JP2002303551A - Method and device for measuring temperature of in- furnace metallic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for measuring a temperature of in-furnace metallic material capable of effectively shielding a backlight radiation noise in the furnace and measuring emissivity and a temperature simultaneously. SOLUTION: A pseudo backbody furnace 5 and a first radiation thermometer 7 are installed mirror-symmetrically to a normal n to the surface of a strip metallic material 3 in a direction orthogonal to a traveling direction of the strip metallic material 3. A signal of the sum of radiation from the strip metallic material 3 and radiation reflected on the surface of the strip metallic material 3 from the pseudo blackbody furnace 5 is detected through a polarizing filter 9 by using the first radiation thermometer 7. A signal of radiation from a pseudo blackbody of the pseudo blackbody furnace 5 is detected by a second radiation thermometer 10 installed outside the furnace on the axis of the pseudo blackbody furnace 5 is installed. A surface temperature and the emissivity are accurately calculated from the signal from the first radiation thermometer 7 and the signal from the second radiation thermometer 10 by using an arithmetic unit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the temperature of a metal material in a furnace, and more particularly to a method suitable for measuring the temperature of a metal material heated in a heat treatment furnace or the like in an environment filled with background radiation noise. And equipment.

[0002]

2. Description of the Related Art It is well known in the art that radiation thermometry conventionally has a serious problem that a significant temperature measurement error occurs when the emissivity of an object to be measured changes. In particular, in the case of a metal that forms an oxide film by heating, the emissivity changes significantly. Therefore, the feature of the radiation temperature measurement method, which is a powerful non-contact temperature measurement method and can respond at high speed, is significantly impaired.

The inventors of the present invention have studied in detail the behavior of the emissivity in the process of forming an oxide film, such as the polarization characteristics and the directional characteristics, for several years, both theoretically and experimentally. As a result, by appropriately selecting the measurement wavelength and the measurement direction, the spectral polarization radiance L _p (hereinafter, referred to as p-polarization radiance) in a direction parallel to the plane including the sample surface normal and the measurement direction is obtained. Vertical spectral polarization radiance L _s
(Hereinafter referred to as s-polarized radiance) R _ps (= L
_p / L _s ) and a specific spectral emissivity can be proved to have a one-to-one correspondence relationship (Iuchi, Hoshino, Furukawa, Tasoe: “Polarization during metal oxidation” Characteristics and Application to Emissivity Corrected Emission Temperature Measurement ”, Transactions of the Society of Instrument and Control Engineers (Vol.35, No.7, pp.832 / 839, 1999). Thus, by measuring the spectral polarization radiance ratio R _ps, it is possible to obtain the spectral emissivity of unambiguously measured.

The result can be immediately applied as a simultaneous measurement method of “emissivity and temperature”. However, since the radiation thermometry detects heat radiation from the surrounding heating source as noise together with radiation from the measurement object, this measurement principle is applied in an environment where the background radiation noise is full such as in a furnace. In order to do so, a new challenge of how to deal with background radiation noise must be solved.

On the other hand, radiation temperature measurement near normal temperature means an environment in which the measurement target and the surroundings are almost equal. Therefore, it can be regarded as an environment full of background radiation noise as in the furnace. The present inventors have proposed a new principle under such conditions, that is, a radiation measurement method for low-emissivity metals near room temperature, which is considered to be extremely difficult to measure. That is, in this method, the metal emissivity increases about three times the normal direction at an angle θ = 80 ° with respect to the glossy metal sample surface normal, and the reflection characteristic of the sample is remarkably specular in that direction. This is a temperature measurement method that focuses on showing characteristics, effectively shields ambient background radiation noise, and measures weak radiation from metals near room temperature with high sensitivity. In addition, the use of p-polarized radiance in this configuration has brought this method to a more practical level. From 300 K for shiny cold-rolled steel sheets with a vertical emissivity of 0.1 or less
In the temperature range of 373 K, measurement was possible at the laboratory level with an error of about ± 2 K.

