JPH0530741U - Measuring device for surface temperature distribution of steel strip - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the emissivity of an object is unknown, correct it to obtain an accurate temperature distribution. [Composition] The thermal radiant energy distribution on the surface of the object is measured within the depth of field, and the surface temperature of the object is calculated by Planck's radiation law from this measured value and the measured wavelength emissivity of the object, A first temperature measuring means for determining a temperature; and a second temperature measuring means for measuring a temperature at an arbitrary point within a measurement area of the object surface measured by the first temperature measuring means, the first temperature measuring means By the temperature obtained by the measuring means and the temperature measured by the second temperature measuring means,
An apparatus for measuring the surface temperature distribution of a steel strip, characterized in that the measuring wavelength emissivity of the first temperature measuring means is corrected.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention corrects the measured wavelength emissivity of an object such as a steel strip being annealed so as to obtain a temperature distribution as close to the true temperature distribution as possible. The present invention relates to a distribution measuring device.

[0002]

[Prior Art]

 A device for measuring the surface temperature distribution of an object, such as a steel strip, uses a rotating mirror or a vibrating mirror to scan each measurement point, and uses PbS or Si as a temperature detector. Various types are used depending on the measurement temperature range. However, the principle is that most of the temperature is obtained from the thermal energy in a certain wavelength range.

That is, the wavelength distribution of heat energy radiated from a black body having a temperature of T ° K is obtained by Equation 1 according to Planck's radiation law.

[0004]

[Equation 1]

The emissivity ελ of an object is defined as the ratio of black body radiation of the same temperature at a certain wavelength λ, as shown in equation 2.

[0006]

[Equation 2]

Further, in the radiation thermometer, the temperature is obtained not by the emissivity for each wavelength but by the emissivity εΔλ in the wavelength section preset in the radiation thermometer.

The emissivity εΔλ over this specific wavelength section is obtained by the equation 3.

[0009]

[Equation 3]

That is, the radiation thermometer is

[0011]

[Equation 4]

The temperature T is obtained from the relationship of, and the emissivity εΔλ must be known as a condition.

[0013]

[Problems to be solved by the device]

 However, it is difficult to specify the emissivity εΔλ of the measured object, and despite the fact that there are many documents regarding emissivity data, in actual measurement, those values do not fall within the range of reference values. In many cases, it is the fact that no reliable value can be found.

Therefore, an object of the present invention is to provide a surface temperature distribution measuring device capable of automatically correcting the temperature distribution even if the emissivity εΔλ is unknown. ..

[0015]

[Means for Solving the Problems]

 The present invention measures the thermal radiant energy distribution on the surface of an object within the depth of field, and calculates the surface temperature of the object by Planck's radiation law from this measured value and the measured wavelength emissivity of the object. A first temperature measuring means for determining a temperature, and a second temperature measuring means for measuring the temperature of an arbitrary point in the measurement area of the object surface measured by the first temperature measuring means, The surface of the steel strip characterized in that the measured wavelength emissivity of the first temperature measuring means is corrected by the temperature obtained by the first temperature measuring means and the temperature measured by the second temperature measuring means. It is a temperature distribution measuring device.

The present invention also provides that the corrected measurement wavelength emissivity has the same value in all measurement regions measured by the first temperature measuring means on the object surface, and the thermal radiation energy of each measurement region is From this, the surface temperature of the object is calculated according to Planck's radiation law, and the temperature distribution is obtained.

Further, the present invention is characterized in that the second temperature measuring means is a two-color thermometer.

[0018]

[Action]

 According to the present invention, the emissivity of an object such as a steel strip is constant at the same location as any one point of the surface temperature distribution measured by the first temperature measuring means. The temperature is measured by a second temperature measuring means which has been confirmed, for example, a two-color thermometer, the measured value is regarded as the true temperature of the object, and the emissivity at that point is calculated to obtain the first temperature. The surface temperature distribution is obtained with the emissivity on the measurement surface of the measuring means as all the emissivities.

Further, according to the present invention, it is assumed that the measured wavelength emissivity obtained and corrected as described above has the same value in the measurement areas of all the object surfaces measured by the first temperature measuring means. From the thermal radiation energy distribution of each measurement area, the surface temperature of the object is calculated according to Planck's radiation law to obtain the temperature distribution.

Further according to the invention, a two-color thermometer is used as the second temperature measuring means.

[0021]

【Example】

 FIG. 1 is a system diagram showing the overall configuration of an embodiment of the present invention. For example, in the annealing line, the steel strip 1 which is an object is run in the direction of arrow A and annealed, and in order to measure the surface temperature of this steel strip 1, the surface temperature distribution measuring device according to the present invention is used. This surface temperature distribution measuring device basically measures the thermal radiation energy distribution on the surface of the steel strip within the depth of field, and from this measurement value and the measured wavelength emissivity ελ of the object, the Planck's radiation Within the measurement area of the surface of the steel strip measured by the scanning radiation thermometer 2 which is the first temperature measuring means for calculating the surface temperature of the steel strip by the law to obtain the temperature distribution. By a two-color thermometer 3 which is a second temperature measuring means for measuring the temperature at an arbitrary point of the above, an arithmetic processing means 4 for arithmetically processing the output from each thermometer 2, 3, and an output from the arithmetic processing means. And a display unit 5 for displaying the temperature distribution, which is realized by a cathode ray tube or the like. The steel strip 1 is, for example, an annealed stainless steel strip.

