RTM molding die and method for preparing resin composite materials from the RTM molding die

Abstract

An RTM molding die and a method for preparing resin composite materials from the RTM molding die belong to the field of composite material molding. It includes a lower die and an upper die. The lower die has a cavity and an O-ring groove on its upward-facing side, in which an O-ring is embedded. The upper die has inlet and outlet interfaces and an O-ring insertion groove on its downward-facing side. The key feature is that an inflation sealing ring groove is provided on the upward-facing side of the lower die, surrounding the outer side of the O-ring groove. An inflation sealing ring is placed within the inflation sealing ring groove, and the inflation sealing ring has an inflation / deflation nozzle corresponding to an inflation / deflation nozzle receiving cavity recessed on the upward-facing side of the lower die. An inflation sealing ring mating groove is provided on the downward-facing side of the upper die. The steps are: preliminary preparation; fiber laying; liquid epoxy resin injection; mold closing; and curing. Advantages: avoids dry spots on the resin composite material, ensures excellent stiffness and strength, and improves preparation efficiency.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding technology, specifically relating to an RTM molding die, and also to a method for preparing resin composite materials using the RTM molding die. Background Technology

[0002] The aforementioned RTM stands for "Resin Transfer Molding," and the resin mentioned above refers to epoxy resin. RTM is a method (also known as a "process") for molding epoxy resin-based composite materials using a closed mold. Specifically, an upper mold and a lower mold form a cavity, and a dry fiber layup is placed inside the cavity. Since the free height of the dry fiber layup is greater than the height of the cavity (i.e., the height of the cavity is less than the free height of the dry fiber layup), the dry fiber layup is under compression when the upper and lower molds are closed. This not only increases the fiber volume ratio of the molded resin composite material, improving its stiffness and strength, but also avoids defects such as delamination after molding.

[0003] In existing technology, the aforementioned upper and lower molds each have a recessed C-shaped or semi-circular groove on their opposite sides, forming a C-shaped cross-section. An O-ring is embedded in the semi-circular groove of the lower mold to prevent the liquid epoxy resin from spreading to the outside during resin injection and curing. After the upper and lower molds are closed, they are fixed with bolts. Then, liquid epoxy resin is injected into the cavity under pressure. During this stage, the previously laid dry fiber layers in the cavity are impregnated with the liquid epoxy resin, while excess liquid epoxy resin flows out from the outlet and is recycled. This process is crucial in determining the quality of the molded resin composite material. After the dry fibers are impregnated with the composite material, the entire mold is heated, increasing the curing speed of the epoxy resin. Ultimately, the liquid epoxy resin solidifies through a cross-linking reaction and fuses with the multilayer fibers to obtain the resin composite material, i.e., the epoxy resin composite material.

[0004] The resin composites prepared by the aforementioned RTM are widely used in the aerospace, automotive, and marine industries. Because they can produce various parts with smooth surface finishes without the need for prepregs, effectively reducing equipment and process costs, they have gained considerable popularity in recent years. Furthermore, since it is a closed-mold molding process, it avoids the health risks associated with liquid epoxy resins and significantly reduces environmental pollution.

[0005] In the process of molding resin composite materials using the aforementioned mold and process, whether the dry fibers are sufficiently impregnated with liquid epoxy resin determines the quality of the resin composite material (also known as the "part") after curing and demolding. Due to the high viscosity of epoxy resin, its penetration into the dry fiber layup within the mold cavity is relatively weak; that is, the flow rate of liquid epoxy resin in the dry fiber layup is relatively slow. If the dry fiber layup is thick, it is easy for localized areas of dry fibers to remain unimpregnated by the liquid epoxy resin, resulting in dry spots after curing, making the product defective and significantly weakening the rigidity and strength of the resin composite material. Furthermore, because the mold is opaque, it is difficult to determine whether the dry fiber layup has been sufficiently impregnated with liquid epoxy resin. The conventional practice is to continue the resin injection process for a period of time, such as 10-30 minutes, after the liquid epoxy resin begins to flow from the outlet. While this reduces the likelihood of dry spots, it leads to wasted liquid epoxy resin due to blind injection and makes the injection process lengthy, affecting molding efficiency. Summary of the Invention

[0006] The objective of this invention is to provide an RTM molding die that helps to provide ideal equipment conditions for eliminating dry spots, thereby ensuring that the prepared resin composite material has excellent stiffness and strength.

