A lifting assembly integrity device and a method for calculating a slot angle of a plastic hinge

Abstract

The present application belongs to the technical field of electro-hydraulic servo actuator assembly, and relates to a device for improving assembly integrity and a method for calculating the groove angle of a plastic hinge. The device for improving assembly integrity comprises a through collar groove protection sleeve, a through pin groove protection sleeve and a piston assembly assembly device. The piston assembly assembly device comprises a screw feed system, an ear ring joint and two sets of cylinder body fixing seats. The screw feed system and the cylinder body fixing seats are installed on a fixed table top. The ear ring joint is connected to the output end of the screw feed system and moves linearly along the axis of the screw feed system. The ear ring joint is connected to the actuator cylinder piston assembly through a pin. The cylinder body assembly is installed on the cylinder body fixing seat. The through collar groove protection sleeve is fixedly attached to the collar groove near the inlet of the cylinder body. The through pin groove protection sleeve is installed in the pin groove of the cylinder body. The pin block installation window of the cylinder body is also used to extract the through pin groove protection sleeve.

Description

Technical Field

[0001] This invention belongs to the field of electro-hydraulic servo actuator assembly technology, and relates to a device for improving assembly integrity and a method for calculating the angle of plastic hinge slotting. Background Technology

[0002] As advanced fighter jets expand their flight envelopes and demand higher maneuverability, the required output force and stroke of main control surface actuators are also increasing. Electro-hydraulic servo actuators, which control load movement by consuming hydraulic energy, are the execution components of flight control systems, offering advantages such as stable performance, long lifespan, high reliability, and a high power-to-weight ratio. Actuators serve as both the drive and support mechanisms for control surfaces, making them crucial for flight safety. However, as electro-hydraulic servo actuators use hydraulic oil as their working medium, persistent problems such as leaks and drips severely impact their performance and reliability.

[0003] For large hydraulic actuators with high output force and long stroke, a dual-chamber tandem structure is often used. A separator bushing is installed in the middle of the cylinder and fixed with a cylindrical pin, while the front of the cylinder is fixed to the outer bushing with a retaining ring. The presence of the pin groove and retaining ring groove makes the inner bore of the cylinder no longer smooth and continuous. When the piston head seal passes through the pin groove and retaining ring groove, it expands and becomes larger, making it very easy to be scratched by the edge of the inner bore, leading to seal damage and the generation of foreign objects. At the same time, seal damage is difficult to detect, excess foreign objects are not easily detected, and scratches on the inner bore cannot be exposed in the short term. All of these have unpredictable and fatal impacts on flight safety.

[0004] Currently, users have a "zero tolerance" attitude towards oil leakage from the seals of large hydraulic actuators. However, there are no effective measures to detect and control seal damage during the assembly process. Therefore, there is an urgent need for a device and method to improve the assembly integrity of seals in large hydraulic actuators. Summary of the Invention

[0005] The purpose of this invention is to provide a device and method for improving the integrity of the seal assembly of large hydraulic redundant actuators with an output force exceeding 200kN and a stroke exceeding 130mm. This invention has the functions of preventing seal damage during installation and detecting damage, and can significantly improve the success rate of the actuator assembly in one go.

[0006] Technical solution:

[0007] Firstly, a device for improving assembly integrity is proposed, which is applied to large hydraulic actuator cylinder seals. The device for improving assembly integrity includes: a protective sleeve for passing through the retaining ring groove, a protective sleeve for passing through the pin groove, and a piston assembly assembly device.

[0008] The piston assembly assembly includes a lead screw feed system, an eyelet connector, and two sets of cylinder mounting bases;

[0009] The lead screw feed system and the cylinder mounting base are mounted on a fixed platform. The clevis joint is connected to the output end of the lead screw feed system and moves linearly along the axis of the lead screw feed system. The clevis joint is connected to the piston assembly of the actuator cylinder through a pin. The cylinder assembly is mounted on the cylinder mounting base and the piston assembly and the cylinder assembly are at the same height along their axes. The piston assembly can move linearly along the axis of the cylinder assembly.

[0010] The retaining ring groove protective sleeve is fixedly attached to the retaining ring groove inside the cylinder near the inlet;

[0011] The through-pin groove protective sleeve is installed at the pin groove inside the cylinder, and the pin stop block installation window of the cylinder is also used to remove the through-pin groove protective sleeve.

