JP2011053047A - Surface temperature measuring method, surface temperature measuring apparatus, and steel manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface temperature measuring method which can perform temperature measurement with high precision even in a low-temperature range in which a material for temperature measurement is under water cooling and its surface temperature is about 200°C. <P>SOLUTION: The method for measuring the surface temperature of a material for temperature measurement detects thermal radiation emitted from the surface of the material for temperature measurement M under water cooling by a radiation thermometer 1 arranged facing the surface of the material for temperature measurement. The wavelength of the thermal radiation detected by the radiation thermometer is set to be 1.60 to 1.80 μm. Air is injected from the radiation thermometer toward the surface of the material for temperature measurement, thereby forming an air column in between the surface of the material for temperature measurement and the radiation thermometer. The thermal radiation emitted from the surface of the material for temperature measurement is detected by the radiation thermometer through the air column. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method and apparatus for measuring the surface temperature of a temperature-measured material such as a steel material by radiation temperature measurement, and a method for manufacturing a steel material having a step of measuring the surface temperature by this method. In particular, the present invention measures the surface temperature by using this method and a surface temperature measuring method and apparatus capable of measuring the temperature accurately even if the temperature of the material to be measured is water-cooled and the surface temperature is about 200 ° C. The present invention relates to a method for manufacturing a steel material having a process.

  In order to improve the quality and productivity of steel, temperature management of the steel in the cooling process is important. When measuring the surface temperature of a steel material being transported using a radiation thermometer in a cooling process such as a hot rolling line or a heat treatment / cooling line for steel, steam between the steel to be measured and the radiation thermometer. The cooling water is scattered, or the surface of the steel material to be measured is covered with a water film or submerged. Under such circumstances, the thermal radiation emitted from the temperature-measured steel material may be absorbed or scattered by water vapor, steam, cooling water, etc., resulting in an error in the temperature measurement value or inability to measure. It may occur.

  Therefore, in order to reduce temperature measurement errors caused by the above factors and enable accurate radiation temperature measurement, a radiation thermometer has been conventionally used by ejecting purge water from a nozzle toward the steel surface. Various methods have been proposed for measuring the surface temperature of a steel material by forming a water column between the surface of the steel material and detecting the radiant energy radiated from the steel material through the water column.

  More specifically, for example, a water column is formed between the measurement object and a radiation thermometer that measures the surface temperature of the measurement object based on the radiant energy radiated from the measurement object, In the temperature measurement method of measuring the surface temperature of the object to be measured using the radiation thermometer while correcting the amount of radiant energy absorbed by the water column among the radiant energy radiated from the object to be measured, the water column In forming the temperature, a temperature measuring method is proposed in which the temperature of the water column is set to 60 ° C. or higher (see, for example, Patent Document 1).

  According to the method described in Patent Document 1, since a water column is formed between the radiation thermometer and the object to be measured, it is difficult for water vapor or scattered water to enter the portion where the water column is formed. It is possible to reduce temperature measurement errors due to absorption and scattering of radiant energy by water. Furthermore, the method described in Patent Document 1 has a configuration in which the temperature of the water column is set to 60 ° C. or higher, and a boiling film is easily formed on the surface of the object to be measured which is in contact with the water column. For this reason, it has the advantage that the surface temperature fall of a to-be-measured object is suppressed, and the cooling nonuniformity of a to-be-measured object can also be reduced, without impairing the representativeness of a measured temperature value.

  However, the method described in Patent Document 1 requires a heating device for raising the temperature of the water column to 60 ° C. or higher, and there is a problem that it takes energy cost to raise the temperature of water. In addition, since a thickness measuring device (for example, an ultrasonic method) for measuring the thickness of the water column is required, the overall size of the device becomes large, and it is difficult to install in a narrow space such as between steel conveying rolls. There is. Further, even if the thickness measuring device can be installed, there is a problem in that the maintenance is hindered such as requiring labor for attaching and detaching, and the stability and reliability of the temperature measurement value is lowered due to the failure of the thickness measuring device.

In order to solve the above-described problems in the method described in Patent Document 1, the present inventors have proposed the method described in Patent Document 2.
Specifically, in Patent Document 2, the heat radiation light radiated from the lower surface of the measured temperature steel material is opposed to the lower side of the measured temperature steel material through purge water jetted from the nozzle toward the lower surface of the measured temperature steel material. A method for measuring the surface temperature of a steel material to be measured by detecting with a radiation thermometer arranged, and setting all the heads of the purge water within a predetermined range with the pass line of the steel material to be measured as a position reference A method for measuring the surface temperature of a steel material characterized in that it has been proposed (Claim 2 of Patent Document 2). And it has been proposed that the wavelength of the thermal radiation detected by the radiation thermometer be 0.9 μm or less (claim 3 of Patent Document 2).

  According to the method described in Patent Document 2, by setting all the purge water heads within a predetermined range, the collision pressure of the purge water against the lower surface of the steel material to be measured is suppressed, and the purge water is at room temperature. Can also suppress cooling. For this reason, the advantage that the energy cost for heating up water like patent document 1 does not start is acquired. Moreover, the advantage that the thickness measuring apparatus for measuring the thickness of a water column becomes unnecessary is acquired by making the wavelength of the thermal radiation light detected with a radiation thermometer into 0.9 micrometer or less.

  However, in the above method described in Patent Document 2, the wavelength of the thermal radiation detected by the radiation thermometer is 0.9 μm or less, so the lower limit of the surface temperature of the steel material that can be measured by radiation is about 500 ° C. is there. In recent years, it has become important to manage the surface temperature in a low temperature range of about 200 ° C. in view of the required level for quality improvement of steel materials. There is a problem that the temperature cannot be controlled.

JP-A-8-295950 JP 2006-17589 A

  The present invention has been made to solve such problems of the prior art, and a temperature-measured material such as a steel material is water-cooled and its surface temperature is about 200 ° C. (for example, 180 to 350 ° C.). However, it is an object of the present invention to provide a surface temperature measuring method and apparatus capable of measuring temperature accurately and a method of manufacturing a steel material having a step of measuring the surface temperature by this method.

