Hydraulic system of press machine

Abstract

The utility model discloses a hydraulic system of a press machine. The hydraulic system comprises a main cylinder hydraulic subsystem, a punching cylinder hydraulic subsystem, a demolding cylinder hydraulic subsystem and an ejection cylinder hydraulic subsystem, the main cylinder hydraulic subsystem comprises a second electric control variable pump, the second electric control variable pump is communicated with the first electric control variable pump, and the output end of the second electric control variable pump is connected with an oil inlet in one end of a first three-position four-way electromagnetic reversing valve through a third one-way valve; a third electric control variable pump is jointly connected among the punching cylinder hydraulic subsystem, the demolding cylinder hydraulic subsystem and the ejection cylinder hydraulic subsystem, and meanwhile, the output end of the third electric control variable pump is connected with a fourth one-way valve; a plurality of variable pumps are combined to provide a hydraulic oil source, actions such as quick descending, pressurization and return stroke of a main cylinder of the executing mechanism, stretching and return stroke of a punching cylinder, passive pressing and stretching of an ejection cylinder and a demolding cylinder and the like are realized, the material forming pressure is accurately controlled, and the working energy efficiency of a hydraulic system is high.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic systems, in particular to a hydraulic system for a press machine. Background Art

[0002] Presses are widely used in metal forming processing, and they have many advantages such as high efficiency, good quality and low cost. The hydraulic system of a press consists of multiple components, mainly including hydraulic fluid, hydraulic pump, control valve, hydraulic cylinder, hydraulic pipeline, etc. They cooperate with each other to realize the conversion and transmission of hydraulic energy.

[0003] The existing press hydraulic system has a simple structure, inaccurate control of material forming pressure, low energy efficiency of the hydraulic system, poor adjustability of process actions, and cannot adapt well to multiple process requirements. For example, in the prior art, the hydraulic pump only supplies oil to the fixed actuator, and there is no logical switching of the oil circuit, resulting in an over-configuration of the main pump, especially when the main pump is a variable pump, the flow control function of the main pump cannot be effectively utilized, and the configuration function is wasted. Utility Model Content

[0004] The purpose of the utility model is to provide a hydraulic system for a press machine, which adopts a combination of multiple variable pumps to provide a hydraulic oil source, multiple proportional relief valves to control the forming pressure, and a differential circuit for rapid action. The working cylinders do not interfere with each other and have good independence. The working pressure and speed of all cylinders are controllable, so as to solve the problems raised in the above-mentioned background technology.

[0005] In order to solve the above technical problems, the utility model provides the following technical solutions:

[0006] A hydraulic system for a press machine includes a main cylinder hydraulic subsystem, a punching cylinder hydraulic subsystem, a demoulding cylinder hydraulic subsystem, and an ejection cylinder hydraulic subsystem; the main cylinder hydraulic subsystem includes a second electrically controlled variable pump connected to a first motor at one end, the second electrically controlled variable pump is connected to the first electrically controlled variable pump, the output end of the second electrically controlled variable pump is connected to an oil inlet at one end of a first three-position four-way electromagnetic reversing valve through a third one-way valve; the output end of the first electrically controlled variable pump is connected to an oil inlet at the same end of the first three-position four-way electromagnetic reversing valve through the electromagnetic reversing valve, the second one-way valve in sequence The first three-position four-way solenoid reversing valve is connected, one end of the oil outlet is connected to the fourth proportional relief valve, and the other end is connected to the rodless chamber of the master cylinder, and the other end of the oil outlet of the first three-position four-way solenoid reversing valve is connected to the rod chamber of the master cylinder; the first solenoid valve is connected in parallel between the two oil outlets of the first three-position four-way solenoid reversing valve; the punching cylinder hydraulic subsystem, the demoulding cylinder hydraulic subsystem, and the ejection cylinder hydraulic subsystem are commonly connected to a third electrically controlled variable pump, and the output end of the third electrically controlled variable pump is connected to a fourth non-return valve; the punching cylinder hydraulic subsystem includes A fourth three-position four-way solenoid reversing valve, the oil outlet of the fourth three-position four-way solenoid reversing valve is connected to the first hydraulic lock, one oil outlet of the first hydraulic lock is connected to the first proportional relief valve, the other is connected to the rod chamber of the punching cylinder, and the first proportional relief valve is connected to the rodless chamber of the punching cylinder at the same time; the demoulding cylinder hydraulic subsystem includes a third three-position four-way solenoid reversing valve, the oil outlet of the third three-position four-way solenoid reversing valve is connected to the second hydraulic lock, the oil outlet of the second hydraulic lock is connected to the rodless chamber of the demoulding cylinder, the other is connected to the rod chamber of the demoulding cylinder, and the second hydraulic lock is connected to the rodless chamber of the demoulding cylinder at the same time. The two oil outlets of the compression lock are also connected in parallel with a first oil replenishment check valve and a second proportional relief valve; the ejection cylinder hydraulic subsystem includes a second three-position four-way electromagnetic reversing valve, the oil outlet of the second three-position four-way electromagnetic reversing valve is connected to the third hydraulic lock, one oil outlet of the third hydraulic lock is connected to the rod chamber of the ejection cylinder, and the other oil outlet is connected to the rodless chamber of the ejection cylinder, and at the same time, the two oil outlets of the third hydraulic lock are also connected in parallel with a second oil replenishment check valve and a third proportional relief valve; the oil outlet of the electromagnetic reversing valve is connected to the rod chamber of the punching cylinder and the first hydraulic lock through the first check valve.

