A process for the forming manufacture of a carbon fibre bicycle crankset

Abstract

The application relates to a forming manufacturing process of a carbon fiber bicycle crankset, and relates to the technical field of carbon fiber processing. The forming manufacturing process adopts a low-melting-point alloy to pour an inner mold of a crank, wraps an inner layer carbon fiber cloth outside the inner mold, sets a carbon fiber mesh cylinder outside the inner layer carbon fiber cloth, and winds carbon fiber cloth strips outside the carbon fiber mesh cylinder; the inner mold with the wound carbon fiber material is placed in an outer mold for extrusion and vacuumizing; a hole is formed in the inner side of a connecting hole of a pedal connecting head part rotating shaft, the inner mold with the wound carbon fiber material and the carbon fiber material are placed in the outer mold, the inner mold is melted after being heated, the outer mold is rotated, the melted inner mold flows out from the hole of the lower end of the spline connecting head part by centrifugal force, a preliminarily solidified crank is left, and the crank is continuously heated until the crank is completely solidified; and the solidified crank is taken out from the outer mold. The application has the effect of improving the stability of the structure.

Description

Technical Field

[0001] This application relates to the field of molding technology for carbon fiber bicycle cranksets, and in particular to a molding and manufacturing process for carbon fiber bicycle cranksets. Background Technology

[0002] Cycling is a sport loved by many. With the development of technology, carbon fiber is often used to manufacture bicycle structures to facilitate transportation and reduce the weight of bicycles. The crank structure includes the handlebars, the spline joint head that is mounted on the handlebars and connected to the axle, and the pedal mounting head that is mounted on the handlebars for mounting the pedals. If the crank is made into a solid structure, a large amount of carbon fiber is required, which increases the production cost. If it is made into a hollow structure, the pedal mounting head and spline joint head are not firmly connected to the handlebars. Summary of the Invention

[0003] The purpose of this application is to provide a molding and manufacturing process for carbon fiber bicycle cranksets to solve the technical problems of "if the crank is manufactured as a solid structure, a large amount of carbon fiber is required, which increases the production cost; if it is manufactured as a hollow structure, the connection between the pedal mounting head and the spline connection head and the crank body is not strong enough".

[0004] The molding and manufacturing process for a carbon fiber bicycle crankset provided in this application adopts the following technical solution: A molding and manufacturing process for a carbon fiber bicycle crankset includes...

[0005] S1. Inner mold fabrication: The mold is made by casting, using a low-melting-point bismuth-tin based alloy.

[0006] Cast into an inner mold for the crank, and after the inner mold cools, spray a release agent onto the surface of the inner mold.

[0007] S2. Carbon fiber laying: Wrap the inner layer of carbon fiber cloth around the outside of the inner mold, and put the middle layer of carbon fiber mesh on the outside of the inner layer of carbon fiber cloth. Wrap the outer layer of carbon fiber cloth strips around the outside of the middle layer of carbon fiber mesh. The inner layer of carbon fiber cloth, the middle layer of carbon fiber mesh, and the outer layer of carbon fiber cloth strips are connected to the spline connection head and the pedal connection head, respectively.

[0008] S3. Carbon fiber compaction: The inner mold with the wrapped carbon fiber material and the carbon fiber material are placed together in the outer mold for compression, while a vacuum is drawn at the same time;

[0009] S4. Carbon fiber opening: After the carbon fiber material is compacted, the mold is opened. A cutting knife is used to open a hole at the lower end of the spline connector head and to open a hole inside the pedal shaft hole of the pedal connector head. The opening at the lower end of the spline connector head is used to discharge the molten inner mold, and the opening inside the pedal shaft hole of the pedal connector head is used to balance the air pressure.

[0010] S5. Inner mold separation: Place the inner mold with the carbon fiber material wound on it and the carbon fiber material together in the outer mold with the spline connection head facing outward. Heat the carbon fiber material to solidify it and melt the inner mold at the same time. Rotate the outer mold and use centrifugal force to make the melted inner mold flow out from the opening at the lower end of the spline connection head, leaving the initially solidified crank. Continue heating until the crank is completely solidified.

