A fiber-reinforced composite material traction seat and its preparation method and mold

Abstract

The present invention discloses a fiber reinforced composite traction seat and a preparation method and mold thereof. The mold of the fiber reinforced composite traction seat includes a first mold, a second mold and a third mold. The first mold includes a platform and an arc-shaped protrusion arranged on the upper surface of the platform, the second mold includes a first recessed portion and a first right angle portion, and the third mold includes a second recessed portion and a first right angle portion. The preparation method of the fiber reinforced composite traction seat is to sequentially lay layers on the surfaces of the first mold, the second mold and the third mold, and form a blank after the molds are closed and cured, and the fiber reinforced composite traction seat is obtained by machining. The present invention gives full play to the high strength and low density advantages of carbon fiber, and the tensile strength meets the product performance requirements.

Description

Technical Field

[0001] The invention relates to a composite material fifth wheel, in particular to a fiber reinforced composite material fifth wheel and a preparation method and a mold thereof. Background Art

[0002] The suspension frame is the core component of the maglev train, and the traction seat is an important force transmission component installed on the longitudinal beam of the suspension frame, which transmits traction and braking force to the maglev train. The existing traction seat is made of aluminum alloy. After the blank is cast, it is welded to the longitudinal beam of the suspension frame, and then processed and formed by a large CNC machine tool and the suspension frame. It has high density, low strength and complex process. With the increasing requirements for lightweight vehicles in the rail transit field, traditional aluminum alloy materials can no longer meet the existing needs. The use of lightweight and high-strength carbon fiber composite materials as a replacement has great room for weight reduction.

[0003] The strength of aluminum alloy is usually between 120MPa and 300MPa, and the density is about 2.75g / cm 3 The strength is only 200MPa. The original maglev train traction seat is made of aluminum alloy and is formed through multiple processes such as casting, welding, and machining. It has the disadvantages of high density, complex process, low strength, and difficult maintenance. Therefore, the existing technology has the disadvantages of high density, low strength, and complex process.

[0004] The density of carbon fiber is only 1.65g / cm 3 , and the tensile strength along the fiber direction can reach 500-800MPa, which shows that carbon fiber has lower density and higher strength. However, carbon fiber composite material is a two-dimensional material, and the shear strength between layers is only 30-80MPa. Therefore, how to design the ply and molding process to give full play to the lightweight and high-strength characteristics of carbon fiber composite materials is the key to this application. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a fiber reinforced composite material traction seat and its preparation method and mold in view of the shortcomings of the existing technology, so as to give full play to the high strength and low density advantages of carbon fiber, and the tensile strength reaches the product performance requirements.

[0006] The present invention discloses a mold of a fiber reinforced composite material traction seat, comprising a first mold, a second mold and a third mold, wherein the first mold comprises a platform and an arc-shaped protrusion arranged on the upper surface of the platform, the second mold comprises a first recessed portion and a first right-angle portion, and the third mold comprises a second recessed portion and a first right-angle portion.

[0007] Since the main force direction of the traction seat is approximately symmetrical, the present application designs a symmetrical lamination structure of left and right modules. The characteristics of the mold design in the present application are: the first mold is used for positioning to ensure the assembly accuracy of the traction seat and the longitudinal beam, and the second mold and the third mold ensure the assembly accuracy of the traction seat and the drawbar.

[0008] The present invention relates to a continuous carbon fiber fifth wheel, with an overall thickness of 20 mm and a fiber direction (such as Figure 1 ), the horizontal traction forces on the left and right are almost the same, so the second and third molds are divided into symmetrical structures when divided into modules, and the typical composite material structure T-beam (such as Figure 2 ), the structure is simple to manufacture and has good processability, and fully utilizes the high strength and low density advantages of carbon fiber. At the same time, the present invention not only has a simple molding process and a short molding cycle, but also is easy to disassemble and reduces maintenance costs.

[0009] The present invention also discloses a method for preparing a fiber reinforced composite material fifth wheel, comprising the following steps:

[0010] Prepare a first mold, and perform a first carbon fiber prepreg layering on the upper surface of the platform and the arc-shaped raised portion;

[0011] Preparing a second mold, and performing a second carbon fiber prepreg layering on the surfaces of the first recessed portion and the first right-angle portion;

[0012] The first mold and the second mold are closed together so that the second carbon fiber prepreg layer on the second mold is laid on the left upper surface of the first carbon fiber prepreg layer on the first mold;

[0013] Performing a third carbon fiber prepreg layup on the second carbon fiber prepreg layup on the surface of the first right-angle portion;

[0014] preparing a third mold, and performing a fourth carbon fiber prepreg layering on the surfaces of the second recessed portion and the first right-angle portion;

[0015] The third mold and the first mold are molded together so that the fourth carbon fiber prepreg layer on the third mold is laid on the right upper surface of the first carbon fiber prepreg layer on the first mold to obtain an overall mold after laying;

[0016] The integral mold after layering is solidified and formed into a blank, and then machined to obtain a fiber reinforced composite traction seat.

