Preparation method of anti-corrosion thermal-insulation anti-shielding basalt fiber gate valve well

Abstract

The invention relates to the technical field of gate valve well preparation, and discloses a preparation method of an anti-corrosion thermal-insulation anti-shielding basalt fiber gate valve well, which adopts an additive manufacturing and fiber winding synergistic forming process to realize seamless manufacturing of an integrated well body. The core is that firstly, a composite wire with a core-shell structure is prepared, and a shell layer of the composite wire contains a first chemical functional group; then, constructing an integrated functional framework comprising a well bottom, a well body and a flange layer by layer by utilizing the wire through an additive manufacturing process; during construction, basalt fibers impregnated with thermosetting resin containing a second chemical functional group are synchronously laid on the surface of a framework through a fiber winding process. Physical bonding seams are fundamentally eliminated, the prepared gate valve well has excellent structural integrity, sealing reliability and durability, the technological process is highly integrated, and the production efficiency and the product quality stability are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of gate valve well manufacturing technology, specifically a method for manufacturing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well. Background Technology

[0002] As a key ancillary structure in underground pipeline systems, the main function of gate valve wells is to provide operating space and protection for valves in underground pipelines, ensuring that the valves are protected from corrosion by environmental factors such as soil and groundwater, and facilitating personnel inspection and maintenance. Buried underground for extended periods, they must withstand lateral pressure from the soil, surface live loads, and the buoyancy and corrosion of groundwater. Therefore, stringent requirements are placed on the structural strength, sealing performance, and durability of gate valve wells.

[0003] Traditionally, gate valve wells are mostly constructed using brick masonry or cast-in-place reinforced concrete structures. While these structures are readily available, they also have significant inherent drawbacks. For example, they are heavy, causing considerable inconvenience for transportation and on-site hoisting; they have long construction periods and require specific working environments. More importantly, brick masonry structures have poor overall integrity. Under long-term soil settlement and temperature stress, cracks easily form at the mortar joints and connections to pipelines, leading to groundwater leakage and severely impacting the lifespan of internal valves and the operational safety of the pipeline system.

[0004] To overcome the shortcomings of traditional materials, fiber-reinforced composite materials, especially fiberglass or basalt fiber composites, have begun to be used in the manufacture of prefabricated gate valve wells in recent years. Composite well bodies exhibit significant technological advantages due to their lightweight, high strength, chemical corrosion resistance, and ease of installation. However, current manufacturing processes for composite gate valve wells generally have inherent limitations.

[0005] Existing composite well bodies typically employ a modular manufacturing and subsequent assembly process. Specifically, the cylindrical well body is usually manufactured independently using fiber winding, while more complex components such as the well bottom, top cover flanges, and sidewall pipe connection bosses are manufactured separately using molding or hand lay-up processes. Finally, these separate components are assembled into a complete well body using adhesives or mechanical connections. This process, relying on secondary bonding or assembly, makes the interface between components a weak point in the entire structure. This physical bonding interface is discontinuous in the material, making it prone to stress concentration in complex underground stress environments. Over time, the aging, hydrolysis, and fatigue of the adhesive under alternating loads all lead to a decrease in bond strength, resulting in a risk of leakage. This fundamentally weakens the durability advantages of composite materials and fails to completely solve the leakage problem of traditional gate valve wells. Therefore, developing a novel manufacturing method that enables seamless integral molding of composite gate valve wells to completely eliminate structural weaknesses and leakage risks caused by secondary connections is a pressing technical problem in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve wells. This method improves upon existing composite material gate valve wells, which are manufactured in separate parts and bonded in a secondary manner, resulting in weak points at structural joints, stress concentration, and leakage risks during long-term service.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well.

[0008] On the one hand, this method prepares an integrated well body through the following steps:

[0009] First, a composite filament with a specific structure is provided for subsequent additive manufacturing processes. In one embodiment, the composite filament has a core-shell structure. The core-shell composite filament can be prepared by a co-extrusion system: a thermoplastic resin material as the core layer and an interfacial reactive prepolymer containing the first chemical functional group as the shell layer are plasticized separately in independent extruders and then integrally formed in a co-extrusion die. The geometric parameters of the core-shell composite filament satisfy the following relationship:

[0010]

[0011] Among them, Vf s D represents the volume fraction of the shell layer in the cross-section of the composite filament. c D is the diameter of the core layer. s The total diameter of the composite filament is given.

