A hollow composite skin forming system

Abstract

The utility model provides a kind of hollow composite material skin forming system, the top of workbench is supported with skin forming mould, the top of skin forming mould is laid hollow composite material preform to be formed;The upper surface of hollow composite material preform is laid release cloth, the upper surface of release cloth is laid flow guide net, the upper surface of flow guide net is laid vacuum bag;Sealing rubber strip is arranged between vacuum bag and skin forming mould;The inside of vacuum bag and one end of hollow composite material preform are provided with glue pipe, glue pipe is connected with glue storage barrel by first communicating pipe, the inside other end of vacuum bag is provided with suction pipe, suction pipe is connected with resin collector by second communicating pipe;Resin collector is connected with vacuum pump by third communicating pipe.This system and method can be used for the forming of 3D felt skin structure aircraft adjusting piece, while meeting the performance structure of adjusting piece, ensure forming quality, and effectively improve forming efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of aircraft rudder and rudder adjustment plate repair technology, specifically relating to a hollow composite material skin molding system. Background Technology

[0002] The elevator and rudder trimmers of a certain type of aircraft are composite material structural parts, and the elevator and rudder trimmers are 3D felt structures. During the aircraft overhaul, it was found that the scrap rate of the elevator and rudder trimmers was about 50%. The main reason for the scrap was that the radial clearance of the suspension bracket joint bearing exceeded the tolerance (after disassembly and inspection, it was found that this fault was caused by the wear of the mounting bolts). At this time, it is necessary to remanufacture the trimmers.

[0003] Currently, only Shaanxi Aircraft Industry Group Co., Ltd. in China is capable of producing 3D felt skin parts based on the mature hand lay-up molding process. However, its production capacity is severely limited. In addition, due to the limitations of the hand lay-up process, the quality stability of the products is poor and the cost is high. This results in a long manufacturing cycle for each trim piece. In addition, the demand for trim pieces is large, and the original manufacturing unit's capacity is limited, making it difficult to purchase the products needed for aircraft overhaul, which is far from meeting the needs of our factory's aircraft repair. Utility Model Content

[0004] The purpose of this invention is to provide a hollow composite material skin molding system. This system and method can be used to mold aircraft trim pieces with 3D felt skin structures. While meeting the performance and structural requirements of the trim pieces, it ensures molding quality and effectively improves molding efficiency, thereby improving aircraft repair efficiency.

[0005] To achieve the above-mentioned technical features, the purpose of this utility model is as follows: A hollow composite material skin molding system includes a worktable, a skin molding mold supported on the top of the worktable, and a hollow composite material preform to be molded laid on the top of the skin molding mold; a release cloth is laid on the upper surface of the hollow composite material preform, a guide net is laid on the upper surface of the release cloth, and a vacuum bag is laid on the upper surface of the guide net; a sealing strip is set between the vacuum bag and the skin molding mold to seal the entire hollow composite material preform; an inlet pipe is set inside the vacuum bag at one end of the hollow composite material preform, the inlet pipe is connected to a glue storage tank through a first connecting pipe, and an exhaust pipe is set inside the vacuum bag at the other end of the hollow composite material preform, the exhaust pipe is connected to a resin collector through a second connecting pipe; the resin collector is connected to a vacuum pump through a third connecting pipe.

[0006] The shape and structure of the upper surface of the skin forming mold are determined according to the shape and structure of the 3D felt skin part to be formed.

[0007] The hollow composite material preform is a three-dimensional woven hollow composite material, woven from glass fiber, and can be impregnated and cured with epoxy resin adhesive to form a 3D felt skin.

[0008] Before molding, a release agent is applied between the upper surface of the skin molding mold and the hollow composite material preform to form a release agent layer.

[0009] The interior of the adhesive storage tank is used to store epoxy resin adhesive.

[0010] The resin collector adopts a closed barrel structure and is equipped with a vacuum gauge.

[0011] A breathable felt is provided between the air extraction pipe and the skin forming mold.

[0012] The resin collector is equipped with a pressure valve for vacuum pressure.

[0013] The present invention has the following beneficial effects:

[0014] 1. This utility model uses molds and vacuum-assisted molding processes to significantly improve the surface quality and resin uniformity of 3D felt skin compared to hand lay-up molding.

[0015] 2. Through reasonable process parameter settings, this utility model enables the overall hollow layer height of the 3D felt skin to have better dimensional stability.

[0016] 3. This invention utilizes vacuum-assisted molding, resulting in higher production efficiency. By adjusting the vacuum level and resin viscosity, resin can be uniformly impregnated to a depth of 1 m within 3 minutes. 2 3D woven material.

[0017] 4. The successful development of this utility model of 3D felt composite material skin can be applied to the expanded repair of rudder and elevator trimmers of a series of aircraft models, solving the problem that the company's inability to control the purchase cycle of the two types of trimmers affects the aircraft overhaul cycle.

[0018] 5. The vacuum-assisted molding technology of this utility model can not only be used for molding 3D felt composite materials, but also for molding fiber composite material structures and fiber sandwich structures. Furthermore, with improvements, this technology can also be applied to the repair of aircraft composite materials to improve repair quality. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 This is a diagram of the molding system of this utility model.