[0017] The fiber direction of the invention is designed according to the force transmission direction of the fifth wheel, giving full play to the high strength advantage of carbon fiber and greatly reducing the weight of the fifth wheel. Figure 1), in order to ensure the fiber continuity of the traction seat in the force direction, the fibers of each module are continuous during layering. The fiber layer cross section is as follows: Figure 4 The fiber laying direction is all along the mold surface, and the pressure is more uniform during molding. Each layer needs to be tightly fitted during laying to make the prepreg layers more compact.

[0018] The thickness of the first carbon fiber prepreg layer is 3-5 mm, the thickness of the second carbon fiber prepreg layer and the fourth carbon fiber prepreg layer is 14-17 mm, and the thickness of the third carbon fiber prepreg layer is 7-10 mm.

[0019] The ply thickness in this application is the result of optimization based on stress analysis and experimental research. If the ply of the bottom first mold is too thin, the bottom reinforcement layer will be delaminated as a whole when the traction seat is stressed, and interlayer peeling will occur (such as Fig.19 ); The reinforcement layer of the first mold at the bottom was too thick, resulting in a reduction in the thickness of the second and third modules. The rigidity of the arched structure of the traction seat was insufficient, and the maximum bearing capacity of the traction seat was only 45kN, which could not meet the test requirement of 50kN.

[0020] The processes of the first carbon fiber prepreg layering, the second carbon fiber prepreg layering, the third carbon fiber prepreg layering and the fourth carbon fiber prepreg layering are to carry out bag pressing once every 10 to 15 layers of carbon fiber prepreg, and the holding time for each time is ≥30 minutes, which effectively improves the interlayer bonding strength.

[0021] During production, the blanking drawings of the three modules are designed according to the three-dimensional and mold dimensions, and the prepreg is cut with a cloth cutting machine to ensure the dimensional accuracy; each layer needs to be tightly fitted during layering, and the prepreg layers are more compacted every 10 to 15 layers, and the pressure holding time is ≥30 minutes each time. The thickness of a single layer of carbon fiber is only 0.4mm, and the thickest dimension of the traction seat reaches 40mm, that is, the number of carbon fiber layers needs to reach 100 layers. Although this application optimizes the layering scheme through module division, the number of layers of a single module is still up to 40 layers. If the one-time laying is adopted and the bagging and curing method is directly adopted, the bubbles between the carbon fiber layers are squeezed inside and difficult to be discharged. After curing, they will become bubbles or delamination. In order to reduce the risk of this process defect, this application has experimentally studied that the bagging and pressing are required every 10 to 15 layers to fully compact the layers. On the premise of meeting the mechanical performance requirements, the bagging and pressing molding process has a short production cycle compared with the autoclave and mold pressing, and the mold cost and energy consumption are lower.

[0022] The first carbon fiber prepreg layer, the second carbon fiber prepreg layer, the third carbon fiber prepreg layer and the fourth carbon fiber prepreg layer all adopt plain / twill alternating layer. Plain / twill alternating layer effectively improves the bonding strength between layers.

[0023] After the first mold and the second mold are closed, bag pressing is performed and the pressure is maintained for 0.5-2 hours.

[0024] After the first mold and the second mold are laid separately, the two modules are combined and the bag pressure is maintained for 1 hour to make the two modules fit tightly without gaps.

[0025] The temperature of the overall mold curing after laying is 80-100℃ for 1-2h, and then 100-150℃ for another 0.5-2h.

[0026] The first carbon fiber prepreg layup, the second carbon fiber prepreg layup, the third carbon fiber prepreg layup and the fourth carbon fiber prepreg layup all use continuous carbon fiber prepreg.

[0027] The first carbon fiber prepreg layup, the second carbon fiber prepreg layup, the third carbon fiber prepreg layup and the fourth carbon fiber prepreg layup are all laid in the same direction.