[0012] Secondly, using the composite filaments, a functional skeleton is formed by stacking layers one by one using an additive manufacturing process. The geometry of this functional skeleton includes the well bottom, well body, and well cover flange of the gate valve well, achieving an integrated design. In some embodiments, the functional skeleton may also be integrally formed with at least one of pipe connection bosses and reinforcing rib structures during the manufacturing process as needed, thereby avoiding post-processing steps.

[0013] Next, in a collaborative and continuous manufacturing process, basalt fibers impregnated with a thermosetting resin containing a second functional group are laid onto the surface of the functional skeleton using a fiber winding process. The key to this step is "synchronization," meaning that the additive manufacturing process and the fiber winding process are performed in the same workflow, coordinated and scheduled online and in real-time by a central control unit. In one embodiment, the fiber winding process can employ a variable-angle winding method, where the winding angle is dynamically adjusted based on the geometric model of the functional skeleton and preset mechanical performance requirements to optimize structural performance.

[0014] Finally, the overall structure after the above-described synchronous composite process is cured. During the curing process, on the one hand, the thermosetting resin undergoes a cross-linking reaction to form a robust basalt fiber winding layer; on the other hand, and more importantly, at a preset curing temperature, the first chemical functional group in the functional framework shell and the second chemical functional group in the thermosetting resin are thermally activated and undergo a chemical reaction, thereby forming a chemical bonding interface between the functional framework and the basalt fiber winding layer. In one embodiment, this chemical reaction is a coupling reaction.

[0015] The chemical reaction system can be implemented in various specific ways. In one specific embodiment, the chemical reaction system can be an addition reaction system of epoxy groups and amino groups:

[0016] The first chemical functional group is amino. In this case, the interfacial reactive prepolymer can be a terminal amino polyether or other oligomer containing primary or secondary amine groups that remains thermally stable at the co-extrusion temperature. This prepolymer can be commercially available, for example, a specific brand of terminal amino polyether product readily available from the market; or it can be prepared using conventional synthetic methods in the art.

[0017] The second chemical functional group is an epoxy group. In this case, the thermosetting winding matrix resin is a conventional epoxy resin. During curing heating, the active hydrogen on the amino group undergoes a ring-opening addition reaction with the epoxy group to form stable hydroxyl and CN chemical bonds, thereby constructing chemical bonds at the interface.

[0018] In another alternative embodiment, the chemical reaction system can be an addition reaction system of isocyanate groups and hydroxyl groups:

[0019] The first chemical functional group is a hydroxyl group. The interfacial reaction prepolymer can be a low molecular weight polyester polyol or polyether polyol.

[0020] The second chemical functional group is an isocyanate group. The thermosetting winding matrix resin system needs to contain a polyisocyanate curing agent. The two react under heating conditions to form urethane bonds, achieving interfacial chemical bonding.

[0021] The kinetics of this interfacial chemical reaction can be described by the following model:

[0022]

[0023] in:

[0024] α: Interfacial reaction conversion rate, a dimensionless parameter with a value between 0 and 1.

[0025] t: reaction time.

[0026] T: Absolute temperature of the reaction system.

[0027] A: Pre-exponential factor, a constant characterizing the collision frequency of reactant molecules.

[0028] E a Apparent activation energy of interfacial chemical reactions characterizes the energy barrier that needs to be overcome for a reaction to occur.

[0029] R: Universal gas constant.

[0030] n: reaction order, a dimensionless empirical constant.

[0031] In one exemplary embodiment, if the aforementioned epoxy-amino reaction system is used, the curing process can be: maintaining a temperature of 120°C to 150°C for 2 to 4 hours. The temperature of the co-extrusion system needs to be controlled within the processing temperature window of the thermoplastic core layer material, while ensuring that this temperature is below the temperature at which the interfacial reaction prepolymer decomposes or degrades significantly.

[0032] By following the steps above, an integrated well body can be obtained that is completely seamless from the bottom of the well, through the well body to the well cover flange, and where the insulation core layer and the load-bearing outer shell are tightly bonded together by chemical bonds.

