Temperature Field Measurement and Control System and Method Based on Finite Element Simulation

Abstract

The present invention belongs to the field of temperature measurement and control technology, and specifically relates to a temperature field measurement and control system and method based on finite element simulation. The system includes a heating unit, the heating unit includes a metal container, the metal container is filled with a conductive powder bed composed of conductive powder; a conductive unit, the conductive unit includes two groups of electrodes that can move toward or oppositely, the two groups of electrodes are wrapped in the conductive powder bed, and the sample is placed between the two groups of electrodes; a monitoring unit, the monitoring unit monitors the global temperature of the conductive powder bed. The method obtains a real-time temperature field distribution image based on a finite element simulation model and compares it with the measured global real-time temperature field of the conductive powder bed, and controls the input current of the electrode or the electrode spacing according to the deviation data obtained by the comparison. Therefore, the present invention realizes real-time monitoring and precise control of the global temperature field of the conductive powder bed through the structure and displacement of the electrode, multi-station temperature measurement, and in conjunction with the finite element simulation model.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature measurement and control, and in particular relates to a temperature field measurement and control system and method based on finite element simulation. Background Art

[0002] For high-temperature manufacturing processes such as synthesis, sintering, smelting, welding, reaction and heat treatment of ceramics, metals and other materials, energy saving, consumption reduction, greenness and efficiency are particularly important.

[0003] Ultrafast high-temperature sintering (UHS) was first disclosed in prior art 1 CN114206802A in 2020. The method of the prior art places the sample between two layers of conductive carbon elements, and quickly heats the conductive carbon elements through the principle of Joule heat of electric current, thereby rapidly heating the sample to achieve ultra-fast synthesis, sintering and reaction of the material. Although the method described in prior art 1 has no special requirements for the chemical composition and physical properties of the sample material, it is limited by the layered structure of the conductive carbon element and the placement of the sample, and it cannot achieve high-temperature preparation of large-size samples with a thickness of more than 1 cm.

[0004] Based on the prior art 1, the prior art 2 CN216205255U discloses an ultrafast heating method based on high melting point conductive powder, which realizes ultrafast heating and preparation of large-sized complex structure samples by burying the sample in the high melting point conductive powder to form a good coating. However, due to the three-dimensional stacking and coating of the sample by the conductive powder, thermocouples, infrared and other temperature measuring instruments cannot obtain the real-time temperature of the sample; and because the conductivity and thermal conductivity of the conductive powder change with temperature, the entire thermal process cannot be accurately controlled and the temperature field distribution is unstable, which ultimately leads to poor operability of the process method and difficulty in engineering application.

[0005] Prior art three CN98220161.3, (1) electrode arrangement and state: the electrodes are fixed on opposite sides of the inner wall of the furnace, so the state of the powder electric heating body in the crucible cannot be changed during the heating process, and it is impossible to effectively control the heating process of the current Joule effect and the spatial distribution of the temperature field in the crucible, which greatly limits the shape, structure and size of the sample; (2) temperature measurement method and accuracy: a through-type fixed thermocouple is used for local single-point temperature measurement, which cannot monitor the temperature field distribution in the crucible in the entire area; the thermocouple has a long response time and the thermocouple is not stable under high current load. The temperature measurement is inaccurate and very easy to be damaged, so it is impossible to achieve real-time temperature measurement of the ultra-fast heating process; (3) Insulation principle and insulation material type: Insulation material is arranged on the outside of the powder electric heating material, so the high temperature resistance is limited and it is difficult to use it at high temperatures above 2000°C; the insulation material is in direct contact with the crucible and has poor thermal shock resistance. It cannot withstand the thermal shock caused by ultra-fast heating, so it cannot be used for ultra-fast heating or cooling processes; (4) Others: No automatic control function, no data acquisition function, no real-time monitoring function of temperature field distribution, and no continuous production potential.

[0006] Prior art 4 CN114522620A, (1) Application scenario: only for graphene preparation, that is, high temperature reaction under vacuum environment; (2) Device main structure and material type: the device main body only includes vacuum chamber, reaction tube and electrode, where the reaction tube is a round tube structure made of ceramic or polymer material, which is simple in form and small in space; since the energized carbon powder is in direct contact with the reaction tube, if ceramic material is used, the thermal shock resistance is poor, and ultra-fast temperature rise and fall cannot be achieved, and the use temperature does not exceed 2000°C; if polymer material is used, the use temperature is severely limited and does not exceed 800℃; (3) Electrode arrangement, state and function: The electrodes pass through the upper and lower covers of the vacuum chamber and are directly connected to the cover body through a sealing ring. Therefore, their function is only to conduct electricity and seal. They cannot move during the thermal process, so the state and resistance value of the carbon powder in the reaction tube cannot be changed. It is therefore impossible to effectively control the heating process of the Joule effect of the current and the spatial distribution of the temperature field in the reaction tube, which greatly limits the shape, structure and size of the sample; (4) Others: The content of the patent is relatively simple, only emphasizing the realization of vacuum conditions, and does not mention any substantial functions and principles such as temperature measurement, control, and monitoring.

[0007] Prior art 5 CN113847805B, (1) Heating element structure and sample placement method: The heating element is a carbon fiber cloth, both ends of which are fixedly connected to a conductive spacer, and the sintered sample is clamped in the carbon fiber cloth. Therefore, the heating element still belongs to the first generation of "layered conductive heating structure", which has great restrictions on sample structure, size and heating uniformity; (2) Electrode arrangement and status: The electrode device is fixed on the track plate. Although the track plate can be moved, its purpose is only to adjust the tightness of the carbon fiber cloth, and its position must be determined before the experiment. It cannot be adjusted in real time during the thermal process, so it is impossible to achieve real-time control of the physical state, resistance value, heating efficiency and spatial distribution of the temperature field of the carbon fiber cloth; (3) Insulation material and structure: This technical solution does not use any insulation material. The electrode device and the heating device are directly exposed to the external atmosphere. Therefore, the thermal efficiency is low and the heat loss is large. It is impossible to achieve ultra-fast heating at low current and low energy consumption, nor is it possible to achieve long-term insulation at high temperature. The high-temperature safety risk of the furnace body device and the electrode device is extremely high; (4) Others: No mention of temperature measurement, control and data acquisition methods or functions, no real-time monitoring function of temperature field distribution, and no continuous production potential. Summary of the invention

[0008] The purpose of the present invention is to solve the above-mentioned problems, namely, the temperature field distribution form is single, and it is impossible to perform real-time visual monitoring and precise regulation of the overall temperature field of the conductive powder bed, and to provide a temperature field measurement and control system and method based on finite element simulation.

