A molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall

Abstract

This invention belongs to the field of composite material molding technology and provides a molding and demolding method for a composite material rotary body with reinforcing ribs on the inner wall, including: S1, building a rigid frame; S2, surrounding the rigid frame, filling it with foam to form a solid core mold; S3, grinding the core mold, applying resin putty to the outer surface of the core mold, and curing; S4, machining the outer surface of the core mold to obtain a molding mold with a groove; S5, attaching release paper and laying reinforcing fiber fabric on the outer surface of the molding mold and inside the groove; S6, curing the reinforcing fabric to form a composite material structure; S7, removing the resin putty, foaming material, and rigid frame from the inside of the composite material structure to obtain the composite material rotary body. This invention can achieve both integrated molding of the reinforcing ribs and the main structure and effective demolding of the whole after molding, and is not limited by the size of the composite material rotary body product, the shape and number of reinforcing ribs, resulting in high molding and demolding efficiency and good molding quality.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, and to a molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall, and more particularly to an integral molding and demolding method for a hollow rotating body structure of resin-based composite material with reinforcing ribs on the inner wall. Background Technology

[0002] For resin-based composite materials with complex reinforcing rib structures on the surface, existing technologies typically use molding molds made of fiberglass or metal to ensure smooth demolding.

[0003] However, for the special structure of a hollow rotating body made of resin-based composite material with an internal cavity and a complex reinforcing rib structure on the inner wall of the cavity, it is impossible to simultaneously meet the two requirements of integral molding of the reinforcing ribs and the main body of the rotating body and effective demolding of the whole after molding, whether using the existing male mold or the existing female mold.

[0004] The current mainstream manufacturing process involves fabricating the reinforcing ribs and the main rotating body separately before assembling and connecting them. This method has the following drawbacks:

[0005] ① For large-sized composite material products with complex main structures, the main structure will undergo certain deformation after molding and demolding, resulting in the assembly interface no longer being in an ideal state.

[0006] ② For reinforcing ribs with irregular shapes such as rings, molding them separately and then assembling them will result in poor overall structural continuity and low structural strength of the composite material.

[0007] ③ For reinforcing ribs with irregular shapes such as rings, it is difficult to guarantee their deformation control, which is not conducive to the realization of subsequent assembly accuracy.

[0008] ④ The assembly and connection of composite material structures involves common processes such as drilling, screwing, and riveting, which can have a certain adverse effect on the overall performance of the composite material and can also easily affect the mechanical properties of the composite material.

[0009] Therefore, for hollow rotating bodies made of composite materials with reinforcing ribs on the inner wall, the existing molding process is difficult to simultaneously meet the two requirements of integral molding of the reinforcing ribs and the main structure of the rotating body and effective demolding of the whole after molding. Summary of the Invention

[0010] In view of this, the present invention aims to propose a molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall. This method is specifically designed for the molding of hollow composite material rotating bodies with reinforcing ribs on the inner wall, in order to solve the problem that the molding process in the prior art is difficult to simultaneously achieve integrated molding of the reinforcing ribs and the main structure of the rotating body and effective overall demolding after molding.

[0011] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0012] A molding and demolding method for a composite material rotary body with reinforcing ribs on the inner wall includes: S1, constructing a rigid frame on a rigid platform using rigid plates; S2, enclosing the rigid frame and filling the enclosed space with foaming material until a solid core mold is formed; S3, sanding the surface of the core mold and uniformly applying resin putty to the sanded outer surface of the core mold until the putty layer thickness is ≥40mm, and then curing; S4, machining the outer surface of the core mold according to the theoretical line shape corresponding to the composite material rotary body product to obtain a molding die, wherein the outer surface of the molding die has grooves corresponding to the reinforcing ribs; S5, attaching release paper and laying reinforcing fiber fabric on the outer surface of the molding die and in the grooves to form a main reinforcing fabric layup and a reinforcing rib reinforcing fabric layup; S6, injecting resin into each reinforcing fabric layup and curing it under the condition of full impregnation of the reinforcing fiber fabric to form a composite material structure; S7, removing the resin putty, foaming material, and rigid frame from the interior of the composite material structure to obtain the composite material rotary body with reinforcing ribs on the inner wall.

