Hydraulic pressure relief system and cubic press applying the same
By employing parallel hydraulic motors and energy recovery devices in the six-sided top press, the problems of poor pressure relief and energy waste have been solved, achieving an efficient and stable pressure relief process and energy recovery, reducing costs and extending equipment life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SENAIM (SHANDONG) MATERIAL TECH CO LTD
- Filing Date
- 2025-08-25
- Publication Date
- 2026-06-23
AI Technical Summary
The existing six-sided top press has an unsatisfactory depressurization effect during the depressurization process. The filter plate structure increases material costs and has poor cooling effect, which cannot fully recover and utilize pressure energy, resulting in damage to hydraulic cylinders and a shortened life of the whole machine.
By using a parallel-connected hydraulic motor and energy recovery device, pressure energy is converted into electrical energy and stored in the energy storage module. The hydraulic motor throttles and dampens the high-pressure oil circuit, eliminating the need for a complex filtration structure, thus achieving smooth pressure relief and energy recovery.
It achieves an efficient and stable pressure relief process, reduces material and production costs, extends the life of hydraulic cylinders, improves energy efficiency and system thermal balance, and meets the requirements of green and environmentally friendly production.
Smart Images
Figure CN224396804U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of hydraulic technology, and in particular to a hydraulic pressure relief system and a six-sided top press using the pressure relief system. Background Technology
[0002] A six-sided top press is a type of hot press with six working cylinders that creates an extreme environment in a closed chamber to transform samples through heating and pressurization. It utilizes high temperature and pressure to synthesize superhard materials (such as diamond and cubic boron nitride). During depressurization, such high pressure forces the pressurized oil back into the tank, converting most of the energy into heat, causing the oil temperature to rise rapidly. If this high-temperature pressurized oil flows back into the tank without cooling, it will then flow back into the hydraulic cylinders during pressurization, damaging the cylinders and severely impacting the lifespan of the press.
[0003] For example, Chinese utility model patent CN219171788U, entitled "An Improved Manual Pressure Relief Device for a Six-Sided Top Press," includes a press, a hydraulic working cylinder mounted on the press, an ultra-high pressure two-position seven-way valve, a three-way valve, a hydraulic check valve, a hydraulic pump, a manual pressure relief valve, and a recovery oil tank. In daily use, the manual pressure relief valve is closed, and the hydraulic pump is started to inject pressurized oil into the ultra-high pressure two-position seven-way valve through the hydraulic check valve and three-way valve. The pressurized oil is then injected into the hydraulic working cylinder through its six connecting pipes, causing it to extend and retract, using the top hammer to press the diamond composite block. In case of electrical control system failure or power outage, the pressure relief valve is manually adjusted by the worker to recover the pressurized oil into the recovery oil tank. Because the pressure is high at this time, a buffer pressure filter plate is installed in the recovery oil tank to effectively offset the pressure during pressure relief.
[0004] However, the existing technology still has the following drawbacks:
[0005] In the current six-sided top press, the pressure relief operation is offset by a filter plate installed in the recovery oil tank. However, the filter plate can only offset a portion of the pressure relief, resulting in an unsatisfactory pressure relief effect. Installing the filter plate in the recovery tank requires setting up two layers of metal plates, machining filter holes, and adding filter cotton, which increases material and production costs. In addition, the pressure relief method using the filter plate is not ideal for cooling the pressure oil during the pressure relief process, and it cannot fully recover and utilize the pressure energy of the pressure oil. Utility Model Content
[0006] In order to overcome the shortcomings of the existing technology, one of the objectives of this utility model is to provide a hydraulic pressure relief system.
[0007] One of the objectives of this utility model is achieved through the following technical solution: a hydraulic pressure relief system, comprising a booster, a hydraulic motor, an energy recovery device, a hydraulically controlled check valve, a solenoid directional valve, and a return oil tank. The booster is connected to the input end of the hydraulically controlled check valve. At least two hydraulic motors are provided and connected in parallel. The output ends of the two hydraulically controlled check valves are connected to the inlet ends of the hydraulic motors. The outlet ends of the two hydraulic motors are connected to the solenoid directional valve. When the coil of the solenoid directional valve is energized, it delivers pressurized oil to the return oil tank. The hydraulic motor is also connected to the energy recovery device for converting the pressure energy of the pressurized oil into electrical energy and storing it in the energy recovery device.
