A dual closed-loop die casting machine injection system

Abstract

This invention relates to the technical field of die-casting equipment, and specifically discloses a dual closed-loop die-casting machine injection system, including an injection cylinder, a booster cylinder, a first accumulator, a second accumulator, an oil tank, a controller, and injection oil circuits, replenishment oil circuits, discharge oil circuits, and booster oil circuits configured in the loop. By setting a fast discharge replenishment valve between the first accumulator and the rod chamber of the injection cylinder, and using a high-frequency response proportional valve with continuous stroke control on the discharge circuit between the rod chamber and the oil tank, the system can seamlessly switch between the rapid injection and booster stages with only a single proportional valve, realizing dual closed-loop control of speed and pressure at the outlet throttling. This structure cleverly eliminates the need for an external replenishment oil source, effectively eliminating the impact of rapid injection, and achieving extremely high injection accuracy and high system safety while significantly reducing high-end hardware and maintenance costs.

Description

Technical Field

[0001] This invention relates to the technical field of die casting machines, and specifically to a double closed-loop die casting machine injection system. Background Technology

[0002] High-pressure casting of aluminum alloys is a casting method in which molten or semi-molten aluminum alloy is rapidly filled into the mold cavity, and then cooled under pressure to form a casting product. High-quality aluminum alloy products have extremely high requirements for the hammer speed and casting pressure of the injection system of the die casting machine. At present, the mainstream die casting machines are divided into open-loop machines and closed-loop machines according to the control method of the injection system.

[0003] Traditional open-loop die casting machines use ordinary cartridge valves to control the inlet and outlet of the injection cylinder, and the hydraulic system has no feedback adjustment. This makes the system highly susceptible to factors such as oil temperature, leakage, and mold, and it is impossible to achieve high process stability. At the same time, key process parameters such as injection speed, pressure build-up time, and casting pressure cannot be dynamically adjusted, which cannot meet the molding requirements of high-precision and complex structure die castings.

[0004] To address the aforementioned issues, the industry has developed a dual-closed-loop injection system. This system typically requires high-frequency response proportional valves to be installed in both the rod-side and rodless-side chambers of the injection cylinder to achieve real-time feedback control of the speed and pressure loops. It offers high injection accuracy and strong process consistency, meeting the molding requirements of most complex die-casting parts. However, it relies on the coordinated action of multiple high-frequency response proportional valves, resulting in higher operating costs.

[0005] To balance dual closed-loop functionality with cost control, some single proportional valve outlet throttling control system solutions have emerged on the market: 1. Using an external oil source combined with a hydraulic booster to directly inject high-pressure oil into the rod chamber of the injection cylinder to establish back pressure, thereby eliminating the hammer head forward thrust phenomenon at the moment of rapid injection start-up. However, the introduced hydraulic booster will also significantly increase hardware costs and generate huge noise during operation. 2. A three-way high-frequency response proportional valve is used for control, eliminating the need for a hydraulic booster. However, due to the functional limitations of the three-way high-frequency response proportional valve, when switching from rapid injection to the boosting stage, the valve core needs to pass through a position that almost completely closes the rod chamber. At this time, the boosting inlet pressure rises sharply, and the volume of the closed rod chamber is compressed, which can easily generate ultra-high hydraulic pressure close to or exceeding 100MPa. This not only places stringent pressure resistance requirements on hardware such as cylinder, valve body, and seals, but also has an extremely low fault tolerance rate, posing a serious safety hazard. Summary of the Invention

[0006] This invention addresses the aforementioned problems and aims to provide a dual closed-loop die-casting machine injection system. By optimizing the oil circuit layout and using a single high-frequency response proportional valve for control, it can significantly reduce operating costs while ensuring high injection accuracy and process stability.

