JPH05164617A - System for measuring surface-physical-property value and surface-characteristic value of continuous process material - Google Patents

Abstract

PURPOSE:The surface-physical-property value and the surface-characteristic value of a process material and their measuring positions are measured accurately on line at the arbitrary positions of a continuous process line. CONSTITUTION:A plurality of radiation thermometers 14A-14N are arranged along a continuous process line. The measuring height and the measuring angle of each thermometer can be varied and can be detected. The ratio of the power of emissivities is operated by using luminance temperatures S1 and S2 at wavelengths lambda1 and lambda2 obtained with the radiation thermometers. The correlation data between the thickness of an oxide film (surface characteristic value) and the ratio of the power of emissivities, which are formed by off line based on experiment data, theory or the like, are applied, and the oxide-film thickness dk at an arbitrary measuring position is obtained. The measuring position is computed based on the measuring height and the measuring angle of each radiation thermometer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical properties of process materials based on information obtained when radiation from a material surface is measured by a radiation thermometer in a continuous process line for continuously processing process materials. Surface physical property values such as values (refractive index, reflectance, absorptance, emissivity, transmittance) and surface characteristic values such as oxide film thickness that can be measured online. Regarding measurement system.

[0002]

2. Description of the Related Art For example, in a continuous process line such as a process of hot rolling a steel sheet, the surface condition of the process material, that is, the surface physical property value and the characteristic value are grasped online at an arbitrary position of the line. It is extremely important to perform process control with high accuracy.

Conventionally, since it was not possible to directly grasp the surface physical property value and the characteristic value, it is assumed that the processing temperature is measured and that the processing temperature and the physical property value have a close relationship. Process control is performed using the processing temperature as a controlled variable. At that time, in the continuous process line, the normal processing temperature is measured using a radiation thermometer.

[0004]

However, when the surface temperature of a process material is measured by using a radiation thermometer, an oxide film is formed on the surface like a process material such as a steel plate and changes with time. In that case, there is a problem that the temperature cannot always be accurately measured because the spectral emissivity from the surface also changes.

Hereinafter, this point will be described in detail.

First, the principle meaning of the symbols used in the following description will be clarified.

Temperature measurement wavelengths: λ ₁ , λ ₂ , ... λ _i [μm] Proximity wavelengths of the above wavelengths: λ _1x , λ _2x , ... λ _ix [μm] _Magnitude relationship of the above wavelengths λ ₁ < λ _1x <λ ₂ <λ _2x <... <λ _i <λ _ix Spectral emissivity at temperature measurement wavelength λ _i : ε _i [μm] Proximity spectral emissivity at near wavelength λ _ix : ε _ix [μm] Thermal object Surface true temperature: T [K] Thermal object surface Luminance temperature at wavelength λ _i : Si [K] Thermal object surface Luminance temperature at wavelength λ _ix : Six [K] Radiant (Plank) second constant C2: 1.4388 × 10 ⁴ [ μm ・ K]

A radiation thermometer for measuring the surface temperature of a hot object by applying the radiation temperature measurement technique is widely used. This radiation thermometer has a single color thermometer having one wavelength used for measurement and two radiation thermometers.
There are two two-color thermometers. Not only a monochromatic thermometer but also a two-color thermometer that uses two wavelengths causes a large measurement error when the emissivity of the measurement target changes.

In the two-color thermometer, when the spectral emissivities at the two wavelengths to be measured are substantially equal or a certain proportional relationship is established, there is no problem in temperature measurement accuracy, but the surface state of the thermal object is an oxidation reaction. When the spectral emissivity deviates from the above relation, the measurement accuracy becomes significantly worse (a monochromatic radiation thermometer has a larger error than this).

Japanese Patent Publication No. 3-4855 discloses an improved two-color thermometer which corrects the emissivity and is used as a radiation thermometer which solves this measurement accuracy problem.

Further, the radiation temperature measuring technique which is substantially the same as that of the improved two-color thermometer is based on "Theory o" by Tanaka and DP Dewitt.
fa New Radiation Thermometry Method and an Experi
mental Study Using Galvannealed Steel Specimens "
(Proceedings of the Society of Instrument and Control Engineers, Vol. 25, No. 10, 1031 /
TRA disclosed on page 1037, October 1989)
CE (Thermometry Re-established by Automatic Comp
ensation of Emissivity) method. This TRACE method has the drawbacks that the calculation is complicated and time consuming, and it is difficult to make an empirical formula as compared with the improved two-color thermometer disclosed in Japanese Patent Laid-Open No. 3-4855. ..

