A high-strength carbon fiber shell molding process for drone fuselages

Abstract

This application relates to the field of unmanned aerial vehicle (UAV) technology, and more particularly to a high-strength carbon fiber shell molding process for UAV fuselages. The high-strength carbon fiber shell molding process for UAV fuselages includes the following steps: material preparation → cutting → coating with epoxy foam material → bonding → mold closing → hot pressing → demolding → finishing → finished product. The material preparation involves preparing carbon fiber cloth with the same carbon fiber direction. The bonding process involves bonding n layers of carbon fiber cloth coated with epoxy foam material on one side to m layers of carbon fiber cloth, respectively. The fiber direction angles of any two adjacent bonded layers of carbon fiber cloth are different, where n is 3-6 and m is 8-15 degrees. The high-strength carbon fiber shell molding process proposed in this application, through simple process steps and optimized material combinations, can produce high-strength carbon fiber shells with excellent appearance quality, meeting the strength and appearance quality requirements of UAV fuselages, and has low cost and high production efficiency.

Description

Technical Field

[0001] This application relates to the field of unmanned aerial vehicle (UAV) technology, and in particular to a high-strength carbon fiber shell molding process for UAV fuselages. Background Technology

[0002] With the continuous development of drone technology, carbon fiber is increasingly being used as an important material in drone airframe structures. Carbon fiber, with its advantages of being lightweight, high-strength, corrosion-resistant, highly rigid, and electromagnetically transparent, has significantly improved the performance and application areas of drones.

[0003] A carbon fiber monocoque structure refers to a drone where the fuselage, wings, and tail are all constructed from a single, integral carbon fiber shell. This structure offers advantages such as simplicity, high strength, and low manufacturing cost. Reducing the need for numerous connectors and welding, the monocoque structure enhances the drone's structural stability, resulting in more reliable flight performance. However, the design and manufacture of this type of structure are relatively complex, primarily employing a wet lay-up process with carbon fiber fabric, which leads to insufficient strength in the drone's fuselage shell and an unsatisfactory shell appearance. Therefore, it is necessary to provide a novel high-strength carbon fiber shell molding process for drone fuselages to address these issues. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a high-strength carbon fiber shell molding process for drone fuselages. This application achieves higher strength carbon fiber material by using different fiber direction angles between any two adjacent layers of carbon fiber cloth during hot pressing, enabling thermal bonding between the layers. Furthermore, by incorporating epoxy foam material between the carbon fiber cloth layers, the modified thermally expanding microspheres in the epoxy foam material expand and the epoxy foam material itself foams during hot pressing, supporting the carbon fiber cloth and ensuring a tight fit between the formed carbon fiber material and the mold cavity, thus improving the final appearance quality of the molded workpiece.

[0005] The following technical solution is adopted:

[0006] A high-strength carbon fiber shell molding process for drone fuselages includes the following steps: material preparation → cutting → coating with epoxy foam material → bonding → mold closing → hot pressing → demolding → finishing → finished product. The material preparation involves preparing carbon fiber cloth with the same carbon fiber direction. The bonding process involves bonding n layers of carbon fiber cloth coated with epoxy foam material on one side to m layers of carbon fiber cloth. The fiber direction angles of any two adjacent bonded carbon fiber cloth layers are different, where n is 3-6 and m is 8-15.

