JP2011183445A - Method for measuring the surface temperature of slab and slab surface temperature measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the surface temperature of a slab in a continuous casting machine without receiving the restriction in the setting place of a measuring apparatus. <P>SOLUTION: An electromagnetic wave in a millimeter wave region radiated from a slab 7 in a continuous casting machine is received by a horn antenna 102, and the surface temperature of the slab 7 is measured using the electromagnetic wave in a millimeter wave region received by the horn antenna 102. By this constitution, a measuring apparatus can be miniaturized, thus the surface temperature of the slab 7 in the continuous casting machine can be measured without receiving the restriction in the setting place of the measuring apparatus. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a slab surface temperature measuring method and a slab surface temperature measuring device for measuring the surface temperature of a slab in a continuous casting machine.

  In the continuous casting process, the cooling water sprayed from the spray nozzles provided in the gaps between the rolls forming the support roll group by continuously drawing out the slab in which the solidified shell is formed by the primary cooling in the mold. This is one of slab manufacturing methods for manufacturing slabs such as slabs, blooms, billets, etc. by performing secondary cooling according to the method and completely solidifying the interior. The primary cooling and secondary cooling in the continuous casting are extremely important from the viewpoint of stable production of the slab and maintenance of quality. If the primary cooling is insufficient, a solidified layer on the surface may remelt after exiting the mold, and a breakout may occur in which the unsolidified molten steel inside leaks. In addition, when uniform cooling is not achieved in primary and secondary cooling, there are cases where cracks due to temperature unevenness on the slab surface, cracks during bending and straightening, etc. are induced. Furthermore, when secondary cooling is insufficient during high-speed casting, unsolidified molten steel may leak from the center when the slab is cut by a cutting machine at the end of the continuous casting machine.

  For this reason, it is possible to predict the solidification process of the slab in the continuous casting machine using a heat transfer model, or to grasp the solidification state inside the slab using an ultrasonic sensor located near the end of the continuous casting machine. There is. However, when the solidification state inside the slab is predicted using the heat transfer model, it is necessary to always measure the temperature of the slab in the mold in order to accurately predict the solidification state inside the slab. On the other hand, when measuring the solidification state inside the slab using an ultrasonic sensor at the end of the machine, it is only possible to know the solidification state inside the slab near the end of the continuous casting machine. Only the subsequent casting is effective, and it can hardly be reflected in the slab currently in the machine, and the conditions cannot be changed quickly.

  Therefore, in recent years, inventions have been proposed for measuring the surface temperature of a slab in a continuous casting machine between the mold and the end of the continuous casting machine (see Patent Documents 1, 2, and 3). Specifically, the invention described in Patent Document 1 measures the surface temperature of a slab in a continuous casting machine using an infrared radiation thermometer. The invention described in Patent Document 2 measures the surface temperature of a slab in a continuous casting machine using an eddy current sensor. The invention described in Patent Document 3 measures the surface temperature of a slab in a continuous casting machine using microwaves radiated from the slab. According to such an invention, it is possible to improve the prediction accuracy of the solidified state inside the slab using the heat transfer model by measuring the surface temperature of the slab. In addition, since the surface temperature of the slab is measured at a location closer to the mold and the solidification state inside the slab can be estimated based on the measurement result, it is possible to perform secondary cooling control promptly based on the estimated solidification state.

JP 2009-195959 A JP 2008-256605 A JP-A-62-269029

  However, the inventions described in Patent Documents 1 to 3 have the following problems.

  The invention described in Patent Document 1 measures the surface temperature of a slab in a continuous casting machine using an infrared radiation thermometer. However, the measurement accuracy of infrared radiation thermometers varies greatly depending on the presence of water vapor and water. In general, a large amount of high-temperature steam is present in a continuous casting machine. For this reason, in invention of patent document 1, when measuring the surface temperature of a slab, in order to improve the measurement accuracy of an infrared radiation thermometer, spraying of the cooling water on the slab surface is temporarily interrupted, The surface temperature of the slab is measured from an environment where water vapor is not generated. However, if spraying of cooling water is temporarily interrupted, the slab will not be cooled, so breakout may occur due to reheating or remelting in places where the solidified layer of the slab is thin. is there. For this reason, the installation place of the infrared radiation thermometer is limited to the place where the solidified layer of the slab becomes sufficiently thick.

