Vehicle body forming method based on low-VOC (volatile organic compound) composite material

Abstract

The invention provides a vehicle body forming method based on a low-VOC composite material, and relates to the technical field of vehicle body forming. The vehicle body forming method based on the low-VOC composite material specifically comprises the following steps of S1, fiber multi-axis laying; s2, carrying out preforming; s3, locally reinforcing the fibers; s4, carrying out vacuum-assisted resin transfer molding; s5, curing and post-processing are carried out; and S6, assembling the components. Through the multi-axis fiber laying, local reinforcement, vacuum auxiliary resin transfer molding forming and multi-material integrated forming processes, the strength of the vehicle body is improved, the weight is reduced, meanwhile, the material uniformity and the structural integrity in the manufacturing process are ensured, and finally comprehensive optimization of performance and efficiency is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle body molding, and in particular to a vehicle body molding method based on a low-VOC composite material. Background Art

[0002] The body is the external structure of the car, which is composed of the chassis frame (frame), doors, roof, windows, hood, bumpers, front and rear fenders, trunk lid and other major parts. It is mainly used to protect the occupants from the external environment (such as rain, dust, hot and cold weather changes), provide aerodynamic performance to reduce wind resistance and improve fuel efficiency, accommodate the engine, passenger space and essential items such as luggage, and at the same time have an aesthetic design to enhance the vehicle's attractiveness and brand image. In the event of a collision, the impact force is absorbed and dispersed through structural design (such as energy absorption zones, anti-collision beams, etc.), thereby reducing damage to the occupants in the car, ensuring the overall rigidity and stability of the vehicle, supporting the installation of various automotive devices (such as suspension systems, braking systems, power systems, etc.), and serving as a connection base for body parts, providing the car with basic driving and operating functions.

[0003] The molding methods of the prior art usually rely on traditional hand lay-up processes or simple compression molding. The process involves manually laying fiber cloth and applying resin. Although it is simple to operate and low in cost, it has obvious defects, such as uneven resin distribution and insufficient fiber impregnation, which leads to poor mechanical properties of the composite material, high porosity, and easy internal defects. In addition, the manual operation has low precision, poor product consistency, and it is difficult to meet high precision and high performance requirements. Although compression molding has improved production efficiency, the laying of fibers and the impregnation of resins are still difficult to control accurately, and there are limitations in the molding of complex structures, which can easily lead to stress concentration and material waste. These traditional processes usually also require a large number of mechanical connections, such as riveting and bolting, which further increase the weight and assembly complexity, and may also cause stress concentration, affecting the overall performance and durability of the vehicle body. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a vehicle body molding method based on low-VOC composite materials, which solves the problems of low efficiency and poor quality of the prior art.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a body molding method based on low-VOC composite materials, specifically comprising the following steps:

[0006] S1. Multiaxial fiber laying

[0007] According to the stress conditions of different parts of the car body, choose glass fiber or carbon fiber material, then cut the fiber cloth, and lay the fiber cloth in four directions of 0°, ±45°, and 90° on the workbench in sequence;

[0008] S2. Preforming

[0009] Using three-dimensional weaving or knitting technology, the fiber cloth is prefabricated into a preform close to the shape of the body part;

[0010] S3. Local fiber reinforcement

[0011] Finite element analysis is used to determine the areas of the vehicle body that are subject to the greatest stress, such as the body frame and joints, and 2 to 3 layers of aramid fiber are added to the designed areas;

[0012] S4. Vacuum Assisted Resin Transfer Molding

[0013] Prepare the mold, clean the mold surface to ensure it is dust-free, lay the prefabricated fiber preform on the mold, ensure that the fiber fits tightly to the mold surface, use a vacuum bag to seal the mold and the fiber preform, ensure that there is no air leakage in the system, turn on the vacuum pump, and then inject the resin. Use the vacuum negative pressure to evenly inject the resin between the fiber layers to ensure that the resin fully infiltrates the fiber, and heat the mold to 80℃ to 120℃ for curing;

[0014] S5. Curing and post-processing

[0015] After demoulding, the body parts may have some excess resin or uneven fiber edges, so they need to be trimmed. Use mechanical cutting tools or high-pressure water jets to accurately cut the body parts, remove excess materials and burrs, and then use fine sandpaper or polishing tools to polish the edges. After the product is trimmed, send the product to the oven at a baking temperature of 80°C for 24 hours.