  In order to solve the above-mentioned problems, the present inventors have intensively studied. As will be described later, if the wavelength of the thermal radiation detected by the radiation thermometer is 1.60 to 1.80 μm, the temperature is as low as about 200 ° C. We found that there was little variation in temperature measurement values even in the area. In addition, as described later, the present inventors have found that the water transmittance is relatively high in the wavelength band of 1.60 to 1.80 μm, and as a result, the radiation thermometer and the temperature-measured material It was found that the temperature measurement error due to the absorption of thermal radiation by the water that entered between them can be reduced. The present invention has been completed based on the knowledge of the present inventors.

  That is, in order to solve the above-mentioned problem, the present invention detects the thermal radiation emitted from the surface of the temperature-measuring material during water cooling with a radiation thermometer disposed opposite to the surface of the temperature-measuring material, A method for measuring the surface temperature of the temperature-measuring material, wherein the wavelength of thermal radiation detected by the radiation thermometer is 1.60 to 1.80 μm. .

  According to such an invention, the surface temperature of the material to be measured can be accurately measured even when the material to be measured is water-cooled and its surface temperature is in a low temperature range of about 200 ° C.

  By injecting air from the radiation thermometer toward the surface of the material to be measured, an air column is formed between the surface of the material to be measured and the radiation thermometer, and through the air column It is preferable to detect the thermal radiation emitted from the surface of the temperature-measuring material with the radiation thermometer.

  According to such a preferable configuration, the intrusion of water between the radiation thermometer and the temperature-measured material is suppressed by the air column, and the temperature can be measured with higher accuracy.

  The amount of water that enters between the radiation thermometer and the temperature-measuring material is not always constant, and usually varies with time. And the more the amount of water that enters, the greater the temperature measurement error due to the absorption and scattering of thermal radiation by the water. Specifically, the greater the amount of water that enters, the lower the temperature measurement value. For this reason, if the maximum temperature measurement value is used as the measurement result among the plurality of temperature measurement values obtained within the predetermined time, the measurement result is obtained at the timing when the amount of water entering the predetermined time is the smallest. Therefore, it can be expected that the temperature measurement accuracy is further improved.

  Therefore, it is preferable to output the maximum measured value among the plurality of measured values obtained within a predetermined time by the radiation thermometer as the surface temperature of the material to be measured.

Further, when the thickness of water that can exist between the surface of the temperature-measuring material and the radiation thermometer is h, the temperature-measuring material is measured from the radiation thermometer at a flow velocity V that satisfies the following formula. It is preferable to inject air toward the surface.
V ² > 2 · ρ _L · g · h / ρ _g
However, in said formula, (rho) _L means the density of water, (rho) _g means the density of air, and g means a gravitational acceleration.

  According to such a preferable configuration, for example, the thermal radiation light radiated from the lower surface of the material to be measured is detected by the radiation thermometer disposed opposite to the lower surface of the material to be measured, and air is injected toward the lower surface of the material to be measured. In this case, as will be described later, the dynamic pressure of the sprayed air becomes larger than the static pressure of the lowermost surface of water. For this reason, the water which exists between a radiation thermometer and a temperature measuring material becomes easy to be excluded by air, and the surface temperature of the temperature measuring material can be measured with higher accuracy.

  Here, in order to further improve the temperature measurement accuracy, when the thickness of water existing between the surface of the temperature measurement material that causes a temperature measurement error and the radiation thermometer is small (for example, 0.1 mm or less) Only in the case), it is preferable to output the temperature measurement value as the surface temperature of the material to be measured. Therefore, as a result of intensive studies on the method for evaluating the thickness of the water, the present inventors have analyzed the heat radiation emitted from the surface of the temperature-measuring material into a plurality of wavelength bands and obtained heat in each wavelength band. It has been found that the ratio of the energy of synchrotron radiation varies with the thickness of water.

  That is, in order to further improve the temperature measurement accuracy, the thermal radiation emitted from the surface of the temperature-measured material is divided into a plurality of wavelength bands, and based on the ratio of the energy of the thermal radiation light in each wavelength band, When it is determined whether or not the thickness of water existing between the surface of the temperature-measured material and the radiation thermometer is 0.1 mm or less, and the thickness of the water is determined to be 0.1 mm or less It is preferable to output only the surface temperature of the temperature-measuring material.

  Specifically, the heat radiation emitted from the surface of the temperature-measuring material is spectrally divided into wavelength bands of 1.60 to 1.80 μm, 1.65 to 1.75 μm, and 1.88 to 1.94 μm. It is preferable to do.

  In order to solve the above-mentioned problem, the present invention includes a radiation thermometer disposed opposite to the surface of the temperature-measuring material that is being water-cooled, and radiates the heat radiation emitted from the surface of the temperature-measuring material. A device for measuring the surface temperature of the temperature-measuring material by detecting with a thermometer, between the surface of the temperature-measuring material and the detection element of the radiation thermometer. It is also provided as a surface temperature measuring device comprising an optical filter that transmits only light in the wavelength band of 80 μm.

  Furthermore, in order to solve the above-mentioned problem, the present invention provides a method for producing a steel material, wherein the temperature-measured material is a steel material, and includes a step of measuring a surface temperature by any one of the methods described above. Provided.

  According to the present invention, by setting the wavelength of the heat radiation light detected by the radiation thermometer to 1.60 to 1.80 μm, fluctuations in the temperature measurement value are reduced even in a low temperature range of about 200 ° C. In addition, since the transmittance of water is relatively high in the wavelength band of 1.60 to 1.80 μm, a temperature measurement error caused by absorption of heat radiation light by water that has entered between the radiation thermometer and the temperature measurement material. Can be reduced. As a result, according to the present invention, the surface temperature of the material to be measured can be accurately measured even when the material to be measured is water-cooled and the surface temperature is in a low temperature range of about 200 ° C.

