KR20220016403A - sleeve still surface temperature measuring apparatus and measuring method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for measuring the temperature of high-temperature sleeve steel without contact based on laser ultrasonic detection and wave number signal processing. The apparatus includes: a laser beam radiation part radiating an impact laser beam to impact points of a scan position so as to generate a sound wave to the surface of high-temperature sleeve steel; a laser beam-based measurement part radiating a reference laser beam to the high-temperature sleeve steel, and receiving a detection laser beam reflected from the high-temperature sleeve steel to measure ultrasonic wave information; and a calculation part calculating the temperature of the surface of the high-temperature sleeve steel by using the ultrasonic wave information measured by the laser beam-based measurement part. The calculation part places a received ultrasonic signal as three-dimensional data to be matched with an excitation point corresponding to each impact point of the scan position, acquires an ultrasonic propagation image placed in reverse order in a temporal direction with respect to the placed three-dimensional data, derives a representative response to the ultrasonic propagation image, extracts a representative wave number after converting the derived representative response into a wave number area signal, and extracts a temperature value corresponding to the extracted representative wave number from a lookup table to calculate the temperature. In accordance with the apparatus and method for measuring the temperature of high-temperature sleeve steel without contact based on laser ultrasonic detection and wave number signal processing, there can be an advantage of precisely measuring the temperature of the surface of the high-temperature sleeve steel by using a laser.

Description

Laser ultrasonic flaw detection and wavenumber signal processing-based non-contact high temperature sleeve steel temperature measuring apparatus and method thereof {sleeve still surface temperature measuring apparatus and measuring method thereof}

The present invention relates to an apparatus for measuring the temperature of a non-contact high-temperature sleeve steel based on laser ultrasonic flaw detection and wavenumber signal processing and a method for measuring the temperature thereof. To a non-contact high temperature sleeve steel temperature measuring device and method for measuring the temperature based on ultrasonic flaw detection and wave number signal processing.

As a contact-type temperature measurement method, there are largely a method using a thermo-couple and a method of measuring resistance change according to temperature. Since both methods utilize the heat conduction phenomenon by conduction, close contact with the temperature measurement object is required, and a waiting time of about 30 seconds is required for the measurement object heat to be sufficiently conducted. The contact temperature measurement method has a disadvantage in that it cannot be applied when the measurement target is sensitive to contact with an external material, is moving, or is placed in an environment that is inaccessible.

In particular, in the case of a plate-shaped sleeve still produced through a rolling process in the steelmaking process, it is difficult to apply a contact measurement method because it is continuously moving and the surface is high.

To overcome these difficulties, a non-contact temperature measurement method was developed. A conventional non-contact temperature measurement method utilizes the phenomenon that the infrared energy emitted by an object varies with temperature. The infrared thermometer consists of a lens, a filter, an optical detector, an amplifier circuit and a linear circuit. The lens of the infrared thermometer collects the light energy emitted from the measurement point on the target surface, and the filter passes only the light of the wavelength that the detector can detect from the light, which is measured by the detector. Since the signal measured by the detector is very small, it is amplified while passing through the amplifier, and this signal is converted into a temperature value in consideration of the emissivity of the object in the linearization circuit. Infrared temperature measurement method can measure temperature within 5 seconds and has the advantage of being non-contact, and is currently being used in many industries.

Meanwhile, ultrasonic flaw detection technology is used for structural health monitoring and non-destructive testing. Ultrasound is widely used to detect surface or internal defects of a measurement object because it propagates quickly throughout the measurement object and responds sensitively to small changes in physical properties. When the temperature change occurs, the ultrasonic behavior changes as the mechanical properties of the medium change, so it is possible to measure the temperature through ultrasonic flaw detection. Although Korean Patent Registration No. 10-0467985 discloses an ultrasonic temperature measuring device, it is difficult to manufacture because a sensing element made of a tungsten alloy is applied, and it is difficult to obtain temperature distribution information while scanning a certain area.

