JP2008032486A - Steel plate temperature measuring method and temperature measuring apparatus, and steel plate temperature control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method, in a measuring method using multiple reflection, which can measure the steel plate temperature with high accuracy over a long period of time, without being affected by fluctuations in the emissivity of a steel plate under measurement and changes in passage of time in the emissivity of a reflecting plate and its apparatus and a high-accuracy steel plate temperature control method. <P>SOLUTION: The reflective plate 2 provided with a temperature control device 5 is placed facing the steel plate 1; a reflecting plate temperature T<SB>2</SB>is measured directly by a contact thermometer 6; radiation energy which is multiply reflected between the reflecting plate 2 and the steel plate 1 is measured by a radiation thermometer 7; the temperature, determined by converting into the temperature of a black body which radiates energy equivalent to the radiation energy, is regarded as a multiple reflection temperature T<SB>m</SB>; and the temperature control device 5 performs control to make the reflecting plate temperature T<SB>2</SB>coincide with the multiple reflection temperature T<SB>m</SB>, and the multiple reflection temperature T<SB>m</SB>is set as the steel plate temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for measuring the temperature of a steel sheet in a non-contact manner, for example, used in a continuous annealing facility or an alloyed hot dip galvanizing facility.

  In continuous annealing equipment for continuously heat-treating steel sheets and galvannealed equipment for galvanizing after hot-dip plating, various types of steel sheets are continuously processed. For this reason, in order to stabilize the mechanical properties (strength, elongation, etc.) and plating properties (degree of alloying, etc.) of steel plates that differ for each product type, the steel plate temperature after the heat treatment process with heating / cooling is set to the target temperature. It is important to control accurately.

  In general, the temperature of a steel sheet continuously conveyed in these facilities is measured using a non-contact radiation thermometer. When using a radiation thermometer, it is necessary to set the emissivity of the steel sheet that is the object to be measured. However, since the emissivity of a steel sheet varies depending on various factors such as the steel sheet itself, the physical properties of the steel sheet, such as the surface properties, and the temperature of the steel sheet, setting the emissivity of the steel sheet in response to such variations is very Have difficulty. As a result, there is a problem that an error is easily generated in the measurement of the steel plate temperature, and the steel plate temperature cannot be accurately controlled to the target temperature.

  Therefore, various measurement methods using multiple reflection have been proposed as a measurement method that eliminates the influence of the emissivity fluctuation of the steel plate as much as possible based on the knowledge that the apparent emissivity increases when multiple reflection is performed. .

  For example, in the cavity method described in Patent Document 1, two types of cylindrical cavities whose inner surface is close to a mirror surface and have high reflectivity are installed close to the steel plate to be measured, and multiple reflections pass through the first cavity. This is a method of obtaining the steel sheet temperature and emissivity by comparing the radiated energy with the radiant energy that has simply passed through the second cavity without multiple reflection. However, in this method, since it is necessary to install two cylindrical cavities, securing a large space becomes a problem.

  On the other hand, as a method that does not require a large space compared with the cavity method, a method using multiple reflection between the steel plate to be measured and the reflecting plate has been proposed.

  For example, in the measurement method described in Patent Document 2, a reflection plate is provided so as to be inclined to face a steel plate, and radiation obtained by considering the radiant energy due to multiple reflection generated between the steel plate and the reflection plate as black body radiant energy. The indicated temperature of the thermometer is the steel plate temperature.

  Moreover, in the measuring method of patent document 3, the method of determining the emissivity of a steel plate from the radiation energy obtained by the same measurement as patent document 2 is disclosed.

  In the measurement methods described in Patent Documents 2 and 3 (including the cavity method described in Patent Document 1), the radiant energy of the reflector plate itself is measured by lowering the reflector plate at room temperature or low temperature. If the reflectivity of the reflector is high (ie, the emittance is lower than Kirchhoff's law) or the reflectivity (emissivity) of the reflector is known This is based on the fact that the influence of the emissivity fluctuation of the steel sheet on the radiant energy by reflection can be ignored. Therefore, in the measurement methods described in Patent Documents 2 and 3 (including the cavity method described in Patent Document 1), the reflectance of the reflector is always maintained in a high state (that is, a mirror surface state), or It is necessary to maintain the known emissivity of the reflector for a long period of time, but since the reflectivity (emissivity) changes due to oxidation of the surface of the reflector, etc., it is necessary to maintain stable accuracy over a long period of time. Is difficult. The same is described in Patent Document 5 described later.

