Hydraulic machine differential hydraulic control system and method with back pressure

Abstract

The invention belongs to the technical field of metal extrusion forming, and particularly provides a hydraulic machine differential hydraulic control system and method with back pressure, one path of an oil source is connected with a side cylinder large cavity through a side cylinder large cavity liquid inlet valve, and the side cylinder large cavity is connected with an oil tank through a side cylinder large cavity liquid discharge valve; the other path of the oil source is connected with a side cylinder small cavity through a side cylinder small cavity liquid inlet valve, and the side cylinder small cavity is connected with the oil tank through a side cylinder small cavity liquid discharge valve; and the cartridge valve control unit is respectively connected with the side cylinder large cavity and the side cylinder small cavity through cartridge valves, so that the problem that the movable cross beam and the main plunger can not work under the action of self weight of the movable cross beam and the main plunger when a common differential valve is only added between the side cylinder large cavity and the side cylinder small cavity and a differential function is started due to the heavy weight of the movable cross beam, the main plunger and the like of the existing vertical press is solved. On the basis that the installed power and the investment cost of the hydraulic machine are not increased, the idle stroke descending speed of the movable cross beam of the hydraulic machine is effectively increased, and then the production efficiency and the safety of the hydraulic machine are improved.

Description

Technical Field

[0001] This invention belongs to the field of metal extrusion forming technology, specifically relating to a differential hydraulic control system and method for a hydraulic press with back pressure. Background Technology

[0002] The idle movement of the moving crossbeam of the vertical hydraulic press is driven by the side cylinder. In order to improve the production efficiency of the hydraulic press and reduce the production cost, it is necessary to further increase the movement speed of the side cylinder.

[0003] Currently, the descent of a vertical hydraulic press is driven by hydraulic oil supplying fluid into the large chamber of the side cylinder through the inlet valve. To control the overall cost and energy consumption of the hydraulic press, the hydraulic oil flow rate is determined based on the main cylinder's operating speed. Some hydraulic presses have a relatively small oil flow rate, and the side cylinder's descent motion utilizes the maximum hydraulic oil flow rate. Since the cross-sectional area of ​​the large chamber of the side cylinder is typically twice that of the small chamber, the maximum descent speed is half the maximum ascent speed, which to some extent limits the press's production efficiency.

[0004] Chinese patent document CN201264383Y discloses a differential circuit system for a hydraulic press. In this document, when the slide block descends, the hydraulic oil in the lower chamber of the hydraulic cylinder is regulated by a speed control valve and then enters the upper oil pipeline through a solenoid valve, merging with the pumped oil into the upper chamber of the hydraulic cylinder, allowing the slide block to descend at a relatively high speed. When the slide block contacts the workpiece, the solenoid valve closes, and the oil pressure in the upper chamber of the hydraulic cylinder increases relatively slowly. At this time, the slide block descends at a relatively slow speed, which can meet the process requirements of the slide block. However, this document does not address the problem that, due to the significant weight of the moving crossbeam and main plunger of the vertical press, if only ordinary differential valves are added between the large and small chambers of the side cylinder and the differential function is activated, the moving crossbeam and main plunger will move uncontrollably downwards under their own weight, creating a dangerous situation. Summary of the Invention

[0005] The present invention provides a differential hydraulic control system and method for a hydraulic press with back pressure. The purpose is to overcome the problem in the prior art that, due to the large weight of the moving crossbeam and main plunger of the vertical press, if only ordinary differential valves are added between the large and small chambers of the side cylinder and the differential function is activated, the moving crossbeam and main plunger will move uncontrollably downward under their own weight, creating a dangerous factor.

