Method for preparing epoxy resin composite material through vacuum-assisted resin transfer molding

Abstract

The invention discloses a method for preparing an epoxy resin composite material through vacuum-assisted resin transfer molding, and belongs to the technical field of composite material preparation. Comprising the following steps: cleaning a mold; preparing demolding cloth and a flow guide net; laying and stacking; resin introduction and collection pipeline connection; sealing detection; infiltrating and solidifying the fiber layer; and post-treatment: firstly removing the vacuum bag, then taking out the infiltrated and consolidated fiber laying layer, and then removing the upper and lower flow guide nets and the upper and lower demolding cloth to obtain the epoxy resin composite material. The mold has the advantages that the liquid epoxy resin introducing pipe and the resin collecting pipe are respectively arranged at the left end and the right end of the mold, so that the liquid epoxy resin can enter the bottom of the fiber laying layer serving as a fiber structure firstly, and the liquid epoxy resin can be prevented from leaving fibers too early, and dry spots can be fully inhibited.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material preparation, and particularly relates to a method for preparing epoxy resin composite material by vacuum assisted resin transfer molding. Background Art

[0002] Vacuum-assisted resin transfer modeling (VARTM) is a production process for composite materials using a single-sided mold. It offers advantages such as low production cost, flexible part shape, and high repeatability. The process involves first placing a release sheet slightly larger than the part size on the mold to prevent adhesion between the molded part and the mold and reduce surface roughness. Dry fiber reinforcement is then laid on a release sheet, and another layer of release sheet is used to cover the dry fibers to improve the surface quality of the workpiece. Finally, a flow guide fabric, often called a flow net due to its mesh structure, is placed on top. Its purpose is to utilize its unique mesh structure to generate surface tension and increase the flow rate of the liquid epoxy resin. After the layers are laid, the entire structure is sealed with a vacuum bag, leaving an inlet and outlet connected to the interior of the bag. The suction port is immersed in the liquid epoxy resin via a pipe, while the outlet is connected to a resin collector and a vacuum pump via a pipe. When the vacuum pump is activated, the liquid epoxy resin enters the vacuum bag under atmospheric pressure. Simultaneously, the pressure differential compacts the entire fiber structure. Once the liquid epoxy resin has fully infiltrated the fiber structure, it is heated until solidified and demolded to produce an epoxy resin composite material.

[0003] Although the above-mentioned VARTM has the aforementioned advantages, it has the following shortcomings: the liquid epoxy resin impregnation of dry fibers not only takes a long time, but is also prone to local dry spots, which greatly weakens the strength of the product. Although the viscosity of the liquid epoxy resin can be reduced by preheating the mold, and the flow rate of the liquid epoxy resin can be increased by using a guide mesh, due to the relatively poor permeability of dry fibers, when faced with thicker dry fiber materials, that is, heavier dry fiber materials, there will often be areas on the side close to the mold that are not fully impregnated with the liquid epoxy resin. After curing, these areas will form dry spots that reduce the mechanical properties of the product, reduce durability and environmental tolerance, and make the product unsafe. Therefore, the quality of the structure of the epoxy resin composite material prepared by VARTM depends to a large extent on whether the liquid epoxy resin can fully impregnate the dry fibers during the preparation process.

[0004] Existing preparation methods, taking into account the difficulty of liquid epoxy resin flowing through fibers and the uncertainty of the degree of impregnation at the bottom of the dry fibers due to the opaque mold, continue to impregnate the fibers with liquid epoxy resin for approximately 10-40 minutes after the liquid epoxy resin begins to flow from the outlet before curing to prevent or reduce dry spots. However, practice has shown that this measure does not completely prevent the formation of dry spots. Instead, it wastes liquid epoxy resin and prolongs the impregnation process, affecting the efficiency of epoxy resin composite preparation. In fact, because the formation mechanism of dry spots involves a complex process of coupled physical fields, simply extending the fiber impregnation time cannot fundamentally solve the problem.

[0005] Published Chinese patents contain technical information related to VARTM methods for preparing epoxy resin composite materials, such as CN112981694A, which recommends "VARTM process-enhanced materials and their preparation methods," and CN111941882A, which describes "VARTM process molding device and component preparation." However, these patents, while not exclusive, offer no technical insights into how to suppress dry spots. Given this, exploring effective technical measures to suppress dry spots is highly beneficial, and the technical solutions described below were developed within this context. Summary of the Invention

[0006] The task of the present invention is to provide a method for preparing epoxy resin composite materials by vacuum-assisted resin transfer molding, which helps to make liquid epoxy resin preferentially enter the bottom of the fiber structure and helps to prevent the liquid epoxy resin from leaving the fiber prematurely, thereby fully suppressing the generation of dry spots.

