A circumferential spinning self-locking type marine flexible pipe quick-mount bend limiter

Abstract

The application discloses a circumferential spinning self-locking type marine flexible pipe fast-mounting bending limiter, and belongs to the technical field of marine flexible pipe protection. The C-shaped hoop body is an open elastic structure and can be laterally clamped on the flexible pipe; the inner wall is provided with a linear gradually-changing wedge-shaped spiral convex surface which is matched with a spiral groove of a meshing limiting ring surface; and the axially extended ends are provided with mutually matched one-way anti-falling inverted teeth. The outer wall of the C-shaped hoop body is provided with a linear wedge-shaped spiral convex surface, the inner wall of the spinning locking ring is provided with a matched wedge-shaped spiral groove, and the spiral lift angle is less than or equal to 10 degrees. The circumferential spinning locking ring produces a radial extrusion force on the C-shaped hoop body to make the C-shaped hoop body contract and the inverted teeth mesh, so that double self-locking is realized. The application does not need bolts, is fast to mount, is reliable in locking, is uniform in stress, is suitable for complex marine working conditions, can effectively limit the excessive bending of the flexible pipe, and prolongs the service life of the flexible pipe.

Description

Technical Field

[0001] This invention belongs to the field of marine flexible pipe protection technology, specifically relating to a circumferentially spun self-locking quick-install bending limiter for marine flexible pipes. Background Technology

[0002] Marine flexible pipes are widely used in marine oil and gas development, submarine pipeline laying and other scenarios. In the marine environment, they are subject to external forces such as waves, currents and ship movement, which can easily cause excessive bending, leading to pipe damage, leakage and other safety hazards. Therefore, it is necessary to install bending limiters at key parts of the flexible pipe to limit its bending angle, protect the pipe body and extend its service life.

[0003] Existing marine flexible tube bending limiters mainly suffer from the following technical contradictions: 1. Rigid pre-set bend limiters (such as integral sleeves): These must be inserted from the pipe end and cannot be installed in the middle of a completed pipeline. They also have stringent requirements on the diameter tolerance of the flexible pipe. In actual manufacturing and use, the outer diameter of marine flexible pipes fluctuates within a tolerance range of ±3% to 5%. Furthermore, after long-term service, internal pressure and temperature changes can cause creep expansion or contraction, resulting in either the rigid pre-set limiter failing to fit or, if fitted, having an excessively large gap and insufficient locking force.

[0004] 2. Multi-lobed spliced ​​bending limiters (such as two- or three-lobed bolt-fastened structures): To accommodate pipe diameter tolerances, a larger assembly clearance must be reserved, and tightening is achieved by forcibly pulling the bolts together. This method has three inherent drawbacks: Uneven distribution of locking force: The bolt is located at a limited number of fastening points, resulting in a non-uniform contact between the inner wall of the limiter and the tube body, characterized by "high pressure at multiple points and low pressure in other areas". This not only results in poor bending limit effect, but also causes local indentations or even damage to the tube body surface. Poor dynamic adaptability: Under the action of waves and ocean currents, marine flexible pipes will generate continuous radial deformation (ellipticization) vibration. The bolt fastening structure cannot dynamically adapt to this slight change in pipe diameter, and the bolts are prone to loosening or pipe wear due to vibration. Stress concentration at the opening: The joints of multi-lobed structures are weak points in terms of mechanical strength. Under bending loads, they are prone to local plastic deformation, which can lead to permanent failure of the limiter.

[0005] In summary, the fundamental contradiction of existing technologies lies in their inability to simultaneously satisfy the two opposing demands of "large-gap rapid assembly" (accommodating pipe diameter tolerances and on-site installation) and "small-gap uniform locking" (ensuring bending limitation and long-term reliability). This invention aims to solve this specific technical problem. Summary of the Invention

[0006] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides a circumferentially spun self-locking quick-installation bending limiter for marine flexible pipes. This limiter includes a C-shaped elastic hoop and a spun locking ring. The hoop has unidirectional anti-disengagement teeth at both ends, and linearly tapered wedge-shaped spiral convex surfaces at both ends of its outer wall. The inner wall of the spun locking ring has a matching groove. Tightening the spiral surface of the locking ring generates uniform radial pressure throughout the circumference, contracting the hoop and engaging the anti-disengagement teeth. This achieves dual self-locking through friction and mechanical stopping, allowing for lateral quick installation and adapting to changes in pipe diameter.

[0007] The technical solution of this invention is: a circumferentially spun self-locking quick-install bending limiter for marine flexible pipes, comprising: The C-shaped hoop is a side-opening elastic structure that can be laterally clamped onto the outer wall of the marine flexible tube; and multiple one-way anti-detachment teeth are provided along the circumferential direction in the axial extension direction at both ends of the hoop, which mesh with multiple one-way anti-detachment teeth at the adjacent ends of the adjacent C-shaped hoop to form an anti-detachment meshing structure. The spinning locking ring is a rigid ring structure. It is sleeved on the outer periphery of the C-shaped hoop and cooperates with the C-shaped hoop through a spiral locking structure. When the spinning locking ring rotates circumferentially relative to the C-shaped hoop in the locking direction, it converts the rotational motion into a radial inward compressive force that is evenly distributed along the entire 360° circumference of the C-shaped hoop, forcing the C-shaped hoop to contract radially. The spiral locking structure has a spiral helix angle of ≤10° and achieves self-locking through friction.

[0008] A further technical solution of the present invention is: the one-way anti-detachment tooth is an asymmetrical wedge-shaped tooth, the inner slope of which is a gentle slope to allow the C-shaped hoop to mesh in stages when it contracts radially, and the outer slope of which is a steep slope to prevent the C-shaped hoop from opening in the opposite direction; After the spinning locking ring and the C-shaped hoop are installed in place, a rigid lock is formed. During service, when the flexible tube contracts radially, the C-shaped hoop contracts under its own elastic restoring force. The anti-disengagement engagement structure automatically engages with the next tooth position along the gentle slope to maintain the clamping force. When the flexible tube expands radially, the outer steep slope of the anti-disengagement engagement structure locks with each other to prevent the C-shaped hoop from opening in the opposite direction, exhibiting a combination of rigidity and flexibility with elastic follow-up and rigid locking coupling. A further technical solution of the present invention is: the two ends of the C-shaped hoop are respectively evenly distributed with 3 to 14 unidirectional anti-detachment teeth and grooves along the circumference, the distance between adjacent teeth is 5 to 10 mm, the height of the unidirectional anti-detachment teeth is consistent with the depth of the grooves, which is 3 to 8 mm, and the root of the teeth is provided with a rounded corner of R0.5 to R1.5 mm. The inner gentle slope of the unidirectional anti-detachment tooth has an inclination angle of 35° to 45°, and the outer steep slope has an inclination angle of 85° to 90°.

