Carbon fiber mid-passage adapted to variable-thickness foam sandwich and its hp-rtm process forming method

Abstract

This invention discloses a carbon fiber central channel adapted to unequal-thickness foam sandwich and its HP-RTM molding method, belonging to the field of carbon fiber composite automotive parts molding technology. The unequal-thickness foam core layer is made of high-strength rigid foam resistant to high temperatures. Both the outer and inner carbon fiber skin layers use continuous carbon fiber fabric as reinforcement, which is bonded to the unequal-thickness foam core layer via a resin matrix to form a sandwich composite structure with no gaps between layers. The unequal-thickness foam core layer is a gradually varying thickness structure adapted to the spatial arrangement and load distribution of the automotive central channel. The carbon fiber sandwich composite structure of this invention uses an unequal-thickness foam core layer in the central channel, with a local thickness of 75mm. The thickness gradually varies with the vehicle body load and spatial arrangement, satisfying both the spatial arrangement requirements of the thicker areas of the central channel and the lightweight and load-bearing requirements of the thinner areas. The interlayer composite carbon fiber skin and foam core layer form a high-strength sandwich structure with excellent mechanical properties, reducing weight by 30%-40% compared to a metal central channel.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber composite automotive parts molding technology, and specifically relates to a carbon fiber central channel adapted to foam cores of unequal thickness and its HP-RTM process molding method. Background Technology

[0002] As the automotive industry rapidly develops towards lightweighting, high performance, and energy conservation, carbon fiber composite materials, with their advantages of high specific strength, high specific modulus, corrosion resistance, and strong design flexibility, are increasingly widely used in automotive bodies and core components. The automotive center tunnel, as a crucial structural component, bears the functions of load-bearing, wiring, and pedal placement, and therefore has stringent requirements for structural strength, stiffness, and lightweighting.

[0003] Currently, composite material molding for automotive center tunnels primarily employs processes such as RTM, SMC, and autoclave molding, which suffer from issues like insufficient strength, low molding efficiency, uneven resin impregnation, and numerous internal defects. Some HP-RTM molding solutions only involve step-by-step molding followed by bonding and mechanical joining, increasing process costs, reducing overall structural strength, and making joints prone to becoming weak points. Therefore, it's difficult to simultaneously achieve both product strength and production efficiency, resulting in problems such as low molding efficiency, poor dimensional accuracy, or insufficient strength. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon fiber central channel that is compatible with foam cores of varying thicknesses and its HP-RTM molding method, which solves the problems of insufficient lightweighting, insufficient strength, poor structural and spatial adaptability, low molding efficiency of composite materials and difficulty in ensuring dimensional accuracy of existing central channels, and realizes the integrated molding of central channels, taking into account structural strength, lightweighting and mass production.

[0005] To solve the above technical problems, the present invention provides a carbon fiber central channel adapted to foam cores of unequal thickness, comprising a carbon fiber outer skin layer, a foam core layer of unequal thickness, and a carbon fiber inner skin layer.

[0006] The unequal thickness foam core layer is made of high-strength rigid foam resistant to high temperature, and its outer contour matches the cavity contour of the car's central channel.

[0007] Both the outer carbon fiber skin layer and the inner carbon fiber skin layer use continuous carbon fiber fabric as reinforcement, and are bonded to the foam core layer of unequal thickness through a resin matrix to form a sandwich composite structure with no gaps between the layers.

[0008] The unequal thickness foam core layer is a gradually thickened structure adapted to the layout of the vehicle's central passage space and load distribution. The thickest part of the core layer is 75mm, and the thickness of the remaining areas gradually varies with the vehicle's load distribution and the requirements of the surrounding component layout.

[0009] Preferably, the thickest part of the unequal-thickness foam core layer is 75mm, and the thickness of the remaining areas gradually changes linearly with the vehicle body load distribution and the arrangement requirements of surrounding components.

[0010] Preferably, the thickest part of the unequal-thickness foam core layer is 75mm, and the thickness of the remaining areas gradually changes in steps according to the vehicle body load distribution and the arrangement requirements of surrounding components.

[0011] Preferably, the thickest part of the unequal-thickness foam core layer is 75mm, and the thickness of the remaining areas ranges from 20mm to 75mm.

[0012] Preferably, the carbon fiber outer skin layer and the carbon fiber inner skin layer are laid up in a symmetrical, balanced manner, with a layup design that reinforces the main load-bearing direction at 0°.

