JPH05126642A - Radiation temperature measuring method and device thereof - Google Patents

Abstract

PURPOSE:To measure the temperature of a metal in no contact with high precision by automatically correcting the error due to the effect of the fluctuation of the emissivity during the growth of a metal oxide film. CONSTITUTION:The relation between the ratio X between the respective products of spectral radiation energy E1, E2 to the exponents lambda1, lambda2 at two different wavelength bands lambda1, lambda2 and the emissivity epsilon2 is determined in advance, and the spectral radiation energy E1, E2 of an object W at different wavelengths lambda1, lambda2 are measured and detected. The ratio X between wavelengths lambda1, lambda2 of the spectral radiation energy E1, E2 is obtained based on the detected spectral radiation energy E1, E2. The emissivity epsilon2 corresponding to the ratio X between the wavelengths lambda1, lambda2 of the obtained spectral radiation energy E1, E2 is obtained from the preset relation, and the temperature T of the object W is calculated with the emissivity epsilon2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention automatically corrects an error due to a change in emissivity on the basis of spectral radiant energy emitted from a metal having a low emissivity as a temperature-measuring object to measure the temperature of the temperature-measuring object. The present invention relates to a radiation temperature measuring method for measuring and a device therefor.

[0002]

2. Description of the Related Art For example, when measuring the temperature of a metal having a low emissivity as a temperature-measuring object, a two-color temperature measurement can be performed continuously by taking a ratio of spectral radiant energies at two different wavelengths. Conventional radiation thermometers have been used. By the way, when a metal having a low emissivity is heat-treated to form an oxide film, the emissivity of the metal fluctuates greatly as the oxide film grows, and thus radiation measurement may be difficult.

As a countermeasure against this, Japanese Patent Laid-Open No. 61-21092
As disclosed in Japanese Patent Publication No. 1, a radiation source that radiates radiant energy to a temperature-measuring body, and radiant energy radiated to the temperature-measuring body from the radiation source between the radiation source and the temperature-measuring body in a stepwise manner. A shutter means that is variable is provided, and by this shutter means, among the output signals of the radiation detector in three different states, the ratio of the contribution ratio, which is the ratio of the difference between any two signals, and the difference in the contribution ratio are An active radiation thermometer has been proposed which obtains the emissivity of a temperature-measured body based on a predetermined relationship and obtains the temperature of the temperature-measured body from this emissivity.

[0004]

However, in the active radiation thermometer described above, in addition to the radiation detector forming the main body of the radiation thermometer, a separate heat source and shutter means are indispensable. However, there is a problem that the entire device is complicated and large in size.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object thereof is to reduce the size of the device with a simple structure, and particularly to change the emissivity during the growth of the metal oxide film. An object of the present invention is to provide a radiation temperature measuring method and a device therefor capable of automatically correcting the error due to the influence of the above to perform metal temperature measurement with high accuracy in a non-contact manner.

[0006]

In order to achieve the above object, the radiant temperature measuring method according to the present invention is such that the ratio of the power of the wavelength of each spectral radiant energy and the emissivity in two predetermined wavelength bands different from each other. The emissivity is calculated from the measured spectral radiant energy based on the relationship with and the temperature is calculated using the calculated emissivity.
Further, a plurality of calibration curves of emissivity with respect to the power ratio of each spectral radiant energy is determined in advance, and the calibration curve is selected according to usage conditions. At this time, the calibration curve may be integrated into a calibration curve in the low emissivity region and two calibration curves in the medium and high emissivity regions. Further, with respect to the calibration curve in the low emissivity region, the lower limit value of the power ratio of each spectral radiant energy can be set. Furthermore, when the value of the power ratio of each spectral radiant energy is equal to or more than the lower limit value, the temperature value, the emissivity value, or both values for each calibration curve are output. When the value of the ratio of the power of each spectral radiant energy rises with the passage of time, select the calibration curve in the low emissivity region, and after the value of the ratio of the power of each spectral radiant energy starts to decrease. Selects a calibration curve for medium and high emissivity regions. Further, the radiation thermometer according to the present invention includes detection means for detecting the respective spectral radiant energies of the temperature-measured body in two wavelength bands different from each other, and each of the spectral radiant energies from the detecting means. Ratio calculation means for calculating the ratio of the power of the wavelength of the spectral radiant energy,
Storage means for storing the data indicating the relationship between the ratio of the power of the wavelength of each spectral radiation energy and the emissivity, and the storage of the ratio of the power of the wavelength of each spectral radiation energy calculated by the ratio calculation means It is characterized by comprising collating means for collating with the data of the means to obtain a corresponding emissivity, and temperature computing means for computing the temperature of the temperature-measured body based on the emissivity obtained by the collating means.