[0009] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0010] The present invention provides a temperature field measurement and control system based on finite element simulation, comprising:

[0011] A heating unit, the heating unit comprising a metal container filled with a conductive powder bed composed of conductive powder;

[0012] A conductive unit, wherein the conductive unit comprises two sets of electrodes that can move toward or away from each other, the two sets of electrodes are wrapped in a conductive powder bed, and the sample is placed between the two sets of electrodes;

[0013] A monitoring unit, wherein the monitoring unit monitors the real-time temperature of the surrounding area in the conductive powder bed, the real-time temperature of the current load core area, and the real-time temperature of the metal container. The current load core area is the area between two groups of electrodes in the conductive powder bed, and the area outside the current load core area is the surrounding area.

[0014] Furthermore, the conductive powder is one of graphite, carbon powder, carbon nanomaterial, carbide or a mixture of any of them.

[0015] Furthermore, the conductive unit further comprises a transmission mechanism, which is connected to at least one group of electrodes and drives the electrodes connected thereto to move, so that the distance between the two groups of electrodes increases or decreases.

[0016] Furthermore, one end of the transmission mechanism is connected to an external programmable motor, and the other end of the transmission mechanism is connected to an electrode clamping device, and the electrode clamping device is used to clamp the electrode.

[0017] Furthermore, the transmission mechanism is a linear motion mechanism.

[0018] Furthermore, the two groups of electrodes are divided into an upper electrode and a lower electrode, and at least one through hole is provided on the electrode plate of the upper electrode.

[0019] Furthermore, the pole plate of the upper electrode includes a columnar shape, a cone shape, a plate shape, a mesh shape, and a curved surface shape.

[0020] Furthermore, the monitoring unit includes two sets of high-temperature thermocouples, one set of low-temperature thermocouples and a two-color infrared thermometer, the two sets of high-temperature thermocouple temperature measuring ends are located in the surrounding area, one set of low-temperature thermocouple temperature measuring ends is in contact with the metal container, and the temperature measuring end of the two-color infrared thermometer is located in the core area of ​​the current load.

[0021] The present invention also provides a temperature field measurement and control method based on finite element simulation, using any of the above-mentioned temperature field measurement and control systems, characterized in that the method comprises the following steps:

[0022] Step 1: Based on the real-time current input value and the finite element simulation model, obtain the real-time global temperature simulation value of the conductive powder bed and its real-time temperature field distribution image;

[0023] Step 2: obtaining real-time measured temperature data of the heating unit and the conductive unit through the monitoring unit;

[0024] Step 3: compare the real-time measured temperature data of the two-color infrared thermometer with the temperature simulation value of the current load core area of ​​the finite element simulation model in real time in situ to obtain deviation data;

[0025] Step 4: When the deviation data in step 3 is greater than the set deviation corresponding to the two-color infrared thermometer, a feedback current is obtained. If the feedback current is within a preset limited current interval, the output power of the electrode is adjusted based on the feedback current. When the feedback current exceeds the limited current interval, the electrode movement data is obtained. Based on the electrode movement data, the electrodes are driven to move closer to or farther from each other, so that the deviation data is less than or equal to the set deviation data.

[0026] Step 5: Compare the real-time measured temperature data of two sets of high-temperature thermocouples and one set of low-temperature thermocouples with the corresponding real-time temperature simulation values ​​of the surrounding areas of the finite element simulation model to obtain three sets of deviation data;

[0027] Step 6: When any one of the three sets of deviation data in step 5 is greater than its corresponding set deviation based on the two sets of high-temperature thermocouples and one set of low-temperature thermocouples, the electrode movement data is obtained, and when the electrode movement data belongs to the limited displacement interval, the electrodes are driven to move closer to each other based on the electrode movement data;

[0028] When the electrode movement data exceeds a limited displacement interval, a feedback current is obtained, and the output power of the electrode is adjusted based on the feedback current so that the deviation data is less than or equal to a set deviation.

[0029] Furthermore, the step 1 comprises:

[0030] The real-time current input value, the three-dimensional structure of the metal vessel, the conductive powder, the electrode and the sample are obtained, and the finite element simulation model is obtained based on the mode of coupling the electric field and the thermal field; the physical performance parameters of the metal vessel, the conductive powder, the electrode and the sample are defined, and the physical performance parameters include material density, specific heat capacity, thermal conductivity, electrical conductivity, relative dielectric constant, surface emissivity, thermal expansion coefficient and specific heat rate, so that the physical performance parameters meet the parameter requirements of the current conservation equation, the heat conduction equation, the thermal radiation equation and the thermal convection equation; the current input value and the potential value in the real-time input finite element simulation model are controlled, and the current parameters of the simulation model are kept synchronized with the real-time current input value of the electrode, the changes in the transient temperature zone in the coupling field are simulated, and the real-time temperature field distribution images of the whole and local parts of the simulation model during the thermal process are obtained.

[0031] Furthermore, step one also includes changing the shape of the upper electrode plate in the simulation model, and the shape of the upper electrode plate is changed to at least columnar, conical, plate-shaped, mesh-shaped, and curved, so as to obtain different real-time temperature field distribution images of the whole and local parts of the simulation model under different upper electrode plates.

[0032] Furthermore, in step 4, if the feedback current is lower than the lower limit of the limited current, the electrodes move closer to each other; if the feedback current is higher than the upper limit of the limited current, the electrodes move away from each other.

