Hydraulic system of hydraulic machine

Abstract

The invention provides a hydraulic system of a hydraulic machine, and relates to the field of hydraulic machines. A port A of the first electromagnetic reversing valve is connected with a hydraulic control port of the first supporting cartridge valve, a port P is connected with a first cylinder body branch, and a port T is connected with an oil tank. An oil cylinder descending valve and a second electromagnetic directional valve are arranged in the second cylinder body branch; a port A of the second electromagnetic directional valve is connected with a hydraulic control port of the oil cylinder descending valve, a port P is connected with the main oil supply path, and a port T is connected with the oil tank; an oil inlet of the first one-way valve is connected with an oil outlet of the oil cylinder descending valve, and an oil outlet of the first one-way valve is connected with the rodless cavity; the first oil return path is connected with a second main oil port of the first supporting cartridge valve; the second oil return path is connected with the rodless cavity; an oil inlet of the interlocking oil drain valve is connected with an oil outlet of the oil cylinder descending valve, a hydraulic control port of the interlocking oil drain valve is connected with a port B of the first electromagnetic reversing valve, an oil outlet of the interlocking oil drain valve is connected with the oil tank, pressure maintaining is conducted on a rod cavity, the gliding pressure of a rodless cavity is reduced, and a piston is prevented from slipping off.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic presses, and in particular to a hydraulic system of a hydraulic press. Background Art

[0002] Hydraulic presses play an important role in the production of the machinery manufacturing industry. With the development of technology, the tonnage of pressing is getting larger and larger, and the tonnage of hydraulic systems is getting higher and higher. Ultra-high pressure and large flow hydraulic systems are gradually being promoted and applied. During the working process of the hydraulic press, its working cycle mainly includes three stages: rapid descent, slow pressurization, and rapid return. At the same time, the hydraulic press also includes a hovering process. During the slow pressurization or hovering process of the hydraulic press, the rod cavity of the hydraulic press needs to be pressurized. Especially for large-diameter cylinders in large-tonnage hydraulic presses, due to their large dead weight, during the hovering process of large-tonnage hydraulic presses, the rod cavity needs to be pressurized to support the hydraulic press and prevent the hydraulic press cylinder from automatically sliding down.

[0003] Therefore, it is urgent to propose a hydraulic system of a hydraulic press that can solve the problem of the hydraulic press sliding sharply downward during the hovering process. Summary of the invention

[0004] The purpose of the present invention is to provide a hydraulic system for a hydraulic press to solve the problems existing in the above-mentioned prior art. While maintaining the pressure of the rod chamber of the oil cylinder, it can also reduce the downward pressure of the rodless chamber, prevent the piston of the oil cylinder from automatically sliding down, and solve the problem of the hydraulic press sliding down sharply during the hovering process.

[0005] To achieve the above object, the present invention provides the following solution: a hydraulic system of a hydraulic press is provided, comprising:

[0006] A main oil supply circuit, the main oil supply circuit is connected to the rod chamber of the oil cylinder through a first cylinder branch circuit, and the main oil supply circuit is connected to the rodless chamber of the oil cylinder through a second cylinder branch circuit;

[0007] The first cylinder branch is provided with a first support cartridge valve and a first electromagnetic reversing valve; the first main oil port of the first support cartridge valve can be connected to the rod chamber; the A port of the first electromagnetic reversing valve is connected to the hydraulic control port of the first support cartridge valve, the P port of the first electromagnetic reversing valve is connected to the first cylinder branch, and the T port of the first electromagnetic reversing valve is connected to the oil tank;

[0008] The second cylinder branch is provided with a cylinder downward valve and a second electromagnetic reversing valve; the A port of the second electromagnetic reversing valve is connected to the hydraulic control port of the cylinder downward valve, the P port of the second electromagnetic reversing valve is connected to the main oil supply circuit, and the T port of the second electromagnetic reversing valve is connected to the oil tank; the second cylinder branch is also provided with a first check valve, the oil inlet of the first check valve is connected to the oil outlet of the cylinder downward valve, and the oil outlet of the first check valve is connected to the rodless chamber;

[0009] a first oil return circuit, the first oil return circuit being connected to a second main oil port of the first support cartridge valve;

[0010] a second oil return circuit, the second oil return circuit being connected to the rodless chamber;

[0011] An interlocking oil drain valve, wherein the oil inlet of the interlocking oil drain valve is connected to the oil outlet of the cylinder downward valve, the hydraulic control port of the interlocking oil drain valve is connected to the B port of the first solenoid reversing valve, and the oil outlet of the interlocking oil drain valve is connected to the oil tank.