[0007] By adopting the above technical solution, the process includes: Material preparation: Preparing carbon fiber cloth with carbon fibers arranged in the same direction. This step provides carbon fiber material for subsequent steps. Cutting: Cutting the carbon fiber cloth to fit the shape and size of the drone fuselage. This step cuts the carbon fiber cloth into the required shape and size. Coating with epoxy foam material: Coating part of the carbon fiber cloth with epoxy foam material. This step provides a foam layer for the carbon fiber cloth and forms a stronger carbon fiber material in subsequent steps. Laying: Laying n layers of carbon fiber cloth coated with epoxy foam material on one side together with m layers of carbon fiber cloth. The fiber direction angles of any two adjacent laminated carbon fiber cloth layers are different, n is 3-6, and m is 8-15. This step forms a multi-layer structure of carbon fiber layers, increasing the strength and stability of the fuselage. Mold fitting: Placing the laminated carbon fiber cloth into a mold for molding. This step ensures a tight fit between the carbon fiber cloth and the mold cavity, guaranteeing the accurate shape and size of the final product. Hot pressing: Hot pressing the carbon fiber cloth in the mold. The purpose of this step is to make the carbon fiber material stronger and improve its strength and durability through hot-melt bonding. Demolding: Remove the formed carbon fiber shell from the mold. The purpose of this step is to obtain a complete carbon fiber shell. Finishing: Trim and process the formed carbon fiber shell to achieve the desired appearance quality. The purpose of this step is to improve the appearance quality of the final formed workpiece. The high-strength carbon fiber shell product prepared in this application is used for the high-strength carbon fiber shell of UAV fuselage, and has excellent strength and appearance quality.

[0008] Preferably, the hot pressing process parameters are: temperature 145-155℃, and molding pressure 100-150 kg / cm². 2 The time is 1-2 hours.

[0009] By adopting the above technical solution, the process parameters of hot pressing have a significant impact on the quality and performance of the final molded workpiece. Temperature: Within the temperature range of 145-155℃, the modified thermally expandable microspheres in the epoxy foam material will expand due to heat, and the epoxy foam material will also foam and bulge. These expanded microspheres and foamed material support the carbon fiber cloth, ensuring that the carbon fiber material tightly adheres to the mold cavity, thus improving the appearance quality of the final molded workpiece. Molding pressure: 100-150 kg / cm² 2Under high molding pressure, the pressure between the carbon fiber cloth and the mold is higher, which helps to form a more uniform and dense carbon fiber material. Controlling the molding pressure can improve the compressive and flexural strength of the workpiece. Time: The hot pressing time depends on the curing time of the epoxy foam material and the hot-melt bonding time of the carbon fiber material. Within a time range of 1-2 hours, it can be ensured that the epoxy foam material is fully cured and the carbon fiber material is fully melted to form a strong bond. Therefore, by controlling the temperature, molding pressure, and time of hot pressing, the material bonding during the carbon fiber shell molding process can be made stronger, improving the strength and appearance quality of the finished product.

[0010] Preferably, the epoxy foam material comprises component A and component B, wherein the mass ratio of component A to component B is (1-3):1; wherein, by mass parts, component A comprises the following raw materials: 80-85 parts of bisphenol A type epoxy resin E-51, 3-5 parts of reactive diluent, 0.5-1 part of coupling agent, 5-8 parts of modified thermal expansion microspheres, and 0.5-1 part of foaming agent; and by mass parts, component B comprises the following raw materials: 85-90 parts of amine curing agent and 10-15 parts of accelerator.

[0011] By adopting the above technical solutions, each component in the epoxy foam material plays a different role in this application, while also working synergistically to ultimately meet the requirements of the molded workpiece. Bisphenol A type epoxy resin E-51: As the main matrix material, it possesses good mechanical and adhesive properties, providing strength and toughness to the epoxy foam material. Reactive diluent: Used to adjust the viscosity of component A, promoting the fluidity of the resin system and making it smoother when laminating carbon fiber cloth. Coupling agent: Plays a role in improving the compatibility and adhesion between epoxy, modified thermally expandable microspheres, and carbon fiber, enhancing the interfacial bonding strength. Modified thermally expandable microspheres: Modified with vinyltriethoxysilane to improve compatibility and dispersibility with epoxy resin. During hot pressing, they expand and bulge due to heat, ensuring uniform stress on the carbon fiber cloth and filling the gaps in the carbon fiber cloth, improving the strength and appearance quality of the carbon fiber material. Foaming agent: Releases gas during hot pressing, causing the epoxy foam material to foam and expand, increasing the volume of the molded part. Amine curing agents: React with the epoxy resin in component A to form a 3D network structure, curing the epoxy resin and improving the mechanical properties of the molded parts. Accelerators: Accelerate the reaction rate between the amine curing agent and the epoxy resin, shortening the curing time. Synergistic effect of components: Bisphenol A type epoxy resin reacts with the amine curing agent to form a stable three-dimensional network structure with high mechanical properties. The use of reactive diluents and coupling agents improves the resin's flowability and the bonding strength of the carbon fibers. The addition of modified thermally expandable microspheres improves the strength of the carbon fiber material and fills the gaps between the carbon fibers, improving the appearance quality of the molded parts. The use of foaming agents causes the epoxy foam material to expand and fill the mold cavity during hot pressing, improving the appearance quality of the molded parts. Through the synergistic effect of the components, the epoxy foam material can meet the requirements of high-strength carbon fiber shells for UAVs, improving the mechanical properties and appearance quality of the finished product.