[0006] Therefore, the present invention provides a differential hydraulic control system for a hydraulic press with back pressure, including an oil source, a side cylinder large chamber inlet valve, a side cylinder large chamber outlet valve, a side cylinder small chamber inlet valve, a side cylinder small chamber outlet valve, a cartridge valve, a cartridge valve control unit, a side cylinder, and an oil tank. One oil source is connected to the side cylinder large chamber via the side cylinder large chamber inlet valve, and the side cylinder large chamber is connected to the oil tank via the side cylinder large chamber outlet valve. The other oil source is connected to the side cylinder small chamber via the side cylinder small chamber inlet valve, and the side cylinder small chamber is connected to the oil tank via the side cylinder small chamber outlet valve. The cartridge valve control unit is connected to the side cylinder large chamber and the side cylinder small chamber respectively via the cartridge valve. Preferably, it also includes an overflow valve, and the side cylinder small chamber is connected to the oil tank through the overflow valve and the side cylinder small chamber drain valve respectively.

[0007] Preferably, the cartridge valve control unit includes a throttling line, a solenoid valve, and a second relief valve. One of the P ports of the solenoid valve is connected to the C port of the cartridge valve, and the other P port of the solenoid valve is connected to the large chamber and the small chamber of the side cylinder respectively through the throttling line. The B port of the solenoid valve is connected to the P port of the second relief valve. The T ports of the solenoid valve and the T ports of the second relief valve are both connected to the oil tank. The A port of the cartridge valve is connected to the small chamber of the side cylinder, and the B port of the cartridge valve is connected to the large chamber of the side cylinder.

[0008] Preferably, the throttling line includes throttling line one and throttling line two. The P port of the solenoid valve is connected to the small chamber of the side cylinder through throttling line one, and the P port of the solenoid valve is connected to the large chamber of the side cylinder through throttling line two.

[0009] Preferably, both the first throttling line and the second throttling line are unidirectional throttling lines.

[0010] Preferably, both the first throttling line and the second throttling line are equipped with one-way throttling plugs.

[0011] A differential hydraulic control method for a hydraulic press with back pressure includes the following steps: S1. Determine the minimum pressure of the movable component supported by the side cylinder small cavity, wherein the movable component includes a movable crossbeam and a main plunger; S2. Based on the minimum pressure of the movable component supported by the side cylinder cavity determined in step S1, set the overflow pressure of overflow valve two. S3. When the movable crossbeam is in the initial state, the side cylinder large chamber inlet valve, side cylinder large chamber outlet valve, side cylinder small chamber inlet valve, and side cylinder small chamber outlet valve are all closed, the cartridge valve control unit is not energized, and the movable crossbeam stops moving under the pressure support of the side cylinder small chamber. S4. When the movable crossbeam is ready to descend during the idle stroke, the cartridge valve control unit is energized, and the movable crossbeam stops moving under the pressure support of the small chamber of the side cylinder. S5. When the movable crossbeam descends during its free-stroke descent, the cartridge valve control unit is energized, the side cylinder large chamber inlet valve opens, and the side cylinder large chamber is filled with liquid to build up pressure. Under the action of the side cylinder large chamber pressure, the side cylinder small chamber pressure gradually rises until the pressure at port A of the cartridge valve is greater than the pressure at port C of the cartridge valve. The cartridge valve then opens, and the fluid in the side cylinder small chamber flows from the cartridge valve to the side cylinder large chamber, realizing the rapid descent of the movable crossbeam. S6. During the working stroke of the hydraulic press, the cartridge valve control unit is not energized. With the inlet valve of the large chamber of the side cylinder open, the outlet valve of the small chamber of the side cylinder opens, and the pressure in the small chamber of the side cylinder drops to 0. At this time, the cartridge valve closes, and the hydraulic press works normally. S7. When the movable crossbeam rises during free travel, the side cylinder large chamber inlet valve and the side cylinder small chamber drain valve are closed, while the side cylinder large chamber drain valve and the side cylinder small chamber inlet valve are open. The cartridge valve control unit is not energized, the cartridge valve is closed, and the hydraulic press operates normally.

[0012] Preferably, in step S1, the minimum pressure of the movable component supported by the side cylinder cavity is determined based on the mass of the movable component to be supported and the cross-sectional area of ​​the side cylinder cavity.