[0012] Preferably, a cylinder return valve and a shuttle valve are provided in the first cylinder branch, the oil inlet of the cylinder return valve is connected to the main oil supply circuit, and the oil outlet of the cylinder return valve is connected to the first support cartridge valve; the oil outlet of the shuttle valve is connected to the hydraulic control port of the cylinder return valve, the first oil inlet of the shuttle valve is connected to the A port of the third solenoid reversing valve, the P port of the third solenoid reversing valve is connected to the main oil supply circuit, and the T port of the third solenoid reversing valve is connected to the oil tank; the second oil inlet of the shuttle valve is connected to the first cylinder branch, and in the first cylinder branch, the connection point of the second oil inlet of the shuttle valve and the first cylinder branch is located between the cylinder return valve and the first support cartridge valve.

[0013] Preferably, a filling valve is provided in the second oil return circuit, the oil inlet of the filling valve is connected to the oil tank, the oil outlet of the filling valve is connected to the rodless chamber, the hydraulic control port of the filling valve is connected to the B port of the fourth solenoid reversing valve, the T port of the fourth solenoid reversing valve is connected to the oil tank, and the P port of the fourth solenoid reversing valve is connected to the main oil supply circuit.

[0014] Preferably, it also includes a second supporting cartridge valve and an electromagnetic ball valve, the second main oil port of the second supporting cartridge valve is connected to the first main oil port of the first supporting cartridge valve, the first main oil port of the second supporting cartridge valve is connected to the rod chamber, the A port of the electromagnetic ball valve is connected to the hydraulic control port of the second supporting cartridge valve, the P port of the electromagnetic ball valve is connected to the first cylinder branch, and the T port of the electromagnetic ball valve is connected to the oil tank.

[0015] Preferably, a safety relief valve is provided in the first cylinder branch, and the first main oil port of the second support cartridge valve is connected to the safety relief valve.

[0016] Preferably, the first oil return circuit includes a rod chamber oil drain valve, the oil inlet of the rod chamber oil drain valve is connected to the second main oil port of the first support cartridge valve, and the oil outlet of the rod chamber oil drain valve is connected to the oil tank.

[0017] Preferably, the hydraulic control port of the rod chamber oil drain valve is connected to the oil tank through a second pilot relief valve.

[0018] Preferably, the hydraulic control port of the rod chamber oil drain valve is connected to the P port and the A port of the three-position four-way solenoid valve, and the T port of the three-position four-way solenoid valve is connected to the oil tank; the hydraulic control port of the rod chamber oil drain valve is also connected to the B port of the three-position four-way solenoid valve through the third pilot overflow valve.

[0019] Preferably, a second one-way valve is arranged on the pipeline between the first cylinder branch and the P port of the first electromagnetic reversing valve, and the oil inlet of the second one-way valve is connected to the first cylinder branch; the oil outlet of the second one-way valve is connected to the P port of the first electromagnetic reversing valve.

[0020] Preferably, a third one-way valve is arranged on the connecting pipeline between the hydraulic control port of the interlocking oil drain valve and the B port of the first solenoid reversing valve, the oil inlet of the third one-way valve is connected to the oil drain port of the interlocking oil drain valve, and the oil outlet of the third one-way valve is connected to the B port of the first solenoid reversing valve.

[0021] Compared with the prior art, the present invention has achieved the following technical effects:

[0022] The present invention can cut off the power of the first electromagnetic reversing valve, and the high-pressure oil in the first cylinder branch is passed to the hydraulic control port of the first support cartridge valve through the P port to the A port of the first electromagnetic reversing valve, so that the first support cartridge valve is closed, so that the first support cartridge valve supports and maintains pressure, and the rod chamber is pressurized to prevent the piston of the oil cylinder from slipping. The second electromagnetic reversing valve is cut off, and the hydraulic oil of the main oil supply circuit passes through the P port to the A port of the second electromagnetic reversing valve and then passes into the hydraulic control port of the oil cylinder downward valve, so that the oil cylinder downward valve is closed, thereby closing the second cylinder branch and preventing the rodless chamber from entering the oil. At this time, since the first electromagnetic reversing valve has been cut off, the interlocking oil drain valve is connected to the oil tank through the B port and the T port of the first electromagnetic reversing valve, and the hydraulic oil will pass through the interlocking oil drain valve to the B port of the first electromagnetic reversing valve and flow back to the oil tank through the T port, and the interlocking oil drain valve is in an open state. Furthermore, in the process from the power off of the second solenoid reversing valve to the closing of the cylinder downward valve, the high-pressure oil passing through the cylinder downward valve will enter the oil tank through the interlocking oil drain valve, preventing more high-pressure oil from entering the rodless chamber, reducing the downward pressure of the rodless chamber, and further preventing the piston of the cylinder from slipping, thereby solving the automatic downward slide of the cylinder and having high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 It is a schematic diagram of the overall system of the present invention.

