JP2000121445A - Surface-temperature measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a temperature measuring apparatus by a method wherein a surface temperature in a first region is calculated by using a heat capacity, by using a flow rate of a fluid coming into contact with a second region per unit time and a heat capacity and by using the difference in a surface temperature, between the first region and the second region, which is found by the function of the temperature of the fluid. SOLUTION: An infrared sensor 2 whose visual field is a first region and an infrared sensor 3 whose visual field is a second region are installed at the upper part of a steel sheet 1. Air which flows in a pipe 5 from a blower 4 is blown from a blowoff port 8. The air is set at a preset temperature by an air heater 6 and an air cooler 7, and the air is blown at a prescribed flow rate. Its temperature is detected by a temperature sensor 9, it is fed back to a surface-temperature computing unit 10a, and the temperature of the air in the pipe 5 is controlled. A quantity of radiation infrared light detected by the sensors 2, 3 and the temperature of the air are input sequentially to the computing unit 10a. The black-body radiance, the emissivity and the stray noise influence coefficient of the steel sheet 1 as well as the emissivity and the environmental temperature of a peripheral object are given to the computing unit 10a in advance. Then, the influence of a stray noise is removed on the basis of the difference in a surface temperature between the first region and the second region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type surface temperature measuring method for measuring the surface temperature of an object to be measured in a low temperature region (for example, an object to be measured during cold rolling).

[0002]

2. Description of the Related Art As a method for measuring the surface temperature of a measurement object moving on a line, a non-contact type temperature measurement method using infrared radiation from the surface of the measurement object is known.

A surface temperature measuring device used in the non-contact type temperature measuring method described in Japanese Patent Application Laid-Open No. 5-248957 is provided with a viewing tube at a position where an infrared sensor of a radiation thermometer looks into a measuring object, A water-cooled shielding plate having a peeping opening at the center is provided at the tip of the viewing tube. In addition, a thermocouple of a thermoelectric thermometer for measuring the surface temperature of the water-cooling shielding plate is provided on the surface of the water-cooling shielding plate facing the object to be measured, and further, to measure an ambient temperature (in this case, air around the measuring position). The thermocouple of the thermocouple detects stray light noise (infrared rays emitted from objects outside this area instead of being emitted from the area where surface temperature is measured and reflected by this area and detected). It is provided in a position that is easy to do.

[0004] The infrared sensor measures the surface temperature of the measurement object by detecting infrared rays radiated from the measurement object through the opening of the water-cooled shielding plate. Further, while the surface temperature of the measurement object is being measured, the above-described thermoelectric thermometer measures the surface temperature of the water-cooled shielding plate and the ambient temperature.

[0005] The detected values of the temperature detected by the radiation thermometer and the two thermoelectric thermometers are output to an arithmetic unit. Here, the stray light noise influence function from the water cooling shield plate and the stray light noise influence function from the surrounding object determined by the function of the distance from the measurement object facing surface of the water cooling shield plate to the measurement object, and the above-described temperature detection value Calculates the influence of the stray light noise from the water-cooled shielding plate and surrounding objects in the amount of radiated infrared light detected by the radiation thermometer based on the Surface temperature measurement accuracy has been improved.

[0006]

When measuring the surface temperature by detecting the amount of infrared light radiated from the surface of a measuring object (for example, a measuring object during cold rolling) in a low temperature region,
Since the amount of radiated infrared rays from the object to be measured is small, the influence of stray light noise from the water-cooled shielding plate and surrounding objects becomes significant in the above-mentioned non-contact type temperature measuring method. Taking into account the effect of this stray light noise, in order to improve the measurement accuracy of the surface temperature of the object to be measured, the distance from the center of the peephole to the outer periphery of the surface of the water-cooled shielding plate facing the object to be measured should be determined by the water-cooled shielding plate It is known that the distance may be increased with respect to the distance from the measurement object facing surface to the measurement object. However, a surface temperature measuring device provided with such a large radiation thermometer having such a water-cooled shielding plate is expensive and is difficult to install when the installation space is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and based on the amount of radiated infrared light from the surface temperature measurement area of a measurement object and a reference area in contact with a fluid near this area. By calculating the surface temperature based on the result of removing the influence of the stray light noise of the light amount by calculation and the heat capacity of the surface temperature measurement area, the flow rate and the heat capacity of the fluid contacting the reference area per unit time, An object of the present invention is to provide a surface temperature measuring method capable of miniaturizing a surface temperature measuring device for measuring a surface temperature of a measurement object in a low temperature region.

