An AGC cylinder back pressure control system and its usage method

Abstract

This invention belongs to the field of metal sheet and strip rolling technology, and specifically relates to an AGC (Automatic Gain Control) cylinder back pressure control system. The system includes a high-pressure filter, a primary three-way pressure reducing valve, a first pilot-operated relief valve, a secondary three-way pressure reducing valve, a first electromagnetic directional valve, a second electromagnetic directional valve, and a second pilot-operated relief valve. The outlet of the high-pressure filter is connected to the inlet of the primary three-way pressure reducing valve, and the outlet of the primary three-way pressure reducing valve is connected to the inlet of the second electromagnetic directional valve. This invention enables multi-stage pressure control of the AGC cylinder back pressure, achieving high reliability and stability while reducing the complexity of the back pressure control system, lowering equipment investment costs, saving maintenance time, and meeting the back pressure control accuracy requirements during AGC cylinder rolling.

Description

Technical Field

[0001] This invention belongs to the field of metal sheet and strip rolling technology, and in particular relates to an AGC hydraulic cylinder back pressure control system and its usage method. Background Technology

[0002] In the field of metal sheet and strip rolling, rolling mill equipment mainly relies on AGC cylinders to output rolling force and uses a high-precision control system to effectively control the thickness and shape of the strip. AGC cylinders come in two forms: push-up and press-down. The back pressure control of the piston rod chamber has a significant impact on the performance of the entire control system. Currently, commonly used back pressure control methods have certain drawbacks, as follows: Using a dedicated low-pressure pump or a circulating pump from a power source to directly supply pressure to the piston rod chamber of the AGC cylinder has the drawback that it can only provide a relatively low level of pressure. When strip breakage occurs in the rolling mill, it cannot increase the back pressure control pressure, which can easily lead to "steel piling up" or "roller jamming" phenomena within the rolling mill stand. Using a servo valve or proportional valve in conjunction with a pressure sensor in the piston rod chamber of the AGC cylinder for closed-loop back pressure control allows for flexible pressure setting and control. However, the servo valve or proportional valve has very high requirements for oil cleanliness and is prone to clogging and jamming, causing the back pressure control system to fail. In addition, the control parameters of the closed-loop control system vary under different operating conditions of the AGC cylinder, making the control system more complex and difficult to analyze and diagnose. Furthermore, the investment and maintenance costs of this method are relatively high.

[0003] To address these issues, an AGC cylinder back pressure control system and its usage method are proposed. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing an AGC cylinder back pressure control system and its usage method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an AGC cylinder back pressure control system, comprising a high-pressure filter, a primary three-way pressure reducing valve, a first pilot relief valve, a secondary three-way pressure reducing valve, a first solenoid directional valve, a second solenoid directional valve, and a second pilot relief valve. The outlet of the high-pressure filter is connected to the inlet of the primary three-way pressure reducing valve, the outlet of the primary three-way pressure reducing valve is connected to the inlet of the second solenoid directional valve, and the outlet of the primary three-way pressure reducing valve is connected to the inlet of the first pilot relief valve, thus constituting the supply and safety protection of the primary pressure back pressure module. The system comprises a primary three-way pressure reducing valve, the outlet of which is connected to the inlet of a secondary three-way pressure reducing valve, serving as the pressure source for the secondary pressure back pressure module. The outlet of the secondary three-way pressure reducing valve is connected to the inlet of the second pilot relief valve, forming a supply and safety protection assembly for the secondary pressure back pressure module. Both the primary and secondary pressure back pressure modules have return ports at their oil outlets. A check valve is installed in the return oil pipeline of the return port to isolate the return oil from the AGC cylinder piston rod chamber, preventing air from being drawn into the piston rod chamber. The return port and the check valve together form the return oil back pressure module.

