Thermoplastic carbon fiber spokes and methods of making the same

Abstract

This invention relates to the field of bicycle component technology, and particularly to a thermoplastic carbon fiber spoke and its manufacturing method. The thermoplastic carbon fiber spoke includes a thermoplastic resin body and a plurality of carbon fibers coated by the thermoplastic resin body. The plurality of carbon fibers are bundled together and extend along a first axial direction. A plurality of gaps are formed between the plurality of carbon fibers, and each gap is filled by the thermoplastic resin body. The thermoplastic carbon fiber spoke extends along the first axial direction for a predetermined length, thereby forming two mutually spaced ends and a long segment between the two ends. The surface of each end is wound with carbon fibers coated by the thermoplastic resin to form an enlarged diameter portion. The thermoplastic carbon fiber spoke provided by this invention combines the performance of a spoke while enabling the recycling and reuse of carbon fiber and resin materials, thereby reducing manufacturing costs and improving material utilization.

Description

Technical Field

[0001] This invention relates to the field of bicycle component technology, and in particular to a thermoplastic carbon fiber spoke and its manufacturing method. Background Technology

[0002] In recent years, with the significant advantages of carbon fiber bicycles in terms of comfort and performance, more and more consumers are choosing this high-performance riding tool, leading to a sharp increase in the number of carbon fiber bicycles. The popularity of carbon fiber bicycles is partly due to the innovative design of their wheel spokes. This design typically includes a circular frame that provides a loop for the tire, with the hub located at the center of the frame. Each end of the spoke has a spoke joint for connecting the frame and the hub, ensuring the relative positioning of the frame and hub. This structure not only improves the stability and strength of the wheel but also optimizes the overall performance of the bicycle.

[0003] In the selection of spoke materials, carbon fiber composites have gradually replaced traditional metal materials and become the preferred choice for high-quality bicycle rims due to their high strength, lightweight, water resistance, and corrosion resistance. However, despite the excellent performance of carbon fiber composite spokes, they still face some challenges in practical applications. Carbon fiber composites are hard and brittle, and difficult to reshape after molding and curing, and the defect rate during processing and manufacturing remains high. Furthermore, the carbon fiber prepreg before pressing flat spokes requires manual rounding, which not only increases manufacturing costs but also makes the disposal of scrap a major problem. Although some spokes can be reused through secondary melting and processing, the effective separation of fibers and resin remains a significant challenge, limiting the scope of carbon fiber reuse and thus affecting the economic benefits of the industry.

[0004] Therefore, how to reduce manufacturing costs and improve material utilization while ensuring the performance of carbon fiber spokes is an urgent problem to be solved. Summary of the Invention

[0005] To address the problems in the prior art, the present invention provides a thermoplastic carbon fiber spoke and a method for manufacturing the same.

[0006] One of the objectives of this invention is to provide a thermoplastic carbon fiber spoke, which is installed between a wheel rim and a hub. The thermoplastic carbon fiber spoke includes a thermoplastic resin body and a plurality of carbon fibers covered by the thermoplastic resin body. The plurality of carbon fibers are bundled together and extend together along a first axial direction. A plurality of gaps are formed between the plurality of carbon fibers, and each gap is filled by the thermoplastic resin body.

[0007] The thermoplastic carbon fiber spokes extend a predetermined length along the first axial direction, thereby forming two ends that are far apart from each other and a long strip between the two ends;

[0008] Each of the end surfaces is wrapped with carbon fibers coated with thermoplastic resin to form an expanded diameter portion.

[0009] A second objective of this invention is to provide a method for manufacturing thermoplastic carbon fiber spokes, comprising the following steps:

[0010] Provide a quantity of carbon fiber;

[0011] Thermoplastic resin is attached to the outer surface of the carbon fibers, and after heat setting, it is wound up to obtain a prepreg tape.

[0012] The prepreg tape is hot-extruded and shaped into a carbon fiber rod, which is extended along the first axial direction to a predetermined length, thereby forming two ends that are far apart from each other and a long strip between the two ends.

[0013] The end surfaces of each end are formed by winding carbon fibers coated with thermoplastic resin to form an expanded diameter portion;

[0014] The diameter-expanding portion is pressed so that it forms a shape in which the outer diameter gradually increases from the long strip to the end;

[0015] Preferably, the diameter-expanding portion is formed in a shape where the outer diameter gradually increases from the long strip to the end.

