Carbon fiber bicycle front fork with high fatigue resistance and preparation method thereof

Abstract

The invention belongs to the technical field of bicycle composite materials, and discloses a preparation method of a carbon fiber bicycle front fork with high fatigue resistance. The front fork is prepared from the following raw materials in parts by weight: 60-70 parts of carbon fibers, 10-20 parts of basalt fibers, 20-40 parts of resin, 5-8 parts of a toughening agent, 1-3 parts of nanosheets, 0.5-2 parts of carbon nanotubes, 1-3 parts of silicon carbide whiskers, 0.5-2 parts of a silane coupling agent and 5-10 parts of a curing agent. The components are reasonably proportioned, and the flexibilizer is uniformly dispersed in the material and can absorb energy and prevent crack propagation, so that the anti-fatigue performance of the material is improved; the nanosheet structure is bridged with the fiber and the resin, so that the interfacial shear strength is improved; silicon carbide whiskers are inserted into crack tips to generate a bridging effect, and crack propagation is hindered. The raw materials are in close contact with the carbon fibers to form a compact cross-linked structure and reduce the internal stress, so that the interface bonding strength and the overall fatigue resistance of the composite material are jointly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of bicycle composite materials, and more particularly relates to a method for preparing a carbon fiber bicycle front fork with high fatigue resistance. Background Art

[0002] Bicycles are a common means of transportation, and the industry's focus has always been on producing lightweight, strong, and rigid bicycles. Traditional bicycles are typically made of steel or aluminum alloy tubes welded and riveted together. However, steel tubes are prone to rust, while aluminum alloys are relatively rigid and offer limited comfort.

[0003] Carbon fiber bicycles are a new type of bicycle that has developed and emerged in recent years. They use carbon fiber composite materials as the bicycle frame, front fork or wheel set. The characteristics of carbon fiber materials are light weight, good rigidity and good impact absorption. Due to the low density of carbon fiber, bicycles made of carbon fiber materials are lighter and have very good mechanical properties. However, traditional carbon fiber front forks are prone to problems such as matrix cracking and fiber-resin interface debonding under long-term alternating stress, resulting in a significant decrease in fatigue life. Due to defects in the manufacturing process, uneven resin infiltration and the presence of bubbles or gaps inside the material are prone to occur, further exacerbating the risk. At the same time, although carbon fiber has high strength and high modulus carbon fiber can improve rigidity, its lateral impact resistance is poor and it is prone to brittle fracture when impacted. In the existing technology, the effect of a single toughening or reinforcing component is limited and cannot synergistically improve the performance of the front fork.

[0004] Therefore, how to provide a carbon fiber bicycle front fork with high fatigue resistance and a preparation method thereof is a problem that those skilled in the art urgently need to solve. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, the present invention provides a carbon fiber bicycle front fork with high fatigue resistance and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A carbon fiber bicycle front fork with high fatigue resistance comprises the following raw materials, measured by weight: 60-70 parts of carbon fiber, 10-20 parts of basalt fiber, 20-40 parts of resin, 5-8 parts of toughening agent, 1-3 parts of nanosheets, 0.5-2 parts of carbon nanotubes, 1-3 parts of silicon carbide whiskers, 0.5-2 parts of silane coupling agent, and 5-10 parts of curing agent.

[0007] Preferably, the resin is selected from one or more of epoxy resin and vinyl resin.

[0008] Preferably, the toughening agent is selected from one or more of carboxyl-terminated nitrile rubber, liquid nitrile rubber, and thermoplastic polyurethane.

[0009] Preferably, the nanosheets are selected from one or more of graphene nanosheets, graphene oxide nanosheets, and boron nitride nanosheets.

[0010] Preferably, the silane coupling agent is selected from one or more of KH-550, KH-560, and KH-792.

[0011] Preferably, the curing agent is selected from one of methyl ethyl ketone peroxide, tert-butyl perbenzoate, maleic anhydride, phthalic anhydride, and m-phenylenediamine.

[0012] The present invention also provides a method for preparing the above-mentioned carbon fiber bicycle front fork with high fatigue resistance, comprising the following steps: (1) Prepare an ethanol solution containing 5% silane coupling agent, immerse the carbon fiber in it, ultrasonically treat it at 60°C for 20 minutes, and then dry it at 80°C for 2 hours to form carbon fiber with amino active groups on the surface; (2) adding the nanosheets to ethanol and ultrasonically peeling for 2 h to obtain a suspension, impregnating the carbon fibers treated in step (1) in the suspension, and then drying at room temperature for later use; (3) Add the resin and toughening agent into the resin tank at 80°C and stir at low speed, then add basalt fiber, carbon nanotubes, silicon carbide whiskers and curing agent in sequence, heat to 100°C and stir at high speed to obtain a mixture; (4) hot-melt impregnating the carbon fibers treated in step (2) into the mixture, passing through a preheating roller, passing through a resin tank, compacting with a roller to remove air bubbles, and curing with a cooling roller to form a prepreg; (5) The prepreg is laid on the mold so that the prepreg fits tightly to the mold. The mold is then placed in a hot pressing machine for hot pressing. The mold is then cooled to room temperature and post-processed to obtain a bicycle front fork.

