An automatic oil return mold temperature controller system and method with online oil supplement

Abstract

This invention discloses an automatic oil return mold temperature controller system and method with online oil replenishment, belonging to the technical field of industrial temperature control equipment. The technical problem to be solved is that existing mold temperature controllers cannot replenish oil online when the expansion tank is under pressure and temperature, requiring shutdown to depressurize and cool down before replenishing oil, resulting in production interruptions, significant heat and pressurizing medium losses, and the inability to recover leaked medium from the pressure plate in the non-closed loop, coupled with a lack of abnormal leakage safety protection, leading to low production efficiency and insufficient operational safety. The key technical solution is that the system consists of an oil return tank, a pressurizing pump, an expansion tank, a main circulation loop, and monitoring interlock components. The pressurizing pump pressurizes atmospheric pressure heat transfer oil and replenishes it to the pressurized expansion tank without shutting down the machine. Leaking oil from the pressure plate is recovered to the oil return tank via a vacuum system, forming a closed-loop circulation. Multiple temperature and pressure sensors monitor in real time, and a PID algorithm enables precise automatic oil replenishment. In case of abnormal leakage, the pressure plate oil circuit is cut off and the system switches to internal circulation, effectively ensuring production continuity and equipment safety.

Description

Technical Field

[0001] This invention belongs to the field of industrial temperature control equipment technology, specifically relating to an automatic oil return mold temperature controller system and method with online oil replenishment capability. Background Technology

[0002] A typical mold temperature controller mainly consists of a heating system, a cooling system, a pressurization system, an expansion tank, a circulating pump, and a control system. The heating system regulates the temperature of the heat transfer oil medium through components such as electric heaters; the cooling system cools the medium through cold water circulation; the pressurization system and expansion tank store the liquid medium participating in the circulation and establish system operating pressure within the tank; the circulating pump delivers the liquid medium to the press and other actuators connected to the mold temperature controller, ensuring a constant temperature and pressure supply within the press plates; and the control system, as the core unit, ensures the stability and control accuracy of the equipment operation through real-time monitoring of parameters such as temperature and pressure.

[0003] Although mold temperature controllers are widely used in industry, existing technologies still have many insurmountable defects and shortcomings. When connected to a fully closed-loop actuator, the pressurized and heated heat transfer oil medium output by the mold temperature controller can completely flow back to the oil tank after passing through the actuator, enabling continuous and uninterrupted operation. However, when the actuator is not a fully closed loop, some of the pressurized and heated heat transfer oil output by the mold temperature controller will be lost after passing through the actuator, resulting in a continuous decrease in the medium flowing back to the mold temperature controller's oil tank. Since the oil tank / expansion tank of existing mold temperature controllers is in a pressurized and heated operating state, it is impossible to directly replenish the liquid medium from the outside, ultimately leading to insufficient medium and the actuator failing to operate continuously.

[0004] To address the aforementioned media loss issue, existing oil replenishment methods require the machine to be shut down first, the pressure in the mold temperature controller's oil tank to atmospheric pressure, and the media temperature to room temperature before the valve can be opened to replenish the media externally. After replenishment, the mold temperature controller and actuator unit are restarted. This replenishment method has three major drawbacks: First, it causes discontinuous operation of the actuator unit, resulting in intermittent production and severely impacting production efficiency. Second, the frequent shutdown-restart process leads to significant ineffective losses of heat energy and pressurizing media (such as nitrogen), substantially increasing production and operating costs. Third, leaked media from actuator units such as pressure plates cannot be recovered and reused in a closed-loop system, further exacerbating media loss and amplifying the impact of the aforementioned drawbacks.