  The invention described in Patent Document 2 measures the surface temperature of a slab in a continuous casting machine using an eddy current sensor. Unlike the infrared radiation thermometer, the measurement accuracy of the eddy current sensor is not easily affected by water or water vapor. However, in order to improve the measurement accuracy of the eddy current sensor, it is necessary to enlarge the electromagnetic coil that constitutes the eddy current sensor, so that the installation place is limited as in the case of the infrared radiation thermometer. On the other hand, when the eddy current sensor is configured using a small electromagnetic coil, it is necessary to shorten the distance between the eddy current sensor and the slab in order to improve the measurement accuracy of the eddy current sensor. Is a problem. Moreover, when a slab and an eddy current sensor contact, an eddy current sensor may break down.

  The invention described in Patent Document 3 measures the surface temperature of a slab in a continuous casting machine using microwaves radiated from the slab. Since the wavelength of the microwave is as long as 1 to 10 cm, the measurement accuracy is not easily affected by water or water vapor, like the eddy current sensor. However, the intensity of the microwave radiated from the slab is very weak. For this reason, when measuring the surface temperature of the slab using microwaves, an antenna for focusing the microwave radiated from the slab is required, so the configuration of the measuring device becomes large, As with infrared radiation thermometers and eddy current sensors, installation locations are limited.

  As described above, according to the inventions described in Patent Documents 1 to 3, since the installation location of the measuring device is limited, the surface temperature at an arbitrary position of the slab is measured, and the slab is solidified based on the measurement result. It was difficult to optimally control the state. Optimum control of the solidification state of the slab is important in improving the quality and production efficiency of the slab. For this reason, provision of the slab surface temperature measuring method and slab surface temperature measuring apparatus which can measure the surface temperature of the slab in a continuous casting machine without being restrict | limited to the installation place of a measuring device is desired.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the object thereof is a slab surface temperature measuring method capable of measuring the slab surface temperature in a continuous casting machine without being restricted by the installation location of the measuring device. And providing a slab surface temperature measuring device.

  In order to solve the above-mentioned problems and achieve the object, a slab surface temperature measuring method according to the present invention includes a reception step for receiving electromagnetic waves in the millimeter wave region radiated from a slab in a continuous casting machine, and a reception step. Measuring the surface temperature of the slab using the received electromagnetic wave in the millimeter wave region.

  In order to solve the above problems and achieve the object, a slab surface temperature measuring device according to the present invention receives electromagnetic waves from a contact point or a contact point between a roll and a slab that conveys a slab in a continuous casting machine. A receiving unit that receives an electromagnetic wave in the millimeter wave region radiated in a radio wave path to the antenna, and an arithmetic unit that calculates the surface temperature of the slab using the electromagnetic wave in the millimeter wave region received by the receiving unit.

  According to the slab surface temperature measuring method and the slab surface temperature measuring device according to the present invention, the measuring device can be miniaturized, so that the slab surface in the continuous casting machine can be reduced without being restricted by the installation location of the measuring device. The surface temperature can be measured.

FIG. 1 is a schematic diagram showing a schematic configuration of a continuous casting machine according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a surface temperature measuring apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram showing the arrangement position of the horn antenna shown in FIG. FIG. 4 is a schematic diagram showing how the horn antenna receives an electromagnetic wave radiated from a contact point between two metal plates. FIG. 5 is a diagram showing the measurement results of the surface temperature of the slab using the present invention and a thermocouple. FIG. 6 is a schematic diagram showing a modification of the arrangement position of the horn antenna. FIG. 7 is a schematic diagram for explaining the positional relationship between the contact point between the roll and the cast piece, the horn antenna, and the reflecting mirror. FIG. 8 is a block diagram showing a configuration of a control device that controls the operation of the continuous casting machine shown in FIG. 1. FIG. 9 is a schematic diagram showing a configuration of a modification of the surface temperature measuring apparatus shown in FIG.