Since the improved radiation thermometer and the TRACE method basically use the same calculation method, the former method will be mainly described.

In Japanese Examined Patent Publication No. 3-4855, T is deleted from the formula of spectral emissivity represented by the following formulas (1) and (2) obtained by using the Wien approximation rule, and the following formula (3) is obtained. Are seeking. The ratio (Kuramasu number) of the power of the wavelength of the spectral emissivity, which is the left side of the equation (3), is called the emissivity exponentiation ratio for convenience of explanation.

Note that the following equation is separated by two wavelengths λ for simplicity.
The case of ₁ and λ ₂ is shown, but two adjacent wavelengths λ
_{The same} holds true for ₁ and λ _1x .

Ε ₁ = exp {(C 2 / λ ₁ ) (1 / T-1 / S 1)} (1) ε ₂ = exp {(C 2 / λ ₂ ) (1 / T-1 / S 2)} (2) ε ₁ ^{λ 1} / ε ₂ ^λ ₂ = exp {C 2 (1 / S 2 −1 / S 1)} (3) (left side: emissivity power ratio)

In the above equation, the brightness temperatures S1 and S2 are 2
Since it is obtained as the output of the wavelength detector, the value of the emissivity exponentiation ratio can be obtained by calculating the right side of the equation (3).

Further, from the equations (1) and (2), the equation (4) expressing the true temperature T of the surface of the heat object is obtained, and by applying the ratio of the spectral emissivity to the equation (4), T can be obtained. You can ask.

T = (λ ₂ −λ ₁ ) / {(λ ₁ λ ₂ / C 2) ln (ε ₁ / ε ₂ ) + λ ₂ / S 1 −λ ₁ / S 2} (4)

On the other hand, the correlation function f between the spectral emissivity ratio and the emissivity exponentiation ratio as shown in equation (5) is determined in advance by measurement.

In measuring the temperature, the spectral emissivity ratio is obtained from the emissivity exponential ratio calculated by the equation (3) by the correlation function f, and the true temperature T is calculated by the equation (4) using the spectral emissivity ratio. To do. As described above, the old two-color radiation thermometer calculates the spectral emissivity ratio as 1 or a constant value, and does not correspond to the change in spectral emissivity.

Ε ₁ / ε ₂ = f (ε ₁ ^{λ 1} / ε ₂ ^λ ₂ ) (5)

When the measurement method using the above equations is applied to a thermal object whose surface state changes due to an oxidation reaction or the like, temperature measurement can be performed with sufficient accuracy by selecting a "dull" measurement wavelength with respect to the surface change. It is possible. However, when the emissivity power ratio of the selected wavelength sensitively changes with respect to the change of the surface state, the measurement accuracy deteriorates remarkably as described below.

As a specific example in which the spectral emissivity of the selected wavelength is sensitively changed by the change of the surface state of the heat object, the surface is oxidized and a semitransparent (at the measurement wavelength) oxide film is formed on the surface. There is. In this case, the semi-transparent film formed on the surface causes optical interference and the spectral emissivity is drastically reduced. In this case, the emissivity exponential ratio also changes suddenly.

Such a sudden change in the emissivity is described by Makino et al. In, for example, "Heat Transfer 1986", vol.
2, Hemishere, (1986), PP. 577-582
From the experiments and model calculations of the optical interference theory, when surface oxidation occurs, a drop in the spectral emissivity spectrum (hereinafter referred to as a valley) appears in the short wavelength region, and this valley moves in the long wavelength direction as the oxidation progresses. Confirmed as a characteristic change.

13 to 17 are schematic diagrams showing an example of characteristic changes in the spectral emissivity spectrum.

In the figure, the horizontal axis is the spectral wavelength λ, and the vertical axis is the emissivity ε.
And the portion indicated as valley is the valley of the spectral emissivity spectrum.

FIGS. 13 to 17 show how the spectral emissivity spectrum of a metal surface such as stainless steel changes as the oxide film is formed on the surface.