[0033] On the other hand, this method, independent of the steps described above, also includes the step of preparing the manhole cover.

[0034] In one embodiment, the manhole cover is prepared by compression molding. Specifically, this method includes: using basalt fiber woven fabric impregnated with thermosetting resin as a prepreg, laying it into a manhole cover mold according to design requirements, and then heating and pressurizing it using a hot pressing device to cure and shape it, ultimately obtaining the manhole cover.

[0035] In another preferred embodiment, to further optimize the mechanical properties of the manhole cover, a customized fiber placement technique can be employed before compression molding. This technique involves stitching continuous basalt fibers onto a substrate according to a pre-designed, optimized stress distribution path to create an integrated preform with an optimized fiber layout. Subsequently, this integrated preform is prepared into the prepreg for further compression molding.

[0036] This invention, through the aforementioned technical solution, simultaneously combines additive manufacturing and fiber winding processes, and utilizes material design to construct chemical bonds at heterogeneous interfaces, fundamentally eliminating physical bonding seams in traditional processes. The resulting gate valve well exhibits high structural integrity and reliable sealing. Furthermore, integrating multiple manufacturing steps into a single, continuous automated process significantly simplifies the process and improves production efficiency and product quality stability.

[0037] This invention provides a method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well. It has the following beneficial effects:

[0038] 1. This invention achieves seamless, single-piece molding of complex structures, from the well bottom and body to the well cover flange, by simultaneously and synergistically combining additive manufacturing and fiber winding processes. This integrated manufacturing method fundamentally eliminates the physical interfaces caused by secondary bonding or mechanical assembly in traditional split manufacturing processes. This not only completely eliminates structural weaknesses and stress concentration points caused by seams, but also ensures that the well body maintains excellent structural integrity and sealing reliability even when facing soil settlement and water pressure changes during long-term underground service.

[0039] 2. This invention utilizes a core-shell structured composite filament with an active shell layer. This design allows the surface of the functional skeleton formed by additive manufacturing to undergo an interfacial chemical reaction with the resin matrix of the impregnated fiber during the subsequent overall curing process, forming a large number of covalent bonds. This molecular-level chemical bonding exhibits bonding strength and durability far exceeding that of traditional physical adhesion or mechanical interlocking. It significantly enhances the interlaminar shear strength between the skeleton layer and the wound reinforcement layer, effectively preventing delamination failure and ensuring efficient load transfer between the inner and outer layers.

[0040] 3. This invention utilizes an additive manufacturing-winding synergistic process to integrate a traditional process that originally required multiple independent steps into a highly automated continuous manufacturing process. This high degree of process integration not only significantly shortens the overall production cycle of the product and reduces reliance on complex molds and manual assembly, but also greatly improves the dimensional accuracy and quality stability of the final product by avoiding errors introduced by multiple steps and human operation.

[0041] 4. This invention fully utilizes the multiple performance advantages of basalt fiber by selecting it as the main reinforcing material. The excellent acid and alkali corrosion resistance of basalt fiber enables it to withstand harsh underground chemical environments, significantly extending the service life of gate valve wells. Simultaneously, its superior thermal insulation properties and natural electrical insulation characteristics ensure that the final well body not only provides thermal insulation but also effectively prevents electromagnetic interference to any electronic sensors or communication equipment that may be housed within, achieving a balance between protective and functional requirements.

[0042] 5. This invention offers unprecedented freedom through the functional framework design of the gate valve well. Based on mechanical analysis results, it can easily manufacture complex optimized structures that are difficult to achieve with traditional molds, such as those with internal reinforcing ribs, localized variable wall thickness, and integrated irregular pipe connection bosses. This truly achieves on-demand structural design and performance optimization. This design flexibility, combined with the adjustability of the material system, allows this invention to flexibly customize and produce gate valve well products that combine optimal mechanical performance and cost-effectiveness according to specific working conditions, demonstrating strong engineering adaptability. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall process of the preparation method of the present invention;

[0044] Figure 2 This is a schematic diagram of the longitudinal section structure of the integrated well body of the present invention;

[0045] Figure 3 This is a schematic diagram of the additive winding co-molding process of the present invention.

[0046] Figure 4 This is a schematic diagram of the planar structure of the gate valve well of the present invention; Detailed Implementation

[0047] The technical solutions in 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.

