Glass optical fiber drawing furnace temperature control system based on adaptive thermal coupling compensation

Abstract

The glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation provided by this invention belongs to the field of fiber drawing technology. This invention can achieve online and accurate identification of the aging state of the heating elements in the drawing furnace. By extracting the real-time heating time constant through no-load step response testing and comparing it with the reference value, a dynamic aging compensation coefficient is generated. This effectively eliminates the slow drift of the temperature field caused by long-term service of the elements, significantly improves the long-term stability and accuracy of furnace temperature control, and ensures the consistency of fiber geometry. At the same time, by coupling the aging compensation coefficient with the real-time drawing speed, a power correction command that dynamically adjusts according to the operating conditions is generated, enabling the temperature control system to adapt to process changes and further optimizing transient response characteristics.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber drawing technology, specifically relating to a temperature control system for a glass optical fiber drawing furnace based on adaptive thermal coupling compensation. Background Technology

[0002] Fiber optic drawing is a core step in fiber manufacturing. The principle involves heating fiber preforms to a molten state in a high-temperature drawing furnace, and drawing them into fibers with specific geometric dimensions and optical properties by precisely controlling the distribution and stability of the temperature field within the furnace. As a critical thermal component, the temperature control accuracy of the drawing furnace directly determines the fiber's diameter uniformity, attenuation characteristics, and mechanical strength. With the development of communication networks towards higher capacity and higher speeds, the requirements for fiber performance consistency are becoming increasingly stringent, and the temperature control technology of drawing furnaces is constantly evolving. Early drawing furnaces mostly used PID control strategies based on thermocouple feedback, maintaining the set temperature by adjusting the heating power. However, the drawing process has large inertia, pure time delay, and strong coupling characteristics, making traditional PID control difficult to adapt to changes in process parameters and external disturbances. Therefore, in recent years, the industry has gradually introduced advanced algorithms such as model predictive control, fuzzy control, and feedforward compensation, combined with distributed control systems to achieve multi-temperature zone coordinated regulation. Simultaneously, the structural design of drawing furnaces has been continuously optimized, for example, by using graphite heating elements, multi-layer insulation structures, and inert gas protection to improve thermal efficiency and temperature field uniformity. Nevertheless, existing technologies still face several bottlenecks: On the one hand, heating elements inevitably undergo oxidation, sublimation, and structural creep under long-term high-temperature service, leading to changes in their resistance characteristics and thermal radiation efficiency, i.e., the so-called aging phenomenon. This slow time-varying characteristic causes the control model with fixed parameters to gradually become mismatched, resulting in temperature field drift. On the other hand, the circulating water cooling system or power supply system may suddenly fail during the wire drawing process. If not handled properly, the rapid change in furnace temperature will generate thermal stress impact inside the furnace material, and may even cause the preform to oxidize or crack, resulting in significant economic losses.

[0003] In existing technologies, compensation for heating element aging typically relies on periodic manual calibration or empirical correction coefficients. Manual calibration requires interrupting production for no-load testing, which is time-consuming and fails to capture the gradual effects of the aging process. Empirical corrections, on the other hand, ignore individual differences and operating condition coupling, resulting in limited compensation accuracy. For example, some solutions use cumulative operating time as a substitute indicator for the degree of aging, but the actual aging rate is affected by factors such as temperature history and power fluctuations, making it difficult for time indicators to accurately reflect the true state. Regarding handling abnormal operating conditions, traditional practices often involve emergency disconnection of the heating power supply and reliance on natural cooling of the furnace. However, if the initial natural cooling rate is too rapid, it can easily cause thermal stress cracks in the quartz glass or refractory materials. Simultaneously, as the high-temperature gas inside the furnace decreases in volume, it shrinks as the temperature drops. If no active gas protection measures are taken, external air will be drawn into the furnace, causing oxidation of the graphite heating elements and preform surfaces, severely affecting the quality of subsequent processes. Furthermore, existing anomaly detection systems often only provide alarm functions and fail to link with subsequent protection mechanisms. Operators must manually check thermal parameters and initiate emergency procedures, delaying the optimal intervention time. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by this invention is: how to achieve online accurate identification and dynamic compensation of the aging state of the heating element of the fiber drawing furnace in order to maintain the stability of the temperature field during long-term operation; and how to achieve controlled cooling and gas protection of the furnace body when the circulating water or power supply is abnormal, so as to avoid thermal stress damage and oxidation risk, thereby ensuring the continuous and reliable operation of the optical fiber drawing process.

[0007] To address the aforementioned technical problems, the present invention provides the following technical solution: The temperature control system for a glass fiber drawing furnace based on adaptive thermal coupling compensation includes: an aging parameter acquisition module, used to perform standard tests under no-load conditions, obtain the furnace heating time constant, and calculate the aging compensation coefficient; a temperature control command correction module, used to correct the heating power command during the drawing process according to the aging compensation coefficient, to offset the temperature field drift caused by the aging of the heating element; an abnormal operating condition identification module, used to monitor the circulating water pressure and power supply status in real time, trigger an early warning when an abnormal signal is detected, and read thermal inertia data from the SCADA historical database; and a conformal cooling execution module, used to generate a controllable cooling curve based on the thermal inertia data under abnormal operating conditions, while controlling the inert gas flow rate to maintain a slight positive pressure inside the furnace to protect the materials inside the furnace.