[0013] Preferably, the formula for calculating the minimum pressure of the movable component supported by the side cylinder cavity is: Where: m is the mass of the moving part that needs to be supported; This refers to the cross-sectional area of ​​the small cavity of the side cylinder; g It is the acceleration due to gravity; P 最小 The minimum pressure required to support the moving parts of the side cylinder's small chamber.

[0014] Preferably, in step S2, the overflow pressure of the second overflow valve is 1.5-2 times the rated pressure. P 最小 .

[0015] The beneficial effects of this invention are: The differential hydraulic control system and method for a hydraulic press with back pressure provided by this invention generates back pressure on the small cavity of the side cylinder to support the weight of the moving parts such as the moving crossbeam during the rapid descent of the moving crossbeam. This achieves effective control of the movement of the moving crossbeam during the differential rapid descent of the side cylinder, and ultimately improves the speed of the moving crossbeam's descent without increasing the installed power and investment cost of the hydraulic press, thereby improving the production efficiency and safety of the hydraulic press. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the differential hydraulic control system of a hydraulic press with back pressure. Figure 2This is a flowchart of the control method for a differential hydraulic control system of a hydraulic press with back pressure.

[0018] Explanation of reference numerals in the attached diagram: 1. Oil source; 2. Side cylinder large chamber inlet valve; 3. Side cylinder large chamber outlet valve; 4. Side cylinder small chamber inlet valve; 5. Side cylinder small chamber outlet valve; 6. Overflow valve one; 7. Cartridge valve; 8. Throttling line one; 9. Throttling line two; 10. Solenoid valve; 11. Overflow valve two; 12. Side cylinder; 13. Oil cylinder. Detailed Implementation

[0019] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0020] Example 1: like Figure 1 As shown, a differential hydraulic control system for a hydraulic press with back pressure includes an oil source 1, a side cylinder large chamber inlet valve 2, a side cylinder large chamber outlet valve 3, a side cylinder small chamber inlet valve 4, a side cylinder small chamber outlet valve 5, a cartridge valve 7, a cartridge valve control unit, a side cylinder 12, and an oil tank 13. One path of the oil source 1 is connected to the large chamber of the side cylinder 12 via the side cylinder large chamber inlet valve 2, and the large chamber of the side cylinder 12 is connected to the oil tank 13 via the side cylinder large chamber outlet valve 3. Another path of the oil source 1 is connected to the small chamber of the side cylinder 12 via the side cylinder small chamber inlet valve 4, and the small chamber of the side cylinder 12 is connected to the oil tank 13 via the side cylinder small chamber outlet valve 5. The cartridge valve control unit is connected to both the large chamber and the small chamber of the side cylinder 12 via the cartridge valve 7. Specifically, such as Figure 2 As shown, the control method of the differential hydraulic control system of the hydraulic press with back pressure of the present invention is as follows: When the movable crossbeam is in the initial state, the side cylinder large chamber inlet valve 2, side cylinder large chamber outlet valve 3, side cylinder small chamber inlet valve 4, and side cylinder small chamber outlet valve 5 are all closed, the cartridge valve control unit is not energized, and the movable crossbeam stops moving under the pressure support of the side cylinder 12 small chamber. When the movable crossbeam is ready to descend during its idle stroke, the cartridge valve control unit is energized, and the movable crossbeam stops moving under the pressure support of the small chamber of the side cylinder 12. When the movable crossbeam descends during its idle stroke, the cartridge valve control unit is energized, the side cylinder large chamber inlet valve 2 opens, and the side cylinder 12 large chamber is filled with liquid to build up pressure. Under the action of the pressure in the side cylinder 12 large chamber, the pressure in the side cylinder 12 small chamber gradually rises until the pressure at port A of cartridge valve 7 is greater than the pressure at port C of cartridge valve 7. Then cartridge valve 7 opens, and the fluid in the side cylinder 12 small chamber flows from cartridge valve 7 to the side cylinder 12 large chamber, realizing the rapid descent of the movable crossbeam. During the working stroke of the hydraulic press, the cartridge valve control unit is not energized. With the side cylinder large chamber inlet valve 2 open, the side cylinder small chamber drain valve 5 opens, and the pressure in the side cylinder 12 small chamber drops to 0. At this time, the cartridge valve 7 closes, and the hydraulic press works normally. When the moving crossbeam rises during idle stroke, the side cylinder large chamber inlet valve 2 and the side cylinder small chamber outlet valve 5 are closed, the side cylinder large chamber outlet valve 3 and the side cylinder small chamber inlet valve 4 are open, the cartridge valve control unit is not energized, the cartridge valve 7 is closed, and the hydraulic press works normally. When the movable crossbeam descends rapidly, the system generates back pressure on the small chamber of the side cylinder 12 to support the weight of the moving parts such as the movable crossbeam. When the side cylinder 12 descends differentially, the movement of the movable crossbeam is effectively controlled. Ultimately, without increasing the installed power and investment cost of the hydraulic press, the speed of the movable crossbeam's descent during idle stroke is effectively improved, thereby improving the production efficiency and safety of the hydraulic press.