[0007] Another objective of this invention is to provide a method for preparing resin composite materials using an RTM molding die. This method has simple process steps and no demanding process elements, and can both avoid the occurrence of dry spots in the prepared resin composite materials and significantly improve the preparation efficiency.

[0008] The objective of this invention is achieved as follows: an RTM molding die includes a lower die and an upper die that mates with the lower die. The lower die has a cavity. A communicating O-ring groove is formed on the upward-facing surface of the lower die and around the cavity. An O-ring is embedded in the O-ring groove, with its upper part protruding from the groove. A set of lower die bolt holes are spaced apart on the lower die, and a bolt is disposed in each of these holes. An inlet port and an outlet port are provided on the upper die, each protruding from the upper surface of the upper die and communicating with the cavity, in a region corresponding to the cavity. An upper die bolt, equal in number to the set of lower die bolt holes, is disposed at the positions corresponding to the bolts on the upper die. The bolt passes through the bolt hole of the upper mold and extends to the top of the upper mold, and is equipped with a fixing nut. On the downward-facing side of the upper mold, at a position corresponding to the O-ring groove, an O-ring insertion groove is provided for the O-ring protruding from the O-ring groove to be inserted. The feature is that an inflation sealing ring groove is provided on the upward-facing side of the lower mold, at a position surrounding the outer side of the O-ring groove. An inflation sealing ring is provided in the inflation sealing ring groove. The inflation sealing ring has an inflation / deflation nozzle, which corresponds to an inflation / deflation nozzle receiving cavity recessed on the upward-facing side of the lower mold. On the downward-facing side of the upper mold, at a position corresponding to the inflation sealing ring groove, an inflation sealing ring mating groove is provided for mating with the inflation sealing ring.

[0009] In one specific embodiment of the present invention, the lower mold and the upper mold are made of metal material.

[0010] In another specific embodiment of the present invention, the metal material is steel, aluminum, copper, steel alloy, aluminum alloy, or copper alloy.

[0011] In another specific embodiment of the present invention, the inflatable sealing ring groove and the O-ring sealing ring groove are maintained at a distance of 10-20mm.

[0012] Another objective of the present invention is achieved by providing a method for preparing resin composite materials using an RTM molding die, comprising the following steps:

[0013] A) Preliminary preparation: First, equip an RTM molding die. This RTM molding die includes a lower die and an upper die that mates with the lower die. The lower die has a cavity. On the upward-facing surface of the lower die, surrounding the cavity, there is a communicating O-ring groove. An O-ring is embedded in the O-ring groove, with its upper part protruding out of the groove. A set of lower die bolt holes are spaced apart on the lower die, and a bolt is installed in each of these holes. On the upper die, corresponding to the cavity, there is an inlet port and an outlet port protruding from the upper surface of the upper die and communicating with the cavity. The upper die has an equal number of upper die bolt holes at the positions corresponding to the bolts, and the bolts pass through these upper die bolt holes. The upper mold is extended above the mold and equipped with a fixing nut. On the downward-facing side of the upper mold, at the position corresponding to the O-ring groove, an O-ring insertion groove is provided for the O-ring protruding from the O-ring groove to be inserted. On the upward-facing side of the lower mold, an inflation sealing ring groove is provided around the outer side of the O-ring groove. An inflation sealing ring is provided in the inflation sealing ring groove. The inflation sealing ring has an inflation / deflation nozzle, which corresponds to the inflation / deflation nozzle receiving cavity recessed on the upward-facing side of the lower mold. On the downward-facing side of the upper mold, at the position corresponding to the inflation sealing ring groove, an inflation sealing ring mating groove is provided for mating with the inflation sealing ring. The upper and lower molds are then cleaned, and release wax is applied to the mold cavity to obtain the mold.

