A method of winding a large diameter solid wall pipe

Abstract

The present application relates to the technical field of composite pipe manufacturing, and particularly relates to a winding method of a large-diameter solid-wall pipe, which comprises the following steps: step one, starting anchoring section winding: continuously circularly winding 3-6 layers on the surface of a core mold at a winding angle of 85-90 degrees, a first tension and a first linear velocity, to form a starting reinforcing ring; the first tension is 110%-120% of a rated tension, and the first linear velocity is not more than 50% of a maximum design linear velocity; step two, transition stable section winding: spirally winding above the starting anchoring section at a winding angle of + / - 55 degrees, a second tension and a second linear velocity. The starting anchoring section with high angle, high tension and low linear velocity is arranged in step one, to form a rigid starting reinforcing ring, so that the problems of fiber slippage, wrinkle and poor combination with the inner liner of the initial layer are fundamentally solved, and the internal stress concentration defects caused thereby are eliminated.

Description

Technical Field

[0001] This invention relates to the field of composite material pipe manufacturing technology, and in particular to a winding method for large-diameter solid-wall pipes. Background Technology

[0002] Composite material large-diameter solid-wall pipes are widely used in municipal water supply and drainage, oil and gas transportation, and marine engineering due to their advantages such as lightweight, high strength, good corrosion resistance, and long service life. Fiber winding is currently the mainstream method for manufacturing such pipes. The basic process involves winding continuous fibers impregnated with resin at a preset angle onto a rotating mandrel, which is then cured to form the pipe body.

[0003] Traditional winding processes typically employ relatively fixed process parameters for helical and circumferential winding, aiming for neat arrangement of fibers in each layer. However, with the continuous increase in pipe diameter (often exceeding 1 meter) and the increasingly complex service environments (such as high internal pressure, deep burial, and impact loads), traditional methods have gradually revealed the following problems: When the initial layer is wound on the mandrel surface, if the same parameters as the main body are used, the fiber-matrix bond is weak, easily leading to slippage or wrinkling. These initial defects, once covered by subsequent layers, form stress concentration points, affecting the overall strength and fatigue life of the pipe end; The interlayer interfaces formed by traditional processes are flat and continuous, with layers mainly relying on resin bonding. Under impact, shear, or cyclic loads, delamination failure easily occurs, reducing the pipe's damage resistance and toughness; While constant tension winding throughout the process is easy to control, it ignores the dynamic changes in structural stiffness during winding, easily accumulating residual stress within the pipe wall, affecting dimensional stability and long-term service safety. Therefore, a winding method for large-diameter solid-wall pipes is needed to solve these problems. Summary of the Invention

[0004] The purpose of this invention is to solve the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for winding large-diameter solid-walled tubes includes the following steps: Step 1, Initial anchoring section winding: Continuously wind 3-6 layers circumferentially on the mandrel surface at a winding angle of 85° to 90°, with a first tension and a first linear velocity to form the initial reinforcing ring; the first tension is 110% to 120% of the rated tension, and the first linear velocity does not exceed 50% of the maximum design linear velocity; Step 2, Transition Stabilization Section Winding: Above the initial anchoring section, spiral winding is performed at a winding angle of ±55°, a second tension, and a second linear speed until the pipe wall thickness reaches 60% to 70% of the target thickness; the second tension is 95% to 105% of the rated tension; Step 3, High-efficiency winding of the main body: On the transition stable section, spiral winding is performed with a third winding angle, the rated tension and the third linear speed until the target wall thickness is reached; the third winding angle is ±54° to ±56°, and the third linear speed is greater than or equal to 80% of the maximum design linear speed.

[0006] Preferably, in the second step of the transition stabilization winding, after each predetermined number of spiral layers are wound, at least one circumferential winding layer is inserted as a constraint layer.

[0007] Preferably, the rated tension is determined based on 5% to 10% of the breaking strength of the reinforcing fiber used.

[0008] Preferably, in at least one stage of the transitional stable section winding in step two and the main high-efficiency section winding in step three, an angle-alternating progressive layup method is adopted: with 2 to 4 layers as a group, the winding angle of adjacent layers within the group alternates between 1 degree and 3 degrees above the target angle reference value.

[0009] Preferably, after completing step three (the main body high-efficiency segment winding), the process further includes: Step 4, Local Circumferential Reinforcing Section Winding: In the predetermined high-stress area of ​​the pipeline, an additional 3-6 layers of pure circumferential winding are performed with a winding angle of greater than or equal to 85 degrees and a tension higher than the rated tension to form a local reinforcing ring.