The scanning radiation thermometer 2 has a detection unit 6 provided in the length of the traveling path of the steel strip 1 and a processing circuit 7 to which an output from the detection unit 6 is input. In, the temperature is converted into the emissivity εΔλ = 1 and output as planar temperature distribution data. That is, since the measurement wavelength λ is known, the temperature T is obtained by the equation 5 described later. Further, the two-color thermometer 3 has a detection unit 8 provided in the vicinity of the traveling path of the steel strip 1, and a processing circuit 9 that receives an output from the detection unit and converts the temperature. The detection unit 8 measures the thermal radiation energy at the central measurement point S1 within the measurement range S of the scanning radiation thermometer 2 and converts the temperature into the processing circuit 9.

FIG. 2 is a system diagram showing a simplified configuration of the scanning radiation thermometer 2. The scanning radiation thermometer 2 scans the infrared rays emitted from the steel strip 1 by a so-called mechanical-optical means and makes them incident on the lens 10, and the collected infrared rays are detected by a detecting element 11. The detected signal is converted into an electric signal in time series, the signal is amplified by the amplifier 12, the wavelength is converted into the visible light region by the signal processing circuit 13, and the wavelength is converted into the visible light region from the signal processing circuit 13. The temperature distribution is displayed on the display means 5 according to the output signal.

As shown in FIG. 3, the optical path length between the surface of the steel strip 1 and the lens 10 includes a condenser lens 17, a vertical scanning prism 15 which constitutes the scanning means 14, and a horizontal scanning prism 15. The scanning prism 16 is interposed. The vertical scanning prism 15 is rotationally driven around a horizontal rotation axis line, and the horizontal scanning prism 16 is rotationally driven around a vertical rotation axis line so that the surface of the steel strip 1 extends in the width direction and the traveling direction of the steel strip 1. It is configured to scan.

FIG. 4 is a system diagram showing a simplified configuration of the two-color thermometer 3. The two-color thermometer 3 is a thermometer that obtains the radiance ratio at two different measurement wavelengths λ1 and λ2, and is configured to show the true temperature regardless of the emissivity when the measurement surface is a gray body. ing. That is, the light from the measurement point S1 is condensed via the lens 20, the light incident through the diaphragm 21 is reflected by the reflecting mirrors 22 and 23, and the measurement point S1 is visually observed through the eyepiece lens 24. You can check. Further, the infrared rays incident on the two-color thermometer 3 are detected by a detection element 28 through wavelength filters 26, 27 having different wavelengths provided on the rotary plate 25, and the detection signal is detected by an AGC (auto gain control) amplifier 29. Is amplified. The one wavelength filter 26 passes light in the wavelength λ1 band, and the other wavelength filter 27 passes light in the wavelength λ2 band. That is, as shown in FIG. 5, when the wavelength at which the amount of light passing through the filter 26 reaches the maximum value G is λ1, the wavelength when the maximum value G is discriminated by 1/2, for example. The section is Δλ1. Similarly, the wavelength section Δλ2 is also specified for the wavelength λ2 at which the amount of light passing through the filter 27 has the maximum value.

The output of the AGC amplifier 29 is input to the separation circuit 30, and the gain is controlled by the AGC amplifier 29 based on the synchronization signal from the synchronization signal generator 31 and then separated into two signal components V1 and V2. Then, the gain of one signal V1 is corrected by the emissivity ratio correction circuit 32, and the signal V1 is input to one input terminal of the comparison circuit 34 via the zero clamp circuit 33. The discrimination level signal V 0 is inputted to the other input terminal of the comparison circuit 34, the level of the signal V 2 is discriminated, and the signal V 2 is inputted again to the AGC amplifier 29 for gain control. When the measured temperature falls below the lower limit, the ratio calculation becomes unstable due to insufficient incident flux, so the signal level is detected and the output is forcibly clamped to the zero point, and this unclamped signal is output to the output terminal 35. To be done.

The two-color thermometer 3 can obtain the temperature of the steel strip 1, which is an object, from the thermal radiation energy ratio R (T) in two different measurement wavelength bands λ1 and λ2. Is shown by the equation 5.

[0028]

[Equation 5]

In Equation 5, even if the emissivities εΔλ1 and εΔλ2 of the steel strip 1 are unknown, if the wavelength sections Δλ1 and Δλ2 are known and εΔλ1 / εΔλ2 is constant, the thermal radiation energy ratio R (T ) Indicates that it can always be a function of temperature T. That is, if the thermal radiation energy ratio R (T) is measured, it can be obtained by back-calculating the temperature T. Therefore, the two-color thermometer 3 selects the wavelength sections Δλ1 and Δλ2 as wavelengths as close as possible, and establishes the relationship that εΔλ1 / εΔλ2 = constant in the minimum wavelength section.