[0025] Among them, 1. main oil supply circuit; 2. interlocking oil drain valve; 3. oil cylinder; 4. rod chamber; 5. rodless chamber; 6. first supporting cartridge valve; 7. first solenoid reversing valve; 8. oil cylinder downward valve; 9. second solenoid reversing valve; 10. first check valve; 11. second check valve; 12. third check valve; 13. first pilot relief valve; 14. oil cylinder return valve; 15. shuttle valve; 16. third solenoid reversing valve; 17. filling valve; 18. fourth solenoid reversing valve; 19. second supporting cartridge valve; 20. solenoid ball valve; 21. safety relief valve; 22. rod chamber oil drain valve; 23. three-position four-way solenoid valve; 24. second pilot relief valve; 25. third pilot relief valve. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Please refer to Figure 1As shown, in this embodiment, a hydraulic system of a hydraulic press is provided, including a main oil supply circuit 1, a first cylinder branch circuit, a second cylinder branch circuit, a first oil return circuit, a second oil return circuit, and an interlocking oil drain valve 2. The main oil supply circuit 1 is connected to the oil cylinder, and an oil pump is arranged on the main oil supply circuit 1, one end of the first cylinder branch circuit is connected to the main oil supply circuit 1, and the other end of the first cylinder branch circuit is connected to the rod chamber 4 of the oil cylinder 3, one end of the second cylinder branch circuit is connected to the main oil supply circuit 1, and the other end of the second cylinder branch circuit is connected to the rodless chamber 5 of the oil cylinder 3. The first support cartridge valve 6 and the first electromagnetic reversing valve 7 are arranged in the first cylinder branch. The first support cartridge valve 6 includes a first main oil port, a second main oil port and a hydraulic control port. The rod chamber 4 is connected to the first main oil port of the first support cartridge valve 6. The A port of the first electromagnetic reversing valve 7 is connected to the hydraulic control port of the first support cartridge valve 6. The P port of the first electromagnetic reversing valve 7 is connected to the first cylinder branch. The connection point between the P port of the first electromagnetic reversing valve 7 and the first cylinder branch is located between the first main oil port of the first support cartridge valve 6 and the rod chamber 4. The T port of the first electromagnetic reversing valve 7 is connected to the oil tank. The oil cylinder descending valve 8 and the second electromagnetic reversing valve 9 are arranged in the second cylinder branch. The oil inlet of the oil cylinder descending valve 8 is connected to the main oil supply circuit 1. The A port of the second electromagnetic reversing valve 9 is connected to the hydraulic control port of the oil cylinder descending valve 8. The P port of the second electromagnetic reversing valve 9 is connected to the main oil supply circuit 1. The T port of the second electromagnetic reversing valve 9 is connected to the oil tank. A first check valve 10 is also provided in the second cylinder branch. The first check valve 10 is located between the oil cylinder downward valve 8 and the rodless chamber 5. The oil inlet of the first check valve 10 is connected to the oil outlet of the oil cylinder downward valve 8, and the oil outlet of the first check valve 10 is connected to the rodless chamber 5, so that the conduction direction of the first check valve 10 is: the delivery direction of the hydraulic oil from the oil cylinder downward valve 8 to the rodless chamber 5. The first oil return circuit is connected to the first cylinder branch. Specifically, the first oil return circuit is connected to the second main oil port of the first support cartridge valve 6. The connection point of the first oil return circuit and the first cylinder branch is located on the side of the first support cartridge valve 6 away from the oil cylinder 3; the connection point of the first oil return circuit and the first cylinder branch, the first support cartridge valve 6, and the connection point of the rod chamber 4 of the oil cylinder 3 and the first cylinder branch are arranged in sequence in the first cylinder branch. The second oil return circuit is connected to the rodless chamber 5 of the oil cylinder 3. The oil inlet of the interlocking oil release valve 2 is connected to the second cylinder branch, the oil inlet of the interlocking oil release valve 2 is connected to the oil outlet of the oil cylinder downward valve 8, and is also connected to the oil inlet of the first one-way valve 10, and the connection point between the interlocking oil release valve 2 and the second cylinder branch is located between the oil cylinder downward valve 8 and the first one-way valve 10. The hydraulic control port of the interlocking oil release valve 2 is connected to the B port of the first electromagnetic reversing valve 7, and the oil outlet of the interlocking oil release valve 2 is connected to the oil tank. The first electromagnetic reversing valve 7 and the second electromagnetic reversing valve 9 are both two-position four-way electromagnetic reversing valves. The first one-way valve 10 is a cartridge one-way valve. The oil cylinder downward valve 8 is a cartridge valve.