[0011] S6. Crank finishing: Remove the cured crank from the outer mold, polish the edges, and then color it to obtain the desired crank.

[0012] Optionally, S2. Carbon fiber laying includes the following steps: S2.1, inner layer carbon fiber cloth wrapping, a whole piece of pre-impregnated carbon fiber cloth is cut according to the shape of the crank and wrapped around the outside of the inner mold of the crank, the pre-impregnated carbon fiber cloth is cut into pre-impregnated carbon fiber strips to form an Ω shape and attached to both sides of the spline connection head and pedal connection head, the two ends of the whole piece of pre-impregnated carbon fiber cloth are pressed tightly to the two ends of the pre-impregnated carbon fiber strips, and then the pre-impregnated carbon fiber cloth is cut into an "O" shape according to the size of the spline connection head and pedal connection head and attached to the front and back of the spline connection head and pedal connection head, and finally the pre-impregnated carbon fiber strips are formed into an O-shaped structure and fitted into the inside of the spline shaft hole and pedal shaft hole;

[0013] S2.2, Reinforcing rib laying: Carbon fiber cloth is made into carbon fiber strips, and the carbon fiber strips are laid around the inner mold at intervals to form external reinforcing ribs. The carbon fiber strips are made into rings and installed in the spline shaft hole and pedal shaft hole.

[0014] S2.3, Prepreg middle layer carbon fiber mesh tube laying: Cut the two ends of the prepreg middle layer carbon fiber mesh tube from the middle, the cut is a T-shaped structure, and it is divided into two equal mesh structures. The mesh tube part is fitted into the inner mold crank section, and the mesh structure is wrapped around the spline connection head and the pedal connection head in sequence, and overlaps with each other.

[0015] S2.4, Winding pre-impregnated carbon fiber cloth; Cut the pre-impregnated carbon fiber cloth into carbon fiber strips, and start winding the carbon fiber strips from the position where the spline connection head connects to the crank part. First, wind the carbon fiber strips twice around the crank part and the spline connection head, then wind them around the spline connection head once, and then wind them around the crank part again. After the crank part is finished, wind the carbon fiber strips around the pedal connection head. After the pedal connection head is wound once, wind it around the crank part again in the reverse direction.

[0016] Optionally, in step S2.3, after the pre-impregnated middle layer carbon fiber mesh is laid, multiple carbon fiber rods are arrayed and pasted inside the spline hole of the spline connection head, and multiple carbon fiber rods are arrayed and installed inside the pedal mounting hole of the pedal connection head before step S2.4, the pre-impregnated carbon fiber cloth is wrapped around the outside of the carbon fiber rods.

[0017] Optionally, S3, carbon fiber compaction, includes the following steps:

[0018] S3.1, Apply release agent to the inside of the outer mold;

[0019] S3.2, Mold placement: The inner mold with the carbon fiber material wound is placed in the outer mold in a ring array structure, wherein the spline connecting head points to the outer edge of the outer mold, and the winding pedal connecting head points to the center of the outer mold;

[0020] S3.3, Mold Closure Stamping: The outer mold is closed, and after the mold is closed, the outer mold forms a sealed structure. Through stamping and vacuuming, the carbon fiber layer wrapped on the inner mold is tightly compacted, and the internal air of the carbon fiber material is discharged.

[0021] Optionally, S5. Inner mold separation:

[0022] S5.1, Carbon fiber structure maintenance: The carbon fiber layer wound on the inner mold is punched and then the mold is closed again, and vacuum is drawn again to maintain the stability of the carbon fiber layer structure.

[0023] S5.2, Carbon fiber curing: By heating the mold, the internal temperature of the outer mold is increased. After a period of heat treatment, the carbon fiber layer is completely cured. At the same time, the alloy structure changes from solid to liquid. The inner mold generates a supporting force on the inside of the carbon fiber layer under the action of thermal expansion, and the outer mold generates a compressive force from the outside of the carbon fiber layer, making the carbon fiber layer structure more stable.

[0024] S5.3, Inner mold discharge: Continue to maintain the internal temperature of the outer mold, allowing gas to enter the outer mold, rotate the outer mold, and use centrifugal force to discharge the molten inner mold from the crank.