[0005] Currently, there are existing technical solutions for the oil replenishment function of mold temperature controllers. For example, Chinese patent CN210718085U discloses an oil temperature controller with automatic oil replenishment function, and Chinese patent CN209246390U discloses a heat-conducting oil heater that can automatically replenish and drain oil. Other related patents disclose control strategies for medium recovery and oil replenishment of mold temperature controllers. However, none of the above-mentioned existing technologies have solved the core problem of online oil replenishment without stopping the machine under high temperature and high pressure conditions. They cannot adapt to the continuous production needs of non-closed loop execution units, nor have they formed a complete closed-loop system of leakage medium recovery and online oil replenishment. They still have obvious shortcomings in terms of system operation continuity, production efficiency improvement, energy consumption and cost control.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] In order to solve the above-mentioned technical problems in the prior art, the present invention provides an automatic oil return mold temperature controller system and method that can replenish oil online, which solves the problem that the expansion tank of the mold temperature controller cannot be directly replenished when it is pressurized and heated, and the medium must be replenished after the machine is stopped to depressurize and cool down to room temperature, resulting in production interruption, intermittent operation and low production efficiency.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: In the first aspect, an automatic oil return mold temperature controller system capable of online oil replenishment includes: an oil return tank, a pressure pump, an expansion tank, a circulation pump, a heater, a pressure plate, a cooler, a third pressure detection sensor, and a control system; The expansion tank, circulating pump, heater, pressure plate, and cooler are connected in sequence to form the main circulation loop of heat transfer oil, and the oil outlet of the cooler flows back to the oil inlet of the circulating pump. The oil return tank is equipped with a vacuum oil return inlet, which is used to connect to an external vacuum oil pumping system to recover the heat transfer oil leaked from the pressure plate. The oil outlet of the return oil tank is connected to the oil replenishment port of the expansion tank through a pressurizing pump. The pressurizing pump is used to pressurize the heat transfer oil in the return oil tank and replenish it into the pressure and temperature expansion tank without shutting down the system. The third pressure detection sensor is installed on the expansion tank and is used to detect the pressure inside the expansion tank in real time. The control system is electrically connected to the booster pump and the third pressure detection sensor respectively. The control system is used to control the start, stop and output of the booster pump in a closed loop according to the feedback data of the third pressure detection sensor, so as to realize automatic online oil replenishment.

[0009] Furthermore, it also includes an accumulator connected in the oil replenishment circuit between the pressurization pump and the expansion tank to stabilize the oil replenishment pressure.

[0010] Furthermore, the output pressure of the pressurizing pump is not less than 3MPa and can be increased to a maximum of 3.5MPa, enabling online oil replenishment without stopping the machine under the maximum working pressure of 3.5MPa of the mold temperature controller.

[0011] Furthermore, a first shut-off valve is provided on the pipeline between the heater and the pressure plate, and a second shut-off valve is provided on the pipeline between the pressure plate and the cooler. Both the first shut-off valve and the second shut-off valve are electrically connected to the control system.

[0012] Furthermore, it also includes an on / off valve, the two ends of which are respectively connected to the oil outlet side of the heater and the oil inlet side of the cooler. The on / off valve is normally closed and is electrically connected to the control system.

[0013] Furthermore, the pressure plate is equipped with a first pressure detection sensor and a first temperature detection sensor at the oil inlet, and a second temperature detection sensor and a second pressure detection sensor at the oil outlet. All sensors are electrically connected to the control system. The control system has a built-in leakage identification interlock logic, which is used to identify the sealing status of the pressure plate based on the pressure difference and temperature difference between the oil inlet and outlet of the pressure plate. When an abnormal leakage is detected, the first shut-off valve and the second shut-off valve are triggered to close, and the on / off valve is triggered to open, switching the system to internal circulation of the mold temperature controller pipeline.

[0014] Furthermore, the expansion tank is also equipped with a safety valve, which is used to overflow and reduce pressure when the pressure inside the expansion tank exceeds the safety pressure; The expansion tank is also equipped with a third temperature detection sensor, which is electrically connected to the control system and is used to detect the temperature of the heat transfer oil in the expansion tank in real time.

[0015] Furthermore, the built-in oil replenishment control logic of the control system is based on the PID algorithm, which can maintain the liquid level control accuracy of the expansion tank within ±5% of the set value, and the system response time for initiating oil replenishment when the liquid level drops is less than 30 seconds.

[0016] Furthermore, the control system is electrically connected to the circulating pump, heater, and cooler respectively, and is used to adjust the output of the circulating pump to stabilize the system pressure and adjust the working state of the heater and cooler to stabilize the temperature of the circulating heat transfer oil according to the target pressure and target temperature set by the pressure plate. The cooler only activates its cooling function when the heat transfer oil in the circulation loop needs to be cooled; otherwise, it is used only as a flow path.