[0021] Example 2: Based on Example 1, it also includes an overflow valve 6, and the small chamber of the side cylinder 12 is connected to the oil tank 13 through the overflow valve 6 and the drain valve 5 of the small chamber of the side cylinder.

[0022] Specifically, the relief valve 6 can limit the maximum pressure of the small chamber of the side cylinder 12, preventing damage to the small chamber of the side cylinder 12, the pipelines and other components in the system due to excessive pressure, improving the safety and reliability of the system, and avoiding overpressure failures. At the same time, the relief valve 6, in conjunction with the drain valve 5 of the small chamber of the side cylinder, can accurately control the on / off state and flow rate of the hydraulic return oil tank 13 of the drain valve 5 of the small chamber of the side cylinder, and can also adjust the draining speed as needed. The relief valve 6 can also maintain the pressure stability of the small chamber of the side cylinder 12 and its draining circuit, avoiding pressure fluctuations from affecting the working accuracy of the side cylinder 12, and making the side cylinder 12 move more smoothly.

[0023] Preferably, the cartridge valve control unit includes a throttling line, a solenoid valve 10, and a relief valve 11. One of the P ports of the solenoid valve 10 is connected to the C port of the cartridge valve 7, and the other of the P port of the solenoid valve 10 is connected to the large chamber and the small chamber of the side cylinder 12 respectively through the throttling line. The B port of the solenoid valve 10 is connected to the P port of the relief valve 11. The T ports of the solenoid valve 10 and the T ports of the relief valve 11 are both connected to the oil tank 13. The A port of the cartridge valve 7 is connected to the small chamber of the side cylinder 12, and the B port of the cartridge valve 7 is connected to the large chamber of the side cylinder 12.

[0024] Specifically, the throttling line controls the opening and closing speed of the cartridge valve 7 by limiting the hydraulic oil flow, achieving stepless speed regulation and shock suppression. The on / off state of the solenoid valve 10 directly controls the oil circuit of the throttling line, improving system response speed and working efficiency. During the operation of the cartridge valve 7, the relief valve 11 can dynamically balance the pressure in the large and small chambers of the side cylinder 12, avoiding pressure fluctuations caused by changes in oil compressibility or pipeline resistance, and ensuring the stability of the cartridge valve 7's operation.

[0025] Preferably, the throttling line includes throttling line 8 and throttling line 9. The P port of the solenoid valve 10 is connected to the small chamber of the side cylinder 12 through throttling line 8, and the P port of the solenoid valve 10 is connected to the large chamber of the side cylinder 12 through throttling line 9.

[0026] Specifically, the P port of solenoid valve 10 is connected to the small chamber and the large chamber of side cylinder 12 through throttling line 8 and throttling line 9 respectively. That is, the P port of solenoid valve 10 adjusts the flow rate of the small chamber of side cylinder 12 through throttling line 8, and the P port of solenoid valve 10 adjusts the flow rate of the large chamber of side cylinder 12 through throttling line 9. This achieves independent adjustment of the flow rate of the small chamber and the large chamber of side cylinder 12. Essentially, it is through differentiated throttling control that the cross-sectional area requirements of different chambers are matched, the pressure change caused by the area difference is alleviated, and the back pressure control improves the smoothness of movement.

