A method for gradient compression molding of a carbon fiber wheel hub and a carbon fiber wheel hub

Abstract

The application provides a method for gradient mold pressing of a carbon fiber wheel hub and the carbon fiber wheel hub. First, carbon fiber prepreg is automatically laid on the surface of a split rim core mold, each layer of the carbon fiber prepreg is coated with a sliding coating material, and a preformed carbon fiber rim blank is obtained; the preformed carbon fiber rim blank is subjected to a low-temperature high-pressure first-stage mold pressing machine and a medium-temperature low-pressure second-stage mold pressing machine to obtain a pre-solidified carbon fiber rim; the core mold is removed and the carbon fiber rim is high-temperature solidified under the action of a sizing ring to obtain a carbon fiber rim; the spoke disc and the carbon fiber rim are connected by a bolt at an annular convex edge, dynamic balance detection is performed, and the carbon fiber wheel hub is obtained. The application realizes efficient mold pressing production of the carbon fiber rim through gradient mold pressing of high pressure followed by low pressure, so that the stress concentration in the rim is fully eliminated, and the carbon fiber rim is completely solidified without warping and deformation under the assistance of the sizing ring after the core mold is removed. Through gradient mold pressing process and interlayer sliding cooperation, the high-efficiency mold pressing production of the carbon fiber rim is realized. The mold-pressed rim has high precision, stable quality and low cost.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber wheel hub molding technology, and particularly to carbon fiber wheel hubs formed by compression molding using carbon fiber prepreg, specifically to a method for gradient compression molding of carbon fiber wheel hubs and a carbon fiber wheel hub. Background Technology

[0002] Carbon fiber wheels are made from high-performance carbon fiber. The lightweight nature of carbon fiber significantly reduces the weight of carbon fiber wheels, making them more than 30% lighter than aluminum alloy wheels. This weight reduction significantly lowers the unsprung mass of the vehicle, helping to reduce energy consumption, increase shock absorption, and improve vehicle handling. The extremely high strength and modulus of elasticity of carbon fiber give carbon fiber wheels excellent structural strength, fatigue resistance, and durability.

[0003] Currently, carbon fiber wheels are gradually penetrating the market from racing cars and supercars to ordinary passenger cars. The main pain point is the high cost. On the one hand, carbon fiber materials are expensive; on the other hand, the molding process of carbon fiber wheels is complex, making stable mass production difficult, which leads to a long-term high price.

[0004] The existing molding processes for carbon fiber wheels mainly employ autoclave molding and resin transfer molding (RTM). Both processes have technical bottlenecks in the stable mass production of carbon fiber wheels. The autoclave process involves precisely cutting carbon fiber prepreg according to the wheel's size and curvature, layering it on a wheel mold to form a wheel blank, sealing it in a vacuum bag, and then placing it in an autoclave for curing. Because the autoclave process is a one-step molding, the orientation of the carbon fiber prepreg is limited by the irregular structure of the wheel. Layering requires precise cutting and layering, sometimes even requiring manual lay-up. Curing relies on the vacuum bag pressing in the autoclave, which cannot guarantee the precise shape and size of the wheel. Significant machining is required after curing, making mass production impossible. The resin transfer molding (RTM) process involves winding and weaving carbon fiber tows into a preform for the wheel, placing it in a closed mold, and then injecting viscous resin into the mold cavity under high pressure to fully impregnate the carbon fiber, followed by thermosetting to obtain the carbon fiber wheel. This process produces carbon fiber wheels with higher performance and higher precision. However, the current carbon fiber winding technology is still immature, requiring advanced equipment and posing challenges to large-scale production, resulting in extremely high manufacturing costs and severely restricting its market promotion. Therefore, overcoming the manufacturing process bottlenecks of carbon fiber wheels and reducing costs has become crucial for carbon fiber wheels to enter the automotive market.

[0005] Carbon fiber wheels currently mainly come in two types: full carbon wheels and semi-carbon wheels (two-in-one carbon-aluminum wheels). Full carbon wheels have both the rim and spokes made of carbon fiber composite materials. If autoclave molding is used, the complex and curved spokes are extremely difficult to lay up, requiring manual layering, resulting in high manufacturing difficulty and cost. Semi-carbon wheels (two-in-one carbon-aluminum wheels) are a design approach that combines carbon fiber with aluminum alloy. The rim is made of carbon fiber, and the spokes are made of aluminum alloy, effectively balancing lightweight and strength. High-strength bolts connect the rim and spokes. While the rim of a semi-carbon wheel is made of carbon fiber, due to its simple structure, we have been aiming to achieve stable mass production of carbon fiber rims through molding processes, thereby simplifying the manufacturing process and reducing costs.