[0016] In one embodiment, the thermoplastic resin is applied to the outer surface of the plurality of carbon fibers by coating or spraying, or by impregnating the plurality of carbon fibers with a flowable thermoplastic resin, so that the thermoplastic resin uniformly coats the outer surface of the plurality of carbon fibers.

[0017] In one embodiment, the thermoplastic resin is selected from any one of the following resins or mixtures thereof: nylon, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polycarbonate, polyurethane, polytetrafluoroethylene, polyethylene terephthalate, polyphenylene sulfide, polyetherketone ketone, polyetheretherketone or polyaryletherketone resins.

[0018] In one embodiment, the polyaryletherketone resin is selected from any one of the resins shown in the following structural formulas or a mixture thereof:

[0019] The structural formula of the resin shown in formula (1) is:

[0020]

[0021] The structural formula of the resin shown in formula (2) is:

[0022]

[0023] The structural formula of the resin shown in formula (3) is:

[0024]

[0025] In one embodiment, the carbon fiber is selected from any one of the following or a mixture thereof: T700 unidirectional carbon fiber or T800 unidirectional carbon fiber.

[0026] Preferably, the carbon fiber is a combination of T700 unidirectional carbon fiber and T800 unidirectional carbon fiber, and the mass ratio of T700 unidirectional carbon fiber to T800 unidirectional carbon fiber is (8-5):(5-2).

[0027] In one embodiment, the carbon fiber rod is hot-pressed before the expansion portion is formed to form a variable diameter carbon fiber rod of a predetermined specification.

[0028] In one embodiment, the resin content of the thermoplastic carbon fiber spokes is above 35% and below 60%.

[0029] In one embodiment, the temperature for hot extrusion setting is 200°C-300°C.

[0030] In one embodiment, the pressing includes cold pressing or hot pressing, wherein the temperature of cold pressing is 120°C-160°C and the temperature of hot pressing is 230°C-300°C.

[0031] Based on the above, compared with the prior art, the thermoplastic carbon fiber spokes provided by the present invention can achieve the recycling and reuse of carbon fiber and resin materials while possessing the performance of spokes, thereby reducing manufacturing costs and improving material utilization.

[0032] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other beneficial effects of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0034] Figure 1 An axial cross-sectional view of the thermoplastic carbon fiber spokes obtained according to a preferred embodiment of the present invention;

[0035] Figure 2 for Figure 1 An enlarged view of the cross section at A-A', showing the cross section of the thermoplastic resin body and carbon fiber along the vertical axial line.

[0036] Figure 3 This is a partial axial cross-sectional view of a carbon fiber spoke in the prior art;

[0037] Figure 4 and Figure 5 The process flow diagram for preparing thermoplastic carbon fiber spokes in Example 1 is shown.

[0038] Figure label:

[0039] 10. Thermoplastic resin body; 20. Carbon fiber; 30. End; 40. Long strip; 50. Expanded diameter section. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0042] Figure 1 An axial cross-sectional view of the thermoplastic carbon fiber spokes obtained according to a preferred embodiment of the present invention; Figure 2 for Figure 1 An enlarged view of the cross section at A-A', showing the cross-section of the thermoplastic resin body and carbon fiber along the vertical axial line.

[0043] Please refer to Figure 1 and Figure 2A preferred embodiment of the present invention provides a thermoplastic carbon fiber spoke, which is installed between a wheel rim and a hub. The thermoplastic carbon fiber spoke 1 includes a thermoplastic resin body 10 and a plurality of carbon fibers 20 covered by the thermoplastic resin body 10. The plurality of carbon fibers 20 are bundled together and extend straight along a first axis Y. A plurality of gaps are formed between the plurality of carbon fibers 20, and each gap is filled by the thermoplastic resin body 10.

[0044] The thermoplastic carbon fiber spokes extend straight along the first axial direction Y for a predetermined length, thereby forming two mutually spaced ends 30 and a long strip 40 between the two ends 30; each end 30 surface is wrapped with carbon fiber coated with thermoplastic resin to form an expanded diameter portion 50, the outer diameter expansion direction of these expanded diameter portions 50, as shown in Figures L2 and L3, is mutually spaced; optionally, the expansion of the outer diameter of the expanded diameter portion 50 can be a multi-gradient step-by-step expansion of the outer diameter, or it can be a continuous and gradual expansion of its outer diameter.

