Dual fluid cylinder clamp

Abstract

The application discloses a double-cylinder clamping device, which comprises a clamping head, a cylinder body arranged below the clamping head, an upper end cover and a lower end cover fixed to the upper and lower ends of the cylinder body respectively, the upper end cover is fixedly connected with the lower end of the clamping head, an upper clamping driving mechanism, a self-adaptive force balance mechanism, a lower clamping driving mechanism, a partition plate and a self-locking mechanism are sequentially arranged in the cylinder body from top to bottom, the upper end cover of the upper clamping driving mechanism extends into the clamping head and is slidably connected with the upper end cover, the lower end of the lower clamping driving mechanism sequentially passes through the partition plate and the self-locking mechanism, a hydraulic port E is arranged on the corresponding side wall of the cylinder body between the self-locking mechanism and the partition plate, a hydraulic port F is arranged on the corresponding side wall of the cylinder body between the self-locking mechanism and the lower end cover, and a mounting guide rod M is fixedly installed on the outer side wall of the lower end cover. The application solves the problem that the underwater equipment rigid joint is affected by sea waves, water flow and mud surface for a long time in the prior art, which leads to loose connection, separation and sealing leakage and interruption of the operation process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil drilling and workover equipment, and relates to a double-liquid-cylinder clamping device. BACKGROUND

[0002] In the process of offshore oil and gas development, underwater equipment such as underwater riser, riser, subsea umbilical, and production pipeline are connected for a long distance to establish a closed channel for drilling, tripping, and oil and gas transportation. These underwater equipment are placed in the marine operating environment for a long time and are easily affected by external dynamic loads such as sea waves, water flow, and mud collapse, causing wear and tear and fatigue damage at the joint, leading to connection loosening, separation, and sealing leakage, and interrupting the operation process. Once an abnormality occurs, underwater inspection and repair or recovery of the problem equipment are usually required, and the operation or production can continue only after the repair is completed. The complex maintenance supporting equipment and personnel requirements, as well as the difficulty and long period of underwater maintenance operation, result in high maintenance operation cost. In summary, the underwater equipment is easily subject to wear and tear and fracture under the action of external dynamic loads, and the maintenance operation time is long and the risk is great after a fault occurs, and the deepwater operation cost is high. Therefore, it is urgent to develop a device that is simple to operate and can reduce the influence of external loads such as sea waves and water flow on the subsea umbilical, underwater riser, riser, and production pipeline, so as to maintain reliable connection of the underwater equipment for a long time and monitor the real-time connection state, and improve the reliability and service life. SUMMARY

[0003] The purpose of the present application is to provide a double-liquid-cylinder clamping device that solves the problem of connection loosening, separation, and sealing leakage caused by the influence of sea waves, water flow, and mud on the joint of underwater equipment in the prior art.

[0004] The technical solution adopted by the present application is a double-liquid-cylinder clamping device, which comprises a clamping head and a cylinder body arranged below the clamping head. An upper end cover and a lower end cover are fixedly arranged at the upper and lower ends of the cylinder body, respectively. The upper end cover is fixedly connected to the lower end of the clamping head. An upper clamping driving mechanism, a self-adaptive force balancing mechanism, a lower clamping driving mechanism, an isolation plate, and a self-locking mechanism are sequentially arranged in the cylinder body from top to bottom. The upper end of the upper clamping driving mechanism extends into the clamping head through the upper end cover and is in sliding connection with the upper end cover. The lower end of the lower clamping driving mechanism sequentially passes through the isolation plate and the self-locking mechanism. A hydraulic port E is formed in the corresponding side wall of the cylinder body between the self-locking mechanism and the isolation plate. A hydraulic port F is formed in the corresponding side wall of the cylinder body between the self-locking mechanism and the lower end cover. An installation guide rod M is fixedly installed on the outer side wall of the lower end cover.