[0007] Preferably, another oil inlet of the first three-position four-way solenoid reversing valve is connected to the oil tank through a second solenoid valve.

[0008] Preferably, the third electrically controlled variable pump is connected to the second motor.

[0009] The working process of the utility model is:

[0010] like Figure 1A press hydraulic system for metal forming equipment shown in the figure includes three electronically controlled variable pumps to provide a high-pressure hydraulic oil source for the system, namely the first electronically controlled variable pump, the second electronically controlled variable pump, and the third electronically controlled variable pump, and each is provided with a pump head check valve, namely the first check valve, the second check valve, the third check valve, and the fourth check valve, respectively, for preventing the hydraulic oil in the hydraulic cylinder from flowing back to the electronically controlled variable pump.

[0011] When the master cylinder is quickly lowered, the solenoid reversing valve is not energized, the solenoid on the b side of the first three-position four-way solenoid reversing valve is energized, the first electronically controlled variable pump and the second electronically controlled variable pump work simultaneously, connecting the rodless chamber of the master cylinder, and controlling the output flow of the first electronically controlled variable pump and the second electronically controlled variable pump to control the quick lowering speed of the master cylinder.

[0012] Furthermore, a first solenoid valve is arranged between the rod chamber and the rodless chamber of the master cylinder. The first solenoid valve is energized, the rod chamber and the rodless chamber of the master cylinder are connected, and the second solenoid valve is energized, closing the system oil return pipeline, and the master cylinder forms a differential circuit to realize rapid action of the master cylinder.

[0013] During pressurization, the first solenoid valve is not energized, and the rod chamber and rodless chamber of the master cylinder are not connected. The first and second electronically controlled variable pumps supply fluid to the rodless chamber of the master cylinder, the second solenoid valve is not energized, and the rod chamber of the master cylinder is connected to the oil tank. The master cylinder speed is controlled by controlling the total output flow of the first and second electronically controlled variable pumps.

[0014] Furthermore, the third electrically controlled variable pump supplies fluid to the punching cylinder, the electromagnet on the b side of the fourth three-position four-way solenoid reversing valve is energized, the first hydraulic lock is opened under the action of high-pressure oil, the hydraulic oil enters the rodless chamber of the punching cylinder through the first hydraulic lock, and the hydraulic oil in the rod chamber of the punching cylinder returns to the hydraulic oil tank through the first hydraulic lock and the fourth three-position four-way solenoid reversing valve. The speed of the punching cylinder is controlled by controlling the output flow of the third electrically controlled variable pump; the action sequence of the master cylinder and the punching cylinder is controlled by controlling the fourth three-position four-way solenoid reversing valve and the first three-position four-way solenoid reversing valve; the pressure of the punching cylinder is adjusted by controlling the first proportional relief valve; the pressure of the master cylinder is adjusted by controlling the fourth proportional relief valve.

[0015] Furthermore, the ejector cylinder and the demoulding cylinder are passively retracted by the pressure of the main cylinder and the punching cylinder; the rodless chambers of the ejector cylinder and the demoulding cylinder are both provided with proportional relief valves. The retraction pressure of the demoulding cylinder is controlled by controlling the second proportional relief valve; the retraction pressure of the ejector cylinder is controlled by controlling the third proportional relief valve.

