Process for manufacturing a bamboo-wrapped pressure pipe

Abstract

The application discloses a kind of preparation processes of bamboo winding pressure pipeline, it is related to pressure pipeline manufacturing technical field, using layered composite forming process, pipeline is sequentially arranged inner lining, structural layer and outer protective layer from inside to outside;By optimizing the inner lining multilayer impermeable composite structure, with just mixing and using type segmented glue spraying gluing process, avoid resin curing failure, interlayer infiltration insufficient problem;Structural layer uses polyester mesh cloth, glass fiber mesh cloth, annular bamboo splint curtain as composite unit multilayer winding reinforcing structure, evenly disperses inside and outside load, eliminates local stress concentration phenomenon;At the same time, cooperate with uniform speed rotation heating curing, port precision finishing polishing process, guarantee pipeline overall structure stability and forming precision.Effectively improve the ring stiffness of bamboo winding pipeline, structural strength and water pressure impermeability, can be widely used in municipal water transmission under pressure, deep buried pressure pipe network, water conservancy engineering and other complex working conditions, process stability, high consistency of finished product.

Description

Technical Field

[0001] This invention relates to the field of pressure pipe manufacturing technology, and in particular to a preparation process for a bamboo-wound pressure pipe. Background Technology

[0002] Bamboo-wound composite pipes, a type of bio-based composite material pipe with bamboo as the reinforcing substrate, have been widely used in normal pressure water transmission fields such as municipal drainage and farmland irrigation due to their advantages of being green and low-carbon, lightweight and high-strength, corrosion-resistant, and recyclable. These pipes typically use continuous bamboo strips as reinforcement and thermosetting resin as the bonding matrix, and are integrally formed on a steel mandrel through a winding and curing process. The conventional structure mainly includes an inner lining layer, a structural layer, and an outer protective layer.

[0003] However, most existing publicly available and industrially applied bamboo-wound pipes are for atmospheric pressure drainage, not designed for pressurized water transmission. Several technical bottlenecks remain in actual high-pressure production and application, making it difficult to meet the standards for pressure pipelines. Regarding the winding process, traditional bamboo-wound pipes use a single constant tension winding method. The layup structure is not mechanically optimized based on the circumferential stress characteristics of pressure pipelines, resulting in insufficient circumferential pressure-bearing bamboo strip density and an unreasonable axial bending resistance layup design. Pipes produced using this method have low circumferential stiffness and weak internal pressure bearing capacity, making them only suitable for low-pressure and unpressurized drainage scenarios, and unsuitable for complex engineering conditions such as deep burial and medium-to-high-pressure water transmission. Furthermore, traditional winding processes suffer from poor process continuity, high levels of manual intervention, poor production consistency, and significant fluctuations in the mechanical properties of batch products.

[0004] To address the industry pain point of insufficient pressure-bearing capacity of bamboo-wound pipes, existing publicly available improvement technologies offer limited optimization and cannot fundamentally solve the compatibility problem with pressurized water transportation. For example, existing patent CN202511936373.4 discloses a method for preparing bamboo-wound pipes. This method only optimizes the molding process of traditional atmospheric pressure pipes and does not design for pressure-bearing compatibility of the pipe layer structure, anti-seepage system, resin application process, and curing process. The resulting pipes are still atmospheric pressure drainage pipes and do not have the pressure-bearing capacity for medium and high pressure water transportation, making them unsuitable for pressurized water transportation conditions.

[0005] In summary, the industry currently lacks a bamboo-wound pressure pipe manufacturing process that is reasonable, has a stable adhesive layer, strong pressure resistance, and high product consistency. This prevents bamboo-wound composite pipes from being extended to high-end application scenarios such as medium and high pressure municipal water supply, industrial fluid transportation, and deep-buried pressure pipelines, which greatly limits the industrialization and application scope of bamboo-wound composite material pipes. Summary of the Invention