[0012] Preferably, the reactive diluent is one or more of propylene oxide ether, butyl glycidyl ether, and glycerol epoxy resin.

[0013] Preferably, the coupling agent is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(ethoxy)silane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:1-3:4-6.

[0014] By adopting the above technical solution, the coupling agent in epoxy foam materials plays a role in improving the compatibility and bonding strength between bisphenol A type epoxy resin and modified thermally expandable microspheres and carbon fibers. In this application, the coupling agent used is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:1-3:4-6. This promotes the fluidity of the resin system, making the epoxy resin smoother when laminating carbon fiber fabric. It improves the compatibility between epoxy resin and carbon fiber, increasing their bonding strength. It enhances the interfacial interaction between carbon fiber and resin, strengthening the adhesion between them. The coupling agent, together with bisphenol A type epoxy resin and other components, improves the fluidity of the resin system, facilitating the resin's full penetration and wetting of carbon fibers, thus improving the adhesion and bonding strength between the resin and carbon fibers. The coupling agent works synergistically with the modified thermally expandable microspheres to improve the compatibility and dispersibility of the microspheres with the epoxy resin, ensuring that the microspheres are uniformly distributed in the resin and bulge during hot pressing to support the carbon fiber cloth, thereby improving the appearance quality of the molded part. Through the synergistic effect of the coupling agent and other components, the epoxy foam material can meet the requirements of the high-strength carbon fiber shell of UAVs, improving the mechanical properties and appearance quality of the finished product.

[0015] Preferably, the modified thermally expandable microspheres have an average particle size of 10μm-25μm, an initial foaming temperature of 105℃-115℃, and a maximum foaming temperature of 145℃-155℃.

[0016] By adopting the above technical solution, the modified thermally expandable microspheres play the following roles and synergistic effects in this application: As a foaming agent in epoxy foaming materials, the modified thermally expandable microspheres can generate bubbles through expansion when heated, promoting material expansion and foaming to form a cellular structure. The modified thermally expandable microspheres have a lower density, which can reduce the material density and increase the material porosity during the foaming process, thereby reducing the material density and improving the lightweight performance of the foamed material. As a filler in foaming materials, the modified thermally expandable microspheres can increase the material volume, reduce the material density, and also change the thermal expansion properties of the foamed material, increasing the thermal expansion rate and thermal expansion temperature. After modification with bisphenol A type epoxy resin E-51 using vinyltriethoxysilane, the compatibility and dispersibility between the modified thermally expandable microspheres and the epoxy foaming material are improved. The improved compatibility allows the thermally expandable microspheres to be uniformly dispersed in the epoxy foaming material, resulting in a uniform distribution of foam pores. When modified thermally expandable microspheres expand due to heat, and during the foaming of epoxy foam material, they bulge and support the carbon fiber cloth, ensuring a tight fit between the carbon fiber material and the mold cavity, thus improving the appearance quality of the final molded workpiece. Through the synergistic effect of coupling agents, thermally expandable microspheres, and other components, this epoxy foam material provides high mechanical strength, uniform cell distribution, and high foaming density, making it ideal for use in high-strength carbon fiber shells for drone fuselages, enhancing both appearance quality and strength performance.

