Air-cooling control method and air-cooling system for low-temperature region intelligent control cooling

Abstract

This application relates to the field of quenching and cooling technology, and provides a method and system for intelligent control of air cooling in low-temperature regions. The method includes: S1: Real-time acquisition of the current temperature inside the furnace body detected by thermocouples; S2: Determining whether the current temperature is lower than a preset low-temperature threshold; S3: If the current temperature is lower than the preset low-temperature threshold, reducing the temperature by a preset fixed decrease; S4: Starting a timer; S5: After the timer finishes, acquiring the latest temperature detected by the thermocouples and calculating the temperature difference between the latest temperature and the temperature before the temperature was reduced; S6: If the temperature difference is less than or equal to 2℃, returning to step S3; S7: If the temperature difference exceeds 2℃, increasing the temperature by a preset pullback increment, resetting the timer, and then returning to step S4. The air cooling control method provided by this application can improve the surface hardness and overall quality of the workpiece.

Description

Technical Field

[0001] This application relates to the field of quenching and cooling technology, and more specifically, to an air-cooling control method and air-cooling system for intelligent control of cooling in low-temperature regions. Background Technology

[0002] Currently, in the quenching process, workpieces require rapid cooling after heat treatment to improve surface hardness and the depth of the hardened layer. However, as the workpiece cools to a low-temperature region, the heat transfer efficiency decreases due to the gradually diminishing temperature difference between the cooling medium and the workpiece surface, resulting in a significantly slower cooling effect. More importantly, traditional technologies generally believe that "the larger the airflow, the faster the cooling," neglecting the fact that the high-speed airflow itself generates heat by performing work on the workpiece surface. In the low-temperature region, the airflow impacting the workpiece surface converts some kinetic energy into heat, causing the workpiece surface temperature to rise instead of fall. This phenomenon, combined with the internal heat source still at a high temperature within the workpiece, causes the workpiece surface to heat up first and then cool down slowly, forming a small-scale aging process. This process thins the already formed hardened layer, directly reducing the surface hardness and overall quality of the workpiece. Furthermore, the cooling rate adjustment methods of existing air-cooling systems are relatively crude. Some systems achieve adjustable air-cooling speed by adjusting the fan speed using frequency converters, but such adjustments are mostly open-loop control or simple PID closed-loop control, lacking adaptive optimization capabilities for the special operating conditions in the low-temperature region. Summary of the Invention

[0003] This application aims to at least solve the technical problem in the related art that the traditional cooling method causes the hard layer to become thinner and the workpiece quality to decrease due to the work done by airflow at low temperatures.

[0004] To solve the above-mentioned technical problems, this application is implemented as follows: Firstly, this application provides an intelligent control method for air cooling in low-temperature areas, applied to an air cooling system. The air cooling system includes an insulated furnace body, a heat exchanger, an air-cooled motor, a proportional control valve, a thermocouple, a timer, and a PLC controller. The intelligent control method for air cooling in low-temperature areas includes the following steps executed by the PLC controller: S1: Real-time acquisition of the current temperature inside the insulated furnace body detected by the thermocouple; S2: Determination of whether the current temperature is lower than a preset low-temperature threshold; S3: When the current temperature is lower than the preset low-temperature threshold, sending a first control signal to the proportional control valve to reduce its opening by a preset fixed decrease; S4: Starting the timer to start timing; S5: After the timer finishes timing, acquiring the latest temperature detected by the thermocouple and calculating the temperature difference between the latest temperature and the temperature before reducing the opening; S6: If the temperature difference is less than or equal to 2℃, returning to step S3; S7: If the temperature difference exceeds 2℃, immediately sending a second control signal to the proportional control valve to increase its opening by a preset callback amplitude, resetting the timer, and then returning to step S4.

[0005] This application provides a method for intelligent air-cooling control in low-temperature regions. Through coordinated control methods including low-temperature detection, stepped airflow reduction, timing verification, temperature rise feedback, asymmetric correction, and fault tolerance, it achieves adaptive and precise adjustment of airflow during the low-temperature cooling stage. This method not only effectively suppresses the problems of workpiece surface tempering and hardness layer thinning caused by airflow work in traditional air-cooling methods at low temperatures, improving workpiece surface hardness and overall quality, but also reduces the ineffective energy consumption of the air-cooling system, achieving energy saving and consumption reduction.

