A method for preventing compression deformation of high-thickness large-curvature pre-impregnated honeycomb preforms

Abstract

The application discloses a method for preventing compression deformation of high-thickness large-curvature pre-impregnated honeycomb preforming, which comprises the following steps: according to the thickness of the pre-impregnated honeycomb to be preformed and the specification of the honeycomb core, a rubber support is designed and prepared, and the rubber support is filled into the honeycomb core at the position where the pre-impregnated honeycomb has large curvature and is prone to compression deformation; then, the pre-impregnated honeycomb filled with the rubber support is laid on a large-curvature preforming tool, and after being packaged, vacuumized and pre-pressed, the pre-impregnated honeycomb is sent into a hot pressing tank for curing and forming, and a large-curvature honeycomb preformed body with good quality can be obtained after demolding. The method is very simple in operation process, the rubber support material can be repeatedly used after being prepared, and can be applied to the preforming of other complex curved surface pre-impregnated honeycomb, has wide application range, and has very good practical value and popularization value.

Description

Technical Field

[0001] This invention relates to a method for preventing compression deformation during the preforming of high-thickness, high-curvature prepreg honeycomb. Background Technology

[0002] Honeycomb sandwich structures are characterized by high strength, light weight, efficient energy absorption, and good thermal and corrosion resistance, making them a common and important design choice in aerospace engineering. For example, in the design of aero-engines, honeycomb sandwich acoustic liners laid inside the air intake can absorb intake fan noise, effectively reducing aero-engine noise.

[0003] Honeycomb sandwich acoustic liner is composed of hexagonal honeycomb layers laid between perforated panels and back panels. However, the honeycomb mesh structure in the middle layer exhibits uneven stress under compressive loads. If the hexagonal honeycomb is directly laid, severe compressive deformation will occur in areas of high curvature, thereby reducing the structural strength of the acoustic liner components. This is particularly true for high-thickness, high-curvature prepreg honeycomb sandwich structures. In areas of high curvature, due to significant bending strain, the panels or back panels will buckle, bending from a planar state to a curved surface. This results in a shortening of the longitudinal length of the panels or back panels, insufficient support for the internal honeycomb structure, leading to compressive deformation during subsequent pressurization processes. Furthermore, the smaller area of ​​the panels or back panels in areas of high curvature increases the compressive load per unit area of ​​the honeycomb structure, also causing compressive deformation. Therefore, the honeycomb prepreg material must be pre-formed separately to create a high-curvature honeycomb preform to ensure its shape and strength before being used to manufacture the corresponding honeycomb sandwich structural components. However, the preforming process of honeycomb prepreg requires vacuuming and autoclave molding, which also presents the challenge of compression deformation of the honeycomb structure.

[0004] Therefore, preventing compression deformation during prepreg honeycomb preforming is the first problem to be solved. Summary of the Invention

[0005] To address the problems associated with existing direct molding methods for high-thickness, high-curvature prepreg honeycomb structures, this invention provides a method for preventing compression deformation of the honeycomb structure during the molding of high-curvature honeycomb sandwich components. The aim is to solve the problem of compression deformation of the high-cell honeycomb core during the preforming process of honeycomb prepreg. The specific technical solution is as follows:

[0006] A method for preventing compression deformation during the preforming of high-thickness, high-curvature preimpregnated honeycomb cells, wherein the preimpregnated honeycomb is a honeycomb impregnated with resin but not yet cured, and the preforming utilizes the characteristic that the honeycomb resin is not yet cured, allowing the preimpregnated honeycomb to be cured into the desired high-curvature honeycomb during the curing process. Specifically, the method includes the following steps:

[0007] 1) Preparation of rubber support: Design and prepare rubber support according to the thickness of the prepreg honeycomb to be preformed and the specifications of its honeycomb core;

[0008] 2) Rubber support material filling: The prepreg honeycomb material is pre-laid onto the large curvature prepreg honeycomb preforming tooling. Corresponding to the large curvature prepreg honeycomb preforming tooling, the prepared rubber support is filled into the honeycomb core cell where the curvature is large and easy to compress and deform.