[0013] Furthermore, the rigid plate includes an annular rigid plate and a longitudinal rigid plate, wherein the longitudinal rigid plate is connected to the rigid platform and each annular rigid plate respectively.

[0014] Furthermore, the rigid plates are connected to each other by at least one of riveting, snap-fitting, or fastener connection, and the rigid plates are connected to the rigid platform by fasteners.

[0015] Furthermore, in step S2, the foaming material includes at least one of polyurethane foaming material and epoxy resin foaming material.

[0016] Furthermore, in step S2, the ambient temperature during the foaming and filling process is controlled at 25±5℃ and the relative humidity is <70%; after the foaming and filling is completed, it is left to stand naturally at room temperature for no less than 24 hours.

[0017] Furthermore, in step S2, after the foam filling is cured, the core mold is filled with resin in a vacuum environment and cured at room temperature for no less than 24 hours.

[0018] Furthermore, in step S3, the resin putty includes a resin liquid, a curing agent, fumed silica, and glass microspheres in a mass ratio of 100:(1.2~2):(10~30):(0~10).

[0019] Furthermore, the resin adhesive includes at least one of epoxy resin adhesive and vinyl resin adhesive, and the curing agent is curing agent LPT.

[0020] Furthermore, in step S5, the reinforcing fiber fabric includes at least one fiber fabric selected from glass fiber, carbon fiber, carbon / glass hybrid fiber, plant fiber, basalt fiber, quartz fiber, Kevlar fiber, ultra-high molecular weight polyethylene fiber, and PBO fiber.

[0021] Compared with existing technologies, the molding and demolding method of a composite material rotating body with reinforcing ribs on the inner wall described in this invention has the following advantages:

[0022] This invention discloses a molding and demolding method for a composite material rotary body with reinforcing ribs on its inner wall. Based on a rigid platform providing a reference for subsequent machine tool precision machining, a rigid frame is constructed using the rigid platform and rigid plate. A solid rigid mandrel is formed by foaming and filling the rigid frame and applying a putty layer. This provides the foundation for the precision machining of the groove structure corresponding to the reinforcing ribs and also enables precise positioning of the reinforcing rib fabric layup, facilitating the laying operation and ensuring the precision of the final product's linear shape. Furthermore, thanks to the ability to set grooves on the outer surface of the mandrel according to actual needs, precise positioning and synchronous integration of the reinforcing rib fabric layup and the main reinforcing fabric layup are achieved during the laying process. The fiber structures can be interlocked and superimposed, organically combining the reinforcing rib fabric layup and the main reinforcing fabric layup, improving the integration degree and structural strength of the reinforcing ribs and the main structure.

[0023] Furthermore, this application, through the aforementioned method, achieves integrated molding of the reinforcing ribs and the main structure of the composite rotating body, avoiding many problems associated with the existing process of separate fabrication and reassembly, thus improving production efficiency and the overall structural strength of the product. On the other hand, the molding die (core mold) of this application can be easily removed after integrated molding, achieving efficient demolding of the composite rotating body structure with complex reinforcing ribs. In short, this application can balance integrated molding of the reinforcing ribs and the main structure with effective overall demolding after molding, without being limited by the size of the composite rotating body product, the shape and number of reinforcing ribs, and features high molding and demolding efficiency, good molding quality, low process risk, and strong process applicability. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic diagram of the rigid platform described in an embodiment of the present invention;

[0026] Figure 2 This is a partial schematic diagram of the rigid frame described in an embodiment of the present invention;

[0027] Figure 3 This is a partial schematic diagram (including a partial cross-sectional view at the putty layer) of the core mold described in an embodiment of the present invention.