[0006] Secondly, this application proposes an intelligent controlled cooling air-cooling system for low-temperature areas, used to execute the air-cooling control method for intelligent controlled cooling in low-temperature areas described above. The air-cooling system includes: a heat-insulating furnace body for accommodating workpieces and providing space for heat treatment; air-cooling pipelines connected to the heat-insulating furnace body to form a gas circulation loop; a heat exchanger installed on the air-cooling pipelines for cooling the circulating gas; an air-cooled motor driving an impeller to rotate, used to drive the gas to circulate within the air-cooling pipelines and the heat-insulating furnace body; a proportional regulating valve installed on the air-cooling pipelines for regulating the gas flow rate in the circulation loop; a thermocouple installed on the heat-insulating furnace body for detecting the temperature inside the furnace body; a timer for timing; and a PLC controller electrically connected to the thermocouples, proportional regulating valve, timer, and air-cooled motor, configured to execute the air-cooling control method described above.

[0007] The air-cooling system for intelligent control cooling in low-temperature regions provided in this application has all the beneficial effects of the air-cooling control method for intelligent control cooling in low-temperature regions used to implement the above scheme, and will not be elaborated here.

[0008] Additional aspects and advantages of this application will become apparent in the following description or may be learned by practice of this application. Attached Figure Description

[0009] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of an air-cooled system for intelligent control cooling in low-temperature regions according to an embodiment of this application; Figure 2 This is one of the flowcharts for an air-cooling control method for intelligent control cooling in low-temperature regions according to an embodiment of this application; Figure 3 This is a second flowchart of an embodiment of the air-cooling control method for intelligent control cooling in low-temperature regions according to this application.

[0010] in, Figures 1 to 3 The correspondence between the reference numerals and component names in the attached drawings is as follows: The system includes a 100°C low-temperature zone intelligent control cooling air-cooling system, consisting of: 1. PLC controller, 2. Temperature control instrument, 3. Thermocouple, 4. Proportional regulating valve, 5. Air-cooled motor, 6. Heat exchanger, 7. Insulated furnace body, 8. Air-cooled pipeline, 9. Compensating wire, 10. First communication line, 11. Second communication line, and 12. Timer. Detailed Implementation

[0011] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0012] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0013] The following reference Figures 1 to 3 This application describes a method and system for intelligent control of air cooling in low-temperature regions, based on some embodiments of the present application.

[0014] According to the first aspect of this application, Figure 1 and Figure 2 As shown in the figure, one embodiment of this application provides an air-cooling control method for intelligent control of cooling in low-temperature areas, which is applied to an air-cooling system. The air-cooling system includes an insulated furnace body, air-cooled pipelines, a heat exchanger, an air-cooled motor, a proportional regulating valve, a thermocouple, a timer, and a PLC controller.

[0015] Specifically, such as Figure 1 As shown, the intelligent controlled air-cooling system for low-temperature areas includes an insulated furnace body, air-cooled piping, a heat exchanger, an air-cooled motor, a proportional control valve, thermocouples, a timer, and a PLC controller. The insulated furnace body houses the workpiece and provides space for heat treatment. The air-cooled piping connects to the furnace body, forming a gas circulation loop. The heat exchanger, located on the air-cooled piping, cools the circulating gas. The air-cooled motor drives an impeller to rotate, propelling the gas through the air-cooled piping and within the furnace body. The proportional control valve, located on the air-cooled piping, regulates the gas flow rate in the circulation loop. The thermocouples are mounted on the furnace body to detect the internal temperature. The timer is used for timing. The PLC controller is electrically connected to the thermocouples, proportional control valve, timer, and air-cooled motor, and executes the air-cooling control method.

[0016] like Figure 2As shown, the air-cooling control method for intelligent control of low-temperature zone cooling proposed in the embodiments of this application includes the following steps executed by a PLC controller: S1: Real-time acquisition of the current temperature inside the insulation furnace detected by the thermocouple; S2: Determine whether the current temperature is lower than the preset low temperature threshold; S3: When the current temperature is lower than the preset low temperature threshold, send a first control signal to the proportional control valve to reduce its opening by a preset fixed decrease. S4: Start the timer to begin timing; S5: After the timer finishes counting down, obtain the latest temperature detected by the thermocouple and calculate the temperature difference between the latest temperature and the temperature before the opening degree was reduced; S6: If the temperature difference is less than or equal to 2℃, then return to step S3; S7: If the temperature difference exceeds 2℃, immediately send a second control signal to the proportional control valve to increase its opening by a preset callback amplitude, reset the timer, and then return to step S4.

