CN217129955U - Oil way of large-scale press - Google Patents

Abstract

The application discloses an oil way of a large-scale press, which comprises a hydraulic circuit and a lubricating oil way, wherein the hydraulic circuit comprises an oil inlet path and an oil return path, the oil inlet path comprises a first oil inlet path, a second oil inlet path and a main oil inlet path, the first oil inlet path and the second oil inlet path are connected in parallel to the main oil inlet path, the hydraulic circuit is provided with an execution cylinder and an unloading assembly, the execution cylinder is connected with the main oil inlet path and the oil return path, the execution cylinder comprises a reversing valve, and the reversing valve is connected with the main oil inlet path and the oil return path; a first constant delivery pump is arranged on the first oil inlet path, a second constant delivery pump is arranged on the second oil inlet path, the first constant delivery pump is a high-pressure low-flow pump, and the second constant delivery pump is a low-pressure high-flow pump; the unloading assembly comprises a first overflow valve and a second overflow valve, the first overflow valve is suitable for an unloading second oil inlet path, the second overflow valve is suitable for an unloading main oil inlet path, the adjusting pressure of the first overflow valve is lower than that of the second overflow valve, and a back pressure valve is arranged on an oil return path. The oil circuit of this application is small, convenient operation and optimizes the combination operating mode.

Description

Oil way of large-scale press

Technical Field

The application relates to the field of hydraulic control, in particular to an oil way of a large-scale press.

Background

The oil circuit comprises a hydraulic circuit and a lubricating oil circuit, wherein the hydraulic circuit is a hydraulic device forming part which is composed of various hydraulic elements and has certain functions, the lubricating oil circuit refers to the direction of lubricating oil of a lubricating system, and the hydraulic system has the advantages of small volume, light weight, high rigidity, high precision, quick response and the like, can generate larger driving force particularly for certain heavy-load machines, and is mainly used in various large-scale equipment and machines. The hydraulic press has the advantages of large working pressure, strong load capacity, stable operation and the like, and is a common press.

However, existing presses, particularly large presses, require large flows for some combined conditions, such as fast forward, but the load pressure is not high; the flow required in high load pressure is very small, and the like, an optimized oil way is not provided, the size is overlarge, and the operation is inconvenient.

Disclosure of Invention

An object of this application is to provide an oil circuit that small, convenient operation and optimize the combination operating mode.

In order to achieve the above purposes, the technical scheme adopted by the application is as follows:

an oil way of a large-scale press comprises a hydraulic circuit and a lubricating oil way, wherein the hydraulic circuit comprises an oil inlet path and an oil return path, the oil inlet path comprises a first oil inlet path, a second oil inlet path and a main oil inlet path, the first oil inlet path and the second oil inlet path are connected into the main oil inlet path in parallel, an execution cylinder and an unloading assembly are arranged on the hydraulic circuit, the execution cylinder is connected with the main oil inlet path and the oil return path, the execution cylinder comprises a reversing valve, and the reversing valve is connected to the main oil inlet path; a first fixed displacement pump is arranged on the first oil inlet path, a second fixed displacement pump is arranged on the second oil inlet path, the first fixed displacement pump is a high-pressure low-flow pump, and the second fixed displacement pump is a low-pressure high-flow pump; the unloading assembly comprises a first overflow valve and a second overflow valve, the first overflow valve is suitable for unloading the second oil inlet path, the second overflow valve is suitable for unloading the main oil inlet path, the adjusting pressure of the first overflow valve is lower than that of the second overflow valve, and a back pressure valve is arranged on the oil return path.

Preferably, the reversing valve is a Y-shaped four-position three-way electromagnetic valve, the reversing valve comprises an A port and a B port, the execution cylinder is connected with a first branch and a second branch, the first branch is communicated with the A port and a left cavity of the execution cylinder, and the second branch is communicated with the B port and a right cavity of the execution cylinder; a first hydraulic control one-way valve is arranged on the first branch, and a control oil way of the first hydraulic control one-way valve is connected to the second branch; and a second hydraulic control one-way valve is arranged on the second branch, and a control oil way of the second hydraulic control one-way valve is connected with the first branch.

