Marine hydraulic machine control system and method
By combining the main hydraulic pump and the electro-hydraulic directional valve, the flow rate and motion state are automatically adjusted, solving the problems of high energy consumption and complex structure of traditional hydraulic presses, and realizing efficient and energy-saving hydraulic press control.
Patent Information
- Application Number
- CN202511953258.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2045-12-23
AI Technical Summary
Traditional large hydraulic presses are large in size, heavy in weight, consume a lot of energy, and have complex structures and accessories. They are also used infrequently and have a limited range of applications, which cannot meet the diverse development requirements of modern ships.
The main hydraulic pump supplies hydraulic oil, and the main hydraulic pump is started under no-load through the neutral position of the first and second electro-hydraulic directional valves. The flow rate and motion state are automatically adjusted by the change of system working pressure, and the motion process is optimized by the electrical control unit to reduce energy consumption.
It achieves efficient operation of the hydraulic press, meets process requirements, saves energy, has a simple structure, and reduces equipment weight and space occupation.
Smart Images
Figure CN121676508B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated control system protection technology, and in particular to a control system and method for a marine hydraulic press. Background Technology
[0002] Hydraulic presses, as a fundamental piece of equipment on ships, play a vital role in ship operation. With technological advancements and manufacturing progress, the shipbuilding industry increasingly demands higher efficiency and economy from hydraulic presses. The main movements of a hydraulic press are those of the upper slide mechanism and the lower slide ejection mechanism. The upper slide mechanism is driven by the main hydraulic cylinder, while the ejection mechanism is driven by the ejection cylinder. The upper slide mechanism, guided by four guide pillars and driven by the main cylinder, achieves a cycle of "rapid descent → slow pressurization → pressure holding delay → rapid return → stop in place." The lower cylinder, located in the center hole of the worktable, drives the lower slide ejection mechanism to achieve two cycles: "upward ejection → downward retraction" or "floating pressure edge descent → stop → ejection." The hydraulic system of the hydraulic press is primarily pressure-controlled, characterized by high pressure, high flow rate, and high power.
[0003] Traditional large hydraulic presses are characterized by their large size, weight, high energy consumption, and complex structure and components. Their disadvantages, such as low usage frequency, limited application range, heavy weight, and difficulty in portability, no longer meet the increasingly diverse requirements of modern shipbuilding. Therefore, this paper proposes a marine hydraulic press control system and method to address these issues. Summary of the Invention
[0004] The purpose of this invention is to provide a control system and method for a marine hydraulic press to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a marine hydraulic press control system, comprising: The main hydraulic cylinder has a filling valve in its upper chamber and an oil tank at the discharge end of the filling valve. The lower chamber of the main hydraulic cylinder is equipped with a first back pressure valve and a hydraulically controlled check valve. A servo pump is connected to the drain end of the oil tank. The servo pump includes a main hydraulic pump and an auxiliary pump. The outlet pipe of the main hydraulic pump is equipped with a first electro-hydraulic directional valve. Port A of the first electro-hydraulic directional valve is equipped with a protective check valve. The outlet pipe of the protective check valve is connected to the upper chamber of the main hydraulic cylinder. Port B of the first electro-hydraulic directional valve is connected to the outlet pipes of the first back pressure valve and the hydraulic control check valve. Port T of the first electro-hydraulic directional valve is equipped with a second electro-hydraulic directional valve. Port T of the second electro-hydraulic directional valve is connected to the inlet of the filling valve. A hydraulic control unit is disposed between the main hydraulic cylinder and the servo pump; An electrical control unit is used for electrical connection control of the system.
[0006] Preferably, the inlet of the main hydraulic pump is equipped with an oil filter, and the inlet of the oil filter is connected in a through connection with the outlet of the oil tank.
[0007] Preferably, the hydraulic control unit includes: The pilot-operated relief valve is connected to the P port of the pilot-operated relief valve and the P port of the first electro-hydraulic directional valve through the outlet pipeline of the main hydraulic pump, and the T port of the pilot-operated relief valve is connected to the oil tank inlet. A remote pressure regulating valve, wherein the P port of the remote pressure regulating valve is connected to the K port of the pilot-operated relief valve, and the T port of the remote pressure regulating valve is connected to the inlet of the oil tank. A pressure relay, wherein the P port of the pressure relay is connected in a through connection with the A port of the first electro-hydraulic directional valve and the P1 port of the protective check valve.
[0008] Preferably, the hydraulic control unit further includes: The hydraulic slide valve is connected to the P1 port of the filling valve, the P2 port of the first back pressure valve, the P1 port of the hydraulic control check valve, and the B port of the first electro-hydraulic directional valve. The T port of the hydraulic slide valve is connected to the inlet of the oil tank. The A port of the hydraulic slide valve is equipped with a pilot-operated sequence valve. The L port of the pilot-operated sequence valve is connected to the inlet of the oil tank. The first pressure gauge is connected in series between the P1 port of the filling valve and the hydraulic slide valve.
[0009] Preferably, the T-port of the first back pressure valve is connected to the inlet of the oil tank, and a displacement sensor group is connected to the piston rod of the main hydraulic cylinder. The displacement sensor group is used to indicate the output position of the main hydraulic cylinder.
[0010] Preferably, the outlet pipeline of the auxiliary pump is equipped with a first relief valve, the T port of the first relief valve is connected to the inlet of the oil tank, the P port of the first relief valve is connected to a solenoid directional valve, the P port of the solenoid directional valve is connected to the P port of a second electro-hydraulic directional valve, a second pressure gauge is connected in series between the P port of the solenoid directional valve and the P port of the first relief valve, the T port of the solenoid directional valve is connected to the inlet of the oil tank, and the P1 port of the hydraulic control check valve is connected to the A port of the solenoid directional valve.
[0011] Preferably, the T port of the second electro-hydraulic directional valve is connected in series with the inlet of the oil tank, the A port of the second electro-hydraulic directional valve is provided with an ejector cylinder, the rodless chamber of the ejector cylinder is connected in series with the B port of the second electro-hydraulic directional valve, the rodless chamber of the ejector cylinder is provided with a second relief valve, the T port of the second relief valve is connected in series with the inlet of the oil tank, the P port of the second relief valve is provided with a second back pressure valve, and a third pressure gauge and a throttle valve are connected in series between the P port of the second relief valve and the P port of the second back pressure valve.
[0012] Preferably, the electrical control unit includes a main hydraulic cylinder control circuit, a downward control circuit, a pressure holding circuit, and an ejector cylinder actuation circuit; The main hydraulic cylinder control circuit includes a start button SB2 and a start contactor KM1 coil of the main hydraulic pump connected in series between the live wire and the neutral wire of the control power supply. The upper terminal of the start button SB2 and the upper terminal of the start contactor KM1 coil are connected across the normally open contact of the main hydraulic pump start contactor KM1. The lower terminal of the normally open contact of KM1 and the neutral wire are connected in series with the normally closed contact of the pressure relay KP, the fast down button SB3 and the coil of the first contactor KA1. The lower terminal of the normally closed contact of KP and the neutral wire are connected in series with the normally open contact of KA1, the normally closed contact of the limit switch SQ2 and the coil of the fifth contactor KA5. The lower terminal of the fast down button SB3 is electrically connected to the upper terminal of the limit switch SQ2. The downlink control circuit includes the normally open contact of pressure relay KP, the normally closed contact of KA2, and the coil of energizing delay time relay KT, which are connected in series between the normally open contact of KM1, the lower terminal, and the neutral line. The voltage holding circuit includes the normally open contact of the second contactor KA2, the normally closed contact of the limit switch SQ1, and the coil of the second contactor KA2 connected in series between the normally open contact of the second contactor KA2 and the normally closed contact of the limit switch SQ1. The normally open contact of the energizing delay time relay KT is connected across the normally open contact of the second contactor KA2 and the normally closed contact of the limit switch SQ1.