The present invention was devised to improve the above problems, and a non-contact high temperature sleeve steel temperature measuring apparatus and method for measuring the temperature of a non-contact high temperature sleeve steel based on laser ultrasonic flaw detection and wave number signal processing capable of measuring the temperature of the surface of the sleeve steel using a laser. Its purpose is to provide

In order to achieve the above object, the non-contact high temperature sleeve steel temperature measuring device based on laser ultrasonic flaw detection and wave number signal processing according to the present invention irradiates an impact laser beam to the impact points of the scan position so as to generate sound waves on the surface of the high temperature sleeve steel. and a laser beam irradiation unit; A reference laser beam is irradiated to the high-temperature sleeve steel at a measurement position different from that of the impact laser beam, and a detection laser beam reflected from the high-temperature sleeve steel is received from the high-temperature sleeve steel. a laser beam-based measuring unit for measuring ultrasonic information generated in response to irradiation of an impact laser beam; Controlling the driving of the laser beam irradiator so that the impact laser beam from the laser beam irradiator is irradiated to the high-temperature sleeve steel, and calculating the temperature of the surface of the high-temperature sleeve steel using the ultrasonic information measured from the laser beam-based measuring unit and a calculator that arranges the received ultrasound signal as three-dimensional data to match the excitation point corresponding to each impact point of the scan position, and arranges the three-dimensional data in reverse order in the time direction. Acquire an ultrasonic wave image, derive a representative response corresponding to the phase difference between the representative frequency signal and the time domain signal of each excitation point for the obtained ultrasonic wave image, convert the derived representative response into a wavenumber domain signal, and then represent The wavenumber is extracted, and the temperature value corresponding to the extracted representative wavenumber is extracted from the lookup table to calculate the temperature.

Preferably, the laser beam irradiation unit comprises: a first laser light source for emitting the impact laser beam; and a scan unit for adjusting a path so that the impact laser beam emitted from the first laser light source is irradiated to an impact point of a set scan position, wherein the laser beam-based measuring unit includes a second laser light source emitting the reference laser beam ; a first beam splitter for dividing the reference laser beam into a first path and a second path in a direction orthogonal to the first path; a second beam splitter for passing the light traveling through the first path and reflecting the light reflected from the high-temperature sleeve steel to a third path that is different from the second path; a first mirror for reflecting the light traveling through the second path to a fourth path parallel to the first path; The light that is reflected from the first mirror and proceeds through the fourth path and the light that proceeds through the third path is disposed at a position where it can be incident and the light that proceeds through the fourth path is transmitted to the fifth path a third beam splitter that transmits the light and reflects the light traveling through the third path to travel through the fifth path; and a photodetector that detects the interference light traveling through the fifth path from the third beam splitter and provides it to the calculator.

In addition, in order to achieve the above object, the method for measuring the temperature of the non-contact high temperature sleeve steel temperature measuring device based on laser ultrasonic flaw detection and wave number signal processing according to the present invention scans the impact laser beam so as to generate sound waves on the surface of the high temperature sleeve steel. A laser beam irradiator that irradiates to the impact points of , and a reference laser beam is irradiated to the high-temperature sleeve steel at a measurement position different from that of the impact laser beam, and is reflected from the high-temperature sleeve steel to the reference laser beam A laser beam-based measuring unit that receives a detection laser beam and measures ultrasonic information generated in response to irradiation of the impact laser beam from the high-temperature sleeve steel, and the impact laser beam from the laser beam irradiation unit is irradiated to the high-temperature sleeve steel In the temperature measuring method of a temperature measuring device having a calculator for controlling the driving of the laser beam irradiator so as to be able to, and calculating the temperature of the surface of the high-temperature sleeve steel using the ultrasonic information measured from the laser beam-based measuring unit, . arranging the received ultrasound signal as three-dimensional data according to the excitation point corresponding to each impact point of the scan position; me. acquiring ultrasonic wave images arranged in a reverse order in a time direction with respect to the arranged 3D data; All. deriving a representative response corresponding to a phase difference between a representative frequency signal and a time-domain signal of each excitation point with respect to the obtained ultrasonic wave image; La. converting the derived representative response into a wavenumber domain signal and then extracting a representative wavenumber; mind. and calculating a temperature by extracting a temperature value corresponding to the extracted representative wavenumber from a lookup table in which a temperature value corresponding to the representative wavenumber is recorded.

According to the laser ultrasonic flaw detection and wavenumber signal processing-based non-contact temperature measuring device and temperature measuring method of the high temperature sleeve steel according to the present invention, it is possible to precisely measure the temperature of the high temperature sleeve steel surface using a laser.