[0007]

[Function] The spectral radiant energy of the temperature-measuring object is detected by establishing the relationship between the emissivity and the ratio of the power of the wavelength of each spectral radiant energy in two different wavelength bands.
The ratio of the power of the wavelength of each spectral radiant energy is calculated based on the detected spectral radiant energy, and the ratio of the power of the wavelength of each spectral radiant energy and the corresponding emissivity is calculated from a predetermined relationship. The temperature of the temperature-measured body is calculated using the rate.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation temperature measuring method and apparatus according to this embodiment have a spectral power ratio and a spectral emissivity (hereinafter, simply referred to as emissivity) of respective spectral radiant energies described below.
The emissivity is obtained from the spectral radiant energy actually measured based on the calibration curve approximated from the relationship with, and the temperature of the temperature-measured body is measured by automatically correcting the error due to the influence of the change in the emissivity. In general, outputs E1 and E2 for wavelengths λ1 and λ2 after correcting the radiation intensity of a black body, the spectral transmittance of an optical system, the spectral sensitivity of an element, and the like are expressed by the following (1) from the Wien equation.
It is represented by a formula. Where ε1 is the emissivity at the wavelength λ1,
ε2 is the emissivity at the wavelength λ2, and C2 is the second constant of radiation (0.014388 m · K).

[Equation 1] From the above equation (1), the following equation (2) is established.

[Equation 2] From this, the ratio X of the powers of the wavelengths of the respective spectral radiant energies is expressed by a function of only the emissivities ε1 and ε2, and the temperature value T
It turns out that the amount does not depend on.

On the other hand, the behavior of the emissivity during the growth of the metal oxide film can be explained as a light interference phenomenon. That is, when light is incident on a metal, this light is reflected on the surface of the oxide film grown on the metal, and part of the light is transmitted through the oxide film and reflected on the surface of the metal. ,
A light interference phenomenon occurs in the oxide film. This light interference phenomenon sways intricately as the oxide film grows, but is uniquely determined by the refractive index and extinction coefficient of each of the metal and the oxide film.

From the above, the relation between the ratio X of the powers of the wavelengths of the respective spectral radiant energies and the emissivities ε1 and ε2 can be obtained by simulating the oxidation of iron and expressed by the characteristic graph shown in FIG. The wavelength is λ1 =
It is set to 1.76 μm and λ2 = 2.06 μm.

Therefore, from this result, in general, the emissivity ε
Since 1 and ε2 do not have a monovalent function with respect to the ratio X of the powers of the wavelengths of the respective spectral radiant energies and may take a multivalued value, the value of the ratio X of the powers of the wavelengths of the respective spectral radiant energy. It is possible to draw a plurality of calibration curves showing an approximate expression of emissivity ε1 and ε2 with respect to.

Therefore, in the radiation temperature measuring method of this embodiment, when a plurality of calibration curves are drawn along the characteristic line, one calibration curve can be selected from among the plurality of calibration curves by a steel process or the like. However, once the operating conditions are determined, the thickness of the oxide film does not change significantly, so one calibration curve is selected according to the operating conditions of the process, and the temperature of the temperature-measured body is measured.

On the other hand, in radiation measurement, the temperature measurement error increases as the emissivity region becomes lower, but in the region where the emissivity is large, conversely, the emissivity evaluation error has a great influence on the temperature measurement error. It is known not to give. Therefore, in the radiation temperature measuring method of this embodiment, as shown in FIG. 2, a plurality of calibration curves are combined into two calibration curves L1 and L2 in the low emissivity region and the middle and high emissivity regions, and 500 ° is gathered. Near C ±
Since the temperature can be measured within 10 ° C and the number of calibration curves is small, it is easy to create and select the calibration curve, the load of software and hardware is reduced, and the measurement work can be facilitated.

By the way, in the characteristic graph of FIG. 2, as the oxide film grows, the value of the ratio X of the powers of the wavelengths of the respective spectral radiant energies increases with a certain value X1 as the starting point, and there is the value of the emissivity. When the value exceeds X2, it starts to decrease. From this, the calibration curve L1 in the low emissivity region does not become less than the value X1 of the ratio X of the powers of the wavelengths of the respective spectral radiant energies when there is no oxide film. Then, the calibration curve L1 in the low emissivity region
Is set to the lower limit value UL (= X1) of the ratio X of the power of the wavelength of each spectral radiant energy.

When the value of the power-of-wavelength ratio X of each spectral radiant energy is less than or equal to the lower limit value UL, the calibration curve L2 in the medium / high emissivity region is uniquely selected. Also,
When the value of the ratio X of the power of the wavelength of each spectral radiant energy is equal to or more than the lower limit value UL, the calculation results by both calibration curves L1 and L2 are output, and the operating conditions etc. are considered from the respective temperature values or emissivity. Then, either calibration curve L1 (or L
The output according to 2) is used.