  Hereinafter, the configuration of a continuous casting machine according to an embodiment of the present invention will be described with reference to the drawings.

[Schematic configuration of continuous casting machine]
First, a schematic configuration of a continuous image casting machine according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic diagram showing a schematic configuration of a continuous casting machine according to an embodiment of the present invention. As shown in FIG. 1, a continuous casting machine 1 according to an embodiment of the present invention is poured from a tundish 3 through which a molten steel 2 is poured from a ladle (not shown) and an immersion nozzle 4. Slab support that cools the molten steel 2 that is semi-solidified while shaping the solidified shell 5 on the surface until it grows into dendrites, and the semi-solid slab 7 that is drawn from the mold 6 vertically downward. A slab support roll 8b for cooling and transporting the slab 7 drawn by the slab support roll 8a, and a slab support roll for cooling and transporting the slab 7 transported by the slab support roll 8b in the horizontal direction. 8c and a gas cutter 9 for cutting the slab 7 conveyed by the slab support roll 8c into a predetermined length. The slab 7 cut | disconnected by the gas cutting machine 9 is sent to subsequent processes, such as a rolling process, sequentially.

  A sliding nozzle 10 is provided between the tundish 3 and the immersion nozzle 4. The sliding nozzle 10 adjusts the amount of molten steel 2 poured per unit time from the immersion nozzle 4 to the mold 6.

[Configuration of surface temperature measuring device]
With reference to FIG. 2 and FIG. 3, the structure of the surface temperature measuring apparatus 100 which is one Embodiment of this invention is demonstrated. FIG. 2 is a block diagram showing a configuration of the surface temperature measuring apparatus 100 according to the embodiment of the present invention. FIG. 3 is a schematic diagram showing an arrangement position of the horn antenna 102 shown in FIG.

  As shown in FIG. 2, the surface temperature measuring apparatus 100 includes a horn antenna 102, a waveguide 103, a suction port 104, a converter 105, an amplifier circuit (AMP) 106, an isolator 107, an amplifier circuit (AMP) 108, and a divider 109. , 94 GHz oscillator 110, hybrid divider 111, mixer 112, mixer 113, and calculation unit 114.

  As shown in FIG. 3, the horn antenna 102 is disposed between the roll 12a and the roll 12b constituting the slab support roll so that the receiving surface faces the contact point P between the slab roll 12a and the slab 7. Has been. The horn antenna 102 feeds the millimeter wave received on the receiving surface to the waveguide 103. In this embodiment, the millimeter wave means an electromagnetic wave having a wavelength of about 1 to 10 mm.

  Here, the reason why the receiving surface of the horn antenna 102 is directed to the contact point P between the roll 12a and the cast piece 7 will be described with reference to FIG. FIG. 4 is a schematic diagram showing how the horn antenna 102 receives the electromagnetic wave L radiated from the contact point A between the two metal plates AB and the metal plate AC.

  The (emissivity, reflectance, temperature) of the metal plate AB and the metal plate AC are (ε1, r1, T1) and (ε2, r2, T2), respectively, and the electromagnetic wave L radiated from the contact point A is the metal plates AB and Assuming that the metal plate AC is reflected n times and m times, respectively, when the temperature T1 of the metal plate AB is equal to the temperature T2 of the metal plate AC, the energy E of the electromagnetic wave L received by the horn antenna 102 is expressed by the following formula (1 ).

  Here, the parameter Eb (T1) in Equation (1) indicates the black body radiant energy at the temperature T1. Further, the parameter ε1 * and the parameter ε2 * indicate integration values of a plurality of reflections and radiations, respectively, and are expressed by the following formulas (2) and (3). Please refer to the reference (ISIJ, '83 -S1223, P.169) for details of these formulas.

  The frequency and wavelength of the electromagnetic wave L are 100 GHz and 3.3 mm, respectively, and the iron is not formed with an oxide film on the surface of the metal plate AB and the metal plate AC (emissivity: ε1 = ε2 = 0.01, reflectivity: r1 = r2 = 0.99), when the horn antenna 102 receives the electromagnetic wave L radiated from the contact point A between the two metal plates AB and AC, the sum of the parameters ε1 * and ε2 * (ε1 *) The value of + ε2 *) is about 0.065. On the other hand, when only the radiation component radiated from the metal plate AC without considering the reflection component is received by making the horn antenna 102 face the metal plate AC, the values of the parameters r1 and r2 are set to 0. The sum of the parameter ε1 * and the parameter ε2 * (ε1 * + ε2 *) is about 0.01.