[0017] Secondly, a method for controlling an automatic oil return mold temperature controller capable of online oil replenishment, applied to the automatic oil return mold temperature controller system capable of online oil replenishment described in any of the preceding claims, comprising: S1. Start the circulation pump. The heat transfer oil in the expansion tank is sent to the pressure plate through the circulation pump and heater. The heat transfer oil after heat exchange flows back to the circulation pump through the cooler to form the main circulation of heat transfer oil. S2. The heat transfer oil leaking from the pressure plate is collected by the external vacuum oil pumping system and sent to the return oil tank for storage through the vacuum return oil inlet. S3. The pressure inside the expansion tank is detected in real time by the third pressure detection sensor. When the pressure inside the expansion tank is lower than the preset lower limit, the control system starts the pressurization pump to pressurize the heat transfer oil in the return oil tank and then add it to the expansion tank until the pressure inside the expansion tank is restored to the preset range. S4. The pressure and temperature at the oil inlet are monitored in real time by the first pressure sensor and the first temperature sensor at the oil inlet of the pressure plate. The pressure data is fed back to the pressurizing pump and the circulating pump for fine-tuning to stabilize the pressure output, and the temperature data is fed back to the heater and the cooler for fine-tuning to stabilize the temperature output. S5. Real-time comparison of pressure and temperature data between the oil inlet and outlet of the pressure plate. When the difference between the two is within a stable range, the pressure plate is judged to be in normal sealing condition. When the difference increases instantaneously and exceeds the preset threshold, the pressure plate is judged to have abnormal leakage. The first and second shut-off valves are immediately closed, and the normally closed on / off valve is opened at the same time to switch the system to internal circulation of the mold temperature controller pipeline.

[0018] Beneficial effects of this invention: (1) It realizes online oil replenishment without stopping the machine under high temperature and high pressure conditions, and completely solves the core defect of the existing technology that requires stopping the machine to release pressure and cool down before oil replenishment. Through the structural design of the return oil tank and the pressurization pump, the atmospheric pressure heat transfer oil can be pressurized to 3MPa and above, and directly replenished into the pressurized and heated expansion tank. There is no need to stop the machine, release pressure, or cool down, which completely eliminates the unplanned shutdown caused by oil replenishment, realizes continuous and uninterrupted production, and greatly improves production efficiency.

[0019] (2) A closed-loop recovery and reuse of leaked heat transfer oil has been achieved, forming a complete oil circulation system. The heat transfer oil leaking from the pressure plate is collected by the external vacuum oil pumping system and can be directly returned to the return oil tank. After purification, it can be reused for system oil replenishment, which greatly reduces the cost of purchasing new oil and further ensures the stability of continuous system operation.

[0020] (3) Significantly reduced production energy consumption and operating costs. It completely eliminated the ineffective loss of heat energy and pressurized nitrogen caused by frequent shutdowns and restarts. After the project is implemented, the nitrogen consumption caused by oil replenishment can be reduced by more than 95%. At the same time, it achieves 100% fully automatic oil replenishment and recycling without manual intervention, which greatly reduces the cost of manual maintenance.

[0021] (4) High oil replenishment control accuracy and strong system stability. By stabilizing the oil replenishment pressure through the accumulator, the oil replenishment control logic based on the PID algorithm can maintain the expansion tank liquid level control accuracy within ±5% of the set value. The system response time for starting oil replenishment when the liquid level drops is less than 30 seconds. The oil replenishment process is smooth and shock-free, and it can operate stably under the maximum working pressure of 3.5MPa of the mold temperature controller.

[0022] (5) It has a complete safety interlock protection function, which greatly improves the safety of equipment operation. By comparing the pressure and temperature parameters of the oil inlet and outlet of the pressure plate in real time, the sealing status of the pressure plate can be accurately identified. When an abnormal large leakage occurs, the oil circuit of the pressure plate can be cut off immediately and the system internal circulation can be switched to avoid the safety hazards caused by the splashing of high temperature heat transfer oil, and at the same time, the leakage condition can be avoided from impacting the mold temperature host system.