[0017] Preferably, the modified thermally expandable microspheres are prepared as follows: by mass, 10 parts of vinyltriethoxysilane, 100 parts of ethanol, and 200 parts of water are mixed, and 200-250 parts of thermally expandable microspheres are added and stirred thoroughly. The mixture is heated to 50°C and refluxed for 50 minutes. The treated thermally expandable microspheres are then filtered, dried, pulverized, ground, and sieved to obtain modified thermally expandable microspheres with a particle size of 10-25 μm.

[0018] Preferably, the foaming agent is one of azobisisovalerate, azodicarbonamide, and N,N-dinitrospentamethylenetetramine.

[0019] Preferably, the amine curing agent is one of 1,6-hexanediamine, isophoronediamine, and 1,3-cyclohexyldimethylamine; and the accelerator is one of 2-phenylimidazole, 2-ethyl-4-methylimidazole, and diethylenetriamine.

[0020] Preferably, the preparation method of the epoxy foam material uses the raw materials of the epoxy foam material in the above-mentioned high-strength carbon fiber shell molding process for UAV fuselage, and includes the following steps:

[0021] Preparation of S101 and Component A: According to the mass fraction, add bisphenol A type epoxy resin E-51 to the reaction vessel, heat to 50℃, add reactive diluent, coupling agent, modified thermal expansion microspheres and foaming agent, stir for 1-2 hours, mix evenly, cool to obtain component A.

[0022] Preparation of S102 and Component B: According to the mass fraction, add the amine curing agent to the reactor, keep the reactor temperature at 40℃, then add the accelerator, stir for 1-2 hours, mix evenly, and let stand to obtain Component B;

[0023] S103. Mix the prepared components A and B evenly at a mass ratio of (1-3):1 to obtain epoxy foam material, and coat it on one side of the carbon fiber cloth.

[0024] In summary, the beneficial technical effects of this application are as follows:

[0025] 1. Simple operation and low cost: The process steps are simple and clear, requiring only a few steps such as cutting carbon fiber cloth, coating epoxy foam material, pasting, and hot pressing. It does not require complex equipment and process control, thus reducing production costs.

[0026] 2. High-strength carbon fiber shell: The carbon fiber shell prepared by this molding process has enhanced strength due to the hot-melt bonding between the carbon fiber cloths and the different fiber direction angles of any two adjacent layers of carbon fiber cloths. It can withstand greater loads and improve the strength and stability of the UAV fuselage.

[0027] 3. Excellent appearance quality: The use of epoxy foam material, especially the properties of modified thermal expansion microspheres, can support the carbon fiber cloth through foaming and bulging, ensuring that the carbon fiber material fits tightly with the mold cavity, eliminating gaps and air bubbles, improving the appearance quality of the final molded workpiece, and making its surface smooth and flat.

[0028] 4. The epoxy foam material of this application has been optimized in terms of mechanical strength, cell distribution uniformity, foam density, compatibility, and dispersibility, which can effectively improve the strength and appearance quality of the high-strength carbon fiber shell of the UAV fuselage, meeting the high strength requirements of the UAV shell. By controlling the mass ratio of component A to component B and optimizing the raw material formula, a high-strength epoxy foam material can be obtained. Using this material to prepare the carbon fiber shell in the UAV fuselage can increase the overall structural strength and stability, and improve tensile and compressive mechanical properties. After adjusting the formula and process conditions, the foam density of the epoxy foam material reaches greater than 430 g / cm³. 3 It has high enough strength to increase the strength and stability of the carbon fiber shell. Detailed Implementation

[0029] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0030] Example 1

[0031] A high-strength carbon fiber shell molding process for drone fuselages includes the following steps: material preparation → cutting → coating with epoxy foam material → bonding → mold closing → hot pressing → demolding → finishing → finished product. The material preparation involves preparing carbon fiber cloth with the same carbon fiber direction. The bonding process involves bonding n layers of carbon fiber cloth coated with epoxy foam material on one side to m layers of carbon fiber cloth, with the fiber direction angles of any two adjacent layers being different (n = 3, m = 8). The hot pressing process parameters are: temperature 145℃, molding pressure 100 kg / cm². 2 The time is 2 hours.