1 is a view showing an apparatus for measuring the temperature of a non-contact high-temperature sleeve steel based on laser ultrasonic flaw detection and wavenumber signal processing according to the present invention;
Figure 2 is a perspective view showing an example of the configuration of the laser beam irradiation unit of Figure 1,
3 is a view showing a configuration example of the laser beam-based measuring unit of FIG. 1,
Figure 4 is a view showing an example of the scan point of the impact laser beam in the laser beam irradiation unit of Figure 1,
5 is a flowchart showing a temperature calculation process of the temperature measuring device of FIG. 1;
6 is a view for explaining a process of rearranging the measured ultrasonic wave signal in three dimensions;
7 is a view for explaining a process of generating an ultrasonic wave image from 3D data rearranged through the process of FIG. 6;
8 is a view for explaining a process of deriving a representative response from the ultrasonic wave image of FIG. 7;
9 is a diagram for explaining a process of deriving a representative wave number from the representative response of FIG. 8;
FIG. 10 is a graph showing the relationship between the representative wave number used to measure the temperature in the calculator of FIG. 1 and the temperature.

Hereinafter, an apparatus for measuring the temperature of a non-contact high temperature sleeve steel based on laser ultrasonic flaw detection and wavenumber signal processing and a method for measuring the temperature according to a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a view showing an apparatus for measuring the temperature of a non-contact high-temperature sleeve steel based on laser ultrasonic flaw detection and wavenumber signal processing according to the present invention.

1, the laser ultrasonic flaw detection and wavenumber signal processing-based non-contact high temperature sleeve temperature measuring apparatus 100 according to the present invention includes a laser beam irradiation unit 110, a laser beam-based measurement unit 150, and a calculation unit 170. and a display unit 180 .

The laser beam irradiation unit 110 irradiates an impact laser beam to generate sound waves on the surface of the high temperature sleeve steel 10 .

Here, the high-temperature sleeve steel 10 refers to steel manufactured in a plate shape by refining molten iron eluted from the blast furnace 20 during the steelmaking process and passing through a rolling roller, and is transported through a conveyor belt.

A detailed structure of the laser beam irradiation unit 110 will be described with reference to FIG. 2 . The laser beam irradiation unit 110 is controlled by the calculation unit 170 and the first laser light source 112 for emitting the impact laser beam 112a, and the impact laser beam 112a emitted from the first laser light source 112 is It consists of a scan unit 120 that adjusts the path to be irradiated to the impact points of the set scan position.

The first laser light source 112 applies an impact to the high-temperature sleeve steel 10 to have a power for emitting the impact laser beam 112a to a degree that ultrasonic waves can be generated from the high-temperature sleeve steel 10 . The first laser light source 112 is controlled by the calculator 170 so that the impact laser beam 112a is emitted only when the impact laser beam 112a is emitted.

The scan unit 120 may be constructed in a conventional structure, and the angle of the first reflector 121 may be adjusted for the light emitted from the first laser light source 112 in the irradiation direction with respect to the first direction based on the irradiation surface. The first direction adjuster 123 to adjust, and the first to adjust the angle of the second reflector 122 with respect to the second direction orthogonal to the first direction with respect to the light that travels through the first reflector 121 It may be constructed as a two-way adjuster 122 . Here, the first and second direction regulators 123 and 124 are controlled by the calculation unit 170, and a motor for rotationally driving a rotation shaft extending from the rotation center of the first and second reflectors 121 and 122 is provided. Of course, a structure for rotating the first and second reflectors 121 and 122 in a manner different from the illustrated example may be applied.

The laser beam irradiator 110 is controlled by the calculation unit 170 so that the impact laser beam 112a is emitted at the set interval of generation of the impact laser beam 112a, and the scan unit 120 is to the calculation unit 170. Controlled to adjust the path so that the impact laser beam 112a is irradiated to the impact point of the scan position set for the scan area. As an example, the impact laser beam 112a irradiated by the scan unit 120 may be constructed to be sequentially irradiated along the arrow direction to the impact point of the scan position indicated by reference numeral 116 as shown in FIG. 4 . . In this case, temperature information for a plurality of impact points can be extracted.