[0016] S6. Component assembly

[0017] Use structural adhesive to bond different car body parts together. Structural adhesive can not only provide high-strength connection, but also disperse stress and improve the durability of the overall structure. Apply structural adhesive evenly on the connection surface of the parts. After application, wait for 24 hours for the structural adhesive to cure naturally.

[0018] Preferably, in the multiaxial fiber laying step S1, the thickness of each layer is controlled to be 0.2 mm to 0.5 mm.

[0019] Preferably, the number of fiber layers in the preforming in step S2 is 4 to 8, and the weaving density is 80% to 90%.

[0020] Preferably, the tensile strength of the aramid fiber in the local fiber reinforcement in step S3 is preferably 3000 MPa.

[0021] Preferably, in the vacuum-assisted resin transfer molding in step S4, the vacuum degree is maintained at -0.08 MPa to -0.09 MPa, the curing time is controlled at 1 to 2 hours, and the resin is a polyester resin with a low styrene content; alkaline montmorillonite, M50 curing agent, accelerator, and styrene inhibitor are added to the resin.

[0022] Preferably, in the step S5 of curing and post-processing, the polishing tool is selected to have a mesh size of 800-1000.

[0023] Preferably, in the step S6 of component assembly, the thickness of the glue layer is controlled to be between 0.5 mm and 1 mm.

[0024] Preferably, after cleaning the mold surface in step S4, a layer of adsorption structure is added to the mold, and adsorption particles are placed in the adsorption structure. The main function of the adsorption particles is to adsorb part of the VOC of the raw materials during the production process; the adsorption particles can be replaced by the adsorption structure device.

[0025] Preferably, the resin in step S4 is epoxy resin or common resin, and alkaline montmorillonite, M50 curing agent, accelerator and styrene inhibitor are added to the resin.

[0026] The present invention provides a method for forming a vehicle body based on a low-VOC composite material. It has the following beneficial effects:

[0027] The present invention provides a vehicle body forming method based on low-VOC composite materials. Through multi-axial fiber laying and local reinforcement technology, customized design can be carried out according to the stress characteristics of different parts of the vehicle body, ensuring the strength and stiffness of each key part, avoiding material waste and excess performance. Secondly, the vacuum-assisted resin transfer molding process can improve the bonding quality of fiber and resin, and ensure the uniformity and high performance of the material by eliminating bubbles and forcing resin penetration. Compared with the traditional hand lay-up process, the amount of resin is reduced, and the production cost and vehicle body weight are reduced. In addition, the multi-material integrated molding method adopted by the present invention can flexibly select materials according to the needs of different parts to achieve the optimal performance combination, while the traditional process can usually only use a single material, which limits the performance improvement. The present invention effectively disperses stress concentration through the hybrid technology of bonding and mechanical connection, and enhances the stability and durability of the vehicle body structure. The large number of mechanical connections in the traditional process not only increase the weight, but also may cause stress concentration and affect the overall performance. Strict quality control and non-destructive testing further ensure the reliability and consistency of the product, which are difficult to achieve with traditional processes. DETAILED DESCRIPTION

[0028] Example 1

[0029] The embodiment of the present invention provides a method for forming a vehicle body based on a low-VOC composite material, which specifically includes the following steps:

[0030] S1. Multiaxial fiber laying

[0031] According to the stress conditions of different parts of the car body, glass fiber or carbon fiber material is selected, and then the fiber cloth is cut and laid on the workbench in four directions of 0°, ±45°, and 90°. The thickness of each layer is controlled at 0.2mm.

