Temperature damage detection method and temperature measuring device based on optimized vacuum sintering furnace

Abstract

The invention provides a temperature damage detection method based on an optimized vacuum sintering furnace and a temperature measuring device, and belongs to the related field of heat transfer science, and the method comprises the following steps: optimizing a vacuum sintering furnace structure by adopting different thermal insulation structures, and deducing a one-dimensional performance simulation model of a carbon felt thermal insulation layer; according to the one-dimensional performance simulation model of the carbon felt thermal insulation layer, the temperature rise curve and the workpiece temperature, the value range of the thickness of the carbon felt thermal insulation layer at different sintering temperatures is calculated by utilizing a reverse simulation principle, and then the optimal thickness of the carbon felt thermal insulation layer is obtained in the value range of the thickness of the carbon felt thermal insulation layer at different sintering temperatures by utilizing forward simulation; and the optimal thickness of the carbon felt heat preservation layer is adopted as the length of the temperature measuring device, the temperature measuring device of the vacuum sintering furnace is constructed, the temperature of the vacuum sintering furnace is measured through the multiple temperature measuring devices, and a temperature damage detection result is obtained according to the measurement result. According to the method, the problem that the temperature in the effective heating area after structure optimization cannot be directly measured due to too high temperature is solved.

Description

Technical Field

[0001] The invention belongs to the field of heat transfer, and in particular relates to a temperature damage detection method and a temperature measuring device based on an optimized vacuum sintering furnace. Background Art

[0002] Vacuum sintering technology combines vacuum technology with sintering process, which can significantly improve the performance of metal materials and workpieces. Vacuum sintering furnace is one of the key equipment for the production of special powder metallurgy and ceramic products, among which furnace temperature uniformity is the main indicator of the heating performance of the reaction vacuum furnace. The structure of the insulation system has an important influence on the furnace temperature uniformity, and the heat insulation screen is its core component. It is located in the furnace of the vacuum furnace as a whole, which can prevent heat loss and reduce the temperature difference in the furnace, which has an important influence on improving the temperature uniformity of the vacuum sintering furnace.

[0003] However, when simulating the improvement of thermal insulation performance after adopting different thermal insulation structures, it is generally carried out on the basis of the original equipment (not optimized), that is, there is only experimental data of the original equipment, and no experimental data after adopting the new structure. This leads to the lack of an accurate one-dimensional data model of the thermal insulation screen temperature drop when predicting the performance parameters of the sintering furnace after adopting the optimized structure. The thermal insulation screen structure has a great influence on the temperature control and heat dissipation loss of the sintering furnace, and according to the material output results, the most suitable thermal insulation screen equipment parameters are not matched.

[0004] If the insulation layer of the vacuum sintering furnace is set too thick or not thick enough during operation, it may affect the yield of the workpiece and the service life of the equipment, and greatly increase the energy consumption.

[0005] When the vacuum sintering furnace is sintering materials, there are slight differences depending on the structure of the workpiece being produced, so the sintering temperature fluctuates within a certain range, resulting in large fluctuations in the yield of the product. The heat insulation screen parameters of the furnace are generally fixed parameters, which affects the production results of the material. The heat insulation screen in the vacuum sintering furnace is generally composed of graphite plates and carbon felt, which is relatively easy to disassemble. Therefore, a simulation method for the thermal insulation performance of the insulation layer of the vacuum sintering furnace is needed to find the parameter range of the heat insulation screen structure, mainly the thickness of the carbon felt. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present application proposes a temperature damage detection method and a temperature measuring device based on an optimized vacuum sintering furnace.

[0007] In the first aspect, the present application proposes a temperature damage detection method based on an optimized vacuum sintering furnace, comprising:

[0008] According to the parameters of the vacuum sintering furnace body, the heat radiation and heat conduction model of the vacuum sintering furnace during the heating process is established. According to the heat radiation and heat conduction model, the temperature rise curve and the workpiece temperature are obtained;

[0009] The structure of the vacuum sintering furnace was optimized by using different insulation structures, the temperature of the vacuum sintering furnace after structural optimization was predicted by using parameter iteration method, and the one-dimensional performance simulation model of the carbon felt insulation layer was derived;

[0010] According to the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature, the thickness range of the carbon felt insulation layer at different sintering temperatures is calculated using the reverse simulation principle, and then the optimal thickness of the carbon felt insulation layer is obtained within the thickness range of the carbon felt insulation layer at different sintering temperatures using the forward simulation;

[0011] The optimal thickness of the carbon felt insulation layer is used as the length of the temperature measuring device, and a temperature measuring device for the vacuum sintering furnace is constructed. The temperature of the vacuum sintering furnace is measured using multiple temperature measuring devices, and the temperature damage detection result is obtained based on the measurement result.