[0032] An epoxy foam material comprises component A and component B, wherein the mass ratio of component A to component B is 1:1. Component A, by mass, comprises the following raw materials: 80 parts of bisphenol A type epoxy resin E-51, 3 parts of propylene oxide ether, 0.5 parts of coupling agent, 5 parts of modified thermally expandable microspheres, and 0.5 parts of azobisisovalerate. Component B, by mass, comprises the following raw materials: 85 parts of 1,6-hexanediamine and 15 parts of 2-phenylimidazole. The coupling agent is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(ethoxy)silane, γ-(methacryloyloxy)propyltrimethoxysilane, and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:1:4. The modified thermally expandable microspheres have an average particle size of 10 μm, an initial foaming temperature of 105°C, and a maximum foaming temperature of 145°C.

[0033] The modified thermally expandable microspheres are prepared as follows: by mass, 10 parts of vinyltriethoxysilane, 100 parts of ethanol, and 200 parts of water are mixed, and 200 parts of thermally expandable microspheres are added and stirred thoroughly. The mixture is heated to 50°C and refluxed for 50 minutes. The treated thermally expandable microspheres are then filtered, dried, pulverized, ground, and sieved to obtain modified thermally expandable microspheres with a particle size of 10 μm.

[0034] The preparation method of epoxy foam material, using the raw materials of epoxy foam material in the above-mentioned high-strength carbon fiber shell molding process for UAV fuselage, includes the following steps:

[0035] Preparation of S101 and Component A: According to the mass fraction, add bisphenol A type epoxy resin E-51 to the reaction vessel, heat to 50°C, add propylene oxide ether, coupling agent, modified thermal expansion microspheres and azobisisovalerate, stir for 1 hour, mix evenly, cool to obtain component A.

[0036] Preparation of S102 and component B: According to the mass fraction, 1,6-hexanediamine was added to the reaction vessel, the temperature of the reaction vessel was kept at 40℃, and then 2-phenylimidazole was added. After stirring for 1 hour and mixing evenly, component B was obtained by standing.

[0037] S103. Mix the prepared components A and B evenly at a mass ratio of 1:1 to obtain an epoxy foam material, and coat it on one side of the carbon fiber cloth.

[0038] Example 2

[0039] A high-strength carbon fiber shell molding process for drone fuselages includes the following steps: material preparation → cutting → coating with epoxy foam material → bonding → mold closing → hot pressing → demolding → finishing → finished product. The material preparation involves preparing carbon fiber cloth with the same carbon fiber direction. The bonding process involves bonding n layers of carbon fiber cloth coated with epoxy foam material on one side to m layers of carbon fiber cloth. The fiber direction angles of any two adjacent bonded layers of carbon fiber cloth are different, where n is 6° and m is 15°. The hot pressing process parameters are: temperature 155°C, molding pressure 150 kg / cm². 2 The time is 1 hour.

[0040] An epoxy foam material comprises component A and component B, wherein the mass ratio of component A to component B is 3:1. Component A, by mass, comprises the following raw materials: 5 parts of bisphenol A type epoxy resin E-518, 5 parts of butyl glycidyl ether, 1 part of coupling agent, 8 parts of modified thermally expandable microspheres, and 1 part of azodicarbonamide. Component B, by mass, comprises the following raw materials: 90 parts of isophorone diamine, 10 parts of 2-ethyl-4-methylimidazole, and the coupling agent is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(ethoxy)silane, γ-(methacryloyloxy)propyltrimethoxysilane, and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:3:6. The modified thermally expandable microspheres have an average particle size of 25 μm, an initial foaming temperature of 115°C, and a maximum foaming temperature of 155°C.