[0029] Working principle: Cylinder propulsion: The oil pump on the main oil supply circuit 1 is energized to generate high-pressure oil, the cross position of the second solenoid reversing valve 9 is energized, and the high-pressure oil enters the cylinder downward valve 8 and the first one-way valve 10 in turn, and then enters the rodless chamber 5 of the cylinder 3 through the oil outlet of the first one-way valve 10; the hydraulic oil in the rod chamber 4 of the cylinder 3 flows back to the first return oil circuit through the first support cartridge valve 6.

[0030] Oil cylinder return stroke: the oil pump on the main oil supply line 1 is energized to generate high-pressure oil. The high-pressure oil on the main oil supply line 1 enters the rod chamber 4 of the oil cylinder 3 through the first support cartridge valve 6. The hydraulic oil in the rodless chamber 5 of the oil cylinder 3 flows back to the oil tank through the second oil return line, realizing the return stroke process.

[0031] When the oil cylinder is maintaining pressure or hovering, the oil cylinder needs to maintain pressure and support the rod chamber of the oil cylinder due to its own weight: the first electromagnetic reversing valve 7 is powered off, and the high-pressure oil in the first cylinder branch is passed from the P port to the A port of the first electromagnetic reversing valve 7 to the hydraulic control port of the first support cartridge valve 6, so that the first support cartridge valve 6 is closed, so that the first support cartridge valve 6 supports and maintains pressure, effectively maintaining pressure in the rod chamber to prevent the piston of the oil cylinder 3 from slipping. The second electromagnetic reversing valve 9 is powered off, and the hydraulic oil in the main oil supply circuit 1 is passed from the P port to the A port of the second electromagnetic reversing valve 9 and then to the hydraulic control port of the oil cylinder downward valve 8, so that the oil cylinder downward valve 8 is closed, thereby closing the second cylinder branch and preventing the rodless chamber 5 from entering oil. However, it still takes a certain amount of time from the power off of the second electromagnetic reversing valve 9 to the closing of the oil cylinder downward valve 8. During this period of time, if no auxiliary measures are taken, a large amount of high-pressure oil in the main oil supply circuit 1 will still be delivered to the rodless chamber 5 through the second cylinder branch. At this time, since the first electromagnetic reversing valve 7 has been powered off, the interlocking oil drain valve 2 is connected to the oil tank through the B port and T port of the first electromagnetic reversing valve 7, and the hydraulic oil will pass through the interlocking oil drain valve 2 to the B port of the first electromagnetic reversing valve 7 and flow back to the oil tank through the T port. The interlocking oil drain valve 2 is in an open state. Furthermore, in the process from the power failure of the second electromagnetic reversing valve 9 to the closing of the oil cylinder downward valve 8, the high-pressure oil passing through the oil cylinder downward valve 8 will pass into the oil tank through the interlocking oil drain valve 2, preventing more high-pressure oil from entering the rodless chamber 5, reducing the downward pressure of the rodless chamber 5, and further preventing the piston of the oil cylinder 3 from sliding; solving the automatic downward movement of the oil cylinder 3, with a simple structure, clear action, high reliability, a wide range of use, and obvious effect.

[0032] In one embodiment, a second one-way valve 11 is provided on the pipeline between the first cylinder branch and the P port of the first electromagnetic reversing valve 7. The second one-way valve 11 can be a threaded one-way valve, and the oil inlet of the second one-way valve 11 is connected to the first cylinder branch. The oil outlet of the second one-way valve 11 is connected to the P port of the first electromagnetic reversing valve 7. A third one-way valve 12 is provided on the connecting pipeline between the hydraulic control port of the interlocking oil release valve 2 and the B port of the first electromagnetic reversing valve 7. The oil inlet of the third one-way valve 12 is connected to the oil release port of the interlocking oil release valve 2, and the oil outlet of the third one-way valve 12 is connected to the B port of the first electromagnetic reversing valve 7. The interlocking oil release valve 2 is also connected to a first pilot relief valve 13, and the other end of the first pilot relief valve 13 is connected to the oil inlet of the third one-way valve 12. When the cross position of the first electromagnetic reversing valve 7 is energized and working, the hydraulic oil cannot be depressurized through the third one-way valve 12 . When the pressure in the pipeline is too high, it can be depressurized through the first pilot relief valve 13 .

