A temperature control system and method for the production of polyacrylonitrile-based carbon films

Abstract

The application discloses a temperature control system and method for polyacrylonitrile-based carbon film preparation and relates to the technical field of temperature control for film preparation. The temperature control method for polyacrylonitrile-based carbon film preparation obtains solidification bath state time series data, traction state time series data and traction wet film thermal imaging time series data of film preparation. Based on the solidification bath state time series data of film preparation, the solidification traction temperature control characteristic value of film preparation is analyzed. The traction state time series data and the traction wet film thermal imaging time series data of film preparation are jointly processed to obtain the traction temperature control adjustment characteristic value of film preparation. The temperature control processing of film preparation is performed based on the solidification traction temperature control characteristic value and the traction temperature control adjustment characteristic value, so that the dynamic connection from solidification to traction is completed, temperature control lag and extensive adjustment are avoided, the traction temperature is accurately matched with the actual state of the wet film, and the film forming quality of the polyacrylonitrile-based carbon film is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film preparation temperature control, in particular to a temperature control system and method for polyacrylonitrile-based carbon thin film preparation. BACKGROUND

[0002] As an important derivative of carbon fiber material, polyacrylonitrile-based carbon thin film has wide application prospects in the fields of aerospace, energy storage devices, flexible electronics, etc. Its preparation process usually includes solution spinning, wet coagulation, drawing film forming, oxidation stabilization and carbonization, etc. Among them, the spinning film forming stage is the key link to determine the microstructure and mechanical properties of the final film.

[0003] In the spinning film forming process, the polyacrylonitrile solution is sprayed out of the spinneret and enters the coagulation bath. The wet film gradually solidifies under the exchange action of solvent and non-solvent, and realizes molecular chain orientation and densification under the traction action. The temperature control in this stage has a decisive influence on the film quality. For example, the heating temperature of the traction zone determines the sufficiency of molecular chain orientation and the balance of stress release. If the temperature is too high, there is a risk of excessive slip and thermal damage of molecular chain. If the temperature is too low, it will increase the traction resistance, resulting in film rupture or insufficient orientation.

[0004] Among them, the limitations of the prior art at least include the following problems. The prior art lacks dynamic comprehensive analysis of the material state difference and thermal field evolution characteristics from coagulation to traction stage. In the film preparation process, the wet film first solidifies and densifies in the coagulation bath, and then enters the traction zone to bear stretching and heating treatment. The coagulation stage affects the initial forming quality, and the traction stage determines the molecular chain orientation and film forming stability. If there is no continuous sensing of the above state, it is difficult to effectively link the solidification characteristics of the coagulation stage and the temperature regulation requirements of the traction stage, so as to easily lead to extensive temperature regulation, difficult to match the actual changes of the wet film, and further easily cause traction overheating or abnormal molecular chain orientation, and thus difficult to ensure the forming quality of the polyacrylonitrile-based carbon thin film. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a temperature control system and method for polyacrylonitrile-based carbon thin film preparation, which solves the problem of lack of coagulation and traction state joint processing in the prior art, resulting in extensive temperature control and easy performance degradation.

[0006] To achieve the above object, the present application is implemented by the following technical solutions: A temperature control method for polyacrylonitrile-based carbon film preparation, comprising the following steps: obtaining coagulation bath state time series data, traction state time series data and traction wet film thermal imaging time series data of film preparation; based on the coagulation bath state time series data of film preparation, analyzing coagulation traction temperature regulation characteristic values of film preparation; jointly processing the traction state time series data and the traction wet film thermal imaging time series data of film preparation to obtain traction temperature control adjustment characteristic values of film preparation; based on the coagulation traction temperature regulation characteristic values and the traction temperature control adjustment characteristic values, performing temperature control processing on film preparation.

[0007] Further, the coagulation bath state time series data includes coagulation bath temperature gradient value, solvent concentration value, coagulation bath wet film shrinkage rate value, bath flow shear rate value, coagulation bath interface light transmission value and solvent partial pressure value at each time point, and the specific steps of analyzing the coagulation traction temperature regulation characteristic values of film preparation are as follows: based on the coagulation bath state time series data of film preparation, analyzing the coagulation time series characteristic set of film preparation, including coagulation bath solidification driving characteristic value and coagulation morphology stability characteristic value at each time point; based on the coagulation time series characteristic set of film preparation, analyzing the coagulation traction temperature regulation characteristic values of film preparation.

[0008] Further, the specific steps of analyzing the coagulation time series characteristic set of film preparation are as follows: based on the coagulation bath temperature gradient value, solvent concentration value and solvent partial pressure value at each time point of film preparation, analyzing the coagulation bath solidification driving characteristic value at the corresponding time point; based on the coagulation bath wet film shrinkage rate value, bath flow shear rate value and coagulation bath interface light transmission value at each time point of film preparation, analyzing the coagulation morphology stability characteristic value at the corresponding time point.

[0009] Further, the specific steps of analyzing the traction temperature control adjustment characteristic values of film preparation are as follows: based on the traction state time series data of film preparation, analyzing traction heat receiving correction characteristic values of film preparation; based on the pre-trained wet film thermal evolution analysis model and combined with the traction wet film thermal imaging time series data of film preparation, analyzing wet film overheating risk characteristic values of film preparation; based on the traction heat receiving correction characteristic values and the wet film overheating risk characteristic values, analyzing the traction temperature control adjustment characteristic values of film preparation.

[0010] Further, the specific steps of analyzing the traction heat receiving correction characteristic values of film preparation are as follows: standardizing the traction state time series data of film preparation; comprehensively analyzing the standardized traction state time series data of film preparation to obtain traction heat receiving bearing characteristic values of film preparation; obtaining traction environment temperature control correction characteristic values of film preparation and combining the traction heat receiving bearing characteristic values to analyze the traction heat receiving correction characteristic values of film preparation.

[0011] Further, the traction wet film thermal imaging time series data includes a plurality of frames of traction wet film thermal imaging data, and each frame of traction wet film thermal imaging data includes the temperature value and two-dimensional coordinates of each pixel point in the traction wet film thermal imaging, and the wet film thermal evolution analysis model includes an input layer, a wet film heating identification layer, a traction thermal field evolution layer, and an output layer.

[0012] Further, the specific steps of analyzing the wet film overheating risk characteristic value of the film preparation are as follows: inputting the traction wet film thermal imaging time series data of the film preparation into the preprocessed wet film thermal evolution analysis model, analyzing the wet film thermal evolution characteristic set of the film preparation, including the thermal orientation drift trend characteristic value, the thermal orientation drift trend characteristic value, and the thermal boundary fractal complexity characteristic value; based on the wet film thermal evolution characteristic set of the film preparation, analyzing the wet film overheating risk characteristic value of the film preparation.