[0025] Optionally, S6. Crank modification includes the following steps:

[0026] S6.1, Hole repair: Insert a locking component into the opening at the lower end of the spline connection head and bond it with AB glue. The locking component is used to install the locking bolt and fix the crank to the spline shaft.

[0027] The opening inside the pivot hole of the pedal connection head is sealed with an embedded metal sheet and AB glue to prevent dust from entering the crank back plate.

[0028] S6.2, External painting: Apply lacquer to the outside of the crankshaft, draw patterns with the lacquer, and polish it. Polishing is done by gradually increasing the grit from 400 grit sandpaper to 3000 grit sandpaper, and finally polishing.

[0029] Optionally, the locking assembly includes an upper sleeve fitting and a lower sleeve fitting. The upper sleeve fitting includes an upper limit ring with an external threaded tube installed on it. The external threaded tube has an internal thread on its inner side. The lower sleeve fitting includes a lower limit member and an internal threaded tube disposed on the lower limit member. The internal threaded tube and the external threaded tube cooperate with each other, and a bolt is threadedly connected to the internal thread on the inner side of the external threaded tube.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. A low-melting-point bismuth-tin-based alloy (melting point range: 70-150℃, eutectic bismuth-tin alloy melting point approximately 138℃ is used as the inner mold) is adopted to facilitate the winding of carbon fiber. After winding is completed and solidified by mold compression, the inner mold is melted by heating and discharged from the inside of the carbon fiber crank, thereby ensuring the stability of the structure after carbon fiber molding. The parts where the pedal connecting head 3 and spline connecting head 2 are connected to the handle body 1 have sufficient support during the carbon fiber winding process. The carbon fiber material is distributed as an integral structure, thereby improving the stability of the structure.

[0032] The inner mold is wrapped with carbon fiber cloth, which serves as a gap detector for the overall structure. A release agent is brushed onto the outside of the inner mold to effectively reduce the amount of material entering the crankshaft after the inner mold melts. A middle layer of carbon fiber mesh is fitted outside the inner carbon fiber cloth, which provides oblique tensile force. Carbon fiber strips are wrapped around the outside of the middle layer of carbon fiber mesh to improve the fit between the middle layer of carbon fiber mesh and the inner mold. At the same time, it strengthens the stability of the connection structure between the pedal connection head and the spline connection head and the crankshaft, thereby improving the overall structural stability of the crankshaft after molding.

[0033] 3. Place the inner mold with the carbon fiber material wound on it and the carbon fiber material together in the outer mold, and compress them. At the same time, vacuum is drawn to initially shape the crank and expel the gas in the gaps of the carbon fiber during the winding process in a negative pressure environment to prevent the formation of bubbles during the heating and curing process.

[0034] 4. The carbon fiber has openings to facilitate timely discharge after the inner mold melts. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the crank structure according to an embodiment of this application;

[0036] Figure 2 This is a schematic diagram of the overall process structure of an embodiment of this application;

[0037] Figure 3 This is a schematic diagram of the carbon fiber laying process in an embodiment of this application;

[0038] Figure 4This is a schematic diagram of the carbon fiber compaction process structure according to an embodiment of this application;

[0039] Figure 5 This is a schematic diagram of the mold separation process structure in an embodiment of this application;

[0040] Figure 6 This is a schematic diagram of the locking component structure according to an embodiment of this application.

[0041] Figure label:

[0042] 1. Crank section; 2. Spline connection head; 21. Spline shaft hole; 3. Pedal connection head; 31. Pedal shaft hole; 4. Locking assembly; 41. Upper sleeve fitting; 42. Lower sleeve fitting; 43. Upper limit ring; 44. External threaded tube; 45. Lower limit fitting; 46. Internal threaded tube. Detailed Implementation

[0043] The following is in conjunction with the appendix Figure 1 - Appendix Figure 6 This application will be described in further detail below.

[0044] Reference Figure 1 A molding and manufacturing process for a carbon fiber bicycle crankset, S1. Inner mold making: The inner mold of the crankset is made by casting using a low melting point alloy (bismuth-tin based alloy: melting point range: 70-150℃ (eutectic bismuth-tin alloy melting point is about 138℃). After the inner mold cools, a release agent (polydimethylsiloxane (PDMS) release agent) is sprayed on the surface of the inner mold. The use of the release agent can make the inner mold quickly separate from the carbon fiber layer after melting and reduce residue.