[0007] The task of the present invention is accomplished by providing a method for preparing an epoxy resin composite material by vacuum-assisted resin transfer molding, comprising the following steps: A) Mold cleaning: Clean the upward-facing surface of the mold with a tool and / or a cleaning agent, and apply mold release wax to the middle area of ​​the mold after cleaning to obtain a clean mold. A liquid epoxy resin introduction tube is provided at the left end of the mold, and a resin collection tube is provided at the right end; B) preparing a release cloth and a guide net. First, prepare a fiber layer, then cut the release cloth and guide net according to the size of the fiber layer. The release cloth includes a lower release cloth and an upper release cloth. The upper and lower release cloths have the same planar dimensions, and the extent to which the edges of the upper and lower release cloths protrude beyond the edges of the fiber layer is controlled. The guide net includes an upper guide net and a lower guide net. The planar dimensions of the upper guide net are the same as the planar dimensions of the fiber layer, and the left side of the lower guide net protrudes beyond the left side of the upper guide net, while the rest of the lower guide net is flush with the upper guide net. C) Laying: First, lay the lower guide net obtained in step B) in the middle of the cleaned mold described in step A). ​​Then, cover the lower guide net with the lower release cloth obtained in step B), aligning the lower release cloth with the center of the lower guide net. Next, cover the fiber layer obtained in step B) on the lower release cloth, with the front and back edges and right side edges of the fiber layer flush with the edges of the lower guide net. Then, lay the upper release cloth obtained in step B) on the fiber layer. Finally, cover the upper guide net obtained in step B) on the upper release cloth, with the edges of the upper guide net flush with the edges of the fiber layer. D) connecting resin introduction and collection pipelines: first, the right end of the liquid epoxy resin introduction tube described in step A) is inserted into the mold and the extent of insertion of the right end of the liquid epoxy resin introduction tube into the mold is controlled. The left end is connected to the feed control valve. A first connecting tube is used and one end of the liquid epoxy resin introduction tube is connected to the feed control valve, while the other end of the first connecting tube is immersed below the liquid level of the liquid epoxy resin. Then, the left end of the resin collection tube described in step A) is inserted into the mold and the extent of insertion of the left end of the resin collection tube into the mold is controlled. The right end is connected to the collection control valve. A second connecting tube is used and one end of the second connecting tube is connected to the collection control valve. The other end of the second connecting tube is connected to the feed port of the resin collector. The discharge port of the resin collector is connected to the third connecting tube via one end of the third connecting tube. The other end of the third connecting tube is connected to a vacuum pump. E) Sealing test: First, the mold, the upper and lower guide nets, the upper and lower release cloths, and the fiber layup located on the mold are sealed with a vacuum bag using sealing tape. A clearance hole is left in the vacuum bag for the liquid epoxy resin inlet pipe and the resin collection pipe described in step D) to pass through. The vacuum bag, the liquid epoxy resin inlet pipe, and the resin collection pipe are sealed at the clearance hole using the sealing tape. Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the vacuum bag. The vacuum pressure gauge on the vacuum pump indicates the vacuum level in the vacuum bag and confirms the vacuum level. A vacuum bag is formed from the vacuum bag. F) impregnating and consolidating the fiber layer. First, the vacuum bag described in step E) is tested for sealing by confirming the vacuum value. Then, the feed control valves described in steps D) and E) are opened, and liquid epoxy resin is introduced into the vacuum bag described in step E) through the first connecting pipe described in step D), the feed control valve, and the liquid epoxy resin introduction pipe. After confirming that the fiber layer described in step C) is impregnated and visually observing that the epoxy resin has flowed to the right edge of the fiber layer, the feed control valve, the collection control valve, and the vacuum pump are closed. Then, the mold described in step E) is heated, and the heating temperature and time are controlled to obtain an impregnated and consolidated fiber layer impregnated with liquid epoxy resin and consolidated by heating. G) Post-processing: first remove the vacuum bags described in steps E) and F), then take out the impregnated and consolidated fiber ply described in step F), and then remove the upper and lower guide nets and the upper and lower release cloths to obtain the epoxy resin composite material.

[0008] In a specific embodiment of the present invention, the tool in step A) is a scraper or a shovel, and the cleaning agent is a solvent-based cleaner, a non-aqueous cleaner, or a semi-aqueous cleaner. The solvent-based cleaner includes acetone, methyl ethyl ketone, or isopropyl alcohol. The non-aqueous cleaner is Chemdease 2306, and the semi-aqueous cleaner is Loctice 7063.

[0009] In another specific embodiment of the present invention, the release wax in step A) is Frekote 200-NC or Frelote 55.

[0010] In another specific embodiment of the present invention, the weight of the upper and lower guide nets in steps B), C) and G) is 80-200 g / m 2 , high-density polyethylene, polypropylene or nylon three-dimensional mesh with a pore size of less than 2mm, the upper and lower release cloths have a gram weight of 50-120g / m 2 Polyamide, polyester or polyurethane coated fabrics.

[0011] In another specific embodiment of the present invention, the controlling of the extent to which the peripheral edges of the upper and lower release cloths protrude beyond the peripheral edges of the fiber ply in step B) means that the peripheral edges of the upper and lower release cloths protrude beyond the peripheral edges of the fiber ply by 5-30 mm, and the extent to which the left side of the lower guide net protrudes beyond the left side of the upper guide net is less than 15 mm.

[0012] In another specific embodiment of the present invention, the first, second and third connecting tubes described in step D) are plastic tubes; the degree to which the right end of the liquid epoxy resin introduction tube is controlled to extend into the mold is controlled to be 10-50 mm, and the degree to which the left end of the resin collection tube is controlled to be inserted into the mold is controlled to be 10-50 mm.

[0013] In a more specific embodiment of the present invention, the liquid epoxy resin introduction tube and the resin collection tube described in steps A), D) and E) are all plastic tubes; the vacuum bag described in step E) is transparent or translucent and made of nylon, polyester or polyethylene film bag, and the confirmation of the vacuum degree refers to confirming that the vacuum degree inside the vacuum bag formed by the vacuum bag is (relatively) greater than -0.9 MPa.

[0014] In a further specific embodiment of the present invention, the fiber plies described in steps B), C), E) and F) are carbon fiber plies with a total thickness of 10 mm stacked from carbon fiber layers with a thickness of 0.625 mm, and the method for confirming that the fiber ply is impregnated in step F) is to determine the extent to which the upper surface of the fiber ply is covered by the liquid epoxy resin by visually observing through the vacuum bag described in step E).

[0015] In yet another specific embodiment of the present invention, the liquid epoxy resin described in steps A), D), E), and F) is a bisphenol F-type epoxy resin having a viscosity of 1800-5000 CPS (25° C.), and the heating temperature controlled in step F) is controlled to be 160-180° C., and the heating time controlled is controlled to be 120-150 minutes.

[0016] In yet another specific embodiment of the present invention, the molds in steps A), C), D), E) and F) are made of steel, aluminum, steel alloy or aluminum alloy.