[0012] The method of using parameter iteration to predict the temperature of the vacuum sintering furnace after structural optimization and derive a one-dimensional performance simulation model of the carbon felt insulation layer includes:

[0013] Step S2.1: using Fluent software to calculate the first total heat flux of the carbon felt insulation layer in the effective heating zone of the vacuum sintering furnace after structural optimization and the temperature of the workpiece in the first furnace;

[0014] Step S2.2: establishing a finite element model of the vacuum sintering furnace after structural optimization, taking the first total heat flux and the temperature of the workpiece in the first furnace as boundary conditions, and calculating the transient temperature of each layer of the graphite plate and the carbon felt insulation layer;

[0015] Step S2.3: averaging the transient temperatures of each layer of the graphite plate and the carbon felt insulation layer to obtain the temperature of each layer of the carbon felt insulation layer;

[0016] Step S2.4: taking the temperature of the first layer of the carbon felt insulation layer and the temperature of the second layer as reference, calculating the heat flux of the two layers;

[0017] Step S2.5: taking the heat flux of the two layers as the initial condition, calculating the second total heat flux of the carbon felt insulation layer in the effective heating area and the temperature of the workpiece in the second furnace;

[0018] Step S2.6: When the difference between the first total heat flux and the second total heat flux is less than a preset total heat flux threshold, or when the difference between the temperature of the workpiece in the first furnace and the temperature of the workpiece in the second furnace is less than a preset temperature threshold, stop the iteration, output the corresponding carbon felt insulation layer in the effective heating area, and go to step S2.7; otherwise, take the second total heat flux as the first total heat flux, take the temperature of the workpiece in the second furnace as the temperature of the workpiece in the first furnace, and go to step S2.2 to continue the iteration;

[0019] Step S2.7: Analyze the carbon felt insulation layer in the effective heating area corresponding to when the iteration stops, and derive a one-dimensional performance simulation model of the carbon felt insulation layer.

[0020] The one-dimensional performance simulation model of the carbon felt insulation layer is derived, and the calculation formula is as follows:

[0021]

[0022]

[0023]

[0024] Where λ is the thermal conductivity of carbon felt, T r is the temperature of the heating body, T1 is the temperature of the inner wall of the carbon felt, T2 is the temperature of the outer wall of the carbon felt, T3 is the temperature of the inner wall of the furnace shell, ε r is the blackness of the heating body, ε1 is the blackness of the inner wall of the carbon felt, ε2 is the blackness of the outer wall of the carbon felt, ε3 is the blackness of the inner wall of the furnace shell, A r is the area of ​​the heating body, A1 is the area of ​​the inner wall of the carbon felt, A2 is the area of ​​the outer wall of the carbon felt, A3 is the area of ​​the inner wall of the furnace shell, L is the height of the carbon felt, D1 is the diameter of the inner wall of the carbon felt, D2 is the diameter of the outer wall, To radiate the heating body to the inner wall of the carbon felt, For heat conduction in carbon felt, is the radiation of the carbon felt outer wall and the furnace shell, and σ0 is the radiation coefficient of the absolute black body.

[0025] The method comprises: calculating the value range of the thickness of the carbon felt insulation layer at different sintering temperatures according to the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature by using the reverse simulation principle, and then using the forward simulation to obtain the optimal thickness of the carbon felt insulation layer within the value range of the thickness of the carbon felt insulation layer at different sintering temperatures, including:

[0026] According to the finite element model of the vacuum sintering furnace after structural optimization, the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature are input, and the thickness range of the carbon felt insulation layer at different sintering temperatures is calculated using the inverse simulation principle;

[0027] According to the expected thickness of the carbon felt insulation layer, a forward simulation is performed on the finite element model of the vacuum sintering furnace after structural optimization, and the thickness that makes the temperature in the furnace most uniform is selected as the optimal thickness of the carbon felt insulation layer within the range of values ​​of the carbon felt insulation layer.

[0028] The temperature of the vacuum sintering furnace is measured by using multiple temperature measuring devices, and the temperature damage detection results are obtained according to the measurement results, including:

[0029] Using multiple temperature measuring devices to measure the temperature at different positions of the vacuum sintering furnace to obtain multiple measurement results;

[0030] Select any target measurement result from multiple measurement results;

[0031] The difference between the target measurement result and all other measurement results is calculated to obtain multiple differences. When there are two differences greater than a preset difference threshold, the position of the vacuum sintering furnace corresponding to the target measurement result is the damage position.

[0032] In a second aspect, the present application proposes a temperature measuring device based on an optimized vacuum sintering furnace, comprising: a quartz tube, a tungsten connecting rod, a tungsten push rod, an inlet stage, a thermocouple stage, and an outlet stage;

[0033] The length of the quartz tube is the optimal thickness of the carbon felt insulation layer, and a thermocouple is installed on the thermocouple stage, and the thermocouple is used to measure the temperature inside the carbon felt insulation layer;

[0034] The entrance stage is fixed to the entrance end of the quartz tube, the exit stage is fixed to the exit end of the quartz tube, the thermocouple stage is inside the quartz tube and moves between the entrance stage and the exit stage, there are two tungsten connecting rods, the tungsten push rod is between the two tungsten connecting rods, the tungsten connecting rod and the tungsten push rod pass through the interior of the quartz tube and penetrate the entrance stage, the thermocouple stage and the exit stage.

[0035] The entrance stage and the exit stage are both provided with pin holes, and the pin holes are connected by pins to respectively fix the entrance stage and the exit stage to the quartz tube.

[0036] A ceramic tube is arranged inside the tungsten connecting rod, and an electric wire is arranged inside the ceramic tube, and the electric wire is connected to the thermocouple.