[0028] Figure 4 This is a partial schematic diagram of the molding die described in an embodiment of the present invention;

[0029] Figure 5 This is a (partial) schematic diagram of the laying of reinforcing fiber fabric on the molding die according to an embodiment of the present invention;

[0030] Figure 6 This is a partial structural diagram of the composite material rotating body after demolding in an embodiment of the present invention, after being cut open.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Rigid platform; 2. Annular rigid plate; 3. Longitudinal rigid plate; 4. Foam-filled area; 5. Putty layer; 6. Circumferential groove; 7. Longitudinal groove; 8. Reinforcing ribs and fabric lay-up; 9. Main reinforcing fabric lay-up; 10. Circumferential reinforcing ribs; 11. Longitudinal reinforcing ribs; 12. Main structure. Detailed Implementation

[0033] The inventive concepts of this disclosure will be described below using terminology commonly used by those skilled in the art to communicate the essence of their work to others skilled in the art. However, these inventive concepts may be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] For the molding of hollow composite rotating bodies with reinforcing ribs on the inner wall, this embodiment proposes a molding and demolding method for composite rotating bodies with reinforcing ribs on the inner wall, in order to solve the problem that existing molding processes cannot simultaneously achieve integrated molding of the reinforcing ribs and the main body of the rotating body and effective overall demolding after molding. (See attached figure.) Figure 1-6 As shown, the method includes:

[0037] S1. A detachable rigid frame is constructed on the rigid platform 1 using rigid plates.

[0038] The rigid platform 1 is made of metal materials such as steel and aluminum alloy and can be used as a platform for positioning reference in machine tool processing.

[0039] The rigid plate has a thickness ≥10mm and includes annular rigid plates 2 and longitudinal rigid plates 3. Each rigid plate is cut and processed according to the spatial dimensions corresponding to a 50mm inward offset from the composite material rotary body product. The longitudinal rigid plates 3 are connected to the rigid platform 1 and each annular rigid plate 2, and are assembled according to the shape corresponding to a 50mm inward offset from the composite material rotary body product. The connection methods between the rigid plates and between the rigid plates and the rigid platform 1 include at least one of riveting, snap-fitting, and fastener connection. Preferably, the rigid plates are connected to the rigid platform 1 via fasteners. Since different composite material rotary body products vary in size and shape, this application does not impose excessive restrictions on the number or processing dimensions of the annular rigid plates 2 and longitudinal rigid plates 3, as long as the assembled rigid frame is stable and does not deform. The rigid plates are preferably made of wood, plastic, metal, or other non-deformable materials.

[0040] The rigid frame can be considered as the internal skeleton of the core mold (forming mold) in the following text, providing a structural strength basis.

[0041] S2. Enclose the rigid frame with foam material and fill the enclosed space with foam until a solid core mold is formed.

[0042] The foaming material includes at least one of AB type foaming materials such as polyurethane foaming material and epoxy resin foaming material that can withstand high temperatures above 150℃, and the foaming material density is >200kg / m³. 3 The foaming and filling process requires the ambient temperature to be controlled at 25±5℃ and the relative humidity to be <70% to ensure that the foaming and curing of the foaming material proceeds normally and stably. After the foaming and filling is completed, it should be left to stand naturally at room temperature for no less than 24 hours to fully release the risk of foam deformation.

[0043] As the foaming material fills the enclosure space to form the foam filling area 4, the foam will come into contact with the rigid frame. Accordingly, the surface of the rigid frame needs to be kept clean, dry, and free of water stains and oil stains to avoid affecting the normal progress of the foaming process.

[0044] To further improve the stability and compressive strength of the solid core mold, in step S2 of this application, after the foam filling and curing, the core mold is grouted with resin under vacuum and cured at room temperature for no less than 24 hours. This vacuum grooving allows the resin to fully penetrate the core mold, preventing unnecessary gaps and thus improving the stability and compressive strength of the solid core mold. The resin can be epoxy resin, polyethylene resin, ABS resin, etc., but this application is not limited to these; they are merely examples for illustrative purposes.

[0045] S3. Grind the surface of the core mold, and evenly apply resin putty to the outer surface of the ground core mold until the putty layer thickness is ≥40mm and then cure.

[0046] For the grinding of the core model surface, it is still necessary to grind according to the final size requirements of the composite material rotating body product, and ensure a grinding sinking amount of 30mm.