[0013] Preferably, the ejector cylinder action circuit includes a cylinder stop button SB4, a normally closed contact of KA1, a normally closed contact of KA2, a normally open contact of KA3, a normally closed contact of KA4, a normally closed contact of limit switch SQ3, and a coil of KA3 connected in series between the lower terminal of the normally open contact of KM1 and the neutral wire. A cylinder ejection button SB5 is connected across the upper terminal of the normally open contact of KA3 and the upper terminal of the normally closed contact of KA4. A normally open contact of KA1, a normally open contact of KA2, a normally open contact of KA4, a normally closed contact of KA3, a normally closed contact of limit switch SQ4, and a coil of KA4 are connected in series between the upper terminal of the normally closed contact of KA1 and the neutral wire. A cylinder retraction button SB6 is connected across the upper terminal of the normally open contact of KA4 and the upper terminal of the normally closed contact of KA3.
[0014] A control method for a marine hydraulic press, employing the aforementioned marine hydraulic press control system, includes the following steps: The first step is to start under no-load conditions. The main hydraulic pump supplies oil to the hydraulic control unit. All the electromagnets in the solenoid directional valve and the hydraulic control unit are de-energized. The pressure oil output by the main hydraulic pump flows through the neutral position of the first electro-hydraulic directional valve and the neutral position of the second electro-hydraulic directional valve, and finally flows back to the oil tank. The hydraulic press starts under no-load conditions. In the second step, the main cylinder moves downward, the first electro-hydraulic directional valve and the solenoid directional valve are energized, and the control oil opens the hydraulic check valve through the solenoid directional valve. The pressurized oil flows from the main hydraulic pump through the right position of the first electro-hydraulic directional valve and the protection check valve in sequence, enters the upper chamber of the main hydraulic cylinder, and then flows from the lower chamber of the main hydraulic cylinder through the hydraulic check valve, the right position of the first electro-hydraulic directional valve and the middle position of the second electro-hydraulic directional valve back to the oil tank. The third step is the main cylinder working advance. When the slider of the main hydraulic cylinder drops to the 2S position of the displacement sensor group, the solenoid directional valve is de-energized and reset, the hydraulic control check valve and the filling valve are closed, and the pressure oil in the lower chamber of the main hydraulic cylinder in the return oil circuit flows back to the oil tank through the first back pressure valve, the right position of the first electro-hydraulic directional valve and the middle position of the second electro-hydraulic directional valve. The fourth step is the main cylinder pressure holding. When the pressure in the upper chamber of the main hydraulic cylinder reaches the preset value of the pressure relay, the first electro-hydraulic directional valve is de-energized and switched to the neutral position. During the preset 10-second pressure holding period, the pressure oil in the upper and lower chambers of the main hydraulic cylinder enters a closed state, and the pressure oil in the main hydraulic pump flows back to the oil tank in sequence through the first electro-hydraulic directional valve and the second electro-hydraulic directional valve. Fifth step, after the pressure holding process of the main cylinder is depressurized, the first electro-hydraulic directional valve is energized, and the pressure oil passes through the left position of the first electro-hydraulic directional valve and the upper position of the hydraulic slide valve in sequence, opening the pilot sequence valve. The pressure oil of the main hydraulic pump of the solenoid directional valve flows back to the oil tank through the pilot sequence valve. At the same time, the unloading core of the filling valve is opened, so that the pressure oil in the upper chamber of the main hydraulic cylinder flows back to the oil tank through the opening of the unloading core of the filling valve, and then the pressure in the upper chamber of the main hydraulic cylinder decreases. Step 6, main cylinder return stroke. When the pressure value in the upper chamber of the main hydraulic cylinder drops to the set value, the pilot sequence valve closes, the main hydraulic pump opens the filling valve, and the pressure oil in the inlet oil circuit of the solenoid directional valve flows through the left position of the first electro-hydraulic directional valve and the hydraulic control check valve into the lower chamber of the main hydraulic cylinder. The pressure oil in the return oil circuit flows back to the oil tank from the upper chamber of the main hydraulic cylinder through the filling valve. Step 7: The main cylinder stops. When the slider of the main hydraulic cylinder touches the displacement sensor group for 1 second, the first electro-hydraulic directional valve is de-energized, the hydraulic control check valve closes the lower chamber of the main hydraulic cylinder, and the pressure oil output by the main hydraulic pump flows back to the oil tank through the middle position of the first electro-hydraulic directional valve and the middle position of the second electro-hydraulic directional valve. Step 8: The ejector cylinder ejects. The ejector cylinder moves after the main hydraulic cylinder stops moving. The second electro-hydraulic directional valve of the solenoid directional valve remains energized. The pressurized oil in the inlet circuit flows into the lower chamber of the ejector cylinder through the main hydraulic pump, the middle position of the first electro-hydraulic directional valve, and the left position of the second electro-hydraulic directional valve in sequence. The pressurized oil in the return circuit flows back to the oil tank through the upper chamber of the ejector cylinder and the left position of the second electro-hydraulic directional valve in sequence. Step 9: The ejector cylinder retracts. After the workpiece is removed, the second electro-hydraulic directional valve remains energized, and pressurized oil enters the upper chamber of the ejector cylinder. The pressurized oil in the lower chamber of the ejector cylinder flows back to the oil tank through the right position of the second electro-hydraulic directional valve, and the ejector cylinder piston moves downward to return to its original position.
[0015] The technical effects and advantages of this invention are as follows: This invention employs a main hydraulic pump to supply hydraulic oil. The main hydraulic pump is started under no-load by the neutral position function of the first and second electro-hydraulic directional valves in sequence. When the main hydraulic cylinder and the ejector cylinder stop in their original positions, the main hydraulic pump is unloaded. The output flow of the main hydraulic pump is automatically adjusted to adapt to the motion state of the main hydraulic cylinder by utilizing the changes in working pressure during the system operation. This not only meets the process requirements of the hydraulic press, but also saves energy. Attached Figure Description
[0016] Figure 1 This is a schematic diagram illustrating the connection principle of the hydraulic press control system of the present invention.
[0017] Figure 2 This is a schematic diagram of the electrical control unit of the present invention.