[0009] 3) Honeycomb laying: The prepreg honeycomb filled with rubber support is laid on the large curvature prepreg honeycomb preforming tooling, and the perimeter of the prepreg honeycomb is cut to match the large curvature prepreg honeycomb preforming tooling.

[0010] 4) Encapsulation and pre-compression: After the honeycomb is laid, the release film and surface breathable material are laid on the prepreg honeycomb in sequence. Finally, a vacuum bag is laid to encapsulate the whole thing on the large curvature preform tooling. Then, vacuum is drawn to pre-compress the encapsulated prepreg honeycomb and observe the honeycomb deformation. At the same time, the sealing performance of the encapsulation is checked.

[0011] 5) Curing and molding: The encapsulated prepreg honeycomb and large curvature preform tooling are sent into an autoclave together, and the temperature and pressure inside the autoclave are controlled to cure and mold the prepreg honeycomb.

[0012] 6) Demolding: After curing, remove the pre-impregnated honeycomb and large curvature preforming tooling for demolding. Remove the rubber support to obtain a high-quality large curvature honeycomb preform.

[0013] In the aforementioned method for preventing the honeycomb structure from compressing and deforming during the molding of large-curvature honeycomb sandwich parts, in step 1), the rubber support is made of silicone rubber material that can withstand temperatures of 180°C and above.

[0014] Preferably, in the aforementioned method for preventing the honeycomb structure from compressing and deforming during the molding of a large-curvature honeycomb sandwich component, the method for preparing the rubber support is as follows: the silicone rubber liquid used to prepare the rubber support is poured into the honeycomb core, cured at room temperature, and then demolded to obtain a solid hexagonal prism-shaped rubber support with a height consistent with the thickness of the pre-impregnated honeycomb.

[0015] The aforementioned method for preventing the honeycomb structure from compressing and deforming during the molding of large-curvature honeycomb sandwich parts, wherein the honeycomb core of the pre-impregnated honeycomb is a hexagonal core with a side length greater than 4.8 mm and a thickness greater than 12 mm.

[0016] In the aforementioned method for preventing the compression deformation of the honeycomb structure during the molding of large-curvature honeycomb sandwich parts, step 2) refers to the area with large curvature and easy compression deformation, which is the area with a curvature radius exceeding 350mm after the pre-impregnated honeycomb is laid. The honeycomb core in this area is filled with rubber support material.

[0017] In the aforementioned method for preventing the honeycomb structure from being compressed and deformed during the molding of large curvature honeycomb sandwich parts, in step 3), the prepreg honeycomb is a whole rectangular prepreg honeycomb material with both length and width greater than 1m. When laying it, the edges of the whole prepreg honeycomb material are cut to match it with the large curvature prepreg honeycomb preforming tooling.

[0018] In the aforementioned method for preventing the honeycomb structure from compressing and deforming during the molding of large curvature honeycomb sandwich parts, step 4) involves vacuuming the encapsulated pre-impregnated honeycomb under pre-pressure, with the pre-pressure pressure ranging from -20 kPa to -65 kPa.

[0019] In the aforementioned method for preventing compression deformation of the honeycomb structure during the molding of large-curvature honeycomb sandwich components, step 5) involves pre-impregnated honeycomb, which is a honeycomb structure impregnated with resin but not yet cured. Pre-molding utilizes the characteristic that the honeycomb resin is not yet cured, allowing the pre-impregnated honeycomb to be cured into the desired large-curvature honeycomb during the curing process. The temperature can be set according to different resin curing conditions, typically 150–180°C. The pressure can be set according to the size of the pre-impregnated honeycomb core, typically -20 kPa to -65 kPa.

