Vacuum furnace temperature prediction method based on multi-type heating body fixing device

Abstract

The invention provides a vacuum furnace temperature prediction method based on a multi-type heating body fixing device, and relates to the technical field of vacuum furnaces, and the multi-type heating body fixing device comprises a plurality of combined heating bodies, a plurality of graphite connecting blocks, a plurality of hexagon bolts and a plurality of electrode plates. The two ends of each combined heating body are provided with tooth-shaped ports, the tooth-shaped ports are embedded into the upper graphite block and the lower graphite block respectively, the heating bodies are fixedly connected through mutual meshing of the tooth-shaped ports, and therefore higher stability is provided. The fixing device effectively solves the problem of loosening possibly caused by threaded connection and fixation in a high-temperature environment, and ensures the connection reliability of the heating body. According to the vacuum furnace temperature prediction method based on the multi-type heating body fixing device, an optimal temperature prediction model is obtained by using a random forest algorithm, and a faster and more accurate prediction result is provided, so that the temperature control in the furnace is optimized, and the production efficiency and the product quality are improved.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum furnaces, in particular to a vacuum furnace temperature prediction method based on a multi-type heating body fixing device. Background Art

[0002] Vacuum furnace is an indispensable equipment in industrial production. The heating body is its core component, and its shape design has a decisive influence on the temperature distribution characteristics in the furnace. At present, the heating body of vacuum furnace mainly adopts a single regular cross-sectional shape, such as the tubular and rod-shaped heating bodies commonly used in vertical furnaces and horizontal furnaces, and the emerging graphite strip and cloth-shaped heating bodies. These heating bodies have simple structures, are easy to disassemble and assemble, and have large radiation areas. However, in practical applications, these heating bodies with a single cross-sectional shape have two main problems: first, the central part of the heating body is heated more, and the temperature of the edge part is low, resulting in uneven temperature distribution in the heating body, affecting the heating effect and performance of the vacuum furnace; second, the heating body with a single cross-sectional shape has poor adaptability and flexibility, and may only be suitable for specific types of heating applications, and it is difficult to meet the complex needs of modern production. In addition, threaded connections are commonly used in fixed connections of heating bodies, but in terms of electrical and mechanical stability, especially in high temperature environments, there are great limitations, such as poor contact, resistance changes, differences in thermal expansion coefficients, etc., which may lead to loose connections and reduced stability.

[0003] In terms of temperature distribution prediction of vacuum furnaces, traditional heat distribution prediction methods mainly rely on empirical formulas or finite element simulations, which are often time-consuming, have limited accuracy and insufficient real-time response capabilities.

[0004] The technical solution described in the Chinese patent "CN214901340U A new type of heating body" is to use the pipe heating structure inside the heating body, with extended input and output pipes, reasonable layout of control components and some innovative structural combination applications, so that the entire product can be small in size, high in power and high in safety. However, the patent does not innovate in the shape of the heating body.

[0005] A utility model patent authorized on January 4, 2012, a connection structure for a graphite rod heater, the technical solution is that the upper and lower ends of the graphite heating rod are respectively arranged in the conical holes of the upper connecting ring and the lower connecting ring and fixedly connected by a graphite conical sleeve, and the electrode lead-out rod is fixed in the through hole of the lower connecting ring at the lower end; the connecting ring is connected to a vertically arranged electrode lead-out rod. The patent connection method only introduces the applicability of a rod-shaped heater, which has limitations and is not suitable for heaters of other shapes and complex structures.

[0006] In the prior art, there is no vacuum furnace temperature prediction scheme for different heating body shapes combined with random forest algorithm. For example, the Chinese patent authorized on July 12, 2024, a method and system for predicting the rough rolling outlet temperature of steel slabs out of a heating furnace, with announcement number CN114798763B, uses random forest algorithm to screen out the most accurate temperature prediction model, effectively improving the temperature prediction accuracy, but it cannot be directly used to predict the temperature distribution in vacuum furnaces with different heating body shapes and sizes. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to propose a vacuum furnace temperature prediction method based on a multi-type heating body fixing device, comprising:

[0008] Step 1: Simulate the heating process of the multi-type heating body fixture in the vacuum furnace to obtain the temperature of each combined heating body in the multi-type heating body fixture during the heating process, as well as the area of ​​the uniform temperature region in the vacuum furnace;

[0009] Step 2: For each combined heating body cross-sectional shape in the multi-type heating body fixture, construct a formula F=F(ρ,θ) to characterize the cross-sectional shape, where ρ and θ are polar coordinate parameters;

[0010] Step 3: The temperature of each combined heating body during the heating process and the formula F=F(ρ,θ) representing the cross-sectional shape are combined into a sample, and then multiple samples are obtained to obtain a sample data set, and the sample data set is preprocessed to obtain a preprocessed sample data set;