[0045] S2. Carbon fiber laying: The inner layer of carbon fiber cloth is wrapped around the outside of the inner mold. The carbon fiber cloth is an integral structure and is wrapped around the inner diaphragm of the crank. By pressing, the carbon fiber cloth is made to fit with the inner mold, which can reduce the gaps in the innermost carbon fiber layer and effectively prevent the inner mold from melting and remaining in the gaps.

[0046] A middle layer of carbon fiber mesh is sleeved on the outside of the inner layer of carbon fiber cloth, and carbon fiber strips are wound around the outside of the middle layer of carbon fiber mesh. The inner layer of carbon fiber cloth, the middle layer of carbon fiber mesh, and the outer layer of carbon fiber strips are respectively connected to the spline connecting head 2 and the pedal connecting head 3. The middle layer of carbon fiber mesh has a mesh structure, which is easy to deform and can better fit the inner mold. This makes the spline connecting head 2 and the pedal connecting head 3 connected to the crank part 1 an integral structure. At the same time, it is cured into a crisscross structure, which can better improve the support force and enhance the overall strength of the crank.

[0047] An outer layer of carbon fiber cloth strips is wrapped around the outside of the middle layer of carbon fiber mesh; the outer layer of carbon fiber cloth strips make the middle layer of carbon fiber mesh and the inner layer of carbon fiber cloth fit more tightly, making the crank structure more stable.

[0048] S3. Carbon fiber compaction: The inner mold with the wound carbon fiber material and the carbon fiber material are placed together in the outer mold and compressed while a vacuum is drawn. The mutual compression between the outer mold and the inner mold shapes the crank and increases the tightness between the carbon fiber cloth, the middle carbon fiber mesh, and the outer layer of wrapped carbon fiber strips, thereby enhancing the stability of the overall structure. By drawing a vacuum, the gas inside the carbon fiber layer is discharged, reducing the gaps between the carbon fiber layers and enhancing the stability of the crank structure after curing.

[0049] S4. Carbon Fiber Opening: After the carbon fiber material is compacted, the mold is opened. A cutting tool is used to open a hole at the lower end of the spline connection head 2. The opening penetrates the carbon fiber layer, which facilitates the discharge of the inner mold after melting under centrifugal force. At the same time, the locking component 4 can be installed to facilitate the fixed connection of the spline shaft to the crank with bolts. An opening is made inside the pedal shaft hole 31 to facilitate the entry of gas, so that the internal air pressure can be quickly balanced during the discharge of the inner mold, reducing the residue of the inner mold. At the same time, when the pedal is installed, the opening inside the pedal shaft hole 31 can be covered without affecting the external shape of the crank. The opening at the lower end of the spline connection head 2 is used to discharge the molten inner mold, and the opening inside the pedal shaft hole 31 is used to balance the air pressure.

[0050] S5. Inner mold separation: Place the inner mold with the carbon fiber material wound on it and the carbon fiber material together in the outer mold, with the spline connection head 2 facing outward. After heating, the carbon fiber material is solidified and the inner mold is melted at the same time. Rotate the outer mold and use centrifugal force to make the melted inner mold flow out from the opening at the lower end of the spline connection head 2, leaving the initially solidified crank. Continue heating until the crank is completely solidified.

[0051] S6. Crank finishing: Remove the cured crank from the outer mold, polish the edges, and then color it to obtain the desired crank.