[0006] Compression molding is typically used to shape thermoplastic materials under hot pressure. Existing compression molding of carbon fiber thermosetting prepregs is limited to simple shapes or sheet materials. For example, Chinese patent publication CN109094057B discloses a method for compression molding a carbon fiber automotive hood. According to the designed hood shape, a cutting machine is used to cut the required multi-layered carbon fiber prepreg into a single piece, which is then placed into a mold and directly pressed, heated, and cured. Chinese patent publication CN107187078B discloses a rapid compression molding process for carbon fiber prepregs. Using carbon fiber prepregs as the molding material, rapid molding is achieved through layup and compression molding, improving production efficiency.

[0007] Obviously, the rim structure of the wheel hub is a through-type rim with a small diameter in the middle and a large diameter at the edges. Direct molding requires a mandrel. The mandrel is needed to stabilize the dimensions during the stacking, molding, curing, and cooling processes, requiring a large number of mandrels for mass production. Furthermore, molding requires moderate plastic stretching, which can easily cause tensile damage to the carbon fiber. Chinese patent publication CN103507185B discloses a mold structure for curing carbon fiber automotive wheel hub blanks and a method for manufacturing products using this mold. By using an air-bag mandrel with a shape consistent with the inner cavity of the automotive wheel hub blank, but slightly smaller in size, and heating and pressurizing the inner air bag according to preset values, the pre-formed automotive wheel hub is cured in the mold, achieving one-piece molding and simplifying the production process. However, the air-bag mandrel is difficult to guarantee the precise shape and size of the wheel hub's inner cavity, affecting the dimensional accuracy of the wheel hub. Summary of the Invention

[0008] To achieve stable, low-cost, and mass production of carbon fiber wheels, and addressing the challenge of precise molding of carbon fiber wheels, this invention proposes a gradient molding method for carbon fiber wheels. This method employs a gradient molding compression molding process involving low-temperature, high-pressure pre-forming and medium-temperature, low-pressure pre-curing, with an auxiliary molding ring further cured at high temperatures for an extended period. This achieves efficient and precise molding of carbon fiber wheels, accelerates mandrel turnover, and improves the production efficiency of carbon fiber wheels. Furthermore, this invention provides carbon fiber wheels prepared using this method.

[0009] To achieve the above objectives, the present invention employs the following technical means:

[0010] In a first aspect, the present invention provides a method for gradient molding of carbon fiber wheel hubs, the specific method of which is as follows:

[0011] S1. The carbon fiber prepreg is automatically cut by the cutting machine according to the shape and size of the rim. The carbon fiber prepreg is automatically laid on the surface of the split rim core mold. When laying each layer of carbon fiber prepreg, a sliding coating material is applied to the bonding surface to obtain the preformed carbon fiber rim blank.

[0012] S2. The preformed carbon fiber rim blank, together with the rim core mold, is fed into the first-stage molding press. It is laid flat with the annular convex edge on the top. The upper mold and the left and right side molds are closed at 40~60℃ with a pressure of 2.0~3.5MPa for first-stage molding. The compression holding time is 10~30s to obtain the preformed carbon fiber rim.

[0013] S3. Transfer the pre-shaped carbon fiber rim along with the rim core mold to a two-stage molding press. At a medium temperature of 110~120℃, close the upper mold and the left and right side molds for two-stage molding. The compression holding time is 20~30min to obtain a pre-cured carbon fiber rim.

[0014] S4. Remove the core mold from the pre-cured carbon fiber rim, place the shaping rings on both sides of the rim, and then lay it flat in the heat curing chamber for heat curing at a high temperature of 150~160℃ for 1.0~1.5h. Allow it to cool naturally to room temperature, remove the shaping rings, drill holes in the annular convex edge, grind and spray to obtain the carbon fiber rim.

[0015] S5. The aluminum alloy forged disc is processed by milling machine, precision engraving machine, polishing and spraying to obtain the spoke disc;

[0016] S6. Connect the spoke disc to the carbon fiber rim with bolts on the annular convex edge, perform dynamic balancing test, and obtain the carbon fiber hub.

