Filling type bamboo winding composite pipeline and preparation method

Abstract

The invention discloses a filling type bamboo winding composite pipeline and a preparation method thereof, and belongs to the technical field of bamboo winding pipelines. The pipeline comprises a lining layer, a structural layer and an outer protective layer from inside to outside. The lining layer comprises unsaturated polyester resin, filler, bamboo fiber non-woven fabric, knitted felt and cotton thread gridding cloth; the structural layer comprises bamboo splits, unsaturated polyester resin, filler and glass fiber gridding cloth; the outer protective layer comprises unsaturated resin and filler; the unsaturated resin used in each layer is of the same type, and the filler is calcium powder. According to the method, through the four core steps of winding, curing, finishing and demolding, laying and dipping of multiple layers of materials are synchronously conducted through the material spraying process, integration of a lining layer and a structural layer resin system is achieved, the layering and falling problems caused by inconsistent resin shrinkage performance of a traditional pipeline are thoroughly solved, the material and labor cost is reduced, and the production efficiency is improved. And by improving the pipeline connecting structure, the loading and transporting efficiency and the construction efficiency are further improved, and the method is suitable for large-scale standardized production.

Description

Technical Field

[0001] This invention belongs to the field of bamboo-wound pipe preparation technology, specifically relating to a filled bamboo-wound composite pipe and its preparation method. Background Technology

[0002] Bamboo-wound composite pipes, a type of bio-based composite material pipe using renewable bamboo as the matrix, have been widely adopted in municipal drainage, farmland irrigation, and integrated pipe corridors due to their advantages such as being green and environmentally friendly, lightweight and high-strength, and utilizing resources sustainably. These pipes typically use bamboo strips or non-woven fabric as reinforcing materials and resin as the matrix, and are formed on a mandrel through a winding process, creating a composite structure that includes an inner lining layer, a structural layer, and an outer protective layer.

[0003] However, existing bamboo-wound composite pipe technology still faces several key technical bottlenecks in actual production and application. Firstly, regarding the material system, current processes often employ different resin systems for the inner lining and structural layers. For example, the inner lining often uses unsaturated polyester resin to ensure a smooth inner wall and corrosion resistance, while the structural layer uses urea-formaldehyde resin to reduce costs and meet strength requirements. Due to differences in the curing shrinkage rate, coefficient of thermal expansion, and interfacial bonding performance of the two resins, delamination, debonding, and even detachment easily occur between the inner lining and structural layers during pipe use, severely affecting the long-term service performance and reliability of the pipe.

[0004] Secondly, in terms of production processes, to meet the special structural and sealing requirements of pipe sockets and spigots, existing technologies require additional manual intervention at the socket, such as wrapping polyester film, pressing non-woven fabric lining with speed-reducing rollers, and alternately increasing the amount of bamboo strips. At the spigot, a thickened structural layer needs to be wrapped separately, and the O-ring grooves require time-consuming finishing and polishing. These processes not only increase manual intervention, leading to low production efficiency, but also significantly increase production costs.

[0005] In addition, in terms of logistics and transportation, due to the inconsistency between the pipe diameters of the socket and spigot parts, the pipes need to be transferred multiple times, staggered, and padded with cushioning materials during loading and transportation. The loading time for a single vehicle can be as long as 2 to 3 hours, which seriously restricts the logistics efficiency and market response speed of the products.

[0006] While some patented technologies have attempted to address the aforementioned issues, their effectiveness has been limited. For example, Chinese patent CN110682556A discloses a method for manufacturing bamboo winding tubes using unsaturated resin as the main adhesive, but it fails to effectively solve the core problem of insufficient interfacial bonding between the resin and bamboo. Chinese patent CN111978705A discloses a resin composition, but its filler system is relatively simple, making it difficult to simultaneously ensure both the mechanical strength of the structural layers and the strong bonding between the interlayer interfaces. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a filled bamboo-wound composite pipe and its preparation method, which integrates the inner lining layer and the structural layer with resin, simplifies the production process, improves product consistency and production efficiency, and reduces overall costs.