[0008] Furthermore, the hydraulic motor includes a first hydraulic motor and a second hydraulic motor, which are connected in parallel. The energy recovery device includes a generator and an energy storage module. The output shafts of the first and second hydraulic motors are drivenly connected to the input shaft of the generator. The generator is electrically connected to the energy storage module for charging or drawing power from the energy storage module.
[0009] Furthermore, the oil outlets of the first hydraulic motor and the second hydraulic motor are connected to a first check valve, and are connected to the solenoid directional valve through the first check valve.
[0010] Furthermore, the solenoid directional valve is a three-position four-way solenoid directional valve. When the system is depressurized, the left coil of the solenoid directional valve is energized, so that the pressure oil from the first hydraulic motor and the second hydraulic motor flows back to the return oil tank in sequence through the first check valve and the solenoid directional valve.
[0011] Furthermore, the hydraulic control check valve is connected to a ball solenoid valve. When the system is depressurized, the coil of the ball solenoid valve is energized and controls the hydraulic control check valve to open.
[0012] Furthermore, the hydraulically controlled check valve is connected in parallel with a second check valve. The input end of the second check valve is connected to the solenoid directional valve, and the output end is connected to the booster. When the system is pressurized, the right coil of the solenoid directional valve is energized, so that the pressure oil returning to the oil tank is delivered to the booster through the second check valve, and the coil of the ball solenoid valve is de-energized to keep the hydraulically controlled check valve closed.
[0013] Furthermore, the electromagnetic reversing valve is connected to a plunger pump, and the pressure oil returning to the oil tank is pumped to the booster sequentially through the electromagnetic reversing valve and the second check valve via the plunger pump.
[0014] Furthermore, the booster is connected to a one-way throttle valve, and is connected to the input end of the hydraulically controlled one-way valve through the one-way throttle valve.
[0015] Furthermore, the hydraulic check valve is connected in parallel with a manual pressure relief valve, the input end of which is connected to the booster and the output end of which is connected to the return oil tank.
[0016] Compared with existing technologies, the advantages of this hydraulic pressure relief system are as follows: the pressure relief oil circuit of the hydraulic pressure relief system is equipped with two or more hydraulic motors connected in parallel, which in turn generate significant throttling and damping effects on the high-pressure oil circuit, cools and depressurizes the oil, provides a controllable and stable pressure relief path, avoids hydraulic shock, and the pressure relief and shock resistance effects are far superior to the traditional filter plate structure. In addition, the complex filter plate, multi-layer metal plate and filter cotton structure inside the return oil tank are eliminated, simplifying the manufacturing process of the return oil tank and significantly reducing material costs and production costs.
[0017] Furthermore, the two hydraulic motors are connected to an energy recovery device, which converts the pressure energy of the hydraulic oil during the depressurization process into electrical energy for storage, achieving efficient and full recovery and utilization of energy. This improves the energy efficiency of the entire press system, meets the requirements of green and environmentally friendly production, and the hydraulic oil does work when flowing through the hydraulic motor. Its internal energy (mainly heat energy) is partially converted into mechanical energy and electrical energy, which helps to reduce the oil temperature, improve the thermal balance of the system, avoid damage caused by high-temperature pressure oil entering the hydraulic cylinder, and extend the service life of the entire machine.
[0018] In order to overcome the shortcomings of the existing technology, the second objective of this utility model is to provide a six-sided top press.
[0019] The second objective of this utility model is achieved by the following technical solution: a six-sided top press, including the hydraulic pressure relief system, wherein the working cylinder of the six-sided top press is connected to the pipeline of the hydraulic pressure relief system, and the hydraulic pressure relief system performs pressure relief and pressure increase actions on the six-sided top press.
[0020] Compared with the prior art, the beneficial effects of this six-sided top press are as follows: The six-sided top press provided in this application embodiment has its six working cylinders connected to the output end of the intensifier. Under the pressure boosting action of the intensifier, ultra-high pressure oil is provided to each working cylinder to generate the ultra-high pressure required for the composite block. Moreover, the pressure boosting and depressurization actions are uniformly controlled by the central controller. In particular, the pressure energy of the pressure oil is efficiently recovered and utilized through the parallel connected hydraulic motors, and the thermal balance of the whole system is improved, ensuring the high-efficiency operation of the whole machine, thereby reducing the overall energy consumption and improving the product yield. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the pressure oil unloading circuit of the six-sided top press in a preferred embodiment of the present invention;
[0022] Figure 2 This is a schematic diagram of the pressure oil booster circuit of the six-sided top press in a preferred embodiment of the present invention.