Further, in a batch process such as metal quenching, the oxide film usually moves in an increasing direction, so the value of the ratio X of the powers of the wavelengths of the respective spectral radiant energies after the start of the heat treatment increases. In the region, the calibration curve L1 in the low emissivity region is selected. Further, after the value of the power-of-wavelength ratio X of each spectral radiant energy starts to decrease, the calibration curve L2 in the medium / high emissivity region is selected.

Here, the schematic construction of the radiation thermometer will be described with reference to FIG. The radiation temperature measuring device is provided with a detection means 2, a storage means 3, a ratio calculation means 4, a collation means 5, a temperature calculation means 6 and an output means 7 in a radiation detector 1 which constitutes a casing body. The storage unit 3, the ratio calculation unit 4, the matching unit 5, the temperature calculation unit 6, and the like are configured by a microcomputer or the like.

The detecting means 2 is composed of a rotating sector 20 having a filter having a predetermined transmission wavelength, a detecting element 21 and the like, which are different from each other as a temperature-measuring object W such as metal such as iron, aluminum or brass. Two wavelength bands λ
The spectral radiant energy at 1, λ2 is detected.
The storage means 3 stores the wavelengths of the respective spectral radiant energies, where E1 and E2 are the spectral radiant energies and the emissivity is ε1 and ε2, respectively, at two different wavelengths λ1 and λ2 which are previously calculated or measured. Power ratio X
And the emissivity ε1 and ε2, or data indicating this relationship, as shown in FIG.
1 and L2 are approximated and stored.

The ratio calculating means 4 calculates the ratio X of the powers of the wavelengths of the respective spectral radiant energies based on the spectral radiant energies E1 and E2 in the two different wavelength bands λ1 and λ2 detected by the detecting means 2 and collates them. Inputting means 5. The matching means 5 selects a calibration curve in which the emissivity ε2 (or ε1) corresponding to the power-of-wavelength ratio X of each spectral radiation energy calculated by the ratio calculation means 4 based on the data stored in the storage means 3 is selected. L1 (or L2)
It is obtained from the above and input to the temperature calculation means 6 and the output means 7. The temperature calculation means 6 calculates the temperature of the temperature-measured body W based on the emissivity ε2 obtained by the collation means 5 and outputs it.
Are typing in. The output means 7 outputs, for example, the value of the emissivity ε2 obtained by the collation means 5 and the value of the temperature T of the temperature-measured body W obtained by the temperature calculation means 6, for example.

Therefore, according to the radiation thermometer of this embodiment, the spectral radiant energy detected by the temperature-measuring object W is a power of the wavelength of the spectral radiant energy of each of two different wavelengths stored in advance. Ratio X and emissivity ε1,
Since the emissivity is determined and the temperature is calculated by collating with the relationship with ε2, a heat source and a shutter means having a separate configuration as in the conventional case are not required, and the apparatus can be downsized with a simple configuration. ..

In order to measure the temperature of the object to be measured based on the above-described measurement principle, first, as shown in FIG. 2, the spectral radiant energies at two different wavelengths λ1 and λ2 are E1, respectively. E2, emissivity is ε2
Then, the relationship between the ratio X of the power of the wavelength of each spectral radiant energy and the emissivity ε2 is calculated in advance or actually measured, and the data showing this relationship is calculated in the low emissivity region and the medium / high emissivity region. It is approximated by the calibration curves L1 and L2 of the book. Next, the spectral radiant energies E1 and E2 at the two wavelengths λ1 and λ2 are detected by the detection unit 2 of the radiation detector 1. Next, based on the detected spectral radiant energies E1 and E2, the ratio X of the powers of the wavelengths of the spectral radiant energies is obtained. Further, the emissivity ε2 is obtained by collating the obtained power ratio X of the spectral radiant energy with respect to the wavelength with the calibration curve L1 (or L2).
Then, the calculated emissivity is substituted into the equation (1) to calculate the temperature of the temperature-measured body W.

Incidentally, as the relationship between the ratio X of the powers of the wavelengths of the spectral radiant energy of each of two different wavelengths and the emissivity ε1 and ε2, only the emissivity ε2 is shown in the embodiment, but the emissivity ε1 is also shown. Similarly, the emissivity may be determined by presetting a relationship with the ratio X of the powers of wavelengths of the spectral radiant energy of each of two different wavelengths.