[0013] Further, the specific steps of analyzing the wet film thermal evolution characteristic set of the film preparation are as follows: in the input layer of the wet film thermal evolution analysis model, receiving a plurality of frames of traction wet film thermal imaging data of the film preparation and performing preprocessing; in the wet film heating identification layer of the wet film thermal evolution analysis model, based on each frame of traction wet film thermal imaging data of the film preparation, extracting the wet film heating state feature vector in the corresponding frame of traction wet film thermal imaging data; in the traction thermal field evolution layer of the wet film thermal evolution analysis model, based on the wet film heating state feature vector in each frame of traction wet film thermal imaging data of the film preparation, extracting the thermal field evolution feature vector of the film preparation; in the input layer of the wet film thermal evolution analysis model, based on the thermal field evolution feature vector of the film preparation, outputting the wet film thermal evolution characteristic set of the film preparation.

[0014] Further, the specific steps of temperature control processing of the film preparation based on the coagulation traction temperature regulation characteristic value and the traction temperature control adjustment characteristic value are as follows: normalizing the coagulation traction temperature regulation characteristic value and the traction temperature control adjustment characteristic value of the film preparation; judging and analyzing the normalized coagulation traction temperature regulation characteristic value and the traction temperature control adjustment characteristic value of the film preparation with respect to a plurality of preset temperature adjustment intervals; and taking appropriate temperature control strategies based on the judgment and analysis results.

[0015] A temperature control system for polyacrylonitrile-based carbon film preparation, comprising: a data acquisition module for acquiring coagulation bath state time series data, traction state time series data, and traction wet film thermal imaging time series data of the film preparation; a coagulation traction regulation analysis module for analyzing the coagulation traction temperature regulation characteristic value of the film preparation based on the coagulation bath state time series data of the film preparation; a traction temperature control adjustment analysis module for jointly processing the traction state time series data and the traction wet film thermal imaging time series data of the film preparation to obtain the traction temperature control adjustment characteristic value of the film preparation; and a joint temperature control module for temperature control processing of the film preparation based on the coagulation traction temperature regulation characteristic value and the traction temperature control adjustment characteristic value.

[0016] The present application has the following beneficial effects:

[0017] (1) The temperature control method for the preparation of polyacrylonitrile-based carbon film synchronously acquires the timing data of the coagulation bath state, the timing data of the traction state, and the timing data of the traction wet film thermal imaging, thereby realizing linkage analysis of the coagulation stage and the traction stage, fully capturing the state differences of the wet film in the coagulation stage and the traction stage, generating corresponding characteristic values through synergistic analysis of the corresponding characteristics, and taking corresponding temperature control strategies, thereby completing the dynamic connection from coagulation to traction, avoiding temperature control lag and extensive regulation, and ensuring that the stretching temperature accurately matches the actual state of the wet film, thereby improving the film forming quality and significantly improving the performance of the polyacrylonitrile-based carbon film.

[0018] (2) The temperature control method for the preparation of polyacrylonitrile-based carbon film introduces a pre-trained wet film thermal evolution analysis model to deeply analyze the traction wet film thermal imaging timing data, thereby quickly identifying the temperature evolution of the wet film during traction. This model not only analyzes the temperature difference distribution of a single image, but also analyzes the evolution of the gradual relationship between multiple images, extracts timing characteristics, and ensures that the temperature control strategy matches the real heating state of the wet film in different stages, thereby significantly improving the pertinence of temperature control regulation, and making temperature control regulation fully utilize complex thermal imaging timing information and improve the refinement level of temperature control.

[0019] (3) The temperature control method for the preparation of polyacrylonitrile-based carbon film normalizes the coagulation and stretching temperature control characteristic values and the traction temperature control adjustment characteristic values, matches them with the pre-set multiple temperature adjustment intervals, and executes differentiated temperature control measures, thereby making the temperature control dynamically switch control modes according to different working conditions. This can identify the current state during wet film preparation and switch to the optimal control mode, significantly improve the accuracy of temperature regulation, and thereby ensure stable film formation of the wet film under variable working conditions while reducing defects such as breakage, thereby effectively improving the overall film forming quality of the polyacrylonitrile-based carbon film.

[0020] (4), the temperature control system for polyacrylonitrile-based carbon film preparation, through the coordinated analysis between modules, so as to realize the accurate temperature control, the data acquisition module can obtain the solidification bath state, the traction state and the traction wet film thermal imaging and other multi-source data in the preparation process; The solidification drawing control analysis module analyzes the solidification driving and forming stability in the solidification stage, the traction temperature control adjustment analysis module extracts the key characteristic value combined with the traction heating state and overheating risk, and the joint temperature control module judges the above analysis results and quickly matches the corresponding temperature control strategy, so that the system can maintain high temperature adaptability under complex preparation conditions, thereby significantly improving the stability of the polyacrylonitrile-based carbon film preparation process.

[0021] Of course, implementing any product of the present application does not necessarily require all the advantages described above to be achieved simultaneously. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A flow chart of a temperature control method for polyacrylonitrile-based carbon film preparation of the present application;

[0023] Figure 2 A schematic diagram of the film preparation coagulation time sequence characteristic set data in the temperature control method for polyacrylonitrile-based carbon film preparation of the present application;

[0024] Figure 3 A flow chart of the specific steps of analyzing the traction temperature control adjustment characteristic value of the film preparation in the temperature control method for polyacrylonitrile-based carbon film preparation of the present application;

[0025] Figure 4 A block diagram of a temperature control system for polyacrylonitrile-based carbon film preparation of the present application. DETAILED DESCRIPTION

[0026] Please refer to Figure 1 The embodiment of the present application provides a technical scheme: a temperature control method for polyacrylonitrile-based carbon film preparation, comprising the following steps: in the spinning film forming process of polyacrylonitrile-based carbon film preparation, obtaining the coagulation bath state time sequence data, the traction state time sequence data and the traction wet film thermal imaging time sequence data of the film preparation in a set period (such as 3s); based on the coagulation bath state time sequence data of the film preparation, analyzing the coagulation drawing temperature control characteristic value of the film preparation; jointly processing the traction state time sequence data and the traction wet film thermal imaging time sequence data of the film preparation to obtain the traction temperature control adjustment characteristic value of the film preparation; based on the coagulation drawing temperature control characteristic value and the traction temperature control adjustment characteristic value, performing temperature control processing on the film preparation.