Here, the measurement principle of the “emissivity-corrected radiation temperature measurement method using polarized radiance” of the above-mentioned reference will be described in detail. Generally, when a metal is heated, an oxide film is formed on its surface. At this time, it is known that the spectral emissivity of the metal changes greatly with the growth of the oxide film. FIG. 7 shows an example of such a case, in which a cold-rolled steel sheet is used as the metal
This is a change in the spectral emissivity of a cold-rolled steel sheet observed over time during heating to 873K in the atmosphere. It can be seen that the spectral emissivity shows a peak value for each wavelength and changes greatly. This phenomenon is considered to be due to an interference effect based on multiple reflection of radiation between the metal surface and the oxide film. When the emissivity of the object to be measured fluctuates greatly, the radiation temperature measurement method causes a large temperature measurement error, and the temperature measurement method is one of methods for overcoming this.

As shown in FIG. 8, a radiation thermometer 22, which is installed at an angle θ with respect to the surface normal n of the metal 21 to be measured.
The radiance of the metal 21 surface is measured by 23. Now metal 21
Let T (K) be the temperature of the black body, and _{Lλ, b} (T) be the black body radiance at the wavelength λ and the temperature T, which is detected by the radiation thermometer 22 through the p-polarization prism 24a of the polarization prism 24. When the radiance signals from the metal 21 surface and E _p, E _p is expressed by the following equation (1). _{E p = k p · ε p} · L λ, b (T) ............ (1) where, _k p; p- polarizing prism (or p- polarized light filter) 2
Electric signal gain of radiance detected by the radiation thermometer 22 via 4a ε _p ; p-polarized spectral emissivity at wavelength λ of metal 21

[0008] Similarly, when the radiance signals from 21 surface metal being detected by the radiation thermometer 23 via the s- polarization prism 24b and E _s, E _s is expressed by the following equation (2). E _s = k _s ε _s L _{λ, b} (T) (2) where k _s ; s-polarizing prism (or s-polarizing filter) 2
Electric signal gain of radiance detected by the radiation thermometer 23 via 4b ε _s ; _s -polarized spectral emissivity at wavelength λ of metal 21

The radiance of the blackbody furnace set at the temperature T is determined by the radiance signals detected by the radiation thermometers 22 and 23 with the above-described polarizing prism (or polarizing filter) 24 attached to p-polarized light and s-polarized light. E _{p, b} , E corresponding to the polarization
_s, and the _{b, E p, b = k} p · L λ, b (T) ............ (3) E s, b = k s · L λ, b (T) ............ (4) here, (1) taking the ratio of the formulas _{(2), E p / E s = (} k p / k s) (ε p / ε s) = k · R ps ......... ... (5)

Further, _{k = k} p / _{k s} is E _p (3) and _{(4), b / E s, b =} k p / k s = k ............ (6), Black Since it is the body output signal ratio, it is obtained in advance and is a known constant value. Rps on the right side of the equation (5) is the polarized emissivity ratio ε _p / ε _s , and since k is constant, as shown on the left side, the polarized radiance signal ratio E _p
/ It is to be understood as measured by _{E s.}

Therefore, if a one-to-one correspondence is established between the index _Rps and the spectral emissivity ε (λ) of the metal 21, R
_The emissivity can be determined by measuring _ps . Figure 9 is R _ps spectral emissivity ε a cold rolled steel sheet as a sample
9 is an experimental example in which the relationship of (λ) was examined. (A) of the figure is R _ps
And the spectral emissivity were both wavelengths λ = 3.4 μm. Also, (b) shows that _Rps is λ = 3.4 μm and the spectral emissivity is λ = 1.5 μm, and (c) shows that _Rps is λ = 1.5 μm and the spectral emissivity is λ = 3.4 μm, and (d) _Indicates that both R _ps and the spectral emissivity were at a wavelength λ = 1.5 μm.

From these relationships, a one-to-one correspondence between _Rps and spectral emissivity can be established by appropriate selection of wavelength λ. The most preferable relational expression in FIG. 9 is the relation represented by (b). That is, R _ps
.Lambda. = 3.4 .mu.m. Generally, a good one-to-one relationship can be obtained by measuring _Rps at a long wavelength and spectral emissivity at a short wavelength. Conversely, as shown in (c), R _ps
Is measured at λ = 1.5 μm and the spectral emissivity at λ = 3.4 μm, a relational expression is obtained such that two spectral emissivities are obtained for one measurement of _Rps . Therefore, proper emissivity correction cannot be performed by such wavelength selection. It has been clarified that these phenomena are caused by an interference phenomenon of radiation due to formation of an oxide film.