[0007] To achieve the above objectives, the present invention provides a dual closed-loop die-casting machine injection system, comprising an injection cylinder, a booster cylinder, a first accumulator, a second accumulator, an oil tank, a controller, and: The injection circuit includes an injection quick valve located between the first accumulator and the rodless chamber of the injection cylinder; The oil replenishment circuit includes a quick-release oil replenishment valve and a quick-release oil replenishment check valve connected in series. The oil replenishment circuit is located between the first accumulator and the rod chamber of the injection cylinder, and the quick-release oil replenishment check valve is configured to unidirectionally flow toward the rod chamber of the injection cylinder. The oil discharge circuit includes a quick discharge proportional valve located between the rod chamber of the injection cylinder and the oil tank, wherein the quick discharge proportional valve is configured as a high-frequency response proportional valve; The booster oil circuit includes a booster oil inlet valve located between the second accumulator and the rodless chamber of the booster oil cylinder; the piston rod of the booster oil cylinder can extend into the rodless chamber of the injection oil cylinder; The controller is communicatively connected to the injection quick valve, the quick discharge replenishment valve, the quick discharge proportional valve, and the booster inlet valve, and is configured as follows: Under rapid injection conditions, the rapid injection valve is opened, the rapid discharge replenishment valve is closed, and the rapid discharge proportional valve is controlled to open to a first predetermined degree. Under boosting conditions, the boosting oil inlet valve and the quick discharge replenishment valve are opened, and the quick discharge proportional valve is controlled to open to the second predetermined degree.

[0008] The above-described dual closed-loop die-casting machine injection system further includes a third accumulator, a pilot filter, a first pilot check valve, and a second pilot check valve. The third accumulator is connected to the pilot chamber of the fast discharge proportional valve. The pilot filter and the first pilot check valve are connected in series to form a pilot oil inlet branch. The pilot oil inlet branch is located between the first accumulator and the third accumulator. The second pilot check valve and the pilot oil inlet branch are connected in parallel between the first accumulator and the third accumulator. The first pilot check valve is configured to unidirectionally open toward the third accumulator, and the second pilot check valve is configured to unidirectionally open toward the first accumulator.

[0009] According to the above-described double closed-loop die-casting machine injection system, the oil discharge circuit further includes an overflow valve, the oil inlet of which is connected to the rod chamber of the injection cylinder, and the oil outlet of which is connected to the oil tank.

[0010] The above-described dual closed-loop die casting machine injection system further includes a system oil source and a start-up pre-pressure oil circuit, wherein the start-up pre-pressure oil circuit includes a hammer pre-valve located between the system oil source and the rodless chamber of the injection cylinder; The controller is further configured to: during the startup phase, open the hammer front valve and the fast discharge replenishment valve, and close the fast discharge proportional valve.

[0011] According to the above-described dual closed-loop die casting machine injection system, the start-up pre-pressure oil circuit further includes a hammer-front one-way valve, which is located between the oil outlet of the hammer-front valve and the rodless chamber of the injection cylinder, and is configured to unidirectionally guide toward the rodless chamber of the injection cylinder.

[0012] According to the above-described dual closed-loop die casting machine injection system, the injection oil circuit further includes a high-pressure isolation valve, which is located between the injection quick valve and the rodless chamber of the injection cylinder. The oil inlet of the high-pressure isolation valve is connected to the oil outlet of the injection quick valve, and the oil outlet of the high-pressure isolation valve is connected to the rodless chamber of the injection cylinder. The oil outlet of the hammer-front check valve is connected to the oil inlet of the high-pressure isolation valve.

[0013] The above-described double closed-loop die casting machine injection system further includes an injection return oil circuit, which includes a hammer inlet valve located between the system oil source and the rod chamber of the injection cylinder, and a hammer return oil valve located between the rodless chamber of the injection cylinder and the oil tank. The controller is further configured to open the hammer rear oil inlet valve and the hammer rear oil return valve when the ejection condition is underway.

[0014] According to the above-described double closed-loop die casting machine injection system, the injection retraction oil circuit further includes a hammer-back check valve, which is located between the oil outlet of the hammer-back oil inlet valve and the rod chamber of the injection cylinder, and is configured to unidirectionally guide towards the rod chamber of the injection cylinder.

[0015] According to the above-described dual closed-loop die-casting machine injection system, the booster oil circuit further includes a hydraulically controlled return oil check valve, which is arranged between the rodless chamber of the booster oil cylinder and the oil tank.

[0016] According to the above-described double closed-loop die-casting machine injection system, the pilot chamber of the hydraulic return oil check valve is connected to the oil outlet of the hammer inlet valve.