Preferably, the first branch is provided with a first pressure relay, the second branch is provided with a second pressure relay, and the first pressure relay and the second pressure relay are suitable for enabling the reversing valve to return to a neutral position.

Preferably, an energy accumulator is arranged on the first branch or the second branch and is suitable for controlling the impact force of oil.

Further preferably, the actuating cylinder includes a clamping cylinder and a jacking cylinder, and the clamping cylinder and the jacking cylinder are operated at different load pressures.

In another preferred embodiment, the hydraulic circuit includes a lubricating oil path, the oil inlet path and the oil return path share the same oil tank, the lubricating oil path is provided with an oil level alarm and a temperature sensor, the oil level alarm is adapted to monitor an oil level of the oil tank, and the temperature sensor is adapted to detect a temperature of the oil in the oil tank.

Preferably, the lubricating oil path comprises a first filtering oil path, a second filtering oil path and a filtering reversing valve, the filtering reversing valve is a two-position three-way electromagnetic valve and is suitable for reversing under the control of a control assembly, the first filtering oil path and the second filtering oil path are connected in parallel on the lubricating oil path, a filtering port A and a filtering port B are arranged on the filtering reversing valve, the filtering port A is communicated with the first filtering oil path, the filtering port B is communicated with the second filtering oil path, and the first filtering oil path and the second filtering oil path are suitable for filtering the oil entering the lubricating oil path.

And preferably, a filtering pressure relay is arranged on the lubricating oil path and is suitable for controlling the filtering reversing valve to reverse.

And in another preferred mode, a plurality of parallel lubricating branches are arranged on the lubricating oil circuit, and speed regulating valves are arranged on the lubricating branches and are suitable for regulating the oil inlet amount of the oil.

Preferably, the lubrication branch is provided with a C-shaped two-position four-way reversing valve, the two-position four-way reversing valve comprises a gap lubrication port a and a gap lubrication port B, the gap lubrication port a is connected with a point position needing lubrication, the gap lubrication port B is connected with the oil tank, and the two-position four-way reversing valve is suitable for gap lubrication of the lubrication branch; and a blockage alarm is arranged on the lubricating branch and is suitable for giving an alarm when the lubricating branch is blocked.

Compared with the prior art, the beneficial effect of this application lies in:

(1) for a large-scale press, different processes are required to be executed by a hydraulically driven executive part, some processes require large flow and low load, such as fast forward and fast backward, and are used for improving the working efficiency, some processes require small flow and low load, such as ejection, and the like, the requirements of complex working conditions cannot be met by using one constant delivery pump, a plurality of motors are required to be matched by selecting a plurality of constant delivery pumps, and the functions cannot be realized on the same hydraulic loop, so that the volume of the hydraulic loop is increased, the production cost is reduced and the use effect is improved by using one motor to be matched with two constant delivery pumps in one hydraulic loop;

(2) the two constant delivery pumps are respectively selected from a low-flow high-load constant delivery pump and a high-flow low-load constant delivery pump, and are matched with the unloading assembly, when high flow is needed, the two constant delivery pumps work simultaneously, and the flow is maximized; when high-load work is needed, the unloading assembly can unload the load of the high-flow low-load fixed displacement pump, the fixed displacement pump with the high flow and the low load is protected from being damaged, the effect that 1 plus 1 is larger than 2 is achieved, the impact of an oil return path can be reduced by arranging the backpressure valve on the oil return path, the oil return path is more stable and durable, the purpose of controlling the oil return speed can be achieved by controlling the size of the backpressure valve, and therefore the purpose of executing the movement speed of the piston in the cylinder is achieved.

Drawings

FIG. 1 is a schematic view of one embodiment of an oil circuit of the present application, showing various components and locations;

FIG. 2 is a schematic view of another embodiment of an oil circuit of the present application, illustrating a plurality of lubrication branches;

FIG. 3 is an enlarged partial view of position A of one embodiment of the oil circuit of the present application, illustrating a pilot operated check valve;

FIG. 4 is an enlarged partial view of a location B of an embodiment of the oil circuit of the present application, illustrating a first oil inlet circuit and a second oil inlet circuit;

fig. 5 is a partial enlarged view of a position C of an embodiment of the oil passage of the present application, showing a first filtered oil passage and a second filtered oil passage.