[0017] The technical effect of the technical solution provided by the present invention is that: since the liquid epoxy resin introduction tube and the resin collection tube are respectively provided at the left and right ends of the mold, it helps to make the liquid epoxy resin first enter the bottom of the fiber layer serving as the fiber structure, thereby preventing the liquid epoxy resin from leaving the fibers too early and fully suppressing the generation of dry spots. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of an embodiment involved in the preparation process of the present invention. DETAILED DESCRIPTION

[0019] Example 1, see Figure 1 , relying on Figure 1 The method for preparing an epoxy resin composite material by vacuum assisted resin transfer molding includes the following steps: A) Cleaning the mold: Use a tool such as a scraper or shovel to clean the upward surface of the mold 1. After cleaning, apply mold release wax such as Frekote 200-NC to the middle area of ​​the mold 1 to obtain a cleaned mold 1. A liquid epoxy resin inlet tube 8 (the same below) made of plastic is installed at the left end of the mold 1, and a resin collection tube 9 (the same below) also made of plastic is installed at the right end. The liquid epoxy resin mentioned in this step and in steps D), E), and F) below is a bisphenol F-type epoxy resin with a viscosity of 1800-5000 CPS (25°C). The mold 1 described in this step and in steps C), D), E), and F) below is a steel mold. B) Prepare a release cloth and a guide net. First, prepare a fiber layer 4, and then cut the release cloth and guide net according to the size of the fiber layer 4. The release cloth includes a lower release cloth 3 and an upper release cloth 5. The upper and lower release cloths 5 and 3 have the same planar dimensions, and the degree to which the edges of the upper and lower release cloths 5 and 3 protrude from the edges of the fiber layer 4 is controlled to be 5 mm. The guide net includes an upper guide net 6 and a lower guide net 2. The planar dimensions of the upper guide net 6 are the same as the planar dimensions of the fiber layer 4, and the left side of the lower guide net 2 protrudes from the left side of the upper guide net 6 by 15 mm, and the rest is flush with the upper guide net 6. The gram weight of the upper and lower guide nets 6 and 2 described in this step and the following steps C) and G) is 80 g / m 2 , high-density polyethylene three-dimensional mesh with a pore size of less than 2mm, upper and lower release cloths 5 and 3 have a gram weight of 100g / m 2 The polyamide coated cloth, the fiber ply 4 described in this step and the following steps C), E) and F) is a carbon fiber ply with a thickness of 0.625 mm stacked into a total thickness of 10 mm; C) Laying: First, lay the lower guide net 2 obtained in step B) in the middle of the cleaned mold 1 described in step A). ​​Then, cover the lower guide net 2 with the lower release cloth 3 obtained in step B), aligning the center of the lower release cloth 3 with the lower guide net 2. Next, cover the fiber layer 4 obtained in step B) with the lower release cloth 3 obtained in step B), with the front and back edges and right side edges of the fiber layer 4 flush with the edges of the lower guide net 2. Then, lay the upper release cloth 5 obtained in step B) on the fiber layer 4. Finally, cover the upper guide net 6 obtained in step B) on the upper release cloth 5, with the edges of the upper guide net 6 flush with the edges of the fiber layer 4. D) Connecting the resin introduction and collection pipelines: first, insert the right end of the liquid epoxy resin introduction tube 8 described in step A) into the mold 1 and control the right end of the liquid epoxy resin introduction tube 8 to extend into the mold 1 to 30 mm, and connect the left end to the feed control valve. Use a first connecting tube and connect one end of the liquid epoxy resin introduction tube 8 to the feed control valve, while immersing the other end of the first connecting tube below the liquid level of the liquid epoxy resin. Then, insert the left end of the resin collection tube 9 described in step A) into the mold 1 and control the left end of the resin collection tube 9 to extend into the mold 1 to 30 mm, and connect the right end to the collection control valve. Use a second connecting tube and connect one end of the second connecting tube to the collection control valve, and connect the other end of the second connecting tube to the feed port of the resin collector. The discharge port of the resin collector is connected to it through one end of a third connecting tube, and the other end of the third connecting tube is connected to the vacuum pump. E) Sealing test: First, a transparent or translucent nylon or polyethylene film bag 7 is used to seal the mold 1, the upper and lower guide nets 6, 2, the upper and lower release cloths 5, 3, and the fiber layer 4 located on the mold 1, using sealing tape. A clearance hole is left in the vacuum bag 7 for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 described in step D) to pass through. The vacuum bag is sealed with the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 at the clearance hole for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 using the sealing tape. Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the bag. The vacuum pressure gauge on the vacuum pump indicates the vacuum level in the vacuum bag and confirms the vacuum level. A vacuum bag is formed from the vacuum bag 7, and the vacuum level within the vacuum bag is (relatively) greater than -0.9 MPa. F) Wetting and consolidating the fiber layer: First, perform a seal test on the vacuum bag 7 described in step E) by confirming the vacuum value. Then, open the feed control valves described in steps D) and E) to allow liquid epoxy resin to enter the vacuum bag described in step E) through the first connecting pipe, feed control valve, and liquid epoxy resin introduction pipe 8 described in step D) in sequence. Confirm that the fiber layer 4 described in step C) is impregnated. After visually observing that the epoxy resin has flowed to the right edge of the fiber layer 4, close the feed control valve, collection control valve, and vacuum pump. Then, heat the mold 1 described in step E) at a controlled temperature of 170° C. and a controlled heating time of 135 minutes to obtain an impregnated and consolidated fiber layer impregnated with liquid epoxy resin and heated. In this step, confirming that the fiber layer 4 is impregnated is by visually observing the extent to which the upper surface of the fiber layer 4 is covered by the liquid epoxy resin through the vacuum bag described in step E). G) Post-processing: first remove the vacuum bag described in steps E) and F), then take out the impregnated and consolidated fiber layer described in step F), and then remove the upper and lower guide meshes 6, 2 and the upper and lower release cloths 5, 3 to obtain the epoxy resin composite material.