[0017] The present invention has the following beneficial effects: 1. A high-frequency response proportional valve is integrated only on the oil discharge side of the rod chamber of the injection cylinder, combining the adjustment functions of the proportional valve required for the speed ring and the proportional valve required for the pressure ring into one. This replaces the multi-proportional valve solution from the source, reduces the number of precision components, greatly saves hardware costs, and reduces the complexity of subsequent software debugging and maintenance. While improving accuracy, it also reduces the cost of use. 2. Due to the use of a high-frequency response proportional valve, when switching from the rapid injection stage to the pressurization stage, the high-frequency response proportional valve needs to switch from the speed control stage to the pressure control stage. Its opening size is adjustable, ensuring that no matter which pressurization stage the system is in, its pressure relief and oil discharge port to the oil tank always retains a specific controlled opening. This ensures that the system will never generate excessively high pressure fluctuations beyond the safety limit due to pressure accumulation, greatly reducing the ultimate pressure bearing requirements of the injection cylinder body, proportional valve, and seals, and reducing safety risks. 3. By using the first accumulator to directly replenish oil to the rod chamber of the injection cylinder, the problem of insufficient back pressure in the rod chamber of the injection cylinder during the rapid injection and pressurization stages can be solved. There is no need to rely on an external oil source to replenish oil to the rod chamber of the injection cylinder, which effectively simplifies the hydraulic circuit and saves the cost of additional oil replenishment equipment. 4. During startup, both the hammer front valve and the quick discharge replenishing valve are open, and the quick discharge proportional valve is closed. This allows the oil from the system oil source to enter the rodless chamber of the injection cylinder, pushing the piston rod out. At the same time, the oil in the first accumulator enters the rod chamber of the injection cylinder. The oil pressure on both sides gradually returns to equilibrium, thus enabling a smooth start when switching to the rapid injection state. This completely eliminates the problem of the hammer head rushing forward during the rapid injection stage caused by a single proportional valve. 5. An overflow valve is installed on the rod chamber side of the injection cylinder to ensure that the pressure in the rod chamber of the injection cylinder is always within a safe range, avoiding safety problems caused by valve jamming or other malfunctions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall oil circuit of the injection system in an embodiment.

[0019] In the picture: 1. Injection cylinder; 2. Booster cylinder; 3. First accumulator; 4. Second accumulator; 5. Oil tank; 6. Injection quick valve; 7. High-pressure isolation valve; 8. Quick discharge replenishing valve; 9. Quick discharge replenishing check valve; 10. Quick discharge proportional valve; 11. Relief valve; 12. Third accumulator; 13. Pilot filter; 14. First pilot check valve; 15. Second pilot check valve; 16. Booster inlet valve; 17. Hydraulic return check valve; 18. System oil source; 19. Hammer inlet valve; 20. Hammer inlet check valve; 21. Hammer outlet valve; 22. Hammer return valve; 23. Hammer outlet check valve. Detailed Implementation

[0020] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solution of the present invention. However, the invention is not limited to these embodiments.

[0021] like Figure 1 As shown, this embodiment discloses a dual closed-loop die-casting machine injection system, including an injection cylinder 1 that provides basic hydraulic power, a booster cylinder 2, a first accumulator 3, a second accumulator 4, an oil tank 5, a controller (not shown in the figure), a system oil source 18, and various hydraulic oil circuits connecting them.

[0022] Both the injection cylinder 1 and the booster cylinder 2 have rod chambers and rodless chambers. The piston rod of the booster cylinder 2 can extend into the rodless chamber of the injection cylinder 1. Once the piston rod of the booster cylinder 2 continues to extend, its volume occupied in the rodless chamber of the injection cylinder 1 increases. Without the piston of the injection cylinder 1 moving, the oil pressure in the rodless chamber of the injection cylinder 1 can be increased, achieving the purpose of boosting pressure. Each hydraulic circuit includes an injection circuit connecting the first accumulator 3 to the rodless chamber of the injection cylinder 1, and a circuit connecting the first accumulator 3 to... The injection cylinder 1 has a replenishing oil circuit for the rod chamber, an oil discharge circuit connecting the rod chamber of the injection cylinder 1 to the oil tank 5, a boosting oil circuit connecting the second accumulator 4 to the rodless chamber of the boosting cylinder 2, a starting pre-pressure oil circuit connecting the system oil source 18 to the rodless chamber of the injection cylinder 1, a retraction oil circuit connecting the system oil source 18 to the rod chamber of the injection cylinder 1 and connecting the rodless chamber of the injection cylinder 1 to the oil tank 5. The core actuator is the injection cylinder 1, which has a starting stage, a rapid injection stage, a boosting / holding stage, and a retraction stage.