[0008] Therefore, the purpose of this invention is to provide a filled bamboo-wound composite pipe, which includes an inner lining layer, a structural layer and an outer protective layer from the inside out. The inner lining layer comprises unsaturated resin, filler, bamboo fiber nonwoven fabric, knitted felt, and cotton mesh fabric; The structural layer comprises bamboo strips, unsaturated resin, filler, and fiberglass mesh. The outer protective layer comprises unsaturated resin and filler; The unsaturated resins in the inner lining, structural layer and outer protective layer are the same type of unsaturated polyester resin. The filler is calcium powder, and its mass content is 40% to 60% of the unsaturated resin.

[0009] Furthermore, the unsaturated polyester resin is one of isophthalic unsaturated polyester resin, vinyl ester resin, or bisphenol A resin; its properties meet the following requirements: viscosity at 25°C is 400-800 mPa·s, solid content is ≥55%, gel time at 25°C is 10-60 min, tensile strength is ≥60 MPa, and elongation at break is ≥3.0%.

[0010] Furthermore, the cotton mesh fabric has a warp and weft density of 2.5 to 6.0 threads / 10mm, a unit area mass of ≤40g / ㎡, a transverse and longitudinal breaking elongation of ≤5%, and a warp breaking strength of ≥1500N; And / or, the fiberglass mesh fabric has a weight of 160g per square meter, a width of 25cm, a transverse and longitudinal alkali-resistant tensile strength ≥1000N / 50mm, and a transverse and longitudinal alkali-resistant tensile strength retention rate ≥50%.

[0011] Furthermore, the connection steps between adjacent single pipe sections are as follows: insert the ends of the two pipes into an annular sleeve, and a sealing ring is embedded in the sleeve through a dovetail groove. The inner side of the sealing ring fits against the outer wall of the pipe to achieve pipe connection.

[0012] Furthermore, the annular sleeve is made of fiberglass, and the sealing ring is made of EPDM rubber.

[0013] This invention also discloses a method for preparing the above-mentioned filled bamboo-wound composite pipe, comprising the following steps: S1, Entanglement: S1.1 Inner Liner Winding: A polyester film, a bamboo fiber nonwoven fabric impregnated with a resin mixture, a knitted felt, and a cotton mesh fabric are sequentially wound around the surface of a rotating mandrel to form an inner lining; wherein, the resin mixture is a pre-mixed mixture of unsaturated resin, filler, and accelerator, and is mixed with a curing agent in proportion and then coated during the winding of the bamboo fiber nonwoven fabric. S1.2 Structural layer forming: On the surface of the inner lining layer, a structural layer is formed by alternately winding glass fiber mesh and circumferential bamboo strips by applying material; S1.3, Outer protective layer treatment: A resin mixture is coated onto the surface of the structural layer to form an outer protective layer; S2. Curing: Place the completed winding mandrel in the curing device and heat and cure it while rotating; S3. Trimming: Trim the dimensions of both ends of the cured pipe. S4. Demolding: Remove the core mold from the cured and trimmed pipe to obtain the filled bamboo-wound composite pipe.

[0014] Furthermore, in step S1.1, when winding the bamboo fiber nonwoven fabric, the flow ratio of the resin mixture to the curing agent is (3-5):10.

[0015] Furthermore, in step S1.1, the method for preparing the resin mixture is as follows: unsaturated resin, filler and accelerator are stirred at 1500 r / min for 10 to 20 minutes at 22 to 25°C.

[0016] Furthermore, in step S1.2, the structural layer winding is carried out in an alternating direction from the tail end to the front end and then from the front end to the tail end until the designed number of layers is reached.

[0017] Furthermore, in step S2, the curing time is 15 to 30 minutes.