[0008] In a preferred embodiment of the present invention, the aging parameter acquisition module includes: before the start of the wire drawing operation and when there are no preforms in the furnace, confirming that the furnace temperature has dropped to the ambient temperature, and continuously injecting inert gas into the furnace at a first gas flow rate to obtain a stable unloaded initial thermal environment; in the stable unloaded initial thermal environment, applying a preset step power command to the heating element, and simultaneously recording the complete temperature response data of the furnace temperature rising from the initial temperature to the target temperature; based on the temperature response data, extracting the current heating time constant of the furnace in the current state at the time point corresponding to n% of the difference between the initial temperature and the target temperature; comparing the current heating time constant with the reference time constant stored in the SCADA system, and calculating the aging compensation coefficient.

[0009] In a preferred embodiment of the present invention, the comparison is performed by calculating the aging compensation coefficient using a ratio or difference method.

[0010] In a preferred embodiment of the present invention, the temperature control command correction module includes: reading the current drawing speed setting value and the current base power command of the main heating zone from the SCADA system; multiplying the aging compensation coefficient by the ratio of the drawing speed setting value to a preset speed reference value to obtain a dynamic power compensation value that varies with the drawing speed; adding the dynamic power compensation value to the current base power command to generate the final actual heating power command and sending it to the heating power supply for execution.

[0011] In a preferred embodiment of the present invention, the abnormal operating condition identification module includes: continuously acquiring the current analog value of the circulating water pressure and the current on / off status signal of the power supply line at a first sampling frequency; comparing the current analog value with a preset pressure lower limit threshold, and simultaneously determining whether the current on / off status signal is in a power outage state; determining an abnormal operating condition when either condition is met; immediately triggering an audible and visual warning signal after determining the abnormal operating condition, and simultaneously sending a data read request to the SCADA historical database to retrieve the most recently calibrated current heating time constant as thermal inertia data.

[0012] In a preferred embodiment of the present invention, the conformal cooling execution module includes: using the thermal inertia data as the basis for calculating the furnace body heat loss rate, generating a controllable cooling curve with a first cooling rate as the target slope and without generating thermal stress impact; converting the controllable cooling curve into a power reduction command on a time series and continuously sending it to the heating power supply in a first control cycle, so that the furnace temperature decreases along the controllable cooling curve; while sending the power reduction command, maintaining the inert gas pressure in the furnace at a preset micro-positive pressure value through a proportional regulating valve to prevent external air from being drawn into the furnace chamber when the furnace temperature decreases and contracts; after the furnace temperature drops below a preset safe storage temperature, issuing a completion signal and maintaining the inert gas pressure until the process is completed.

[0013] As a preferred embodiment of the present invention, the generation of the controllable cooling curve includes: reading the heating time constant of the current furnace body from the abnormal operating condition identification module; determining the first cooling rate and the safe storage temperature, and ensuring that the first cooling rate does not exceed the maximum thermal stress impact limit allowed by the furnace body material; estimating the heat loss rate of the furnace body under natural cooling state by combining thermal inertia data and the difference between the current furnace temperature and the ambient temperature; starting from the current furnace temperature, linearly decreasing to the safe storage temperature according to the first cooling rate to obtain a target curve of temperature change over time; if the rate at any moment during the linear decrease exceeds the stress limit, automatically adjusting the local rate or introducing a smooth transition section; checking whether the target curve meets the power output range of the heating power supply and the actual response capability of the furnace body; and using the finally determined temperature-time relationship curve as the controllable cooling curve.

[0014] As a preferred embodiment of the present invention, converting the controllable cooling curve into a power reduction command on a time sequence includes: dividing the time range of the controllable cooling curve into continuous time nodes with a first control cycle as the interval; reading the target furnace temperature value corresponding to each time node according to the controllable cooling curve; using the thermal dynamic model of the furnace body, combined with the target temperature change of adjacent nodes and the temperature difference between the current furnace temperature and the environment, calculating the heating power required to reduce the furnace temperature along the curve; performing amplitude limiting processing on the calculated power value to ensure that it is within the minimum and maximum power range allowed by the heating power supply, and smoothing the power commands of adjacent nodes to prevent power abrupt changes; arranging each time node and the corresponding power command in chronological order to form a power reduction command sequence; during the conformal cooling process, sending the corresponding power command to the heating power supply sequentially according to the first control cycle to achieve a controlled decrease in furnace temperature.

[0015] The beneficial effects of this invention are as follows: Compared with the prior art, the technical effects of this invention are as follows: This invention can achieve online and accurate identification of the aging state of heating elements in a wire drawing furnace. By extracting the real-time heating time constant through no-load step response testing and comparing it with a reference value, a dynamic aging compensation coefficient is generated. This effectively eliminates the slow drift of the temperature field caused by long-term service of the elements, significantly improves the long-term stability and accuracy of furnace temperature control, and ensures the consistency of optical fiber geometry. At the same time, by coupling the aging compensation coefficient with the real-time wire drawing speed, a power correction command that dynamically adjusts according to the operating conditions is generated, enabling the temperature control system to have the ability to adapt to process changes, further optimizing transient response characteristics.

[0016] In terms of handling abnormal operating conditions, this invention can immediately trigger an early warning when the circulating water pressure is too low or the power supply is interrupted, and automatically retrieve the most recently calibrated thermal inertia data to generate a controllable cooling curve that meets thermal stress constraints. Through precise power following control, the furnace temperature drops along a preset safe slope, effectively avoiding thermal stress damage caused by rapid cooling. The synchronously executed micro-positive pressure inert gas protection completely eliminates the intake of external air during the furnace temperature drop and contraction process, preventing oxidation and contamination of high-temperature graphite components and preforms.

[0017] Furthermore, this invention significantly shortens the response time from the occurrence of a fault to the protective action, reduces the risk of delay due to manual intervention, provides intelligent safety assurance for the entire life cycle of the wire drawing furnace, and can provide key thermal inertia trend data for subsequent process optimization and predictive maintenance. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation described in this invention.