[0005] The present application is also characterized in that,

[0006] The clamping head is arranged as a "C"-shaped opening clamping head.

[0007] The lower wall of the clamping head is provided with a cover assembly hole, and the inner surface of the lower wall of the clamping head is provided with a retaining nut clamping groove around the cover assembly hole. The upper surface of the upper cover is provided with an extension end, which extends into the cover assembly hole and extends into the inside of the "C" type clamping head. The extension end of the upper cover is connected with a retaining nut through a threaded connection, and the retaining nut is clamped in the retaining nut clamping groove. The clamping head and the upper cover are fixed by the retaining nut clamped in the retaining nut clamping groove and the clamping head lower surface and the upper cover upper surface clamping.

[0008] The upper clamping driving mechanism includes an upper piston connected with the inner wall of the cylinder through sliding fit below the upper cover in the cylinder. The upper surface of the upper piston is connected with a clamping rod, the upper end of the clamping rod extends into the "C" type inside of the clamping head through the upper cover, the clamping rod is connected with the upper cover through sliding, and the top of the clamping rod is provided with a pressure sensor. The upper surface of the upper piston, the clamping rod and the lower surface of the upper cover form a cavity a, and the corresponding side wall of the cylinder is provided with a hydraulic port A.

[0009] The lower clamping driving mechanism includes a lower piston connected with the inner wall of the cylinder through sliding fit below the self-adaptive force balance mechanism in the cylinder. The lower surface of the lower piston is fixedly connected with a self-locking rod, and the lower end of the self-locking rod passes through the isolation plate and the self-locking mechanism in sequence.

[0010] The self-adaptive force balance mechanism is a plurality of springs uniformly arranged between the upper surface of the lower piston and the lower surface of the upper piston, and the two ends of the spring are fixed on the upper surface of the lower piston and the lower surface of the upper piston respectively.

[0011] The isolation plate is connected with the inner wall of the cylinder through threaded connection, and the cavity b is formed between the upper surface of the isolation plate, the self-locking rod and the lower surface of the lower piston. The corresponding side wall of the cylinder is provided with a hydraulic port B.

[0012] The self-locking mechanism comprises a plurality of locking sliders, the outer side profile of the locking sliders is a tapered surface, the inner side of the locking sliders is a cylindrical surface, the plurality of locking sliders are spliced into a complete hollow circular truncated cone body, the self-locking rod passes through the hollow part of the hollow circular truncated cone body, the outer diameter of the hollow circular truncated cone body gradually decreases from top to bottom, the inner wall of the cylinder body corresponding to the hollow circular truncated cone body is provided as a tapered surface matched with the hollow circular truncated cone body, the upper surfaces and the lower surfaces of the plurality of locking sliders are respectively provided with upper push plates and lower push plates, the upper push plates and the lower push plates are adapted to the inner wall of the cylinder body and slide up and down on the inner wall of the cylinder body, the diameter of the upper push plate is equal to the maximum diameter of the hollow circular truncated cone body, the diameter of the lower push plate is equal to the minimum diameter of the hollow circular truncated cone body, the upper push plates and the lower push plates are provided with T-shaped grooves distributed along the radial direction of the upper push plates and the lower push plates at positions corresponding to each locking slider, the upper surfaces and the lower surfaces of each locking slider are provided with T-shaped sliders corresponding to the T-shaped grooves, and the T-shaped sliders slide in the T-shaped grooves in the radial direction of the upper push plates and the lower push plates; a cavity e is formed between the upper surface of the upper push plate, the self-locking rod, the inner wall of the cylinder body and the lower surface of the isolation plate, a hydraulic port E is arranged on the side wall of the cylinder body corresponding to the cavity e, a cavity f is formed between the lower surface of the lower push plate, the self-locking rod, the inner wall of the cylinder body and the upper surface of the lower end cover, and a hydraulic port F is arranged on the side wall of the cylinder body corresponding to the cavity f, the tapered surface of the locking slider is an angle, that is, the self-locking angle is γ, and the locking slider is made of a deformable material.