FIG. 13 shows a low temperature state before the oxide film is formed,
FIG. 14 shows a stage where an oxide film is not formed yet while being heated to a medium temperature, FIG. 15 is a stage where an oxide film starts to be formed when heated to a medium temperature, and FIG. 16 shows an oxide film growing at the same temperature. FIG. 17 shows the respective spectra at the stage where the thick oxide film was formed by heating to the high temperature.

It is considered that the reason why the above-mentioned valleys occur is mainly due to the optical interference due to the oxide film, and Makino et al. Obtained the spectral emissivity spectrum by the model calculation based on the interference theory, and calculated the result and the experimental value. It is reported that they compare well with each other.

Therefore, it is explained that the phenomenon that the spectral emissivity spectrum changes appears because the radiant energy in the spectral wavelength band on the order of the thickness of the oxide film or less is selectively trapped in the oxide film. That is, because the radiation specifically selected causes interference or multiple reflections in the oxide film, remarkable energy attenuation occurs, and the selected wavelength band moves as the oxide film thickness increases, so the valley has a short wavelength → It is thought to move to longer wavelengths.

When such a spectral emissivity spectrum changes with time, the emissivity ratio changes, so that the old type 2
It goes without saying that a measurement error occurs in the color radiation thermometer, and it is also difficult to calculate the equation used in the improved two-color thermometer, and thus a measurement error similarly occurs.

The reason is that in the calculation of the improved two-color thermometer using the two adjacent wavelengths λ ₁ and λ _1x , the correlation between the two spectral emissivities ε ₁ and ε _1x is preliminarily calculated from the experimental data by using a regression function. This is because it is difficult to return to the situation even though it must be decided as. This will be briefly described below.

_{Assuming that} the measured data of the spectral emissivity ε ₁ and ε _1x is the data during the movement of the valley from the short wavelength to the long wavelength as in the above-mentioned spectral emissivity spectrum, the emissivity ε
The correlation between ₁ and ε _1x changes from “positive correlation” to “negative correlation” to “positive correlation”.

This can be easily understood by following the changes in the values of the emissivity ε ₁ and ε _1x corresponding to the approaching two wavelengths λ ₁ and λ _1x in FIGS. 13 to 17. That is, "vall
Short wavelength side of "ey" part (where the spectral slope is negative)
When is between wavelengths λ ₁ and λ _1x , the magnitude relationship between the emissivity ε ₁ and ε _1x is reversed, and the positive and negative signs of the correlation are reversed.

This state is concretely shown in FIG. It is understood that there is a completely opposite correlation between the valley before (time 1) and after the valley (time 2). When there is no valley, such a reversal of the correlation does not occur (Fig. 18).

"Steelmaking Research No. 339" by Tanaka et al. (1
990) 63 to 67, the ε ₁ -ε ₂ correlation graph as schematically shown in FIG. 20 is not monovalent, and a loop is formed, but this loop also shows oxide film radiation interference. It is estimated that

As explained above, since the correlation regression graph of the emissivity ε ₁ and ε _1x cannot be determined simply, it is inevitable that a measurement error will occur even in the case of the improved two-color thermometer. ..

Actually, when the temperature of the stainless steel plate (SUS430) whose surface oxidation was in progress was measured with the improved two-color thermometer, the maximum value of the measurement error was about 15 ° C. in the temperature range of about 600 ° C., and the standard deviation. Was about 5 ° C.

As described in detail above, in the radiation thermometer, when the surface condition of the process material such as the steel plate changes with time and the emissivity also changes, as in the case of continuously heating the steel plate. However, since the surface temperature of the process material cannot be accurately measured, the thickness of the oxide film cannot be controlled with high accuracy even when the surface temperature of the process material is used as a control amount.

Therefore, it has been earnestly desired to directly measure the optical property value of the surface of the process material, the characteristic value such as the oxide film thickness online and use the measured value for the control of the continuous process line. However, such a technique has not yet been developed, and the conventional process control is, so to speak, blind control.

The present invention has been made to solve the above-mentioned conventional problems, and the physical property value or characteristic value of the surface of the process material can be directly measured online at an arbitrary position of the continuous process line, Moreover, it is an object of the present invention to provide a surface physical property value / characteristic value measurement system for a continuous process material, which can accurately measure the measurement position.