Further, when calculating the surface temperature, the heat capacity of the surface temperature measurement area, the flow rate of the fluid in contact with the reference area per unit time, and the heat capacity can be obtained by using a proportional constant obtained empirically through the measurement of the surface temperature. Another object of the present invention is to provide a surface temperature measuring method capable of calculating the surface temperature even if the value is unknown.

Further, by performing calculations taking into account the moving speed of the object to be measured when calculating the surface temperature based on the calculation results, the surface temperature measurement method described above can be performed with higher accuracy. It is another object to provide a temperature measurement method.

[0010]

According to a first aspect of the present invention, there is provided a method of measuring a surface temperature, comprising: bringing a fluid controlled at a predetermined temperature into contact with a first region for measuring the surface temperature of an object to be measured; By changing the surface temperature of the second region, the amount of radiated infrared light from the first region and the amount of radiated infrared light from the second region are respectively detected, and the influence of stray light noise on the amount of radiated infrared light from both regions is detected. A subtraction operation is performed by subtracting the amount of infrared radiation from the second region from the amount of infrared radiation emitted from the first region to obtain an arithmetic expression for obtaining the surface temperature of the first region. In the surface temperature measuring method for calculating the surface temperature of the first region and the second region, the heat capacity of the first region, the flow rate and the heat capacity of the fluid contacting the second region per unit time, and the temperature of the fluid are determined. Territory And calculating the surface temperature of the first region is given to the mathematical expression of the surface temperature difference between the.

According to a second aspect of the present invention, there is provided a method for measuring a surface temperature of a target object, comprising the steps of: bringing a fluid controlled at a predetermined temperature into contact with a first area for measuring a surface temperature of an object to be measured;
The surface temperature of the area is changed to detect the amount of radiated infrared light from the first area and the amount of radiated infrared light from the second area, respectively. An arithmetic expression for obtaining the surface temperature of the first region by performing an operation of subtracting the amount of infrared infrared radiation from the second region from the amount of infrared radiation emitted from the second region to obtain the surface temperature of the first region is obtained based on the arithmetic expression. In the surface temperature measuring method to be calculated, the first area is determined based on the difference between the amount of radiated infrared light and the temperature of the fluid when the absolute value of the difference between the amounts of radiated infrared light between the first area and the second area is equal to or less than a predetermined value. Is characterized in that the surface temperature is calculated.

According to a third aspect of the present invention, there is provided a method for measuring a surface temperature of a moving object to be measured, the method comprising: bringing a fluid controlled at a predetermined temperature into contact with a first region for measuring the surface temperature of a moving measuring object; The surface temperature of the area is changed to detect the amount of radiated infrared light from the first area and the amount of radiated infrared light from the second area, respectively. An arithmetic expression for obtaining the surface temperature of the first region by performing an operation of subtracting the amount of infrared infrared radiation from the second region from the amount of infrared radiation emitted from the second region to obtain the surface temperature of the first region is obtained based on the arithmetic expression. In the calculated surface temperature measuring method, the moving speed of the measurement object is detected, and the moving speed, the heat capacity of the first area, the flow rate and the heat capacity of the fluid that contacts the second area per unit time,
In addition, a surface temperature difference between the first region and the second region obtained by a function of the temperature of the fluid is given to the arithmetic expression to calculate a surface temperature of the first region.

The amount of radiated infrared light from this area and the amount of radiated infrared light due to stray light noise from outside this area of the measurement object whose surface temperature is Ts (unknown) in the first area for measuring the surface temperature of the object to be measured. Is given by the following equation (1).

