Fatigue testing machine actuator

Abstract

The utility model discloses an actuator for fatigue testing machine belongs to fatigue test equipment technical field. The actuator includes cylinder and the piston of sliding in cylinder, and the piston has piston rod. Its rear end and top have integrated function structure: the rear end is equipped with rear flange, and the anti -rotation board and sensor seat are fixed on the rear flange, the anti -rotation board and piston rod sliding contact, and the annular magnetic block of fixed in the piston rod end is equipped in sensor seat, and the top is equipped with servo valve board, and the fluid intercommunication accumulator valve block is equipped with servo valve board side, and the first and second capsule type energy accumulator are installed on accumulator valve block. The utility model discloses through the integration of energy storage, anti -rotation and sensing system, has solved the problem that the existing actuator is under high frequency and the piston rotation influence precision under the big pressure fluctuation, has compact structure, can stable system pressure, guarantees the piston pure linear motion, the effect that overall control precision is comprehensively promoted.

Description

Technical Field

[0001] This utility model relates to a fatigue testing machine as an actuator, and to the field of mechatronics and automation equipment that requires high-precision force and displacement control, particularly to a fatigue testing machine as an actuator. Background Technology

[0002] Fatigue testing machines are crucial equipment for evaluating the fatigue life of materials and structural components. Their core actuators are responsible for applying precise and controllable cyclic loads to the test specimens. Among various actuator types, electro-hydraulic servo actuators are widely used due to their advantages such as high output force, fast response speed, and high control precision. For example, aerospace attitude control and weapon aiming systems in the defense industry require actuators to maintain micron-level positioning accuracy during high-speed reciprocating motion. In heavy industries such as shipbuilding and mining, high-flow systems driving giant components can suffer serious consequences from any control delays or instabilities, such as jitter caused by pressure pulsations. This cross-industry demand has driven the pursuit of the ultimate servo performance of actuators, making the stability of actuators under high-frequency, heavy-load conditions increasingly critical and urgent to be addressed.

[0003] With increasingly stringent requirements for material performance, fatigue tests often need to be conducted at high frequencies. Under high-frequency reciprocating motion conditions, the hydraulic system inside the actuator will generate severe pressure pulsations, which not only affect the stability of the output force but also pose a serious challenge to the system's rapid response capability.

[0004] Furthermore, to achieve precise closed-loop control of displacement or force, actuators need to integrate high-precision sensors. However, traditional actuator designs often overlook the minute rotations that may occur during the reciprocating motion of the piston. Once this rotation occurs, it directly affects the measurement reference of the displacement sensor, causing feedback signal distortion, which severely reduces the positioning accuracy and control stability of the entire servo control system.

[0005] In summary, the existing fatigue testing machine actuators have difficulty in simultaneously solving the two major challenges of pressure stability at high frequencies and the purity of piston motion posture in their structural design, resulting in poor performance in high-precision servo control applications.

[0006] Therefore, this utility model proposes a fatigue testing machine as an actuator to overcome the shortcomings of the prior art. Utility Model Content

[0007] To overcome the above shortcomings, this utility model provides a brake for a fatigue testing machine, aiming to improve the problems of large pressure fluctuations and easy piston rotation during high-frequency operation in the existing fatigue testing machine brake, which affect the control accuracy.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a fatigue testing machine actuator, comprising: a cylinder and a piston; the piston comprises a piston head that is slidably fitted inside the cylinder and a piston rod extending from the rear end of the cylinder; the fatigue testing machine actuator further comprises a rear end and a top structure integrating sensing, anti-rotation and energy storage.

[0009] The rear and top structures are a combined structure formed by compactly integrating components with different functions.

