Radial forging machine hydraulic frequency conversion system

Abstract

The application discloses a kind of radial forging machine hydraulic frequency conversion systems, including the eccentric shaft being installed on main frame, eccentric shaft is connected with forging cylinder, forging cylinder, frequency conversion piston cylinder and main plug-in valve are communicated with integrated valve block internal oil channel, main plug-in valve and pilot servo cylinder are connected, the piston rod of pilot servo cylinder is electrically connected with displacement sensor.Main plug-in valve and pilot servo cylinder form quick discharge oil channel, so that forging cylinder does not rotate with eccentric shaft and extend, reduce the forging frequency of forge, adapt to the large cross-section billet large deformation forming requirement;In low-frequency forging mode, the time interval of hammer head is increased, and longer adjustment time is provided for the axial and rotary feed of the forged piece, the frequency is reduced by half, the forging interval time is also multiplied, under the same axial feed speed and rotary speed, the axial feed amount and rotation amount are also multiplied.

Description

Technical Field

[0001] This invention relates to the field of radial forging machine technology, specifically a hydraulic frequency conversion system for a radial forging machine. Background Technology

[0002] Radial forging machines, as advanced dieless forging near-net-shape forming equipment, operate on the principle of using a motor to drive an eccentric shaft to rotate, which in turn drives an adjusting cylinder to achieve the reciprocating striking action of the forging hammer, causing the forging to undergo plastic deformation under multi-directional compressive stress. Existing radial forging machines generally employ a high-frequency forging mode. While this mode can achieve high-precision forging, it has the following inherent drawbacks: 1. The forging frequency is too high, and the deformation of the forging is small in a single operation. Multiple blows are required to achieve the target size, which limits the improvement of the axial feed and rotary feed of the forging, making it difficult to meet the requirements of large cross-section and large deformation forming process. 2. Existing radial forging machines lack precise control logic based on the position of the eccentric shaft, making it impossible to predict the timing of the impact based on the rotation phase of the eccentric shaft. The rapid oil discharge action is not synchronized with the movement of the eccentric shaft, making it impossible to achieve "forging without extension". In addition, the conventional oil discharge structure has a slow response and large pressure impact, which cannot be adapted to the high load conditions of the radial forging machine. 3. For billets with large diameter and high hardness, such as stainless steel and high-temperature alloy billets, which have internal porosity and shrinkage defects, high-frequency small deformation is difficult to achieve sufficient core deformation, which can easily lead to quality problems such as incomplete forging and uneven structure. It is necessary to optimize the forming effect by reducing the forging frequency and increasing the amount of deformation per pass.

[0003] In existing technologies, research on frequency regulation for radial forging mills mainly focuses on motor speed control or eccentricity adjustment. Due to the strong impact, large load, and need for instantaneous liquid drainage and replenishment during the forging process of radial forging mills, conventional rapid oil drainage structures cannot be directly adapted, resulting in problems such as delayed oil drainage response, large pressure shock, and poor system stability. Summary of the Invention

