Integrated forming method and die for composite material frame with turnup

Abstract

The invention provides an integrated forming method for a composite material frame with a flange and a mold thereof, and belongs to the technical field of composite material forming. The problems that in the forming process of an existing composite closed cavity frame with an outer flange, due to the fact that the outer flange and a frame body cannot be integrally formed and segmented splicing is carried out, the connecting strength is insufficient, the size precision exceeds the standard, and the requirements for the integrity and high precision of a closed cavity structure are difficult to consider are solved. The mold comprises an outer mold, an outer flanging corner box, outer sections, a metal core mold, water-soluble core molds, an upper cover, a pressurizing outer frame, a bottom plate and positioning blocks, the metal core mold is connected to the bottom plate, the positioning blocks are connected to the circumferential direction and the top face of the metal core mold, the water-soluble core molds are connected to the peripheries of the positioning blocks, the outer sections are connected to the two sides of the water-soluble core molds, and the upper cover is connected to the outer sections. The outer flanging corner box is vertically connected to the side edge of the outer section, and the outer mold is connected to the outer side of the outer section and the outer flanging corner box. The forming die is mainly used for integrally forming the composite material frame with the turned-over edge.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding technology, and in particular relates to an integrated molding method for composite material frames with flanges and its mold. Background Technology

[0002] With the rapid development of aerospace technology, the structural design of spacecraft is constantly moving towards lightweight, high precision, and high integration, which places extremely stringent requirements on the performance of various key structural components. Among the many structural forms, the closed-cavity frame with outward-flared edges has become an indispensable basic component in aerospace equipment due to its multiple functions, including load-bearing, sealing, and installation connection. This type of structure not only needs to minimize its own weight to improve launch efficiency and payload transport capacity to meet the lightweight requirements, but its outward-flared edges often serve as mounting surfaces for connection with the launch system or other components. Therefore, it must achieve reliable integrated molding with the frame body. If secondary connection methods such as post-bonding or screwing are used, insufficient interface bonding can easily lead to weak connection strength, or assembly errors can cause dimensional inaccuracies to exceed standards, thus affecting the reliability and service life of the entire system. Therefore, integrated molding is the core technical requirement for this structural component.

[0003] Composite materials, with their high specific strength and high specific stiffness, have become the preferred material for achieving lightweight aerospace structural components. However, in the molding practice of closed-cavity frames with outward-flared edges, the integrated molding of the outward-flared edges and the frame body has long faced technical bottlenecks. In existing composite material molding processes, the mainstream solution for such complex structures is to mold in sections and then assemble them: that is, to first prepare the frame body and the outward-flared edge components separately, and then combine them into a whole through mechanical connection or adhesive bonding. However, this approach has significant drawbacks: on the one hand, segmented molding will create obvious stress concentration areas at the connection interfaces. Due to the process differences in molding of different components and the unavoidable defects of secondary connections, this part becomes the weak point in the mechanical properties of the entire structure, making it difficult to withstand the complex dynamic loads and extreme environmental tests in aerospace applications; on the other hand, the splicing process is highly dependent on assembly accuracy. Even with the assistance of precision tooling, it is still difficult to completely eliminate accumulated errors, affecting its compatibility with supporting systems; in addition, multi-process operations will prolong the production cycle and increase the difficulty of quality control, failing to meet the manufacturing requirements of aerospace products for high efficiency and high stability. Summary of the Invention

[0004] In view of this, the present invention aims to propose an integrated molding method and mold for composite material frames with flanges, in order to solve the problems in the existing molding of composite material closed-cavity frames with external flanges, where the external flanges and the frame body cannot be integrally molded, resulting in insufficient connection strength and excessive dimensional accuracy due to segmented splicing, and it is difficult to balance the integrity of the closed-cavity structure with high precision requirements.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an integrated molding method for a composite material frame with flanges, wherein the molding resin of the composite material is epoxy resin and the reinforcing phase is carbon fiber prepreg; the molding method includes the following steps: Step 1: Apply release agent evenly to all molding surfaces of the mold. After initial curing, repeat the application multiple times. Place the mold in a curing oven for heating. After removing it from the oven, apply release agent evenly to the mold surface and apply silicone grease evenly to the threads. Select water-soluble material and process the shape of the water-soluble core mold according to the dimensions of the frame cavity. After processing, lay prepreg on the water-soluble core mold. Step 2: Install the metal core mold onto the base plate, lay prepreg on the metal core mold as a base, connect the positioning block to the metal core mold, and place the water-soluble core mold with prepreg laid on it in sequence around the positioning block. Turn the prepreg laid on the metal core mold over to ensure the continuity of the fiber of the overall frame components. Step 3: Install the outer segments onto both sides of the water-soluble core mold, lay prepreg on the outward-turned corner box, vertically connect the outward-turned corner box to the side of the outer segments, connect the outer mold to the outside of the outer segments and the outward-turned corner box, lay prepreg on the bottom surface of the outward-turned corner box to ensure the fiber continuity between the outward-turned corner box and the frame. Step 4: Install a top cover on the outer mold, install screws on the top cover and base plate and tighten them for pressure, install a pressure outer frame on the base plate, connect screws on the pressure outer frame, and apply axial pressure to the outer mold through the screws; Step 5: Place the molded product into a curing oven for curing. After curing, cool it with the oven. After cooling, demold. After demolding, open several demolding holes on the surface of the composite material frame. Rinse the internal water-soluble core mold with water until it is completely removed. Use the same composite material as the frame to seal the demolding holes.