[0017] Preferably, the separable rim core mold consists of at least four segments. The annular convex edge of the rim is where the rim connects to the spoke disc, and its protruding characteristic makes it difficult to remove the core mold easily. Therefore, a separable rim core mold is used, where each segment is detachable, allowing for better assembly and demolding.

[0018] Preferably, the carbon fiber prepreg is obtained by pre-impregnating epoxy resin onto carbon fiber twill or carbon fiber satin woven fabric, and the epoxy resin content needs to be controlled at 40-45% by mass. More preferably, the density of the carbon fiber twill or carbon fiber satin woven fabric is 1.5-1.6 g / cm³. By selecting carbon fiber fabrics with high epoxy resin content and low density, it is easier for them to undergo local deformation during molding without excessive stretching and damage to the carbon fibers, thus adapting to the molding process and obtaining high-precision carbon fiber rims. Typically, T800H carbon fiber woven fabric with 12K tow is used.

[0019] Preferably, when automatically laying up carbon fiber prepreg, the layers are laid up sequentially at 0° / 45° / -45° / 90° in the winding direction of the prepreg.

[0020] Preferably, the sliding coating material is a low-viscosity sliding coating material prepared by liquid bisphenol F epoxy resin, glass microspheres, and curing agent in a mass ratio of 100:(4~6):(3~5); more preferably, the viscosity of the liquid bisphenol F epoxy resin at 40°C is less than 2000 mPa·s, such as NPEF-170 bisphenol F epoxy resin from Nan Ya Plastics Industrial Co., Ltd., which has low viscosity and high fluidity; more preferably, the glass microspheres are solid glass microspheres with a D50 particle size range of 10~30μm; more preferably, the curing agent is a polyamide curing agent. The glass microspheres have good sliding properties. By adding bisphenol F epoxy resin to prepare the sliding coating material, the good interlayer sliding property facilitates micro-sliding between the carbon fiber prepreg layers during gradient molding, ensuring precise molding without causing excessive tensile damage to the carbon fiber prepreg.

[0021] Preferably, the shaping ring is made of metal or ceramic. Depending on the diameter of the rim, the shaping ring is placed tightly against the inner edges of both sides of the rim to prevent warping and deformation of the rim during high-temperature curing and cooling.

[0022] When carbon fiber prepreg is laminated after being stacked, it is generally laminated during molding, and excessive stretching in other directions is not advisable. Therefore, conventionally, the stacking of multiple carbon fiber prepreg layers for curved structures requires precise cutting, resulting in a complex layup process that requires manual installation to meet requirements, leading to low production efficiency. Furthermore, the presence of a large amount of air between each prepreg layer severely affects product quality. This invention applies a sliding coating material between the carbon fiber prepreg layers. During gradient molding, micro-slippage occurs between the carbon fiber prepreg layers under low temperature and high pressure, ensuring precise pre-forming of the rim and preventing excessive tensile damage to the carbon fiber prepreg under high pressure. Furthermore, the layup precision can be appropriately reduced during carbon fiber prepreg layering, simplifying the layup process and improving production efficiency.

[0023] Conventional molding requires segmented heating and pressurization of the mold for curing, followed by cooling before the next production run. This results in long mold occupancy times, low mandrel turnover, and extremely low production efficiency. This invention employs a gradient molding process—low-temperature high-pressure pre-molding and medium-temperature low-pressure pre-curing—to ensure the precision and quality stability of carbon fiber rims. Two molding machines are used: high-pressure molding at a lower temperature allows for precise shaping of the ply material through micro-sliding, while completely eliminating interlayer air; short-term pre-curing at medium temperature and low pressure pre-cures and shapes the rim, reducing stress concentration and preventing warping. Furthermore, a shaping ring is placed tightly against the inner rim flanges on both sides to prevent deformation. High-temperature, long-term complete curing occurs without a mandrel or pressure, accelerating mandrel turnover and improving production efficiency.

[0024] Secondly, a carbon fiber wheel hub obtained by the above-described gradient molding method is provided.

[0025] Compared with existing technologies, the present invention brings the following technical effects:

[0026] This invention employs a gradient molding process, first applying high pressure and then low pressure, to fully eliminate stress concentration within the rim. As a result, after demolding, the rim can be completely cured at high temperature for an extended period without warping or deformation, aided by a shaping ring.