[0004] The purpose of this invention is to provide a hydraulic frequency conversion system for a radial forging machine, which combines eccentric shaft position detection and a mechanism and control strategy to prevent the forging cylinder from rotating and extending with the eccentric shaft through rapid oil discharge. It relies on the return force of the plunger return cylinder to ensure the reliability of the operation, breaks through the constraints of the traditional reciprocating striking mode, achieves precise and controllable reduction of forging frequency, and simultaneously increases the feed rate, thus solving the problem of forming large cross-section billets.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A radial forging machine hydraulic frequency conversion system includes an eccentric shaft mounted on the main frame. The eccentric part of the eccentric shaft passes through the middle hole of the slider and is connected to the main cylinder seat of the forging cylinder. The lower end plane of the slider contacts the main cylinder seat plane of the forging cylinder. The oil port of the forging cylinder is connected to one oil port of the internal oil passage of the integrated valve block. The other oil port of the internal oil passage of the integrated valve block is connected to the oil port of the frequency conversion piston cylinder. The frequency conversion piston cylinder is fastened to the outside of the integrated valve block by bolts. The main cartridge valve is installed on the internal oil passage of the integrated valve block. The hammer rod of the forging cylinder is connected to the forging hammer head, and the end of the hammer rod is connected to the top of the piston rod of the two return cylinders fixed on the main frame. The main cylinder hydraulic oil cavity formed between the hammer rod and the inner wall of the main cylinder seat of the forging cylinder is connected to the main hydraulic oil circuit. The main hydraulic oil circuit is equipped with a reversing servo valve, a P oil source pump, a P relief valve, and a check valve. The P port of the reversing servo valve is connected to the P port oil source. The main valve core of the main cartridge valve is connected to the pilot servo cylinder. The cylinder seat of the pilot servo cylinder is closed on the outer wall of the integrated valve block. The piston rod of the pilot servo cylinder is electrically connected to the displacement sensor. The pilot servo cylinder is connected to the P port oil source through a fast oil discharge circuit. A fast oil discharge servo valve and a fast oil discharge safety valve are also installed on the fast oil discharge circuit. The variable frequency piston cylinder is connected to the variable frequency accumulator. The variable frequency accumulator, the X port of the reversing servo valve, and the X port of the fast oil discharge servo valve are all connected to the X port oil source. The return oil circuit of the return cylinder is equipped with a return servo valve and a return safety valve. The P port of the return servo valve is connected to the P port oil source.

[0006] Preferably, the main cartridge valve includes a main valve core, a main valve sleeve, and a main valve seat, with one end of the main valve core connected to the pilot piston rod.

[0007] Preferably, a fast discharge accumulator and a fast discharge check valve are installed between the fast discharge servo valve and the P-port oil source in the fast discharge circuit.

[0008] Preferably, a quick-release safety valve is installed on the hydraulic oil pipeline between the pilot piston rod oil chamber and the oil tank.

[0009] Preferably, a return accumulator and a return check valve are installed on the oil source connection pipeline between the P port and P1 port of the return servo valve.

[0010] Preferably, the variable frequency piston cylinder includes a cylinder body and an end cap. A piston is assembled in the inner cavity of the cylinder body, and a guide rod is installed at the center of the rear end of the piston. The rear end of the guide rod is assembled in a guide sleeve that penetrates the end cap. A sliding sleeve is installed on the outer wall of the piston. An air filter is installed at the top of the rod chamber of the variable frequency piston cylinder.

[0011] Preferably, the input end of the eccentric shaft is equipped with a rotary encoder that can acquire the rotation angle, phase and speed signals of the eccentric shaft in real time, and the rotary encoder is connected to a remote control center.

[0012] Preferably, a wear-resistant sleeve is fitted between the eccentric shaft and the intermediate hole of the slider; a wear-resistant plate is installed between the contact surfaces of the slider and the forging cylinder.

[0013] Preferably, a high-pressure sealing ring is provided at the connection between the variable frequency piston cylinder and the internal oil passage of the integrated valve block.

[0014] Preferably, several pressure sensors are installed on both the main hydraulic oil circuit and the return oil circuit of the forging cylinder, and the pressure sensors are connected to a remote control center.

[0015] This invention, based on the traditional eccentric shaft-cylinder transmission system of a radial forging mill, adds a rapid oil discharge circuit consisting of a main cartridge valve, a pilot servo cylinder, and a variable frequency piston cylinder. This prevents the forging cylinder from extending with the rotation of the eccentric shaft, and ensures the reliability of the operation by relying on the return force of the return cylinder. It breaks through the constraints of the traditional reciprocating striking mode, achieves precise and controllable reduction of forging frequency, and simultaneously increases the feed rate, meeting the requirements of large cross-section and large deformation forming processes, and solving the problem of forming large cross-section billets.

