A temperature-indicating paint calibration device and its calibration method

Abstract

This invention discloses a calibration device and method for temperature-indicating paint. A heating program segment is set by a host computer and transmitted to a PID control module. The PID control module controls the output power of the induction heating power supply. A standard specimen is inserted into the induction heating coil. A first thermometer transmits the temperature signal from this end to the PID control module, forming a closed-loop heating circuit. After heating reaches a stable state, the host computer controls a second sensor to move according to a planned path and speed. The second thermometer moves from one end of the standard specimen to the other, measuring the temperature of the standard specimen along the planned path and transmitting the data to the host computer. By querying the temperature measurement results of the coordinates of the isotherm of the temperature-indicating paint on the standard specimen along the planned path, the temperature value corresponding to the isotherm is obtained. This invention uses induction heating, which has advantages such as low requirements for the geometric dimensions and material parameters of the standard specimen, high safety, temperature measurement using moving measurement, calibration completed in one heating cycle, high calibration accuracy, and no isotherm drift.

Description

Technical Field

[0001] This invention relates to the field of temperature detection technology, and in particular to a temperature-indicating paint calibration device and its calibration method. Background Technology

[0002] Irreversible temperature-indicating paint is a special functional coating that measures the surface temperature changes of high-temperature components such as aircraft engines, gas turbines, and industrial pipelines by observing changes in the color of the paint film. If the surface of a specimen coated with irreversible temperature-indicating paint undergoes a temperature change, the color of the paint film will also change accordingly. Moreover, due to the irreversibility of its color change, the changed color will remain on the surface of the object, thus indicating the temperature distribution on the surface of the specimen. Irreversible temperature-indicating paint is an important non-interference surface temperature measurement method that combines the advantages of both contact and non-contact temperature measurement methods. It can be applied to the surface of temperature measuring devices without the need for leads or test windows, and it does not interfere with the target temperature field. It is particularly suitable for situations where general temperature measuring tools cannot or are difficult to use, such as composite material surfaces, component surfaces, rotating parts surfaces, and large-area surfaces. It can be used for temperature measurement in harsh environments without damaging the structure and working state of the test piece, without affecting the aerodynamic and thermal properties of the test piece, and without affecting the repeated use of the test piece. It can measure continuous temperature distribution, does not require a physical transmission medium for the signal, and has an intuitive and clear color display of the temperature field. The results are accurate, the color changes are clear and stable, easy to interpret and can be stored for a long time, and the temperature measurement range is wide.

[0003] The temperature measurement principle of irreversible thermochromic paint lies in the fact that the paint film sprayed on the surface of the test piece undergoes a physicochemical reaction with temperature changes, causing the paint film color to change. The surface temperature of the test piece is mainly determined by identifying the isotherms representing the color changes of the paint film. Therefore, to accurately determine the temperature distribution on the surface of the test piece, the irreversible thermochromic paint needs to be calibrated during its development and use to obtain the temperature values ​​represented by different isotherms.

[0004] In 2013, my country promulgated HG-T 4562-2013, which specifies the product classification, requirements, test methods, and inspection rules for irreversible temperature-indicating paints. A utility model patent application with application number CN201320269903.0, entitled "A Temperature Detection Device for Temperature-Indicating Paint," discloses a method for calibrating temperature-indicating paints by applying a large current to both ends of a standard test piece to heat it and form isothermal lines. This method involves applying a current of 500-900A to both ends of the standard specimen for heating. The tensile force generated by the high current can cause the narrowest part of the standard specimen to twist and deform, leading to safety issues and calibration failure. Furthermore, it requires two heating calibrations, and the standard specimens used in both calibrations must maintain consistent geometric dimensions and material parameters, placing high demands on the standard specimens. Multiple thermocouples also need to be welded and fixed to the standard specimen. Because the positions and number of thermocouples welded and fixed during the two heating cycles differ, the conductivity of the standard specimens will differ between the two cycles, reducing calibration accuracy. Moreover, it will cause differences in temperature distribution on the standard specimens between the two cycles, and the thermocouple welding positions will differ from the actual isotherms, leading to isotherm drift and calibration failure of the temperature indicator paint. Additionally, it can only calibrate temperatures at the isotherms, and its use involves multiple pieces of equipment that are inconvenient to carry and operate. Summary of the Invention

[0005] One objective of this invention is to propose a calibration device and method for temperature-indicating paint. This invention uses induction heating of a standard specimen and a moving temperature sensor to measure the temperature, completing the calibration in one heating cycle, thus solving problems such as low calibration accuracy, easy drift of isotherms, and easy failure of temperature-indicating paint calibration.

[0006] A temperature-indicating paint calibration device according to an embodiment of the present invention includes an induction heating power supply, an induction heating coil, a control unit, a standard test piece, a bracket, at least one first thermometer, and at least one second thermometer;

[0007] The induction heating power supply is connected to the induction heating coil and electrically connected to the control unit. The induction heating power supply provides power to both the induction heating coil and the control unit.

[0008] One end of the standard specimen is mounted on the support as the non-heating end, and the other end extends into the center of the induction heating coil as the heating end.

[0009] At least one of the first temperature sensors is fixedly mounted on the bracket. The first temperature sensor is used to measure the temperature of the heating end of the standard specimen and transmit the temperature signal to the control unit to form a heating closed loop.

[0010] At least one of the second thermometers is mounted on a bracket and can move along the length of the standard specimen. The second thermometer is used to measure the temperature from the heated end to the unheated end of the standard specimen and transmit it to the control unit.

[0011] The control unit controls the output power of the induction heating power supply and controls the movement of the second temperature sensor.

[0012] The temperature value corresponding to the isotherm is obtained by querying the temperature measurement results of the coordinates of the isotherm of the temperature-indicating paint on the standard test piece on the planned path.