FIG. 1 is a schematic diagram showing a schematic configuration of a surface temperature measuring apparatus according to the first embodiment of the present invention. FIG. 2 is a graph showing an example of a result of evaluating a temperature measurement variation of a radiation thermometer in which the wavelength of thermal radiation to be detected is 0.65 to 0.83 μm. FIG. 3 is a graph showing the results of examining the spectral transmittance of water in the wavelength band of 1.0 to 2.5 μm. FIG. 4 shows the spectral radiance of a black body at 200 ° C. FIG. 5 is a graph showing an example of a result of evaluating a temperature measurement value variation of a radiation thermometer in which the wavelength of detected thermal radiation light is 1.60 to 1.80 μm. FIG. 6 is a graph showing the results of examining the water transmittance in the wavelength band of 1.60 to 1.80 μm. FIG. 7 is a graph showing an example of a result of evaluating a temperature measurement value variation of a radiation thermometer in which the wavelength of heat radiation light detected through water having a thickness of 1 mm, 2 mm, and 4 mm is 1.60 to 1.80 μm. is there. FIG. 8 is a schematic diagram showing a schematic configuration of a test apparatus for examining air purge. FIG. 9 shows measured values and calculated values of the thickness of water that can be removed according to the air flow rate. FIG. 10 is a graph showing an example of a result of evaluating a temperature measurement error that occurs when the air flow rate is changed in the test apparatus shown in FIG. FIG. 11 is a graph showing an example of a temperature measurement result using the test apparatus shown in FIG. FIG. 12 is a graph showing variations in measurement results (extracted maximum temperature measurement values) when the time unit for extracting the maximum temperature measurement value is changed with respect to the plurality of temperature measurement values shown in FIG. . FIG. 13 is a graph showing the result of extracting the maximum temperature measurement value every 0.2 sec for the plurality of temperature measurement values shown in FIG. FIG. 14 is a graph showing another example of a temperature measurement result using the test apparatus shown in FIG. FIG. 15 is a schematic diagram showing a schematic configuration of a surface temperature measuring apparatus according to the second embodiment of the present invention. FIG. 16 is a graph showing an example of a change of E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm). FIG. 17 is a graph showing an example of a change of E (1.88 to 1.94 μm) / E (1.60 to 1.80 μm). 18 is an enlarged graph showing a portion where the thickness of water is small in the graph shown in FIG. FIG. 19 is a schematic diagram illustrating a schematic configuration example of a production line for thick steel plates.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings as appropriate.

<First Embodiment>
FIG. 1 is a schematic diagram showing a schematic configuration of a surface temperature measuring apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the surface temperature measuring apparatus 100 according to the present embodiment includes a radiation thermometer 1 disposed opposite to a temperature-measured material (steel plate M in the present embodiment) during water cooling, and the surface of the steel plate M This is a device for measuring the surface temperature of the steel sheet M by detecting the thermal radiation emitted from the lower surface (in this embodiment) with the radiation thermometer 1. Further, the surface temperature measuring apparatus 100 according to the present embodiment includes a nozzle 2 for air purging (injecting air) toward the surface of the steel sheet M (lower surface in the present embodiment). Furthermore, the surface temperature measuring apparatus 100 according to the present embodiment includes a flow rate adjusting valve 3 for adjusting the flow rate of air supplied from the air supply source (not shown) to the nozzle 2, and the air in the air supplied to the nozzle 2. And a filter 4 for removing moisture and oil.

  The radiation thermometer 1 is transmitted by a light receiving optical system 11 that receives thermal radiation from the surface of the steel plate M, an optical fiber 12 that transmits thermal radiation received by the light receiving optical system 11, and the optical fiber 12. The temperature calculation unit 13 that detects the thermal radiation and converts it into a temperature, and among the plurality of temperature measurement values obtained within a predetermined time by the temperature calculation unit 13, the maximum temperature measurement value is used as the surface temperature of the steel sheet M. And a maximum temperature measurement value extraction unit 14 for output.

The light receiving optical system 11 is an optical system for adjusting the detection field of the thermal radiation light, and includes a condenser lens, a field stop, and the like.
As the optical fiber 12, for example, an optical fiber made of a quartz material can be used. Since the optical fiber 12 alone may be damaged, the optical fiber 12 is covered with a stainless steel flexible hose.
A part of the light receiving optical system 11 and the optical fiber 12 described above is built in the nozzle 2 and is positioned by an appropriate guide member (not shown) along the central axis of the nozzle 2.

  The temperature calculation unit 13 includes an InGaAs photodiode as a detection element that photoelectrically converts thermal radiation light transmitted through the optical fiber 12 and outputs a current corresponding to the amount of light, and outputs an output current from the InGaAs photodiode. After amplification, current-voltage conversion and AD conversion are performed, and the emissivity of the steel sheet M is corrected and converted into temperature. Further, the temperature calculation unit 13 is more specifically arranged between the surface (lower surface) of the steel plate M and the detection element of the radiation thermometer 1, more specifically, the end of the optical fiber 12 on the temperature calculation unit 13 side and the InGaAs photodiode. And an optical filter that transmits only light in the wavelength band of 1.60 to 1.80 μm. Thereby, the wavelength of the thermal radiation light detected by the radiation thermometer 1 becomes 1.60 to 1.80 μm.

  The maximum temperature measurement value extraction unit 14 extracts the maximum temperature measurement value in a predetermined time unit from the plurality of temperature measurement values obtained by the temperature calculation unit 13. The time unit for extracting the maximum temperature measurement value is determined in consideration of variations in measurement results (extracted maximum temperature measurement value) and required response time. The maximum temperature measurement value extraction unit 14 of the present embodiment samples the temperature measurement value obtained by the temperature calculation unit 13 every 10 msec, extracts the maximum temperature measurement value every 0.2 sec, and extracts the extracted maximum measurement value. The temperature value is output as the surface temperature of the steel plate M.

