Closed hydraulic system and control method of a quick forging press

Abstract

The application discloses a closed hydraulic system of a quick forging press and a control method, and belongs to the technical field of hydraulic control of quick forging presses. The hydraulic system comprises a main cylinder, a return cylinder, a movable beam, a hydraulic pump set and an accumulator set. The hydraulic pump set is a closed variable pump set. The closed hydraulic system further comprises a proportional cartridge valve and a check valve. A closed hydraulic circuit is formed among the closed variable pump set, the main cylinder, the return cylinder and the accumulator set. The proportional cartridge valve is arranged on the oil circuit of the main cylinder and is used for controlling pressure relief of the main cylinder. The check valve is connected with the accumulator set and the oil suction port of the closed variable pump set and is used for supplementing oil for the closed variable pump set during pressing. The closed variable pump set controls the flow and direction of hydraulic oil by adjusting the size and direction of the swash plate swing angle, drives the quick forging press to complete the pressing, pressure relief and return actions, and has no throttling loss in the whole system action. The application discloses a closed variable pump volume speed regulation method which discards the valve port throttling control and has no throttling loss in the whole process, and the comprehensive energy saving rate reaches 40%-50%.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology for high-speed forging presses, and more specifically, to a closed-loop hydraulic system and control method for high-speed forging presses. Background Technology

[0002] High-speed forging presses are core equipment in the field of precision metal forging. Among them, small-tonnage high-speed forging presses with a tonnage of less than 10MN are widely used in working conditions with stringent requirements for installation space, operating energy consumption, control accuracy and dynamic response due to their suitability for precision small parts forging and strong site adaptability.

[0003] Currently, the hydraulic drive system of small-tonnage high-speed forging presses generally adopts an open hydraulic circuit with a fixed displacement pump and a proportional valve. This solution relies on the throttling of the proportional valve orifice to achieve flow regulation, action reversal, and speed control, and is a conventional technical solution in the industry. However, this traditional system has inherent defects that are difficult to overcome in practical applications: High energy consumption and severe heat generation: The throttling at the valve port generates a large amount of throttling loss, resulting in low system transmission efficiency and persistently high energy consumption during long-term operation; the heat generated by throttling causes the oil to heat up rapidly, further increasing energy consumption and equipment costs.

[0004] Bulky structure and large space occupation: Open loops require large main oil tanks and complex pipelines, which not only significantly occupy equipment installation space, but also increase the difficulty of pipeline layout and reduce system response speed.

[0005] Insufficient control and stability: The reversing impact of throttling speed regulation is large, which cannot meet the high requirements of small-tonnage presses for the control accuracy, dynamic response and operation stability of the moving beam.

[0006] The overall cost is relatively high: the large oil tank and supporting oil filter and cooling components increase the manufacturing cost of the hydraulic system; at the same time, the complex equipment foundation also increases the investment in civil engineering, and the later maintenance costs are also relatively high.

[0007] The aforementioned shortcomings mean that traditional open hydraulic systems cannot simultaneously meet the comprehensive requirements of small-tonnage high-speed forging presses in terms of energy saving, compactness, high precision, and low cost. The industry urgently needs a more efficient, compact, and energy-saving hydraulic system solution. Therefore, this invention proposes a closed hydraulic system and control method for high-speed forging presses. Summary of the Invention

[0008] The purpose of this invention is to provide a closed-loop hydraulic system and control method for a fast forging press to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A closed-loop hydraulic system for a fast forging press includes a main cylinder, a return cylinder, a movable beam, a hydraulic pump group, and an accumulator group. The main cylinder plunger and the movable beam are designed as a single unit to reduce the weight of the moving parts. The hydraulic pump group is a closed-loop variable pump group. The closed-loop hydraulic system also includes a proportional cartridge valve and a check valve. The closed-loop variable pump unit, master cylinder, return cylinder, and accumulator unit form a closed hydraulic circuit. A proportional cartridge valve is located in the master cylinder oil circuit and is used to control the depressurization of the master cylinder; The check valve connects the accumulator group to the oil inlet of the closed variable pump group and is used to replenish oil to the closed variable pump group during the pressing process. The closed-loop variable pump unit controls the flow rate and direction of hydraulic oil by adjusting the size and direction of the swashplate, driving the fast forging press to complete the pressing, depressurizing, and return actions. The entire system operation is free of throttling losses.