[0016] In this invention, the eccentric shaft is driven by a motor, and the eccentric shaft is rotated by gears. The eccentric shaft is connected to the cylinder body of the forging cylinder by a wear-resistant sliding plate, which is used to convert the rotational motion into an axial driving force on the cylinder. In this invention, the forging cylinder is a plunger cylinder, and its plunger rod is connected to the forging hammer head as a hammer rod. The space between the main cylinder seat and the hammer rod is a forging regulating hydraulic oil cavity. In this invention, the return cylinder is a plunger cylinder, which is linked to the forging cylinder and is independently arranged at the end of the hammer rod. It provides a stable return force through the return hydraulic circuit to ensure that the plunger rod quickly resets during the forging cycle and to ensure that the forging cylinder and the eccentric shaft sliding block maintain good contact. The return hydraulic circuit is equipped with a return servo valve and a return safety valve, which can adjust the magnitude of the return force to adapt to different working conditions. The main hydraulic oil circuit of the present invention includes a hydraulic pump, a relief valve and a check valve. The hydraulic pump provides working oil to the forging cylinder, the return cylinder and the pilot servo cylinder through the reversing servo valve. The relief valve is used to adjust the rated pressure of the system and the check valve prevents oil backflow. This invention features a rapid oil discharge circuit, comprising a main cartridge valve, a pilot servo cylinder and displacement sensor, a rapid discharge servo valve, a variable frequency piston cylinder, and an accumulator. The main cartridge valve is connected in series between the hydraulic oil chamber of the forging cylinder and the rodless chamber of the variable frequency piston cylinder to achieve rapid oil discharge and replenishment. The variable frequency accumulator is used to absorb pressure shocks during the oil discharge process and simultaneously replenish and stabilize the system's pressure. This invention incorporates an angular displacement sensor installed at the input end of the eccentric shaft to collect real-time signals of the eccentric shaft's rotation angle, phase, and speed, providing accurate feedback on the eccentric shaft's position and offering a basis for predicting the timing of oil discharge. This invention sets up multiple pressure detection modules, which are respectively installed in the rodless chamber, rod chamber, main hydraulic circuit and piston return cylinder oil circuit of the forging cylinder to collect oil pressure signals in real time and monitor the cylinder status and return force stability. In this invention, the remote control center uses a PLC and a motion controller with a built-in position signal processing algorithm. It is electrically connected to a rotary encoder, a pressure sensor, a displacement sensor, and a servo valve control element to achieve real-time coordinated control of signal acquisition, logic judgment, and command output.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Breakthrough in variable frequency forging: This invention forms a rapid oil discharge channel by using a main cartridge valve and a pilot servo cylinder, so that the forging cylinder does not extend with the rotation of the eccentric shaft, which changes the traditional forging mode in which the hammer rotates with the eccentric shaft. For example, the forging frequency of the 18MN diameter forging machine can be reduced from the existing 180 times / minute to below 90 times / minute, which is suitable for the large deformation forming requirements of large cross-section billets. (2) Improve the feed rate adjustment range: In the low frequency forging mode, the present invention increases the time interval of hammer strike, providing a longer adjustment time for the axial and rotational feed of the forging. When the frequency is reduced by half, the forging interval time is also increased by a factor of two. Under the same axial feed speed and rotational speed, the axial feed rate and rotational rate are also increased by a factor of two. (3) Optimize the forming quality of forgings: The low-frequency, high-feed forging method increases the deformation of a single impact, which can effectively break the coarse grains of the as-cast structure, eliminate defects such as porosity and shrinkage cavities inside the billet, and improve the core quality and structural uniformity of the forgings; at the same time, accumulators are installed in the main hydraulic oil circuit, the return hydraulic pipeline and the variable frequency piston cylinder hydraulic oil pipeline, which reduces the hydraulic oil pressure fluctuation in the hydraulic oil pipeline and reduces the surface defects of the forgings; (4) Strong process adaptability: By dynamically adjusting the parameters of the cartridge valve through the remote control center, the forging frequency can be adjusted in multiple stages, adapting to the forging process requirements of forging parts of different materials and cross-sectional sizes, such as high-temperature alloys and stainless steel, thus expanding the application range of radial forging machines. Attached Figure Description