[0006] The purpose of this invention is to provide a manufacturing process for bamboo-wound pressure pipes to solve the problems existing in the prior art, effectively improve the circumferential pressure bearing capacity, overall structural stability and water pressure seepage prevention performance of the pipes, and enable the prepared bamboo-wound pipes to meet the working conditions of pressurized water transportation.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides a manufacturing process for a bamboo-wound pressure pipe, wherein the pipe comprises, from the inside out, an inner lining layer, a structural layer, and an outer protective layer; the manufacturing process includes the following steps: S1. Preparation of inner lining layer: A layer of polyester film, a layer of bamboo fiber knitted felt impregnated with resin, two layers of glass fiber knitted felt, a layer of polyester mesh cloth, two layers of glass fiber filaments, and a layer of polyester mesh cloth are sequentially wound on the surface of a rotating winding mold to form the inner lining layer. S2. Preparation of structural layer: A resin mixture is coated onto the surface of the formed inner lining layer. At the same time, four layers of polyester mesh cloth, glass fiber mesh cloth, and circumferential bamboo strip curtain are wound in a circular manner from the inside to the outside. Then, a layer of bamboo fiber felt and a layer of polyester mesh cloth are wound in sequence to form the structural layer. S3. Preparation of outer protective layer: A resin mixture with added color paste is coated onto the surface of the pipe after the structural layer has been wound, and the outer protective layer is formed. S4. Curing treatment: Place the pipe with the completed three-layer structure along with the mold into the curing oven, rotate it at a speed of 5~20 r / min, and heat it to 100~120℃ at the same time. Keep it at the temperature for 15~30 minutes to complete the curing. S5. Finishing: Milling the cured pipe joints; S6. Demolding process: Separate the pipe from the mold to obtain a semi-finished bamboo-wound pressure pipe; S7. Fine grinding: Fine grinding is performed on the pipe joints after demolding to complete the pipe preparation and place it for storage.

[0008] In some embodiments, the inner lining is a multi-layered composite dense seepage-proof structure, which is formed by interlacing polyester film, bamboo fiber knitted felt, glass fiber knitted felt, glass fiber filaments and double-layer polyester mesh cloth to form a seepage barrier without capillary seepage channels, suitable for pressurized water transportation seepage prevention conditions.

[0009] In some embodiments, the four-layer unit of the structural layer adopts a continuous winding molding process, in which circumferential bamboo strips are interwoven with fiberglass mesh and polyester mesh to form a high-strength composite load-bearing skeleton, thereby improving the circumferential pressure-bearing capacity and structural stability of the pipeline.

[0010] In some embodiments, the resin includes an unsaturated resin, an accelerator, and a curing agent. The application method is spraying, and the application process is as follows: the unsaturated resin and the accelerator are mixed in advance, and the resin and the curing agent are pneumatically mixed before spraying, so that it can be used immediately after mixing.

[0011] In some embodiments, the resin mixture consists of unsaturated resin, accelerator, calcium powder, and curing agent, and is applied by spraying. The application process is as follows: the unsaturated resin, calcium powder, and accelerator are mixed in advance, and then pneumatically mixed with the curing agent before spraying, so that it can be used immediately after mixing.

[0012] In some embodiments, the resin used in the inner lining layer and the resin mixture used in the structural layer are applied using a separate premixing and immediate stirring process to ensure the resin curing activity, so that each functional layer is fully impregnated and bonded, and to prevent defects such as interlayer voids, delamination, and bubbles.

[0013] In some embodiments, the curing process adopts a dynamic rotary heating curing method, in which the pipeline rotates at a constant speed throughout the entire process, so as to achieve uniform heating and consistent curing of the entire pipe wall, and ensure the integrity and mechanical uniformity of the overall pipe structure.

[0014] In some embodiments, the resin mixture used in the outer protective layer is a modified unsaturated resin system with added color paste, which has the effects of protection, weather resistance and aesthetic enhancement, and can protect the internal structural layer from external environmental erosion.

[0015] In some implementations, after the pipe is formed, it undergoes a double process of interface milling and fine grinding to ensure the flatness and fitting accuracy of the pipe interface, effectively prevent interface leakage, and meet the sealing requirements for pressurized water transmission.

[0016] The present invention achieves the following technical effects compared to the prior art: 1. Reasonable structural stress distribution, crack resistance, and no stress concentration: The structural layer of this invention adopts a three-layer composite unit structure, consisting of polyester mesh, fiberglass mesh, and circumferential bamboo strips laid layer by layer, and repeatedly wound four times, further reinforced by bamboo fiber felt and polyester mesh. This multi-layer composite structure can evenly distribute the internal pressure and external load of the pipeline, effectively solving the defects of uneven stress distribution, local stress concentration, and interlayer cracking in traditional single bamboo strip structures, significantly improving the overall structural stability of the pipeline.