[0010] Preferably, a flexible interface layer construction step is introduced before the start of the initial anchoring section winding in step one, or during the transition stabilization section winding in step two: Apply a thin layer of resin rich in elastomer microparticles or chopped flexible fibers to the surface of the already wound fiber layer.

[0011] Preferably, during the transition stabilization winding in step two, a three-dimensional fiber network is constructed simultaneously: while spiral winding, one or more continuous axial fibers or large-angle fibers are directly laid and embedded into the spiral fiber layer being wound.

[0012] Preferably, in the second step of the transition stabilization section winding, the predetermined number of winding layers is 10 layers, and the inserted circumferential winding layer is 1 layer.

[0013] A large-diameter solid-walled tube is manufactured by the winding method of any one of claims 1 to 8.

[0014] The present invention has at least the following beneficial effects: 1. This invention, by setting a high-angle, high-tension, and low-linear-speed initial anchoring section in step one, forms a rigid initial reinforcing ring, which fundamentally solves the problems of initial layer fiber slippage, wrinkling, and poor bonding with the inner lining, and eliminates the internal stress concentration defects caused by this, thus ensuring the structural integrity of the pipe end and its long-term static pressure strength.

[0015] 2. This invention breaks the traditional flat interlayer interface by using alternating progressive lay-up and flexible interface layer construction in steps two and three, forming a micro-mechanical interlock or flexible stress buffer zone, which effectively inhibits crack propagation along the interlayer, improves the interlayer shear strength of the pipeline, and enhances its impact energy absorption capacity.

[0016] 3. This invention adopts a segmented strategy and parameter optimization that combines transitional stability with high efficiency of the main body. Under the premise of ensuring structural quality, a higher linear speed is used in the main body to improve overall production efficiency. At the same time, in step four, local circumferential reinforcement is carried out in the high-stress area to achieve precise material distribution and on-demand reinforcement, thereby improving local pressure bearing capacity. This solves the problem that homogeneous winding cannot provide targeted reinforcement and can directly and efficiently strengthen the axial performance of the pipeline by simultaneously constructing a three-dimensional fiber network. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the process flow of a winding method for a large-diameter solid-walled tube proposed in this invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] In this invention, the winding angle refers to the angle between the direction of the wound fiber and the axis of the pipe. The ± symbol indicates that the helical winding includes two symmetrical directions to balance the torque. The angle selection is based on the pipe stress analysis: circumferential winding (85°–90°) mainly resists the circumferential stress caused by internal pressure; an angle around ±55° is a classic balanced winding angle that can match the circumferential and axial strength; fine-tuning to 54°–56° can optimize the stress distribution under specific loads.

[0021] Maximum design linear speed: This is determined by the winding equipment capacity, resin curing characteristics, and fiber impregnation effect. It is not only the upper limit of the equipment's mechanical capacity but also the upper limit of the process speed under the premise of ensuring interlayer bonding quality, no air bubbles, and uniform fiber arrangement. The initial low-speed stage (≤50%) ensures initial lamination and impregnation; the high-speed stage (≥80%) improves efficiency after the structure stabilizes.

[0022] The target wall thickness is determined by classical mechanics formulas based on the pipeline design pressure, diameter, and safety factor. The formula can be a thin-walled cylinder formula. The predetermined high-stress areas can be identified in advance through finite element analysis, which usually refers to the parts with stress concentration factor > 2.0, such as: socket joints, elbows, opening reinforcement areas, and supports of buried pipelines.

[0023] Rated tension refers to the baseline tension value for the main winding stage, determined through process optimization, for a specific reinforcing fiber such as E-glass fiber or carbon fiber, ensuring that the fiber does not break and is fully impregnated with resin during winding. It is typically determined through pre-experiments and ranges from 5% to 10% of the typical breaking strength of the fiber monofilament. Maximum design linear speed refers to the highest permissible mechanical linear speed of the winding equipment, ensuring stable fiber transport, uniform resin impregnation, and flat yarn arrangement. It is provided by the equipment manufacturer or obtained through equipment calibration.

[0024] The target wall thickness of this invention is determined by conventional mechanical calculations or by referring to industry standards, based on pipeline design pressure, diameter, safety factor, etc.

[0025] The predetermined high-stress areas include, but are not limited to, the socket connection ports of pipes, bends, tees or valve connections, and pipe sections where the internal pressure, external pressure, and bending stress concentration factors are greater than 2.0 under specific loads, as determined by finite element analysis.