[0010] The components in the rear and top structures are combined in the following manner: the rear flange is fixedly connected to the rear end of the cylinder; the sensor seat is fixed to the outside of the rear flange and covers the end of the piston rod; the annular magnetic block is fixed to the area of ​​the piston rod located inside the sensor seat; the anti-rotation plate is fixed to the outer wall of the rear flange and slides in contact with the outer surface of the piston rod; the servo valve plate is fixedly connected to the top outer wall of the cylinder; the accumulator valve block is fluidly connected and arranged side by side on one side of the servo valve plate, and a first capsule accumulator and a second capsule accumulator are installed at the upper end of the accumulator valve block.

[0011] Preferably, a roller bearing is installed inside the anti-rotation plate, and the roller bearing makes rolling contact with the outer surface of the piston rod.

[0012] Preferably, a tail cylinder is also fitted on the outer side of the rear flange, and the tail cylinder is located between the rear flange and the sensor seat; the front end of the cylinder is sealed by the front flange; the actuator of the fatigue testing machine also includes studs and nuts that penetrate the front flange, the cylinder and the rear flange.

[0013] Preferably, the fatigue testing machine further includes a first bolt, a second bolt, and a third bolt for fixing the sensor seat and the anti-rotation plate; and a fourth bolt for assisting in tightening the rear flange.

[0014] Preferably, the piston head of the piston is provided with a Glyd ring for a hole; the piston rod is provided with a shaft seal and a thin combined dustproof ring at the position where it passes through the cylinder.

[0015] Preferably, a first O-ring, a second O-ring, and a third O-ring are provided at the connection interface between the front flange, the rear flange, the servo valve plate, and the cylinder.

[0016] Preferably, a magnetic shielding pad is provided between the annular magnetic block and the piston rod; the accumulator valve block is also provided with a sensor as a pressure measuring point.

[0017] Preferably, the fluid communication between the servo valve plate and the accumulator valve block is achieved through a piping system, which includes stainless steel pipes and compression tees, carbon steel fittings, stainless steel fittings, and threaded fittings for connecting the stainless steel pipes.

[0018] Preferably, the unused oil ports on the servo valve plate and the accumulator valve block are sealed by a first hexagonal socket plug, a second hexagonal socket plug, a third hexagonal socket plug, and a fourth hexagonal socket plug. This utility model has the following beneficial effects: 1. In this utility model, by setting an accumulator valve block that is fluidly connected to the servo valve plate, and installing a first capsule-type accumulator and a second capsule-type accumulator on the accumulator valve block, the problem of unstable output force and slow response speed caused by oil pressure pulsation during high-frequency reciprocating motion of the actuator in the prior art is solved, and the technical effect of stabilizing system pressure and improving high-frequency dynamic response capability is achieved.

[0019] 2. In this utility model, by setting an anti-rotation mechanism composed of an anti-rotation plate and a roller bearing, the anti-rotation mechanism forms a rolling guide with the outer surface of the piston rod, which solves the problem in the prior art that the piston is prone to rotation during reciprocating motion, resulting in inaccurate displacement measurement. It achieves the technical effect of ensuring pure linear motion of the piston and improving the stability and reliability of the displacement sensing system. Attached Figure Description

[0020] Figure 1 This is a three-dimensional schematic diagram of a fatigue testing machine using an actuator according to the present invention; Figure 2 This is a front view of the actuator used in the fatigue testing machine proposed in this utility model; Figure 3 This is a schematic diagram of the left side structure of the actuator used in the fatigue testing machine proposed in this utility model; Figure 4 This is a schematic diagram of the right side structure of the actuator used in the fatigue testing machine proposed in this utility model; Figure 5 This is a side view of the actuator used in a fatigue testing machine according to the present invention. Figure 6 This is a top view of the actuator used in a fatigue testing machine according to the present invention. Figure 7 This is a cross-sectional structural diagram of the actuator used in a fatigue testing machine proposed in this utility model.