[0006] Furthermore, the reinforcing phase is M40 grade carbon fiber prepreg with a fiber volume fraction ≥60%.

[0007] Furthermore, after applying the release agent described in step 1, let it stand for 20 minutes to initially cure, repeat the application 2-3 times, and let it air dry naturally until there are no drips or bubbles on the surface; heat the mold in the curing oven at 40℃ and keep it at that temperature for 30 minutes, and apply the release agent twice after removing it from the oven.

[0008] Furthermore, in step 1, the dimensional tolerance of the water-soluble core mold is ≤0.1mm, and it needs to be cleaned and dried after processing to remove surface debris and moisture.

[0009] Furthermore, the metal core mold described in step 2 is positioned and mounted on the base plate using screws and pins; the outer threaded hole of the base plate is used to connect with the top cover to achieve pressure, and the inner threaded hole is used to connect with the metal core mold.

[0010] Furthermore, in step 3, the outer segments are connected to the outer mold using screws and pins.

[0011] Furthermore, the curing process in step 5 is as follows: first, heat to 100±5℃ and maintain for 2h±10min until the mold gap is ≤0.05mm; then, heat to the curing temperature at a rate of 1℃ / min and maintain for 3-4h. Furthermore, after curing, the product is cooled to below 80°C in the oven before demolding.

[0012] Furthermore, the diameter of the demolding hole mentioned in step 5 is 3-5mm.

[0013] This invention also provides a mold for an integrated molding method of a composite material frame with flanges. The mold includes: an outer mold, an outer flange corner box, outer segments, a metal core mold, a water-soluble core mold, a top cover, a pressure outer frame, a base plate, and positioning blocks. The metal core mold is connected to the base plate. Positioning blocks are connected to the circumference and top surface of the metal core mold. The water-soluble core mold is connected around the positioning blocks. The outer segments are connected to both sides of the water-soluble core mold. The outer flange corner box is vertically connected to the side of the outer segments. The outer mold is connected to the outside of the outer segments and the outer flange corner box. A top cover is provided above the outer mold. The top cover is connected to the base plate by a first pressure screw. A pressure outer frame is installed on the base plate. A second pressure screw is connected to the pressure outer frame and contacts the outer mold.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention effectively solves the problems of insufficient connection strength, excessive dimensional accuracy, and difficulty in ensuring integrity caused by segmented molding of existing closed-cavity structures. Integrated molding avoids defects such as weak interface bonding and cumulative assembly errors caused by secondary connections such as subsequent bonding and screwing. The overall mechanical properties of the frame are excellent, with a fiber volume fraction ≥60%. Through simulation comparison, the mechanical properties of the integrated structure are more stable and can meet the requirements of complex aerospace loads and extreme environments. After the closed-cavity structure is sealed with carbon fiber, a sealing effect is achieved, ensuring the functionality and reliability of the structure. At the same time, by combining water-soluble pre-embedded molding technology with segmented mold design, the integrated molding of the closed-cavity structure and the outer flange is achieved, solving the technical problem of insufficient connection strength between the outer flange and the frame and the inability to integrate them in traditional molding processes. The seamless connection between the outer flange and the frame body is achieved through segmented mold positioning, ultimately obtaining a composite material frame with uniform wall thickness, high dimensional accuracy, and excellent mechanical properties.