[0018] In the diagram: 1. Oil filter; 2. Main hydraulic pump; 3. Auxiliary pump; 4. First relief valve; 5. Pilot-operated relief valve; 6. First electro-hydraulic directional valve; 7. Remote pressure regulating valve; 8. Pilot-operated sequence valve; 9. Pressure relay; 10. Protective check valve; 11. First pressure gauge; 12. Hydraulic slide valve; 13. Filling valve; 14. Main hydraulic cylinder; 15. First back pressure valve; 16. Hydraulic check valve; 17. Solenoid directional valve; 18. Second electro-hydraulic directional valve; 19. Ejector cylinder; 20. Throttle valve; 21. Second relief valve; 22. Second back pressure valve; 23. Oil tank; 24. Displacement sensor group; 25. Second pressure gauge; 26. Third pressure gauge. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1: The present invention provides as follows Figure 1 The marine hydraulic press control system shown includes: The main hydraulic cylinder 14 has a filling valve 13 in its upper chamber and an oil tank 23 in its drain end. The lower chamber of the main hydraulic cylinder 14 has a first back pressure valve 15 and a hydraulic control check valve 16. A servo pump is connected to the drain end of the oil tank 23. The servo pump includes a main hydraulic pump 2 and an auxiliary pump 3. The outlet pipe of the main hydraulic pump 2 is equipped with a first electro-hydraulic directional valve 6. The A port of the first electro-hydraulic directional valve 6 is equipped with a protective check valve 10. The outlet pipe of the protective check valve 10 is connected to the upper chamber of the main hydraulic cylinder 14. The B port of the first electro-hydraulic directional valve 6 is connected to the outlet pipes of the first back pressure valve 15 and the hydraulic control check valve 16. The T port of the first electro-hydraulic directional valve 6 is equipped with a second electro-hydraulic directional valve 18. The T port of the second electro-hydraulic directional valve 18 is connected to the inlet of the filling valve 13. The inlet of the main hydraulic pump 2 is equipped with an oil filter 1. The inlet of the oil filter 1 is connected to the outlet of the oil tank 23. It should be noted that the main hydraulic pump 2 is used to supply hydraulic oil. The main hydraulic pump 2 is started under no-load by the neutral position function of the first electro-hydraulic directional valve 6 and the second electro-hydraulic directional valve 18 in sequence. When the main hydraulic cylinder 14 and the ejector cylinder 19 stop in their original positions, the main hydraulic pump 2 is unloaded. The output flow of the main hydraulic pump 2 is automatically adjusted to adapt to the movement state of the main hydraulic cylinder 14 by utilizing the change of working pressure during the operation of the system. This not only meets the process requirements of the hydraulic press, but also saves energy.
[0021] The hydraulic control unit is located between the main hydraulic cylinder 14 and the servo pump; Specifically, the hydraulic control unit includes: The pilot-operated relief valve 5 and the outlet pipeline of the main hydraulic pump 2 are connected to the P port of the pilot-operated relief valve 5 and the P port of the first electro-hydraulic directional valve 6. The T port of the pilot-operated relief valve 5 is connected to the inlet of the oil tank 23. The remote pressure regulating valve 7 has its P port connected to the K port of the pilot-operated relief valve 5, and its T port connected to the inlet of the oil tank 23. Pressure relay 9, the P port of pressure relay 9 is connected to the A port of the first electro-hydraulic directional valve 6 and the P1 port of the protective check valve 10. It should be noted that the first electro-hydraulic directional valve 6 is a three-position four-way electro-hydraulic directional valve. The right-position solenoid 1YV and the left-position solenoid 2YV of the first electro-hydraulic directional valve 6 control the upward and downward movement of the main hydraulic cylinder 14, respectively. The hydraulic pump is started first in the hydraulic system to ensure that it has a good working condition. This allows the hydraulic pump to immediately enter normal working condition when the pressure oil circuit is connected. The maximum working pressure of the main hydraulic pump 2 in the hydraulic system is regulated by the remote pressure regulating valve 7 of the pilot-operated relief valve 5. The hydraulic system uses the main hydraulic pump 2 for oil supply and utilizes the weight of the slider to achieve the rapid downward movement of the main hydraulic cylinder 14. The filling valve 13 is used to replenish the hydraulic oil, making the rapid movement circuit simple in structure, using fewer components, and ensuring sufficient oil replenishment. This meets the process requirements and reduces energy consumption. The hydraulic system uses a pressure-holding circuit with a protective check valve 10 and a filling valve 13 to maintain pressure and unload the system. Pressure is maintained in the upper chamber of the hydraulic cylinder while the hydraulic system is unloaded. Therefore, the hydraulic system has high energy efficiency.
[0022] Hydraulic slide valve 12 is connected to the P1 port of filling valve 13, the P2 port of first back pressure valve 15, the P1 port of hydraulic control check valve 16 and the B port of first electro-hydraulic directional valve 6. The T port of hydraulic slide valve 12 is connected to the inlet of oil tank 23. A pilot-operated sequence valve 8 is provided at the A port of hydraulic slide valve 12. The L port of pilot-operated sequence valve 8 is connected to the inlet of oil tank 23. The T-port of the first back pressure valve 15 is connected to the inlet of the oil tank 23. A displacement sensor group 24 is connected to the piston rod of the main hydraulic cylinder 14. The displacement sensor group 24 is used to indicate the output position of the main hydraulic cylinder 14. It should be noted that the hydraulic system uses a protective check valve 10 for pressure holding and a pressure relief circuit consisting of a pilot-operated sequence valve 8 and a filling valve 13 with an unloading valve core. The structure is simple and reduces the hydraulic shock when the main hydraulic cylinder 14 switches from pressure holding to rapid return. The hydraulic system uses a balanced locking circuit consisting of a hydraulically controlled check valve 16 and a pilot-operated sequence valve 8, which allows the slider of the main hydraulic cylinder 14 to stop at any position and to remain in the locked position for a long time.
[0023] The first pressure gauge 11 is connected in series between the P1 port of the filling valve 13 and the hydraulic slide valve 12.
[0024] The outlet pipeline of the auxiliary pump 3 is equipped with a first overflow valve 4. The T port of the first overflow valve 4 is connected to the inlet of the oil tank 23. The P port of the first overflow valve 4 is connected to a solenoid directional valve 17. The P port of the solenoid directional valve 17 is connected to the P port of the second electro-hydraulic directional valve 18. A second pressure gauge 25 is connected in series between the P port of the solenoid directional valve 17 and the P port of the first overflow valve 4. The T port of the solenoid directional valve 17 is connected to the inlet of the oil tank 23. The P1 port of the hydraulic control check valve 16 is connected to the A port of the solenoid directional valve 17.
[0025] It should be noted that the solenoid directional valve 17 is a two-position four-way solenoid valve; when the solenoid 5YV of the solenoid directional valve 17 is not energized, the hydraulic control check valve 16 can only be opened to the left; when the solenoid 5YV of the solenoid directional valve 17 is energized, the hydraulic control check valve 16 can only be opened to the right. The solenoid 5YV of the solenoid directional valve 17 controls the speed of the slider of the main hydraulic cylinder 14; the auxiliary pump 3 in the hydraulic system is used to supply control oil to the hydraulic slide valve 12, and its pressure is adjusted by the relief valve 4.
[0026] The T port of the second electro-hydraulic directional valve 18 is connected to the inlet of the oil tank 23. The A port of the second electro-hydraulic directional valve 18 is provided with an ejector cylinder 19. The rodless chamber of the ejector cylinder 19 is connected to the B port of the second electro-hydraulic directional valve 18. The rodless chamber of the ejector cylinder 19 is provided with a second relief valve 21. The T port of the second relief valve 21 is connected to the inlet of the oil tank 23. The P port of the second relief valve 21 is provided with a second back pressure valve 22. A third pressure gauge 26 and a throttle valve 20 are connected in series between the P port of the second relief valve 21 and the P port of the second back pressure valve 22.