[0018] The advantages and positive effects of this invention are: The filled bamboo-wound composite pipe of this invention reduces the use of axial bamboo strips, structural layer resin, reactants, glass fiber filaments, and bamboo powder in traditional bamboo-wound pipes, while increasing the use of new materials such as calcium powder and glass fiber mesh, and reducing the number of bamboo strip lay-ups. Existing bamboo-wound pipes involve six core steps according to their process requirements: lining preparation, structural layer winding, curing, outer protection fabrication, finishing, and demolding. This invention optimizes this to four core steps: winding, curing, finishing, and demolding.

[0019] The material supply method of this invention is optimized from the existing coating + impregnation production mode to a coating mode, which effectively controls the amount of resin used. Attached Figure Description

[0020] Figure 1This is a cross-sectional schematic diagram of the bamboo-wound pipe of the present invention.

[0021] Figure 2 This is a rendering of the bamboo-wound pipe of the present invention. Figure 3 This is a physical rendering of an existing bamboo-wound pipe technology; Figure 4 This is a process flow diagram of the bamboo-wound pipe of the present invention; Figure 5 This is a schematic diagram of the structure of the annular sleeve and the sealing ring.

[0022] In the diagram, 1 is the inner lining layer; 2 is the structural layer; 3 is the outer protective layer; 4 is the annular sleeve; and 5 is the sealing ring. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below; obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 This invention provides a filled bamboo-wound composite pipe, comprising, from the inside out, an inner lining layer 1, a structural layer 2, and an outer protective layer 3; the inner lining layer 1 comprises unsaturated resin, filler, bamboo fiber nonwoven fabric, knitted felt, and cotton mesh fabric; the structural layer 2 comprises bamboo strips, unsaturated resin, filler, and glass fiber mesh fabric; the outer protective layer 3 comprises unsaturated resin and filler; it also includes an accelerator and a curing agent, wherein the accelerator is preferably an unsaturated resin accelerator (purple water); and the curing agent is preferably V388; In this embodiment, all unsaturated resins in the inner lining layer 1, structural layer 2, and outer protective layer 3 are of the same type, preferably one of isophthalic unsaturated polyester resin, vinyl ester resin, or bisphenol A resin, with isophthalic unsaturated polyester resin being more preferable, as it meets production requirements while reducing costs. This resin primarily functions to adhere the bamboo strips, and after bonding with the bamboo strips, it forms a bamboo-based composite material with higher strength.

[0025] The performance requirements for unsaturated resins are as follows: 1) Viscosity at 25℃: 400-800 mPa·s; 2) Solid content: ≥55%; 3) Gel time at 25℃: 10-60 min; 4) Tensile strength: ≥60 MPa; 5) Elongation at break: ≥3.0%.

[0026] The fillers are all calcium powder, with a mass content of 40-60% of the unsaturated resin. Adding calcium powder to the resin can fully fill the pores between the bamboo strips, enhance the overall ring stiffness of the pipe, and at the same time reduce costs.

[0027] like Figure 2 The unsaturated resin and filler fully fill the gaps during the bamboo winding process, resulting in a dense overall pipe structure without delamination or voids. The pipe's main mechanical properties, such as ring stiffness and tensile strength, are significantly improved. The inner lining and structural layers are integrated, completely resolving quality issues like delamination and detachment during use. Furthermore, the curing time is optimized from the existing 3-5 hours to 20-30 minutes.

[0028] like Figure 3 In existing technologies, the inner lining layer is mainly composed of unsaturated resin, bamboo fiber nonwoven fabric, and knitted felt, the structural layer is mainly composed of bamboo strips and amino resin, and the outer protective layer is mainly composed of unsaturated resin and color paste. Because the properties of the inner lining resin and the structural layer resin used in production are incompatible, and the shrinkage properties of the inner lining resin and the structural layer resin are inconsistent, phenomena such as delamination and detachment of the inner lining layer and the structural layer may occur during use, affecting product quality.