[0045] Please refer to Figure 3 The commonly used diameter expansion method in the prior art involves heating the end of the carbon fiber spoke to a softened state through heat treatment, followed by applying pressure along the same axial direction to the end, causing axial contraction and radial expansion of material flow to form the diameter expansion. This method causes the carbon fiber at the end to collapse, damaging the carbon fiber material and reducing its stability. However, this invention avoids the stability reduction caused by carbon fiber collapse by winding carbon fiber around the surface of the end 30 to form the diameter expansion 50.

[0046] Furthermore, in a preferred embodiment of the present invention, the thermoplastic carbon fiber spokes are made of, for example, T700 or T800 unidirectional carbon fiber. The fibers in unidirectional carbon fiber are mainly arranged along the same axial direction, a structure that makes its mechanical properties particularly outstanding in that direction. Therefore, unidirectional carbon fiber has extremely high tensile strength and stiffness in a specific direction (such as the axial direction), and can withstand a large amount of tensile force. In contrast, the diameter expansion method of the prior art disrupts the arrangement direction of the carbon fibers at the ends, which is detrimental to maintaining the performance of that portion of the carbon fiber.

[0047] Meanwhile, in the thermoplastic carbon fiber spokes made based on the above preferred embodiment, each of the expanded diameter portions 50 and the joint form a one-way stop with each other, thereby preventing each of the expanded diameter portions 50 from detaching from the corresponding joint through the corresponding end 30; and each of the corresponding joints is also unable to detach from the thermoplastic resin body 10 in a direction away from the long strip 40.

[0048] The present invention provides a method for manufacturing thermoplastic carbon fiber spokes according to a preferred embodiment, comprising the following steps:

[0049] Step 1: Provide a quantity of carbon fiber;

[0050] Preferably, the carbon fiber is selected from any one of the following or a mixture thereof: T700 unidirectional carbon fiber or T800 unidirectional carbon fiber. In unidirectional carbon fiber, the fibers are mainly aligned in one direction, a structure that makes its mechanical properties particularly outstanding in that direction. Therefore, unidirectional carbon fiber has extremely high tensile strength and stiffness in a specific direction (such as the axial direction), and can withstand a large amount of tensile force. In contrast, ordinary carbon fiber may have lower strength and stiffness in a specific direction due to the randomness or multidirectionality of fiber arrangement. Therefore, under the premise of meeting performance requirements, selecting unidirectional carbon fiber fabric can more effectively control costs and improve the economic efficiency of material use.

[0051] In some preferred embodiments, the carbon fiber is a combination of T700 unidirectional carbon fiber and T800 unidirectional carbon fiber, with a mass ratio of (8-5):(5-2). This mass ratio can be, for example, 8:2, 7.5:2.5, 7:3, 6.5, 3.5, 6:4, 5.5:4.5, 5:5, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. More preferably, the mass ratio of T700 unidirectional carbon fiber to T800 unidirectional carbon fiber is (7.5-6.5):(3.5-2.5). For example, when the mass ratio is 7.5:2.5 or 6.5:3.5, their performance can achieve the effect of using 100% T800 unidirectional carbon fiber, thus achieving low cost and high performance.

[0052] Step 2: Attach thermoplastic resin to the outer surface of the carbon fibers, heat-set and then wind them up to obtain a prepreg tape;

[0053] In some preferred embodiments, the thermoplastic resin is selected from any one of the following resins or mixtures thereof: nylon, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polycarbonate, polyurethane, polytetrafluoroethylene, polyethylene terephthalate, polyphenylene sulfide, polyetherketone ketone, polyetheretherketone, or polyaryletherketone resins; more preferably, the polyaryletherketone resin is selected from any one of the following resins shown in the following structural formulas or mixtures thereof:

[0054] The structural formula of the resin shown in formula (1) is:

[0055]

[0056] The structural formula of the resin shown in formula (2) is:

[0057]

[0058] The structural formula of the resin shown in formula (3) is:

[0059]

[0060] Using polyaryletherketone resins such as ST-PEKKS and ST-PEKK, it has radiation resistance, corrosion resistance, salt and alkali resistance, high and low temperature resistance, and can significantly improve the toughness and tensile strength of the product.