[0032] S2. Preforming

[0033] Using three-dimensional weaving or knitting technology, the fiber cloth is prefabricated into a preform close to the shape of the body part, with 4 fiber layers and a weaving density of 80%;

[0034] S3. Local fiber reinforcement

[0035] Finite element analysis is used to determine the areas of the vehicle body that are subject to the greatest stress, such as the vehicle body frame and connection parts. Two layers of aramid fiber are added to the designed areas. The tensile strength of the aramid fiber is preferably 3000MPa.

[0036] S4. Vacuum Assisted Resin Transfer Molding

[0037] Prepare the mold, clean the mold surface to ensure that it is dust-free and dirt-free, lay the prefabricated fiber preform on the mold, ensure that the fiber is tightly attached to the mold surface, use a vacuum bag to seal the mold and the fiber preform, ensure that there is no air leakage in the system, turn on the vacuum pump, maintain the vacuum degree at -0.08MPa, and then inject the resin. The resin is evenly injected into the fiber layer through the vacuum negative pressure to ensure that the resin fully infiltrates the fiber. Heat the mold to 80°C for curing. The curing time is controlled within 1 hour. The resin uses a polyester resin with a low styrene content, and the resin is added with alkaline montmorillonite, M50 curing agent, accelerator, and styrene inhibitor;

[0038] S5. Curing and post-processing

[0039] After demoulding, the body parts may have some excess resin or uneven fiber edges, so they need to be trimmed. Use mechanical cutting tools or high-pressure water jets to accurately cut the body parts to remove excess materials and burrs, and then use fine sandpaper or polishing tools to polish the edges. The polishing tool is 800. After the product is trimmed, send the product to the oven at a baking temperature of 80°C for 24 hours.

[0040] S6. Component assembly

[0041] Use structural adhesive to bond different car body parts together. Structural adhesive can not only provide high-strength connection, but also disperse stress and improve the durability of the overall structure. Apply structural adhesive evenly on the connection surface of the parts. The thickness of the adhesive layer should be controlled at 0.5. After application, wait for 24 hours for the structural adhesive to cure naturally.

[0042] Example 2

[0043] The embodiment of the present invention provides a method for forming a vehicle body based on a low-VOC composite material, which specifically includes the following steps:

[0044] S1. Multiaxial fiber laying

[0045] According to the stress conditions of different parts of the car body, glass fiber or carbon fiber material is selected, and then the fiber cloth is cut and laid on the workbench in four directions of 0°, ±45°, and 90°. The thickness of each layer is controlled at 0.4mm.

[0046] S2. Preforming

[0047] Using three-dimensional weaving or knitting technology, the fiber cloth is prefabricated into a preform close to the shape of the body part, with 7 fiber layers and a weaving density of 85%;

[0048] S3. Local fiber reinforcement

[0049] Finite element analysis is used to determine the areas of the vehicle body that are subject to the greatest stress, such as the body frame and connection parts. Three layers of aramid fiber are added to the designed areas. The tensile strength of the aramid fiber is preferably 3000MPa.

[0050] S4. Vacuum Assisted Resin Transfer Molding

[0051] Prepare the mold, clean the mold surface to ensure that it is dust-free and dirt-free, lay the prefabricated fiber preform on the mold, ensure that the fiber is tightly attached to the mold surface, use a vacuum bag to seal the mold and the fiber preform, ensure that there is no air leakage in the system, turn on the vacuum pump, maintain the vacuum degree at -0.07MPa, and then inject the resin. Use the vacuum negative pressure to evenly inject the resin into the fiber layers to ensure that the resin fully infiltrates the fiber, heat the mold to 100℃, and cure it. The curing time is controlled at 1.5 hours. The resin is a polyester resin with a low styrene content;

[0052] S5. Curing and post-processing

[0053] After demoulding, the body parts may have some excess resin or uneven fiber edges, so they need to be trimmed. Use mechanical cutting tools or high-pressure water jets to accurately cut the body parts to remove excess materials and burrs, and then use fine sandpaper or polishing tools to polish the edges. The polishing tool should be 900 mesh. After the product is trimmed, send the product to the oven at a baking temperature of 80°C for 24 hours.