[0006] Preferably, the outlet of the secondary three-way pressure reducing valve is connected to the inlet of the first solenoid directional valve, which is used to provide a secondary pressure back pressure module to the AGC cylinder according to the controller command. The outlet of the secondary three-way pressure reducing valve is also connected to an accumulator through a high-pressure valve. The accumulator is used to eliminate pressure pulsation to stabilize the secondary pressure back pressure module.

[0007] Preferably, the pipeline between the accumulator and the return oil port is equipped with a pressure relief valve to release the pressure inside the accumulator during maintenance.

[0008] Preferably, the oil return port is connected to the oil return pipeline, and the oil supply port is connected to the oil supply pipeline.

[0009] Preferably, the second electromagnetic reversing valve has a back pressure outlet at its liquid outlet, and a pressure measuring point is provided at the back pressure outlet to detect the actual pressure in the piston rod chamber of the AGC cylinder, which facilitates debugging and maintenance.

[0010] A method for using the primary pressure back pressure module in an AGC cylinder back pressure control system includes the following steps: S1. The oil inside the oil supply pipeline is transported to the high-pressure filter through the oil supply port for filtration; S2. The filtered oil enters the first three-way pressure reducing valve and the first pilot relief valve to form a first-level pressure oil.

[0011] S3. The system controls the first and second solenoid directional valves to be de-energized simultaneously. The oil under first-level pressure is directly delivered to the piston rod chamber through the inlet of the second solenoid directional valve and the working port on one side, providing first-level pressure for roller changing and belt breakage conditions.

[0012] A method for using a secondary pressure back pressure module in an AGC cylinder back pressure control system, characterized by comprising the following steps: S1. The oil inside the oil supply pipeline is transported to the high-pressure filter through the oil supply port for filtration; S2. The filtered oil enters the first three-way pressure reducing valve and the first pilot relief valve to form a first-stage pressure oil. S3. A portion of the first-stage pressure oil is delivered to the second three-way pressure reducing valve. The second three-way pressure reducing valve and the second pilot relief valve together form the second-stage pressure oil. S4. The system controls the first and second solenoid directional valves to be energized simultaneously. The secondary pressure oil will be delivered to the piston rod chamber through the first solenoid directional valve, providing the secondary pressure back pressure module for rolling, pressing, and roll gap opening operations.

[0013] A method for using the return oil back pressure module in an AGC cylinder back pressure control system, characterized by comprising the following steps: S1. The system controls the first solenoid directional valve to be energized, while the second solenoid directional valve is de-energized. S2. The oil in the piston rod chamber enters the first solenoid directional valve from the back pressure outlet and flows back to the return port through the check valve, providing return back pressure for debugging, maintenance and fault diagnosis.

[0014] Compared with existing technologies, the advantages of an AGC cylinder back pressure control system and its usage method are: 1. This invention can realize multi-level back pressure control, adapt to various working conditions, and can provide a secondary pressure back pressure module, a primary pressure back pressure module and oil return back pressure according to different working conditions such as rolling, pressing, opening roll gap, roll changing, strip breakage, debugging, maintenance and fault diagnosis, to meet the back pressure requirements in different scenarios.

[0015] 2. This invention can ensure pressure stability and control accuracy. In conditions such as rolling that require a secondary pressure back pressure module, the energy storage compensation effect of the accumulator eliminates pressure pulsation, ensuring the high stability of the secondary pressure back pressure module and meeting the back pressure control accuracy requirements during rolling.

[0016] 3. This invention simplifies the system structure, reduces costs and maintenance difficulty, eliminates the need for complex closed-loop proportional servo valve control, reduces system complexity, reduces the use of expensive and easily damaged components such as servo valves or proportional valves, and lowers equipment investment costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an AGC cylinder back pressure control system and its usage method provided by the present invention.