[0037] A thermocouple bracket and a thermal resistance humidity sensor are installed on the thermocouple stage;

[0038] The thermocouple bracket is used to fix and install the thermocouple and serves as a limiting device for the thermocouple;

[0039] The thermal resistance humidity sensor is used to determine whether the temperature measurement value of the thermocouple at the moment is affected by humidity and generates an error.

[0040] The tungsten push rod is fixedly mounted on the thermocouple stage and connected to an external cylinder to realize the movement of the thermocouple inside the quartz tube.

[0041] Beneficial effects:

[0042] The present application proposes a temperature damage detection method and temperature measuring device based on an optimized vacuum sintering furnace. For the vacuum sintering furnace after structural optimization, a parameter iteration method is used to predict the temperature of the vacuum sintering furnace after structural optimization, and a one-dimensional performance simulation model of the carbon felt insulation layer is derived, thereby obtaining the optimal thickness of the carbon felt insulation layer. This solves the problem that the temperature in the effective heating zone after structural optimization cannot be directly measured due to excessively high temperature, and avoids the problem that a large number of experiments are required for direct measurement using experimental data. The method of the present application reduces experimental costs, extends the life of the vacuum sintering furnace, and improves the yield rate. In addition, the optimal thickness of the carbon felt insulation layer is used as the length of the temperature measuring device, and a temperature measuring device is designed. The temperature is measured using the temperature measuring device to obtain the temperature damage detection result. The temperature measuring device improves the accuracy of temperature measurement and solves the problem that thermocouples cannot be directly placed in the furnace and cannot withstand high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solution in the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 A flow chart of a temperature damage detection method based on an optimized vacuum sintering furnace according to an embodiment of the present application;

[0045] Figure 2 Schematic diagram of the temperature rise process curve of the embodiment of the present application;

[0046] Figure 3 Flow chart of parameter iteration method in the embodiment of the present application;

[0047] Figure 4 Schematic diagram of parameter iteration method in an embodiment of the present application;

[0048] Figure 5 A flow chart of obtaining the optimal thickness of the carbon felt insulation layer according to an embodiment of the present application;

[0049] Figure 6 Schematic diagram of obtaining the optimal thickness of the carbon felt insulation layer in an embodiment of the present application;

[0050] Figure 7 Schematic diagram of the selection of the temperature measurement position of the thermal insulation layer in the embodiment of the present application;

[0051] Figure 8 Schematic diagram of an external cylinder driven temperature measuring device according to an embodiment of the present application;

[0052] Fig. 9 Schematic diagram of a temperature measuring device according to an embodiment of the present application inserted into a carbon felt insulation layer;

[0053] Fig.10 Schematic diagram of the external structure of the temperature measuring device according to the embodiment of the present application;

[0054] Fig.11 Schematic diagram of the internal structure of the temperature measuring device according to an embodiment of the present application;

[0055] Fig.12 Schematic diagram of the bottom of the thermocouple stage of the embodiment of the present application;

[0056] Fig.13 A schematic side view of a thermocouple stage according to an embodiment of the present application;

[0057] Fig.14 A top view of the thermocouple stage of an embodiment of the present application;

[0058] Fig.15 Schematic diagram of the thermocouple structure of the embodiment of the present application;

[0059] Fig.16 Schematic diagram of the one-dimensional performance simulation model implemented in this application;

[0060] Among them, 1-quartz tube, 2-tungsten connecting rod, 3-tungsten push rod, 4-inlet stage, 5-thermocouple stage, 6-exit stage, 7-wire, 8-thermocouple, 9-thermal resistance humidity sensor, 10-thermocouple bracket, 11-thermocouple stage through hole, 12-internal wiring hole, 13-armored protection tube, 14-temperature measuring point, 15-R type iron-nickel alloy, 16-temperature treatment system, 17-cylinder. DETAILED DESCRIPTION

[0061] The specific implementation of the present application is further described in detail below in conjunction with the drawings and examples.

[0062] The present application proposes a temperature damage detection method and a temperature measuring device based on an optimized vacuum sintering furnace. In order to further improve the temperature uniformity in the vacuum sintering furnace, the vacuum sintering furnace needs to be structurally optimized. Since the temperature is too high, it is impossible to directly measure the temperature in the effective heating zone after structural optimization. Direct measurement using experimental data requires a large number of experiments, which greatly increases the cost. If there are no specific temperature conditions in the furnace, the life of the structure in the furnace will be affected by the high temperature, and the yield rate will be greatly reduced. In addition, different temperatures are required to adapt to the production of different workpieces. If the original furnace structure is used, since the parameters of its insulation layer are generally fixed, the insulation efficiency of the original scheme may not meet the requirements. As a result, when the final material is output, the temperature loss reaction is incomplete, and the performance of the generated material is relatively different. The present application provides a more accurate insulation layer thickness range based on the one-dimensional performance simulation model of the carbon felt insulation layer.