[0013] This structure uses induction heating, which causes minimal damage to the standard specimen, has no current on the standard specimen, and has low requirements for the geometric dimensions and material parameters of the standard specimen, resulting in high safety. It allows for mobile measurement, and calibration can be completed with a single heating, resulting in high calibration accuracy. Moreover, a single heating does not produce isotherm drift, and the temperature at the isotherm and other required calibration locations can be calibrated.

[0014] Specifically, the control unit includes a host computer and a PID control module, and the host computer is communicatively connected to the PID control module;

[0015] The host computer sets a heating program segment to set the desired temperature value;

[0016] The PID control module receives temperature electrical signals from the host computer and the first temperature sensor and converts the temperature electrical signals into temperature data to form a feedback temperature value. The PID control module automatically adjusts the output power of the induction heating power supply according to the difference between the feedback temperature value and the desired temperature value.

[0017] In this structure, the heating program segment is set by the host computer and transmitted to the PID control module. The PID control module controls the output power of the high-frequency heating power supply. One end of the standard specimen is inserted into the induction heating coil. The high-frequency heating power supply uses the induction heating coil to heat one end of the standard specimen. The first thermometer transmits the temperature signal of this end to the PID control module to form a heating closed loop.

[0018] Specifically, the control unit further includes a data acquisition unit that is connected to a host computer for communication. The data acquisition unit is used to convert the temperature electrical signal of the second thermometer into temperature data and transmit it to the host computer for display and recording.

[0019] In this structure, after heating to a stable state, the movable part on the host computer control bracket moves according to the planned path and speed. The second temperature sensor is fixed on the movable part on the bracket. The movable part on the bracket drives the second temperature sensor to move from one end of the standard specimen to the other end, measuring the temperature of the standard specimen along the planned path and transmitting it to the host computer.

[0020] Specifically, the bracket includes a base, a first support rod, a support column, a movable slider, a second support rod, a threaded rod, a guide rod, and a lifting motor;

[0021] The base, the first support rod, the movable slider, and the second support rod are arranged parallel to each other. The support column is vertically installed on the base, and one end of the first support rod and one end of the second support rod are fixedly connected to the support column.

[0022] The threaded rod and the guide rod are arranged parallel to each other between the first support rod and the second support rod. The lifting motor is used to drive the threaded rod to rotate. The lifting motor is installed at the end of the threaded rod near the second support rod. The guide rod is used to guide the movement of the movable slider. The movable slider has a first through hole for the threaded rod to pass through and a second through hole for the guide rod to pass through. The first through hole is provided with an internal thread that matches the external thread of the threaded rod.

[0023] This structure is mainly used to fix the induction heating coil, the first thermometer, and the second thermometer, and to move the second thermometer to measure the temperature on the standard test piece.

[0024] Based on this, the first temperature sensor is installed at the end of the first support rod away from the support column, and the second temperature sensor is installed at the end of the movable slider away from the support column. The second temperature sensor moves along the length of the threaded rod under the drive of the movable slider.

[0025] Based on this, the lifting motor is connected to the host computer for communication. The lifting motor receives the movement signal sent by the host computer to control the rotation speed of the threaded rod. The rotation of the threaded rod drives the moving slider to rise or fall.

[0026] This structure, upon receiving the start signal from the PID control module, moves the second thermometer from the heating end of the standard specimen to the other end according to the planned path and speed.

[0027] Based on this, the error in the feedback temperature value generated by the PID control module is less than 0.1%, and the error in the automatic adjustment of the output power of the induction heating power supply by the PID control module is no greater than 0.1%.

[0028] This structure ensures the calibration accuracy of the calibration device.

[0029] Preferably, the induction heating power supply, PID control module, and data acquisition unit can be integrated into a programmable data acquisition induction heating power supply.

[0030] This structure integrates a programmable data acquisition induction heating power supply into a single unit, resulting in a small size, low cost, and the ability to independently calibrate the temperature-indicating paint without a host computer. It is also portable and easy to operate.

[0031] Based on this, both the first and second temperature measuring devices can be temperature sensors or infrared temperature measuring devices.

[0032] A method for calibrating a temperature-indicating paint, using the aforementioned temperature-indicating paint calibration device, includes the following steps:

[0033] S1: Connect the temperature-indicating paint calibration device to the power supply;

[0034] S2: Move the slider on the support bracket to the bottom using the host computer control, and record the position P0 of the second thermometer when it contacts the standard specimen;

[0035] S3: Set the heating program segment, temperature measurement point K, and temperature measurement length L0 of the temperature-indicating paint through the host computer, and start heating. The host computer will then transmit the heating program segment to the PID control module.

[0036] S4: The PID control module uses an internal PID program to control the output power of the induction heating power supply based on the heating program segment and the temperature measured by the first thermometer. The output power of the induction heating power supply heats the standard test piece through the induction heating coil.

[0037] S5: The temperature at the bottom of the standard specimen rises and is transmitted to the top. The first thermometer measures the temperature at the bottom of the standard specimen and transmits it to the PID control module.

[0038] S6: The second thermometer measures the temperature at the contact point with the standard specimen and transmits it to the data acquisition system. The data acquisition system converts the temperature electrical signal into a digital signal and transmits it to the host computer, which displays it in real time.

[0039] S7: After the heating program segment is completed, the host computer records the temperature data D1;

[0040] S8: The host computer automatically controls the lifting motor to move the second temperature sensor upward by L1. After waiting for 5 seconds, the host computer records the temperature data D2.