[0015] The molding method described in this invention simplifies the molding process of closed cavity structures and outward flanges, and shortens the production cycle compared with traditional segmented molding processes. The water-soluble core mold is easy to remove, which further improves the smoothness and efficiency of process implementation, reduces the difficulty of quality control, and can better meet the manufacturing requirements of aerospace products for high efficiency and high stability.

[0016] This invention has a wide range of applications. The method is not only applicable to closed-cavity frame structures with outward flanges in the aerospace field, but can also be adapted to the manufacturing of similar structural components in the aviation, rail transportation and other fields by adjusting the mold size and layup parameters. It has strong versatility and promotion value, and provides a feasible technical solution for the manufacturing of lightweight, integrated and high-precision structural components in related fields. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a three-dimensional structural diagram of an integrated molding die for a composite material frame with flanges, as described in this invention. Figure 2 This is a schematic diagram of the internal structure of an integrated molding die for a composite material frame with flanges, as described in this invention. Figure 3 This is a cross-sectional view of an integrated molding die for a composite material frame with flanges, as described in this invention. Figure 4 This is a schematic diagram of the upper cover structure described in this invention; Figure 5 This is a schematic diagram of the pressurized outer frame structure described in this invention; Figure 6 This is a schematic diagram of the base plate structure described in this invention; Figure 7 This is a schematic diagram of the outer mold structure described in this invention; Figure 8 This is a schematic diagram of the outward-flaring corner box structure described in this invention; Figure 9 This is a schematic diagram of the external lobe structure described in this invention; Figure 10 This is a schematic diagram of the metal core mold structure described in this invention; Figure 11 This is a schematic diagram of the water-soluble core mold structure described in this invention.

[0018] In the picture: 1-Outer mold, 2-Outwardly turned corner box, 3-Outer segment, 4-Metal core mold, 5-Water-soluble core mold, 6-Top cover, 7-Pressure outer frame, 8-Base plate, 9-Positioning block. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0020] See Figure 1-11 This embodiment describes an integrated molding method for a composite material frame with flanges. The molding resin of the composite material is epoxy resin, and the reinforcing phase is carbon fiber prepreg. The molding method includes the following steps: Step 1: Apply release agent evenly to all molding surfaces of the mold. After initial curing, repeat the application multiple times. Place the mold in a curing oven for heating. After removing it from the oven, apply release agent evenly to the mold surface and apply silicone grease evenly to the threads. Select water-soluble material and process the shape of the water-soluble core mold 5 according to the dimensions of the frame cavity. After processing, lay prepreg on the water-soluble core mold 5. Step 2: Install the metal core mold 4 onto the base plate 8, lay prepreg on the metal core mold 4 as a base, connect the positioning block 9 to the metal core mold 4, and place the water-soluble core mold 5 with prepreg laid on it in sequence around the positioning block 9. Turn the prepreg laid on the metal core mold 4 to ensure the continuity of the fiber of the overall frame components. Step 3: Install the outer segment 3 on both sides of the water-soluble core mold 5, lay prepreg on the outward-turned corner box 2, vertically connect the outward-turned corner box 2 to the side of the outer segment 3, connect the outer mold 1 to the outside of the outer segment 3 and the outward-turned corner box 2, lay prepreg on the bottom surface of the outward-turned corner box 2 to ensure that the fibers of the outward-turned corner box 2 and the frame are continuous. Step 4: Install an upper cover 6 on the outer mold 1, install screws on the upper cover 6 and the base plate 8 and tighten them for pressure, install a pressure outer frame 7 on the base plate 8, connect screws on the pressure outer frame 7, and apply axial pressure to the outer mold 1 through the screws; Step 5: Place the molded product into a curing oven for curing. After curing, cool it with the oven. After cooling, demold. After demolding, open several demolding holes on the surface of the composite material frame. Rinse the internal water-soluble core mold 5 with water until it is completely removed. Use the same composite material as the frame to seal the demolding holes.

[0021] In this embodiment, the reinforcing phase is M40 grade carbon fiber prepreg with a fiber volume fraction ≥60%. After applying the release agent in step 1, allow it to stand for 20 minutes for initial curing, repeat the application 2-3 times, and allow it to air dry naturally until the surface is free of drips and bubbles. The mold is heated in a curing oven at 40℃ for 30 minutes, and after removal from the oven, apply two coats of release agent. The water-soluble core mold 5 in step 1 has a dimensional tolerance ≤0.1mm and requires cleaning and drying after processing to remove surface debris and moisture.

