Vacuum pumping hydraulic drive system and die casting machine

Abstract

The application discloses a vacuum-pumping hydraulic driving system and a die-casting machine, and relates to the technical field of die-casting forming. The vacuum-pumping hydraulic driving system comprises a driving oil cylinder and a normally open electromagnetic valve. The driving oil cylinder comprises a rod cavity and a rodless cavity. The normally open electromagnetic valve is arranged in an oil path between the rod cavity and a system oil source. When the normally open electromagnetic valve is switched to an electrified state, the oil path between the rod cavity and the system oil source is closed. When the normally open electromagnetic valve is reset to a power-off state, the oil path between the rod cavity and the system oil source is opened. The power-off state reset speed of the normally open electromagnetic valve is faster than the electrified state switching speed. When the oil path between the rod cavity and the system oil source is opened, the die-casting machine is switched to a vacuum-pumping stop mode. The technical scheme provided by the application can effectively shorten the response time between the vacuum-pumping stop instruction sent by the hydraulic driving system and the actual action of the driving oil cylinder.

Description

Technical Field

[0001] This invention relates to the field of die casting technology, and in particular to a vacuum hydraulic drive system and a die casting machine. Background Technology

[0002] In the die-casting process, to eliminate internal porosity, improve the density and heat treatment performance of the castings, a vacuum treatment is often performed on the mold cavity before injection filling. Currently, the mainstream control method for vacuuming in die-casting machines is the use of an active hydraulic vacuum valve. Specifically, the two flow ports of the hydraulic vacuum valve are connected to the die-casting machine mold cavity and the vacuum pump, respectively. When the hydraulic vacuum valve is open, the vacuuming channel between the two is connected to perform the vacuuming action; when the hydraulic vacuum valve is closed, the vacuuming channel between the two is disconnected to stop the vacuuming action. The control principle of the hydraulic vacuum valve is to control the switching of oil inlet and outlet between the rod chamber and the rodless chamber of an external drive cylinder, causing the piston rod connected to the valve core of the hydraulic vacuum valve to extend and retract, thereby controlling the opening and closing of the hydraulic vacuum valve.

[0003] The actual operation of the aforementioned drive cylinder is highly dependent on the performance of its hydraulic drive system. This requires a response time in milliseconds between the hydraulic drive system issuing a vacuum stop command and the actual action of the drive cylinder. This ensures that the hydraulic vacuum valve closes precisely before the rapid filling process begins, thus stopping the vacuuming operation of the die-casting machine. This approach aims to maximize the vacuuming time to achieve sufficient vacuum while preventing the high-temperature molten aluminum from being drawn into the vacuum channel during filling, which could cause the mechanism to jam and fail. For these reasons, shortening the response time between the hydraulic drive system issuing a vacuum stop command and the actual action of the drive cylinder has become a key research and development focus for die-casting manufacturers.

[0004] It should be noted that the above content is only used to help understand the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this invention is to propose a vacuum hydraulic drive system and a die-casting machine, which aims to effectively shorten the response time between the issuance of a vacuum stop command by the hydraulic drive system and the actual action of the drive cylinder.

[0006] To achieve the above objectives, this invention proposes a vacuum hydraulic drive system for use in die-casting machines; specifically, the vacuum hydraulic drive system includes: The hydraulic cylinder includes a rod chamber and a rodless chamber; A normally open solenoid valve is disposed in the oil passage between the rod chamber and the system oil source; the normally open solenoid valve is configured to close the oil passage between the rod chamber and the system oil source when switched to the energized state; and to open the oil passage between the rod chamber and the system oil source when reset to the de-energized state; wherein the de-energized state reset speed of the normally open solenoid valve is faster than its energized state switching speed; When the oil circuit between the rod chamber and the system oil source is opened, and the oil circuit between the rodless chamber and the return oil tank is opened, the die-casting machine switches to the vacuum stop mode.