[0010] Preferably, the fast forging press is a top-pressure cylinder-driven fast forging press with a tonnage of less than 10MN.

[0011] Preferably, the closed variable pump unit includes at least three closed variable pumps, each of which can independently or synchronously adjust the swashplate angle.

[0012] Preferably, the proportional cartridge valve is installed on the top of the master cylinder, and when the pressure is released, the high-pressure oil in the master cylinder is released to the accumulator group through the proportional cartridge valve.

[0013] Preferably, the closed-loop variable pump unit is in a positive swashplate state, drawing oil from the return cylinder and accumulator group, the proportional cartridge valve is closed, and the pressing speed is infinitely adjustable by the swashplate swashplate angle of the closed-loop variable pump unit.

[0014] Preferably, during the return stroke, the closed variable pump group switches to a negative swing angle state and draws oil from the master cylinder; part of the closed variable pump delivers hydraulic oil to the accumulator group for storage, and the other part of the closed variable pump delivers hydraulic oil to the return cylinder to drive the movable beam to return.

[0015] Preferably, the swashplate angle of the closed-loop variable pump delivered to the accumulator group is adjusted synchronously, while the swashplate angle of the closed-loop variable pump delivered to the return cylinder is adjusted independently to control the return speed.

[0016] Preferably, the return cylinder has a double-sided cylinder structure, which works in conjunction with the main cylinder to drive the movable beam.

[0017] Preferably, the closed-loop hydraulic system does not have a traditional main oil tank, and the system oil volume is supplied by a closed loop and an accumulator group.

[0018] A closed-loop hydraulic control method for a high-speed forging press, employing the aforementioned closed-loop hydraulic system, includes the following steps: S1, Pressing: Control the closed variable pump group to be in the positive swing angle, draw oil from the return cylinder and accumulator group, close the proportional cartridge valve, and adjust the pressing speed steplessly by adjusting the swashplate swing angle. When the oil suction flow is insufficient, the accumulator group replenishes oil through the check valve. S2, Depressurization: Open the proportional cartridge valve to release the high-pressure oil in the main cylinder to the accumulator group until the pressure in the main cylinder drops to the preset safety pressure; S3, Return: Control the closed variable pump group to switch to negative swashplate angle, draw oil from the main cylinder, store part of the hydraulic oil in the accumulator group and send part to the return cylinder to drive the movable beam to return. The return speed is controlled by independently adjusting the swashplate angle of the corresponding pump.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention abandons valve port throttling control and adopts closed variable pump volumetric speed regulation, with no throttling loss throughout the process, resulting in a comprehensive energy saving of 40%-50%; the high-pressure depressurized oil is recovered to the accumulator, which greatly improves the energy utilization rate. The traditional large main oil tank is eliminated, and the system oil consumption is only 10% of that of the traditional open system. The pipeline is shortened and the footprint is small, which is suitable for the compact installation requirements of small tonnage presses.

[0020] (2) This invention achieves shock-free reversing by adjusting the rate of change of the swashplate angle, resulting in smooth operation of the moving beam and significantly improved control accuracy and dynamic response. The system valve group is simplified, the cooling system is smaller, and the equipment manufacturing cost, civil engineering cost, and subsequent maintenance cost are greatly reduced; the system generates less heat, and the hydraulic oil has a longer service life. Attached Figure Description

[0021] Figure 1 This is a hydraulic schematic diagram of the pressing process of the present invention; Figure 2 This is a hydraulic schematic diagram of the depressurization and return process of the present invention.