  As a method for improving such a problem, in the measuring method described in Patent Document 4, by performing multiple reflections between the steel plates to be measured, the temperature of the steel plates can be measured regardless of the influence of the emissivity of the steel plates to be measured. Yes. This measurement method uses the basic physical phenomenon that the apparent emissivity increases when multiple reflections are made within the object to be measured, and the reflectivity (emissivity) of the reflector is not used because the reflector is not used. Since there is no influence, even if the emissivity of the steel sheet to be measured varies, the apparent emissivity becomes substantially equal to 1, so that the measurement method has little measurement error and is not affected by changes over time. However, since multiple reflections between the steel plates to be measured are used, there is a problem that the measurement location can be applied only to a very limited part where the steel plates run opposite to each other by vertical hearth rolls of a vertical furnace.

  On the other hand, as a measure for improving the measurement method described in Patent Document 3, in the measurement method described in Patent Document 5, the reflectance (emissivity) of the reflector is increased by providing a function of keeping the temperature of the reflector constant. It is said that measurement accuracy can be improved even if it changes with time.

However, even with the measurement method described in Patent Document 5, in order to accurately control the steel plate temperature to the target temperature, the reflector is adjusted to an appropriate temperature according to the emissivity and temperature of the steel plate to be measured, the emissivity of the reflector, and the like. Therefore, it is difficult to stably control the steel plate to the target temperature with high accuracy over a long period of time.
JP 54-85079 A JP 59-87329 A JP 59-1111026 A JP 60-86431 A JP-A-5-203497

Therefore, the present invention is a measurement method using multiple reflections, which measures the steel plate temperature with high accuracy over a long period of time without being affected by fluctuations in the emissivity of the steel plate to be measured and changes in the emissivity of the reflector plate over time. An object of the present invention is to provide a more accurate method and apparatus therefor, and a more accurate temperature control method for a steel sheet using this measurement method.

In order to solve the above-mentioned problems, the inventors have conducted the following theoretical investigation on a measuring method using multiple reflection between a steel plate and a reflecting plate.

That is, radiant energy E _m for multiple reflection of the steel sheet and the reflecting plates is expressed by the following equation (11).

From the above equation (11), when F = [1- (1-ε ₁ ) ⁿ (1-ε ₂ ) ⁿ ] and transformed into an equation for obtaining E _b (T ₁ ), the following equation (12) is obtained. It is done.

Here, since 0 <ε1 <1, 0 <ε2 <1, when n is sufficiently large,

Thus, the above equation (12) is simplified to the following equation (13).

Here, the temperature of a black body that emits multiple reflection energy E _m equivalent energy measured by a radiation thermometer (hereinafter, referred to as "multiple reflection temperature" or "radiation thermometer indicated temperature".) The When T _m, From E _m = σT _m ⁴ , the following formula (15) is obtained.

However, since the correction coefficient K is a function of the emissivities ε ₁ and ε ₂ of the steel plate and the reflector as shown in the equation (14), the right side of the equation (16) is still the value of the steel plate and the reflector. In the case of a function including emissivity, and T _m ≠ T ₂ , the steel sheet temperature T ₁ calculated by the equation (15) includes a measurement error.

    Therefore, the inventors have further studied means for reducing the measurement error as much as possible, and as a result, have developed the following first to third means.

[First means]
The first means is for controlling the reflection plate heated to cooling by the temperature control device a reflector temperature T ₂ to match the multiple reflections temperature T _m. As a result, the value of K (T _m ⁴ −T ₂ ⁴ ) in the second term on the right side of the equation (15) approaches 0. As a result, the above equation (15) becomes T ₁ ⁴ = T _m ⁴ , that is, T ₁ = T _m , and the steel plate temperature T ₁ is obtained regardless of the accuracy of the correction coefficient K.

[Second means]
Second means, similarly to the first means, performs the control of the reflector temperature T _2, the reflection plate temperature T _2, rather than the multiple reflections temperature T _m, further simplifying the above formula (15) The control is performed so as to match the approximate value T ₁ ′ of the steel plate temperature T ₁ calculated using the following formula 1 (formula (1)). Thus, the reflecting plate temperature T ₂ will be closer to the more rapidly the actual steel sheet temperature T _1, the steel sheet temperature of the high accuracy and thus be measured earlier.