[0007] In one embodiment, the vacuum pumping hydraulic drive system includes: The main control valve includes a main oil inlet, a main oil return port, a first oil port, and a second oil port; the main oil inlet is connected to the system oil source, and the main oil return port is connected to the return oil tank. The secondary control valve includes a secondary oil inlet, a secondary oil return port, and a third oil port; the secondary oil inlet is connected to the second oil port, the secondary oil return port is connected to the oil return tank, and the third oil port is connected to the rodless chamber. A first check valve is disposed in the oil passage between the first oil port and the rod chamber, and the first check valve is disposed in parallel with the normally open solenoid valve; the unidirectional flow direction of the first check valve points to the first oil port. The normally open solenoid valve is located in the oil passage between the first oil port and the rod chamber; Wherein, when the main control valve is switched to the first state, the main oil inlet is connected to the first oil port, and the main oil return port is connected to the second oil port; and when the secondary control valve is switched to the first state, the secondary oil return port is connected to the third oil port; and when the normally open solenoid valve is reset to the de-energized state, the die-casting machine is switched to the vacuum stop mode. Specifically, when the main control valve is switched to the second state, the main oil inlet is connected to the second oil port, and the main oil return port is connected to the first oil port; when the secondary control valve is switched to the second state, the secondary oil inlet is connected to the third oil port; and when the normally open solenoid valve is switched to the energized state, the die-casting machine is switched to the vacuum opening mode.

[0008] In one embodiment, when the die-casting machine switches to the vacuum stop mode, the switching time of the secondary control valve to the first state, the switching time of the main control valve to the first state, and the switching time of the normally open solenoid valve to the energized state (pre-positioned in the oil inlet cut-off state) are all earlier than the time of switching to the vacuum stop mode; and the switching time of the normally open solenoid valve to the energized state is earlier than the switching time of the main control valve and the secondary control valve to the first state.

[0009] In one embodiment, when the die-casting machine switches to the vacuum opening mode, the normally open solenoid valve switches to the energized state earlier than the time it switches to the vacuum opening mode.

[0010] In one embodiment, the vacuum hydraulic drive system includes an accumulator, the connection end of which is connected to the oil circuit between the system oil source and the main oil inlet.

[0011] In one embodiment, the vacuum hydraulic drive system includes a pressure gauge, a pressure gauge shut-off valve, and an energy storage pressure sensor. The pressure gauge is connected to the connection end of the energy storage device, and the pressure gauge shut-off valve is located in the oil circuit between the pressure gauge and the energy storage device. The energy storage pressure sensor is connected to the connection end of the energy storage device.

[0012] In one embodiment, the vacuum hydraulic drive system includes a pressure relief valve disposed in the oil passage between the accumulator and the return oil tank; the pressure relief valve is configured to close the oil passage between the accumulator and the return oil tank when switched to the energized state.

[0013] In one embodiment, the vacuum hydraulic drive system includes a pressure reducing valve, which is disposed in the oil passage between the system oil source and the main oil inlet.

[0014] In one embodiment, the vacuum hydraulic drive system includes a second check valve, which is disposed in the oil passage between the pressure reducing valve and the main oil inlet; the unidirectional flow direction of the second check valve is directed towards the main oil inlet.

[0015] To achieve the above objectives, the present invention proposes a die-casting machine, wherein the die-casting machine employs a vacuum hydraulic drive system as described in any of the preceding claims.

[0016] The technical solution of this invention employs a normally open solenoid valve with a reset speed faster than its switching speed in the energized state as the oil inlet control valve for the rod chamber. When the vacuum stop command is issued, the normally open solenoid valve is controlled to reset to the de-energized state to open the oil passage between the rod chamber and the system oil source. Utilizing the inherent millisecond-level short-time response characteristic of the reset spring's instantaneous release of energy when the normally open solenoid valve resets due to de-energization, it replaces the electromagnetic force establishment delay inherent in the existing technology where the solenoid valve relies on energized switching. This significantly shortens the response time from the issuance of the vacuum stop command to the actual action of the driving cylinder. This allows the die-casting machine to maximize the vacuum time before injection filling to obtain sufficient vacuum, ensuring the internal quality and heat treatment performance of the casting, and to reliably close the vacuum channel before the instantaneous filling of high-temperature molten aluminum, preventing molten aluminum from being drawn in and causing the mechanism to jam and fail. The structure is simple and highly practical. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of one embodiment of the vacuum hydraulic drive system provided by the present invention; Figure 2 A second schematic diagram of an embodiment of the vacuum hydraulic drive system provided by the present invention (the die-casting machine switches to the vacuum stop mode). Figure 3 The third schematic diagram of an embodiment of the vacuum hydraulic drive system provided by the present invention (the die casting machine switches to the vacuum start mode).