[0009] A further technical solution of the present invention is: the spiral locking structure includes wedge-shaped spiral convex surfaces disposed at both ends of the outer wall of the C-shaped hoop, and wedge-shaped spiral grooves disposed on the inner wall of the spiral locking ring, which are fully adapted to the wedge-shaped spiral convex surfaces; The radial height of the wedge-shaped helical convex surface increases linearly along the locking direction, and is related to the circumferential angle. θ satisfy: ,in, Circumferential turning angle The radial height of the wedge-shaped helical convex surface. This is the initial engagement height. The gradient coefficient; The total radial compression of the wedge-shaped spiral convex surface matches the allowable shrinkage within the elastic limit of the C-shaped hoop, so that the C-shaped hoop has a preset elastic potential energy when locking is completed.

[0010] A further technical solution of the present invention is: the gradient coefficient of the linearly gradient wedge-shaped helical convex surface. The value ranges from 3.8 to 4.2 mm / rad, and the initial engagement height is... The value range is 2 to 5 mm, and the total radial compression is 5 to 12 mm.

[0011] A further technical solution of the present invention is: the bending limiter further includes an engagement limiting opening annular surface; the outer surface of the engagement limiting opening annular surface is consistent with the inner surface of the C-shaped hoop, and is coaxially fitted into the C-shaped hoop, and its opening is aligned with the side opening of the C-shaped hoop; the inner surface of the engagement limiting opening annular surface is a circumferential surface of unequal diameter, wherein the radial height near the bending stress concentration part of the flexible tube is greater than the radial height away from the stress concentration part, so as to achieve precise bending limitation and reduce contact stress.

[0012] A further technical solution of the present invention is: the inner wall of the C-shaped hoop is provided with a linearly gradient wedge-shaped spiral convex surface, which is adapted to the gradient spiral groove opened on the outer circumferential surface of the meshing and limiting opening ring surface; the specific design includes: Inner radius of C-shaped hoop: ,in, R The outer radius of the C-shaped hoop. The radial cross-sectional wall thickness of the C-shaped hoop body; Radial profile equation of a linearly gradient wedge-shaped helical convex surface: ,in, For the corner The radial height of the linearly tapered wedge-shaped spiral convex surface; The radial height of the linearly tapered wedge-shaped spiral convex surface at the spiral's starting position; The gradient coefficient of the linearly gradient wedge-shaped spiral convex surface; The radius of gyration of the circumference of the top surface of the linearly gradient wedge-shaped helical convex surface: .

[0013] A further technical solution of the present invention is: the inner wall surface of the engagement limiting opening ring surface is provided with an elastic pad, the elastic pad is attached to the inner wall surface of the engagement limiting opening ring surface and the flexible tube, and is made of a high friction and corrosion resistant material, which is used to increase static friction, buffer vibration and avoid tube wear.

[0014] A further technical solution of the present invention is: the end of the wedge-shaped spiral groove of the spinning locking ring is provided with a mechanical limiting platform to limit the twisting stroke of the spinning locking ring and prevent excessive twisting from causing plastic deformation of the C-shaped hoop or damage to the spiral locking structure. An installation method using the aforementioned circumferentially spun self-locking marine flexible tube quick-installation bend limiter includes the following steps: Step 1: Pry open at least two of the C-shaped clamps from the side and sequentially attach them to the outer periphery of the preset bending limit position of the marine flexible pipe from the side. The adjacent ends of the adjacent C-shaped clamps engage in a one-way anti-disengagement toothed engagement structure to form an anti-disengagement engagement structure. Step 2: Insert multiple spinning locking rings into the end of the marine flexible pipe. The number of spinning locking rings is twice the number of C-shaped clamps. Push them along the axial direction of the flexible pipe to each end of each C-shaped clamp, so that the inner wall of the spinning locking ring and the outer wall of the C-shaped clamp are initially engaged, in a loose fit and without compressive force. Step 3: Rotate the spiral locking ring circumferentially along the locking direction. The spiral locking structure converts the rotational motion into a uniform extrusion force in the radial direction, driving the C-shaped hoop to contract radially. The side opening gap gradually narrows, causing the one-way anti-disengagement engagement structure to smoothly engage along the gentle slope. Step 4: Continue to screw until the mechanical limiting platform of the screw-locking ring abuts against the end of the wedge-shaped spiral convex surface. At this time, the C-shaped hoop shrinks to the preset size and tightly hugs the flexible tube. The one-way anti-disengagement engagement structure is fully engaged, and the spiral locking structure achieves friction self-locking, completing the installation. Step 5: When disassembly is required, apply force in the opposite direction of the locking direction to twist the screw-locking ring to overcome the self-locking friction of the spiral locking structure, so that the radial extrusion force is gradually released. The C-shaped hoop slowly opens under its own elasticity, and the anti-disengagement engagement structure separates. Then, push the screw-locking ring axially to remove it, and then pry the C-shaped hoop open from the side to remove it.

[0015] Beneficial effects The beneficial effects of this invention are as follows: This invention synergistically applies a C-shaped elastic opening, a wedge-shaped spiral locking surface, and unidirectional anti-detachment teeth to limit the bending of marine flexible pipes. The wedge-shaped spiral surface converts rotation into a 360° uniform radial force, enabling a switch from low-rigidity installation to high-rigidity locking. During service, the gentle slope of the unidirectional anti-detachment teeth allows for elastic tightening while a steep slope prevents reverse opening. Combined with spiral friction self-locking, this forms a rigid-flexible coupled dual self-locking mechanism, solving the long-standing problem of existing technologies being unable to simultaneously satisfy quick installation, uniform locking, and dynamic adaptation. Specific effects are analyzed below: 1. Significantly improved installation compatibility, enabling wide-tolerance lateral quick installation: Existing rigid sleeves can only be installed at the ends and cannot accommodate pipe diameter tolerances of ±3% to 5%; bolt splicing requires on-site alignment and is cumbersome; ordinary clamps have a narrow range of compatibility and are prone to jamming during installation. This invention adopts a C-shaped elastic opening with a free opening gap of 5 to 15 mm, which can be directly clamped laterally, accommodating the manufacturing tolerances and service deformation of flexible pipes in one go. No on-site adjustment or auxiliary tooling is required, and installation can be completed by a single person. It is especially suitable for complex working conditions such as underwater and pre-laid pipelines.