[0026] Reference Figure 1 , Example 1: A three-stage progressive winding method for large-diameter solid-walled pipe foundations; This embodiment demonstrates the basic three-stage winding process of the present invention, namely, initiation, transition, and main body, which solves the problem of balancing the stability of winding initiation with overall production efficiency.

[0027] Step 1: Wrapping the initial anchoring section; First, the 2-meter diameter steel mandrel is surface-treated, coated with a release agent, and a resin-rich inner lining layer with a thickness of approximately 1.5 mm is created using a spraying process. Then, the initial anchoring section is wound. E-glass fiber untwisted roving (2400Tex) is impregnated with epoxy resin, and the process parameters are set as follows: for pure circumferential winding, the winding angle is 90°, the winding tension is 12N (in this example, the rated tension is set to 10N, therefore 120% of the rated tension), and the linear speed is 0.15 m / s (when the maximum design linear speed of the equipment is 0.3 m / s, i.e., 50%).

[0028] Starting at one end of the mandrel, four layers are continuously and tightly wound in a circumferential direction. During this stage, high tension and low linear speed are used to ensure that the fiber and lining are fully impregnated and compacted, forming an initial reinforcing ring with a width of about 200 mm and high circumferential stiffness, providing a stable mechanical anchor point for subsequent winding.

[0029] Step 2, winding of the transition and stabilization segment; Above the initial reinforcing ring, switch to the transition stabilization section for winding. Adjust the process parameters as follows: winding angle ±55°, tension 10.5N (105% of the rated tension), and linear speed increased to 0.18m / s. Helical winding begins from the end of the initial reinforcing ring. During this process, after every 10 consecutive ±55° helical layers, a 90° circumferential layer is inserted as a constraint layer.

[0030] This spiral and circumferential constraint pattern continues until the cumulative wall thickness of the entire pipe section reaches 65% of the target total thickness. For example, 65% of 25mm is 16.25mm. This stage constructs a uniform and stable transition skeleton, effectively avoiding internal defects.

[0031] Step 3: Winding of the main high-efficiency section; Above the transition and stabilization section, the main high-efficiency section is wound to quickly achieve the final wall thickness. The process parameters are further optimized as follows: the winding angle is finely adjusted to ±54.5° to slightly increase the axial strength component, the tension is precisely maintained at the rated tension of 10N, and the linear speed is increased to a relatively high speed of 0.26m / s for stable operation of the equipment. This speed is approximately 87% of the maximum design linear speed. The spiral winding continues until the tube wall thickness reaches the target value of 25mm.

[0032] The large-diameter solid-wall pipe produced by the method of this embodiment effectively avoids initial slippage or wrinkling defects in the starting area of ​​its end due to the presence of a high-rigidity anchoring ring. Compared with the traditional winding method using constant process parameters throughout, the pipe produced by this embodiment shows an average increase of approximately 8% in burst strength during hydrostatic burst testing. Simultaneously, due to the use of a higher winding speed in the main body section, the overall production efficiency is increased by approximately 15%. The traditional winding method described in the above embodiment, used to manufacture pipes of the same specifications with a target wall thickness of 25mm, involves spiral winding on the mandrel surface from the beginning at a winding angle of ±55°, a constant tension of 10N, and a constant linear speed of 0.18m / s until the wall thickness reaches 25mm. During this process, there is no distinction between the starting, transition, and main body sections, and no circumferential constraint layer.

[0033] Example 2: An enhanced winding method for large-diameter solid-wall tubes integrating alternating angles and three-dimensional networks; Based on the three-segment framework established in Example 1, this embodiment integrates two reinforcement technologies: alternating angle lay-up and three-dimensional fiber network construction, which significantly improves the interlayer toughness and axial mechanical properties of the pipeline.

[0034] Step 1, initial anchoring section winding: the specific operation and process parameters are the same as in Example 1.

[0035] Step 2, transition and stabilization winding: This phase incorporates two important enhancements based on Example 1: First, progressive layering with alternating angles: When performing ±55° spiral winding, a progressive layup method of 3 layers per group is adopted. Specifically, the first layer within a group is wound at an angle of 54°, the second layer at 55°, and the third layer at 56°. This pattern of 54°, 55°, and 56° is then repeated for subsequent winding. A periodic layup method with a small amplitude of ±1° is used around the target angle reference value of ±55°, breaking the traditional completely parallel interlayer interface and forming a microscopic mechanical interlocking structure.