In the figure: 1. an oil inlet path; 11. a first oil inlet path; 111. a first fixed displacement pump; 12. a second oil inlet path; 121. a second fixed displacement pump; 13. a main oil inlet path;

2. an oil return path; 21. a back pressure valve;

3. an execution cylinder; 31. a diverter valve; 311. a port A; 312. a port B; 32. a clamping cylinder; 33. jacking up the cylinder; 34. a first branch; 341. a first hydraulic control check valve; 342. a first pressure relay; 35. a second branch circuit; 351. a second hydraulic control one-way valve; 352. a second pressure relay; 36. an accumulator;

4. an unloading assembly; 41. a first overflow valve; 42. a second overflow valve;

5. an oil tank;

6. a lubrication oil path; 61. a filter diverter valve; 611. filtering an opening A; 612. filtering the port B; 62. a first filtering oil path; 63. a second filtering oil path; 64. a filtering pressure relay; 65. a lubrication branch; 651. a speed regulating valve; 652. a two-position four-way reversing valve; 6521. a gap lubrication port A; 6522. a gap lubricates a port B; 653. a blockage alarm; 66. an oil level alarm; 67. a temperature sensor.

Detailed Description

The present application is further described below with reference to specific embodiments, and it should be noted that, without conflict, any combination between the embodiments or technical features described below may form a new embodiment.

In the description of the present application, it should be noted that, for the terms of orientation, such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., it indicates that the orientation and positional relationship shown in the drawings are based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be construed as limiting the specific scope of protection of the present application.

It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

The terms "comprises," "comprising," and "having," and any variations thereof, in the description and claims of this application, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The existing hydraulic loop of the press machine has the advantages that for some complex working conditions, such as working procedures requiring low-load high-speed movement or high-load low-speed movement, a large-flow and large-load fixed displacement pump is selected, so that the cost is increased, and most of flow is unloaded through an overflow valve when the high-load and low-speed movement is required, so that a large amount of energy is wasted; or the selection of a servomotor drive, which increases the cost of the drive assembly, is not an optimal solution for such complex operating conditions.

Therefore, the inventor of the present application has developed an oil path of a large press, one embodiment of which is shown in fig. 1 to 5, and includes a hydraulic circuit and a lubricating oil path 6, wherein the hydraulic circuit includes an oil inlet path 1 and an oil return path 2, the oil inlet path 1 includes a first oil inlet path 11, a second oil inlet path 12 and a main oil inlet path 13, the first oil inlet path 11 and the second oil inlet path 12 are connected in parallel to the main oil inlet path 13, the hydraulic circuit is provided with an actuating cylinder 3 and an unloading assembly 4, the actuating cylinder 3 connects the main oil inlet path 13 and the oil return path 2, the actuating cylinder 3 includes a reversing valve 31, and the reversing valve 31 is connected to the main oil inlet path 13; a first quantitative pump 111 is arranged on the first oil inlet path 11, a second quantitative pump 121 is arranged on the second oil inlet path 12, the first quantitative pump 111 is a high-pressure low-flow pump, and the second quantitative pump 121 is a low-pressure high-flow pump; the unloading assembly 4 comprises a first overflow valve 41 and a second overflow valve 42, the first overflow valve 41 is suitable for unloading the second oil inlet path 12, the second overflow valve 42 is suitable for unloading the main oil inlet path 13, the adjusting pressure of the first overflow valve 41 is lower than that of the second overflow valve 42, and the oil return path 2 is provided with a back pressure valve 21.