[0013] The upper end cover and the clamping rod are sequentially provided with a wear-resistant ring and a seal I from top to bottom, the upper end cover and the inner wall of the cylinder body are provided with a seal II, the upper piston and the inner wall of the cylinder body are provided with a seal III, the lower piston and the inner wall of the cylinder body are provided with a seal IV, the isolation plate and the self-locking rod and the inner wall of the cylinder body are respectively provided with a seal V and a seal VI, the upper push plate and the self-locking rod and the inner wall of the cylinder body are respectively provided with a seal VII and a seal VIII, and the lower push plate and the self-locking rod and the inner wall of the cylinder body are respectively provided with a seal X and a seal IX.

[0014] The beneficial effects of the present application are:

[0015] The device is driven by hydraulic pressure, allows remote and full-automatic operation, is not limited by the working water depth, solves the problem that deep-water and super-deep-water divers cannot work, reduces the underwater maintenance operation cost and risk of underwater equipment, the self-adaptive force balancing mechanism of the clamping device can automatically adjust and absorb the force caused by external load changes, reduces the eccentric load and wear caused by the action of wind and waves, water flow and mud surface collapse of underwater equipment, improves the connection reliability and service life of underwater equipment, the device is a mechanical structure, can be applied to harsh seabed environment, and can be repeatedly used, through the combination of a plurality of cylinder sizes and spring capacities of the self-adaptive force balancing mechanism, the application requirements of the clamping force of specific underwater equipment are met, the manufacturing cost and use cost are low, the self-locking mechanism of the device can provide a continuous and constant clamping force in the whole life cycle without continuous energy supply and regular maintenance after the clamping operation is completed, and the device has strong universality and is suitable for underwater risers, risers, submarine umbilical cables and production pipelines. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the double-liquid-cylinder clamping device of the present application;

[0017] Figure 2 is a schematic diagram of the self-locking principle of the locking slider in the double-liquid-cylinder clamping device of the present application;

[0018] Figure 3 is a schematic diagram of the assembly structure of the locking slider, the upper push plate and the lower push plate in the double-liquid-cylinder clamping device of the present application;

[0019] Figure 4 is a schematic diagram of the structure of the locking slider and the T-shaped slider in the double-liquid-cylinder clamping device of the present application;

[0020] Figure 5 is a schematic diagram of the installation of the double-liquid-cylinder clamping device of the present application;

[0021] Figure 6 is a process diagram of the loosening operation of the double-liquid-cylinder clamping device of the present application.

[0022] In the figure, 1. lower end cover, 2. cylinder body, 3. locking slider, 3-1. T-shaped slider, 4. self-locking rod, 5. isolation plate, 6. lower piston, 7. self-adaptive force balance mechanism, 8. upper piston, 9. upper end cover, 10. clamping rod, 11. retaining nut, 12. clamping head, 13. sensor, 14. wear-resistant ring, 15. seal I, 16. seal II, 17. seal III, 16. seal IV, 19. seal V, 20. seal VI, 21. seal VII, 22. upper push plate, 22-1. T-shaped groove, 23. seal VIII, 24. lower push plate, 25. seal IX, 26. seal X. DETAILED DESCRIPTION