[0063] Finally, in the prior art, most of the temperature measurements are made using infrared temperature measurement methods. However, since infrared temperature measurement methods do not come into contact with solids, the accuracy of temperature measurement is very poor. When a vacuum sintering furnace is sintering, the temperature can reach over 1500°C. Thermocouples cannot be directly placed in the furnace and cannot withstand high temperatures, making it impossible to detect abnormal conditions in the furnace. In addition, since the workpieces carry some air when they are filled, water vapor will evaporate in the furnace when the air is heated, making it impossible to monitor and predict faults in the furnace and during sintering in real time. Therefore, the present application designs a device that can directly measure the temperature of the insulation layer, predict the temperature in the furnace, and predict damage factors in the furnace.

[0064] Embodiment 1:

[0065] This application proposes a temperature damage detection method based on an optimized vacuum sintering furnace, such as Figure 1 As shown, including:

[0066] Step S1: establishing a heat radiation and heat conduction model of the vacuum sintering furnace during the heating process according to the parameters of the vacuum sintering furnace body, and obtaining a temperature rise curve and a workpiece temperature according to the heat radiation and heat conduction model;

[0067] In this embodiment, the heat radiation and heat conduction models are calculated as follows:

[0068] The pressure in the vacuum sintering furnace is 101325Pa before the coke is discharged, and the vacuum degree is 50Pa after the coke is discharged. Ignoring the convection heat transfer, the energy equation is:

[0069]

[0070] Where t is time, unit: s; ρ is density, unit: kg / m 3 ; h is the specific enthalpy, the unit is kj / kg, h = ∫C p dT, where C p is the specific heat capacity at constant pressure J / (kg·K); is the Hamiltonian operator; u is the velocity vector, in m / s; λ is the thermal conductivity, in W / (m·K); T is the temperature, in K; S h is the internal heat source, unit is W / m 3 , the thermal physical properties of the materials are shown in Table 1.

[0071] Using the discrete ordinate DO radiation model, the radiation heat transfer model is:

[0072]

[0073] Where I is the radiation intensity, in W / m 2 ; r is the normal vector of the radiation azimuth; s is the length vector of the radiation along the path; s′ is the scattering direction; α is the material absorption coefficient; σs is the heat dissipation coefficient; n is the refractive coefficient; σ is the blackbody radiation constant; Ω′ is the radiation solid angle.

[0074] Table 1 Thermophysical properties of materials

[0075]

[0076] UDF was used to simulate the temperature rise curve and power control for computational heat transfer. The energy equation and discrete ordinate DO radiation model were turned on. Temperature monitoring points were set on the workpiece to obtain the temperature rise curve of the vacuum sintering furnace during the entire heating process.

[0077] The accuracy of the simulation process is verified by comparing the temperature of the temperature sensor and the temperature rise curve measured during the simulation and actual heating process.

[0078] The process of obtaining the workpiece temperature rise curve and the average temperature difference of all workpieces to optimize the original furnace type is as follows: Under the production process requirement that the temperature difference between the surface and the core of the same workpiece is less than 5°C, a group that best matches the actual production curve is selected as the reference process curve, such as Figure 2 shown.

[0079] Step S2: Use different insulation structures to optimize the vacuum sintering furnace structure, use parameter iteration method to predict the temperature of the vacuum sintering furnace after structure optimization, and derive a one-dimensional performance simulation model of the carbon felt insulation layer, such as Figure 3 , Figure 4 As shown, including:

[0080] Step S2.1: Use Fluent software to calculate the first total heat flux Q1 of the carbon felt insulation layer in the effective heating area of ​​the vacuum sintering furnace after structural optimization and the first furnace workpiece temperature T SIC1 ;

[0081] Step S2.2: Establish a finite element model of the vacuum sintering furnace after structural optimization, and transform the first heat flux total Q1 and the first furnace workpiece temperature T SIC1 As boundary conditions, the transient temperature of each layer (10 mm per layer) of graphite plate and carbon felt insulation layer is calculated;

[0082] Step S2.3: averaging the transient temperatures of each layer of the graphite plate and the carbon felt insulation layer to obtain the temperature T = {T1, T2, ..., Tx} of each layer of the carbon felt insulation layer;

[0083] Step S2.4: Calculate the heat flux Q of the two layers based on the temperature T6 of the first layer of the carbon felt insulation layer and the temperature T7 of the second layer. cross ;

[0084] Step S2.5: Take the heat flux Q of the two layers crossAs the initial condition, calculate the second total heat flux Q2 of the carbon felt insulation layer in the effective heating area and the temperature of the workpiece in the second furnace T SIC2 ;

[0085] Step S2.6: When the difference between the first heat flux total amount and the second heat flux total amount is less than the preset heat flux total amount threshold value (i.e., Q cross and Q come When the temperature difference between the workpiece in the first furnace and the workpiece in the second furnace is less than the preset temperature threshold, the iteration is stopped, the corresponding carbon felt insulation layer in the effective heating area is output, and the process goes to step S2.7; otherwise, the second total heat flux is used as the first total heat flux, the workpiece temperature in the second furnace is used as the workpiece temperature in the first furnace, and the process goes to step S2.2 to continue the iteration;

[0086] Step S2.7: Analyze the carbon felt insulation layer in the effective heating area corresponding to when the iteration stops, and derive a one-dimensional performance simulation model of the carbon felt insulation layer.