The first relief valve 41 and the second relief valve 42 have different functions, and when a large-flow and low-load process is required, the first fixed displacement pump 111 and the second fixed displacement pump 121 operate simultaneously, and hydraulic oil is collected into the main oil inlet 13 through the first oil inlet 11 and the second oil inlet 12; when a low-flow high-load process is required, because the load of the main oil inlet 13 is large, the first overflow valve 41 is opened, the second oil inlet 12 is unloaded, that is, the second fixed displacement pump 121 (low-pressure high-flow pump) is unloaded, at this time, hydraulic oil enters the main oil inlet 13 through the first oil inlet 11, hydraulic oil in the second oil inlet 12 returns to the oil tank 5 through the first overflow valve 41, the pressure of the whole hydraulic circuit is protected from being too large under the action of the second overflow valve 42, and when a blockage or other problems occur, the main oil inlet 13 can be unloaded through the second overflow valve 42.

The method that the first oil inlet path 11 and the second oil inlet path 12 are connected in parallel to enter the main oil inlet path 13 and are unloaded through the unloading assembly 4 is adopted, two constant delivery pumps can work simultaneously, when the work of large flow and low load is realized, the flow which can be provided by the hydraulic oil path is larger, and when the work of low flow and large load is needed, the hydraulic oil path can work smoothly under the protection of the first overflow valve 41, the production cost is saved, the waste of energy is also reduced, only one motor drives the two constant delivery pumps to work, the size of the whole hydraulic loop is reduced, and the production cost is reduced.

As shown in fig. 1, the back pressure valve 21 is a speed regulating valve, and the back pressure valve 21 selected in this embodiment is capable of regulating the flow speed of the hydraulic oil in the oil return path 2 as required, so as to control the retraction speed of the piston in the actuating cylinder 3, and thus control the load of the hydraulic oil path.

Further preferably, as shown in fig. 3, the reversing valve 31 is a Y-shaped four-position three-way electromagnetic valve, the reversing valve 31 includes an a port 311 and a B port 312, the actuating cylinder 3 is connected with a first branch 34 and a second branch 35, the first branch 34 communicates the a port 311 with the left chamber of the actuating cylinder 3, and the second branch 35 communicates the B port 312 with the right chamber of the actuating cylinder 3; a first hydraulic control one-way valve 341 is arranged on the first branch 34, and a control oil path of the first hydraulic control one-way valve 341 is connected to the second branch 35; a second hydraulic control one-way valve 351 is arranged on the second branch 35, and a control oil path of the second hydraulic control one-way valve 351 is connected with the first branch 34.

When the change valve 31 is switched to the operating state, taking the oil inlet of the port a 311 and the oil outlet of the port B312 as an example, the hydraulic oil enters the first branch line 34, and since the control oil path of the second hydraulic check valve 351 is connected to the first branch line 34, the control oil path of the second hydraulic check valve 351 flows in the hydraulic pressure oil, so as to control the second hydraulic check valve 351 to be in a two-way state, the oil outlet of the second branch line 35 passes through the second hydraulic check valve 351, at this time, although the second branch line 35 communicates with the control oil path of the first hydraulic check valve 341, the second branch line 35 is in an oil return state, and the second hydraulic check valve 351 cannot be driven to open, so that the purpose of one-way oil inlet of the port a 311 and one-way oil outlet of the port B312 is achieved.

The Y-shaped four-position three-way electromagnetic valve can reduce the impact from rest to start and also can reduce the impact from start to rest, thereby ensuring that the pressure conduction of the hydraulic circuit is smoother,

set up first hydraulically controlled check valve 341 and second hydraulically controlled check valve 351 in first branch road 34 and second branch road 35 and can prevent in the course of the work, the hydraulic oil backward flow in the pipeline leads to the pipeline to strike, the unstable result of pressure to make the control oil circuit of first hydraulically controlled check valve 341 connect on second branch road 35, on the control oil circuit of second hydraulically controlled check valve 351 connects first branch road 34, conveniently control one-way oil feed and one-way oil outlet.

Further preferably, as shown in fig. 3, the first branch 34 is provided with a first pressure relay 342, the second branch 35 is provided with a second pressure relay 352, and the first pressure relay 342 and the second pressure relay 352 are adapted to return the direction valve 31 to the neutral position.