[0033] Furthermore, when all the deviation data are smaller than or equal to the corresponding set deviation data, no instruction or action is executed.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The real-time temperature of the surrounding area of ​​the conductive powder bed, the real-time temperature of the current load core area, and the real-time temperature of the metal container are monitored through the multi-station monitoring unit, realizing real-time visual monitoring of the temperature field of the conductive powder bed in the whole area;

[0036] Based on the real-time current input value and the finite element simulation model, the real-time global temperature simulation value of the conductive powder bed and its real-time temperature field distribution image are obtained. The real-time measured temperature data of the conductive powder bed in the whole area are compared with the temperature simulation data obtained by the finite element simulation model to obtain the deviation data. The output power or electrode movement of the electrode is precisely controlled in real time according to the deviation data, thereby precisely controlling the real-time temperature of the global temperature field of the conductive powder bed.

[0037] Therefore, the present invention realizes real-time visual monitoring and precise control of the global temperature field of the conductive powder bed.

[0038] 2. The present invention designs the electrode structure, and the temperature field distribution under different electrode structures is different. Electrodes with different plate shapes can be selected for heating work according to the shape, size, microstructure and performance requirements of the sample to be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the temperature field measurement and control system of the present invention, in which the furnace door is in an open state;

[0040] Figure 2 It is a structural schematic diagram of the temperature field measurement and control system of the present invention, in which the furnace door is in a closed state;

[0041] Figure 3 It is a schematic diagram of the internal structure of the metal container of the present invention;

[0042] Figure 4 is a schematic diagram of the first electrode structure of the present invention;

[0043] Figure 5 It is a schematic diagram of the plate structure of the first electrode of the present invention;

[0044] Figure 6 The real-time temperature field distribution image obtained by the finite element simulation model program using the first electrode of the present invention;

[0045] Figure 7 is a schematic diagram of a second electrode structure of the present invention;

[0046] Figure 8 is a schematic diagram of the electrode plate structure of the second electrode of the present invention;

[0047] Fig. 9 The real-time temperature field distribution image obtained by the finite element simulation model program using the second electrode of the present invention;

[0048] Fig.10 is a schematic diagram of a third electrode structure of the present invention;

[0049] Fig.11 is a schematic diagram of the plate structure of the third electrode of the present invention;

[0050] Fig.12 The real-time temperature field distribution image obtained by the third electrode based on the finite element simulation model program of the present invention;

[0051] Fig.13 is a schematic diagram of a fourth electrode structure of the present invention;

[0052] Fig.14 is a schematic diagram of the plate structure of the fourth electrode of the present invention;

[0053] Fig.15 The real-time temperature field distribution image obtained by the fourth electrode based on the finite element simulation model program of the present invention;

[0054] Fig.16 is a schematic diagram of a fifth electrode structure of the present invention;

[0055] Fig.17 is a schematic diagram of the plate structure of the fifth electrode of the present invention;

[0056] Fig.18 The real-time temperature field distribution image obtained by the fifth electrode based on the finite element simulation model program of the present invention;

[0057] Fig.19 It is a real-time temperature field distribution image obtained by the finite element simulation model program of the electrode using the plate-shaped electrode of the present invention, in which the numerical deviation between the measured temperature of the thermocouple 1 and its corresponding simulation temperature is greater than the set deviation;

[0058] Fig. 20 The simulated temperature field distribution image after the electrode displacement is regulated by the temperature field measurement and control method based on finite element simulation of the present invention;

[0059] Fig.21 It is a real-time temperature field distribution image obtained by the finite element simulation model program of the electrode using the plate-shaped electrode of the present invention. In the figure, the deviation between the measured temperature of thermocouple 2 and its corresponding simulation temperature is greater than the set deviation, and the electrode movement data exceeds the limited displacement range;

[0060] Fig. 22 It is a simulated temperature field distribution image after the output power of the electrode is regulated by the temperature field measurement and control method based on finite element simulation of the present invention;

[0061] In the picture

[0062] degC stands for degrees Celsius;

[0063] Reference numerals:

[0064] 1-Dual-color infrared thermometer; 2-Program-controlled motor; 3-Infrared thermometer bracket; 4-Power interface; 5-Thermocouple 1; 6-Thermocouple 2; 7-Temperature measuring window; 8-Transmission mechanism; 9-Electrode clamping device; 10-Exhaust valve; 11-Observation window; 12-Upper electrode; 13-Thermocouple 3; 14-Hinge; 15-Inlet valve; 16-Positioning base; 17-Metal container; 18-Lower electrode; 19-Conductive powder bed; 20-Program-controlled power supply; 21-Computer system; 22-Multi-channel data acquisition card; 23-Furnace body; 24-Furnace door; 25-Surrounding area; 26-Current load core area. DETAILED DESCRIPTION

[0065] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0066] Embodiment 1

[0067] refer to Figure 1 and Figure 2 The structure shown in this embodiment provides a temperature field measurement and control system based on finite element simulation, including:

[0068] A heating unit, the heating unit comprising a metal container 17, wherein the metal container 17 is filled with a conductive powder bed 19 composed of conductive powder;

[0069] refer to Figure 3 The structure shown is a conductive unit, which includes two groups of electrodes that can move toward or oppositely, the two groups of electrodes are wrapped in a conductive powder bed 19, and the sample is placed between the two groups of electrodes; the two groups of electrodes are divided into positive electrodes and negative electrodes according to polarity, a gap is left between the positive electrode and the negative electrode and they are symmetrically arranged in the conductive powder bed 19, and the two groups of electrodes apply current load to the conductive powder bed 19.

[0070] A monitoring unit, wherein the monitoring unit monitors the real-time temperature of the surrounding area 25 in the conductive powder bed 19, the real-time temperature of the current load core area 26 and the real-time temperature of the metal container 17; wherein the two groups of electrodes are divided into an upper electrode 12 and a lower electrode 18 according to their positional relationship, and the upper electrode 12 and the lower electrode 18 are symmetrically arranged in the conductive powder bed 19 along the vertical direction; the gap between the lower surface of the electrode plate of the upper electrode 12 and the upper surface of the electrode plate of the lower electrode 18 forms the current load core area 26, and the area outside the current load core area 26 is the surrounding area 25; the sample will be placed in the current load core area 26, and under the current load, the current load core area 26 will generate heat through the Joule effect.