[0061] In some preferred embodiments, the thermoplastic resin may be applied to the outer surface of the plurality of carbon fibers by coating or spraying, or the plurality of carbon fibers may be immersed in a flowable thermoplastic resin by impregnation, so that the thermoplastic resin uniformly coats the outer surface of the plurality of carbon fibers; more preferably, the carbon fibers are immersed in a flowable resin by spreading the yarn.

[0062] In an embodiment of the present invention, thermoplastic resin (e.g., ST-PEKKS, ST-PEKK) is prepared into a fluid colloid and placed in a special glue tank. T700 / T800 unidirectional carbon fiber is introduced into the glue tank through yarn spreading and impregnated with it. After heat setting, it is then wound into a prepreg tape.

[0063] In some preferred embodiments, the resin content (rubber content) of the thermoplastic carbon fiber spokes is above 35% and below 60%. This rubber content is achieved by adjusting the dynamic viscosity of the rubber and the wetting time. Those skilled in the art can adjust it in a conventional way, which will not be elaborated on here.

[0064] The formula for calculating the adhesive content is as follows:

[0065]

[0066] In some preferred embodiments, in step (2), the heat setting temperature is 210-310°C.

[0067] Step 3: The prepreg tape is hot-extruded and shaped into a carbon fiber rod, which is extended along the first axial direction to a predetermined length, thereby forming two ends that are far apart from each other and a long strip between the two ends; in some preferred embodiments, the hot extrusion temperature is 200℃-300℃.

[0068] In an embodiment of the present invention, the prepreg tape is pultruded into carbon fiber rods by hot extrusion shaping through a pultrusion device and the heating temperature is controlled between 200°C and 300°C.

[0069] Step 4: Hot-press the carbon fiber rod to form a variable diameter carbon fiber rod of a preset specification;

[0070] In an embodiment of the present invention, carbon fiber rods are cut to the required size and placed in a special mold. They are then heated to 200°C-300°C and hot-pressed to produce variable-diameter carbon fiber rods of different specifications. In addition, the variable-diameter carbon fiber rods formed after hot pressing can also be presented in other forms, such as tapered carbon fiber rods, irregular cross-section carbon fiber rods, etc. It should be noted that the "required size" mentioned here refers to the length of the carbon fiber rod. For example, when the carbon fiber rod is made into spokes, the size can be between 240mm and 300mm to meet the needs of different wheel rims.

[0071] Step 5: An expanded diameter portion is formed by winding carbon fibers coated with thermoplastic resin onto the surface of each end.

[0072] In embodiments of the present invention, the two ends of the variable-diameter carbon fiber rod are thickened by winding with T700 / T800 carbon fibers coated with thermoplastic resin. In some preferred embodiments, the carbon fibers coated with thermoplastic resin are wound around the end surfaces, and the entire assembly is rotated in the same direction to form a tapered shape from the inside out on the end surfaces.

[0073] Step 6: Press the expanded diameter portion to form a shape in which the outer diameter gradually increases from the long strip to the end.

[0074] In an embodiment of the present invention, after the two ends of the variable-diameter carbon fiber rod are expanded, it can be pressed again to form a certain taper in the expanded portion, thereby better matching the metal cap and improving the bonding force between the variable-diameter carbon fiber rod and the nut. The pressing includes cold pressing or hot pressing, wherein the temperature of cold pressing is 120℃-160℃, and the temperature of hot pressing is 230℃-300℃.

[0075] This invention uses carbon fiber to thicken both ends of the spokes and increases the tensile strength of the metal parts bonded to the variable diameter carbon fiber rod body by pressing. This step does not cause secondary damage to the variable diameter carbon fiber rod body, thereby greatly improving the product qualification rate.

[0076] The following examples and comparative examples are provided to illustrate the invention in more detail, but are not intended to limit the invention in any way. Furthermore, unless otherwise specified, the raw materials used may be commercially available products conventional in the art, or may be prepared by conventional methods in the art.

[0077] Example 1

[0078] Please refer to Figure 4 and Figure 5This embodiment provides a high-temperature thermoplastic prepreg production process, including the following steps:

[0079] Step 1: The spindle-loaded fibers are placed on the yarn rack. After being released and combed, the carbon fibers are arranged in parallel and driven into the spreading unit by the first traction roller. Spreading can be done in various ways, including multi-roller spreading, vibration spreading, and ultrasonic spreading. In the spreading unit, the carbon fibers are evenly spread into a uniformly distributed unidirectional belt. A tension detection device is installed at the outlet of the first traction roller to realize closed-loop automatic tension control. It should be noted that the first traction roller cooperates with the subsequent second traction roller to provide process transmission for the entire line. The diameter of the first traction roller is 200mm-800mm.