[0023] In this embodiment, the core improvement lies in the fast discharge oil circuit, which includes a fast discharge proportional valve 10 located between the rod chamber of the injection cylinder 1 and the oil tank 5. This fast discharge proportional valve 10 is a high-frequency response proportional valve, specifically a two-position high-frequency response proportional valve. Its valve core is configured to move controllably within the stroke range between the fully closed and fully open positions, meaning the opening size of the fast discharge proportional valve 10 is adjustable. This allows control over the oil discharge speed and volume of the rod chamber of the injection cylinder 1. During the rapid injection phase, the injection oil circuit supplies oil to the rodless chamber of the injection cylinder 1, and the opening of the fast discharge proportional valve 10 controls the oil discharge speed of the rod chamber, thereby controlling the overall injection speed of the die-casting machine. In other words, by pre-setting process parameters through the software control system, the controller can adjust the speed feedback accordingly. The control algorithm is executed to precisely control the opening of the quick-release proportional valve 10, thereby controlling the piston extension speed and achieving a speed closed loop. When the injection cylinder 1 is in the pressurization / holding stage, oil is supplied to the rodless chamber of the pressurization cylinder 2 through the pressurization oil circuit, and oil is simultaneously supplied to the rod chamber of the injection cylinder 1 through the replenishment oil circuit, thereby establishing back pressure to control the casting pressure. During this process, adjusting the oil discharge opening of the quick-release proportional valve 10 can adjust the pressure in the rod chamber of the injection cylinder 1, thereby controlling the casting pressure. Consistent with speed control, the software system executes the control algorithm based on pressure feedback to achieve a pressure closed loop. In this embodiment, a single quick-release proportional valve 10 can achieve dual closed-loop control of speed and pressure in the injection system, which can greatly save costs and improve product competitiveness.

[0024] Furthermore, the oil discharge circuit also includes a third accumulator 12, a pilot filter 13, a first pilot check valve 14, and a second pilot check valve 15. The third accumulator 12 is connected to the pilot chamber of the fast discharge proportional valve 10. The pilot filter 13 and the first pilot check valve 14 are connected in series to form a pilot inlet branch, which is located between the first accumulator 12 and the third accumulator 12. The second pilot check valve 15 is connected in parallel with the pilot inlet branch between the first accumulator 3 and the third accumulator 12. The first pilot check valve 14 is configured to unidirectionally flow towards the third accumulator 12, and the second pilot check valve 15 is configured to unidirectionally flow towards the first accumulator 3. When the fast discharge proportional valve 10 is working, the control oil required for its pilot chamber is directly supplied by the third accumulator 12. Due to the volume buffering effect of the third accumulator 12, it can... Instantly providing or absorbing flow ensures pilot pressure stability, unaffected by instantaneous fluctuations in main oil circuit pressure. This provides the foundation for high-precision closed-loop control of injection speed and casting pressure. Simultaneously, when the pressure of the first accumulator 3 is higher than that of the third accumulator 12, the pressurized oil is purified by the pilot filter 13 before entering the third accumulator 12. This effectively prevents contaminants that may exist in the main oil circuit from entering the pilot chamber of the quick-release proportional valve 10, avoiding valve core jamming or wear, and improving the lifespan and control stability of the quick-release proportional valve 10. The second pilot check valve 15 forms a safe pressure release channel. In case of emergency stop or maintenance, the high-pressure oil in the pilot control circuit can be safely released, avoiding the risks caused by residual pressure and facilitating the reset of the quick-release proportional valve 10.

[0025] Furthermore, the oil discharge circuit also includes an overflow valve 11. The oil inlet of the overflow valve 11 is connected to the rod chamber of the injection cylinder 1, and the oil outlet of the overflow valve 11 is connected to the oil tank 5. The overflow valve 11 is used to ensure that the pressure in the rodless chamber of the injection cylinder 1 is always within a safe range, and to prevent safety problems caused by valve jamming or other malfunctions.

[0026] Specifically, since the quick-release proportional valve 10 is set as a high-frequency response proportional valve, when switching between speed control and pressure control, the main valve core only needs to switch between left and right positions, resulting in a faster response speed and more sensitive action.

[0027] Specifically, the injection oil circuit includes an injection quick valve 6 located between the first accumulator 3 and the rodless chamber of the injection cylinder 1. That is, the oil inlet of the injection quick valve 6 is connected to the first accumulator 3, and the oil outlet of the injection quick valve 6 is connected to the rodless chamber of the injection cylinder 1. When the injection quick valve 6 is opened, the high-pressure oil in the first accumulator 3 can enter the rodless chamber of the injection cylinder 1 through the injection quick valve 6, and push the piston rod of the injection cylinder 1 to extend, thereby realizing the injection action.