[0023] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0024] Example 1

[0025] The double-liquid-cylinder clamping device of the present application has the structure as shown in Figure 1As shown, the device includes a clamping head 12 and a cylinder 2 located below the clamping head 12. An upper end cover 9 and a lower end cover 1 are fixedly installed at the upper and lower ends of the cylinder 2, respectively. The upper end cover 9 is fixedly connected to the lower end of the clamping head 12. From top to bottom, the cylinder 2 is provided with an upper clamping drive mechanism, an adaptive force balancing mechanism 7, a lower clamping drive mechanism, an isolation plate 5, and a self-locking mechanism. The upper end of the upper clamping drive mechanism extends through the upper end cover 9 into the clamping head 12 and is slidably connected to the upper end cover 9. The lower end of the lower clamping drive mechanism passes through the isolation plate 5 and the self-locking mechanism in sequence. A hydraulic port E is opened on the side wall of the cylinder 2 corresponding to the self-locking mechanism and the isolation plate 5. A hydraulic port F is opened on the side wall of the cylinder 2 corresponding to the self-locking mechanism and the lower end cover 1. An installation guide rod M is fixedly installed on the outer side wall of the lower end cover 1.

[0026] The clamping head 12 is configured as a clamping head with a "C" shaped opening.

[0027] The lower wall of the clamping head 12 has an end cap assembly hole, and the inner surface of the lower wall of the clamping head 12 has a retaining nut groove around the end cap assembly hole. The upper end cap 9 has an extension end in the middle of its upper surface. The extension end extends into the end cap assembly hole and into the "C"-shaped interior of the clamping head 12. The extension end of the upper end cap 9 is connected to a retaining nut 11 by a threaded connection. The retaining nut 11 is locked in the retaining nut groove. The clamping head 12 and the upper end cap 9 are fixed by the retaining nut 11 being locked in the retaining nut groove and by the locking of the lower surface of the clamping head 12 and the upper surface of the upper end cap 9.

[0028] The upper clamping drive mechanism includes an upper piston 8 that is slidably connected to the inner wall of the cylinder 2 below the upper end cover 9 inside the cylinder 2. A clamping rod 10 is connected to the middle of the upper surface of the upper piston 8. The upper end of the clamping rod 10 passes through the upper end cover 9 and extends into the "C"-shaped interior of the clamping head 12. The clamping rod 10 is slidably connected to the upper end cover 9. A pressure sensor 13 is provided on the top of the clamping rod 10. A cavity a is formed between the upper surface of the upper piston 8, the clamping rod 10 and the lower surface of the upper end cover 9. A hydraulic port A is opened on the side wall of the cylinder 2 corresponding to the cavity a.

[0029] The lower clamping drive mechanism includes a lower piston 6 that is slidably connected to the inner wall of the cylinder 2 below the adaptive force balancing mechanism 7 inside the cylinder 2. A self-locking rod 4 is fixedly connected to the center of the lower surface of the lower piston 6. The lower end of the self-locking rod 4 passes through the isolation plate 5 and the self-locking mechanism in sequence.

[0030] The adaptive force balancing mechanism 7 consists of multiple sets of springs evenly arranged between the upper surface of the lower piston 6 and the lower surface of the upper piston 8, with the two ends of the springs fixed to the upper surface of the lower piston 6 and the lower surface of the upper piston 8, respectively.

[0031] The isolation plate 5 is connected to the inner wall of the cylinder 2 by a threaded connection. A cavity b is formed between the upper surface of the isolation plate 5, the self-locking rod 4, and the lower surface of the lower piston 6. A hydraulic port B is opened on the side wall of the cylinder 2 corresponding to the cavity b.