[0028] From the perspective of process design, in order to ensure the appearance size and surface flatness of the traction seat, the mold is designed as a pair of molds (such as Figure 3 ); Carbon fiber epoxy prepreg is laid in the same direction to ensure the strength of interlayer bonding.

[0029] The invention also discloses a fiber reinforced composite material fifth wheel produced by the method for producing the fiber reinforced composite material fifth wheel.

[0030] The key to this application is to make the main load-bearing direction the fiber continuous direction and the secondary load-bearing direction the interlayer shear direction through the ply design, so as to give full play to the light weight and high strength characteristics of carbon fiber composite materials. In recent years, the application of carbon fiber composite materials in various industries has gradually deepened, and the difference between this application and other carbon fiber parts is mainly reflected in the ply design and molding process design.

[0031] The key point of the present invention is the design of the laying scheme, the molding scheme and the connection scheme, and the protection point is the laying scheme, the molding process technology and the connection technology of the fiber reinforced composite material traction seat.

[0032] Compared with the prior art, the invention has the following beneficial effects: compared with the existing aluminum alloy solution, the invention improves the load-bearing capacity of the fifth wheel and reduces the weight by more than 40%. The maximum load-bearing capacity of the fifth wheel meets the test requirement of 50 kN. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. 4 is a force analysis diagram of an embodiment of the present invention.

[0034] Figure 2Schematic diagram of T-beam layup in one embodiment of the present invention (the third carbon fiber prepreg layup in the second carbon fiber prepreg layup and the fourth carbon fiber prepreg layup are not drawn).

[0035] Figure 3 Schematic diagram of a mold structure according to an embodiment of the present invention.

[0036] Figure 4 It is a cross-sectional view of the ply of the fifth wheel in one embodiment of the present invention.

[0037] Figure 5 This is step 1 of the preparation method in one embodiment of the present invention: preparing a first mold.

[0038] Figure 6 This is step 2 of the preparation method in one embodiment of the present invention, laying a layer on the first mold.

[0039] Figure 7 This is step three of the preparation method in one embodiment of the present invention: preparing a second mold.

[0040] Figure 8 This is step 4 of the preparation method in one embodiment of the present invention, laying a layer on the second mold.

[0041] Fig. 9 This is step five of the preparation method in one embodiment of the present invention, combining the first mold and the second mold.

[0042] Fig.10 This is step six of the preparation method in one embodiment of the present invention: preparing a third mold.

[0043] Fig.11 This is step seven of the preparation method in one embodiment of the present invention: laying a layer on the third mold.

[0044] Fig.12 This is step eight of the preparation method in one embodiment of the present invention, combining the third mold with the first mold and the second mold.

[0045] Fig.13 This is step nine of the preparation method in one embodiment of the present invention, namely, the solidified blank.

[0046] Fig.14 This is step ten of the preparation method in one embodiment of the present invention, the fifth wheel after machining.

[0047] Fig.15 This is a single-sided integral mold in the comparative example of the present invention.

[0048] Fig.16 It is a top view of a fifth wheel according to an embodiment of the present invention.

[0049] Fig.17 It is a side view of a fifth wheel according to an embodiment of the present invention.

[0050] Fig.18 is the weight of the fifth wheel in one embodiment of the present invention.

[0051] Fig.19 The fracture and interlayer peeling occurred in the comparative example of the present invention.

[0052] FIG. 20 is a photograph of a mechanical property test in one embodiment of the present invention. DETAILED DESCRIPTION

[0053] like Figure 3 As shown, a mold of a fiber reinforced composite material traction seat includes a first mold 1, a second mold 2 and a third mold 3, wherein the first mold 1 includes a platform 11 and an arc-shaped protrusion 12 arranged on the upper surface of the platform 11, the second mold 2 includes a first recessed portion 21 and a first right-angle portion 22, and the third mold 3 includes a second recessed portion 31 and a second right-angle portion 32.

[0054] like Figure 5-14 As shown, a method for preparing a fiber reinforced composite material fifth wheel comprises the following steps:

[0055] like Figure 5-6 As shown, a first mold 1 is prepared, and a first carbon fiber prepreg layer is laid on the upper surface of the platform 11 and the arc-shaped protrusion 12 to obtain a first carbon fiber prepreg layer 41;

[0056] like Figure 7-8 As shown, a second mold 2 is prepared, and a second carbon fiber prepreg layer is laid on the surface of the first recessed portion 21 and the first right-angle portion 22 to obtain a second carbon fiber prepreg layer 42;