[0016] 2. Significantly enhanced locking uniformity and reliability, eliminating localized stress damage: Existing bolt-type locking systems use point-locking, resulting in stress concentration at the bolt location and a circumferential stress uniformity of less than 55%, which can easily cause localized indentations, wear, or even damage to the pipe body. Ordinary clamps have insufficient elastic clamping force and uneven distribution. This invention outputs a 360° uniform radial compressive force through a gradually changing wedge-shaped spiral surface, achieving a stress uniformity of over 92.6% and eliminating localized high-pressure areas. Combined with a friction self-locking mechanism with a spiral helix angle ≤10°, the locking force is stable and does not attenuate, completely eliminating the off-center loading defects of point-locking and protecting the safety of the flexible pipe body.

[0017] 3. Low-torque smooth locking + automatic centering, a double breakthrough in installation experience and reliability: The wedge-shaped spiral locking surface ensures that the compressive force is evenly distributed 360° around the entire circumference of the C-shaped hoop, avoiding the problem of "high pressure at multiple points and low pressure in other areas" caused by multiple bolts. Simultaneously, the anti-disengagement teeth on the open end face, after engagement, transform the stress state at the opening from "cantilever beam bending stress" to "inter-tooth compressive stress," significantly improving the fatigue life of the C-shaped hoop in marine vibration environments. Furthermore, the elastic pad buffers vibration, protects the pipe body, and enhances the protective effect.

[0018] 4. The wedge-shaped gradient is precise and controllable, with a high degree of elasticity matching: By using the linear variable lift compression curve and the elastic deformation function of the C-shaped hoop, a precise 1:1 match between the wedge compression and elastic deformation is achieved. The unidirectional anti-disengagement tooth meshing is smooth and impact-free, avoiding local stress concentration and significantly improving structural reliability and fatigue life. Attached Figure Description Figure 1 : An assembly diagram of the overall structure of a circumferentially spun self-locking marine flexible tube quick-assembly bending limiter in an embodiment of the present invention; Figure 2 : Schematic diagram of the C-shaped hoop structure in an embodiment of the present invention; Figure 3 : A schematic diagram of the adjacent unidirectional anti-dislodgement teeth meshing of two C-shaped hoop bodies in an embodiment of the present invention; Figure 4 : A schematic diagram of the linearly gradient wedge-shaped spiral convex surface of the inner wall of the C-shaped hoop in this embodiment of the invention; Figure 5 Schematic diagram of the meshing limiting opening annular structure in an embodiment of the present invention: Figure 6 : Schematic diagram of the spinning locking ring structure in an embodiment of the present invention; Figure 7 : A schematic diagram of the wedge-shaped spiral locking structure in an embodiment of the present invention; Figure 8 : A schematic diagram of the installation process of a circumferentially spun self-locking marine flexible pipe quick-installation bending limiter in an embodiment of the present invention (from top to bottom: C-shaped clamping body clamping, locking ring insertion, tightening engagement); Figure 9 The present invention relates to the self-locking performance, stress distribution, dynamic clamping performance, and the reversal angle of the locking ring after vibration of the bending limiter.

[0019] Explanation of reference numerals in the attached drawings: 1-C-type hoop, 2-spinning locking ring, 3-one-way anti-disengagement teeth, 4-wedge-shaped spiral groove, 5-wedge-shaped spiral convex surface, 6-meshing and limiting opening ring surface, 7-elastic pad, 8-anti-slip ridge, 9-mechanical limiting platform, 10-marine flexible tube, 11-linearly gradient wedge-shaped spiral convex surface on the inner wall of the C-type hoop, 12-gradient spiral groove on the meshing and limiting opening ring surface. Detailed Implementation The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] Traditional spiral wedge structures used in pipe connectors are typically designed for axial pull-out, with the wedge-shaped surface primarily generating axial clamping force. To generate sufficient radial clamping force, multiple rotations with long strokes are often required, placing extremely high demands on the coaxiality and rigidity of the locking ring and the base. Existing technology, such as US5280138A, uses a flanged opening that engages with the pipe port; once removed from the port, it easily loosens and falls off. CN210577689U's snap-fit ​​structure has limited locking force, making it unsuitable for handling dynamic marine loads, and snap-fit ​​or bolt structures can lead to excessive localized stress at the opening. This invention, however, achieves locking through a C-shaped clamp and a spun locking ring.

[0022] This invention is applied to flexible tube bending restraint scenarios, with the core requirements being: quick installation, low centering requirements, and avoidance of localized stress damage to the tube body. Existing marine flexible tube bending restraints generally suffer from a technical deficiency: the structural mechanical state cannot be actively, controllably, and reversibly switched dynamically across the three different stages of installation, locking, and service. Specifically: the installation stage requires a large gap, low stiffness, and easy deformation to achieve rapid lateral clamping and accommodate outer diameter fluctuations caused by the manufacturing and service of the flexible tube; the locking stage must quickly transform into a high-stiffness, small-gap, full-circumference rigid constraint to form a uniform, stable, and durable clamping force; and the long-term service stage requires a dual mechanical response of elastic follow-up and rigid locking to adapt to continuous radial elliptic vibration and creep deformation caused by internal pressure, temperature, and bending loads.

[0023] However, existing technologies, regardless of whether they employ rigid integral sleeves, multi-lobed bolt splicing structures, or ordinary C-type open clamps, are limited to a single, fixed mechanical working mode. They cannot achieve the three-level mechanical state switching of "low-rigidity installation - high-rigidity locking - rigid-flexible coupling service" within the same structure, forming an insurmountable technical bottleneck: rigid integral sleeves maintain high rigidity throughout, and although locking is reliable, they cannot be installed laterally, cannot accommodate pipe diameter tolerances, and completely lose dynamic adaptability; multi-lobed bolt splicing structures rely on discrete point bolt tightening, resulting in localized concentration and uneven overall locking stiffness, and discrete stress distribution, which easily causes localized indentations and damage on the pipe surface. Furthermore, they cannot follow dynamic changes in pipe diameter, and under long-term vibration, bolts are prone to loosening, preload attenuation, and failure of bending limiting function; ordinary C-type open clamps... Although the open-type clamp can be quickly installed laterally and accommodate tolerances, it relies entirely on the elasticity of the material itself to maintain the clamping force. It lacks a rigid locking mechanism, resulting in insufficient clamping force, low stiffness, and poor vibration resistance. Under alternating marine loads, it is very easy to open and loosen, and cannot meet the requirements for long-term reliable service in the deep sea.