[0032] like Figures 2-4 As shown, the self-locking mechanism includes multiple locking sliders 3. The outer contour of each locking slider 3 is a conical surface, and the inner side is a cylindrical surface. Multiple locking sliders 3 are assembled to form a complete hollow frustum. The self-locking rod 4 passes through the hollow part of the hollow frustum. The outer diameter of the hollow frustum gradually decreases from top to bottom. The inner wall of the cylinder 2 corresponding to the hollow frustum is set as a conical surface that matches the hollow frustum. The upper and lower surfaces of the multiple locking sliders 3 are respectively provided with an upper push plate 22 and a lower push plate 24. The upper push plate 22 and the lower push plate 24 adapt to the inner wall of the cylinder 2 and slide up and down on the inner wall of the cylinder 2. The diameter of the upper push plate 22 is equal to the maximum diameter of the hollow frustum, and the diameter of the lower push plate 24 is equal to the minimum diameter of the hollow frustum. The upper push plate 22 and the lower push plate 24... Each locking slider 3 is provided with a T-slot 22-1 distributed radially therein. The upper and lower surfaces of each locking slider 3 have T-slots 3-1 corresponding to the T-slots 22-1. The T-slots 3-1 slide radially within the T-slots 22-1 along the upper push plate 22 and the lower push plate 24. A cavity e is formed between the upper surface of the upper push plate 22, the self-locking rod 4, the inner wall of the cylinder 2, and the lower surface of the isolation plate 5. The hydraulic port E is set on the side wall of the cylinder 2 corresponding to the cavity e. A cavity f is formed between the lower surface of the lower push plate 24, the self-locking rod 4, the inner wall of the cylinder 2, and the upper surface of the lower end cover 1. The hydraulic port F is set on the side wall of the cylinder 2 corresponding to the cavity f. The cone angle of the locking slider 3, that is, the self-locking angle, is γ. The locking slider 3 is made of deformable material.

[0033] The working principle of the self-locking mechanism is as follows:

[0034] The locking slider 3 is a split rotary structure, radially distributed around the self-locking rod 4, located between the upper push plate 22 and the lower push plate 24. Its outer contour is a conical surface, and its inner side is a cylindrical surface. The cross-section of a single slider is a wedge-shaped structure, which can move axially under the action of external force. The wedge angle γ is the self-locking angle. The upper and lower ends of the locking slider 3 are respectively inserted into the radial T-shaped grooves 22-1 in the upper push plate 22 and the lower push plate 24. It can move downward with the upper push plate 22 and upward with the lower push plate 24. When the locking slider 3 moves upward, it moves radially away from the self-locking rod 4. When the locking slider 3 moves downward, the outer conical surface moves downward along the conical surface L of the cylinder body 2 and moves radially closer to the self-locking rod 4.

[0035] A wear-resistant ring 14 and a seal I 15 are arranged sequentially from top to bottom between the upper end cover 9 and the clamping rod 10. A seal II 16 is arranged between the upper end cover 9 and the inner wall of the cylinder 2. A seal III 17 is arranged between the upper piston 8 and the inner wall of the cylinder 2. A seal IV 18 is arranged between the lower piston 6 and the inner wall of the cylinder 2. A seal V 19 and a seal VI 20 are arranged between the isolation plate 5, the self-locking rod 4, and the inner wall of the cylinder 2, respectively. A seal VII 21 and a seal VIII 23 are arranged between the upper push plate 22, the self-locking rod 4, and the inner wall of the cylinder 2, respectively. A seal X 26 and a seal IX 25 are arranged between the lower push plate 24, the self-locking rod 4, and the inner wall of the cylinder 2, respectively.

[0036] The working principle of the dual-cylinder clamping device in this embodiment is as follows:

[0037] This device should be used as a set, and the number used should not be less than two. Figure 5 As shown, after the two rigidly connected workpieces I and II are connected, the double hydraulic cylinder clamping device of the present invention is then installed. Figure 3 A pair of double-cylinder clamping devices are used. The two devices are placed on either side of the connection point between workpiece I and workpiece II. The mounting guide rod M is fixed to workpiece II, ensuring that the connection point between workpiece I and workpiece II is within the C-shape of the clamping head 12 and located between the upper end of the clamping rod 10 and the upper inner surface of the C-shape of the clamping head 12. The clamping operation is then performed. The end of the clamping head 12 furthest from the retaining nut 11 is the upper working plane during the clamping action. The specific clamping operation is as follows:

[0038] Clamping operation:

[0039] Hydraulic ports A, E, and F release pressure, and pressure is applied to cavity b through hydraulic port B, causing the lower piston 6 to drive the self-locking rod 4, the adaptive force balancing mechanism 7, the upper piston 8, and the clamping rod 10 to move to the upper limit position, clamping the connection between workpiece I and workpiece II. The feedback information from the pressure sensor 13 determines that the clamping force has reached the preset value, thus completing the clamping of workpiece I and workpiece II.