The laser beam-based measuring unit 150 irradiates a reference laser beam 152 to the high-temperature sleeve steel 10 at a measurement position m different from the irradiation position 116 of the impact laser beam 112a, and the high-temperature sleeve steel ( 10) receives the detection laser beam reflected with respect to the reference laser beam 152, measures the sound wave information generated in response to the irradiation of the impact laser beam 112a from the high-temperature sleeve steel 10, and with reference to FIG. Explain.

The laser beam-based measuring unit 150 includes a second laser light source 151 , a first beam splitter 161 , a second beam splitter 162 , a first mirror 155 , and a third beam splitter 163 . , a photodetector 165 is provided.

The second laser light source 151 emits a reference laser beam. The second laser light source 151 is controlled to continuously emit a reference laser beam in the measurement mode.

The first beam splitter 161 divides the reference laser beam emitted from the second laser light source 151 into a first path 157 and a second path 158 in a direction orthogonal to the first path 157. print out

Reference numeral 153 denotes an optical modulator installed on the first path 157 to modulate a light beam, and mechanical and physical modulators and other modulators may be applied.

The second beam splitter 162 passes the light traveling through the first path 157 and the light reflected from the high-temperature sleeve steel 10 passes through the third path 159 parallel to the second path 158 . reflect

The first mirror 155 reflects the light traveling through the second path 158 to the fourth path 160 parallel to the first path 157 .

The third beam splitter 163 is disposed at a position where both the light that is reflected from the first mirror 155 and travels through the fourth path 160 and the light that travels through the third path 159 can be incident. The light traveling through the fourth path 160 is transmitted through the fifth path 164 , and the light traveling through the third path 159 is reflected to proceed to the fifth path 164 to generate interference light. do.

The photodetector 165 detects the interference light traveling from the third beam splitter 163 to the fifth path 164 and provides it to the calculator 170 .

The calculator 170 controls the driving of the laser beam irradiator 110 so that the impact laser beam from the laser beam irradiator 110 is irradiated to the high-temperature sleeve steel 10, and the photodetector ( 165), obtains sound wave information from the information received, calculates the temperature of the surface of the high temperature sleeve steel 10 by using the sound wave information, and displays the calculated temperature information through the display unit 180 .

In this case, the calculator 170 applies the impact laser to the plurality of impact points 116 set along the first direction (X) and the second direction (Y) orthogonal to the first direction (X) with respect to the scan target area. The laser beam irradiator 110 is controlled so that the beam 112a is irradiated at a set excitation interval. Here, the excitation frequency is 50 KHz or more, the excitation time, which is the time the impact laser beam is irradiated, is within 1/1000 second, and the excitation interval, which is the interval between the impact points 116, can be applied within 1 mm, and appropriately according to the measurement environment. Adjust and change.

Next, the calculation unit 170 measures the temperature using the ultrasonic signal received from the laser beam-based measurement unit 150 after the impact laser beam 112a is irradiated to each of the impact points 116 and performs the process It will be described with reference to FIG. 5 .

First, the calculator 170 arranges the received ultrasound signal as three-dimensional data according to the excitation point corresponding to each impact point 116 of the scan position (step 210). Here, the three-dimensional data refers to data in which two-dimensional ultrasound signals corresponding to excitation points are arranged in three dimensions along the time axis. In addition, in order to obtain a high-quality ultrasound signal, a sampling frequency of 2 MHz or more for the ultrasound signal is applied. In addition, as can be understood through FIG. 6 , the ultrasound signal received from the laser beam-based measuring unit 150 is data arranged in one dimension, and the amount of time required for excitation of individual excitation points for the data signal arranged in one dimension is After separating them in time, they are rearranged according to the position of each excitation point on the scan path. For reference, in FIG. 4, 9 excitation points are applied in 9 vertical columns, but in FIG. 6, in order to avoid the complexity of the drawing, 5 in 5 horizontal columns and 5 vertical columns are exemplified.

Next, as shown in FIG. 7 , ultrasonic wave images arranged in the reverse order in the time direction with respect to the 3D data generated in the previous process are acquired (step 220).