[0013] Preferably, the total thickness of the carbon fiber outer skin layer and the carbon fiber inner skin layer is 1.5mm-3.5mm.

[0014] The present invention also provides a method for forming carbon fiber with a central channel HP-RTM process, comprising the following steps:

[0015] Step A: Mold assembly and heating;

[0016] Step A1: Assemble the cavity, core, injection gun head, heating oil pipe, and vacuum pipe of the HP-RTM molding die into place;

[0017] Step A2: Start the mold temperature control system to heat the HP-RTM molding mold to the required temperature and ensure uniform mold temperature;

[0018] Step B: Setting parameters for the press and dispensing machine;

[0019] Step B1: Input the pressing process parameters into the press and save them. Confirm that the pressure, holding time, pressing speed, pressure height, vacuum opening and closing and holding time are correct. Input the glue injection process parameters into the glue injection machine and save them. Ensure that the total glue injection volume, glue injection time, glue injection rate, resin, curing agent and release agent ratio are correct.

[0020] Step C: Preform preparation and inspection;

[0021] Step C1: Cut the carbon fiber fabric on the cutting machine according to the layup design and the cut piece design, and stack them according to the layup;

[0022] Step C2: The carbon fiber fabric is heated, baked, transferred, and pressed on a preforming equipment to obtain a preform;

[0023] Step C3: After the preform is transferred to the laying fixture, trim the excess and lay and position the local reinforcement layer;

[0024] Step C4: Assemble and fit the preform and the foam core layer of unequal thickness and inspect them with tooling;

[0025] Step D: Mold closing and sealing;

[0026] Step D1: Start the press to close the mold, controlling the closing speed within the required range, and gradually increase the closing pressure to the required range to ensure that the preform is wrinkle-free and displacement-free; the mold parting surface adopts a zero-gap sealing structure, the upper mold and lower mold are precisely closed by the press and pre-pressurized, and the mold parting surface is sealed by the sealing component to ensure the sealing of the mold cavity; start the vacuum pump to start vacuuming to ensure that the vacuum degree in the mold cavity meets the requirements;

[0027] Step E: High-pressure injection and pressure-holding curing;

[0028] Step E1: Start the HP-RTM injection system and inject the low-shrinkage epoxy resin matrix into the mold cavity at an injection pressure of 8MPa-15MPa. The injection speed is 80g / s-180g / s. The resin quickly fills the cavity through the injection channel. After injection, close the injection port and continue to close the mold and apply pressure to the bottom. The holding pressure is 6MPa-8MPa, and the holding pressure is maintained for 3-5 minutes until the resin is cured.

[0029] Step F: Cooling, demolding, and post-processing;

[0030] Step F1: After curing, open the mold to demold and take out the central channel part; after demolding, the part needs to be cooled and shaped to room temperature, and then the part is preliminarily inspected and sent for post-processing.

[0031] Preferably, the injection gate and injection channel of the HP-RTM molding die need to be simulated and verified in advance to shorten the injection time and avoid air bubbles and dry yarn caused by air being trapped in the part.

[0032] Preferably, the viscosity of the low-shrinkage epoxy resin matrix is ​​200 mPa·s-300 mPa·s, which is suitable for the high-pressure rapid dispensing and rapid curing requirements of the HP-RTM process.

[0033] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0034] 1. In the carbon fiber sandwich composite structure of the present invention, the channel adopts a foam core layer of unequal thickness, with a local thickness of 75mm. The thickness gradually changes with the vehicle body load and spatial arrangement, which not only meets the spatial arrangement requirements of the thick area of ​​the channel (such as battery and wiring harness arrangement), but also takes into account the lightweight and load-bearing requirements of the thin area. The carbon fiber skin and foam core layer composite between the layers form a high-strength sandwich structure with excellent mechanical properties, and the weight is reduced by 30%-40% compared with the metal channel.

[0035] 2. The carbon fiber sandwich structure of the present invention has an integrally formed channel without splicing seams, good structural integrity, strong impact resistance and deformation resistance, and the composite structure of carbon fiber and foam has good corrosion resistance and long service life. It is suitable for the manufacture of the channel of various new energy vehicles and fuel vehicles and has a wide range of applications.