[0012] Furthermore, the piston assembly assembly device also includes a force sensor, which is mounted on the earring connector and can provide real-time feedback on the installation force applied to the piston assembly.

[0013] Furthermore, the protective sleeve for the retaining ring groove adopts a two-part split structure, and lubricant should be applied before installation.

[0014] Furthermore, the protective sleeve for the through-column pin groove also adopts a two-part split structure, and the node position of the protective sleeve is designed with a wedge-shaped groove, so that the protective sleeve changes from a ring shape to a strip shape when it is taken out, making it easy to pull out from a narrow window.

[0015] Furthermore, the protective sleeve for the through-pin groove, which is a T-shaped cross-section open ring, needs to form a deformable structure and be removed from the actuating cylinder pin window, requiring at least three hinge points.

[0016] Furthermore, the lead screw feed system includes a motor, coupling, lead screw, nut, support bearing, guide rail, and slider;

[0017] The guide rail and the cylinder fixing seat are installed on the same plane; the lead screw is installed on the frame through front and rear support bearings and rotates around the bearing axis; the motor is fixed on the worktable and connected to the lead screw through the coupling; the nut is the output end of the lead screw and is connected to the lug connector to convert the rotational motion of the lead screw into axial movement; at the same time, the lug connector is connected to the guide rail through the slider to eliminate side load.

[0018] Furthermore, the protective sleeve for the through pin groove is designed with a wedge-shaped groove with an included angle of 90° and a depth of 2.5mm at 90° intervals. The width of the T-shaped head of the protective sleeve is consistent with the cylindrical pin of the actuator cylinder separator bushing of this type, and the thickness is half the depth of the through pin groove inside the cylinder. The width and depth of the T-shaped tail of the protective sleeve are both half the width and depth of the through pin groove of this type of actuator cylinder.

[0019] Furthermore, the raw materials for the protective sleeves for the retaining ring groove and the protective sleeves for the pin groove are both polytetrafluoroethylene plastic that matches the modulus of the seal.

[0020] Secondly, a method for calculating the slotting angle of a plastic hinge is provided, specifically for a protective sleeve with a through-pin groove. This method includes:

[0021] During the process of pulling the protective sleeve through the pin groove from the pin stop installation window of the cylinder, the upper semi-circular ring was taken for stress analysis.

[0022] Based on the force analysis and the principle of torque balance, the plastic hinge slot angle is calculated.

[0023] Furthermore, the calculation equation for the plastic hinge slot angle is:

[0024] M1(θ0)=M2(θ0)=-M p ;

[0025]

[0026] F N =F y ;

[0027]

[0028]

[0029]

[0030] Among them, M p The torque at point A, θ is the angle between the upper end of the cylindrical window and the central axis; θ is from 0 to... The angles are M1(θ) and M2(θ). M1(θ) is the moment of the arc segment corresponding to angle 0 to θ. The arc segment torque corresponding to the angle; θ0 is the angle corresponding to the position of the plastic hinge slot; P is the pulling force; R is the inner control radius of the protective sleeve through the pin groove; F x It is the lateral force F exerted by the cylinder on the protective sleeve of the through-column pin groove. y F represents the longitudinal force exerted by the cylinder on the protective sleeve of the through-column pin groove. N It is the internal force of the protective sleeve of the column pin groove.

[0031] Beneficial effects:

[0032] This invention provides a device and method for improving the assembly integrity of seals in large hydraulic actuators. It controls dimensional accuracy at the design and manufacturing stage of the parts to prevent uneven wear under lateral loads on the large actuators. Before component installation, a visual quality inspection is performed to avoid introducing burrs and abrasive particles. During assembly, protective sleeves through the retaining ring groove and the pin groove effectively prevent the seals from expanding and being damaged by compression. Simultaneously, the piston assembly installation device ensures coaxiality during assembly and provides real-time feedback on assembly force to determine if the seals are damaged. This reduces the impact of human factors in the assembly of large actuators, significantly improving the first-time assembly success rate. Furthermore, it avoids frequent replacement of damaged seals, greatly reducing costs and saving assembly time. It has been adopted in the development of several key models with good results. Attached Figure Description

[0033] Figure 1 This invention provides a structural diagram of a device for improving the assembly integrity of seals in large hydraulic actuators;

[0034] Figure 2 This is a schematic diagram of the lead screw feeding system in a device for improving the assembly integrity of seals in a large hydraulic actuator according to the present invention;

[0035] Figure 3a This is a side view of the protective sleeve through the retaining ring groove in Example 1;

[0036] Figure 3b This is a front view of the protective sleeve through the retaining ring groove in Example 1.