[0018] In the diagram: 1. High-pressure filter; 2. First-stage three-way pressure reducing valve; 3. First pilot relief valve; 4. Second-stage three-way pressure reducing valve; 5. First solenoid directional valve; 6. Second solenoid directional valve; 7. Second pilot relief valve; 8. Pressure relief valve; 9. High-pressure valve; 10. Accumulator; 11. Check valve; 12. Pressure measuring point; 13. Oil supply port; 14. Oil return port; 15. Back pressure outlet; 16. First-stage pressure back pressure module; 17. Second-stage pressure back pressure module; 18. Oil return back pressure module. Detailed Implementation

[0019] 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.

[0020] like Figure 1 As shown, an AGC cylinder back pressure control system includes a high-pressure filter 1, a primary three-way pressure reducing valve 2, a first pilot relief valve 3, a secondary three-way pressure reducing valve 4, a first solenoid directional valve 5, a second solenoid directional valve 6, and a second pilot relief valve 7. The outlet of the high-pressure filter 1 is connected to the inlet of the primary three-way pressure reducing valve 2. The outlet of the primary three-way pressure reducing valve 2 is connected to the inlet of the second solenoid directional valve 6. The outlet of the primary three-way pressure reducing valve 2 is connected to the inlet of the first pilot relief valve 3, forming a supply and safety protection combination for the primary pressure back pressure module 16. The primary three-way pressure reducing valve 2... The outlet is connected to the inlet of the secondary three-way pressure reducing valve 4, serving as the pressure source for the secondary pressure back pressure module 17. The outlet of the secondary three-way pressure reducing valve 4 and the inlet of the second pilot relief valve 7 are connected, forming a supply and safety protection combination for the secondary pressure back pressure module 17. The oil outlets of the primary pressure back pressure module 16 and the secondary pressure back pressure module 17 are provided with oil return ports 14. A one-way valve 11 is provided in the oil return pipeline of the oil return port 14 to isolate the oil return from the piston rod chamber of the AGC cylinder and prevent the piston rod chamber from drawing in air. The oil return port 14 and the one-way valve 11 form the oil return back pressure module 18.

[0021] The outlet of the secondary three-way pressure reducing valve 4 is connected to the inlet of the first solenoid directional valve 5, and is used to provide the secondary pressure back pressure module 17 to the AGC cylinder according to the controller command. The outlet of the secondary three-way pressure reducing valve 4 is also connected to the accumulator 10 through the high pressure valve 9. The accumulator 10 is used to eliminate pressure pulsation to stabilize the secondary pressure back pressure module 17.

[0022] The pipeline between the accumulator 10 and the return port 14 is equipped with a pressure relief valve 8, which is used to release the pressure inside the accumulator 10 during maintenance. The return port 14 is connected to the return pipeline, and the supply port 13 is connected to the supply pipeline.

[0023] The second electromagnetic reversing valve 6 has a back pressure outlet 15 at its outlet, and a pressure measuring point 12 is set at the back pressure outlet 15 to detect the actual pressure in the piston rod chamber of the AGC cylinder, which is convenient for debugging and maintenance.