[0023] (6) High temperature and pressure control accuracy, adaptable to various production needs. Through real-time monitoring and closed-loop control by high-precision sensors, the working status of the pump group, heater and cooler can be finely adjusted in real time according to the target pressure and temperature requirements of the actuator, so as to achieve stable pressure and temperature output and adapt to the production needs of different working conditions. Attached Figure Description

[0024] Figure 1 This is a structural diagram of the automatic oil return mold temperature controller system provided in an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Return oil tank; 2. Pressurization pump; 3. Expansion tank; 4. Circulation pump; 5. Heater; 6. Pressure plate; 7. Cooler; 8. Accumulator; 9. First pressure sensor; 10. First temperature sensor; 11. First shut-off valve; 12. Second shut-off valve; 13. Second temperature sensor; 14. Second pressure sensor; 15. Third temperature sensor; 16. Safety valve; 17. Third pressure sensor; 18. On / off valve. Detailed Implementation

[0025] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0026] It should be noted that, unless otherwise specifically stated, the relative arrangement and numerical expressions of the components and steps described in these embodiments should not be construed as limiting the scope of the invention.

[0027] The following description of exemplary embodiments is merely illustrative and is not intended to limit the invention or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail herein, but where applicable, such techniques, methods, and apparatus should be considered part of this specification.

[0028] Example 1 See Figure 1 , Figure 1 This is a structural diagram of an automatic oil return mold temperature controller system with online oil replenishment proposed in this invention, which specifically includes: 1. Return oil tank, 2. Pressurization pump, 3. Expansion tank, 4. Circulation pump, 5. Heater, 6. Pressure plate, 7. Cooler, 8. Accumulator, 9. First pressure sensor, 10. First temperature sensor, 11. First shut-off valve, 12. Second shut-off valve, 13. Second temperature sensor, 14. Second pressure sensor, 15. Third temperature sensor, 16. Safety valve, 17. Third pressure sensor, 18. On / off valve and control system.

[0029] The main circulation loop of the heat transfer oil system consists of an expansion tank 3, a circulation pump 4, a heater 5, a first shut-off valve 11, a pressure plate 6, a second shut-off valve 12, and a cooler 7 connected in sequence. The oil outlet of the cooler 7 flows back to the oil inlet of the circulation pump 4, forming a closed-loop main circulation path for the heat transfer oil. In operation, the circulation pump 4 provides circulation power for the loop, pressurizes and transports the heat transfer oil in the expansion tank 3, and after being conditioned by the heater 5, it is sent to the pressure plate 6 to complete heat exchange. The heat transfer oil after heat exchange flows back to the inlet of the circulation pump 4 through the cooler 7 and continues to circulate. The return oil tank 1 is an atmospheric pressure oil storage structure with a vacuum return oil inlet on its side wall. This vacuum return oil inlet is used to connect to an external vacuum oil pumping system to recover the heat transfer oil leaked during the operation of the pressure plate 6, allowing the leaked medium to flow back into the return oil tank 1 for storage, forming a closed-loop recovery path for the leaked medium. The oil outlet of the return oil tank 1 is connected to the oil replenishment port of the expansion tank 3 through a pressurization pump 2. The pressurization pump 2 is used to pressurize the heat transfer oil in the atmospheric pressure return oil tank 1 and then replenish it into the pressurized and heated expansion tank 3 without shutting down the system. In this embodiment, the output pressure of the pressurizing pump 2 is not less than 3MPa and can be boosted to a maximum of 3.5MPa, enabling online oil replenishment without shutting down the system under the maximum working pressure of 3.5MPa of the mold temperature controller. The accumulator 8 is connected in the oil replenishment circuit between the pressurizing pump 2 and the expansion tank 3, and is used to absorb pressure fluctuations during the oil replenishment process, stabilize the oil replenishment pressure, and avoid pressure shocks affecting the expansion tank 3 and the main circulation circuit.

[0030] The third pressure detection sensor 17 is installed on the expansion tank 3 to detect the pressure inside the expansion tank 3 in real time. The control system is electrically connected to the pressurizing pump 2 and the third pressure detection sensor 17 respectively. The oil replenishment control logic built into the control system is based on the PID algorithm. It can control the start and stop and output power of the pressurizing pump 2 in a closed loop according to the real-time feedback data of the third pressure detection sensor 17 to realize automatic online oil replenishment.

[0031] In this embodiment, the expansion tank 3 is a constant-volume sealed structure. The pressure of the gas phase space inside the tank and the liquid level are in a fixed correspondence. Therefore, the liquid level height can be indirectly reflected by detecting the pressure inside the tank. Based on the above PID control logic, the liquid level control accuracy of the expansion tank 3 can be maintained within ±5% of the set value. The system response time for starting oil replenishment when the liquid level drops is less than 30 seconds, and the oil replenishment process is smooth without pressure shock.