L = εs · Lb (Ts) + α (1−εs) · εw · Lb (Tw) (1) where Lb (Ts) is the blackbody radiance of the object at the temperature Ts, and εs is the object to be measured. E represents the emissivity of the object, α represents the stray light noise influence coefficient, εw represents the emissivity (average value) of the surrounding object, and Tw represents the surrounding environmental temperature.

In equation (1), the first term on the right-hand side represents the amount of radiated infrared light from the first region, and the second term on the right-hand side represents the amount of radiated infrared light from areas other than this region due to stray light noise. When a fluid controlled at a predetermined temperature is brought into contact with a second region (a reference region of the surface temperature) near the first region, the surface temperature of this region changes by Δt. The sum Lt of the amount of radiated infrared light and the amount of radiated infrared light due to stray light noise from areas other than this region is expressed by the following equation (2).

Lt = εs · Lb (Ts + Δt) + α (1−εs) · εw · Lb (Tw) (2)

In equation (1), the amount of radiated infrared light due to stray light noise from regions other than the first region and the amount of radiated infrared light due to stray light noise from regions other than the second region in formula (2) are equal. By subtracting equation (2),
The amount of radiated infrared light due to stray light noise can be eliminated, and the following equation (3) is obtained.

ΔL = L−Lt = εs · {Lb (Ts) −Lb (Ts + Δt)} (3) where ΔL is a difference between the amounts of radiated infrared rays between the first region and the second region.

The surface temperature difference Δ between the first region and the second region
t is determined by the temperature and heat capacity of the first region, the flow rate and heat capacity of the above-mentioned fluid that comes into contact with the second region per unit time, and the temperature of this fluid, and recursively calculated by using these to calculate the surface temperature. It is determined by the obtained function F as shown in the following equation (4).

Δt = F (Ts, Cs, 1, Ca, Ta,) (4) where Cs is the heat capacity of the first region, and 1 is the second region per unit time.
The flow rate of the above-mentioned fluid in contact with the region, Ca represents its heat capacity, and Ta represents its temperature.

From equations (3) and (4), ΔL can be expressed as shown in equation (5) below.

ΔL = εs · [Lb (Ts) −Lb {Ts + F (Ts, Cs, 1, Ca, Ta,)}] (5)

The above-mentioned fluid temperature is controlled to Ta, the above-mentioned difference in the amount of emitted infrared rays ΔL is detected and given to equation (5), and the surface temperature Ts of the first region is calculated from equation (5). Is performed, the surface temperature of the measurement object is calculated. The above is the surface temperature measuring method according to the first invention.

If the temperature of the fluid in contact with the second region is substantially the same as the surface temperature of the first region and the difference between the surface temperatures of the first region and the second region is very small, the first region and the second region may be separated. The difference ΔL in the amount of radiated infrared light between the two regions becomes small. In the surface temperature measuring method according to the second invention, the temperature of the above-described fluid is variously controlled without using the heat capacity of the first area, the flow rate and the heat capacity of the above-mentioned fluid that comes into contact with the second area per unit time, and the radiation is controlled. The surface temperature of the first region is calculated from the radiated infrared light amount difference ΔL when the absolute value of the infrared light amount difference ΔL is equal to or less than a predetermined value (small amount) and the fluid temperature at this time. Here, the above-mentioned surface temperature difference Δt is expressed by the following equation (6) by the product of the difference between the surface temperature of the first region and the temperature of the above-mentioned fluid, and the proportionality constant empirically obtained through the surface temperature measurement. Determined as follows.

Δt = −K (Ts−Ta) (6) where K is a proportional constant empirically obtained through surface temperature measurement.

By giving this in place of the function of equation (4), the above-mentioned difference in radiated infrared light quantity ΔL can be expressed as shown in the following equation (7).

ΔL = εs · [Lb (Ts) −Lb {Ts−K (Ts−Ta)}] (7)

By controlling the temperature Ta of the fluid described above, the absolute value of the radiant infrared light quantity difference ΔL is a predetermined value (determined in consideration of an allowable range of error when calculating the surface temperature of the first area).
From the equation (7), the surface temperature Ts of the first region is obtained when
The surface temperature of the measurement object is calculated by performing the calculation of The above is the surface temperature measuring method according to the second invention.