[0087] A one-dimensional performance simulation calculation model of the vacuum sintering furnace after the structure is changed is established and calibrated. A three-dimensional FLUENT simulation calculation model in the vacuum sintering furnace corresponding to the model established in step S1, including a turbulence model, a viscosity model, and a radiation model, is established and calibrated. The water-cooled wall temperature, room temperature, and heating body power set in the established one-dimensional model are used as the initial temperature boundary conditions for the three-dimensional simulation calculation.

[0088] Obtain the initial data of the workpiece, the data of the insulation time point in the sintering furnace and the data when the chemical reaction occurs, the three-dimensional model of the equipment, the process data of the sintering process and the ideal state data of the product output furnace, organize the temperature curve of the workpiece when it is insulated inside the sintering furnace, collect the data of the workpiece at multiple insulation nodes, and the parameter data when the equipment is in normal operation includes the input operation instructions of the equipment and the data that changes at each node inside the equipment when it is running; establish a finite element model of the vacuum sintering furnace after structural optimization, and simulate the treatment of the insulation layer of different workpiece structures, and change the physical property parameters of the grid corresponding to the insulation area into the parameters of the new insulation layer;

[0089] A forward simulation operation model and a reverse simulation operation model are established. The three-dimensional model of the equipment is combined with the operation rule data of the equipment to form a reverse simulation operation model. The operation rule data is the operation data of normal materials in the furnace to obtain normal results. The feature extraction process is reversed, and the output result is substituted into the one-dimensional performance simulation calculation model of carbon felt obtained in step S2.7 to obtain the reverse operation rule. The feature extraction process is carried out forward, from the input condition to the output result direction to obtain the forward operation rule; the dynamic instruction data is combined to control the simulation operation model to simulate the sintering of the workpiece in the sintering furnace, and obtain simulation data, compare the simulation data with the optimal data range, and adjust the heat insulation screen parameters of the vacuum sintering furnace operation process based on the simulation data analysis results.

[0090] The workpiece data includes: workpiece shape, physical parameters, normal temperature, humidity, etc., and the equipment data includes: furnace vacuum, furnace temperature, and humidity. This embodiment adopts a reverse reaction, that is, first obtains the ideal reaction temperature, final temperature, and humidity of the product, uses a one-dimensional mathematical model of the temperature between each layer of carbon felt insulation layer, derives the appropriate range of carbon felt layers, and uses forward simulation to determine the impact of specific equipment parameters on the output results.

[0091] Step S3: According to the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature, the thickness range of the carbon felt insulation layer at different sintering temperatures is calculated using the reverse simulation principle, and then the optimal thickness of the carbon felt insulation layer is obtained within the thickness range of the carbon felt insulation layer at different sintering temperatures using the forward simulation, such as Figure 5 , Figure 6 ,include:

[0092] Step S3.1: for the finite element model of the vacuum sintering furnace after structural optimization, the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature are input, and the value range of the thickness of the carbon felt insulation layer at different sintering temperatures is calculated using the inverse simulation principle;

[0093] Step S3.2: forward simulation is performed on the finite element model of the vacuum sintering furnace after structural optimization according to the desired thickness of the carbon felt insulation layer, and the thickness that makes the temperature in the furnace most uniform is selected as the optimal thickness of the carbon felt insulation layer within the range of carbon felt insulation layer thickness.

[0094] Step S4: using the optimal thickness of the carbon felt insulation layer as the length of the temperature measuring device, constructing a temperature measuring device for the vacuum sintering furnace, using multiple temperature measuring devices to measure the temperature of the vacuum sintering furnace, and obtaining temperature damage detection results based on the measurement results.

[0095] The one-dimensional performance simulation model of the carbon felt insulation layer is derived, and the calculation formula is as follows:

[0096]

[0097]

[0098]

[0099] Where, λ is the thermal conductivity of carbon felt, in W / (m·K); T r , T1, T2, T3 are the temperatures of the heating body, the inner and outer walls of the carbon felt, and the inner wall of the furnace shell, respectively, in K; ε r , ε1, ε2, ε3 are the blackness of the heating body, the inner and outer walls of the carbon felt, and the inner wall of the furnace shell; A1, A2, A3, A4 are the areas of the heating body, the inner and outer walls of the carbon felt, and the inner wall of the furnace shell, respectively, in units of m 2 ; L, D1, D2 are the height of carbon felt, the inner diameter of carbon felt and the outer diameter of carbon felt, respectively, in m; are the radiation from the heating body to the inner wall of the carbon felt, the heat conduction inside the carbon felt, and the radiation from the outer wall of the carbon felt to the furnace shell; σ0 is the radiation coefficient of an absolute black body, in W / (m 2 ·K 4 ),like Fig.16 As shown in the figure, r, 1, 2, and 3 represent the subscripts of the letters in the above calculation formula, wherein r represents the heating body, 1 represents the inner wall of the carbon felt, 2 represents the outer wall of the carbon felt, and 3 represents the inner wall of the furnace shell.

[0100] According to the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature, the thickness range of the carbon felt insulation layer at different sintering temperatures is calculated by using the reverse simulation principle, and then the optimal thickness of the carbon felt insulation layer is obtained in the thickness range of the carbon felt insulation layer at different sintering temperatures by using the forward simulation.