[0080] Step 2: After passing through the first traction roller and the yarn spreading unit, the carbon fiber enters the impregnation unit. The impregnation unit is filled with pre-prepared ST-Pekks adhesive (the resin content in the adhesive is 35% by mass percentage). When the carbon fiber passes through the impregnation unit, it is fully impregnated with the resin in the adhesive. After the front and back sides are impregnated, the adhesive thickness is controlled by rolling the pressure roller to obtain the prepreg blank.

[0081] Step 3: The prepreg blank is passed through the traction roller into the drying oven (drying oven temperature 80℃) for heat setting and then wound up to obtain the prepreg tape. The drying oven is equipped with a solvent removal device, which includes a fan and a filter box. The air inlet of the fan is connected to a recovery pipe that extends to the top of the drying oven. A condenser converter is installed in the pipe. The gaseous solvent is condensed into liquid after passing through the converter and is recovered. The air outlet of the fan is connected to a conveying pipe that extends through to the inside of the filter box. The inside of the filter box is connected to an air supply pipe that extends through to the outside of the filter box and to the top of the drying oven. A filter screen with a mesh size of 150 mesh is installed inside the air supply pipe.

[0082] Step 4: The prepreg tape enters the first mold through the positioning mold. The temperature of the first mold is set to 300℃. After the prepreg tape is softened and extruded into a preform, it enters the second mold. The temperature of the second mold is set to 150℃. After the preform is shaped, it is sent to the cutting position through the traction line and cut to obtain the preform.

[0083] Step 5: After cutting the preform into 294mm lengths, place it into the mold cavity, heat it to 300℃, start the press to press it, and turn off the heating device to allow the mold temperature to drop to 130℃. Then open the mold to obtain the flat spoke product.

[0084] Step 6: First, fit the metal connectors at both ends into place. Then, wrap the two ends with T700 continuous carbon fiber coated with thermoplastic resin, press and shape them so that the two ends form two cylinders respectively. After grinding the cylinders into a trapezoidal shape, pull the metal connectors back into place.

[0085] Example 2

[0086] Please refer to Figure 4 and Figure 5 This embodiment provides a high-temperature thermoplastic prepreg production process, including the following steps:

[0087] Step 1: The spindle-loaded fibers are placed on the yarn rack. After being released and combed, the carbon fibers are arranged in parallel and driven into the spreading unit by the first traction roller. Spreading can be done in various ways, including multi-roller spreading, vibration spreading, and ultrasonic spreading. In the spreading unit, the carbon fibers are evenly spread into a uniformly distributed unidirectional belt. A tension detection device is installed at the outlet of the first traction roller to realize closed-loop automatic tension control. It should be noted that the first traction roller cooperates with the subsequent second traction roller to provide process transmission for the entire line. The diameter of the first traction roller is 200mm-800mm.

[0088] Step 2: After passing through the first traction roller and the yarn spreading unit, the carbon fiber enters the impregnation unit. The impregnation unit is filled with a pre-prepared ST-Pekk suspension (the resin content in the solution is 40% by mass percentage). When the carbon fiber passes through the impregnation unit, it is fully impregnated with the resin in the solution. After the front and back sides are impregnated, the glue thickness is controlled by rolling the pressure roller to obtain the prepreg blank.

[0089] Step 3: The prepreg blank is passed through the traction roller into the drying oven (drying oven temperature 150℃) for heat setting and then wound up to obtain the prepreg tape. The drying oven is equipped with a solvent removal device, which includes a fan and a filter box. The air inlet of the fan is connected to a recovery pipe that extends to the top of the drying oven. A condenser converter is installed in the pipe. The gaseous solvent is condensed into liquid after passing through the converter and is recovered. The air outlet of the fan is connected to a conveying pipe that extends through to the inside of the filter box. The inside of the filter box is connected to an air supply pipe that extends through to the outside of the filter box and to the top of the drying oven. A filter screen with a mesh size of 150 mesh is installed inside the air supply pipe.