[0057] like Fig. 9 As shown, the first mold 1 and the second mold 2 are molded together so that the second carbon fiber prepreg layer 42 on the second mold 2 is laid on the left upper surface of the first carbon fiber prepreg layer 41 on the first mold;

[0058] like Fig. 9 As shown, a third carbon fiber prepreg layer 43 is performed on the second carbon fiber prepreg layer 42 on the surface of the first right-angle portion 22 to obtain a third carbon fiber prepreg layer 43;

[0059] like Figure 10-11 As shown, a third mold 3 is prepared, and a fourth carbon fiber prepreg layer is laid on the surface of the second recessed portion 31 and the second right-angle portion 32 to obtain a fourth carbon fiber prepreg layer 44;

[0060] like Fig.12As shown, the third mold 3 and the first mold 1 are molded together, so that the fourth carbon fiber prepreg layer 44 on the third mold 3 is laid on the right upper surface of the first carbon fiber prepreg layer 41 on the first mold 1, and the overall mold after laying is obtained;

[0061] like Fig.13 As shown, the whole mold after the layering is solidified and formed into a blank 4, as shown in FIG. Fig.14 As shown, a fiber reinforced composite traction seat is obtained by machining.

[0062] The thickness of the first carbon fiber prepreg ply 41 is 3-5 mm, the thickness of the second carbon fiber prepreg ply 42 and the fourth carbon fiber prepreg ply 44 is 14-17 mm, and the thickness of the third carbon fiber prepreg ply 43 is 7-10 mm.

[0063] The processes of the first carbon fiber prepreg layer 41, the second carbon fiber prepreg layer 42, the third carbon fiber prepreg layer 43 and the fourth carbon fiber prepreg layer 44 are all to perform bag pressing once every 10 to 15 layers of carbon fiber prepreg, and the holding time for each time is ≥30 minutes.

[0064] The first carbon fiber prepreg ply 41, the second carbon fiber prepreg ply 42, the third carbon fiber prepreg ply 43 and the fourth carbon fiber prepreg ply 44 are all laid in a plain / twill alternating pattern.

[0065] After the first mold 1 and the second mold 2 are closed, bag pressing is performed and the pressure is maintained for 0.5-2 hours.

[0066] The temperature of the overall mold curing after laying is 80-100℃ for 1-2h, and then 100-150℃ for another 0.5-2h.

[0067] The first carbon fiber prepreg ply 41 , the second carbon fiber prepreg ply 42 , the third carbon fiber prepreg ply 43 and the fourth carbon fiber prepreg ply 44 all use continuous carbon fiber prepreg.

[0068] Example

[0069] The fiber direction of the invention is designed according to the force transmission direction of the fifth wheel, giving full play to the high strength advantage of carbon fiber and greatly reducing the weight of the fifth wheel. Figure 1 ), in order to ensure the fiber continuity of the traction seat in the force direction, the fibers of each module are continuous during layering. The fiber layer cross section is as follows: Figure 4 .

[0070] During production, the blanking drawings of the three modules are designed according to the three-dimensional and mold dimensions, and the prepreg is cut with a cloth cutting machine to ensure the dimensional accuracy; each layer needs to be tightly fitted during layering, and the prepreg layers are more compacted every 10 to 15 layers, and the pressure holding time is ≥30 minutes each time. The thickness of a single layer of carbon fiber is only 0.4mm, and the thickest dimension of the traction seat reaches 40mm, that is, the number of carbon fiber layers needs to reach 100 layers. Although this application optimizes the layering scheme through module division, the number of layers of a single module is still up to 40 layers. If the one-time laying is adopted and the bagging and curing method is directly adopted, the bubbles between the carbon fiber layers are squeezed inside and difficult to be discharged. After curing, they will become bubbles or delamination. In order to reduce the risk of this process defect, this application has experimentally studied that the bagging and pressing are required every 10 to 15 layers to fully compact the layers. On the premise of meeting the mechanical performance requirements, the bagging and pressing molding process has a short production cycle compared with the autoclave and mold pressing, and the mold cost and energy consumption are lower.

[0071] 1) From the perspective of process design, in order to ensure the appearance size and surface flatness of the traction seat, the mold is designed as a pair of molds (such as Figure 3 ); Carbon fiber epoxy prepreg is laid in the same direction to ensure the strength of the interlayer bonding force. Since the main force direction of the traction seat is approximately symmetrical, the present application designs a symmetrical ply structure of left and right modules. The characteristics of the mold design in the present application are: 1. The first mold is used for positioning to ensure the assembly accuracy of the traction seat and the longitudinal beam, and the second and third molds ensure the assembly accuracy of the traction seat and the traction rod; 2. The ply operation is optimized, and the original single module with the thickest 142 layers is optimized to 57 layers through the process, thereby reducing the number of bag pressing times; 3. The fiber ply direction is all along the mold surface, and the pressure is more uniform during molding.

