difference [Delta] V of the level meter output corresponding to a known value S 0 of the amplitude stroke is smaller than [Delta] V 0. In the case of one-dot chain line A2 is to reduce the difference [Delta] V of the level meter output to increase the positive feedback ratio K so as to coincide with the [Delta] V 0. In the case of two-dot chain line B2 is to increase the difference [Delta] V of the level meter output to reduce the positive feedback ratio K so as to coincide with the [Delta] V 0.
　図７のステップＳ１０４０において、モールド・オシレーション較正部１４０は、新たに定めた正帰還率Ｋを帰還インピーダンス１２０５へ設定する。 7, in step S1040, the mold oscillation calibration unit 140 sets the newly determined positive feedback rate K to the feedback impedance 1205.
　図７のステップＳ１０５０において、モールド・オシレーション較正部１４０は、ＭＯＳＣを終了するか判断する。モールド・オシレーション較正部１４０は、上述のモールド・オシレーション・サイクル信号によってＭＯＳＣを終了する時点を定める。終了する場合には、処理を終了する。終了しない場合には、ステップＳ１０２０に戻る。 In step S1050 of FIG. 7, the mold oscillation calibration unit 140 determines whether to end the MOSC. The mold oscillation calibration unit 140 determines a time point at which the MOSC is terminated by the above-described mold oscillation cycle signal. If the process is to be terminated, the process is terminated. If not finished, the process returns to step S1020.
　ＭＯＳＣにおいては、渦流式モールドレベル測定装置の出力の変化分、及びモールド・オシレーションの既知の振幅ストローク値を使用して較正を行うので、高精度が達成される。また、図６に示すように、ＭＯＳＣによれば、引き抜き期間を通して逐次的に較正を実施することができる。したがって、鋳造中におけるタンディッシュの上下降やスラブモールドにおける幅替えなどの動的外乱要因に十分に対応することができる。このように、ＭＯＳＣによって、十分に高い精度を有し、動的外乱要因へ対応することのできる渦流式モールドレベル測定装置を実現することができる。さらに、渦流式モールドレベル測定装置自身の出力を使用して較正を行うので、較正に、熱電対式のモールドレベル計や電極式レベル計などの他のタイプのレベル計を必要としない。 In MOSC, since the calibration is performed using the change in the output of the eddy current mold level measuring device and the known amplitude stroke value of the mold oscillation, high accuracy is achieved. Further, as shown in FIG. 6, according to the MOSC, calibration can be performed sequentially throughout the drawing period. Therefore, it is possible to sufficiently cope with dynamic disturbance factors such as tundish up / down during casting and width change in the slab mold. As described above, the MOSC can realize an eddy current mold level measuring apparatus having sufficiently high accuracy and capable of dealing with a dynamic disturbance factor. Further, since the calibration is performed using the output of the eddy current mold level measuring device itself, other types of level meters such as a thermocouple type mold level meter and an electrode type level meter are not required for the calibration.

Claims (7)