[0042]

SUMMARY OF THE INVENTION The present invention is a surface property / characteristic value measuring system for a continuous process material, in which a plurality of radiation thermometers are installed along a continuous process line. At least one of the height and the measurement angle is variable, and the measurement height and the measurement angle can be detected, and each radiation thermometer has two different wavelengths λ.
Using the brightness temperatures S1 and S2 measured for 1 and λ2, an emissivity power ratio calculating means for calculating the emissivity power ratio according to the following relational expression, and ε1 ^λ1 / ε2 ^λ2 = exp {C2 (1 / S2 − 1 / S1)} (C2: Second Blank constant) Data for storing correlation data between surface property values / characteristic values and emissivity exponential ratio, created offline based on experimental data, theory, or approximation from theory Storage means, for each radiation thermometer, a conversion means for converting the emissivity power ratio calculated by the above relational expression into the surface physical property value / characteristic value by the above correlation data, and the measurement height of each radiation thermometer at the time of measurement. The above object is achieved by a configuration including a position calculation unit that calculates a measurement position based on a measurement angle.

The present invention also enables a radiation thermometer to be set to a measurement height and a measurement angle corresponding to a specified surface physical property value / characteristic value in a surface physical property value / characteristic value measurement system for a continuous process material. As a result, the above-mentioned problems have been achieved.

[0044]

As a result of various studies on the radiation temperature measuring technique, the inventors of the present invention, on the contrary, positively utilize the emissivity which fluctuates according to the change of the surface condition of the process material, thereby making it possible to obtain the surface property value / characteristic value. We have found that it becomes possible to directly grasp. The present invention has been made based on the above findings.

In the present invention, a plurality of radiation thermometers installed along the continuous process line can be changed to arbitrary measurement heights and measurement angles, so that any of the process materials moved by each radiation thermometer can be changed. The surface position of can be measured, and the emissivity power ratio based on the actual measurement obtained from each radiation thermometer is correlated with the emissivity power ratio created in advance based on experimental data, theory, etc., and the physical and property values of the surface. The physical properties and characteristic values corresponding to the measured emissivity power ratio can be calculated from the data, and the measured height and measurement position of the radiation thermometer can also be used to calculate the measured position. The measurement position of the process material can be specified at any position on the line, and at the same time, the surface physical property value / characteristic value at the measurement position can be measured online.

Further, since the radiation thermometer can be set to the measurement height and the measurement angle corresponding to the specific values by designating the specific values of the surface physical property value / characteristic value, the measurement height at the measurement By calculating the measurement position using the measurement angle, the position of the process material having the specified specific surface physical property value / characteristic value can be determined.

Therefore, according to the present invention, the surface physical property value / characteristic value at an arbitrary position of the continuously moving process material can be directly measured, and the measuring position can be specified. By using the obtained measurement information, it is possible to control the continuous process line with high accuracy.

[0048]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram conceptually showing the overall structure of the measuring system according to the first embodiment of the present invention.

The measuring system of this embodiment can be applied to, for example, a hot rolling line or the like, and has basic devices 10A to 10N having the same functions as the basic device 10 shown in FIG.
Is installed along a continuous line (not shown), and when the output of each of these basic devices 10A to 10N is input to the output block 12, a predetermined calculation is executed and the measurement result is output. There is.

The basic devices 10A to 10N are vertical drive mechanisms 16 having radiation thermometers 14A to 14N and a function of detecting the height of the radiation thermometer and a height positioning function, respectively.
A to 16N, rotation driving mechanism 18A to 18N having a function of detecting the measurement angle of the radiation thermometer and an angle positioning mechanism
And control arithmetic units 20A to 20N. The functions of these basic devices 10A to 10N will be described below with reference to FIGS.

The radiation thermometer 14 can be moved up and down to an arbitrary position by a vertical drive mechanism 16 and can detect its height h, and can be rotated at an arbitrary angle by a rotary drive mechanism 18 and its measurement angle. θ can be detected.

Further, the radiation thermometer 14 measures the wavelength λ 1,
The brightness temperatures S1 and S2 measured for λ2 and the height h and the angle θ of the radiation thermometer 14 detected by the vertical drive mechanism 16 and the rotary drive mechanism 18, respectively, are input to the control calculation unit 20. There is.