Taking the left cavity oil inlet and the right cavity oil outlet as an example, when the oil pressure of the left cavity reaches the set pressure of the first pressure relay 342, the first pressure relay 342 sends an electric signal to the control assembly, so as to drive the reversing valve 31 to return to the neutral position, the Y-shaped four-position three-way electromagnetic valve enables the execution cylinder 3 to be in a floating state, the execution cylinder 3 can advance for a certain distance under the driving of inertia, and the sudden stop can not occur, so that the execution cylinder 3 is shaken too much.

Further preferably, as shown in fig. 2, an accumulator 36 is disposed on the first branch 34 or the second branch 35, and the accumulator 36 is adapted to control the impact force of the oil.

The accumulator 36 is a conventional technique, and is generally used to reduce the impact of hydraulic oil on the oil circuit, because the hydraulic circuit is used in a large-sized press, the flow rate and load change are fast, the pulse can be reduced by using the accumulator 36, and when a certain amount of hydraulic oil can be stored in the accumulator 36, the static to start impact and the start to static impact can be further reduced when the reversing valve 31 is in the neutral position.

Further preferably, as shown in fig. 1, the actuator cylinder 3 includes a clamp cylinder 32 and a jack cylinder 33, and the clamp cylinder 32 and the jack cylinder 33 are operated at different load pressures.

According to different requirements, one or more execution cylinders 3 can be adopted, and when one execution cylinder 3 is adopted, the working state is slow-speed and high-load working; high speed, low load backoff. When a plurality of actuating cylinders 3 are provided, as shown in fig. 1, the press machine needs to use a clamping process and a jacking process, the load pressures of the clamping cylinder 32 and the jacking cylinder 33 are different, oil inlets of the clamping cylinder 32 and the jacking cylinder 33 are communicated, oil outlets of the clamping cylinder 32 and the jacking cylinder 33 are also communicated, the working requirements are met, and the volumes of a hydraulic circuit and a hydraulic actuating part are reduced.

Alternatively, as shown in fig. 1, the lubricating oil circuit 6 and the hydraulic circuit share the same oil tank 5, the lubricating oil circuit 6 is provided with an oil level alarm 66 and a temperature sensor 67, the oil level alarm 66 is adapted to monitor the oil level of the oil tank 5, and the temperature sensor 67 is adapted to detect the temperature of the oil in the oil tank 5.

Make lubricated oil circuit 6 and same oil tank 5 of hydraulic circuit sharing can reduce the volume of the hydraulic circuit of this application to set up oil level alarm 66, when the oil level was crossed lowly, can remind the user to refuel, temperature sensor 67 detects the temperature of fluid in the oil tank 5, can prevent the sealing member of hydraulic circuit because the too high too early damage of temperature.

In another preferred embodiment, as shown in fig. 5, the lubricating oil path 6 includes a first filtering oil path 62, a second filtering oil path 63 and a filtering reversing valve 61, the filtering reversing valve 61 is a two-position three-way electromagnetic valve, the filtering reversing valve 61 is adapted to reverse under the control of the control assembly, the first filtering oil path 62 and the second filtering oil path 63 are connected in parallel to the lubricating oil path 6, the filtering reversing valve 61 is provided with a filtering a port 611 and a filtering B port 612, the filtering a port 611 is communicated with the first filtering oil path 62, the filtering B port 612 is communicated with the second filtering oil path 63, and the first filtering oil path 62 and the second filtering oil path 63 are adapted to filter oil entering the lubricating oil path 6.

The filter change valve 61 is changed in direction under the control of the control assembly, different cut-off states can be changed, the lubricating oil circuit 6 and the hydraulic circuit share one oil tank 5, hydraulic oil has more impurities, and the filter oil circuit is easy to be blocked, so the first filter oil circuit 62 and the second filter oil circuit 63 are separately arranged, and the filter change valve 61 is changed in direction, when the filter change valve is in an initial state, a P port on the filter change valve 61 is communicated with a filter B port 612, as shown in fig. 5, the first filter oil circuit 62 does not pass through the hydraulic oil, the second filter oil circuit 63 passes through the hydraulic oil, when the second filter oil circuit 63 is blocked after long-term use, the filter change valve 61 can be switched through the control assembly, so that the first filter oil circuit 62 works, and workers can directly change filter elements in the second filter oil circuit 63 without stopping.