[0027] The specific steps of temperature control processing based on the solidification drawing temperature regulation characteristic value and the traction temperature control adjustment characteristic value are as follows: normalizing the solidification drawing temperature regulation characteristic value and the traction temperature control adjustment characteristic value of the film preparation (i.e. mapping the values between 0 and 1); judging and analyzing the normalized solidification drawing temperature regulation characteristic value and the traction temperature control adjustment characteristic value of the film preparation with the preset temperature adjustment intervals (and each temperature adjustment interval includes a solidification drawing temperature regulation interval and a traction temperature control adjustment interval, and each temperature adjustment interval corresponds to a temperature control strategy);

[0028] According to the judgment and analysis results, the corresponding temperature control strategy is adopted, that is, the temperature control strategy corresponding to the normalized solidification drawing temperature regulation characteristic value and the traction temperature control adjustment characteristic value within the preset temperature adjustment interval is adopted for the film preparation (drawing) temperature control processing, including but not limited to the following examples:

[0029] Interval group 1 (high solidification orientation, low traction demand):

[0030] Solidification drawing temperature regulation interval: 0.8-1.0 (indicating that the wet film is fully and stably solidified in the solidification stage);

[0031] Traction temperature control adjustment interval: 0.0-0.3 (indicating that the traction process is insufficiently heated and needs to be compensated);

[0032] Strategy: moderately increase the drawing zone temperature (such as 2%-5% above the baseline drawing temperature, but not more than the set safety temperature upper limit, and the baseline drawing temperature is a reference temperature value determined in advance when the process is set), compensate for the insufficient heat in the traction zone;

[0033] Interval group 2 (high solidification orientation, high traction demand):

[0034] Solidification drawing temperature regulation interval: 0.8-1.0;

[0035] Traction temperature control adjustment interval: 0.7-1.0 (indicating that there is a risk of overheating);

[0036] Strategy: although the solidification state allows temperature rise, the traction overheating risk is high, the drawing zone temperature should be lowered (such as 3%-4% below the baseline drawing temperature), to avoid local overheating causing abnormal molecular chain orientation;

[0037] Interval group 3 (low solidification orientation, low traction demand):

[0038] Solidification drawing temperature regulation interval: 0.0-0.3 (indicating that the solidification is insufficient and the forming is fragile);

[0039] Traction temperature control adjustment interval: 0.0-0.3;

[0040] Strategy: Reduce the drawing temperature (e.g., by 2%-3% based on the reference drawing temperature) and maintain low intensity drawing (e.g., reduce the drawing speed by 5%-10%) to avoid film breakage due to incomplete densification of the film;

[0041] Interval group 4 (low solidification orientation, high drawing demand):

[0042] Solidification drawing temperature regulation interval: 0.0-0.3;

[0043] Drawing temperature control adjustment interval: 0.7-1.0;

[0044] Strategy: This combination is in a dangerous state with both insufficient shaping and overheating risk, so the temperature needs to be adjusted downward (e.g., by 5%-6% based on the reference drawing temperature) and the drawing speed needs to be reduced (e.g., by 10%-15%), while an early warning is triggered to prompt process adjustment;

[0045] Interval group 5 (moderate solidification orientation, moderate drawing demand):

[0046] Solidification drawing temperature regulation interval: 0.4-0.6;

[0047] Drawing temperature control adjustment interval: 0.4-0.6;

[0048] Strategy: Maintain the current temperature setting, or dynamically fine-tune within ±1% of the current temperature to ensure film stability.

[0049] Specifically, the solidification bath state time series data includes the solidification bath temperature gradient value, the solvent concentration value, the solidification bath wet film shrinkage rate value, the bath flow shear rate value, the solidification bath interface light transmission value, and the solvent partial pressure value at each time point. The specific steps for analyzing the solidification drawing temperature regulation characteristic value of the film preparation are as follows: based on the solidification bath state time series data of the film preparation, analyze the solidification time series characteristic set of the film preparation, including the solidification bath solidification driving characteristic value and the solidification morphology stability characteristic value at each time point.

[0050] Based on the coagulation time sequence feature set prepared by the film, the coagulation drawing temperature regulation characteristic value of the film preparation is analyzed, which is specifically: based on the coagulation bath solidification driving characteristic value and the coagulation form stability characteristic value of each time point of the film preparation, the coagulation drawing temperature regulation characteristic value of the corresponding time point is analyzed (used to represent the comprehensive guiding effect of the forming state of the wet film in the coagulation stage on the temperature control of the subsequent drawing stage, such as the higher the value, the more sufficient the wet film is solidified and the more stable the form is in the coagulation stage, which can withstand higher drawing temperature to promote molecular chain orientation; When the value is low, it means that the wet film is not solidified enough or the form is unstable in the coagulation stage, and the temperature needs to be reduced in the subsequent drawing stage to avoid instability of the film structure), and the sliding average processing is carried out to obtain the coagulation drawing temperature regulation characteristic value of the film preparation.

[0051] Wherein, the coagulation bath temperature gradient value is the temperature distribution difference of different positions inside the coagulation bath liquid, which reflects the heat convection and temperature distribution uniformity in the coagulation bath. It can be realized by arranging temperature sensors at the upper, middle and lower layers of the coagulation bath to collect the temperature values of each position in real time, and by analyzing the temperature difference between adjacent measuring points and performing weighted processing, the result is taken as the coagulation bath temperature gradient value.

[0052] The solvent concentration value is the concentration of the solvent in the coagulation bath liquid. It can be realized by deploying an electrical conductivity sensor at the outlet of the coagulation bath to measure the electrical conductivity of the coagulation bath liquid, and combining with the calibration curve (which can be in a pre-set standard solvent-non-solvent system, a series of known concentration electrical conductivity values are measured in advance, and a corresponding relationship curve between concentration and electrical conductivity value is established as a calibration curve) to obtain the solvent concentration value.

[0053] The coagulation bath wet film shrinkage rate value is the width shrinkage degree of the wet film in the coagulation process in the coagulation bath. It can be realized by setting a laser diameter measuring instrument at the outlet of the coagulation bath, making the laser beam perpendicular to the width direction of the wet film to scan, and detecting the laser blocking position of the two sides of the wet film by the photoelectric receiver in the laser diameter measuring instrument in real time to obtain the actual width of the wet film at this time point. And compare the initial width (determined by the laser diameter measuring instrument at the first time point before the wet film enters the coagulation bath in the spinning starting stage) to get (initial width-actual width) / initial width, and take the result as the coagulation bath wet film shrinkage rate value.

[0054] The flow shear rate value of the coagulation bath is the shear intensity of the flow field of the coagulation bath liquid, which can be obtained by arranging multiple flow velocity collection points on the cross section of the coagulation bath liquid, for example, arranging flow velocity probes at positions away from the surface of the bath liquid, the middle layer and close to the bottom, or using an ultrasonic Doppler velocity sensor to measure the flow velocity values at different depth positions in a non-contact manner, so as to respectively collect the flow velocity values of each flow velocity collection point, and record the vertical distance between adjacent flow velocity collection points. The local shear rate is analyzed based on the flow velocity difference (the flow velocity values of adjacent flow velocity collection points are subjected to difference processing, and the absolute value is taken) and the vertical distance, that is, the flow velocity difference / vertical distance, and a weighted average processing is performed, and the result is taken as the flow shear rate value of the bath liquid.