[0022] In this embodiment, the metal core mold 4 described in step 2 is positioned and installed on the base plate 8 using screws and pins. The outer threaded hole of the base plate 8 is used to connect with the upper cover 6 to achieve pressure, and the inner threaded hole is used to connect with the metal core mold 4. In step 3, the outer segment 3 is connected to the outer mold 1 using screws and pins. The curing process in step 5 is as follows: first, the temperature is raised to 100±5℃ and held for 2h±10min until the mold gap is ≤0.05mm. Then, the temperature is raised to the curing temperature at a rate of 1℃ / min and held for 3-4h. After curing, the temperature is cooled to below 80℃ in the furnace before demolding. The diameter of the demolding hole described in step 5 is 3-5mm.

[0023] This embodiment describes a mold used in an integrated molding method for a composite material frame with flanges. The mold includes: an outer mold 1, an outer flange corner box 2, an outer segment 3, a metal core mold 4, a water-soluble core mold 5, a top cover 6, a pressure outer frame 7, a base plate 8, and positioning blocks 9. The metal core mold 4 is connected to the base plate 8. Positioning blocks 9 are connected to the circumference and top surface of the metal core mold 4. The water-soluble core mold 5 is connected to the four sides of the positioning blocks 9. The outer segment 3 is connected to both sides of the water-soluble core mold 5. The outer flange corner box 2 is vertically connected to the side of the outer segment 3. The outer mold 1 is connected to the outer side of the outer segment 3 and the outer flange corner box 2. The top cover 6 is provided above the outer mold 1. The top cover 6 is connected to the base plate 8 by a first pressure screw. The pressure outer frame 7 is installed on the base plate 8. A second pressure screw is connected to the pressure outer frame 7, and the second pressure screw is in contact with the outer mold 1.

[0024] The complete description of this implementation method is as follows: The molding die includes an outer mold 1, an outwardly turned corner box 2, an outer segment 3, a metal core mold 4, a water-soluble core mold 5, a top cover 6, a pressure outer frame 7, a base plate 8, and positioning blocks 9. The metal core mold 4 is connected to the base plate 8. Positioning blocks 9 are connected to the circumference and top surface of the metal core mold 4. The water-soluble core mold 5 is connected to the four sides of the positioning blocks 9. The outer segment 3 is connected to both sides of the water-soluble core mold 5. The outwardly turned corner box 2 is vertically connected to the side of the outer segment 3. The outer mold 1 is connected to the outer sides of the outer segment 3 and the outwardly turned corner box 2. The top cover 6 is installed above the outer mold 1. The top cover 6 is connected to the base plate 8 by a first pressure screw. The pressure outer frame 7 is installed on the base plate 8. A second pressure screw is connected to the pressure outer frame 7, and the second pressure screw contacts the outer mold 1. The outer ring threaded hole of the base plate 8 is used to connect with the upper cover 6 to achieve pressure, and the inner ring threaded hole is used to connect with the metal core mold 4; the metal core mold 4 is positioned and installed on the base plate 8 by screws and pins; the outer segment 3 is connected to the outer mold 1 by screws and pins.

[0025] During molding, the molding resin of the composite material is epoxy resin, and the reinforcing phase is M40 grade carbon fiber prepreg with a fiber volume fraction ≥60%. A release agent is evenly applied to all molding surfaces of the mold. After standing for 20 minutes to allow the release agent to initially cure, the application is repeated 2-3 times. The mold is then allowed to air dry naturally until there are no drips or bubbles on the surface. The mold is then placed in a curing oven and heated to 40℃ for 30 minutes. After removing it from the oven, two coats of release agent are quickly and evenly applied to the mold surface. Silicone grease is evenly applied to the screw threads to prevent thread adhesion. A water-soluble material with high dimensional stability is selected. The structure of the water-soluble core mold 5 is designed according to the dimensions of the frame cavity. The shape is machined using a CNC milling machine to ensure a dimensional tolerance ≤0.1mm. After machining, the water-soluble core mold 5 is cleaned and dried to remove surface debris and moisture, ensuring no impurities in contact with the prepreg. The prepreg is then laid on the water-soluble core mold 5. During the laying process, cold vacuum is used to remove interlayer air, ensuring compaction of the layers.