[0022] The labels in the diagram are as follows: 1. Return cylinder; 2. Moving beam; 3. Main cylinder; 4. Proportional cartridge valve; 5. Hydraulic pump assembly; 6. Check valve; 7. Accumulator assembly. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Example: Please see Figure 1-2A closed-loop hydraulic system for a fast forging press is disclosed. The fast forging press is a top-pressure cylinder-driven fast forging press with a tonnage of less than 10MN. It includes a main cylinder 3, a return cylinder 1, a movable beam 2, a hydraulic pump group 5, and an accumulator group 7. The main cylinder plunger and the movable beam 2 are designed as a single unit to reduce the weight of the moving parts. The hydraulic pump group 5 is a closed-loop variable pump group. The closed-loop hydraulic system also includes a proportional cartridge valve 4 and a check valve 6. The return cylinder 1 has a double-sided cylinder structure and works with the main cylinder 3 to drive the movable beam 2. The double-sided return cylinders 1 are symmetrically arranged, and the force is evenly distributed to ensure the smooth operation of the movable beam 2 and improve forging accuracy.

[0025] The closed-loop variable pump group, main cylinder 3, return cylinder 1, and accumulator group 7 form a closed hydraulic circuit. The proportional cartridge valve 4 is located in the oil circuit of the main cylinder 3 and is used to control the pressure relief of the main cylinder 3. The proportional cartridge valve 4 is installed on the top of the main cylinder 3 and is specifically used for high pressure relief, so as to realize the rapid and shock-free pressure relief of the main cylinder and avoid pressure shock damage to the equipment. During pressure relief, the high pressure oil in the main cylinder 3 is discharged to the accumulator group 7 through the proportional cartridge valve 4, and the pressure relief oil is directly recovered to the accumulator group 7, resulting in a high energy recovery and utilization rate.

[0026] One-way valve 6 connects accumulator group 7 to the oil inlet of closed variable pump group. It is used to replenish oil to closed variable pump group during the pressing process, prevent insufficient oil suction of pump and cavitation, ensure stable operation of pump group and improve system reliability.

[0027] The closed-loop variable displacement pump unit controls the flow rate and direction of hydraulic oil by adjusting the size and direction of the swashplate angle, driving the high-speed forging press to complete the pressing, depressurizing, and return strokes. The entire system operates without throttling losses. Using a swashplate variable displacement pump, the flow rate and direction are directly controlled by the swashplate angle, replacing the traditional proportional valve for throttling speed regulation. This eliminates throttling losses throughout the process, improving transmission efficiency by 40%-50%. It can be adjusted independently or synchronously, achieving precise speed control for pressing and return strokes, with smooth and shock-free reversing.

[0028] In this application, the closed-loop variable pump unit includes at least three closed-loop variable pumps, each of which can independently or synchronously adjust the swashplate angle. When the closed-loop variable pump unit is in a positive swashplate state, it draws oil from the return cylinder 1 and the accumulator group 7, the proportional cartridge valve 4 is closed, and the pressing speed is continuously adjustable by the swashplate angle of the closed-loop variable pump unit.

[0029] In this application, during the return stroke, the closed variable pump group switches to a negative swing angle state and draws oil from the main cylinder 3; part of the closed variable pump delivers hydraulic oil to the accumulator group 7 for storage, and the other part of the closed variable pump delivers hydraulic oil to the return cylinder 1 to drive the movable beam 2 to return.

[0030] In this application, the swashplate angle of the closed variable pump delivered to the accumulator group 7 is synchronously adjusted, and the swashplate angle of the closed variable pump delivered to the return cylinder 1 is independently adjusted to control the return speed; the accumulator group 7 has three functions: oil replenishment, oil storage, and energy recovery, which balances the system flow fluctuations, stabilizes the system pressure, and further reduces energy consumption.