[0013]

However, the emissivity correction method using the polarized radiance described so far is
This method was effective in an environment where there was no heat source around the object to be measured, so that radiation from the heat source was not reflected by the metal 21 and incident on the radiation thermometers 22 and 23. That is,
This is based on the assumption that there is no background radiation noise.

By the way, when applying to a measurement object in a high-temperature furnace such as a heat treatment furnace for heat-treating a metal or the like at a high temperature, heat radiation from an ambient heating source is detected as noise together with radiation from the measurement object. Will be lost.
In an environment where the background radiation noise is full, such as in a high-temperature furnace, how to deal with the background radiation noise has been a major issue.

Conventionally, as a means for shielding the background radiation noise peculiar to the furnace, for example, as shown in FIG. 10, a water-cooled shielding plate 25 or the like is introduced into the furnace 26 to forcibly shield or eliminate the background radiation noise. In general, however, there is a risk of causing a water leak accident, and it is difficult to detect the water leak. However, there is a disadvantage in that the operation of the production process is hindered, for example, the quality is deteriorated by cooling, and the safe operation for a long period is hindered. Also,
As shown in FIG. 11, a non-water-cooled reference black body light source 27 is installed in the furnace, and the temperature of the material 21 and the temperature of the black body 30 are measured using two radiation thermometers 28 and 29, respectively. There is also a technology to shield the background radiation noise, but this means is a furnace temperature measurement technology that assumes that the emissivity of the measurement object is constant, and attempts to simultaneously measure the emissivity and temperature, which is the object of the present invention Not a technology.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and effectively shields background radiation noise and simultaneously measures emissivity and temperature. It is an object of the present invention to provide a method and an apparatus for measuring a temperature of a metal material in a furnace.

[0017]

The method of the present invention is a method for measuring the temperature of a metal material to be heated while traveling in a furnace, wherein the temperature of the metal material is measured in a direction perpendicular to the running direction of the metal material. A pseudo-blackbody furnace and a first radiation thermometer are installed in mirror symmetry with respect to a normal line of a material surface, and the radiation from the metal material and the pseudo-blackbody furnace are measured using the first radiation thermometer. Detecting a signal of the sum of the radiation reflected from the surface of the metal material and a second radiation thermometer installed outside the furnace on the axis where the pseudo black body furnace is installed. A step of detecting a signal of radiation from the pseudo black body of the furnace; and calculating a surface temperature and an emissivity of the metal material from a signal from the first radiation thermometer and a signal from the second radiation thermometer. And measuring the temperature of the metal material in the furnace.

In the method of the present invention, the first radiation thermometer detects a sum of radiation from the metal material and radiation reflected from the surface of the metal material from the pseudo blackbody furnace. ,
Preferably, the measurement is performed separately for p-polarized radiance and s-polarized radiance. Furthermore, the method according to the invention can also be applied to metal materials which are heated while standing in a furnace.

Further, the apparatus of the present invention is an apparatus for measuring the temperature of a metal material to be heated while traveling in a furnace, wherein the temperature of the metal material is measured in a direction perpendicular to the traveling direction of the metal material. A pseudo-blackbody furnace installed at a position in the furnace that mirror-reflects rays, and a pseudo-blackbody furnace installed at a position outside the furnace that is mirror-symmetrical to the pseudo-blackbody furnace and emitting radiation from the metal material surface. A first radiation thermometer for simultaneously detecting radiation from a light source via a polarizing filter, a second radiation thermometer for detecting radiation on a pseudo black body surface of the pseudo black body furnace, and the first radiation thermometer The sum signal of the radiation from the metal material detected by the above and the radiation reflected from the surface of the metal material from the pseudo black body furnace, and the radiation signal of the pseudo black body surface detected by the second radiation thermometer, A computing device for computing the surface temperature and emissivity of the metal material using It is made of a temperature measuring device in the furnace metal material characterized by.

In the apparatus of the present invention, the pseudo black body furnace may be made of a ceramic heat insulating material or a heat-resistant metal.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view schematically showing the configuration of the present invention. In this figure, reference numeral 1 denotes a high-temperature furnace body such as a heat treatment furnace, in which a refractory 2 such as a brick is stuck. Reference numeral 3 denotes a strip-shaped metal material to be heated in the furnace, which can be moved in the furnace via a roll 4 installed in the furnace.