[0017] Specifically, such as Figure 2As shown, in step S1, the PLC controller continuously or periodically collects real-time temperature signals inside the heat-insulating furnace via electrically connected thermocouples. The thermocouples convert the temperature into electrical signals and transmit them to the PLC as the basis for subsequent judgments. In step S2, the PLC controller compares the current temperature obtained in step S1 with a pre-stored low-temperature threshold. This low-temperature threshold is a critical temperature point set according to the material's heat treatment process characteristics. That is, when the workpiece temperature is higher than this threshold, the workpiece is still in a high-temperature state with high heat transfer efficiency, allowing for rapid cooling with a large air volume; when it is lower than this threshold, the workpiece enters a low-temperature sensitive zone, significantly increasing the hazards of airflow work, requiring the activation of intelligent control. In step S3, when step S2 determines that the current temperature is lower than the low-temperature threshold, the PLC controller sends a first control signal to the proportional control valve, driving the proportional control valve to reduce its opening by a preset fixed decrease. Reducing the airflow opening means decreasing the cross-sectional area of ​​the gas flow in the air-cooled pipeline. With the air-cooled motor speed remaining constant or decreasing in tandem, the flow rate and velocity of the circulating gas decrease accordingly. This actively reduces the impact kinetic energy of the high-speed airflow on the workpiece surface, thereby reducing the heat generated by the airflow and preventing tempering of the workpiece surface due to additional heating. In step S4, the PLC controller starts a timer immediately upon issuing the command to reduce the airflow opening. The timer's duration is preset based on parameters such as the system's thermal inertia, furnace volume, and gas circulation cycle. Its function is to provide an observation window, allowing the system sufficient time to observe the actual temperature change trend inside the furnace after reducing the airflow, avoiding misjudgments due to instantaneous fluctuations in the temperature signal. In step S5, after the timer finishes counting, the PLC controller reads the latest temperature detected by the thermocouple again and calculates the difference between this latest temperature and the reference temperature recorded before reducing the airflow opening in step S3. The temperature difference directly reflects the actual impact of the reduced airflow on the cooling effect: a negative or small positive temperature difference indicates that the temperature continues to decrease slowly or remains basically stable after reducing the airflow, indicating that the current airflow can still meet the heat exchange requirements; a large positive temperature difference indicates that the temperature rises instead of falling after reducing the airflow, indicating that the airflow speed is too low to effectively remove the heat continuously released from the inside of the workpiece, causing the surface temperature to rise again; a negative temperature difference indicates that the cooling is too fast, but in this scheme, due to the active reduction of airflow, the probability of a negative temperature difference is low. In step S6, if the temperature difference calculated in step S5 is less than or equal to 2℃, it indicates that the workpiece temperature has not risen significantly after the reduction of airflow, and may even have slightly decreased, meaning that the current airflow has neither caused harmful airflow heating nor has maintained a certain heat exchange capacity. At this time, the system determines that the current airflow still has room to be further reduced, so it returns to step S3 to reduce the opening of the proportional regulating valve again and enter the next round of testing. This cycle repeats, and the system gradually approaches the optimal airflow balance point under the current operating conditions in a step-by-step manner.In step S7, if the temperature difference calculated in step S5 exceeds 2°C, it indicates that the reduction in airflow was excessive, and the airflow speed is insufficient to remove the heat continuously conducted from the inside of the workpiece, causing the workpiece surface temperature to rise again, resulting in the "backfire" phenomenon in the low-temperature zone of traditional air cooling. At this time, the system immediately takes reverse adjustment measures: the PLC controller sends a second control signal to the proportional control valve, increasing its opening by a preset pullback margin, while resetting the timer, and then returning to step S4. The key here is that the pullback margin is smaller than the previous reduction margin, so that the overall opening shows a step-like convergence trend, rather than oscillating back and forth at a fixed point. After several trials, pullbacks, and further trials, the system can automatically stabilize near the optimal opening, achieving stable and efficient cooling in the low-temperature zone.

[0018] Thus, the air-cooling control method for intelligent control of low-temperature cooling provided in this application achieves intelligent control of the air-cooling system through real-time temperature monitoring, low-temperature threshold judgment, step-by-step active airflow reduction, timing verification, temperature difference calculation, and feedback adjustment based on temperature difference results. The core of this method lies in ensuring rapid cooling during the high-temperature stage, at which point the proportional control valve is fully open. During the low-temperature stage, it automatically switches to an intelligent mode of trial, verification, and correction. By gradually reducing and automatically finding the optimal airflow balance point that effectively removes internal heat from the workpiece without causing harmful heating due to high-speed airflow impact, it avoids the problems of surface tempering and thinning of the hardened layer on the workpiece caused by airflow work in the low-temperature zone, as seen in traditional constant airflow cooling, thus ensuring the surface hardness and overall quality of the workpiece. Simultaneously, by actively reducing unnecessary airflow, it reduces the energy consumption of the air-cooling motor and gas circulation, achieving energy saving and consumption reduction. Moreover, the entire adjustment process is automatically completed by the PLC without manual intervention, improving the automation level and stability of the cooling process.