[0016] Furthermore, the ejection cylinder and the demolding cylinder are respectively provided with a third hydraulic lock and a second hydraulic lock, and the middle position functions of the third three-position four-way solenoid reversing valve and the second three-position four-way solenoid reversing valve are both Y-type, ensuring that when pressurized, the hydraulic oil in the rodless chamber of the ejection cylinder and the demolding cylinder can only flow back to the oil tank through the second proportional relief valve and the third proportional relief valve.

[0017] Furthermore, the ejection cylinder and the demoulding cylinder have rod cavities respectively provided with a second oil replenishment one-way valve and a first oil replenishment one-way valve.

[0018] When maintaining pressure, the main cylinder and the rodless chamber of the punching cylinder are respectively provided with a first proportional relief valve and a fourth proportional relief valve to achieve stepless regulation of the pressure during maintaining pressure.

[0019] In the first stage of the return stroke, the main cylinder slowly retracts part of the punching cylinder, the punching cylinder fully retracts, and the ejection cylinder fully extends. The electromagnetic reversing valve is energized, and the first electrically controlled variable pump is only connected to the rod chamber of the punching cylinder. The return speed of the punching cylinder is controlled by controlling the output flow of the first electrically controlled variable pump, the ejection cylinder is fully extended, and the first electrically controlled variable pump stops outputting hydraulic oil. During this process, the pressure of the first proportional relief valve is adjusted to 0MPa, and the hydraulic oil in the rodless chamber of the punching cylinder returns to the oil tank through the first proportional relief valve. A first one-way valve is provided between the rod chamber of the punching cylinder and the first electrically controlled variable pump to ensure that when the rod chamber of the punching cylinder is connected to the first electrically controlled variable pump, the hydraulic oil can only flow to the rod chamber of the punching cylinder and cannot flow in the opposite direction.

[0020] Further, the solenoid valve on the a side of the first three-position four-way solenoid reversing valve is energized, the first solenoid valve is not energized, the rod chamber and the rodless chamber of the master cylinder are not connected, the second electrically controlled variable pump is connected to the rod chamber of the master cylinder, and the second electrically controlled variable pump controls the return speed of the master cylinder until a certain stroke is completed, and the second electrically controlled variable pump stops outputting hydraulic oil. During this process, the second solenoid valve is energized, and the master cylinder's non-cavity is connected to the oil tank. The overflow pressure of the fourth proportional relief valve is adjusted to 0MPa, and the hydraulic oil in the master cylinder's non-cavity returns to the oil tank through the second solenoid valve and the fourth proportional relief valve.

[0021] Furthermore, the electromagnet on the b side of the second three-position four-way solenoid reversing valve is energized, the third hydraulic lock is opened under the action of high-pressure oil, the third electrically-controlled variable pump is connected with the rodless chamber of the ejection cylinder, and the rod chamber of the ejection cylinder is connected with the oil tank, so as to realize the extension of the ejection cylinder, and the extension speed of the ejection cylinder is controlled by controlling the output flow of the third electrically-controlled variable pump.

[0022] During the second-stage return stroke, the solenoid valve is not energized, the a-side electromagnet of the first three-position four-way solenoid reversing valve is energized, the second solenoid valve is energized, the second electronically controlled variable pump and the first electronically controlled variable pump are connected to the rod chamber of the master cylinder, and the rodless chamber of the master cylinder is connected to the oil tank, thereby realizing a rapid return stroke of the master cylinder to its initial position.

[0023] Furthermore, the electromagnet on the b side of the third three-position four-way solenoid reversing valve is energized, and the third electrically controlled variable pump is only connected to the rodless chamber of the demolding cylinder. The return speed of the demolding cylinder is controlled by controlling the output flow of the third electrically controlled variable pump until the initial position.

[0024] At this point, a stamping cycle is completed.

[0025] The beneficial effects of the utility model are:

[0026] (1) The utility model adopts a combination of multiple variable pumps to provide hydraulic oil source, so as to realize the actions of quick lowering, pressurizing and returning of the main cylinder of the actuator, extending and returning of the punching cylinder, passive pressing and extending of the ejection cylinder and the demoulding cylinder. The speed control of the actuator is realized by controlling the flow output of the electronically controlled variable pump. Each rodless chamber of the oil cylinder is provided with a proportional relief valve for controlling the stamping pressure. The material forming pressure is precisely controlled and the hydraulic system has high energy efficiency.