[0036] 3. This invention employs the HP-RTM process to achieve integrated molding of the central channel. The mold is designed with shrinkage compensation allowance, and precise temperature and pressure control is maintained throughout the entire process of mold closing, glue injection, pressure holding, and curing. Cutting is performed after demolding. Moreover, this molding method has a simple process, high efficiency in mold closing and glue injection, and a short curing cycle. Compared with the traditional autoclave process, the molding efficiency is improved by 3-5 times, which is suitable for the mass production needs of automotive parts. The molding mold is easy to disassemble and assemble, has precise positioning, and good sealing performance, enabling uninterrupted continuous operation in industrial production. Attached Figure Description

[0037] Figure 1 An exploded view of the carbon fiber channel adapted to foam cores of unequal thickness provided by the present invention.

[0038] Figure 2 A cross-sectional view of the carbon fiber channel adapted to foam cores of unequal thickness provided by the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the carbon fiber outer skin layer provided by the present invention;

[0040] Figure 4 A schematic diagram of the structure of the unequal thickness foam core layer provided by the present invention;

[0041] Figure 5 This is a schematic diagram of the structure of the carbon fiber inner skin layer provided by the present invention.

[0042] The meanings of the markings in the attached diagram are as follows:

[0043] In the figure: 1. Carbon fiber outer skin layer; 2. Uneven thickness foam core layer; 3. Carbon fiber inner skin layer. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0045] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] Example

[0048] This invention provides a carbon fiber central channel adapted to foam cores of varying thicknesses; please refer to [link / reference]. Figure 1-5 It includes a carbon fiber outer skin layer 1, an unequal thickness foam core layer 2, and a carbon fiber inner skin layer 3; the unequal thickness foam core layer 2 is made of high-temperature resistant, high-strength rigid foam, and its outer contour matches the cavity contour of the vehicle's central tunnel; both the carbon fiber outer skin layer 1 and the carbon fiber inner skin layer 3 use continuous carbon fiber fabric as reinforcement, and are bonded to the unequal thickness foam core layer 2 through a resin matrix to form a sandwich composite structure without gaps between layers; the unequal thickness foam core layer 2 is a gradually thickened structure adapted to the spatial arrangement and load distribution of the vehicle's central tunnel, with the thickest part of the core layer being 75mm, and the thickness of the remaining areas gradually changing according to the vehicle's load distribution and the requirements of the surrounding component arrangement.

[0049] The carbon fiber sandwich composite structure of the present invention uses a foam core layer of unequal thickness in the channel, with a local thickness of 75mm. The thickness gradually changes with the vehicle body load and spatial arrangement, which not only meets the spatial arrangement requirements of the thick area of ​​the channel (such as battery and wiring harness arrangement), but also takes into account the lightweight and load-bearing requirements of the thin area. The carbon fiber skin and foam core layer of the interlayer composite form a high-strength sandwich structure with excellent mechanical properties, and the weight is reduced by 30%-40% compared with the metal channel.

[0050] In one embodiment, the thickest part of the unequal-thickness foam core layer 2 is 75mm, and the thickness of the remaining areas gradually changes linearly with the vehicle body load distribution and the arrangement requirements of surrounding components.

[0051] In another embodiment, the thickest part of the unequal-thickness foam core layer 2 is 75mm, and the thickness of the remaining areas gradually changes in steps according to the vehicle load distribution and the arrangement requirements of surrounding components.

[0052] In this embodiment, the thickest part of the unequal thickness foam core layer 2 is 75mm, and the thickness of the remaining areas ranges from 20mm to 75mm.

[0053] Furthermore, the carbon fiber outer skin layer 1 and the carbon fiber inner skin layer 3 are laid up in a symmetrical, balanced manner, with a layup design that reinforces the main load-bearing direction at 0°.

[0054] Furthermore, the total thickness of the carbon fiber outer skin layer 1 and the carbon fiber inner skin layer 3 is both 1.5mm-3.5mm.

[0055] The carbon fiber sandwich structure of this invention features an integrally molded channel without seams, resulting in excellent structural integrity, strong impact resistance and deformation resistance. Furthermore, the composite structure of carbon fiber and foam exhibits good corrosion resistance and a long service life, making it suitable for manufacturing the central channels of various new energy vehicles and fuel vehicles, with a wide range of applications.