[0031] In this application, the closed hydraulic system does not have a traditional main oil tank. The system oil volume is supplied by the closed circuit and the accumulator group 7. The traditional large main oil tank is eliminated, and the system oil consumption is only 10% of that of the traditional open system. The system has a compact structure, small footprint, shortened pipelines, and significantly improved system response speed.

[0032] The system has no throttling losses, generates little heat, and requires no additional cooling devices; the valve assembly is simplified, significantly reducing civil engineering and maintenance costs, and is suitable for the stringent operating conditions of small-tonnage high-speed forging presses.

[0033] A closed-loop hydraulic control method for a high-speed forging press, employing the aforementioned closed-loop hydraulic system, achieves throttling-free and impact-free operation of the press through three-step control: pressing, depressurization, and return stroke; including the following steps: S1, Pressing: Control the closed variable pump group to be in the positive swing angle, draw oil from the return cylinder 1 and accumulator group 7, close the proportional cartridge valve 4, and adjust the pressing speed steplessly by adjusting the swash plate swing angle. When the oil suction flow is insufficient, the accumulator group 7 replenishes oil through the check valve 6. S2, Depressurization: Open the proportional cartridge valve 4 to release the high-pressure oil in the main cylinder 3 to the accumulator group 7 until the pressure of the main cylinder 3 drops to the preset safety pressure. S3, Return: Control the closed variable pump group to switch to negative swashplate angle, draw oil from main cylinder 3, store part of the hydraulic oil in accumulator group 7, and send part of it to return cylinder 1 to drive movable beam 2 to return. The return speed is controlled by independently adjusting the swashplate angle of the corresponding pump.

[0034] This embodiment uses a 6.3MN top-pressure cylinder-driven fast forging press as the specific implementation object. The press has a tonnage of less than 10MN and is suitable for the application scenarios of the closed hydraulic system of this invention. The key structural parameters of the system are as follows: Main cylinder 3 diameter: 500mm, volume: 137.5L; Return cylinder 1: Double-sided cylinder structure, diameter 2×140mm, volume 21.5L; Press stroke: 700mm; Accumulator group 7: Total volume 1000L, working volume 137.5L, pre-charge pressure 11.7bar, minimum working pressure 13bar, maximum working pressure 18bar; Closed-loop variable pump unit: Three A4VSG250HS5 closed-loop variable pumps, with independent / synchronous adjustment of the swashplate angle; Proportional cartridge valve 4: 2WRCE proportional cartridge valve, installed on top of master cylinder 3.

[0035] In this embodiment, the closed variable pump group, main cylinder 3, return cylinder 1, and accumulator group 7 constitute a closed hydraulic circuit. The system does not have a traditional main oil tank. All oil is supplied by the closed circuit and accumulator group 7 in a circulating manner. The oil volume is only 10% of that of the traditional open system.

[0036] 1. Suppression process ( Figure 1 ) All three closed variable pumps are in the positive swing angle state, synchronously drawing oil from the rodless chamber of return cylinder 1 and accumulator group 7; proportional cartridge valve 4 remains energized and closed.

[0037] The pressing speed is achieved by continuously adjusting the swashplate angle of the closed variable pump unit. The larger the swashplate angle, the greater the flow rate and the faster the pressing speed.

[0038] When the oil discharge flow rate of the return cylinder 1 is less than the oil suction flow rate of the pump group, the hydraulic oil in the accumulator group 7 is automatically replenished into the oil suction port of the pump group through the one-way valve 6 to avoid insufficient oil suction of the pump and cavitation, and to ensure continuous and stable pressing process.

[0039] Meanwhile, by controlling the rate of change of the swashplate angle, a shock-free transition between pressing start and stop is achieved, and the running fluctuation of the movable beam 2 is ≤±1mm, preventing the movable beam 2 from shaking.