[0041] The formula is as follows:

[0042]

[0043] In the formula, K is the temperature measurement point and L0 is the temperature measurement length;

[0044] S9: Repeat step S8 (K-1) times;

[0045] S10: The temperature-indicating paint calibration device is turned off after data acquisition is completed;

[0046] S11: After the standard test piece has cooled, measure the isotherms C1, C2, ..., C of the temperature-indicating paint. n-1 The distances between the intersection point of the longitudinal centerline of the left surface of the standard specimen and P0 are S1, S2, ..., S. n-1 ;

[0047] S12: Using the measured distances S1, S2, ..., S n-1 Combined with the temperature recording data D1, D2, ..., D from the host computern Calculate the isotherms C1, C2, ..., C of the temperature-indicating paint. n-1 The indicated temperatures T1, T2, ..., T n-1 ;

[0048] Temperature T i The calculation formula is:

[0049]

[0050] T i =D j +(D j+1 -D j )×(S i -j×L1) / L1

[0051] Where i = 1, 2, ..., n-1, and j is rounded down to the nearest integer;

[0052] S13: If the temperature at other locations on the longitudinal center line of the left side surface of the standard specimen is required, measure the distance between that location and P0, and repeat the formula in step S12 to calculate it.

[0053] The beneficial effects of this invention are:

[0054] (1) The present invention uses induction heating and no current, which has the advantages of low requirements for the geometric dimensions and material parameters of standard specimens, minimal damage, and high safety.

[0055] (2) The present invention has fewer temperature measuring devices, requiring only two temperature measuring devices. At the same time, the temperature measurement adopts moving measurement, and calibration can be completed in one heating. The calibration accuracy is high and there is no isothermal drift.

[0056] (3) This invention can calibrate the temperature at the isotherm of the temperature-indicating paint and other required locations, and has a wide range of applications and is easy to promote and use. Attached Figure Description

[0057] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0058] Figure 1 This is a schematic diagram of the structure of a temperature-indicating paint calibration device proposed in this invention;

[0059] Figure 2 This is a schematic diagram of the structure of the support proposed in this invention;

[0060] Figure 3 These are schematic diagrams of the temperature-indicating paint calibration device in Examples 4 and 5;

[0061] Figure 4This is a control layout diagram of the temperature-indicating paint calibration device proposed in this invention;

[0062] Figure label:

[0063] 1-Induction heating power supply; 2-Induction heating coil;

[0064] 3-Control unit, 301-PID control module, 302-Data acquisition unit;

[0065] 4-Standard specimen;

[0066] 5-Bracket, 501-Base, 502-First support rod, 503-Support rod, 504-Moving slider, 505-Second support rod, 506-Threaded rod, 507-Guide rod, 508-Lifting motor;

[0067] 6 - First thermometer, 7 - Second thermometer;

[0068] 8-Programmable data acquisition induction heating power supply. Detailed Implementation

[0069] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0070] Example 1

[0071] like Figure 1 and Figure 4 As shown, a temperature-indicating paint calibration device includes an induction heating power supply 1, an induction heating coil 2, a control unit 3, a standard test piece 4, a bracket 5, at least one first thermometer 6, and at least one second thermometer 7.

[0072] The induction heating power supply 1 is connected to the induction heating coil 2, and the induction heating power supply 1 is electrically connected to the control unit 3. The induction heating power supply 1 supplies power to the induction heating coil 2 and the control unit 3 respectively.

[0073] One end of the standard specimen 4 is mounted on the bracket 5 as the non-heating end, and the other end extends into the center of the induction heating coil 2 as the heating end.

[0074] At least one of the first temperature measuring devices 6 is fixedly mounted on the bracket 5. The first temperature measuring device 6 is used to measure the temperature of the heating end of the standard specimen 4 and transmit the temperature signal to the control unit 3 to form a heating closed loop.

[0075] At least one of the second thermometers 7 is mounted on the bracket 5 and can move along the length of the standard specimen 4. The second thermometer 7 is used to measure the temperature from the heated end to the unheated end of the standard specimen 4 and transmit it to the control unit 3.

[0076] The control unit 3 controls the output power of the induction heating power supply 1 and controls the movement of the second temperature sensor 7;

[0077] The temperature value corresponding to the isotherm is obtained by querying the temperature measurement results of the coordinates of the isotherm of the temperature-indicating paint on the planned path on the standard specimen 4.

[0078] This structure uses induction heating, which causes minimal damage to the standard specimen 4. There is no current on the standard specimen 4, and the requirements for the geometric dimensions, materials and other parameters of the standard specimen 4 are low, resulting in high safety. It allows for mobile measurement, and calibration can be completed with a single heating, resulting in high calibration accuracy. Moreover, a single heating will not cause isotherm drift, and the temperature at the isotherm and other required calibration locations can be calibrated.

[0079] Specifically, the control unit 3 includes a host computer and a PID control module 301, and the host computer and the PID control module 301 are communicatively connected.

[0080] The host computer sets a heating program segment to set the desired temperature value;

[0081] The PID control module 301 receives temperature electrical signals from the host computer and the first temperature sensor 6 and converts the temperature electrical signals into temperature data to form a feedback temperature value. The PID control module 301 automatically adjusts the output power of the induction heating power supply 1 according to the difference between the feedback temperature value and the desired temperature value.

[0082] In this structure, the heating program segment is set by the host computer and transmitted to the PID control module 301. The PID control module 301 controls the output power of the high-frequency heating power supply. One end of the standard specimen 4 is inserted into the induction heating coil 2. The high-frequency heating power supply uses the induction heating coil 2 to heat one end of the standard specimen 4. The first thermometer 6 transmits the temperature signal of this end to the PID control module 301 to form a heating closed loop.

[0083] Specifically, the control unit 3 further includes a data acquisition unit 302 that is connected to the host computer for communication. The data acquisition unit 302 is used to convert the temperature electrical signal of the second thermometer 7 into temperature data and transmit it to the host computer for display and recording.

[0084] In this structure, after heating to a stable state, the movable part on the host computer control bracket 5 moves according to the planned path and speed. The second temperature sensor 7 is fixed on the movable part on the bracket 5. The movable part on the bracket 5 drives the second temperature sensor 7 from one end of the standard specimen 4 to the other end, measuring the temperature of the standard specimen 4 on the planned path and transmitting it to the host computer.

[0085] Based on this, the error of the feedback temperature value generated by the PID control module 301 is less than 0.1%, and the error of the automatic adjustment of the output power of the induction heating power supply 1 by the PID control module 301 is not greater than 0.1%.