  Therefore, when the horn antenna 102 receives the electromagnetic wave L radiated from the contact point A between the two metal plates AB and AC, the energy E of the electromagnetic wave L received by the horn antenna 102 It can be seen that when facing the metal plate AC, the energy E of the electromagnetic wave L received by the horn antenna 102 is about 6.5 times. In general, since the metal surface has a high reflectance, the intensity of the millimeter wave emitted from the metal surface is low. Therefore, by directing the receiving surface of the horn antenna 102 toward the contact point P between the roll 12a and the cast piece 7, the amount of millimeter wave energy received by the horn antenna 102 can be increased, and millimeter waves can be received with high sensitivity. .

  When the contact point P between the roll 12a and the slab 7 is actually observed from the line direction, the reddish color of the slab 7 can be confirmed, but light from the outside may appear to be reflected like specular reflection. When the temperature is low, the vicinity of the contact point P is dark due to the shadow. This means that the reflection component reaching the observation direction is low. Therefore, when the receiving surface of the horn antenna 102 is arranged toward the contact point P between the roll 12a and the cast piece 7, the amount of reflection received by the horn antenna 102 becomes small, and the amount of radiation received by the horn antenna 102 becomes small. Apparently bigger. Thereby, the surface temperature of the slab 7 can be measured only by the electromagnetic wave receiving system.

  The waveguide 103 is made of a hollow metal member and is connected to the horn antenna 102. The waveguide 103 guides the millimeter wave signal received by the horn antenna 102. The suction port 104 is provided at the end of the waveguide 103 and reduces the water vapor in the waveguide 103 by passing cooling air from the waveguide 103 to the horn antenna 102. The coaxial converter 105 converts the millimeter wave signal guided by the waveguide 103 into the coaxial mode, and then transmits the millimeter wave signal to the coaxial cable.

  Since the horn antenna 102 and the waveguide 103 are metal workpieces, even if the horn antenna 102 and the waveguide 103 are in contact with the slab 7 or deteriorated by heat from the slab 7, Only the exchange with 103 is sufficient. Further, since the millimeter wave signal received by the horn antenna 102 is guided to the coaxial converter 105 via the waveguide 103, the horn antenna 102 and the coaxial converter 105 are spaced apart and immediately above the cast piece 7. The horn antenna 102 and the waveguide 103 can be simply arranged. However, if the distance between the horn antenna 102 and the coaxial converter 105 is long, it causes a detection error. Therefore, the length of the waveguide 103 is preferably as short as possible.

  The amplifier circuit 106 amplifies the millimeter wave signal transmitted by the coaxial converter 105. The isolator 107 removes the reflected wave signal generated by the coaxial converter 105 and the reverse signal mixed from the outside from the millimeter wave signal amplified by the amplifier circuit 106. The amplifier circuit 108 amplifies the millimeter wave signal output from the isolator 107. The divider 109 separates the millimeter wave signal amplified by the amplifier circuit 108 into an in-phase component signal and a quadrature component signal, and inputs the separated in-phase component signal and quadrature component signal to the mixer 112 and the mixer 113, respectively.

  The oscillator 110 oscillates using a millimeter wave having a frequency of 94 GHz as a reference carrier wave. The hybrid divider 111 applies phase changes of 0 ° and 90 ° to the reference signal oscillated by the oscillator 110, and inputs the reference signals to which the phase changes of 0 ° and 90 ° are applied to the mixer 112 and the mixer 113, respectively. The mixer 112 generates an in-phase component signal by mixing the in-phase component signal input from the divider 109 and the reference signal input from the hybrid divider 111.