[0071] The conductive powder is one or a mixture of any of graphite, carbon powder, carbon nanomaterials, and carbide. The mixture is a high-temperature resistant powder. The conductive powder is directly filled into the metal container 17 to form a conductive powder bed 19. Heat is efficiently generated through the Joule effect under current load, and no additional insulating material is required between the conductive powder and the metal container 17. The sample is placed in the conductive powder bed 19, and the conductive powder can form an all-round three-dimensional wrapping of the sample. Therefore, the present invention has no restrictions on the shape, structure, volume and size of the sample.

[0072] like Figure 3 As shown, when the two groups of electrodes are displaced and the distance between the two groups of electrodes changes, the stacking state of the conductive powder in the current load core area 26 changes, and the pressure between the plates changes, so the resistance value and thermal conductivity change accordingly, thereby producing an in-situ impact and change on the generation and transfer of heat. The conductive powder in the surrounding area 25 is relatively loosely stacked, has high resistance and low thermal conductivity compared to the conductive powder in the current load core area 26, and therefore does not serve as the main current path. The conductive powder in the surrounding area 25 exists as a low thermal conductivity material, forming thermal insulation for the current load core area 26, and efficiently controls the Joule heat around the current load core area 26, thereby quickly establishing a thermal balance between the sample and the conductive powder, greatly improving the heating efficiency, effectively reducing heat dissipation, reducing energy loss, and saving energy. At the same time, it is easy to achieve ultra-fast heating in a wide temperature range and safe insulation at ultra-high temperatures without the need to add additional insulation materials or structures, avoiding the use of additional insulation or insulating materials, simplifying the heating system structure, and reducing manufacturing costs. In addition, for ultra-fast high-temperature manufacturing of large-size samples, the integrity of the sample structure and heating uniformity can be ensured, thereby improving product quality.

[0073] like Figure 1 and Figure 2 As shown, the temperature field measurement and control system further includes a furnace body 23, which is a closed cavity. The furnace body 23 has a furnace door 24 that can be opened or closed. In this embodiment, Figure 1 As shown, the furnace body 23 is connected to the furnace door 24 by a hinge 14. The metal vessel 17 is placed in the furnace body 23, and a positioning base 16 is fixed to the inner bottom of the furnace body 23, and the bottom of the metal vessel 17 is fixed to the upper surface of the positioning base 16. In this embodiment, the size of the furnace body 23 can be flexibly changed according to the application scenario and the sample size, and the metal vessel 17 is a metal crucible.

[0074] The furnace body 23 itself can form a stainless steel vacuum cavity to achieve a certain degree of heat preservation effect. The metal container 24 is arranged in the stainless steel vacuum cavity. Figure 1As shown, the outer surface of the furnace body 23 is provided with a vacuum pump interface, an air outlet valve 10, and an air inlet valve 15 on the side corresponding to the air outlet valve 10. The vacuum pump interface is connected to a vacuum pump, which is an existing device. The vacuum pump uses mechanical, physical, chemical or physical and chemical methods to evacuate the furnace body 23 so that the furnace body 23 obtains a vacuum environment. An observation window 11 is also provided on the outer surface of the furnace body 23 for real-time observation of the internal situation of the furnace body 23 during high-temperature sintering.

[0075] like Figure 1 , Figure 2 As shown, an infrared thermometer bracket 3, a temperature measuring window 7, a power interface 4 and a motor interface are provided on the top of the furnace body 23. The temperature measuring window 7 is located directly below the infrared thermometer bracket 3. The connecting end of the power interface 4 is connected to a programmable power supply 20 through a power line. The programmable power supply 20 is respectively connected to the upper electrode 12 and the lower electrode 18 through the power line to provide current for the two groups of electrodes.

[0076] like Figure 1 As shown, a program-controlled motor 2 is installed on the motor interface at the top of the furnace body 23, and a transmission mechanism 8 is provided at the lower end of the motor interface. The transmission mechanism 8 is a linear motion mechanism, and the lower end of the transmission mechanism 8 is connected to the electrode clamping device 9, and the electrode clamping device 9 is used to clamp the upper electrode 12, and the lower electrode 18 is fixed on the inner bottom surface of the metal vessel 17. The program-controlled motor 2 drives the transmission mechanism 8 to change the distance between the electrodes, and the contact and stacking state between the sample and the conductive powder is changed through the displacement of the electrodes, so as to realize the in-situ real-time control of the resistance value and thermal conductivity of the conductive powder in the current load core area 26 during the power-on heating process, and finally realize the dynamic and precise regulation of the thermal efficiency and heat distribution during the entire heating process.

[0077] The specific principle is: the programmable motor 2 drives the transmission mechanism 8 to move up and down, thereby driving the upper electrode 12 to move in the vertical direction. Figure 3 As shown, the upper electrode 12 moves downward, the distance between the upper electrode 12 and the lower electrode 18 decreases, the pressure on the conductive powder between the two groups of electrodes increases, and the conductive powder accumulation state in the current load core area 26 directly in contact with the two groups of electrodes tends to be compact, resulting in reduced resistance and increased thermal conductivity; the upper electrode moves upward, the distance between the upper electrode 12 and the lower electrode 18 increases, the pressure on the conductive powder between the two groups of electrodes decreases, and the conductive powder accumulation state in the current load core area 26 directly in contact with the electrodes tends to be loose, so the resistance increases and the thermal conductivity decreases; in addition, during the sample cooling process, the upward movement of the upper electrode can improve the heat dissipation efficiency of the conductive powder bed 19 in the current load core area 26, thereby accelerating the sample cooling.