[0019] Explanation of reference numerals in the attached figures: 1. Drive cylinder; 101. Rod chamber; 102. Rodless chamber; 103. Piston rod; 2. Hydraulic vacuum valve; 201. Valve seat; 202. Valve core; 203. Flow port; 3. Normally open solenoid valve; 4. System oil source; 5. Return oil tank; 8. Main control valve; 9. Secondary control valve; 10. First check valve; 11. Accumulator; 12. Pressure gauge; 13. Pressure gauge shut-off valve; 14. Accumulated pressure sensor; 15. Pressure relief valve; 16. Pressure reducing valve; 17. Second check valve; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, it should be noted that the descriptions involving "first," "second," etc., in this invention 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. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0023] In existing technologies, the actual movement of the drive cylinder is highly dependent on the performance of its hydraulic drive system. This requires a response time in milliseconds between the hydraulic drive system issuing a vacuum stop command and the actual movement of the drive cylinder. This ensures that the hydraulic vacuum valve closes precisely before the rapid filling process begins, thus stopping the vacuuming operation of the die-casting machine. This approach aims to maximize the vacuuming time to achieve sufficient vacuum while preventing the high-temperature molten aluminum from being drawn into the vacuum channel during filling, which could cause the mechanism to jam and fail. Therefore, shortening the response time between the hydraulic drive system issuing a vacuum stop command and the actual movement of the drive cylinder has become a key research and development focus for die-casting manufacturers.

[0024] To address the aforementioned technical problems, this invention proposes a vacuum hydraulic drive system.

[0025] Please see Figures 1 to 2 In one embodiment of the present invention, the vacuum hydraulic drive system is applied to a die-casting machine; specifically, the vacuum hydraulic drive system includes: The drive cylinder 1 includes a rod chamber 101 and a rodless chamber 102; A normally open solenoid valve 3 is installed in the oil passage between the rod chamber 101 and the system oil source 4. The normally open solenoid valve 3 is configured to close the oil passage between the rod chamber 101 and the system oil source 4 when switched to the energized state, and to open the oil passage between the rod chamber 101 and the system oil source 4 when reset to the de-energized state. The de-energized state reset speed of the normally open solenoid valve 3 is faster than its energized state switching speed. When the oil circuit between the rod chamber 101 and the system oil source 4 is opened, and the oil circuit between the rodless chamber 102 and the return oil tank 5 is opened, the die-casting machine switches to the vacuum stop mode.

[0026] The technical solution of this invention uses a normally open solenoid valve 3, whose de-energized reset speed is faster than its energized switching speed, as the oil inlet control valve for the rod chamber 101. When the vacuum stop command is issued, the normally open solenoid valve 3 is de-energized and reset to the de-energized state to open the oil passage between the rod chamber 101 and the system oil source 4. The millisecond-level short-time response characteristic inherent in the instantaneous release of the energy stored in the reset spring when the normally open solenoid valve 3 is de-energized replaces the electromagnetic force establishment delay that exists in the prior art where the solenoid valve relies on energized switching. This significantly shortens the response time from the issuance of the vacuum stop command to the actual action of the driving cylinder 1. This allows the die casting machine to maximize the vacuum time before injection filling to obtain sufficient vacuum to ensure the internal quality and heat treatment performance of the casting, and to reliably close the vacuum channel before the instantaneous filling of high-temperature aluminum liquid to avoid aluminum liquid entrapment causing the mechanism to jam and fail. The structure is simple and highly practical.