[0033] In one embodiment, a cylinder return valve 14 and a shuttle valve 15 are provided in the first cylinder branch. The cylinder return valve 14 is a cartridge valve. One end of the cylinder return valve 14 is connected to the main oil supply circuit 1, and the other end of the cylinder return valve 14 is connected to the first support cartridge valve 6. The oil outlet of the shuttle valve 15 is connected to the hydraulic control port of the cylinder return valve 14, the first oil inlet of the shuttle valve 15 is connected to the A port of the third electromagnetic reversing valve 16, the P port of the third electromagnetic reversing valve 16 is connected to the main oil supply circuit 1, and the T port of the third electromagnetic reversing valve 16 is connected to the oil tank; the second oil inlet of the shuttle valve 15 is connected to the first cylinder branch. In the first cylinder branch, the connection point of the second oil inlet and the first cylinder branch is located between the cylinder return valve 14 and the first support cartridge valve 6. At the same time, in the first cylinder branch, the connection point of the first oil return circuit and the first cylinder branch is also located between the cylinder return valve 14 and the first support cartridge valve 6. When the oil cylinder returns, the first oil inlet of the shuttle valve 15 is connected to the oil outlet, and the cross position of the third electromagnetic reversing valve 16 is controlled to be energized, so that the oil cylinder return valve 14 is in an open state, and the high-pressure oil in the main oil supply circuit 1 is sequentially input into the rod chamber 4 through the oil cylinder return valve 14 and the first support cartridge valve 6. The third electromagnetic reversing valve 16 is preferably a two-position four-way electromagnetic valve.

[0034] In this embodiment, the connection point of the first oil return circuit and the first cylinder branch is located between the cylinder return valve 14 and the first support cartridge valve 6. Preferably, the connection point of the first oil return circuit on the first cylinder branch coincides with the connection point of the second oil inlet of the shuttle valve 15 on the first cylinder branch. During the cylinder propulsion process, the second oil inlet of the shuttle valve 15 can be connected to the oil outlet, and the hydraulic oil in the first cylinder branch closes the cylinder return valve 14 through the shuttle valve 15, so that the hydraulic oil in the first cylinder branch can flow into the first oil return circuit.

[0035] In one embodiment, a filling valve 17 is provided in the second oil return circuit, the oil inlet of the filling valve 17 is connected to the oil tank, and the oil outlet of the filling valve 17 is connected to the rodless chamber 5 of the oil cylinder 3. The hydraulic control port of the filling valve 17 is connected to the B port of the fourth electromagnetic reversing valve 18, the T port of the fourth electromagnetic reversing valve 18 is connected to the oil tank (return oil), and the P port of the fourth electromagnetic reversing valve 18 is connected to the main oil supply circuit 1, that is, the P port of the fourth electromagnetic reversing valve 18 is connected to the oil pump. During the return stroke of the oil cylinder, the cross position of the fourth electromagnetic reversing valve 18 is energized, the filling valve 17 is reversely opened, and the hydraulic oil in the rodless chamber 5 enters the oil tank through the filling valve 17 to realize the return stroke process. The fourth electromagnetic reversing valve 18 is preferably a two-position four-way solenoid valve.

[0036] In one embodiment, a second support cartridge valve 19 and an electromagnetic ball valve 20 are arranged on the pipeline between the first support cartridge valve 6 and the rod chamber 4 in the first cylinder branch, the second main oil port of the second support cartridge valve 19 is connected to the first main oil port of the first support cartridge valve 6, and the first main oil port of the second support cartridge valve 19 is connected to the rod chamber 4, that is, the first main oil port of the first support cartridge valve 6 is connected to the rod chamber 4 through the second support cartridge valve 19. The A port of the electromagnetic ball valve 20 is connected to the hydraulic control port of the second support cartridge valve 19, and the P port of the electromagnetic ball valve 20 is connected to the first cylinder branch, that is, the P port of the electromagnetic ball valve 20 is connected to the oil pump, and the T port of the electromagnetic ball valve 20 is connected to the oil tank. When the cylinder is maintaining pressure or hovering, the cylinder needs to have a rod chamber to maintain pressure support due to its own weight, the electromagnetic ball valve 20 is powered off, and the high-pressure oil passes from the P port to the A port of the electromagnetic ball valve 20 and enters the hydraulic control port of the second support cartridge valve 19, so that the second support cartridge valve 19 is closed, and the first support cartridge valve 6 and the second support cartridge valve 19 form a secondary pressure-maintaining support to ensure a good support effect.