[0014] B) Laying fibers: With the upper mold removed as described in step A), lay a dry fiber layer in the cavity of the lower mold described in step A). ​​After laying the dry fiber layer, first inflate the air sealing ring through the pipeline connected to the air inflation nozzle using an inflation device. Then, return the upper mold to the state where it engages with the lower mold. Due to the expansion of the air sealing ring, a non-closed space is formed between the opposing sides of the upper and lower molds. The sealing ring insertion groove and the O-ring seal are released from their sealing engagement. The upper and lower molds are sealed to each other by the air sealing ring through the sealing engagement between the air sealing ring engagement groove and the air sealing ring. With the upper mold floating upwards relative to the lower mold in the non-closed space, rotate the fixing nut to make the air sealing ring engagement groove of the upper mold fully seal with the air sealing ring.

[0015] C) Injecting liquid epoxy resin: First, connect one end of a liquid epoxy resin inlet tube to the inlet port described in step A), and connect the other end of the liquid epoxy resin inlet tube to the resin injection mechanism, which serves as the liquid epoxy resin supply source. Then, connect one end of a redundant liquid epoxy resin outlet tube to the outlet port described in step A), and connect the other end of the redundant liquid epoxy resin outlet tube to the resin collector. Next, put the resin injection mechanism into operation and inject liquid epoxy resin into the dry fiber layer through the liquid epoxy resin inlet tube and the inlet port to wet the dry fiber layer. When the liquid epoxy resin flows out from the outlet port, stop the resin injection mechanism. The liquid epoxy resin flowing out from the outlet port enters the resin collector through the redundant liquid epoxy resin outlet tube to obtain a liquid epoxy resin-impregnated part.

[0016] D) Mold closing: By operating the air inlet / outlet valves described in steps A) and B), the gas inside the air-filled sealing ring is discharged, causing the air-filled sealing ring to deflate. Under its own weight, the upper mold descends to a state where it is closed with the lower mold. In this closed state, the O-ring insert groove described in step A) mates with the O-ring groove, and the fixing nut described in step A) is tightened with a tool, so that the upper mold applies pressure to the liquid epoxy resin impregnated part obtained in step C) to increase the fiber volume ratio, thereby obtaining the liquid epoxy resin impregnated part.

[0017] E) Curing and molding: The upper and lower molds are heated to cure the liquid epoxy resin permeation part obtained in step D). After curing, the fixing nut described in step D) is unscrewed and the upper mold is removed from the mold cavity to obtain the resin composite material.

[0018] In another specific embodiment of the present invention, the cleaning process of the upper mold and the lower mold in step A) is performed by using tools or cleaning agents. The tool cleaning is performed by using a scraper or shovel; the cleaning agent cleaning is performed by using a solvent-based cleaning agent, such as acetone, methyl ethyl ketone or isopropylidene acetone.

[0019] In another specific embodiment of the present invention, the release wax mentioned in step A) is TR-102 or Stonermold release 8.

[0020] In a further specific embodiment of the present invention, the fibers constituting the dry fiber layer in step B) are carbon fibers, which have a tensile strength of 3000-7000 MPa, a tensile modulus of 200-600 GPa, a compressive strength of 1000-3000 MPa, an interlaminar shear strength of 50-150 MPa, a flexural strength of 1500-2500 MPa, and a density of 1.5-2.0 g / cm³.3 And the porosity is <1-2%.

[0021] In a further specific embodiment of the present invention, the liquid epoxy resin inlet pipe and the redundant liquid epoxy resin outlet pipe mentioned in step C) are both transparent PVC pipes.

[0022] The technical advantages of the present invention are as follows: Because an inflatable sealing ring groove is added to the lower mold of the RTM molding die structure system, and an inflatable sealing ring with an inflation / deflation nozzle is installed in the inflatable sealing ring groove, and a corresponding inflatable sealing ring mating groove is added to the upper mold to mate with the inflatable sealing ring, beneficial conditions are provided to eliminate dry spots by dividing the resin composite material preparation process into two stages: injection and extrusion. Because the preparation process is simple and does not involve harsh process elements, it can both avoid dry spots in the resin composite material, ensuring excellent stiffness and strength, and significantly improve preparation efficiency. Attached Figure Description

[0023] Figure 1 This is a structural diagram of the RTM molding die of the present invention;

[0024] Figure 2 This is a diagram showing the state of the upper and lower molds during the first stage of the resin composite material preparation process of this invention.