[0019] Figure 2This is a schematic diagram of the operation of the temperature control command correction module described in this invention.

[0020] Figure 3 This is a schematic diagram of the operation of the abnormal working condition identification module described in this invention.

[0021] Figure 4 This is a schematic diagram of the conformal cooling execution module operation described in this invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0023] like Figure 1 As shown, the glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation of the present invention includes: The aging parameter acquisition module is used to perform standard tests under no-load conditions, obtain the furnace heating time constant, and calculate the aging compensation coefficient; the temperature control command correction module is used to correct the heating power command during the wire drawing process according to the aging compensation coefficient to offset the temperature field drift caused by the aging of the heating element; the abnormal working condition identification module is used to monitor the circulating water pressure and power supply status in real time, trigger an early warning when an abnormal signal is detected, and read thermal inertia data from the SCADA (Supervisory Control and Data Acquisition) historical database; the conformal cooling execution module is used to generate a controllable cooling curve based on the thermal inertia data under abnormal working conditions, and at the same time control the inert gas flow to maintain a slight positive pressure inside the furnace to protect the materials inside the furnace.

[0024] It should be noted that existing technologies typically address heating element aging by periodic manual calibration or compensation based on empirical formulas. However, manual calibration is time-consuming and struggles to capture slow drift, while empirical formulas cannot adapt to individual differences and changes in operating conditions, leading to a gradual decrease in temperature control accuracy over service life. This invention, through constructing a standard no-load test condition and utilizing step response analysis to extract the heating time constant online, achieves precise quantification of aging characteristics. Specifically, in this invention, the aging parameter acquisition module includes:

[0025] Step 11: Before the wire drawing operation begins and there are no preforms in the furnace, confirm that the furnace temperature has dropped to the ambient temperature, and continuously inject inert gas into the furnace at the first gas flow rate to obtain a stable initial thermal environment under no-load conditions.

[0026] To achieve the above objectives, the following technical solutions are specifically included: First, the furnace temperature signal is collected in real time by thermocouples or infrared temperature sensors installed inside the furnace chamber, and then transmitted to the controller. The controller has a preset ambient temperature threshold, which is usually set to a range where the deviation from the current workshop ambient temperature does not exceed ±2℃.

[0027] When the furnace body temperature is detected to continuously fall within the threshold range for a duration of a first preset time (e.g., 30 minutes), it is determined that the furnace body has reached a thermal equilibrium state.

[0028] Meanwhile, to avoid residual convection disturbances affecting test accuracy, the controller activates the gas mass flow controller to continuously inject inert gas (such as nitrogen or argon) into the furnace at a first gas flow rate (e.g., 5~10 liters / minute). This flow rate must ensure that the pressure inside the furnace is slightly higher than the external atmospheric pressure to create a slightly positive pressure environment and prevent external air from seeping in.

[0029] Through the above operations, an unloaded initial thermal environment with no preforms, no residual heat sources, and stable airflow can be established in the furnace, providing repeatable benchmark conditions for subsequent step tests.

[0030] Step 12: In the stable initial thermal environment without load, apply a preset step power command to the heating element and simultaneously record the complete temperature response data of the furnace body temperature rising from the initial temperature to the target temperature.

[0031] After confirming the stability of the no-load thermal environment, the controller sends a step command with an amplitude of a preset step power value to the heating power supply. This preset step power value needs to balance response speed and furnace safety, and is typically set to 30% to 70% of the heating power supply's rated power. For example, for a 50kW rated furnace, the step power can be set to 25kW. The moment the command is issued, the controller's internal high-precision timer starts, and simultaneously begins acquiring the output signal from the furnace temperature sensor at the first sampling frequency (e.g., 10Hz), recording time-temperature data pairs in real time.

[0032] The temperature recording range starts from the initial temperature (i.e., ambient temperature) before the step is applied and continues until the furnace temperature rises to the preset target temperature.

[0033] The target temperature should be set below the maximum withstand temperature of the furnace material, while ensuring that the temperature rise is sufficient to accurately identify the thermal inertia characteristics. It is usually set to 100°C to 200°C above the initial temperature. The recording process continues until the furnace temperature reaches the target temperature and stabilizes, thus obtaining a complete step response temperature rise curve.

[0034] The above operations eliminate errors caused by differences in excitation amplitude or asynchronous sampling.

[0035] Step 13: Based on the temperature response data, extract the current heating time constant of the furnace body in the current state at the time point corresponding to n% of the difference between the starting temperature and the target temperature.

[0036] In practice, after obtaining the step response data, the controller first filters the collected raw temperature data. It can use moving average filtering or median filtering algorithms to remove measurement noise and occasional interference.

[0037] Subsequently, the steady-state total change in temperature response is calculated, which is the difference ΔT between the target temperature and the initial temperature. According to the definition of the time constant of a first-order system, the controller searches for the moment when the temperature value first reaches the initial temperature + n%×ΔT in the time-temperature data sequence, where n is usually taken as 63.2 (corresponding to the 63.2% response point of a first-order system).

[0038] The time difference between this moment and the initial moment of the step application is the current heating time constant. .

[0039] Optionally, to improve accuracy, curve fitting can also be used to fit the entire response data with the first-order system model using least squares to extract the optimal time constant.

[0040] The extracted time constant is stored in the controller's non-volatile memory and synchronously uploaded to the SCADA system's historical database, marked as the most recently calibrated current heating time constant.