Reference numeral 5 denotes a pseudo black body furnace installed in the furnace. The pseudo black body furnace 5 is suspended from the ceiling 1c so that the opening surface 5a is oriented at an angle θ with respect to the surface normal n of the center of the strip-shaped metal material 3. It is attached to the support member 6 that can be lowered. Reference numeral 7 denotes a first radiation thermometer installed outside the furnace, and an opening 8a provided in the side wall 1a.
At a position symmetrical to the pseudo black body furnace 5 with respect to the surface normal n of the center of the strip-shaped metal material 3 from the angle θ direction.
The sum of the surface radiation and the radiation of the pseudo blackbody furnace 5 is detected simultaneously. Reference numeral 9 denotes a polarization filter, which includes p-polarization filters 9a and s-
By switching the polarization filter 9b, p-polarized luminance and s-polarized luminance can be detected alternately.

Reference numeral 10 denotes a second radiation thermometer installed outside the furnace, which emits radiation on the back side of the pseudo black body 5b of the pseudo black body furnace 5 through an opening 6b provided in the side wall 1b on the opposite side. Opening surface 5
Non-contact detection from c. The attachment angle θ between the pseudo black body furnace 5 and the first radiation thermometer 7 is preferably around 80 °.
The reason will be described later. Numeral 11 denotes an arithmetic unit, which is a sum signal of the radiation from the band-shaped metal material 3 detected by the first radiation thermometer 7 and the radiation reflected from the surface of the band-shaped metal material 3 from the pseudo blackbody furnace 5, and the second signal. Has a function of calculating the surface temperature and emissivity of the band-shaped metal material 3 using the radiation signal of the pseudo black body surface detected by the radiation thermometer 10 of the present invention.
The output is displayed on 12.

With such a configuration, first, the first radiation thermometer 7 forms an angle θ with respect to the surface normal n of the central portion of the strip-shaped metal material 3.
The p-polarized radiance is measured from the direction. At this time, the pseudo-blackbody furnace 5 arranged in a mirror-symmetrical direction with respect to the first radiation thermometer 7 with respect to the sample surface normal acts as a reference light source. The detected signal is not affected by shielding background radiation in the furnace, which may be noise. Here, the structure of the pseudo blackbody furnace 5 installed in the furnace will be supplemented. That is, in order to install the pseudo black body furnace 5 in a high-temperature furnace and realize a pseudo black body by natural heating, there are some restrictions on the material, shape, dimensions, mounting position, and the like.

First, since the material must withstand semi-permanent continuous use in a high-temperature furnace exceeding 1000 ° C., it must be made of a high-temperature heat-resistant material such as a ceramic heat insulating material or a heat-resistant metal. . A simple shape for cavity radiation is to configure a cylindrical shape, but when this is used as a pseudo blackbody furnace, the effective emissivity is infinite
Must be configured to have a value close to 1.0.
For this purpose, as shown in FIG.
It has been experimentally confirmed that the ratio L / D of the length L to the bottom surface and the diameter D of the opening surface 5a should be 5 or more.
It is to be noted that the thickness t of the pseudo black body 5b is preferably as thin as possible so as not to have a temperature difference between both surfaces, and specifically, it is desirably L / 10 or less. However, the intrinsic emissivity of the material constituting the pseudo blackbody furnace must be 0.5 or more. This condition can be easily realized by the above-mentioned ceramic heat insulating material.

The reason why a non-contact radiation thermometer is used to measure the temperature of the pseudo black body furnace 5 is supplemented by the fact that the radiation thermometer is used for a contact thermocouple or a resistance thermometer used for ordinary temperature measurement. On the other hand, it is advantageous because it is non-contact type, can be installed outside the furnace, there is no risk of deterioration over time, and temperature measurement can be performed semi-permanently. The second radiation thermometer 10 measures the surface on the opposite side of the cylindrical pseudo black body 5b. In order to make the effective emissivity of that surface sufficiently close to 1.0, the surface of the aperture surface 5c should be measured. It is preferable that the shape be symmetrical with the opening surface 5a about the bottom surface of the pseudo black body 5b.

Hereinafter, the basic principle of temperature measurement according to the present invention will be described in detail. Now, let T (K) be the temperature of the traveling metal strip 3 measured by the first radiation thermometer 7,
Let black body spectral radiance at wavelength λ and temperature T be L _{λ, b} (T). Also, assuming that the pseudo black body temperature of the pseudo black body furnace 5 measured by the second radiation thermometer 10 is _Tr (K), a signal detected by the first radiation thermometer 7 through the p-polarizing filter 9a. E _p can be expressed by the following equation (7).