The control calculation unit 20 has the configuration shown in FIG. 3, and the brightness temperatures S1 and S2 are applied to the equation (3) to calculate the emissivity ratio ε1 ^λ1 / ε2 ^λ2 (hereinafter abbreviated as Ku). And a data storage unit for storing correlation data (correlation function f) between the emissivity power ratio Ku and the oxide film thickness d created in advance by experimental data, theory, etc. off-line. 24, a conversion block 26 for deriving an oxide film thickness d corresponding to the actually measured emissivity power ratio Ku ^* from the data storage block 24, a measured height h from the vertical drive mechanism 16 and the rotary drive mechanism 18. Of the oxide film thickness d obtained in the conversion block 26 and the reference position to the measurement position obtained in the position calculation block 28. Distance Δ It outputs x and.

The control operation section 20 will be described in detail below.
The data storage block 24 stores the correlation functions f1, f2 ... For each measurement angle .theta.1, .theta.2 ... Representing the correlation data between the emissivity power ratio Ku and the oxide film thickness d as shown in FIG. ing.

As shown in FIG. 5, the correlation data shown in FIG. 4 is measured wavelength λ above the steel plate P moving in the arrow direction.
It is theoretically obtained by the following method when the radiation thermometer 14 is installed at 1, λ 2, measurement angle θ, and height h (actually, not only theory but experimentally for each measurement object). , Or it can be created by approximation from theory). The oxide film is exaggerated in the drawing.

When an oxide film is formed on the surface of the process material, consider a case where carbon steel, a single-layer oxide film, and air are arranged in this order from the bottom as shown in the schematic view of FIG. Therefore, first, the complex refraction index for each of air (1), oxide film (2), and carbon steel (3)
n ₁ ^* , n ₂ ^* , and n ₃ ^* are expressed by the following equation (6). Here, j = 1, 2, 3, and i represents an imaginary number.

N _j ^* = n _j + ik _j (6)

In the above equation (6), the real part n is usually called the "refractive index" and the imaginary part k is called the "absorption coefficient", and the complex index of refraction for the air, oxide film and carbon steel SPCC. Is given from literature values as follows.

N ₁ ^* = 1.0 + 0.0i n ₂ ^* = 2.5 + 0.65i n ₃ ^* = 2.0 + 2.1i

The complex reflection indices r ^{* at} the interface between the air and the oxide film surface (12 interfaces) and at the interface between the oxide film and carbon steel SPCC (23 interfaces) are given by Fresnel (7) Fresnel).

R _jk ^* = (n _j ^* −n _k ^* ) / (n _j ^* + n _k ^* ) (7)

The complex reflection index given by the above equation (7) and the oxide film thickness d have the following equations (8) and (9).

[0064] _{^{r * = {r 12 * +}} r 23 * · exp (i δ)} ÷ {1+ r 12 * · r 23 * · exp (i δ)} ... (8) δ = (4π / λi) ( n ₂ ^* d) cos θi (9)

An opaque mat such as a steel material
erials) has a transmittance of 0 and Kirchhof
Since the emissivity is equal to the absorptivity from the law of ff), the emissivity ε
Is calculated by the following equations (10) and (11).

Ε = 1-R (10) R = │r ^* │ ² (11)

The complex refraction index for the air, oxide film and carbon steel is applied to the above calculation formula to carry out the calculation, and the graph is obtained by plotting the oxide film thickness d on the horizontal axis and the emissivity power ratio Ku on the vertical axis. This is shown in FIG.

In FIG. 4, λ 1 = 0.9 as the measurement wavelength.
μm, λ2 = 1.1 μm, the measurement angle θ is 0 °,
The cases of 30 ° and 45 ° are schematically shown by a solid line, a broken line and a dashed line, respectively.

In the data storage block 24, the correlation data between the emissivity power ratio Ku and the oxide film thickness d for various measurement two wavelengths and measurement angles as shown in FIG.
The change range of d is stored.

As can be seen from FIG. 4, d is polyvalent with respect to Ku, but in the actual process, the change range of d at a certain measurement position is limited.