For this verification, the first material characteristic, that is, the grain size or hardness and the indicated value of the two-color thermometer are checked several times per coil to confirm that they are within the control range. . The relationship between the temperature and the hardness H _v is shown in FIG. 6, and it is confirmed that the lines L1 and L 2 are within the control range. Further, the relationship between the material temperature and the grain size is shown in FIG. 7, and it is confirmed that it is within the control range sandwiched between the line L3 and the line L4. In this way, if the relationship between temperature and hardness or the relationship between temperature and crystal grain has a certain correlation and is within the control range, it can be considered that the indicated value of the two-color thermometer 3 is close to the true value. .

Next, the emissivity εΔλ of the scanning radiation thermometer 2 is calculated by the equation 6 using the indicated value of the two-color thermometer 3 as the true temperature of the steel strip 1.

[0032]

[Equation 6]

The denominator in Equation 6 can be obtained by substituting the temperature measured by the two-color thermometer 3 into the temperature T1. Therefore, Equation 6 is expressed as Equation 7.

[0034]

[Equation 7]

In Equation 7, since τλ, aλ and Δλ are eigenvalues, the emissivity εΔλ can be derived.

In the arithmetic processing means 4, all temperature values T2 which are temperature data converted and stored as emissivity εΔλ = 1 and the emissivity εΔλ obtained by the equation (5). Can be substituted into the following equation 8 to obtain the temperature T3.

[0037]

[Equation 8]

In this way, a corrected temperature distribution can be obtained by calculating and obtaining the temperature T3 of the entire measurement surface of the steel strip 1 which is derived by the equation 8.

In this way, according to the present invention, it is possible to manage the displacement of the temperature distribution of the object in a state that is close to the true value, and therefore, for example, the temperature distribution of the annealing furnace is abnormal, or direct heating is used. Anomalies in the burner of the annealing furnace can be detected early. Further, in order to reduce the temperature distribution of the surface material of the steel strip 1, by adjusting the frame length of the direct-fired annealing furnace, it becomes possible to uniformly anneal the steel strip in the width direction, and the temperature distribution of the steel strip and the strip It is possible to analyze the relationship with the shape and contribute to the improvement and stability of the steel strip quality.

[0040]

[Effect of the device]

 As described above, according to the present invention, the temperature of an arbitrary point in the measurement area of the object surface measured by the first temperature measuring means is measured by the second temperature measuring means and is obtained by the second temperature measuring means. Since the measured wavelength emissivity of the first temperature measuring means is corrected by the temperature distribution measured by the second temperature measuring means and the temperature measured by the second temperature measuring means, the surface temperature distribution of an object such as a steel strip can be calculated. It is possible to obtain a value that is as close as possible to the true surface temperature distribution, and it is possible to detect abnormalities in the temperature distribution of an object at an early stage.

[Brief description of drawings]

FIG. 1 is a system diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a system diagram showing a configuration of a scanning radiation thermometer 2.

FIG. 3 is a diagram showing a specific configuration of a scanning unit 14.

FIG. 4 is a system diagram showing a specific configuration of a two-color thermometer 3.

FIG. 5 is a graph showing a relationship between light having a wavelength λ1 that passes through a filter and its wavelength section Δλ1.

FIG. 6 is a graph showing a relationship between temperature and hardness for showing that the emissivity ratio εΔλ of the two-color thermometer 3 is constant.

FIG. 7 is a graph showing the relationship between temperature and crystal grain size, which shows that the emissivity ratio of the two-color thermometer 3 is constant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel strip 2 Scanning radiation thermometer 3 2 Color thermometer 4 Arithmetic processing means 5 Display means 6,8 Detection part 7,9 Processing circuit

Claims (3)

[Scope of utility model registration request] 1. The thermal radiation energy distribution on the surface of an object is measured within the depth of field, and the surface temperature of the object is calculated from the measured value and the measured wavelength emissivity of the object by Planck's radiation law. A first temperature measuring means for determining a temperature, and a second temperature measuring means for measuring a temperature at an arbitrary point within a measurement area of the object surface measured by the first temperature measuring means. Of the temperature measured by the second temperature measuring means and the temperature measured by the second temperature measuring means.
An apparatus for measuring the surface temperature distribution of a steel strip, which is characterized in that the measuring wavelength emissivity of the temperature measuring means is corrected. 2. Assuming that the corrected measurement wavelength emissivity has the same value in all measurement areas measured by the first temperature measuring means on the surface of the object, from the thermal radiation energy of each measurement area, the Planck 2. The surface temperature distribution measuring device for a steel strip according to claim 1, wherein the surface temperature of the object is calculated by the radiation law of 1. 3. The surface temperature distribution measuring device for a steel strip according to claim 2, wherein the second temperature measuring means is a two-color thermometer.