The principle of generating an ultrasonic wave image through this process is as follows. In principle, in order to acquire an ultrasonic wave image without distortion, it is necessary to measure the inspection area at the same time as in general camera photography. However, since ultrasonic signal measurement cannot be performed with camera equipment, signals for multiple measurement points in the inspection area are acquired through laser equipment to generate images. In ultrasonic flaw detection, if excitation is performed at the same location with the same energy and input signal, it can be assumed that the ultrasonic propagation pattern generated in the first half area is the same every time excitation is performed. Therefore, even if the measurement position is changed, if the excitation and the measurement time coincide with each other, the ultrasound signal acquired at each measurement point can be regarded as acquiring the ultrasound signal of all areas at the same time as when photographing with a camera. The principle of generating an ultrasonic wave image after scanning by performing excitation at a fixed position and moving the measurement point is as above. Conversely, in the ultrasonic flaw detection performed in the present invention, the measuring point is fixed and the excitation point is moved. Therefore, based on the time reversal method theory, if the signal acquired at the measuring point is reproduced in the reverse order of time, the same signal as when the measuring point and the excitation point are exchanged can be obtained. can be obtained

Next, a representative response corresponding to the phase difference between the representative frequency signal and the time domain signal of each excitation point is derived for the obtained ultrasonic wave image (step 230). Since the signal by excitation is a square pulse waveform, it contains various frequencies. Therefore, for effective signal processing, frequency filtering is first performed in the time domain, and the frequency range may be appropriately determined in consideration of the characteristics of the target. Next, a response representative of the ultrasonic wave image is acquired as shown in FIG. 8 . The representative response means the phase difference between the representative frequency signal and the time domain signal at each excitation point. Signal-to-noise ratio (SNR) can be improved even if the signal is acquired from a moving object or an uneven surface through effective signal superposition in the process of obtaining the representative response. Through this process, a two-dimensional representative response image representing the image is obtained through Equation 1 below.

where T is the total time of the ultrasonic wave image,

r(x,y) is the representative response, v(x,y,t) is the response of each position (x,y) in the ultrasonic wave image, f is the ultrasonic excitation frequency, and exp(-j2πft) is the sine wave generation it is expression

Thereafter, the representative response generated as shown in FIG. 9 is converted into a wavenumber domain (wavenumber domain) signal by applying a two-dimensional Fourier transform technique (step 240). If the scan surface is flat or not very curved, the wavenumber component usually has a torus shape, so it can be expressed in terms of diameter. Thereafter, a representative wavenumber is extracted in the wavenumber region, and a temperature is calculated therefrom (step 250).

First, the representative wavenumber Kr of the ultrasound image is selected by deriving the radius between the point having the maximum value in the wavenumber region and the origin. That is, the representative wave number is calculated through Equation 2 below.

Here, Kx and Ky are the positions of the maximum values in the wavenumber region.

On the other hand, the movement speed, size, and wavelength of ultrasonic waves change even at the same frequency according to the change of the medium. When the temperature changes, the physical properties (density and stiffness, etc.) of the object change, so the medium changes, which in turn changes the propagation speed and representative wave number of ultrasonic waves according to the temperature.

Accordingly, the temperature is calculated by extracting the temperature value corresponding to the extracted representative wave number from a lookup table (not shown) in which the temperature value corresponding to the representative wave number is recorded. Here, as shown in FIG. 10 , the lookup table is provided in the calculation unit 170, and values obtained by experimentation on the relationship between the representative wave number and the temperature are recorded, and the temperature can be calculated therefrom.

According to the above-described laser ultrasonic flaw detection and wavenumber signal processing-based temperature measuring device and temperature measuring method for non-contact high-temperature sleeve steel, when the surface is solidified by cooling in a molten state like the high-temperature sleeve steel 10, the surface emissivity is Accurate temperature measurement is possible even in rapidly changing conditions. In addition, since the entire process (excitation-signal measurement-signal processing-temperature conversion) is completed quickly, real-time temperature measurement can be performed. Because of these advantages, it is possible to know the exact cooling time of the sleeve steel and to apply the processes after cooling in a timely manner, thereby improving process efficiency and worker safety.

In addition, when the scan area is increased through this device, it is possible to create a temperature map for not only a local area but also the entire area of the target surface. In addition, when the acquired ultrasonic signal is applied to the existing non-destructive inspection technique, it can be expanded to the field of quality inspection through surface defect detection along with temperature measurement.