[0027] Preferably, both the first throttling line 8 and the second throttling line 9 are unidirectional throttling lines.

[0028] Specifically, a one-way throttling pipeline can generate back pressure through throttling to counteract load inertia or gravity.

[0029] Preferably, both the first throttling line 8 and the second throttling line 9 are equipped with one-way throttling plugs.

[0030] Specifically, the one-way throttle plug integrates the functions of a one-way valve and a throttle valve into a single component, reducing the number of valves and pipe joints, lowering the risk of leakage, and having a small installation size and light weight. One-way throttle plugs mostly use cartridge or threaded connections, so disassembly does not require damaging the entire oil circuit and is easy to clean.

[0031] Example 3: Based on Example 2, a differential hydraulic control method for a hydraulic press with back pressure includes the following steps: S1. Determine the minimum pressure of the movable component supported by the small chamber of the side cylinder 12, wherein the movable component includes a movable crossbeam and a main plunger; S2. Based on the minimum pressure of the movable part supported by the small cavity of the side cylinder 12 determined in step S1, set the overflow pressure of the overflow valve 11. S3. When the movable crossbeam is in the initial state, the side cylinder large chamber inlet valve 2, side cylinder large chamber outlet valve 3, side cylinder small chamber inlet valve 4, and side cylinder small chamber outlet valve 5 are all closed. The cartridge valve control unit is not energized, and the movable crossbeam stops moving under the pressure support of the side cylinder 12 small chamber. S4. When the movable crossbeam is ready to descend during the idle stroke, the cartridge valve control unit is energized, and the movable crossbeam stops moving under the pressure support of the small chamber of the side cylinder 12. S5. When the movable crossbeam descends during its free-stroke descent, the cartridge valve control unit is energized, the side cylinder large chamber inlet valve 2 opens, and the side cylinder 12 large chamber is filled with liquid to build up pressure. Under the action of the side cylinder 12 large chamber pressure, the side cylinder 12 small chamber pressure gradually rises until the pressure at port A of cartridge valve 7 is greater than the pressure at port C of cartridge valve 7. Then cartridge valve 7 opens, and the fluid in the side cylinder 12 small chamber flows from cartridge valve 7 to the side cylinder 12 large chamber, realizing the rapid descent of the movable crossbeam. S6. During the working stroke of the hydraulic press, the cartridge valve control unit is not energized. With the side cylinder large chamber inlet valve 2 open, the side cylinder small chamber drain valve 5 opens, and the pressure in the side cylinder 12 small chamber drops to 0. At this time, the cartridge valve 7 closes, and the hydraulic press works normally. S7. When the movable crossbeam rises during free travel, the side cylinder large chamber inlet valve 2 and the side cylinder small chamber drain valve 5 are closed, the side cylinder large chamber drain valve 3 and the side cylinder small chamber inlet valve 4 are open, the cartridge valve control unit is not energized, the cartridge valve 7 is closed, and the hydraulic press works normally.

[0032] Specifically, when the movable crossbeam descends rapidly, this system generates back pressure on the small chamber of the side cylinder 12 to support the weight of the moving components such as the movable crossbeam. When the side cylinder 12 descends differentially, it effectively controls the movement of the movable crossbeam. Ultimately, without increasing the installed power and investment cost of the hydraulic press, it effectively improves the speed of the movable crossbeam's descent during idle stroke, thereby improving the production efficiency and safety of the hydraulic press.

[0033] Preferably, in step S1, the minimum pressure of the movable component supported by the small cavity of the side cylinder 12 is determined based on the mass of the movable component to be supported and the cross-sectional area of ​​the small cavity of the side cylinder 12.

[0034] Specifically, this ensures that the small chamber of the side cylinder 12 can stably support the moving parts.