[0027] In this invention, a coating material that facilitates sliding is applied during the layup of carbon fiber prepreg. During gradient molding, micro-sliding occurs between the carbon fiber prepreg layers, ensuring precise shaping of the rim and preventing excessive tensile damage to the carbon fiber prepreg.

[0028] This invention achieves efficient molding production of carbon fiber rims through gradient molding and interlayer sliding synergy, resulting in rims with high precision and stable quality. The two-in-one carbon fiber wheel hub, assembled using pre-aluminum alloy spoke discs, has low cost and significantly enhances its application potential in ordinary passenger cars. Attached Figure Description

[0029] To more clearly illustrate the technical solution of the present invention, it is further described below in the form of illustrations.

[0030] Figure 1 This is a process flow diagram of the gradient molding carbon fiber wheel hub of the present invention.

[0031] Figure 2 This is a schematic diagram of the two-in-one assembly of the carbon fiber wheel hub of the present invention. In the figure, 1-carbon fiber rim; 2-aluminum alloy wheel spoke; 3-connecting bolt. Detailed Implementation

[0032] To better illustrate the purpose, technical solution, and advantages of this application, the following description, in conjunction with specific embodiments and comparative examples, is intended only to aid in understanding the content of this application and not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this application.

[0033] The raw materials used in this application are commercially available. The sliding coating material is self-made: NPEF-170 bisphenol F epoxy resin from Nan Ya Plastics Industrial Co., Ltd., solid glass microspheres with a D50 particle size range of 10~30μm, and 651 low molecular weight polyamide are formulated in a mass ratio of 100:5:3. The tooling and testing instruments used in the preparation are all owned by the applicant.

[0034] Unless otherwise stated, the terminology used herein is as commonly understood by one of ordinary skill in the art, such as the annular convex edge being the part of a two-piece wheel hub where the rim and spoke disc are connected; the spoke disc can be commonly understood as the middle piece.

[0035] Example 1

[0036] Please refer to the process flow. Figure 1 .

[0037] S1. The carbon fiber prepreg is automatically cut by a cutting machine according to the shape and size of the rim. The carbon fiber prepreg is automatically laid on the surface of the split rim core mold, and the layers are laid in sequence according to the winding direction of the prepreg: 0° / 45° / -45° / 90°. A sliding coating material is applied to the bonding surface when laying each layer of carbon fiber prepreg. A preformed carbon fiber rim blank is obtained. The carbon fiber prepreg is an epoxy resin prepreg of 12K T800H twill carbon fiber weave, with an epoxy resin content of 40% by mass and a twill carbon fiber weave density of 1.5 g / cm³.

[0038] S2. The preformed carbon fiber rim blank, together with the rim core mold (8-petal detachable core mold), is fed into the first-stage molding press. It is laid flat with the annular convex edge on the top. The upper mold and the left and right side molds are closed at 60°C with a pressure of 3.5MPa for first-stage molding. The compression holding time is 20s to obtain the preformed carbon fiber rim.

[0039] S3. Transfer the pre-shaped carbon fiber rim along with the rim core mold to the secondary molding machine. Close the upper mold and left and right side molds at a medium temperature of 120℃ and a pressure of 1.5MPa for secondary molding. The compression holding time is 30min to obtain the pre-cured carbon fiber rim.

[0040] S4. Remove the core mold from the pre-cured carbon fiber rim, place circular metal shaping rings on both sides of the rim, then lay it flat and send it to the heat curing chamber for heat curing at 155℃ for 1.5 hours. Allow it to cool naturally to room temperature, remove the shaping rings, drill holes in the annular convex edge, grind and spray to obtain the carbon fiber rim.

[0041] S5. The aluminum alloy forged disc is processed by milling machine, precision engraving machine, polishing and spraying to obtain the spoke disc;

[0042] S6. Connect the spoke disc to the carbon fiber rim with bolts along the annular convex edge, perform dynamic balancing, and obtain the two-in-one carbon fiber hub. A schematic diagram of the two-in-one carbon fiber hub assembly is shown below. Figure 2 1 is a carbon fiber rim; 2 is an aluminum alloy spoke disc; 3 is a connecting bolt.