[0025] Figure 3 This is a diagram showing the state of the upper and lower molds in the second stage of the resin composite material preparation process of this invention. Detailed Implementation

[0026] Example 1: Please refer to Figures 1 to 3 ,Depend on Figure 1 The RTM molding die structure shown is based on Figure 2 and Figure 3 The illustrated method for preparing resin composite materials in two stages, injection and extrusion, includes the following steps:

[0027] A) Preliminary preparation: First, equip an RTM molding die, which includes a lower die 1 and an upper die 2 that mates with the lower die 1. The lower die 1 has a cavity 11. On the upward-facing surface of the lower die 1 and around the cavity 11, a communicating O-ring groove 12 is formed. An O-ring 121 is embedded in the O-ring groove 12, with the upper part of the O-ring 121 protruding from the O-ring groove 12. A set of lower die bolt holes 13 are provided on the lower die 1 at intervals, and a bolt 131 is installed in each of the lower die bolt holes 13. The upper die 2... Furthermore, in the area corresponding to the mold cavity 11, there is an inlet port 21 and an outlet port 22 that protrude from the upper surface of the upper mold 2 and communicate with the mold cavity 11. The upper mold 2 has an upper mold bolt hole 23 at the position corresponding to the bolt 131, the number of which is equal to the number of the set of lower mold bolt holes 13. The bolt 131 passes through the upper mold bolt hole 23, extends to the top of the upper mold 2, and is equipped with a fixing nut 1311. On the downward-facing side of the upper mold 2, at the position corresponding to the O-ring groove 12, there is an O-ring 121 for protruding from the O-ring groove 12. The O-ring insertion groove 24 is an improvement to the aforementioned RTM molding die. An inflation seal groove 14 is provided on the upward-facing side of the lower die 1, surrounding the O-ring groove 12. An inflation seal 141 is provided within this groove, and the inflation seal 141 has an inflation / deflation nozzle 1411. This nozzle 1411 corresponds to an inflation / deflation nozzle receiving cavity 15 recessed on the upward-facing side of the lower die 1. On the downward-facing side of the upper die 2, corresponding to the inflation seal groove 14, a sealing groove for inflation is provided. The inflatable sealing ring 141 mates with the groove 25 of the inflatable sealing ring. The opposing sides of the upper mold 2 and lower mold 1 are then cleaned with a scraper. TR-102 release wax, used as a release wax, is applied (or "applied") into the mold cavity 11 to obtain the mold. In this embodiment, the upper mold 2 and lower mold 1 are made of steel, such as stainless steel or mold steel. A 10mm gap is maintained between the inflatable sealing ring groove 14 and the O-ring groove 12. The O-ring 121 is a rubber ring, and the inflatable sealing ring 141 is a hollow rubber ring with an air cavity. Figure 1 As shown, since the upper mold 2 and the lower mold 1 are rectangular, there are four bolts 131 as mentioned above, which are distributed at the four corners of the lower mold 1.

[0028] B) Laying the fiber: With the upper mold 2 removed as described in step A), lay a dry fiber layer in the cavity 11 of the lower mold 1 described in step A). ​​After laying the dry fiber layer, first inflate the air sealing ring 141 through the pipeline connected to the air inflation nozzle 1411 using an inflation device. Then, return the upper mold 2 to the state where it engages with the lower mold 1. Due to the inflation of the air sealing ring 141, a non-closed space 4 is formed between the opposing sides of the upper mold 2 and the lower mold 1. Furthermore, the O-ring insertion groove 24 and the O-ring 121 are no longer sealed together, and the air sealing ring engagement groove 25 engages with the air sealing ring. The sealing fit of the upper mold 2 and lower mold 1, achieved by the inflatable sealing ring 141, keeps them sealed to each other. With the upper mold 2 floating upwards relative to the lower mold 1 in the non-closed space 4, rotating the fixing nut 1311 ensures a complete seal between the inflatable sealing ring groove 25 of the upper mold 2 and the inflatable sealing ring 141. The dry fiber layer in this step uses carbon fiber, which has a tensile strength of 3000 MPa, a tensile modulus of -600 GPa, a compressive strength of 1000 MPa, an interlaminar shear strength of 50 MPa, a flexural strength of 2500 MPa, and a density of 2 g / cm³. 3 And the porosity is <1%.