[0023] In the picture:
[0024] 10. Intensifier; 20. Hydraulic check valve; 30. First hydraulic motor; 31. Second hydraulic motor; 40. Generator; 50. Energy storage module; 60. Solenoid directional valve; 70. Return oil tank; 80. First check valve; 81. Second check valve; 90. Ball solenoid valve; 100. Piston pump; 200. One-way throttle valve; 300. Manual pressure relief valve. Detailed Implementation
[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0026] like Figure 1-2 As shown, a hydraulic pressure relief system is provided, which utilizes high temperature and high pressure to synthesize superhard materials (such as diamond and cubic boron nitride). During the hydraulic pressure relief process, the pressure energy of the pressure oil can be recovered and utilized, fundamentally solving the problems of poor pressure relief effect, high cost and energy waste.
[0027] The hydraulic pressure relief system includes a booster 10, at least two hydraulic motors connected in parallel, an energy recovery device, a hydraulically controlled check valve 20, a solenoid directional valve 60, and a return oil tank 70. The output of the booster 10 is connected to the input of the hydraulically controlled check valve 20, and the output of the hydraulically controlled check valve 20 is connected to the inlet of each of the two parallel hydraulic motors. The outlets of the two hydraulic motors are combined and connected to one working port (e.g., port A) of the solenoid directional valve 60, and the return port (port T) of the solenoid directional valve 60 is connected to the return oil tank 70. Furthermore, the output shaft of the hydraulic motor is mechanically connected to the input shaft of the energy recovery device.
[0028] Therefore, when pressure relief is needed, there is no need to install shock-resistant structures such as filter plates in the return oil tank 70. Instead, the oil is guided to the hydraulic motor. The high-pressure oil drives the hydraulic motor to rotate, converting its pressure energy and kinetic energy into mechanical energy. The rotational output of the hydraulic motor then drives the energy recovery device (such as the generator 40) to work, further converting the mechanical energy into electrical energy, which is then stored in the energy storage module 50 such as a battery. This not only achieves smooth and efficient pressure relief but also recovers energy that would otherwise be wasted.
[0029] In the embodiments of this application, the hydraulic motor can be two, three or more hydraulic motors connected in parallel to adapt to different flow and power pressure relief requirements.
[0030] Thus, in this embodiment of the hydraulic pressure relief system, two or more hydraulic motors are connected in parallel in the pressure relief oil circuit. The hydraulic motors then generate significant throttling and damping effects on the high-pressure oil circuit, thereby cooling and depressurizing the oil. This provides a controllable and stable pressure relief path, avoids hydraulic shock, and the pressure relief and shock resistance effects are far superior to the traditional filter plate structure. Furthermore, the complex filter plate, multi-layer metal plate, and filter cotton structure inside the return oil tank 70 are eliminated, simplifying the manufacturing process of the return oil tank 70 and significantly reducing material and production costs.
[0031] Furthermore, the two hydraulic motors are connected to an energy recovery device, which converts the pressure energy of the hydraulic oil during the depressurization process into electrical energy for storage. This achieves efficient and full recovery and utilization of energy, improves the energy efficiency of the entire press system, meets the requirements of green and environmentally friendly production, and the hydraulic oil does work when flowing through the hydraulic motor. Its internal energy (mainly heat energy) is partially converted into mechanical energy and electrical energy, which helps to reduce the oil temperature, improve the thermal balance of the system, avoid damage caused by high-temperature pressure oil entering the hydraulic cylinder, and extend the service life of the whole machine.
[0032] The hydraulic motors provided in this application include a first hydraulic motor 30 and a second hydraulic motor 31 connected in parallel, and the energy recovery device includes a generator 40 and an energy storage module 50 (such as a battery pack, supercapacitor, etc.). More specifically, the output shafts of the first hydraulic motor 30 and the second hydraulic motor 31 are connected to the input shaft of the generator 40 via a coupling, gearbox, or belt transmission mechanism. The power output terminal of the generator 40 is electrically connected to the energy storage module 50, and the type of energy storage module 50 can be selected as needed.