[Third means]
Unlike the first and second means, the third means does not control the reflector temperature T ₂ so as to coincide with the multiple reflection temperature T _m or the estimated value T ₁ ′ of the steel sheet temperature. it is for setting the steel target temperature T _0. As a result, it is possible to set the reflector temperature T ₂ in advance to the steel plate target temperature T ₀ , which eliminates the time required for the control to match the multiple reflection temperature T _{m and the} like. A highly accurate steel plate temperature can be measured. Then, by controlling the steel plate heating device or cooling device so that the steel plate temperature measured by this means coincides with the steel plate target temperature T ₀ , more accurate temperature control of the steel plate can be realized.

  The invention completed based on the above findings is summarized as follows.

According to the first aspect of the present invention, a reflector equipped with a temperature control device is installed opposite to a steel plate to be measured, and the temperature of the reflector (hereinafter referred to as “reflector temperature”) T ₂ is the radiation temperature described later. A black body that directly measures with a thermometer different from the meter, measures the radiant energy reflected multiple times between the reflector and the steel plate to be measured, and radiates energy equivalent to this radiant energy. the temperature obtained in terms of temperature and multiple reflection temperature T _m, the reflection plate temperature T ₂ at the temperature control unit performs control so as to coincide with the multiple reflection temperature T _m, the multiple reflection temperature T _g is a temperature of the steel plate to be measured (hereinafter referred to as “steel plate temperature”).

The invention according to claim 2, with a reflector equipped with a temperature control device placed opposite to the measured steel sheet, directly measuring the reflecting plate temperature T ₂ in a different thermometer and later radiation thermometer, The radiant energy that multi-reflects between the reflector and the steel plate to be measured is measured with a radiation thermometer, and the temperature obtained by converting it to the temperature of a black body that radiates energy equivalent to this radiant energy is the multiple reflection temperature. T _m is used to calculate an approximate value T ₁ ′ of the steel sheet temperature by the following formula 1, and the temperature control device performs control so that the reflector temperature T ₂ matches the approximate value T ₁ ′ of the steel sheet temperature. The steel plate temperature measurement method is characterized in that the approximate value T ₁ ′ of the steel plate temperature is defined as the steel plate temperature.
Formula 1 T ₁ ′ = T _m + K (T _m −T ₂ )
Here, K is a correction coefficient based on estimated values of the emissivities of the reflector and the steel plate to be measured, which are obtained from separate measurements or literature values.

According to a third aspect of the invention, a reflector having a temperature control device is installed to face the measured steel plate, the reflection plate temperature T ₂ is steel target was measured directly in a separate thermometer and later radiation thermometer The temperature is controlled by the temperature control device so as to coincide with the temperature T ₀ , and the radiant energy that is multiply reflected between the reflector and the steel plate to be measured is measured with a radiation thermometer, and the energy equivalent to this radiant energy is measured. Is a temperature obtained by converting the temperature of a black body that emits light into a multiple reflection temperature _Tm , and the multiple reflection temperature _Tm is set as a steel plate temperature.

The invention according to claim 4, the reflection plate having a temperature control device is installed to face the measured steel plate, the reflection plate temperature T ₂ is steel target was measured directly in a separate thermometer and later radiation thermometer The temperature is controlled by the temperature control device so as to coincide with the temperature T ₀ , and the radiant energy that is multiply reflected between the reflector and the steel plate to be measured is measured with a radiation thermometer, and the energy equivalent to this radiant energy is measured. The temperature obtained by converting to the temperature of a black body that emits light is defined as the multiple reflection temperature T _m, and the approximate value T ₁ ′ of the steel sheet temperature calculated by the following equation 1 is defined as the steel sheet temperature. Is the method.
Formula 1 T ₁ ′ = T _m + K (T _m −T ₂ )
Here, K is a correction coefficient based on estimated values of the emissivities of the reflector and the steel plate to be measured, which are obtained from separate measurements or literature values.