[0040] 2. Depressurization process ( Figure 2 ) After the pressing action is completed, the system enters the depressurization stage: the proportional cartridge valve 4 is opened in a controlled manner, and the 31.5MPa high-pressure oil in the main cylinder 3 is quickly and without impact discharged to the accumulator group 7 through the proportional cartridge valve 4, realizing high-pressure energy recovery.

[0041] The pressure relief gradient linear control reduces pressure to below 50 Pa / s within 300 ms. When the pressure in the main cylinder 3 drops below 50 bar, the pressure relief process is complete, eliminating pressure shock for subsequent return stroke and protecting system pipelines and valves. The system shock pressure fluctuation is ≤ ±10 bar.

[0042] 3. The return journey ( Figure 2 ) The three closed-loop variable pumps synchronously switch to the negative swing angle state, and the functions of the pump group's suction and discharge ports are interchanged, with all pumps drawing oil from the rodless chamber of the main cylinder 3: 1# and 2# closed variable pumps: the swashplate angle is synchronously adjusted, and all the discharged oil is sent to the accumulator group 7 for storage, which is used for the next pressing oil replenishment; #3 Closed Variable Pump: The swashplate angle is independently adjustable. The discharged oil is directly sent to the rod chamber of the return cylinder 1, driving the movable beam 2 to return quickly. The return speed is controlled independently by the swashplate angle of the #3 pump, and the return speed adjustment range is 0-300mm / s.

[0043] If the oil flow rate of the main cylinder 3 exceeds the total oil suction capacity of the three pumps, the excess oil flows back to the accumulator group 7 through the opened proportional cartridge valve 4, maintaining the system pressure stable without fluctuation.

[0044] During the return stroke and reversal, the starting and stopping of the moving beam 2 is also controlled by adjusting the rate of change of the swashplate angle, thereby improving the forging control accuracy.

[0045] 4. System abnormal operating condition protection When the system pressure exceeds the maximum working pressure of 18 bar, the accumulator group 7 automatically overflows and releases pressure; when the pump group's oil suction pressure is lower than the minimum working pressure of 13 bar, the one-way valve 6 quickly opens to replenish oil, ensuring the safe operation of the system throughout the process.

[0046] Under continuous forging conditions, the system oil temperature is stable at 40±5℃, which is more than 15℃ lower than that of traditional systems; the oil contamination level is maintained within NAS 6 level, and the filter maintenance cycle is extended by 3 times.

[0047] This embodiment, compared to the traditional open hydraulic system with a fixed displacement pump and proportional valve, has been verified through actual testing: With no throttling losses throughout the process, the overall energy saving is 45% (average), and the high-pressure depressurization energy recovery efficiency reaches 85%. The main oil tank is eliminated, reducing oil consumption by 90% and the system footprint by 60%, making it suitable for installation in confined workshops. The positioning control accuracy of the movable beam is improved by 30%, with a repeatability accuracy of ≤±1mm. The system generates less heat, simplifies the valve group, reduces equipment manufacturing costs by 25%, and reduces operating and maintenance costs by more than 30%. The system response time is shortened to 80ms, which is 40% better than traditional systems, and the dynamic response meets the requirements of precision small parts forging.

[0048] The parameters of this embodiment can be linearly extended to small-tonnage top-pressure cylinder-driven fast forging presses with capacities of 2.5MN, 5MN, 8MN, etc. (<10MN). Only the volume of the main cylinder / return cylinder, the working volume of the accumulator, and the displacement of the pump group need to be adjusted according to the tonnage ratio. The core closed loop, control logic, and energy-saving effect of the system remain consistent, and it has the versatility for mass promotion.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A closed-loop hydraulic system for a fast forging press, comprising a main cylinder (3), a return cylinder (1), a movable beam (2), a hydraulic pump assembly (5), and an accumulator assembly (7), characterized in that, The hydraulic pump set (5) is a closed variable pump set, and the closed hydraulic system also includes a proportional cartridge valve (4) and a check valve (6). The closed-loop variable pump group, main cylinder (3), return cylinder (1), and accumulator group (7) form a closed hydraulic circuit. The proportional cartridge valve (4) is located in the oil circuit of the main cylinder (3) and is used to control the depressurization of the main cylinder (3); The one-way valve (6) connects the accumulator group (7) to the oil inlet of the closed variable pump group and is used to replenish oil to the closed variable pump group during the pressing process. The closed-loop variable pump unit controls the flow rate and direction of hydraulic oil by adjusting the size and direction of the swashplate, driving the fast forging press to complete the pressing, depressurizing, and return actions. The entire system operation is free of throttling losses.