[0078] like Figure 1As shown, the monitoring unit includes two sets of high-temperature thermocouples, one set of low-temperature thermocouples and a two-color infrared thermometer 1. The two sets of high-temperature thermocouples are thermocouple one 5 and thermocouple two 6, and one set of low-temperature thermocouples is thermocouple three 13; thermocouple one 5 and thermocouple two 6 are arranged on the upper surface of the furnace body 23, and thermocouple three 13 is arranged on the outer surface of the furnace body 23. The aforementioned arrangement refers to the connection and fixing part of the thermocouples. The thermocouples are mainly tested at the corresponding parts through the temperature measuring ends. The temperature measuring ends of thermocouple one 5 and thermocouple two 6 pass through the upper wall of the furnace body 23 and extend to the surrounding area 25 of the conductive powder bed 19 in the metal container 17. The temperature measuring end of thermocouple three 13 passes through the outer wall of the furnace body 23 and touches the outer wall of the metal container 17; the two-color infrared thermometer 1 is installed On the infrared thermometer bracket 3, the infrared thermometer bracket 3 is arranged at the center position of the top of the furnace body 23, and the temperature measuring end of the two-color infrared thermometer 1 passes through the temperature measuring window 7 and the axial passage inside the upper electrode 12. When in use, the two-color infrared thermometer 1 can directly observe the center position of the conductive powder bed 19 through the temperature measuring window 7 on the upper wall of the furnace body 23 and the middle passage of the upper electrode 12, and can directly measure the temperature of the central area between the upper electrode 12 and the lower electrode 18 plates, so as to more accurately determine the real-time temperature data; therefore, thermocouple 1 5 and thermocouple 2 6 collect the real-time temperature of the surrounding area 25 in the conductive powder bed 19, thermocouple 3 13 collects the real-time temperature of the metal container 17, and the two-color infrared thermometer 1 collects the real-time temperature of the current load core area 26.

[0079] like Figure 2 As shown, a multi-channel data acquisition card 22 is also arranged outside the furnace body 23, and the multi-channel data acquisition card 22 is connected with thermocouple 1 5, thermocouple 2 6, thermocouple 3 13 and two-color infrared thermometer 1 through a data transmission line, and the multi-channel data acquisition card 22, programmable motor 2 and programmable power supply 20 are connected with the computer system 21 through a signal transmission line, and the computer system 21 program records the temperature data collected by the multi-channel data acquisition card 22 and feeds back to the monitoring interface in real time, and the collected temperature data is compared in real time with the temperature of the corresponding spatial position in the real-time temperature field distribution image obtained by the finite element simulation model program, so as to clarify the deviation of the temperature field distribution simulation result, and finally realize the real-time dynamic visualization monitoring and precise control of the global temperature field of the conductive powder bed 19 during the whole heating process.

[0080] Therefore, the conductive powder is used as both a heating element and a heat-insulating structural material, which can not only ensure the ultra-fast heating effect of the current-load core area 26 and obtain a safe and stable working environment above 3000°C, but also change the contact and stacking state between the sample and the conductive powder by displacing the upper electrode 12, and adjust the resistance value and thermal conductivity of the conductive powder current-load core area 26 in real time in situ, thereby realizing dynamic and precise control of the thermal efficiency and heat distribution of the whole process of heating, heat preservation and cooling. Therefore, the present invention does not need to use additional insulating material or heat-insulating material between the conductive powder and the metal vessel 17.

[0081] According to the requirements of sample structure, size and product performance, the shape, structure and size of the electrode and other structural elements are specially designed to achieve precise control of the temperature field range and distribution form of the heating area. Therefore, the plates of the upper electrode 12 and the lower electrode 18 can be set to any shape as needed;

[0082] The electrode includes a pole plate and a pole column connected to each other. The pole plate is arranged close to the current load core area 26 , and the pole column is arranged far away from the current load core area 26 .

[0083] In this embodiment, the lower electrode 18 is fixedly arranged, and the electrode plate of the lower electrode 18 is preferably in a plate shape. It is only necessary to change the structure of the upper electrode 12 to obtain real-time temperature field distribution images under electrodes of various structures. Figures 4 to 18 Five preferred electrode shape structures and their corresponding real-time temperature field distribution images obtained based on the finite element simulation model program are shown.

[0084] In this embodiment, at least one through hole is opened on the electrode plate of the upper electrode 12, and multiple through holes are evenly distributed on the electrode plate of the upper electrode 12. The through holes are used for conductive powder to pass through. The electrode plate can be in various forms including columnar, conical, plate-shaped, mesh, curved, etc.

[0085] Embodiment 2

[0086] On the basis of the first embodiment, the electrode plate of the upper electrode 12 in this embodiment is integrated with the electrode column. Specifically, Figure 4 , Figure 5 As shown, the upper electrode 12 adopts a columnar structure, and a through hole is set in the upper electrode 12 along the axial center. The temperature measuring end of the two-color infrared thermometer 1 passes through the temperature measuring window 7 and extends to the through hole and then enters the current load core area 26; based on the electrode structure of the columnar upper electrode 12, a real-time temperature field distribution image of a sample is obtained by using a finite element simulation model program, as shown in FIG. Figure 6 shown.

[0087] Embodiment 3

[0088] On the basis of the first embodiment, the electrode plate of the upper electrode 12 in this embodiment adopts a cone-shaped structure, specifically, as shown in FIG. Figure 7 , Figure 8 As shown, the lower surface of the electrode plate is a conical surface, the upper surface of the electrode plate is a conical surface, the electrode plate has a certain thickness, and a plurality of through holes with small apertures are evenly opened on the electrode plate, and the through holes are used for conductive powder to pass through; the through hole in the center of the electrode plate extends to the axial passage of the pole, and the temperature measuring end of the two-color infrared thermometer 1 passes through the temperature measuring window 7 to enter the axial passage of the pole, and then passes through the through hole in the center of the conical electrode plate to enter the current load core area 26; based on the electrode structure of the upper electrode 12 of the conical electrode plate, the real-time temperature field distribution image of the same sample as in Example 2 is obtained by using the finite element simulation model program, as shown Fig. 9 shown.