[0019] Compared with existing technologies, the air-cooling control method for intelligent control of low-temperature cooling provided in this application has the following advantages: First, it solves the technical problem of surface tempering of workpieces caused by airflow work in the low-temperature zone in traditional air cooling. Existing technologies generally believe that the larger the airflow, the faster the cooling, ignoring the kinetic energy heating effect of high-speed airflow on the workpiece surface. This application reduces harmful work by actively reducing the airflow, fundamentally protecting the thickness of the hardened layer. Second, unlike the simple PID tracking of preset curves or open-loop speed regulation in existing technologies, this application's control method does not rely on preset cooling curves. Instead, it uses real-time temperature feedback, and after each fixed reduction, it observes the temperature difference change by timing: if the temperature difference is small, it continues to reduce; if the temperature difference is large, it adjusts appropriately, allowing the system to automatically converge to the optimal equilibrium point, adapting to changes in different workpieces and furnace conditions. Third, it achieves a balance between cooling efficiency and workpiece quality in the low-temperature zone. This method, while ensuring no surface temperature rise, increases the effective contact area between the gas and the workpiece by gradually reducing the airflow, thereby maintaining or even improving the heat transfer efficiency in the low-temperature zone. Fourth, this method also includes an exception handling mechanism that enters an observation period after multiple consecutive callback triggers to prevent the system from oscillating under extreme operating conditions. By keeping the high-temperature segment fully open and intelligently adjusting the low-temperature segment, the cooling process is automatically switched, improving the intelligence level of the equipment.

[0020] In some embodiments, optionally, such as Figure 2 As shown, in step S2, the preset low temperature threshold is 300℃.

[0021] Specifically, such as Figure 2 As shown, by setting the preset low temperature threshold to 300℃, this application can accurately distinguish between the high temperature rapid cooling stage and the low temperature fine control stage, ensuring that intelligent air volume adjustment is activated at the optimal time. This not only guarantees the overall cooling efficiency but also minimizes the negative impact of airflow work in the low temperature zone on the workpiece quality, thus improving the process adaptability of this method to different materials and workpieces.

[0022] In some embodiments, optionally, such as Figure 2 As shown, in step S3, the preset fixed reduction is 5% to 15% of the current opening of the proportional control valve.

[0023] Specifically, such as Figure 2 As shown, by setting the preset fixed reduction to 5% to 15% of the current opening of the proportional control valve, this application can avoid system oscillation caused by over-adjustment while ensuring that each adjustment produces an effective temperature response. At the same time, it achieves adaptive adaptation to air-cooled systems of different specifications, improving cooling efficiency, system stability and process versatility.

[0024] In practical applications, the preset fixed reduction can be set to 5%, 8%, 10% or 15% of the current opening of the proportional control valve. The specific choice can be made according to the actual usage situation, and will not be listed here.

[0025] In some embodiments, optionally, such as Figure 2 As shown, in step S4, the timing duration is set to 30 to 120 seconds.

[0026] Specifically, such as Figure 2 As shown, by setting the timer duration to 30 to 120 seconds, the accuracy and stability of temperature detection are ensured, avoiding misjudgments caused by insufficient gas circulation or temperature fluctuations. This also ensures the response speed of the control system, enabling the low-temperature intelligent cooling process to adapt to the optimal airflow balance point within a reasonable time window, thus balancing control precision and process efficiency.

[0027] In practical applications, the timing duration can be set to 30 seconds, 50 seconds, 80 seconds, 100 seconds, or 120 seconds, depending on the specific usage situation. These options will not be listed here.

[0028] In some embodiments, optionally, such as Figure 2 As shown, in step S7, the preset callback amplitude is 30% to 70% of the preset fixed reduction amplitude.

[0029] Specifically, such as Figure 2 As shown, if the pullback amplitude equals the fixed reduction amplitude, the system opening will return to its position before the last reduction. Then, executing step S3 again will reduce the opening by the same amplitude, causing the opening to oscillate around the same value, making it difficult to detect the optimal balance point. By setting the pullback amplitude to 30% to 70% of the preset fixed reduction amplitude, a stepped control with more reductions and less pullbacks is achieved. This effectively avoids infinite oscillations in the system during the search for the optimal airflow balance point, speeds up the search, improves the stability and efficiency of the low-temperature intelligent control program, and ensures a smooth transition in the cooling process.