[0032] The expansion tank 3 is also equipped with a safety valve 16 and a third temperature detection sensor 15. The opening pressure of the safety valve 16 is set to the system safety pressure threshold. It is used to automatically open the overflow pressure relief when the pressure in the expansion tank 3 exceeds the safety pressure, so as to avoid equipment failure caused by excessive pressure in the tank. The third temperature detection sensor 15 is electrically connected to the control system. It is used to detect the temperature of the heat transfer oil in the expansion tank 3 in real time and feed the temperature data back to the control system. It is used to monitor the state of the medium in the tank and realize the over-temperature protection logic.

[0033] A first shut-off valve 11 is installed on the pipeline between the heater 5 and the pressure plate 6, and a second shut-off valve 12 is installed on the pipeline between the pressure plate 6 and the cooler 7. Both the first shut-off valve 11 and the second shut-off valve 12 are electrically connected to the control system and can be controlled to open and close the oil circuits on both sides of the pressure plate 6. The two ends of the on / off valve 18 are respectively connected to the oil outlet side of the heater 5 and the oil inlet side of the cooler 7. The on / off valve 18 is normally closed and is electrically connected to the control system.

[0034] The pressure plate 6 is equipped with a first pressure sensor 9 and a first temperature sensor 10 at its oil inlet, and a second temperature sensor 13 and a second pressure sensor 14 at its oil outlet. Both the pressure and temperature sensors are electrically connected to the control system and are used to collect real-time pressure and temperature data from the oil inlet and outlet of the pressure plate 6. The control system has a built-in leakage identification interlock logic to identify the sealing status of the pressure plate 6 based on the pressure and temperature differences between its inlet and outlet. Under normal operating conditions, the pressure and temperature differences between the inlet and outlet of the pressure plate 6 are within a preset stable range. When an abnormal leak occurs in the pressure plate 6, the pressure and temperature differences between the inlet and outlet will instantly increase and exceed the preset leakage threshold. At this time, the control system triggers the first shut-off valve 11 and the second shut-off valve 12 to close, cutting off the oil inlet and outlet of the pressure plate 6. Simultaneously, it triggers the on / off valve 18 to open, allowing the heat transfer oil to flow directly from the heater 5 side through the on / off valve 18 to the cooler 7 side, switching the system to internal circulation within the mold temperature controller pipeline, isolating the leak fault section and ensuring continuous operation of the main system.

[0035] The control system is electrically connected to the circulating pump 4, heater 5, and cooler 7, respectively. It is used to adjust the output power of the circulating pump 4 to stabilize the system circulation pressure, and to adjust the heating power of the heater 5 and the operating state of the cooler 7 to stabilize the temperature of the circulating heat transfer oil, based on the target pressure and temperature set by the pressure plate 6. The cooler 7 only activates its cooling function when the heat transfer oil in the circulation loop needs to be cooled. When cooling is not required, it serves only as a flow path, with the heat transfer oil flowing directly through the cooler 7's pipes for return, thereby reducing equipment operating energy consumption.