[0021] Legend: 1. Piston; 2. Cylinder; 3. Front flange; 4. Rear flange; 5. Tail tube; 6. Sensor mount; 7. Stud; 8. Nut; 9. Servo valve plate; 10. Accumulator valve block; 11. Anti-rotation plate; 12. Glyd ring for bores; 13. Step seal for shafts; 14. Thin combination dust seal; 15. First O-ring; 16. Second O-ring; 17. Third O-ring; 18. First capsule accumulator; 19. Second capsule accumulator; 20. Sensor; 21. Ring-shaped magnetic block; 22. Magnetic shielding gasket; 23. Roller bearing; 24. Threaded connector; 25. Carbon steel connector; 26. Stainless steel connector; 27. Compression fitting tee; 28. First hexagonal socket plug; 29. ​​Second hexagonal socket plug; 30. Third hexagonal socket plug; 31. Fourth hexagonal socket plug; 32. Stainless steel pipe; 33. First bolt; 34. Second bolt; 35. Third bolt; 36. Fourth bolt. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Reference Figures 1-7 The present invention provides an embodiment of a fatigue testing machine actuator, which aims to solve the problems of insufficient position control accuracy, large pressure fluctuation, and easy piston rotation affecting measurement accuracy in the prior art fatigue testing machine actuator.

[0024] A fatigue testing machine actuator includes a cylinder 2 and a piston 1 that slides inside the cylinder 2; the piston 1 includes a piston head and a piston rod extending from the rear end of the cylinder 2; the core structure of the actuator is a rear end and top structure that integrates sensing, anti-rotation and energy storage, which organically integrates various functional components around the cylinder 2. Specifically, at the rear end of the actuator, the rear flange 4 is fixedly connected to the rear end of the cylinder 2. The sensor seat 6 is fixed to the outside of the rear flange 4 by fasteners such as the first bolt 33 and the second bolt 34. The sensor seat 6 is also covered at the end of the piston rod for installing and protecting the displacement sensing system. The annular magnetic block 21, as the sensing element of the displacement sensing system, is firmly fixed in the sensing area of ​​the piston rod located inside the sensor seat 6. This non-contact arrangement allows the sensor probe fixed inside the sensor seat 6 to accurately detect the position of the annular magnetic block 21 that moves with the piston rod, thereby achieving high-precision displacement closed-loop control. Meanwhile, in order to ensure that the piston rod does not rotate during high-speed reciprocating motion, an anti-rotation mechanism is provided at the rear end of the actuator. The anti-rotation plate 11 is fixed to the outer side wall of the rear flange 4 by the third bolt 35. The anti-rotation plate 11 slides in contact with the outer surface of the piston rod. By providing a fixed guide surface, the movement trajectory of the piston rod is constrained, ensuring that the piston 1 only performs pure linear motion. At the top of the actuator, the servo valve plate 9 is fixedly connected to the top outer wall of the cylinder 2, serving as the core interface for hydraulic control; the accumulator valve block 10 is fluidly connected to the servo valve plate 9 and is arranged side by side, together forming the top hydraulic control module; the first capsule accumulator 18 and the second capsule accumulator 19 are vertically installed at the upper end of the accumulator valve block 10, used to store energy and absorb pressure pulsations under high-frequency operating conditions, ensuring the rapid response and pressure stability of the hydraulic system.