[0086] This structure ensures the calibration accuracy of the calibration device.

[0087] The high-frequency induction heating power supply 1 primarily provides power to the induction heating coil 2, with an output power of 0-10KW, heating the lower end of the standard specimen 4 to above 1400℃. The high-frequency induction heating power supply 1 can adjust its output power according to the received output signal from the PID control module 301. The right side of the high-frequency induction heating power supply 1 has an interface for installing the induction heating coil 2.

[0088] The PID control module 301 is the central control unit for the heating of the temperature-indicating paint calibration device. It employs the Yudian AI-3956PX artificial intelligence temperature controller, which can be configured with 30 heating program segments. It features Ethernet connectivity, a built-in host computer, and remote control capabilities. The PID heating control module interacts with the host computer, receiving settings such as the heating program segment, temperature measurement point K, and temperature measurement length L0, as well as the temperature signal from the heated end of the standard specimen 4 measured by the first thermometer 6. It converts the temperature signal into temperature data to form a feedback temperature value with an error of less than 0.1%. Then, the built-in PID control module 301 automatically adjusts the output power of the high-frequency induction heating power supply 1 based on the difference between the feedback temperature value and the desired temperature set in the heating program segment, with a control error not exceeding 0.1%. The PID control module 301 also controls the movement, stopping time, and movement speed of the movable part of the support 5, transmitting temperature data to the touchscreen and the host computer for display and storage. The data acquisition unit 302 is a high-precision data acquisition unit with an error of less than 0.1%. It is used to convert the temperature electrical signal transmitted by the second thermometer 7 into temperature data and transmit it to the host computer for display and recording.

[0089] The induction heating coil 2 is installed on the right side of the high-frequency induction heating power supply 1, and uses its output power to heat one end of the standard specimen 4.

[0090] Standard specimen 4 is a rectangular metal plate coated with temperature-indicating paint according to HG-T 4562-2013, with a length of 150-200mm, a width of 10-40mm, and a thickness of 1-3mm. The material is selected from ordinary stainless steel or high-temperature stainless steel depending on the temperature-indicating paint to be tested. Standard specimen 4 has a 1-1.2cm diameter hole at its horizontal center, 1.5-2cm from the top. The upper end of standard specimen 4 is fixed to the center of the left side of the first support rod 502 by fixing bolts, and the lower end is inserted into the center of the induction heating coil 2 for induction heating.

[0091] After the lower end of standard specimen 4 is heated to the calibrated temperature of the temperature-indicating paint, the heat will be transferred upwards, forming a temperature field distribution from bottom to top. The paint film on the surface of standard specimen 4 will change color according to the temperature field distribution.

[0092] Example 2

[0093] Based on Example 1, such as Figure 2 As shown, specifically, the bracket 5 includes a base 501, a first support rod 502, a support column 503, a movable slider 504, a second support rod 505, a threaded rod 506, a guide rod 507, and a lifting motor 508;

[0094] The base 501, the first support rod 502, the movable slider 504, and the second support rod 505 are arranged parallel to each other. The support column 503 is vertically installed on the base 501. One end of the first support rod 502 and one end of the second support rod 505 are fixedly connected to the support column 503.

[0095] The threaded rod 506 and the guide rod 507 are arranged parallel to each other between the first support rod 502 and the second support rod 505. The lifting motor 508 is used to drive the threaded rod 506 to rotate. The lifting motor 508 is installed at one end of the threaded rod 506 near the second support rod 505. The guide rod 507 is used to guide the movement of the movable slider 504. The movable slider 504 has a first through hole for the threaded rod 506 to pass through and a second through hole for the guide rod 507 to pass through. The first through hole is provided with an internal thread that matches the external thread of the threaded rod 506.

[0096] This structure is mainly used to fix the induction heating coil 2, the first thermometer 6 and the second thermometer 7, and to move the second thermometer 7 to measure the temperature on the standard test piece 4.

[0097] Based on this, the first temperature sensor 6 is installed at the end of the first support rod 502 away from the support column 503, and the second temperature sensor 7 is installed at the end of the movable slider 504 away from the support column 503. The second temperature sensor 7 moves along the length direction of the threaded rod 506 under the drive of the movable slider 504.

[0098] Based on this, the lifting motor 508 is connected to the host computer for communication. The lifting motor 508 receives the movement signal sent by the host computer to control the rotation speed of the threaded rod 506. The rotation of the threaded rod 506 drives the moving slider 504 to rise or fall.

[0099] This structure, upon receiving the start signal from the PID control module 301, moves the second temperature sensor 7 from the heating end of the standard specimen 4 to the other end according to the planned path and speed.

[0100] The base 501 is a cuboid with a length of 15-20cm, a width of 10-15cm, and a height of 2-3cm. It is used to support the movable slider 504 and is placed horizontally on the worktable. The movable slider 504 must be kept horizontal.

[0101] The support column 503 is a cuboid with a length of 3-5cm, a width of 2-3cm, and a height of 20-40cm. The bottom of the support column 503 is welded to the base 501. The front and rear end faces of the support column 503 are at least 3cm away from the front and rear end faces of the base 501, and the right end face is at least 1cm away from the right end face of the base 501. The front of the support column 503 has a 1-1.2cm threaded hole at its horizontal center, 100-150cm and 250-300cm from the bottom surface. The side of the support column 503 has a 1-2cm square through hole at its horizontal center, 100-150cm and 250-300cm from the bottom surface.