[0026] Install the metal core mold 4 onto the base plate 8 and secure it with screws and pins; lay prepreg on the metal core mold 4 as a base layer; connect the positioning block 9 to the metal core mold 4, and place the water-soluble core mold 5 with prepreg laid on it in sequence around the positioning block 9; turn the prepreg laid on the metal core mold 4 to achieve the continuity of the fiber of the overall frame component. Install the outer segment 3 onto both sides of the water-soluble core mold 5; lay prepreg on the outward-turned corner box 2 and vertically connect the outward-turned corner box 2 to the side of the outer segment 3; connect the outer mold 1 to the outside of the outer segment 3 and the outward-turned corner box 2 by screws and pins; lay prepreg on the bottom surface of the outward-turned corner box 2 to achieve fiber continuity between the outward-turned corner box 2 and the frame, thereby improving the overall strength of the component after curing.

[0027] A top cover 6 is set above the outer mold 1. Screws are installed and tightened on the bottom plate 8 and the top cover 6 to achieve molding pressure. A pressure outer frame 7 is installed on the bottom plate 8. Screws are connected to the pressure outer frame 7. The mold axially pressurizes the component through the contact between the screws and the outer mold 1.

[0028] The pre-molded product is placed in a curing oven and heated to 100±5℃, held for 2h±10min until the mold gap is ≤0.05mm. The mold gap data is measured and recorded with a feeler gauge. The temperature is increased to the curing temperature at a rate of 1℃ / min and held for 3-4h for curing. After curing, the product is cooled to below 80℃ in the oven and removed from the curing oven. After cooling, the product is demolded. After demolding, several demolding holes with a diameter of 3-5mm are opened on the surface of the composite material frame. The internal water-soluble core mold 5 is rinsed with high-pressure water until it is completely removed. The demolding holes are sealed with the same M40 grade carbon fiber prepreg and epoxy resin as the frame, ensuring that the sealed area is flush with the surface of the frame and has no obvious seams.

[0029] In the above embodiments, the water-soluble core mold 5 serves to form a closed cavity structure and ensure its integrity during the molding process, which can then be easily removed by rinsing with water. The positioning block 9 is used to accurately fix the position of the water-soluble core mold 5, ensuring its relative positional accuracy with the metal core mold 4, and cooperating with the flipping operation to ensure the fiber continuity of the overall frame components. The outer segment 3 is used to assist in positioning the outward-flared corner box 2, and together with the outer mold 1, forms the external contour required for molding. The outward-flared corner box 2 directly forms the outward-flared structure of the frame, and the prepreg laid on its bottom surface ensures the fiber continuity with the overall frame, thereby realizing the integration of the outward-flared edge with the frame body. The outer mold 1 is connected to the outer segment 3 and the outer flange corner box 2 to form the main external cavity for molding. The upper cover 6 and the bottom plate 8 are connected by screws to achieve radial pressure during the molding process. The pressure outer frame 7 and the second pressure screw achieve axial pressure. The two work together to ensure that the prepreg layer is tightly attached to the mold surface during the curing process, resulting in a component with uniform wall thickness. The metal core mold 4 serves as a basic support component connected to the bottom plate 8 and provides an installation reference for the water-soluble core mold 5 and the positioning block 9. The inner and outer ring threaded holes on the bottom plate 8 are used to connect the upper cover 6 to achieve pressure and to connect with the metal core mold 4, respectively. The pin holes are used to position the metal core mold 4.

[0030] The entire process is based on water-soluble pre-embedded molding technology combined with segmented mold design. First, a base prepreg is laid on the metal core mold 4. The water-soluble core mold 5 is fixed by the positioning block 9, and the material is turned over to ensure fiber continuity. Then, the outer segments 3, the outer flange corner boxes 2, and the outer mold 1 are installed in sequence. After the layup is completed, radial and axial pressure is applied by the top cover 6 and the pressure-pressurizing outer frame 7. After the mold is closed, the temperature is gradually increased to cure, so that the epoxy resin and carbon fiber prepreg are formed into an integral structure. After curing, the water-soluble core mold 5 is removed to form a closed cavity. The demolding hole is sealed and smoothed, and finally a composite material frame with uniform wall thickness, high dimensional accuracy, and excellent mechanical properties is obtained. The precise positioning of the segmented mold achieves seamless connection between the outer flange and the frame body. The integrated molding avoids the weakness caused by later bonding and screwing. The water-soluble core mold 5 ensures the integrity of the closed cavity structure and is easy to remove. The pressure system ensures dense layup, thereby meeting the aerospace field's requirements for lightweight, integrated, and high-precision structural components.