[0037] In this embodiment, a safety overflow valve 21 is provided between the second support cartridge valve 19 and the rod chamber 4 of the cylinder 3 in the first cylinder branch. The first main oil port of the second support cartridge valve 19 is connected to the safety overflow valve 21. When an abnormality occurs in the first cylinder branch, the oil pressure increases to the set value of the safety overflow valve 21. At this time, the hydraulic oil in the rod chamber 4 can flow out of the safety overflow valve 21 to ensure the safety of the cylinder 3.

[0038] In one embodiment, a rod chamber drain valve 22 is provided in the first oil return circuit, the oil inlet of the rod chamber drain valve 22 is connected to the first cylinder branch, the hydraulic control port of the rod chamber drain valve 22 is connected to the P port and the A port of the three-position four-way solenoid valve 23, the T port of the three-position four-way solenoid valve 23 and the oil outlet of the rod chamber drain valve 22 are both connected to the oil tank, the hydraulic control port of the rod chamber drain valve 22 is also connected to the oil tank through the second pilot relief valve 24, and the second pilot relief valve 24 is preferably a high-pressure pilot relief valve; the hydraulic control port of the rod chamber drain valve 22 is also connected to the B port of the three-position four-way solenoid valve 23 through the third pilot relief valve 25. The third pilot relief valve 25 is a low-pressure pilot relief valve. When the parallel position of the three-position four-way solenoid valve 23 is energized, the high-pressure pilot relief valve and the low-pressure pilot relief valve are in parallel, the low-pressure pilot relief valve opens first, and the pressure oil overflows from the low-pressure pilot relief valve.

[0039] In this embodiment, the oil inlet of the rod chamber oil drain valve 22 is connected to the second main oil port of the first support cartridge valve 6, the connection point between the oil inlet of the rod chamber oil drain valve 22 and the first cylinder body branch is located between the cylinder return valve 14 and the first support cartridge valve 6, and the connection point between the rod chamber oil drain valve 22 and the first cylinder body branch is located on the oil outlet side of the cylinder return valve 14.

[0040] In the present invention, the plug chamber oil circuit of the oil cylinder 3: the oil pump is connected to the oil inlet of the oil cylinder downward valve 8, the oil outlet of the oil cylinder downward valve 8 is connected to the oil inlet of the first one-way valve 10, and the oil outlet of the first one-way valve 10 is connected to the rodless chamber 5 of the oil cylinder 3; the rodless chamber 5 is connected to the B port of the filling valve 17; the A port of the filling valve 17 is connected to the oil tank.

[0041] The rod chamber oil circuit of the oil cylinder 3: the oil pump is connected to the oil inlet of the oil cylinder return valve 14, the oil outlet of the oil cylinder return valve 14 is connected to the oil inlet of the first support cartridge valve 6 and the rod chamber oil drain valve 22, the oil outlet of the first support cartridge valve 6 is connected to the oil inlet of the second support cartridge valve 19, the oil outlet of the second support cartridge valve 19 is connected to the rod chamber 4 of the oil cylinder 3, and the oil outlet of the rod chamber oil drain valve 22 is connected to the oil tank. The entire system of the present invention is composed of a two-position four-way electromagnetic reversing valve, a three-position four-way electromagnetic reversing valve, a two-way cartridge valve, a superimposed one-way valve, a pilot overflow valve, a filling valve 17, and a master cylinder. This system has a master cylinder fast down, a master cylinder slow down, and a master cylinder return. The device has five oil ports, namely: the oil inlet is connected to the oil pump through an oil pipe; the oil outlet of the two-way cartridge valve is connected to the cylinder plug chamber and the cylinder rod chamber respectively; the oil outlet of the two-position four-way solenoid valve is connected to the control port of the filling valve 17; and the oil return port is connected to the oil tank through an oil pipe.