[0102] The first support rod 502 is a cuboid with a length of 2-3 cm, a width of 2-3 cm, and a height of 15-20 cm. At the longitudinal center of the front face of the first support rod 502, there is a 1-1.2 cm circular through hole, the diameter of which is equal to the threaded hole at the upper end of the support column 503. The distance from the center of the circular through hole to the right end face of the first support rod 502 is equal to the distance from the center of the threaded hole at the upper end of the support column 503 to the right end face of the support column 503. A section of the first support rod 502 is inserted into the through hole at the upper end of the support column 503 and fixed with a fixing bolt. At the longitudinal center of the upper end face of the first support rod 502, 6-12 cm and 10-15 cm from the right end face, there are circular through holes with a diameter of 1-2 cm, the same diameter as the threaded rod 506 and the guide rod 507, respectively. At the center of the left end face of the first support rod 502, there is a 1-1.2 cm threaded hole for fixing the standard specimen 4 with a fixing bolt.

[0103] The second support rod 505 is a cuboid 10-15cm long, 2-3cm wide, and 2-3cm high. At the longitudinal center of the front of the second support rod 505 is a 1-1.2cm circular through hole, the diameter of which is equal to the threaded hole at the lower end of the support column 503. The distance from the center of the circular through hole to the right end face of the second support rod 505 is equal to the distance from the center of the threaded hole at the upper end of the support column 503 to the right end face of the support column 503. A section of the second support rod 505 is inserted into the through hole at the lower end of the support column 503 and secured with a fixing bolt. At the longitudinal center of the upper end face of the second support rod 505, 6-12cm and 10-15cm from the right end face, there are circular holes with a diameter of 1-2cm and a depth of 1cm, respectively, which are coaxial with and have the same diameter as the corresponding circular through holes on the first support rod 502. At the center of the left end face of the second support rod 505 is a 1-1.2cm threaded hole for fixing the second thermometer 7.

[0104] The threaded rod 506 is a threaded round rod with a diameter of 1-2 cm and a length of 180-230 cm. The threaded rod 506 passes through the left circular through-hole of the first support rod 502 and the left circular through-hole of the movable slider 504, and is inserted into the left circular hole of the second support rod 505. When the threaded rod 506 rotates forward or backward, it will cause the movable slider 504 to rise or fall.

[0105] The guide rod 507 is a smooth round rod with a diameter of 1-2 cm and a length of 150-200 cm. The guide rod 507 passes through the round through hole on the right side of the first support rod 502 and the round through hole on the right side of the movable slider 504, and is inserted into the round hole on the right side of the second support rod 505. The guide rod 507 is used to guide the movable slider 504 to move up and down, preventing the movable slider 504 from rotating or wobbling left and right.

[0106] The lifting motor 508 is used to rotate the threaded rod 506 at a planned speed according to the movement signal sent by the host computer, thereby driving the moving slider 504 to rise or fall.

[0107] The movable slider 504 is a cuboid with a length of 8-15cm, a width of 2-3cm, and a height of 3-6cm. At the longitudinal center of the upper end face of the movable slider 504, 0.5-2cm and 4.5-6cm from the right end face, there are circular through holes with a diameter of 1-2cm and a depth of 1cm, respectively. These holes have the same diameter and center-to-center distance as the corresponding circular through holes on the first support rod 502. At the center of the left end face of the movable slider 504, there is a 1-1.2cm threaded hole for fixing the first temperature sensor 6.

[0108] The fixing bolts are used to fix the standard specimen 4, the first support rod 502 and the second support rod 505. The model is the same as that of the fixing threaded hole.

[0109] Example 3

[0110] Based on Examples 1 and 2, such as Figure 1 , 2 As shown in Figure 4, a method for calibrating a temperature-indicating paint, taking a six-color temperature-indicating paint with five isotherms as an example, uses the aforementioned temperature-indicating paint calibration device and includes the following steps:

[0111] S1: Connect the temperature-indicating paint calibration device to the power supply;

[0112] S2: Move the slider 504 on the upper computer control bracket 5 to the bottom, record the position P0 of the second thermometer 7 when it contacts the standard test piece 4, and mark it as 0cm;

[0113] S3: Set the temperature indicator paint calibration heating program segment, the number of temperature measurement points to 31, and the temperature measurement length to 15cm through the host computer, and start heating. The host computer will then transmit the heating program segment to the PID control module 301.

[0114] S4: The PID control module 301 uses an internal PID program to control the output power of the induction heating power supply 1 based on the heating program segment and the temperature measured by the first thermometer 6. The output power of the induction heating power supply 1 heats the standard test piece 4 through the induction heating coil 2.

[0115] S5: The temperature at the lower end of the standard specimen 4 rises and is transmitted to the upper end. The first thermometer 6 measures the temperature at the lower end of the standard specimen 4 and transmits it to the PID control module 301.

[0116] S6: The second thermometer 7 measures the temperature at the contact point with the standard specimen 4 and transmits it to the data acquisition unit 302. The data acquisition unit 302 converts the temperature electrical signal into a digital signal and transmits it to the host computer, which displays it in real time.

[0117] S7: After the heating program segment is completed, the host computer records the temperature data D1 as 629.31℃;

[0118] S8: The host computer automatically controls the lifting motor 508 to move the second temperature sensor 7 upward by 0.5cm. After waiting for 5 seconds, the host computer records the temperature data D2 as 624.14℃.

[0119] S9: Repeat step S8 30 times;

[0120] S10: The temperature-indicating paint calibration device is turned off after data acquisition is completed;

[0121] S11: After the standard specimen 4 has cooled down, measure the distances between the intersection points of the isotherms C1, C2, ..., C5 of the temperature-indicating paint and the longitudinal center line of the left surface of the standard specimen 4 and P0. The distances are 2.9cm, 6.3cm, 9.1cm, 11.9cm, and 14.3cm, respectively.

[0122] S12: Using measurement distances of 2.9cm, 6.3cm, 9.1cm, 11.9cm, and 14.3cm, combined with temperature data recorded by the host computer: 629.31℃, 624.14℃, 619.41℃, 616.47℃, 613.53℃, 610.59℃, 607.65℃, 604.71℃, 601.76℃, 598.57℃, 595.00℃, 591.43℃, 587.86℃, 584.29℃, 58 Given the temperatures of 0.71℃, 575.71℃, 570.36℃, 565.00℃, 559.64℃, 554.29℃, 549.17℃, 545.00℃, 540.83℃, 536.67℃, 532.50℃, 528.33℃, and 524.17℃, calculate the temperatures indicated by the isotherms C1, C2, ..., C5 of the temperature-indicating paint to be 620.03℃, 600.11℃, 580.09℃, 550.13℃, and 530.05℃, respectively.