[0040] Then, pressure is applied to the cavity e through the hydraulic port E, such as... Figure 1 As shown, the upper push plate 22 and the locking slider 3 are pushed down to the lower limit position; during the movement of the locking slider 3 along the conical surface L of the cylinder body 2, it grips the outer contour surface K of the self-locking rod 4 and reaches the locked state; the self-locking angle γ ensures that the locking slider 3 always maintains the locked position when subjected to downward axial external load; thus, the locking of the clamping position is completed.

[0041] Next, hydraulic ports B and E are depressurized, disconnecting the hydraulic power source.

[0042] Off-center load adjustment:

[0043] When the workpiece I is subjected to bending moment load, the workpiece I and the workpiece II have a tendency to separate on one side. At this time, the spring force group of the adaptive force balance mechanism 7 under compression pushes the clamping rod 10 out, providing a continuous and stable clamping force, so that the workpiece I and the workpiece II are always in a reliable connection state.

[0044] Loosening operation:

[0045] By applying pressure to the cavity b through the hydraulic port B and applying pressure to the cavity f through the hydraulic port F, as shown in Figure 6 the lower push plate 24 and the locking slider 3 are pushed to move upwards to the upper limit position; during the movement of the locking slider 3 along the conical surface L of the cylinder body 2, the outer contour surface K of the self-locking rod 4 is loosened, and the unlocking state is reached. Thus, the unlocking of the clamping position is completed. The hydraulic port B is depressurized, and pressure is applied to the cavity a through the hydraulic port A, so that the upper piston 8 drives the clamping rod 10, the adaptive force balance mechanism 7, the lower piston 6 and the self-locking rod 4 to move to the lower limit position, the workpiece I and the workpiece II are loosened, and the loosening state is monitored through the digital display of the pressure sensor 13. Thus, the loosening of the workpiece I and the workpiece II is completed. The hydraulic port A and the hydraulic port F are depressurized, and the hydraulic source is disconnected.

[0046] Example 2

[0047] On the basis of example 1, the lower end cover 1 is a stepped structure, which is connected as a whole with the cylinder body 2 through threads, and the connection is welded.

[0048] Example 3

[0049] The upper end cover 9 is an L-shaped rotary body structure, which is connected as a whole with the cylinder body 2 through fastening screws at the lower part and has connecting threads at the upper part, and a wear-resistant ring 14 is installed inside.

[0050] The locking slider 3 is made of special material, which can be locally deformed under external force to generate friction force with the self-locking rod 4;

[0051] A seal can be added between the lower end cover 1 and the self-locking rod 4 to form a sealed cavity, which is connected with the sealed cavity b to increase the clamping force of the clamping driving mechanism.

[0052] The double-liquid-cylinder type clamping device of the present application is used for monitoring the clamping and connection state of the joint after the underwater installation and connection of underwater equipment such as underwater risers, riser pipes, submarine umbilical cables and production pipelines. The device is driven by hydraulic pressure, allowing remote and fully automatic operation, and is not limited by the water depth. It does not require divers or underwater robots for operation, reducing the cost and risk of underwater maintenance of underwater equipment. The clamping device can automatically adjust and absorb the force caused by changes in external load, improving the connection reliability and service life of underwater equipment. The device is a mechanical structure that can be used in harsh submarine environments and is reusable, reducing manufacturing and use costs. The self-locking mechanism of the device can maintain a constant clamping force without continuous energy supply throughout the life cycle once the clamping operation is completed. The device is versatile and suitable for a variety of underwater equipment such as underwater risers, riser pipes, submarine umbilical cables and production pipelines. By combining with various cylinder sizes and energy storage component spring capacities, it can meet the application requirements of specific underwater equipment clamping force.

