Hollow reinforced rib reinforced composite pipe and method of making same

Abstract

The present application relates to the technical field of composite material reinforced pipeline, in particular to a hollow reinforcing rib reinforced composite pipeline and a preparation method thereof. The hollow reinforcing rib reinforced composite pipeline comprises a pipeline body and a hollow reinforcing rib, the hollow reinforcing rib is spirally wound outside the pipeline body, and the pipeline body and the hollow reinforcing rib are integrally formed. The hollow reinforcing rib reinforced composite pipeline does not need quartz sand filler, is light in weight, high in rigidity, the reinforcing rib is combined with the pipe wall of the pipeline body through spiral winding to realize interface combination, and can be continuously integrally formed.

Description

Technical Field

[0001] This invention relates to the field of composite material reinforced pipe technology, and more specifically, to hollow reinforced composite pipe and its preparation method. Background Technology

[0002] In existing technologies, to improve the ring stiffness of fiberglass pipes, silica sand is typically added to the resin to reduce costs and increase pipe stiffness. However, the addition of silica sand significantly increases the pipe's weight, reduces its specific strength, and adversely affects the long-term corrosion resistance and fatigue resistance of the fiberglass pipe. Furthermore, the silica sand layer is prone to cracking under impact, leading to the overall failure of the fiberglass pipe.

[0003] To address the above problems, existing technologies have employed structures using online synchronous winding of circumferential solid reinforcing ribs. However, these methods typically suffer from the following issues: 1. The fabrication process for circumferential reinforcing ribs is discontinuous. When winding each reinforcing rib, the winding material must be hung on the outer surface of the fiberglass pipe body. The fiberglass pipe body rotates once, and one layer of winding material is wound on each layer until the number of layers meets the design height requirements of the reinforcing rib. Finally, the winding material is cut, and the next reinforcing rib is wound in the same manner to obtain a continuously wound reinforcing rib tube. This technology has low production efficiency, high manual intervention in the reinforcing rib fabrication process, many unstable factors in controlling the reinforcing rib spacing, and great difficulty in controlling product quality and performance.

[0004] 2. The reinforcing ribs are solid structures, which consume a lot of material and make it difficult to achieve the optimal balance between lightweight and high strength.

[0005] Therefore, there is an urgent need to develop a lightweight, high-strength, fiber-reinforced composite pipe and its preparation method that can achieve synchronous and integrated molding of the pipe body and reinforcing ribs without the use of quartz sand.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a hollow reinforced composite pipe and its preparation method. The hollow reinforced composite pipe provided by this invention requires no quartz sand filler, is lightweight, has high rigidity, and the reinforcing ribs achieve interfacial bonding with the pipe wall through spiral winding, allowing for continuous integrated molding.

[0008] This invention is implemented as follows: In a first aspect, the present invention provides a hollow reinforcing composite pipe, which includes a pipe body and hollow reinforcing ribs, wherein the hollow reinforcing ribs are spirally wound around the pipe body, and the pipe body and the hollow reinforcing ribs are integrally formed.

[0009] In an optional embodiment, the pipe body includes an inner lining and a structural layer.

[0010] In an optional embodiment, the hollow reinforcing rib includes a thermoplastic single-wall corrugated inner core tube and a thermosetting fiber reinforcement layer disposed outside the thermoplastic single-wall corrugated inner core tube.

[0011] In an optional embodiment, the cross-sectional shape of the hollow reinforcing rib is any one of a circle, a square, a rectangle, and a trapezoid; Preferably, the interior of the hollow reinforcing rib is a hollow cavity.

[0012] In an optional embodiment, the thickness of the above-mentioned thermoplastic hollow threaded inner tube is 0.5-6 mm; The thickness of the thermosetting fiber reinforcement layer is 1-16 mm.

[0013] In a second aspect, the present invention provides a method for preparing the hollow reinforcing composite pipe described in the foregoing embodiments, comprising: forming uncured wet prefabricated hollow reinforcing ribs outside a thermoplastic single-wall corrugated inner core pipe; An inner lining layer and a structural layer are sequentially fabricated outside the pipe core mold to form the uncured pipe body; Uncured wet prefabricated hollow reinforcing ribs are wound around the outside of the uncured structural layer at a certain helical angle, so that the reinforcing rib resin and the structural layer resin fuse and penetrate at the interface, and then are cured simultaneously to form the pipe body and the hollow reinforcing ribs, and the two are integrally formed.