[0048] Please see the appendix Figure 1-4 This invention provides a method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well. This method achieves an integrated well body including the well bottom, well body, and well cover flange through a collaborative manufacturing process, and independently prepares a high-performance well cover that matches it.

[0049] The preparation method may include steps for preparing an integrated well body and steps for preparing a well cover.

[0050] The core of the integrated well body fabrication process lies in achieving seamless molding of the well body structure in a continuous process through a combination of material design and technological innovation. First, specific raw materials for subsequent processes need to be prepared, including a thermoplastic material for the additive manufacturing functional skeleton, an interfacial reactive prepolymer containing specific chemical functional groups, and a thermosetting resin system and basalt fiber for fiber winding. In this embodiment, the core layer material of the functional skeleton is a thermoplastic polyester with good thermal stability and mechanical properties, such as polyethylene terephthalate (PETG); the interfacial reactive prepolymer is an amino-terminated polyether, whose molecular chain ends with an amino group as the first chemical functional group; and the thermosetting resin system used for fiber winding is a bisphenol A type epoxy resin, whose molecular structure contains an epoxy group as the second chemical functional group.

[0051] Subsequently, the above materials are prepared into a composite filament with a core-shell structure. This process is completed in a twin-screw co-extrusion system. Thermoplastic polyester is fed into the main extruder as the core material, while a mixture of amino-terminated polyether and a small amount of thermoplastic polyester is fed into the secondary extruder as the shell material. The two materials converge and are extruded in the co-extrusion die, and after cooling and shaping, a composite filament is formed. The shell of this composite filament is rich in amino groups, and its core-shell geometric relationship is defined by the following formula:

[0052]

[0053] Among them, Vf s D represents the volume fraction of the shell in the cross-section of the composite filament. c D is the diameter of the core layer. s This represents the total diameter of the composite filament. By adjusting this ratio, the density of interfacial reactive functional groups can be precisely controlled.

[0054] Next, the well body is integrally formed on a collaborative manufacturing platform integrating an additive manufacturing system, a robotic fiber winding system, and a central control unit. The central control unit first generates time-synchronized, path-coupled motion commands based on the three-dimensional digital model of the gate valve well. Upon receiving the commands, the additive manufacturing system begins to melt and extrude the aforementioned core-shell composite filaments, stacking them layer by layer from the center of the well bottom to construct a complete functional skeleton including the well bottom curved surface, well shaft, top flange, and pre-set pipe connection bosses and internal and external reinforcing ribs.

[0055] During the construction of the skeleton by the additive manufacturing system, the robotic fiber winding system is activated simultaneously. Continuous basalt fiber roving impregnated with epoxy resin, under the precise guidance of the robot, is wound along a pre-set variable-angle winding path with constant tension, covering the newly printed functional skeleton, whose surface still possesses a certain temperature and chemical activity, in real time and tightly. The additive manufacturing and fiber winding processes highly overlap in time and are closely integrated in space until the entire well structure is formed.

[0056] The molded well body is then transferred as a whole into a curing oven for heating and curing. The curing process includes three stages: heating, holding, and cooling. During the holding stage, two crucial chemical reactions occur simultaneously within the system: first, the bulk cross-linking reaction of the epoxy resin forms a three-dimensional network structure, endowing the winding layer with macroscopic mechanical properties; second, the amino groups in the functional framework shell undergo nucleophilic addition reactions with the epoxy groups of the epoxy resin, forming a large number of CN covalent bonds at the interface between the framework and the winding layer. The kinetics of this interfacial chemical bonding reaction can be described and guided by the following model:

[0057]

[0058] Where α is the interfacial reaction conversion rate, t is the reaction time, T is the absolute temperature during the curing process, A is the pre-exponential factor, and E is the exponential factor. a Let α be the apparent activation energy of the interfacial chemical reaction, R be the universal gas constant, and n be the reaction order. By precisely controlling the curing temperature and time, it can be ensured that the interfacial reaction conversion rate α reaches an ideal level while the epoxy resin is fully cured, thereby forming a gradient chemically bonded interface with continuously transitioning properties, ultimately obtaining an integrated well body.