[0029] Preferably, the performance requirements of the bamboo fiber nonwoven fabric are as follows: 1) thickness 0.3-0.36 mm; 2) moisture content 6-17%; 3) longitudinal elongation <30%; 4) transverse elongation <200%.

[0030] Preferably, the performance requirements of the cotton thread mesh fabric are as follows: 1) Warp and weft density: 2.5~6.0 threads / 10mm; 2) Unit area mass ≤40g / ㎡; 3) Elongation at break in both the transverse and longitudinal directions ≤5%; 4) Warp breaking strength ≥1500N. The cotton thread mesh fabric is mainly used to wrap bamboo strips for conveyor belt feeding; the fiberglass mesh fabric is mainly used to replace axial bamboo strips, providing axial tensile strength.

[0031] Preferably, the performance requirements of the fiberglass mesh are as follows: 1) weight per square meter: 160g; 2) width: 25cm; 3) transverse and longitudinal alkali-resistant tensile strength ≥1000N / 50mm; 4) transverse and longitudinal alkali-resistant tensile strength retention rate ≥50%. Its main function is to replace axial bamboo strips, providing axial tensile strength and enhancing the axial tensile strength of the pipe.

[0032] The performance requirements for the knitted felt are as follows: 1) Unit area mass: 380±5g / m2, width: 260±5mm; 2) Combustible content: tested according to GB / T9914.2, the combustible content should be 2.0%-8.0%; 3) Moisture content: tested according to GB / T9914.1, the moisture content should be ≤0.5%; 4) Tensile breaking strength: tested according to GB / T6006.2, longitudinal ≥150N; transverse ≥60N; effective sample size: 150mm*200mm; resin impregnation rate: according to Appendix A of GB / T17470-2007, the resin impregnation rate (25℃) ≤250S.

[0033] The number of winding layers varies depending on the pipe diameter and ring stiffness. Larger pipe diameters require more winding layers, and higher ring stiffness also necessitates more layers. For example, consider a pipe with an inner diameter of 500mm and a ring stiffness of 10000N / ㎡: The inner lining layer comprises: one layer of bamboo fiber nonwoven fabric, one layer of knitted felt, and one layer of cotton mesh fabric; the structural layer comprises five layers of circumferential bamboo strips and five layers of fiberglass mesh fabric.

[0034] The preparation method of the filled bamboo-wound composite pipe of the present invention includes the following steps: S1, Entanglement: S1.1, Inner Liner Winding 1) Polyester film laying: Move the winding equipment to the front end of the mandrel, set the winding pitch to 180mm and the overlap width to 20mm; start the mandrel rotation and wind the polyester film from the front end to the end; cut the film and fix it after winding to the end. 2) Location markers: Using the mold socket end as a reference, mark the winding start line 1000mm away from the end, and mark the winding end line 10000mm along the axial direction to provide an accurate position reference for subsequent material laying.

[0035] 3) Bamboo fiber nonwoven fabric winding: Move the coating device above the center line of the core mold, with the edge of the coating plate ≤20mm from the surface of the core mold; the mixture is discharged from the resin mixing tank and mixed with the curing agent before entering the coating device, and the flow ratio of the two is (3~5):10; The material is applied from the end of the winding process towards the beginning of the process, and the bamboo fiber nonwoven fabric is wound simultaneously. By controlling the uniformity of the mixture distribution, the fiber felt is ensured to be completely impregnated. It should be noted that the materials entering the coating device need to be mixed and stirred in the resin mixing tank beforehand. Specifically, unsaturated resin and fillers and accelerators in the resin mixing tank are added to form a resin mixture. Stirring is started, the stirring temperature is 22-25℃, the stirring time is 10-20 minutes, and the speed is 1500 r / min to ensure that the mixture is stirred evenly. The evenly stirred mixture and the curing agent are then introduced into the coating device.