[0027] It should be noted that the second electro-hydraulic directional valve 18 is a three-position four-way electro-hydraulic directional valve; the left-position solenoid 3YV and the right-position solenoid 4YV of the second electro-hydraulic directional valve 18 control the pushing out and pulling back of the ejector cylinder 19, respectively.
[0028] refer to Figure 2As shown in the diagram, the letters represent: FR1 is the thermal relay for hydraulic pump 1; FR2 is the thermal relay for hydraulic pump 2; FU1 is the first fuse; FU2 is the second fuse; FU3 is the third fuse; FU4 is the fourth fuse; SB1 is the main stop button; SB2 is the pump start button; SB3 is the rapid descent button; SB4 is the lower cylinder stop button; SB5 is the lower cylinder ejection button; KM1 is the hydraulic pump start contactor; KT is the energizing delay time relay; KA1 is the first contactor; KA2 is the second contactor; KA3 is the third contactor; KA4 is the fourth contactor; KA5 is the fifth contactor; 1Y is the first electromagnet; 2Y is the second electromagnet; 3Y is the third electromagnet; 4Y is the fourth electromagnet; 5Y is the fifth electromagnet. M1 is servo motor 1; M2 is servo motor 2; SQ1 is the first limit switch; SQ2 is the second limit switch; SQ3 is the third limit switch; SQ4 is the fourth limit switch; TL1 is the first transformer; TL2 is the second transformer; VC is the DC power supply; EL is the lighting lamp; S1 is the lighting lamp switch; KP is the pressure relay 9; QS is the knife switch.
[0029] Electrical control unit: The electrical control unit is used for electrical connection control of the system.
[0030] Specifically, the electrical control unit includes the main hydraulic cylinder 14 control circuit, the downward control circuit, the pressure holding circuit, and the ejector cylinder 19 actuation circuit; The control circuit of the main hydraulic cylinder 14 includes a start button SB2 and a start contactor KM1 coil of the main hydraulic pump 2 connected in series between the live wire and the neutral wire of the control power supply. The upper terminal of the start button SB2 and the upper terminal of the start contactor KM1 coil are connected across the normally open contact of the start contactor KM1 of the main hydraulic pump 2. The lower terminal of the normally open contact of KM1 and the neutral wire are connected in series with the normally closed contact of the pressure relay 9KP, the fast down button SB3 and the coil of the first contactor KA1. The lower terminal of the normally closed contact of KP and the neutral wire are connected in series with the normally open contact of KA1, the normally closed contact of the limit switch SQ2 and the coil of the fifth contactor KA5. The lower terminal of the fast down button SB3 is electrically connected to the upper terminal of the limit switch SQ2. The downlink control circuit includes the normally open contact of pressure relay 9KP, the normally closed contact of KA2, and the coil of energizing delay time relay KT, which are connected in series between the normally open contact of KM1 and the neutral line. The voltage holding circuit includes the normally open contact of the second contactor KA2, the normally closed contact of the limit switch SQ1, and the coil of the second contactor KA2, which are connected in series between the normally open contact of the second contactor KA2 and the normally closed contact of the limit switch SQ1. The normally open contact of the energizing delay time relay KT is connected across the normally open contact of the second contactor KA2 and the normally closed contact of the limit switch SQ1.
[0031] The ejector cylinder 19 operating circuit includes a cylinder stop button SB4, normally closed contacts of KA1, KA2, KA3, and KA4, normally closed contacts of limit switch SQ3, and the coil of KA3 connected in series between the lower terminal of the normally open contact of KM1 and the neutral wire. A cylinder ejection button SB5 is connected across the upper terminal of the normally open contact of KA3 and the upper terminal of the normally closed contact of KA4. A normally open contact of KA1, normally open contact of KA2, normally open contact of KA4, normally closed contact of KA3, normally closed contact of limit switch SQ4, and the coil of KA4 are connected in series between the upper terminal of the normally closed contact of KA1 and the neutral wire. A cylinder retraction button SB6 is connected across the upper terminal of the normally open contact of KA4 and the upper terminal of the normally closed contact of KA3.
[0032] It should be noted that the circuit also includes a lighting circuit. A fuse FU3, a normally closed contact of the thermal relay FR1 of hydraulic pump 1, a normally closed contact of the thermal relay FR2 of hydraulic pump 2, and a main stop button SB1 are connected in series between the upper terminal of the transformer TL2 and the upper terminal of the normally open contact of the hydraulic pump start contactor KM1. A fuse FU4, a lighting switch S1, and a green signal light EL are connected in series between the lower terminal of the transformer TL2 and the coil of the hydraulic pump start contactor KM1. The lower terminals of the transformer TL2, the green signal light EL, and the coil of the hydraulic pump start contactor KM1 are all connected to the protective grounding wire PE. In the main motor control circuit, the main power switch QS is connected in series with the servo motor 1 via a fuse FU1, the normally open contact of the hydraulic pump 1 start contactor KM1, and the thermal relay FR1 of the hydraulic pump 1. The lower terminal of the normally open contact of the hydraulic pump 1 start contactor KM1 is connected in series with the servo motor M2 via a thermal relay FR2 of the hydraulic pump 2. Both the servo motor 1 and the servo motor 2 are connected to the protective grounding wire PE. In the electromagnet circuit, DC transformer TL1 is connected to DC power supply VC. Between the positive and negative terminals of DC power supply VC, a fuse 2, the normally open contact of the first contactor KA1, the normally closed contact of the second contactor KA2, and electromagnet coil 1YV are connected in series. The upper terminal of the normally open contact of the first contactor KA1 and the lower terminal of electromagnet coil 1YV are connected in series with the normally open contact of the second contactor KA2, the normally closed contact of the first contactor KA1, and electromagnet coil 2YV. The upper terminal of the normally open contact of the second contactor KA2 and the lower terminal of electromagnet coil 2YV are connected in series with the third contactor... The normally open contact of contactor KA3, the normally closed contact of the fourth contactor KA4, and the electromagnet coil 3YV are connected in series with the upper terminal of the normally open contact of the third contactor KA3 and the lower terminal of the electromagnet coil 3YV. The normally open contact of the fourth contactor KA4, the normally closed contact of the third contactor KA3, and the electromagnet coil 4YV are connected in series with the upper terminal of the normally open contact of the fourth contactor KA4 and the lower terminal of the electromagnet coil 4YV. The normally open contact of the fifth contactor KA5 and the electromagnet coil 5YV are connected in series with the lower terminal of the normally open contact of the first contactor KA1 and the DC power supply VC. The normally open contact of the first contactor KA1 and the DC power supply VC are connected to the protective grounding wire PE. When the pump start button SB2 is pressed, the coil of the hydraulic pump start contactor KM1 in the hydraulic pump control circuit is energized and closed, the normally open contact of the main hydraulic pump start contactor KM1 is closed, and the normally open contact of the hydraulic pump start contactor KM1 in the motor circuit is closed. At this time, the main hydraulic pump 2 starts to supply oil to the hydraulic system, and the electromagnets 1Y, 2Y, 3Y, 4Y and 5Y in the electrical control circuit system are all de-energized. When the rapid descent button SB3 is pressed, the coils of the first contactor KA1 and the fifth contactor KA5 in the hydraulic pump control circuit are energized and attracted, and the normally open contact of the first