[0028] _{E p = k p · {ε} p · L λ, b (T) + p · (1-ε p) · L λ, b (T r)} ............ (7) where, _{k p} An electrical signal gain ε _{p of} radiance detected by the first radiation thermometer 7 including the p-polarization filter 9 a; p-polarized spectral emissivity p at a wavelength λ of the metal band 3; A coefficient to be corrected because the surface is somewhat rough and therefore not a perfectly specular reflection surface (0 <p
≦ 1). In the case of a perfectly specular reflection surface, p = 1.

[0029] Similarly, the signal E _s, which is detected by the first radiation thermometer 7 through s- polarization filter 9b can be expressed by the following equation (8). _{E s = k s · {ε} s · L λ, b (T) + s · (1-ε s) · L λ, b (T r)} ............ (8) where, _k s; s- Electric signal gain ε _{s of} radiance detected by the first radiation thermometer 7 including the polarization filter 9b; _s -polarized spectral emissivity s at the wavelength λ of the band-shaped metal material 3; Coefficient (0 <s) to correct for a rough surface and therefore not a perfectly specular reflection surface
≦ 1). In the case of a perfectly specular reflection surface, s = 1.

When a part of the second term on the right side of the equations (7) and (8) is moved to the left side and summarized, the following equations (9) and (10) are obtained. _{E p -k p · p · L} λ, b (T r) = k p · ε p · {L λ, b (T) -p · L λ, b (T r)} ............ (9) _{E s -k s · p · L} λ, b (T r) = k s · ε s · {L λ, b (T) -p · L λ, b (T r)} ............ (10)

Taking the ratio of each side of the equations (9) and (10), the following equation (11) is obtained. _{{E p -k p · p ·} L λ, b (T r)} / {E s -k s · p · L λ, b (T r)} = (k p / k s) · (ε p / ε _s ) · {L _{λ, b} (T) / {L _{λ, b} (T)} (11) In Equation (11), the gains k _p and k _s are default values, respectively. Thus, the ratio _{k = k} p / _{k s} is the known constant value. Further, since the temperature _{Tr of the} black body is measured by the second radiation thermometer 10, L
_{λ, b} (T _r ) is known. Therefore, _{Ep, b} =
k _p · L _{λ, b} ( _Tr ), E _{s, b} = k _s · L _{λ, b}
(T _r ) is a known value based on the measurement of T _r . The correction coefficients p and s are equal if the surface to be measured is a random rough surface, and can be set to p = s (= q; constant).

Rewriting equation (11) under these conditions gives:
Equation (12) is obtained. (E_p -QE_{p, b}) / (E_s -QE_{s, b}) = K · (ε_p / Ε_s ) = KR_ps  ... (12) where the polarized emissivity ratio R_ps= Ε_p / Ε_s Was used.
In equation (12), the left side is the ratio of the measured value if q is given.
It is a value that can be calculated because
Value, the polarization emissivity ratio R_psIs obtained by equation (13).
Can be R_ps= (1 / k) ・ (E_p −q · E_{p, b}) / (E_s −q · E_sb) …(13)

The correction coefficient q increases as the measurement target becomes a specular reflection surface. That is, although it is related to the surface roughness of the measurement object, Beckma shown in the following equation (14) is used as an index for evaluating the specular reflection surface under the condition of σ / λ≪1.
There are nn analytical expressions. ρ _r = ρ _o exp [−4π ｛(σ / λ) cos θ｝] ² (14) where, ρ _r : specular reflectance of the actual sample, ρ _o ; optically smooth with the same sample Surface reflectance, σ; mean square roughness (μm) of the sample surface, θ; angle (°), indicating that the mirror surface component increases as the wavelength λ increases and as the angle θ increases. ing.

FIG. 3 shows an example of the directional characteristics of the emissivity of the metal. As the angle θ increases, the p-polarized emissivity ε _p (θ) and the unpolarized emissivity ε (θ) increase. Especially θ
It can be seen that at around = 80 °, the emissivity value is several times the s-polarized emissivity in the vertical direction. As described above, by increasing the angle θ (for example, θ ≧ 60 °), by increasing the measurement wavelength λ, the metal sample exhibits a specular reflection characteristic, and at that angle, the emissivity is also extremely high. By utilizing the synergistic effect of increasing the noise, it is possible to shield the background radiation noise.