[0101] The temperature of the vacuum sintering furnace is measured by using multiple temperature measuring devices, and the temperature damage detection results are obtained according to the measurement results, including:

[0102] Using multiple temperature measuring devices to measure the temperature at different positions of the vacuum sintering furnace to obtain multiple measurement results;

[0103] Select any target measurement result from multiple measurement results;

[0104] The difference between the target measurement result and all other measurement results is calculated to obtain multiple differences. When there are two differences greater than a preset difference threshold, the position of the vacuum sintering furnace corresponding to the target measurement result is the damage position.

[0105] Embodiment 2:

[0106] This embodiment proposes a temperature measurement device based on an optimized vacuum sintering furnace, comprising: a quartz tube 1, a tungsten connecting rod 2, a tungsten push rod 3, an inlet stage 4, a thermocouple stage 5 and an outlet stage 6;

[0107] The length of the quartz tube 1 is the optimal thickness of the carbon felt insulation layer, and a thermocouple 8 is installed on the thermocouple stage 5, and the thermocouple 8 is used to measure the temperature inside the carbon felt insulation layer;

[0108] The inlet stage 4 is fixed to the inlet end of the quartz tube 1, the outlet stage 6 is fixed to the outlet end of the quartz tube 1, the thermocouple stage 5 is inside the quartz tube 1 and moves between the inlet stage 4 and the outlet stage 6, there are two tungsten connecting rods 2, the tungsten push rod 3 is between the two tungsten connecting rods 2, the tungsten connecting rods 2 and the tungsten push rod 3 pass through the inside of the quartz tube 1 and penetrate the inlet stage 4, the thermocouple stage 5 and the outlet stage 6 at the same time.

[0109] The inlet stage 4 and the outlet stage 6 are both provided with pin holes, and the pin holes are connected by pins to fix the inlet stage 4 and the outlet stage 6 to the quartz tube 1 respectively.

[0110] A ceramic tube is arranged inside the tungsten connecting rod 2 . An electric wire 7 is arranged inside the ceramic tube. The electric wire 7 is connected to a thermocouple 8 .

[0111] A thermocouple bracket 10 and a thermal resistance humidity sensor 9 are installed on the thermocouple stage 5;

[0112] The thermocouple bracket 10 is used to fix the thermocouple 8 and serves as a limiting device for the thermocouple 8;

[0113] The thermal resistance humidity sensor 9 is used to determine whether the temperature measurement value of the thermocouple 8 at this moment is affected by humidity and generates an error.

[0114] The tungsten push rod 3 is fixedly mounted on the thermocouple stage 5 and connected to the external cylinder 17 to realize the movement of the thermocouple 8 inside the quartz tube 1. The thermocouple stage 5 has two thermocouple stage through holes 11 and an internal wiring hole 12, which are used for the tungsten connecting rod 2 to pass through the thermocouple stage through holes 11 and the wire 7 to pass through the internal wiring hole 12.

[0115] In this embodiment, 11 longitudinal temperature measurement points are first selected in the carbon felt insulation layer area. Figure 7 As shown, an external cylinder 17 is used to push the tungsten push rod 3 to drive the quartz tube 1, as shown in FIG. Figure 8 , Fig. 9 As shown, a temperature measuring device based on the optimized vacuum sintering furnace is inserted into the longitudinal temperature measuring hole, such as Fig.10 , Fig.11As shown, it includes: a quartz tube 1, a tungsten connecting rod 2, a tungsten push rod 3, an armored thermocouple 8, a high-temperature resistant ceramic tube, and a thermal resistance humidity sensor 9. The inlet end of the quartz tube 1 adopts a conventional cylindrical shape, and the outlet end of the right end adopts a pointed shape in order to better insert into the carbon felt layer. Three stage bases are provided at the inlet, middle and outlet positions of the quartz tube 1. The stage bases are all provided with pin holes, and the pin holes are connected by pins to fix the stage base with the quartz tube 1 to prevent the stage from shifting during insertion. An armored thermocouple 8 is installed on the stage, and its direction is toward the heating direction in the furnace. In order to achieve safe measurement and protection of the thermocouple wires and the humidity sensor wires in a high temperature environment, the thermocouple wires and the humidity sensor wires are in the ceramic tube inside the tungsten connecting rod 2, and each ceramic tube is provided with 2 wires. This embodiment proposes a temperature measuring device based on an optimized vacuum sintering furnace, and its technical solution is detailed as follows:

[0116] First, process the thermocouple wires and humidity sensor wires, and use wire strippers or electrician's knife to accurately strip the insulation layer at the end of the wire. The stripping length needs to be determined according to the size and shape of the high-temperature resistant ceramic tube socket to be inserted later, to ensure that the conductor can be fully and smoothly inserted into the socket, and form a smooth cone transition part, so that the wire can be smoothly inserted into the ceramic tube for protection.