[0041] The modified thermally expandable microspheres are prepared as follows: by mass, 10 parts of vinyltriethoxysilane, 100 parts of ethanol, and 200 parts of water are mixed, and 250 parts of thermally expandable microspheres are added and stirred thoroughly. The mixture is heated to 50°C and refluxed for 50 minutes. The treated thermally expandable microspheres are then filtered, dried, pulverized, ground, and sieved to obtain modified thermally expandable microspheres with a particle size of 25 μm.

[0042] The preparation method of epoxy foam material, using the raw materials of epoxy foam material in the above-mentioned high-strength carbon fiber shell molding process for UAV fuselage, includes the following steps:

[0043] Preparation of S101 and Component A: According to the mass fraction, add bisphenol A type epoxy resin E-51 to the reaction vessel, heat to 50°C, add butyl glycidyl ether, coupling agent, modified thermal expansion microspheres and azodicarbonamide, stir for 2 hours, mix evenly, cool to obtain component A.

[0044] Preparation of S102 and component B: Isophorone diamine was added to the reaction vessel according to the mass fraction, the temperature of the reaction vessel was kept at 40℃, and then 2-ethyl-4-methylimidazole was added. After stirring for 2 hours and mixing evenly, component B was obtained by standing.

[0045] S103. Mix the prepared components A and B evenly at a mass ratio of 3:1 to obtain an epoxy foam material, and coat it on one side of the carbon fiber cloth.

[0046] Example 3

[0047] A high-strength carbon fiber shell molding process for drone fuselages includes the following steps: material preparation → cutting → coating with epoxy foam material → bonding → mold closing → hot pressing → demolding → finishing → finished product. The material preparation involves preparing carbon fiber cloth with the same carbon fiber direction. The bonding process involves bonding n layers of carbon fiber cloth coated with epoxy foam material on one side to m layers of carbon fiber cloth, with the fiber direction angles of any two adjacent layers being different (n = 5, m = 11). The hot pressing process parameters are: temperature 150℃, molding pressure 120 kg / cm². 2 The time is 1.5 hours.

[0048] Epoxy foam material, comprising component A and component B, wherein the mass ratio of component A to component B is 2:1; wherein, by mass parts, component A comprises the following raw material: bisphenol A type epoxy resin E-51 The composition comprises: 83 parts of 1,3-cyclohexyldimethylamine, 4 parts of glycerol epoxy resin, 0.7 parts of coupling agent, 7 parts of modified thermal expansion microspheres, and 0.7 parts of N,N-dinitrospentamethylenetetramine; by mass, component B includes the following raw materials: 88 parts of 1,3-cyclohexyldimethylamine and 13 parts of diethylenetriamine; the coupling agent is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(ethoxy)silane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:2:5; the average particle size of the modified thermal expansion microspheres is 15 μm; the initial foaming temperature of the modified thermal expansion microspheres is 110℃; and the maximum foaming temperature of the modified thermal expansion microspheres is 150℃.

[0049] The modified thermally expandable microspheres are prepared as follows: by mass, 10 parts of vinyltriethoxysilane, 100 parts of ethanol, and 200 parts of water are mixed, and 230 parts of thermally expandable microspheres are added and stirred thoroughly. The mixture is heated to 50°C and refluxed for 50 minutes. The treated thermally expandable microspheres are then filtered, dried, pulverized, ground, and sieved to obtain modified thermally expandable microspheres with a particle size of 15 μm.

[0050] The preparation method of epoxy foam material, using the raw materials of epoxy foam material in the above-mentioned high-strength carbon fiber shell molding process for UAV fuselage, includes the following steps:

[0051] Preparation of S101 and Component A: According to the mass fraction, add bisphenol A type epoxy resin E-51 to the reaction vessel, heat to 50°C, add glycerol epoxy resin, coupling agent, modified thermal expansion microspheres and N,N-dinitrospentamethylenetetramine, stir for 1.5 hours, mix evenly, cool to obtain component A.