[0011] Step 4: Processing the preprocessed sample data set according to the random forest algorithm to obtain multiple prediction models, wherein the prediction models are used to predict the uniform temperature area in the vacuum furnace;

[0012] Step 5: Calculate the predicted value of the uniform temperature area in the vacuum furnace through each prediction model, obtain the predicted value corresponding to each prediction model, obtain the predicted value greater than or equal to the preset area threshold value among all the predicted values, and then determine the prediction model corresponding to the predicted value greater than or equal to the preset area threshold value, and use it as the optimal prediction model;

[0013] Step 6: Randomly select a sample data from the preprocessed sample data set, bring it into the optimal prediction model, obtain the predicted value of the uniform temperature area in the vacuum furnace, and calculate the error with the uniform temperature area in the vacuum furnace obtained by simulation in step 1 to determine whether the error is less than or equal to the preset threshold. If the error is less than or equal to the preset threshold, the optimal prediction model is used as the final prediction model. If the error is greater than the preset threshold, return to step 4 until the error is less than or equal to the preset threshold.

[0014] Optionally, step 4 specifically includes:

[0015] The preprocessed sample data set is randomly sampled by Bootstrap sampling to obtain multiple sub-sample training sets, where the number of samples in the sub-sample training set is the same as the number of samples in the preprocessed sample data set. A decision tree is established for each sub-sample training set, and each node in the decision tree contains multiple samples. For each decision tree, a preset number of samples are selected from the multiple samples contained in each node and used as specific variables. A prediction model is constructed according to the specific variables to obtain a prediction model corresponding to each sub-training set.

[0016] Optionally, a prediction model is constructed based on specific variables to obtain a prediction model corresponding to each sub-training set, including:

[0017] Substitute specific variables into the preset formula to obtain the prediction model. The preset formula is expressed as:

[0018] Y(i)=((T j (i) 4 )·ρ·(5.67e-8)·sinθ·(0.57-ρ·cosθ)) / (pi·(ρ 2 -2·cosθ·ρ·0.57+0.57 2 ) 2 );

[0019] Where i represents the time in the heating process, T j (i) represents the temperature of the heating body at time i during the heating process, and Y(i) represents the area of ​​the uniform temperature region in the vacuum furnace at time i.

[0020] Optionally, the multi-type heating body fixing device includes a plurality of combined heating bodies, a plurality of graphite connecting blocks, a plurality of hexagonal bolts and a plurality of electrode plates;

[0021] The multi-type heating body fixing device is a cube, which is composed of a plurality of graphite connecting blocks and a plurality of different combined heating bodies connected to each other. The first end of a combined heating body is connected to a graphite connecting block through a hexagonal bolt, and the second end of the combined heating body is connected to another graphite connecting block through a hexagonal bolt. The combined heating bodies are parallel to each other, and a graphite connecting block is connected to a plurality of different combined heating bodies. The graphite connecting blocks include right-angled graphite connecting blocks and linear graphite connecting blocks, and the graphite connecting blocks are connected to the electrode plate.

[0022] The combined heating body is composed of at least two heating bodies, and the combined heating body includes a basic heating body, or a special-shaped heating body, or a basic heating body and a special-shaped heating body. The cross-sectional shape of the basic heating body is a single cross-sectional shape, and the single cross-sectional shape includes at least a circular ring, a circle, a square, and a diamond. The cross-sectional shape of the special-shaped heating body is a shape obtained by combining single cross-sectional shapes.

[0023] Optionally, both ends of the combined heating body are provided with toothed ports, the center of the toothed ports has an internal thread, the graphite connecting block is designed with a toothed hole corresponding to the toothed port, the toothed hole of the graphite connecting block is coupled with the toothed port, and the internal thread in the center of the toothed port engages with the hexagonal bolt.

[0024] Optionally, the combined heating body includes two heating bodies, and the combined heating body is composed of a first heating body and a second heating body, the first heating body includes a tubular heating body or a rod-shaped heating body, the cross-sectional shape of the tubular heating body is a circular ring, and the cross-sectional shape of the rod-shaped heating body is a circle; the second heating body includes a basic heating body or a special-shaped heating body, one end face of the first heating body is designed with an internal thread, and the second heating body is provided with an extending stud, and the extending studs of the second heating body are all engaged with the internal thread of the first heating body.

[0025] Optionally, the combined heating body includes three heating bodies, and the combined heating body consists of a first heating body, a third heating body and a fourth heating body, the first heating body includes a tubular heating body or a rod-shaped heating body, the cross-sectional shape of the tubular heating body is a circular ring, the cross-sectional shape of the rod-shaped heating body is a circle, the third heating body includes a basic heating body or a special-shaped heating body, and the fourth heating body includes a basic heating body or a special-shaped heating body; both end faces of the first heating body are designed with internal threads, the third heating body and the fourth heating body are both provided with protruding studs, the internal thread of the first end of the first heating body is engaged with the protruding stud of the third heating body, and the internal thread of the second end of the first heating body is engaged with the protruding stud of the fourth heating body.