[0014] In an optional implementation, the method includes: using a three-dimensional braiding wet molding process to braid and impregnate the outside of a thermoplastic single-wall corrugated inner core tube with thermosetting resin to form an uncured wet prefabricated hollow reinforcing rib.

[0015] In an optional implementation, the method includes forming a thermoplastic single-wall corrugated inner core tube using a screw extrusion molding process.

[0016] In optional embodiments, curing conditions include: room temperature curing at 20-40°C or infrared heating curing.

[0017] The present invention has the following beneficial effects: (1) Innovative structure and excellent performance: The embodiments of the present invention use hollow reinforcing ribs to replace the quartz sand layer and the circumferential solid reinforcing ribs. While significantly reducing the self-weight of the glass fiber pipe (pure fiber reinforced composite material structure), the hollow structure greatly improves the moment of inertia of the pipe wall section of the glass fiber pipe under the premise of minimizing the increase in weight, thereby greatly improving the ring stiffness and resistance to external pressure of the glass fiber pipe.

[0018] (2) Technological innovation and integrated molding: An online integrated process of "wet winding of pipe body" and "wet prefabrication and synchronous winding of reinforcing ribs" was created. That is, the reinforcing ribs and structural layers achieve interfacial contact in the uncured state of resin, and the resin is bonded at the molecular level, eliminating the interface defects of traditional secondary bonding and forming a true integral structure.

[0019] (3) The preparation method provided in the embodiments of the present invention integrates the prefabrication and spiral winding of the reinforcing ribs into a continuous process flow, from extrusion, weaving, winding to curing in one go, with high production efficiency and good process stability, and is suitable for large-scale industrial production.

[0020] (4) Overall improvement in corrosion resistance: The quartz sand, which is easy to absorb moisture and has a large difference in expansion coefficient with resin, has been abandoned. The whole structure is a dense fiber-reinforced composite material, which makes the long-term corrosion resistance and water resistance of the pipeline more superior. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the cross-sectional interface of the hollow reinforcing composite pipe provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the hollow reinforcing composite pipe provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the hollow reinforcing rib provided in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the hollow reinforced composite pipe provided in Embodiment 1 of the present invention.

[0023] Illustration: 100-Hollow reinforced composite pipe; 1-Pipe body; 2-Hollow reinforcing rib; 2-1-Thermoplastic single-wall corrugated inner core pipe; 2-2-Thermosetting fiber reinforcement layer; 3-Extruder; 4-Three-dimensional braiding machine; 5-Continuous fiber yarn bundle; 6-Resin impregnation tank; 7-Wet prefabricated hollow reinforcing rib; 8-Guiding device; 9-Pipe core mold. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0025] To address the problems of existing sand-filled pipes being heavy and having low specific strength, and the discontinuous manufacturing process, low production efficiency, high material consumption, and difficulty in controlling product quality and performance of existing spiral-wound circumferentially reinforced pipes, this invention provides a hollow-reinforced composite pipe and its manufacturing method that eliminates the need for quartz sand filler, is lightweight, has high rigidity, and features hollow reinforcing ribs 2 that achieve interfacial bonding with the pipe wall through spiral winding, allowing for continuous and integrated molding.

[0026] Specifically, the hollow-reinforced composite pipe 100 provided in this embodiment of the invention includes a pipe body 1 and hollow reinforcing ribs 2, both made of fiber material. The hollow reinforcing ribs 2 have spiral threads on their surface and are spirally wound around the outside of the pipe body 1. This embodiment of the invention uses threaded hollow reinforcing ribs 2 to replace the quartz sand layer and the circumferential solid reinforcing ribs. While significantly reducing the self-weight of the pipe (pure fiber-reinforced composite material structure), the hollow structure greatly increases the moment of inertia of the pipe wall section while minimizing the increase in weight, thereby greatly improving the ring stiffness and resistance to external pressure of the hollow-reinforced composite pipe.

[0027] In this embodiment of the invention, the pipe body 1 and the hollow reinforcing rib 2 are integrally formed. This integral forming eliminates the interface defects of traditional secondary bonding, resulting in a truly integrated structure.

[0028] In this embodiment of the invention, the hollow reinforcing rib 2 includes a thermoplastic single-wall corrugated inner core tube 2-1 and a thermosetting fiber reinforcement layer 2-2 disposed outside the thermoplastic single-wall corrugated inner core tube 2-1. The thermoplastic single-wall corrugated inner core tube 2-1 and the thermosetting fiber reinforcement layer 2-2 are firmly bonded together, and its multidirectional fiber structure provides excellent shear and peel resistance.