[0123] Temperature T i The calculation formula is:

[0124] j = 2 × S i

[0125] T i =D j +(D j+1 -D j )×(S i -j×L1) / L1

[0126] T i =D j +(D j+1 -D j )×2×(S i -0.5×j)

[0127] i=1, 2,...,5, j is rounded down to an integer;

[0128] Note: C1, C2, ..., C5 are markers and do not have actual values.

[0129] S13: If the temperature at other locations on the longitudinal center line of the left side surface of standard specimen 4 is required, measure the distance between that location and point P0 (0cm), and repeat the formula in step S12 to calculate it.

[0130] Example 4

[0131] Based on Examples 1, 2, or 3, such as Figure 3 As shown, the high-frequency induction heating power supply 1, the PID control module 301, and the acquisition system can be integrated into a programmable data acquisition induction heating power supply 8. After integration, the programmable data acquisition induction heating power supply 8 is a single unit with a small size and low cost. It can be used independently without a host computer for temperature-indicating paint calibration, and is portable and easy to operate.

[0132] The programmable data acquisition induction heating power supply 8 internally includes a high-frequency induction heating power supply module 1, a PID control module 301, a data acquisition unit 302, and a touch screen. The left side of the programmable data acquisition induction heating power supply 8 has temperature interface 1, temperature interface 2, data interface 1, and data interface 2. Except for temperature interface 2, which connects to the data acquisition unit 302, the other interfaces connect to the PID control module 301. The right side has an interface for installing the induction heating coil 2.

[0133] The high-frequency induction power supply mainly provides power to the induction heating coil 2. The output power (0-10KW) is adjusted according to the control signal of the PID control module 301 to heat the lower end of the standard specimen 4 to above 1400℃.

[0134] The PID control module 301, employing the Yudian AI-3956PX artificial intelligence temperature controller, can be set with 30 heating program segments. It features Ethernet functionality, a built-in host computer, and remote control capabilities. The PID control module 301 interacts with the touchscreen and host computer software, receiving settings such as heating program segments, temperature measurement point K, and temperature measurement length L0 from the host computer. The PID control module 301 uses the temperature of the heated end of the standard specimen 4 measured by the first thermometer 6 and the desired temperature set in the heating program segment to form a feedback loop with an error of less than 0.1%. Then, it uses the built-in PID control module 301 to control the output power of the high-frequency induction power supply module, with a control error not exceeding 0.1%. The PID control module 301 transmits the temperature data measured by the first thermometer 6 and the second thermometer 7 to the touchscreen and host computer for display and storage.

[0135] The touch screen is mainly used to input and store setting parameters such as heating program segments, temperature measurement point K, temperature measurement length L0, start and stop the heating program, and fault alarms. It has the same functions as the PID control module 301 and the host computer.

[0136] Standard specimen 4 is a rectangular metal plate coated with temperature-indicating paint according to HG-T 4562-2013, with a length of 150-200mm, a width of 10-40mm, and a thickness of 1-3mm. The material is selected from ordinary stainless steel or high-temperature stainless steel depending on the temperature-indicating paint to be tested. Standard specimen 4 has a 1-1.2cm diameter circular hole at its horizontal center, 1.5-2cm from the top. The top of standard specimen 4 is fixed to the center of the left side of the first support rod 502 with fixing bolts, and the bottom is inserted into the center of the induction heating coil 2 for induction heating. After the bottom of standard specimen 4 is heated to the calibrated temperature of the temperature-indicating paint, the heat is transferred upwards, forming a temperature field distribution from bottom to top. The paint film on the surface of standard specimen 4 will change color according to the temperature field distribution.

[0137] The first temperature sensor 6 uses a Class I K-type thermocouple with an accuracy of 0.4. It is fixed to the center of the first support rod 502 by threads and is used to measure the temperature of the heated end surface of the standard specimen 4. The temperature is then transmitted to the PID control module 301 of the programmable data acquisition induction heating power supply 8 to form a heating closed loop.

[0138] The second temperature sensor 7 uses a Class I K-type thermocouple with an accuracy of 0.4. It is fixed to the movable slider 504 by threads. The temperature of the standard specimen 4 from the hot end to the cold end surface is measured by the movable slider 504 and transmitted to the data acquisition unit 302 of the programmable data acquisition induction heating power supply 8.

[0139] Example 5

[0140] Based on Examples 1, 2, or 3, such as Figure 3As shown, taking a six-color temperature-indicating paint with a total of five isothermal lines as an example, the first temperature sensor 6 and the second temperature sensor 7 can both be temperature sensors or infrared temperature sensors. Infrared temperature measurement is a non-contact measurement with high sensitivity, high reliability, fast temperature measurement speed, and strong anti-interference ability.

[0141] Taking cost into consideration, preferably, the second thermometer 7 can be an infrared thermometer.

[0142] The first temperature sensor 6 uses a Class I K-type thermocouple with an accuracy of 0.4. It is fixed to the center of the left side of the first support rod 502 by a thread. It is used to measure the temperature of the heated end surface of the standard specimen 4 and transmits it to the PID control module 301 of the programmable data acquisition induction heating power supply 8 to form a heating closed loop.

[0143] The second temperature sensor 7 is a high-precision infrared thermometer with an accuracy of 0.4. The specific model is selected according to the temperature variation range of the temperature-indicating paint. The second temperature sensor 7 is fixed to the movable slider 504 by threads. Under the action of the movable slider 504, the temperature of the standard test piece 4 from the hot end to the cold end surface is measured and transmitted to the PID control module 301.