[0090] Step 4: The prepreg tape enters the first mold through the positioning mold. The temperature of the first mold is set to 400℃. After the prepreg tape is softened and extruded into a preform, it enters the second mold. The temperature of the second mold is set to 150℃. After the preform is shaped, it is sent to the cutting position through the traction line and cut to obtain the preform.

[0091] Step 5: After cutting the preform into 294mm lengths, place it into the mold cavity, heat it to 300℃, start the press to press it, and turn off the heating device to allow the mold temperature to drop to 130℃. Then open the mold to obtain the flat spoke product.

[0092] Step 6: First, fit the metal connectors at both ends into place. Then, wrap the two ends with T700 continuous carbon fiber coated with thermoplastic resin, press and shape them so that the two ends form two cylinders respectively. After grinding the cylinders into a trapezoidal shape, pull the metal connectors back into place.

[0093] Example 3

[0094] Please refer to Figure 4 and Figure 5 This embodiment provides a high-temperature thermoplastic prepreg production process, including the following steps:

[0095] Step 1: The spindle-loaded fibers are placed on the yarn rack. After being released and combed, the carbon fibers are arranged in parallel and driven into the spreading unit by the first traction roller. Spreading can be done in various ways, including multi-roller spreading, vibration spreading, and ultrasonic spreading. In the spreading unit, the carbon fibers are evenly spread into a uniformly distributed unidirectional belt. A tension detection device is installed at the outlet of the first traction roller to realize closed-loop automatic tension control. It should be noted that the first traction roller cooperates with the subsequent second traction roller to provide process transmission for the entire line. The diameter of the first traction roller is 200mm-800mm.

[0096] Step 2: After passing through the first traction roller and the yarn spreading unit, the carbon fiber enters the impregnation unit. A pre-prepared PA suspension (40% resin content by mass percentage) is added to the impregnation unit. The carbon fiber is fully impregnated with the resin in the adhesive as it passes through the impregnation unit. After the front and back sides are impregnated, the adhesive thickness is controlled by rolling the pressure roller to obtain the prepreg blank.

[0097] Step 3: The prepreg blank is passed through the traction roller into the drying oven (drying oven temperature 150℃) for heat setting and then wound up to obtain the prepreg tape. The drying oven is equipped with a solvent removal device, which includes a fan and a filter box. The air inlet of the fan is connected to a recovery pipe that extends to the top of the drying oven. A condenser converter is installed in the pipe. The gaseous solvent is condensed into liquid after passing through the converter and is recovered. The air outlet of the fan is connected to a conveying pipe that extends through to the inside of the filter box. The inside of the filter box is connected to an air supply pipe that extends through to the outside of the filter box and to the top of the drying oven. A filter screen with a mesh size of 150 mesh is installed inside the air supply pipe.

[0098] Step 4: The prepreg tape enters the first mold through the positioning mold. The temperature of the first mold is set to 350℃. After the prepreg tape is softened and extruded into a preform, it enters the second mold. The temperature of the second mold is set to 150℃. After the preform is shaped, it is sent to the cutting position through the traction line and cut to obtain the preform.

[0099] Step 5: After cutting the preform into 294mm lengths, place it into the mold cavity, heat it to 300℃, start the press to press it, and turn off the heating device to allow the mold temperature to drop to 130℃. Then open the mold to obtain the flat spoke product.

[0100] Step 6: First, fit the metal connectors at both ends into place. Then, wrap the two ends with T700 continuous carbon fiber coated with thermoplastic resin, press and shape them so that the two ends form two cylinders respectively. After grinding the cylinders into a trapezoidal shape, pull the metal connectors back into place.

[0101] Comparative Example 1

[0102] The only difference between this comparative example and Example 1 is that the resin used is epoxy resin.

[0103] Comparative Example 2

[0104] The difference between this comparative example and Example 1 is only in the method of forming the expanded diameter section: the mold temperature is set to 300°C to heat the end of the carbon fiber spoke to a softened state, and then a pressure is applied to the end along the same axial direction to cause the material flow to generate axial contraction and radial expansion at the end to form the expanded diameter section.

[0105] Comparative Example 3

[0106] The only difference between this comparative example and Example 1 is the method of forming the expanded diameter section: a unidirectional carbon fiber tube with an inner diameter the same as the diameter of the spoke cylinder is fixed to both ends of the spoke by heating and then polished into a trapezoidal shape.