[0054] S6. Component assembly

[0055] Use structural adhesive to bond different car body parts together. Structural adhesive can not only provide high-strength connection, but also disperse stress and improve the durability of the overall structure. Apply structural adhesive evenly on the connection surface of the parts. The thickness of the adhesive layer should be controlled at 0.7mm. After application, wait for 24 hours for the structural adhesive to cure naturally.

[0056] Example 3

[0057] The embodiment of the present invention provides a method for forming a vehicle body based on a low-VOC composite material, which specifically includes the following steps:

[0058] S1. Multiaxial fiber laying

[0059] According to the stress conditions of different parts of the car body, glass fiber or carbon fiber material is selected, and then the fiber cloth is cut and laid on the workbench in four directions of 0°, ±45°, and 90°. The thickness of each layer is controlled at 0.5mm.

[0060] S2. Preforming

[0061] Using three-dimensional weaving or knitting technology, the fiber cloth is prefabricated into a preform close to the shape of the body part, with 8 fiber layers and a weaving density of 90%;

[0062] S3. Local fiber reinforcement

[0063] Finite element analysis is used to determine the areas of the vehicle body that are subject to the greatest stress, such as the body frame and connection parts. Three layers of aramid fiber are added to the designed areas. The tensile strength of the aramid fiber is preferably 3000MPa.

[0064] S4. Vacuum Assisted Resin Transfer Molding

[0065] Prepare the mold, clean the mold surface to ensure that it is dust-free and dirt-free, lay the prefabricated fiber preform on the mold, ensure that the fiber fits tightly to the mold surface, use a vacuum bag to seal the mold and the fiber preform, ensure that there is no air leakage in the system, turn on the vacuum pump, maintain the vacuum degree at -0.09MPa, and then inject the resin. Use the vacuum negative pressure to evenly inject the resin into the fiber layers to ensure that the resin fully infiltrates the fiber, heat the mold to 120℃, and cure it. The curing time is controlled within 2 hours. The resin is a polyester resin with a low styrene content;

[0066] S5. Curing and post-processing

[0067] After demoulding, the body parts may have some excess resin or uneven fiber edges, so they need to be trimmed. Use mechanical cutting tools or high-pressure water jets to accurately cut the body parts to remove excess materials and burrs, and then use fine sandpaper or polishing tools to polish the edges. Choose 1000 mesh for the polishing tool.

[0068] S6. Component assembly

[0069] Use structural adhesive to bond different car body parts together. Structural adhesive can not only provide high-strength connection, but also disperse stress and improve the durability of the overall structure. Apply structural adhesive evenly on the connection surface of the parts. The thickness of the adhesive layer should be controlled at 1mm. After application, wait for 24 hours for the structural adhesive to cure naturally.

[0070] Through the precisely controlled multi-axis fiber laying technology, the fiber angle, number of layers and distribution can be customized according to the stress characteristics and structural requirements of different parts of the car body, ensuring that each key part obtains the best strength and stiffness, avoiding the problems of material waste and excess performance in traditional processes. At the same time, local reinforcement technology further improves the durability and fatigue resistance of these key areas by adding additional fiber layers or using high-strength materials to reinforce the stress-concentrated areas of the car body (such as connection points and corners), effectively preventing damage and deformation during long-term use. The application of vacuum-assisted resin transfer molding (VARTM) technology ensures the perfect combination of fiber and resin. By eliminating bubbles and forcing resin penetration in a vacuum environment, the fiber can be fully infiltrated, avoiding the uneven resin distribution and high porosity problems common in traditional hand-layup processes, thereby greatly improving the mechanical properties and environmental resistance of composite materials. In addition, the VARTM process also significantly reduces the amount of resin used, reducing production costs and body weight. Innovative multi-material integrated molding technology allows the use of different types of fiber materials and resin matrices in the same body structure, such as using carbon fiber in areas where high strength is required, and glass fiber or aramid fiber in areas where high toughness or energy absorption is required, thereby achieving the best combination of performance. Through this flexible material selection and integrated molding, the overall weight of the body can be further reduced, while the performance is significantly improved. The introduction of hybrid bonding and mechanical connection technology disperses stress concentration while ensuring the connection strength, enhancing the stability and durability of the body structure. Compared with simple bonding or riveting, this hybrid connection method can effectively cope with multi-dimensional stress under complex working conditions. The application of non-destructive testing technology, such as ultrasonic testing and X-ray imaging, ensures the uniform distribution of fibers and resins inside the body and the absence of internal defects, thereby improving the reliability and safety of the product. Strict quality control processes and multi-stage performance tests (including bending strength, torsional stiffness, impact strength, etc.) further ensure the consistency and high quality of body manufacturing, so that the final product not only performs well in lightweight, but also has excellent strength, stiffness and durability, and can meet various complex working conditions and high performance requirements.