[0027] It should be noted that the normally open solenoid valve 3 resets faster in the de-energized state than it switches faster in the energized state. This is due to the fundamental difference in the source of driving force and the energy process between the two: during energized switching, the solenoid valve core's movement relies on the gradual establishment of electromagnetic force after the electromagnet is energized. However, the current in the electromagnetic coil, as an inductive load, cannot change abruptly and requires a millisecond delay to rise to a level sufficient to overcome the resistance of the reset spring and the inertia of the solenoid valve core. This is a gradual input and accumulation process of energy from electrical energy to magnetic energy and then to mechanical energy. Furthermore, the electromagnetic force must perform work throughout the entire process to drive the solenoid valve core to complete its stroke, hence the longer time. During de-energized reset, the solenoid valve... The driving force that the core relies on to return to its initial position is not built from zero, but comes from the elastic potential energy that the return spring has stored in advance during the compression process. The electromagnetic force disappears immediately when the power is lost, and the spring force is released instantaneously to drive the solenoid valve core to move. This is a mechanical process of instantaneous energy release without electrical delay, so the response is extremely fast. The present invention is based on the utilization of this inherent characteristic, and configures the vacuum stop command to control the normally open solenoid valve 3 to reset when it is de-energized instead of switching when it is energized. Thus, the mechanical response of instantaneous energy release replaces the electromagnetic response of gradual energy accumulation, and the action delay of the solenoid valve is greatly reduced.

[0028] Understandably, the hydraulic vacuum valve 2 includes a valve seat 201, a valve core 202, and two flow ports 203 on the valve seat 201. The two flow ports 203 are respectively connected to the die-casting machine mold cavity and the vacuum pump to form a vacuuming channel. The piston rod 103 of the drive cylinder 1 and the valve core 202 of the hydraulic vacuum valve 2 are telescopically connected so that the telescopic movement of the piston rod 103 can drive the valve core 202 to move in the valve seat 201. When the piston rod 103 extends, the flow port 203 connected to the die-casting machine mold cavity opens, and the vacuum pump performs a vacuuming operation on the die-casting machine mold cavity. When the piston rod 103 retracts, the flow port 203 connected to the die-casting machine mold cavity closes, and the vacuuming stops. When the system receives a vacuum stop command, the normally open solenoid valve 3 is de-energized and resets to the de-energized state to open the oil inlet passage from the rod chamber 101 to the system oil source 4. At the same time, other valves control the opening of the return passage from the rodless chamber 102 to the return oil tank 5. As a result, hydraulic oil enters the rod chamber 101 and pushes the piston toward the rodless chamber 102, so that the piston drives the piston rod 103 to retract. The hydraulic oil in the rodless chamber 102 then flows back to the return oil tank 5, thereby driving the hydraulic vacuum valve 2 to switch to the closed state, realizing the switching of the die-casting machine to the vacuum stop mode.

[0029] As a preferred embodiment of the above embodiments, the vacuum hydraulic drive system includes: The main control valve 8 includes a main oil inlet P1, a main oil return port T1, a first oil port A1, and a second oil port B1; the main oil inlet P1 is connected to the system oil source 4, and the main oil return port T1 is connected to the return oil tank 5; in this embodiment, the main control valve 8 is configured as a three-position four-way directional valve. Secondary control valve 9 includes a secondary oil inlet P2, a secondary oil return port T2, and a third oil port A2; the secondary oil inlet P2 is connected to the second oil port B1, the secondary oil return port T2 is connected to the return oil tank 5, and the third oil port A2 is connected to the rodless chamber 102; in this embodiment, the above-mentioned secondary control valve 9 is configured as a two-position three-way directional valve. The first check valve 10 is disposed in the oil passage between the first oil port A1 and the rod chamber 101, and the first check valve 10 is disposed in parallel with the normally open solenoid valve 3; the unidirectional conduction direction of the first check valve 10 is directed towards the first oil port A1. The normally open solenoid valve 3 is located in the oil passage between the first oil port A1 and the rod chamber 101; Among them, as attached Figure 2 As shown, when the main control valve 8 is switched to the first state, the main oil inlet P1 is connected to the first oil port A1, and the main oil return port T1 is connected to the second oil port B1; and when the secondary control valve 9 is switched to the first state, the secondary oil return port T2 is connected to the third oil port A2; and when the normally open solenoid valve 3 is reset to the de-energized state, the die-casting machine is switched to the vacuum stop mode. Among them, as attached Figure 3As shown, when the main control valve 8 is switched to the second state, the main oil inlet P1 is connected to the second oil inlet B1, and the main oil return port T1 is connected to the first oil inlet A1; and when the secondary control valve 9 is switched to the second state, the secondary oil inlet P2 is connected to the third oil inlet A2; and when the normally open solenoid valve 3 is switched to the energized state, the die-casting machine is switched to the vacuum opening mode.