[0117] Next, the core structure of the device includes a quartz tube 1, a tungsten connecting rod 2, a tungsten push rod 3 and a thermocouple stage 5 (graphite stage), as shown in FIG. Fig.12 , Fig.13 , Fig.14 As shown. The side of the graphite stage is designed with two transverse through holes, each of which is equipped with a tungsten connecting rod 2, and the stage and the two tungsten connecting rods 2 are movably connected. One end of the two tungsten connecting rods 2 is fixed in the transverse through hole of the entrance stage 4, and the other end is fixed in the transverse through hole of the exit stage 6, ensuring the stability of the structure and the continuity of wire transmission. It is important that the left head end of the tungsten connecting rod 2 is equipped with external circuit terminals, which are led out through the high-temperature resistant ceramic tube buried inside the tungsten rod, which not only protects the safety of the line, but also ensures the accuracy of temperature measurement.

[0118] In addition, the entrance stage 4 and the exit stage 6 are respectively fixed at the entrance and exit of the quartz tube 1. They and the side of the movable thermocouple stage 5 are designed with transverse through holes for installing the tungsten connecting rod 2. The movable thermocouple stage 5 is the main part of the temperature measuring device, on which there is a thermocouple 8 for measuring the temperature inside the insulation layer, a thermal resistance humidity sensor 9, which is used to determine whether the temperature at this moment is affected by humidity and produces errors, and a tungsten push rod 3 connected to an external cylinder 17 for realizing the movement of the thermocouple inside the quartz tube to determine the damage inside the insulation layer. Among them, the thermocouple bracket 10 is used as a limit device to fix the thermocouple 8. The thermocouple 8 is covered with an armored protective tube 13, and the temperature measuring point 14 is inside the armored protective tube 13. The material of the temperature measuring point 14 is R-type iron-nickel alloy 15. The temperature data measured by the electric thermocouple 8 is transmitted to the temperature processing system 16 for processing. Fig.15 shown.

[0119] In summary, this embodiment, through a carefully designed structure, not only achieves safe transmission and measurement of thermocouple wires and humidity sensor wires in a high temperature environment, but also ensures the horizontal mobility and measurement accuracy of the temperature measuring device.

[0120] The various embodiments in the present application are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0121] The protection scope of the present application is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present disclosure without departing from the scope and spirit of the present disclosure. If these changes and modifications fall within the scope of the claims of the present disclosure and their equivalents, the intention of the present disclosure also includes these changes and modifications.

Claims

1. A temperature damage detection method based on an optimized vacuum sintering furnace, characterized in that: include: According to the parameters of the vacuum sintering furnace body, the heat radiation and heat conduction model of the vacuum sintering furnace during the heating process is established. According to the heat radiation and heat conduction model, the temperature rise curve and the workpiece temperature are obtained; The structure of the vacuum sintering furnace was optimized by using different insulation structures, the temperature of the vacuum sintering furnace after structural optimization was predicted by using parameter iteration method, and the one-dimensional performance simulation model of the carbon felt insulation layer was derived; According to the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature, the thickness range of the carbon felt insulation layer at different sintering temperatures is calculated using the reverse simulation principle, and then the optimal thickness of the carbon felt insulation layer is obtained within the thickness range of the carbon felt insulation layer at different sintering temperatures using the forward simulation; The optimal thickness of the carbon felt insulation layer is used as the length of the temperature measuring device, and a temperature measuring device for the vacuum sintering furnace is constructed. The temperature of the vacuum sintering furnace is measured using multiple temperature measuring devices, and the temperature damage detection result is obtained based on the measurement result.

2. The temperature damage detection method based on the optimized vacuum sintering furnace according to claim 1 is characterized in that: The method of using parameter iteration to predict the temperature of the vacuum sintering furnace after structural optimization and derive a one-dimensional performance simulation model of the carbon felt insulation layer includes: Step S2.1: using Fluent software to calculate the first total heat flux of the carbon felt insulation layer in the effective heating zone of the vacuum sintering furnace after structural optimization and the temperature of the workpiece in the first furnace; Step S2.2: establishing a finite element model of the vacuum sintering furnace after structural optimization, taking the first total heat flux and the temperature of the workpiece in the first furnace as boundary conditions, and calculating the transient temperature of each layer of the graphite plate and the carbon felt insulation layer; Step S2.3: averaging the transient temperatures of each layer of the graphite plate and the carbon felt insulation layer to obtain the temperature of each layer of the carbon felt insulation layer; Step S2.4: taking the temperature of the first layer of the carbon felt insulation layer and the temperature of the second layer as reference, calculating the heat flux of the two layers; Step S2.5: taking the heat flux of the two layers as the initial condition, calculating the second total heat flux of the carbon felt insulation layer in the effective heating area and the temperature of the workpiece in the second furnace; Step S2.6: When the difference between the first total heat flux and the second total heat flux is less than a preset total heat flux threshold, or when the difference between the temperature of the workpiece in the first furnace and the temperature of the workpiece in the second furnace is less than a preset temperature threshold, stop the iteration, output the corresponding carbon felt insulation layer in the effective heating area, and go to step S2.7; otherwise, take the second total heat flux as the first total heat flux, take the temperature of the workpiece in the second furnace as the temperature of the workpiece in the first furnace, and go to step S2.2 to continue the iteration; Step S2.7: Analyze the carbon felt insulation layer in the effective heating area corresponding to when the iteration stops, and derive a one-dimensional performance simulation model of the carbon felt insulation layer.