[0028] Furthermore, to prevent excessive oil pressure in the rodless chamber of the injection cylinder 1 from causing backflow into the first accumulator 3, the injection oil circuit also includes a high-pressure isolation valve 7. The high-pressure isolation valve 7 is located between the injection quick valve 6 and the rodless chamber of the injection cylinder 1. The inlet of the high-pressure isolation valve 7 is connected to the outlet of the injection quick valve 6, and the outlet of the high-pressure isolation valve 7 is connected to the rodless chamber of the injection cylinder 1. The high-pressure isolation valve 7 is mainly used in the pressurization stage, when the oil pressure in the rodless chamber of the injection cylinder 1 increases. The high-pressure isolation valve 7 can isolate the high-pressure oil in the rodless chamber of the injection cylinder 1 during the pressurization stage, preventing the high-pressure oil from flowing back into the first accumulator 3, and also avoiding changes in the oil pressure in the rodless chamber of the injection cylinder 1 due to the backflow of high-pressure oil.

[0029] Of course, in this embodiment, the rapid injection valve 6 has a pilot valve, which controls the opening and closing of the rapid injection valve 6. Specifically, when the pilot valve is energized, the rapid injection valve 6 opens; when the pilot valve is de-energized, the rapid injection valve 6 closes. The pilot oil of the pilot valve comes from the first accumulator 3.

[0030] Specifically, the oil replenishment circuit includes a quick-release oil replenishment valve 8 and a quick-release oil replenishment check valve 9 connected in series. The oil replenishment circuit connects the first accumulator 3 and the rod chamber of the injection cylinder 1, and the quick-release oil replenishment check valve 9 is configured to conduct unidirectionally toward the rod chamber of the injection cylinder 1. The oil replenishment circuit shares the first accumulator 3 with the injection circuit, eliminating the need for external oil sources to replenish the rodless chamber of the injection cylinder 1, thus saving the hardware cost of external oil replenishment equipment and simplifying the oil circuit. It is mainly used to replenish the rod chamber of the injection cylinder 1 during the start-up and pressurization stages, thereby quickly establishing back pressure. The function of the quick-release oil replenishment check valve 9 is to prevent the hydraulic oil in the rod chamber of the injection cylinder 1 from flowing to the first accumulator 3, thereby improving the service life of the first accumulator 3.

[0031] Of course, the quick-discharge oil replenishment valve 8 also has a pilot valve, which is used to control the opening and closing of the quick-discharge oil replenishment valve 8. Its pilot oil also comes from the first accumulator 3.

[0032] Specifically, the boosting oil circuit includes a boosting oil inlet valve 16 connecting the second accumulator 4 and the rodless chamber of the boosting cylinder 2. When the boosting oil inlet valve 16 is open, the hydraulic oil in the second accumulator 4 can enter the rodless chamber of the boosting cylinder 2 through the boosting oil inlet valve 16. At this time, the piston rod of the boosting cylinder 2 extends and occupies more volume in the rodless chamber of the injection cylinder 1. When the piston rod of the injection cylinder 1 does not move, the oil pressure in the rodless chamber of the injection cylinder 1 will rise, thereby achieving the effect of boosting. Similarly, the boosting oil inlet valve 16 also has a pilot valve for controlling the opening or closing of the boosting oil inlet valve 16.

[0033] Specifically, the pre-pressurization oil circuit includes a hammer pre-valve 19 located between the system oil source 18 and the rodless chamber of the injection cylinder 1. The inlet of the hammer pre-valve 19 is connected to the system oil source 18, and its outlet is connected to the rodless chamber of the injection cylinder 1. It is used to supply oil to the rodless chamber of the injection cylinder 1 during the injection start-up phase. During this phase, the replenishment oil circuit simultaneously supplies oil to the rod chamber of the injection cylinder 1 until the pressure in the two chambers of the injection cylinder 1 is the same, which facilitates the smooth start-up of the subsequent injection phase.

[0034] Furthermore, the pre-pressurization oil circuit also includes a hammer-front check valve 20 located between the outlet of the hammer-front valve 19 and the rodless chamber of the injection cylinder 1. The hammer-front check valve 20 is configured to conduct unidirectionally toward the rodless chamber of the injection cylinder 1. The hammer-front check valve 20 can prevent the hydraulic oil in the rodless chamber of the injection cylinder 1 from entering the system oil source 18 through the hammer-front valve 19. Specifically, the hammer-front check valve 20 is arranged between the hammer-front valve 19 and the high-pressure isolation valve 7, and the outlet of the hammer-front check valve 20 is connected to the inlet of the high-pressure isolation valve 7.