  The nozzle 2 is disposed at a position where the distance between its tip and the lower surface of the steel plate M is, for example, about 40 mm. Air is supplied to the nozzle 2 from an air supply source via a flow rate adjusting valve 3 and a filter 4. The nozzle 2 includes a stainless steel mesh 21, and the supplied air is rectified by passing through the mesh 21. The rectified air that has passed through the mesh 21 is jetted from the tip of the nozzle 2 toward the lower surface of the steel plate M. Thereby, an air column A is formed between the lower surface of the steel plate M and the radiation thermometer 1. Thermal radiation light radiated from the lower surface of the steel plate M is detected by the radiation thermometer 1 through the air column A. The bottom surface of the nozzle 2 is provided with a seal portion 22 having an O-ring to prevent air leakage, and the optical fiber 12 extends outside the nozzle 2 via the seal portion 22. .

  The flow rate adjusting valve 3 functions to reduce the air consumption by reducing the air flow rate supplied to the nozzle 2 when water cooling around the nozzle 2 is stopped or when the amount of cooling water is small. Further, the filter 4 has a function of removing dirt and oil in the air supplied to the nozzle 2 and reducing contamination of the light receiving optical system 11 and the optical fiber 12.

In the present embodiment, as a preferable configuration, the thickness of the water W that can exist between the lower surface of the steel plate M and the radiation thermometer 1 (specifically, between the lower surface of the steel plate M and the tip of the nozzle 2). If h is h, air is injected at a flow velocity V that satisfies the following equation.
V ² > 2 · ρ _L · g · h / ρ _g
However, in said formula, (rho) _L means the density of water, (rho) _g means the density of air, and g means a gravitational acceleration.
If the value of the water thickness h in the above formula is set to a value equal to the distance between the lower surface of the steel plate M and the tip of the nozzle 2 (in this embodiment, about 40 mm), the steel plate is not sprayed with air. Even when the space between the lower surface of M and the tip of the nozzle 2 is completely filled with water W (as shown in FIG. 1), it is preferable in that the water W can be eliminated.

  Hereinafter, the reason for setting various parameters in the surface temperature measuring apparatus 100 according to the present embodiment will be described.

(1) About the wavelength of the thermal radiation light detected with the radiation thermometer 1 As mentioned above, the wavelength of the thermal radiation light detected with the radiation thermometer 1 shall be 1.60-1.80 micrometers.
In setting the above wavelength band, the inventors first made a prototype of a radiation thermometer in which the wavelength of thermal radiation to be detected was 0.65 to 0.83 μm, and evaluated its temperature characteristics. Specifically, the temperature of a radiant heat source (black body furnace, temperature variation of 1 ° C. or less) that is generally used to evaluate the temperature characteristics of a radiant thermometer is measured with the prototype radiation thermometer via water. Then, the variation (3σ) in the temperature measurement value was evaluated. The emissivity of the black body furnace, which is a radiant heat source, was 1.0. FIG. 2 is a graph illustrating an example of evaluation results of temperature measurement variation with respect to various water thicknesses. As shown in FIG. 2, in the case of a radiation thermometer having a wavelength of 0.65 to 0.83 μm to detect the thermal radiation light, the temperature measurement value fluctuates greatly at 600 ° C. or less, and the temperature is measured accurately. I found out I couldn't. This is considered to be caused by the fact that the long wavelength component of the emitted thermal radiation increases when the temperature-measuring material becomes low temperature. Therefore, it has been found that in order to perform radiation measurement at a temperature in a low temperature region of 600 ° C. or lower, it is necessary to shift the wavelength of the thermal radiation light to be detected to a longer wavelength side than 0.65 to 0.83 μm.

  Next, the present inventors assume the case where the thermal radiation light emitted from the temperature-measured material in the low temperature range is detected through water positioned between the temperature-measured material and the radiation thermometer, The spectral transmittance of water was investigated. FIG. 3 shows a case where the thickness of water interposed between the black body furnace and the radiation thermometer is 0.1 mm, 0.2 mm, 0.5 mm, 1.0 mm, 2.0 mm, and 4.0 mm. It is a graph which shows the spectral transmittance of water in a wavelength band of 1.0-2.5 micrometers. As shown in FIG. 3, in the wavelength band longer than 0.65 to 0.83 μm, the wavelength band near 1.2 μm, the wavelength band near 1.7 μm, and the wavelength band near 2.2 μm. It was found that the water permeability was high.

FIG. 4 shows the spectral radiance of a black body at 200 ° C. When an InGaAs photodiode is used as the detection element of a radiation thermometer, the spectral radiance is low and the sensitivity of the InGaAs photodiode is low in the wavelength band near 1.2 μm, so it is suitable for measurement in a low temperature range of about 200 ° C. Not.
In addition, in the wavelength band near 2.2 μm, although it is advantageous in that the spectral radiance is high, when an inexpensive quartz glass is used as a condenser lens or an optical fiber of a light receiving optical system constituting the radiation thermometer, There is a problem that the light transmittance is lowered.
On the other hand, in the wavelength band near 1.7 μm, the spectral radiance and the sensitivity of the InGaAs photodiode are high, and inexpensive quartz glass is used as the condenser lens and optical fiber of the light receiving optical system constituting the radiation thermometer. it can.

  Therefore, the inventors made a prototype of a radiation thermometer in which the wavelength of the thermal radiation light to be detected is 1.60 to 1.80 μm including a wavelength in the vicinity of 1.7 μm, and its temperature characteristics are measured using a black body furnace. evaluated. FIG. 5 is a graph showing an example of the evaluation result. As shown in FIG. 5, in the case of a radiation thermometer having a wavelength of heat radiation light to be detected of 1.60 to 1.80 μm, if the variation in temperature measurement value (3σ) is 2 ° C., the allowable range is It was found that measurement was possible up to 160 ° C.

  In addition, the inventors appropriately changed the thickness of water interposed between the radiation thermometer and the black body furnace in which the wavelength of the thermal radiation light to be detected was 1.60 to 1.80 μm, and the black body furnace The water permeability was investigated by appropriately changing the temperature. FIG. 6 is a graph showing the results of examining the water permeability. As shown in FIG. 6, it was found that although the transmittance decreases as the water thickness increases, a transmittance of about 20% can be obtained if the thickness of the water film can be reduced to about 2 mm.