[0055] The light transmission value of the coagulation bath interface is the optical uniformity of the interface between the wet film and the coagulation bath liquid. A light source and a photoelectric detector can be arranged at the outlet position of the coagulation bath, so that the light beam vertically penetrates the interface between the wet film and the coagulation bath liquid. At each time point, the incident light intensity and the transmitted light intensity are recorded, and a ratio processing is performed, that is, the transmitted light intensity / incident light intensity, and the result is taken as the light transmission value of the coagulation bath interface.

[0056] The solvent partial pressure value is the partial pressure generated by the solvent vapor in the gas phase region above the coagulation bath liquid. A gas sensor, such as a gas-sensitive sensor, can be arranged in the gas phase region above the coagulation bath liquid to collect the volume fraction of the solvent vapor at each time point. At the same time, the total pressure of the gas phase (i.e. atmospheric pressure, which can be obtained by setting a gas pressure sensor above the coagulation bath) is comprehensively processed, that is, the total pressure of the gas phase x the volume fraction of the solvent vapor, and the result is taken as the solvent partial pressure value at the time point.

[0057] The specific formula for calculating the coagulation drawing temperature regulation characteristic value of the film preparation at a certain time point is as follows: ; wherein, is the coagulation drawing temperature regulation characteristic value of the film preparation at a certain time point, is the coagulation bath solidification driving characteristic value of the film preparation at a certain time point, is the solidification driving adjustment coefficient stored in the database, is the coagulation morphology stability characteristic value of the film preparation at a certain time point, is the morphology stability adjustment coefficient stored in the database, , and in the embodiment, the solidification driving adjustment coefficient and the morphology stability adjustment coefficient stored in the database are 0.475 and 0.525, respectively.

[0058] The specific implementation example of calculating the coagulation drawing temperature regulation characteristic value of a certain time point of film preparation is as follows, and the existing data includes the coagulation bath solidification driving characteristic value and the coagulation morphology stability characteristic value of five time points (randomly selected) of film preparation, and the specific data is shown in Table 1 and Figure 2

[0059] Table 1: Coagulation time sequence characteristic set data example of film preparation

[0060] Coagulation bath solidification driving characteristic value Coagulation morphology stabilizing characteristic value Time point 1 0.682 0.726 Time point 2 0.712 0.753 Time point 3 0.736 0.794 Time point 4 0.694 0.768 Time point 5 0.786 0.813

[0061] The solidification driving adjustment coefficient stored in the database is 0.475.

[0062] The morphology stability adjustment coefficient stored in the database is 0.525.

[0063] Substitute the data in Table 1 and the above coefficients into the specific formula for calculating the coagulation drawing temperature regulation characteristic value of a certain time point of film preparation to obtain:

[0064] The coagulation drawing temperature regulation characteristic value of the first time point of film preparation is 0.475 x 0.682 + 0.525 x 0.726 ≈ 0.705.

[0065] The coagulation drawing temperature regulation characteristic value of the second time point of film preparation is 0.475 x 0.712 + 0.525 x 0.753 ≈ 0.734.

[0066] The coagulation drawing temperature regulation characteristic value of the third time point of film preparation is 0.475 x 0.736 + 0.525 x 0.794 ≈ 0.766.

[0067] The coagulation drawing temperature regulation characteristic value of the fourth time point of film preparation is 0.475 x 0.694 + 0.525 x 0.768 ≈ 0.733.

[0068] The coagulation drawing temperature regulation characteristic value of the fifth time point of film preparation is 0.475 x 0.786 + 0.525 x 0.813 ≈ 0.800.

[0069] ​​​The specific steps for analyzing the condensation time sequence characteristic set of thin film preparation are as follows: Based on the coagulation bath temperature gradient value, solvent concentration value, and solvent partial pressure value at each time point of thin film preparation, the solidification driving characteristic value of the coagulation bath at the corresponding time point is analyzed. Specifically, the coagulation bath temperature gradient value, solvent concentration value, and solvent partial pressure value at each time point are standardized (unit removal). The results of the standardization are then weighted (normalized to between 0 and 1). In this weighting process, the standardized solvent concentration value is inverted, i.e., 1 / (1+standardized solvent concentration value), to obtain the solidification driving characteristic value of the coagulation bath at the corresponding time point. This is used to characterize the strength of the driving effect of the coagulation bath on the densification process of the wet film, thereby reflecting the solidification speed of the wet film in the solidification stage. If the solidification driving characteristic value is high, the wet film is already densified before entering the stretching stage and can withstand higher stretching temperatures.

[0070] Based on the shrinkage rate of the wet film in the coagulation bath, the shear rate of the liquid flow, and the transmittance of the coagulation bath interface at each time point in the thin film preparation, the solidification morphology stability characteristic value at the corresponding time point is analyzed. Specifically, the shrinkage rate of the wet film in the coagulation bath, the shear rate of the liquid flow, and the transmittance of the coagulation bath interface at each time point are standardized (unit removal). The results of the standardization are then weighted (normalized to between 0 and 1). During this weighting process, the standardized shrinkage rate of the wet film in the coagulation bath and the shear rate of the liquid flow are inverted, such as 1 / (1 + standardized shrinkage rate of the wet film in the coagulation bath). This yields the solidification morphology stability characteristic value at the corresponding time point, which is used to characterize the deformation stability of the wet film during the solidification stage. This reflects whether the wet film is stably formed during the solidification stage and determines whether it can withstand higher temperatures during stretching. If the morphology stability characteristic value is high, it indicates that the wet film is stably formed, and the temperature can be appropriately increased during subsequent stretching to promote molecular chain orientation.

[0071] In this implementation scheme, the time-series data of the coagulation bath state during the coagulation stage of the spinning process for preparing polyacrylonitrile-based carbon thin films are divided into two parts: one is the coagulation bath coagulation driving characteristic value reflecting the coagulation driving force, and the other is the coagulation morphology stability characteristic value reflecting the deformation stability. By simultaneously introducing parameters related to coagulation driving, the densification rate of the wet film can be more realistically reproduced. Combined with parameters related to morphology stability, the stability of the wet film in terms of interface and overall morphology can be expressed. By setting different parameter inversions, negative effects can be reasonably suppressed, making the analyzed characteristic values ​​more consistent with the actual process logic. Through this step, the preparation process can not only monitor the coagulation and stability of the wet film, but also use these characteristic values ​​as a guide for temperature control in the drawing zone, forming a dynamic connection from the coagulation stage to the drawing stage, which significantly improves the accuracy of temperature control.