[0033] The system employs a dual-motor parallel design to ensure that the two motors rotate at the same speed, resulting in stable voltage during power generation. This design also allows for the diversion of high-pressure, high-flow-rate oil, reducing the performance requirements of individual components and thus improving the system's reliability and flexibility. The generator 40 converts mechanical energy into electrical energy, which is then stored by the energy storage module 50 for later use, such as powering the top press, pumps, solenoid valves, or other auxiliary equipment within the system, or even feeding it back to the power grid.
[0034] Thus, by using the parallel design of the first hydraulic motor 30 and the second hydraulic motor 31, and the connection with the generator 40 and the energy storage module 50, the adaptability of the hydraulic pressure relief system to different flow conditions is enhanced, ensuring the stability and efficiency of pressure relief, realizing the specific energy conversion of the top press during the pressure relief process, and clarifying the energy recovery path of pressure energy → mechanical energy → electrical energy → chemical energy / electrical energy.
[0035] In this embodiment of the application, a first check valve 80 is provided on the oil outlet line of the first hydraulic motor 30 and the second hydraulic motor 31. The output end of the first check valve 80 is connected to the left position of the solenoid directional valve 60. After the left coil of the solenoid directional valve 60 is energized, the first check valve 80 is connected to the return oil tank 70 through the solenoid directional valve 60.
[0036] By setting the first check valve 80, the direction of oil flow during pressure relief is clearly defined, preventing oil from flowing back to the hydraulic motor from the direction of the solenoid directional valve 60 when not under pressure relief conditions (such as system pressurization), which could cause the motor to reverse or generate unnecessary agitation. This protects the hydraulic motor, avoids energy loss and potential interference, ensures normal pressure relief operation of the system, and further improves the stability of system operation.
[0037] The electromagnetic directional valve 60 in this embodiment is a three-position four-way electromagnetic directional valve 60. When the system is depressurized, its P port is closed, its A port is connected to the oil circuit after the first check valve 80, its T port is connected to the return oil tank 70, and its B port can be used for other functions. A ball solenoid valve 90 (e.g., a normally closed two-position two-way solenoid valve) is connected to the control oil circuit of the hydraulic check valve 20. The inlet of the ball solenoid valve 90 is led from the high-pressure oil circuit of the booster 10, and the outlet is connected to the control oil port of the hydraulic check valve 20.
[0038] When the system is depressurized, the coil of the ball solenoid valve 90 is first energized to open it. High-pressure oil then flows through the ball solenoid valve 90 to the control port of the hydraulic check valve 20, opening it and connecting the booster 10 to the high-pressure oil circuit of the hydraulic motor. Next, the left coil of the three-position four-way solenoid directional valve 60 is energized, switching the valve core to the left position. At this time, low-pressure oil from the hydraulic motor flows smoothly back to the oil tank 70 through the channel from port A to port T, completing the depressurization circuit.
[0039] Therefore, by controlling the opening and closing sequence of the ball solenoid valve 90 and the solenoid directional valve 60 with electrical signals, precise automated control is achieved, which ensures that the hydraulic check valve 20 opens first and the pressure relief circuit is established later. This improves the response speed, avoids hydraulic shock, and ensures that the pressure relief process is smooth and controllable.
[0040] In this embodiment, a second check valve 81 is connected in parallel to the hydraulic control check valve 20, the first check valve 80, and the hydraulic motor. The input end (i.e., the outlet) of the second check valve 81 is connected to the booster 10, and the output end (i.e., the inlet) is connected to the B port of the solenoid directional valve 60. The P port of the solenoid directional valve 60 is connected to a plunger pump 100. The oil suction port of the plunger pump 100 extends into the return oil tank 70 for pumping pressurized oil.
[0041] When system pressurization is required, the right coil of the three-position four-way solenoid directional valve 60 is energized, and the valve core switches to the right position. Simultaneously, the coil of the ball solenoid valve 90 is de-energized and closes, cutting off the control oil circuit of the pilot-operated check valve 20, keeping it closed. Because the pilot-operated check valve 20 is closed, high-pressure oil will not flow back into the pressure relief circuit, thus preventing pressure oil from flowing back to the hydraulic motor during pressurization, avoiding damage to the hydraulic motor and preventing the booster 10 from failing to pressurize or maintain pressure. At this time, the plunger pump 100 can be started to pump the pressure oil from the return oil tank 70, through the P port of the solenoid directional valve 60 to the B port, and then push open the second check valve 81 to deliver it to the booster 10, replenishing the booster 10 with oil and driving its operation.