[0041] It should be noted that the time constant is extracted using the classic 63.2% response point method or model fitting method. The physical meaning is clear, the algorithm is mature and reliable, and it can accurately quantify the thermal inertia characteristics of the furnace body in the current state. This provides an objective quantitative indicator for the assessment of the degree of aging and avoids the ambiguity of subjective experience judgment.

[0042] Step 14: Set the current heating time constant The aging compensation coefficient is calculated by comparing it with the reference time constant stored in the SCADA system, wherein the aging compensation coefficient is calculated by ratio or difference method.

[0043] Preferably, the controller reads a preset reference time constant from the historical database of the SCADA system. This reference time constant is typically obtained during the first no-load test after a new furnace is put into operation or after the heating elements are replaced, and serves as the reference origin for all subsequent aging comparisons.

[0044] Subsequently, a comparison operation is performed according to the preset calculation logic. When the ratio method is used, the aging compensation coefficient is: A coefficient greater than 1 indicates a decrease in heating efficiency, requiring an increase in power; a coefficient less than 1 indicates an improvement in heating efficiency (e.g., after replacing a new component), allowing for a reduction in power. This ratio can be directly used as a multiplicative correction factor for subsequent power commands.

[0045] Furthermore, when using the difference method, the increment of the time constant is calculated: ; Then, by querying the pre-calibrated power compensation coefficient mapping table, the corresponding power compensation value or compensation coefficient can be obtained.

[0046] The calculated aging compensation coefficient is updated in real time to the controller's operating parameter area for use by the temperature control command correction module. Simultaneously, this coefficient and its calculation timestamp are stored in the SCADA system, forming an aging trend record.

[0047] It should be noted that this invention generates a compensation coefficient with clear physical meaning by quantitatively comparing the real-time extracted time constant with a reference value. Both the ratio method and the difference method transform the slow aging process of the heating element into quantifiable and real-time correctable mathematical parameters, effectively offsetting the temperature field drift caused by aging.

[0048] In this embodiment of the invention, to address the shortcomings of existing technologies where heating power commands are based solely on basic process parameters, fail to dynamically compensate for temperature field drift caused by heating element aging, and do not consider the impact of wire drawing speed changes on heat load requirements, a temperature control command correction module is provided. This module generates a power command that dynamically adjusts according to operating conditions by integrating aging compensation coefficients and real-time process parameters, achieving high-precision adaptive control of the temperature field. The following details each sub-step of this module in conjunction with specific embodiments: In this embodiment of the invention, as... Figure 2 As shown, the temperature control command correction module specifically includes:

[0049] Step 21: Read the current wire drawing speed setting and the current base power command of the main heating zone from the SCADA system.

[0050] In practice, the controller periodically sends data read requests to the SCADA system via an industrial Ethernet or fieldbus communication interface, according to a preset communication protocol. These requests contain labels for the parameters to be read, including the wire drawing speed setpoint (usually in meters per minute) characterizing the current process state, and the base power command for the main heating zone (usually in kilowatts) set by the upstream process model or operator.

[0051] After receiving the request, the SCADA system retrieves the latest parameter values ​​from the real-time database and encapsulates them into a response data packet to return to the controller.

[0052] To ensure the real-time performance and validity of the data, the controller is equipped with a data validity verification mechanism. For example, it checks whether the read value is within a preset reasonable range (the wire drawing speed is usually 0~3000m / min, and the basic power is 0~rated power). It also monitors the rate of change of continuously read data to eliminate abnormal jumps caused by communication interference.

[0053] The read operation is executed cyclically in the second control cycle (e.g., 100 milliseconds) to ensure that the subsequent calculation module can obtain the latest process parameters.

[0054] Step 22: Multiply the aging compensation coefficient by the ratio of the wire drawing speed setting value to a preset speed reference value to obtain a dynamic power compensation value that varies with the wire drawing speed.

[0055] The controller first reads the aging compensation coefficient calculated and stored by the aging parameter acquisition module from its internal memory. This coefficient reflects the efficiency change of the heating element relative to a reference state. Simultaneously, a speed reference value is read from the preset parameter area. This benchmark value is usually defined as the rated speed of the wire drawing machine or the commonly used process speed, and is used as a normalization factor for the influence of speed.

[0056] Subsequently, the controller performs the first-level operation: calculating the speed impact factor. ; in, Set the current wire drawing speed.

[0057] This ratio represents the proportion of heat load demand at the current process speed relative to the baseline speed.

[0058] Next, the second-level operation is performed: calculating the dynamic power compensation value. ; This calculation process is completed at high speed in the controller using a floating-point arithmetic logic unit. The result is a dimensionless or power-dimensional compensation value (the specific dimension depends on the subsequent superposition method with the basic instruction. In this embodiment, the result after being used as a multiplicative factor is still a dimensionless coefficient, which needs to be converted in combination with the basic power dimension, or it can be directly used as an additive compensation amount, see step 23 for details).

[0059] To prevent abnormal calculation results, the controller also... A limiting process is performed to ensure the value is between the preset minimum and maximum compensation coefficients (e.g., 0.8~1.2). After calculation, the dynamic compensation value is temporarily stored in the output register, awaiting superposition with the base power command.

[0060] Furthermore, as another embodiment, if the aging compensation coefficient is obtained using the difference method (e.g.) Corresponding power compensation coefficient Then the dynamic power compensation value The calculation formula can be adjusted as follows: ; Or it can be directly used as an additive compensation term in subsequent calculations. Set the current wire drawing speed.

[0061] Step 23: Add the dynamic power compensation value to the current base power command to generate the final actual heating power command and send it to the heating power supply for execution.