[0035] Preferably, the formula for calculating the minimum pressure of the movable component supported by the small cavity of the side cylinder 12 is as follows: Where: m is the mass of the moving part that needs to be supported; This refers to the cross-sectional area of ​​the small chamber of the side cylinder 12; g It is the acceleration due to gravity; P 最小 The minimum pressure for the moving parts supporting the small chamber of the side cylinder 12.

[0036] Specifically, this calculation method is simple, practical, and highly accurate.

[0037] Preferably, in step S2, the overflow pressure of the overflow valve 11 is 1.5-2 times the rated pressure. P 最小 .

[0038] Specifically, this pressure enables the small chamber of the side cylinder 12 to reliably and smoothly support the moving parts.

[0039] Example 4: Based on Example 3, a differential hydraulic control method for a hydraulic press with back pressure includes the following steps: S1. Based on the required mass of the movable component being supported and the cross-sectional area of ​​the small cavity of the side cylinder 12, determine the minimum pressure exerted on the movable component supported by the small cavity of the side cylinder 12. The movable component includes a movable crossbeam and a main plunger; S2. Based on the minimum pressure of the movable component supported by the small cavity of the side cylinder 12 determined in step S1, set the overflow pressure of the overflow valve 11 to 1.5-2 times the minimum pressure. P 最小 ; S3. When the movable crossbeam is in its initial state, the side cylinder large chamber inlet valve 2, side cylinder large chamber outlet valve 3, side cylinder small chamber inlet valve 4, and side cylinder small chamber outlet valve 5 are all closed. Solenoid valve 10 is not energized, and the P port of solenoid valve 10 is connected to the A port of solenoid valve 10. Pressure is generated in the small chamber of side cylinder 12 due to the weight of the movable parts. Since port C (control port) of cartridge valve 7 is connected to the small chamber of side cylinder 12 through throttling line 8, the pressure at port C of cartridge valve 7 is the same as the pressure at port A of cartridge valve 7, both being... The cartridge valve 7 is closed; the movable crossbeam stops moving under the pressure support of the small chamber of the side cylinder 12. S4. When the movable crossbeam is ready to descend during idle stroke, solenoid valve 10 is energized, and port P of solenoid valve 10 is connected to port B. At this time, the pressure at port C of cartridge valve 7 and port P of relief valve 11 are both... The pressure at port C of cartridge valve 7 is less than that of the cartridge valve. Overflow valve 11 is closed, cartridge valve 7 is closed, and the movable crossbeam stops moving under the pressure support of the small chamber of side cylinder 12; S5. When the movable crossbeam descends during its free-stroke descent, the inlet valve 2 of the large chamber of the side cylinder opens, and pressure is established in the large chamber of the side cylinder 12. Under the pressure of the large chamber of the side cylinder 12, the pressure in the small chamber of the side cylinder 12... Depend on It began to rise gradually: when At that time, the pressure at port A of cartridge valve 7 is The pressure at port P of relief valve 211 rises to At this time, relief valve 21 begins to overflow; fluid flows from port A of cartridge valve 7 through throttling line 18, solenoid valve 10, and relief valve 21 back to oil tank 13; due to the throttling effect of throttling line 18 and the overflow effect of relief valve 21, a pressure drop occurs at the inlet and outlet of throttling line 18, with the inlet pressure being... Export pressure is That is, the pressure at port C of cartridge valve 7 is Due to the pressure at port A of cartridge valve 7 The pressure at port C of cartridge valve 7 is greater than the pressure at port C. When cartridge valve 7 is opened, fluid in the small chamber of side cylinder 12 flows from cartridge valve 7 to the large chamber of side cylinder 12, enabling the rapid descent of the movable crossbeam. S6. During the working stroke of the hydraulic press, solenoid valve 10 is not energized, and the P port of solenoid valve 10 is connected to the A port of solenoid valve 10. With the inlet valve 2 of the large chamber of the side cylinder open, the outlet valve 5 of the small chamber of the side cylinder opens. At this time, the pressure in the small chamber of the side cylinder 12 drops to 0, and the pressure in the large chamber of the side cylinder 12 rises to the working pressure. The large chamber of side cylinder 12 is connected to port C of cartridge valve 7 via throttling line 29, and the pressure at port C of cartridge valve 7 also changes. At this point, cartridge valve 7 is closed, and the hydraulic press operates normally; S7. When the movable crossbeam rises during free travel, the side cylinder large chamber inlet valve 2 and the side cylinder small chamber drain valve 5 are closed, the side cylinder large chamber drain valve 3 and the side cylinder small chamber inlet valve 4 are open, the cartridge valve control unit is not energized, the cartridge valve 7 is closed, and the hydraulic press works normally.