[0018] Figure 1 This is a hydraulic schematic diagram of the present invention; Figure 2 This is a schematic diagram of the main unit of a multi-hammer radial forging machine; Figure 3 This is a schematic diagram of the connection structure between the main cartridge valve and the pilot servo cylinder. Figure 4 This is a schematic diagram of the structure of a variable frequency piston cylinder; Figure 5 This is a schematic diagram of the connection structure of the integrated valve block, main cartridge valve, pilot servo cylinder, and variable frequency piston cylinder; the character P in the diagram refers to the integrated valve block and... Figure 1 The oil port connected to the oil source is P in the middle. The character T indicates that the integrated valve block is connected to... Figure 1 The interface of the oil circuit in the intermediate return oil tank; the character X indicates the variable frequency piston cylinder and... Figure 1 The interface of the X-type oil circuit; Figure 6 This is a diagram illustrating the rapid oil removal process; Figure 7 This is a diagram illustrating the fluid resuscitation process; Figure 8 It is a schematic diagram of the main frame, eccentric shaft, slider, and main cylinder structure; In the diagram: 1. Main frame; 2. Slider; 3. Eccentric shaft; 4. Forging cylinder; 5. Hammer rod; 6. Rotary encoder; 7. Return cylinder; 8. Reversing servo valve 1; 9. Main cartridge valve; 10. Variable frequency piston cylinder; 11. Air filter; 12. Variable frequency accumulator; 13. Displacement sensor; 14. Quick-release safety valve; 15. Quick-release servo valve; 16. Quick-release accumulator; 17. Quick-release check valve; 18. Oil tank; 19. Return safety valve; 20. Return check valve; 21. Return accumulator ; 22. Return servo valve; 24. Pilot servo cylinder; 25. Main valve core; 26. Main valve sleeve; 27. Main valve seat; 28. Cylinder; 29. ​​Sliding sleeve; 30. Piston; 31. Guide rod; 32. End cover; 33. Guide sleeve; 34. P1 oil source pump; 35. P1 relief valve; 36. P oil source pump; 37. P relief valve; 38. X oil source pump; 39. X relief valve; 40. Integrated valve block; 41. Main cylinder hydraulic oil chamber; 42. Main hydraulic oil circuit; 43. Quick oil discharge circuit. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] like Figures 1 to 8 The radial forging machine hydraulic frequency conversion system shown includes an eccentric shaft 3 mounted on the main frame 1. The eccentric part of the eccentric shaft 3 passes through the middle hole of the slider 2 and is connected to the main cylinder seat of the forging cylinder 4. The lower end plane of the slider 2 is in contact with the main cylinder seat plane of the forging cylinder 4. The oil port of the forging cylinder 4 is connected to one oil port of the internal oil passage of the integrated valve block 40. The other oil port of the internal oil passage of the integrated valve block 40 is connected to the oil port of the frequency conversion piston cylinder 10. The frequency conversion piston cylinder 10 is fastened to the outside of the integrated valve block 40 by bolts. The main cartridge valve 9 is installed on the internal oil passage of the integrated valve block 40. The hammer rod 5 of the forging cylinder 4 is connected to the forging hammer head, and the end of the hammer rod 5 is connected to the top of the piston rod of the two return cylinders 7 whose cylinder seats are fixed on the main frame 1; the main cylinder hydraulic oil cavity 41 formed between the hammer rod 5 and the inner wall of the main cylinder seat of the forging cylinder 4 is connected to the main hydraulic oil circuit 42, and the main hydraulic oil circuit 42 is equipped with a reversing servo valve 8, a P oil source pump 36, a P overflow valve 37 and a check valve. The P port of the reversing servo valve 8 is connected to the P port oil source, and the main valve core of the main cartridge valve 9 is connected to the pilot servo cylinder 24; the pilot servo cylinder 24 The cylinder seat is mounted on the outer wall of the integrated valve block 40. The displacement sensor 13 is installed at the tail of the pilot servo cylinder 24. The piston rod of the pilot servo cylinder 24 is electrically connected to the displacement sensor 13. The pilot servo cylinder 24 is connected to the P port oil source through the fast oil discharge circuit 43. The fast oil discharge circuit 43 is also equipped with a fast discharge servo valve 15 and a fast discharge safety valve 14. The variable frequency piston cylinder 10 is connected to the variable frequency accumulator 12. The variable frequency accumulator 12, the X port of the reversing servo valve 8 and the X port of the fast discharge servo valve 15 are all connected to the X port oil source. The return oil line of the return cylinder 7 is equipped with a return servo valve 22 and a return safety valve 19. The P port of the return servo valve 22 is connected to the P port oil source.