[0013] Preferably, the low-speed stirring rate in step (3) is 500-600 rpm for 0.5-1 h, and the high-speed stirring rate is 1800-2000 rpm for 1-2 h.

[0014] Preferably, in step (4), the temperature of the preheating roller is 80° C., the temperature of the resin tank is 130-140° C., and the pulling speed is 10-15 m / min.

[0015] Preferably, the pressure of the hot pressing molding in step (5) is 15-18 MPa and the time is 2-4 hours.

[0016] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a carbon fiber bicycle front fork with high fatigue resistance and a preparation method thereof, which has the following beneficial effects: (1) The proportions of the components in the present invention are reasonable. Carbon fiber serves as the main load-bearing structure, providing high strength and modulus. A small amount of basalt fiber is used to reduce costs and improve the corrosion resistance of the material. The resin bonds the fiber and transfers the load. The toughening agent is evenly dispersed in the material. When the material is subjected to fatigue load, it can absorb energy and prevent the expansion of cracks, thereby improving the fatigue resistance of the material. The nanosheet structure bridges the fiber and the resin, improving the interface shear strength, and has high thermal conductivity, accelerating heat dissipation during fatigue and avoiding local overheating. Silicon carbide whiskers are inserted into the crack tip to produce a bridging effect, hindering crack expansion. The raw materials are in close contact with the carbon fiber, forming a dense cross-linked structure and reducing internal stress, which together improve the interface bonding strength and overall fatigue resistance of the composite material. (2) The present invention pre-treats carbon fibers, whereby a silane coupling agent forms a chemical bonding layer on the carbon fiber surface. Graphene nanosheets are adsorbed on the fiber surface through a π-π conjugation effect. The two synergistically enhance the interfacial shear strength and reduce interfacial debonding during load transfer. The prepared composite material can be used not only to make front forks but also in various bicycle components. (3) The present invention adopts hot melt impregnation and molding process, which can be quickly formed, reduces the preparation cost, and is suitable for industrial continuous production. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0018] Example 1. A carbon fiber bicycle front fork with high fatigue resistance comprises the following raw materials, in parts by weight: 60 parts of carbon fiber, 10 parts of basalt fiber, 20 parts of epoxy resin, 5 parts of carboxyl-terminated nitrile rubber, 1 part of graphene oxide nanosheets, 0.5 parts of carbon nanotubes, 1 part of silicon carbide whiskers, 0.5 parts of silane coupling agent KH-792, and 5 parts of methyl ethyl ketone peroxide.

[0019] A method for preparing a carbon fiber bicycle front fork with high fatigue resistance comprises the following steps: (1) Prepare an ethanol solution containing 5% silane coupling agent KH-792, immerse the carbon fiber in it, ultrasonically treat it at 60°C for 20 minutes, and then dry it at 80°C for 2 hours to form carbon fiber with amino active groups on the surface; (2) adding graphene oxide nanosheets to ethanol and ultrasonically peeling for 2 h to obtain a suspension, impregnating the carbon fibers treated in step (1) in the suspension, and then drying at room temperature for later use; (3) Add epoxy resin and carboxyl-terminated nitrile rubber into a resin tank at 80°C and stir at a low speed. Then, add basalt fiber, carbon nanotubes, silicon carbide whiskers, and methyl ethyl ketone peroxide in sequence, raise the temperature to 100°C, and stir at a high speed to obtain a mixture. (4) hot-melt impregnating the carbon fibers treated in step (2) into the mixture, passing through a preheating roller, passing through a resin tank, compacting with a roller to remove air bubbles, and curing with a cooling roller to form a prepreg; (5) The prepreg is laid on the mold so that the prepreg fits tightly to the mold. The mold is then placed in a hot pressing machine for hot pressing. The mold is then cooled to room temperature and post-processed to obtain a bicycle front fork.

[0020] The low-speed stirring rate in step (3) is 500 rpm for 0.5 h, and the high-speed stirring rate is 1800 rpm for 1 h.

[0021] In step (4), the temperature of the preheating roller is 80° C., the temperature of the resin tank is 130° C., and the pulling speed is 10 m / min.