contactor KA1 closes; the normally open contacts of the first contactor KA1 and the normally open contacts of the fifth contactor KA5 in the electromagnet group circuit close, and the electromagnet coils 1Y and 5Y are energized and attracted. When the slider of the main hydraulic cylinder 14 descends to the 2S position of the displacement sensor group 24, the trigger signal causes the limit switch SQ2 in the hydraulic pump control circuit to de-energize and open, the coil of the fifth contactor KA5 to de-energize, the normally open contact of the fifth contactor KA5 in the corresponding electromagnet group circuit to de-energize and open, and the electromagnet coil 5Y to de-energize. When the pressure in the upper chamber of the main hydraulic cylinder 14 in the hydraulic control system reaches the preset value of the pressure relay 9, the normally open contact of the pressure relay 9KP in the downlink control circuit is energized and closes, the normally closed contact of the pressure relay KP9 in the hydraulic pump control circuit is energized and opens, the coil of the first contactor KA1 is de-energized and opens, the normally open contact of the first contactor KA1 opens, the normally open contact of the first contactor in the corresponding electromagnet group circuit opens, and the coil of the electromagnet 1Y is de-energized and opens; at this time, the coil of the energizing delay time relay KT is energized and closes, and the normally open contact of the energizing delay time relay KT will not be energized and closed within the preset 10s; After the pressure holding process is completed, that is, after the preset value of 10 seconds, the normally open contact of the energizing delay time relay KT in the pressure holding circuit is energized and closed, the coil of the second contactor KA2 is energized and closed, and its normally open contact is energized and closed; in the corresponding electromagnet group circuit, the normally open contact of the second contactor KA2 is energized and closed, and its electromagnet 2Y coil is energized and closed; in the corresponding downlink control circuit, the normally closed contact of the second contactor KA2 is de-energized and opened, and the coil of the energizing delay time relay KT is de-energized and opened. When the slider of the main hydraulic cylinder 14 touches the displacement sensor group 24 at 1S, the normally closed contact of the limit switch SQ1 in the pressure holding circuit is energized and opens, the coil of the second contactor KA2 is de-energized and opens, and the normally open contact of the second contactor KA2 is de-energized and opens; correspondingly, the normally open contact of the second contactor KA2 in the electromagnet group circuit is de-energized and opens, and the coil of the electromagnet 2Y is de-energized and opens. When the lower cylinder ejection button SB5 is pressed, the coil of the third contactor KA3 in the ejection cylinder 19 action circuit is energized and closed, and its normally open contact is energized and closed; correspondingly, the normally open contact of the third contactor KA3 in the electromagnet group circuit is energized and closed, and the coil of electromagnet 3Y is energized and energized. When the slider of the ejection cylinder 19 ejects and triggers the displacement sensor group 24 at 4S, the normally closed contact of the limit switch SQ3 in the ejection cylinder 19 action circuit is energized and opened, the coil of the third contactor KA3 is de-energized and opened, and its normally open contact is de-energized and closed; correspondingly, the normally open contact of the third contactor KA3 in the electromagnet group circuit is de-energized and opened, and the coil of electromagnet 3Y is de-energized and opened. When the lower cylinder retraction button SB6 is pressed, the coil of the fourth contactor KA4 in the ejector cylinder 19 action circuit is energized and closed, its normally open contact is energized and closed, and its normally closed contact is energized and closed. Correspondingly, in the electromagnet group circuit, the normally open contact of the fourth contactor KA4 is energized and closed, and the coil of electromagnet 4Y is energized and closed. When the slider of the ejector cylinder 19 retracts and triggers the displacement sensor group 24 for 5 seconds, the normally closed contact of the limit switch SQ4 in the ejector cylinder 19 action circuit is energized and opened, the coil of the fourth contactor KA4 is de-energized and opened, its normally open contact is de-energized and opened, and its normally closed contact is de-energized and closed. Correspondingly, in the electromagnet group circuit, the normally open contact of the fourth contactor KA4 is de-energized and opened, and the coil of electromagnet 4Y is de-energized and opened.
[0033] Example 2: This invention provides a control method for a marine hydraulic press, employing a marine hydraulic press control system as described in Example 1. The control method includes the following steps: The first step is to start under no-load conditions. The main hydraulic pump 2 supplies oil to the hydraulic control unit. The solenoid directional valve 17 and the electromagnets in the hydraulic control unit are all de-energized. The pressure oil output by the main hydraulic pump 2 flows through the middle position of the first electro-hydraulic directional valve 6 and the middle position of the second electro-hydraulic directional valve 18, and finally flows back to the oil tank 23. The hydraulic press starts under no-load conditions. It should be noted that when the main hydraulic pump 2 supplies oil to the hydraulic system, all the electromagnets in the hydraulic control system are de-energized. High pressure, high flow rate, constant power variable; the pressurized oil output from the main hydraulic pump 2 flows through the neutral positions of the first electro-hydraulic directional valve 6 and the second electro-hydraulic directional valve 18, and finally flows back to the oil tank 23, allowing the hydraulic press to start under no-load conditions.
[0034] In the second step, the main cylinder moves downward, the first electro-hydraulic directional valve 6 and the solenoid directional valve 17 are energized, and the control oil opens the hydraulic control check valve 16 through the solenoid directional valve 17. The pressurized oil flows from the main hydraulic pump 2 through the right position of the first electro-hydraulic directional valve 6 and the protection check valve 10 in sequence, enters the upper chamber of the main hydraulic cylinder 14, and then flows from the lower chamber of the main hydraulic cylinder 14 through the hydraulic control check valve 16, the right position of the first electro-hydraulic directional valve 6 and the middle position of the second electro-hydraulic directional valve 18 in sequence back to the oil tank 23. It should be noted that when the right electromagnet 1YV of the first electro-hydraulic directional valve 6 and the electromagnet 5YV of the electromagnet directional valve 17 are energized in sequence, the control oil opens the hydraulic control check valve 16 through the right position of the electromagnet directional valve 17. The pressurized oil flows from the main hydraulic pump 2 through the right position of the first electro-hydraulic directional valve 6 and the protection check valve 10 in sequence, and enters the upper chamber of the main hydraulic cylinder 14. At this time, the movable crossbeam of the main hydraulic cylinder 14 descends rapidly under the action of gravity. Although the main hydraulic pump 2 is at its maximum flow rate, it still cannot meet the flow requirements of the upper chamber of the main hydraulic cylinder 14. Therefore, the upper chamber of the main hydraulic cylinder 14 will form a negative pressure state. As a result, the hydraulic oil in the upper oil tank 23 will flow into the upper chamber of the main hydraulic cylinder 14 through the filling valve 13 due to the negative pressure. In the return oil circuit, the pressurized oil flows from the lower chamber of the main hydraulic cylinder 14 through the hydraulic control check valve 16, the right position of the first electro-hydraulic directional valve 6 and the middle position of the second electro-hydraulic directional valve 18 in sequence back to the oil tank 23.