When detecting the amount of infrared radiation radiated from the surface of the object to be measured, there is a difference between the amount of infrared light actually radiated from the surface of the object to be measured and the amount of infrared light to be detected. Is known to increase when moving at high speed. In this case, high precision temperature measurement accuracy cannot be obtained unless the moving speed of the measurement target is taken into account when calculating the surface temperature of the measurement target based on the detected amount of radiation infrared radiation.

Therefore, in the surface temperature measuring method according to the third invention, the surface temperature difference Δt between the first region and the second region is set so as to obtain high temperature measurement accuracy even when the measuring object moves at high speed. The following equation (8) is used in which the moving speed Vs of the measurement object is added to the element of the function that determines

Δt = F (Ts, Cs, 1, Ca, Ta, Vs) (8)

The following equation (9) is obtained by giving equation (8) instead of function F in equation (5).

ΔL = εs · [Lb (Ts) −Lb {Ts + F (Ts, Cs, 1, Ca, Ta, Vs)}] (9)

The temperature of the above-mentioned fluid is controlled to Ta, and the above-mentioned difference in the amount of radiated infrared rays ΔL and the moving speed V of the measuring object are obtained.
s is detected, and these are given to equation (9) to calculate the surface temperature Ts of the first region, thereby calculating the surface temperature of the measurement object. The above is the surface temperature measuring method according to the third invention.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments.

Embodiment 1 FIG. 1 is a schematic diagram showing an apparatus used when the surface temperature measuring method according to the present invention is performed on a steel sheet during cold rolling. In the figure, reference numeral 1 denotes a steel plate as an object to be measured. Above the steel plate 1, an infrared sensor 2 having a first area for measuring the surface temperature as a visual field,
An infrared sensor 3 having a field of view in a second area (a reference area for surface temperature) near the area is provided. Air blown from the blower 4 and flowing through the pipe 5 is blown from the air blowing port 8 to the second area. The temperature of this air is
While flowing through the pipe 5, the air heater 6 and the air cooler 7 control the temperature to a preset temperature (determined by the degree of cooling of the steel plate 1), and the amount of air blown per unit time to the second area Is controlled to a preset flow rate by flow rate control means (not shown). A temperature sensor 9 for detecting the temperature of the air blown to the second area is provided near the air blowing port 8.

The air temperature detected by the temperature sensor 9 is fed back to the surface temperature calculator 10a, and the air heater 6
The temperature of the air flowing through the pipe 5 is controlled by the air cooler 7. Further, the amount of radiated infrared rays detected by the infrared sensors 2 and 3 and the air temperature detected by the temperature sensor 9 are sequentially input to the surface temperature calculator 10a. In the present embodiment, air is used as a fluid for changing the surface temperature of the second region. However, this may be a liquid such as water.

The surface temperature calculator 10a stores the blackbody radiance Lb, the emissivity εs, and the stray light noise influence coefficient α of the steel plate 1, the emissivity εw (average value) of the object around the steel plate 1, and the surrounding environmental temperature. Tw (temperature in consideration of the environment for measuring the surface temperature) is given in advance, and the following expressions (1) and (2) are given.
L = εs · Lb (Ts) + α (1−εs) · εw · Lb (Tw) (1) Lt = εs · Lb (Ts + Δt) + α (1−εs) · εw · Lb (Tw) ( 2) is set. Δt in the equation (2) is the surface temperature difference between the first region and the second region, which is the surface temperature Ts and heat capacity Cs of the first region, and the flow rate l of air blown to the second region per unit time. And the heat capacity Ca and the air temperature Ta are defined by the function shown in the equation (4). Δt = F (Ts, Cs, 1, Ca, Ta,) (4)

The surface temperature calculator 10a gives the amount of radiated infrared rays detected by the infrared sensors 2 and 3 to L in equation (1) and Lt in equation (2), and subtracts equation (2) from equation (1). Then, an equation (5) for calculating the surface temperature of the first region in which the influence of the stray light noise in the amount of infrared radiation emitted from the first region and the second region is removed is obtained. ΔL = εs · [Lb (Ts) −Lb {Ts + F (Ts, Cs, 1, Ca, Ta,)}] (5) Air temperature Ta detected by the temperature sensor 9 according to the equation (5).
To calculate the surface temperature of the first region. The calculated surface temperature Ts of the first region is output to the temperature display unit 11 and displayed.