[0029] In this embodiment of the invention, the cross-sectional shape of the hollow reinforcing rib 2 is any one of a circle, square, rectangle, and trapezoid; at the same time, the thermoplastic single-wall corrugated inner core tube 2-1 is a plastic corrugated tube with a hollow cavity that has any one of a circle, square, rectangle, and trapezoid, and its dimensions are stable. When it is wound around the surface of the pipe body 1, it has good conformability.

[0030] In this embodiment of the invention, the thickness of the thermoplastic single-wall corrugated inner core tube 2-1 is 0.5-6 mm; the thickness of the thermosetting fiber reinforcement layer 2-2 is 1-16 mm.

[0031] In this embodiment of the invention, the pipe body 1 includes an inner lining layer and a structural layer. That is, the hollow reinforcing ribs 2 are spirally wound around the outside of the structural layer.

[0032] This invention also provides a method for preparing the above-mentioned hollow reinforcing rib 2 reinforced composite pipe, including: An uncured inner lining layer and structural layer are formed outside the pipe core mold 9; the pipe core mold 9 can be an existing purchased pipe core mold 9, such as a steel mold or fiberglass mold with a circular cross section.

[0033] Then, an inner lining and a structural layer are fabricated outside the pipe core mold 9 to form the uncured pipe body 1 (at this time, both the inner lining and the structural layer are in an uncured state). This fabrication process is an existing process, for example, referring to standard GB 51160.

[0034] Thermoplastic single-wall corrugated inner core tube 2-1 is manufactured using a screw extrusion molding process. Specifically, the thermoplastic single-wall corrugated inner core tube 2-1 is obtained by single-layer melt extrusion, vacuum / pneumatic corrugation molding, and continuous cooling and shaping through a plastic extruder 3, resulting in round, square, rectangular, or trapezoidal shapes. More specifically, thermoplastic plastic (such as PP, PE, PA, etc.) granules are added to the extruder 3, melted and plasticized, and then continuously extruded through an annular die with a round, square, rectangular, or trapezoidal cross-section. After vacuum / pneumatic corrugation molding and preliminary cooling and shaping, a thermoplastic single-wall corrugated inner core tube 2-1 with a stable cross-sectional shape and a hollow cavity is formed.

[0035] The embodiments of the present invention allow for adjustments to the extrusion die to change the cross-sectional shape and size of the reinforcing ribs, thus achieving design flexibility.

[0036] Subsequently, uncured wet prefabricated hollow reinforcing ribs 7 are formed on the outside of the thermoplastic single-wall corrugated inner core tube 2-1. Specifically, uncured wet prefabricated hollow reinforcing ribs 7 are formed by weaving and impregnating thermosetting resin on the outside of the thermoplastic single-wall corrugated inner core tube 2-1 using a three-dimensional braiding wet molding process.

[0037] In this embodiment of the invention, a three-dimensional weaving process is used to firmly bond the thermosetting fiber reinforcement layer 2-2 to the thermoplastic single-wall corrugated inner core tube 2-1, and its multi-directional fiber structure provides excellent shear and peel resistance.

[0038] Specifically, the thermoplastic single-wall corrugated inner core tube 2-1 prepared above is guided through a three-dimensional braiding machine 4. The three-dimensional braiding machine 4 weaves continuous fiber yarn bundles 5 around the circumference of the thermoplastic single-wall corrugated inner core tube 2-1, while simultaneously impregnating the fibers with resin through a resin impregnation tank 6 to form a "wet" prefabricated hollow reinforcing rib 2. At this time, the resin system of the reinforcing rib is compatible with the resin system of the structural layer of the pipe body 1 and their curing characteristics are synchronized.

[0039] Furthermore, in this embodiment of the invention, the mechanical properties of the reinforcing rib can be adjusted by changing the number of braided layers and the fiber type.

[0040] Uncured, wet-state prefabricated hollow reinforcing ribs 7 are wound around the outside of the uncured structural layer. Specifically, through a guiding device 8, the uncured, wet-state prefabricated hollow reinforcing ribs 7 are simultaneously wound onto the outer surface of the uncured pipe body 1 structural layer at a certain helical angle. Under pressure, the reinforcing ribs achieve interfacial contact with the structural layer, and the uncured resins of both fuse and permeate each other. This embodiment of the invention, through an online integrated process of "wet winding of the pipe body 1" and "wet prefabrication-synchronous winding of reinforcing ribs," achieves interfacial contact between the reinforcing ribs and the structural layer in the uncured resin state. The resin bonds at the molecular level, eliminating the interfacial defects of traditional secondary bonding and forming a truly integral structure.