[0035] The third step is the main cylinder working advance. When the slider of the main hydraulic cylinder 14 drops to the 2S position of the displacement sensor group 24, the solenoid directional valve 17 is de-energized and reset, the hydraulic control check valve 16 and the filling valve 13 are closed, and the pressure oil in the lower chamber of the main hydraulic cylinder 14 in the return oil circuit flows back to the oil tank 23 through the first back pressure valve 15, the right position of the first electro-hydraulic directional valve 6, and the middle position of the second electro-hydraulic directional valve 18. It should be noted that when the slider of the main hydraulic cylinder 14 descends to the 2S position of the displacement sensor group 24, the trigger signal causes the limit switch SQ2 to de-energize and disconnect, causing the electromagnet 5YV of the solenoid directional valve 17 to de-energize. At this time, the first electro-hydraulic directional valve 6 is in its original position (originally in the right position), the hydraulic control check valve 16 is closed, and the filling valve 13 is closed due to the increase in pressure value in the upper chamber of the main hydraulic cylinder 14. The pressure oil in the lower chamber of the main hydraulic cylinder 14 in the return oil circuit flows back to the oil tank 23 through the first back pressure valve 15, the right position of the first electro-hydraulic directional valve 6, and the middle position of the second electro-hydraulic directional valve 18.
[0036] The fourth step is to maintain the pressure in the main cylinder. When the pressure in the upper chamber of the main hydraulic cylinder 14 reaches the preset value of the pressure relay 9, the first electro-hydraulic directional valve 6 is de-energized and switched to the neutral position. During the preset 10-second pressure maintenance period, the pressure oil in the upper and lower chambers of the main hydraulic cylinder 14 enters a closed state, and the pressure oil in the main hydraulic pump 2 flows back to the oil tank 23 through the first electro-hydraulic directional valve 6 and the second electro-hydraulic directional valve 18 in sequence. It should be noted that when the pressure in the upper chamber of the main hydraulic cylinder 14 reaches the preset value of the pressure relay 9, the solenoid 1YV of the first electro-hydraulic directional valve 6 is de-energized, and the first electro-hydraulic directional valve 6 switches to the neutral position. During the preset 10s pressure holding period, the pressure oil in the upper and lower chambers of the main hydraulic cylinder 14 enters a closed state, and the pressure oil in the main hydraulic pump 2 flows back to the oil tank 23 through the first electro-hydraulic directional valve 6 and the second electro-hydraulic directional valve 18 in sequence.
[0037] Fifth step, after the pressure holding process of the main cylinder is depressurized, the first electro-hydraulic directional valve 6 is energized, and the pressure oil passes through the left position of the first electro-hydraulic directional valve 6 and the upper position of the hydraulic slide valve 12 in sequence, opening the pilot sequence valve 8. The pressure oil of the main hydraulic pump 2 of the solenoid directional valve 17 flows back to the oil tank 23 through the pilot sequence valve 8. At the same time, the unloading core of the filling valve 13 is opened, so that the pressure oil in the upper chamber of the main hydraulic cylinder 14 flows back to the oil tank 23 through the opening of the unloading core of the filling valve 13, and then the pressure in the upper chamber of the main hydraulic cylinder 14 decreases. It should be noted that after the pressure holding process is completed, that is, after the preset value of 10 seconds, the left electro-hydraulic directional valve 6 remains energized. Since the pressure value of the upper chamber of the main hydraulic cylinder 14 is high, the hydraulic slide valve 12 is in the upper position. The pressure oil passes through the left position of the first electro-hydraulic directional valve 6 and the upper position of the hydraulic slide valve 12 in sequence, thereby opening the pilot-operated sequence valve 8. At this time, the pressure oil of the main hydraulic pump 2 flows back to the oil tank 23 through the pilot-operated sequence valve 8. At the same time, in the low-pressure environment, the main hydraulic pump 2 is insufficient to open the valve core of the filling valve 13. Therefore, the unloading core in the filling valve 13 is opened, so that the pressure oil in the upper chamber of the main hydraulic cylinder 14 flows back to the upper oil tank 23 through the opening of the unloading valve core of the filling valve 13. Then the pressure in the upper chamber of the main hydraulic cylinder 14 decreases.
[0038] Step 6, main cylinder return stroke. When the pressure value of the upper chamber of the main hydraulic cylinder 14 drops to the set value, the pilot sequence valve 8 closes, the main hydraulic pump 2 opens the filling valve 13, and the pressure oil in the oil inlet of the solenoid directional valve 17 flows through the left position of the first electro-hydraulic directional valve 6 and the hydraulic control check valve 16 in sequence into the lower chamber of the main hydraulic cylinder 14 via the main hydraulic pump 2. The pressure oil in the return oil line flows back to the oil tank 23 from the upper chamber of the main hydraulic cylinder 14 through the filling valve 13. It should be noted that when the pressure value of the upper chamber of the main hydraulic cylinder 14 drops to a certain value, the pilot-operated sequence valve 8 closes, and the oil supply pressure of the main hydraulic pump 2 increases, thereby making the filling valve 13 fully open. At this time, the pressurized oil in the oil inlet circuit flows through the left position of the first electro-hydraulic directional valve 6 and the hydraulic control check valve 16 in sequence via the main hydraulic pump 2 into the lower chamber of the main hydraulic cylinder 14. The pressurized oil in the oil return circuit flows from the upper chamber of the main hydraulic cylinder 14 back to the oil tank 23 via the filling valve 13.
[0039] Step 7: The main cylinder stops. When the slider of the main hydraulic cylinder 14 touches the displacement sensor group 24 for 1 second, the first electro-hydraulic directional valve 6 is de-energized, the hydraulic control check valve 16 closes the lower chamber of the main hydraulic cylinder 14, and the pressure oil output by the main hydraulic pump 2 flows back to the oil tank 23 through the middle position of the first electro-hydraulic directional valve 6 and the middle position of the second electro-hydraulic directional valve 18. It should be noted that when the slider of the main hydraulic cylinder 14 touches the displacement sensor group 24 at 1S, the solenoid 2YV of the first electro-hydraulic directional valve 6 is de-energized. At this time, the first electro-hydraulic directional valve 6 in the hydraulic system is in the neutral position, the hydraulic control check valve 16 closes the lower chamber of the main hydraulic cylinder 14, and its upper chamber remains stationary. The pressure oil output by the main hydraulic pump 2 flows sequentially through the neutral position of the first electro-hydraulic directional valve 6 and the neutral position of the second electro-hydraulic directional valve 18 back to the oil tank 23, and the pump is unloaded.
[0040] Step 8: The ejector cylinder 19 ejects. The movement of the ejector cylinder 19 occurs after the main hydraulic cylinder 14 stops moving. The solenoid directional valve 17 and the second electro-hydraulic directional valve 18 remain energized. The pressurized oil in the inlet circuit flows into the lower chamber of the ejector cylinder 19 through the main hydraulic pump 2, the middle position of the first electro-hydraulic directional valve 6, and the left position of the second electro-hydraulic directional valve 18 in sequence. The pressurized oil in the return circuit flows back to the oil tank 23 through the upper chamber of the ejector cylinder 19 and the left position of the second electro-hydraulic directional valve 18 in sequence. It should be noted that the movement of the ejector cylinder 19 occurs after the main hydraulic cylinder 14 stops moving. At this time, the solenoid 3YV of the second electro-hydraulic directional valve 18 remains energized, and the second electro-hydraulic directional valve 18 is switched to the left position. The pressurized oil in the inlet circuit flows into the lower chamber of the ejector cylinder 19 through the main hydraulic pump 2, the middle position of the first electro-hydraulic directional valve 6, and the left position of the second electro-hydraulic directional valve 18 in sequence. The pressurized oil in the return circuit flows back to the oil tank 23 through the upper chamber of the ejector cylinder 19 and the left position of the second electro-hydraulic directional valve 18 in sequence.