[0030] In practical applications, the preset callback range can be set to 30%, 40%, 50% or 70% of the preset fixed reduction range. The choice can be made according to the specific actual use case, and will not be listed here.

[0031] In some embodiments, optionally, such as Figure 3 As shown, the air-cooling control method for intelligent control of cooling in low-temperature areas also includes an abnormal handling step, specifically: when step S7 is executed three times in a row, the PLC controller suspends the execution of step S3 and enters an observation period. During the observation period, the temperature change of the thermocouple is monitored until the temperature starts to drop continuously, and then step S3 is resumed.

[0032] Specifically, such as Figure 3 As shown, the air-cooling control method for intelligent control of cooling in low-temperature areas also includes an anomaly handling step S8. Specifically, step S8 involves the PLC controller pausing step S3 after three consecutive executions of step S7, entering an observation period, and monitoring the temperature change of the thermocouples during this period. Once a sustained temperature drop is detected, step S3 is resumed. This anomaly handling step, which pauses airflow after three consecutive callbacks and enters an observation period until the temperature resumes its sustained drop, effectively prevents the system from falling into ineffective oscillations under abnormal operating conditions, avoids adverse effects on workpiece quality, improves the stability, fault tolerance, and adaptability of the low-temperature intelligent control program under various complex operating conditions, and ensures that the cooling process remains controllable and stable.

[0033] In some embodiments, optionally, such as Figure 2 As shown, in step S3, when the opening of the proportional control valve is reduced, a speed reduction control signal is simultaneously sent to the air-cooled motor; in step S7, when the opening of the proportional control valve is increased, a speed increase control signal is simultaneously sent to the air-cooled motor.

[0034] Specifically, such as Figure 2 As shown, by simultaneously reducing the motor speed through the frequency converter when the opening degree is reduced and simultaneously increasing the motor speed through the frequency converter when the opening degree is increased, the coordinated control of the proportional control valve and the air-cooled motor is realized. This not only further improves the energy utilization efficiency in the low-temperature intelligent control process and reduces unnecessary throttling losses, but also accelerates the response speed of the back-down suppression of temperature rise, and improves the operational stability of the gas circulation system, achieving multiple beneficial effects of energy saving, high efficiency, and stability.

[0035] In some embodiments, optionally, such as Figure 1 and Figure 2 As shown, the air-cooling system also includes air-cooling pipes. The interior of the insulation furnace is filled with inert gas. The air-cooled motor drives the impeller to rotate, so that the inert gas circulates in the air-cooling pipes and the insulation furnace.

[0036] Specifically, such as Figure 1 As shown, the air-cooling system also includes air-cooling pipes. The interior of the insulation furnace is filled with inert gas, and an air-cooled motor drives an impeller to rotate, causing the inert gas to circulate within the air-cooling pipes and the insulation furnace. By setting up air-cooling pipes and filling the insulation furnace with inert gas, this application uses pure inert gas as the heat exchange medium. While ensuring that the workpiece surface does not oxidize or become contaminated, it achieves efficient heat transfer and circulating cooling, providing a stable and controllable gas flow environment for low-temperature intelligent control methods, further improving cooling quality and process safety.

[0037] In specific applications, the inert gas can be nitrogen, argon, or helium, etc., and can be selected according to the specific application. They will not be listed here.

[0038] In some embodiments, optionally, such as Figure 2 As shown, during the entire cooling process, the PLC controller continuously monitors the temperature inside the insulation furnace through thermocouples, and controls the proportional regulating valve to remain fully open when the current temperature is higher than the preset low temperature threshold.

[0039] Specifically, such as Figure 2 As shown, by keeping the proportional regulating valve fully open during the high-temperature stage, the maximum airflow is fully utilized to achieve rapid cooling while the workpiece is still in the high-temperature range, effectively shortening the overall cooling cycle and improving production efficiency. At the same time, when the temperature enters the low-temperature range, the system automatically triggers the low-temperature intelligent control program, realizing adaptive and precise adjustment of the airflow during the low-temperature cooling stage, ensuring both cooling efficiency and workpiece quality, and achieving automation and intelligence of the entire cooling process.