[0022] The pressure of the hot pressing molding in step (5) is 15 MPa and the time is 2 hours.

[0023] Example 2: A carbon fiber bicycle front fork with high fatigue resistance comprises the following raw materials, in parts by weight: 70 parts of carbon fiber, 20 parts of basalt fiber, 40 parts of epoxy resin, 8 parts of carboxyl-terminated nitrile rubber, 3 parts of graphene oxide nanosheets, 2 parts of carbon nanotubes, 3 parts of silicon carbide whiskers, 22 parts of silane coupling agent KH-79, and 10 parts of methyl ethyl ketone peroxide.

[0024] A method for preparing a carbon fiber bicycle front fork with high fatigue resistance comprises the following steps: (1) Prepare an ethanol solution containing 5% silane coupling agent KH-792, immerse the carbon fiber in it, ultrasonically treat it at 60°C for 20 minutes, and then dry it at 80°C for 2 hours to form carbon fiber with amino active groups on the surface; (2) adding graphene oxide nanosheets to ethanol and ultrasonically peeling for 2 h to obtain a suspension, impregnating the carbon fibers treated in step (1) in the suspension, and then drying at room temperature for later use; (3) Add epoxy resin and carboxyl-terminated nitrile rubber into a resin tank at 80°C and stir at a low speed. Then, add basalt fiber, carbon nanotubes, silicon carbide whiskers, and methyl ethyl ketone peroxide in sequence, raise the temperature to 100°C, and stir at a high speed to obtain a mixture. (4) hot-melt impregnating the carbon fibers treated in step (2) into the mixture, passing through a preheating roller, passing through a resin tank, compacting with a roller to remove air bubbles, and curing with a cooling roller to form a prepreg; (5) The prepreg is laid on the mold so that the prepreg fits tightly to the mold. The mold is then placed in a hot pressing machine for hot pressing. The mold is then cooled to room temperature and post-processed to obtain a bicycle front fork.

[0025] The low-speed stirring rate in step (3) is 500 rpm for 0.5 h, and the high-speed stirring rate is 1800 rpm for 1 h.

[0026] In step (4), the temperature of the preheating roller is 80° C., the temperature of the resin tank is 130° C., and the pulling speed is 10 m / min.

[0027] The pressure of the hot pressing molding in step (5) is 15 MPa and the time is 2 hours.

[0028] Example 3: A carbon fiber bicycle front fork with high fatigue resistance comprises the following raw materials, in parts by weight: 65 parts of carbon fiber, 15 parts of basalt fiber, 30 parts of epoxy resin, 6 parts of carboxyl-terminated nitrile rubber, 2 parts of graphene oxide nanosheets, 1 part of carbon nanotubes, 2 parts of silicon carbide whiskers, 1 part of silane coupling agent KH-792, and 8 parts of methyl ethyl ketone peroxide.

[0029] A method for preparing a carbon fiber bicycle front fork with high fatigue resistance comprises the following steps: (1) Prepare an ethanol solution containing 5% silane coupling agent KH-792, immerse the carbon fiber in it, ultrasonically treat it at 60°C for 20 minutes, and then dry it at 80°C for 2 hours to form carbon fiber with amino active groups on the surface; (2) adding graphene oxide nanosheets to ethanol and ultrasonically peeling for 2 h to obtain a suspension, impregnating the carbon fibers treated in step (1) in the suspension, and then drying at room temperature for later use; (3) Add epoxy resin and carboxyl-terminated nitrile rubber into a resin tank at 80°C and stir at a low speed. Then, add basalt fiber, carbon nanotubes, silicon carbide whiskers, and methyl ethyl ketone peroxide in sequence, raise the temperature to 100°C, and stir at a high speed to obtain a mixture. (4) hot-melt impregnating the carbon fibers treated in step (2) into the mixture, passing through a preheating roller, passing through a resin tank, compacting with a roller to remove air bubbles, and curing with a cooling roller to form a prepreg; (5) The prepreg is laid on the mold so that the prepreg fits tightly to the mold. The mold is then placed in a hot pressing machine for hot pressing. The mold is then cooled to room temperature and post-processed to obtain a bicycle front fork.

[0030] The low-speed stirring rate in step (3) is 500 rpm for 0.5 h, and the high-speed stirring rate is 1800 rpm for 1 h.

[0031] In step (4), the temperature of the preheating roller is 80° C., the temperature of the resin tank is 130° C., and the pulling speed is 10 m / min.

[0032] The pressure of the hot pressing molding in step (5) is 15 MPa and the time is 2 hours.

[0033] Comparative Example 1 The difference from Example 3 is that step (2) is omitted and graphene oxide nanosheets are not added. The rest is the same as in Example 3. A front fork is obtained.