[0040] When the moving crossbeam rises during free travel, the side cylinder large chamber inlet valve 2 and the side cylinder small chamber outlet valve 5 are closed, while the side cylinder large chamber outlet valve 3 and the side cylinder small chamber inlet valve 4 are open. The solenoid valve 10 is not energized, and the P port of the solenoid valve 10 is connected to the A port of the solenoid valve 10. At this time, the side cylinder 12 small chamber is inlet, and the side cylinder 12 large chamber is outlet. The side cylinder 12 small chamber is connected to the C port of the cartridge valve 7 through the throttling line 8. The pressure at the C port of the cartridge valve 7 is the same as the pressure at the A port of the cartridge valve 7. The cartridge valve 7 is closed, and the hydraulic press operates normally.

[0041] This method generates back pressure on the small chamber of the side cylinder 12 during the rapid descent of the movable crossbeam, supporting the weight of the moving components such as the movable crossbeam. During the differential descent of the side cylinder 12, it effectively controls the movement of the movable crossbeam. Ultimately, without increasing the installed power and investment cost of the hydraulic press, it effectively improves the descent speed of the movable crossbeam during idle stroke, thereby improving the production efficiency of the hydraulic press.

[0042] In the description of this invention, it should be understood that if any term indicates an orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are for illustrative purposes only and should not be construed as limiting the invention.

[0043] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A differential hydraulic control system for a hydraulic press with back pressure, characterized in that: It includes an oil source (1), a side cylinder large chamber inlet valve (2), a side cylinder large chamber outlet valve (3), a side cylinder small chamber inlet valve (4), a side cylinder small chamber outlet valve (5), a cartridge valve (7), a cartridge valve control unit, a side cylinder (12), and an oil tank (13). One oil source (1) is connected to the large chamber of the side cylinder (12) via the side cylinder large chamber inlet valve (2), and the large chamber of the side cylinder (12) is connected to the oil tank (13) via the side cylinder large chamber outlet valve (3). Another oil source (1) is connected to the small chamber of the side cylinder (12) via the side cylinder small chamber inlet valve (4), and the small chamber of the side cylinder (12) is connected to the oil tank (13) via the side cylinder small chamber outlet valve (5). The cartridge valve control unit is connected to the large chamber of the side cylinder (12) and the small chamber of the side cylinder (12) respectively via the cartridge valve (7).

2. The differential hydraulic control system for a hydraulic press with back pressure as described in claim 1, characterized in that: It also includes an overflow valve (6), and the side cylinder (12) small chamber is connected to the oil tank (13) through the overflow valve (6) and the side cylinder small chamber drain valve (5).

3. The differential hydraulic control system for a hydraulic press with back pressure as described in claim 1, characterized in that: The cartridge valve control unit includes a throttling line, a solenoid valve (10), and a relief valve (11). One of the P ports of the solenoid valve (10) is connected to the C port of the cartridge valve (7), and the other of the P port of the solenoid valve (10) is connected to the large chamber and the small chamber of the side cylinder (12) respectively through the throttling line. The B port of the solenoid valve (10) is connected to the P port of the relief valve (11). The T ports of the solenoid valve (10) and the T ports of the relief valve (11) are both connected to the oil tank (13). The A port of the cartridge valve (7) is connected to the small chamber of the side cylinder (12), and the B port of the cartridge valve (7) is connected to the large chamber of the side cylinder (12).