[0062] In specific operation, the controller extracts the current base power command of the main heating zone from the real-time process parameters read in step 21. (Unit: kilowatts), and read the dynamic power compensation value from the calculation result register in step 22. The calculation is performed according to the preset compensation overlay mode: if If the coefficient is dimensionless (i.e., the aging compensation coefficient is a ratio and has been multiplied by the speed factor), then the final power command is: ,at this time In essence, it is the total correction factor; if For compensation values ​​with power dimensions (e.g., the result of the difference method), the final power command P.

[0063] In this embodiment, a multiplicative superposition method is preferred to maintain the proportional relationship with the base power command, which is more in line with the physical process.

[0064] After the calculation is completed, the controller... The final safety verification includes: whether the rated power of the heating power supply is exceeded, whether it is lower than the minimum power requirement of the process, and whether the difference between the power supply and the previous cycle instruction exceeds the allowable power change rate.

[0065] If the verification passes, the value is sent to the power regulator of the heating power supply via an analog output module (such as a 4-20mA current signal or a 0-10V voltage signal) or a digital communication protocol (such as PROFIBUS or EtherCAT). The sending action is synchronized with steps 21 and 22, and is executed cyclically in a third control cycle (e.g., the same as or slightly shorter than the reading cycle, such as 50 milliseconds) to achieve real-time tracking control. Simultaneously, the controller feeds back the final output actual heating power command to the SCADA system for recording and display, facilitating operator monitoring.

[0066] As can be seen, this invention generates an actual heating command that integrates aging state and process speed by superimposing dynamic compensation values ​​with basic power commands, thus achieving precise control of the heating power supply. The final command's safety verification ensures that the execution process does not exceed equipment limits or cause process risks, while real-time command feedback provides data support for system monitoring and subsequent optimization.

[0067] In embodiments of the present invention, such as Figure 3 As shown, the abnormal operating condition identification module specifically includes:

[0068] Step 31: Continuously acquire the current analog value of the circulating water pressure and the current on / off status signal of the power supply line at the first sampling frequency.

[0069] Preferably, the controller connects to a pressure transmitter installed on the circulating water pipeline via its analog input module. This transmitter outputs a standard 4-20mA current signal, which is converted into a 0-10V voltage signal by high-precision resistance sampling. This voltage signal is then continuously sampled and digitized by an analog-to-digital converter at a first sampling frequency (e.g., 100Hz). The sampled data is processed by a digital filtering algorithm (such as a first-order low-pass filter or moving average filter) to remove spike noise, obtaining an analog value representing the current circulating water pressure. .

[0070] Simultaneously, the controller connects to the auxiliary contacts of the main contactor and / or voltage detection relay of the power supply line via a digital input module to acquire the on / off status signal of the power supply line in real time. This signal is a dry contact signal, which, after being input through opto-isolation, is periodically scanned by the controller (the scanning frequency is synchronized with or higher than the analog sampling frequency, such as 200Hz) to obtain the current status value. , where 1 indicates normal power supply and 0 indicates power outage.

[0071] To ensure the reliability of the data acquisition, the controller performs anti-jitter processing on the status signals, meaning that a status change is only confirmed when multiple consecutive sampling results are consistent. All acquired data is timestamped and stored in the controller's loop buffer for subsequent logical judgment and fault tracing.

[0072] Step 32: Compare the current analog quantity value with the preset pressure lower limit threshold, and at the same time determine whether the current on / off state signal is in a power-off state. If any condition is met, it is determined to be an abnormal working condition.

[0073] Specifically, the controller has two independent exception detection conditions preset inside.

[0074] The first condition pertains to circulating water pressure: a pre-set low pressure threshold (e.g., 0.2 MPa, determined by process safety requirements) is used by the controller to obtain the current pressure value in step 31. Compare with the lower pressure threshold. If If the pressure is less than or equal to the lower pressure threshold and the duration exceeds the preset first delay time (e.g., 2 seconds, to avoid instantaneous pressure fluctuations), then the first condition is deemed met.

[0075] The second condition pertains to the power supply status: the controller directly determines the current power supply status signal. If the value is 0 (power off state), a second anti-shake delay is also set (e.g., 0.5 seconds). If the value remains 0, the second condition is considered met.

[0076] The judgment logic of the above two conditions is an OR relationship. That is, as long as either condition is true, the state machine inside the controller will jump from the normal state to the abnormal state and record the time of the abnormality, the type of abnormality (low pressure or power failure) and the parameter value at that time.

[0077] The determination result is written to the exception event log and triggers a global interrupt flag to initiate subsequent steps.

[0078] It can be seen that the use of OR logic combination judgment covers the two most common types of critical faults (cooling failure and power interruption). The judgment conditions are clear and have delayed confirmation, which not only ensures the timeliness of abnormal response, but also avoids false triggering caused by instantaneous jitter.

[0079] Step 33: After determining that the abnormal working condition is as described above, immediately trigger the audible and visual warning signal, and at the same time send a data read request to the SCADA historical database to retrieve the most recently calibrated current heating time constant as thermal inertia data.

[0080] Once step 32 determines that an abnormal operating condition has been established, the controller immediately drives an external audible and visual alarm (such as a buzzer and a rotating warning light) through its digital output module to output a continuous or flashing alarm signal until the operator confirms a reset.

[0081] At the same time, the controller starts a concurrent data reading thread to send structured query requests to the SCADA system's historical database via industrial Ethernet or fieldbus.

[0082] The request contains a specific data tag, namely the most recently calibrated current heating time constant, and limits the query to the most recent timestamped record. Upon receiving the request, the SCADA system retrieves the corresponding time constant value from the historical database. The system records the calibration time and returns it to the controller. Upon receiving this data, the controller stores it in a dedicated thermal inertia data register and marks the data source time and validity.