[0017] 2. Excellent mechanical properties, high ring stiffness, and strong pressure bearing capacity: Through the synergistic composite winding of glass fiber, polyester fabric and circumferential bamboo strips, the circumferential strength and overall ring stiffness of the pipe are greatly improved. The pipe's load-bearing capacity is significantly better than that of traditional atmospheric pressure bamboo-wound pipes. It has good structural integrity, small deformation, and can stably adapt to pressurized water transmission conditions.

[0018] 3. Reliable seepage prevention performance, meeting national standard pressure pipeline requirements: This invention is equipped with an optimized inner lining seepage prevention structure and adhesive application and curing process. The finished product can meet the water pressure leakage test requirements of GB / T 37805-2019 bamboo winding composite pipe. There is no leakage or sweating under pressure conditions, which completely solves the problem of easy water leakage in traditional normal pressure pipelines.

[0019] 4. Wider range of applications and stronger engineering practicality: Traditional bamboo-wound pipes are only suitable for unpressurized and normal pressure drainage scenarios. This invention, through structural and process optimization, enables bamboo-wound pipes to have pressurized water transmission capabilities, and can be widely used in complex engineering scenarios such as pressurized water transmission and deep buried pipe networks, greatly expanding the application fields of bamboo-wound composite pipes. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the bamboo-wound pressure pipe in this invention; Figure 2 This is a process flow diagram of the preparation process of the bamboo-wound pressure pipe in this invention; In the diagram: 1. Mold; 2. Liner; 3. Structural layer; 4. Protective layer. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0023] The purpose of this invention is to provide a manufacturing process for bamboo-wound pressure pipes to solve the problems existing in the prior art.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The fabrication process of the bamboo-wound pressure pipe in this embodiment is as follows: Figures 1-2As shown, the pipe consists of an inner lining layer 2, a structural layer 3, and an outer protective layer 4 from the inside out. The prepared pipe meets the water pressure leakage requirements of GB / T 37805-2019 bamboo-wound composite pipe 6.4.4. The preparation process includes the following steps: S1. Preparation of inner lining layer 2: A layer of polyester film, a layer of bamboo fiber knitted felt impregnated with resin, two layers of glass fiber knitted felt, a layer of polyester mesh cloth, two layers of glass fiber filaments, and a layer of polyester mesh cloth are sequentially wound on the surface of the rotating winding mold 1 to form inner lining layer 2. S2. Preparation of structural layer 3: A resin mixture is coated onto the surface of the formed inner lining layer 2. At the same time, four layers of polyester mesh cloth, glass fiber mesh cloth, and circumferential bamboo strip curtain are wound in a cycle from the inside to the outside. Then, a layer of bamboo fiber felt and a layer of polyester mesh cloth are wound in sequence to form structural layer 3. S3. Preparation of outer protective layer 4: A resin mixture with added color paste is coated onto the surface of the pipe after the structural layer 3 has been wound, and the outer protective layer 4 is obtained by molding. S4. Curing treatment: Place the pipe with the three-layer structure prepared together with mold 1 into the curing oven, rotate it at a speed of 5~20 r / min, and heat it to 100~120℃ at the same time. Keep it at the temperature for 15~30 minutes to complete the curing. S5. Finishing: Milling the cured pipe joints; S6. Demolding process: Separate the pipe from mold 1 to obtain a semi-finished bamboo-wound pressure pipe; S7. Fine grinding: Fine grinding is performed on the pipe joints after demolding to complete the pipe preparation and place it for storage.

[0026] This embodiment utilizes a three-layer functional structure design—an inner anti-seepage lining, a multi-layer composite pressure-bearing structure layer 3, and a weather-resistant outer protective layer 4—along with dedicated curing, finishing, and polishing processes, to achieve integrated molding of the pipeline for seepage prevention, pressure bearing, and protection. The entire process is tightly integrated and exhibits strong molding stability. From the perspective of overall structure and manufacturing process, it overcomes the shortcomings of traditional bamboo-wound pipes that cannot adapt to pressurized water transmission conditions, ensuring that the finished pipeline meets the overall performance requirements for pressurized water transmission, with high molding precision and excellent overall integrity.