[0072] Specifically, such asFigure 3 As shown, the specific steps of analyzing the traction temperature control adjustment characteristic value of the film preparation are as follows: based on the traction state time series data of the film preparation, the traction heat correction characteristic value of the film preparation is analyzed; based on the pre-trained wet film heat evolution analytical model and combined with the traction wet film heat imaging time series data of the film preparation, the wet film overheating risk characteristic value of the film preparation is analyzed; based on the traction heat correction characteristic value and the wet film overheating risk characteristic value of the film preparation, the traction temperature control adjustment characteristic value of the film preparation (used to represent the temperature regulation demand of the film in the traction process, such as when the characteristic value is too high, the traction zone heating temperature can be lowered to avoid local overheating; when the characteristic value is too low, the traction zone heating temperature can be raised to ensure sufficient molecular chain orientation and film stability) is analyzed, and the specific formula is as follows:

[0073] ; wherein, is the traction temperature control adjustment characteristic value of the film preparation, is the traction heat correction characteristic value of the film preparation, is the traction heat adjustment coefficient stored in the database, is the wet film overheating risk characteristic value of the film preparation, is the overheating risk adjustment coefficient stored in the database, is the proportion adjustment coefficient stored in the database, is the overheating risk smoothing adjustment coefficient stored in the database, and in the embodiment, the traction heat adjustment coefficient , the overheating risk adjustment coefficient , the proportion adjustment coefficient , and the overheating risk smoothing adjustment coefficient stored in the database of the traction heat correction characteristic value of the film preparation take values of 0.426, 0.537, 0.650, and 0.483, respectively.

[0074] The traction state time series data includes the traction coordination ratio value, the traction stress value, the traction energy consumption density value, and the traction heat flow density value at each time point. The specific steps of analyzing the traction heat correction characteristic value of the film preparation are as follows: the traction state time series data of the film preparation is standardized (i.e., the traction coordination ratio value, the traction stress value, the traction energy consumption density value, and the traction heat flow density value at each time point of the film preparation are standardized);

[0075] The traction state time series data of the standardization processed film preparation is comprehensively analyzed to obtain a traction heat bearing characteristic value of the film preparation, which is specifically: the traction stress value, the traction energy consumption density value, the traction heat flow density value of each time point of the standardization processed film preparation are weighted and processed, and the results are slidingly averaged to obtain the traction heat bearing characteristic value of the film preparation (used to represent the immediate heat bearing state of the film under tension, when it is too high, it means that the film has obtained more heat input under larger load, the traction zone heating temperature should be adjusted downward to avoid overheating, otherwise the film is not heated enough and the traction zone heating temperature should be adjusted upward to compensate for the insufficient heating);

[0076] The traction environment temperature control correction characteristic value of the film preparation is obtained, and the traction heat bearing correction characteristic value is analyzed in combination with the traction heat bearing characteristic value, which is specifically: the traction environment temperature control correction characteristic value is weighted and processed to obtain the traction heat correction characteristic value.

[0077] The traction coordination ratio is the ratio of the traction speed to the winding speed, which represents the coordination degree of the film heating time in the traction zone and the winding process, which can be obtained by arranging speed sensors at the traction roller and the winding roller, collecting the traction speed and the winding speed and processing the ratio, and taking the result as the traction coordination ratio. When it is too large, it means that the residence time of the film in the traction zone is relatively prolonged, and the cumulative effect of heat input is enhanced, so the traction zone temperature needs to be adjusted downward to avoid overheating, otherwise it needs to be increased.

[0078] The traction stress value is the instantaneous tensile stress of the film in the traction process, which can be obtained by arranging a tension sensor on the traction roller or a tension detection roller with guiding function to collect the tensile stress value of the film at this time point in real time, and arranging a laser thickness gauge and a laser diameter gauge in the traction zone to measure the film thickness and the film width, so as to obtain the cross-sectional area, and then divide the tensile stress value by the cross-sectional area to obtain the traction stress value.

[0079] The traction energy consumption density value is the energy consumption intensity of the traction driving device per unit time converted to unit film area, which can be obtained by arranging a power sensor at the traction driving motor to collect the instantaneous power value, and arranging a speed sensor on the traction roller to obtain the film running speed, and combining the film width to analyze the film area flow (i.e. film running speed x film width), and processing the ratio of the instantaneous power value to the film area flow, i.e. instantaneous power value / film area flow, and taking the result as the traction energy consumption density value. When it is too large, it means that the energy consumption of the traction motor per unit film area is high, and the film is in a strong energy input state, so the traction zone heating temperature needs to be adjusted downward to avoid overheating.

[0080] The value of the traction heat flow density is the instantaneous heat transfer rate of the film per unit area on the surface of the traction area. It can be obtained by arranging a micro heat flow sensor near the surface of the traction heating area. The micro heat flow sensor is internally provided with a thermocouple array. When heat passes through, a voltage signal proportional to the heat flow density is generated. Through the pre-established voltage-heat flow calibration curve, the voltage signal is converted into the heat flow density value per unit area in real time, so as to obtain the traction heat flow density value at the time point. When it is too large, it means that the heat input of the heating unit is too strong, which may cause local overheating of the film. At this time, the temperature of the traction area needs to be lowered, otherwise it needs to be raised to ensure sufficient orientation of the molecular chain.

[0081] The specific steps for obtaining the traction environment temperature control correction characteristic value of the film preparation are as follows: obtaining the environment temperature value, environment humidity value and environment wind speed value of each time point of the film preparation, and respectively performing ratio processing with the environment temperature reference value, environment humidity reference value and environment wind speed reference value stored in the database, such as |environment temperature reference value-environment temperature value| / environment temperature reference value, based on the ratio result, performing weighted processing and taking the average value, to obtain the traction environment temperature control correction characteristic value.

[0082] The environment temperature value, environment humidity value and environment wind speed value can be obtained by temperature sensor, relative humidity sensor and wind speed sensor respectively.

[0083] The environment temperature reference value, environment humidity reference value and environment wind speed reference value stored in the database are the environment standard parameters set by the enterprise process specification as the corresponding reference values and stored in the database.

[0084] In the embodiment, the current temperature control requirement can be accurately determined by combining the corresponding factors in the traction process. Secondly, the heating and stress conditions of the wet film in the traction area can be comprehensively reflected by standardizing and comprehensively processing the traction state time series data, and the instantaneous fluctuation interference is eliminated by the sliding average, so that the result is closer to the actual process state. At the same time, the parameters related to the environment are additionally introduced, and the effect of the external environment change on the film forming stability is included in the analysis. In this way, even when the workshop environment fluctuates greatly, the temperature control can be reasonably corrected. Finally, the traction temperature control adjustment characteristic value obtained is the comprehensive result of the heating and bearing state and the environment correction, which is more in line with the complex situation in actual production, so as to guide the temperature reduction to prevent local overheating, and prompt the temperature rise to compensate for the deficiency, so as to make the temperature regulation more accurate, and significantly reduce the risk of film breakage and uneven orientation.

[0085] Specifically, the traction wet film thermal imaging time series data includes a plurality of frames of traction wet film thermal imaging data, and each frame of traction wet film thermal imaging data includes a temperature value and a two-dimensional coordinate of each pixel point in the traction wet film thermal imaging, and the wet film thermal evolution analysis model includes an input layer, a wet film heating identification layer, a traction thermal field evolution layer, and an output layer.