[0144] 1. Procedure for using the temperature-indicating paint calibration device: Prepare standard test specimen 4 of the temperature-indicating paint according to HG-T 4562-2013;

[0145] 2. Fix the first temperature sensor 6 to the left end of the first support rod 502;

[0146] 3. Fix the second thermometer 7 onto the movable slider 504;

[0147] 4. Install the induction heating coil 2 onto the corresponding interface on the right side of the programmable data acquisition induction heating power supply 8;

[0148] 5. Insert the lower end of the temperature-indicating paint standard specimen 4 into the center of the induction heating coil 2, and fix the upper end to the left end of the first support rod 502. Record the position P0 of the second thermometer 7 when it contacts the standard specimen 4.

[0149] 6. Connect the compensation line of the first thermometer 6 to the temperature interface on the left side of the programmable data acquisition induction heating power supply 8;

[0150] 7. Connect the data cable of the second thermometer 7 to the data interface 3 on the left side of the programmable data acquisition induction heating power supply 8;

[0151] 8. Connect the data interface on the left side of the programmable data acquisition induction heating power supply 8 to the host computer;

[0152] 9. Connect the movable slider 504 to the data interface 2 on the left side of the programmable data acquisition induction heating power supply 8;

[0153] 10. After checking that the circuit is normal, connect the programmable data acquisition induction heating power supply 8 and the power supply of the moving slider 504;

[0154] 11. The sliding slider 504 is moved to the bottom by controlling the upper computer of the PID control module 301 via the touch screen or the PID control module 301.

[0155] 12. Set the temperature-indicating paint calibration heating program segment, moving speed v (1cm / s), and temperature measurement length of 15cm via the touch screen or the host computer of the PID control module 301, and click Start Heating;

[0156] 13. The PID control module 301 uses an internal PID program to control the output power of the high-frequency induction heating power supply 1 based on the desired temperature set in the heating program segment and the feedback temperature measured by the first thermometer 6.

[0157] 14. The output power of the high-frequency induction heating power supply 1 heats the standard specimen 4 through the induction heating coil 2;

[0158] 15. The temperature at the lower end of standard specimen 4 rises and is transferred to the upper end;

[0159] 16. The first thermometer 6 measures the temperature at the lower end of the standard specimen 4 and transmits it to the PID control module 301.

[0160] 17. The second thermometer 7 measures the temperature of the standard specimen 4 and transmits it to the PID control module 301;

[0161] 18. The PID control module 301 transmits temperature data to the touch screen and the host computer, which then display it in real time.

[0162] 19. After the heating program segment is completed, the touch screen and the host computer record the time t0 at this time, which can be set to 0s, and automatically control the moving slider 504 to drive the second temperature sensor 7 to move upward by a distance of 15cm at a speed v through the PID control module 301.

[0163] 20. Calibration complete, the temperature-indicating paint calibration device is turned off;

[0164] 21. After the standard specimen 4 has cooled, measure the distances from P0 to the intersection of the isotherms C1, C2, ..., C5 of the temperature-indicating paint with the longitudinal center line of the left surface of the standard specimen 4: 2.9cm, 6.3cm, 9.1cm, 11.9cm, and 14.3cm, respectively.

[0165] Calculate the corresponding measurement times of 2.9s, 6.3s, 9.1s, 11.9s, and 14.3s using measurement distances of 2.9cm, 6.3cm, 9.1cm, 11.9cm, and 14.3s, respectively. Then combine this with the time-temperature data T1:D1, T2:D2, ..., T from the temperature recorder on the host computer. n:D n Calculate the temperatures indicated by the isotherms C1, C2, ..., C5 of the temperature-indicating paint: 620.11℃, 600.07℃, 580.03℃, 550.08℃, and 530.11℃, respectively.

[0166] 22. Measurement time t i The calculation formula is:

[0167] Δt i =S i / v(i = 1, 2, ..., 5)

[0168] t i =t0+Δt i

[0169] In the above formula, S i Given the following values: 2.9cm, 6.3cm, 9.1cm, 11.9cm, 14.3cm, v = 1cm / s, t0 = 0s, then t i The times are 2.9s, 6.3s, 9.1s, 11.9s, and 14.3s.

[0170] (Note: C1, C2, ..., C5 are label numbers and do not have actual values. Time-temperature data: T1: D1, T2: D2, ..., T...) n :D n Too many to list here)

[0171] 23. If the temperature at other locations on the longitudinal center line of the left surface of standard specimen 4 is required, measure the distance between that location and P0, and calculate it using the formula in step 22.

[0172] In summary, in the temperature-indicating paint calibration device, the heating program segment is set by the host computer and transmitted to the PID control module 301. The PID control module 301 controls the output power of the high-frequency heating power supply. One end of the standard specimen 4 is inserted into the induction heating coil 2. The high-frequency heating power supply uses the induction heating coil 2 to heat one end of the standard specimen 4. The first thermometer 6 transmits the temperature signal of this end to the PID control module 301 to form a heating closed-loop circuit. After the heating reaches a stable state, the host computer controls the moving slider 504 to move according to the planned path and speed. The second thermometer 7 is fixed on the moving slider 504. The moving slider 504 drives the second thermometer 7 from one end of the standard specimen 4 to the other end, measuring the temperature of the standard specimen 4 on the planned path and transmitting it to the host computer. After the heating ends and the standard specimen 4 cools down, the temperature value corresponding to the isotherm of the temperature-indicating paint on the standard specimen 4 can be obtained by querying the temperature measurement results based on the coordinates of the isotherm of the temperature-indicating paint on the planned path.