[0037] Figure 4a This is a side view of the protective sleeve for the through-column pin groove in Example 1;

[0038] Figure 4b This is a front view of the protective sleeve for the through-column pin groove in Example 1;

[0039] Figure 5 This is a schematic diagram of the through-column pin groove protection kit for Example 1;

[0040] Figure 6 This is a schematic diagram of the protective kit for the circlip groove in Example 1;

[0041] Figure 7 This is a schematic diagram of the actuator cylinder assembly in Example 1;

[0042] Figure 8 This is a force analysis diagram.

[0043] Wherein: 1-lead screw feed system, 2-force sensor, 3-ear ring connector, 4-cylinder fixing seat; 201-motor, 202-coupling, 203-support bearing, 204-lead screw, 205-lead screw nut, 206-guide rail, 207-slider, 208-ear ring connector. Detailed Implementation

[0044] In practical applications, the specifications, dimensions, and structural details of different hydraulic actuators vary. First, when designing the parts in the drawings, stricter tolerances are imposed on relevant features, including coaxiality, cylindricity, runout, surface finish, and perpendicularity. Rounding and polishing are also required for sharp edges of the parts. Second, based on the characteristic dimensions of the retaining ring groove and pin groove inside different actuators, corresponding protective sleeves for the retaining ring groove and pin groove are designed. Third, before assembly, the appearance of the seals and the parts are inspected for burrs and surface defects as required. Finally, after fixing the actuator body, applying grease, and installing the protective sleeves for the retaining ring groove and pin groove, the actuator is assembled using a piston assembly device. During assembly, the installation force is observed; if there is a sudden change, the piston assembly should be pushed out, and the seals should be carefully inspected for damage.

[0045] The present invention will be further described below with reference to embodiments.

[0046] This invention provides a device for improving assembly integrity, comprising a retaining ring groove protective sleeve, a pin groove protective sleeve, and a piston assembly assembly device. The retaining ring groove protective sleeve is made of polytetrafluoroethylene (PTFE), whose elastic modulus is comparable to that of the sealing material, preventing excessive deformation and increased friction after the sealing material is squeezed into contact. For easy disassembly, the retaining ring groove protective sleeve adopts a two-part split structure, and lubricant is applied before installation.

[0047] The protective sleeve for the through-pin groove is also made of polytetrafluoroethylene (PTFE). Before installation, lubricant is applied to the protective sleeve to secure it to the pin groove. Because the pin groove is located in the middle of the cylinder, the protective sleeve cannot be removed from the inner orifice of the cylinder after piston installation. To solve this problem, the through-pin groove protective sleeve adopts a two-part split structure. After the piston head seal passes through the pin groove, the protective sleeve is pulled out from the pin stop installation window in the cylinder. A wedge-shaped groove is designed at the joint of the protective sleeve, changing the shape from a ring to a strip when removed, facilitating extraction from the narrow window.

[0048] The protective sleeve through the pin groove is a T-shaped open circular ring. To form a deformable structure and be removed from the pin window of the actuating cylinder, at least three hinge points are required. Its force analysis is shown in the figure. Applying the momentum theorem in the horizontal direction, the acceleration of the ring's center of mass is...

[0049]

[0050] ρ is the density of the material of the protective sleeve through the pin groove, P is the tensile force, R is the inner radius of the protective sleeve through the pin groove, and F is the tensile force. x It is the lateral force exerted by the cylinder on the protective sleeve of the through-column pin groove.

[0051] Considering symmetry, let's analyze the upper semicircular ring as follows: Figure 8 As shown, the upper semicircular ring is subjected to a circumferential axial force F from the lower semicircular ring at point A.N The effect of the plastic hinge at point A, and the bending moment at point A. Point A is the point of contact with the window of the cylinder during extraction. For the small infinitesimal element Rdθ on the annulus, its inertial force is...