[0020] The beneficial effects of this invention are as follows:

[0021] 1) The method of the present invention is simple to operate. It only requires the preparation of a rubber support material with certain rigidity, high temperature resistance and slight expansion under high temperature environment, filling it into the honeycomb core, and preforming it. This solves the compression deformation problem of high-thickness and high-curvature pre-impregnated honeycomb during preforming, ensuring the shape of the honeycomb structure and the quality of the honeycomb sandwich parts prepared, and has good practical value.

[0022] 2) The rubber support material of the present invention can provide a certain support force to the honeycomb core during the pre-impregnation and curing process, preventing the honeycomb core from being compressed and deformed when laid on the pre-forming tooling with large curvature; and the rubber support material is easy to reuse after preparation, without increasing the manufacturing cost of the parts.

[0023] 3) The method of the present invention cuts the honeycomb during the laying process and pre-extracts it before packaging, which ensures the fit between the honeycomb in the large curvature area and the pre-formed tooling, and further ensures the shape of the honeycomb structure and the forming quality of its parts.

[0024] 4) In addition to honeycomb sandwich structure acoustic liner, the method of the present invention can be applied to the preforming of other complex curved honeycomb prepregs. The rubber support material used can be designed according to needs, with a wide range of applications and very good promotional value. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the longitudinal section structure of the rubber support material filling during the molding of the large curvature honeycomb sandwich part of the present invention;

[0026] Figure 2 This is a schematic diagram of the rubber support material filling structure during the molding of the large curvature honeycomb sandwich part of the present invention;

[0027] In the figure: 1. High curvature preforming tooling; 2. Rubber support; 3. Honeycomb; 4. Separating membrane; 5. Surface breathable material; 6. Vacuum bag; 7. Rubber support; 8. Pre-impregnated honeycomb. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are merely preferred embodiments of the present invention, and not all embodiments, nor are they intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications or equivalent variations based on the disclosed technical content. However, any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

[0029] Example 1

[0030] This embodiment is a method for preventing compression deformation during the preforming of high-thickness, high-curvature prepreg honeycomb, including the following steps:

[0031] 1) Preparation of the rubber support: The rubber support is prepared according to the specifications of the pre-impregnated honeycomb core. In this embodiment, the specifications of the pre-impregnated honeycomb core are hexagonal cores with a side length greater than 4.8 mm, and the thickness of the pre-impregnated honeycomb material is greater than 12 mm. In this embodiment, the rubber support is made of silicone rubber that can withstand temperatures of 180°C and above. The preparation method is as follows: liquid silicone (component A) and curing agent (component B) are mixed in a 1:1 volume ratio to form a slurry for preparing the rubber support. This slurry is then poured into the honeycomb core. After curing and demolding at room temperature, a solid hexagonal prism-shaped rubber support is obtained, with a height consistent with the thickness of the pre-impregnated honeycomb. This rubber support has a certain rigidity, and when filled into the honeycomb core of the pre-impregnated honeycomb material, it can effectively prevent the compression deformation of the honeycomb core.

[0032] 2) Rubber support material filling: The prepreg honeycomb material is pre-laid onto the large curvature prepreg honeycomb preforming tooling. Corresponding to the large curvature prepreg honeycomb preforming tooling, the prepared rubber support is filled into the honeycomb core cell in the area with a curvature radius of more than 350 mm.

[0033] 3) Honeycomb installation: The pre-impregnated honeycomb material filled with rubber support is formally installed on the large curvature honeycomb metal preform tooling; since the pre-impregnated honeycomb material to be installed is a whole rectangular piece with both length and width greater than 1m, its four edges need to be trimmed after installation to match the large curvature pre-impregnated honeycomb preform tooling.