Therefore, on the surface of the process material, the wavelength λ1 = 0.9 μm, λ2 = 1.1 μm, and the measurement angle θ =
As a result of measurement with the radiation thermometer set to the condition of 45 °,
The emissivity exponentiation ratio Ku ^* of 1.1 is obtained,
In addition, the change range of d at that measurement position is a ₁ , a _{2 in the} figure.
If so, the oxide film thickness d at the measurement position is about 0.3.
It can be seen that it is μm.

In the conversion block 26, the correlation data extracted from the data storage block 24 and the correlation data extracted from the data emissivity power ratio Ku ^* are measured based on the above principle.
The oxide film thickness d is calculated from the change range of d.

In the position calculation block 28, as shown in FIG.
As shown in, using the height h of the radiation thermometer 14 at the time of measurement and the measurement angle θ, the measurement position x and the installation position of the radiation thermometer 14 from the following equations (12) and (13) Standard) x
The distance Δx from ₀ to the measurement position x is calculated.

X = x ₀ −h tan θ (12) Δx = h tan θ (13)

FIG. 7 shows a modification of the installation method of the radiation thermometer 14, where the measurement angles θ are the same and the measurement height is h ₁
And h ₂ , the distance from the reference x ₀ is Δ x
₁ and Δ x ₂ and Δ x ₁ = h ₁ tan θ and Δ x ₂
= Given by h ₂ tan θ.

FIG. 8 is a modification of the radiation thermometer installation method when both the measurement height and the measurement angle are changed. The distances Δ x ₁ and Δ x ₂ from the reference x ₀ to the measurement position are Δ x, respectively.
It is given by ₁ = h ₁ tan θ1 and Δ x ₂ = h ₂ tan θ2.

FIG. 9 shows an example in which two radiation thermometers 14 are installed close to each other, and the measurement angle θ is the same, and the vertical drive mechanism 16 can move between the measurement heights h ₁ and h _2. Also in this case, the difference (spacing) Δx ₁ and Δx ₂ between the measurement positions of the two radiation thermometers is h _i tan θ
It is given by (i = 1, 2).

As described above, by changing the measurement positions of the two radiation thermometers to arbitrary measurement heights h _i , the measurement position interval Δ x _i can be calculated by the following formula.

Δ x _i = h _i tan θ

FIG. 10 shows another modification in which two radiation thermometers are arranged close to each other. Here, the same measurement is performed with the two radiation thermometers fixed at an angle Φ. It is installed so that it can rotate around the axis of rotation (shown by the black dots) below the height h.

In this case, from the measurement angles θ11 and θ21 shown on the left side of the two radiation thermometers to the θ shown on the right side of the figure.
12 shows the state of being rotated by the rotary drive mechanism 18 to θ22, and the distance Δ between the measurement positions in the case of the left side and the right side in the figure.
x ₁ and Δ x ₂ can be calculated by the following equations, respectively.

Δ x ₁ = {(tan θ21−tan (θ21−Φ)} · h Δ x ₂ = {(tan θ22−tan (θ22−Φ)} · h

Further, in the case of the arrangement of the radiation thermometer 14 shown in FIG. 10, it is possible to set an arbitrary rotational position.
The measurement angle of one radiation thermometer at that setting position is θ
If the fixed angle between the two thermometers is Φ, the distance Δx _i between the measurement positions at that time can be calculated by the following equation.

Δ x _i = {(tan θi −tan (θi −Φ)} · h

Further, in the case of FIG. 10 described above, by making the height h also changeable, it is possible to set the distance Δx between the measurement positions over a wider range.

In the measuring system of this embodiment shown in FIG. 1, n basic devices 10A to 10N each having the above-described function are installed at a predetermined position along a continuous line process. ..

Therefore, the film thickness d1 to dn (indicated by dk in the figure) obtained by measuring the continuously moving process material at the position where each radiation thermometer 10A to 10N is installed is output through the output block 12. It becomes possible to do.