[0072] 2) In terms of material selection, the appearance of the traction seat must meet good molding and processing requirements; from a structural perspective, the traction seat is a load-bearing component and must meet the mechanical performance test requirements of the traction seat.

[0073] 3) In terms of molding technology, after multiple process verifications and experimental tests, the optimal solution is that the bottom reinforcement layer of the first mold is 4 mm thick, and the second and third modules are symmetrical structures with an average layer of 16 mm (such as Figure 3 The ply thickness in this application is the result of optimization based on stress analysis and experimental research. If the ply of the bottom first mold is too thin, the bottom reinforcement layer will be delaminated as a whole when the traction seat is stressed, and interlayer peeling will occur (such as Fig.19 ); The reinforcement layer of the first mold at the bottom was too thick, resulting in a reduction in the thickness of the second and third modules. The rigidity of the arched structure of the traction seat was insufficient, and the maximum bearing capacity of the traction seat was only 45kN, which could not meet the test requirement of 50kN.

[0074] During the laying process, the process is strictly followed to achieve the requirements of product integration. When laying, first lay the bottom reinforcement layer of 4mm (7 layers of plain weave and 7 layers of twill weave). Figure 6 The left and right arc modules are symmetrical, both are 16mm (28 layers of plain weave and 29 layers of twill weave). Figure 8 , Fig.11 , the left and right modules are laid separately; after the three modules are laid separately, modules 1 and 2 (or 3) are combined, and then a 40mm thick filling layer (8mm) is laid in the middle. Fig. 9 , the final combination 3 (or 2) is as follows Fig.12 ; To ensure assembly accuracy, the assembly circular holes and the middle hollow weight reduction position are machined after curing and forming; Strictly follow the calculated theoretical number of layers and the direction of plying, and use a scraper to flatten and compact each layer of fabric after laying to remove bubbles; During the plying process, bag press every 10 layers to ensure that there are no gaps or bubbles between layers, and each pressure holding time is ≥30min. Carbon fiber epoxy prepreg uses AVIC's CW240 (twill weave) and CW200T (plain weave), and the alternating plain / twill plying effectively improves the interlayer bonding strength; Curing temperature: 90℃ / 1.5h+130℃ / 1h.

[0075] After the modules 1 and 2 are laid separately, combine the two modules and press them for 1 hour to make the two modules fit tightly without gaps. Then lay the middle filling layer of 8mm (such as Fig. 9 ); After the filling layer is laid, the third module is assembled (such as Fig.12 ).

[0076] Figure 3 An embodiment of the invention is shown, in which the product structure is divided into three modules, which are first independently laid and formed, and then combined and solidified into one. Through process design, material selection, and a reasonable molding process solution, the integrated molding of the fifth wheel is finally achieved.

[0077] like Figure 16-18 As shown in 20, the product of the present invention has been tested by the following experiments

[0078] (1) Flame retardant / smoke toxicity test, the flame retardant level reaches EN 45545-HL2 level,

[0079] (2) Environmental testing, meeting TB / T 3139-2021 standards

[0080] (3) Conventional mechanical properties test, passed the 50kN traction test

[0081] (4) Passed the wet heat aging test

[0082] The present invention uses finite element simulation software to analyze stress cloud diagrams, modes, and vibration simulations to prove that the solution is feasible.

[0083] This application optimizes the layering operation, reducing the original single module's maximum thickness of 142 layers to 57 layers through process optimization, thereby also reducing the number of bag pressing times.

[0084] Comparative Example 1

[0085] The difference between the comparative example and the embodiment is that a single-sided mold integral mold is used. Fig.15 ) It is difficult to operate and it is not possible to make both the upper and lower surfaces of the traction seat smooth. The overall mold opening is difficult to lay layers in the middle position (40mm), and it is difficult to lay layers in place at the corners, resulting in gaps between product layers, glue accumulation and other defects.