  1. 　モールド内の溶融金属のレベルを測定する渦流式モールドレベル測定装置であって、
    　モールドレベルの変化によるインピーダンス値の変化を検出するコイルを備えた検出部と、
    　該検出部の出力を増幅する増幅部と、
    　モールド・オシレーションの際の該測定装置の出力の最大値と最小値との差が、モールド・オシレーションの振幅の値を示すように該増幅部の正帰還率を較正するように構成されたモールド・オシレーション較正部と、を備えた渦流式モールドレベル測定装置。     An eddy current mold level measuring device for measuring the level of molten metal in a mold,
    A detector having a coil for detecting a change in impedance value due to a change in mold level;
    An amplification unit for amplifying the output of the detection unit;
    The difference between the maximum value and the minimum value of the measurement device output during mold oscillation is configured to calibrate the positive feedback factor of the amplifier so that the amplitude value of the mold oscillation is indicated. An eddy current mold level measuring device comprising a mold oscillation calibration unit.
  2. 　該モールド・オシレーション較正部は、モールド・オシレーションの期間中に該測定装置の出力の最大値と最小値との差を逐次的に求め、該増幅部の正帰還率を逐次的に較正するように構成された請求項１に記載の渦流式モールドレベル測定装置。 The mold oscillation calibration unit sequentially obtains the difference between the maximum value and the minimum value of the output of the measurement apparatus during the mold oscillation period, and sequentially calibrates the positive feedback rate of the amplification unit. The eddy current mold level measuring device according to claim 1 configured as described above.
  3. 　該モールド・オシレーション較正部は、モールド・オシレーション・サイクルを表す信号を外部から受け取り、該モールド・オシレーション・サイクルを表す信号にしたがって、モールド・オシレーションによる較正を行う期間を定めるように構成された請求項１または２に記載の渦流式モールドレベル測定装置。 The mold oscillation calibration unit is configured to receive a signal representing a mold oscillation cycle from the outside and determine a period for performing calibration by mold oscillation according to the signal representing the mold oscillation cycle. The eddy current mold level measuring device according to claim 1 or 2.
  4. 　該モールド・オシレーション較正部は、外部からの入力に基づいてモールド・オシレーションの振幅の値を定め、該振幅の値を使用して該増幅部の正帰還率を較正するように構成された請求項１から３のいずれかに記載の渦流式モールドレベル測定装置。 The mold oscillation calibration unit is configured to determine a mold oscillation amplitude value based on an external input, and to calibrate the positive feedback factor of the amplification unit using the amplitude value. The eddy current mold level measuring device according to any one of claims 1 to 3.
  5. 　モールド・オシレーションによる成分のみを検出するように設定されたフィルタをさらに備え、
    　該モールド・オシレーション較正部は、モールド・オシレーションの際の該測定装置の出力の最大値と最小値との差を求める際に、該フィルタを通した信号を使用するように構成された請求項１から４のいずれかに記載の渦流式モールドレベル測定装置。     It further comprises a filter set to detect only the component due to mold oscillation,
    The mold oscillation calibration unit is configured to use a signal that has passed through the filter when determining a difference between a maximum value and a minimum value of the output of the measurement apparatus during mold oscillation. Item 5. The eddy current mold level measuring device according to any one of Items 1 to 4.
  6. 　渦流式モールドレベル測定装置によって、モールド内の溶融金属のレベルを測定するモールドレベル測定方法であって、
    　コイルによって、モールドレベルの変化によるインピーダンス値の変化を検出するステップと、
    　増幅部によって、該インピーダンス値の変化に対応する電圧を増幅するステップと、
    　該モールド・オシレーション較正部によって、モールド・オシレーションの際の該測定装置の出力の最大値と最小値との差が、モールド・オシレーションの振幅の値を示すように該増幅部の正帰還率を較正するステップと、を含むモールドレベル測定方法。     A mold level measuring method for measuring the level of molten metal in a mold by an eddy current mold level measuring device,
    Detecting a change in impedance value due to a change in mold level by means of a coil;
    Amplifying a voltage corresponding to a change in the impedance value by an amplifying unit;
    The mold oscillation calibration unit causes the positive feedback of the amplification unit so that the difference between the maximum value and the minimum value of the output of the measuring apparatus during mold oscillation indicates the amplitude value of the mold oscillation. A mold level measuring method comprising: calibrating the rate.
  7. 　モールド・オシレーションの期間中に該測定装置の出力の最大値と最小値との差を逐次的に求め、該増幅部の正帰還率を逐次的に較正する、請求項６に記載のモールドレベル測定方法。 The mold level according to claim 6, wherein a difference between a maximum value and a minimum value of the output of the measuring device is sequentially obtained during a mold oscillation period, and a positive feedback rate of the amplification unit is sequentially calibrated. Measuring method.
PCT/JP2014/070340 2014-08-01 2014-08-01 Eddy current-type mold level measurement device and mold level measurement method WO2016017028A1 (en)

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PCT/JP2014/070340 WO2016017028A1 (en) 2014-08-01 2014-08-01 Eddy current-type mold level measurement device and mold level measurement method
JP2015024950A JP5782202B1 (en) 2014-08-01 2015-02-12 Eddy current mold level measuring apparatus and mold level measuring method
EP15176759.7A EP2980538B1 (en) 2014-08-01 2015-07-15 Molten metal level measuring method by eddy current and related measuring device
US14/809,582 US9816851B2 (en) 2014-08-01 2015-07-27 Eddy current mold level measuring device and mold level measuring method
TW104124326A TW201606270A (en) 2014-08-01 2015-07-28 Eddy current mold level measuring device and mold level measuring method
CN201510459980.6A CN105312510B (en) 2014-08-01 2015-07-30 Eddy current type mould level measurement device and mould level assay method
KR1020150108511A KR102242430B1 (en) 2014-08-01 2015-07-31 Vortex type mold level measuring instrument and method

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60216959A (en) * 1984-04-13 1985-10-30 Nippon Steel Corp Detection of level of continuous casting mold
JPS63111248U (en) * 1987-01-13 1988-07-16
JP2007021529A (en) * 2005-07-15 2007-02-01 Jfe Steel Kk Multi-frequency vortex type thickness measuring method for molten mold powder
JP5463440B1 (en) * 2013-06-18 2014-04-09 品川リフラクトリーズ株式会社 Calibration method and calibration jig for mold level gauge in mold

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60216959A (en) * 1984-04-13 1985-10-30 Nippon Steel Corp Detection of level of continuous casting mold
JPS63111248U (en) * 1987-01-13 1988-07-16
JP2007021529A (en) * 2005-07-15 2007-02-01 Jfe Steel Kk Multi-frequency vortex type thickness measuring method for molten mold powder
JP5463440B1 (en) * 2013-06-18 2014-04-09 品川リフラクトリーズ株式会社 Calibration method and calibration jig for mold level gauge in mold

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