[0027] (2) The utility model adopts a differential circuit for the quick lowering of the main cylinder, and realizes pump control through the logical combination of the solenoid valve. The working cylinders do not interfere with each other, have good independence, and have high adjustability of process actions.

[0028] (3) The utility model forms a hydraulic system logic combination through the hydraulic valve, making full use of the flow control function of the electronically controlled variable pump, thereby saving costs and improving the motion control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the working principle of the utility model;

[0030] In the figure, 1, the first proportional relief valve, 2, the first hydraulic lock, 3, the punching cylinder, 4, the second hydraulic lock, 5, the demoulding cylinder, 6, the first oil replenishment check valve, 7, the second proportional relief valve, 8, the third hydraulic lock, 9, the ejection cylinder, 10, the second oil replenishment check valve, 11, the third proportional relief valve, 12, the fourth proportional relief valve, 13, the first solenoid valve, 14, the main cylinder, 15, the first check valve, 16, the solenoid reversing valve, 17, the second check valve, 18, the first electrically controlled variable pump, 19, the second electrically controlled variable pump, 20, the first motor, 21, the third check valve, 22, the second solenoid valve, 23, the first three-position four-way solenoid reversing valve, 24, the second three-position four-way solenoid reversing valve, 25, the third electrically controlled variable pump, 26, the second motor, 27, the fourth check valve, 28, the third three-position four-way solenoid reversing valve, 29, the fourth three-position four-way solenoid reversing valve. DETAILED DESCRIPTION

[0031] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0032] like Figure 1 A press hydraulic system shown includes a main cylinder hydraulic subsystem, a punching cylinder hydraulic subsystem, a demoulding cylinder hydraulic subsystem, and an ejection cylinder hydraulic subsystem;

[0033] The master cylinder hydraulic subsystem includes a second electrically controlled variable pump 19 connected to a first motor 20 at one end, the second electrically controlled variable pump 19 is connected to the first electrically controlled variable pump 18, the output end of the second electrically controlled variable pump 19 is connected to an oil inlet at one end of a first three-position four-way electromagnetic reversing valve 23 through a third one-way valve 21; the output end of the first electrically controlled variable pump 18 is connected to an oil inlet at the same end of the first three-position four-way electromagnetic reversing valve 23 through an electromagnetic reversing valve 16 and a second one-way valve 17 in sequence, and an oil outlet at one end of the first three-position four-way electromagnetic reversing valve 23 is connected to an oil outlet at the fourth proportional relief valve 1 2 is connected, and the other is connected to the rodless chamber of the master cylinder 14. The other end oil outlet of the first three-position four-way electromagnetic reversing valve 23 is connected to the rod chamber of the master cylinder 14; the first electromagnetic valve 13 is connected in parallel between the two oil outlets of the first three-position four-way electromagnetic reversing valve 23; the punching cylinder hydraulic subsystem, the demoulding cylinder hydraulic subsystem, and the ejection cylinder hydraulic subsystem are commonly connected to a third electrically controlled variable pump 25, and the output end of the third electrically controlled variable pump 25 is connected to a fourth one-way valve 27; the punching cylinder hydraulic subsystem includes a fourth three-position four-way electromagnetic reversing valve 29, and the fourth three-position four-way electromagnetic reversing valve 29 is connected to the fourth one-way valve 27. The oil outlet of the magnetic reversing valve 29 is connected to the first hydraulic lock 2, and one of the oil outlets of the first hydraulic lock 2 is connected to the first proportional relief valve 1, and the other is connected to the rod chamber of the punching cylinder 3, and the first proportional relief valve 1 is also connected to the rodless chamber of the punching cylinder 3; the demoulding cylinder hydraulic subsystem includes a third three-position four-way electromagnetic reversing valve 28, and the oil outlet of the third three-position four-way electromagnetic reversing valve 28 is connected to the second hydraulic lock 4, and one of the oil outlets of the second hydraulic lock 4 is connected to the rodless chamber of the demoulding cylinder 5, and the other is connected to the rod chamber of the demoulding cylinder 5, and the two oil outlets of the second hydraulic lock 4 are also connected in parallel There is a first oil replenishment check valve 6 and a second proportional relief valve 7; the ejection cylinder hydraulic subsystem includes a second three-position four-way electromagnetic reversing valve 24, the oil outlet of the second three-position four-way electromagnetic reversing valve 24 is connected to the third hydraulic lock 8, one oil outlet of the third hydraulic lock 8 is connected to the rod chamber of the ejection cylinder 9, and the other oil outlet is connected to the rodless chamber of the ejection cylinder 9. At the same time, the two oil outlets of the third hydraulic lock 8 are also connected in parallel with the second oil replenishment check valve 10 and the third proportional relief valve 11; the oil outlet of the electromagnetic reversing valve 16 is connected to the rod chamber of the punching cylinder 3 and the first hydraulic lock 2 through the first check valve 15.