  Furthermore, the present inventors set the thickness of the water interposed between the radiation thermometer with the wavelength of the thermal radiation light to be detected being 1.60 to 1.80 μm and the black body furnace to 1 mm, 2 mm, and 4 mm, Temperature characteristics were evaluated. FIG. 7 is a graph showing an example of the evaluation result. As shown in FIG. 7, in the case of a radiation thermometer having a wavelength of 1.60 to 1.80 μm for detecting the thermal radiation light, even when 2 mm thick water is used, variation in temperature measurement value (3σ) Assuming that the allowable range is up to 3 ° C., it was found that the temperature-measured material in the low temperature range up to about 200 ° C. can be measured.

  As described above, if the wavelength of the thermal radiation light detected by the radiation thermometer is 1.60 to 1.80 μm, the temperature measurement value hardly fluctuates even in a low temperature range of about 200 ° C. Temperature measurement errors due to absorption of thermal radiation by water that has entered between the temperature measuring materials can also be reduced. For this reason, the wavelength of the thermal radiation light detected by the radiation thermometer 1 of the present embodiment is 1.60 to 1.80 μm.

(2) Flow rate of air sprayed from the nozzle 2 As described above, if the thickness of the water interposed between the temperature-measured material and the radiation thermometer can be reduced to about 2 mm, the temperature of the low-temperature range up to about 200 ° C. Although it is possible to measure the temperature of the temperature measuring material, the thickness of the intervening water is preferably as small as possible in order to increase the temperature measurement accuracy. For this reason, the present inventors examined air purging from the radiation thermometer toward the temperature-measured material to eliminate water.

  FIG. 8 is a schematic diagram showing a schematic configuration of a test apparatus for examining air purge. As shown in FIG. 8, an air purge nozzle 2 having a built-in radiation thermometer 1 '(as described above, a prototype radiation thermometer in which the wavelength of the detected thermal radiation light is 1.60 to 1.80 μm). 'Was installed on the bottom of the aquarium 5. Above the nozzle 2 ′, a rubber heater 7 is installed on the quartz glass 6 in order to simulate the heat radiation emitted from the temperature measuring material. The distance between the lower surface of the quartz glass 6 and the tip of the nozzle 2 'was set to 60 mm. The measurement field diameter of the radiation thermometer 1 '(field diameter at the tip of the nozzle 2') was 6 mm, and the diameter of the tip of the nozzle 2 'was 22 mm.

  In the test apparatus having the above-described configuration, water W was injected into the water tank 5 while air was being sprayed from the nozzle 2 ′ toward the lower surface of the quartz glass 6. At this time, by adjusting the flow rate of the air supplied to the nozzle 2 ′, the flow rate of the air injected from the nozzle 2 ′ is changed, and the thickness of the water W that can be eliminated at each air flow rate (the tip of the nozzle 2 ′ and the water W The maximum value of the distance to the upper surface of the film was measured. Note that whether or not the water W was removed was determined by visually confirming whether or not an air column reaching the upper surface of the water W was formed. The flow rate of air was calculated by dividing the flow rate of air supplied to the nozzle 2 ′ measured by the flow meter 9 by the diameter of the tip of the nozzle 2 ′.

On the other hand, in order to eliminate the water W with the air jetted from the nozzle 2 ′, theoretically, the dynamic pressure of the jetted air is higher than the static pressure Ps at the lowermost surface of the water W (static pressure at the tip of the nozzle 2 ′). (Dynamic pressure at the tip of the nozzle 2 ') It is necessary to determine the air flow rate so that Pd becomes larger, that is, the following equation (1) is satisfied.
Pd> Ps (1)

Here, the static pressure Ps on the lowermost surface of the water W is expressed by the following equation (2), and the dynamic pressure Pd of the air to be injected is expressed by the following equation (3).
Ps = ρ _L · g · h (2)
Pd = 1/2 · ρ _g · V ² (3)
In the above equations (2) and (3), ρ _L is the density of water W, ρ _g is the density of air, g is the acceleration of gravity, h is the thickness of water W, and V is the flow velocity of air. Means.

Substituting the above formulas (2) and (3) into both sides of the above formula (1) and rearranging, the following formula (4) is established.
V ² > 2 · ρ _L · g · h / ρ _g (4)
In other words, in order to eliminate the water W having a thickness h, it is theoretically necessary to inject air at a flow velocity V that satisfies the above equation (4).

  FIG. 9 shows the measured value of the thickness (maximum value) of water that can be removed according to the air flow rate described above, and the water that can be removed according to the air flow rate derived from the equation (4). The calculated thickness (maximum value) is shown. As shown in FIG. 9, the calculated value derived from the equation (4) matches the measured value relatively well. Therefore, if the flow velocity of the air injected from the nozzle 2 is determined so as to satisfy the equation (4), the water W existing between the radiation thermometer 1 ′ and the rubber heater 7 is actually easily removed by the air. I found out that

  Next, in the test apparatus shown in FIG. 8, the temperature of the rubber heater 7 was measured with the radiation thermometer 1 ′, and at the same time, the temperature of the rubber heater 7 was measured by attaching a thermocouple 8 (hereinafter referred to as the thermocouple 8). The measured temperature is called actual temperature). At this time, the thickness of the water W injected into the water tank 5 was 20 mm, 40 mm, and 60 mm. Further, the flow rate of the air injected from the nozzle 2 'was changed, and the temperature measurement error at each air flow rate (difference between the temperature measured by the radiation thermometer 1' and the actual temperature) was evaluated. In addition, the maximum temperature measurement value extracted every 0.2 sec was used as the temperature measurement value by the radiation thermometer 1 '.

  FIG. 10 is a graph showing an example of an evaluation result in the above test. As is clear from the results shown in FIG. 10, the temperature of the rubber heater 7 can be accurately adjusted by the radiation thermometer 1 ′ if the flow velocity of the air injected from the nozzle 2 ′ is determined so as to satisfy the above-described formula (4). It was measurable.