[0107] Test case

[0108] The two ends of the sample are clamped with fixtures and stretched bidirectionally using a universal testing machine until the sample breaks to obtain the maximum force at the time of fracture. The universal testing machine is a microcomputer-controlled electronic universal testing machine of model XBD5205 from Shanghai Xinbiao Testing Instruments Manufacturing Co., Ltd.

[0109] The preforms and flat spokes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to maximum force tests according to the above methods. The test results are shown in Table 1 and Table 2, respectively.

[0110] Table 1 Comparison of Pultrusion Molding Data for Different Resin-Based Carbon Fibers

[0111] stage Material Maximum force / N Example 1 Precast rods PEKKS+ Carbon Fiber T700 7218N Example 2 Precast rods PEKK+ Carbon Fiber T700 7444N Example 3 Precast rods PA+ Carbon Fiber T700 6246N Comparative Example 1 Precast rods Epoxy resin + carbon fiber T700 6572N

[0112] Table 2 Comparison of tensile strength of flat spokes with different resin bases and carbon fiber.

[0113] stage Material Maximum force / N Example 1 flat spokes PEKKS+ Carbon Fiber T700 6956N Example 2 flat spokes PEKK+ Carbon Fiber T700 7636N Example 3 flat spokes PA+ Carbon Fiber T700 5526N Comparative Example 1 flat spokes Epoxy + Carbon Fiber T700 6030N

[0114] It can be seen that the production of thermoplastic carbon fiber preforms combines prepreg and pultrusion processes, reducing the prepreg heating and prepreg steps, which greatly reduces production costs. The resin content has a wide range, between 35% and 60%, and is uniform and adjustable to meet the needs of different applications. It has good mechanical properties, especially high toughness and strong impact resistance. All properties are superior to thermosetting resins. The production efficiency is high, and the molding time is between 3 and 30 minutes.

[0115] More importantly, thermoplastic resins do not have a cross-linking and curing reaction process, so the molding process mainly involves heating, pressurizing, and cooling. Compared with thermosetting resins, they are more suitable for mass production and do not require post-curing. They have good flame retardancy, are environmentally friendly, and can be reshaped after heating. They are more environmentally friendly than thermosetting resins, are easy to recycle, and do not require degradation. Continuous fiber reinforced thermoplastic composites can be recycled and reused as short fiber reinforced composites after being crushed. They have a long storage period and can be stored for a long time without special means. They have low water absorption and excellent resistance to damp heat.

[0116] The present invention also provides a method for recycling and reusing thermoplastic carbon fiber spokes, comprising the following steps:

[0117] (1) Separation of thermoplastic resin and carbon fiber

[0118] Step 1: Collect the failed thermoplastic carbon fiber spokes;

[0119] Step 2: Cut the collected spokes to the required length and place them in a sealed container containing a solution of dimethylformamide (DMF) for extraction. Since thermoplastic resin has a certain solubility in DMF solution, this is based on intermolecular interaction forces, such as van der Waals forces and hydrogen bonds. When thermoplastic resin comes into contact with DMF solution, these interaction forces cause the resin molecules to gradually separate from the carbon fiber surface and dissolve in the solution.

[0120] In some preferred embodiments, the weight ratio of dimethylformamide to solvent in the dimethylformamide solution is 1:1 to 1:5. This weight ratio can be, for example, 1:1, 1:2, 1:3, 1:4, 1:5, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. More preferably, the weight ratio of dimethylformamide to solvent in the dimethylformamide solution is 1:3.

[0121] In some other embodiments, the solvent used for extraction may be one or any combination of two or more of dichloromethane, dichloroethane, chloroform, and pyrrolidone.

[0122] Step 3: After the carbon fiber softens, separate the DMF from the carbon fiber and add new DMF for a second extraction. Repeat this step several times. After ensuring that the resin is completely separated from the carbon fiber, wash with deionized water three times to obtain the carbon fiber.

[0123] It should be noted that the softening of carbon fiber can be observed with the naked eye. This is because the spokes made by combining carbon fiber and thermoplastic resin in this invention are solid. When the spokes are immersed in dimethylformamide solution, the thermoplastic resin covering the gaps on the surface of the carbon fiber will be gradually extracted into the solution. Therefore, the carbon fiber will appear loose, which is to say, it will appear to be "softened".

[0124] (2) Reuse of carbon fiber

[0125] After drying the carbon fibers obtained in (1), they were mixed with other resins and then produced into short carbon fiber particles using a granulator.