3. The temperature damage detection method based on the optimized vacuum sintering furnace according to claim 2 is characterized in that: The one-dimensional performance simulation model of the carbon felt insulation layer is derived, and the calculation formula is as follows: Where λ is the thermal conductivity of carbon felt, T r is the temperature of the heating body, T1 is the temperature of the inner wall of the carbon felt, T2 is the temperature of the outer wall of the carbon felt, T3 is the temperature of the inner wall of the furnace shell, ε r is the blackness of the heating body, ε1 is the blackness of the inner wall of the carbon felt, ε2 is the blackness of the outer wall of the carbon felt, ε3 is the blackness of the inner wall of the furnace shell, A r is the area of ​​the heating body, A1 is the area of ​​the inner wall of the carbon felt, A2 is the area of ​​the outer wall of the carbon felt, A3 is the area of ​​the inner wall of the furnace shell, L is the height of the carbon felt, D1 is the diameter of the inner wall of the carbon felt, D2 is the diameter of the outer wall, To radiate the heating body to the inner wall of the carbon felt, For heat conduction in carbon felt, is the radiation of the carbon felt outer wall and the furnace shell, and σ0 is the radiation coefficient of the absolute black body.

4. The temperature damage detection method based on the optimized vacuum sintering furnace according to claim 1 is characterized in that: The method comprises: calculating the value range of the thickness of the carbon felt insulation layer at different sintering temperatures according to the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature by using the reverse simulation principle, and then using the forward simulation to obtain the optimal thickness of the carbon felt insulation layer within the value range of the thickness of the carbon felt insulation layer at different sintering temperatures, including: According to the finite element model of the vacuum sintering furnace after structural optimization, the one-dimensional performance simulation model of the carbon felt insulation layer, the temperature rise curve and the workpiece temperature are input, and the thickness range of the carbon felt insulation layer at different sintering temperatures is calculated using the inverse simulation principle; According to the expected thickness of the carbon felt insulation layer, a forward simulation is performed on the finite element model of the vacuum sintering furnace after structural optimization, and the thickness that makes the temperature in the furnace most uniform is selected as the optimal thickness of the carbon felt insulation layer within the range of values ​​of the carbon felt insulation layer.

5. The temperature damage detection method based on the optimized vacuum sintering furnace according to claim 1 is characterized in that: The temperature of the vacuum sintering furnace is measured by using multiple temperature measuring devices, and the temperature damage detection results are obtained according to the measurement results, including: Using multiple temperature measuring devices to measure the temperature at different positions of the vacuum sintering furnace to obtain multiple measurement results; Select any target measurement result from multiple measurement results; The difference between the target measurement result and all other measurement results is calculated to obtain multiple differences. When there are two differences greater than a preset difference threshold, the position of the vacuum sintering furnace corresponding to the target measurement result is the damage position.

6. A temperature measuring device based on an optimized vacuum sintering furnace, characterized in that: include: A quartz tube (1), a tungsten connecting rod (2), a tungsten push rod (3), an inlet stage (4), a thermocouple stage (5), and an outlet stage (6); The length of the quartz tube (1) is the optimum thickness of the carbon felt insulation layer, and a thermocouple (8) is installed on the thermocouple stage (5), and the thermocouple (8) is used to measure the temperature inside the carbon felt insulation layer; The inlet stage (4) is fixed to the inlet end of the quartz tube (1), the outlet stage (6) is fixed to the outlet end of the quartz tube (1), the thermocouple stage (5) is inside the quartz tube (1) and moves between the inlet stage (4) and the outlet stage (6), there are two tungsten connecting rods (2), the tungsten push rod (3) is between the two tungsten connecting rods (2), the tungsten connecting rod (2) and the tungsten push rod (3) pass through the inside of the quartz tube (1), and pass through the inlet stage (4), the thermocouple stage (5) and the outlet stage (6).

7. The temperature measuring device based on the optimized vacuum sintering furnace according to claim 6 is characterized in that: The inlet loading platform (4) and the outlet loading platform (6) are both provided with pin holes, and the pin holes are connected by pins, so that the inlet loading platform (4) and the outlet loading platform (6) are respectively fixedly connected to the quartz tube (1).

8. The temperature measuring device based on the optimized vacuum sintering furnace according to claim 6 is characterized in that: A ceramic tube is arranged inside the tungsten connecting rod (2), and an electric wire (7) is arranged inside the ceramic tube. The electric wire (7) is connected to a thermocouple (8).

9. The temperature measuring device based on the optimized vacuum sintering furnace according to claim 6, characterized in that: A thermocouple bracket (10) and a thermal resistance humidity sensor (9) are installed on the thermocouple stage (5); The thermocouple bracket (10) is used to fix the thermocouple (8) and serves as a limiting device for the thermocouple (8); The thermal resistance humidity sensor (9) is used to determine whether the temperature measurement value of the thermocouple (8) at this moment is affected by humidity and generates an error.

10. The temperature measuring device based on the optimized vacuum sintering furnace according to claim 6, characterized in that: The tungsten push rod (3) is fixedly mounted on the thermocouple stage (5) and connected to an external cylinder (17) to enable the thermocouple (8) to move inside the quartz tube (1).

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