[0071] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for forming a car body based on a low-VOC composite material, characterized in that: The specific steps include: S1. Multiaxial fiber laying According to the stress conditions of different parts of the car body, choose glass fiber or carbon fiber material, then cut the fiber cloth, and lay the fiber cloth in four directions of 0°, ±45°, and 90° on the workbench in sequence; S2. Preforming Using three-dimensional weaving or knitting technology, the fiber cloth is prefabricated into a preform close to the shape of the body part; S3. Local fiber reinforcement Finite element analysis is used to determine the areas of the vehicle body that are subject to the greatest stress, such as the body frame and joints, and 2 to 3 layers of aramid fiber are added to the designed areas; S4. Vacuum Assisted Resin Transfer Molding Prepare the mold, clean the mold surface to ensure it is dust-free, lay the prefabricated fiber preform on the mold, ensure that the fiber fits tightly to the mold surface, use a vacuum bag to seal the mold and the fiber preform, ensure that there is no air leakage in the system, turn on the vacuum pump, and then inject the resin. Use the vacuum negative pressure to evenly inject the resin between the fiber layers to ensure that the resin fully infiltrates the fiber, and heat the mold to 80℃ to 120℃ for curing; S5. Curing and post-processing After demoulding, the body parts may have some excess resin or uneven fiber edges, so they need to be trimmed. Use mechanical cutting tools or high-pressure water jets to accurately cut the body parts, remove excess materials and burrs, and then use fine sandpaper or polishing tools to polish the edges. After the product is trimmed, send the product to the oven at a baking temperature of 80°C for 24 hours. S6. Component assembly Use structural adhesive to bond different car body parts together. Structural adhesive can not only provide high-strength connection, but also disperse stress and improve the durability of the overall structure. Apply structural adhesive evenly on the connection surface of the parts. After application, wait for 24 hours for the structural adhesive to cure naturally.

2. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: In the multiaxial fiber laying step S1, the thickness of each layer is controlled to be 0.2 mm to 0.5 mm.

3. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: The number of fiber layers in the preforming in step S2 is 4 to 8, and the weaving density is 80% to 90%.

4. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: The tensile strength of the aramid fiber in the fiber local reinforcement in step S3 is preferably 3000 MPa.

5. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: In the vacuum-assisted resin transfer molding in step S4, the vacuum degree is maintained at -0.08 MPa to -0.09 MPa, the curing time is controlled at 1 to 2 hours, and the resin is a polyester resin with a low styrene content.

6. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: In the step S5 of curing and post-processing, the polishing tool is selected to be 800-1000 mesh.

7. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: In the step S6, the thickness of the glue layer in the component assembly is controlled to be between 0.5 mm and 1 mm.

8. The method for forming a vehicle body based on a low-VOC composite material according to claim 1, characterized in that: After the mold surface is cleaned in step S4, a layer of adsorption structure is added to the mold, and adsorption particles are placed in the adsorption structure.

9. The method for forming a vehicle body based on a low-VOC composite material according to claim 5, characterized in that: The resin is added with alkaline montmorillonite, M50 curing agent, accelerator and styrene inhibitor.