[0020] Example 2, see Figure 1 , relying on Figure 1 The method for preparing an epoxy resin composite material by vacuum assisted resin transfer molding includes the following steps: A) Mold cleaning: Use acetone or methyl ethyl ketone to clean the upward side of the mold 1. After cleaning, apply mold release wax, such as Frelote 55, to the central area of ​​the mold 1 to obtain a clean mold 1. A liquid epoxy resin inlet tube 8 (the same below) made of plastic is provided at the left end of the mold 1, and a resin collection tube 9 (the same below) also made of plastic is provided at the right end. The liquid epoxy resin mentioned in this step and in steps D), E), and F) below is a bisphenol F-type epoxy resin with a viscosity of 1800-5000 CPS (25°C). The mold 1 described in this step and in steps C), D), E), and F) below is an aluminum mold. B) Prepare a release cloth and a guide net. First, prepare a fiber layer 4, and then cut the release cloth and guide net according to the size of the fiber layer 4. The release cloth includes a lower release cloth 3 and an upper release cloth 5. The upper and lower release cloths 5 and 3 have the same planar dimensions, and the degree to which the edges of the upper and lower release cloths 5 and 3 protrude from the edges of the fiber layer 4 is controlled to be 5 mm. The guide net includes an upper guide net 6 and a lower guide net 2. The planar dimensions of the upper guide net 6 are the same as the planar dimensions of the fiber layer 4, and the left side of the lower guide net 2 protrudes from the left side of the upper guide net 6 by 1 mm, and the rest is flush with the upper guide net 6. The gram weight of the upper and lower guide nets 6 and 2 described in this step and the following steps C) and G) is 120 g / m 2 , polypropylene three-dimensional mesh with a pore size of less than 2mm, upper and lower release cloths 5 and 3 are 50g / m 2 The polyester coated cloth, the fiber ply 4 in this step and the following steps C), E) and F) is a carbon fiber ply with a thickness of 0.625 mm stacked into a total thickness of 10 mm; C) Laying: First, lay the lower guide net 2 obtained in step B) in the middle of the cleaned mold 1 described in step A). ​​Then, cover the lower guide net 2 with the lower release cloth 3 obtained in step B), aligning the center of the lower release cloth 3 with the lower guide net 2. Next, cover the fiber layer 4 obtained in step B) with the lower release cloth 3 obtained in step B), with the front and back edges and right side edges of the fiber layer 4 flush with the edges of the lower guide net 2. Then, lay the upper release cloth 5 obtained in step B) on the fiber layer 4. Finally, cover the upper guide net 6 obtained in step B) on the upper release cloth 5, with the edges of the upper guide net 6 flush with the edges of the fiber layer 4. D) Connecting the resin introduction and collection pipelines: first, insert the right end of the liquid epoxy resin introduction tube 8 described in step A) into the mold 1 and control the right end of the liquid epoxy resin introduction tube 8 to extend into the mold 1 to a depth of 40 mm. The left end is connected to the feed control valve. A first connecting tube is used and one end of the liquid epoxy resin introduction tube 8 is connected to the feed control valve, while the other end of the first connecting tube is immersed below the liquid level of the liquid epoxy resin. Then, insert the left end of the resin collection tube 9 described in step A) into the mold 1 and control the left end of the resin collection tube 9 to extend into the mold 1 to a depth of 40 mm. The right end is connected to the collection control valve. A second connecting tube is used and one end of the second connecting tube is connected to the collection control valve. The other end of the second connecting tube is connected to the feed port of the resin collector. The discharge port of the resin collector is connected to it through one end of a third connecting tube. The other end of the third connecting tube is connected to a vacuum pump. E) Sealing test: First, a transparent or translucent nylon or polyethylene film bag 7 is used to seal the mold 1, the upper and lower guide nets 6, 2, the upper and lower release cloths 5, 3, and the fiber layer 4 located on the mold 1, using sealing tape. A clearance hole is left in the vacuum bag 7 for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 described in step D) to pass through. The vacuum bag is sealed with the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 at the clearance hole for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 using the sealing tape. Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the bag. The vacuum pressure gauge on the vacuum pump indicates the vacuum level in the vacuum bag and confirms the vacuum level. A vacuum bag is formed from the vacuum bag 7, and the vacuum level within the vacuum bag is (relatively) greater than -0.9 MPa. F) Wetting and consolidating the fiber layer: First, the vacuum bag 7 described in step E) is sealed and tested by confirming the vacuum value. Then, the feed control valves described in steps D) and E) are opened, and liquid epoxy resin is sequentially introduced into the vacuum bag described in step E) through the first connecting pipe, the feed control valve, and the liquid epoxy resin introduction pipe 8 described in step D). After confirming that the fiber layer 4 described in step C) is wetted, and after visually observing that the epoxy resin has flowed to the right edge of the fiber layer 4, the feed control valve, the collection control valve, and the vacuum pump are closed. Then, the mold 1 described in step E) is heated at a controlled temperature of 160° C. and a controlled heating time of 150 minutes to obtain an wetted and consolidated fiber layer impregnated with liquid epoxy resin and heated. In this step, wetted fiber layer 4 is confirmed by visually observing the extent of coverage of the upper surface of the fiber layer 4 by liquid epoxy resin through the vacuum bag described in step E). G) Post-processing: first remove the vacuum bag described in steps E) and F), then take out the impregnated and consolidated fiber layer described in step F), and then remove the upper and lower guide meshes 6, 2 and the upper and lower release cloths 5, 3 to obtain the epoxy resin composite material.