[0034] 4) Encapsulation and pre-compression: After the honeycomb is laid, the release film and surface breathable material are laid on the prepreg honeycomb in sequence. Finally, a vacuum bag is laid to encapsulate the whole thing on the large curvature preforming tooling. Then, vacuum is drawn to pre-compress the encapsulated prepreg honeycomb. The pre-compression pressure is -20kpa to -65kpa. During the pre-compression process, the honeycomb deformation is observed and the sealing performance of the encapsulation is checked.

[0035] 5) Curing and molding: The encapsulated prepreg honeycomb and large curvature preform tooling are sent into the autoclave together. The temperature can be set according to different resin curing conditions, generally 150 to 180℃; the pressure can be set according to the size of the prepreg honeycomb core, generally -20 kPa to -65 kPa.

[0036] 6) Demolding: After curing, remove the pre-impregnated honeycomb and large curvature preforming tooling for demolding. Remove the rubber support to obtain a high-quality large curvature honeycomb preform.

[0037] Example 2

[0038] This embodiment describes the preforming of a honeycomb sandwich prepreg for the acoustic liner of an S-shaped air intake of a certain type of aircraft, according to the method described in Embodiment 1. The specific process is as follows:

[0039] Because the air intake of this aircraft model is S-shaped, its internal surface has many bends and a large curvature, with a maximum curvature radius of about 500mm. The corresponding acoustic liner structure also contains many large curvature sections. In order to achieve the expected noise reduction effect, the acoustic liner is designed to be relatively thick, with a maximum thickness of about 38mm. In order to prevent the honeycomb sandwich layer from compressing and deforming during the acoustic liner molding process and to ensure the strength of the acoustic liner structure, in this embodiment, the honeycomb sandwich layer prepreg used for the acoustic liner is pre-molded separately, and then composited with the front panel and back panel to prepare an acoustic liner product that meets the design requirements.

[0040] In this embodiment, the specific process of prepreg honeycomb preforming is as follows:

[0041] 1) The rubber support is designed and prepared according to the thickness of the honeycomb sandwich prepreg and the specifications of the honeycomb core used in the acoustic liner. In this embodiment, the honeycomb core is a hexagonal core with a side length of 4.8 mm, and the thickness of the prepreg is 38 mm. The liquid silicone (component A) and curing agent (component B) are mixed in a volume ratio of 1:1 and poured into the honeycomb core. After curing and demolding at room temperature, a solid hexagonal prism-shaped rubber support with a side length of 4.8 mm and a height of 38 mm can be obtained.

[0042] 2) Rubber support material filling: The pre-impregnated honeycomb material is pre-laid onto a pre-forming tooling for pre-impregnated honeycomb with high curvature. Corresponding to the pre-forming tooling for pre-impregnated honeycomb with high curvature, the prepared rubber support is filled into the honeycomb core cells in areas of the pre-impregnated honeycomb with curvature greater than 350 mm that are easily compressed and deformed; for example... Figure 1 and Figure 2 As shown, a total of 200 rubber support materials are filled in this embodiment.

[0043] 3) Honeycomb laying: The honeycomb sandwich prepreg filled with rubber support is formally laid on the large curvature honeycomb metal preform tooling, and its four edges are trimmed to match the forming tooling.

[0044] 4) Encapsulation and pre-compression: After the honeycomb is laid, the release film and surface breathable material are laid on the prepreg honeycomb in sequence. Finally, a vacuum bag is laid to encapsulate the whole thing on the large curvature preforming tooling. Then, vacuum is drawn to pre-compress the encapsulated prepreg honeycomb. The pre-compression pressure is -60kpa and the honeycomb deformation is observed. At the same time, the sealing performance of the encapsulation is checked.

[0045] 5) Curing and molding: The encapsulated prepreg honeycomb and the large curvature preform tooling are sent into the autoclave together, and the temperature inside the autoclave is controlled at 180℃ and the pressure at -60kpa to cure and mold the prepreg honeycomb.