[0030] With this configuration, when the system executes the vacuum stop mode, the main control valve 8 switches to the first state, connecting the main inlet P1 to the first port A1 and the main return port T1 to the second port B1. The secondary control valve 9 switches to the first state, connecting the secondary return port T2 to the third port A2 to connect the rodless chamber 102 to the return oil tank 5 for pressure relief. The normally open solenoid valve 3, due to power failure and reset, opens the oil passage between the first port A1 and the rod chamber 101, allowing the system hydraulic oil to flow sequentially through the main inlet P1 of the main control valve 8, the first port A1, and the normally open solenoid valve 3 into the rod chamber 101. Meanwhile, some of the hydraulic fluid in the rodless chamber 102 flows back to the return oil tank 5 through the third port A2 and the secondary return port T2 of the secondary control valve 9. The combination of these two actions retracts the piston rod 103 of the drive cylinder 1, thereby closing the hydraulic vacuum valve 2 connected to it, and the die-casting machine switches to the vacuum stop mode. When the system executes the vacuum opening mode, the main control valve 8 switches to the second state, connecting the main oil inlet P1 with the second oil port B1 and the main oil return port T1 with the first oil port A1. The secondary control valve 9 switches to the second state, connecting the secondary oil inlet P2 with the third oil port A2, so that the hydraulic oil of the system flows sequentially through the main oil inlet P1 and the second oil port B1 of the main control valve 8, and the secondary oil inlet P2 and the third oil port A2 of the secondary control valve 9 into the rodless chamber 102. The normally open solenoid valve 3 switches to the energized state and closes the oil circuit between the first oil port A1 and the rod chamber 101, so that the hydraulic oil in the rod chamber 101 can only be discharged to the first oil port A1 through the unidirectional direction of the first check valve 10, and then flow back to the oil tank 5 through the main oil return port T1. The combination of the two realizes the extension of the piston rod 103 of the driving cylinder 1, thereby opening the hydraulic vacuum valve 2 connected to it, and the die-casting machine switches to the vacuum opening mode.

[0031] As a preferred embodiment of the above, when the die-casting machine switches to the vacuum stop mode, the switching time of the normally open solenoid valve 3 to the energized state, the switching time of the secondary control valve 9 to the first state, and the switching time of the main control valve 8 to the first state are earlier than the time of switching to the vacuum stop mode; and the switching time of the normally open solenoid valve 3 to the energized state is earlier than the switching time of the main control valve 8 and the secondary control valve 9 to the first state. With this configuration, before the die-casting machine switches to the vacuum stop mode, the normally open solenoid valve 3 is first switched to the energized state, and then the secondary control valve 9 and the main control valve 8 are switched to the first state. That is, the normally open solenoid valve 3 is switched to the energized state first, then the secondary control valve 9 and the main control valve 8 are switched to the first state, and finally, when the vacuum stop mode is reached, the normally open solenoid valve 3 is reset to the de-energized state, so that the die-casting machine switches to the vacuum stop mode. This ensures that the oil return passage from the rodless chamber 102 to the oil return tank 5 is pre-established before the hydraulic vacuum valve 2 closes, and the pressure from the first oil port A1 to the oil inlet of the normally open solenoid valve 3 is pre-established, thus ensuring that the pressure is maintained before the vacuum stop command is issued. The bottom eliminates the back pressure of the rodless chamber 102 during the piston retraction process caused by the oil inlet of the rod chamber 101, effectively avoiding problems such as piston start-up obstruction, action delay, or speed instability caused by back pressure interference. This ensures that the drive cylinder 1 smoothly completes the retraction action within a millisecond response time, further improving the start-up speed and action consistency of the hydraulic vacuum valve 2 closing. Furthermore, the pre-established pressure only needs to be quickly conducted through the de-energized oil circuit of the normally open solenoid valve 3 when the vacuum closing mode command is issued, and the pressure quickly flows to the rod chamber 101 of the drive cylinder 1. The vacuum response speed is determined by the reset speed of the normally open solenoid valve, not by the energization speed of the main control valve 8, thereby further improving the start-up speed.