[0024] Based on the above problems, this invention proposes a circumferentially spun self-locking quick-installation bending limiter for marine flexible pipes, combining the elastic contraction of a C-shaped side opening with a short-stroke wedge-shaped helix. The presence of the side opening actively reduces the requirements for the machining accuracy and fit clearance of the wedge-shaped helix surface. Even if there is a certain initial eccentricity or gap between the locking ring and the C-shaped clamp, the wedge-shaped surface can be aligned during rotation through the elastic deformation of the C-shaped opening. The wedge-shaped helix principle has been modified to adapt to the field installation scenarios of marine flexible pipes with large gaps, low stiffness, and fast operation. The specific technical solution is as follows: This invention discloses a circumferentially spun self-locking quick-install bend limiter for marine flexible tubing, comprising: The C-shaped hoop is a side-opening elastic structure that can be laterally clamped onto the outer wall of the marine flexible tube; and multiple one-way anti-detachment teeth are provided along the circumferential direction in the axial extension direction at both ends of the hoop, which mesh with multiple one-way anti-detachment teeth at the adjacent ends of the adjacent C-shaped hoop to form an anti-detachment meshing structure. The spinning locking ring is a rigid ring structure. It is sleeved on the outer periphery of the C-shaped hoop and cooperates with the C-shaped hoop through a spiral locking structure. When the spinning locking ring rotates circumferentially relative to the C-shaped hoop in the locking direction, it converts the rotational motion into a radial inward compressive force that is evenly distributed along the entire 360° circumference of the C-shaped hoop, forcing the C-shaped hoop to contract radially. The spiral locking structure has a spiral helix angle of ≤10° and achieves self-locking through friction.

[0025] Specifically, the spiral locking structure includes wedge-shaped spiral convex surfaces disposed at both ends of the outer wall of the C-shaped hoop, and wedge-shaped spiral grooves disposed on the inner wall of the spiral locking ring that are perfectly adapted to the wedge-shaped spiral convex surfaces. Taking the starting position of the spiral as the zero point of the circumferential coordinate system, the circumferential rotation angle is defined as... (Unit: rad, range 0≤θ≤2π).

[0026] Using a linear gradient profile, the total radial height of the wedge-shaped helical convex surface increases linearly with the circumferential rotation angle, expressed as: ,in, Circumferential turning angle Radial height of the wedge-shaped spiral convex surface, in mm; The initial radial height at the starting end of the spiral is set to 2–5 mm to ensure the initial assembly clearance and avoid assembly jamming. The slope of the height change (gradual change coefficient), in mm / rad, has a range of values ​​that are determined by the locking stroke and force requirements. K ∈[3.8,4.2]mm / rad. When If the load is too small, the load increases too slowly, the maximum compression is insufficient, and the clamping force does not meet the design requirements. When the angle is too large, the load increases too rapidly, approaching the instantaneous hard contact of a typical wedge surface with equal height, losing the advantage of gradual loading, and the stress uniformity decreases. The total wrap angle is fixed at... Match the installation process and locking stroke.

[0027] The total radial compression of the wedge-shaped helical convex surface matches the allowable shrinkage within the elastic limit of the C-shaped hoop, ensuring that the C-shaped hoop retains a preset elastic potential energy upon locking. The design is as follows: Total radial compression (5–12 mm) To lock the final corner ( rad); helix angle The self-locking condition is met. The wedge compression and the elastic deformation of the C-shaped hoop are precisely matched, satisfying the functional relationship: , The allowable shrinkage within the elastic limit of the C-shaped hoop (8-12 mm) ensures that the wedge compression and elastic deformation are completely synchronized, achieving uniform and impact-free shrinkage throughout the circumference.

[0028] The wedge-shaped spiral convex surface designed in this invention is compared and analyzed with the traditional wedge-shaped surface of equal height as follows: Traditional equal-height wedge surface: The radial height is a constant: (Constant), corresponding to radial compression (constant).

[0029] Substituting into the coupling formula, we get: The load reaches a constant peak instantaneously, and the circumferential load has no gradual change process. The initial contact impact is large and local stress concentration is easy to occur.

[0030] The wedge-shaped helical convex surface designed in this invention: When the C-shaped hoop is subjected to radial compression, the radial compression amount With unit circumferential radial load Satisfies the mechanical equations of an elastic circular ring: The load expression can be obtained from the deformation: ; radial compression of the helix Substitute the load formula to establish the circumferential position. Coupled function of gradient profile and elastic load: This indicates that the gradually varying height of the helical surface along the circumference is transformed into a radial load that is linearly and continuously distributed along the circumference through the elastic deformation of the hoop, thus achieving progressive uniform loading. Load With the continuous linear increase of the circumferential rotation angle, the loading process is smooth and impact-free; combined with the C-shaped opening elastic self-centering, the load is evenly distributed throughout the entire domain.

[0031] Specifically, the inner wall of the C-shaped hoop is provided with a linearly tapered wedge-shaped spiral convex surface, which matches the tapered spiral groove opened on the outer circumference of the meshing limiting opening ring surface. It only bears local meshing extrusion stress, serving as a guide, preventing torsion, and limiting the ultimate stroke. No circumferential clamping load is applied to drive the C-shaped hoop to contract, therefore it is not included in the elastic constitutive coupling calculation of the ring. The specific design includes: Inner radius of C-type hoop: ,in, R The outer radius of the C-shaped hoop. The radial cross-sectional wall thickness of the C-shaped hoop body; Radial profile equation: In the formula: For the corner The radial height of the linearly tapered wedge-shaped spiral convex surface, in mm; The radial height of the linearly tapered wedge-shaped helical convex surface at the helical starting position, with a value range of: ∈[1.0,2.0]mm; The gradient coefficient of the linearly gradient wedge-shaped helical convex surface, with a value range of: ∈[2.0,3.0]mm / rad.

[0032] Radius of rotation of the innermost helical protrusion (the side closest to the flexible mandrel): .

[0033] Instructions for parameter selection: a) Too small: The radial height of the spiral increases too slowly, the meshing clearance is too large in the middle and late stages of locking, the hoop is prone to circumferential eccentricity and deflection, and the guide fails; b) Too large: The height rises too quickly, and the spiral tightens the limiting rib groove during the locking process, making it impossible to rotate to the designed locking angle; c) To ensure the initial assembly clearance, the gradually changing spiral groove on the outer circumferential surface of the meshing limit opening ring can smoothly engage with the inner wall spiral without pre-assembly interference or jamming.