[0052]

[0053] Based on the force analysis diagram of the upper semicircular ring, the moment balance equation for point A is:

[0054]

[0055]

[0056] Where Mp is the torque at point A, The angle between the upper end of the cylinder window and the central axis; Fy is the longitudinal force exerted by the cylinder on the protective sleeve of the through-column pin groove;

[0057] Analyzing the force equilibrium of a segment of the circular arc corresponding to angle θ, we have:

[0058]

[0059]

[0060] F N It is the internal force of the protective sleeve of the through-column pin groove; M1(θ) is the integral variable of the arc segment θ; M1(θ) is the torque of the arc segment θ.

[0061] Analyzing the force balance of the remaining arc, we have:

[0062]

[0063]

[0064] M2(θ) is the torque of the remaining arc segment outside the θ-segment arc;

[0065] If the angle corresponding to the position C of the plastic hinge slot is θ0, then we have

[0066] M1(θ0)=M2(θ0)=-M p ;

[0067]

[0068] F N =F y ;

[0069] Solving the system of equations simultaneously yields θ0.

[0070] The shape and positioning dimensions of the protective sleeves for the retaining ring groove and the pin groove are determined according to the corresponding position dimensions of the actuator cylinder. This ensures that the protective sleeves can completely fill the retaining ring groove and the pin groove after installation, preventing the seals from expanding when passing through the grooves and being sheared and damaged by the edge of the inner hole of the cylinder.

[0071] The piston assembly assembly device includes a lead screw feed system 1, a force sensor 2, an earpiece connector 3, and a cylinder fixing seat 4, such as Figure 1 As shown. The lead screw feed system and the cylinder mounting base are mounted on a fixed platform. The clevis joint is connected to the output end of the lead screw, and the clevis joint moves linearly along the lead screw axis. The clevis joint is connected to the actuator piston assembly via a pin. The cylinder assembly is mounted on the cylinder mounting base, and the piston assembly and cylinder assembly have the same axis height, allowing the piston assembly to move linearly along the cylinder assembly axis. The force sensor is mounted on the clevis joint and can provide real-time feedback on the installation force applied to the piston assembly. When the seal is damaged, the frictional force changes, and the force sensor reading will change abruptly, which can be used to determine whether the seal was damaged during assembly.

[0072] The lead screw feed system includes a motor 201, a coupling 202, a lead screw 204, a lead screw nut 205, a support bearing 203, a guide rail 206, and a slider 207, such as... Figure 2 As shown, the guide rail and the cylinder mounting base are installed on the same plane. The lead screw is mounted on the frame via front and rear support bearings and rotates around the bearing axis. The motor is fixed on the worktable and connected to the lead screw via the coupling. The nut is the output end of the lead screw and is connected to the clevis joint, converting the rotational motion of the lead screw into axial movement. Simultaneously, the clevis joint is connected to the guide rail via a slider to eliminate side loads.

[0073] The component design precision control method targets key components of the actuator, such as bushings, sleeves, pistons, and cylinders. To prevent lateral wear from damaging the seals, stricter requirements are imposed on the cylindricity and runout of the outer surfaces of sleeves, pistons, and bushings; stricter requirements on the coaxiality of the mounting holes in the cylinder and the inner holes of the bushings; and stricter requirements on the perpendicularity of the end faces of each component's vertical axis. To prevent sharp edges of components from scratching the seals, uniform rounding and polishing requirements are also proposed for the sharp edges of components.

[0074] There are three main methods for inspecting the appearance quality of components before assembly. First, the appearance of the seals: the rubber elastomer should be smooth and flat, free from pores, impurities, cracks, bubbles, scratches, and axial flow marks; the sealing ring should be smooth and uniform in color, free from impurities, cracks, defects, bubbles, dents, and other defects. Second, the sealing surfaces and burrs of the bushings and piston heads should be inspected: there should be no burrs, rust, scratches, indentations, dents, or other external defects. Third, the surface defects of the sleeves and pistons should be inspected: the threads should be free from dents, stripping, deformation, and other defects, and the chrome plating should be free from obvious defects. The method for inspecting the appearance quality of components after assembly mainly involves using an endoscope to check the installation status of the seals after the actuator cylinder is assembled. The rubber rings should be intact, free from damage, defects, and misalignment, and free from excess material caused by cuts to the retaining ring.