[0059] The manhole cover is manufactured using a high-performance molding process. First, based on the finite element stress analysis results of the manhole cover, a customized fiber laying technology is used to precisely sew continuous basalt fiber yarns onto a thin glass fiber felt substrate according to the optimized stress path, forming an integrated preform with fibers arranged as needed.

[0060] Then, the integrated preform is prepared into a prepreg and laid in a preheated manhole cover metal mold according to a specific layup sequence and angle. After the mold is closed, a set pressure and temperature are applied on a hot press to fully impregnate and cure the resin, and finally demold to obtain a finished manhole cover with high strength and high rigidity. This manhole cover fits precisely with the flange structure on the top of the integrated manhole body to form a complete basalt fiber gate valve manhole.

[0061] This invention provides a method for preparing a functional framework and a fiber winding layer by using different chemical reaction systems to achieve interfacial chemical bonding. The purpose of this embodiment is to demonstrate the universality of the core technical concept of this invention, namely, the idea of ​​improving the overall structural performance by constructing covalent bonds at the interface of heterogeneous materials, and it is not limited to a specific chemical pairing.

[0062] In this embodiment, the preparation method of the integrated well body is consistent with the aforementioned embodiments in terms of process flow and equipment system. The core difference lies in the chemical system of the raw materials used. Specifically, the chemical bonding at the interface is constructed through the addition reaction between isocyanate groups and hydroxyl groups. For the core-shell composite filament used in additive manufacturing of functional skeletons, the core layer material can still be thermoplastic polyester or other materials, but the first chemical functional group contained in the shell layer is designed to be hydroxyl. This shell layer can be formed by using a low molecular weight polyester polyol or polyether polyol as an interfacial reaction prepolymer, blending it with a thermoplastic resin, and then coating it outside the core layer in a co-extrusion system.

[0063] Accordingly, the thermosetting resin system used for fiber winding must contain a second chemical functional group, namely an isocyanate group, that can react with hydroxyl groups. For example, a two-component polyurethane resin system can be used, in which one component contains a polyisocyanate curing agent. During the fiber winding process, basalt fibers are impregnated in this mixture of polyurethane resin system.

[0064] In the subsequent overall curing step, when the overall structure is heated to the preset curing temperature, the hydroxyl groups in the functional skeleton shell react with the isocyanate groups in the winding resin to generate a large number of urethane bonds. These newly formed chemical bonds form a strong bridge connecting the functional skeleton and the fiber winding layer, thereby achieving stable chemical bonding between the heterogeneous material interfaces.

[0065] The kinetics of this interfacial reaction can also be described and analyzed using a general model that helps optimize the curing process to ensure the full progress of the chemical reaction.

[0066]

[0067] Where α represents the interfacial reaction conversion rate, t is the reaction time, T is the absolute temperature of the curing system, A is the pre-exponential factor, and E... a Let be the apparent activation energy of the reaction between isocyanate groups and hydroxyl groups in the current chemical system, R be the universal gas constant, and n be the apparent reaction order of the reaction.

[0068] Similarly, the geometric design principles of core-shell composite filaments remain unchanged, and their shell volume fraction Vf s With the diameter of the core layer D c Total diameter D of the wire s The relationship between them still follows:

[0069]

[0070] This embodiment further demonstrates that by rationally designing and selecting functional group pairs that can react with each other, and introducing them into the shell of the additive manufacturing filament and the resin matrix in which the fiber is wound, the technical solution of simultaneous composite and interfacial chemical bonding proposed in this invention can be realized using diverse material systems, and has good flexibility and broad industrial application prospects.

[0071] In another embodiment of the present invention, the aforementioned integrated well body preparation method is further optimized by introducing an online monitoring and closed-loop feedback control system, which aims to elevate the two processes of additive manufacturing and fiber winding from simple synchronous execution to a level of intelligent manufacturing with deep coupling and dynamic collaboration.

[0072] In this embodiment, the collaborative manufacturing platform, in addition to the basic additive manufacturing system and robotic fiber winding system, also integrates a multimodal sensing system. This sensing system includes a geometric sensing module, such as a non-contact laser scanner, for real-time monitoring of the workpiece's three-dimensional contour; and an infrared thermal imaging module for real-time monitoring of the workpiece's surface temperature field. Both sensing modules operate continuously throughout the manufacturing process, transmitting the collected data to the central control unit in real time.