[0040] According to the second aspect of this application, such as Figure 1 As shown, embodiments of this application also propose a low-temperature zone intelligent controlled cooling air-cooling system 100, used to execute the low-temperature zone intelligent controlled cooling air-cooling control method of the above embodiments. The low-temperature zone intelligent controlled cooling air-cooling system 100 includes: a heat-insulating furnace body 7, which is used to accommodate workpieces and provide space for heat treatment; an air-cooling pipeline 8, which is connected to the heat-insulating furnace body 7 to form a gas circulation loop; a heat exchanger 6, which is disposed on the air-cooling pipeline 8 and used to cool the circulating gas; and an air-cooled motor 5, which drives an impeller. Rotation is used to drive the gas to circulate within the air-cooled pipe 8 and the insulation furnace body 7; a proportional regulating valve 4 is installed on the air-cooled pipe 8 to regulate the gas flow rate in the circulation loop; a thermocouple 3 is installed on the insulation furnace body 7 to detect the temperature inside the insulation furnace body 7; a timer 12 is used for timing; and a PLC controller 1 is electrically connected to the thermocouple 3, the proportional regulating valve 4, the timer 12, and the air-cooled motor 5, respectively, and the PLC controller 1 is configured to execute the air-cooling control method of the above embodiment.

[0041] Specifically, such as Figure 1 and Figure 2As shown, the heat-insulating furnace body 7 adopts a sealed container structure, with an internal main chamber for accommodating workpieces and performing heat treatment. The furnace body is typically a double-layer water-cooled structure, with circulating cooling water flowing through the outer layer to prevent overheating of the outer wall and protect operators and surrounding equipment. The air-cooled piping 8 includes an inlet pipe and a return pipe, which are sealed to the inlet and outlet of the heat-insulating furnace body 7, respectively, forming a closed gas circulation loop with the furnace interior. The heat exchanger 6 is specifically a tube-fin heat exchanger or a plate heat exchanger, with cooling water flowing through it. When high-temperature gas flows through the heat exchanger 6, it exchanges heat with the cooling water, transferring heat to the cooling water and being cooled. The heat exchanger 6 is installed in series in the return section of the air-cooled piping 8 to ensure that the gas entering the impeller is sufficiently cooled. The air-cooled motor 5 can be a variable frequency speed-regulating motor, which drives the impeller to rotate at high speed. The impeller performs work on the gas, generating a pressure difference that drives the gas to circulate between the piping and the furnace body. The proportional control valve 4 can be a butterfly valve or ball valve controlled electrically or pneumatically. It is installed in the air inlet section of the air-cooled pipeline 8 and adjusts the valve core opening by receiving control signals sent by the PLC controller 1, thereby changing the gas flow cross-sectional area and achieving precise and continuous regulation of the circulating gas flow. Thermocouple 3 has its temperature measuring end inserted into the heat preservation furnace body 7 and is arranged close to the workpiece. It is used to collect the furnace temperature in real time and convert it into an electrical signal to be transmitted to the PLC controller 1. Timer 12 can be an independent hardware timing module or a software timer integrated into the PLC controller 1. It is used to provide accurate time measurement function and provide a time reference for the timing wait in step S4. The PLC controller 1 is the control core of the entire system. Its input end is connected to the thermocouple 3 through the compensation wire 9 and to the temperature control instrument 2 through the first communication line 10 to receive temperature signals. Its output end is connected to the actuator of the proportional control valve 4, the frequency converter of the air-cooled motor 5, and the control end of the timer 12 through the second communication line 11. When the cooling process reaches a low temperature range, such as below 300°C, the PLC controller 1 adjusts the opening of the proportional control valve 4 according to the temperature drop, thereby adjusting the airflow at the outlet and controlling the gas flow rate within the system to achieve the best cooling effect.

[0042] Specifically, in the quenching process, the heat-treated workpiece needs to be cooled extremely rapidly to increase the surface hardness of the metal. The thicker the hardness layer, the better the quality of the workpiece. However, when the workpiece is cooled to a low temperature, such as below 300°C, the temperature difference between the cooling medium and the workpiece surface becomes smaller and smaller, resulting in a gradual decrease in the efficiency of heat conduction and a slower cooling effect. Moreover, the high-speed airflow itself does work on the workpiece surface, causing the surface temperature to rise. Combined with the high internal temperature of the workpiece, the workpiece surface will first heat up and then slowly cool down over a long period of time, forming a small aging process. This process thins the hardness layer that was originally formed on the workpiece, thereby reducing the quality of the workpiece.