Alternatively, as shown in fig. 1, the lubricating oil path 6 is provided with a filtering pressure relay 64, and the filtering pressure relay 64 is adapted to control the filtering direction change valve 61 to change the direction.

When the second filtering oil path 63 is blocked, the filtering pressure relay 64 detects that the pressure in the lubricating oil path 6 is too high, and can automatically send an electric signal to the control assembly, so that the control assembly switches the filtering reversing valve 61 to reverse, the first filtering oil path 62 works, and the second filtering oil path 63 is automatically disconnected, so that subsequent replacement is facilitated, and the filtering oil path is prevented from being blocked and the unblocked filtering oil path cannot be automatically switched when no one is looking at the filtering oil path.

Preferably, as shown in fig. 2, the lubrication oil path 6 is provided with a plurality of parallel lubrication branches 65, the lubrication branches 65 are provided with speed control valves 651, and the speed control valves 651 are adapted to adjust the oil inlet amount of the oil.

Because different lubrication branches 65 require different lubrication, the speed of the speed regulating valve 651 can be set to achieve the effects of different lubrication effects for different branches at different positions.

Preferably, the lubrication branch 65 is provided with a C-shaped two-position four-way reversing valve 652, the two-position four-way reversing valve 652 comprises a gap lubrication port a 6521 and a gap lubrication port B6522, the gap lubrication port a 6521 is connected with a point position needing lubrication, the gap lubrication port B6522 is connected with the oil tank 5, and the two-position four-way reversing valve 652 is suitable for the gap lubrication point position; a blockage alarm 653 is provided on the lubrication branch 65, the blockage alarm 653 being adapted to alarm when the lubrication branch 65 is blocked.

When the C-shaped two-position four-way reversing valve 652 is in a normal state in an initial state, the gap lubrication port a 6521 is communicated with the oil inlet P, and the gap lubrication port B6522 is communicated with the oil return port T, as shown in fig. 1, hydraulic oil in the lubrication oil path 6 enters the gap lubrication port a 6521 through the oil inlet P, then enters the oil tank 5 through the gap lubrication port a 6521, no hydraulic oil flows in the gap lubrication port B6522, and no lubrication effect is generated at this time; the C-shaped two-position four-way reversing valve 652 is switched, at the moment, the gap lubrication A port 6521 is communicated with the oil return port T, the gap lubrication B port 6522 is communicated with the oil inlet P, oil in the oil inlet P enters a point position needing to be lubricated through the gap lubrication B port 6522 and enters the point position needing to be lubricated, the lubricating effect is achieved, at the moment, no hydraulic oil flows in the gap lubrication A port 6521, the two-position four-way reversing valve 652 can be switched on the control assembly according to time, and therefore the effect of the gap lubrication branch circuit 65 is achieved; the blockage alarm 653 is adapted to alarm when the lubrication branch 65 is blocked, for which oil circuit two lubrication branches 65 can be provided as shown in fig. 1, or a plurality of lubrication branches 65 can be provided as shown in fig. 2.

The foregoing has described the general principles, essential features, and advantages of the application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, which are merely illustrative of the principles of the application, but that various changes and modifications may be made without departing from the spirit and scope of the application, and these changes and modifications are intended to be within the scope of the application as claimed. The scope of protection claimed by this application is defined by the following claims and their equivalents.