[0052] Preparation of S102 and Component B: According to the mass fraction, 1,3-cyclohexyldimethylamine was added to the reaction vessel, the temperature of the reaction vessel was kept at 40℃, then diethylenetriamine was added, and the mixture was stirred for 1.5 hours. After mixing evenly, the mixture was allowed to stand to obtain Component B.

[0053] S103. Mix the prepared components A and B evenly at a mass ratio of 2:1 to obtain an epoxy foam material, and coat it on one side of the carbon fiber cloth.

[0054] Comparative Example 1

[0055] Similar to Example 3, except that in the epoxy foam material, an equal amount of unmodified thermal expansion microspheres are used instead of the modified thermal expansion microspheres prepared in this application.

[0056] Comparative Example 2

[0057] Similar to Example 3, except that in the epoxy foam material, equal amounts of N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane are used instead of the coupling agent, which is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:2:5.

[0058] Comparative Example 3

[0059] Similar to Example 3, except that in the epoxy foam material, equal amounts of γ-(methacryloyloxy)propyltrimethoxysilane are used instead of the coupling agent N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:2:5.

[0060] Comparative Example 4

[0061] Similar to Example 3, except that in the epoxy foam material, equal amounts of γ-diethylenetriaminepropylenetriethoxysilane are used instead of the coupling agent N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:2:5.

[0062] Performance testing

[0063] The epoxy foam materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests, and the results are shown in Table 1.

[0064] Compressive strength: Tested according to GB / T8813-2008;

[0065] Foaming density: Tested according to GB / T6343-1995.

[0066] Table 1

[0067] Compressive strength / MPa <![CDATA[Foaming density / g / cm 3 > Example 1 25.6 435.5 Example 2 27.3 456.7 Example 3 26.8 463.2 Comparative Example 1 20.1 387.5 Comparative Example 2 22.6 402.3 Comparative Example 3 23.1 398.6 Comparative Example 4 22.3 395.3

[0068] As shown in Table 1, the epoxy foam materials prepared in Examples 1-3 have good foaming density and compressive strength, with foaming densities ranging from 435.5 to 463.2 g / cm³. 3 The compressive strength is between 25.6 and 27.3 MPa.

[0069] Table 1 shows that, comparing the performance of the epoxy foam materials prepared in Example 3 and Comparative Example 1, the modified thermally expandable microspheres can generate bubbles through expansion when heated, promoting material expansion and foaming to form a cellular structure. The modified thermally expandable microspheres have a lower density, which can reduce the material's density and increase its porosity during the foaming process, thereby improving the lightweight performance of the foam material. As a filler in foam materials, the modified thermally expandable microspheres can increase the material's volume, reduce its density, and also alter the thermal expansion properties of the foam material, increasing its thermal expansion rate and thermal expansion temperature. The modification of the modified thermally expandable microspheres with bisphenol A type epoxy resin E-51 using vinyltriethoxysilane improves their compatibility and dispersibility. This improved compatibility allows the thermally expandable microspheres to be uniformly dispersed in the epoxy foam material, resulting in a uniform distribution of foam pores. When modified thermally expandable microspheres expand due to heat, and during the foaming of epoxy foam material, they bulge and support the carbon fiber cloth, ensuring a tight fit between the carbon fiber material and the mold cavity, thus improving the appearance quality of the final molded workpiece. Through the synergistic effect of coupling agents, thermally expandable microspheres, and other components, this epoxy foam material provides high mechanical strength, uniform cell distribution, and high foaming density, making it ideal for use in high-strength carbon fiber shells for drone fuselages, enhancing both appearance quality and strength performance.

[0070] As shown in Table 1, the performance comparison analysis of the epoxy foam materials prepared in Example 3 and Comparative Examples 2-4 shows that the combination of N-(β-aminoethyl)-γ-aminopropyltrimeth(ethoxy)silane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane as coupling agents in a mass ratio of 3:2:5 utilizes their synergistic effect to improve the overall performance of the epoxy foam materials.