[0021] Example 3, see Figure 1 , relying on Figure 1 The method for preparing an epoxy resin composite material by vacuum assisted resin transfer molding includes the following steps: A) Mold cleaning: Use Chemdease 2306 to clean the upward side of the mold 1. After cleaning, apply mold release wax such as Frelote 55 to the middle area of ​​the mold 1 to obtain a clean mold 1. A liquid epoxy resin inlet tube 8 (hereinafter the same) made of plastic is provided at the left end of the mold 1, and a resin collection tube 9 (hereinafter the same) also made of plastic is provided at the right end. The liquid epoxy resin mentioned in this step and in steps D), E), and F) below is a bisphenol F-type epoxy resin with a viscosity of 1800-5000 CPS (25°C). The mold 1 described in this step and in steps C), D), E), and F) below is a steel alloy mold. B) Prepare a release cloth and a guide net. First, prepare a fiber layer 4, and then cut the release cloth and guide net according to the size of the fiber layer 4. The release cloth includes a lower release cloth 3 and an upper release cloth 5. The upper and lower release cloths 5 and 3 have the same planar dimensions, and the degree to which the edges of the upper and lower release cloths 5 and 3 protrude from the edges of the fiber layer 4 is controlled to be 5 mm. The guide net includes an upper guide net 6 and a lower guide net 2. The planar dimensions of the upper guide net 6 are the same as the planar dimensions of the fiber layer 4, and the left side of the lower guide net 2 protrudes from the left side of the upper guide net 6 by 5 mm, and the rest is flush with the upper guide net 6. The gram weight of the upper and lower guide nets 6 and 2 described in this step and the following steps C) and G) is 200 g / m 2 , nylon three-dimensional mesh with a pore size of less than 2mm, upper and lower release cloth 5, 3 with a gram weight of 120g / m 2 The polyurethane coated cloth, the fiber ply 4 in this step and the following steps C), E) and F) is a carbon fiber ply with a thickness of 0.625 mm stacked into a total thickness of 10 mm; C) Laying: First, lay the lower guide net 2 obtained in step B) in the middle of the cleaned mold 1 described in step A). ​​Then, cover the lower guide net 2 with the lower release cloth 3 obtained in step B), aligning the center of the lower release cloth 3 with the lower guide net 2. Next, cover the fiber layer 4 obtained in step B) with the lower release cloth 3 obtained in step B), with the front and back edges and right side edges of the fiber layer 4 flush with the edges of the lower guide net 2. Then, lay the upper release cloth 5 obtained in step B) on the fiber layer 4. Finally, cover the upper guide net 6 obtained in step B) on the upper release cloth 5, with the edges of the upper guide net 6 flush with the edges of the fiber layer 4. D) Connecting the resin introduction and collection pipelines: first, insert the right end of the liquid epoxy resin introduction tube 8 described in step A) into the mold 1 and control the right end of the liquid epoxy resin introduction tube 8 to extend into the mold 1 to 50 mm, and connect the left end to the feed control valve. Use a first connecting tube and connect one end of the liquid epoxy resin introduction tube 8 to the feed control valve, while immersing the other end of the first connecting tube below the liquid level of the liquid epoxy resin. Then, insert the left end of the resin collection tube 9 described in step A) into the mold 1 and control the left end of the resin collection tube 9 to extend into the mold 1 to 50 mm, and connect the right end to the collection control valve. Use a second connecting tube and connect one end of the second connecting tube to the collection control valve, and connect the other end of the second connecting tube to the feed port of the resin collector. The discharge port of the resin collector is connected to it through one end of a third connecting tube, and the other end of the third connecting tube is connected to the vacuum pump. E) Sealing test: First, a transparent or translucent nylon or polyethylene film bag 7 is used to seal the mold 1, the upper and lower guide nets 6, 2, the upper and lower release cloths 5, 3, and the fiber layer 4 located on the mold 1, using sealing tape. A clearance hole is left in the vacuum bag 7 for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 described in step D) to pass through. The vacuum bag is sealed with the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 at the clearance hole for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 using the sealing tape. Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the bag. The vacuum pressure gauge on the vacuum pump indicates the vacuum level in the vacuum bag and confirms the vacuum level. A vacuum bag is formed from the vacuum bag 7, and the vacuum level within the vacuum bag is (relatively) greater than -0.9 MPa. F) Wetting and consolidating the fiber layer: First, perform a seal test on the vacuum bag 7 described in step E) by confirming the vacuum value. Then, open the feed control valves described in steps D) and E) to allow liquid epoxy resin to enter the vacuum bag described in step E) through the first connecting pipe, feed control valve, and liquid epoxy resin introduction pipe 8 described in step D) in sequence. Confirm that the fiber layer 4 described in step C) is wetted. After visually observing that the epoxy resin has flowed to the right edge of the fiber layer 4, close the feed control valve, collection control valve, and vacuum pump. Then, heat the mold 1 described in step E) at a controlled temperature of 180° C. and a controlled heating time of 120 minutes to obtain a wetted and consolidated fiber layer impregnated with liquid epoxy resin and heated. In this step, wetted fiber layer 4 is confirmed by visually observing the extent of coverage of the upper surface of the fiber layer 4 by liquid epoxy resin through the vacuum bag described in step E). G) Post-processing: first remove the vacuum bag described in steps E) and F), then take out the impregnated and consolidated fiber layer described in step F), and then remove the upper and lower guide meshes 6, 2 and the upper and lower release cloths 5, 3 to obtain the epoxy resin composite material.