[0075] In practical applications, the specifications, dimensions, and structural details of different hydraulic actuators vary. First, when designing the parts in the drawings, stricter tolerances are imposed on relevant features, including coaxiality, cylindricity, runout, surface finish, and perpendicularity. Rounding and polishing are also required for sharp edges of the parts. Second, based on the characteristic dimensions of the retaining ring groove and pin groove inside different actuators, corresponding protective sleeves for the retaining ring groove and pin groove are designed. Third, before assembly, the appearance of the seals and the parts are inspected for burrs and surface defects as required. Finally, after fixing the actuator body, applying grease, and installing the protective sleeves for the retaining ring groove and pin groove, the actuator is assembled using a piston assembly device. During assembly, the installation force is observed; if there is a sudden change, the piston assembly should be pushed out, and the seals should be carefully inspected for damage.

[0076] The present invention will be further described below with reference to embodiments.

[0077] Example 1:

[0078] For a certain type of high-output force dual-chamber series hydraulic actuator, during the design phase, the following accuracy requirements for key sealing dimensions of related parts were added: the cylindricity of the piston, sleeve and other parts should be 0.02, the coaxiality of the hole between the cylinder and the sleeve should be 0.01, the perpendicularity of the bushing groove end face should be 0.01, the runout of the bushing outer surface should be 0.01, and the sharp edges of the parts should be rounded to R0.5 and polished to a surface finish of 2.5.

[0079] Based on the dimensions of the retaining ring groove in the cylinder, a retaining ring groove protective sleeve was designed, with the structure as follows: Figures 3a-3b As shown. The cross-sectional shape of the protective sleeve through the retaining ring groove is semi-circular, with a radius consistent with the radius of the retaining ring of this type of actuator; the inner diameter of the protective sleeve is consistent with the inner diameter of the actuator. Based on the dimensions of the cylinder pin groove, the protective sleeve through the pin groove is designed, with the structure as shown. Figures 4a-4bAs shown. For easy removal, the protective sleeve for the through-pin groove has a T-shaped cross-section, with wedge-shaped grooves of 90° angle and 2.5mm depth designed at 90° intervals. The width of the T-shaped head of the protective sleeve is consistent with the cylindrical pin of the actuator cylinder separator bushing of this type, and the thickness is half the depth of the through-pin groove inside the cylinder. The width and depth of the T-shaped tail of the protective sleeve are both half the width and depth of the through-pin groove of this type of actuator cylinder. The raw materials for both the through-ring groove protective sleeve and the through-pin groove protective sleeve are polytetrafluoroethylene plastic that matches the modulus of the sealing element.

[0080] Before assembling this type of actuator, first inspect the appearance quality of the seals. The rubber elastomer should be smooth and flat, free from pores, impurities, cracks, bubbles, scratches, and axial flow marks. The sealing ring should be smooth and uniform in color, free from impurities, cracks, defects, bubbles, dents, and other defects. Next, inspect the end face of the bushing and piston head sealing groove, ensuring there are no burrs, rust, scratches, indentations, dents, or other external defects. Finally, inspect the surface quality of the sleeve and piston; the chrome plating should be free from obvious defects.

[0081] When assembling this type of actuator, first fix the cylinder body to the cylinder body fixing seat of the piston assembly assembly device. Pay attention to adjusting the position of the fixing seat to avoid the oil passage connection surface, ensuring the cylinder body axis is parallel to the fixing platform surface and does not move. Apply grease evenly to the cylinder body's pin groove, then insert the pin groove protective sleeve into the cylinder's inner hole, placing it tightly against the pin groove, ensuring the inner hole of the protective sleeve is flush with the inner hole of the actuator cylinder. Figure 5 As shown. Next, evenly apply grease to the inside of the retaining ring groove on the cylinder body. Place the protective sleeve over the retaining ring groove tightly against the retaining ring groove, flush with the inner hole of the cylinder, as shown. Figure 6 As shown.