[0086] The specific steps of analyzing the wet film overheating risk characteristic value of the film preparation are as follows: input the traction wet film thermal imaging time series data of the film preparation into the preprocessed wet film thermal evolution analysis model, analyze the wet film thermal evolution characteristic set of the film preparation, including the temperature difference deviation fluctuation characteristic value, the thermal orientation drift trend characteristic value, and the thermal boundary fractal complexity characteristic value; based on the wet film thermal evolution characteristic set of the film preparation, analyze the wet film overheating risk characteristic value of the film preparation (used to represent the overheating risk level of the wet film in the overall heating process in the traction zone, and when it is high, it indicates that the wet film has a strong thermal accumulation effect), and the specific formula is as follows:

[0087] ; wherein, is the wet film overheating risk characteristic value of the film preparation, is the temperature difference deviation fluctuation characteristic value of the film preparation, is the temperature difference deviation fluctuation adjustment coefficient stored in the database, is the thermal orientation drift trend characteristic value of the film preparation, is the thermal orientation drift adjustment coefficient stored in the database, is the thermal boundary fractal complexity characteristic value of the film preparation, is the fractal complexity adjustment coefficient stored in the database, is the synergistic adjustment coefficient stored in the database, and in the embodiment, the temperature difference deviation fluctuation adjustment coefficient , the thermal orientation drift adjustment coefficient , the fractal complexity adjustment coefficient , and the synergistic adjustment coefficient stored in the database are 0.462, 0.571, 0.396, and 0.333, respectively.

[0088] The specific steps of analyzing the wet film thermal evolution characteristic set of the film preparation are as follows: in the input layer of the wet film thermal evolution analysis model, receive a plurality of frames of traction wet film thermal imaging data of the film preparation, and perform preprocessing, which specifically includes: using a median filter or a Gaussian filter method to perform denoising processing on each thermal imaging image to eliminate pseudo-pixel points generated by infrared sensor thermal noise, environmental interference, etc., and improve the authenticity of the temperature distribution.

[0089] In the wet film heating identification layer of the wet film thermal evolution analytical model, based on the wet film thermal imaging data of each frame of the film preparation, the wet film heating state feature vector in the corresponding frame of the wet film thermal imaging is extracted; in the traction thermal field evolution layer of the wet film thermal evolution analytical model, based on the wet film heating state feature vector in each frame of the wet film thermal imaging of the film preparation, the thermal field evolution feature vector of the film preparation is extracted, which is specifically: the wet film segments collected by thermal imaging at different time frames are not the same, but each frame of image comes from the same production process, which can be regarded as the dynamic observation results of the process at different time, so that the wet film heating state feature vectors of the continuous frames are input to the time sequence modeling unit in the order of collection, and the time sequence modeling unit can be a one-dimensional convolution network, an improved recurrent neural network or a time sequence Transformer. In this process, the network gradually updates the internal state and maintains the memory of the previous frames by processing the sequential relationship between the frame sequences, so as to capture the evolution trend of the process thermal field over time and generate the thermal field evolution feature vector, such as:

[0090] For the temperature difference bias feature in the wet film heating state feature vector in each frame of the traction wet film thermal imaging, the temperature difference bias feature mean, the temperature difference bias feature maximum and the temperature difference bias feature minimum are extracted, and the ratio processing is performed, (temperature difference bias feature maximum-temperature difference bias feature minimum) / temperature difference bias feature mean, to extract the temperature difference bias fluctuation feature, which is used to represent the time sequence fluctuation degree of the temperature distribution in the horizontal and vertical directions of the wet film. When the characteristic value is larger, it indicates that the temperature difference in the horizontal and vertical directions of the wet film fluctuates violently, the heat distribution is uneven, and the thermal stress is not balanced;

[0091] For the thermal field orientation offset feature in the wet film heating state feature vector in each frame of the traction wet film thermal imaging, the thermal field orientation offset feature change rate in the adjacent frame of the traction wet film thermal imaging is extracted, and the weighted average processing is performed, to extract the thermal orientation drift trend feature, which is used to represent the consistency between the overall orientation of the thermal field and the traction direction. When it is larger, it means that the thermal field orientation gradually deviates from the traction direction with time, and there is an abnormal risk of molecular chain orientation;

[0092] The thermal boundary fractal feature in the wet film heating state feature vector in each frame of the traction wet film thermal imaging is subjected to sliding average processing, to extract the thermal boundary fractal complexity feature, which is used to represent the geometric complexity degree of the thermal spot boundary. When it is larger, it indicates that the thermal spot boundary form is complex and the disturbance is significant, and the wet film has a higher instability risk in the traction process; and the temperature difference bias fluctuation feature, the thermal orientation drift trend feature and the thermal boundary fractal complexity feature are spliced into the thermal field evolution feature vector;

[0093] In the input layer of the wet film thermal evolution analysis model, the thermal field evolution feature vector based on film preparation is input, and the wet film thermal evolution feature set of film preparation is output, which is specifically: the temperature difference bias fluctuation feature, the thermal orientation drift trend feature, and the thermal boundary fractal complexity feature in the thermal field evolution feature vector are respectively activated by the Sigmoid function to obtain the temperature difference bias fluctuation feature value, the thermal orientation drift trend feature value, and the thermal boundary fractal complexity feature value between 0 and 1.

[0094] Wherein, the specific steps of extracting the wet film heating state feature vector in each frame of traction wet film thermal imaging of film preparation are as follows:

[0095] The temperature value of each pixel point in each frame of traction wet film thermal imaging of preprocessed film preparation is respectively calculated in the horizontal and vertical directions (and the horizontal direction is the film width direction, and the vertical direction is the traction direction), and the difference is calculated (the numerical difference operator or Sobel operator can be used to calculate the discrete gradient of the temperature field), to obtain the horizontal temperature gradient value and the vertical temperature gradient value of the pixel point. The absolute value of the horizontal temperature gradient value of each pixel point in each frame of traction wet film thermal imaging is averaged to obtain the horizontal average gradient intensity. The absolute value of the vertical temperature gradient value of all pixel points in the whole image is averaged to obtain the vertical average gradient intensity. The ratio of the difference degree and the total intensity is calculated based on the horizontal average gradient intensity and the vertical average gradient intensity, which is specifically: the absolute value of the difference between the two is taken as the numerator, and the sum of the two is taken as the denominator, and the ratio is calculated. The temperature difference bias feature is extracted to represent the gradient intensity difference of the wet film thermal distribution in the horizontal and vertical directions. When it is close to zero, it indicates that the wet film thermal distribution in the horizontal and vertical directions is balanced. When it is large, it indicates that there is obvious asymmetry in the wet film thermal distribution in the horizontal and vertical directions, which is easy to cause uneven thermal stress of the film body during the traction process.