[0022] Example 4, see Figure 1 , relying on Figure 1 The method for preparing an epoxy resin composite material by vacuum assisted resin transfer molding includes the following steps: A) Mold cleaning: Use Loctice 7063 to clean the upward side of the mold 1. After cleaning, apply mold release wax, such as Frelote 55, to the central area of ​​the mold 1 to obtain a clean mold 1. A liquid epoxy resin inlet tube 8 (hereinafter referred to as plastic) is provided at the left end of the mold 1, and a resin collection tube 9 (hereinafter referred to as plastic) is provided at the right end. The liquid epoxy resin mentioned in this step and in steps D), E), and F) below is a bisphenol F epoxy resin with a viscosity of 1800-5000 CPS (25°C). The mold 1 described in this step and in steps C), D), E), and F) below is an aluminum alloy mold. B) Prepare a release cloth and a guide net. First, prepare a fiber layer 4, and then cut the release cloth and guide net according to the size of the fiber layer 4. The release cloth includes a lower release cloth 3 and an upper release cloth 5. The upper and lower release cloths 5 and 3 have the same planar dimensions, and the degree to which the edges of the upper and lower release cloths 5 and 3 protrude from the edges of the fiber layer 4 is controlled to be 5 mm. The guide net includes an upper guide net 6 and a lower guide net 2. The planar dimensions of the upper guide net 6 are the same as the planar dimensions of the fiber layer 4, and the left side of the lower guide net 2 protrudes from the left side of the upper guide net 6 by 0.5 mm, and the rest is flush with the upper guide net 6. The gram weight of the upper and lower guide nets 6 and 2 described in this step and the following steps C) and G) is 140 g / m 2 , high-density polyethylene three-dimensional mesh with a pore size of less than 2mm, upper and lower release cloths 5 and 3 are 90g / m 2 The polyurethane coated cloth, the fiber ply 4 in this step and the following steps C), E) and F) is a carbon fiber ply with a thickness of 0.625 mm stacked into a total thickness of 10 mm; C) Laying: First, lay the lower guide net 2 obtained in step B) in the middle of the cleaned mold 1 described in step A). ​​Then, cover the lower guide net 2 with the lower release cloth 3 obtained in step B), aligning the center of the lower release cloth 3 with the lower guide net 2. Next, cover the fiber layer 4 obtained in step B) with the lower release cloth 3 obtained in step B), with the front and back edges and right side edges of the fiber layer 4 flush with the edges of the lower guide net 2. Then, lay the upper release cloth 5 obtained in step B) on the fiber layer 4. Finally, cover the upper guide net 6 obtained in step B) on the upper release cloth 5, with the edges of the upper guide net 6 flush with the edges of the fiber layer 4. D) Connecting the resin introduction and collection pipelines: first, insert the right end of the liquid epoxy resin introduction tube 8 described in step A) into the mold 1 and control the right end of the liquid epoxy resin introduction tube 8 to extend into the mold 1 to 20 mm, and connect the left end to the feed control valve. Use a first connecting tube and connect one end of the liquid epoxy resin introduction tube 8 to the feed control valve, while immersing the other end of the first connecting tube below the liquid level of the liquid epoxy resin. Then, insert the left end of the resin collection tube 9 described in step A) into the mold 1 and control the left end of the resin collection tube 9 to extend into the mold 1 to 20 mm, and connect the right end to the collection control valve. Use a second connecting tube and connect one end of the second connecting tube to the collection control valve, and connect the other end of the second connecting tube to the feed port of the resin collector. The discharge port of the resin collector is connected to it through one end of a third connecting tube, and the other end of the third connecting tube is connected to the vacuum pump. E) Sealing test: First, a transparent or translucent nylon or polyethylene film bag 7 is used to seal the mold 1, the upper and lower guide nets 6, 2, the upper and lower release cloths 5, 3, and the fiber layer 4 located on the mold 1, using sealing tape. A clearance hole is left in the vacuum bag 7 for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 described in step D) to pass through. The vacuum bag is sealed with the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 at the clearance hole for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 using the sealing tape. Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the bag. The vacuum pressure gauge on the vacuum pump indicates the vacuum level in the vacuum bag and confirms the vacuum level. A vacuum bag is formed from the vacuum bag 7, and the vacuum level within the vacuum bag is (relatively) greater than -0.9 MPa. F) Wetting and consolidating the fiber layer: First, perform a seal test on the vacuum bag 7 described in step E) by confirming the vacuum value. Then, open the feed control valves described in steps D) and E) to allow liquid epoxy resin to enter the vacuum bag described in step E) through the first connecting pipe, feed control valve, and liquid epoxy resin introduction pipe 8 described in step D) in sequence. Confirm that the fiber layer 4 described in step C) is wetted. After visually observing that the epoxy resin has flowed to the right edge of the fiber layer 4, close the feed control valve, collection control valve, and vacuum pump. Then, heat the mold 1 described in step E) at a controlled temperature of 175° C. and a controlled heating time of 140 minutes to obtain a wetted and consolidated fiber layer impregnated with liquid epoxy resin and heated. In this step, wetted fiber layer 4 is confirmed by visually observing the extent of coverage of the upper surface of the fiber layer 4 by liquid epoxy resin through the vacuum bag described in step E). G) Post-processing: first remove the vacuum bag described in steps E) and F), then take out the impregnated and consolidated fiber layer described in step F), and then remove the upper and lower guide meshes 6, 2 and the upper and lower release cloths 5, 3 to obtain the epoxy resin composite material.

[0023] Example 5, see Figure 1 , relying on Figure 1 The method for preparing an epoxy resin composite material by vacuum assisted resin transfer molding includes the following steps: A) Mold cleaning: First, clean the upward surface of the mold 1 with a scraper and then with isopropyl alcohol. After cleaning, apply mold release wax, such as Frekote 200-NC, to the central area of ​​the mold 1 to obtain a cleaned mold 1. A liquid epoxy resin inlet tube 8 (hereinafter the same) made of plastic is provided at the left end of the mold 1, and a resin collection tube 9 (hereinafter the same) also made of plastic is provided at the right end. The liquid epoxy resin mentioned in this step and in steps D), E), and F) below is a bisphenol F-type epoxy resin with a viscosity of 1800-5000 CPS (25°C). The mold 1 described in this step and in steps C), D), E), and F) below is an aluminum alloy mold. B) Prepare a release cloth and a guide net. First, prepare a fiber layer 4, and then cut the release cloth and guide net according to the size of the fiber layer 4. The release cloth includes a lower release cloth 3 and an upper release cloth 5. The upper and lower release cloths 5 and 3 have the same planar dimensions, and the degree to which the edges of the upper and lower release cloths 5 and 3 protrude from the edges of the fiber layer 4 is controlled to be 5 mm. The guide net includes an upper guide net 6 and a lower guide net 2. The planar dimensions of the upper guide net 6 are the same as the planar dimensions of the fiber layer 4, and the left side of the lower guide net 2 protrudes from the left side of the upper guide net 6 by 12 mm, and the rest is flush with the upper guide net 6. The gram weight of the upper and lower guide nets 6 and 2 described in this step and the following steps C) and G) is 160 g / m 2 , high-density polyethylene three-dimensional mesh with a pore size of less than 2mm, upper and lower release cloths 5 and 3 are 110g / m 2 The polyurethane coated cloth, the fiber ply 4 in this step and the following steps C), E) and F) is a carbon fiber ply with a thickness of 0.625 mm stacked into a total thickness of 10 mm; C) Laying: First, lay the lower guide net 2 obtained in step B) in the middle of the cleaned mold 1 described in step A). ​​Then, cover the lower guide net 2 with the lower release cloth 3 obtained in step B), aligning the center of the lower release cloth 3 with the lower guide net 2. Next, cover the fiber layer 4 obtained in step B) with the lower release cloth 3 obtained in step B), with the front and back edges and right side edges of the fiber layer 4 flush with the edges of the lower guide net 2. Then, lay the upper release cloth 5 obtained in step B) on the fiber layer 4. Finally, cover the upper guide net 6 obtained in step B) on the upper release cloth 5, with the edges of the upper guide net 6 flush with the edges of the fiber layer 4. D) Connecting the resin introduction and collection pipelines: first, insert the right end of the liquid epoxy resin introduction tube 8 described in step A) into the mold 1 and control the right end of the liquid epoxy resin introduction tube 8 to extend into the mold 1 to a depth of 10 mm. The left end is connected to the feed control valve. A first connecting tube is used and one end of the liquid epoxy resin introduction tube 8 is connected to the feed control valve, while the other end of the first connecting tube is immersed below the liquid level of the liquid epoxy resin. Then, insert the left end of the resin collection tube 9 described in step A) into the mold 1 and control the left end of the resin collection tube 9 to extend into the mold 1 to a depth of 10 mm. The right end is connected to the collection control valve. A second connecting tube is used and one end of the second connecting tube is connected to the collection control valve. The other end of the second connecting tube is connected to the feed port of the resin collector. The discharge port of the resin collector is connected to it through one end of a third connecting tube. The other end of the third connecting tube is connected to a vacuum pump. E) Sealing test: First, a transparent or translucent nylon or polyethylene film bag 7 is used to seal the mold 1, the upper and lower guide nets 6, 2, the upper and lower release cloths 5, 3, and the fiber layer 4 located on the mold 1, using sealing tape. A clearance hole is left in the vacuum bag 7 for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 described in step D) to pass through. The vacuum bag is sealed with the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 at the clearance hole for the liquid epoxy resin introduction pipe 8 and the resin collection pipe 9 using the sealing tape. Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the bag. The vacuum pressure gauge on the vacuum pump indicates the vacuum level in the vacuum bag and confirms the vacuum level. A vacuum bag is formed from the vacuum bag 7, and the vacuum level within the vacuum bag is (relatively) greater than -0.9 MPa. F) Wetting and consolidating the fiber layer: First, the vacuum bag 7 described in step E) is sealed and tested by confirming the vacuum value. Then, the feed control valves described in steps D) and E) are opened, and liquid epoxy resin is introduced into the vacuum bag described in step E) through the first connecting pipe, the feed control valve, and the liquid epoxy resin introduction pipe 8 described in step D) in sequence. After confirming that the fiber layer 4 described in step C) is wetted, and after visually observing that the epoxy resin has flowed to the right edge of the fiber layer 4, the feed control valve, the collection control valve, and the vacuum pump are closed. Then, the mold 1 described in step E) is heated at a controlled temperature of 165° C. and a controlled heating time of 145 minutes to obtain a wetted and consolidated fiber layer impregnated with liquid epoxy resin and heated. In this step, wetted fiber layer 4 is confirmed by visually observing the extent of coverage of the upper surface of the fiber layer 4 by liquid epoxy resin through the vacuum bag described in step E). G) Post-processing: first remove the vacuum bag described in steps E) and F), then take out the impregnated and consolidated fiber layer described in step F), and then remove the upper and lower guide meshes 6, 2 and the upper and lower release cloths 5, 3 to obtain the epoxy resin composite material.