[0083] If communication times out or the returned data is invalid, the controller will use preset default thermal inertia data (such as factory calibration value) as a backup and simultaneously issue a level two warning to alert the operator of the data anomaly. This thermal inertia data is then sent to the input of the conformal cooling execution module for later use.

[0084] It should be noted that existing technologies, when faced with emergencies such as circulating water failure or power outages, often resort to emergency shutdown and cutting off all heating power, allowing the furnace temperature to cool naturally with the environment. In this approach, the cooling rate is entirely determined by the furnace's thermal inertia and the ambient temperature difference, resulting in extremely rapid initial cooling and a high risk of thermal stress cracks within the quartz glass or refractory materials. Simultaneously, the high-temperature gas inside the furnace contracts in volume as the temperature decreases; without gas protection measures, external air will be drawn into the furnace, causing oxidation and damage to the preforms or internal components. This invention addresses these problems by actively controlling the cooling process and maintaining a slight positive pressure within the furnace. In this invention embodiment, as... Figure 4 As shown, the conformal cooling execution module specifically includes:

[0085] Step 41: Using the thermal inertia data as the basis for calculating the furnace body heat loss rate, generate a controllable cooling curve with the first cooling rate as the target slope and without generating thermal stress impact.

[0086] The generation of the controllable cooling curve includes the following steps:

[0087] Read the most recently calibrated current heating time constant from the dedicated register of the abnormal operating condition identification module. (Unit: seconds) This constant characterizes the thermal inertia of the furnace body under the current state and is the core parameter for calculating the heat loss rate.

[0088] Read the first cooling rate from the system preset parameter area. (Unit: ℃ / min), Safe storage temperature (Unit: °C) and the limiting cooling rate corresponding to the maximum allowable thermal stress shock of the furnace material. (Unit: ℃ / min). Simultaneously, the current measured furnace temperature is obtained through a temperature sensor. (Unit: °C) and ambient temperature (Unit: °C)

[0089] Furthermore, based on a first-order thermal system model, the instantaneous natural cooling rate of the furnace body under the current temperature difference is calculated: ; in, The unit needs to cooperate with Maintain consistency (e.g., uniformly convert to ℃ / min). This rate is used to evaluate the furnace's own heat dissipation capacity and is compared with a preset first cooling rate to determine the feasibility of the target cooling curve.

[0090] At the current furnace temperature Starting from a constant rate linear descent An idealized linear cooling curve is obtained: ; in, For time variables (unit: min or s, must be compared with) (Unit matching). Discretize the curve into a series of time-temperature nodes, with the node interval being the time unit of the subsequent control cycle (e.g., 1 second).

[0091] Iterate through each discrete node, calculate the actual cooling rate between adjacent nodes, and ensure that the rate between any two points does not exceed [the actual cooling rate]. If a certain cooling rate exceeds the limit, the target slope of that segment is automatically adjusted to reduce the local cooling rate. A smooth transition function (such as an S-curve or a first-order hysteresis filter) is introduced to connect the preceding and following segments, ensuring that the entire curve is continuous and second-order differentiable. The corrected curve may exhibit piecewise linear or nonlinear characteristics, but the overall descent time remains within an acceptable range.

[0092] The corrected temperature curve was input into the furnace thermal model for simulation to estimate the power output range required to achieve the curve, and compared with the maximum output power of the heating power supply. and minimum adjustable power Linear comparison. If the power demand exceeds [a certain threshold] during a certain period. If the required power is lower than the required power, then the cooling rate of the corresponding section will be further reduced; If natural cooling is maintained, the curve extends according to the natural cooling law. Ultimately, a controllable cooling curve that balances thermal stress safety and actuator capability is generated and stored in the controller's memory in tabular or functional form.

[0093] Step 42: Convert the controllable cooling curve into a power reduction command on a time series and continuously send it to the heating power supply in the first control cycle to make the furnace temperature decrease along the controllable cooling curve.

[0094] Set the first control cycle (Unit: seconds), the total time length of the controllable cooling curve is divided into... At any given moment: ,in The moment when the exception occurs and execution begins. For expected arrival The time point. Each time point corresponds to a target temperature value. .

[0095] Based on the controllable cooling curve, the target furnace temperature value at each time point is read to form a target temperature sequence. .

[0096] Based on the first-order thermal dynamic model of the furnace body, for each control cycle From 0 to (N−1), the following formula is used to calculate the temperature from the current temperature. Transition to the next target temperature Required heating power : ; in, For the first The heating power command to be applied per control cycle, in kW; The power-temperature gain coefficient, in °C / kW, is obtained from the step response experiment during system commissioning. The first control cycle, in seconds; For the first The furnace temperature measured at each time point (or the model estimate in open-loop mode), in °C.

[0097] If the calculation result is negative, it indicates that natural cooling is required, and the power command is set to zero.

[0098] Furthermore, the calculated power value The power command is compared to the allowable power range of the heating power supply; if it exceeds this range, the boundary value is used. The power command is then subjected to limiting and smoothing. Each time stamp corresponds to a complete power reduction instruction sequence, which can be pre-generated and stored as a data table, or calculated and output point by point in real time.

[0099] During conformal cooling, the timer interrupt service routine inside the controller operates in the first control cycle. At intervals, the power value corresponding to the current moment is retrieved from the instruction sequence and sent to the power regulator of the heating power supply through the analog output channel or digital communication interface to drive its execution.