[0032] As a preferred embodiment of the above, when the die-casting machine switches to the vacuum opening mode, the normally open solenoid valve 3 switches to the energized state earlier than the switching time to the vacuum opening mode. With this configuration, the normally open solenoid valve 3 is pre-energized before the die-casting machine switches to the vacuum opening mode; that is, after the normally open solenoid valve 3 switches to the energized state, the main control valve 8 switches to the second state and the secondary control valve 9 switches to the second state, so that the die-casting machine switches to the vacuum opening mode, thereby achieving the pre-closing function of the oil inlet passage of the normally open solenoid valve 3. Before the vacuum opening action is executed, the normally open solenoid valve 3 is energized in advance, cutting off the oil circuit between the rod chamber 101 and the normally open solenoid valve 3 in advance. This prevents the hydraulic oil in the rod chamber 101 from flowing back to the rod chamber 101 through the normally open solenoid valve 3 after passing through the first check valve 10, thus avoiding lag in the action of the drive cylinder 1 or disordered pressure distribution, ensuring the reliability and timing accuracy of the vacuum opening action.

[0033] As a preferred embodiment of the above, the vacuum hydraulic drive system includes an accumulator 11, the connection end of which is connected to the oil circuit between the system oil source 4 and the main oil inlet. This configuration, by placing the accumulator 11 between the system oil source 4 and the main oil inlet of the main control valve 8, and connecting the connection end of the accumulator 11 to the system oil circuit, enables a high-flow-rate instantaneous supply capability. During vacuum stop mode, the drive cylinder 1 needs to retract rapidly, creating a peak demand for hydraulic fluid flow. The accumulator 11 pre-stores hydraulic oil, and at the moment the normally open solenoid valve 3 de-energizes and resets to open the oil inlet channel of the rod chamber 101, it can immediately release the stored hydraulic fluid to meet the high-flow-rate instantaneous demand of the rod chamber 101. This overcomes the defect of relying solely on the system oil source 4 pump for oil supply, which limits the cylinder's action speed due to lag in flow response, ensuring that the retraction time of the piston rod 103 of the drive cylinder 1 meets the millisecond-level requirement.

[0034] The aforementioned accumulator 11 is configured as either a bladder-type accumulator or a diaphragm-type accumulator. Their common working principle is to store hydraulic energy using the compressibility of gas. When the system pressure increases, the hydraulic oil compresses the gas (usually nitrogen) inside the bladder or diaphragm and enters the accumulator 11 to store energy. When the system requires a large instantaneous flow, the compressed gas rapidly expands, quickly pushing the hydraulic oil out. This ensures that the stored pressure oil is released at a millisecond-level response time the vacuum stop command is issued, thereby ensuring that the normally open solenoid valve 3, after completing its high-speed reset, can immediately obtain sufficient flow to retract into the rodless chamber 102 of the driving cylinder 1.

[0035] Furthermore, the vacuum hydraulic drive system includes a pressure gauge 12, a pressure gauge shut-off valve 13, and an energy storage pressure sensor 14. The pressure gauge 12 is connected to the connection end of the accumulator 11, and the pressure gauge shut-off valve 13 is located in the oil circuit between the pressure gauge 12 and the accumulator 11. The energy storage pressure sensor 14 is connected to the connection end of the accumulator 11. This configuration, by including the pressure gauge 12, the pressure gauge shut-off valve 13, and the energy storage pressure sensor 14, constitutes a complete pressure monitoring and display unit for the energy storage system. The pressure gauge shut-off valve 13 facilitates the safe isolation of the pressure gauge 12 during equipment maintenance. The pressure gauge 12 provides a local visual pressure reading, while the energy storage pressure sensor 14 feeds back the pressure signal to the control system in real time. This achieves both local display and remote monitoring of the energy storage pressure, enabling operators and the control system to monitor the energy storage status in real time and provide timely warnings or interlock protection in case of abnormal pressure, ensuring the long-term safety and maintainability of the equipment.