[0073] The core function of the central control unit is that it not only issues preset manufacturing instructions, but more importantly, it compares the data fed back from the sensors with the theoretical values ​​in the digital model in real time, and dynamically adjusts the process parameters based on the deviation. This closed-loop feedback control process contains two interrelated control loops.

[0074] The first is geometric closed-loop control. A laser scanner continuously scans the contour of the functional skeleton just constructed by the additive manufacturing system. The central control unit compares this real-time geometric data with the original digital model to calculate the geometric deviation. If any micron-level shape deviation is detected, such as local collapse or bulge caused by material shrinkage or minor disturbances, the control unit immediately adjusts the motion path of the subsequent fiber winding arm or the attitude of its end effector. This adjustment aims to compensate for the generated geometric deviations, ensuring that the final wellbore outer contour accuracy is as close as possible to the theoretical design.

[0075] Secondly, there is closed-loop thermal field control. An infrared thermal imaging module continuously monitors the temperature distribution across the entire workpiece. Because the moistened fibers impregnated with liquid resin exert a localized cooling effect on the still-warm functional skeleton during winding, these temperature fluctuations affect the material's curing behavior and the generation of internal stress. The central control unit compares the real-time monitored temperature field with a preset, ideal, stable temperature field model. If a significant temperature gradient or deviation occurs, the control unit will fine-tune the additive manufacturing system's process parameters in reverse, for example, appropriately increasing the extrusion temperature of subsequent printing layers or decreasing the printing speed to replenish heat, thereby maintaining a uniform and stable thermal field throughout the molding process and suppressing structural internal stress caused by temperature unevenness.

[0076] The entire closed-loop control logic's operating mechanism can be conceptually described by a multivariable control function:

[0077] ΔP(t)=f(ΔG(t),ΔT(t))

[0078] Where: ΔP(t): represents the dynamic adjustment amount of the central control unit outputting process parameters (such as winding path, printing speed, etc.) at time t.

[0079] f(...): Represents a nonlinear, multivariable coupled control algorithm function.

[0080] ΔG(t): represents the geometric deviation at time t, which is the difference between the real-time geometric measurement and the theoretical model value.

[0081] ΔT(t): represents the thermal field deviation at time t, which is the difference between the real-time temperature field measurement and the theoretical model value.

[0082] By introducing this closed-loop feedback control system, the manufacturing method provided in this embodiment can actively respond to and eliminate errors caused by various uncertainties in the manufacturing process, significantly improving the dimensional accuracy, geometric tolerances and internal quality stability of the final product, and enabling the integrated manufacturing of the gate valve well to reach a higher level of technology.

[0083] In a further embodiment, this invention discloses a scheme for enhancing the performance of core-shell composite filaments used in additive manufacturing. The core of this scheme lies in modifying the core material of the functional framework to impart superior lightweight characteristics and thermal insulation properties to the well body without affecting its structural support capabilities, thereby expanding the application potential of the invention's technical solution in special working conditions.

[0084] In this embodiment, the overall preparation process of the integrated well body, the principle of interfacial chemical bonding, and the collaborative manufacturing process adopted can all remain consistent with any of the aforementioned embodiments. Its innovation lies in the internal structure of the core-shell composite filament. Specifically, its core layer is no longer composed of a single thermoplastic resin, but is replaced by a composite material—lightweight, high-strength composite foam.

[0085] This composite foam is a composite material formed by uniformly dispersing a large number of hollow microspheres in a thermoplastic resin matrix. In the preparation of the core-shell structured composite filament, the selected thermoplastic resin is first physically blended with hollow inorganic microspheres of specific particle size and wall thickness in a high-speed mixing device. This mixture is then fed into the main extruder of a co-extrusion system. During melt plasticization, the microspheres are uniformly distributed in the resin melt, forming the core melt of the composite foam, which, together with the shell melt provided by the secondary extruder, is formed in the co-extrusion die.

[0086] The technological contribution of using composite foam as the core layer material lies in the fact that a large number of closed hollow microspheres construct a microscopic independent air cell structure within the material. This significantly reduces the thermal conductivity of the material, thereby significantly improving the thermal insulation performance of the functional skeleton. Simultaneously, since the density of the hollow microspheres is much lower than that of the resin matrix, their introduction also greatly reduces the overall density of the composite filaments, making the final integrated well body lighter and easier to transport and install.