[0052] Reference Figure 2The S2. carbon fiber laying includes the following steps: S2.1, inner layer carbon fiber cloth wrapping: a whole piece of pre-impregnated carbon fiber cloth is cut according to the shape of the crank and wrapped around the outside of the inner mold of the crank, so that the innermost carbon fiber cloth is a whole structure, reducing the gaps at the joints of the carbon fiber cloth, which can reduce the residue after the inner mold melts; the pre-impregnated carbon fiber cloth is cut into pre-impregnated carbon fiber strips to form an Ω shape and attached to both sides of the spline connection head 2 and pedal connection head 3, which can enhance the stability of the carbon fiber layer structure attached to the spline connection head 2 and pedal connection head 3, and at the same time strengthen the connection between the carbon fiber layer structure of the spline connection head 2 and pedal connection head 3 and the carbon fiber layer structure of the crank part 1; thereby enhancing the overall structural strength of the crank; the two ends of the whole piece of pre-impregnated carbon fiber cloth are pressed tightly to the two ends of the pre-impregnated carbon fiber strips, and then the pre-impregnated carbon fiber cloth is placed on the inner mold. The carbon fiber cloth is cut into an "O" shape according to the size of the spline connector head 2 and the pedal connector head 3, and is attached to the front and back of the spline connector head 2 and the pedal connector head 3. In the "O" shape, the "+" structure is attached to and wrapped around the crank part 1 and pressed tightly on the outside of the pre-impregnated carbon fiber strip. The "mouth" part is aligned with the spline shaft hole 21 and the pedal shaft hole 31, thereby further enhancing the connection strength between the carbon fiber layer structure of the spline connector head 2 and the pedal connector head 3 and the carbon fiber layer structure of the crank part 1. Finally, the pre-impregnated carbon fiber strip is formed into an O-shaped structure and fitted inside the spline shaft hole 21 and the pedal shaft hole 31. The O-shaped structure, the "O" shaped carbon fiber sheet and the Ω-shaped carbon fiber strip form a cavity structure, which is wrapped around the outside of the inner carbon fiber cloth, enhancing the overall stability of the spline connector head 2 and the pedal connector head 3.

[0053] S2.2, Reinforcing Rib Laying: The carbon fiber cloth is made into carbon fiber strips. First, the carbon fiber cloth is cut into strips, then the strips are rolled into a cylinder, and then pressed to form a solid carbon fiber strip. The carbon fiber strips are laid around the inner mold at intervals to form external reinforcing ribs, which strengthen the carbon fiber layer from the outside, thereby making the structure of the spline connection head 2, pedal connection head 3, and crank part more stable.

[0054] The carbon fiber strips are made into a ring shape and installed in the spline shaft hole 21 and the pedal shaft hole 31 to increase the thickness of the inner wall of the spline shaft hole 21 and the pedal shaft hole 31, making the structure more stable after the spline shaft and the pedal shaft are installed.

[0055] S2.3, Pre-impregnated intermediate carbon fiber mesh tube laying: Cut both ends of the pre-impregnated intermediate carbon fiber mesh tube in the middle, with the cut forming a T-shaped structure, dividing it into two equal mesh sections. The mesh tube section is fitted onto the inner mold crank section, and the mesh sections are sequentially wrapped around the spline connection head 2 and the pedal connection head 3, overlapping each other. Through the pre-impregnated intermediate carbon fiber mesh tube, the carbon fiber layer has an oblique tensile force after formation, thereby giving the hardened crank greater stability.

[0056] The pre-impregnated middle layer carbon fiber mesh tube forms a cylindrical and mesh structure that is interconnected, thereby further enhancing the structural strength between the spline connection head 2 and the pedal connection head 3 and the crank part 1.

[0057] S2.4, Winding pre-impregnated carbon fiber cloth; Cut the pre-impregnated carbon fiber cloth into carbon fiber strips, and start winding the outer layer of carbon fiber cloth strips from the position where the spline connection head 2 connects to the crank part 1. First, wind it twice around the crank part 1 and the spline connection head 2, then wind it around the spline connection head 2 once, and then wind it around the crank part 1 again. After the crank part 1 is finished being wound, wind it around the pedal connection head 3. After the pedal connection head 3 is wound once, wind it again in the reverse direction around the crank part 1. The winding of the outer layer of carbon fiber cloth strips further strengthens the structural strength between the spline connection head 2 and the crank part 1 and between the pedal connection head 3 and the crank part 1, and at the same time increases the tightness of the carbon fiber layer stacking.