[0027] In some embodiments, the inner lining layer 2 is a multi-layered, dense, seepage-proof structure. It is formed by interlacing polyester film, bamboo fiber knitted felt, glass fiber knitted felt, glass fiber filaments, and double-layer polyester mesh fabric to create a seepage barrier without capillary seepage channels, suitable for pressurized water transmission and seepage prevention conditions. The dense water-resistant barrier formed by the interlacing of polyester film, bamboo fiber knitted felt, multi-layered glass fiber knitted felt, glass fiber filaments, and double-layer polyester mesh fabric completely seals capillary seepage channels in the pipe wall. Compared to traditional single-layer lining structures, it effectively resists media penetration under pressurized water transmission conditions, eliminates problems such as pipe wall sweating, micro-seepage, and leakage under high-pressure conditions, stably meets the GB / T 37805-2019 water pressure leakage testing standard, and significantly improves the reliability of pipeline pressure-bearing seepage prevention.

[0028] In some implementations, the four-layer unit of structural layer 3 employs a continuous winding molding process, where circumferential bamboo strips are interwoven with fiberglass mesh and polyester mesh to form a high-strength composite load-bearing skeleton, enhancing the circumferential pressure-bearing capacity and structural stability of the pipeline. The four-layer continuous winding structure, combining polyester mesh, fiberglass mesh, and circumferential bamboo strips, utilizes the high circumferential tensile strength of bamboo strips with the flexible reinforcement and stress dispersion properties of fiberglass and polyester fabrics to construct a high-strength composite load-bearing skeleton. This effectively optimizes the circumferential load-bearing structure of the pipeline, solving the problems of insufficient circumferential stiffness and easy deformation under pressure in traditional bamboo-wound pipelines. It evenly distributes the internal pressure and external soil load of the pipeline, avoids local stress concentration, and significantly improves the circumferential pressure-bearing capacity and overall structural stability of the pipeline.

[0029] In some embodiments, the resin includes unsaturated resin, an accelerator, and a curing agent. The application method is spraying, and the application process is as follows: the unsaturated resin and accelerator are premixed, and then pneumatically mixed with the curing agent before spraying, allowing for immediate use. The inner lining layer 2 uses a premixed method of unsaturated resin and accelerator, followed by pneumatic mixing with the curing agent before spraying, effectively avoiding problems such as premature resin curing, adhesive failure, and uneven gelation. This ensures that each fiber substrate of the inner lining layer 2 is fully impregnated with resin, improving the overall density and interlayer bonding strength of the inner lining layer 2, and guaranteeing uniform molding and stable performance of the waterproof structure.

[0030] In some embodiments, the resin mixture consists of unsaturated resin, accelerator, calcium powder, and curing agent. It is applied using a spray coating method. The application process involves pre-mixing the unsaturated resin, calcium powder, and accelerator, then pneumatically mixing them with the curing agent before spray coating, allowing for immediate use. Calcium powder filler is added to the resin system of structural layer 3, and a pre-mixed, on-the-spot mixing application process is used. Calcium powder effectively improves the hardness, rigidity, and wear resistance of the cured resin, while reducing the resin curing shrinkage rate. Simultaneously, the on-the-spot mixing process ensures uniform adhesive layer and sufficient curing of structural layer 3, significantly improving the overall stiffness and mechanical load-bearing capacity of structural layer 3, enhancing the overall bonding strength of the multi-layer wound structure, and improving the pipeline's pressure resistance and deformation resistance.

[0031] In some embodiments, the resin used in the inner lining layer 2 and the resin mixture used in the structural layer 3 are both applied using a separate premixing and immediate stirring process to ensure the resin curing activity, so that each functional layer is fully impregnated and bonded, and to prevent defects such as interlayer voids, delamination, and bubbles.

[0032] In some implementations, the curing process employs a dynamic rotary heating curing method, where the pipeline rotates at a constant speed throughout the entire process, ensuring uniform heating and consistent curing of the entire pipe wall, thus guaranteeing the integrity and mechanical uniformity of the overall pipeline structure.