[0088] Also, in each radiation thermometer 10A to 10N, it can be based on the installation position x _0, and outputs the distance Δ x ₁ ~Δ x _n to the measurement position from the x ₀ to the output block 12. Therefore, this output block 12 uses the radiation thermometers based on the installation position x ₀ (different for each radiation thermometer) of each radiation thermometer 10A to 10N and the distance Δx _{1 to} Δx _n to the measurement position. , For example, the measurement position (indicated as x _{k in the} figure) with the line start end as the origin can be output, and by performing a predetermined calculation, any measurement position measured by each radiation thermometer 10A to 10N The distance between them (denoted as Δ x _{ij in the} figure) and the difference in film thickness generated between them (denoted as Δ d _{ij in the} figure) can be output.

The film thickness difference Δ d _ij , the distances Δ x _ij and x _k
Are respectively given by the following equations.

Δ d _ij = d _i −d _j Δ x _ij = x _i −x _j x _k = x ₀ −h _k tan θ _k

Here, i and j indicate that they were measured by different radiation thermometers, and k indicates that they were measured by any radiation thermometer.

According to the present embodiment described in detail above, the film thickness d of the continuously moving process material can be measured at any position on the continuous process line, and at the same time, the measured position can be detected. Moreover, the distance Δ x _ij between arbitrary measurement positions and the film thickness Δ d _ij changed (grown) while moving the distance can be measured. Therefore, the change pattern of the oxide film thickness in the process material P processed in the continuous process line can be known, and the oxide film thickness can be known.
Since the growth rate of d can also be known, it becomes possible to directly control the oxide film thickness d by adjusting the heating temperature and line speed based on this information.
As a result, the oxide film thickness can be controlled with extremely high precision, and the quality of the process material can be dramatically improved.

FIG. 11 is a block diagram conceptually showing the basic device 10 which is the essential part of the second embodiment according to the present invention.

The measurement system of this embodiment is the same as the first embodiment except that the basic device 10 having the function shown in FIG. 11 is adopted as the plurality of radiation thermometers 10A to 10N shown in FIG.
It is substantially the same as the embodiment.

The basic device 10 in this embodiment is similar to that shown in FIG. 2, and the radiation thermometer 1 for measuring the brightness temperature is used.
4, a vertical drive mechanism 16 for moving the radiation thermometer up and down, a rotary drive mechanism 18 for rotating the radiation thermometer, an emissivity exponentiation for calculating the emissivity exponentiation ratio Ku ^* using the brightness temperature measured by the radiation thermometer A ratio calculation block 22, a data storage block 24 for storing data created off-line, and a conversion block 2 for converting the emissivity power ratio Ku ^* into an oxide film thickness d.
6 and a position calculation block 28 for calculating a measurement position, and further a control block 30 shown in the drawing.

The set specific oxide film thickness d ₀ is input to the control block 30, and the control block 30 inputs the input specific thickness as shown in the enlarged view of FIG. It is determined whether or not the set film thickness d ₀ is equal to the actually measured oxide film thickness d obtained based on the actual measurement by the radiation thermometer 14 input from the conversion block 26. If the result of the determination is NO, the height
The vertical drive command that changes h to h + Δh is the vertical drive mechanism 1
6, the rotation drive command for changing the measurement angle θ to θ + Δθ is output to the rotation drive mechanism 18, respectively.

When the correction signals of h + Δh and θ + Δθ are input to the vertical drive mechanism 16 and the rotary drive mechanism 18, respectively, the radiation thermometer 14 is set to a predetermined change position based on the signals, and the process material is measured again. Then, based on the result, a new oxide film thickness d 1 measured at the measurement position changed by the conversion block 26 is calculated, and the oxide film thickness d 2 is output to the control block 30.

When the corrected oxide film thickness d is input to the control block 30, it is again compared with the set film thickness d _0. If NO again, the above operation is repeated, and if YES is determined, An output command is issued from the control block 30 to the position calculation block 28, and the position calculation block 28 uses the measurement height h of the radiation thermometer 14 and the measurement angle θ at the time of the measurement to obtain an expression of Δx = h tan θ. Then, the measurement position information Δx at that time (for example, the distance from the radiation thermometer position x ₀ ) is calculated, and the Δx is output.

According to this embodiment, by setting an arbitrary oxide film thickness d ₀ , it is possible to accurately find the position of the set film thickness d ₀ on the continuous process line.