[0035] Specifically, the ejection oil circuit includes a hammer-back oil inlet valve 21 located between the system oil source 18 and the rod chamber of the injection cylinder 1, and a hammer-back oil return valve 22 located between the rodless chamber of the injection cylinder 1 and the oil tank 5. After all actions are completed, the injection cylinder 1 needs to be reset. At this time, the ejection oil circuit starts to work, and both the hammer-back oil inlet valve 21 and the hammer-back oil return valve 22 are opened. The system oil source 18 supplies oil to the rod chamber of the injection cylinder 1 through the hammer-back oil inlet valve 21. The oil in the rodless chamber of the injection cylinder 1 enters the oil tank 5 through the hammer-back oil return valve 22. At this time, the piston rod of the injection cylinder 1 retracts, performing the ejection action.

[0036] Furthermore, the injection retraction oil circuit also includes a hammer-back check valve 23. The hammer-back check valve 23 is located between the oil outlet of the hammer-back oil inlet valve 21 and the rod chamber of the injection cylinder 1, and is configured to unidirectionally guide the oil towards the rod chamber of the injection cylinder 1. The hammer-back check valve 23 is used to prevent the oil in the rod chamber of the injection cylinder 1 from entering the system oil port.

[0037] Of course, the hammer front valve 19, the hammer rear oil inlet valve 21, and the hammer rear oil return valve 22 are all equipped with pilot valves to control their opening or closing.

[0038] Furthermore, during the retraction phase, the booster cylinder 2 also needs to retract its piston rod, thus requiring the hydraulic oil in its rodless chamber to be discharged. In this embodiment, the booster oil circuit also includes a hydraulically controlled return check valve 17, which is located between the rodless chamber of the booster cylinder 2 and the oil tank 5. The hydraulically controlled return check valve 17 facilitates the discharge of oil from the rodless chamber of the booster cylinder 2. However, if a conventional one-way check valve is used, the oil in the rodless chamber of the booster cylinder 2 will enter and be discharged through the check valve during the boosting phase, preventing the boosting action from taking place. Therefore, the check valve is configured as a hydraulically controlled return check valve 17, whose pilot chamber is connected to the outlet of the hammer inlet valve 21. The hydraulically controlled return check valve 17 can only be opened after the hammer inlet valve 21 is opened, i.e., during the retraction phase, allowing the oil in the rodless chamber of the booster cylinder 2 to be discharged.

[0039] In this embodiment, the controller is communicatively connected to the injection quick valve, quick discharge replenishment valve, quick discharge proportional valve, booster inlet valve, hammer pre-valve, hammer post-inlet valve, and hammer post-return valve, and is configured to provide control for each action. The complete operation of the injection system can be divided into the following four stages: 1. Start-up Phase: During this preparation phase, the system oil source 18 has already supplied hydraulic oil at the target pressure to the first accumulator 3 and the second accumulator 4. The oil in the first accumulator 3 has also been replenished to the third accumulator 12 through the pilot oil filter and the first pilot check valve 14. During startup, the controller is configured to: control the valve core of the fast discharge proportional valve 10 to be in the fully closed position, and issue a command to energize the pilot valves of the hammer front valve 19 and the fast discharge replenishment valve 8. At this time, the oil from the system oil source 18 passes through the hammer front valve 19 and the high pressure... Isolation valve 7 enters the rodless chamber of injection cylinder 1. At the same time, the oil in the first accumulator 3 passes through the quick-release oil replenishment valve 8 into the rod chamber of injection cylinder 1. However, since the piston on the rodless side is slightly larger than that on the rod side, the injection piston is squeezed and extends forward slightly, which compresses the rod chamber. Because the quick-release proportional valve 10 is closed, the pressure in the rod chamber rises spontaneously until the forces on the left and right chambers of the piston reach static equilibrium. At this time, the pre-start is achieved smoothly, the piston is stationary, and the high-pressure impact caused by instantaneous connection during the injection stage is avoided.