[0047] The resin putty comprises a resin liquid, a curing agent, fumed silica, and glass microspheres in a mass ratio of 100:(1.2~2):(10~30):(0~10), and is prepared into a paste-like resin putty at room temperature. After being scraped and cured, it can form a structural reinforcement layer on the outer surface of the core mold to enhance the rigidity and processability of the core mold. The core mold of this application can withstand a pressure of not less than 0.06MPa without collapsing or deforming.

[0048] The resin adhesive includes at least one of room-temperature curing resins such as epoxy resin adhesive and vinyl resin adhesive, and the curing agent is commercially available curing agent LPT.

[0049] Preferably, in step S3, the density of the cured putty layer 5 is >200 kg / m³. 3 The thickness of putty layer 5 is ≥40mm.

[0050] S4. Based on the shape, size, and reinforcing rib position requirements of the composite material rotary body product, and according to the theoretical line shape corresponding to the composite material rotary body product, the outer surface of the core mold is machined to obtain the molding mold, and the outer surface of the molding mold is formed with a groove corresponding to the reinforcing rib.

[0051] Correspondingly, the outer surface of the molding die corresponds to the inner wall of the composite material rotary body product. The machining in step S4 can be completed by placing the entire core mold on a machine tool. The size, position, and shape of the groove need to be based on the actual structural design requirements of the composite material rotary body product; this application does not impose excessive restrictions on them. Accordingly, the circumferential groove 6 and longitudinal groove 7 shown in the accompanying drawings are for the circumferential reinforcing rib 10 and longitudinal reinforcing rib 11 on the inner wall of the main structure 12 of the product. This application only uses them as examples to facilitate understanding of the solution and is not limited thereto.

[0052] S5. Adhere release paper to the outer surface of the molding mold and inside the groove, and lay reinforcing fiber fabric according to the laying requirements of reinforcing fabric layup to form the main reinforcing fabric layup 9 and the reinforcing rib reinforcing fabric layup 8.

[0053] The reinforcing fiber fabric includes at least one type of reinforcing fiber fabric such as glass fiber, carbon fiber, carbon / glass hybrid fiber, plant fiber, basalt fiber, quartz fiber, Kevlar fiber, ultra-high molecular weight polyethylene fiber, and PBO fiber.

[0054] S6. Inject resin into each reinforcing fabric layer, and cure and mold it under the condition that the reinforcing fiber fabric is fully impregnated to form a composite material structure; specifically, the curing and molding of the reinforcement can be completed through processes such as VARI, OOA, and hot pressing to form a composite material structure.

[0055] Given that the resin matrix of resin-based composite rotating body products varies, this application does not impose too many restrictions on the specific type of resin, but only uses individual resins as examples, such as epoxy resin, polyethylene resin, ABS resin, etc.

[0056] Correspondingly, the curing and molding process can adopt the VARI molding process, hot pressing molding process, and OOA molding process commonly used in the prior art. Since these are all conventional molding processes for existing resin-based composite materials, this application will not elaborate on them.

[0057] To ensure the dimensional accuracy of the composite material rotating body product, before demolding in step S7, the composite material structure can be placed on a machine tool and precision machined according to the product's dimensional requirements. This ensures the dimensional accuracy of the product and, due to the supporting role of the molding die inside the composite material structure, avoids unnecessary deformation of the composite material structure during machining, thus helping to ensure the regularity of the product in terms of size and shape.

[0058] S7. Remove the resin putty, foaming material, and rigid frame inside the composite material structure to obtain the composite material rotating body with reinforcing ribs on the inner wall.

[0059] Therefore, based on the rigid platform 1 providing a benchmark for subsequent machine tool precision machining, this application constructs a rigid frame using the rigid platform 1 and rigid plate. A solid rigid core mold is formed by foaming and filling the rigid frame and applying a putty layer 5. This provides the foundation for the precision machining of the groove structure corresponding to the reinforcing ribs, and also enables the precise positioning of the reinforcing rib reinforced fabric layup 8, facilitating the laying operation of the reinforcing rib reinforced fabric layup 8 and ensuring the precision of the final product's linear shape. Simultaneously, thanks to the ability to set grooves on the outer surface of the core mold according to actual needs, the reinforcing rib reinforced fabric layup 8 and the main reinforcing fabric layup 9 are precisely positioned and synchronously integrated during the laying process. The fiber structures can be interlocked and superimposed, allowing the reinforcing rib reinforced fabric layup 8 and the main reinforcing fabric layup 9 to form an organic combination, improving the integration degree and structural strength of the reinforcing ribs and the main structure 12.