[0026] Optionally, the combined heating body includes two heating bodies, and the combined heating body consists of a fifth heating body and a sixth heating body, the fifth heating body includes a basic heating body or a special-shaped heating body, the sixth heating body includes a basic heating body or a special-shaped heating body, one end face of the fifth heating body is designed with an internal thread, one end face of the sixth heating body is designed with an internal thread, the first end of the external stud is engaged with the internal thread of the fifth heating body, and the second end of the external stud is engaged with the internal thread of the sixth heating body.

[0027] The beneficial effects of adopting the above technical solution are:

[0028] The present invention provides a multi-type heating body fixing device, including multiple combined heating bodies, multiple graphite connecting blocks, multiple hexagonal bolts and multiple electrode plates. Both ends of each combined heating body are designed with toothed ports of uniform specifications, which are respectively embedded in the upper graphite block and the lower graphite block. The fixed connection of the heating body is achieved through the mutual engagement of the toothed ports, thereby providing higher stability. This fixing device effectively solves the problem of loosening that may occur in threaded connection fixation under high temperature environment, and ensures the connection reliability of the heating body. The present invention provides a vacuum furnace temperature prediction method based on a multi-type heating body fixing device, which uses a random forest algorithm to obtain an optimal temperature prediction model, providing faster and more accurate prediction results, thereby optimizing the temperature control in the furnace and improving production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of a vacuum furnace temperature prediction method based on a multi-type heating body fixing device in an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of the structure of a multi-type heating body fixing device in an embodiment of the present invention, wherein Figure (a) is a three-dimensional diagram of the multi-type heating body fixing device, and Figure (b) is a cross-sectional view of the multi-type heating body fixing device;

[0031] Figure 3 Schematic diagrams of single cross-sectional shapes in embodiments of the present invention, wherein (a) is a ring shape, (b) is a circle, (c) is a square, and (d) is a rhombus;

[0032] Figure 4 Schematic diagram of the cross-sectional shape of the special-shaped heating body in the embodiment of the present invention, wherein Figure (e) is a combined cross-section 1, Figure (f) is a combined cross-section 2, Figure (g) is a combined cross-section 3, and Figure (h) is a combined cross-section 4;

[0033] Figure 5 Schematic diagram of the structure of a combined heating body composed of two heating bodies in an embodiment of the present invention, wherein Figure (a) is a schematic diagram of two heating bodies A+B constituting the combined heating body, and Figure (b) is a schematic diagram of the connection method of the two heating bodies A+B constituting the combined heating body;

[0034] Figure 6 Schematic diagram of the structure of a combined heating body composed of three heating bodies in an embodiment of the present invention, FIG. (a) is a schematic diagram of three heating bodies A+B+A constituting the combined heating body, and FIG. (b) is a schematic diagram of three heating bodies A+B+C constituting the combined heating body;

[0035] Figure 7Schematic diagram of the structure of another combined heating body composed of two heating bodies in an embodiment of the present invention, wherein Figure (a) is a schematic diagram of two heating bodies A+F constituting the combined heating body, and Figure (b) is a schematic diagram of the connection method of the two heating bodies A+F constituting the combined heating body;

[0036] Figure 8 It is a schematic diagram of the structure of the toothed ports at both ends of the combined heating body in an embodiment of the present invention;

[0037] Fig. 9 Schematic diagram of the structure of the tooth-shaped holes of the graphite connecting block in the embodiment of the present invention;

[0038] Fig.10 A detailed diagram of the engagement between the internal thread at the center of the toothed port and the hexagonal bolt in an embodiment of the present invention;

[0039] Fig.11 It is a central cross-sectional view of a vacuum furnace and a schematic diagram of the overall layout of a heating body in an embodiment of the present invention;

[0040] Fig.12 The temperature cloud diagram and isotherms of the combined cross-section 1 heating body in the embodiment of the present invention;

[0041] Fig.13 It is a schematic diagram of the area of ​​the uniform temperature zone in the furnace of the combined cross section of the vacuum furnace heating body in the embodiment of the present invention;

[0042] Fig.14 The temperature cloud diagram and isotherms of the circular cross-section heating body in the furnace in the embodiment of the present invention;

[0043] Fig.15 It is a schematic diagram of the uniform temperature area of ​​a single furnace of a vacuum furnace heating body in an embodiment of the present invention;

[0044] Fig.16 A comparison of the uniform temperature area of ​​the vacuum furnace heating body in the embodiment of the present invention with a single and combined cross-sectional shape