[0036] As a preferred embodiment of the above, the vacuum hydraulic drive system includes a pressure relief valve 15, which is located in the oil circuit between the accumulator 11 and the return oil tank 5. The pressure relief valve 15 is configured to close the oil circuit between the accumulator 11 and the return oil tank 5 when switched to the energized state. This configuration, by setting the pressure relief valve 15 between the accumulator 11 and the return oil tank 5, and closing the oil circuit from the accumulator 11 to the return oil tank 5 when the pressure relief valve 15 is switched to the energized state, ensures reliable pressure maintenance of the accumulator 11 during normal equipment operation. When the equipment is shut down or requires maintenance, the pressure relief valve 15 switches to de-energized switching, automatically draining the residual hydraulic oil in the accumulator 11 back to the return oil tank 5. This eliminates the safety hazards caused by long-term pressurized storage of the accumulator 11, prevents accidental release of high-pressure oil during maintenance that could cause personal injury or equipment damage, significantly improves the operational safety of the entire machine during shutdown maintenance, and meets the inherent safety design requirements of industrial equipment.

[0037] As a preferred embodiment of the above, the vacuum hydraulic drive system includes a pressure reducing valve 16, which is located in the oil circuit between the system oil source 4 and the main oil inlet. This configuration, by placing the pressure reducing valve 16 between the system oil source 4 and the main oil inlet of the main control valve 8, enables precise adjustment and control of the hydraulic oil pressure entering the main control valve 8 and subsequent execution circuits. The pressure reducing valve 16 stabilizes the high-pressure hydraulic oil supplied by the system oil source 4 within the allowable working pressure range of the drive cylinder 1 and each valve component, preventing impact damage to precision components such as the valve core 202 and the seals of the drive cylinder 1 caused by system pressure fluctuations or excessive pressure. Simultaneously, it provides a stable charging pressure to the accumulator 11, ensuring the consistency of the accumulator 11's energy storage pressure, thereby guaranteeing the stability and consistency of the response speed in the vacuum stop mode.

[0038] Furthermore, the vacuum hydraulic drive system includes a second check valve 17, which is located in the oil passage between the pressure reducing valve 16 and the main oil inlet. The unidirectional flow direction of the second check valve 17 points towards the main oil inlet. This configuration, by placing the second check valve 17 between the pressure reducing valve 16 and the main oil inlet of the main control valve 8, and with its unidirectional flow direction pointing towards the main oil inlet, achieves backflow protection for the pressure reducing valve 16 and the oil passage on the system oil source 4 side. When the vacuum stop mode is executed, the instantaneous large flow of oil released by the accumulator 11 enters the rod chamber 101 through the main control valve 8. During this process, if the main control valve 8 switches or the system oil source 4 pressure drops instantaneously, the second check valve 17 can prevent the high-pressure oil released by the accumulator 11 from flowing back to the pressure reducing valve 16 and the system oil source 4 side. This avoids backflow causing impact damage to the pressure reducing valve 16 and ensures that all the hydraulic oil released by the accumulator 11 is used to drive the retraction action of the cylinder 1, improving the system's operating efficiency and reliability.

[0039] This invention also discloses a die-casting machine, including the vacuum hydraulic drive system of any of the above embodiments. The specific structure of the vacuum hydraulic drive system can be found in the above embodiments. Since this die-casting machine adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0040] It should be noted that the vacuum hydraulic drive system and other contents of the die-casting machine disclosed in this invention are prior art and will not be described in detail here.

[0041] The above are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. Any application of the present invention directly or indirectly in other related technical fields is included within the patent protection scope of the present invention.