[0041] In the ninth step, the ejector cylinder 19 retracts. After the workpiece is removed, the second electro-hydraulic directional valve 18 remains energized, and pressurized oil enters the upper chamber of the ejector cylinder 19. The pressurized oil in the lower chamber of the ejector cylinder 19 flows back to the oil tank 23 through the right position of the second electro-hydraulic directional valve 18. The piston of the ejector cylinder 19 moves downward and returns to its original position.
[0042] It should be noted that after the workpiece is removed, the right electromagnet of the second electro-hydraulic directional valve 18 is energized and YV4 remains energized. The second electro-hydraulic directional valve 18 is switched to the right position. At this time, the pressure oil enters the upper chamber of the ejector cylinder 19, and the pressure oil in the lower chamber of the ejector cylinder 19 flows back to the oil tank 23 through the right position of the second electro-hydraulic directional valve 18. The piston of the ejector cylinder 19 moves downward and returns to its original position. When performing thin plate stretching and blanking, it is required that after the piston of the lower cylinder rises to a certain position, it maintains a certain pressure and can also descend with the downward pressure of the upper cylinder slider. At this time, the second relief valve 21 is in the neutral position. When the upper cylinder slider is pressed down, the piston of the lower cylinder is forced to move downward. The oil in the lower chamber of the lower cylinder flows back to the oil tank 23 through the throttle valve 20 and the second back pressure valve 22, so that the lower chamber of the lower cylinder maintains the required blanking pressure. The floating blanking force can be changed by adjusting the second back pressure valve 22. The upper chamber of the lower cylinder is replenished with oil from the oil tank 23 through the neutral position of the second relief valve 21. The second electro-hydraulic directional valve 18 is a safety valve for the lower chamber of the lower cylinder.
[0043] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A control system for a marine hydraulic press, characterized in that, include: The main hydraulic cylinder (14) is provided with a filling valve (13) in its upper chamber and an oil tank (23) in its drain end. The main hydraulic cylinder (14) is provided with a first back pressure valve (15) and a hydraulic control check valve (16) in its lower chamber. A servo pump is connected to the drain end of the oil tank (23). The servo pump includes a main hydraulic pump (2) and an auxiliary pump (3). The outlet pipe of the main hydraulic pump (2) is provided with a first electro-hydraulic directional valve (6). The A port of the first electro-hydraulic directional valve (6) is provided with a protective check valve (10). The outlet pipe of the protective check valve (10) is connected to the upper cavity of the main hydraulic cylinder (14). The B port of the first electro-hydraulic directional valve (6) is connected to the outlet pipes of the first back pressure valve (15) and the hydraulic control check valve (16). The T port of the first electro-hydraulic directional valve (6) is provided with a second electro-hydraulic directional valve (18). The T port of the second electro-hydraulic directional valve (18) is connected to the inlet of the filling valve (13). The outlet pipeline of the auxiliary pump (3) is provided with a first overflow valve (4). The T port of the first overflow valve (4) is connected to the inlet of the oil tank (23). The P port of the first overflow valve (4) is connected to an electromagnetic reversing valve (17). The P port of the electromagnetic reversing valve (17) is connected to the P port of the second electro-hydraulic reversing valve (18). A second pressure gauge (25) is connected in series between the P port of the electromagnetic reversing valve (17) and the P port of the first overflow valve (4). The T port of the electromagnetic reversing valve (17) is connected to the inlet of the oil tank (23). The P1 port of the hydraulic control check valve (16) is connected to the A port of the electromagnetic reversing valve (17). The T port of the second electro-hydraulic directional valve (18) is connected to the inlet of the oil tank (23). The A port of the second electro-hydraulic directional valve (18) is provided with an ejector cylinder (19). The rodless chamber of the ejector cylinder (19) is connected to the B port of the second electro-hydraulic directional valve (18). The rodless chamber of the ejector cylinder (19) is provided with a second relief valve (21). The T port of the second relief valve (21) is connected to the inlet of the oil tank (23). The P port of the second relief valve (21) is provided with a second back pressure valve (22). A third pressure gauge (26) and a throttle valve (20) are connected in series between the P port of the second relief valve (21) and the P port of the second back pressure valve (22). A hydraulic control unit is located between the main hydraulic cylinder (14) and the servo pump; An electrical control unit is used for electrical connection control of the system.
2. The marine hydraulic press control system according to claim 1, characterized in that, The main hydraulic pump (2) is equipped with an oil filter (1) at its inlet, and the inlet of the oil filter (1) is connected to the outlet of the oil tank (23).
3. A marine hydraulic press control system according to claim 2, characterized in that, The hydraulic control unit includes: The pilot-operated relief valve (5) is connected to the P port of the main hydraulic pump (2) and the P port of the first electro-hydraulic directional valve (6). The T port of the pilot-operated relief valve (5) is connected to the inlet of the oil tank (23). Remote pressure regulating valve (7), the P port of the remote pressure regulating valve (7) is connected to the K port of the pilot relief valve (5), and the T port of the remote pressure regulating valve (7) is connected to the inlet of the oil tank (23). Pressure relay (9), the P port of the pressure relay (9) is connected to the A port of the first electro-hydraulic directional valve (6) and the P1 port of the protective check valve (10).
4. A marine hydraulic press control system according to claim 3, characterized in that, The hydraulic control unit also includes: Hydraulic slide valve (12) is connected to the P1 port of filling valve (13), the P2 port of first back pressure valve (15), the P1 port of hydraulic control check valve (16) and the B port of first electro-hydraulic reversing valve (6). The T port of hydraulic slide valve (12) is connected to the inlet of oil tank (23). A pilot-operated sequence valve (8) is provided at the A port of hydraulic slide valve (12). The L port of pilot-operated sequence valve (8) is connected to the inlet of oil tank (23). The first pressure gauge (11) is connected in series between the P1 port of the filling valve (13) and the hydraulic slide valve (12).
5. A marine hydraulic press control system according to claim 4, characterized in that, The T-port of the first back pressure valve (15) is connected to the inlet of the oil tank (23). A displacement sensor group (24) is connected to the piston rod of the main hydraulic cylinder (14). The displacement sensor group (24) is used to indicate the output position of the main hydraulic cylinder (14).