[0056] The present invention also provides a method for forming carbon fiber with a central channel HP-RTM process, comprising the following steps:

[0057] Step A: Mold assembly and heating;

[0058] Step A1: Assemble the cavity, core, injection gun head, heating oil pipe, and vacuum pipe of the HP-RTM molding die into place;

[0059] Step A2: Start the mold temperature control system to heat the HP-RTM molding mold to the required temperature and ensure uniform mold temperature;

[0060] Step B: Setting parameters for the press and dispensing machine;

[0061] Step B1: Input the pressing process parameters into the press and save them. Confirm that the pressure, holding time, pressing speed, pressure height, vacuum opening and closing and holding time are correct. Input the glue injection process parameters into the glue injection machine and save them. Ensure that the total glue injection volume, glue injection time, glue injection rate, resin, curing agent and release agent ratio are correct.

[0062] Step C: Preform preparation and inspection;

[0063] Step C1: Cut the carbon fiber fabric on the cutting machine according to the layup design and the cut piece design, and stack them according to the layup;

[0064] Step C2: The carbon fiber fabric is heated, baked, transferred, and pressed on a preforming equipment to obtain a preform;

[0065] Step C3: After the preform is transferred to the laying fixture, trim the excess and lay and position the local reinforcement layer;

[0066] Step C4: Assemble and fit the preform and the unequal thickness foam core layer 2, and inspect them using tooling;

[0067] Step D: Mold closing and sealing;

[0068] Step D1: Start the press to close the mold, controlling the closing speed within the required range, and gradually increase the closing pressure to the required range to ensure that the preform is wrinkle-free and displacement-free; the mold parting surface adopts a zero-gap sealing structure, the upper mold and lower mold are precisely closed by the press and pre-pressurized, and the mold parting surface is sealed by the sealing component to ensure the sealing of the mold cavity; start the vacuum pump to start vacuuming to ensure that the vacuum degree in the mold cavity meets the requirements;

[0069] Step E: High-pressure injection and pressure-holding curing;

[0070] Step E1: Start the HP-RTM injection system and inject the low-shrinkage epoxy resin matrix into the mold cavity at an injection pressure of 8MPa-15MPa. The injection speed is 80g / s-180g / s. The resin quickly fills the cavity through the injection channel. After injection, close the injection port and continue to close the mold and apply pressure to the bottom. The holding pressure is 6MPa-8MPa, and the holding pressure is maintained for 3-5 minutes until the resin is cured.

[0071] Step F: Cooling, demolding, and post-processing;

[0072] Step F1: After curing, open the mold to demold and take out the central channel part; after demolding, the part needs to be cooled and shaped to room temperature, and then the part is preliminarily inspected and sent for post-processing.

[0073] Specifically, the injection gate and injection channel of the HP-RTM molding mold need to be simulated and verified in advance to shorten the injection time and avoid air bubbles and dry yarn caused by air being trapped in the part.

[0074] Specifically, the viscosity of the low-shrinkage epoxy resin matrix is ​​200 mPa·s-300 mPa·s (70℃-80℃), which is suitable for the high-pressure rapid dispensing and rapid curing requirements of the HP-RTM process.

[0075] This invention employs the HP-RTM process to achieve integrated molding of the central channel. The mold is designed with shrinkage compensation allowance, and precise temperature and pressure control is maintained throughout the entire process of mold closing, glue injection, pressure holding, and curing. Cutting is performed after demolding. Moreover, this molding method has a simple process, high efficiency in mold closing and glue injection, and a short curing cycle. Compared with the traditional autoclave process, the molding efficiency is improved by 3-5 times, which is suitable for the mass production needs of automotive parts. The molding mold is easy to assemble and disassemble, has precise positioning, and good sealing performance, enabling uninterrupted continuous operation in industrial production.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A carbon fiber central channel adapted to foam cores of varying thicknesses, characterized in that, It includes a carbon fiber outer skin layer (1), an unequal thickness foam core layer (2), and a carbon fiber inner skin layer (3). The unequal thickness foam core layer (2) is made of high-temperature resistant high-strength rigid foam, and its outer contour matches the cavity contour of the car's central channel. Both the outer carbon fiber skin layer (1) and the inner carbon fiber skin layer (3) are made of continuous carbon fiber fabric as reinforcement, and are bonded to the foam core layer (2) of unequal thickness through a resin matrix to form a sandwich composite structure with no gaps between the layers. The unequal thickness foam core layer (2) is a gradually thickened structure adapted to the channel space layout and load distribution in the car. The thickest part of the core layer is 75mm, and the thickness of the remaining areas gradually changes with the load distribution of the vehicle body and the requirements of the surrounding component layout.