[0043] To address the aforementioned technical problems, this application provides a low-temperature zone intelligent controlled cooling air-cooling system 100, including a PLC controller 1, a temperature control instrument 2, a timer 12, a thermocouple 3, an air-cooled motor 5 and impeller, a proportional regulating valve 4, air-cooled pipelines 8, a heat exchanger 6, and a heat-insulating furnace body 7. The specific control method of the low-temperature zone intelligent controlled cooling air-cooling system 100 is as follows: After the workpiece undergoes heat treatment, it enters the cooling stage. The heat-insulating furnace body 7 is filled with inert gas for cooling, and the pressure is adjusted according to the workpiece process. The air-cooled motor 5 is started, and the cooling process begins. Temperature feedback within the heat-insulating furnace body 7 is transmitted to the temperature control instrument 2 via the thermocouple 3. The temperature from the temperature control instrument 2 is transmitted to the PLC controller 1 via the first communication line 10. When the temperature is lower than the preset value in the PLC controller 1, it indicates that the system has entered the low-temperature zone, and the low-temperature intelligent control program is activated. The program reduces the opening of proportional control valve 4 by a fixed amount, then starts timer 12. When timer 12 finishes counting and the temperature of thermocouple 3 has not risen, PLC controller 1 resets timer 12 and continues to reduce the opening of proportional control valve 4, repeating the previous step in a cyclical manner. If the temperature of thermocouple 3 rises during the counting process, PLC controller 1 interrupts the original program, immediately resets timer 12, increases the opening of proportional control valve 4, and then resumes the original program. If three consecutive interruptions occur, the program pauses the frequency reduction process and enters an observation period until a cooling process occurs. This achieves stable cooling, improves workpiece quality, and saves energy. The condition that timer 12 finishes counting and the temperature of thermocouple 3 has not risen means that after timer 12 finishes counting, the latest temperature detected by thermocouple 3 is obtained, and the temperature difference between the latest temperature and the temperature before the opening was reduced is calculated, with the temperature difference being less than or equal to 2℃. The temperature rise of thermocouple 3 during the timing process refers to the acquisition of the latest temperature detected by thermocouple 3 after the timing of timer 12 ends, and the calculation of the temperature difference between the latest temperature and the temperature before the opening degree is reduced, and the temperature difference exceeds 2℃.

[0044] Specifically, the process of the air-cooled control method for intelligent cooling in low-temperature zones is as follows: The PLC acquires the furnace temperature detected by thermocouple 3 in real time and compares it with the preset low-temperature threshold. When the temperature enters the low-temperature zone, the system automatically triggers the low-temperature intelligent control program, realizing accurate judgment and automatic intervention for the differentiated cooling needs of traditional "high temperature and high speed, low temperature and low speed," avoiding the lag and arbitrariness of manual judgment. Specifically, the PLC sends a control signal to the proportional regulating valve 4, reducing its opening by a preset fixed decrease, and simultaneously starts timer 12 to observe the timing from 30 to 120 seconds. After the timing ends, the system calculates the temperature difference before and after cooling. If the temperature difference is less than or equal to 2℃, it indicates that the reduction in air volume has neither caused a temperature rise nor achieved effective heat exchange. Then, the system continues to execute the next reduction in opening, causing the air volume to decrease in a stepwise manner, gradually approaching the optimal air volume balance point under the current operating conditions. When the temperature difference exceeds 2℃ after cooling, it indicates that the airflow has been excessively reduced, leading to insufficient heat exchange capacity and heat accumulation inside the workpiece causing surface reheating. In this case, the system immediately sends a second control signal to the proportional control valve 4, increasing its opening by a preset correction margin. This method employs an asymmetric correction approach of "more reduction, less recovery," resulting in a stepped convergence trend in the system opening, effectively avoiding oscillations near the optimal opening and improving the system's rapid stability. In abnormal handling situations, when temperature rise correction is triggered multiple times consecutively, the PLC automatically pauses the frequency reduction test and enters an observation period, continuously monitoring temperature changes until the temperature begins to decrease again before resuming the stepped airflow reduction operation.