2. The closed-loop hydraulic system for a high-speed forging press according to claim 1, characterized in that, The fast forging press is a top-pressure cylinder-driven fast forging press with a tonnage of less than 10MN.

3. The closed-loop hydraulic system for a high-speed forging press according to claim 1, characterized in that, The closed-loop variable pump unit comprises at least three closed-loop variable pumps, each of which can independently or synchronously adjust the swashplate angle.

4. The closed-loop hydraulic system for a high-speed forging press according to claim 3, characterized in that, The proportional cartridge valve (4) is installed on the top of the main cylinder (3). When the pressure is released, the high pressure oil in the main cylinder (3) is released to the accumulator group (7) through the proportional cartridge valve (4).

5. The closed-loop hydraulic system for a high-speed forging press according to claim 3, characterized in that, The closed variable pump unit is in a positive swing angle state, drawing oil from the return cylinder (1) and the accumulator group (7), the proportional cartridge valve (4) is closed, and the pressing speed is infinitely adjustable by the swashplate swing angle of the closed variable pump unit.

6. The closed-loop hydraulic system for a high-speed forging press according to claim 3, characterized in that, During the return stroke, the closed variable pump group switches to a negative swing angle state and draws oil from the main cylinder (3); part of the closed variable pump delivers hydraulic oil to the accumulator group (7) for storage, and another part of the closed variable pump delivers hydraulic oil to the return cylinder (1) to drive the movable beam (2) to return.

7. The closed-loop hydraulic system for a high-speed forging press according to claim 6, characterized in that, The swashplate angle of the closed variable pump delivered to the accumulator group (7) is synchronously adjusted, and the swashplate angle of the closed variable pump delivered to the return cylinder (1) is independently adjusted to control the return speed.

8. The closed-loop hydraulic system for a high-speed forging press according to claim 1, characterized in that, The return cylinder (1) is a double-sided cylinder structure, which works in conjunction with the main cylinder (3) to drive the movable beam (2) to move.

9. The closed-loop hydraulic system for a high-speed forging press according to claim 1, characterized in that, The closed hydraulic system does not have a traditional main oil tank. The system oil volume is supplied by the closed loop and the accumulator group (7).

10. A closed-loop hydraulic control method for a high-speed forging press, characterized in that, The closed hydraulic system according to any one of claims 1-9 includes the following steps: S1, Pressing: Control the closed variable pump group to be in the positive swing angle, draw oil from the return cylinder (1) and accumulator group (7), close the proportional cartridge valve (4), and adjust the pressing speed steplessly by adjusting the swash plate angle. When the oil flow is insufficient, the accumulator group (7) replenishes oil through the check valve (6). S2, Depressurize: Open the proportional cartridge valve (4) to release the high-pressure oil in the main cylinder (3) to the accumulator group (7) until the pressure of the main cylinder (3) drops to the preset safety pressure; S3, Return: Control the closed variable pump group to switch to negative swing angle, draw oil from the main cylinder (3), store part of the hydraulic oil into the accumulator group (7), and send part of it into the return cylinder (1) to drive the movable beam (2) to return. Control the return speed by independently adjusting the swashplate swing angle of the corresponding pump.

Images