[0024] From the above examples 1 to 5, it can be seen that the present invention adds a layer of guide net between the mold and the bottom release cloth to improve the flow of liquid epoxy resin on the side of the dry fiber close to the mold, such as Figure 1 As shown. The size of the newly added guide cloth depends on the size of the dry fiber material. At the inlet end close to the liquid epoxy resin, the guide net should extend out of the fiber structure by less than 10mm. This is because the fibers close to the mold side are more difficult to be infiltrated by liquid epoxy resin than the top. Therefore, when the guide net protrudes from the carbon fiber structure, the epoxy resin will preferentially enter the bottom of the fiber structure. If the extension distance is too long, it will affect the flow of liquid epoxy resin at the top of the fiber, thereby forming a dry spot at the top of the fiber structure. In the directions of the other sides, the guide net should be level with the fiber structure or slightly shorter than the fiber structure to prevent the liquid epoxy resin from leaving the fiber too early and forming a dry spot inside.

[0025] In the fiber layup 4 of the present invention, liquid epoxy resin penetrates the fiber structure through two channels, the bottom and the top. This significantly reduces the likelihood of areas within the fiber structure not being fully wetted by the liquid resin. It's important to note that because the mid-bottom flow guide mesh slightly protrudes from the fiber layup 4, the liquid resin preferentially enters the bottom of the fiber structure rather than the top. The bottom of the fiber is precisely where dry spots are most likely to occur. Therefore, using the layup of the present invention effectively reduces the occurrence of dry spots. In actual operation, when the top of the fiber is observed to be fully wetted by liquid epoxy resin through the vacuum bag 7, the bottom of the fiber structure is inevitably fully wetted as well. Therefore, once the top of the fiber is completely covered by the liquid, heating and curing can begin. However, using conventional layup processes requires a longer wait time to avoid dry spots at the bottom of the structure. Experiments have shown that using the new layup process to prepare a 16-layer dry carbon fiber layup with a side length of 300 mm x 300 mm and a total thickness of 10 mm requires only 25 minutes on average to complete the impregnation stage, compared to 40 minutes using conventional layups, a 37.5% reduction in production cycle time. Despite the significantly reduced wetting time, all samples showed no dry spots on the bottom after demolding. Mechanical tensile testing also confirmed no dry spots within the samples. Samples were cut into strips for tensile testing. If dry spots were present, the test sample would break at the location and the material strength would be lower than normal. Tensile tests confirmed that the strength values ​​of samples prepared using the new layup were consistent with those of samples prepared using the traditional process, confirming the absence of dry spots within the samples.