[0021] The main cartridge valve 9 includes a main valve core 25, a main valve sleeve 26, and a main valve seat 27. A fast discharge accumulator 16 and a fast discharge check valve 17 are installed between the fast discharge servo valve 15 and the P port oil source on the fast discharge circuit 43.

[0022] A quick-release safety valve 14 is installed on the hydraulic oil pipeline between the oil chamber of the pilot piston rod 24 and the oil tank 18.

[0023] A return accumulator 21 and a return check valve 20 are installed on the oil source connection pipeline between port P and port P1 of the return servo valve 22.

[0024] The variable frequency piston cylinder 10 includes a cylinder body 28 and an end cover 32. A piston 30 is assembled in the inner cavity of the cylinder body 28. A guide rod 31 is installed at the center of the rear end of the piston 30. The rear end of the guide rod 31 is assembled in a guide sleeve 33 that passes through the end cover 32. A sliding sleeve 29 is installed on the outer wall of the piston 30. An air filter 11 is installed at the top of the rod chamber of the variable frequency piston cylinder 10.

[0025] The input end of the eccentric shaft 3 is equipped with a rotary encoder 6, which collects the rotation angle, phase and speed signals of the eccentric shaft in real time. The rotary encoder 6 is connected to the remote control center.

[0026] A wear-resistant sleeve is fitted between the eccentric shaft 3 and the intermediate hole of the slider 2; a wear-resistant plate is installed between the contact surfaces of the slider 2 and the forging cylinder 4.

[0027] A high-pressure sealing ring is provided at the connection between the internal oil passage of the variable frequency piston cylinder 10 and the integrated valve block 40.

[0028] Several pressure sensors are installed on the main hydraulic oil circuit and return oil circuit of the forging cylinder 4, and the pressure sensors are connected to the remote control center.