[0043] Example 2

[0044] S1. The carbon fiber prepreg is automatically cut by a cutting machine according to the shape and size of the rim. The carbon fiber prepreg is automatically laid on the surface of the split rim core mold, and the layers are laid in sequence according to the winding direction of the prepreg: 0° / 45° / -45° / 90°. A sliding coating material is applied to the bonding surface when laying each layer of carbon fiber prepreg. A preformed carbon fiber rim blank is obtained. The carbon fiber prepreg is an epoxy resin prepreg of 12K T800H twill carbon fiber weave, with an epoxy resin content of 40% by mass and a twill carbon fiber weave density of 1.5 g / cm³.

[0045] S2. The preformed carbon fiber rim blank, together with the rim core mold (8-petal detachable core mold), is fed into the first-stage molding press. It is laid flat with the annular convex edge on the top. The upper mold and the left and right side molds are closed at 40°C with a pressure of 2.5MPa for first-stage molding. The compression holding time is 30s to obtain the preformed carbon fiber rim.

[0046] S3. Transfer the pre-shaped carbon fiber rim along with the rim core mold to the secondary molding machine. At a medium temperature of 110℃, close the upper mold and the left and right side molds for secondary molding. The compression holding time is 20 minutes to obtain the pre-cured carbon fiber rim.

[0047] S4. Remove the core mold from the pre-cured carbon fiber rim, place circular ceramic shaping rings on both sides of the rim, then lay it flat and send it to the heat curing chamber for heat curing at 150℃ for 1.5 hours. Allow it to cool naturally to room temperature, remove the shaping rings, drill holes in the annular convex edge, grind and spray to obtain the carbon fiber rim.

[0048] S5. The aluminum alloy forged disc is processed by milling machine, precision engraving machine, polishing and spraying to obtain the spoke disc;

[0049] S6. Connect the spoke disc to the carbon fiber rim with bolts on the annular convex edge, perform dynamic balancing test, and obtain the carbon fiber hub.

[0050] Comparative Example 1

[0051] Using the pre-formed carbon fiber rim blank from Example 1, along with the rim core mold (8 detachable core molds), it was fed into a molding press, laid flat with the annular convex edge on top. The upper mold and left and right side molds were closed at 1.5 MPa at 60°C for primary molding, with a compression holding time of 20 seconds. The temperature was then raised to 120°C with a pressure of 3.5 MPa for 30 minutes. The temperature was then raised to 155°C for heat curing for 1.5 hours, followed by natural cooling to room temperature. Holes were drilled in the annular convex edge, and the surface was polished and sprayed to obtain the carbon fiber rim. The spoke disc was then bolted to the carbon fiber rim along the annular convex edge, and dynamic balancing was performed to obtain a two-in-one carbon fiber hub.

[0052] A single molding process requires the mold to be cooled down before it can be used again. This process takes a long time, results in low production efficiency, and can lead to warping and deformation.

[0053] Comparative Example 2

[0054] Carbon fiber rims are formed using an autoclave process. The pre-formed carbon fiber rim blank obtained in Example 1 is extracted into a bag by a vacuum pump and compacted under a negative pressure of -0.09MPa. It is then heat-cured in an autoclave at a pressure of 1.5MPa and a high temperature of 155℃ for 1.5 hours. After natural cooling to room temperature, holes are drilled in the annular convex edge, and the rim is polished and sprayed to obtain the carbon fiber rim. The spoke disc is then connected to the carbon fiber rim in the annular convex edge by bolts, and dynamic balancing is performed to obtain a two-in-one carbon fiber hub.

[0055] Autoclave molding cannot guarantee the shape and size of the rim, and extensive machining is required after curing, making mass production impossible.

[0056] Comparative Example 3

[0057] In the implementation of the scheme in Example 1, no sliding coating was applied during the layup process.

[0058] During compression molding, the layers do not easily slide, resulting in low molding precision. Consequently, the final carbon fiber rim has poor dimensional precision and uniformity of mass distribution.

[0059] The dynamic balance and radial runout of the carbon fiber wheel hub were tested to measure the impact of gradient molding on the mass distribution uniformity and dimensional stability of the carbon fiber wheel rim.

[0060] The wheel hub was installed on a dynamic balancing machine to simulate high-speed rotation, and the imbalance was checked to ensure it was ≤5g, meeting the standard. The dynamic balancing data reflects the uniformity of the wheel hub's forming quality distribution and whether the hub's dimensions are warped. Warping or uneven forming quality in the wheel hub will result in an excessive imbalance. The test results are shown in Table 1.