[0034] This invention precisely and functionally positions ratchet teeth on the open end face of a C-shaped clamp, forming a dual, redundant, and mutually guiding self-locking system with the wedge-shaped spiral locking structure. The wedge-shaped spiral structure self-locks against the reverse rotational torque of the spinning locking ring, preventing it from loosening due to vibration. The unidirectional anti-disengagement teeth self-lock against the radial force of the C-shaped clamp opening, preventing it from being stretched open by internal pressure or bending deformation of the flexible tube. This dual self-locking mechanism uses two completely different physical mechanisms to simultaneously resist two different types and directions of external forces. Furthermore, during the tightening of the spinning locking ring, the wedge-shaped spiral surface provides a gradual and controllable radial force, guiding the anti-disengagement teeth on the open end face to engage smoothly and steadily, avoiding the need for forceful pressing or striking to engage the ratchet teeth as with ordinary clamps. This enables precise, shock-free locking with one hand, offering significant advantages in underwater operations. The specific principle analysis is as follows: 1. Helical Self-Locking: This invention employs a C-shaped opening with elastic deformation combined with a 10° gradually changing wedge-shaped helix angle to satisfy the frictional self-locking condition tanα < μ, thus providing the helical structure with reliable frictional self-locking capability. In contrast, a C-shaped opening without a helix lacks radial locking force and cannot self-lock; a wedge-shaped helix without an opening requires a larger helix angle to generate sufficient radial force, inevitably violating the self-locking condition. Only a C-shaped opening with a wedge-shaped helical surface can achieve a low helix angle and strong self-locking.

[0035] Simulation verification shows that the self-locking condition for the helical screw is tanα < μ, where α is the helix angle and μ is the steel-to-steel dry friction coefficient, with a value of 0.2. The critical helix angle for self-locking is: Therefore, this invention uses α = 10° < 11.31°, satisfying: This indicates that the 10° spiral satisfies self-locking and the vibration does not reverse.

[0036] However, when there is only a helix and no opening: to obtain sufficient radial force, the helix angle must be increased. This will prevent it from locking itself. However, having only an opening and no spiral means there is no radial pressure and it cannot self-lock at all.

[0037] 2. Radial Clamping Uniformity: Based on the elastic ring contraction theory, calculations show that the C-shaped opening's elastic self-centering combined with the gradually changing wedge-shaped spiral applies pressure throughout the circumference, resulting in a uniform radial clamping force distribution along the entire circumference, achieving a stress uniformity of 92.6%. In contrast, a C-shaped opening without a spiral relies solely on elastic clamping, leading to uneven stress distribution; a spiral without an opening cannot self-align, resulting in localized high pressure due to eccentricity. Only a C-shaped opening with a wedge-shaped spiral surface can achieve uniform clamping throughout the entire circumference.

[0038] Simulation verification shows that the outer radius of the constructed C-shaped hoop model is... R =155mm, axial width of C-shaped hoopb =20mm, radial wall thickness of C-shaped hoop t =10mm; Material is high-strength stainless steel, elastic modulus = MPa; Radial uniform contact pressure after locking p =5MPa.

[0039] The axial section of the C-shaped hoop profile is rectangular, and the corresponding moment of inertia is: ; Distance from neutral axis to outer edge When an open circular ring is subjected to a uniformly distributed radial pressure, the formula for the circumferential bending stress is: MPa; The local stress is slightly higher due to the edge effect at the opening end, with the maximum contact stress being: MPa; The gradient wedge-shaped spiral continuous surface has a small discrete error, and the minimum contact stress is: MPa.

[0040] Preliminary stress uniformity:

[0041] Introducing C-type opening elastic self-centering correction (correction factor) k =1.005), further eliminating eccentricity and flattening stress distribution, resulting in final stress uniformity:

[0042] This value is derived quantitatively and rigorously from the theory of elasticity, and can only be achieved under the synergistic effect of the C-shaped elastic opening and the gradually changing wedge-shaped spiral. A single structure cannot eliminate eccentricity or achieve uniform pressure, and is far lower than the performance level of the C-shaped opening with the wedge-shaped spiral surface in this invention.

[0043] 3. Dynamic Pipe Diameter Adaptation: Under pipe diameter fluctuations of ±3%, the C-shaped opening with elastic follow-up and a gradually changing wedge-shaped spiral provides smooth guidance. The unidirectional anti-disengagement teeth enable step-by-step follow-up engagement, maintaining a clamping force retention rate of ≥97.4%. A C-shaped opening without spiral guidance results in significant tooth engagement impact and a tendency for teeth to jump; a spiral alone lacks the elasticity of the opening, making it unable to adapt to pipe diameter deformation and leading to adaptation failure. Only a C-shaped opening with a wedge-shaped spiral surface can achieve stable dynamic adaptation.

[0044] Simulation verification showed that a flexible pipe model was constructed with an outer diameter of D=300mm, a diameter fluctuation of ΔD=±3%, and a maximum fluctuation of ΔDmax=9mm. The initial gap of the C-type clamp opening was δ0=10mm. The parameters for the unidirectional anti-detachment teeth were: tooth pitch s=8mm and inner slope angle of the teeth. Assume the initial clamping force is the reference value F0.

[0045] Pipe diameter shrinkage That is, the hoop retracts radially: mm; The C-shaped opening elastically retracts, and the unidirectional teeth slide along the gentle slope, meshing in stages. The force transmission efficiency of the meshing teeth is determined by the slope angle. ; The gradient helical surface provides smooth guidance, eliminates impact loss, and improves guiding efficiency. ; When the pipe diameter expands: steep slope locking, almost no force loss, steep slope angle on the outer side. Almost vertical, the reverse opening is completely locked, and the force loss is minimal: ; Integrated flexible follow-up, gear meshing, helical guidance, and steep slope locking: ; Type C opening elastic reserve (opening gap of 10 mm is much larger than the fluctuation of 4.5 mm, with sufficient elastic margin), introduces an elastic correction coefficient: ; Final retention rate: ; Open only, no spiral: large impact during tooth meshing, tooth skipping, and low retention rate. Spiral only, no opening: lacks elasticity and cannot adapt to changes in pipe diameter. Only the C-shaped opening design with a wedge-shaped helical surface can balance elastic follow-up and smooth guidance, thus ensuring stable clamping force.

[0046] 4. Long-term vibration to prevent loosening: 1×10 6 Simulations under alternating loads show that the C-shaped opening elastic buffer combined with the gradually changing wedge-shaped spiral friction self-locking mechanism results in a locking ring reversal angle ≤0.04° with no slippage or loosening. A C-shaped opening without spiral self-locking is prone to fatigue opening under vibration; a spiral without opening buffer leads to contact stress concentration and slippage / loosening. Only a C-shaped opening with a wedge-shaped spiral surface can achieve long-term stable anti-loosening.

[0047] Simulation verification shows that under a single alternating load, the instantaneous infinitesimal element offset angle of the helical pair is... Radius, total cumulative turning angle in uncorrected state: ; Introducing a C-type opening elastic buffer coefficient By utilizing the elastic deformation of the opening to absorb vibration and shock and suppress slippage, the corrected rotation angle is achieved. ; The gradient wedge-shaped helical surface can achieve uniform circumferential pressure distribution, further reducing local slippage, and is combined with a structural uniformity correction coefficient. The final cumulative reversal angle: ; Open only, no spiral: lacks frictional self-locking constraint, and is prone to continuous loosening under long-term vibration; Only spiral, no opening: unable to absorb vibration and shock, and the reversal angle is much greater than... ; Only the C-shaped opening design with a wedge-shaped helical surface, relying on the dual effects of frictional self-locking and elastic buffering, allows the passage through... After the alternating load, the locking ring reverses its angle. The structure did not loosen or fail.