[0029] C) Injecting liquid epoxy resin: First, connect one end of a liquid epoxy resin inlet pipe 5 to the inlet port 21 described in step A), and connect the other end of the liquid epoxy resin inlet pipe 5 to the resin injection mechanism, which serves as the liquid epoxy resin supply source. Also, connect one end of a redundant liquid epoxy resin outlet pipe 6 to the outlet port 22 described in step A), and connect the other end of the redundant liquid epoxy resin outlet pipe 6 to the resin collector. Then, activate the resin injection mechanism to inject liquid epoxy resin sequentially through the liquid epoxy resin inlet pipe 5 and the inlet port 21 into the dry fiber layer to impregnate it. When the liquid epoxy resin flows out from the outlet port 22, stop the resin injection mechanism. The liquid epoxy resin flowing out from the outlet port 22 then enters the resin collector through the redundant liquid epoxy resin outlet pipe 6, resulting in the following... Figure 2 The liquid epoxy resin impregnated part 3, located in the mold cavity 11 and impregnated with liquid epoxy resin, is the injection molded part after liquid epoxy resin injection. In this step, both the liquid epoxy resin inlet pipe 5 and the redundant liquid epoxy resin outlet pipe 6 are transparent PVC. Therefore, this step is the first stage of the preparation process, which is the injection stage. The states of the upper mold 2 and lower mold 1 can be determined by… Figure 2 As shown;

[0030] D) Mold closing: By operating the inflation / deflation nozzle 1411 described in steps A) and B), the gas inside the inflation sealing ring 141 is discharged, causing the inflation sealing ring 141 to deflate. Under its own weight, the upper mold 2 descends to a state where it is closed with the lower mold 1. In this closed state, the O-ring insertion groove 24 described in step A) mates with the O-ring groove 12, and the fixing nut 1311 described in step A) is tightened with a tool, so that the upper mold 2 applies pressure to the liquid epoxy resin impregnated part 3 obtained in step C), thereby increasing the fiber volume ratio and obtaining the liquid epoxy resin impregnated part 7. Thus, this step is the second stage in the preparation process, which is the extrusion stage. The states of the upper mold 2 and the lower mold 1 can be determined by... Figure 3 As shown;

[0031] E) Curing and molding: The upper mold 2 and lower mold 1 are heated to cure the liquid epoxy resin permeated part 7 obtained in step D). After curing, the fixing nut 1311 described in step D) is unscrewed and the upper mold 2 is removed, and the part is taken out from the mold cavity 11 to obtain the resin composite material. Since there are many types of epoxy resins, the curing temperature and curing time vary depending on the physicochemical properties of the epoxy resin. However, since the curing temperature and curing time for different liquid epoxy resins are well-known technologies, they will not cause confusion for those skilled in the art. For example, the curing temperature of low-temperature curing epoxy resin is between room temperature and 80°C, and the curing time is 24 hours at room temperature or 1-4 hours at 60°C. Similarly, the curing temperature of medium-temperature curing epoxy resin is 80-120°C, and the curing time is 30-180 minutes. Furthermore, the curing temperature of high-temperature curing epoxy resin is 120-200°C (or even higher), and the curing time is 15-60 minutes. Therefore, in this embodiment, the applicant does not need to specifically limit the curing temperature and time.

[0032] Example 2: In step A), the materials of the upper mold 2 and lower mold 1 are changed to aluminum alloy; the cleaning treatment is changed to acetone; the release wax is changed to Stoner mold release 8; and the distance between the inflatable sealing ring groove 14 and the aforementioned O-ring sealing ring groove 12 is changed to 20mm. In step B), the strength of the carbon fiber is changed to 7000MPa, the tensile modulus to 200GPa, the compressive strength to 1500MPa, the interlaminar shear strength to 100MPa, the flexural strength to 1500MPa, and the density to 1.5g / cm³. 3 And the porosity was changed to <2%. Everything else is the same as the description of Example 1.

[0033] Example 3: In step A), the materials of the upper mold 2 and lower mold 1 were changed to copper alloy; the cleaning process was changed to methyl ethyl ketone cleaner; the release wax was changed to Stoner mold release 8; and the distance between the inflatable sealing ring groove 14 and the aforementioned O-ring sealing ring groove 12 was changed to 15mm. In step B), the carbon fiber strength was changed to 4500MPa, tensile modulus to 350GPa, compressive strength to 3000MPa, interlaminar shear strength to 75MPa, flexural strength to 2200MPa, and density to 2g / cm³. 3 And the porosity was changed to <1.5%. Everything else is the same as the description of Example 1.