[0096] The temperature value of each pixel point in each frame of the traction wet film thermal imaging prepared after the pretreatment of the film is processed by mean value to obtain the temperature mean value in the corresponding frame of the traction wet film thermal imaging, and a plurality of threshold intervals are divided above and below the temperature mean value by a fixed step (which can be 0.2-1℃), and the corresponding isotherm is extracted in each threshold interval by using the contour detection algorithm, that is, the contour detection can be performed by pixel-by-pixel scanning, and the pixel points with temperature values in the threshold interval are connected into a closed or open curve, so as to obtain a plurality of isotherms (including a plurality of pixel points belonging to the threshold interval). The two-dimensional coordinates of each pixel point of each isotherm are read and processed, such as using the least square straight line fitting method, that is, the two-dimensional coordinates of each pixel point of the isotherm are input into the fitting algorithm, and an optimal straight line is obtained, so that the straight line is closest to the overall shape of the isotherm, and the slope and intercept parameters of the straight line are obtained, and the direction angle of the straight line is calculated based on the slope parameter, such as arctan (slope parameter). The direction angle of the corresponding straight line fitted by each isotherm is processed by difference with the traction direction (defined as the longitudinal axis direction, the angle is 0°), to obtain the deviation angle of each isotherm;

[0097] The temperature value of each pixel point of each isotherm is read, and the temperature line mean value of each isotherm is extracted, and the sum is processed to obtain the temperature line sum value. The temperature line mean value of each isotherm is processed by ratio with the temperature line sum value to obtain the weight of each isotherm, and the weight is processed by weighting with the deviation angle of the corresponding isotherm to extract the thermal field orientation deviation feature, which is used to represent the deviation degree between the overall orientation of the isotherm of the wet film thermal field and the traction direction. When it is close to zero, it indicates that the orientation of the heat distribution is consistent with the traction direction, and the heated state is relatively uniform and stable. When it is larger, it indicates that the thermal field has deviated obviously, and there is a risk of causing the orientation deviation of molecular chain and unstable traction;

[0098] The temperature mean value in each frame of the traction wet film thermal imaging prepared after the pretreatment of the film is read, and the pixel points higher than the temperature mean value by a certain amplitude (for example, higher than the temperature mean value by 0.5℃) are selected as hot pixel points, and the connected processing (which can adopt 8-neighborhood rule) is performed to obtain a plurality of hot spot regions (and the hot spot regions with hot spot area lower than the preset hot spot area threshold are removed, and the hot spot area is the total number of pixel points in the hot spot region). For each hot spot region, a boundary detection algorithm (such as Canny operator) is used to extract the boundary pixel point set (including a plurality of boundary pixel points) of the corresponding hot spot region.

[0099] Each frame of wet film traction thermal imaging is sequentially divided into a number of square grids of certain scales according to a certain ratio. The grid side length can be gradually reduced from half of the image width to a single pixel size. The reduction ratio factor can be set to one half each time. At each scale, the situation of the boundary pixel points (boundary pixel points in the set of all thermal spot region boundary pixel points) falling into the grid is counted. If at least one boundary pixel point is contained in a certain grid, it is determined that the grid is covered, and the number of covered grids at this scale is counted. The grid side length and the corresponding number of covered grids are logarithmically transformed to obtain a number of logarithmic coordinate points, which are used for linear fitting (least squares fitting method can be used). The slope of the fitted straight line is obtained, which is used as the thermal spot boundary fractal feature to represent the complexity of the thermal spot region boundary. When it is larger, it indicates that the thermal spot boundary form is complex, the thermal field disturbance is significant, and the wet film has a higher instability risk in the traction process. The temperature difference bias feature, thermal field orientation offset feature, and thermal spot boundary fractal feature are spliced into the wet film heating state feature vector.

[0100] The pre-training steps of the wet film thermal evolution analysis model are as follows: obtaining a labeled data set composed of a number of batches of traction wet film thermal imaging sequence data and process parameter record data in the film preparation process, the label is formed by process experts according to experimental monitoring and quality detection results, each sample in the labeled data set includes traction wet film thermal imaging sequence in continuous multiple time periods, each frame of image contains pixel temperature value, two-dimensional coordinate information and wet film thermal state label (such as normal temperature control, overheating risk, orientation offset risk, etc.) labeled by experts, ensuring that the sample has a clear true value label. The labeled data set is preprocessed, including denoising, normalization, thermal spot detection and feature extraction, to obtain the wet film heating state feature vector. The data set is divided into training set, validation set and test set according to the ratio of 8:1:1. All sequences are arranged in chronological order to ensure that the model can learn the time sequence evolution characteristics of the process thermal field.

[0101] The wet film thermal evolution analysis model is trained. Taking the traction thermal field evolution layer as an example, the wet film heating state feature vector (including temperature difference bias feature, thermal field orientation offset feature, and thermal spot boundary fractal feature) extracted from each frame of wet film thermal imaging is input into the time sequence modeling unit (such as one-dimensional convolution network, improved recurrent neural network or time sequence Transformer) in chronological order. In the training process, the time sequence modeling unit learns the dependence between frame sequences through internal mechanisms, captures the evolution trend of the wet film thermal field over time, and generates a thermal field evolution feature vector. The model optimizes the parameters through the back propagation algorithm (BPTT), minimizes the error (such as cross-entropy or mean square error) between the predicted output and the labeled label, and gradually learns the thermal field abnormal pattern and stable pattern of the wet film in the traction area.

[0102] During the training process, an optimization algorithm (such as the Adam optimizer) is used to update the network weights, adjust hyperparameters (such as learning rate, number of hidden layer units, convolution kernel size, etc.) to improve the training performance of the model, and evaluate the performance of the model through the validation set to avoid overfitting. Finally, the generalization ability of the trained model is verified using the test set to ensure that it can accurately extract time series features such as temperature difference fluctuation, orientation shift, and thermal spot complexity from unseen wet film thermal imaging sequences, and output the wet film thermal evolution feature set. After training, the optimal model parameters are saved for real-time deployment and online temperature control risk assessment during actual thin film preparation.

[0103] In this embodiment, the traction wet film thermal imaging time series data of thin film preparation is analyzed in combination with the wet film thermal evolution analysis model, so that the model can extract features such as temperature difference imbalance and orientation drift, and thermal spot complexity. In this way, the heating state of the wet film during traction can be fully described, both the temperature distribution fluctuation in the horizontal and vertical directions can be seen, the shift of the thermal field direction can be captured, and the geometric disturbance of the thermal spot boundary can be revealed. These features are related to whether the thin film will overheat and whether the molecular chain will abnormally orient in the actual process. At the same time, the trend changes of the above features are identified by combining the time series processing in the traction thermal field evolution layer, so that the temperature regulation in the traction stage is more accurate, and the stability of the film formation process is significantly improved.