[0048] In this embodiment, the equation for the gradient wedge surface profile is: The corresponding unit circumferential load The radial height of the traditional constant-height wedge surface is 8.28 mm, and the load... N / mm.

[0049] Gradient structure at corner 0, , The loads at the points were 1.10 N / mm, 2.82 N / mm, and 4.54 N / mm, respectively. The loads increased linearly and continuously along the circumference. The initial load was only 24.23% of the peak value, achieving gradual and stable loading. Traditional equal-height structures reached full load upon initial contact, resulting in significant contact impact.

[0050] The above technical solution will be further analyzed below with reference to case studies and accompanying diagrams: Example 1: Reference Figure 1-6 As shown, a circumferentially spun self-locking quick-installation bending limiter for marine flexible pipes includes a C-shaped clamp 1 and a spun locking ring 2, with the specific structure as follows: Reference Figure 2 and Figure 4 As shown, the C-type clamp 1 is an open-type elastic structure made of high-strength stainless steel with anti-corrosion treatment. It can be laterally clamped onto the outer wall of the marine flexible pipe 10. Its inner wall has a wedge-shaped spiral concave surface 11, which cooperates with the spiral groove 12 on the engagement and limiting opening annular surface 6. The inner wall of the C-type clamp 1 is also provided with an elastic pad 7, which is set to fit against the engagement and limiting opening annular surface 6. The elastic pad 7 is made of high-friction, corrosion-resistant polyurethane material to increase the static friction between the C-type clamp 1 and the marine flexible pipe 10, while buffering vibration and avoiding pipe wear.

[0051] Reference Figure 5 As shown, the outer surface of the engagement limiting opening annular surface 6 is consistent with the inner surface of the C-shaped hoop 1, and is coaxially fitted inside the C-shaped hoop 1, with its opening aligned with the side opening of the C-shaped hoop 1; the inner surface of the engagement limiting opening annular surface 6 is a circumferential surface of unequal diameter, wherein the radial height near the stress concentration point of the flexible tube bending is greater than the radial height away from the stress concentration point, which is used to precisely limit the excessive bending of the flexible tube, so as to achieve precise bending limit and reduce contact stress.

[0052] Reference Figure 2 and Figure 3 As shown, multiple unidirectional anti-detachment teeth 3 are arranged circumferentially along the axial extension direction at both ends of the C-shaped hoop 1. The unidirectional anti-detachment teeth 3 on the left end face are defined as convex tooth structures, and the unidirectional anti-detachment teeth 3 on the right end face are defined as groove structures, which are precisely matched with the convex tooth structures of the adjacent C-shaped hoop 1. The unidirectional anti-detachment teeth 3 are asymmetrical wedge-shaped teeth. The inner slope of the tooth (towards the direction of hoop contraction) has an inclination angle of 35°, and the outer slope (towards the direction of hoop opening) is a 90° vertical straight surface. It only allows the C-shaped hoop 1 to contract and tighten radially, and prohibits it from opening in the opposite direction under the action of external force. The unidirectional anti-detachment teeth 3 are evenly arranged in 4 rows along the circumference, with a tooth pitch of 8mm. The height of the convex tooth structure is consistent with the depth of the groove structure, which is 5mm. The tooth roots of the convex tooth structure and the groove structure are provided with R1.0mm rounded corners to avoid stress concentration and tooth breakage.

[0053] Reference Figure 2 and Figure 7 As shown, both axial ends of the outer wall of the C-type hoop 1 are provided with continuous wedge-shaped spiral convex surfaces 5. The wedge-shaped spiral convex surfaces 5 extend circumferentially along the hoop, and their height gradually changes in a wedge shape, becoming higher towards the tightening direction. The wedge-shaped spiral convex surfaces 5 adopt a linear variable lift gradual design, and the compression curve is as follows: ( ∈[0,π / 2] rad), initial height mm, total compression mm, matching the elastic shrinkage of the C-type hoop. mm; helix angle It satisfies the self-locking condition.

[0054] Reference Figure 6 As shown, the spinning locking ring 2 is a rigid integral ring structure, also made of high-strength stainless steel with anti-corrosion treatment on the surface. It can be inserted into the end of the marine flexible pipe 10 and pushed axially to the outer periphery of the C-shaped hoop 1. Its inner wall is provided with a wedge-shaped spiral groove 4 that is completely adapted to the wedge-shaped spiral convex surface 5 of the outer wall of the C-shaped hoop 1. The width, depth, and spiral angle of the wedge-shaped spiral groove 4 are consistent with the wedge-shaped spiral convex surface 5, forming a sliding fit. The outer wall of the spinning locking ring 2 is provided with an anti-slip twisting structure, including anti-slip ridges 8 evenly arranged in the circumference, which facilitates the clamping and force application of construction tools. The end of the wedge-shaped spiral groove 4 of the spinning locking ring 2 is provided with a mechanical limiting platform 9, which is used to limit the twisting stroke of the spinning locking ring 2 and prevent excessive twisting from causing plastic deformation of the C-shaped hoop 1 or damage to the spiral surface.

[0055] Reference Figure 7As shown, the wedge-shaped spiral convex surface 5 and the wedge-shaped spiral groove 4 cooperate to form a wedge-shaped spiral locking structure. The spiral helix angle of the wedge-shaped spiral locking structure is 10°, which meets the mechanical self-locking conditions. When the circumferentially rotating and spinning locking ring 2 is rotated, the wedge-shaped spiral groove 4 slides along the wedge-shaped spiral convex surface 5, generating a uniform extrusion force in the radial direction, which forces the C-shaped hoop 1 to contract, causing the one-way anti-disengagement teeth 3 at the opening to mesh with each other, and finally achieving the double self-locking of the C-shaped hoop 1 and the spinning locking ring 2, so that the C-shaped hoop 1 tightly hugs the marine flexible pipe 10.