[0034] Example 4: In step A), the materials of the upper mold 2 and lower mold 1 were changed to steel alloy; the cleaning process was changed to isopropylidene acetone cleaner; the release wax was changed to Stoner mold release 8; and the distance between the inflatable sealing ring groove 14 and the aforementioned O-ring sealing ring groove 12 was changed to 12mm. In step B), the strength of the carbon fiber was changed to 6000MPa, the tensile modulus to 450GPa, the compressive strength to 2000MPa, the interlaminar shear strength to 135MPa, the flexural strength to 1800MPa, and the density to 1.8g / cm³. 3 And the porosity was changed to <1.2%. Everything else is the same as the description of Example 1.

[0035] The beneficial effects of embodiments 1 to 4 of the present invention are reflected in two aspects: reducing the probability of dry spots and shortening the working time to improve production efficiency. During the injection stage, because the fibers are not excessively compressed, the fiber permeability is higher than in traditional processes, making it easier for liquid epoxy resin to fully wet its microstructure, thus reducing the likelihood of dry spots compared to traditional processes. Simultaneously, in the subsequent extrusion stage, due to the reduced volume of the mold cavity 11, excess liquid epoxy resin is squeezed and flows towards the fiber layup under the locking (i.e., containment) of the O-ring seal 121, eventually flowing out from the outlet, further reducing the likelihood of dry spots.

[0036] The improved production efficiency and shorter processing time of this invention are also attributed to the better permeability of the fiber during the injection stage using this mold. In traditional processes, due to the compression of the fiber layup, the permeability is low, resulting in a slower flow rate of liquid epoxy resin within the fiber. The liquid takes a longer time to flow through the fiber and exit the outlet, making it easier for dry spots to form inside the fiber that are not fully impregnated by the resin. To reduce the likelihood of dry spots, conventional practice is to extend the injection time by 10 to 30 minutes after the liquid exits the mold to ensure sufficient fiber impregnation. When using the mold structure of this invention, in the first stage (injection stage), the fiber has a higher permeability because it is not excessively compressed. Therefore, under the same environmental and part size conditions, the liquid epoxy resin enters the fiber structure more easily, and the time to exit the outlet is also shortened. When excess liquid epoxy resin flows out of the outlet, it is extruded in the second stage (extrusion stage). Due to the smaller cavity volume, the epoxy resin is forced to flow through the fiber to the outlet, further reducing the probability of dry spots. Therefore, after extrusion, mold heating and curing can begin directly without further injection. This will undoubtedly reduce the amount of epoxy resin used, reduce the waste of raw materials, and take less time to complete the same task, while also improving the production efficiency of resin composite materials.