Based on the results described above, in this embodiment, the water W that can exist between the lower surface of the steel plate M and the radiation thermometer 1 (specifically, between the lower surface of the steel plate M and the tip of the nozzle 2). In this case, air is jetted at a flow velocity V that satisfies the following formula.
V ² > 2 · ρ _L · g · h / ρ _g
However, in said formula, (rho) _L means the density of water, (rho) _g means the density of air, and g means a gravitational acceleration.

(3) Processing contents of the maximum temperature measurement value extraction unit 14
In the test apparatus shown in FIG. 8, the distance between the lower surface of the quartz glass 6 and the tip of the nozzle 2 ′ was set to 60 mm. In this test apparatus, water W is injected into the water tank 5 while air is being injected from the tip of the nozzle 2 ′ toward the lower surface of the quartz glass 6, and the temperature of the rubber heater 7 is adjusted to the radiation thermometer 1. Measured with '. At this time, the thickness of the water W injected into the water tank 5 was changed from 0 to 60 mm. The actual temperature of the rubber heater 7 was stable at 175 ° C.

  FIG. 11 is a graph showing an example of the result of measuring the temperature of the rubber heater 7 with the radiation thermometer 1 ′ when the thickness of the water W is 40 mm. In the example shown in FIG. 11, the air flow rate (flow rate at the tip of the nozzle 2 ′) is set to 35 m / sec that satisfies the above-described formula (4).

  As shown in FIG. 11, it was found that although the temperature measurement value of the radiation thermometer 1 ′ fluctuated greatly with time, a part of the temperature measurement value was equal to the actual temperature (175 ° C.). In the case of other water W thicknesses (except for the case of 0 mm), it was found that the same tendency as the result shown in FIG. 11 was exhibited.

  As described above, the measured temperature value of the radiation thermometer 1 'is partially equal to the actual temperature because the measured temperature value and the actual temperature are equalized by the air purge from the nozzle 2'. It is considered that water W no longer exists between the total 1 ′ and the rubber heater 7. Therefore, the present inventors use a maximum temperature measurement value among a plurality of temperature measurement values obtained within a predetermined time as a measurement result, and this measurement result is a timing at which water W does not exist within the predetermined time. Or it is a temperature measurement value obtained at the timing when the thickness of the water W present is the smallest, and it was considered that the temperature measurement accuracy can be expected to increase.

  FIG. 12 shows the variation (3σ) in the measurement result (extracted maximum temperature measurement value) when the time unit for extracting the maximum temperature measurement value is changed with respect to the plurality of temperature measurement values shown in FIG. It is a graph. FIG. 13 is a graph showing the result of extracting the maximum temperature measurement value every 0.2 sec for the plurality of temperature measurement values shown in FIG. As shown in FIGS. 12 and 13, it was found that if the maximum temperature measurement value is extracted in units of time of 0.2 sec or more, the variation in the measurement result is reduced and stable temperature measurement is possible.

  FIG. 14 shows a test apparatus shown in FIG. 8, in which the water W has a thickness of 60 mm (corresponding to the distance between the lower surface of the quartz glass 6 and the tip of the nozzle 2 ′), and the flow rate of air injected from the nozzle 2 ′ (nozzle 2). The “flow velocity at the tip” is a graph showing an example of the result of measuring the temperature of the rubber heater 7 with the radiation thermometer 1 ′ at 35 m / sec that satisfies the above-described formula (4). The actual temperature of the rubber heater was changed from 175 ° C. to 195 ° C. during the measurement.

  As shown in FIG. 14, although the temperature measurement value of the radiation thermometer 1 ′ fluctuates greatly with time, if the maximum temperature measurement value is extracted every 0.2 sec, the variation in the measurement result is reduced and stable measurement is performed. It turns out that temperature is possible.

  Based on the results described above, the maximum temperature measurement value extraction unit 14 of the present embodiment samples the temperature measurement value obtained by the temperature calculation unit 13 every 10 msec, and the maximum temperature measurement value every 0.2 sec. , And the extracted maximum temperature measurement value is output as the surface temperature of the steel plate M.

According to the surface temperature measuring apparatus 100 according to the present embodiment described above, the steel plate M is in water-cooled state by setting the wavelength of the heat radiation light detected by the radiation thermometer 1 to 1.60 to 1.80 μm. Even in the low temperature range where the surface temperature is about 200 ° C., the surface temperature of the steel sheet M can be measured with high accuracy.
Further, according to the surface temperature measuring apparatus 100 according to the present embodiment, the intrusion of the water W between the radiation thermometer 1 and the steel plate M is suppressed by the air column A formed by the air sprayed from the nozzle 2. The In particular, by injecting air at a flow velocity V that satisfies V ² > 2 · ρ _L · g · h / ρ _g , water W is effectively eliminated and the surface temperature of the steel sheet M can be measured with higher accuracy. It is.
Furthermore, according to the surface temperature measurement device 100 according to the present embodiment, the maximum temperature measurement value extraction unit 14 outputs the maximum temperature measurement value among the plurality of temperature measurement values as the surface temperature of the steel sheet M, so that the measurement is performed. As a result, variation in the results is reduced, and the surface temperature of the steel sheet M can be measured with higher accuracy.

<Second Embodiment>
FIG. 15 is a schematic diagram showing a schematic configuration of a surface temperature measuring apparatus according to the second embodiment of the present invention. As shown in FIG. 15, the surface temperature measuring device 100A according to the present embodiment is similar to the surface temperature measuring device 100 according to the first embodiment in that the radiation thermometer 1A, the nozzle 2, the flow rate adjusting valve 3, and the filter 4 are used. It has. The radiation thermometer 1A of the present embodiment is also common to the radiation thermometer 1 of the first embodiment in that the light receiving optical system 11, the optical fiber 12, the temperature calculation unit 13, and the maximum temperature measurement value extraction unit 14 are provided. To do. However, the radiation thermometer 1A of this embodiment is different from the radiation thermometer 1 of the first embodiment in that it further includes a water thickness estimation unit 15 and a temperature measurement value output unit 16. Hereinafter, the configuration common to the surface temperature measurement apparatus 100 according to the first embodiment will not be described because it has the same function, and the above differences will mainly be described.