[0056] Reference Figure 8 As shown, the installation process in this embodiment is as follows: 1. Installing C-type hoop 1: Install the engagement limiting opening ring surface 6 into the C-type hoop 1, and embed the wedge-shaped spiral protrusion 11 on the inner wall of the C-type hoop into the spiral groove 12 of the engagement limiting opening ring surface 6, and lay an elastic pad 7 on the inner wall surface of the engagement limiting opening ring surface 6; then, laterally pry open the two installed C-type hoop 1, and sequentially clamp them at the preset bending limit points of the marine flexible pipe 11, with the elastic pad 7 tightly attached to the outer wall of the pipe; the unidirectional anti-disengagement teeth 3 at the adjacent ends of the two C-type hoop 1 engage to form an anti-disengagement engagement structure; 2. Insert the spinning locking rings 2: Insert the four spinning locking rings 2 into the end of the marine flexible tube 10 and push them along the tube axial direction to the outside of the C-shaped hoop 1. Each end of the C-shaped hoop 1 is equipped with a spinning locking ring 2, so that the wedge-shaped spiral groove 4 on the inner wall of the spinning locking ring 2 and the wedge-shaped spiral convex surface 5 on the outer wall of the C-shaped hoop 1 are initially engaged (loose fit, no compressive force). 3. Tighten and lock: Use a wrench to hold the screw-locking ring 2 and screw it circumferentially in the clockwise tightening direction. The wedge-shaped spiral groove 4 slides along the wedge-shaped spiral convex surface 5, generating a uniform extrusion force in the radial direction. Under the extrusion force, the C-shaped hoop 1 slowly and elastically contracts, and the opening gap gradually narrows. The one-way anti-disengagement teeth 3 at the opening smoothly engage along the gentle slope. 4. Locking in place: Continue to tighten until the mechanical limit table 9 and the end of the wedge-shaped spiral convex surface 5 are tightly pressed together and cannot be rotated further. At this time, the C-shaped hoop 1 shrinks to the preset size and tightly hugs the marine flexible tube 10. The one-way anti-detachment teeth 3 are fully engaged, and the wedge-shaped spiral locking surface achieves friction self-locking, completing the installation.

[0057] 5. When disassembly or adjustment is required, simply use a wrench to hold the screw-on locking ring 2 and apply force in the opposite direction of the tightening direction to overcome the self-locking friction of the wedge-shaped spiral locking surface. The wedge-shaped spiral groove 4 slides in the opposite direction along the wedge-shaped spiral convex surface 5, and the radial extrusion pressure is gradually released. The C-shaped hoop 1 slowly opens under its own elasticity, and the one-way anti-detachment teeth 3 separate. Then, push the screw-on locking ring 2 along the axial direction of the tube body to remove it, and then pry the C-shaped hoop 1 open from the side to remove it. The operation is simple.

[0058] Example 2: The difference between this embodiment and Embodiment 1 is that: the unidirectional anti-detachment teeth 3 are evenly arranged in 6 rows along the radial end face of the opening of the C-shaped hoop 1, with a tooth pitch of 5mm, the height of the convex tooth structure is consistent with the depth of the groove structure, which is 3mm, and the tooth root radius is R0.5mm; the helix angle of the wedge-shaped spiral locking surface is 10°; the engagement limiting opening annular spiral groove 12 is provided in 6 rows, the elastic pad 7 is made of fluororubber, and the rest of the structure is the same as that of Embodiment 1, which can achieve the same technical effect and adapt to the bending limit requirements of small-diameter marine flexible pipes.

[0059] Example 3: The difference between this embodiment and embodiment 1 is that the outer slope angle of the one-way anti-detachment tooth 3 is 85° and the inner slope angle is 45°; the helix angle of the wedge-shaped spiral locking surface is 6°; the rest of the structure is the same as that of embodiment 1, which can be adapted to the bending limit requirements of large-diameter marine flexible pipes and is convenient to tighten with the help of a large wrench.

[0060] Example 4: The difference between this embodiment and Embodiment 1 is that the free opening gap of the C-type hoop is 12 mm, which can accommodate pipe diameter tolerances of ±5%. The unidirectional anti-loosening backtooth pitch is set to 6 mm to achieve more precise step-by-step locking; the wedge-shaped spiral locking surface has a helix angle of 7° to further improve self-locking stability.

[0061] Simulation results show that: within a pipe diameter of +3%~ Under 3% dynamic fluctuation conditions, the clamping force retention rate in this embodiment is 98.2%, the uniformity of contact stress throughout the circumference is 93.5%, and the vibration is 10 6 The locking ring does not reverse or loosen after the second lock, and can simultaneously meet the three major technical requirements of "large gap assembly, uniform locking, and dynamic self-adaptation".

[0062] Comparative Example 1: Traditional multi-lobed bolt-type bending limiter; Structure: Two or three-lobed splicing, secured circumferentially with 4 to 6 bolts.

[0063] Defects exist: 1. The bolts are point-tightened, resulting in uneven distribution of clamping force and localized stress concentration; 2. It cannot adapt to dynamic fluctuations in pipe diameter, and is prone to loosening due to long-term vibration; 3. Installation requires multiple torque calibrations, making the operation cumbersome and underwater construction difficult; 4. The open splice is under cantilever stress, which makes it prone to fatigue cracking.

[0064] Comparative Example 2: Open-type C-shaped cable protective sleeve; Structure: Soft plastic C-shaped opening structure, no locking ring, no one-way anti-disengagement teeth, and no radial clamping structure.

[0065] Defects exist: 1. Relying solely on the end flange to hold the pipe port, it is impossible to fix it at any position along the pipe's axial direction; 2. Lacking rigid support and locking structure, it lacks bending restraint capabilities; 3. The opening is not locked and fixed, making it easy to open and fall off, and it cannot withstand dynamic marine loads; 4. Only applicable to cable conduit opening protection, not suitable for marine flexible conduit bending scenarios.

[0066] Comparative Example 3: Ordinary flexible open C-type clamp (without spiral locking + without one-way teeth); Structure: It relies solely on the elasticity of the material to hold the object in place, without external locking or ratchet anti-detachment mechanisms.

[0067] Defects exist: 1. Low clamping force, prone to rebound and loosening, and lacks self-locking ability; 2. It is extremely easy to loosen under vibration and has no dynamic pipe diameter adaptability; 3. Lacking sufficient stiffness, it cannot effectively limit bending. 4. It cannot meet the requirements for long-term reliable service in the deep sea.

[0068]

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A circumferential spinning self-locking marine flexible pipe quick-fit bend limiter, characterized in that, include: The C-shaped hoop is a side-opening elastic structure that can be laterally clamped onto the outer wall of the marine flexible tube; and multiple one-way anti-detachment teeth are provided along the circumferential direction in the axial extension direction at both ends of the hoop, which mesh with multiple one-way anti-detachment teeth at the adjacent ends of the adjacent C-shaped hoop to form an anti-detachment meshing structure. The spinning locking ring is a rigid ring structure. It is sleeved on the outer periphery of the C-shaped hoop and cooperates with the C-shaped hoop through a spiral locking structure. When the spinning locking ring rotates circumferentially relative to the C-shaped hoop in the locking direction, it converts the rotational motion into a radial inward compressive force that is evenly distributed along the entire 360° circumference of the C-shaped hoop, forcing the C-shaped hoop to contract radially. The spiral locking structure has a spiral helix angle of ≤10° and achieves self-locking through friction.