Therefore, a control target value can be set as the set film thickness d ₀ , and it can be easily grasped from the obtained position information whether or not the target control is performed.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the examples, the measurement of the oxide film thickness, which is one of the surface characteristics, has been described, but the present invention is not limited to this. For example, other thin films such as a nitride film, refractive index, reflectance, As long as it has a correlation with an emissivity power ratio, such as an optical property value such as an absorptance, an emissivity, and a transmittance, it can be applied to various surface property values / characteristic values.

Further, the function of converting the emissivity exponentiation ratio calculated by the calculation block 22 into the emissivity ratio ε 1 / ε 2 by the equation (5) and further calculating the surface temperature T by the equation (4). Also, the measurement temperature T may be measured at the same time.

[0104]

As described above, according to the present invention, it becomes possible to accurately measure the surface physical property value / characteristic value of the process material and its measurement position at any position of the continuous process line. It is possible to dramatically improve the accuracy of process control.

[Brief description of drawings]

FIG. 1 is a block diagram conceptually showing the overall structure of a measuring system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a basic device that constitutes the measurement system.

FIG. 3 is a block diagram showing functions of the basic device.

FIG. 4 is a diagram showing an example of the correlation between the emissivity power ratio and the oxide film thickness.

FIG. 5 is an explanatory diagram showing a measurement principle according to the present invention.

FIG. 6 is a partial cross-sectional view showing an enlarged surface state of carbon steel.

FIG. 7 is another explanatory diagram showing the measurement principle according to the present invention.

FIG. 8 is still another explanatory view showing the measurement principle according to the present invention.

FIG. 9 is still another explanatory view showing the measurement principle according to the present invention.

FIG. 10 is still another explanatory view showing the measurement principle according to the present invention.

FIG. 11 is a block diagram showing a main part of a second embodiment according to the present invention.

FIG. 12 is a block diagram showing an enlarged function of a determination block included in the main part.

FIG. 13 is a diagram showing an emissivity spectrum of a low temperature surface without an oxide film.

FIG. 14 is a diagram showing an emissivity spectrum of a medium-temperature surface without an oxide film.

FIG. 15 is a diagram showing an emissivity spectrum of a surface immediately after generation of an oxide film.

FIG. 16 is a diagram showing a surface emissivity spectrum during growth of an oxide film.

FIG. 17 is a diagram showing an emissivity spectrum of a surface after formation of a passive oxide film.

FIG. 18 is a diagram showing an emissivity spectrum of two adjacent wavelengths on a surface having no oxide film.

FIG. 19 is a diagram showing an emissivity spectrum of two adjacent wavelengths after generation of a surface oxide film.

FIG. 20 is a diagram showing a correlation of spectral emissivity of two wavelengths.

[Explanation of symbols]

 10, 10A-10N ... Basic device, 12 ... Output block, 14, 14A-14N ... Radiation thermometer, 16, 16A-16N ... Vertical drive mechanism, 18, 18A-18N ... Rotation drive mechanism, 20 ... Control calculation part, 22 ... Emissivity power ratio calculation block, 24 ... Data storage block, 26 ... Conversion block, 28 ... Position calculation block, 30 ... Control block.

Claims (2)

[Claims] 1. A surface physical property / characteristic value measuring system for a continuous process material, wherein a plurality of radiation thermometers are installed along a continuous process line, wherein each radiation thermometer has at least one of measurement height and measurement angle. It is variable, and its measurement height and measurement angle are made detectable, and the brightness temperatures S1 and S2 measured at two different wavelengths λ1 and λ2 by each radiation thermometer are used. Emissivity power ratio calculating means for calculating the emissivity power ratio, and ε1 ^λ1 / ε2 ^λ2 = exp {C2 (1 / S2 -1 / S1)} (C2: second constant of Plank) from experimental data, theory or theory. Data storage means for storing correlation data between surface physical property values / characteristic values and emissivity power ratios created offline based on the approximation of Eq. The above phase A conversion means for converting the physical property value / characteristic value based on the relational data, and a position calculation means for calculating the measurement position based on the measurement height and the measurement angle of each radiation thermometer at the time of measurement. A system for measuring the physical and physical values of surfaces of continuous process materials. 2. The surface of a continuous process material according to claim 1, wherein the radiation thermometer can be set to a measurement height and a measurement angle corresponding to specified surface physical property values and characteristic values. Physical property / characteristic value measurement system.