[0060] Furthermore, this application, through the aforementioned method, achieves integrated molding of the reinforcing ribs and the main structure 12 of the composite material rotary body, avoiding many problems associated with the existing process of separate manufacturing and reassembly, thus improving production efficiency and the overall structural strength of the product. On the other hand, the molding die (core mold) of this application can be easily removed after integrated molding, achieving efficient demolding of the composite material rotary body structure with complex reinforcing ribs. In short, this application can balance integrated molding of the reinforcing ribs and the main structure with effective overall demolding after molding, without being limited by the size of the composite material rotary body product, the shape and number of reinforcing ribs, and features high molding and demolding efficiency, good molding quality, low process risk, and strong process applicability.

[0061] The invention will be explained in more detail through the following examples. The purpose of disclosing the invention is to protect all variations and improvements within the scope of the invention. The invention is not limited to the following embodiments.

[0062] Example 1

[0063] As attached Figure 1-6 As shown, the composite material rotating body in this embodiment is an approximately conical epoxy resin-based carbon fiber composite material rotating body with circumferential reinforcing ribs 10 and longitudinal reinforcing ribs 11 on the inner wall of the main structure 12. The corresponding molding and demolding method is as follows:

[0064] S1. Use steel of a certain thickness (e.g., 30mm) as the reference platform, and reinforce its back to prevent deformation. Machining is used to form the machining and assembly reference surface. Use 10mm thick wooden boards. Based on the space dimensions corresponding to a 50mm inward offset from the product, cut each rigid board into shape. Assemble the machined boards onto the rigid platform 1 using snap-fit, bolt, or other methods to form a rigid frame. Refer to the attached diagram for the specific assembly structure. Figure 2 .

[0065] S2. Enclose the perimeter of the rigid frame and use high-density polyurethane foam to foam and fill the enclosed space. The ambient temperature of the foaming process should be controlled at 25±5℃ and the relative humidity should be <70%. After the foaming and filling is completed, let it stand naturally at room temperature for no less than 24 hours to form a polyurethane core mold. Use epoxy resin to fill the core mold in a vacuum environment and cure it at room temperature for no less than 24 hours.

[0066] S3. According to the final size requirements of the composite material rotating body product, grind the surface of the polyurethane core mold and ensure a grinding sinkage of 30mm. Then, use resin 725-R30: curing agent LPT: fumed silica: glass microspheres = 100:1.5:20:6 to prepare a paste-like resin putty at room temperature. Apply it evenly to the outer surface of the sanded core mold until the putty layer thickness is ≥40mm. Cure at room temperature for 24 hours.

[0067] S4. Based on the shape, size, and reinforcing rib position requirements of the composite material rotary body product, and according to the theoretical line shape corresponding to the composite material rotary body product, the outer surface of the core mold is machined to obtain the molding mold, and the outer surface of the molding mold is formed with circumferential grooves 6 and longitudinal grooves 7 that correspond one-to-one with the circumferential reinforcing ribs 10 and 11 respectively.

[0068] S5. Apply release paper to the outer surface of the molding die and inside the circumferential reinforcing ribs 10 and longitudinal reinforcing ribs 11, ensuring no wrinkles or overlaps. Then, lay carbon fiber fabric according to the requirements for laying the reinforcing fabric layer, forming the main reinforcing fabric layer 9 and the reinforcing rib reinforcing fabric layer 8 in terms of structure. In essence, the carbon fibers between the two can be intersected and superimposed, so that the two form an organic combination.