[0087] The theoretical density of the composite foam core layer can be estimated and designed using the mixing principle, and the relationship is as follows:

[0088] ρ syn =ρ m ·V m +ρ p ·V p

[0089] in:

[0090] ρ syn : Represents the theoretical density of the composite foam core layer.

[0091] ρ m : Represents the density of the thermoplastic resin matrix.

[0092] V m: Represents the volume fraction of the thermoplastic resin matrix in the core layer.

[0093] ρ p : Represents the material density of the added hollow microspheres.

[0094] V p : Represents the volume fraction of hollow microspheres in the core layer, and V m +V p =1.

[0095] By adjusting the volume fraction V of the hollow microspheres p This allows for precise control of the density and thermal conductivity of the prepared functional skeleton to meet the specific requirements of lightweighting and thermal insulation performance in different application scenarios. In subsequent additive-winding co-molding and curing processes, the shell of this material-optimized composite filament can still form a stable chemical bond interface with the winding resin, thus ensuring the integrity and reliability of the overall structure. This embodiment fully demonstrates the flexibility and scalability of this invention at the material design level.

[0096] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well, characterized in that, Includes the following steps: a. Preparing an integrated well body: Step a1: Provide a composite filament with a core-shell structure, wherein the shell surface of the composite filament contains a first chemical functional group. Step a2: Using an additive manufacturing process, the composite filament is stacked layer by layer to form a functional skeleton including a well bottom, a well body, and a well cover flange. Step a3: During the forming process of the functional skeleton, basalt fibers impregnated with thermosetting resin containing a second chemical functional group are simultaneously applied to the surface of the functional skeleton through a fiber winding process. Step a4: The overall structure after step a3 is cured, so that the first chemical functional group and the second chemical functional group react chemically to form a chemical bonding interface between the functional skeleton and the basalt fiber winding layer, thereby obtaining the integrated well body. b. Preparation of manhole cover: Independent of step a, prepare a manhole cover for mating with the manhole cover flange of the integrated manhole body.

2. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 1, characterized in that, In step a1, the core-shell composite filament is prepared by co-extruding a thermoplastic resin material as the core layer with an interfacial reaction prepolymer containing the first chemical functional group as the shell layer.

3. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 1, characterized in that, In step a4, the chemical reaction between the first chemical functional group and the second chemical functional group is a coupling reaction that is thermally activated at a preset curing temperature.

4. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 4, characterized in that, The reaction rate of the chemical reaction is described by the following kinetic model: Where α is the interfacial reaction conversion rate, t is the reaction time, T is the absolute temperature, A is the pre-exponential factor, and E is the exponential factor. a η is the apparent activation energy, R is the universal gas constant, and n is the reaction order.

5. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 1, characterized in that, In step a3, the additive manufacturing process and the fiber winding process are coordinated and scheduled by a central control unit to achieve online synchronous manufacturing.

6. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 1, characterized in that, In step a2, the functional skeleton is integrally formed with at least one of pipe connecting bosses and reinforcing rib structures.

7. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 1, characterized in that, The method for preparing the manhole cover in step b is a compression molding method, which includes: using basalt fiber woven fabric impregnated with thermosetting resin as a prepreg, laying it into a manhole cover mold, and curing it by hot pressing.

8. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 7, characterized in that, Before compression molding, the process also includes using customized fiber placement technology to sew continuous basalt fibers onto the substrate along a preset path to create an integrated preform with optimized fiber layout, and then preparing the integrated preform into the prepreg.

9. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 2, characterized in that, The geometric parameters of the core-shell composite filament satisfy the following relationship: Among them, Vf s D represents the volume fraction of the shell layer in the cross-section of the composite filament. c D is the diameter of the core layer. c The total diameter of the composite filament is given.

10. The method for preparing a corrosion-resistant, heat-insulating, and shielding basalt fiber gate valve well according to claim 7, characterized in that, In step a3, the fiber winding process adopts a variable angle winding method, and the winding angle is dynamically adjusted according to the geometric model of the functional skeleton and the preset mechanical performance requirements.

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