2. A circumferential spinning self-locking bend limiter for flexible pipe for offshore use according to claim 1, characterized in that: The one-way anti-detachment tooth is an asymmetrical wedge-shaped tooth, with a gentle slope on its inner side to allow the C-shaped hoop to engage in stages when it contracts radially, and a steep slope on its outer side to prevent the C-shaped hoop from opening in the opposite direction. After the spinning locking ring and the C-shaped hoop are installed in place, a rigid lock is formed. During service, when the flexible tube contracts radially, the C-shaped hoop contracts under its own elastic restoring force. The anti-disengagement engagement structure automatically engages with the next tooth position along the gentle slope to maintain the clamping force. When the flexible tube expands radially, the outer steep slope of the anti-disengagement engagement structure locks with each other to prevent the C-shaped hoop from opening in the opposite direction, exhibiting a combination of rigidity and flexibility with elastic follow-up and rigid locking coupling.

3. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 2, characterized in that: The C-shaped hoop has 3 to 14 unidirectional anti-detachment teeth and grooves evenly distributed around its two ends. The distance between adjacent teeth is 5 to 10 mm. The height of the unidirectional anti-detachment teeth and the depth of the grooves are the same as 3 to 8 mm. The tooth roots are provided with rounded corners of R0.5 to R1.5 mm. The inner gentle slope of the unidirectional anti-detachment tooth has an inclination angle of 35° to 45°, and the outer steep slope has an inclination angle of 85° to 90°.

4. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 1, characterized in that: The spiral locking structure includes wedge-shaped spiral convex surfaces disposed at both ends of the outer wall of the C-shaped hoop, and wedge-shaped spiral grooves disposed on the inner wall of the spiral locking ring that are perfectly adapted to the wedge-shaped spiral convex surfaces. The radial height of the wedge-shaped helical convex surface increases linearly along the locking direction, and is related to the circumferential angle. θ satisfy: ,in, Circumferential turning angle The radial height of the wedge-shaped helical convex surface. This is the initial engagement height. The gradient coefficient; The total radial compression of the wedge-shaped spiral convex surface matches the allowable shrinkage within the elastic limit of the C-shaped hoop, so that the C-shaped hoop has a preset elastic potential energy when locking is completed.

5. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 4, characterized in that: The gradient coefficient of the linearly gradient wedge-shaped spiral convex surface The value ranges from 3.8 to 4.2 mm / rad, and the initial engagement height is... The value range is 2 to 5 mm, and the total radial compression is 5 to 12 mm.

6. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 1, characterized in that: The bending limiter also includes an engagement limiting opening annular surface; the outer surface of the engagement limiting opening annular surface is consistent with the inner surface of the C-shaped hoop, and is coaxially fitted into the C-shaped hoop, with its opening aligned with the side opening of the C-shaped hoop; the inner surface of the engagement limiting opening annular surface is a circumferential surface of unequal diameter, wherein the radial height near the stress concentration point of the flexible tube bending is greater than the radial height away from the stress concentration point, so as to achieve precise bending limitation and reduce contact stress.

7. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 6, characterized in that: The inner wall of the C-shaped hoop is provided with a linearly gradient wedge-shaped spiral convex surface, which is adapted to the gradient spiral groove opened on the outer circumference of the meshing and limiting opening annular surface; the specific design includes: Inner radius of C-shaped hoop: ,in, R The outer radius of the C-shaped hoop. The radial cross-sectional wall thickness of the C-shaped hoop body; Radial profile equation of a linearly gradient wedge-shaped helical convex surface: ,in, For the corner The radial height of the linearly tapered wedge-shaped spiral convex surface; The radial height of the linearly tapered wedge-shaped spiral convex surface at the spiral's starting position; The gradient coefficient of the linearly gradient wedge-shaped spiral convex surface; The radius of the circumference of the top surface of the linearly gradient wedge-shaped helical convex surface: .

8. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 7, characterized in that: The inner wall of the engagement limiting opening ring is provided with an elastic pad. The elastic pad is attached between the inner wall of the engagement limiting opening ring and the flexible tube. It is made of high friction and corrosion resistant material and is used to increase static friction, buffer vibration and avoid tube wear.

9. The circumferentially spun self-locking quick-install bending limiter for marine flexible tubing according to claim 1, characterized in that: The wedge-shaped spiral groove of the spinning locking ring is provided with a mechanical limiting platform at its end, which is used to limit the twisting stroke of the spinning locking ring and prevent excessive twisting from causing plastic deformation of the C-shaped hoop or damage to the spiral locking structure.

10. An installation method for a quick-installation bending limiter for circumferentially spun self-locking marine flexible pipe as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Pry open at least two of the C-shaped clamps from the side and sequentially attach them to the outer periphery of the preset bending limit position of the marine flexible pipe from the side. The adjacent ends of the adjacent C-shaped clamps engage in a one-way anti-disengagement toothed engagement structure to form an anti-disengagement engagement structure. Step 2: Insert multiple spinning locking rings into the end of the marine flexible pipe. The number of spinning locking rings is twice the number of C-shaped clamps. Push them along the axial direction of the flexible pipe to each end of each C-shaped clamp, so that the inner wall of the spinning locking ring and the outer wall of the C-shaped clamp are initially engaged, in a loose fit and without compressive force. Step 3: Rotate the spiral locking ring circumferentially along the locking direction. The spiral locking structure converts the rotational motion into a uniform extrusion force in the radial direction, driving the C-shaped hoop to contract radially. The side opening gap gradually narrows, causing the one-way anti-disengagement engagement structure to smoothly engage along the gentle slope. Step 4: Continue to screw until the mechanical limiting platform of the screw-locking ring abuts against the end of the wedge-shaped spiral convex surface. At this time, the C-shaped hoop shrinks to the preset size and tightly hugs the flexible tube. The one-way anti-disengagement engagement structure is fully engaged, and the spiral locking structure achieves friction self-locking, completing the installation. Step 5: When disassembly is required, apply force in the opposite direction of the locking direction to twist the screw-locking ring to overcome the self-locking friction of the spiral locking structure, so that the radial extrusion force is gradually released. The C-shaped hoop slowly opens under its own elasticity, and the anti-disengagement engagement structure separates. Then, push the screw-locking ring axially to remove it, and then pry the C-shaped hoop open from the side to remove it.

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