Invention of claim 5, measuring a reflection plate disposed opposite to a measured steel plate, a temperature control device for controlling the temperature of the reflector, the reflector plate temperature T ₂ directly below the radiation temperature A thermometer different from a meter, and a radiant energy that multi-reflects between the reflector and the steel plate to be measured, and a multi-reflective temperature T that is the temperature of a black body that radiates energy equivalent to this radiant energy. A steel plate temperature measuring device comprising a radiation thermometer converted into _m and a steel plate temperature calculation circuit for calculating an approximate value T ₁ ′ of the steel plate temperature from the following formula 1.
Formula 1 T ₁ ′ = T _m + K (T _m −T ₂ )
Here, K is a correction coefficient based on estimated values of the emissivities of the reflector and the steel plate to be measured, which are obtained from separate measurements or literature values.

  The invention according to claim 6 is the steel sheet according to claim 5, wherein a plurality of combinations of the reflector, the temperature control device, and the thermometer are provided, and each reflector temperature can be controlled independently. It is a temperature measuring device.

The invention according to claim 7 is characterized in that the heating device or the cooling device for the steel sheet is controlled so that the steel sheet temperature measured by the method according to claim 3 or 4 matches the steel sheet target temperature T _0. It is the temperature control method of the steel plate to perform.

  According to the present invention, the reflector temperature is controlled so as to coincide with the temperature (multiple reflection temperature) obtained by converting the radiant energy of the multiple reflection measured with a radiation thermometer into the temperature or the steel plate target temperature, and Unlike the conventional measurement method using multiple reflections, the variation in the emissivity of the steel sheet to be measured and the reflection plate (the reflection plate in the above-mentioned conventional technology) are configured by estimating the steel plate temperature based on the multiple reflection temperature. The steel sheet temperature can be measured with high accuracy over a long period of time without being affected by the change in emissivity over time. Further, by performing the heating or cooling control of the steel plate using the highly accurate steel plate temperature measured in this way, it has become possible to realize more accurate steel plate temperature control.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

Embodiment 1
FIG. 1 is a view for explaining a schematic configuration of a temperature measuring apparatus for a steel plate according to an embodiment using the first means, and shows a cross section in the plate passing direction and a control flow.

  As shown in the figure, in the same way as the inventions described in Patent Documents 2, 3, and 5, in order to ensure a sufficient number of multiple reflections, the reflecting plate 2 is installed opposite to the steel plate 1 and inclined with respect to the steel plate. Has been.

  The reflector 2 has a built-in heater 3 so that the temperature of the reflector 2 can be controlled. The heater 3 can be heated by a heater power source 4 provided with a temperature control device 5.

Further, a contact-type thermometer 6 such as a thermocouple is provided so as to be in contact with the reflector 2 as a thermometer different from the later-described radiation thermometer 7 for directly measuring the temperature of the reflector 2. Based on the reflector temperature T ₂ measured by the thermometer 6, the output of the heater power supply 4 is adjusted by the temperature controller 5, and the reflector temperature T ₂ is controlled to a predetermined temperature (described later). The initial set temperature of the reflector temperature T ₂ may be, for example, steel target temperature T _0. Also, contact thermometer 6 for measuring the temperature of the reflector 2, a plurality placed the reflecting plate 2, it is desirable to average measurements of each thermometer and reflector temperature T _2.

  On the other hand, the radiation thermometer 7 is installed from the gap between the reflecting plate 2 and the steel plate 1 toward the surface of the steel plate 1 so as to receive the radiant energy that is multiply reflected between the reflecting plate 2 and the steel plate 1. The installation angle θ of the radiation thermometer 7 with respect to the steel plate 1 is desirably adjusted in the range of 60 to 70 °, as in the inventions described in Patent Documents 2, 3 and 5.

Then, by setting the emissivity to 1.0 with the radiation thermometer 7, the multiple reflection temperature (radiation thermometer indicated temperature) T _m is the temperature of a black body that emits radiant energy equivalent energy multiple reflections taking measurement.

Then, it is input as the set temperature of the reflector temperature T ₂ in the radiation thermometer indicated temperature (multiple reflection temperature) T _m is the temperature control device 5 measured by a radiation thermometer 7, the reflecting plate temperature T ₂ is matching T _m The output of the heater power supply 4 is adjusted in the direction to perform. As a result, the difference ΔT between T ₂ and T _m gradually decreases and approaches 0, so that the steel plate temperature can be measured with high accuracy by a measuring method in which T _m is regarded as the steel plate temperature T ₁ . Moreover, such a steel sheet temperature T ₁ of which is measured as the match to the steel target temperature T _0, by controlling the heating device or cooling device of the steel plate, the steel plate temperature control with high accuracy can be realized.