[0034] Another oil inlet of the first three-position four-way electromagnetic reversing valve 23 is connected to the oil tank through the second electromagnetic valve 22 .

[0035] The third electronically controlled variable displacement pump 25 is connected to the second motor 26 .

[0036] The working process of the utility model is:

[0037] like Figure 1The hydraulic system of a press machine for metal forming equipment shown in the figure includes three electrically controlled variable pumps to provide a high-pressure hydraulic oil source for the system, namely a first electrically controlled variable pump 18, a second electrically controlled variable pump 19, and a third electrically controlled variable pump 25, and each is provided with a pump head check valve, namely a first check valve 15, a second check valve 17, a third check valve 21, and a fourth check valve 27, which are used to prevent the hydraulic oil in the hydraulic cylinder from flowing back to the electrically controlled variable pump.

[0038] When the master cylinder 14 is rapidly lowered, the electromagnetic reversing valve 16 is not energized, the electromagnet on the b side of the first three-position four-way electromagnetic reversing valve 23 is energized, the first electrically controlled variable pump 18 and the second electrically controlled variable pump 19 work simultaneously, connecting the rodless chamber of the master cylinder 14, and controlling the rapid lowering speed of the master cylinder 14 by controlling the output flow of the first electrically controlled variable pump 18 and the second electrically controlled variable pump 19;

[0039] Furthermore, a first solenoid valve 13 is provided between the rod chamber and the rodless chamber of the master cylinder 14. The first solenoid valve 13 is energized, the rod chamber and the rodless chamber of the master cylinder 14 are connected, and the second solenoid valve 22 is energized, closing the system oil return pipeline, and the master cylinder 14 forms a differential circuit, thereby realizing rapid action of the master cylinder 14.

[0040] During pressurization, the first solenoid valve 13 is not energized, and the rod chamber and the rodless chamber of the master cylinder 14 are not connected. The first electrically controlled variable pump 18 and the second electrically controlled variable pump 19 supply fluid to the rodless chamber of the master cylinder 14, the second solenoid valve 22 is not energized, and the rod chamber of the master cylinder 14 is connected to the oil tank. The master cylinder speed is controlled by controlling the sum of the output flow rates of the first electrically controlled variable pump 18 and the second electrically controlled variable pump 19.

[0041] Furthermore, the third electrically controlled variable pump 25 supplies fluid to the punching cylinder 3, the electromagnet on the b side of the fourth three-position four-way solenoid reversing valve 29 is energized, the first hydraulic lock 2 is opened under the action of high-pressure oil, the hydraulic oil enters the rodless chamber of the punching cylinder 3 through the first hydraulic lock 2, and the hydraulic oil in the rod chamber of the punching cylinder 3 returns to the hydraulic oil tank through the first hydraulic lock 2 and the fourth three-position four-way solenoid reversing valve 29. The speed of the punching cylinder is controlled by controlling the output flow of the third electrically controlled variable pump 25; the action sequence of the master cylinder 14 and the punching cylinder 3 is controlled by controlling the fourth three-position four-way solenoid reversing valve 29 and the first three-position four-way solenoid reversing valve 23; the pressure of the punching cylinder 3 is adjusted by controlling the first proportional relief valve 1; the pressure of the master cylinder 14 is adjusted by controlling the fourth proportional relief valve 12;

[0042] Furthermore, the ejector cylinder 9 and the demoulding cylinder 5 are passively retracted by the pressure of the main cylinder 14 and the punching cylinder 3; the rodless chambers of the ejector cylinder 9 and the demoulding cylinder 5 are both provided with proportional relief valves. The retraction pressure of the demoulding cylinder 5 is controlled by controlling the second proportional relief valve 7; the retraction pressure of the ejector cylinder 9 is controlled by controlling the third proportional relief valve 11.