[0041] The aforementioned helix angle can be designed according to requirements. In this embodiment of the invention, different load requirements can be adapted by changing the helix winding angle, resulting in extremely high design flexibility.

[0042] In this embodiment of the invention, the tube blank formed by the above winding is cured, so that the resin of the uncured inner lining layer, structural layer and uncured wet prefabricated hollow reinforcing rib 7 (that is, the uncured thermosetting fiber reinforcing layer 2-2) is cured simultaneously to form a complete, dense, and firmly bonded hollow reinforcing rib 2 reinforced composite pipe. After curing, the final product is obtained by trimming and cutting.

[0043] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0044] Example 1 See Figures 1-3 This invention provides a hollow-reinforced composite pipe 100, comprising a pipe body 1 and hollow reinforcing ribs 2. The pipe body 1 includes an inner lining layer and a structural layer; the hollow reinforcing ribs 2 are spirally wound around the structural layer. The hollow reinforcing ribs 2 include a thermoplastic single-wall corrugated inner core tube 2-1 and a thermosetting fiber reinforcement layer 2-2 disposed outside the thermoplastic single-wall corrugated inner core tube 2-1. The thickness of the thermoplastic hollow threaded inner core tube 2-1 is 1 mm; the thickness of the thermosetting fiber reinforcement layer 2-2 is 4 mm.

[0045] This embodiment provides a method for preparing a hollow reinforcing rib-reinforced composite pipe, including: See Figure 4An inner lining layer and a structural layer are sequentially fabricated outside the pipe core mold 9 to form an uncured pipe body 1. Specifically, the prepared unsaturated resin liquid is first uniformly coated onto the pipe core mold 9, and then the glass fiber surface mat and glass fiber chopped strand mat, sewn braided fabric or sprayed yarn are used to make the inner lining layer through hand lay-up, winding or spraying processes. Subsequently, the structural layer is made by winding glass fiber yarn.

[0046] Thermoplastic PP granules are added to extruder 3, melted at 200℃, and continuously extruded through an annular die with a trapezoidal cross section. After vacuum corrugation forming and initial cooling and shaping by water spraying at 20℃, a thermoplastic single-wall corrugated inner core tube 2-1 with a stable cross-sectional shape and a hollow cavity is formed.

[0047] The thermoplastic single-wall corrugated inner core tube 2-1 is guided through a three-dimensional braiding machine 4. The three-dimensional braiding machine 4 weaves continuous fiber yarn bundles 5 around the circumference of the thermoplastic single-wall corrugated inner core tube 2-1, while simultaneously impregnating the fibers with resin through a resin impregnation tank 6, forming uncured, wet, prefabricated hollow reinforcing ribs 7. The resin system of these reinforcing ribs is compatible with the resin system of the structural layer of the pipe body 1, and their curing characteristics are synchronized.

[0048] Uncured wet precast hollow reinforcing ribs 7 are simultaneously wound onto the outer surface of the uncured pipe body 1 structural layer via a guide device 8 at a 75-degree helical angle.

[0049] The composite pipe is formed by curing at room temperature to create the hollow reinforcing rib 2.

[0050] Examples 2-4 Examples 2-4 also provide a hollow reinforcing rib 2 reinforced composite pipe, whose structure is the same as that of the hollow reinforcing rib 2 reinforced composite pipe provided in Example 1, the only difference being that some thicknesses are different, as detailed below: Example 2: The thickness of the thermoplastic single-wall corrugated inner core tube 2-1 is 1.2 mm; the thickness of the thermosetting fiber reinforcement layer 2-2 is 6 mm.

[0051] Example 3: The thickness of the thermoplastic hollow threaded inner core tube 2-1 is 1.5 mm; the thickness of the thermosetting fiber reinforcement layer 2-2 is 8 mm.

[0052] Example 4: The thickness of the thermoplastic hollow threaded inner core tube 2-1 is 2.0 mm; the thickness of the thermosetting fiber reinforcement layer 2-2 is 10 mm.

[0053] Comparative Example 1 This comparative example provides a traditional quartz sand-filled composite pipe with the same nominal diameter and pressure rating as Example 1. It includes an inner lining layer and a sand-filled structural layer. The sand-filled structural layer is formed by winding unsaturated polyester resin, quartz sand and glass fiber. The quartz sand content is 35% by mass. It does not contain hollow reinforcing ribs. The preparation process is carried out in accordance with GB / T 21238 "Glass Fiber Reinforced Plastic Sand-Filled Pipe".