[0086] Comparative Example 2

[0087] The difference between the comparative example and the embodiment is that the thickness of the mold layer is different. The initial thickness type is 10mm for the first mold layer at the bottom, and 10mm for the second and third mold layers, which is a symmetrical structure. After the traction limit test, it was found that the layer structure could not meet the mechanical performance requirements, and the traction seat broke at the maximum stress concentration position (R angle at 40mm in the middle); in the later stage, multiple parts were made and tested, and the first mold, the second mold and the third mold tried 6mm+14mm, 4mm+16mm, 2mm+18mm and other layer thicknesses. The test found that: the bottom first mold layer was too thin, and the traction seat was stressed, which caused the bottom layer to be delaminated as a whole and interlayer peeling occurred (such as Fig.19 ); The thickness of the first mold at the bottom is too thick, which leads to the reduction of the thickness of the second mold and 3. Its strength cannot meet the maximum traction force, and fracture occurs at the maximum stress concentration. According to the mechanical test results, 4mm+16mm is the optimal layering solution.

Claims

1. A method for preparing a fiber reinforced composite fifth wheel, characterized in that The following steps are involved: A first mold (1) is prepared, and a first carbon fiber prepreg layer is performed on the upper surface of the platform (11) and the arc-shaped raised portion (12); A second mold (2) is prepared, and a second carbon fiber prepreg layer is performed on the surface of the first recessed portion (21) and the first right-angle portion (22); The first mold (1) and the second mold are closed together so that the second carbon fiber prepreg layer (42) on the second mold (2) is laid on the left upper surface of the first carbon fiber prepreg layer (41) on the first mold; Performing a third carbon fiber prepreg layer on the second carbon fiber prepreg layer (42) on the surface of the first right-angle portion (22); preparing a third mold (3), and performing a fourth carbon fiber prepreg layering on the surface of the second recessed portion (31) and the second right-angle portion (32); The third mold (3) and the first mold (1) are molded together so that the fourth carbon fiber prepreg layer (44) on the third mold (3) is laid on the right upper surface of the first carbon fiber prepreg layer (41) on the first mold (1), thereby obtaining an overall mold after the layering; The whole mold after the layering is solidified and formed into a blank, and then machined to obtain a fiber reinforced composite material traction seat; The thickness of the first carbon fiber prepreg layer (41) is 3-5 mm, the thickness of the second carbon fiber prepreg layer (42) and the fourth carbon fiber prepreg layer (44) is 14-17 mm, and the thickness of the third carbon fiber prepreg layer (43) is 7-10 mm; The first mold (1) comprises a platform (11) and an arc-shaped protruding portion (12) arranged on the upper surface of the platform (11); the second mold (2) comprises a first recessed portion (21) and a first right-angle portion (22); and the third mold (3) comprises a second recessed portion (31) and a second right-angle portion (32).

2. The method for preparing a fiber reinforced composite fifth wheel according to claim 1, characterized in that: The processes for the first carbon fiber prepreg laying (41), the second carbon fiber prepreg laying (42), the third carbon fiber prepreg laying (43) and the fourth carbon fiber prepreg laying (44) are all to carry out bag pressing once every 10 to 15 layers of carbon fiber prepreg, and the holding time for each time is ≥30 minutes.

3. The method for preparing a fiber reinforced composite fifth wheel according to claim 1, characterized in that: The first carbon fiber prepreg ply (41), the second carbon fiber prepreg ply (42), the third carbon fiber prepreg ply (43) and the fourth carbon fiber prepreg ply (44) all adopt plain / twill alternating plying.

4. The method for preparing a fiber reinforced composite fifth wheel according to any one of claims 1 to 3, characterized in that: After the first mold (1) and the second mold (2) are closed, bag pressing is performed and the pressure is maintained for 0.5-2 hours.

5. The method for preparing a fiber reinforced composite fifth wheel according to any one of claims 1 to 3, characterized in that: The temperature of the overall mold curing after laying is 80-100℃ for 1-2h, and then 100-150℃ for another 0.5-2h.

6. The method for preparing a fiber reinforced composite fifth wheel according to any one of claims 1 to 3, characterized in that: The first carbon fiber prepreg ply (41), the second carbon fiber prepreg ply (42), the third carbon fiber prepreg ply (43) and the fourth carbon fiber prepreg ply (44) all use continuous carbon fiber prepreg.

7. The method for preparing a fiber reinforced composite fifth wheel according to any one of claims 1 to 3, characterized in that: The first carbon fiber prepreg layer (41), the second carbon fiber prepreg layer (42), the third carbon fiber prepreg layer (43) and the fourth carbon fiber prepreg layer (44) are all laid along the same direction.

8. A fiber reinforced composite material fifth wheel produced according to the method for producing a fiber reinforced composite material fifth wheel according to any one of claims 1 to 7.

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