[Embodiment 2]
FIG. 2 is a view for explaining a schematic configuration of a temperature measuring apparatus for a steel sheet according to an embodiment using the second means, and shows a cross section in the plate passing direction and a control flow.

  As shown in FIG. 2, the present embodiment is obtained by adding a steel plate temperature calculation circuit (hereinafter also simply referred to as “calculation circuit”) 8 to the configuration of the first embodiment (FIG. 1).

Until measurement of the reflection plate temperature T ₂ and a radiation thermometer indicated temperature (multiple reflection temperature) T _m, because it is exactly the same as the above embodiments it will not be described.

Below and, a reflective plate temperature T ₂ measured by a contact thermometer 6 and the radiation thermometer indicated temperature T _m, and input to the arithmetic circuit 8, which further simplifies the above equation (15) in the operation circuit 8 An approximate value T ₁ ′ of the steel plate temperature T ₁ is calculated from the equation (1).

_{T 1 '= T m + K} (T m -T 2) ... Equation (1)

  Here, the reason for using the simplified formula (1) without directly using the formula (15) is that it is complicated to obtain the steel plate temperature using a quaternary formula such as the formula (15), A normal computer requires a calculation time, so the responsiveness is inferior. On the other hand, an attempt to reduce the calculation time in order to ensure the responsiveness requires a computer capable of high-speed calculation. Therefore, a simple linear expression (1) This is to reduce the calculation time and secure the responsiveness even with a normal computer. The process of deriving equation (1) from equation (15) will be described below.

From the above equation (15),
T ₁ ⁴ = (1 + K) T _m ⁴ −KT ₂ ^{4
_{= T m 4 + K (T}} m 4 -T 2 4)
= T _m ⁴ [1 + K (1− (T ₂ / T _m ) ⁴ )]
Furthermore, if T ₂ / T _m = a,
T ₁ ⁴ = T _m ⁴ [1 + K (1-a ⁴ )]
= T _m ⁴ [1 + K (1-a) (1 + a) (1 + a ² )]
If a ≒ 1, then
T ₁ ⁴ ≈T _m ⁴ [1 + 4K (1-a)]
It becomes.

Therefore,
T ₁ ≈T _m [1 + 4K (1-a)] ^1/4
It becomes.

Here, when b≈0, (1−b) ⁴ = (1−4b + 6b ² −4b ³ + b ⁴ ) ≈ (1−4b), so that 1−b≈ (1−4b) ^1/4 Become.

Therefore,
T ₁ ≈T _m [1 + K (1-a)]
_{= T m [1 + K (} 1-T 2 / T m)]
_{= T m + K (T 2} -T m)
Thus, replacing T ₁ with T ₁ ′ yields equation (1).

Here, K is a correction coefficient composed of a function of only the emissivities ε ₁ and ε ₂ of the steel plate 1 and the reflecting plate 2 as shown in the above equation (14). Therefore, the correction coefficient K itself is will be affected by emissivity variations of the steel sheet 1 and the reflector 2, and controls to match the reflective plate temperature T ₂ to multiple reflections temperature T _m, the correction factor The error due to K is excluded, and the steel plate temperature can be measured with high accuracy.

Therefore, the correction coefficient K does not need to be set strictly, but has a certain degree of accuracy because it affects the time required for the measured steel plate temperature to reach a predetermined accuracy. For this reason, as the estimated values of the emissivities ε ₁ and ε ₂ of the steel plate 1 and the reflecting plate 2, for example, values measured separately off-line or average values in the range of fluctuations assumed from literature values are adopted. What is calculated by substituting the value into the above equation (14) may be used as the correction coefficient K.

Then, the approximate value T ₁ of the steel sheet temperature calculated by the arithmetic circuit 8 _'is inputted to the temperature control device 5 as the set temperature of the reflector plate temperature T _2, the reflecting plate temperature T ₂ is T _1' heater in a direction that matches the The output of the power supply 4 is adjusted. As a result, the difference ΔT between T ₂ and T _m gradually decreases and approaches 0, so that the steel sheet temperature can be measured with high accuracy by a measuring method in which T ₁ ′ is regarded as the steel sheet temperature T ₁ .