[0082] Connect the piston assembly to the earring connector via a pivot pin, such as Figure 7 As shown. After ensuring the cylinder and piston assembly are securely installed, use a handheld pressure sprayer to draw aviation hydraulic oil and thoroughly wet the inside of the cylinder assembly, or apply hydraulic oil directly to the cylinder port. Control the lead screw feed system, first slowly pushing the large end of the piston assembly into the cylinder, observing the shape of the seal as it passes through the cylinder orifice. After ensuring the seal is not damaged, continue to slowly push the piston assembly into the cylinder while controlling the motor to drive the lead screw, observing the force sensor reading. If the force sensor reading changes abruptly, remove the piston and check for scratches or damage to the piston ring. After confirming everything is correct, reassemble to ensure assembly quality. After the piston assembly and cylinder are assembled, use an endoscope to check the installation status of the actuator cylinder seal, confirming that the piston ring is intact, without damage, defects, or misalignment, and without any excess material caused by cuts to the retaining ring.

[0083] Example 2:

[0084] For another type of high-output dual-chamber series hydraulic actuator, during the design phase, the following accuracy requirements for key sealing dimensions of related parts are added: the cylindricity of the piston, sleeve and other parts is required to be 0.02; the coaxiality of the hole between the cylinder and the sleeve is required to be 0.01; the perpendicularity of the bushing groove end face is required to be 0.01; the runout of the bushing outer surface is required to be 0.01; and the sharp edges of the parts are required to be rounded to R0.5 and polished to a surface finish of 2.5.

[0085] The diameter of the retaining ring groove of this type of cylinder is 104.6mm, the diameter of the ball is 6mm, and the design features a semi-circular cross-section protective sleeve for the retaining ring groove with a radius of 3mm and an inner diameter of 104.6mm. The length of the cylinder pin groove is 10mm, the depth is 5mm, and the diameter is 104.6mm. A T-shaped cross-section protective sleeve for the pin groove is designed, with a T-shaped head width of 10mm and a thickness of 2.5mm, and a T-shaped tail width of 5mm and a thickness of 2.5mm. Wedge-shaped grooves with an included angle of 90° and a depth of 2.5mm are designed at 90° intervals. Both the retaining ring groove protective sleeve and the pin groove protective sleeve are made of polytetrafluoroethylene (PTFE).

[0086] Before assembling this type of actuator, first inspect the appearance quality of the seals. The rubber elastomer should be smooth and flat, free from pores, impurities, cracks, bubbles, scratches, and axial flow marks. The sealing ring should be smooth and uniform in color, free from impurities, cracks, defects, bubbles, dents, and other defects. Next, inspect the end face of the bushing and piston head sealing groove, ensuring there are no burrs, rust, scratches, indentations, dents, or other external defects. Finally, inspect the surface quality of the sleeve and piston; the chrome plating should be free from obvious defects.

[0087] When assembling this type of actuator, first fix the cylinder body to the cylinder body fixing seat of the piston assembly device. Pay attention to adjusting the position of the fixing seat to avoid the oil passage connection surface, ensuring the cylinder body axis is parallel to the fixing platform surface and does not move. Apply grease evenly to the cylinder body's pin groove, then insert the pin groove protective sleeve into the cylinder's inner hole, placing it tightly against the pin groove, ensuring the inner hole of the protective sleeve is flush with the inner hole of the actuator cylinder. Next, apply grease evenly to the cylinder body's retaining ring groove, placing the retaining ring groove protective sleeve tightly against the retaining ring groove, flush with the inner hole of the cylinder.

[0088] After ensuring the cylinder and piston assembly are securely installed, use a hand-held pressure sprayer to draw aviation hydraulic oil and thoroughly wet the inside of the cylinder assembly, or apply hydraulic oil directly to the cylinder port. Connect the piston assembly to the lug connector via a pin. Control the screw feed system and slowly push the large end of the piston assembly into the cylinder, observing the shape of the seal as it passes through the cylinder orifice. After ensuring the seal is not damaged, continue to slowly push the piston assembly into the cylinder while controlling the motor to drive the screw, observing the force sensor reading. If the force sensor reading changes abruptly, remove the piston and inspect the piston ring for scratches or damage. After confirming everything is correct, reassemble to ensure assembly quality. After the piston assembly and cylinder are assembled, use an endoscope to inspect the actuating cylinder seal installation status, confirming that the rubber ring is intact, without damage, defects, or misalignment, and without any excess material caused by cuts to the retaining ring.