[0036] 4) Knitted felt wrapping On the surface of the bamboo fiber nonwoven fabric layer, a knitted felt is wound with a pitch of 235mm and an overlap width of 15–20mm; the process is carried out from the starting line to the ending line, and the flow rate of the mixture is adjusted according to the impregnation state to ensure that the material is fully impregnated; after winding to the ending line, the material is cut and compacted with a pressure roller. 5) Wrapping with cotton mesh fabric: Continue to wrap a layer of cotton mesh fabric around the outer layer of the knitted felt, with a pitch of 210mm and an overlap width of 15–20mm. Do not drip material during the wrapping process. Maintain a large tension during wrapping to expel internal air bubbles and promote uniform distribution of the mixture, thus completing the inner lining. S1.2, Structural layer forming: 1) Initial winding: Start the core mold and wind it from the tail end to the front end; after starting the material coating device, roll in cotton mesh and fiberglass mesh in sequence, and after winding it once, introduce the circumferential bamboo strip with an overlap width of 165mm. 2) Alternating winding Once the circumferential bamboo strips completely cover the front inner lining layer, change the winding direction and wrap the second layer from the front to the rear. Repeat this process until all the designed layers are completed. 3) Outer layer fixing After the circumferential bamboo strips are finished, only the bamboo strips and fiberglass mesh are cut off. After stopping the feeding, a layer of bamboo fiber non-woven fabric is added to the outermost layer, and 2-3 turns of cotton mesh are wrapped around the end before cutting to prevent the outer bamboo strips from loosening.

[0037] S1.3, Outer Protective Layer Treatment On the surface of the structural layer, a layer of mixture is evenly coated using a structural winding device. The pitch is adjusted to ensure that the mixture fully covers the outer surface of the pipe. Simultaneously, a roller brush is used for coating and finishing to ensure that the surface is smooth and free of bumps or burrs.

[0038] In step S1, the winding device is installed on a movable trolley. While moving along the axial direction of the mandrel, i.e. the length of the pipe, it releases material to wind onto the surface of the mandrel. Therefore, the traveling speed of the winding device is matched with the rotational speed of the mandrel.

[0039] S2, Curing; After the winding process is completed, the mandrel is hoisted into the curing oven and rotated at a speed of 300-400 r / min. It is then cured at 80℃ for 15-30 minutes. After curing, the mandrel is moved to the finishing station.

[0040] S3, Trimming: After curing, select a suitable grinding wheel according to the size of the pipe diameter to trim both ends of the pipe. After trimming, measure the dimensions of both ends again. Once the product dimensions are confirmed to be qualified, prepare for demolding.

[0041] S4, Demolding 1) Hoist the trimmed pipe to the center of the support vehicle, raise the pallet to make the core mold horizontal, move the support vehicle so that the core mold positioning plate is locked in the U-shaped chuck of the demolding vehicle, put on the demolding ring and adjust its position so that it is evenly locked at the front end of the pipe. 2) The trolley moves slowly toward the gantry, allowing the demolding ring to move to the inside of the gantry clamping arm. Extend the four clamping arms of the gantry and adjust their length to clamp the demolding ring. Leave a gap of about 1 cm between the clamping claw and the core mold. 3) Activate the ejection cylinder to push the demolding trolley forward, and start the demolding trolley intermittently to relieve the stress on the chain buffer rod of the demolding trolley; when the ejection cylinder is relieved of stress, start the demolding trolley to pull the core mold at low speed, and it can run at high speed when the resistance is low; 4) When the core mold is pulled out 1 / 3, the inner roller of the gantry is raised to support the core mold; after the core mold is completely separated from the product, the demolding car stops, the pipe pallet is opened and moves away from the gantry, and then the pallet is lowered. 5) Remove the polyester film from the pipe, hoist the pipe to the designated position, return the mandrel winding equipment to the initial position, and remove the mandrel for reuse.

[0042] The present invention significantly improves the production efficiency and product consistency of bamboo-wound composite pipes through the above-mentioned optimized process, enhances the structural strength and surface quality of the pipe body, and reduces manual intervention and material loss, making it suitable for large-scale standardized production.