110: laser beam irradiation unit 112: first laser light source
120: scan unit 150: laser beam-based measurement unit
151: second laser light source 155: first mirror
161: first beam splitter 162: second beam splitter
163: third beam splitter 165: photodetector
170: calculation unit 180: display unit

Claims (3)

a laser beam irradiator for irradiating an impact laser beam to impact points of a scan position so as to generate a sound wave on the surface of the high temperature sleeve steel;
A reference laser beam is irradiated to the high-temperature sleeve steel at a measurement position different from that of the impact laser beam, and a detection laser beam reflected from the high-temperature sleeve steel to the reference laser beam is received from the high-temperature sleeve steel. a laser beam-based measuring unit for measuring ultrasonic information generated in response to irradiation of an impact laser beam;
The driving of the laser beam irradiator is controlled so that the impact laser beam from the laser beam irradiator is irradiated to the high-temperature sleeve steel, and the temperature of the surface of the high-temperature sleeve steel is calculated using the ultrasonic information measured from the laser beam-based measuring unit. and a calculation unit to
the calculation unit
The received ultrasound signal is arranged as 3D data according to the excitation point corresponding to each impact point of the scan position, and the ultrasound propagation image arranged in reverse order in the time direction is obtained with respect to the arranged 3D data, and the obtained ultrasound For the radio image, a representative response corresponding to the phase difference between the representative frequency signal and the time domain signal of each excitation point is derived, the derived representative response is converted into a wavenumber domain signal, and then the representative wave number is extracted and corresponding to the extracted representative wave number A non-contact high temperature sleeve steel temperature measuring device based on laser ultrasonic flaw detection and wave number signal processing, characterized in that the temperature is calculated by extracting the temperature value from the lookup table. According to claim 1, wherein the laser beam irradiation unit
a first laser light source emitting the impact laser beam;
A scanning unit for adjusting the path so that the impact laser beam emitted from the first laser light source is irradiated to the impact point of the set scan position;
The laser beam-based measuring unit
a second laser light source emitting the reference laser beam;
a first beam splitter for dividing the reference laser beam into a first path and a second path in a direction orthogonal to the first path;
a second beam splitter for passing the light traveling through the first path and reflecting the light reflected from the high-temperature sleeve steel to a third path that is different from the second path;
a first mirror for reflecting the light traveling through the second path to a fourth path parallel to the first path;
The light that is reflected from the first mirror and proceeds through the fourth path and the light that proceeds through the third path is disposed at a position where it can be incident and the light that proceeds through the fourth path is transmitted to the fifth path. a third beam splitter that transmits the light and reflects the light traveling through the third path to travel through the fifth path;
and a photodetector that detects the interference light traveling from the third beam splitter to the fifth path and provides it to the calculator. A laser beam irradiator that irradiates an impact laser beam to impact points of a scan position to generate sound waves on the surface of the high temperature sleeve steel, and a reference laser beam to the high temperature sleeve steel at a measurement position different from the irradiation position of the impact laser beam A laser beam-based measuring unit for irradiating a laser beam and measuring ultrasonic information generated in response to the irradiation of the impact laser beam from the high-temperature sleeve steel by receiving a detection laser beam reflected from the high-temperature sleeve steel with respect to the reference laser beam; , control the driving of the laser beam irradiator so that the impact laser beam from the laser beam irradiator is irradiated to the high-temperature sleeve steel, and measure the temperature of the surface of the high-temperature sleeve steel using the ultrasonic information measured from the laser beam-based measuring unit In the temperature measuring method of a temperature measuring device having a calculation unit for calculating,
go. arranging the received ultrasound signal as three-dimensional data according to the excitation point corresponding to each impact point of the scan position;
me. acquiring ultrasonic wave images arranged in a reverse order in a time direction with respect to the arranged 3D data;
All. deriving a representative response corresponding to a phase difference between a representative frequency signal and a time-domain signal of each excitation point with respect to the obtained ultrasonic wave image;
La. converting the derived representative response into a wavenumber domain signal and then extracting a representative wavenumber;
mind. Calculating the temperature by extracting the temperature value corresponding to the extracted representative wave number from a look-up table in which the temperature value corresponding to the representative wave number is recorded; Temperature measurement method of steel temperature measuring device.

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