[0031] The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A method of integrally forming a composite material frame with a flange, the method comprising: The molding resin of the composite material is epoxy resin, and the reinforcing phase is carbon fiber prepreg; the molding method comprises the following steps: ​ Step 1: uniformly brush the mold release agent on all the molding surfaces of the mold, repeat the brushing multiple times after preliminary curing, heat the mold in a curing oven, uniformly apply the mold release agent on the surface of the mold after taking out of the oven, uniformly apply silicone grease on the threads, select water-soluble material, process the water-soluble core mold (5) according to the size of the closed cavity of the frame, and lay the prepreg on the water-soluble core mold (5) after processing; Step 2: install the metal core mold (4) on the bottom plate (8), lay the prepreg on the metal core mold (4) for bottoming, connect the positioning block (9) to the metal core mold (4), and sequentially place the water-soluble core mold (5) with the prepreg laid thereon around the positioning block (9), turn over the prepreg laid on the metal core mold (4) for bottoming to ensure the continuity of the fibers of the frame overall component; Step 3: install the outer split part (3) to the two sides of the water-soluble core mold (5), lay the prepreg on the outer turned edge corner box (2), vertically connect the outer turned edge corner box (2) to the side edge of the outer split part (3), connect the outer mold (1) to the outer side of the outer split part (3) and the outer turned edge corner box (2), and lay the prepreg on the bottom surface of the outer turned edge corner box (2) to ensure the fiber continuity between the outer turned edge corner box (2) and the frame as a whole; Step 4: set the upper cover (6) above the outer mold (1), screw and tighten the upper cover (6) to the bottom plate (8) for pressing, install the pressing outer frame (7) on the bottom plate (8), connect the screw to the pressing outer frame (7), and axially press the outer mold (1) through the screw; Step 5: place the molded product in the curing oven for curing, cool down after curing, and demold after cooling; after demolding, a plurality of demolding holes are formed on the surface of the composite frame, the internal water-soluble core mold (5) is washed by water flow until completely removed, and the demolding holes are closed by using the same composite material as the frame.

2. The method of claim 1, wherein: The reinforcing phase is M40 grade carbon fiber prepreg, and the fiber volume fraction is ≥60%.

3. The method of claim 1, wherein: In step 1, the mold release agent is brushed and left to stand for 20 minutes for preliminary curing, and the brushing is repeated 2-3 times, and the surface is naturally dried until there is no dripping and no bubbles; the mold is heated in the curing oven at a temperature of 40℃, and the temperature is kept for 30 minutes, and the mold release agent is applied for 2 times after taking out of the oven.

4. The method of claim 1, wherein: In step 1, the size tolerance of the water-soluble core mold (5) is ≤0.1mm, and the water-soluble core mold (5) needs to be cleaned and dried after processing to remove surface debris and moisture.

5. The method of claim 1, wherein: In step 2, the metal core mold (4) is positioned and installed on the bottom plate (8) through screws and pins; the outer circle threaded hole of the bottom plate (8) is used to connect with the upper cover (6) to realize pressing, and the inner circle threaded hole is used to connect with the metal core mold (4).

6. The method of claim 1, wherein: In step 3, the outer split part (3) is connected with the outer mold (1) through screws and pins.

7. The method of claim 1, wherein: In step 5, the curing process is as follows: first, heat to 100±5℃ and keep for 2h±10min until the gap between the molds is ≤0.05mm, then heat to the curing temperature at a rate of 1℃ / min, and keep for 3-4h.

8. The method of claim 1, wherein: After curing, cool down to below 80℃ in the oven before demolding.

9. The method of claim 1, wherein: In step 5, the diameter of the demolding hole is 3-5mm.

10. A mold for use in the integrated molding of a composite material frame with a flange according to any one of claims 1 to 9, characterized in that: The mold comprises: The utility model provides an outer mould (1), outside turn -up edge corner box (2), outer split (3), metal core mould (4), water -soluble core mould (5), upper cover (6), pressurizing outer frame (7), bottom plate (8) and positioning block (9), metal core mould (4) is connected on bottom plate (8), metal core mould (4) circumferential and top surface all are connected with positioning block (9), positioning block (9) four quarters are connected water -soluble core mould (5), water -soluble core mould (5) both sides are connected with outer split (3), outside turn -up edge corner box (2) vertical connection is in the side of outer split (3), outer mould (1) is connected in outer split (3) and outside turn -up edge corner box (2), the upper cover (6) of outer mould (1) is provided, the upper cover (6) is connected with bottom plate (8) through first pressurizing screw, the bottom plate (8) is installed pressurizing outer frame (7), the pressurizing outer frame (7) is connected second pressurizing screw, and the second pressurizing screw is in contact with outer mould (1).

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