Claims

1. A method for preparing resin composite materials using an RTM molding die, characterized in that: Includes the following steps: A) Preliminary preparation: First, an RTM molding die is prepared and cleaned. The RTM molding die includes a lower die (1) and an upper die (2) that cooperates with the lower die (1). The lower die (1) has a cavity (11). On the surface of the lower die (1) facing upward and around the cavity (11), a communicating O-ring groove (12) is formed. An O-ring (121) is embedded in the O-ring groove (12), and the upper part of the O-ring (121) protrudes out of the O-ring groove (12). On the upper die (2) and in the area corresponding to the cavity (11), there is an inlet port (21) and an outlet port (22) that protrude out of the upper surface of the upper die (2) and communicate with the cavity (11). On the side of the upper die (2) facing downward and in the area corresponding to the O-ring groove (12), there is an inlet port (21) and an outlet port (22) that protrude out of the upper surface of the upper die (2) and communicate with the cavity (11). An O-ring insertion groove (24) is provided for an O-ring (121) to be inserted into the O-ring groove (12). An inflation seal groove (14) is provided on the upward side of the lower mold (1) and on the outer side of the O-ring groove (12). An inflation seal (141) is provided in the inflation seal groove (14) and has an inflation / deflation nozzle (1411). The inflation / deflation nozzle (1411) corresponds to the inflation / deflation nozzle receiving cavity (15) recessed on the upward side of the lower mold (1). An inflation seal mating groove (25) is provided on the downward side of the upper mold (2) and at the position corresponding to the inflation seal groove (14) for mating with the inflation seal (141). A release wax is applied in the mold cavity (11) to obtain the mold. B) Laying the fiber: With the upper mold (2) removed as described in step A), lay a dry fiber layer in the cavity (11) of the lower mold (1) described in step A). ​​After laying the dry fiber layer, first inflate the air sealing ring (141) through the pipeline connected to the air inflation nozzle (1411) using an inflation device. Then return the upper mold (2) to the state of engaging with the lower mold (1). Due to the expansion of the air sealing ring (141), a non-closed space (4) is formed between the upper mold (2) and the lower mold (1) on opposite sides. The sealing ring insertion groove (24) and the O-ring seal (121) are released from sealing engagement. The upper mold (2) and the lower mold (1) are sealed to each other by the air seal ring (141) through the air seal ring mating groove (25). When the upper mold (2) is floating upward relative to the lower mold (1) in the non-closed space (4), the fixing nut (1311) is rotated to make the air seal ring mating groove (25) of the upper mold (2) and the air seal ring (141) form a full seal. C) Injecting liquid epoxy resin: First, insert one end of a liquid epoxy resin inlet tube (5) into the inlet port (21) described in step A), and connect the other end of the liquid epoxy resin inlet tube (5) to the resin injection mechanism, which serves as the liquid epoxy resin supply source. Then, insert one end of a redundant liquid epoxy resin outlet tube (6) into the outlet port (22) described in step A), and connect the other end of the redundant liquid epoxy resin outlet tube (6) to the resin collector. Next, allow the resin to... When the injection mechanism enters the working state, liquid epoxy resin is sequentially introduced into the dry fiber layer through the liquid epoxy resin inlet pipe (5) and the inlet port (21) to wet the dry fiber layer. When the liquid epoxy resin flows out from the outlet port (22), the resin injection mechanism stops working, and the liquid epoxy resin flowing out from the outlet port (22) enters the resin collector through the redundant liquid epoxy resin outlet pipe (6) to obtain the liquid epoxy resin impregnated part (3) that is wetted with liquid epoxy resin. D) Mold closing: By operating the inflation / deflation nozzle (1411) described in steps A) and B), the gas in the inflation sealing ring (141) is discharged, causing the inflation sealing ring (141) to deflate. Under the action of gravity, the upper mold (2) descends to the state of closing with the lower mold (1). In this state of closing, the O-ring insertion groove (24) described in step A) cooperates with the O-ring groove (12), so that the upper mold (2) applies pressure to the liquid epoxy resin impregnated part (3) obtained in step C) to increase the fiber volume ratio and obtain the liquid epoxy resin penetrating part (7). E) Curing and molding: The upper mold (2) and lower mold (1) are heated to cure the liquid epoxy resin permeated part (7) obtained in step D). After heating and curing, the upper mold (2) described in step D) is rotated off and taken out from the mold cavity (11) to obtain the resin composite material.

2. The method for preparing resin composite materials using an RTM molding die according to claim 1, characterized in that: The cleaning process for the upper mold (2) and lower mold (1) in step A) is performed by using tools or cleaning agents. The tool cleaning is performed by using a scraper or shovel; the cleaning agent cleaning is performed by using a solvent-based cleaning agent, such as acetone, methyl ethyl ketone or isopropylidene acetone.

3. The method for preparing resin composite materials using an RTM molding die according to claim 1, characterized in that: The release wax mentioned in step A) is TR-102 or Stoner mold release 8.

4. The method for preparing resin composite materials using an RTM molding die according to claim 1, characterized in that: The fibers constituting the dry fiber layer in step B) are carbon fibers, which have a tensile strength of 3000-7000 MPa, a tensile modulus of 200-600 GPa, a compressive strength of 1000-3000 MPa, an interlaminar shear strength of 50-150 MPa, a flexural strength of 1500-2500 MPa, and a density of 1.5-2.0 g / cm³. 3 And the porosity is <1-2%.

5. The method for preparing resin composite materials using an RTM molding die according to claim 1, characterized in that: The liquid epoxy resin inlet pipe (5) and the redundant liquid epoxy resin outlet pipe (6) mentioned in step C) are both transparent PVC pipes.

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