  The optical fiber 12 constituting the radiation thermometer 1A of the present embodiment is branched into two in the middle, and one is connected to the temperature calculation unit 13 and the other is connected to the water thickness estimation unit 15. Thereby, the heat radiation light from the surface of the steel plate M is transmitted to both the temperature calculation unit 13 and the water thickness estimation unit 15 via the light receiving optical system 11 and the optical fiber 12.

  Similar to the first embodiment, the temperature calculation unit 13 photoelectrically converts only the light in the wavelength band of 1.60 to 1.80 μm out of the thermal radiation transmitted through the optical fiber 12 and converts it into temperature. Then, the maximum temperature measurement value extraction unit 14 outputs the maximum temperature measurement value as the surface temperature of the steel plate M among the plurality of temperature measurement values obtained by the temperature calculation unit 13 within a predetermined time.

  The water thickness estimation unit 15 splits the heat radiation light transmitted through the optical fiber 12 into a plurality of wavelength bands, and radiates the surface (lower surface) of the steel sheet M and the radiation based on the ratio of the energy of the heat radiation light in each wavelength band. It is determined whether or not the thickness of the water W existing between the thermometer 1A (specifically, between the lower surface of the steel plate M and the tip of the nozzle 2) is 0.1 mm or less.

  Specifically, the water thickness estimation unit 15 of the present embodiment converts the heat radiation transmitted through the optical fiber 12 from 1.60 to 1.80 μm, 1.65 to 1.75 μm, and 1.88 to 1.8. The spectrum is divided into each wavelength band of 94 μm, and the thermal radiation light in each wavelength band after the spectrum is photoelectrically converted by an InGaAs photodiode as a detection element to calculate energy. The spectroscopic method is not particularly limited. For example, there is a method in which three optical filters that transmit only light in each wavelength band are fixed to a disc, and the disc is rotated to perform spectroscopic analysis. Can be mentioned. Alternatively, the optical fiber 12 connected to the water thickness estimation unit 15 may be branched into three, and the above three optical filters may be arranged to face the ends of the three branched optical fibers (in this case) Requires three detector elements). Furthermore, it is also possible to apply a spectroscopic method using a prism or a spectroscope (in these cases, three detection elements are also required).

  Next, the water thickness estimation unit 15 performs heat radiation light energy E (1.65 to 1.75 μm) in the wavelength band of 1.65 to 1.75 μm and heat in the wavelength band of 1.60 to 1.80 μm. E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm), which is a ratio to the energy E (1.60 to 1.80 μm) of the emitted light, is calculated. Further, the water thickness estimation unit 15 includes energy E (1.88 to 1.94 μm) of heat radiation light in the wavelength band of 1.88 to 1.94 μm and heat radiation in the wavelength band of 1.60 to 1.80 μm. E (1.88 to 1.94 μm) / E (1.60 to 1.80 μm), which is a ratio to the light energy E (1.60 to 1.80 μm), is calculated.

The water thickness estimation unit 15 determines that the thickness of the water W is 1.0 mm or more when E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm) ≧ 0.55 is established. To do.
Further, the water thickness estimation unit 15 satisfies E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm) <0.55, and E (1.88 to 1.94 μm). When / E (1.60 to 1.80 μm) <0.42, the thickness of the water W is determined to be more than 0.1 mm and less than 1.0 mm.
Further, the water thickness estimation unit 15 satisfies E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm) <0.55, and E (1.88 to 1.94 μm). When / E (1.60 to 1.80 μm) ≧ 0.42, the thickness of the water W is determined to be 0.1 mm or less.

  The temperature measurement value output unit 16 outputs the output value of the maximum temperature measurement value extraction unit 14 as the surface temperature of the steel sheet M only when the water thickness estimation unit 15 determines that the thickness of the water W is 0.1 mm or less. To do. If the thickness of the water W is about 0.1 mm, as shown in FIG. 6 described above, the water permeability is about 95%, and the influence on the temperature measurement value is extremely small.

  Hereinafter, the reason why the above-described determination is performed in the water thickness estimation unit 15 of the surface temperature measurement apparatus 100A according to the present embodiment will be described.

  The inventors of the present invention have a detection between a radiation thermometer and a black body furnace in which the wavelength of the thermal radiation light to be detected is 1.60 to 1.80 μm, 1.65 to 1.75 μm, and 1.88 to 1.94 μm. While changing the thickness of the water to intervene suitably, the temperature of the black body furnace was changed suitably, and the test which detects the thermal radiation light from a black body furnace was done.

  FIG. 16 is a graph showing changes in E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm) obtained by the above test. As is clear from the results shown in FIG. 16, when E (1.65 to 1.75 μm) / E (1.60 to 1.80 μm) <0.55 is established, the blackbody furnace (temperature measurement material) Even if the temperature of the water changes in the range of 200 ° C. to 500 ° C., it can be said that the thickness of water is less than 1.0 mm.

FIG. 17 is a graph showing changes in E (1.88 to 1.94 μm) / E (1.60 to 1.80 μm) obtained by the above test. 18 is an enlarged graph showing a portion where the thickness of water is small in the graph shown in FIG.
According to the result shown in FIG. 18, when E (1.88 to 1.94 μm) / E (1.60 to 1.80 μm) ≧ 0.42 is established, the temperature of the black body furnace (temperature measuring material) Even if it changes in the range of 200 degreeC-500 degreeC, it can be said that the thickness of water is 0.1 mm or less.
However, according to the results shown in FIG. 17, even when the thickness of water exceeds 4.0 mm, E (1.88 to 1.94 μm) / E depending on the temperature of the blackbody furnace (temperature measuring material). (1.60 to 1.80 μm) ≧ 0.42 may be satisfied. That is, it is not possible to determine that the thickness of the water is 0.1 mm or less only when E (1.88 to 1.94 μm) / E (1.60 to 1.80 μm) ≧ 0.42.
Therefore, E (1.88 to 1.94 μm) / E (1.60 to 1.80 μm) ≧ 0.42 is satisfied, and at the same time, E (1.65 to 1.75 μm) / E (1. 60 to 1.80 μm) <0.55 is satisfied (that is, the water thickness is less than 1.0), the water thickness may be determined to be 0.1 mm or less.