[0043] Furthermore, the ejection cylinder 9 and the demolding cylinder 5 are respectively provided with a third hydraulic lock 8 and a second hydraulic lock 4, and the middle position functions of the third three-position four-way solenoid reversing valve 28 and the second three-position four-way solenoid reversing valve 24 are both Y-type, ensuring that when pressurized, the hydraulic oil in the rodless chamber of the ejection cylinder 9 and the demolding cylinder 5 can only flow back to the oil tank through the second proportional relief valve 7 and the third proportional relief valve 11.

[0044] Furthermore, the ejection cylinder 9 and the demoulding cylinder 5 are provided with a second oil replenishment check valve 10 and a first oil replenishment check valve 6 on the rod cavity, respectively.

[0045] When maintaining pressure, the rodless chambers of the main cylinder 14 and the punching cylinder 3 are respectively provided with a first proportional relief valve 1 and a fourth proportional relief valve 12 to achieve stepless regulation of the pressure during maintaining pressure.

[0046] In the first stage of the return stroke, the main cylinder 14 slowly retracts part of the punching cylinder 3, the punching cylinder 3 is fully retracted, and the ejection cylinder 9 is fully extended. The electromagnetic reversing valve 16 is energized, and the first electrically controlled variable pump 18 is only connected to the rod chamber of the punching cylinder. The return speed of the punching cylinder 3 is controlled by controlling the output flow of the first electrically controlled variable pump 18, the ejection cylinder 9 is fully extended, and the first electrically controlled variable pump 18 stops outputting hydraulic oil. During this process, the pressure of the first proportional relief valve 1 is adjusted to 0MPa, and the hydraulic oil in the rodless chamber of the punching cylinder 3 returns to the oil tank through the first proportional relief valve 1. A first one-way valve 15 is provided between the rod chamber of the punching cylinder and the first electrically controlled variable pump 18 to ensure that when the rod chamber of the punching cylinder 3 is connected to the first electrically controlled variable pump 18, the hydraulic oil can only flow to the rod chamber of the punching cylinder 3 and cannot flow in the opposite direction.

[0047] Further, the a-side solenoid valve of the first three-position four-way solenoid reversing valve 23 is energized, the first solenoid valve 13 is not energized, the rod chamber and the rodless chamber of the master cylinder 14 are not connected, the second electrically controlled variable pump 19 is connected to the rod chamber of the master cylinder 14, and the second electrically controlled variable pump 19 controls the return speed of the master cylinder 14 until a certain stroke is completed, and the second electrically controlled variable pump 19 stops outputting hydraulic oil. During this process, the second solenoid valve 22 is energized, and the non-cavity of the master cylinder 14 is connected to the oil tank. The overflow pressure of the fourth proportional relief valve 12 is adjusted to 0MPa, and the hydraulic oil of the non-cavity of the master cylinder 14 returns to the oil tank through the second solenoid valve 22 and the fourth proportional relief valve 12.

[0048] Furthermore, the electromagnet on the b side of the second three-position four-way solenoid reversing valve 24 is energized, the third hydraulic lock 8 is opened under the action of high-pressure oil, the third electrically-controlled variable pump 25 is connected with the rodless chamber of the ejection cylinder 9, and the rod chamber of the ejection cylinder 9 is connected with the oil tank, so as to realize the extension of the ejection cylinder 9, and the extension speed of the ejection cylinder 9 is controlled by controlling the output flow of the third electrically-controlled variable pump 25.

[0049] During the second-stage return stroke, the solenoid valve 16 is not energized, the a-side electromagnet of the first three-position four-way solenoid reversing valve 23 is energized, the second solenoid valve 22 is energized, the second electrically controlled variable pump 19 and the first electrically controlled variable pump 18 are both connected to the rod chamber of the master cylinder 14, and the rodless chamber of the master cylinder 14 is connected to the oil tank, thereby realizing a rapid return stroke of the master cylinder 14 to its initial position.

[0050] Furthermore, the electromagnet on the b side of the third three-position four-way solenoid reversing valve 28 is energized, and the third electrically controlled variable pump 25 is only connected to the rodless chamber of the demolding cylinder 5. The return speed of the demolding cylinder 5 is controlled by controlling the output flow of the third electrically controlled variable pump 25 until the initial position.

[0051] At this point, a stamping cycle is completed.