Embodiment 2 FIG. 2 is a schematic diagram showing an apparatus used when the surface temperature measuring method according to the present invention is applied to a steel sheet during cold rolling.

Surface temperature calculator 10 used in this embodiment
In b, the product of the difference between the surface temperature Ts of the first region and the above-described air temperature Ta and the proportional constant K = 0.5 empirically obtained through the measurement of the surface temperature is determined as shown in Expression (6). The surface temperature difference Δ between the first region and the second region by the function
t is defined. Δt = −0.5 (Ts−Ta) (6)

The surface temperature calculator 10b calculates the surface temperature of the first region obtained by removing the stray light noise before the air is blown as described above, using the following equation (7): ΔL = εs · [Lb ( Ts) −Lb {Ts−0.5 (Ts−Ta)}] When the radiation infrared light quantity difference ΔL (L−Lt) in (7) is positive, an enable signal is transmitted to the air heater 6, and when negative, the enable signal is enabled. The signal is transmitted to the air cooler 7. The air heater 6 or the air cooler 7 heats or cools the air flowing through the pipe 5 during a period when the enable signal is given.

During this period, the radiation infrared light amount difference ΔL is calculated as described above, and the absolute value of the difference is equal to or less than a predetermined value (determined in consideration of an allowable range of error when calculating the surface temperature of the first region). In some cases, the transmission of the enable signal to the air heater 6 or the air cooler 7 is stopped, and the radiated infrared light amount difference ΔL and the air temperature Ta detected by the temperature sensor 9 at this time are given to the equation (7). Then, the surface temperature of the first region is calculated. The surface temperature of the first region thus calculated is output to the temperature display unit 11 and displayed.

When the calculated absolute value of the infrared ray difference ΔL exceeds the above-mentioned value, the transmission of the enable signal to the air heater 6 or the air cooler 7 is continued.
The rest is the same as the first embodiment of the present invention, and the description is omitted.

Embodiment 3 FIG. 3 is a schematic view showing an apparatus used when the surface temperature measuring method according to the present invention is performed on a steel sheet that is being cold-rolled and that moves in the longitudinal direction.

In the present embodiment, a surface temperature calculator 10c is provided instead of the surface temperature calculator 10a used in the first embodiment. In addition, a speed detector 13 using a rotary encoder is provided in connection with the roll 12, and detects the moving speed of the steel plate 1 from the rotation speed of the roll 12 that guides the steel plate 1.

In the surface temperature calculator 10c, the moving speed Vs of the steel sheet 1, the surface temperature Ts and heat capacity Cs of the first area, the flow rate l and heat capacity Ca of air contacting the second area per unit time, and the The surface temperature difference Δt between the first region and the second region is defined by a function determined by the temperature Ta as shown in Expression (8). Δt = F (Ts, Cs, 1, Ca, Ta, Vs) (8)

The surface temperature calculator 10c performs an operation for removing stray light noise as described above, and obtains Expression (9) for obtaining the surface temperature of the first area. ΔL = εs · [Lb (Ts) −Lb {Ts + F (Ts, Cs, 1, Ca, Ta, Vs)}] (9) The speed at the time of calculating the surface temperature of the first region from equation (9) The moving speed of the steel plate 1 detected by the detector 13 is given.
The surface temperature of the first region calculated in this manner is indicated by the temperature display unit 1.
1 and displayed. The rest is the same as the first embodiment of the present invention, and the description is omitted.

[0049]

As described above in detail, according to the surface temperature measuring method according to the present invention, the first area for measuring the surface temperature of the object to be measured and the second area in which the fluid near this area is brought into contact.
The influence of stray light noise in the amount of radiated infrared light detected from the first area is removed by calculation based on the amount of radiated infrared light from the area, and the heat capacity of the first area is sprayed onto the second area per unit time. The surface temperature of the first region can be calculated based on the flow rate and heat capacity of the supplied air and the air temperature. Therefore, it is not necessary to provide a water-cooling shielding plate for removing stray light noise in a device for detecting the amount of infrared radiation emitted from the measurement object in order to calculate the surface temperature of the measurement object in the low temperature region. The size of the temperature measuring device can be reduced.