[0043] Product performance test results: Ring stiffness: 11594 N / m² (standard requirement ≥10000 N / m²); Circumferential tensile strength: 2650 kN / m; Axial tensile strength: 2432 N / m; Water pressure leakage: No leakage at 2.4MPa; Low-temperature thermal conductivity (30℃): 0.20 W / (m·K).

[0044] When connecting the manufactured pipes, the following joint connection method is adopted: the connection between adjacent bamboo-wound pipes is changed from the existing socket connection structure to a sleeve connection with a sealing ring, so as to realize the direct connection between two pipes with the same diameter. Specifically, the sealing ring sleeve includes an annular sleeve 4 placed on the outside of the joint end of the two pipes. A sealing ring 5 is embedded in the sleeve through a dovetail groove and chemically bonded with an interface agent. The inner side of the sealing ring 5 is in contact with the outer wall of the pipe. Preferably, the annular sleeve 4 is made of fiberglass to bear mechanical strength, and the sealing ring 5 is made of full-width EPDM rubber to seal the pipe.

[0045] This connection structure improves the stability of the pipe products. No special treatment is required at the pipe connection points. The number of times raw materials need to be replaced during production can be reduced. After the bamboo-wound composite pipe is cured, the finishing, demolding, and excess material removal can be completed in 10-15 minutes. No unloading or padding is required during loading. The loading of a truckload of bamboo-wound composite pipe can be completed in 1 hour, which can greatly improve the production and transportation efficiency of bamboo-wound composite pipe.

[0046] In summary, the existing production process consists of six core steps: lining fabrication, structural layer winding, curing, outer protective layer fabrication, finishing, and demolding. Compared to the existing technology, the core steps of this invention are winding, curing, finishing, and demolding, offering advantages in cost and production capacity as follows: 1) Reduced product costs: Compared with existing technologies, the pipeline of this invention reduces material costs, labor costs, and fuel and power costs, while improving production efficiency. Statistics, taking DN500 as an example, show the cost reduction ratio in Table 1 below:

[0047] 2) Material costs reduced Bamboo-wound composite pipes reduce the use of axial bamboo strips, structural layer resin, reactants, glass fiber filaments, and bamboo powder, while increasing the use of filler and glass fiber mesh, and reducing the number of bamboo strip layers. Taking a DN500-0.2-10000N / ㎡ pipe as an example, the structural layering process is shown in Table 2 below:

[0048] As shown in Table 2, compared with existing products, the product of this invention can reduce the number of bamboo strips while meeting usage requirements. Furthermore, the reduction in the number of material types mitigates problems such as incompatibility caused by too many material types, thereby lowering the material cost of the pipe.

[0049] 3) Reduced labor costs Compared with existing bamboo-wound composite pipes, the bamboo-wound composite pipe of the present invention reduces the number of lining stations, reduces the number of workers on the production line from 7 to 5, and reduces labor costs by 28%.

[0050] 4) Reduced fuel and power costs The product of this invention uses a thermosetting unsaturated resin that can be naturally cured at room temperature (25°C). Existing urea-formaldehyde resin products require a high-power curing oven to cure for 3-5 hours, while the resin of this invention only needs to be cured for 0.5 hours, which greatly shortens the curing time and reduces pipeline fuel and power costs.

[0051] 5) Capacity increase The optimized production process of the bamboo-wound composite pipe of the present invention reduces the existing six production processes to four, thereby increasing the pipe production capacity.

[0052] The embodiments given above are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or substitutions made by those skilled in the art based on the technical features of the present invention are within the protection scope of the present invention.