[0036] Second, synchronous three-dimensional fiber network construction: Simultaneously with the aforementioned spiral winding, a separate axial fiber laying device is activated. This device impregnates a bundle of high-strength carbon fibers with resin and lays them directly and synchronously into the forming wet spiral fiber layer at approximately 20mm intervals along the axial direction at 0°. The axial and spiral fibers interweave and combine within the resin matrix.

[0037] The specific implementation method for constructing a three-dimensional fiber network is as follows: Method 1: Online synchronous yarn laying; This is achieved by adding an axial yarn-laying guide head that is linked to or independently programmed and controlled by the main winding head. This guide head is located approximately 50-200mm behind the winding point. A pressure roller with a pressure of 0.5-2.0 bar directly presses the resin-impregnated axial fibers into the uncured helical fiber layer, ensuring embedding and the formation of an interwoven structure. The CNC system of the main winding machine needs to synchronize the helical winding speed with the axial yarn-laying speed. The ratio of the axial yarn-laying speed to the mandrel rotational linear speed is controlled between 0.95 and 1.05 to ensure accurate placement of the axial fibers at the set spacing.

[0038] Method 2: Precast concrete strip laying; As an alternative, a prefabricated tape laying method can also be used. Specifically, multiple axial fibers are arranged in parallel at a set interval and fixed on the release paper using lightly cured resin or a peelable film to form an axial rib prefabricated tape with a width equivalent to the pipe section. During the spiral winding process, the prefabricated tape is laid on the surface of the wet spiral fiber layer and pressed into the spiral layer by an active pressure roller with a pressure of 0.3-1.0 bar. After winding, the release paper can be removed before curing or retained as an inner protective layer.

[0039] Step 3: High-efficiency winding of the main body section: The process parameters and operation are the same as in Example 1. The angle alternating lay-up pattern can also be selectively applied in the main body section.

[0040] The pipe manufactured in this embodiment has an interlaminar shear strength that is more than 25% higher than that of the product in Example 1, effectively suppressing the delamination failure mode. Due to the direct reinforcement effect of the axial fibers in the three-dimensional fiber network, the axial tensile strength and bending stiffness of the pipe are increased by about 30% and 40% respectively compared with the product in Example 1.

[0041] Example 3: A high-toughness winding method for flexible interfaces and localized reinforcement in large-diameter solid-walled tubes; This embodiment focuses on maximizing the damage tolerance, toughness, and local pressure-bearing capacity of pipelines under harsh working conditions such as potential impacts and pressure fluctuations.

[0042] Construction of flexible interface layer: After completing the resin-rich inner liner layer on the surface of the core mold with a thickness of 1.5 mm, fiber winding is not performed first. Instead, a special resin thin layer of about 0.3 mm thickness is uniformly coated on the inner liner surface using a scraper roller. The resin matrix premixes about 20% by volume of polyurethane elastomer microspheres with a particle size of 50-100 μm and 5% of short-cut para-aramid fibers with a length of 6 mm. This layer serves as the first flexible stress buffer interface.

[0043] Step 1, Initial anchoring section winding: After the flexible interface layer has cured to the finger-dry state, the initial anchoring section is wound, and the process parameters are the same as in Example 1.

[0044] Step 2, transition and stabilization winding: When the fiber winding reaches approximately 32.5% of the total target thickness, for example, when the target thickness is 25 mm, at a position of approximately 8.125 mm, the fiber winding is paused. A controlled spraying system is then used to apply a thin layer of resin rich in chopped flexible fibers to the surface of the current winding layer. The chopped flexible fibers can be chopped nylon fibers. The subsequent spiral winding is then resumed.

[0045] The term "rich in" refers to the volumetric addition of elastomer microparticles in the resin matrix being 15%-30%, and the volumetric addition of chopped flexible fibers being 3%-8%. The elastomer microparticles are preferably polyurethane, rubber, or thermoplastic elastomer microspheres with a particle size range of 50-150 μm, and the chopped flexible fibers are preferably aramid fibers, nylon fibers, or ultra-high molecular weight polyethylene fibers with a length of 3-12 mm.

[0046] The flexible interface layer can be formed by pre-mixing the above-mentioned elastomer particles and chopped fibers with a resin system to form a special adhesive, and then applying it to the surface of the mandrel or the wound layer by means of scraping, spraying or roller coating. The resin system can be epoxy resin or unsaturated polyester resin.

[0047] Step 3, winding of the main high-efficiency section: process parameters and operation are the same as in Example 1.