Further, when calculating the surface temperature of the first area, the proportional capacity empirically obtained through the measurement of the surface temperature is used, so that the heat capacity of the first area and the air blown to the second area per unit time are obtained. It is possible to calculate the surface temperature of the first region even when the flow rate and heat capacity of the first region are unknown.

Further, by calculating the surface temperature of the first area in consideration of the moving speed of the object to be measured, it becomes possible to calculate the surface temperature of the first area with higher accuracy. The present invention has excellent effects.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an apparatus used when a surface temperature measuring method according to the present invention is performed on a steel sheet during cold rolling.

FIG. 2 is a schematic view showing an apparatus used when the surface temperature measuring method according to the present invention is performed on a steel sheet during cold rolling.

FIG. 3 is a schematic view showing an apparatus used when the surface temperature measuring method according to the present invention is performed on a steel sheet that is being cold-rolled and moves in a longitudinal direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate 2, 3 Infrared sensor 4 Blower 5 Piping 6 Air heater 7 Air cooler 8 Air blowing port 9 Temperature sensor 10a, 10b, 10c Surface temperature calculator 11 Temperature display part 12 Roll 13 Speed detector

Claims (3)

[Claims] 1. A first region in which a fluid controlled at a predetermined temperature is brought into contact with a first region for measuring a surface temperature of an object to be measured, and a surface temperature of a second region contacted with the fluid is changed. The amount of radiated infrared light from the first region and the amount of radiated infrared light from the second region are detected, and the amount of the radiated infrared light from both regions is affected by stray light noise. In the method for measuring the surface temperature of the first area based on the arithmetic expression for calculating the surface temperature of the first area by performing the operation of removing the infrared ray by reducing the amount of the radiated infrared light, and calculating the surface temperature of the first area based on the arithmetic equation, The heat capacity of the fluid, the flow rate and heat capacity of the fluid that contacts the second area per unit time, and the surface temperature difference between the first area and the second area obtained by a function of the temperature of the fluid are given to the arithmetic expression to obtain the first equation. Area surface A method for measuring a surface temperature, comprising calculating a temperature. 2. The method according to claim 1, further comprising: bringing a fluid controlled at a predetermined temperature into contact with the first area for measuring the surface temperature of the object to be measured, and changing the surface temperature of the second area contacted with the fluid, The amount of radiated infrared light from the first region and the amount of radiated infrared light from the second region are detected, and the amount of the radiated infrared light from both regions is affected by stray light noise. In the method for measuring the surface temperature of the first area based on the arithmetic expression for calculating the surface temperature of the first area by performing the operation of removing the infrared ray by reducing the amount of the radiated infrared light, and calculating the surface temperature of the first area based on the arithmetic equation, And the second
Measuring the surface temperature of the first area based on the difference between the amount of the emitted infrared light and the temperature of the fluid when the absolute value of the difference between the amounts of the emitted infrared light and the area is equal to or less than a predetermined value; Method. 3. A method in which a fluid controlled at a predetermined temperature is brought into contact with a first area for measuring the surface temperature of a moving measuring object, and the surface temperature of a second area contacted with the fluid is changed. The amount of radiated infrared light from one region and the amount of radiated infrared light from the second region are detected, respectively, and the influence of stray light noise in the amount of radiated infrared light from both regions is determined from the amount of radiated infrared light from the first region to the second region. An arithmetic expression for calculating the surface temperature of the first region by performing an operation of removing by reducing the amount of radiated infrared light from the device, and calculating the surface temperature of the first region based on the arithmetic expression, Detecting the moving speed of the measurement object, the moving speed, the heat capacity of the first area, the flow rate and heat capacity of the fluid that contacts the second area per unit time, and the first area obtained by a function of the temperature of the fluid. No. A surface temperature measuring method, wherein a surface temperature difference between two regions is given to the arithmetic expression to calculate a surface temperature of the first region.