[0089] Embodiment 4

[0090] On the basis of the first embodiment, the electrode plate of the upper electrode 12 in this embodiment adopts the optimal electrode plate structure, that is, a plate-shaped structure. Specifically, Fig.10 , Fig.11 As shown, the lower surface of the plate is a circular surface, the upper surface of the plate is a circular surface, the plate has a certain thickness, and a plurality of through holes with small apertures are evenly opened on the plate, and the through holes are used for conductive powder to pass through; the through hole in the center of the plate extends to the axial passage of the pole, and the temperature measuring end of the two-color infrared thermometer 1 passes through the temperature measuring window 7 to enter the axial passage of the pole, and then passes through the through hole in the center of the plate-shaped plate to enter the current load core area 26; based on the electrode structure of the upper electrode 12 of the plate-shaped plate, the real-time temperature field distribution image of the same sample as in Example 2 is obtained by using the finite element simulation model program, as shown Fig.12 shown.

[0091] Embodiment 5

[0092] On the basis of the first embodiment, the electrode plate of the upper electrode 12 in this embodiment adopts a mesh structure, specifically, as Fig.13 , Fig.14 As shown, the lower surface of the electrode plate is a circular surface, the upper surface of the electrode plate is a circular surface, the electrode plate has a certain thickness, and a plurality of small-aperture through holes of different shapes are evenly opened on the electrode plate. The small-aperture through holes are square, trapezoidal, triangular, etc. The square, trapezoidal, and triangular through holes of small apertures are distributed in a grid shape on the electrode plate, and the through holes are used for conductive powder to pass through; the through hole in the center of the electrode plate extends to the axial passage of the pole, and the temperature measuring end of the two-color infrared thermometer 1 passes through the temperature measuring window 7 to enter the axial passage of the pole, and then passes through the through hole in the center of the plate-shaped electrode to enter the current load core area 26; based on the electrode structure of the upper electrode 12 of the mesh electrode plate, the real-time temperature field distribution image of the same sample as that of Example 2 is obtained by using a finite element simulation model program, as shown Fig.15 shown.

[0093] Embodiment 6

[0094] On the basis of the first embodiment, the electrode plate of the upper electrode 12 in this embodiment adopts a curved surface structure, specifically, Fig.16 , Fig.17 As shown, the lower surface of the plate is a curved surface, the upper surface of the plate is a curved surface, the plate has a certain thickness, and a plurality of through holes with small apertures are evenly opened on the plate, and the through holes are used for conductive powder to pass through; the through hole in the center of the plate extends to the axial passage of the pole, and the temperature measuring end of the two-color infrared thermometer 1 passes through the temperature measuring window 7 to enter the axial passage of the pole, and then passes through the through hole in the center of the plate-shaped plate to enter the current load core area 26; based on the electrode structure of the upper electrode 12 of the curved plate, the real-time temperature field distribution image of the same sample as in Example 2 is obtained by using the finite element simulation model program, as shown Fig.18 shown.

[0095] Through the above five real-time temperature field distribution images, it can be seen that each electrode form corresponds to a different temperature field range. Therefore, the upper electrode 12 with different electrode shapes can be selected for heating work according to work needs to prepare samples with different shapes, sizes, microstructures, and performance requirements, as well as samples with heterogeneous structures and phase compositions.

[0096] Therefore, through the temperature field shown in the finite element simulation image, electrodes with different plate shapes can be selected for heating work according to work needs.

[0097] Embodiment 7

[0098] In this embodiment, a temperature field measurement and control method based on finite element simulation is provided, and the method comprises the following steps:

[0099] Step 1: Based on the real-time current input value and the finite element simulation model, obtain the real-time global temperature simulation value of the conductive powder bed and its real-time temperature field distribution image;

[0100] Step 2: obtaining real-time measured temperature data of the heating unit and the conductive unit through the monitoring unit;

[0101] Step 3: Compare the real-time measured temperature data of the two-color infrared thermometer with the simulated temperature value of the core area of ​​the current load in real time and in situ to obtain deviation data;

[0102] Step 4: When the deviation data in step 3 is greater than the set deviation corresponding to the two-color infrared thermometer, a feedback current is obtained. If the feedback current is in a preset limited current range, the output power of the electrode is adjusted based on the feedback current. When the feedback current exceeds the limited current range, the electrode movement data is obtained. Based on the electrode movement data, the electrodes are driven to move closer to or away from each other so that the deviation data is less than or equal to the set deviation.

[0103] Specifically, for the automatic control process of the thermal process, the control principle and logic are as follows: during the thermal process, the two-color infrared thermometer 1 measures the temperature data of the current load core area 26 in real time, and the obtained temperature data is communicated and recorded in real time with the computer system 21 through NI-LabVIEW or the host computer program, and is compared in real time with the temperature of the spatial position corresponding to the real-time temperature field distribution image obtained based on the finite element simulation model to obtain the deviation data between the two; when the deviation data is greater than the set deviation, the feedback current is obtained, and if the feedback current is within the preset limited current interval, the feedback current instruction is fed back to the programmable power supply 20, and within the preset limited current Within the interval, the programmable power supply 20 outputs current to the electrode and the heating unit; when the output current value exceeds the upper and lower limits of the specified current interval, the program will send an electrode movement data instruction to the programmable motor 2, and the programmable motor 2 controls the lifting and lowering of the transmission mechanism 8 based on the electrode movement data, and then controls the upper electrode 12 to perform an upward or downward movement, that is, increasing or decreasing the resistance value of the conductive powder in the current load core area 26, which is equivalent to reducing or increasing the thermal conductivity of the conductive powder in this area, and finally realizing the process in-situ control and rapid response under the PID logic algorithm, so that the entire "heating-keeping-cooling" thermal process can obtain the desired precise temperature control.