  The mixer 113 generates a quadrature component signal by mixing the quadrature component signal input from the divider 109 and the reference signal input from the hybrid divider 111. The computing unit 114 computes the sum of squares of the in-phase component signal and the quadrature component signal input from the mixer 112 and the mixer 113, and uses the square root of the computed sum of squares as information on the surface temperature of the slab 7. To enter. Note that the information processing apparatus 200 may calculate the sum of squares of the in-phase component signal and the quadrature component signal input from the mixer 112 and the mixer 113 without providing the calculation unit 114 in the surface temperature measurement apparatus 100.

  As is clear from the above description, according to the continuous casting machine 1 which is an embodiment of the present invention, the surface temperature measuring device 100 is an electromagnetic wave in the millimeter wave region radiated from the slab 7 in the continuous casting machine 1. The surface temperature of the slab 7 is measured using the received electromagnetic wave in the millimeter wave region. According to such a configuration, since the surface temperature measuring device 100 can be downsized, the surface temperature of the slab 7 in the continuous casting machine 1 can be measured without being restricted by the installation location of the measuring device.

  The millimeter wave has higher directivity than the microwave. In general, even if an antenna having excellent focusing properties is used, the spread of the focal point does not become less than the wavelength. Therefore, when the measurement point of the surface temperature is narrow, it is desirable to use an antenna with higher directivity. Therefore, by measuring the surface temperature of the slab 7 using an electromagnetic wave in the millimeter wave region having a shorter wavelength than that of the microwave, an antenna having high directivity is used even when the measurement point of the surface temperature is narrow. Thus, the surface temperature of the slab 7 can be measured.

  According to the continuous casting machine 1 which is one embodiment of the present invention, the surface temperature measuring device 100 includes a horn arranged so that the receiving surface faces the contact point P between the roll 12a carrying the cast piece 7 and the cast piece 7. Since the electromagnetic wave in the millimeter wave region is received using the antenna 102, the electromagnetic wave in the millimeter wave region can be received with high sensitivity, and the surface temperature of the slab 7 can be accurately measured. Here, the measurement result of the surface temperature of the slab 7 is shown in FIG. The solid line and the broken line shown in FIG. 5 show the measurement results of the surface temperature of the slab using the present invention and the thermocouple, respectively. As shown in FIG. 5, according to the present invention, it is understood that the surface temperature of the slab 7 can be measured with an error of about 10 ° C. with respect to the measurement result by the thermocouple.

  In addition, as shown in FIG. 5, the surface temperature measured increases / decreases according to time. Therefore, when there is a possibility that the measurement error of the surface temperature may increase depending on the surface state and the surrounding environment, the surface temperature measuring device 100 increases the measurement time of the surface temperature of the slab 7 and the surface temperature within the measurement time. May be calculated as the surface temperature of the slab 7.

  In this embodiment, the receiving surface of the horn antenna 102 is arranged so as to face the contact point P between the slab roll 12a and the slab 7, but as shown in FIG. A reflecting mirror 101 for focusing on the horn antenna 102 may be provided. In this case, as shown in FIG. 7, the reflecting mirror 101 has a part of an elliptical surface R in which the contact point between the roll 12a and the slab 7 and the arrangement position of the horn antenna 102 are the focal position A and the focal position B, respectively. It has as a reflective surface. In addition, the actual measured temperature is the average value of the roll and slab, but the correction may be offset correction or linear correction. It is also possible to obtain the slab surface temperature from the model with high accuracy.

  The size of the focusing device increases as the wavelength of the electromagnetic wave to be focused increases. Therefore, when focusing the millimeter wave, the focusing device can be downsized, and the focusing device can be installed in a narrow place such as between rolls. Note that the focusing device that focuses the millimeter wave radiated from the slab 7 toward the horn antenna 102 is not limited to the reflecting mirror 101. In consideration of interference with the installation space and surrounding structure, the parabolic antenna and the electromagnetic wave Other focusing devices such as lenses may be used. However, it is desirable to keep the temperature of the focusing device at 100 ° C. or higher in order to prevent adhesion of water droplets or the like.

[Configuration of control device]
With reference to FIG. 8, the structure of the control apparatus which controls operation | movement of the continuous casting machine 1 is demonstrated.