[0025] The actuator's overall frame consists of a cylinder 2 and flanges at both ends. The front end of the cylinder 2 is sealed by a front flange 3, and the rear end is fixedly connected to a rear flange 4. A tail cylinder 5 is also mounted on the outside of the rear flange 4, and the tail cylinder 5 is positioned between the rear flange 4 and the sensor seat 6. To ensure the rigidity and sealing of the entire cylinder structure under high pressure, multiple studs 7 penetrate the front flange 3, cylinder 2, and rear flange 4, and are locked at both ends by nuts 8, firmly integrating the above components into one. In addition, a fourth bolt 36 is provided for auxiliary fastening of components such as the rear flange 4. Specifically, the anti-rotation plate 11 is fixed to the outer wall of the rear flange 4 by the third bolt 35. The anti-rotation plate 11 is equipped with a roller bearing 23. In the assembled state, the roller of the roller bearing 23 forms a rolling contact with the outer surface of the piston rod. The rolling guide relationship can provide reliable lateral support and rotation constraint for the piston rod with extremely low friction when it reciprocates, thereby completely avoiding the rotation of the piston rod and ensuring the stability and accuracy of the position detection of the annular magnetic block 21. In addition, to ensure long-term leak-free operation of the hydraulic system, the actuator adopts a multi-seal structure. In terms of dynamic sealing, a Glyd ring 12 for sealing holes is installed on the outer circumference of the piston head of piston 1 to seal the gap between the piston head and the inner wall of cylinder 2. At the position where the piston rod passes through cylinder 2, a shaft seal 13 and a thin combined dust seal 14 are installed in sequence. The shaft seal 13 is used to prevent high-pressure hydraulic oil from leaking out, and the thin combined dust seal 14 is used to scrape dust and contaminants from the surface of the piston rod to prevent external impurities from entering the hydraulic system. In terms of static sealing, the first O-ring 15, the second O-ring 16, and the third O-ring 17 are respectively installed at the fixed connection interface between the front flange 3, the rear flange 4, and the servo valve plate 9 and the cylinder 2, ensuring that there is no leakage between the mating surfaces of each component.

[0026] A magnetic isolation pad 22 is also provided between the annular magnetic block 21 and the piston rod. The magnetic isolation pad 22 is used to isolate the magnetic field of the annular magnetic block 21 and avoid interference with the sensor signal. In addition, a sensor 20 is also provided on the accumulator valve block 10. The sensor 20 serves as a pressure measuring point or pressure sensor interface to monitor the hydraulic system pressure in real time, thereby providing feedback signals for achieving closed-loop force control.

[0027] To construct a complete and reliable hydraulic circuit, the fluid connection between the servo valve plate 9 and the accumulator valve block 10 is achieved through a piping system. This piping system includes a main oil pipeline stainless steel pipe 32, as well as threaded connectors 24, carbon steel connectors 25, stainless steel connectors 26, and compression fittings 27 for connecting the stainless steel pipe 32 with other hydraulic components. These connectors and pipelines reliably connect the various hydraulic components into a complete hydraulic system.

[0028] To ensure the sealing integrity of the hydraulic circuit and prevent oil leakage, the unused oil ports reserved on the servo valve plate 9 and the accumulator valve block 10 are all sealed with corresponding plugs; specifically, these oil ports are reliably threaded sealed by the first internal hexagon plug 28, the second internal hexagon plug 29, the third internal hexagon plug 30 and the fourth internal hexagon plug 31.

[0029] Working principle: When the external control system sends an electrical signal command to the servo valve installed on the servo valve plate 9, the servo valve converts the electrical signal into precise hydraulic flow and pressure. The high-pressure oil enters the cylinder 2 through the servo valve plate 9. By alternately supplying and returning oil to the two chambers on both sides of the piston head of the piston 1, a pressure difference is formed at both ends of the piston head, thereby driving the piston 1 and the piston rod fixed to it to perform precise reciprocating linear motion in the cylinder 2.

[0030] Under high-frequency reciprocating motion conditions, the rapid reversal of piston 1 requires a large instantaneous flow of oil. At the same time, the rapid switching of the servo valve will cause system pressure pulsation. At this time, the first capsule accumulator 18 and the second capsule accumulator 19 on the accumulator valve block 10, which are in fluid communication with the servo valve plate 9, release the pre-stored high-pressure oil to meet the flow requirements and absorb and buffer the pressure shock, thereby ensuring the smoothness of the actuator output and high dynamic response capability.