[0053] The initial positioning and clamping of the double-liquid-cylinder type clamping device of the present application is achieved by driving the clamping drive mechanism with hydraulic pressure. When the clamping force is adjusted to the predetermined value, the self-locking mechanism is started to maintain the clamping position of the clamping drive mechanism. When the load of the clamped system changes, the self-adaptive force balancing mechanism can respond in time to provide a constant clamping force throughout the use of the clamping device, reducing the impact of load changes caused by wind and waves, water flow and mud surface collapse. The clamping drive mechanism and self-locking mechanism of the clamping device are both operated by hydraulic pressure, and only require energy supply during positioning and initial clamping. No energy supply or regular maintenance is required during use.

Claims

1. Double cylinder clamping device, characterized in that, The utility model provides a kind of clamping head (12) and the cylinder (2) being arranged below the clamping head (12), the upper end cover (9) and the lower end cover (1) are fixedly arranged on the cylinder (2) upper and lower ends respectively, the upper end cover (9) is fixedly connected with the lower end of the clamping head (12), the cylinder (2) is sequentially provided with upper clamping drive mechanism, self-adapting force balance mechanism (7), lower clamping drive mechanism, isolation plate (5), self-locking mechanism from top to bottom, the upper end of the upper clamping drive mechanism extends to the clamping head (12) inside through the upper end cover (9) and is slidably connected with the upper end cover (9), the lower end of the lower clamping drive mechanism sequentially passes through the isolation plate (5) and self-locking mechanism, the hydraulic port E is opened on the corresponding cylinder (2) side wall between the self-locking mechanism and isolation plate (5), the hydraulic port F is opened on the corresponding cylinder (2) side wall between the self-locking mechanism and lower end cover (1), the installation guide rod M is fixedly installed on the outer side wall of the lower end cover (1). The upper clamping drive mechanism includes the upper piston (8) that is slidably connected with the inner wall of the cylinder (2) below the upper end cover (9) in the cylinder (2). The lower clamping drive mechanism includes the lower piston (6) that is slidably connected with the inner wall of the cylinder (2) below the self-adapting force balance mechanism (7) in the cylinder (2). The self-adapting force balance mechanism (7) is a plurality of springs evenly arranged between the upper surface of the lower piston (6) and the lower surface of the upper piston (8), and the two ends of the spring are fixed on the upper surface of the lower piston (6) and the lower surface of the upper piston (8) respectively.

2. The dual fluid cylinder clamp device according to claim 1, characterized by The clamping head (12) is provided as a clamping head with a "C" shaped opening.

3. The dual fluid cylinder clamp device of claim 2, wherein The lower wall of the clamping head (12) is provided with a cover assembly hole, and the inner surface of the lower wall of the clamping head (12) is provided with a retaining nut clamping groove around the cover assembly hole. The upper surface of the upper end cover (9) is provided with an extension end, which extends into the cover assembly hole and extends into the inside of the "C" shape of the clamping head (12). The extension end of the upper end cover (9) is connected with a retaining nut (11) by a threaded connection. The retaining nut (11) is clamped in the retaining nut clamping groove. The clamping head (12) and the upper end cover (9) are fixed by clamping the retaining nut (11) in the retaining nut clamping groove and clamping the clamping head (12) and the upper end cover (9) on the lower surface of the clamping head (12) and the upper surface of the upper end cover (9).

4. The dual fluid cylinder clamp of claim 2, wherein, The upper surface of the upper piston (8) is connected with a clamping rod (10), the upper end of the clamping rod (10) extends into the "C" shaped inside of the clamping head (12) after passing through the upper end cover (9), the clamping rod (10) is slidably connected with the upper end cover (9), the clamping rod (10) is provided with a pressure sensor (13) on the top, and the upper surface of the upper piston (8), the clamping rod (10) and the lower surface of the upper end cover (9) form a cavity a, and the corresponding side wall of the cylinder (2) of the cavity a is provided with a hydraulic port A.