[0033] In some embodiments, the resin mixture used in the outer protective layer 4 is a modified unsaturated resin system with added color paste, which has the effects of protection, weather resistance and aesthetic enhancement, and can protect the inner structural layer 3 from external environmental erosion.

[0034] In some implementations, after the pipe is formed, it undergoes a double process of interface milling and fine grinding to ensure the flatness and fitting accuracy of the pipe interface, effectively prevent interface leakage, and meet the sealing requirements for pressurized water transmission.

[0035] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A manufacturing process for a bamboo-wound pressure pipe, characterized in that, The pipeline comprises, from the inside out, an inner lining layer, a structural layer, and an outer protective layer; the manufacturing process includes the following steps: S1. Preparation of inner lining layer: A layer of polyester film, a layer of bamboo fiber knitted felt impregnated with resin, two layers of glass fiber knitted felt, a layer of polyester mesh cloth, two layers of glass fiber filaments, and a layer of polyester mesh cloth are sequentially wound on the surface of a rotating winding mold to form the inner lining layer. S2. Preparation of structural layer: A resin mixture is coated onto the surface of the formed inner lining layer. At the same time, four layers of polyester mesh cloth, glass fiber mesh cloth, and circumferential bamboo strip curtain are wound in a circular manner from the inside to the outside. Then, a layer of bamboo fiber felt and a layer of polyester mesh cloth are wound in sequence to form the structural layer. S3. Preparation of outer protective layer: A resin mixture with added color paste is coated onto the surface of the pipe after the structural layer has been wound, and the outer protective layer is formed. S4. Curing treatment: Place the pipe with the completed three-layer structure along with the mold into the curing oven, rotate it at a speed of 5~20 r / min, and heat it to 100~120℃ at the same time. Keep it at the temperature for 15~30 minutes to complete the curing. S5. Finishing: Milling the cured pipe joints; S6. Demolding process: Separate the pipe from the mold to obtain a semi-finished bamboo-wound pressure pipe; S7. Fine grinding: Fine grinding is performed on the pipe joints after demolding to complete the pipe preparation and place it for storage.

2. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The inner lining is a multi-layered, dense, and leak-proof structure. It is formed by interlacing polyester film, bamboo fiber knitted felt, glass fiber knitted felt, glass fiber filaments, and double-layer polyester mesh fabric to create a leak-proof barrier without capillary seepage channels, making it suitable for pressurized water supply and leak prevention conditions.

3. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The four-layer unit of the structural layer adopts a continuous winding molding process. The circumferential bamboo strip curtain is interwoven with glass fiber mesh and polyester mesh to form a high-strength composite load-bearing skeleton, which improves the circumferential pressure bearing capacity and structural stability of the pipeline.

4. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The resin includes unsaturated resin, accelerator and curing agent. The application method is spraying. The application process is as follows: the unsaturated resin and accelerator are mixed in advance, and the resin and curing agent are pneumatically mixed before spraying. The mixture is ready to use immediately.

5. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The resin mixture consists of unsaturated resin, accelerator, calcium powder, and curing agent. It is applied by spraying glue, and the application process is as follows: the unsaturated resin, calcium powder, and accelerator are mixed in advance, and then pneumatically mixed with the curing agent before spraying glue. It can be used immediately after mixing.

6. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The resin used in the inner lining layer and the resin mixture used in the structural layer are all applied using a separate premixing and instant stirring process to ensure the resin curing activity, so that each functional layer is fully impregnated and bonded, and to prevent defects such as interlayer voids, delamination, and bubbles.

7. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The curing process adopts a dynamic rotary heating curing method, in which the pipeline rotates at a constant speed throughout the process, so as to achieve uniform heating and consistent curing of the entire pipe wall, ensuring the integrity of the overall pipe structure and mechanical uniformity.

8. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: The resin mixture used in the outer protective layer is a modified unsaturated resin system with added color paste, which has the effects of protection, weather resistance and aesthetic enhancement, and can protect the internal structural layer from external environmental erosion.

9. The manufacturing process of the bamboo-wound pressure pipe according to claim 1, characterized in that: After the pipe is formed, it undergoes two processes of joint milling and fine grinding to ensure the flatness and fitting accuracy of the pipe joint, effectively prevent joint leakage, and meet the sealing requirements of pressurized water transmission.

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