Claims

1. A filled bamboo-wound composite pipe comprising, from inside to outside, an inner liner layer, a structural layer and an outer protective layer; characterized in that, The inner lining layer comprises unsaturated resin, filler, bamboo fiber non-woven fabric, knitted felt and cotton mesh cloth. The structural layer comprises bamboo splints, unsaturated resin, filler and glass fiber mesh cloth. The outer protective layer comprises unsaturated resin and filler. The unsaturated resin in the inner lining layer, the structural layer and the outer protective layer is the same type of unsaturated polyester resin. The filler is calcium powder, and the mass content of the calcium powder is 40% to 60% of the unsaturated resin.

2. The filled bamboo-wound composite pipe according to claim 1, wherein, The unsaturated polyester resin is one of m-benzene type unsaturated polyester resin, vinyl ester resin or bisphenol A type resin, and the performance of the unsaturated polyester resin satisfies the following conditions: the viscosity at 25 DEG C is 400 to 800 mPa s, the solid content is greater than or equal to 55%, the gel time at 25 DEG C is 10 to 60 minutes, the tensile strength is greater than or equal to 60 MPa, and the elongation at break is greater than or equal to 3.0%.

3. The filled bamboo-wound composite pipe according to claim 1, wherein, The cotton mesh cloth has a warp and weft density of 2.5 to 6.0 per 10 mm, a unit area mass of less than or equal to 40 g / m2, and a transverse and longitudinal breaking elongation of less than or equal to 5%, and a warp breaking strength of greater than or equal to 1500 N. The glass fiber mesh cloth has a weight of 160 g per square meter, a width of 25 cm, a transverse and longitudinal alkali-resistant breaking strength of greater than or equal to 1000 N / 50 mm, and a transverse and longitudinal alkali-resistant breaking strength retention rate of greater than or equal to 50%.

4. The filled bamboo-wound composite pipe according to claim 1, wherein, The connecting step between adjacent single-joint pipes is that the end portions of the two pipes are inserted into a ring-shaped sleeve, a sealing ring is embedded in the sleeve through dovetail grooves, the inner side of the sealing ring is attached to the outer wall of the pipe, and the pipe connection is achieved.

5. The filled bamboo-wound composite pipe according to claim 4, characterized in that, The ring-shaped sleeve is made of glass fiber reinforced plastic, and the sealing ring is made of ethylene-propylene-diene rubber.

6. A process for the preparation of filled bamboo-wrapped composite pipe as claimed in any one of claims 1 to 5, wherein, The method comprises the following steps: S1, winding: S1.1, inner lining layer winding: sequentially winding polyester film, bamboo fiber non-woven fabric impregnated with resin mixture, knitted felt and cotton mesh cloth on the surface of a rotating core mold to form an inner lining layer; wherein the resin mixture is pre-mixed with unsaturated resin, filler and accelerator, and is mixed with a curing agent in a certain proportion and then is sprayed when the bamboo fiber non-woven fabric is wound; S1.2, structural layer forming: forming a structural layer by spraying resin mixture, introducing glass fiber mesh cloth and annular bamboo splints and alternately winding on the surface of the inner lining layer; S1.3, outer protective layer processing: spraying resin mixture on the surface of the structural layer to form an outer protective layer; S2, curing: placing the core mold after winding in a curing device and heating and curing in a rotating state; S3, trimming: trimming the size of the two ends of the cured pipe; S4, demolding: demolding the core mold from the cured and trimmed pipe to obtain the filled bamboo winding composite pipe.

7. The production method according to claim 6, wherein In step S1.1, when the bamboo fiber non-woven fabric is wound, the flow ratio of the resin mixture to the curing agent is (3 to 5):

10.

8. The preparation method according to claim 6, characterized in that, In step S1.1, the preparation method of the resin mixture is that the unsaturated resin, the filler and the accelerator are stirred at a speed of 1500 r / min for 10 to 20 minutes at 22 to 25 DEG C.

9. The preparation method according to claim 6, characterized in that, In step S1.2, the structural layer is wound in an alternating direction from the tail end to the front end and then from the front end to the tail end until the designed number of layers is reached.

10. The method of claim 6, wherein, In step S2, the curing time is 15 to 30 minutes.

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