[0045] Fig.17 It is a schematic diagram of the geometric relationship of the cross-sectional shape of the vacuum furnace heating body under the coordinate axis in the embodiment of the present invention;

[0046] Fig.18 It is a schematic diagram of radiation heat transfer between microelement surfaces of the cross-sectional shape of the vacuum furnace heating body in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0048] With the rapid development of big data and machine learning technology, the random forest algorithm provides a new solution for improving the accuracy and efficiency of temperature distribution prediction in vacuum furnaces. The random forest algorithm can effectively handle multiple factors that affect temperature distribution and provide better prediction performance by constructing multiple decision tree models and integrating their prediction results. Specifically, the present invention proposes an innovative composite cross-section heating body design, which breaks through the limitations of traditional heating bodies by combining multiple single cross-sectional shapes, achieves a more uniform temperature distribution inside the vacuum furnace, and increases the uniform temperature area. This design not only improves the flexibility and adaptability of the heating body, enabling it to be customized and adjusted according to different sintering requirements and adapt to different materials and processes, but also allows local replacement of the heating body in a specific area, and flexibly adjusts the shape of the heating body according to the furnace size and temperature requirements. In addition, the present invention also provides a fixing device with strong adaptability and stable performance, which is suitable for a variety of heating body shapes including rectangles, diamonds and special shapes.

[0049] In view of the problems existing in the prior art, the present invention provides a vacuum furnace temperature prediction method based on a multi-type heating body fixing device, combined with Figure 1 , which may include the following steps:

[0050] Step 1: Simulate the heating process of the multi-type heating body fixture in the vacuum furnace to obtain the temperature of each combined heating body in the multi-type heating body fixture during the heating process, as well as the area of ​​the uniform temperature region in the vacuum furnace;

[0051] Combination Figure 2 In Figures (a) and (b), the multi-type heating body fixing device includes a plurality of combined heating bodies 1, a plurality of graphite connecting blocks 2, a plurality of hexagonal bolts 3 and a plurality of electrode plates 4;

[0052] The multi-type heating body fixing device is a cube, which is composed of a plurality of graphite connecting blocks 2 and a plurality of combined heating bodies 1 connected to each other. The first end of a combined heating body 1 is connected to a graphite connecting block 2 through a hexagonal bolt 3, and the second end of the combined heating body 1 is connected to another graphite connecting block 2 through a hexagonal bolt 3. The combined heating bodies 1 are parallel to each other, and a graphite connecting block 2 is connected to a plurality of combined heating bodies 1. The graphite connecting block 2 includes a right-angled graphite connecting block and a straight-line graphite connecting block. The graphite connecting block 2 is connected to an electrode plate 4; Figure 2 , Figure 2 It is a structural schematic diagram of a multi-type heating body fixing device, and the multi-type heating body fixing device includes.

[0053] It should be noted that the combined heating body in the multi-type heating body can be of the same type or of multiple different types.

[0054] The combined heating body 1 is composed of at least two heating bodies, and the combined heating body 1 includes a basic heating body, or a special-shaped heating body, or a basic heating body and a special-shaped heating body. The cross-sectional shape of the basic heating body is a single cross-sectional shape, and the single cross-sectional shape includes at least a circular ring, a circle, a square, a diamond, and so on. Figure 3 (a)-(d) are all single cross-sectional shapes. The cross-sectional shape of the special-shaped heating body is a shape obtained by combining single cross-sectional shapes. Figure 4 The cross-sectional shape of the special-shaped heating body includes a square and a circular cross-sectional shape compounded into a combined cross-sectional shape 1, that is, Figure 4 Figure (e) in the figure; the rhombus and circular sections are combined into a combined section 2, that is, Figure 4 Figure (f) in the figure; the square and circular sections are combined into a combined section 3, that is, Figure 4 Figure (g); the rhombus and circular sections are combined into a combined section 4, that is, Figure 4 Figure (h) in .

[0055] The combined heating body 1 may include two heating bodies, and the combined heating body 1 is composed of a first heating body and a second heating body, the first heating body includes a tubular heating body or a rod-shaped heating body, the cross-sectional shape of the tubular heating body is a circular ring, and the cross-sectional shape of the rod-shaped heating body is a circle; the second heating body includes a basic heating body or a special-shaped heating body, Figure 5 Taking Figure (a) in FIG. 1 as an example, the combined heating body 1 may include a rod-shaped heating body B and a square heating body A. An end face of the first heating body is designed with an internal thread, and the second heating body is provided with an extended stud. The extended stud of the second heating body is engaged with the internal thread of the first heating body. Figure 5 In Figure (b), E is an outwardly extending stud of the square heating body, and the end face of the rod-shaped heating body is designed with an internal thread.