[0058] S2.3 After the pre-impregnated middle layer carbon fiber mesh is laid, multiple carbon fiber rods are arrayed and pasted inside the spline hole of the spline connection head 2, and multiple carbon fiber rods are arrayed and installed inside the pedal mounting hole of the pedal connection head 3. Then, S2.4 is performed, where pre-impregnated carbon fiber cloth is wrapped around the outside of the carbon fiber rods. Multiple carbon fiber rods can enhance the thickness of the carbon fiber layer inside the spline shaft connection hole and the pedal shaft connection hole, so that the crank can have a stronger connection force with the spline shaft and the pedal shaft. At the same time, during the extrusion process, the carbon fiber rods can form protrusions, which can enhance the stability of the connection between the crank and the spline shaft after being connected with the spline shaft or crank shaft.

[0059] Reference Figure 1 , Figure 3 S3, carbon fiber compaction, includes the following steps:

[0060] S3.1, Apply release agent to the inside of the outer mold; this facilitates rapid separation of the carbon fiber layer from the outer mold.

[0061] S3.2, Mold Placement: The inner mold with the carbon fiber material wound is placed in the outer mold in a ring array structure, wherein the spline connecting head 2 points to the outer edge of the outer mold, and the winding pedal connecting head 3 points to the center of the outer mold; this facilitates the demolding of the molten inner mold from the carbon fiber layer after heating by centrifugal force.

[0062] S3.3, Mold Closure Stamping: The outer mold is closed, and after the mold is closed, the outer mold forms a sealed structure. Through stamping and vacuuming, the carbon fiber layer wrapped on the inner mold is tightly compressed and the internal air of the carbon fiber material is discharged to enhance the tightness of the carbon fiber layer adhesion.

[0063] Reference Figure 1 , Figure 4 S5. Inner mold separation:

[0064] S5.1, Carbon fiber structure maintenance: The carbon fiber layer wound on the inner mold is punched and then the mold is closed again, and vacuum is drawn again to maintain the stability of the carbon fiber layer structure.

[0065] S5.2, Carbon Fiber Curing: By heating the mold, the internal temperature of the outer mold is increased. After a period of heat treatment, the carbon fiber layer is completely cured. At the same time, the alloy structure changes from solid to liquid. The inner mold generates a supporting force on the inside of the carbon fiber layer under the action of thermal expansion, and the outer mold generates a compressive force from the outside of the carbon fiber layer. The principle of thermal expansion and contraction is used to further compact the carbon fiber layer, making the carbon fiber layer structure more stable. After the temperature rises, the inner mold melts. At this time, the carbon fiber layer has been initially cured, which can prevent the carbon fiber layer from cracking due to excessive pressure caused by thermal expansion and contraction.

[0066] S5.3, Inner mold discharge: Continue to maintain the internal temperature of the outer mold and fill the outer mold with gas, allowing the gas to enter the outer mold. Rotate the outer mold and use centrifugal force to discharge the molten inner mold from the crank.

[0067] The S6. crank modification includes the following steps:

[0068] S6.1, Hole repair: Insert locking component 4 into the lower opening of spline connection head 2 and bond it with AB glue. Locking component 4 is used to install locking bolts to fix the crank to the spline shaft. The lower opening of spline connection head 2 can be filled by locking component 4, and the crank to spline can be fixed by screws installed by locking component 4.

[0069] The opening inside the 3-axis connecting hole of the pedal connection head is sealed with an embedded metal sheet and AB glue to prevent dust from entering the crank back plate.

[0070] S6.2, External painting: Apply lacquer to the outside of the crank, draw patterns with the lacquer, and polish it. The polishing is done by gradually increasing the grit sandpaper from 400 grit to 3000 grit sandpaper, and finally polishing. Applying lacquer and polishing it makes the crank hydrophobic, which makes it easy to clean the dust generated on the crank.