[0042] Therefore, the embodiments of this application not only solve the system depressurization problem, but also provide a complete pressurization oil circuit, forming a closed-loop hydraulic control system; by closing the hydraulic control check valve 20 and the one-way nature of the second check valve 81, the high-pressure working circuit and the depressurization / energy recovery circuit are effectively isolated when the system is pressurized, ensuring the independence and reliability of their respective functions, and further improving the overall operational stability of the system.
[0043] In this embodiment, a one-way throttle valve 200 is connected in series in the pipeline between the booster 10 and the hydraulically controlled one-way valve 20 / second one-way valve 81. This one-way throttle valve 200 is used to regulate the flow rate and velocity of the high-pressure oil entering the pressure relief circuit, thereby controlling the pressure relief rate and achieving a smooth and adjustable pressure relief process. Its one-way function allows the oil to pass through unimpeded during pressurization. The one-way throttle valve 200 also adopts an electro-proportional throttle valve to achieve more precise computer control.
[0044] In addition, a manual pressure relief valve 300 is connected in parallel to the hydraulic check valve 20, the first check valve 80, the hydraulic motor, and the second check valve 81. The input end of the manual pressure relief valve 300 is connected to the booster 10 side via a one-way throttle valve 200, and the output end is connected back to the return oil tank 70. This manual pressure relief valve 300 serves as a safety precaution; in the event of an electrical system failure or the need for emergency manual intervention, it can be manually opened to directly release high-pressure oil to the return oil tank 70, thereby ensuring the safety of the system and personnel.
[0045] Therefore, a one-way throttle valve 200 is installed in the circuit of the booster 10. By adjusting the one-way throttle valve 200, the depressurization speed can be precisely controlled to meet the depressurization requirements of different processes. In addition, by setting a manual depressurization valve 300, an emergency safety passage is provided, which maximizes the safety and reliability of the entire system.
[0046] A six-sided top press is also provided. This application embodiment applies the aforementioned hydraulic pressure relief system to the six-sided top press. According to the prior art, this six-sided top press typically includes six working cylinders. The output end of the booster 10 of the hydraulic pressure relief system is connected to the oil inlet chambers of the six working cylinders, and oil is supplied to the six-sided top press through the return oil tank 70 to provide ultra-high pressure oil to the working cylinders to generate the ultra-high pressure required for the synthetic blocks. In practical applications, the central controller of the six-sided top press centrally controls its boosting and depressurizing actions, thereby reducing overall energy consumption and improving product yield.
[0047] The booster, solenoid valve, check valve, directional valve, hydraulic motor, etc. in the embodiments of this application are all based on existing technology, and no specific restrictions or related descriptions are made on their models or specifications here.
[0048] The pressurization and depressurization process of the six-sided top press provided in this embodiment is as follows:
[0049] I. Pressurization process:
[0050] 1. The central controller issues a pressurization command;
[0051] 2. When the right coil of the solenoid directional valve 60 is energized for 2CT (the left coil is de-energized for 1CT), the valve core moves to the right position;
[0052] 3. The ball solenoid valve 90 closes when de-energized, and the hydraulic check valve 20 remains closed due to the lack of control oil pressure;
[0053] 4. When the plunger pump 100 starts, it draws oil from the return oil tank 70. The pumped pressure oil pushes open the second check valve 81 through the solenoid directional valve 60 (P→B port) and enters the lower chamber of the booster 10.
[0054] 5. Under the drive of pressurized oil, the intensifier 10 pressurizes the oil and delivers it to the six working cylinders of the six-sided top press, pushing the top hammer to complete the pressurization action.
[0055] During the system pressurization process, the pressure relief circuit is isolated from the high-pressure main oil circuit due to the closure of the hydraulic control check valve 20 and the first check valve 80, so the system pressurization process will not affect the pressure relief circuit.
[0056] II. Depressurization and Energy Recovery Process:
[0057] 1. The central controller issues a pressure relief command;
[0058] 2. First step: The coil 3CT of the ball solenoid valve 90 is energized and opens first, and the high-pressure oil in the main oil circuit enters the control oil port of the hydraulic control check valve 20, opening it.
[0059] 3. Second step: The left coil of the solenoid directional valve 60 is energized for 1 CT (the right coil is de-energized for 2 CT), and the valve core moves to the left position;
[0060] 4. The ultra-high pressure oil in the working cylinder and high pressure pipeline of the six-sided top press can enter the first hydraulic motor 30 and the second hydraulic motor 31 in parallel through the opened hydraulic control check valve 20, driving the two hydraulic motors to rotate at the same speed; the rotation of the two hydraulic motors consumes the pressure energy of the oil and reduces its pressure and temperature.