[0104] The specific control process is that the upper electrode 12 realizes real-time displacement under the control and drive of the computer system 21 program and the programmable motor 2. Through the displacement, the in-situ real-time control of the resistance value and thermal conductivity of the conductive powder in the current load core area 26 is realized, thereby realizing the dynamic and precise regulation of the thermal efficiency and heat distribution in the whole thermal process; the upper electrode 12 moves downward, the electrode spacing decreases, and the conductive powder accumulation state in the current load core area 26 directly contacting the electrode tends to be compact, so the resistance decreases and the thermal conductivity increases; the upper electrode 12 moves upward, the electrode spacing increases, and the conductive powder accumulation state in the current load core area 26 directly contacting the electrode tends to be loose, so the resistance increases and the thermal conductivity decreases; in addition, the upper electrode 12 moves upward during the cooling process, which can improve the heat dissipation efficiency of the current load core area 26 of the conductive powder bed 19 and accelerate the cooling of the sample. The real-time resistance value change of the conductive powder in the current load core area 26 can be reflected by the sample heating efficiency directly measured by the two-color infrared thermometer 1, and can also be derived by the current and voltage measurement values; the thermal conductivity of the conductive powder in the current load core area 26 is derived by the measured thermal conductivity, infrared real-time temperature and temperature function: the resistance value and thermal conductivity of the surrounding area 25 are derived from the room temperature measured data, the high-temperature thermocouple real-time temperature and temperature function; the real-time temperature, resistance value and thermal conductivity of the metal container 17 are derived from the room temperature measured data, the thermocouple 13 real-time temperature and temperature function; the thermal conductivity of the entire area can be reflected by the heat transfer efficiency in the conductive powder bed 19 measured and derived by the two-color infrared thermometer and the multi-station thermocouple. However, other existing rapid thermal equipment does not have the finite element real-time simulation and temperature field monitoring functions.

[0105] The method of obtaining the real-time temperature field distribution image through the finite element simulation model program is:

[0106] The real-time current input value, the three-dimensional structure of the metal vessel 17, the conductive powder, the electrode and the sample are obtained, and a preliminary simulation model is obtained based on the mode of coupling the electric field and the thermal field; the physical performance parameters such as material density, specific heat capacity, thermal conductivity, surface emissivity, electrical conductivity, relative dielectric constant, surface emissivity, thermal expansion coefficient and specific heat rate of the metal vessel 17, the conductive powder, the electrode and the sample are defined to satisfy the parameter requirements of the current conservation equation, the heat conduction equation, the thermal radiation equation and the thermal convection equation; the current density and electric potential values ​​in the input simulation model are controlled to simulate the changes in the transient temperature zone in the coupling field, and the real-time temperature field distribution images of the whole and local parts of the simulation model during the thermal process are obtained.

[0107] The specific steps of the finite element simulation model are as follows: the finite element simulation model is based on the three-dimensional structure of a real metal crucible, conductive powder, electrode and sample, and adopts the mode of coupling electric field and thermal field, and the simulation model is input into the COMSOL multi-physics field simulation software; then the physical performance parameters such as material density, specific heat capacity, thermal conductivity, surface emissivity, electrical conductivity, relative dielectric constant, surface emissivity, thermal expansion coefficient and specific heat rate of the metal crucible, conductive powder, electrode and sample are defined to meet the parameter requirements of the current conservation equation, heat conduction equation, thermal radiation equation and thermal convection equation; on the basis of considering the heat conduction and thermal radiation between the conductive powder and the sample, as well as the thermal radiation of the surface of the simulation model to the external environment, by controlling the current density and potential values ​​in the input simulation model, the changes in the transient temperature zone in the coupling field are simulated, and the real-time temperature field distribution images of the whole and local simulation model in the thermal process are obtained.

[0108] Among them, the simulation process is a process controlled by a computer program, so the current input value is also completed by a computer program (or manually). Here, the current value input to the simulation model (computer program) is synchronized with the current value input by the programmable power supply 20; the resistance value of the current load core area 26 of the conductive powder bed 19 is derived from the in-situ measurement of the experimental process, and the thermal conductivity of the current load core area 26 of the conductive powder bed 19 is derived from the measured thermal conductivity, infrared real-time temperature and temperature function under different stacking states; the resistance value and thermal conductivity of the surrounding area 25 are derived from the room temperature measured data, the real-time temperature of thermocouple 15 and thermocouple 26 and the temperature function; the real-time temperature, resistance value and thermal conductivity of the metal crucible are derived from the room temperature measured data, the real-time temperature of thermocouple 3 13 and the temperature function. Therefore, a two-color infrared thermometer 1 and thermocouple 1 5 , thermocouple 2 6 , and thermocouple 3 13 are used to simultaneously perform real-time temperature measurement on the sample current load core area 26 , the surrounding area 25 , and the metal crucible. In conjunction with the finite element simulation model, accurate measurement of the sample temperature and real-time dynamic visualization monitoring and precise control of the global temperature field of the conductive powder bed 19 are achieved.

[0109] The temperature field measurement and control method further comprises:

[0110] Step 5: The real-time measured temperature data of two sets of high-temperature thermocouples and one set of low-temperature thermocouples are respectively compared with the real-time temperature simulation values ​​corresponding to the surrounding areas of the finite element simulation model, that is, real-time in-situ comparison is performed with the temperature of the corresponding spatial position in the real-time temperature field distribution image to obtain three sets of deviation data;

[0111] Step 6: When any one of the three sets of deviation data in step 5 is greater than the set deviation based on the two sets of high-temperature thermocouples and the one set of low-temperature thermocouples, the electrode movement data is obtained, and when the electrode movement data belongs to the limited displacement interval, the electrodes are driven to move closer to each other;

[0112] When the electrode movement data exceeds the limited displacement range, a feedback current is obtained, and the output power of the electrode is adjusted based on the feedback current so that the deviation data is less than or equal to the set deviation; when the three sets of deviation data are all less than or equal to their corresponding set deviations, no instructions or actions are executed.

[0113] Execute step 5 to obtain a global real-time simulated temperature field distribution image of the plate-shaped electrode at a certain time based on a finite element simulation model program, such as Fig.19 As shown; the real-time measured temperature data of the thermocouple 5 at this time and Fig.19 The real-time temperature simulation values ​​of the corresponding positions of the surrounding areas in the global real-time temperature field distribution image are compared to obtain the deviation data corresponding to the thermocouple 5;

[0114] Continue to execute step 6. When the deviation data based on the thermocouple 15 is greater than the set deviation data based on the thermocouple 15, the electrode movement data is obtained. When the electrode movement data belongs to the limited displacement range, the upper electrode 12 is driven to move downward based on the electrode movement data, and the global real-time simulation temperature field distribution image after the electrode displacement is adjusted is obtained, such as Fig. 20 shown.