[0023]

As described above, according to the first aspect of the present invention.
According to the radiation temperature measuring method described above, the spectral radiation measured from the temperature-measuring object based on the relationship between the emissivity and the ratio of the power of the wavelength of each spectral radiation energy in two different predetermined wavelength bands. Since the emissivity is calculated from the energy and the temperature of the temperature-measuring object is calculated using this emissivity, the error due to the fluctuation of the emissivity during the growth of the metal oxide film is automatically corrected. The metal temperature can be measured with high accuracy without contact. Further, according to the radiation temperature measuring method of claim 2 of the present invention, in a steel process or the like,
If the operating conditions are determined, the thickness of the oxide film will not change significantly, so data showing the relationship between the ratio of the power of the wavelength of each spectral radiant energy and the emissivity in two different wavelength bands, It is possible to measure the temperature of the temperature-measuring object by replacing the plural calibration curves showing the emissivity with respect to the power ratio of each spectral radiant energy and selecting the calibration curve according to the operating conditions of the process. Furthermore, according to the radiation temperature measuring method of claim 3 of the present invention, the calibration curve is aggregated into the calibration curve of the low emissivity region and the two calibration curves of the medium and high emissivity regions. Can be easily selected, and measurement work can be facilitated. Further, according to the radiation temperature measuring method of claim 4 of the present invention, the lower limit value of the ratio of the powers of the respective spectral radiant energies is set with respect to the calibration curve in the low emissivity region. If less than
The calibration curve can be uniquely determined. Further, according to the radiation temperature measuring method of claim 5 of the present invention, when the value of the ratio of the powers of the respective spectral radiant energies is equal to or more than the lower limit value, the temperature value, the emissivity value or both for each calibration curve is obtained. , The optimum output can be obtained from each temperature value or emissivity in consideration of operating conditions and the like.
According to the radiation temperature measuring method of claim 6 of the present invention,
When the value of the ratio of the power of each spectral radiant energy rises with the passage of time, select the calibration curve in the low emissivity region, and after the value of the ratio of the power of each spectral radiant energy starts to decrease,・ Since the calibration curve in the high emissivity region is selected, the optimum calibration can be performed by increasing or decreasing the value of the ratio of the power of each spectral radiant energy with the growth of the oxide film formed on the metal to be measured. The line is uniquely selected, and the temperature of the object to be measured can be measured. Further, according to the radiation thermometer of claim 7 of the present invention, the measured temperature measured from data showing the relationship between the ratio of the power of the wavelength of each spectral radiation energy in two different wavelength bands and the emissivity. Since the emissivity is determined based on the spectral radiant energy of the warm body and the temperature of the temperature-measured body is calculated based on this determined emissivity, there is no need for a heat source or shutter means with a different configuration as in the past. Thus, the device can be downsized with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a radiation temperature measuring device to which a radiation temperature measuring method according to the present invention is applied.

FIG. 2 is a characteristic graph showing the relationship between the ratio of the power of wavelength of each spectral radiant energy and the spectral emissivity.

[Explanation of symbols]

2 ... Detection part, 3 ... Storage part, 4 ... Ratio calculation part, 5 ... Data matching part, 6 ... Temperature calculation part, W ... Temperature measurement object (metal).

Claims (7)

[Claims] 1. The emissivity is obtained from the spectral radiant energy actually measured from the temperature-measuring object based on the relationship between the ratio of the power of the wavelength of each spectral radiant energy in two different wavelength bands and the emissivity, and this is obtained. A radiation temperature measuring method, wherein the temperature of the temperature-measuring object is calculated using the emissivity. 2. The radiant temperature measuring method according to claim 1, wherein a plurality of calibration curves of emissivity with respect to a power ratio of each spectral radiant energy are determined in advance, and the calibration curve is selected according to usage conditions. .. 3. The radiant temperature measuring method according to claim 2, wherein the calibration curve is integrated into a calibration curve in a low emissivity region and two calibration curves in a medium / high emissivity region. 4. The radiation temperature measuring method according to claim 2, wherein a lower limit value of a ratio of powers of respective spectral radiant energies is set for the calibration curve in the low emissivity region. 5. The temperature value, the emissivity value, or both values for each calibration curve are output when the value of the power ratio of each spectral radiant energy is equal to or more than the lower limit value. Radiation temperature measurement method described. 6. A calibration curve in a low emissivity region is selected when the value of the power ratio of each spectral radiant energy increases with the passage of time, and the value of the power ratio of each spectral radiant energy decreases. 4. The radiation temperature measuring method according to claim 3, wherein a calibration curve in the middle / high emissivity region is selected after the change. 7. A detection means for detecting each spectral radiant energy of the temperature-measuring object in two different wavelength bands, and a wavelength of each spectral radiant energy based on each spectral radiant energy from the detecting means. Ratio calculating means for calculating a ratio of powers, storage means for storing data indicating a relationship between a ratio of powers of wavelengths of the respective spectral radiant energies and emissivity, and respective spectra calculated by the ratio calculating means. Collating means for collating the ratio of the power of the wavelength of radiant energy with the data of the storage means to obtain the corresponding emissivity, and temperature for computing the temperature of the temperature-measured body based on the emissivity obtained by the collating means. A radiation thermometer, which is provided with a computing means.