[0061] 5. The oil outlets of the two hydraulic motors (now low-pressure oil) converge at the first check valve 80, and then flow back to the oil tank 70 through the solenoid directional valve 60 (A→T port); at the same time, the output shafts of the first hydraulic motor 30 and the second hydraulic motor 31 drive the generator 40 to rotate and generate electricity, and the generated electrical energy is stored in the energy storage module 50.
[0062] During the system depressurization process, the depressurization rate can be set by adjusting the one-way throttle valve 200 at the oil outlet of the booster 10 to ensure smooth system depressurization. In case of emergency, the manual depressurization valve 300 can be opened at any time to force depressurization and ensure the safe operation of the whole system.
[0063] Through the above working process, the system efficiently and smoothly completed the depressurization of the six-sided top press, improved the finished product flatness rate, and efficiently and fully recovered the pressure energy of the oil, saving energy and promoting green production.
[0064] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.
Claims
1. A hydraulic pressure relief system, characterized by, It includes a booster, a hydraulic motor, an energy recovery device, a hydraulically controlled check valve, a solenoid directional valve, and a return oil tank. The booster is connected to the input end of the hydraulically controlled check valve, and two or more hydraulic motors are connected in parallel. The output ends of the two hydraulic check valves are connected to the oil inlet of the hydraulic motor, and the oil outlet of the two hydraulic motors are connected to the solenoid directional valve. After the coil of the solenoid directional valve is energized, it delivers the pressurized oil to the return oil tank. The hydraulic motor is also connected to an energy recovery device, which converts the pressure energy of the hydraulic oil into electrical energy and stores it in the energy recovery device.
2. The hydraulic pressure relief system as described in claim 1, characterized in that, The hydraulic motor includes a first hydraulic motor and a second hydraulic motor, which are connected in parallel. The energy recovery device includes a generator and an energy storage module. The output shafts of the first and second hydraulic motors are connected to the input shaft of the generator. The generator is electrically connected to the energy storage module for charging the energy storage module.
3. The hydraulic pressure relief system as described in claim 2, characterized in that, The oil outlets of the first hydraulic motor and the second hydraulic motor are connected to a first check valve, and are connected to the solenoid directional valve through the first check valve.
4. The hydraulic pressure relief system as described in claim 3, characterized in that, The solenoid directional valve is a three-position four-way solenoid directional valve. When the system is depressurized, the left coil of the solenoid directional valve is energized, so that the pressure oil from the first hydraulic motor and the second hydraulic motor flows back to the return oil tank through the first check valve and the solenoid directional valve in sequence.
5. The hydraulic pressure relief system as described in claim 4, characterized in that, The hydraulic control check valve is connected to a ball solenoid valve. When the system is depressurized, the coil of the ball solenoid valve is energized and controls the hydraulic control check valve to open.
6. The hydraulic pressure relief system as described in claim 5, characterized in that, The hydraulically controlled check valve is connected in parallel with a second check valve. The input end of the second check valve is connected to the solenoid directional valve, and the output end is connected to the booster. When the system is pressurized, the right coil of the solenoid directional valve is energized so that the pressure oil returning to the oil tank is delivered to the booster through the second check valve, and the ball solenoid valve coil is de-energized to keep the hydraulically controlled check valve closed.
7. The hydraulic pressure relief system as described in claim 6, characterized in that, The solenoid directional valve is connected to a plunger pump, and the pressure oil returning to the oil tank is pumped to the booster sequentially through the solenoid directional valve and the second check valve via the plunger pump.
8. The hydraulic pressure relief system according to any one of claims 1-7, characterized in that, The booster is connected to a one-way throttle valve, and is connected to the input end of the hydraulically controlled one-way valve through the one-way throttle valve.
9. The hydraulic pressure relief system as described in claim 8, characterized in that, The hydraulic check valve is connected in parallel with a manual pressure relief valve. The input end of the manual pressure relief valve is connected to the booster, and the output end is connected to the return oil tank.
10. A six-sided top press, characterized in that, The system includes the hydraulic pressure relief system according to any one of claims 1-9, wherein the working cylinder of the six-sided top press is connected to the hydraulic pressure relief system, and the hydraulic pressure relief system performs pressure relief and pressure increase actions on the six-sided top press.