2. The carbon fiber central channel for adapting to foam cores of unequal thickness according to claim 1, characterized in that, The thickest part of the unequal thickness foam core layer (2) is 75mm, and the thickness of the remaining areas gradually changes linearly with the distribution of vehicle load and the requirements of the surrounding component layout.

3. The carbon fiber central channel adapted to foam cores of unequal thickness according to claim 1, characterized in that, The thickest part of the unequal thickness foam core layer (2) is 75mm, and the thickness of the remaining areas gradually changes stepwise according to the vehicle load distribution and the requirements of the surrounding component layout.

4. The carbon fiber central channel adapted to foam cores of unequal thickness according to claim 2 or 3, characterized in that, The thickest part of the unequal thickness foam core layer (2) is 75mm, and the thickness range of the remaining areas is 20mm-75mm.

5. The carbon fiber central channel adapted to foam cores of unequal thickness according to claim 1, characterized in that, The carbon fiber outer skin layer (1) and the carbon fiber inner skin layer (3) are laid up in a symmetrical and balanced manner, with a layup design that strengthens the main load-bearing direction at 0°.

6. The carbon fiber central channel adapted to foam cores of unequal thickness according to claim 1, characterized in that, The total thickness of the carbon fiber outer skin layer (1) and the carbon fiber inner skin layer (3) is 1.5mm-3.5mm.

7. A method for forming carbon fiber with a central channel using HP-RTM process, characterized in that, Includes the following steps: Step A: Mold assembly and heating; Step A1: Assemble the cavity, core, injection gun head, heating oil pipe, and vacuum pipe of the HP-RTM molding die into place; Step A2: Start the mold temperature control system to heat the HP-RTM molding mold to the required temperature and ensure uniform mold temperature; Step B: Setting parameters for the press and dispensing machine; Step B1: Input the pressing process parameters into the press and save them. Confirm that the pressure, holding time, pressing speed, pressure height, vacuum opening and closing and holding time are correct. Input the glue injection process parameters into the glue injection machine and save them. Ensure that the total glue injection volume, glue injection time, glue injection rate, resin, curing agent and release agent ratio are correct. Step C: Preform preparation and inspection; Step C1: Cut the carbon fiber fabric on the cutting machine according to the layup design and the cut piece design, and stack them according to the layup; Step C2: The carbon fiber fabric is heated, baked, transferred, and pressed on a preforming equipment to obtain a preform; Step C3: After the preform is transferred to the laying fixture, trim the excess and lay and position the local reinforcement layer; Step C4: Assemble and fit the preform and the foam core layer of unequal thickness (2) and inspect with tooling; Step D: Mold closing and sealing; Step D1: Start the press to close the mold, controlling the closing speed within the required range, and gradually increase the closing pressure to the required range to ensure that the preform is wrinkle-free and displacement-free; the mold parting surface adopts a zero-gap sealing structure, the upper mold and lower mold are precisely closed by the press and pre-pressurized, and the mold parting surface is sealed by the sealing component to ensure the sealing of the mold cavity; start the vacuum pump to start vacuuming to ensure that the vacuum degree in the mold cavity meets the requirements; Step E: High-pressure injection and pressure-holding curing; Step E1: Start the HP-RTM injection system and inject the low-shrinkage epoxy resin matrix into the mold cavity at an injection pressure of 8MPa-15MPa. The injection speed is 80g / s-180g / s. The resin quickly fills the cavity through the injection channel. After injection, close the injection port and continue to close the mold and apply pressure to the bottom. The holding pressure is 6MPa-8MPa, and the holding pressure is maintained for 3-5 minutes until the resin is cured. Step F: Cooling, demolding, and post-processing; Step F1: After curing, open the mold to demold and take out the central channel part; after demolding, the part needs to be cooled and shaped to room temperature, and then the part is preliminarily inspected and sent for post-processing.

8. The carbon fiber in-channel HP-RTM forming method according to claim 1, characterized in that, The injection gate and injection channel of the HP-RTM molding die need to be simulated and verified in advance to shorten the injection time and avoid air bubbles and dry yarn caused by air being trapped in the part.

9. The carbon fiber in-channel HP-RTM forming method according to claim 1, characterized in that, The viscosity of the low-shrinkage epoxy resin matrix is ​​200 mPa·s-300 mPa·s, which is suitable for the high-pressure rapid dispensing and rapid curing requirements of the HP-RTM process.

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