[0045] The beneficial effects of this invention are as follows: When the temperature reaches below 300°C, adjusting the opening of the proportional regulating valve 4 controls the gas flow rate within the system. First, this reduces the air volume, thereby reducing the amount of work done by the high-speed airflow on the workpiece surface and reducing the heat generated. Second, when the high-speed airflow impacts the workpiece surface, the airflow forms a large deflection angle. When the airflow speed is reduced, the deflection angle decreases, thereby increasing the contact area with the workpiece. According to the formula Q = (kAΔT) / d, where Q is the heat transfer rate (unit: W), and A is the heat transfer area perpendicular to the heat flow direction (unit: m²). 2 ΔT is the temperature difference along the heat flow direction (unit: K), and d is the heat transfer distance (unit: m). Increasing the contact area A increases the thermal conductivity Q, thus further increasing the overall thermal conductivity. This prevents the surface temperature from increasing due to the work done by the airflow, and the internal temperature decreases steadily due to the increased thermal conductivity. This prevents the workpiece surface temperature from rising, thus avoiding a thinning of the workpiece's hardness layer and improving workpiece quality. Furthermore, reducing the work done by the high-speed airflow also reduces energy waste, resulting in energy savings.

[0046] In the description of this application, the term "multiple" refers to two or more. Unless otherwise expressly defined, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0047] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for intelligent control of air cooling in low-temperature regions, characterized in that, This method is applied to an air-cooled system, which includes an insulated furnace body, a heat exchanger, an air-cooled motor, a proportional control valve, a thermocouple, a timer, and a PLC controller. The air-cooled control method for intelligent control of cooling in low-temperature areas includes the following steps executed by the PLC controller: S1: Real-time acquisition of the current temperature inside the heat-insulating furnace detected by the thermocouple; S2: Determine whether the current temperature is lower than a preset low temperature threshold; S3: When the current temperature is lower than the preset low temperature threshold, send a first control signal to the proportional control valve to reduce its opening by a preset fixed decrease. S4: Start the timer to begin timing; S5: After the timer finishes counting down, obtain the latest temperature detected by the thermocouple and calculate the temperature difference between the latest temperature and the temperature before the opening degree was reduced; S6: If the temperature difference is less than or equal to 2°C, then return to step S3; S7: If the temperature difference exceeds 2°C, immediately send a second control signal to the proportional regulating valve to increase its opening by a preset callback amplitude, reset the timer, and then return to step S4.

2. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, In step S2, the preset low temperature threshold is 300°C.

3. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, In step S3, the preset fixed reduction is 5% to 15% of the current opening of the proportional control valve.

4. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, In step S4, the duration of the timer is set to 30 to 120 seconds.

5. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, In step S7, the preset callback amplitude is 30% to 70% of the preset fixed reduction amplitude.

6. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, The intelligent control cooling method for low-temperature regions also includes anomaly handling steps, specifically: When step S7 is executed three times consecutively, the PLC controller pauses the execution of step S3 and enters an observation period. During the observation period, the temperature change of the thermocouple is monitored until the temperature starts to drop continuously, and then the execution of step S3 is resumed.

7. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, In step S3, when the opening of the proportional control valve is reduced, a speed reduction control signal is simultaneously sent to the air-cooled motor; in step S7, when the opening of the proportional control valve is increased, a speed increase control signal is simultaneously sent to the air-cooled motor.

8. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, The air-cooling system also includes air-cooling pipes. The interior of the heat-insulating furnace is filled with inert gas. The air-cooling motor drives the impeller to rotate, so that the inert gas circulates in the air-cooling pipes and the heat-insulating furnace.

9. The air-cooling control method for intelligent control of cooling in low-temperature regions according to claim 1, characterized in that, Throughout the cooling process, the PLC controller continuously monitors the temperature inside the insulation furnace via the thermocouple, and controls the proportional regulating valve to remain fully open when the current temperature is higher than the preset low temperature threshold.

10. A low-temperature region intelligent controlled cooling air-cooling system, used to execute the low-temperature region intelligent controlled cooling air-cooling control method according to any one of claims 1 to 9, characterized in that, The air-cooling system for intelligent control of cooling in the low-temperature region includes: A heat-insulating furnace body, which serves to accommodate workpieces and provide space for heat treatment; Air-cooled piping is connected to the insulation furnace body to form a gas circulation loop; A heat exchanger is installed on the air-cooled pipeline for cooling the circulating gas; An air-cooled motor drives an impeller to rotate, which in turn drives the gas to circulate in the air-cooled pipeline and the heat preservation furnace. A proportional regulating valve is provided on the air-cooled pipeline and is used to regulate the gas flow rate in the circulation loop; A thermocouple, which is installed on the insulation furnace body, is used to detect the temperature inside the insulation furnace body; A timer, used for timing; A PLC controller is electrically connected to the thermocouple, the proportional control valve, the timer, and the air-cooled motor, respectively, and the PLC controller is configured to perform the air-cooling control method according to any one of claims 1 to 9.

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