[0071] Reference Figure 6The locking assembly 4 includes an upper sleeve 41 and a lower sleeve 42. The upper sleeve 41 includes an upper limit ring 43, on which an externally threaded pipe 44 is mounted. The externally threaded pipe 44 has an internal thread on its inner side. The lower sleeve 42 includes a lower limit member 45 and an internally threaded pipe 46 disposed on the lower limit member 45. The internally threaded pipe 46 and the externally threaded pipe 44 cooperate with each other, and a bolt is threadedly connected to the internal thread on the inner side of the externally threaded pipe 44. During the installation of the locking assembly 4, the upper sleeve 41 and the lower sleeve 42... AB glue is applied to the outside of the sleeve fitting 42. After the external threaded pipe 44 and the internal threaded pipe 46 are threaded together, a tension force is generated, which locks the upper sleeve fitting 41 and the lower sleeve fitting 42 onto the spline connection head 2, and at the same time seals the hole opened in the spline connection head 2. The bolt is threaded to the internal thread on the inside of the external threaded pipe 44 and abuts against the spline shaft, thereby locking the spline shaft and the spline connection head 2. After locking the locking assembly 4, the end of the locking assembly 4 is ground so that the end of the locking assembly 4 is flush with the edge of the spline connection head 2.

[0072] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A process for the profiled manufacture of a carbon fibre bicycle crankset, characterised in that, comprising S1. Inner mold making: using pouring method, pouring low melting point alloy into crank inner mold, after the inner mold cooling, spraying release agent on the surface of the inner mold; the melting point range of low melting point alloy: 75-150℃; S2. Carbon fiber laying: wrapping inner layer carbon fiber cloth outside the inner mold, setting middle layer carbon fiber mesh tube outside the inner layer carbon fiber cloth, winding outer layer carbon fiber cloth strip outside the middle layer carbon fiber mesh tube; the inner layer carbon fiber cloth, the middle layer carbon fiber mesh tube and the outer layer carbon fiber cloth strip are connected with the spline connecting head (2) and the pedal connecting head (3) respectively; S3. Carbon fiber compaction: placing the inner mold and carbon fiber material wrapped with carbon fiber material together in the outer mold, extruding and vacuumizing at the same time; S4. Carbon fiber opening: after the carbon fiber material is compacted, the mold is opened, the cutting knife is used to open the hole at the lower end of the spline connecting head (2) and the hole inside the pedal shaft hole (31) of the pedal connecting head (3), the hole at the lower end of the spline connecting head (2) is used to discharge the melted inner mold, and the hole inside the pedal shaft hole (31) of the pedal connecting head (3) is used to balance the air pressure; S5. Inner mold separation: placing the inner mold and carbon fiber material wrapped with carbon fiber material together in the outer mold, the spline connecting head (2) is outward, after heating, the carbon fiber material is solidified and the inner mold is melted, rotating the outer mold, using the centrifugal force to make the melted inner mold flow out from the hole at the lower end of the spline connecting head (2), leaving the preliminary solidified crank, and continuing to heat until the crank is completely solidified; S6. Crank modification: taking out the solidified crank from the outer mold, polishing the edge, and after polishing, coloring to obtain the required crank; The carbon fiber laying comprises the following steps: S2.1, inner layer carbon fiber cloth wrapping, cutting a whole piece of pre-impregnated carbon fiber cloth according to the shape of the crank, wrapping it outside the crank inner mold, cutting the pre-impregnated carbon fiber cloth into pre-impregnated carbon fiber strips, forming an Ω shape, and fitting on both sides of the spline connecting head (2) and the pedal connecting head (3), pressing the two ends of the whole piece of pre-impregnated carbon fiber cloth on the two ends of the pre-impregnated carbon fiber strips, then cutting the pre-impregnated carbon fiber cloth into a "ancient" shape according to the size of the spline connecting head (2) and the pedal connecting head (3), and fitting on the front and back of the spline connecting head (2) and the pedal connecting head (3), and finally forming an O-shaped structure of the pre-impregnated carbon fiber strips and fitting inside the spline connecting head (2) and the pedal connecting head; S2.2, reinforcement laying: making the carbon fiber cloth into carbon fiber strips, laying the carbon fiber strips around the inner mold at intervals to form external reinforcement, and making the carbon fiber strips into a circular ring shape and installing them in the spline shaft hole (21) and the pedal shaft hole (31); S2.3, pre-impregnated middle layer carbon fiber mesh tube laying: cutting the two ends of the pre-impregnated middle layer carbon fiber mesh tube from the middle, cutting the opening into a T-shaped structure, dividing the mesh structure into two sections, the mesh tube part is sleeved on the crank section of the inner mold, and the mesh structure is wrapped around the spline connecting head (2) and the pedal connecting head (3) in turn and overlaps each other; S2.4, winding the prepreg carbon fiber cloth; the prepreg carbon fiber cloth is cut into outer carbon fiber cloth strips, which are wound from the position where the spline connecting head (2) and the crank (1) are connected, first winding two turns on the crank (1) and the spline connecting head (2), then winding one turn around the spline connecting head (2) and then winding the crank (1), after winding the crank (1), winding the pedal connecting head (3), after winding one turn on the pedal connecting head (3), winding the crank (1) in the reverse direction again.