[0040] 2. Rapid Injection Stage: At this stage, the controller is configured to de-energize and close the pilot valves of the rapid discharge oil replenishment valve 8 and the hammer front valve 19, and energize and open the pilot valve of the rapid injection valve 6 to the first predetermined opening degree. A large flow of oil from the first accumulator 3 enters the rodless chamber of the injection cylinder 1 through the rapid injection valve 6. Because static balance has been achieved on both sides of the injection cylinder 1 during the start-up stage, there is no forward surge during the instantaneous pressure release. At the first predetermined opening degree, the valve core of the rapid discharge proportional valve 10 is in the fully open position or within its stroke range, meaning the rapid discharge proportional valve 10 receives the output from the controller. When the command voltage is turned on, the oil in the rod chamber of the injection cylinder 1 is discharged into the oil tank 5 along the piston through the quick discharge proportional valve 10. The discharge of oil causes the pressure in the rod chamber to drop, and the oil in the rodless chamber begins to push the piston to do work at high speed. The opening of the quick discharge proportional valve 10 can be changed by continuously adjusting the feedback voltage, thereby precisely intercepting and changing the amount of oil discharged. When the hammer head approaches the end of the stroke, the system automatically makes the opening of the quick discharge proportional valve 10 significantly reduce to create an effective oil valve brake, preventing the hammer head from hitting the mold area, and realizing speed closed-loop control based on a single proportional valve.

[0041] 3. Pressure Intensification / Holding Stage: In this stage, injection is complete and mold filling is finished. High casting pressure needs to be established to ensure proper molding. At this time, the controller is configured to energize the pilot valve of the pressure inlet valve 16, causing it to open. Oil from the second accumulator 4 enters the rodless chamber of the pressure cylinder 2. Due to the impulse area ratio effect inside the pressure piston, the piston rod causes a two-stage superimposed compression of the oil in the rodless chamber of the preceding injection cylinder 1, thus increasing the oil pressure in the rodless chamber of injection cylinder 1. However, since the rapid injection stage has just ended, the oil pressure in the rod chamber of injection cylinder 1 is still low. Due to insufficient pressure, damping resistance cannot be formed. Therefore, the control system controls the quick discharge oil replenishment valve 8 to open simultaneously, allowing the first accumulator 3 to input oil into the rod chamber of the injection cylinder 1, thereby quickly establishing back pressure in the rod chamber. The controller then controls the quick discharge proportional valve 10 to open to the second predetermined opening degree. At this time, the valve core of the quick discharge proportional valve 10 is in the stroke range between the fully open and fully closed positions, thereby adjusting the ratio of the amount of oil entering and exiting the rod chamber of the injection cylinder 1, thus maintaining a constant back pressure and accurately controlling the casting pressure finally applied to the internal cavity of the aluminum alloy mold, completing the pressure closed-loop control.

[0042] 4. Injection Retraction Stage: After one molding cycle is completed, the piston rods of the injection cylinder 1 and the booster cylinder 2 need to be returned to their original positions. At this time, the controller is configured to open the hammer inlet valve 21 and the hammer return valve 22. The oil in the system oil source 18 enters the rod chamber of the injection cylinder 1, the oil pressure in the rod chamber increases, pushing the piston to retract, and the oil in the rodless chamber returns to the oil tank 5 through the hammer return valve 22. At the same time, when the oil flows through the hammer inlet valve 21, a small portion of the oil acts as a pilot valve to open the pilot valve seat of the hydraulically controlled return check valve 17. This allows the piston of the injection cylinder 1 to physically push back the piston rod of the booster cylinder 2. At this time, the oil in the rodless chamber of the booster cylinder 2 can be discharged through the hydraulically controlled return check valve 17.

[0043] Of course, the complete action should also include a cooling phase and a follow-up hammer phase. The cooling phase is after the pressurization phase, and the follow-up hammer phase is between the cooling phase and the ejection phase. However, since this does not involve the content that this application needs to protect, it will not be elaborated further.

[0044] The first preset opening and the second preset opening can be controlled according to actual needs.