Claims

1. A device for improving assembly integrity, characterized in that, This lifting assembly integrity device, applied to large hydraulic actuator cylinder seals, includes: a protective sleeve for passing the retaining ring groove, a protective sleeve for passing the pin groove, and a piston assembly assembly device. The piston assembly assembly includes a lead screw feed system, an eyelet connector, and two sets of cylinder mounting bases; The lead screw feed system and the cylinder mounting base are mounted on a fixed platform. The clevis joint is connected to the output end of the lead screw feed system and moves linearly along the axis of the lead screw feed system. The clevis joint is connected to the piston assembly of the actuator cylinder through a pin. The cylinder assembly is mounted on the cylinder mounting base and the piston assembly is at the same height as the cylinder assembly axis. The piston assembly can move linearly along the axis of the cylinder assembly. The retaining ring groove protective sleeve is fixedly attached to the retaining ring groove inside the cylinder near the inlet; The through-pin groove protective sleeve is installed at the pin groove inside the cylinder, and the pin stop block installation window of the cylinder is also used to pull out the through-pin groove protective sleeve. The piston assembly assembly device is characterized by further including a force sensor, which is installed on the earring connector and can provide real-time feedback on the installation force applied to the piston assembly; The retaining ring groove protective sleeve adopts a two-part split structure. Apply lubricant before installation. The protective sleeve for the through-column pin groove also adopts a two-part split structure. The protective sleeve is designed with wedge-shaped grooves at the node positions, so that the protective sleeve changes from a ring shape to a strip shape when it is taken out, making it easy to pull out from a narrow window. The protective sleeve for the through-pin groove is a T-shaped open ring that needs to form a deformable structure. To be removed from the actuating cylinder pin window, at least three hinge points are required.

2. The device for improving assembly integrity according to claim 1, characterized in that, The lead screw feed system includes a motor, coupling, lead screw, nut, support bearing, guide rail, and slider; The guide rail and the cylinder fixing seat are installed on the same plane; the lead screw is installed on the frame through front and rear support bearings and rotates around the bearing axis; the motor is fixed on the worktable and connected to the lead screw through the coupling; the nut is the output end of the lead screw and is connected to the lug connector to convert the rotational motion of the lead screw into axial movement; at the same time, the lug connector is connected to the guide rail through the slider to eliminate side load.

3. The device for improving assembly integrity according to claim 2, characterized in that, The protective sleeve for the through pin groove is designed with a wedge-shaped groove with an included angle of 90 degrees and a depth of 2.5mm at every 90-degree interval. The width of the T-shaped head of the protective sleeve is consistent with the cylindrical pin of the actuator cylinder separator bushing, and the thickness is half the depth of the through pin groove inside the cylinder. The width and depth of the T-shaped tail of the protective sleeve are both half the width and depth of the through pin groove of the actuator cylinder.

4. The device for improving assembly integrity according to claim 1, characterized in that, The raw materials for the protective sleeves for the retaining ring groove and the protective sleeves for the pin groove are both polytetrafluoroethylene plastic that matches the modulus of the seal.

5. A method for calculating the angle of a plastic hinge slot, characterized in that, The method for the through-pin groove protective sleeve according to any one of claims 1-4 includes: During the process of pulling the protective sleeve through the pin groove from the pin stop installation window of the cylinder, the upper semi-circular ring was taken for stress analysis. Based on the force analysis and the principle of torque balance, the plastic hinge slot angle is calculated.

6. The method according to claim 5, characterized in that, The equation for calculating the angle of a plastic hinge slot is: ； ； ； ； ； ； in, M p The torque at point A, The angle between the upper end of the cylinder window and the central axis; From 0 to Angle, M 1 ( ) From 0 to The torque of the arc segment corresponding to the angle, M 2 ( ) for to The torque of the arc segment corresponding to the angle; The angle corresponding to the position of the slot in the plastic hinge; P It is the pulling force. R It is the inner control radius of the protective sleeve for the through-column pin groove. F x It is the lateral force exerted by the cylinder on the protective sleeve of the through-column pin groove. F y This refers to the longitudinal force exerted by the cylinder on the protective sleeve of the through-column pin groove. F N It is the internal force of the protective sleeve of the column pin groove.

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