[0021] In the diagram: 1. Glue storage tank; 2. First connecting pipe; 3. Workbench; 4. Sealing strip; 5. Release agent layer; 6. Skin forming mold; 7. Glue inlet pipe; 8. Vacuum bag; 9. Guide net; 10. Release cloth; 11. Hollow composite preform; 12. Evacuation pipe; 13. Breathable felt; 14. Second connecting pipe; 15. Vacuum gauge; 16. Resin collector; 17. Third connecting pipe; 18. Vacuum pump. Detailed Implementation

[0022] The embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0023] See Figure 1 A hollow composite material skin molding system includes a workbench 3, a skin molding mold 6 supported on the top of the workbench 3, and a hollow composite material preform 11 to be molded laid on the top of the skin molding mold 6. A release cloth 10 is laid on the upper surface of the hollow composite material preform 11, a guide net 9 is laid on the upper surface of the release cloth 10, and a vacuum bag 8 is laid on the upper surface of the guide net 9. A sealing strip 4 is set between the vacuum bag 8 and the skin molding mold 6 to seal the entire hollow composite material preform 11. A glue inlet pipe 7 is set inside the vacuum bag 8 and at one end of the hollow composite material preform 11. The glue inlet pipe 7 is connected to a glue storage tank 1 through a first connecting pipe 2. An air extraction pipe 12 is set inside the vacuum bag 8 and at the other end of the hollow composite material preform 11. The air extraction pipe 12 is connected to a resin collector 16 through a second connecting pipe 14. The resin collector 16 is connected to a vacuum pump 18 through a third connecting pipe 17. The vacuum-assisted molding process described above offers several advantages over hand lay-up: more uniform adhesive impregnation and higher precision in controlling the amount of adhesive used. This makes it well-suited for molding aircraft trim panels with 3D felt skin structures. While meeting the performance and structural requirements of the trim panels, it ensures molding quality and effectively improves molding efficiency, thus enhancing aircraft repair efficiency. Specifically, the vacuum-assisted molding process involves removing gas from the three-dimensional woven hollow composite material under vacuum conditions. Resin flow and penetration are then used to impregnate the fibers and fabric, followed by curing at a specific temperature to form a 3D felt skin component with a defined resin / fiber ratio.

[0024] Furthermore, the upper surface shape of the skin forming mold 6 is determined according to the shape of the 3D felt skin part to be formed. The skin forming mold 6 described above can be used to pre-process and manufacture the corresponding skin forming mold 6 according to the structure of the part to be formed.

[0025] Among them, the skin of the aircraft elevator trimmer and rudder trimmer are both curved surfaces, and the hollow thickness of the skin should be consistent. Using a vacuum induction molding process can improve production efficiency while ensuring product quality. The corresponding skin molding mold 6 is made using the external structure of the aircraft elevator trimmer and rudder trimmer.

[0026] Furthermore, the hollow composite material preform 11 is a three-dimensional woven hollow composite material, woven from glass fibers, and can be impregnated and cured with epoxy resin adhesive to form a 3D felt skin. The glass fibers should be flame-retardant, and the epoxy resin adhesive used to impregnate and cure the 3D felt skin also possesses flame-retardant properties.

[0027] Furthermore, before molding, a release agent is pre-applied between the upper surface of the skin molding mold 6 and the hollow composite preform 11, thereby forming a release agent layer 5. Applying the release agent facilitates demolding after subsequent molding, thus improving demolding efficiency.

[0028] Furthermore, the interior of the storage tank 1 is used to store epoxy resin adhesive. The storage tank 1 facilitates the storage of epoxy resin adhesive required during the molding process.

[0029] Furthermore, the resin collector 16 adopts a closed barrel structure and is equipped with a vacuum gauge 15. The vacuum gauge 15 facilitates the display of the vacuum level during the impregnation process, thereby ensuring the impregnation effect of the bracket.

[0030] Furthermore, a breathable felt 13 is provided between the air extraction pipe 12 and the skin forming mold 6. The breathable felt 13 ensures the air permeability of the air extraction pipe 12 and prevents it from becoming blocked.

[0031] Furthermore, the resin collector 16 is equipped with a pressure valve for vacuum pressure. This pressure valve facilitates pressure control during the curing process.

[0032] The working process and principle of this utility model:

[0033] A hollow composite material skin forming system is used to achieve skin forming, including the following steps:

[0034] S1, Tooling preparation:

[0035] According to the required 3D felt skin shape structure, make the corresponding skin forming mold 6, and prepare the positioning blocks and clamping plates required in the forming process.

[0036] S2, Fabric Cutting:

[0037] According to the required 3D felt skin parts, cut the corresponding size of the three-dimensional woven hollow composite material to form the hollow composite material preform 11.

[0038] S3, Fabric Positioning:

[0039] Clean the skin forming mold 6, apply a release agent, position the hollow composite material preform 11 on the skin forming mold 6, and then lay the release cloth 10 and the guide net 9.