[0056] The combined heating body 1 may further include three heating bodies, and the combined heating body 1 is composed of a first heating body, a third heating body and a fourth heating body, wherein the first heating body includes a tubular heating body or a rod-shaped heating body, the cross-sectional shape of the tubular heating body is a circular ring, the cross-sectional shape of the rod-shaped heating body is a circle, the third heating body includes a basic heating body or a special-shaped heating body, the fourth heating body includes a basic heating body or a special-shaped heating body, and the Figure 6 Taking the middle figure (a) as an example, the combined heating body 1 may include a rod-shaped heating body B and two square heating bodies A. Figure 6Taking the middle figure (b) as an example, the combined heating body 1 can also include a rod-shaped heating body B, a square heating body A and a special-shaped heating body C; the two end faces of the first heating body are designed with internal threads, the third heating body and the fourth heating body are both provided with extended studs, the internal thread of the first end of the first heating body is engaged with the extended stud of the third heating body, and the internal thread of the second end of the first heating body is engaged with the extended stud of the fourth heating body.

[0057] The combined heating body 1 may also include two heating bodies, and the combined heating body 1 is composed of a fifth heating body and a sixth heating body, wherein the fifth heating body includes a basic heating body or a special-shaped heating body, and the sixth heating body includes a basic heating body or a special-shaped heating body. Figure 7 Taking the middle figure (a) as an example, the combined heating body 1 may include a rhombus-shaped heating body F and a square heating body A, one end surface of the fifth heating body is designed with an internal thread, one end surface of the sixth heating body is designed with an internal thread, the first end of the external stud is engaged with the internal thread of the fifth heating body, and the second end of the external stud is engaged with the internal thread of the sixth heating body, such as Figure 7 In Figure (b), D is a stud.

[0058] This combined heating body can realize the replacement of a certain section of the heating body in a specific area by connecting threaded studs of different heating body shapes, and also allows the shape of the heating body to be flexibly selected and adjusted according to the size and shape of the furnace and the temperature requirements of different areas in the furnace.

[0059] Wherein, the two ends of the combined heating body 1 are provided with toothed ports 5, and the center of the toothed ports 5 has an internal thread, such as Figure 8 The graphite connection block 2 is designed with a toothed hole 6 corresponding to the toothed port, and the toothed hole 6 of the graphite connection block is coupled with the toothed port 5, such as Fig. 9 , the internal thread at the center of the toothed port engages with the hexagonal bolt, such as Fig.10 Such a connection structure helps to reduce the relaxation coefficient of the connection and reduce the looseness of the connection.

[0060] The core advantage of this fixture is the toothed meshing mechanism, which provides a mechanical lock for the connected parts, enhances the stability of the connection, and effectively reduces the displacement caused by vibration or thermal expansion, thereby avoiding the loosening and poor contact problems that may be caused by threaded connections; the toothed meshing can also increase the contact area between the connected parts and improve the heat conduction efficiency. In addition, the toothed meshing design can adapt to a variety of loads and working environments, including high temperature, high pressure and corrosive environments.

[0061] Based on the structure of the above multi-type heating body fixing device, it is placed in a vacuum furnace for simulation. Fig.11, including a plurality of combined heating bodies 1, a water cooling system 7, a steel plate 8, a carpet layer 9 and a graphite plate 10, the simulation includes the following steps:

[0062] Step 1.1: Since the furnace heating system is axially symmetrically distributed, 1 / 2 of the furnace cross section is selected to build the temperature field model. Automatic meshing is used, with a total of 32,979 meshes and 33,271 nodes. In the sintering process, only thermal radiation is considered, and heat conduction and convection are ignored. The DO radiation model is used, and the radiation heat transfer model is: Where: I is the radiation intensity, r is the radiation azimuth normal vector; s is the radiation length vector, s′ is the scattering direction; α is the material absorption coefficient; σ s is the heat dissipation coefficient; I(r,s) is the radiation intensity; n is the refractive index; σ is the blackbody radiation constant; Φ(s,s') is the energy source term; Ω' is the radiation solid angle.

[0063] The physical properties of the furnace material are set as shown in Table 1. The graphite heating tube is set as the body heat source. The rated power is 2000000 W / m3, the heating is 3 h, the step length is set to 360 steps, and each step is 30 s. The water cooling system is simplified as a wall surface and set as a constant temperature boundary. The initial temperature of the calculation domain is set to 25 °C.

[0064] Table 1 Physical properties of furnace materials

[0065]

[0066] Step 1.2: Based on the above-mentioned furnace material properties and radiation heat transfer model, simulation is carried out, the energy equation and discrete ordinate DO radiation model are turned on, a temperature monitoring point is set at the center of the cross section of the vacuum furnace, and the temperature field distribution law of the vacuum furnace under no-load state is obtained.