Further, by making the opening surface 5a of the pseudo black body furnace 5 sufficiently large, the diffuse reflection component of the strip-shaped metal material 3 can be reduced, so that the strip-shaped metal material 3 is made of a material such as a stainless steel plate. Has some specular reflection characteristics, q あ る 程度 1.0 can be approximately set. The size of the aperture surface can be roughly estimated by the equation (14), but can be practically determined by actually measuring a diffuse reflection component of a specific measurement object. When the measurement object is a metal, if the polarized radiance ratio R _ps and the spectral emissivity ε (λ) are respectively obtained in appropriate wavelength bands, as shown in FIG.
As described above, a one-to-one correspondence relationship can be established between _ps and ε (λ). Taking a heat treatment of a stainless steel plate having a temperature range of 1200 K as an example, a composite element of Si and InGaAs is used as the sensor of the first radiation thermometer 7, and the polarized radiance is InGaAs sensor which is sensitive at a wavelength of λ = 1.5 μm. Ratio R _ps
Can be used to correct the spectral emissivity ε (λ) with a Si sensor sensitive at a wavelength of λ = 0.9 μm.

As described above, even in the case of a metal such as a strip-shaped metal material running in the furnace, the introduction of the pseudo blackbody furnace 5 shields the background radiation noise from the furnace wall and the heating source, and By regarding the radiation from the pseudo blackbody furnace 5 as the reference radiation source, the polarized radiance ratio R
_ps can be determined. Accordingly, the emissivity ε _p or ε _s is obtained based on FIG.
By determining the E _p or E _s into equation or equation (8), it is the true temperature T of the belt-like metal material is obtained.

The conditions required for the simulated black body furnace 5 are, in addition to the dimensional conditions described above, an opening 5a which is large in order to correct the diffuse reflection component on the sample surface, and which is installed as close as possible to the sample surface to be measured. There is a need to. At this time, there is a possibility that the traveling strip-shaped metal material 3 may come into contact with the movable metal material 3 if it moves up and down. As a means for avoiding this, as shown in FIG. 5, a pseudo blackbody furnace 5 can be provided on the side of the band-shaped metal material 3. If this method is further extended, a part of the side wall 1c itself can be formed as a pseudo black body 13 as shown in FIG. In this case, the opening surface 5a can be made large, and a contact-type thermocouple 14 or the like can be easily used instead of the radiation thermometer for measuring the pseudo black body temperature.

Although the above embodiment has been described with reference to a case where the present invention is applied to a strip-shaped metal material such as a cold-rolled steel plate or a stainless steel plate which is heated while traveling in a furnace, the present invention is not limited to this. Needless to say, the present invention can also be applied to a metal material that is stationary in a furnace. In addition, the present invention is not limited to the cold rolling process described above,
Obviously, the present invention can be applied to other steel manufacturing processes, aluminum and other non-ferrous metal manufacturing processes, paper making processes and printing processes, Si semiconductor wafer manufacturing processes, and the like.

[0039]

Embodiments of the present invention will be described below.
When a cold-rolled steel sheet having a thickness of 1.0 mm and a width of 1000 mm was heat-treated using a continuous annealing furnace, the surface temperature of the steel sheet was measured by applying the method of the present invention. The traveling speed of the steel sheet at that time was 60m / min,
The ambient temperature in the furnace is 1000 ° C and the target temperature for heat treatment of the steel sheet is 9
It was 00 ° C. The size of the pseudo black body furnace 5 is 2L = 1000m in length
m, an inner diameter D = 100 mm, and a pseudo black body 5b having a thickness t = 50 mm was fixed such that the bottom face was positioned at the position of the length L. Mounting angle θ of this pseudo blackbody furnace 5 and first radiation thermometer 7
Is the surface normal n of the steel plate so as to detect the radiation of the specular reflection surface.
70 °, the emissivity and temperature could be measured simultaneously and accurately.

[0040]

As described above, according to the method and the apparatus of the present invention, the pseudo blackbody furnace is introduced into the furnace, and the radiation from the metal material and the metal material from the pseudo blackbody furnace are installed. And simultaneously detect the radiation reflected from the surface of the simulated blackbody furnace,
Even if the speed of the metal material traveling in the furnace is sufficiently low or stationary, it can accurately measure the emissivity and temperature, contributing to appropriate heat treatment of the material. It can contribute to the improvement of product quality, stable operation of processes, energy saving and cost reduction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of the present invention.