Although the present embodiment requires an extra arithmetic circuit 8 as compared with the first embodiment, the reflector plate temperature T ₂ is directly controlled to be close to the approximate value T ₁ ′ of the steel plate temperature. Realization of high-precision steel plate temperature measurement can be expected even earlier than the method of the first embodiment. Further, by adopting the above equation (1), which is a simple primary equation, as the equation for calculating the approximate value T ₁ ′ of the steel plate temperature, the responsiveness can be improved without using a calculator capable of high-speed calculation in the calculation circuit 8. It is possible to measure the steel plate temperature with high accuracy without sacrificing.

[Embodiment 3]
FIG. 3 is a view for explaining a schematic configuration of a temperature measuring apparatus for a steel sheet according to an embodiment using the third means, and shows a cross section in the plate passing direction and a control flow.

As shown in FIG. 3, this embodiment, in the configuration of the first embodiment (FIG. 1), the set temperature inputted to the temperature control device 5, instead of the radiation thermometer indicated temperature (multiple reflection temperature) T _m Thus, the steel plate target temperature T ₀ which is a constant value is set, and the radiation thermometer command temperature (multiple reflection temperature) T _m is immediately set to the steel plate temperature T ₁ without performing control. According to this embodiment, as can be seen from the above equation (15), if there is a difference between the multiple reflection temperature T _m and the reflector temperature T ₂ includes a measurement error in the steel sheet temperature T ₁ of However, the reflector temperature T ₂ is set to the steel plate target temperature T ₀ , and the actual steel plate temperature T ₁ itself is naturally controlled to the steel plate target temperature T ₀ , so that the multiple reflection temperature T _m is also set. As the steel plate approaches the target temperature T ₀ , the measurement error is not so large. Moreover, the reflective plate since it is not necessary to control the temperature T _2, it is also possible to set in advance reflector temperature T ₂ in the passing plate front steel plate target temperature T _0, steel sheet temperature T ₁ of the earlier Can be obtained.

[Embodiment 4]
FIG. 4 is a view for explaining a schematic configuration of a temperature measuring apparatus for a steel plate according to another embodiment using the third means, and shows a cross section in the plate passing direction and a control flow.

As shown in FIG. 4, the present embodiment is obtained by adding a steel plate temperature calculation circuit 8 to the configuration of the third embodiment (FIG. 3).

Then, the reflection plate temperature T ₂ is set to the steel plate target temperature T ₀ as in the third embodiment, and the reflection thermometer indicated temperature T _g and the reflection measured by the contact thermometer 6 as in the second embodiment. The plate temperature T ₂ is input to the arithmetic circuit 8, and the arithmetic circuit 8 calculates an approximate value T ₁ ′ of the steel plate temperature T _{1 according} to the above equation (1), and this T ₁ ′ is calculated as the steel plate temperature T ₁ . You may make it do.

Although the present embodiment requires an extra arithmetic circuit 8 as compared with the third embodiment, even if the actual steel plate temperature T ₁ is deviated from the steel plate target temperature T ₀ , the above formula (1 ) Can be used to obtain a more accurate steel plate temperature.

[Embodiment 5]
In continuous annealing equipment or hot-dip galvanizing equipment that continuously heat treats steel plate 1, heating or cooling is required to obtain different mechanical properties (strength, elongation, etc.) and plating properties (degree of alloying, etc.) for each steel type. The target temperature of the steel plate in the heat treatment process is changed stepwise (see FIG. 5). For this reason, when the present invention is applied to these facilities, it is necessary to change the reflecting plate temperature T ₂ in accordance with the change of the target temperature T ₀ of the steel plate. However, as shown in FIG. . Furthermore, if a short period of maintaining the steel sheet at the target temperature, and performing control for changing the target temperature of the next steel plate before reflecting plate temperature T ₂ reaches the target temperature of the steel sheet. As a result, the steel plate temperature T ₁ calculated using the radiation thermometer instruction temperature (multiple reflection temperature) T _m and the above equation (15) also takes time to reach the target temperature T _{0 of the} steel plate, and the target temperature T There is a case where the temperature is changed to the next steel plate target temperature without reaching _0, and the measurement accuracy of the steel plate temperature is lowered.