[0104] Please refer to Figure 4 The embodiment of the present application provides a technical solution: a temperature control system for polyacrylonitrile-based carbon film preparation, comprising: a data acquisition module for acquiring coagulation bath state time series data, traction state time series data, and traction wet film thermal imaging time series data of thin film preparation; a coagulation and drawing control analysis module for analyzing coagulation and drawing temperature control characteristic values of thin film preparation based on coagulation bath state time series data of thin film preparation; a traction temperature control adjustment analysis module for jointly processing traction state time series data and traction wet film thermal imaging time series data of thin film preparation to obtain traction temperature control adjustment characteristic values of thin film preparation; and a joint temperature control module for performing temperature control processing on thin film preparation based on coagulation and drawing temperature control characteristic values and traction temperature control adjustment characteristic values.

[0105] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they understand the basic inventive concept. Therefore, the appended claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0106] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A temperature control method for preparing polyacrylonitrile-based carbon thin films, characterized in that, Includes the following steps: Acquire time-series data on the solidification bath state, traction state, and traction wet film thermal imaging of the thin film preparation. Based on the time-series data of the solidification bath state in thin film preparation, the characteristic values ​​of solidification stretching temperature control in thin film preparation are analyzed. By jointly processing the traction state time-series data and the traction wet film thermal imaging time-series data of thin film preparation, the traction temperature control adjustment characteristic value of thin film preparation is obtained. Temperature control is applied to thin film preparation based on solidification and stretching temperature regulation characteristic values ​​and traction temperature control adjustment characteristic values.

2. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 1, characterized in that, The coagulation bath state time-series data includes the coagulation bath temperature gradient, solvent concentration, wet film shrinkage rate, liquid flow shear rate, interfacial transmittance, and solvent partial pressure at each time point. The specific steps for analyzing the coagulation stretching temperature control characteristics of the thin film preparation are as follows: Based on the time-series data of the solidification bath state in thin film preparation, the time-series feature set of the solidified state in thin film preparation is analyzed, including the solidification driving characteristic value and the solidification morphology stability characteristic value of the solidification bath at each time point. Based on the condensation time sequence characteristic set of thin film preparation, the characteristic values ​​of solidification and stretching temperature control in thin film preparation are analyzed.

3. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 2, characterized in that, The specific steps for analyzing the condensation time sequence feature set of thin film preparation are as follows: Based on the coagulation bath temperature gradient, solvent concentration, and solvent partial pressure at each time point in the thin film preparation, the solidification driving characteristic values ​​of the coagulation bath at the corresponding time points are analyzed. Based on the shrinkage rate of the wet film in the coagulation bath, the shear rate of the liquid flow, and the transmittance of the coagulation bath interface at each time point in the thin film preparation, the stability characteristics of the coagulation morphology at the corresponding time points are analyzed.

4. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 1, characterized in that, The specific steps for analyzing the traction temperature control adjustment characteristic values ​​in thin film preparation are as follows: Based on the time-series data of the traction state of thin film preparation, the characteristic values ​​of traction heating correction of thin film preparation are analyzed. Based on a pre-trained analytical model of wet film thermal evolution, and combined with time-series data of traction wet film thermal imaging during thin film preparation, the characteristic values ​​of wet film overheating risk during thin film preparation are analyzed. Based on the traction heating correction characteristic value and wet film overheating risk characteristic value of thin film preparation, the traction temperature control adjustment characteristic value of thin film preparation is analyzed.

5. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 4, characterized in that, The specific steps for analyzing the traction-heat-corrected characteristic values ​​of thin film preparation are as follows: The timing data of the traction state in thin film preparation were standardized. By comprehensively analyzing the time-series data of the traction state of the prepared film after standardization, the characteristic values ​​of traction heat bearing capacity of the prepared film are obtained. The traction environment temperature control correction characteristic value of the thin film preparation is obtained, and combined with the traction heat bearing characteristic value, the traction heat correction characteristic value of the thin film preparation is analyzed.

6. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 4, characterized in that, The traction wet film thermal imaging time series data includes several frames of traction wet film thermal imaging data, and each frame of traction wet film thermal imaging data includes the temperature value and two-dimensional coordinates of each pixel in the traction wet film thermal imaging. The wet film thermal evolution analytical model includes an input layer, a wet film heating identification layer, a traction thermal field evolution layer, and an output layer.

7. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 6, characterized in that, The specific steps for analyzing the characteristic values ​​of overheating risk in wet films prepared with thin films are as follows: The time series data of thermal imaging of the traction wet film prepared by the thin film were input into the preprocessed wet film thermal evolution analytical model to analyze the feature set of the wet film thermal evolution, including the characteristic value of temperature difference imbalance fluctuation, the characteristic value of thermal orientation drift trend, and the characteristic value of thermal boundary fractal complexity. Based on the thermal evolution characteristic set of wet films prepared by thin film, the overheating risk characteristic value of wet films prepared by thin film is analyzed.

8. The temperature control method for preparing polyacrylonitrile-based carbon films according to claim 7, characterized in that, The specific steps for analyzing the wet film thermal evolution characteristic set of thin film preparation are as follows: In the input layer of the wet film thermal evolution analytical model, several frames of traction wet film thermal imaging data from thin film preparation are received and preprocessed. In the wet film thermal evolution analysis model, the feature vector of the wet film thermal state in the corresponding frame of traction wet film thermal imaging is extracted based on the thermal imaging data of each frame of the thin film preparation. In the traction thermal field evolution layer of the wet film thermal evolution analytical model, the thermal field evolution feature vector of the thin film preparation is extracted based on the feature vector of the wet film heating state in each frame of traction wet film thermal imaging. In the input layer of the wet film thermal evolution analytical model, the thermal field evolution feature vector of thin film preparation is used as the basis to output the wet film thermal evolution feature set of thin film preparation.

9. The temperature control method for preparing polyacrylonitrile-based carbon thin films according to claim 1, characterized in that, The specific steps for temperature control in thin film preparation based on solidification-stretching temperature regulation characteristic values ​​and traction temperature control adjustment characteristic values ​​are as follows: The solidification and stretching temperature control characteristic values ​​and the traction temperature control adjustment characteristic values ​​of thin film preparation were normalized. The solidification and stretching temperature control characteristic values ​​and traction temperature control adjustment characteristic values ​​of the normalized thin film preparation are compared with several preset temperature adjustment ranges for judgment and analysis. Based on the judgment and analysis results, corresponding temperature control strategies are adopted.

10. A temperature control system for preparing polyacrylonitrile-based carbon thin films, employing the temperature control method for preparing polyacrylonitrile-based carbon thin films according to any one of claims 1-9, characterized in that, include: The data acquisition module is used to acquire time-series data of the coagulation bath state, traction state, and traction wet film thermal imaging during thin film preparation. The solidification stretching control analysis module is used to analyze the solidification stretching temperature control characteristic values ​​of thin film preparation based on the solidification bath state time series data. The traction temperature control adjustment analysis module is used to jointly process the traction state time-series data and traction wet film thermal imaging time-series data of film preparation to obtain the traction temperature control adjustment characteristic value of film preparation. The combined temperature control module is used to perform temperature control processing on thin film preparation based on solidification and stretching temperature regulation characteristic values ​​and traction temperature control adjustment characteristic values.

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