[0054] Comparative Example 2 This comparative example provides a circumferentially wound solid reinforcing composite pipe with the same cross-sectional dimensions as in Example 1. The spacing of the circumferential reinforcing ribs is the same as the pitch in Example 1. The only difference is that the hollow reinforcing ribs are replaced with solid thermosetting fiber reinforcing ribs, that is, the thermoplastic single-wall corrugated inner core tube is cancelled, and the reinforcing ribs are solid structures formed by pure glass fiber impregnation with resin and curing.

[0055] Comparative Example 3 This comparative example provides a step-by-step molded hollow reinforcing composite pipe, which has the same structure as Example 1, except for the manufacturing process: first, the pipe body is cured and molded, and then the pre-made uncured hollow reinforcing ribs are wound around the outer wall of the pipe body to achieve the winding of the reinforcing ribs.

[0056] Performance testing To verify the technical effect of the present invention, the composite pipes obtained in Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests. The test environment temperature was 23±2℃ and the relative humidity was 50±5%. The specific test methods and results are as follows: 1. Testing Methods

[0057] 2. Test Results Table 1 Performance test results of the examples and comparative examples

[0058] 3. Results Analysis As shown in Table 1: (1) Compared with Comparative Example 1, Embodiments 1-4 of the present invention significantly reduce the weight of the pipe while greatly improving the ring stiffness. This is because the hollow structure of the hollow reinforcing ribs effectively increases the moment of inertia of the pipe wall section, achieving a balance between "lightweight and high stiffness".

[0059] (2) Compared with Comparative Example 2, the peel strength of the embodiment of the present invention is higher, indicating that the composite structure of thermoplastic single-wall corrugated inner tube and thermosetting fiber reinforcement layer in hollow reinforcing rib has better shear resistance and less material consumption under the same stiffness.

[0060] (3) Compared with Comparative Example 3, the interface peel strength of the present invention embodiment is improved by more than 267%, which fully demonstrates the integrated process advantage of "wet winding of pipe body + wet prefabrication of reinforcing rib - synchronous winding": the uncured resin is fused together at the molecular level, eliminating the interface defects of traditional secondary bonding, forming a true integral structure, and greatly improving the interlayer bonding force.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hollow reinforced composite pipe, characterized in that, It includes a pipe body and hollow reinforcing ribs, the hollow reinforcing ribs being spirally wound around the pipe body, and the pipe body and the hollow reinforcing ribs being integrally formed.

2. The hollow reinforced composite pipe according to claim 1, characterized in that, The pipe body includes an inner lining layer and a structural layer.

3. The hollow reinforced composite pipe according to claim 1, characterized in that, The hollow reinforcing rib includes a thermoplastic single-wall corrugated inner core tube and a thermosetting fiber reinforcement layer disposed outside the thermoplastic single-wall corrugated inner core tube.

4. The hollow reinforced composite pipe according to claim 2, characterized in that, The cross-sectional shape of the hollow reinforcing rib can be any one of the following: circular, square, rectangular, and trapezoidal. Preferably, the interior of the hollow reinforcing rib is a hollow cavity.

5. The hollow reinforced composite pipe according to claim 3, characterized in that, The thickness of the aforementioned thermoplastic single-wall corrugated inner core tube is 0.5-6 mm; The thickness of the thermosetting fiber reinforcement layer is 1-16 mm.

6. A method for preparing a hollow reinforced composite pipe according to claim 1, characterized in that, include: Uncured, wet, prefabricated hollow reinforcing ribs are formed on the outside of the thermoplastic single-wall corrugated inner core tube; An inner lining layer and a structural layer are sequentially fabricated outside the pipe core mold to form the uncured pipe body; Uncured wet prefabricated hollow reinforcing ribs are wound around the uncured structural layer at a helical angle, allowing the reinforcing rib resin and the structural layer resin to fuse and penetrate at the interface, and then cured simultaneously to form the pipe body and the hollow reinforcing ribs, which are integrally formed.

7. The preparation method according to claim 6, characterized in that, include: An uncured, wet, prefabricated hollow reinforcing rib is formed by weaving and impregnating the outside of a thermoplastic single-wall corrugated inner core tube with thermosetting resin using a three-dimensional braiding wet molding process.

8. The preparation method according to claim 6, characterized in that, include: Thermoplastic single-wall corrugated inner core tubes are formed using screw extrusion molding.

9. The preparation method according to claim 6, characterized in that, Curing conditions include: room temperature curing at 20-40℃ or infrared heating curing.

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