[0173] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A temperature-indicating paint calibration device, characterized in that, It includes an induction heating power supply, an induction heating coil, a control unit, a standard test piece, a bracket, at least one first thermometer, and at least one second thermometer; The induction heating power supply is connected to the induction heating coil and electrically connected to the control unit. The induction heating power supply provides power to both the induction heating coil and the control unit. One end of the standard specimen is mounted on the support as the non-heating end, and the other end extends into the center of the induction heating coil as the heating end. At least one of the first temperature sensors is fixedly mounted on the bracket. The first temperature sensor is used to measure the temperature of the heating end of the standard specimen and transmit the temperature signal to the control unit to form a heating closed loop. At least one of the second thermometers is mounted on a bracket and can move along the length of the standard specimen. The second thermometer is used to measure the temperature from the heated end to the unheated end of the standard specimen and transmit it to the control unit. The control unit controls the output power of the induction heating power supply and controls the movement of the second temperature sensor. The temperature value corresponding to the isotherm is obtained by querying the temperature measurement results of the coordinates of the isotherm of the temperature-indicating paint on the standard test piece on the planned path.

2. The temperature-indicating paint calibration device according to claim 1, characterized in that, The control unit includes a host computer and a PID control module, and the host computer is communicatively connected to the PID control module. The host computer sets a heating program segment to set the desired temperature value; The PID control module receives temperature electrical signals from the host computer and the first temperature sensor and converts the temperature electrical signals into temperature data to form a feedback temperature value. The PID control module automatically adjusts the output power of the induction heating power supply according to the difference between the feedback temperature value and the desired temperature value.

3. The temperature-indicating paint calibration device according to claim 2, characterized in that, The control unit also includes a data acquisition unit that is connected to a host computer. The data acquisition unit is used to convert the temperature electrical signal of the second thermometer into temperature data and transmit it to the host computer for display and recording.

4. The temperature-indicating paint calibration device according to claim 3, characterized in that, The bracket includes a base, a first support rod, a pillar, a movable slider, a second support rod, a threaded rod, a guide rod, and a lifting motor; The base, the first support rod, the movable slider, and the second support rod are arranged parallel to each other. The support column is vertically installed on the base, and one end of the first support rod and one end of the second support rod are fixedly connected to the support column. The threaded rod and the guide rod are arranged parallel to each other between the first support rod and the second support rod. The lifting motor is used to drive the threaded rod to rotate. The lifting motor is installed at the end of the threaded rod near the second support rod. The guide rod is used to guide the movement of the movable slider. The movable slider has a first through hole for the threaded rod to pass through and a second through hole for the guide rod to pass through. The first through hole is provided with an internal thread that matches the external thread of the threaded rod.

5. The temperature-indicating paint calibration device according to claim 4, characterized in that, The first temperature sensor is installed at the end of the first support rod away from the support column, and the second temperature sensor is installed at the end of the movable slider away from the support column. The second temperature sensor moves along the length of the threaded rod under the drive of the movable slider.

6. The temperature-indicating paint calibration device according to claim 4, characterized in that, The lifting motor is connected to the host computer for communication. The lifting motor receives the movement signal sent by the host computer to control the rotation speed of the threaded rod. The rotation of the threaded rod drives the moving slider to rise or fall.

7. The temperature-indicating paint calibration device according to claim 2, characterized in that, The error in the feedback temperature value generated by the PID control module is less than 0.1%, and the error in the automatic adjustment of the output power of the induction heating power supply by the PID control module is no greater than 0.1%.

8. The temperature-indicating paint calibration device according to claim 3, characterized in that, The induction heating power supply, PID control module, and data acquisition unit can be integrated into a programmable data acquisition induction heating power supply.

9. The temperature-indicating paint calibration device according to claim 1, characterized in that, Both the first and second temperature sensors can be temperature sensors.

10. A method for calibrating temperature-indicating paint, using the temperature-indicating paint calibration device according to any one of claims 4-6, characterized in that, Includes the following steps: S1: Connect the temperature-indicating paint calibration device to the power supply; S2: Move the slider on the support bracket to the bottom using the host computer control, and record the position P0 of the second thermometer when it contacts the standard specimen; S3: Set the heating program segment, temperature measurement point K, and temperature measurement length L0 of the temperature-indicating paint through the host computer, and start heating. The host computer will then transmit the heating program segment to the PID control module. S4: The PID control module uses an internal PID program to control the output power of the induction heating power supply based on the heating program segment and the temperature measured by the first thermometer. The output power of the induction heating power supply heats the standard test piece through the induction heating coil. S5: The temperature at the bottom of the standard specimen rises and is transmitted to the top. The first thermometer measures the temperature at the bottom of the standard specimen and transmits it to the PID control module. S6: The second thermometer measures the temperature at the contact point with the standard specimen and transmits it to the data acquisition system. The data acquisition system converts the temperature electrical signal into a digital signal and transmits it to the host computer, which displays it in real time. S7: After the heating program segment is completed, the host computer records the temperature data D1; S8: The host computer automatically controls the lifting motor to move the second temperature sensor upward by L1. After waiting for 5 seconds, the host computer records the temperature data D2. The formula is as follows: In the formula, K is the temperature measurement point and L0 is the temperature measurement length; S9: Repeat step S8 (K-1) times; S10: The temperature-indicating paint calibration device is turned off after data acquisition is completed; S11: After the standard test piece has cooled, measure the isotherms C1, C2, ..., C of the temperature-indicating paint. n-1 The distances between the intersection point of the longitudinal centerline of the left surface of the standard specimen and P0 are S1, S2, ..., S. n-1 ; S12: Using the measured distances S1, S2, ..., S n-1 Combined with the temperature recording data D1, D2, ..., D from the host computer n Calculate the isotherms C1, C2, ..., C of the temperature-indicating paint. n-1 The indicated temperatures T1, T2, ..., T n-1 ; Temperature T i The calculation formula is: T i =D j +(D j+1 -D j )×(S i -j×L1) / L1 Where i = 1, 2, ..., n-1, and j is rounded down to the nearest integer; S13: If the temperature at other locations on the longitudinal center line of the left side surface of the standard specimen is required, measure the distance between that location and P0, and repeat the formula in step S12 to calculate it.

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