Therefore, as shown in FIG. 6, two reflectors 2a and 2b are installed in the furnace, temperature controllers 5a and 5b, contact-type thermometers 6a and 6b, and radiation thermometers 7a and 7b are provided, respectively, and the steel plate temperature One arithmetic circuit 8 is provided, and the reflector temperature T _2a , T _2b and the multiple reflection temperatures T _ma , T _mb measured by the reflectors 2a, 2b and radiation thermometers 7a, 7b are switched to each other to calculate the steel plate temperature. A selection circuit 9 that can be input to the circuit 8 is provided. And when passing the following steel plate 1b from which the target temperature differs from the steel plate 1a currently passing through continuously, the reflecting plate 2b different from the reflecting plate 2a currently used is previously made into the target of the steel plate 1b. It is recommended that the temperature be set so that the next steel plate 1b is passed through and switched to the reflecting plate 2b and the radiation thermometer 7b side by the selection circuit 9.

(Modification)
In the said Embodiment 1-5, although the reflecting plate 2 showed the example installed inclining with respect to the steel plate 1, you may install in parallel with respect to the steel plate 1. FIG. However, when installing in parallel, in order to ensure the frequency | count of reflection, it is necessary to lengthen the length of the reflecting plate 2 rather than the case where it installs in inclination.

  Moreover, in the said Embodiment 1-5, although the example which inclines with respect to the plate | board direction with respect to the reflecting plate was shown, it may be installed to incline with respect to the plate width direction. You may incline and install with respect to both the board width directions.

In the first to fifth embodiments, the heater 3 as the heating unit is illustrated for controlling the temperature of the reflector 2. However, in addition to the heating unit, a cooling unit such as an air cooling device or a water example device is provided. May be. Thus, the reflection plate temperature T ₂ can be more rapidly controlled.

  Moreover, in the said Embodiment 1-5, although the contact-type thermometers, such as a thermocouple, were illustrated as a thermometer for directly measuring the temperature of the reflecting plate 2, it is not limited to this, For example, in a cavity It is also possible to use a non-contact thermometer in which a thermocouple is arranged.

In the first and second embodiments, the example in which T _m or T ₁ ′ is always regarded as the steel plate temperature while the reflector temperature T ₂ is being controlled is shown, but T ₂ and T _m or T ₁ ′ are shown. Convergence control may be performed for the first time when T _m or T ₁ ′ is regarded as the steel plate temperature when the difference ΔT with respect to becomes smaller than a predetermined value (for example, 5 ° C.).

  In the fifth embodiment, the two reflectors 2a and 2b are arranged so as to face each other with the steel plate 1 interposed therebetween, but may be arranged side by side in the sheet passing direction.

  Moreover, although the example which provided two reflecting plates 2 was shown, you may make it use by providing three or more and switching sequentially.

  Moreover, although the example which each provides the radiation thermometer 7 in two reflectors 2a and 2b was shown, it is made to use it by moving one radiation thermometer 7 alternately between the two reflectors 2a and 2b. May be.

  In addition, an example in which only one steel plate temperature calculation circuit 8 is installed and the combination of the reflection plate 2 and the radiation thermometer 7 is switched by the selection circuit 9 has been shown. Of course, the reflection is performed without using the selection circuit 9. A steel plate temperature calculation circuit 8 may be installed for each combination of the plate 2 and the radiation thermometer 7.

It is a plate direction cross section and control flow figure for demonstrating schematic structure of the temperature measuring apparatus of the steel plate which concerns on Embodiment 1. FIG. FIG. 5 is a cross-sectional view in the plate passing direction and a control flow diagram for explaining a schematic configuration of a temperature measuring device for a steel plate according to a second embodiment. FIG. 5 is a cross-sectional view in a plate passing direction and a control flow diagram for explaining a schematic configuration of a temperature measuring device for a steel plate according to a third embodiment. FIG. 6 is a cross-sectional view in a plate passing direction and a control flow diagram for explaining a schematic configuration of a temperature measuring device for a steel plate according to a fourth embodiment. It is a graph which shows typically the mode of each change of a reflecting plate temperature, radiation thermometer instruction | indication temperature, and steel plate temperature when the steel plate target temperature is changed in steps. It is a sheet direction cross section and a control flow figure for demonstrating schematic structure of the temperature measuring apparatus of the steel plate which concerns on Embodiment 5. FIG.