[0042] Specific working process: Fast forward process: On the main oil supply line 1, the pump is energized to generate high-pressure oil, and the second solenoid reversing valve 9 is energized at the cross position. The high-pressure oil enters the cylinder downward valve 8 and the first one-way valve 10 in turn, and then enters the rodless chamber 5 of the cylinder 3 through the oil outlet of the first one-way valve 10. At the same time, the solenoid ball valve 20 and the first solenoid reversing valve 7 are energized, and the hydraulic oil in the rod chamber 4 of the cylinder 3 passes through the second supporting cartridge valve 19 and the first supporting cartridge valve 6 to the oil inlet of the rod chamber drain valve 22. At this time, the cross position of the three-position four-way solenoid valve 23 is energized, and the hydraulic oil is connected to the oil tank through the rod chamber drain valve 22, so that the hydraulic oil in the rod chamber 4 of the cylinder 3 returns to the oil tank, realizing the fast descent of the cylinder 3. When the piston rod of the cylinder 3 is fast down, its plug chamber forms a negative pressure to open the filling valve 17, and the hydraulic oil in the oil tank connected to the filling valve 17 enters the rodless chamber 5 of the cylinder 3, realizing the fast forward process. When the high-pressure oil reaches the oil inlet of the rod chamber drain valve 22, the cylinder return valve 14 is closed through the shuttle valve 15 at the same time.

[0043] Slow-forward process: When the fast-forward process makes the oil cylinder 3 reach the specified position, it is necessary to switch to the slow-forward process to prevent the oil cylinder 3 from colliding with the workpiece. When other actions remain unchanged, the parallel position of the three-position four-way solenoid valve 23 is energized, and the hydraulic oil in the rod chamber 4 of the oil cylinder 3 generates a certain back pressure through the third pilot relief valve 25, and then passes through the B port of the three-position four-way solenoid valve 23 and connects to the oil tank through the T port, generating a slow-down attack speed. If an abnormality occurs during the slow-down attack process, the oil pressure rises to the set value of the safety relief valve 21, and the hydraulic oil in the rod chamber 4 flows out of the safety relief valve 21 to ensure the safety of the oil cylinder 3.

[0044] Cylinder return stroke: On the main oil supply line 1, the pump is energized to generate high-pressure oil, the cross position of the third solenoid reversing valve 16 is energized, and the high-pressure oil enters the rod chamber 4 of the cylinder 3 through the cylinder return valve 14, the first support cartridge valve 6, and the second support cartridge valve 19 in sequence, the cross position of the fourth solenoid reversing valve 18 is energized, the filling valve 17 opens in the reverse direction, and the hydraulic oil in the rodless chamber 5 of the cylinder 3 enters the oil tank through the filling valve 17, realizing the return stroke process.

[0045] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any reference numerals in the claims should not be regarded as limiting the claims involved.

[0046] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A hydraulic system of a hydraulic press, characterized in that: include: A main oil supply circuit (1), the main oil supply circuit (1) being connected to a rod chamber (4) of an oil cylinder (3) via a first cylinder branch circuit, and the main oil supply circuit (1) being connected to a rodless chamber (5) of the oil cylinder (3) via a second cylinder branch circuit; A first support cartridge valve (6) and a first electromagnetic reversing valve (7) are provided in the first cylinder branch; the first main oil port of the first support cartridge valve (6) can be connected to the rod chamber (4); the A port of the first electromagnetic reversing valve (7) is connected to the hydraulic control port of the first support cartridge valve (6), the P port of the first electromagnetic reversing valve (7) is connected to the first cylinder branch, and the T port of the first electromagnetic reversing valve (7) is connected to the oil tank; The second cylinder branch is provided with a cylinder downward valve (8) and a second electromagnetic reversing valve (9); the A port of the second electromagnetic reversing valve (9) is connected to the hydraulic control port of the cylinder downward valve (8), the P port of the second electromagnetic reversing valve (9) is connected to the main oil supply circuit (1), and the T port of the second electromagnetic reversing valve (9) is connected to the oil tank; the second cylinder branch is also provided with a first check valve (10), the oil inlet of the first check valve (10) is connected to the oil outlet of the cylinder downward valve (8), and the oil outlet of the first check valve (10) is connected to the rodless chamber (5); a first oil return circuit, the first oil return circuit being connected to a second main oil port of the first support cartridge valve (6); a second oil return circuit, the second oil return circuit being connected to the rodless chamber (5); An interlocking oil drain valve (2), wherein the oil inlet of the interlocking oil drain valve (2) is connected to the oil outlet of the cylinder downward valve (8), the hydraulic control port of the interlocking oil drain valve (2) is connected to the B port of the first electromagnetic reversing valve (7), and the oil outlet of the interlocking oil drain valve (2) is connected to the oil tank.