[0126] (3) Reuse of resin

[0127] The solution containing thermoplastic resin and DMF obtained in (2) was filtered to obtain a clean solution. After a second purification and extraction, the thermoplastic resin and DMF were separated. After washing and drying, the resin was obtained.

[0128] Compared with existing technologies, the carbon fiber spokes provided by this invention can achieve non-destructive separation of resin and fiber using a solvent method. The resulting resin solution is then treated through filtration, purification, precipitation, and washing processes to reduce it to high-purity resin. Furthermore, the recycled carbon fiber can be melt-granulated with different thermoplastic resins (PP, PPS, PA, PAEK, etc.) to prepare thermoplastic carbon fiber short fiber particles. This achieves the recyclability of carbon fiber spokes and reduces their carbon emissions.

[0129] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0130] Although this document frequently uses terms such as thermoplastic resin body, carbon fiber, end, long segment, and expanded diameter section, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention. The terms "first," "second," etc. (if present) in the specification, claims, and accompanying drawings of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thermoplastic carbon fiber spoke, mounted between a wheel rim and a hub, characterized in that, The thermoplastic carbon fiber spokes include a thermoplastic resin body and a plurality of carbon fibers covered by the thermoplastic resin body. The plurality of carbon fibers are bundled together and extend together along a first axial direction. A plurality of gaps are formed between the plurality of carbon fibers, and each gap is filled by the thermoplastic resin body. The thermoplastic carbon fiber spokes extend a predetermined length along the first axial direction, thereby forming two ends that are far apart from each other and a long strip between the two ends; Each of the end surfaces is wrapped with carbon fibers coated with thermoplastic resin to form an expanded diameter portion.

2. A method for manufacturing thermoplastic carbon fiber spokes, characterized in that, Includes the following steps: Provide a quantity of carbon fiber; Thermoplastic resin is attached to the outer surface of the carbon fibers, and after heat setting, it is wound up to obtain a prepreg tape. The prepreg tape is hot-extruded and shaped into a carbon fiber rod, which is extended along the first axial direction to a predetermined length, thereby forming two ends that are far apart from each other and a long strip between the two ends. The end surfaces of each end are formed by winding carbon fibers coated with thermoplastic resin to form an expanded diameter portion; The diameter-expanding portion is pressed so that it forms a shape in which the outer diameter gradually increases from the long strip to the end; Preferably, the diameter-expanding portion is formed in a shape where the outer diameter gradually increases from the long strip to the end.

3. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, The thermoplastic resin is applied to the outer surface of the carbon fibers by coating or spraying, or by impregnating the carbon fibers with a flowable thermoplastic resin, so that the thermoplastic resin uniformly coats the outer surface of the carbon fibers.

4. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, The thermoplastic resin is selected from any one of the following resins or mixtures thereof: nylon, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polycarbonate, polyurethane, polytetrafluoroethylene, polyethylene terephthalate, polyphenylene sulfide, polyetherketone ketone, polyetheretherketone or polyaryletherketone resins.

5. The method for manufacturing thermoplastic carbon fiber spokes according to claim 4, characterized in that, The polyaryletherketone resin is selected from any one of the resins shown in the following structural formulas or a mixture thereof: The structural formula of the resin shown in formula (1) is: The structural formula of the resin shown in formula (2) is: The structural formula of the resin shown in formula (3) is:

6. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, The carbon fiber is selected from any one of the following or a mixture thereof: T700 unidirectional carbon fiber or T800 unidirectional carbon fiber. Preferably, the carbon fiber is a combination of T700 unidirectional carbon fiber and T800 unidirectional carbon fiber, and the mass ratio of T700 unidirectional carbon fiber to T800 unidirectional carbon fiber is (8-5):(5-2).

7. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, Before forming the expanded diameter section, the carbon fiber rod is hot-pressed to form a variable diameter carbon fiber rod of a predetermined specification.

8. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, The resin content of the thermoplastic carbon fiber spokes is above 35% and below 60%.

9. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, The temperature for hot extrusion setting is 200℃-300℃.

10. The method for manufacturing thermoplastic carbon fiber spokes according to claim 2, characterized in that, The pressing includes cold pressing or hot pressing, wherein the temperature of cold pressing is 120℃-160℃ and the temperature of hot pressing is 230℃-300℃.

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