[0045] The technical solution of the present invention has been described in detail above with reference to the accompanying drawings. The described embodiments are used to help understand the concept of the present invention. The specific embodiments described herein are merely illustrative examples of the spirit of the present invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

[0046] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0047] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A dual closed-loop die-casting machine injection system, characterized in that, Includes injection cylinder, booster cylinder, first accumulator, second accumulator, oil tank, controller, and: The injection circuit includes an injection quick valve located between the first accumulator and the rodless chamber of the injection cylinder; The oil replenishment circuit includes a quick-release oil replenishment valve and a quick-release oil replenishment check valve connected in series. The oil replenishment circuit is located between the first accumulator and the rod chamber of the injection cylinder, and the quick-release oil replenishment check valve is configured to unidirectionally flow toward the rod chamber of the injection cylinder. The oil discharge circuit includes a quick discharge proportional valve located between the rod chamber of the injection cylinder and the oil tank, wherein the quick discharge proportional valve is configured as a high-frequency response proportional valve; The booster oil circuit includes a booster oil inlet valve located between the second accumulator and the rodless chamber of the booster oil cylinder; the piston rod of the booster oil cylinder can extend into the rodless chamber of the injection oil cylinder; The controller is communicatively connected to the injection quick valve, the quick discharge replenishment valve, the quick discharge proportional valve, and the booster inlet valve, and is configured as follows: Under rapid injection conditions, the rapid injection valve is opened, the rapid discharge replenishment valve is closed, and the rapid discharge proportional valve is controlled to open to a first predetermined degree. Under boosting conditions, the boosting oil inlet valve and the quick discharge replenishment valve are opened, and the quick discharge proportional valve is controlled to open to the second predetermined degree.

2. The injection system for a dual closed-loop die-casting machine according to claim 1, characterized in that, It also includes a third accumulator, a pilot filter, a first pilot check valve, and a second pilot check valve, wherein the third accumulator is connected to the pilot chamber of the fast discharge proportional valve; The pilot filter and the first pilot check valve are connected in series to form a pilot oil inlet branch. The pilot oil inlet branch is located between the first accumulator and the third accumulator. The second pilot check valve and the pilot oil inlet branch are connected in parallel between the first accumulator and the third accumulator. The first pilot check valve is configured to unidirectionally open toward the third accumulator, and the second pilot check valve is configured to unidirectionally open toward the first accumulator.

3. The injection system for a dual closed-loop die-casting machine according to claim 1, characterized in that, The oil discharge circuit also includes an overflow valve, the oil inlet of which is connected to the rod chamber of the injection cylinder, and the oil outlet of which is connected to the oil tank.

4. The injection system for a dual closed-loop die-casting machine according to claim 1, characterized in that, It also includes a system oil source and a starting pre-pressure oil circuit, wherein the starting pre-pressure oil circuit includes a hammer pre-valve located between the system oil source and the rodless chamber of the injection cylinder; The controller is further configured to: during the startup phase, open the hammer front valve and the fast discharge replenishment valve, and close the fast discharge proportional valve.

5. The injection system for a dual closed-loop die casting machine according to claim 4, characterized in that, The pre-pressurization oil circuit also includes a hammer-front check valve, which is located between the outlet of the hammer-front valve and the rodless chamber of the injection cylinder, and is configured to unidirectionally flow toward the rodless chamber of the injection cylinder.

6. The injection system for a dual closed-loop die-casting machine according to claim 5, characterized in that, The injection oil circuit also includes a high-pressure isolation valve, which is located between the injection quick valve and the rodless chamber of the injection cylinder. The oil inlet of the high-pressure isolation valve is connected to the oil outlet of the injection quick valve, and the oil outlet of the high-pressure isolation valve is connected to the rodless chamber of the injection cylinder. The oil outlet of the hammer-front check valve is connected to the oil inlet of the high-pressure isolation valve.

7. The injection system for a dual closed-loop die-casting machine according to claim 4, characterized in that, It also includes an injection retraction oil circuit, which includes a hammer inlet valve located between the system oil source and the rod chamber of the injection cylinder, and a hammer return valve located between the rodless chamber of the injection cylinder and the oil tank. The controller is further configured to open the hammer rear oil inlet valve and the hammer rear oil return valve when the ejection condition is underway.

8. The injection system for a dual closed-loop die-casting machine according to claim 7, characterized in that, The ejection oil circuit also includes a hammer-back check valve, which is located between the oil outlet of the hammer-back oil inlet valve and the rod chamber of the injection cylinder, and is configured to unidirectionally guide toward the rod chamber of the injection cylinder.

9. The injection system for a dual closed-loop die casting machine according to claim 7, characterized in that, The booster oil circuit also includes a hydraulically controlled return check valve, which is arranged between the rodless chamber of the booster cylinder and the oil tank.

10. The injection system for a dual closed-loop die-casting machine according to claim 9, characterized in that, The pilot chamber of the hydraulic return check valve is connected to the oil outlet of the hammer-fed inlet valve.

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