[0029] The working principle of this invention is as follows: Step 1, Initial Preparation: Start the hydraulic pump, connect the P port oil source at 12MPa to fill the fast discharge accumulator 16 with oil; connect the P1 port oil source at 9MPa to fill the return accumulator 21 with oil; connect the X port oil source at 7MPa to fill the frequency converter accumulator 12 with oil. Step 2, Forging Start-up: The starter motor drives the eccentric shaft 3 to rotate, and the eccentric shaft 3 applies axial driving force to the forging cylinder 4. At this time, the oil between the main cylinder seat and the hammer rod of the forging cylinder 4 is a closed dead cavity. When the main cylinder seat of the forging cylinder 4 moves axially, it compresses the oil and pushes the hammer rod 5 to extend for forging. At the same time, the hammer rod 5 compresses the plunger of the return cylinder 7 and retracts, and the oil is discharged to the return accumulator 21. After the eccentric shaft 3 rotates to the bottom dead center, the hammer rod 5 extends and the forging action is completed. The eccentric shaft 3 continues to rotate, and the hammer rod 5 retracts under the hydraulic pushing force of the return cylinder 7. The data collected in real time by the rotary encoder 6 is calculated and the hammer head movement direction and position are determined by the remote control center. During normal forging, the eccentric shaft 3 rotates once, and the hammer head completes one forging cycle. Step 3, Rapid Oil Discharge: When it is necessary to reduce the forging frequency, the remote control center calculates the rotation of the eccentric shaft 3 to the top dead center based on the data collected by the rotary encoder 6. The remote control center then sends control signals to the rapid discharge servo valve 15 and the return servo valve 22. The return servo valve 22 switches to the left position, and its ports P, A, B, and T are not interconnected. The piston of the return cylinder 7 cannot retract, and the hammer rod 5 cannot extend. The rapid discharge servo valve 15 switches to the right position, and its ports P and B connect to A and T. The oil pressure pushes the piston rod of the pilot servo cylinder 24, causing the main valve core 25 to move. The main valve core 25 and the main valve seat 27 open to create a throttling orifice. The displacement sensor 13 detects this in real time. The position of the piston rod of the pilot servo cylinder 24 is detected. At this time, the forging cylinder 4 moves downward with the rotation of the eccentric shaft 3. Since the hammer rod 5 cannot move downward under the action of the return cylinder 7, the oil between the main cylinder seat of the forging cylinder 4 and the hammer rod 5 is quickly discharged through the throttle port opened between the main valve core 25 and the main valve seat 27, and enters the variable frequency piston cylinder 10 through the flow channel on the main valve sleeve 26. The oil pushes the piston 30, the sliding sleeve 29 and the guide rod 31 to move backward. The air on the other side of the piston 30 is discharged through the air filter 11. The guide rod 31 pushes the oil back to the variable frequency accumulator 12. When the eccentric shaft 3 rotates to the bottom dead center, the rapid oil discharge ends. Step 4, Rapid Oil Replenishment: After the eccentric shaft 3 passes the bottom dead center and continues to rotate, the forging cylinder 4 is no longer driven by the eccentric shaft 3. At this time, the guide rod 31, under the push of the hydraulic pressure, drives the piston 30 and the sliding sleeve 29 to move forward. The oil is reversed and pressed into the cavity between the hammer rod 5 and the main cylinder seat of the forging cylinder 4. The remote control center detects and calculates when the eccentric shaft 3 rotates to the top dead center through the rotary encoder 6, and sends control signals to the quick-release servo valve 15 and the return servo valve 22. The quick-release servo valve 15 switches to the left position, with its oil port P connected to B and A connected to T. The high-pressure oil drives the pilot. The piston rod of the servo cylinder 24 drives the main valve core 25 to move, closing the throttle port between the main valve core 25 and the valve seat 27. The position of the piston rod of the pilot servo cylinder 24 is detected by the displacement sensor 13 to ensure that the throttle port between the main valve core 25 and the valve seat 27 is completely closed. The cavity between the hammer rod 5 and the main cylinder seat of the forging cylinder 4 is sealed as a dead cavity. The return servo valve 22 is switched to the right position, and its oil port P is connected to A and B is connected to T. The return cylinder 7 is connected to the return accumulator 21. When the eccentric shaft 3 moves downward from the top dead point, the hammer rod 5 compresses the plunger of the return cylinder 7 and extends it to perform forging.

[0030] Step 5, Precise Position Adjustment: The eccentric shaft 3 moves downward from the top dead center, and the throttling port between the main valve core 25 and the valve seat 27 is completely closed. At the same time, the remote control center controls the reversing servo valve 8 to quickly and precisely adjust the position of the hammer rod 5 to ensure that the forging size after the hammer rod 5 extends is the target forging size.

[0031] This invention uses a main cartridge valve and a pilot servo cylinder to form a rapid oil discharge channel, so that the forging cylinder does not extend with the rotation of the eccentric shaft. This changes the traditional forging mode where the hammer rotates with the eccentric shaft. For example, the forging frequency of an 18MN diameter forging machine can be reduced from the current 180 times / minute to below 90 times / minute, which is suitable for the large deformation forming requirements of large cross-section billets. In the low-frequency forging mode, the time interval between hammer strikes is increased, providing a longer adjustment time for the axial and rotational feed of the forging. The frequency is reduced by half, and the forging interval time is also increased exponentially. At the same axial feed speed and rotational speed, the axial feed amount and rotation amount are also increased exponentially.