[0046] 6) Demolding: After curing, remove the pre-impregnated honeycomb and large curvature preform tooling for demolding. Remove the rubber support to obtain a high-quality large curvature honeycomb for sound lining.

[0047] In summary, this invention uses rubber to prepare a rubber support material with certain rigidity, high temperature resistance, and slight expansion under high temperature conditions. This material is then filled into the honeycomb core at large curvatures to prevent deformation during preforming. The operation process is very simple, and the rubber support material is easy to reuse after preparation. It can also be applied to the preforming of other complex curved honeycomb prepregs, making it widely applicable and possessing excellent practical and promotional value.

[0048] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalent elements of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0049] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preventing compression deformation during the preforming of high-thickness, high-curvature prepreg honeycomb, characterized in that: Includes the following steps: 1) Preparation of rubber support: Based on the thickness of the prepreg honeycomb and the specifications of its honeycomb core, design and prepare the rubber support; the rubber support is made of silicone rubber material that can withstand 180℃ and above, and its preparation method is as follows: pour the silicone rubber liquid used to prepare the rubber support into the honeycomb core, cure at room temperature and demold to obtain a solid hexagonal prism-shaped rubber support with a height consistent with the thickness of the prepreg honeycomb; 2) Rubber support material filling: The prepreg honeycomb material is pre-laid onto the large curvature prepreg honeycomb preforming tooling. Corresponding to the large curvature prepreg honeycomb preforming tooling, the prepared rubber support is filled into the honeycomb core cell where the curvature is large and easy to compress and deform. 3) Honeycomb laying: The prepreg honeycomb filled with rubber support is laid on the large curvature prepreg honeycomb preforming tooling, and the perimeter of the prepreg honeycomb is cut to match the large curvature prepreg honeycomb preforming tooling. 4) Encapsulation and pre-compression: After the honeycomb is laid, the release film and surface breathable material are laid on the prepreg honeycomb in sequence. Finally, a vacuum bag is laid to encapsulate the whole thing on the large curvature preform tooling. Then, vacuum is drawn to pre-compress the encapsulated prepreg honeycomb and observe the honeycomb deformation. At the same time, the sealing performance of the encapsulation is checked. 5) Curing and molding: The encapsulated prepreg honeycomb and large curvature preform tooling are sent into an autoclave together, and the temperature and pressure inside the autoclave are controlled to cure and mold the prepreg honeycomb. 6) Demolding: After curing, remove the pre-impregnated honeycomb and large curvature preforming tooling for demolding. Remove the rubber support to obtain a high-quality large curvature honeycomb preform.

2. The method for preventing compression deformation during high-thickness, high-curvature prepreg honeycomb preforming according to claim 1, characterized in that: The pre-impregnated honeycomb core is a hexagonal core with a side length greater than 4.8 mm and a thickness greater than 12 mm.

3. The method for preventing compression deformation during high-thickness, high-curvature prepreg honeycomb preforming according to claim 1, characterized in that: In step 2), the area with large curvature and easy compression deformation is the region with a curvature radius exceeding 350mm after the prepreg honeycomb is laid.

4. The method for preventing compression deformation during high-thickness, high-curvature prepreg honeycomb preforming according to claim 1, characterized in that: In step 3), the prepreg honeycomb is a whole rectangular prepreg honeycomb material with both length and width greater than 1m. When laying it, the four edges of the whole prepreg honeycomb material are cut to match it with the prepreg honeycomb preforming tooling with large curvature.

5. The method for preventing compression deformation during high-thickness, high-curvature prepreg honeycomb preforming according to claim 1, characterized in that: In step 4), the vacuuming process pre-presses the encapsulated pre-impregnated honeycomb with a pressure of -20 kPa to -65 kPa.

6. The method for preventing compression deformation during high-thickness, high-curvature prepreg honeycomb preforming according to claim 1, characterized in that: In step 5), the curing temperature is 150-180℃ and the pressure is -20kpa to -65kpa.

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