[0031] While piston 1 moves, the actuator achieves precise closed-loop control through its integrated sensing and anti-rotation system. The annular magnetic block 21 fixed to the end of the piston rod moves synchronously with the piston rod. The sensor probe located in the sensor seat 6 detects the position change of the annular magnetic block 21 non-contactly and feeds the signal back to the control system. This precise measurement is achieved by the anti-rotation mechanism composed of the anti-rotation plate 11 and the roller bearing 23. This mechanism strictly limits the rotation of the piston rod at any angle during movement by rolling contact with the outer surface of the piston rod, ensuring the accuracy of displacement measurement. At the same time, the sensor 20 set on the accumulator valve block 10 can monitor the system pressure in real time and provide feedback for force control.

Claims

1. A fatigue testing machine as an actuator, comprising: Cylinder (2); Piston (1), the piston (1) includes a piston head that is slidably fitted inside the cylinder (2) and a piston rod that extends from the rear end of the cylinder (2); Its characteristic is that it further includes: The rear end and top structure includes: a rear flange (4), which is fixedly connected to the rear end of the cylinder (2); Sensor base (6), the sensor base (6) is fixed to the outside of the rear flange (4) and covers the end of the piston rod; An annular magnetic block (21) is fixed to the area where the piston rod is located inside the sensor seat (6); Anti-rotation plate (11), the anti-rotation plate (11) is fixed to the outer side wall of the rear flange (4) and slides in contact with the outer surface of the piston rod; Servo valve plate (9), which is fixedly connected to the top outer wall of the cylinder (2); Accumulator valve block (10), which is fluidly connected and arranged side by side on one side of the servo valve plate (9), and a first capsule accumulator (18) and a second capsule accumulator (19) are installed on the upper end of the accumulator valve block (10).

2. The fatigue testing machine as an actuator according to claim 1, characterized in that, The anti-rotation plate (11) is equipped with a roller bearing (23) inside, and the roller bearing (23) makes rolling contact with the outer surface of the piston rod.

3. The fatigue testing machine as an actuator according to claim 1, characterized in that, The rear flange (4) is also fitted with a tail cylinder (5), which is located between the rear flange (4) and the sensor seat (6); the front end of the cylinder (2) is sealed by the front flange (3); and studs (7) and nuts (8) are also included that penetrate the front flange (3), the cylinder (2) and the rear flange (4).

4. The fatigue testing machine as an actuator according to claim 3, characterized in that, It also includes a first bolt (33), a second bolt (34), and a third bolt (35) for securing the sensor base (6) and the anti-rotation plate (11); and a fourth bolt (36) for assisting in fastening the rear flange (4).

5. The fatigue testing machine as an actuator according to claim 1, characterized in that, The piston (1) has a Glyd ring (12) for holes on the outer periphery of the piston head, and the piston rod has a shaft seal (13) and a thin combined dustproof ring (14) at the position where it passes through the cylinder (2).

6. The fatigue testing machine according to claim 3, characterized in that, A first O-ring (15), a second O-ring (16), and a third O-ring (17) are provided at the connection interface between the front flange (3), the rear flange (4), the servo valve plate (9), and the cylinder (2).

7. The fatigue testing machine as an actuator according to claim 1, characterized in that, A magnetic shielding pad (22) is provided between the annular magnetic block (21) and the piston rod; a sensor (20) as a pressure measuring point is also provided on the accumulator valve block (10).

8. The fatigue testing machine as an actuator according to claim 1, characterized in that, The fluid communication between the servo valve plate (9) and the accumulator valve block (10) is achieved through a pipeline system, which includes a stainless steel pipe (32) and a compression tee (27), a carbon steel connector (25), a stainless steel connector (26), and a threaded connector (24) for connecting the stainless steel pipe (32).

9. The fatigue testing machine as an actuator according to claim 1, characterized in that, The unused ports on the servo valve plate (9) and the accumulator valve block (10) are sealed by the first internal hexagon plug (28), the second internal hexagon plug (29), the third internal hexagon plug (30) and the fourth internal hexagon plug (31).

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