[0052] The utility model adopts a combination of multiple variable pumps to provide a hydraulic oil source to realize the actions of fast lowering, pressurization, and return of the main cylinder of the actuator, extension and return of the punching cylinder, passive pressing and extension of the ejection cylinder and the demoulding cylinder. The speed control of the actuator is achieved by controlling the flow output of the electronically controlled variable pump. Each rodless cavity of the oil cylinder is provided with a proportional relief valve for controlling the stamping pressure. The material forming pressure is accurately controlled and the hydraulic system has high working energy efficiency.

[0053] The above are only preferred examples of the present invention. It should be pointed out that for ordinary technicians in this field, under the technical inspiration provided by the present invention, as common knowledge in the hydraulic field, other equivalent variations and improvements can be made, which should also be regarded as the protection scope of the present invention.

Claims

1. A hydraulic system for a press, characterized in that: It includes the main cylinder hydraulic subsystem, punching cylinder hydraulic subsystem, demoulding cylinder hydraulic subsystem and ejection cylinder hydraulic subsystem; The master cylinder hydraulic subsystem comprises a second electrically controlled variable pump (19) having one end connected to a first motor (20), the second electrically controlled variable pump (19) being connected to the first electrically controlled variable pump (18), the output end of the second electrically controlled variable pump (19) being connected to an oil inlet at one end of a first three-position four-way electromagnetic reversing valve (23) through a third one-way valve (21); the output end of the first electrically controlled variable pump (18) being connected to an oil inlet at the same end of the first three-position four-way electromagnetic reversing valve (23) through an electromagnetic reversing valve (16) and a second one-way valve (17) in sequence, one end of an oil outlet of the first three-position four-way electromagnetic reversing valve (23) being connected to a fourth proportional relief valve (12) on one side and to a rodless chamber of the master cylinder (14) on the other side, and the other end of an oil outlet of the first three-position four-way electromagnetic reversing valve (23) being connected to a rod chamber of the master cylinder (14); the first electromagnetic valve (13) being connected in parallel between the two oil outlets of the first three-position four-way electromagnetic reversing valve (23); The punching cylinder hydraulic subsystem, the demoulding cylinder hydraulic subsystem, and the ejection cylinder hydraulic subsystem are commonly connected to a third electrically controlled variable pump (25), and the output end of the third electrically controlled variable pump (25) is connected to a fourth non-return valve (27); the punching cylinder hydraulic subsystem comprises a fourth three-position four-way electromagnetic reversing valve (29), the oil outlet of the fourth three-position four-way electromagnetic reversing valve (29) is connected to the first hydraulic lock (2), one oil outlet of the first hydraulic lock (2) is connected to the first proportional relief valve (1), and the other oil outlet is connected to the rod chamber of the punching cylinder (3), and the first proportional relief valve (1) is simultaneously connected to the rodless chamber of the punching cylinder (3); The demoulding cylinder hydraulic subsystem comprises a third three-position four-way electromagnetic reversing valve (28), the oil outlet of the third three-position four-way electromagnetic reversing valve (28) is connected to the second hydraulic lock (4), one oil outlet of the second hydraulic lock (4) is connected to the rodless chamber of the demoulding cylinder (5), and the other oil outlet is connected to the rod chamber of the demoulding cylinder (5), and at the same time, the two oil outlets of the second hydraulic lock (4) are also connected in parallel with a first oil replenishment check valve (6) and a second proportional relief valve (7); The ejection cylinder hydraulic subsystem comprises a second three-position four-way electromagnetic reversing valve (24), the oil outlet of the second three-position four-way electromagnetic reversing valve (24) being connected to a third hydraulic lock (8), one oil outlet of the third hydraulic lock (8) being connected to a rod chamber of the ejection cylinder (9) and the other oil outlet of the third hydraulic lock (8) being connected to a rodless chamber of the ejection cylinder (9), and the two oil outlets of the third hydraulic lock (8) being connected in parallel to a second oil replenishment check valve (10) and a third proportional relief valve (11); The oil outlet of the electromagnetic reversing valve (16) is connected to the rod chamber of the punching cylinder (3) and the first hydraulic lock (2) via the first one-way valve (15).

2. A press hydraulic system according to claim 1, characterized in that: The other oil inlet of the first three-position four-way solenoid reversing valve (23) is connected to the oil tank via the second solenoid valve (22).

3. A press hydraulic system according to claim 2, characterized in that: The third electrically controlled variable displacement pump (25) is connected to the second motor (26).

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