2. The hydraulic system of the hydraulic press according to claim 1, characterized in that: A cylinder return valve (14) and a shuttle valve (15) are provided in the first cylinder branch. The oil inlet of the cylinder return valve (14) is connected to the main oil supply circuit (1), and the oil outlet of the cylinder return valve (14) is connected to the first support cartridge valve (6); the oil outlet of the shuttle valve (15) is connected to the hydraulic control port of the cylinder return valve (14); the first oil inlet of the shuttle valve (15) is connected to the A port of the third electromagnetic reversing valve (16), the P port of the third electromagnetic reversing valve (16) is connected to the main oil supply circuit (1), and the T port of the third electromagnetic reversing valve (16) is connected to the oil tank; the second oil inlet of the shuttle valve (15) is connected to the first cylinder branch. In the first cylinder branch, the connection point between the second oil inlet of the shuttle valve (15) and the first cylinder branch is located between the cylinder return valve (14) and the first support cartridge valve (6).

3. The hydraulic system of the hydraulic press according to claim 1, characterized in that: A charging valve (17) is provided in the second oil return circuit, the oil inlet of the charging valve (17) is connected to the oil tank, the oil outlet of the charging valve (17) is connected to the rodless chamber (5), the hydraulic control port of the charging valve (17) is connected to the B port of the fourth electromagnetic reversing valve (18), the T port of the fourth electromagnetic reversing valve (18) is connected to the oil tank, and the P port of the fourth electromagnetic reversing valve (18) is connected to the main oil supply circuit (1).

4. The hydraulic system of the hydraulic press according to claim 1, characterized in that: It also includes a second supporting cartridge valve (19) and an electromagnetic ball valve (20), wherein the second main oil port of the second supporting cartridge valve (19) is connected to the first main oil port of the first supporting cartridge valve (6), the first main oil port of the second supporting cartridge valve (19) is connected to the rod chamber (4), the A port of the electromagnetic ball valve (20) is connected to the hydraulic control port of the second supporting cartridge valve (19), the P port of the electromagnetic ball valve (20) is connected to the first cylinder branch, and the T port of the electromagnetic ball valve (20) is connected to the oil tank.

5. The hydraulic system of the hydraulic press according to claim 4, characterized in that: A safety overflow valve (21) is provided in the first cylinder branch, and the first main oil port of the second support cartridge valve (19) is connected to the safety overflow valve (21).

6. The hydraulic system of the hydraulic press according to claim 2, characterized in that: The first oil return circuit includes a rod chamber oil drain valve (22), the oil inlet of the rod chamber oil drain valve (22) is connected to the second main oil port of the first support cartridge valve (6), and the oil outlet of the rod chamber oil drain valve (22) is connected to the oil tank.

7. The hydraulic system of the hydraulic press according to claim 6, characterized in that: The hydraulic control port of the rod chamber oil drain valve (22) is connected to the oil tank via a second pilot overflow valve (24).

8. The hydraulic system of the hydraulic press according to claim 7, characterized in that: The hydraulic control port of the rod chamber oil drain valve (22) is connected to the P port and the A port of the three-position four-way solenoid valve (23), and the T port of the three-position four-way solenoid valve (23) is connected to the oil tank; the hydraulic control port of the rod chamber oil drain valve (22) is also connected to the B port of the three-position four-way solenoid valve (23) through the third pilot overflow valve (25).

9. The hydraulic system of the hydraulic press according to claim 1, characterized in that: A second one-way valve (11) is provided on the pipeline between the first cylinder branch and the P port of the first electromagnetic reversing valve (7); the oil inlet of the second one-way valve (11) is connected to the first cylinder branch; and the oil outlet of the second one-way valve (11) is connected to the P port of the first electromagnetic reversing valve (7).

10. The hydraulic system of the hydraulic press according to claim 9, characterized in that: A third one-way valve (12) is provided on the connecting pipeline between the hydraulic control port of the interlocking oil drain valve (2) and the B port of the first electromagnetic reversing valve (7); the oil inlet of the third one-way valve (12) is connected to the oil drain port of the interlocking oil drain valve (2), and the oil outlet of the third one-way valve (12) is connected to the B port of the first electromagnetic reversing valve (7).

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