5. The dual fluid cylinder clamp of claim 4, wherein, The lower surface of the lower piston (6) is fixedly connected with a self-locking rod (4), and the lower end of the self-locking rod (4) sequentially passes through the isolation plate (5) and the self-locking mechanism.

6. The dual fluid cylinder clamp device of claim 5, wherein, The isolation plate (5) is connected with the inner wall of the cylinder body (2) by threaded connection, the upper surface of the isolation plate (5), the self-locking rod (4) and the lower surface of the lower piston (6) form a cavity b, and the corresponding side wall of the cylinder body (2) is provided with a hydraulic port B.

7. The dual fluid cylinder clamp device of claim 6, wherein The self-locking mechanism comprises a plurality of locking sliders (3), the outer side profile of the locking slider (3) is a conical surface, the inner side of the locking slider (3) is a cylindrical surface, a plurality of the locking sliders (3) are spliced into a complete hollow circular truncated cone body, the self-locking rod (4) passes through the hollow part of the hollow circular truncated cone body, the outer diameter of the hollow circular truncated cone body gradually decreases from top to bottom, the inner wall of the cylinder body (2) corresponding to the hollow circular truncated cone body is provided as a conical surface matched with the hollow circular truncated cone body, the upper surface and the lower surface of the plurality of locking sliders (3) are respectively provided with an upper push plate (22) and a lower push plate (24), the upper push plate (22) and the lower push plate (24) are adapted to the inner wall of the cylinder body (2) and slide up and down on the inner wall of the cylinder body (2), the diameter of the upper push plate (22) is equal to the maximum diameter of the hollow circular truncated cone body, the diameter of the lower push plate (24) is equal to the minimum diameter of the hollow circular truncated cone body, the upper push plate (22) and the lower push plate (24) are provided with T-shaped grooves (22-1) distributed along the radial direction at positions corresponding to each of the locking sliders (3), the upper surface and the lower surface of each of the locking sliders (3) are provided with T-shaped sliders (3-1) corresponding to the T-shaped grooves (22-1), and the T-shaped sliders (3-1) slide in the T-shaped grooves (22-1) in the radial direction of the upper push plate (22) and the lower push plate (24); the upper surface of the upper push plate (22), the self-locking rod (4), the inner wall of the cylinder body (2) and the lower surface of the isolation plate (5) form a cavity e, the hydraulic port E is arranged on the side wall of the cylinder body (2) corresponding to the cavity e, the lower surface of the lower push plate (24), the self-locking rod (4), the inner wall of the cylinder body (2) and the upper surface of the lower end cover (1) form a cavity f, and the hydraulic port F is arranged on the side wall of the cylinder body (2) corresponding to the cavity f, the included angle of the conical surface of the locking slider (3) is the self-locking angle γ, and the locking slider (3) is made of a deformable material.

8. The dual fluid cylinder clamp of claim 7, wherein, The upper end cover (9) and the clamping rod (10) are sequentially provided with a wear-resistant ring (14) and a seal I (15) from top to bottom, the upper end cover (9) and the inner wall of the cylinder body (2) are provided with a seal II (16), the upper piston (8) and the inner wall of the cylinder body (2) are provided with a seal III (17), the lower piston (6) and the inner wall of the cylinder body (2) are provided with a seal IV (18), the isolation plate (5) and the self-locking rod (4) and the inner wall of the cylinder body (2) are respectively provided with a seal V (19) and a seal VI (20), the upper push plate (22) and the self-locking rod (4) and the inner wall of the cylinder body (2) are respectively provided with a seal VII (21) and a seal VIII (23), and the lower push plate (24) and the self-locking rod (4) and the inner wall of the cylinder body (2) are respectively provided with a seal X (26) and a seal IX (25).

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