[0048] Step 4, local circumferential reinforcement section winding: At both ends of the pipe designed for socket connection, a 1-meter range is marked as a high-stress area. After the main section is wound and cured, the winding machine is positioned in this area and wound at an 88° angle with a tension of 13N, which is 130% of the rated tension. An additional 6 layers of pure circumferential winding are then performed to form a significant local thickening and reinforcement zone.

[0049] The pipe manufactured in this embodiment exhibits excellent toughness. Drop hammer impact tests show that the energy required for its failure is more than 50% higher than that of traditional homogeneous wound pipes. The local reinforcing rings at both ends of the pipe increase its pressure-bearing capacity by 15% compared to the average value of the pipe body, greatly ensuring the reliability of the connection parts. The built-in flexible interface layer can effectively passivate the crack tip, allowing the pipe to exhibit a more obvious plastic deformation stage before final failure, significantly enhancing its safety warning capability.

[0050] The above embodiments illustrate the specific applications and combinations of the large-diameter solid-wall tube winding method of the present invention under different performance requirements. Those skilled in the art will understand that the above embodiments are merely examples to clearly illustrate the technical solution of the present invention and are not intended to limit the invention. In practical applications, the winding angle, tension, linear velocity, and layup method of each stage—the initial anchoring section, the transition stabilization section, and the main high-efficiency section—can be combined and optimized according to the specific service requirements of the final product. Furthermore, one or more reinforcing technical features, such as a flexible interface layer, a three-dimensional fiber network, or a local circumferential reinforcement section, can be selectively introduced. This modular, programmable, and segmented progressive winding concept enables the present invention to flexibly and efficiently manufacture large-diameter, high-performance composite material solid-wall tubes with precisely customized performance, effectively overcoming the inherent defects of traditional homogeneous winding methods.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method for winding a large-diameter solid-walled tube, characterized in that, Includes the following steps: Step 1, Initial anchoring section winding: Continuously wind 3-6 layers circumferentially on the mandrel surface at a winding angle of 85° to 90°, with a first tension and a first linear velocity to form the initial reinforcing ring; the first tension is 110% to 120% of the rated tension, and the first linear velocity does not exceed 50% of the maximum design linear velocity; Step 2, Transition Stabilization Section Winding: Above the initial anchoring section, spiral winding is performed at a winding angle of ±55°, a second tension, and a second linear speed until the pipe wall thickness reaches 60% to 70% of the target thickness; the second tension is 95% to 105% of the rated tension; Step 3, High-efficiency winding of the main body: On the transition stable section, spiral winding is performed with a third winding angle, the rated tension and the third linear speed until the target wall thickness is reached; the third winding angle is 54° to 56° and the third linear speed is greater than or equal to 80% of the maximum design linear speed.

2. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, In the second step of the transition stabilization winding, after each predetermined number of spiral layers are wound, at least one circumferential winding layer is inserted as a constraint layer.

3. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, The rated tension is determined based on 5% to 10% of the breaking strength of the reinforcing fiber used.

4. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, In at least one stage of the transitional stable section winding in step two and the main high-efficiency section winding in step three, an alternating progressive layup method is adopted: with 2 to 4 layers as a group, the winding angle of adjacent layers within the group alternates between 1 degree and 3 degrees above the target angle reference value.

5. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, After completing step three, the main high-efficiency segment winding is completed, the following steps are also included: Step 4, Local Circumferential Reinforcing Section Winding: In the predetermined high-stress area of ​​the pipeline, an additional 3-6 layers of pure circumferential winding are performed with a winding angle of greater than or equal to 85 degrees and a tension higher than the rated tension to form a local reinforcing ring.

6. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, Before the start of the initial anchoring section winding in step one, or during the transition stabilization section winding in step two, the construction step of introducing a flexible interface layer is introduced: Apply a thin layer of resin rich in elastomer microparticles or chopped flexible fibers to the surface of the already wound fiber layer.

7. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, In the second step of the transition and stabilization winding, the construction of a three-dimensional fiber network is carried out simultaneously: while spiral winding, one or more continuous axial fibers or large-angle fibers are directly laid and embedded into the spiral fiber layer being wound.

8. The winding method for a large-diameter solid-walled tube according to claim 1, characterized in that, In the second step of the transition stabilization winding, the predetermined number of winding layers is 10 layers, and the inserted circumferential winding layer is 1 layer.

9. A large-diameter solid-walled pipe, characterized in that, It is made by the winding method of any one of claims 1 to 8 for a large-diameter solid-wall tube.

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