2. A process for the forming manufacture of a carbon fibre bicycle crankset according to claim 1, characterised in that, After the S2.3, the prepreg middle layer carbon fiber mesh cylinder laying is completed, a plurality of carbon fiber rods are arrayed and pasted in the spline hole of the spline connecting head (2), and after a plurality of carbon fiber rods are arrayed and installed in the pedal mounting hole of the pedal connecting head (3), S2.4, winding the prepreg carbon fiber cloth, is performed, and the prepreg carbon fiber cloth is wound outside the carbon fiber rods.

3. A process for the forming manufacture of a carbon fibre bicycle crankset according to claim 2, characterised in that, The S3, carbon fiber compaction, comprises the following steps: S3.1, brushing a release agent on the inner side of the outer mold; S3.2, mold placement: the inner mold with wound carbon fiber material is placed in the outer mold in an annular array structure, wherein the spline connecting head (2) points to the outer edge of the outer mold, and the pedal connecting head (3) points to the center of the outer mold; S3.3, mold closing and stamping: the outer mold is closed, and after closing, the outer mold forms a sealed structure, and by stamping and vacuumizing, the carbon fiber layer wound on the inner mold is tightly compacted, and the internal air of the carbon fiber material is discharged.

4. A process for the forming manufacture of a carbon fibre bicycle crankset according to claim 3, characterised in that, The S5. inner mold separation: S5.1, carbon fiber structure maintenance: after the carbon fiber layer wound on the inner mold is punched, the mold is closed again, and vacuumized again to maintain the stability of the carbon fiber layer structure; S5.2, carbon fiber curing: by heating the mold, the temperature inside the outer mold is increased, and after a period of heating treatment, the carbon fiber layer is completely cured, and at the same time, the alloy structure changes from solid to liquid, the inner mold generates supporting force to the inside of the carbon fiber layer under the action of thermal expansion, and the outer mold generates extrusion force from the outside of the carbon fiber layer, making the carbon fiber layer structure more stable; S5.3, inner mold discharge: continue to maintain the temperature inside the outer mold, make the gas enter the inside of the outer mold, rotate the outer mold, and discharge the melted inner mold from the crank by centrifugal force.

5. A process for the forming manufacture of a carbon fibre bicycle crankset according to claim 4, characterised in that, The S6. crank modification, comprises the following steps: S6.1, hole repair, insert the locking assembly (4) into the hole at the lower end of the spline connecting head (2) and bond with AB glue, the locking assembly (4) is used for installing locking bolts to fixedly connect the crank and the spline shaft; The opening inside the pedal shaft hole (31) is sealed by embedding a metal sheet and using AB glue, which is used to prevent dust from entering the crank back plate; S6.2, external painting, brushing lacquer on the outside of the crank, drawing patterns by lacquer, and polishing treatment.

6. A process for the forming manufacture of a carbon fibre bicycle crankset according to claim 5, characterised in that, The locking assembly (4) comprises an upper sleeve member (41), a lower sleeve member (42), the upper sleeve member (41) comprises an upper limiting ring (43), an outer threaded pipe (44) is installed on the upper limiting ring (43), an inner thread is formed in the inner side of the outer threaded pipe (44), the lower sleeve member (42) comprises a lower limiting member (45), an inner threaded pipe (46) is arranged on the lower limiting member (45), the inner threaded pipe (46) is matched with the outer threaded pipe (44), and a bolt is threadedly connected with the inner thread in the inner side of the outer threaded pipe (44).

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