Claims

1. A method for preparing epoxy resin composite materials by vacuum-assisted resin transfer molding, characterized in that: The steps include: A) cleaning the mold, using a tool and / or a cleaning agent to clean the upward side surface of the mold (1), and after cleaning, applying mold release wax to the middle area of ​​the mold (1) to obtain a cleaned mold (1), and providing a liquid epoxy resin introduction tube (8) at the left end of the mold (1) and a resin collection tube (9) at the right end; B) preparing a release cloth and a guide net, first preparing a fiber layer (4), and then cutting the release cloth and the guide net according to the size of the fiber layer (4), the release cloth includes a lower release cloth (3) and an upper release cloth (5), the upper and lower release cloths (5) and (3) have the same plane size and control the extent to which the edges of the upper and lower release cloths (5) and (3) protrude from the edges of the fiber layer (4), the guide net includes an upper guide net (6) and a lower guide net (2), the plane size of the upper guide net (6) is the same as the plane size of the fiber layer (4), and the left side of the lower guide net (2) protrudes from the left side of the upper guide net (6), and the rest is flush with the upper guide net (6); C) Laying down, first laying down the lower guide net (2) obtained in step B) in the middle of the cleaned mold (1) described in step A), then covering the lower demoulding cloth (3) obtained in step B) on the lower guide net (2), and aligning the lower demoulding cloth (3) with the center of the lower guide net (2), then covering the fiber layer (4) obtained in step B) on the lower demoulding cloth (3) obtained in step B), with the front and rear and right edges of the fiber layer (4) flush with the edges of the lower guide net (2), then laying down the upper demoulding cloth (5) obtained in step B) on the fiber layer (4), and finally covering the upper guide net (6) obtained in step B) on the upper demoulding cloth (5), with the edges of the upper guide net (6) flush with the edges of the fiber layer (4); D) Resin introduction and collection pipeline connection, first, the right end of the liquid epoxy resin introduction pipe (8) described in step A) is inserted into the mold (1) and the degree of the right end of the liquid epoxy resin introduction pipe (8) inserted into the mold (1) is controlled, and the left end is connected to the feed control valve, a first connecting pipe is used and one end of the liquid epoxy resin introduction pipe (8) is connected to the feed control valve, and the other end of the first connecting pipe is immersed below the liquid level of the liquid epoxy resin, and then the left end of the resin collection pipe (9) described in step A) is inserted into the mold (1) and the degree of the left end of the resin collection pipe (9) inserted into the mold (1) is controlled, and the right end is connected to the collection control valve, a second connecting pipe is used and one end of the second connecting pipe is connected to the collection control valve, and the other end of the second connecting pipe is connected to the feed port of the resin collector, and the discharge port of the resin collector is connected to it through one end of a third connecting pipe, and the other end of the third connecting pipe is connected to the vacuum pump; E) Sealing test: first, the mold (1) and the upper and lower guide nets (6, 2), the upper and lower demoulding cloths (5, 3) and the fiber layer (4) on the mold (1) are sealed with a vacuum bag (7) by means of a sealing tape, and a clearance hole for the liquid epoxy resin introduction pipe (8) and the resin collection pipe (9) described in step D) is left on the vacuum bag (7). The sealing tape is used to seal the vacuum bag, the liquid epoxy resin introduction pipe (8) and the resin collection pipe (9) at the clearance hole for the liquid epoxy resin introduction pipe (8) and the resin collection pipe (9). Then, the feed control valve described in step D) is closed, the collection control valve is opened, and the vacuum pump described in step D) is turned on to evacuate the vacuum. The vacuum pressure gauge on the vacuum pump reveals the vacuum degree in the vacuum bag, and the vacuum degree is confirmed. A vacuum bag is formed by the vacuum bag (7); F) Wetting and consolidating the fiber layer, firstly, performing a sealing test on the vacuum bag (7) described in step E) by confirming the vacuum value, then opening the feed control valves described in steps D) and E), and allowing the liquid epoxy resin to enter the vacuum bag described in step E) through the first connecting pipe, the feed control valve, and the liquid epoxy resin introduction pipe (8) described in step D), confirming that the fiber ply (4) described in step C) is wetted, and visually observing that the epoxy resin flows to the right edge of the fiber ply (4), then closing the feed control valve, the collection control valve, and the vacuum pump, and then heating the mold (1) described in step E), and controlling the heating temperature and the heating time, to obtain an wetted and consolidated fiber ply that is wetted with the liquid epoxy resin and consolidated by heating; G) Post-processing: first remove the vacuum bag described in steps E) and F), then take out the impregnated and consolidated fiber layer described in step F), and then remove the upper and lower guide nets (6, 2) and the upper and lower release cloths (5, 3) to obtain the epoxy resin composite material.

2. The method for preparing epoxy resin composite materials by vacuum-assisted resin transfer molding according to claim 1, characterized in that: The tool in step A) is a scraper or a shovel, and the cleaning agent is a solvent-based cleaner, a non-aqueous cleaner, or a semi-aqueous cleaner. The solvent-based cleaner includes acetone, methyl ethyl ketone, or isopropyl alcohol. The non-aqueous cleaner is Chemdease 2306, and the semi-aqueous cleaner is Loctice 7063.

3. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 1, characterized in that: The release wax in step A) is Frekote 200-NC or Frelote 55.

4. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 1, characterized in that: The weight of the upper and lower guide nets 6 and 2 in steps B), C) and G) is 80-200 g / m 2 , high-density polyethylene, polypropylene or nylon three-dimensional mesh with a pore size of less than 2 mm, the upper and lower release cloths (5, 3) are 50-120 g / m 2 Polyamide, polyester or polyurethane coated fabrics.

5. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 4, characterized in that: The control of the extent to which the peripheral edges of the upper and lower release cloths (5, 3) protrude from the peripheral edges of the fiber ply 4 in step B) means that the peripheral edges of the upper and lower release cloths (5, 3) protrude from the peripheral edges of the fiber ply 4 by 5-30 mm, and the extent to which the left side of the lower guide net (2) protrudes from the left side of the upper guide net (6) is less than 15 mm.

6. The method for preparing epoxy resin composite materials by vacuum-assisted resin transfer molding according to claim 1, characterized in that: The first, second and third connecting tubes described in step D) are plastic tubes; the extent to which the right end of the liquid epoxy resin introduction tube (8) extends into the mold (1) is controlled to be 10-50 mm, and the extent to which the left end of the resin collection tube (9) is inserted into the mold (1) is controlled to be 10-50 mm.

7. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 1, characterized in that: The liquid epoxy resin introduction tube (8) and the resin collection tube (9) described in steps A), D) and E) are all plastic tubes; the vacuum bag (7) described in step E) is transparent or translucent and made of nylon, polyester or polyethylene film bag, and the confirmation of the vacuum degree refers to confirming that the vacuum degree inside the vacuum bag formed by the vacuum bag (7) is greater than -0.9 MPa.

8. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 1, characterized in that: The fiber ply (4) described in steps B), C), E) and F) is a carbon fiber ply with a total thickness of 10 mm stacked from carbon fiber layers with a thickness of 0.625 mm, and the method for confirming that the fiber ply (4) is wetted in step F) is to observe the extent to which the upper surface of the fiber ply (4) is covered by the liquid epoxy resin by visually observing through the vacuum bag described in step E).

9. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 1, characterized in that: The liquid epoxy resin described in steps A), D), E) and F) is a bisphenol F-type epoxy resin with a viscosity of 1800-5000 CPS (25°C), and the heating temperature controlled in step F) is controlled to be 160-180°C, and the heating time controlled is controlled to be 120-150 minutes.

10. The method for preparing epoxy resin composite materials by vacuum assisted resin transfer molding according to claim 1, characterized in that: The mold (1) in steps A), C), D), E) and F) is made of steel, aluminum, steel alloy or aluminum alloy.

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