  Based on the results described above, the water thickness estimation unit 15 of the present embodiment makes the above-described determination.

  According to the surface temperature measuring apparatus 100A according to the present embodiment described above, in addition to the configuration of the surface temperature measuring apparatus 100 according to the first embodiment, the surface of the steel plate M and the radiation temperature that cause a temperature measurement error. Compared to the surface temperature measuring apparatus 100 because the temperature measurement value is output as the surface temperature of the steel plate M only when the thickness of the water W existing between the total 1A is small (in the case of 0.1 mm or less). Therefore, it can be expected that the temperature measurement accuracy will be further improved.

  Hereinafter, a method for producing a thick steel plate by applying the surface temperature measuring device according to the present invention to a production line for the thick steel plate will be described.

FIG. 19 is a schematic diagram illustrating a schematic configuration example of a production line for thick steel plates.
In the production line 10 shown in FIG. 19, a heating furnace 20, a rough rolling mill 30, a finishing rolling mill 40, a cooling device 50, and a hot leveler 60 are arranged in this order from the left side of the drawing. The slab M1 heated to about 1100 to 1200 ° C. in the heating furnace 20 is reduced in thickness to a certain thickness by the roughing mill 30 to be a rough rolled material M2. Next, the rough rolled material M2 is reciprocated before and after the finish rolling mill 40 to be a rolled material M3 having a predetermined thickness. Thereafter, the material to be rolled M3 is water cooled by the cooling device 50 and the material is adjusted, and then the flatness is corrected by the hot leveler 60.

  In the thick steel plate production line 10 having the above-described configuration, the surface temperature measuring device according to the present invention is installed in the cooling device 50 (specifically, for example, between the transport rolls arranged in the cooling device 50). Can be used. The cooling device 50 is used to cool the material 8 to be rolled, which has a temperature of about 600 to 700 ° C. even after passing through the finish rolling mill 40, to near room temperature. The surface temperature measuring apparatus according to the present invention has a surface temperature of the material to be rolled 8 in a low temperature range of about 200 ° C. by setting the wavelength of the heat radiation light detected by the radiation thermometer to 1.60 to 1.80 μm. However, it is possible to measure temperature accurately. Moreover, since the plate | board thickness of the to-be-rolled material 8 is thick, although the cooling device 50 requires a lot of cooling water, it is air purge toward the surface of the to-be-rolled material 8 like the surface temperature measuring device based on this invention. If an air column is formed, highly accurate temperature measurement is possible even in an environment where a large amount of cooling water exists.

  As described above, the surface temperature measuring device according to the present invention can be installed in the cooling device 50 in which a large amount of cooling water is used in the thick steel plate production line 10.

DESCRIPTION OF SYMBOLS 1 ... Radiation thermometer 2 ... Nozzle 3 ... Flow control valve 4 ... Filter 11 ... Light-receiving optical system
DESCRIPTION OF SYMBOLS 12 ... Optical fiber 13 ... Temperature calculation part 14 ... Maximum temperature measurement value extraction part 100 ... Surface temperature measurement apparatus A ... Air column W ... Water M ... Steel plate (to be measured Warm material)

Claims (8)

A method of measuring the surface temperature of the temperature-measured material by detecting thermal radiation emitted from the surface of the temperature-measured material during water cooling with a radiation thermometer disposed opposite to the surface of the temperature-measured material. There,
A method for measuring a surface temperature, wherein the wavelength of thermal radiation detected by the radiation thermometer is 1.60 to 1.80 μm. By injecting air from the radiation thermometer toward the surface of the temperature measuring material, an air column is formed between the surface of the temperature measuring material and the radiation thermometer,
2. The surface temperature measuring method according to claim 1, wherein the radiation thermometer detects thermal radiation emitted from the surface of the temperature-measuring material through the air column.   The maximum temperature measurement value among a plurality of temperature measurement values obtained within a predetermined time by the radiation thermometer is output as the surface temperature of the temperature measurement material. Surface temperature measurement method. When the thickness of water that can exist between the surface of the temperature measuring material and the radiation thermometer is h, the surface of the temperature measuring material from the radiation thermometer at a flow velocity V that satisfies the following formula: The surface temperature measuring method according to claim 2, wherein air is jetted toward the surface.
V ² > 2 · ρ _L · g · h / ρ _g
However, in said formula, (rho) _L means the density of water, (rho) _g means the density of air, and g means a gravitational acceleration.   The thermal radiation light radiated from the surface of the temperature measurement material is divided into a plurality of wavelength bands, and the surface of the temperature measurement material and the radiation thermometer based on the ratio of the energy of the thermal radiation light of each wavelength band Only when it is determined whether the thickness of the water existing between and is 0.1 mm or less and the thickness of the water is 0.1 mm or less, the surface temperature of the temperature-measured material is determined. 5. The surface temperature measuring method according to claim 1, wherein the surface temperature is measured.   The present invention is characterized in that the heat radiation emitted from the surface of the temperature-measuring material is split into each wavelength band of 1.60 to 1.80 μm, 1.65 to 1.75 μm, and 1.88 to 1.94 μm. The surface temperature measuring method according to claim 5. A radiation thermometer disposed opposite to the surface of the temperature-measuring material during water cooling, and detecting the heat radiation emitted from the surface of the temperature-measuring material by the radiation thermometer; An apparatus for measuring the surface temperature of
An apparatus for measuring a surface temperature, comprising an optical filter that transmits only light having a wavelength band of 1.60 to 1.80 μm between a surface of the temperature-measured material and a detection element of the radiation thermometer. The measured temperature material is a steel material,
A method for producing a steel material, comprising a step of measuring a surface temperature by the method according to claim 1.