[0032] The above are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, other equivalent modifications and improvements can be made based on the technical teachings provided by the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A hydraulic frequency conversion system for a radial forging machine, characterized in that: The eccentric shaft (3) is installed on the main frame (1). The eccentric part of the eccentric shaft (3) passes through the middle hole of the slider (2) and is connected to the main cylinder seat of the forging cylinder (4). The lower end plane of the slider (2) is in contact with the main cylinder seat plane of the forging cylinder (4). The oil port of the forging cylinder (4) is connected to one oil port of the internal oil passage of the integrated valve block (40). The other oil port of the internal oil passage of the integrated valve block (40) is connected to the oil port of the variable frequency piston cylinder (10). The variable frequency piston cylinder (10) is fastened to the outside of the integrated valve block (40) by bolts. The main cartridge valve (9) is installed on the internal oil passage of the integrated valve block (40). The hammer rod (5) of the forging cylinder (4) is connected to the forging hammer head, and the end of the hammer rod (5) is connected to the top of the piston rod of the two return cylinders (7) whose cylinder seats are fixed on the main frame (1); the main cylinder hydraulic oil cavity (41) formed between the hammer rod (5) and the inner wall of the main cylinder seat of the forging cylinder (4) is connected to the main hydraulic oil circuit (42), and the main hydraulic oil circuit (42) is equipped with a reversing servo valve (8), a P oil source pump (36), a P overflow valve (37) and a check valve. The P port of the reversing servo valve (8) is connected to the P port oil source, and the main valve core (25) of the main cartridge valve (9) and the pilot servo cylinder are connected to the main cylinder. (24) are connected, the cylinder seat of the pilot servo cylinder (24) is mounted on the outer wall of the integrated valve block (40), the piston rod of the pilot servo cylinder (24) is electrically connected to the displacement sensor (13), the pilot servo cylinder (24) is connected to the P port oil source through the fast oil discharge circuit (43); the fast oil discharge circuit (43) is also equipped with a fast discharge servo valve (15) and a fast discharge safety valve (14); the variable frequency piston cylinder (10) is connected to the variable frequency accumulator (12), the X port of the variable frequency accumulator (12), the X port of the reversing servo valve (8) and the X port of the fast discharge servo valve (15) are all connected to the X port oil source; The return oil line of the return cylinder (7) is equipped with a return servo valve (22) and a return safety valve (19), and the P port of the return servo valve (22) is connected to the P port oil source; The input end of the eccentric shaft (3) is equipped with a rotary encoder (6) that collects the rotation angle, phase and speed signals of the eccentric shaft in real time. The rotary encoder (6) is connected to the remote control center.

2. The frequency conversion system according to claim 1, characterized in that: The main cartridge valve (9) includes a main valve core (25), a main valve sleeve (26) and a main valve seat (27), with one end of the main valve core (25) connected to the pilot piston rod.

3. The frequency conversion system according to claim 1, characterized in that: A fast discharge accumulator (16) and a fast discharge check valve (17) are installed between the fast discharge servo valve (15) and the P port oil source on the fast discharge circuit (43).

4. The frequency conversion system according to claim 1, characterized in that: A quick-release safety valve (14) is installed on the hydraulic oil line between the pilot piston rod oil chamber and the oil tank (18).

5. The frequency conversion system according to claim 1, characterized in that: The return servo valve (22) has a return accumulator (21) and a return check valve (20) installed on the connection pipeline between the P port and the P port oil source.

6. The frequency conversion system according to claim 1, characterized in that: The variable frequency piston cylinder (10) includes a cylinder (28) and an end cap (32). A piston (30) is assembled in the inner cavity of the cylinder (28). A guide rod (31) is installed at the center of the rear end of the piston (30). The rear end of the guide rod (31) is assembled in a guide sleeve (33) that passes through the end cap (32). A sliding sleeve (29) is installed on the outer wall of the piston (30). An air filter (11) is installed at the top of the rod chamber of the variable frequency piston cylinder (10).

7. The frequency conversion system according to claim 1, characterized in that: A wear-resistant sleeve is fitted between the eccentric shaft (3) and the intermediate hole of the slider (2); a wear-resistant plate is installed between the contact surfaces of the slider (2) and the forging cylinder (4).

8. The frequency conversion system according to claim 1, characterized in that: A high-pressure sealing ring is provided at the connection between the internal oil passage of the variable frequency piston cylinder (10) and the integrated valve block (40).

9. The frequency conversion system according to claim 1, characterized in that: Several pressure sensors are installed on the main hydraulic oil circuit and return oil circuit of the forging cylinder (4), and the pressure sensors are connected to the remote control center.

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