[0100] Step 43: While sending the power reduction command, maintain the inert gas pressure in the furnace at a preset slightly positive pressure value through a proportional regulating valve to prevent external air from being drawn into the furnace when the furnace temperature drops and the furnace contracts.

[0101] It should be noted that the controller activates the gas pressure control subroutine simultaneously with the power reduction command. This subroutine executes in a loop with a fourth control cycle (which can be independently set, e.g., 200 milliseconds). The controller reads the pressure value inside the furnace in real time through a pressure sensor, which is typically installed on the top or side wall of the furnace body, with a range of micro-pressure (e.g., -100Pa to +500Pa). The preset micro-positive pressure target value is a positive pressure value, such as +50Pa, to ensure that the pressure inside the furnace is always slightly higher than the external atmospheric pressure.

[0102] The controller inputs the deviation between the measured pressure and the preset micro-positive pressure target value into the proportional control algorithm (preferably P-regulation or PI-regulation in this embodiment) to calculate the opening adjustment amount of the proportional control valve. The proportional control valve is installed on the inert gas (such as nitrogen) supply line and receives a 4-20mA or 0-10V control signal from the controller to continuously adjust the valve opening, thereby controlling the gas flow rate into the furnace. The output signal of the regulation algorithm is sent to the valve actuator after digital-to-analog conversion, forming a closed-loop pressure control system.

[0103] As the furnace temperature drops, the volume of gas inside the furnace contracts. If the gas supply is not increased, the pressure will naturally decrease or even become negative. The proportional control valve automatically increases its opening based on the pressure deviation, supplying more inert gas to counteract the contraction effect and maintain the measured pressure near the preset slightly positive pressure target value. At the same time, the controller monitors whether the gas source pressure is normal. If the gas source pressure is too low to maintain the slightly positive pressure, a supplemental alarm is issued.

[0104] It can be seen that the automatic closed-loop control of the proportional regulating valve achieves dynamic stability of the furnace pressure, effectively counteracting the negative pressure trend caused by gas volume contraction during cooling. This prevents the intake of external oxygen-containing air at the source, protecting the preforms, graphite heating elements, and furnace inner wall from oxidative damage at high temperatures. This control is executed in parallel with power cooling without interference.

[0105] Step 44: After the furnace temperature drops below the preset safe storage temperature, a completion signal is issued and the inert gas pressure is maintained until the process is completed. During the power reduction command execution, the real-time reading will gradually decrease along the controllable cooling curve. When the real-time reading is detected to be below the preset safe storage temperature (e.g., 200°C) for the first time, and this is continuously confirmed for more than a second preset time (e.g., 10 seconds to prevent measurement fluctuations), the controller determines that the conformal cooling main process is complete.

[0106] At this point, the controller performs two operations. First, it sends a cooling completion signal via the human-machine interface, indicator lights, or host computer communication, indicating to the on-site operator that the furnace has entered a safe state and subsequent process handling (such as disassembly, inspection, or maintenance) can proceed. Second, it maintains the continued operation of the gas pressure control subroutine, with the proportional regulating valve continuing to maintain the furnace pressure near the preset slightly positive pressure target value, without immediately closing it upon reaching the temperature target. This holding state will continue until the operator explicitly indicates the process handling is complete and the system is ready to return to normal via the reset button or host computer command.

[0107] Meanwhile, the controller records key data throughout the conformal cooling process, including actual tracking deviation of the cooling curve, maximum pressure fluctuation, and total gas consumption, and generates an event report which is then uploaded to the SCADA system.

[0108] The system also includes one or more processors and memory.

[0109] The memory is used to store operable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, including the processes of the adaptive thermal coupling compensation-based glass fiber drawing furnace temperature control system of the foregoing embodiments, especially... Figure 1 The flowchart of the system is shown.

[0110] Other aspects disclosed in the embodiments of the present invention also propose a computer-readable medium for storing software including instructions executable by one or more computers, which, upon execution, cause the one or more computers to perform operations including the processes of the glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation of the foregoing embodiments, particularly... Figure 1 The flowchart of the system is shown.

[0111] It should be recognized that embodiments of the present invention may be implemented or carried out by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable storage medium.

[0112] The method can be implemented using standard programming techniques, including a non-transitory computer-readable storage medium configured with a computer program in the computer program, wherein the storage medium is configured such that the computer operates in a specific and predefined manner.

[0113] Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system; however, if required, the program can be implemented in assembly or machine language.

[0114] In any case, the language can be either compiled or interpreted.

[0115] Furthermore, for this purpose, the program can run on programmed application-specific integrated circuits.

[0116] The processes described herein (or variations and / or combinations thereof) can be executed under the control of one or more computer systems configured with executable instructions, and can be implemented by hardware or a combination thereof as code (e.g., executable instructions, one or more computer programs, or one or more applications) that commonly executes on one or more processors. The computer program includes a plurality of instructions executable by one or more processors.

[0117] Furthermore, the method can be implemented in any suitable computing platform, including but not limited to personal computers, minicomputers, mainframes, workstations, networked or distributed computing environments, standalone or integrated computer platforms, or in communication with charged particle tools or other imaging devices.

[0118] Various aspects of the present invention can be implemented in machine-readable code stored on a non-transitory storage medium or device, whether portable or integrated into a computing platform, such as a hard disk, optical read and / or write storage medium, RAM, ROM, etc., such that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the processes described herein.

[0119] Furthermore, machine-readable code, or parts thereof, can be transmitted via wired or wireless networks.

[0120] When such media includes instructions or programs that combine with a microprocessor or other data processor to implement the steps described above, the invention described herein includes these and other different types of non-transitory computer-readable storage media.