[0071] The above embodiments are only used to explain the technical solutions of this application and are not intended to limit it. Although the above embodiments have provided specific descriptions of this application, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation methods of this application. Any modifications and equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. A high-strength carbon fiber shell molding process for unmanned aerial vehicle (UAV) fuselages, characterized in that, Includes the following steps: Material preparation → cutting → coating with epoxy foam material → bonding → mold closing → hot pressing → demolding → finishing → finished product. The material preparation refers to preparing carbon fiber cloth composed of carbon fibers in the same direction. The bonding refers to bonding n layers of carbon fiber cloth coated with epoxy foam material on one side to m layers of carbon fiber cloth. The fiber direction angles of any two adjacent bonded carbon fiber cloths are different, where n is 3-6 and m is 8-15. The epoxy foam material comprises component A and component B, wherein the mass ratio of component A to component B is (1-3):1; wherein, by mass parts, component A comprises the following raw materials: 80-85 parts of bisphenol A type epoxy resin E-51, 3-5 parts of reactive diluent, 0.5-1 part of coupling agent, 5-8 parts of modified thermal expansion microspheres, and 0.5-1 part of foaming agent; and by mass parts, component B comprises the following raw materials: 85-90 parts of amine curing agent and 10-15 parts of accelerator. The coupling agent is a composition of N-(β-aminoethyl)-γ-aminopropyltrimeth(ethoxy)silane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-diethylenetriaminepropylenetriethoxysilane in a mass ratio of 3:1-3:4-6; The modified thermally expandable microspheres are prepared as follows: by mass, 10 parts of vinyltriethoxysilane, 100 parts of ethanol, and 200 parts of water are mixed, and 200-250 parts of thermally expandable microspheres are added and stirred thoroughly. The mixture is heated to 50°C and refluxed for 50 minutes. The treated thermally expandable microspheres are then filtered, dried, pulverized, ground, and sieved to obtain modified thermally expandable microspheres with a particle size of 10-25 μm.

2. The high-strength carbon fiber shell molding process for UAV fuselage according to claim 1, characterized in that, The hot pressing process parameters are: temperature 145-155℃, molding pressure 100-150 kg / cm². 2 The time is 1-2 hours.

3. The high-strength carbon fiber shell molding process for UAV fuselage according to claim 1, characterized in that, The reactive diluent is one or more of propylene oxide ether, butyl glycidyl ether, and glycerol epoxy resin.

4. The high-strength carbon fiber shell molding process for UAV fuselage according to claim 1, characterized in that, The modified thermal expansion microspheres have an average particle size of 10μm-25μm, an initial foaming temperature of 105℃-115℃, and a maximum foaming temperature of 145℃-155℃.

5. The high-strength carbon fiber shell molding process for UAV fuselage according to claim 1, characterized in that, The foaming agent is one of azobisisovalerate, azodicarbonamide, and N,N-dinitrospentamethylenetetramine.

6. The high-strength carbon fiber shell molding process for UAV fuselage according to claim 1, characterized in that, The amine curing agent is one of 1,6-hexanediamine, isophoronediamine, and 1,3-cyclohexyldimethylamine; the accelerator is one of 2-phenylimidazole, 2-ethyl-4-methylimidazole, and diethylenetriamine.

7. The high-strength carbon fiber shell molding process for UAV fuselage according to claim 1, characterized in that, The preparation method of the epoxy foam material includes the following steps: Preparation of S101 and Component A: According to the mass fraction, add bisphenol A type epoxy resin E-51 to the reaction vessel, heat to 50℃, add reactive diluent, coupling agent, modified thermal expansion microspheres and foaming agent, stir for 1-2 hours, mix evenly, cool to obtain component A. Preparation of S102 and Component B: According to the mass fraction, add the amine curing agent to the reactor, keep the reactor temperature at 40℃, then add the accelerator, stir for 1-2 hours, mix evenly, and let stand to obtain Component B; S103. Mix the prepared components A and B evenly at a mass ratio of (1-3):1 to obtain epoxy foam material, and coat one side of it onto the surface of carbon fiber cloth.