4. The differential hydraulic control system for a hydraulic press with back pressure as described in claim 3, characterized in that: The throttling pipeline includes throttling pipeline one (8) and throttling pipeline two (9). The P port of the solenoid valve (10) is connected to the small chamber of the side cylinder (12) through throttling pipeline one (8), and the P port of the solenoid valve (10) is connected to the large chamber of the side cylinder (12) through throttling pipeline two (9).

5. The differential hydraulic control system for a hydraulic press with back pressure as described in claim 4, characterized in that: Both the first throttling line (8) and the second throttling line (9) are unidirectional throttling lines.

6. The differential hydraulic control system for a hydraulic press with back pressure as described in claim 4, characterized in that: One-way throttling plugs are installed on both the first throttling line (8) and the second throttling line (9).

7. A differential hydraulic control method for a hydraulic press with back pressure, characterized in that: Includes the following steps: S1. Determine the minimum pressure of the movable component supported by the small cavity of the side cylinder (12), the movable component including the movable crossbeam and the main plunger; S2. Based on the minimum pressure of the movable part supported by the small cavity of the side cylinder (12) determined in step S1, set the overflow pressure of the overflow valve (11). S3. When the moving crossbeam is in the initial state, the side cylinder large chamber inlet valve (2), side cylinder large chamber outlet valve (3), side cylinder small chamber inlet valve (4), and side cylinder small chamber outlet valve (5) are all closed. The cartridge valve control unit is not energized, and the moving crossbeam stops moving under the pressure support of the side cylinder (12) small chamber. S4. When the movable crossbeam is ready to descend during the idle stroke, the cartridge valve control unit is energized, and the movable crossbeam stops moving under the pressure of the small chamber of the side cylinder (12). S5. When the movable crossbeam descends during the idle stroke, the cartridge valve control unit is energized, the side cylinder large chamber inlet valve (2) opens, the side cylinder (12) large chamber is filled with liquid to build up pressure, under the action of the side cylinder (12) large chamber pressure, the side cylinder (12) small chamber pressure gradually rises until the pressure at port A of cartridge valve (7) is greater than the pressure at port C of cartridge valve (7), cartridge valve (7) opens, and the fluid in the side cylinder (12) small chamber flows from cartridge valve (7) to the side cylinder (12) large chamber, realizing the rapid descent of the movable crossbeam; S6. During the working stroke of the hydraulic press, the cartridge valve control unit is not energized. With the side cylinder large chamber inlet valve (2) open, the side cylinder small chamber drain valve (5) opens, and the pressure in the side cylinder (12) small chamber drops to 0. At this time, the cartridge valve (7) closes, and the hydraulic press works normally. S7. When the moving crossbeam rises during free travel, the side cylinder large chamber inlet valve (2) and the side cylinder small chamber drain valve (5) are closed, the side cylinder large chamber drain valve (3) and the side cylinder small chamber inlet valve (4) are open, the cartridge valve control unit is not energized, the cartridge valve (7) is closed, and the hydraulic press works normally.

8. The differential hydraulic control method for a hydraulic press with back pressure as described in claim 7, characterized in that: Step S1 determines the minimum pressure of the movable component supported by the small cavity of the side cylinder (12) based on the mass of the movable component to be supported and the cross-sectional area of ​​the small cavity of the side cylinder (12).

9. The differential hydraulic control method for a hydraulic press with back pressure as described in claim 7, characterized in that: The formula for calculating the minimum pressure of the movable component supported by the small cavity of the side cylinder (12) is as follows: Where: m is the mass of the moving part that needs to be supported; The cross-sectional area of ​​the small cavity of the side cylinder (12); g It is the acceleration due to gravity; P 最小 The minimum pressure of the moving part that supports the small cavity of the side cylinder (12).

10. The differential hydraulic control method for a hydraulic press with back pressure as described in claim 7, characterized in that: In step S2, the overflow pressure of overflow valve two (11) is 1.5-2 times the rated pressure. P 最小 .

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