[0121] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A temperature control system for a glass fiber drawing furnace based on adaptive thermal coupling compensation, characterized in that, include: The aging parameter acquisition module is used to perform standard tests under no-load conditions, obtain the furnace heating time constant, and calculate the aging compensation coefficient. The temperature control command correction module is used to correct the heating power command during the wire drawing process according to the aging compensation coefficient, so as to offset the temperature field drift caused by the aging of the heating element. The abnormal operating condition identification module is used to monitor the circulating water pressure and power supply status in real time. When an abnormal signal is detected, it triggers an early warning and reads thermal inertial data from the SCADA historical database. The conformal cooling execution module is used to generate a controllable cooling curve based on the thermal inertia data under abnormal operating conditions, while controlling the inert gas flow rate to maintain a slight positive pressure inside the furnace to protect the materials inside the furnace.

2. The glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation according to claim 1, characterized in that, The aging parameter acquisition module includes: Before the wire drawing operation begins and there are no preforms in the furnace, confirm that the furnace temperature has dropped to the ambient temperature, and continuously inject inert gas into the furnace at the first gas flow rate to obtain a stable initial thermal environment under no-load conditions. In the stable initial thermal environment under no-load conditions, a preset step power command is applied to the heating element, and the complete temperature response data of the furnace body temperature rising from the initial temperature to the target temperature is recorded simultaneously. Based on the temperature response data, the current heating time constant of the furnace body in the current state is extracted at the time point corresponding to n% of the difference between the starting temperature and the target temperature. The current heating time constant is compared with the reference time constant stored in the SCADA system to calculate the aging compensation coefficient.

3. The glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation according to claim 2, characterized in that, The comparison is performed by calculating the aging compensation coefficient using a ratio or difference method.

4. The temperature control system for a glass fiber drawing furnace based on adaptive thermal coupling compensation according to claim 3, characterized in that, The temperature control command correction module includes: Read the current wire drawing speed setting and the current base power command of the main heating zone from the SCADA system; Multiply the aging compensation coefficient by the ratio of the wire drawing speed setting value to a preset speed reference value to obtain a dynamic power compensation value that varies with the wire drawing speed. The dynamic power compensation value is added to the current base power command to generate the final actual heating power command, which is then sent to the heating power supply for execution.

5. The glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation according to claim 4, characterized in that, The abnormal operating condition identification module includes: The current analog value of the circulating water pressure and the current on / off status signal of the power supply line are continuously acquired at the first sampling frequency. The current analog quantity value is compared with the preset pressure lower limit threshold, and it is determined whether the current on / off state signal is in a power-off state. When any condition is met, it is determined to be an abnormal working condition. Upon determining the abnormal operating condition, an audible and visual warning signal is immediately triggered, and a data read request is sent to the SCADA historical database to retrieve the most recently calibrated current heating time constant as thermal inertia data.

6. The glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation according to claim 5, characterized in that, The conformal cooling execution module includes: Using the thermal inertia data as the basis for calculating the furnace body heat loss rate, a controllable cooling curve with a target slope of the first cooling rate and without thermal stress impact is generated. The controllable cooling curve is converted into a power reduction command on a time series and continuously sent to the heating power supply in the first control cycle, so that the furnace temperature decreases along the controllable cooling curve. While sending the power reduction command, the pressure of the inert gas inside the furnace is maintained at a preset slightly positive pressure value through a proportional regulating valve to prevent external air from being drawn into the furnace when the furnace temperature drops and the furnace contracts. After the furnace temperature drops below the preset safe storage temperature, a completion signal is issued and the inert gas pressure is maintained until the process is completed.

7. The temperature control system for a glass fiber drawing furnace based on adaptive thermal coupling compensation according to claim 6, characterized in that, The generation of the controllable cooling curve includes: Read the current furnace heating time constant from the abnormal operating condition identification module; Determine the first cooling rate and the safe storage temperature, and ensure that the first cooling rate does not exceed the maximum thermal stress shock limit allowed by the furnace material; By combining thermal inertia data and the difference between the current furnace temperature and the ambient temperature, the heat loss rate of the furnace body under natural cooling conditions is estimated. Starting from the current furnace temperature, the temperature is linearly reduced to the safe storage temperature at the first cooling rate, resulting in a target curve of temperature change over time. If the rate at any moment during the linear reduction exceeds the stress limit, the local rate is automatically adjusted or a smooth transition section is introduced. Check whether the target curve meets the power output range of the heating power supply and the actual response capability of the furnace body; The final determined temperature-time relationship curve is used as the controllable cooling curve.

8. The glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation according to claim 7, characterized in that, Converting the controllable cooling curve into a power decrement command over a time series includes: The time range of the controllable cooling curve is divided into continuous time nodes with the first control cycle as the interval; Based on the controllable cooling curve, read the target furnace temperature value corresponding to each time point; Using the thermal dynamics model of the furnace body, combined with the target temperature change of adjacent nodes and the temperature difference between the current furnace temperature and the environment, the heating power required to make the furnace temperature drop along the curve is calculated. The calculated power value is limited to ensure that it is within the minimum and maximum power range allowed by the heating power supply, and the power commands of adjacent nodes are smoothed to prevent sudden power changes. Arrange each time node and its corresponding power command in chronological order to form a power reduction command sequence; During the conformal cooling process, corresponding power commands are sent to the heating power supply in sequence according to the first control cycle to achieve a controlled decrease in furnace temperature.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation as described in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the glass fiber drawing furnace temperature control system based on adaptive thermal coupling compensation as described in any one of claims 1 to 8.

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