[0034] Comparative Example 2 The difference from Example 3 is that no carboxyl-terminated nitrile rubber is added, and the rest is the same. A front fork is obtained.

[0035] Performance testing Refer to GB / T 3565.6-2022 Bicycle Safety Requirements Part 6: Frame and Front Fork Test Methods.

[0036] A bending fatigue test was performed on the front fork. According to the standard for racing bicycles, the force applied to the load-bearing device was 620N. During the test, the peak-to-peak displacement at the point of force application was checked to see if it exceeded 20% of the initial value. If so, the test was terminated. After 100,000 cycles, the test was stopped and the specimen was carefully inspected for fracture. If fracture was detected, the test was terminated. The results are shown in Table 1.

[0037] Table 1 2. If the specimen does not exceed the displacement limit and does not break after 100,000 cycles, a rearward impact test is performed. The drop height of the hammer is 640 mm, as per racing bicycle standards. The results are shown in Table 2.

[0038] Table 2 In summary, the raw material ratios of the present invention jointly improve the interface bonding strength and overall fatigue resistance of the composite material.

[0039] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the solutions disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method section.

[0040] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A carbon fiber bicycle front fork with high fatigue resistance, characterized in that: The raw materials include the following by weight: 60-70 parts of carbon fiber, 10-20 parts of basalt fiber, 20-40 parts of resin, 5-8 parts of toughening agent, 1-3 parts of nanosheets, 0.5-2 parts of carbon nanotubes, 1-3 parts of silicon carbide whiskers, 0.5-2 parts of silane coupling agent and 5-10 parts of curing agent.

2. The carbon fiber bicycle front fork with high fatigue resistance according to claim 1, characterized in that: The resin is selected from one or more of epoxy resin and vinyl resin.

3. The carbon fiber bicycle front fork with high fatigue resistance according to claim 1, characterized in that: The toughening agent is selected from one or more of carboxyl-terminated nitrile rubber, liquid nitrile rubber, and thermoplastic polyurethane.

4. The carbon fiber bicycle front fork with high fatigue resistance according to claim 1, characterized in that: The nanosheets are selected from one or more of graphene nanosheets, graphene oxide nanosheets, and boron nitride nanosheets.

5. The carbon fiber bicycle front fork with high fatigue resistance according to claim 1, characterized in that: The silane coupling agent is selected from one or more of KH-550, KH-560, and KH-792.

6. The carbon fiber bicycle front fork with high fatigue resistance according to claim 1, characterized in that: The curing agent is selected from one of methyl ethyl ketone peroxide, tert-butyl perbenzoate, maleic anhydride, phthalic anhydride and m-phenylenediamine.

7. The method for preparing a carbon fiber bicycle front fork with high fatigue resistance according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Prepare an ethanol solution containing 5% silane coupling agent, immerse the carbon fiber in it, ultrasonically treat it at 60°C for 20 minutes, and then dry it at 80°C for 2 hours to form carbon fiber with amino active groups on the surface; (2) adding the nanosheets to ethanol and ultrasonically peeling for 2 h to obtain a suspension, impregnating the carbon fibers treated in step (1) in the suspension, and then drying at room temperature for later use; (3) Add the resin and toughening agent into the resin tank at 80°C and stir at low speed, then add basalt fiber, carbon nanotubes, silicon carbide whiskers and curing agent in sequence, heat to 100°C and stir at high speed to obtain a mixture; (4) hot-melt impregnating the carbon fibers treated in step (2) into the mixture, passing through a preheating roller, passing through a resin tank, compacting with a roller to remove air bubbles, and curing with a cooling roller to form a prepreg; (5) The prepreg is laid on the mold so that the prepreg fits tightly to the mold. The mold is then placed in a hot pressing machine for hot pressing. The mold is then cooled to room temperature and post-processed to obtain a bicycle front fork.

8. The method for preparing a carbon fiber bicycle front fork with high fatigue resistance according to claim 7, characterized in that: The low-speed stirring rate in step (3) is 500-600 rpm, and the time is 0.5-1 h. The high-speed stirring rate is 1800-2000 rpm, and the time is 1-2 h.

9. The method for preparing a carbon fiber bicycle front fork with high fatigue resistance according to claim 7, characterized in that: In step (4), the temperature of the preheating roller is 80° C., the temperature of the resin tank is 130-140° C., and the pulling speed is 10-15 m / min.

10. The method for preparing a carbon fiber bicycle front fork with high fatigue resistance according to claim 7, characterized in that: The pressure of the hot pressing molding in step (5) is 15-18 MPa and the time is 2-4 hours.

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