[0036] Example 2 This embodiment provides a method for controlling an automatic oil return mold temperature controller with online oil replenishment, based on the system described in Embodiment 1. The specific steps are as follows: S1. Before starting the system, confirm that the first shut-off valve 11 and the second shut-off valve 12 are in the open state and the on / off valve 18 is in the normally closed state; start the circulation pump 4, and the heat transfer oil in the expansion tank 3 is pressurized by the circulation pump 4 and temperature adjusted by the heater 5 before being sent to the pressure plate 6. After heat exchange is completed in the pressure plate 6, the heat transfer oil flows back to the oil inlet of the circulation pump 4 through the cooler 7, forming a continuously running main circulation of heat transfer oil. S2. The heat transfer oil leaked during the operation of the pressure plate 6 is collected by the external vacuum oil pumping system and sent to the atmospheric pressure return oil tank 1 through the vacuum return oil inlet of the return oil tank 1 for storage, thus completing the closed-loop recovery of the leaked medium. S3. The pressure inside the expansion tank 3 is monitored in real time by the third pressure sensor 17. Since the expansion tank 3 is a constant-volume closed structure, the pressure inside the tank has a fixed relationship with the liquid level. When the pressure inside the expansion tank 3 is lower than the preset lower limit, that is, when the corresponding liquid level is lower than the set lower limit, the control system starts the pressurization pump 2 based on the built-in PID algorithm to pressurize the heat transfer oil in the atmospheric pressure return oil tank 1 to a level not lower than the system working pressure and then add it to the expansion tank 3. During the oil replenishment process, the accumulator absorbs pressure fluctuations to stabilize the oil replenishment pressure until the pressure inside the expansion tank 3 returns to the preset range, that is, when the corresponding liquid level returns to the set range, the pressurization pump 2 is controlled to stop replenishing the oil. In this control method, the liquid level control accuracy of the expansion tank 3 can be maintained within ±5% of the set value, and the system response time for starting oil replenishment when the liquid level drops is less than 30 seconds. During operation, if the pressure inside the expansion tank 3 exceeds the set safety pressure threshold, the safety valve 16 automatically opens to overflow and reduce pressure, ensuring that the pressure inside the tank is within the safe range. S4. The first pressure sensor 9 and the first temperature sensor 10 at the oil inlet of the pressure plate 6 monitor the oil inlet pressure and temperature in real time. The pressure data is fed back to the control system in real time. The control system adjusts the oil replenishment output of the pressurizing pump 2 and the circulation output of the circulating pump 4 to make fine adjustments to stabilize the pressure output on the pressure plate side. The temperature data is fed back to the control system in real time. The control system adjusts the heating power of the heater 5 and the cooling state of the cooler 7 to make fine adjustments to stabilize the temperature output on the pressure plate side. The cooler 7 only activates the cooling function when the temperature of the circulating heat transfer oil is higher than the target temperature and the temperature needs to be reduced. When no cooling is needed, it is only used as a flow pipeline. S5. The control system collects and compares the pressure and temperature data of the oil inlet and outlet of the pressure plate 6 in real time. When the pressure difference and temperature difference are both within the preset stable range, the pressure plate 6 is judged to be in normal sealing condition. When the pressure difference or temperature difference increases instantaneously and exceeds the preset leakage judgment threshold, the pressure plate 6 is judged to have abnormal leakage. The control system immediately outputs a control signal to close the first shut-off valve 11 and the second shut-off valve 12 to cut off the oil circuit on both sides of the pressure plate. At the same time, it opens the normally closed on / off valve 18 so that the heat transfer oil flows directly from the oil outlet side of the heater to the oil inlet side of the cooler through the on / off valve. The system is switched to internal circulation of the mold temperature controller pipeline, the fault section is isolated and the main system is ensured to continue to operate stably.

[0037] The above specific 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 examples, 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 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. An automatic oil return mold temperature control system with online oil replenishment, characterized in that, include: Return oil tank (1), pressurizing pump (2), expansion tank (3), circulation pump (4), heater (5), pressure plate (6), cooler (7), third pressure detection sensor (17) and control system; The expansion tank (3), circulation pump (4), heater (5), pressure plate (6), and cooler (7) are connected in sequence to form a main circulation loop for heat transfer oil. The oil outlet of the cooler (7) flows back to the oil inlet of the circulation pump (4). The oil return tank (1) is provided with a vacuum oil return inlet, which is used to connect to an external vacuum oil pumping system to recover the heat transfer oil leaked from the pressure plate (6); The oil outlet of the return oil tank (1) is connected to the oil replenishment port of the expansion tank (3) through the pressurizing pump (2). The pressurizing pump (2) is used to pressurize the heat transfer oil in the return oil tank (1) and replenish it into the expansion tank (3) with pressure and temperature without stopping the system. The third pressure detection sensor (17) is installed on the expansion tank (3) and is used to detect the pressure inside the expansion tank (3) in real time; The control system is electrically connected to the booster pump (2) and the third pressure detection sensor (17) respectively. The control system is used to control the start, stop and output of the booster pump (2) in a closed loop according to the feedback data of the third pressure detection sensor (17) to realize automatic online oil replenishment.

2. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, It also includes an accumulator (8), which is connected in the oil replenishment circuit between the pressurizing pump (2) and the expansion tank (3) to stabilize the oil replenishment pressure.

3. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, The output pressure of the pressurizing pump (2) is not less than 3MPa and can be increased to 3.5MPa. It can achieve online oil replenishment without stopping the machine under the working pressure of 3.5MPa of the mold temperature controller.

4. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, A first shut-off valve (11) is provided on the pipeline between the heater (5) and the pressure plate (6), and a second shut-off valve (12) is provided on the pipeline between the pressure plate (6) and the cooler (7). Both the first shut-off valve (11) and the second shut-off valve (12) are electrically connected to the control system.

5. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, It also includes a shut-off valve (18), the two ends of which are connected to the oil outlet side of the heater (5) and the oil inlet side of the cooler (7), respectively. The shut-off valve (18) is normally closed and is electrically connected to the control system.

6. The automatic oil return mold temperature control system with online oil replenishment according to claim 4, characterized in that, The pressure plate (6) is provided with a first pressure detection sensor (9) and a first temperature detection sensor (10) at the oil inlet, and a second temperature detection sensor (13) and a second pressure detection sensor (14) at the oil outlet. All sensors are electrically connected to the control system. The control system has a built-in leakage identification interlock logic, which is used to identify the sealing status of the pressure plate (6) based on the pressure difference and temperature difference between the oil inlet and outlet of the pressure plate (6). When an abnormal leakage is detected, the first shut-off valve (11) and the second shut-off valve (12) are triggered to close, and the on / off valve (18) is triggered to open, switching the system to internal circulation of the mold temperature controller pipeline.

7. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, The expansion tank (3) is also provided with a safety valve (16), which is used to overflow and reduce pressure when the pressure inside the expansion tank (3) exceeds the safety pressure; The expansion tank (3) is also equipped with a third temperature detection sensor (15), which is electrically connected to the control system and is used to detect the temperature of the heat transfer oil in the expansion tank (3) in real time.

8. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, The built-in oil replenishment control logic of the control system is based on the PID algorithm, which can maintain the liquid level control accuracy of the expansion tank (3) within ±5% of the set value, and the system response time for starting oil replenishment when the liquid level drops is less than 30 seconds.

9. The automatic oil return mold temperature control system with online oil replenishment according to claim 1, characterized in that, The control system is electrically connected to the circulating pump (4), heater (5), and cooler (7) respectively. It is used to adjust the output of the circulating pump (4) to stabilize the system pressure and adjust the working state of the heater (5) and cooler (7) to stabilize the temperature of the circulating heat transfer oil according to the target pressure and target temperature set by the pressure plate (6). The cooler (7) only activates the cooling function when the heat transfer oil in the circulation loop needs to be cooled down; otherwise, it is used as a flow pipeline.

10. A method for controlling an automatic oil return mold temperature controller with online oil replenishment, characterized in that, The automatic oil return mold temperature controller system with online oil replenishment as described in any one of claims 1-9 includes: S1. Start the circulation pump (4). The heat transfer oil in the expansion tank (3) is sent to the pressure plate (6) through the circulation pump (4) and heater (5). The heat transfer oil after heat exchange flows back to the circulation pump (4) through the cooler (7) to form the main circulation of heat transfer oil. S2. The heat transfer oil leaking from the pressure plate (6) is collected by the external vacuum oil pumping system and then sent to the return oil tank (1) for storage through the vacuum return oil inlet. S3. The pressure inside the expansion tank (3) is detected in real time by the third pressure detection sensor (17). When the pressure inside the expansion tank (3) is lower than the preset lower limit, the control system starts the pressurization pump (2) to pressurize the heat transfer oil in the return oil tank (1) and add it to the expansion tank (3) until the pressure inside the expansion tank (3) is restored to the preset range. S4. The first pressure sensor (9) and the first temperature sensor (10) at the oil inlet of the pressure plate (6) monitor the pressure and temperature of the oil inlet in real time. The pressure data is fed back to the pressurizing pump (2) and the circulating pump (4) for fine-tuning to stabilize the pressure output. The temperature data is fed back to the heater (5) and the cooler (7) for fine-tuning to stabilize the temperature output. S5. Real-time comparison of pressure data and temperature data between the oil inlet and outlet of the pressure plate (6). When the difference between the two is within a stable range, it is determined that the pressure plate (6) is properly sealed. When the difference increases instantaneously and exceeds the preset threshold, it is determined that the pressure plate (6) has an abnormal leak. Immediately close the first shut-off valve (11) and the second shut-off valve (12), and at the same time open the normally closed on / off valve (18) to switch the system to internal circulation of the mold temperature controller pipeline.

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