[0067] Step 1.3: Perform heating simulation at constant power under no-load state to obtain the uniform temperature area in the vacuum furnace. Specifically, for special-shaped heating bodies with different cross-sectional shapes, the corresponding uniform temperature area in the vacuum furnace can be obtained. Taking the heating body of combined section 1 as an example, after simulation, the temperature cloud map of the heating body of combined section 1 in the furnace at the end of heating can be obtained, as shown in Fig.12 Taking the furnace center temperature of 1356.45K as the benchmark, draw the isotherm of 1361.75K within the range of ±5K, and calculate the area of ​​the uniform temperature zone to be 4997.58cm 2 The average temperature area of ​​the other special-shaped heating bodies with different combined cross sections is calculated in the same way as above, and then the average temperature area of ​​the combined cross sections 1-4 can be obtained, such as Fig.13 .

[0068] Based on the above simulation process, the present invention simulates a heating body with a single cross section, taking a circular heating body as an example. After the simulation, a temperature cloud diagram of the circular heating body in the furnace can be obtained at the end of heating, such as Fig.14 The cloud map intuitively shows the temperature distribution in the furnace. Taking the furnace center temperature 1350.75K as the benchmark, the isotherm 1355.75K is drawn within the range of ±5K according to the relevant standard furnace temperature uniformity requirement. The origin software is further used to calculate that the area of ​​the uniform temperature zone in the furnace under this cross-sectional shape is 4863.75cm 2 , and then the simulated uniform temperature area of ​​other single cross-section heating bodies can be obtained, such as Fig.15 .

[0069] Based on this, we can also find that when the heating power remains unchanged, the cross-sectional shape of the heating body is changed, and it is found that the area of ​​the uniform temperature zone in the furnace changes significantly. Among them, the heating body with a single cross-sectional shape: (a) the heating body with a circular cross-sectional shape has the largest uniform temperature zone area of ​​4863.75cm 2 (d) The minimum uniform temperature area of ​​the rectangular cross-section heating body is 4189.02 cm 2 ; Combined cross-sectional shape heating element: (e) Combined cross-sectional shape 1 The maximum uniform temperature area in the furnace is 4997.58 cm 2 (g) The minimum uniform temperature area in the combined section 4 furnace is 4842.035 cm 2 . See Fig.16 , the heating simulation is carried out at constant power under no-load condition, and the maximum area of ​​the uniform temperature zone of the combined section is 4997.58cm 2 The minimum uniform temperature area of ​​the rectangular cross section is 4189.02 cm 2 The area of ​​the uniform temperature zone is increased by about 16%. The innovative combined cross-sectional shape of the heating body of the present invention reduces the temperature gradient in the furnace, expands the area of ​​the uniform temperature zone, and significantly improves the uniformity of the furnace temperature.

[0070] Step 2: For each combined heating body cross-sectional shape in the multi-type heating body fixture, construct a formula F=F(ρ,θ) to characterize the cross-sectional shape, where ρ and θ are polar coordinate parameters;

[0071] The inside of the vacuum furnace is a sealed vacuum chamber, and energy transfer is mainly achieved through radiation heat transfer. Therefore, the radiation heat transfer process inside the vacuum furnace is analyzed, mainly including the determination of key parameters such as radiation force, system emissivity, and angular coefficient. Among them, the focus is on the calculation of the angular coefficient between the two surfaces in the radiation heat transfer process, which is achieved by drawing a geometric relationship diagram through the relative position of the vacuum furnace heating body and the heating chamber. Fig.17, simplify the geometric cross-sectional shape of the heating body, take the moving axis ρ, the angle θ between ρ and OX as a variable, and use the motion trajectory of the end point of the moving axis ρ to represent the geometric cross-sectional shape of the heating body. Then, any geometric cross-sectional shape of the heating body can be expressed as F=F(ρ,θ).

[0072] See also Fig.18 , according to the geometric relationship expression between the microelement cross section of the heating body and a relative position of the heating chamber: L = x 2 +y 2 ;Radiative heat transfer expression: Where: dΦ 1,2 is the energy radiated from the micro-element surface dA1 to another micro-element surface dA2; T is the initial temperature of the micro-element surface dA1; β1 is the angle between the normal line of the dA1 surface and the line of sight from dA1 to dA2; L is the distance from dA1 to dA2; β2 is the angle between the normal line of the dA1 surface and the line of sight from dA1 to dA2; d is the distance from a certain position in the heating chamber to the central section of the sintering furnace, which is set to a constant.

[0073] Step 3: The temperature of each combined heating body during the heating process and the formula F=F(ρ,θ) representing the cross-sectional shape are combined into a sample, and then multiple samples are obtained to obtain a sample data set, and the sample data set is preprocessed to obtain a preprocessed sample data set;

[0074] Among them, the preprocessing of the sample data set includes data deletion and abnormal data processing to eliminate abnormal and erroneous data.