FIG. 2 is a schematic view showing an example of a pseudo blackbody furnace used in the present invention.

FIG. 3 is a characteristic diagram illustrating an example of a directional characteristic of an emissivity of a metal.

FIG. 4 is a characteristic diagram illustrating an example of a relationship between a polarized radiance ratio and an emissivity.

FIG. 5 is a schematic diagram showing another embodiment of the present invention.

FIG. 6 is a schematic diagram showing another embodiment of the present invention.

FIG. 7 is a characteristic diagram illustrating an example of a change in spectral emissivity of a cold-rolled steel sheet.

FIG. 8 is an explanatory diagram schematically showing a conventional measurement example of radiance.

FIGS. 9A to 9D are characteristic diagrams showing an example of the relationship between the index _Rps and the spectral emissivity ε.

FIG. 10 is an explanatory diagram illustrating a conventional example of back light radiation noise shielding.

FIG. 11 is an explanatory diagram showing another conventional example of back light radiation noise shielding.

[Description of Signs] 1 Furnace body 1a Side wall 1b Side wall 1c Ceiling part 2 Refractory 3 Strip-shaped metal material (metal material) 4 Roll 5 Pseudo black body furnace 5a Opening surface 5b Pseudo black body 5c Open surface 6 Support member 7 First member Radiation thermometer 8a, 8b Opening 9 Polarization filter 9a p-polarization filter 9b s-polarization filter 10 Second radiation thermometer 11 Operation device 12 Display device 13 Pseudo black body 14 Thermocouple 21 Metal (material) 22 Radiation thermometer 23 Radiation thermometer 24 Polarizing prism 24a p-polarizing prism 24b s-polarizing prism 25 Shielding plate 26 Furnace 27 Reference black body light source 28 Radiation thermometer 29 Radiation thermometer 30 Black body

Claims (5)

[Claims] 1. A method for measuring a temperature of a metal material heated while traveling in a furnace, wherein the temperature is a mirror symmetry with respect to a normal to a surface of the metal material in a direction perpendicular to a traveling direction of the metal material. A simulated black body furnace and a first radiation thermometer are installed, and the radiation from the metal material and the reflection from the surface of the metal material from the simulated black body furnace using the first radiation thermometer are used. Detecting a signal of the sum of the radiation and a signal of radiation from the pseudo-blackbody of the pseudo-blackbody furnace with a second radiation thermometer installed outside the furnace on the axis where the pseudo-blackbody furnace is installed. And calculating the surface temperature and emissivity of the metal material from a signal from the first radiation thermometer and a signal from the second radiation thermometer. To measure the temperature of the metal material inside the furnace. 2. The p-polarized radiance when the first radiation thermometer detects the sum of radiation from the metal material and radiation reflected by the surface of the metal material from the pseudo blackbody furnace. And s
The method for measuring a temperature of a metal material in a furnace according to claim 1, wherein the temperature is measured separately from the polarized radiance. 3. The method for measuring the temperature of a metal material in a furnace according to claim 1, wherein the method is for a metal material that is heated while being stationary in the furnace. 4. An apparatus for measuring the temperature of a metal material that is heated while traveling in a furnace, wherein the temperature of the metal material is mirror-reflected with respect to a normal line of the surface of the metal material in a direction perpendicular to a traveling direction of the metal material. A pseudo black body furnace installed at a position inside the furnace, and a mirror installed at a position outside the furnace that is mirror-symmetrical to the pseudo black body furnace to polarize radiation from the metal material surface and radiation from the pseudo black body furnace. A first radiation thermometer that detects simultaneously through a filter, a second radiation thermometer that detects radiation of the pseudo black body surface of the pseudo black body furnace, and the metal that is detected by the first radiation thermometer Using the sum signal of the radiation from the material and the radiation reflected by the surface of the metal material from the pseudo black body furnace and the radiation signal of the pseudo black body surface detected by the second radiation thermometer, A computing device for computing the surface temperature and emissivity of the object. Temperature measuring device furnace metal material to. 5. The apparatus for measuring a temperature of a metal material in a furnace according to claim 4, wherein the pseudo black body furnace is made of a ceramic-based heat insulating material or a heat-resistant metal.