[0061] The wheel hub was mounted on a runout testing platform, and radial runout was measured using a laser runout detector at 200 rpm. A radial runout of ≤0.5 mm was required to meet the standard. A large offset of the wheel hub's circumferential surface from the ideal center of rotation indicates a large deviation in wheel hub roundness. The test results are shown in Table 1.

[0062] Table 1:

[0063]

[0064] The test data in Table 1 show that the present invention can precisely plasticize the rim by gradient molding, and the mass distribution is more uniform compared with the rim formed by one-time molding and autoclave molding. Moreover, the high pressure followed by low pressure molding fully eliminates stress, and the rim has good roundness and small radial runout with the assistance of the shaping ring.

[0065] It should be noted that although the above embodiments have been described in detail with reference to preferred solutions, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application, all of which fall within the protection scope of the application.

Claims

1. A method for gradient molding carbon fiber wheel hubs, characterized in that, The specific method is as follows: S1. The carbon fiber prepreg is automatically cut by the cutting bed according to the shape and size of the rim. The carbon fiber prepreg is automatically laid on the surface of the split rim core mold. When laying each layer of carbon fiber prepreg, a sliding coating material is applied to the bonding surface. Preformed carbon fiber rim blanks were obtained; S2. The preformed carbon fiber rim blank, together with the rim core mold, is fed into the first-stage molding press. It is laid flat with the annular convex edge on the top. The upper mold and the left and right side molds are closed at 40-60℃ with a pressure of 2.0-3.5MPa for first-stage molding. The compression holding time is 10-30s to obtain the preformed carbon fiber rim. S3. Transfer the pre-shaped carbon fiber rim along with the rim core mold to a two-stage molding press. At a medium temperature of 110-120℃, close the upper mold and the left and right side molds for two-stage molding. The compression holding time is 20-30 minutes to obtain a pre-cured carbon fiber rim. S4. Remove the core mold from the pre-cured carbon fiber rim, place the shaping rings on both sides of the rim, and then place it flat in the heat curing chamber for heat curing at a high temperature of 150-160℃ for 1.0-1.5 hours. Allow it to cool naturally to room temperature, remove the shaping rings, drill holes in the annular convex edge, grind and spray to obtain the carbon fiber rim. S5. The aluminum alloy forged disc is processed by milling machine, precision engraving machine, polishing and spraying to obtain the spoke disc; S6. Connect the spoke disc to the carbon fiber rim with bolts on the annular convex edge, perform dynamic balancing test, and obtain the carbon fiber hub.

2. The method for gradient molding carbon fiber wheel hubs according to claim 1, characterized in that, The split rim core mold consists of at least four segments.

3. The method for gradient molding carbon fiber wheel hubs according to claim 1, characterized in that, The carbon fiber prepreg is obtained by prepregding epoxy resin on carbon fiber twill weave or carbon fiber satin weave, with an epoxy resin content of 40-45% by mass.

4. The method for gradient molding carbon fiber wheel hub according to claim 3, characterized in that, The density of the carbon fiber twill weave or carbon fiber satin weave is 1.5–1.6 g / cm³. 3 .

5. The method for gradient molding carbon fiber wheel hubs according to claim 1, characterized in that, In step S1, when automatically laying up the carbon fiber prepreg, the layers are laid up sequentially at 0° / 45° / -45° / 90° of the prepreg winding direction.

6. The method for gradient molding of carbon fiber wheel hubs according to claim 1, characterized in that, The sliding coating material is prepared by liquid bisphenol F type epoxy resin, glass microspheres and curing agent in a mass ratio of 100:(4-6):(3-5).

7. The method for gradient molding of carbon fiber wheel hubs according to claim 6, characterized in that, The viscosity of the liquid bisphenol F type epoxy resin at 40°C is less than 2000 mPa·s; the glass microspheres are solid glass microspheres with a D50 particle size range of 10-30 μm; and the curing agent is a polyamide curing agent.

8. The method for gradient molding carbon fiber wheel hubs according to claim 1, characterized in that, The shaping ring can be made of metal or ceramic.

9. A carbon fiber wheel hub prepared by the method according to any one of claims 1 to 8.

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