[0040] S4, Bag making:

[0041] Based on the dimensions of the hollow composite preform 11 and the skin forming mold 6, cut and manufacture the corresponding vacuum bags 8, ensuring that the vacuum bags 8 can cover the entire hollow composite preform 11. Arrange the corresponding glue inlet pipe 7 and air extraction pipe 12 on the skin forming mold 6. Connect the glue inlet pipe 7 to the glue storage tank 1 and the air extraction pipe 12 to the resin collector 16 and the vacuum pump 18. Then, use the sealing strip 4 to bond the vacuum bags 8 to the upper surface of the skin forming mold 6.

[0042] S5, resin formulation:

[0043] According to the molding performance requirements of the three-dimensional braided hollow composite material, the corresponding epoxy resin adhesive is prepared and stored in the inside of the adhesive storage tank 1 for later use.

[0044] S6, Vacuum Injection:

[0045] Start the vacuum pump 18 to perform vacuuming inside the vacuum bag 8, thereby guiding the epoxy resin adhesive inside the glue storage tank 1 from the glue inlet pipe 7 into the hollow composite preform 11 and flowing through the hollow composite preform 11 to impregnate it. At this time, the hollow composite preform 11 will expand vertically through capillary action to form a 3D felt structure.

[0046] After the entire hollow composite preform 11 has been impregnated, maintain pressure for a period of time;

[0047] S7, Vacuum Release:

[0048] Before the epoxy resin adhesive inside the hollow composite preform 11 is completely cured, stop the vacuum pump 18 and depressurize the vacuum bag 8 to allow the hollow composite preform 11 to fully unfold and form a 3D felt structure.

[0049] S8, Curing:

[0050] After the impregnation molding is completed, the 3D felt structure is removed and then cured under certain temperature conditions;

[0051] S9, Demolding:

[0052] After curing is complete, demold the product and remove the molded 3D felt skin part.

[0053] S10, Detection:

[0054] Use calipers, feeler gauges, and vernier calipers to inspect the thickness of the 3D felt covering and the shape of its outer surface.

[0055] The quality of the cured 3D felt skin parts is inspected visually. The surface is not allowed to have indentations or scratches that damage the fibers. Check whether wrinkles appear on the surface and whether hollow areas in the thickness direction are collapsed or sunken. Observe whether the resin distribution is uniform after curing and try to avoid excessive resin residue in the hollow layer.

[0056] During the curing process, key parameters for the 3D felt structure curing process are determined in advance using a combination of experimental and numerical simulation methods: curing temperature, heating rate, cooling rate, vacuum degree, curing time, resin viscosity, and resin content; environmental and equipment requirements are clarified based on the characteristics of the molding process and material requirements; and inspection processes are formulated according to the technical requirements and process flow.

Claims

1. A hollow composite material skin molding system, characterized in that, The system includes a workbench (3), with a skin forming mold (6) supporting the top of the workbench (3). A hollow composite material preform (11) to be formed is laid on the top of the skin forming mold (6). A release cloth (10) is laid on the upper surface of the hollow composite material preform (11), a guide net (9) is laid on the upper surface of the release cloth (10), and a vacuum bag (8) is laid on the upper surface of the guide net (9). A sealing strip (4) is set between the vacuum bag (8) and the skin forming mold (6), and the entire hollow composite material preform ( 11) Seal it; a glue inlet pipe (7) is provided inside the vacuum bag (8) and at one end of the hollow composite preform (11). The glue inlet pipe (7) is connected to the glue storage tank (1) through the first connecting pipe (2). A vacuum extraction pipe (12) is provided inside the vacuum bag (8) and at the other end of the hollow composite preform (11). The vacuum extraction pipe (12) is connected to the resin collector (16) through the second connecting pipe (14). The resin collector (16) is connected to the vacuum pump (18) through the third connecting pipe (17).

2. The hollow composite material skin forming system according to claim 1, characterized in that: The shape and structure of the upper surface of the skin forming mold (6) are determined according to the shape and structure of the 3D felt skin part to be formed.

3. The hollow composite material skin forming system according to claim 1, characterized in that: The hollow composite material preform (11) is a three-dimensional woven hollow composite material, woven from glass fiber, and can be impregnated and cured with epoxy resin adhesive to form a 3D felt skin.

4. The hollow composite material skin forming system according to claim 1, characterized in that: Before molding, a release agent is applied between the upper surface of the skin molding mold (6) and the hollow composite preform (11) to form a release agent layer (5).

5. The hollow composite material skin forming system according to claim 1, characterized in that: The interior of the glue storage tank (1) is used to store epoxy resin adhesive.

6. The hollow composite material skin forming system according to claim 1, characterized in that: The resin collector (16) adopts a closed barrel structure and is equipped with a vacuum gauge (15).

7. The hollow composite material skin forming system according to claim 1, characterized in that: A breathable felt (13) is provided between the air extraction pipe (12) and the skin forming mold (6).

8. The hollow composite material skin forming system according to claim 1, characterized in that: The resin collector (16) is equipped with a pressure valve for vacuum pressure.

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