  FIG. 8 is a block diagram illustrating a configuration of a control device that controls the operation of the continuous casting machine 1. As shown in FIG. 8, the control device includes a surface temperature measurement device 100 and an information processing device 200. The surface temperature measuring device 100 measures information related to the surface temperature of the slab 7 and inputs the measured information to the information processing device 200. In this embodiment, the surface temperature measuring device 100 is arranged near the slab support roll 8a or the slab support roll 8b, and is cooled by the slab support roll 8a or the slab support roll 8b. Measure information about. The surface temperature measuring device 100 functions as a receiving unit and a calculating unit according to the present invention.

  The information processing device 200 is configured by an arithmetic processing device such as a microcomputer, and includes a solidified layer thickness calculation unit 201. The solidified layer thickness calculation unit 201 calculates the thickness of the solidified layer of the slab 7 using information regarding the surface temperature of the slab 7 input from the surface temperature measuring device 100. The information processing apparatus 200 controls the operation of the continuous casting machine 1 based on the thickness of the solidified layer measured by the solidified layer thickness calculation unit 201. Specifically, the information processing apparatus 200 outputs a flow control command and a cooling control command based on the thickness of the solidified layer measured by the solidified layer thickness calculation unit 201, so that the submerged nozzle 4 sends it to the mold 6. The amount of molten steel 2 to be poured and the cooling temperature of the slab 7 are feedback-controlled. Further, the information processing apparatus 200 predicts the crack of the solidified layer and the solidification completion point of the slab 7 based on the thickness of the solidified layer measured by the solidified layer thickness calculation unit 201, and the slab according to the predicted result. The feed-out control of the drawing speed of 7 and the temperature of the cooling water is performed.

  Although the embodiment to which the invention made by the present inventor is applied has been described above, the present invention is not limited by the description and the drawings that form a part of the disclosure of the present invention according to this embodiment. For example, in this embodiment, as shown in FIG. 9, a plurality of horn antennas 102 may be arranged in the width direction of the slab 7, and the surface temperatures at a plurality of points in the width direction of the slab 7 may be measured. In this embodiment, detection is performed at a frequency of 94 GHz. However, detection is performed at a frequency of 94 ± 0.1 GHz to generate an in-phase component signal and a quadrature component signal having an intermediate frequency of 100 MHz, and then detected at a frequency of 100 MHz. You may do it. As described above, other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Molten steel 3 Tundish 4 Immersion nozzle 5 Solidification shell 6 Mold 7 Cast slab 8a, 8b, 8c Slab support roll 9 Gas cutting machine 100 Surface temperature measuring device 101 Reflector 102 Horn antenna 103 Waveguide 104 Suction Mouth 105 Converter 106, 108 Amplifier circuit (AMP)
107 Isolator 109 Divider 110 94 GHz Oscillator 111 Hybrid Divider 112, 113 Mixer 114 Arithmetic Unit 200 Information Processing Device

Claims (5)

A receiving step of receiving electromagnetic waves in the millimeter wave region radiated from the slab in the continuous casting machine;
Measuring the surface temperature of the slab using electromagnetic waves in the millimeter wave region received by the receiving step;
A slab surface temperature measuring method comprising:   2. The slab surface temperature according to claim 1, wherein the receiving surface receives an electromagnetic wave in the millimeter wave region using an antenna disposed toward a contact point between the slab and a roll that transports the slab. Measurement method.   The slab surface temperature measuring method according to claim 2, wherein the antenna includes a focusing mechanism that focuses and receives the electromagnetic wave in the millimeter wave region.   The casting according to claim 1 or 2, wherein a plurality of the antennas are arranged in a width direction of the slab, and surface temperatures at a plurality of points in the width direction of the slab are measured using the plurality of antennas. Single surface temperature measurement method. A receiving unit for receiving electromagnetic waves in the millimeter wave region radiated in a radio wave path from a contact point between a roll and a slab that conveys a slab in a continuous casting machine to an antenna that receives electromagnetic waves;
A slab surface temperature measuring device comprising: an arithmetic unit that calculates a surface temperature of the slab using an electromagnetic wave in a millimeter wave region received by the receiving unit.

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