Explanation of symbols

1: Steel plate 2: Reflecting plate 3: Heater 4: Heater power supply 5: Temperature controller 6: Thermometer (contact thermometer)
7: Radiation thermometer 8: Steel plate temperature calculation circuit 9: Selection circuit

Claims (7)

A reflector equipped with a temperature control device is placed opposite the steel plate to be measured, and the temperature of the reflector (hereinafter referred to as “reflector temperature”) T ₂ is directly measured by a thermometer different from the radiation thermometer described later. The temperature obtained by measuring the radiant energy that is reflected multiple times between the reflector and the steel plate to be measured with a radiation thermometer, and converting it to the temperature of a black body that radiates energy equivalent to this radiant energy. was a multiple reflection temperature T _m, the temperature control the reflective plate temperature T ₂ at device performs control so as to coincide with the multiple reflection temperature T _m, the multiple reflection temperature T _m of said measured steel sheet temperature ( Hereinafter, it is referred to as “steel plate temperature”). A reflector provided with a temperature control device is installed to face the measured steel plate, the reflecting plate as well as directly measured in a different thermometer and temperature T _2, infra radiation thermometer, and the reflecting plate and the object to be measured steel plate between the radiant energy to multiple reflection was measured by a radiation thermometer, a temperature obtained by converting the temperature of a black body that emits the radiant energy equivalent energy and multiple reflections temperature T _m, the steel sheet by the following formula 1 An approximate value T ₁ ′ of temperature is calculated, and the temperature control device controls the reflector plate temperature T ₂ so as to match the approximate value T ₁ ′ of the steel plate temperature, and the approximate value T _{1 of the} steel plate temperature. A method for measuring the temperature of a steel sheet, characterized in that 'is the steel sheet temperature.
Formula 1 T ₁ ′ = T _m + K (T _m −T ₂ )
Here, K is a correction coefficient based on estimated values of the emissivities of the reflector and the steel plate to be measured, which are obtained from separate measurements or literature values. A reflector provided with a temperature control device placed opposite to the measured steel plate such that said reflective plate temperature T ₂ measured directly in a separate thermometer matches the steel target temperature T ₀ and the later radiation thermometer While controlling with a temperature control device, measure the radiant energy reflected multiple times between the reflector and the steel plate to be measured with a radiation thermometer, and convert it to the temperature of a black body that radiates energy equivalent to this radiant energy. A temperature measurement method for a steel sheet, characterized in that the temperature obtained in this way is defined as a multiple reflection temperature _Tm , and the multiple reflection temperature Tm is _defined as a steel sheet temperature. A reflector provided with a temperature control device placed opposite to the measured steel plate such that said reflective plate temperature T ₂ measured directly in a separate thermometer matches the steel target temperature T ₀ and the later radiation thermometer While controlling with a temperature control device, measure the radiant energy reflected multiple times between the reflector and the steel plate to be measured with a radiation thermometer, and convert it to the temperature of a black body that radiates energy equivalent to this radiant energy. A temperature measurement method for a steel sheet, characterized in that the temperature obtained in this way is defined as a multiple reflection temperature T _m and an approximate value T ₁ ′ of the steel sheet temperature calculated by the following formula 1 is used as the steel sheet temperature.
Formula 1 T ₁ ′ = T _m + K (T _m −T ₂ )
Here, K is a correction coefficient based on estimated values of the emissivities of the reflector and the steel plate to be measured, which are obtained from separate measurements or literature values. A reflector disposed opposite to a measured steel plate, a temperature control device for controlling the temperature of the reflection plate, measuring the reflection plate temperature T ₂ directly, and another thermometer and later radiation thermometer, between the measured steel plate and the reflective plate to measure the radiant energy to multiple reflection, the radiation thermometer to be converted to multiple reflections temperature T _m is the temperature of a black body that emits the radiant energy equivalent energy, A steel plate temperature measurement circuit comprising: a steel plate temperature calculation circuit that calculates an approximate value T ₁ ′ of the steel plate temperature from the following formula 1.
Formula 1 T ₁ ′ = T _m + K (T _m −T ₂ )
Here, K is a correction coefficient based on estimated values of the emissivities of the reflector and the steel plate to be measured, which are obtained from separate measurements or literature values.   The steel plate temperature measuring device according to claim 5, wherein a plurality of combinations of the reflecting plate, the temperature control device, and the thermometer are provided so that the temperature of each reflecting plate can be controlled independently. The steel plate temperature measured by the method described in claim 3 or 4 to match the steel target temperature T _0, the temperature control method of steel plate characterized by controlling a heating device or cooling device of the steel plate.

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