[0115] Execute step 5 to obtain a global real-time simulated temperature field distribution image of the finite element simulation model of the plate-shaped electrode at a certain time, such as Fig.21 The real-time measured temperature data of the thermocouple 26 at this time is compared with Fig.21 The real-time temperature simulation values ​​of the corresponding positions of the surrounding areas in the global real-time temperature field distribution image are compared to obtain the deviation data corresponding to the thermocouple 26;

[0116] Continue to execute step 6. When the deviation data based on the thermocouple 26 is greater than the set deviation data based on the thermocouple 26, the electrode movement data is obtained. When the electrode movement data exceeds the limited displacement range, the feedback current is obtained. The full-domain real-time simulated temperature field distribution image after the electrode output power is accurately controlled according to the feedback current is as follows: Fig. 22 shown.

[0117] Therefore, the temperature field measurement and control method based on finite element simulation can accurately control the temperature field of the conductive powder bed by moving the electrode or the output power of the electrode.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention itself. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. The temperature field measurement and control system based on finite element simulation is characterized by: include, A heating unit, the heating unit comprising a metal container filled with a conductive powder bed composed of conductive powder; A conductive unit, wherein the conductive unit comprises two groups of electrodes that can move toward or away from each other, the two groups of electrodes are wrapped in a conductive powder bed, and the sample is placed between the two groups of electrodes; the conductive unit also comprises a transmission mechanism, the transmission mechanism is connected to at least one group of electrodes, and drives the electrodes connected thereto to move, so that the distance between the two groups of electrodes increases or decreases; A monitoring unit, wherein the monitoring unit monitors the real-time temperature of the surrounding area in the conductive powder bed, the real-time temperature of the current load core area and the real-time temperature of the metal container, wherein the current load core area is the area between two groups of electrodes in the conductive powder bed, and the area outside the current load core area is the surrounding area; the monitoring unit comprises two sets of high-temperature thermocouples, one set of low-temperature thermocouples and a two-color infrared thermometer, wherein the temperature measuring ends of the two sets of high-temperature thermocouples are located in the surrounding area, the temperature measuring end of one set of low-temperature thermocouples is in contact with the metal container, and the temperature measuring end of the two-color infrared thermometer is located in the current load core area.

2. The temperature field measurement and control system according to claim 1, characterized in that: The two groups of electrodes are divided into an upper electrode and a lower electrode, and at least one through hole is provided on the electrode plate of the upper electrode.

3. The temperature field measurement and control system according to claim 2, characterized in that: The pole plate of the upper electrode at least includes a columnar shape, a cone shape, a plate shape, a mesh shape, and a curved surface shape.

4. A temperature field measurement and control method based on finite element simulation, using the temperature field measurement and control system according to claim 2 or 3, characterized in that: The method comprises the following steps, Step 1: Based on the real-time current input value and the finite element simulation model, obtain the real-time global temperature simulation value of the conductive powder bed and its real-time temperature field distribution image; Step 2: obtaining real-time measured temperature data of the heating unit and the conductive unit through the monitoring unit; Step 3: compare the real-time measured temperature data of the two-color infrared thermometer with the temperature simulation value of the current load core area of ​​the finite element simulation model in real time in situ to obtain deviation data; Step 4: When the deviation data in step 3 is greater than the set deviation corresponding to the two-color infrared thermometer, a feedback current is obtained. If the feedback current is within a preset limited current interval, the output power of the electrode is adjusted based on the feedback current. When the feedback current exceeds the limited current interval, the electrode movement data is obtained. Based on the electrode movement data, the electrodes are driven to move closer to or farther from each other, so that the deviation data is less than or equal to the set deviation data. Step 5: Compare the real-time measured temperature data of two sets of high-temperature thermocouples and one set of low-temperature thermocouples with the corresponding real-time temperature simulation values ​​of the surrounding areas of the finite element simulation model to obtain three sets of deviation data; Step 6: When any one of the three sets of deviation data in step 5 is greater than its corresponding set deviation based on the two sets of high-temperature thermocouples and one set of low-temperature thermocouples, the electrode movement data is obtained, and when the electrode movement data belongs to the limited displacement interval, the electrodes are driven to move closer to each other based on the electrode movement data; When the electrode movement data exceeds a limited displacement interval, a feedback current is obtained, and the output power of the electrode is adjusted based on the feedback current so that the deviation data is less than or equal to a set deviation.

5. The temperature field measurement and control method according to claim 4, characterized in that: The step one comprises: The real-time current input value, the three-dimensional structure of the metal vessel, the conductive powder, the electrode and the sample are obtained, and the finite element simulation model is obtained based on the mode of coupling the electric field and the thermal field; the physical performance parameters of the metal vessel, the conductive powder, the electrode and the sample are defined, and the physical performance parameters include material density, specific heat capacity, thermal conductivity, electrical conductivity, relative dielectric constant, surface emissivity, thermal expansion coefficient and specific heat rate, so that the physical performance parameters meet the parameter requirements of the current conservation equation, the heat conduction equation, the thermal radiation equation and the thermal convection equation; the current input value and the potential value in the real-time input finite element simulation model are controlled, and the current parameters of the simulation model are kept synchronized with the real-time current input value of the electrode, the changes in the transient temperature zone in the coupling field are simulated, and the real-time temperature field distribution images of the whole and local parts of the simulation model during the thermal process are obtained.

6. The temperature field measurement and control method according to claim 5, characterized in that: The step one also includes changing the shape of the upper electrode plate in the simulation model, and the shape of the upper electrode plate is changed to at least a columnar, conical, plate-like, mesh-like, or curved surface shape, so as to obtain different real-time temperature field distribution images of the entire and local parts of the simulation model under different upper electrode plates.

7. The temperature field measurement and control method according to claim 4, characterized in that: In step 4, if the feedback current is lower than the lower limit of the limited current, the electrodes move closer to each other; if the feedback current is higher than the upper limit of the limited current, the electrodes move away from each other.

8. The temperature field measurement and control method according to claim 4, characterized in that: When all the deviation data are less than or equal to the corresponding set deviation data, no instruction or action is executed.

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