[0075] Step 4: Processing the preprocessed sample data set according to the random forest algorithm to obtain multiple prediction models, wherein the prediction models are used to predict the uniform temperature area in the vacuum furnace;

[0076] Among them, the random forest algorithm can be implemented through Matlab programming.

[0077] Wherein, step 4 specifically includes:

[0078] The preprocessed sample data set is randomly sampled by Bootstrap sampling to obtain multiple sub-sample training sets, where the number of samples in the sub-sample training set is the same as the number of samples in the preprocessed sample data set. A decision tree is established for each sub-sample training set, and each node in the decision tree contains multiple samples. For each decision tree, a preset number of samples are selected from the multiple samples contained in each node and used as specific variables. A prediction model is constructed according to the specific variables to obtain a prediction model corresponding to each sub-training set.

[0079] A prediction model is constructed based on specific variables to obtain the prediction model corresponding to each sub-training set, including:

[0080] Substitute specific variables into the preset formula to obtain the prediction model. The preset formula is expressed as:

[0081] Y(i)=((T j (i) 4 )·ρ·(5.67e-8)·sinθ·(0.57-ρ·cosθ)) / (pi·(ρ 2 -2·cosθ·ρ·0.57+0.57 2 ) 2 );

[0082] Where i represents the time in the heating process, T j (i) represents the temperature of the heating body at time i during the heating process, and Y(i) represents the area of ​​the uniform temperature region in the vacuum furnace at time i.

[0083] Step 5: Calculate the predicted value of the uniform temperature area in the vacuum furnace through each prediction model, obtain the predicted value corresponding to each prediction model, obtain the predicted value greater than or equal to the preset area threshold value among all the predicted values, and then determine the prediction model corresponding to the predicted value greater than or equal to the preset area threshold value, and use it as the optimal prediction model;

[0084] The preset area threshold is 4800cm 2 The optimal prediction model can be one or more. If no prediction model in this step has a prediction value greater than or equal to the preset area threshold, return to step 4.

[0085] Step 6: Randomly select a sample data from the preprocessed sample data set, bring it into the optimal prediction model, obtain the predicted value of the uniform temperature area in the vacuum furnace, and calculate the error with the uniform temperature area in the vacuum furnace obtained by simulation in step 1 to determine whether the error is less than or equal to the preset threshold. If the error is less than or equal to the preset threshold, the optimal prediction model is used as the final prediction model. If the error is greater than the preset threshold, return to step 4 until the error is less than or equal to the preset threshold.

[0086] The preset threshold is 10% or 15%, and the final prediction model can be one or more.

[0087] The innovative composite heating body cross-section of the present invention achieves a more uniform temperature distribution in the vacuum furnace, and the area of ​​the uniform temperature zone is increased by 16%. The special-shaped heating body parts can realize local replacement of the heating bodies in different specific areas. In addition, the present invention uses a random forest algorithm to predict the furnace temperature of different heating bodies.

[0088] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form a technical solution.

Claims

1. A vacuum furnace temperature prediction method based on a multi-type heating body fixing device, characterized in that: include: Step 1: Simulate the heating process of the multi-type heating body fixture in the vacuum furnace to obtain the temperature of each combined heating body in the multi-type heating body fixture during the heating process, as well as the area of ​​the uniform temperature region in the vacuum furnace; Step 2: For each combined heating body cross-sectional shape in the multi-type heating body fixture, construct a formula F=F(ρ,θ) to characterize the cross-sectional shape, where ρ and θ are polar coordinate parameters; Step 3: The temperature of each combined heating body during the heating process and the formula F=F(ρ,θ) representing the cross-sectional shape are combined into a sample, and then multiple samples are obtained to obtain a sample data set, and the sample data set is preprocessed to obtain a preprocessed sample data set; Step 4: Processing the preprocessed sample data set according to the random forest algorithm to obtain multiple prediction models, wherein the prediction models are used to predict the uniform temperature area in the vacuum furnace; Step 5: Calculate the predicted value of the uniform temperature area in the vacuum furnace through each prediction model, obtain the predicted value corresponding to each prediction model, obtain the predicted value greater than or equal to the preset area threshold value among all the predicted values, and then determine the prediction model corresponding to the predicted value greater than or equal to the preset area threshold value, and use it as the optimal prediction model; Step 6: Randomly select a sample data from the preprocessed sample data set, bring it into the optimal prediction model, obtain the predicted value of the uniform temperature area in the vacuum furnace, and calculate the error with the uniform temperature area in the vacuum furnace obtained by simulation in step 1 to determine whether the error is less than or equal to the preset threshold. If the error is less than or equal to the preset threshold, the optimal prediction model is used as the final prediction model. If the error is greater than the preset threshold, return to step 4 until the error is less than or equal to the preset threshold.

2. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 1 is characterized in that: Step 4 specifically includes: The preprocessed sample data set is randomly sampled by Bootstrap sampling to obtain multiple sub-sample training sets, where the number of samples in the sub-sample training set is the same as the number of samples in the preprocessed sample data set. A decision tree is established for each sub-sample training set, and each node in the decision tree contains multiple samples. For each decision tree, a preset number of samples are selected from the multiple samples contained in each node and used as specific variables. A prediction model is constructed according to the specific variables to obtain a prediction model corresponding to each sub-training set.

3. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 2 is characterized in that: A prediction model is constructed based on specific variables to obtain the prediction model corresponding to each sub-training set, including: Substitute specific variables into the preset formula to obtain the prediction model. The preset formula is expressed as: Y(i)=((T j (i) 4 )·ρ·(5.67e-8)·sinθ·(0.57-ρ·cosθ)) / (pi·(ρ 2 -2·cosθ·ρ·0.57+0.57 2 ) 2 ); Where i represents the time in the heating process, T j (i) represents the temperature of the heating body at time i during the heating process, and Y(i) represents the area of ​​the uniform temperature region in the vacuum furnace at time i.

4. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 1 is characterized in that: The multi-type heating body fixing device comprises a plurality of combined heating bodies, a plurality of graphite connecting blocks, a plurality of hexagonal bolts and a plurality of electrode plates; The multi-type heating body fixing device is a cube, which is composed of a plurality of graphite connecting blocks and a plurality of different combined heating bodies connected to each other. The first end of a combined heating body is connected to a graphite connecting block through a hexagonal bolt, and the second end of the combined heating body is connected to another graphite connecting block through a hexagonal bolt. The combined heating bodies are parallel to each other, and a graphite connecting block is connected to a plurality of different combined heating bodies. The graphite connecting blocks include right-angled graphite connecting blocks and linear graphite connecting blocks, and the graphite connecting blocks are connected to the electrode plate. The combined heating body is composed of at least two heating bodies, and the combined heating body includes a basic heating body, or a special-shaped heating body, or a basic heating body and a special-shaped heating body. The cross-sectional shape of the basic heating body is a single cross-sectional shape, and the single cross-sectional shape includes at least a circular ring, a circle, a square, and a diamond. The cross-sectional shape of the special-shaped heating body is a shape obtained by combining single cross-sectional shapes.

5. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 4 is characterized in that: The combined heating body is provided with toothed ports at both ends, with internal threads at the centers of the toothed ports, and the graphite connecting block is designed with toothed holes corresponding to the toothed ports. The toothed holes of the graphite connecting block are coupled with the toothed ports, and the internal threads at the centers of the toothed ports are engaged with the hexagonal bolts.

6. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 4 is characterized in that: The combined heating body includes two heating bodies, and the combined heating body consists of a first heating body and a second heating body, the first heating body includes a tubular heating body or a rod-shaped heating body, the cross-sectional shape of the tubular heating body is a circular ring, and the cross-sectional shape of the rod-shaped heating body is a circle; the second heating body includes a basic heating body or a special-shaped heating body, one end face of the first heating body is designed with an internal thread, and the second heating body is configured with an extended stud, and the extended studs of the second heating body are all engaged with the internal thread of the first heating body.

7. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 4 is characterized in that: The combined heating body includes three heating bodies, and the combined heating body consists of a first heating body, a third heating body and a fourth heating body, the first heating body includes a tubular heating body or a rod-shaped heating body, the cross-sectional shape of the tubular heating body is a circular ring, the cross-sectional shape of the rod-shaped heating body is a circle, the third heating body includes a basic heating body or a special-shaped heating body, and the fourth heating body includes a basic heating body or a special-shaped heating body; both end faces of the first heating body are designed with internal threads, the third heating body and the fourth heating body are both provided with extended studs, the internal thread of the first end of the first heating body is engaged with the extended stud of the third heating body, and the internal thread of the second end of the first heating body is engaged with the extended stud of the fourth heating body.

8. The vacuum furnace temperature prediction method based on a multi-type heating body fixing device according to claim 4 is characterized in that: The combined heating body includes two heating bodies, and the combined heating body consists of a fifth heating body and a sixth heating body, the fifth heating body includes a basic heating body or a special-shaped heating body, the sixth heating body includes a basic heating body or a special-shaped heating body, one end face of the fifth heating body is designed with an internal thread, one end face of the sixth heating body is designed with an internal thread, the first end of the external stud is engaged with the internal thread of the fifth heating body, and the second end of the external stud is engaged with the internal thread of the sixth heating body.

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