Claims (10)

1. The oil circuit of the large-scale press comprises a hydraulic circuit and a lubricating oil circuit, wherein the hydraulic circuit comprises an oil inlet path and an oil return path, and is characterized in that the oil inlet path comprises a first oil inlet path, a second oil inlet path and a main oil inlet path, the first oil inlet path and the second oil inlet path are connected in parallel to the main oil inlet path, the hydraulic circuit is provided with an execution cylinder and an unloading assembly, the execution cylinder is connected with the main oil inlet path and the oil return path, the execution cylinder comprises a reversing valve, and the reversing valve is connected with the main oil inlet path and the oil return path; a first constant delivery pump is arranged on the first oil inlet path, a second constant delivery pump is arranged on the second oil inlet path, the first constant delivery pump is a high-pressure low-flow pump, and the second constant delivery pump is a low-pressure high-flow pump; the unloading assembly comprises a first overflow valve and a second overflow valve, the first overflow valve is suitable for unloading the second oil inlet path, the second overflow valve is suitable for unloading the main oil inlet path, the adjusting pressure of the first overflow valve is lower than that of the second overflow valve, and a back pressure valve is arranged on the oil return path.

2. The oil circuit of a large-scale press machine according to claim 1, wherein the reversing valve is a Y-shaped four-position three-way electromagnetic valve, the reversing valve comprises an A port and a B port, the execution cylinder is connected with a first branch and a second branch, the first branch is communicated with the A port and a left cavity of the execution cylinder, and the second branch is communicated with the B port and a right cavity of the execution cylinder; a first hydraulic control one-way valve is arranged on the first branch, and a control oil path of the first hydraulic control one-way valve is connected to the second branch; and a second hydraulic control one-way valve is arranged on the second branch, and a control oil way of the second hydraulic control one-way valve is connected to the first branch.

3. The oil circuit of a large-scale press machine according to claim 2, wherein a first pressure relay is arranged on the first branch, a second pressure relay is arranged on the second branch, and the first pressure relay and the second pressure relay are suitable for controlling the reversing valve to return to a neutral position.

4. An oil circuit of a large-scale press machine according to claim 3, wherein an accumulator is arranged on the first branch or the second branch, and the accumulator is suitable for controlling the impact force of oil.

5. The oil circuit of a large-sized press machine according to claim 4, wherein the actuating cylinder comprises a clamping cylinder and a jacking cylinder, and the clamping cylinder and the jacking cylinder are operated at different load pressures.

6. An oil circuit of a large-scale press machine according to claim 1, wherein the lubricating oil circuit and the hydraulic circuit share the same oil tank, and an oil level alarm and a temperature sensor are arranged on the lubricating oil circuit, wherein the oil level alarm is suitable for monitoring the oil level of the oil tank, and the temperature sensor is suitable for detecting the temperature of the oil in the oil tank.

7. The oil circuit of a large-sized press machine according to claim 6, wherein the lubricating oil circuit comprises a first filtering oil circuit, a second filtering oil circuit and a filtering reversing valve, the filtering reversing valve is a two-position three-way solenoid valve, the filtering reversing valve is suitable for reversing under the control of a control assembly, the first filtering oil circuit and the second filtering oil circuit are connected in parallel on the lubricating oil circuit, the filtering reversing valve is provided with a filtering A port and a filtering B port, the filtering A port is communicated with the first filtering oil circuit, the filtering B port is communicated with the second filtering oil circuit, and the first filtering oil circuit and the second filtering oil circuit are suitable for filtering the oil entering the lubricating oil circuit.

8. An oil circuit of a large-scale press machine as claimed in claim 7, wherein the lubricating oil circuit is provided with a filtering pressure relay, and the filtering pressure relay is suitable for controlling the filtering reversing valve to reverse.

9. An oil circuit of a large-scale press machine as claimed in claim 6, wherein the lubricating oil circuit is provided with a plurality of parallel lubricating branches, and the lubricating branches are provided with speed regulating valves which are suitable for regulating the oil feeding amount of the oil.

10. The oil circuit of a large-scale press machine according to claim 9, wherein a two-position four-way reversing valve is arranged on the lubricating branch, the normal position of the two-position four-way reversing valve is C-shaped, the two-position four-way reversing valve comprises a gap lubricating A port and a gap lubricating B port, the gap lubricating A port is connected with the oil tank, and the gap lubricating B port is connected with a point position needing to be lubricated; and a blockage alarm is arranged on the lubricating branch and is suitable for giving an alarm when the lubricating branch is blocked.

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