6. A marine hydraulic press control system according to claim 5, characterized in that, The electrical control unit includes a main hydraulic cylinder (14) control circuit, a downlink control circuit, a pressure holding circuit, and an ejector cylinder (19) actuation circuit; The control circuit of the main hydraulic cylinder (14) includes a start button SB2 and a start contactor KM1 coil of the main hydraulic pump (2) connected in series between the live wire and the neutral wire of the control power supply. The upper terminal of the start button SB2 and the upper terminal of the start contactor KM1 coil are connected across the normally open contact of the start contactor KM1 of the main hydraulic pump (2). The lower terminal of the normally open contact of KM1 is connected in series with the neutral wire via the normally closed contact of the pressure relay (9) KP, the fast down button SB3 and the coil of the first contactor KA1. The lower terminal of the normally closed contact of KP is connected in series with the neutral wire via the normally open contact of KA1, the normally closed contact of the limit switch SQ2 and the coil of the fifth contactor KA5. The lower terminal of the fast down button SB3 is electrically connected to the upper terminal of the limit switch SQ2. The downlink control circuit includes the normally open contact of the pressure relay (9) KP, the normally closed contact of KA2, and the coil of the energizing delay time relay KT, which are connected in series between the normally open contact of KM1 and the neutral line. The voltage holding circuit includes the normally open contact of the second contactor KA2, the normally closed contact of the limit switch SQ1, and the coil of the second contactor KA2 connected in series between the normally open contact of the second contactor KA2 and the normally closed contact of the limit switch SQ1. The normally open contact of the energizing delay time relay KT is connected across the normally open contact of the second contactor KA2 and the normally closed contact of the limit switch SQ1.
7. A marine hydraulic press control system according to claim 6, characterized in that, The ejector cylinder (19) operating circuit includes a cylinder stop button SB4, a normally closed contact of KA1, a normally closed contact of KA2, a normally open contact of KA3, a normally closed contact of KA4, a normally closed contact of limit switch SQ3, and a coil of KA3 connected in series between the normally open contact of KM1 and the neutral wire. A cylinder ejection button SB5 is connected across the normally open contact of KA3 and the normally closed contact of KA4. A normally open contact of KA1, a normally open contact of KA2, a normally open contact of KA4, a normally closed contact of KA3, a normally closed contact of limit switch SQ4, and a coil of KA4 are connected in series between the normally closed contact of KA1 and the neutral wire. A cylinder retraction button SB6 is connected across the normally open contact of KA4 and the normally closed contact of KA3.
8. A method for controlling a marine hydraulic press, comprising a marine hydraulic press control system as described in claim 7, characterized in that, The control method includes the following steps: First step, no-load start-up: the main hydraulic pump (2) supplies oil to the hydraulic control unit. The solenoid directional valve (17) and the electromagnets in the hydraulic control unit are all de-energized. The pressure oil output by the main hydraulic pump (2) flows through the middle position of the first electro-hydraulic directional valve (6) and the middle position of the second electro-hydraulic directional valve (18), and finally flows back to the oil tank (23). The hydraulic press starts without load. In the second step, the main cylinder moves downward, the first electro-hydraulic directional valve (6) and the solenoid directional valve (17) are energized, and the control oil opens the hydraulic control check valve (16) through the solenoid directional valve (17). The pressure oil flows from the main hydraulic pump (2) through the right position of the first electro-hydraulic directional valve (6) and the protection check valve (10) in sequence, enters the upper chamber of the main hydraulic cylinder (14), and then flows from the lower chamber of the main hydraulic cylinder (14) through the hydraulic control check valve (16), the right position of the first electro-hydraulic directional valve (6) and the middle position of the second electro-hydraulic directional valve (18) back to the oil tank (23). In the third step, the main cylinder advances. When the slider of the main hydraulic cylinder (14) drops to the 2S position of the displacement sensor group (24), the solenoid directional valve (17) is de-energized and reset, the hydraulic check valve (16) and the filling valve (13) are closed, and the pressure oil in the lower chamber of the main hydraulic cylinder (14) in the return oil circuit flows back to the oil tank (23) through the first back pressure valve (15), the right position of the first electro-hydraulic directional valve (6), and the middle position of the second electro-hydraulic directional valve (18). Fourth step, main cylinder pressure holding. When the pressure in the upper chamber of the main hydraulic cylinder (14) reaches the preset value of the pressure relay (9), the first electro-hydraulic directional valve (6) is de-energized and switched to the neutral position. During the preset 10s pressure holding period, the pressure oil in the upper and lower chambers of the main hydraulic cylinder (14) enters the closed state, and the pressure oil in the main hydraulic pump (2) flows back to the oil tank (23) through the first electro-hydraulic directional valve (6) and the second electro-hydraulic directional valve (18). Fifth step, after the pressure holding process of the main cylinder is depressurized, the first electro-hydraulic directional valve (6) is energized, and the pressure oil passes through the left position of the first electro-hydraulic directional valve (6) and the upper position of the hydraulic slide valve (12) in sequence, opening the pilot sequence valve (8). The pressure oil of the main hydraulic pump (2) of the electromagnetic directional valve (17) flows back to the oil tank (23) through the pilot sequence valve (8). At the same time, the unloading core of the filling valve (13) is opened, so that the pressure oil in the upper chamber of the main hydraulic cylinder (14) flows back to the oil tank (23) through the opening of the unloading core of the filling valve (13), and then the pressure in the upper chamber of the main hydraulic cylinder (14) decreases. Step 6, main cylinder return stroke. When the pressure value of the upper chamber of the main hydraulic cylinder (14) drops to the set value, the pilot sequence valve (8) closes, the main hydraulic pump (2) opens the filling valve (13), and the pressure oil in the oil inlet circuit of the solenoid directional valve (17) flows through the left position of the first electro-hydraulic directional valve (6) and the hydraulic control check valve (16) in sequence into the lower chamber of the main hydraulic cylinder (14) via the main hydraulic pump (2). The pressure oil in the return oil circuit flows back to the oil tank (23) from the upper chamber of the main hydraulic cylinder (14) through the filling valve (13). Step 7: The main cylinder stops. When the slider of the main hydraulic cylinder (14) touches the displacement sensor group (24) for 1 second, the first electro-hydraulic directional valve (6) is de-energized, the hydraulic control check valve (16) closes the lower chamber of the main hydraulic cylinder (14), and the pressure oil output by the main hydraulic pump (2) flows back to the oil tank (23) through the middle position of the first electro-hydraulic directional valve (6) and the middle position of the second electro-hydraulic directional valve (18). Step 8: The ejector cylinder (19) ejects. The movement of the ejector cylinder (19) is carried out after the main hydraulic cylinder (14) stops moving. The solenoid directional valve (17) and the second electro-hydraulic directional valve (18) remain energized. The pressurized oil in the oil inlet flows into the lower chamber of the ejector cylinder (19) through the main hydraulic pump (2), the middle position of the first electro-hydraulic directional valve (6), and the left position of the second electro-hydraulic directional valve (18) in sequence. The pressurized oil in the oil return flows back to the oil tank (23) through the upper chamber of the ejector cylinder (19) and the left position of the second electro-hydraulic directional valve (18) in sequence. In the ninth step, the ejector cylinder (19) retracts. After the workpiece is removed, the second electro-hydraulic directional valve (18) remains energized, and the pressure oil enters the upper chamber of the ejector cylinder (19). The pressure oil in the lower chamber of the ejector cylinder (19) flows back to the oil tank (23) through the right position of the second electro-hydraulic directional valve (18). The piston of the ejector cylinder (19) moves downward and returns to its original position.
Citation Information
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