[0024] The operating principle of this invention is explained as follows: The operating principle of this AGC cylinder back pressure control system is based on multi-stage pressure regulation and electromagnetic reversing switching. Back pressure control under different working conditions is achieved through the coordinated action of various components. Specifically, the oil inside the oil supply pipeline is transported through the oil supply port 13 to the high-pressure filter 1 for filtration to prevent impurities from clogging the components. The filtered oil then enters the first three-way pressure reducing valve 2, which adjusts the input pressure to the first-stage back pressure. The first pilot relief valve 3 acts as a safety protection to prevent overpressure of the first-stage back pressure. The first-stage back pressure oil is divided into two paths: one path enters the second three-way pressure reducing valve 4, and the second three-way pressure reducing valve 4 and the second pilot relief valve 7 form a second-stage back pressure system. The pressure back pressure reduces the primary pressure back pressure to the secondary pressure back pressure (since the secondary pressure back pressure originates from the primary pressure back pressure, the secondary pressure back pressure must be lower than the primary pressure back pressure to ensure safety). The second pilot relief valve 7 provides safety protection for the secondary pressure back pressure, and another path is connected to the inlet of the second solenoid directional valve 6 to wait for switching to the primary pressure back pressure. The secondary pressure back pressure oil is connected to the inlet of the first solenoid directional valve 5 on one hand, and to the accumulator 10 through the high-pressure valve 9 on the other hand. The accumulator 10 eliminates pressure pulsation through energy storage compensation to ensure the stability of the secondary pressure back pressure. The pressure relief valve 8 connects the accumulator 10 to the return port 14 and is used to release the pressure in the accumulator 10 during maintenance. The system achieves three back pressure modes through the combination of the energized / de-energized states of the first electromagnetic directional valve 5 and the second electromagnetic directional valve 6. When both are energized simultaneously, it is suitable for rolling, pressing, and roll gap opening operations in rolling mill equipment. The secondary pressure back pressure oil flows from the outlet of the second three-way pressure reducing valve 4 to the inlet of the first electromagnetic directional valve 5. Because the first electromagnetic directional valve 5 is energized, the oil enters the back pressure outlet 15 and flows to the piston rod chamber of the AGC cylinder. At the same time, the accumulator 10 assists in stabilizing the pressure, providing secondary pressure back pressure for rolling, pressing, and roll gap opening operations. When the first electromagnetic directional valve 5 and the second electromagnetic directional valve 6 are de-energized simultaneously, it is suitable for roll changing and strip breakage operations in rolling mill equipment. The primary pressure back pressure oil flows from the outlet of the first three-way pressure reducing valve 2 to the inlet of the second electromagnetic directional valve 6. Because the second electromagnetic directional valve 6 is de-energized, the oil flows from the inlet of the second electromagnetic directional valve 6 and one side of the working... The oil from the piston rod chamber is directed to the piston rod cavity, providing primary back pressure for roll changing and strip breakage conditions. When the first solenoid directional valve 5 is energized while the second solenoid directional valve 6 is de-energized, it is suitable for mill equipment debugging, maintenance, and fault diagnosis. The oil in the piston rod cavity enters the first solenoid directional valve 5 from the back pressure outlet 15. Because the first solenoid directional valve 5 is energized, the oil will pass through the check valve 11 to the return oil port 14. The check valve 11 prevents air intake and provides return oil back pressure for debugging, maintenance, and fault diagnosis conditions. In addition, the pressure measuring point 12 is set at the back pressure outlet A to detect the actual pressure and ensure that the system operation status can be monitored. Each pilot relief valve ensures that the pressure does not exceed the upper limit. The high-pressure valve 9 of the accumulator controls its connection and disconnection with the oil circuit. The pressure relief valve 8 is used for pressure relief during maintenance. The whole system achieves accurate and stable control of back pressure under different operating conditions through component coordination, taking into account both safety and reliability.

[0025] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An AGC cylinder back pressure control system, comprising a high-pressure filter (1), a primary three-way pressure reducing valve (2), a first pilot relief valve (3), a secondary three-way pressure reducing valve (4), a first solenoid directional valve (5), a second solenoid directional valve (6), and a second pilot relief valve (7), characterized in that, The high-pressure filter (1) has an oil supply port (13) on its surface, which is connected to the oil supply pipeline. The outlet of the high-pressure filter (1) is connected to the inlet of the first-stage three-way pressure reducing valve (2). The outlet of the first-stage three-way pressure reducing valve (2) is connected to the inlet of the second electromagnetic reversing valve (6). The outlet of the first-stage three-way pressure reducing valve (2) is connected to the inlet of the first pilot relief valve (3), forming a supply and safety protection combination for the first-stage pressure back pressure module (16). The outlet of the first-stage three-way pressure reducing valve (2) is connected to the inlet of the second-stage three-way pressure reducing valve (4), serving as the second-stage pressure. The pressure source of the back pressure module (17) is connected to the outlet of the secondary three-way pressure reducing valve (4) and the inlet of the second pilot relief valve (7), forming a supply and safety protection combination for the secondary pressure back pressure module (17). The oil outlets of the primary pressure back pressure module (16) and the secondary pressure back pressure module (17) are provided with oil return ports (14). The oil return pipeline of the oil return port (14) is provided with a check valve (11) to isolate the oil return from the piston rod chamber of the AGC cylinder and prevent the piston rod chamber from sucking in air. The oil return port (14) and the check valve (11) form the oil return back pressure module (18).