Claims

1. A vacuum hydraulic drive system, applied to a die-casting machine; characterized in that, include: The hydraulic cylinder includes a rod chamber and a rodless chamber; A normally open solenoid valve is configured such that when switched to the energized state, the oil passage between the rod chamber and the system oil source is closed; and when reset to the de-energized state, the oil passage between the rod chamber and the system oil source is opened; wherein the de-energized state reset speed of the normally open solenoid valve is faster than its energized state switching speed. When the oil circuit between the rod chamber and the system oil source is opened, and the oil circuit between the rodless chamber and the return oil tank is opened, the die casting machine switches to the vacuum stop mode. The main control valve includes a main oil inlet, a main oil return port, a first oil port, and a second oil port; the main oil inlet is connected to the system oil source, and the main oil return port is connected to the return oil tank. The secondary control valve includes a secondary oil inlet, a secondary oil return port, and a third oil port; the secondary oil inlet is connected to the second oil port, the secondary oil return port is connected to the oil return tank, and the third oil port is connected to the rodless chamber. A first check valve is disposed in the oil passage between the first oil port and the rod chamber, and the first check valve is disposed in parallel with the normally open solenoid valve; the unidirectional flow direction of the first check valve points to the first oil port. The normally open solenoid valve is located in the oil passage between the first oil port and the rod chamber; Wherein, when the main control valve is switched to the first state, the main oil inlet is connected to the first oil port, and the main oil return port is connected to the second oil port; and when the secondary control valve is switched to the first state, the secondary oil return port is connected to the third oil port; and when the normally open solenoid valve is reset to the de-energized state, the die-casting machine is switched to the vacuum stop mode. When the main control valve is switched to the second state, the main oil inlet is connected to the second oil port, and the main oil return port is connected to the first oil port; when the secondary control valve is switched to the second state, the secondary oil inlet is connected to the third oil port; and when the normally open solenoid valve is switched to the energized state, the die-casting machine is switched to the vacuum opening mode. When the die-casting machine switches to the vacuum stop mode, the switching time of the secondary control valve to the first state, the switching time of the main control valve to the first state, and the switching time of the normally open solenoid valve to the energized state are all earlier than the time of switching to the vacuum stop mode; and the switching time of the normally open solenoid valve to the energized state is earlier than the switching time of the main control valve and the secondary control valve to the first state. When the die-casting machine switches to the vacuum opening mode, the normally open solenoid valve switches to the energized state earlier than the time it switches to the vacuum opening mode.

2. The vacuum pumping hydraulic drive system as described in claim 1, characterized in that: The vacuum hydraulic drive system includes an accumulator, the connection end of which is connected to the oil circuit between the system oil source and the main oil inlet.

3. The vacuum pumping hydraulic drive system as described in claim 2, characterized in that: The vacuum hydraulic drive system includes a pressure gauge, a pressure gauge shut-off valve, and an energy storage pressure sensor. The pressure gauge is connected to the connection end of the energy storage device, and the pressure gauge shut-off valve is located in the oil circuit between the pressure gauge and the energy storage device. The energy storage pressure sensor is connected to the connection end of the energy storage device.

4. The vacuum pumping hydraulic drive system as described in claim 2, characterized in that: The vacuum hydraulic drive system includes a pressure relief valve, which is located in the oil circuit between the accumulator and the return oil tank; the pressure relief valve is configured to close the oil circuit between the accumulator and the return oil tank when switched to the energized state.

5. The vacuum pumping hydraulic drive system as described in claim 1, characterized in that: The vacuum hydraulic drive system includes a pressure reducing valve, which is located in the oil circuit between the system oil source and the main oil inlet.

6. The vacuum pumping hydraulic drive system as described in claim 5, characterized in that: The vacuum hydraulic drive system includes a second check valve, which is located in the oil passage between the pressure reducing valve and the main oil inlet; the unidirectional flow direction of the second check valve is towards the main oil inlet.

7. A die-casting machine, characterized in that: The die-casting machine employs the vacuum hydraulic drive system as described in any one of claims 1 to 6.

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