[0069] S6. The entire molding mold after the fabric layup is completed is sealed using a vacuum bag film. The vacuum level inside the bag film must be ≤-0.095MPa. Epoxy resin is injected into each reinforcing fabric layer through the pre-reserved injection port in the vacuum bag film, utilizing the pressure difference between the inside and outside of the film. After the carbon fiber is fully impregnated, the injection port is closed, and the temperature is maintained at 25℃±5℃ for at least 24 hours to form a composite material structure. It should be noted that to ensure airtight sealing, the ultimate vacuum level within the sealing area must be ≤-0.095MPa, and the pressure drop should be less than 0.005MPa within 5 minutes after the vacuum pump is turned off.

[0070] S7. After the curing in step S6 is completed, remove the resin putty, foaming material and rigid frame inside the composite material structure to obtain the composite material rotating body with reinforcing ribs on the inner wall.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A molding and demolding method for a composite material rotating body with reinforcing ribs on its inner wall, characterized in that, The method is an integral molding and demolding method for hollow rotating structures of resin-based composite materials with reinforcing ribs on the inner wall. The method includes: S1. A rigid frame is formed on a rigid platform (1) by building a rigid plate; S2. Enclose the rigid frame and fill the enclosed space with foam material until a solid core mold is formed. S3. Grind the surface of the core mold and apply resin putty evenly to the outer surface of the core mold after grinding until the putty layer (5) thickness is ≥40mm. Then cure it to form a structural reinforcement layer on the outer surface of the core mold. S4. Based on the theoretical profile of the composite material rotating body product, the outer surface of the core mold is machined to obtain the molding mold, and the outer surface of the molding mold has a groove corresponding to the reinforcing rib. S5. Attach release paper and lay reinforcing fiber fabric on the outer surface of the molding mold and inside the groove to form the main reinforcing fabric layup (9) and the reinforcing rib reinforcing fabric layup (8); the fiber structure of the reinforcing rib reinforcing fabric layup (8) and the fiber structure of the main reinforcing fabric layup (9) are intersected and superimposed. S6. Inject resin into each reinforcing fabric layup, and cure and form a composite material structure under the condition of full impregnation of reinforcing fiber fabric, so that the reinforcing rib reinforcing fabric layup (8) and the main reinforcing fabric layup (9) are formed in an integrated manner, realizing the integrated forming of the reinforcing rib and the main structure (12) of the composite material rotating body. S7. Remove the resin putty, foaming material, and rigid frame inside the composite material structure to obtain the composite material rotating body with reinforcing ribs on the inner wall; In step S2, after the foam filling and curing, the core mold is filled with resin in a vacuum environment and cured at room temperature for no less than 24 hours; in step S3, the resin putty includes a resin adhesive, a curing agent, fumed silica, and glass microspheres in a mass ratio of 100:(1.2~2):(10~30):(0~10); the resin adhesive includes at least one of epoxy resin adhesive and vinyl resin adhesive; the curing agent is LPT curing agent; the core mold cured in step S3 can withstand a pressure of no less than 0.06 MPa without collapsing or deforming.

2. The molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall according to claim 1, characterized in that, The rigid plate includes an annular rigid plate (2) and a longitudinal rigid plate (3), and the longitudinal rigid plate (3) is connected to the rigid platform (1) and each annular rigid plate (2) respectively.

3. The molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall according to claim 1, characterized in that, The rigid plates are connected to each other by at least one of riveting, snap-fitting, and fastener connection, and the rigid plates are connected to the rigid platform (1) by fasteners.

4. The molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall according to claim 1, characterized in that, In step S2, the foaming material includes at least one of polyurethane foaming material and epoxy resin foaming material.

5. The molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall according to claim 1, characterized in that, In step S2, the ambient temperature during the foaming and filling process is controlled at 25±5℃ and the relative humidity is <70%; after the foaming and filling is completed, it is left to stand naturally at room temperature for no less than 24 hours.

6. The molding and demolding method for a composite material rotating body with reinforcing ribs on the inner wall according to claim 1, characterized in that, In step S5, the reinforcing fiber fabric includes at least one fiber fabric selected from glass fiber, carbon fiber, carbon / glass hybrid fiber, plant fiber, basalt fiber, quartz fiber, Kevlar fiber, ultra-high molecular weight polyethylene fiber, and PBO fiber.

Images