2. The AGC cylinder back pressure control system according to claim 1, characterized in that, The outlet of the secondary three-way pressure reducing valve (4) is connected to the inlet of the first electromagnetic reversing valve (5) to provide the secondary pressure back pressure module (17) to the AGC cylinder according to the controller command. The outlet of the secondary three-way pressure reducing valve (4) is also connected to an accumulator (10) through a high-pressure valve (9). The accumulator (10) is used to eliminate pressure pulsation to stabilize the secondary pressure back pressure module (17).

3. The AGC cylinder back pressure control system according to claim 2, characterized in that, The pipeline between the accumulator (10) and the return port (14) is equipped with a pressure relief valve (8) to release the pressure inside the accumulator (10) during maintenance.

4. The AGC cylinder back pressure control system according to claim 3, characterized in that, The return port (14) is connected to the return pipeline.

5. The AGC cylinder back pressure control system according to claim 1, characterized in that, The second electromagnetic reversing valve (6) has a back pressure outlet (15) at its outlet. A pressure measuring point (12) is provided at the back pressure outlet (15) to detect the actual pressure in the piston rod chamber of the AGC cylinder, which is convenient for debugging and maintenance.

6. The method of using the primary pressure back pressure module (16) in the AGC cylinder back pressure control system according to any one of claims 1-5, characterized in that, Includes the following steps: S1. The oil inside the oil supply pipeline is transported to the high-pressure filter (1) through the oil supply port (13) for filtration; S2. The filtered oil enters the first three-way pressure reducing valve and the first pilot relief valve (3) to form a first-level pressure oil. S3. The system controls the first solenoid directional valve (5) and the second solenoid directional valve (6) to be de-energized at the same time. The oil under first-level pressure is directly delivered to the piston rod chamber through the inlet of the second solenoid directional valve (6) and the working port on one side, providing first-level pressure for roller changing and belt breakage conditions.

7. The method of using the secondary pressure back pressure module (17) in the AGC cylinder back pressure control system according to any one of claims 1-5, characterized in that, Includes the following steps: S1. The oil inside the oil supply pipeline is transported to the high-pressure filter (1) through the oil supply port (13) for filtration; S2. The filtered oil enters the first three-way pressure reducing valve and the first pilot relief valve (3) to form a first-level pressure oil. S3. A portion of the first-level pressure oil is delivered to the second three-way pressure reducing valve. The second three-way pressure reducing valve and the second pilot relief valve (7) together form the second-level pressure oil. S4. The system controls the first solenoid directional valve (5) and the second solenoid directional valve (6) to be energized at the same time. The secondary pressure oil will be delivered to the piston rod chamber through the first solenoid directional valve (5) to provide the secondary pressure back pressure module (17) for rolling, pressing and opening roll gap conditions.

8. The method of using the return oil back pressure module (18) in the AGC cylinder back pressure control system according to any one of claims 1-5, characterized in that, Includes the following steps: S1. The system controls the first solenoid directional valve (5) to be energized, while the second solenoid directional valve (6) is not energized. S2. The oil in the piston rod chamber enters the first solenoid directional valve (5) from the back pressure outlet (15) and flows back to the return oil port (14) through the check valve (11) to provide return oil back pressure for debugging, maintenance and fault diagnosis.

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