Method of forming a metal-bonded foam sandwich structure and forming aid assembly
By using a molding method assisted by plastic parts and diaphragms, the problem of difficult bonding and assembly of metal skin and foam core was solved, realizing efficient and low-cost sandwich structure molding, ensuring molding accuracy and reducing the risk of pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- COMMERCIAL AIRCRAFT CORP OF CHINA LTD
- Filing Date
- 2025-03-13
- Publication Date
- 2026-07-21
AI Technical Summary
In existing technologies, the bonding and assembly of metal skin and foam core is difficult, the molding accuracy is poor, and the molding process is inefficient, costly, and prone to pollution problems.
By using molding auxiliary components, plastic parts and diaphragms, the foam core is first pre-processed and then re-polished to ensure its fit with the cavity. Then, vacuuming and curing are performed, eliminating the need for a first autoclave curing process and avoiding contact between the adhesive film and the foam core and metal skin.
It improves molding efficiency, reduces molding costs, avoids colloidal contamination, and enhances molding precision and efficiency.
Smart Images
Figure CN120792213B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft composite material manufacturing technology, and in particular to a molding method and molding auxiliary components for a metal-bonded foam sandwich structure. Background Technology
[0002] Metal-foam sandwich structures are a type of sandwich structure that uses metal as the skin and foam plastic as the core material. Due to their advantages such as light weight, good sealing performance, high strength, high rigidity, fatigue resistance, and corrosion resistance, they are widely used in advanced structures such as aerospace. Sandwich structures used in areas such as hatches and doors, which require even higher strength, are typically constructed by bonding a metal skin to a high-temperature resistant polymethyl methacrylate (PMMA) foam core. However, due to the porous structure within the foam core, there are several manufacturing challenges after assembly, including large gaps between the foam core and the metal skin, difficult bonding, poor warpage after curing, and low molding precision.
[0003] To address the aforementioned issues, thickness measurements from calibration film tests are typically used to adjust the foam core. This process requires two autoclave curing cycles, which results in low efficiency and high costs for foam core molding. Furthermore, because calibration film tests involve a liner wrapping the adhesive film, the foam core is prone to puncturing the liner during the experiment, causing the adhesive to flow into the foam core or metal skin and contaminate them, further increasing molding costs. Summary of the Invention
[0004] The purpose of this invention is to provide a molding method and molding auxiliary components for a metal-bonded foam sandwich structure. This molding method and molding auxiliary components can improve molding efficiency and reduce molding costs.
[0005] To achieve this objective, the present invention adopts the following technical solution:
[0006] A molding method for a metal-bonded foam sandwich structure, used for bonding a foam core in the sandwich structure to a cavity in a metal skin using molding auxiliary components, the molding method comprising:
[0007] The foam core is initially polished and fitted according to the size, depth and shape of the cavity;
[0008] First, the plastic parts in the molding auxiliary components are laid in the gap area of the cavity. Then, the foam core, which has been pre-polished and repaired, is pre-assembled into the cavity. Then, the metal skin is bagged and vacuumed in sequence.
[0009] After the plastic part in the cavity is shaped, the bag is removed and the plastic part and the foam core that has been preliminarily polished and repaired are taken out. The fit between the plastic part and the inner wall of the cavity is analyzed and recorded.
[0010] Based on the fit between the plastic part and the inner wall of the cavity, the foam core that has been initially ground and fitted is subjected to secondary grinding and fitting until the foam core that has been secondary ground and fitted is reassembled into the cavity, and the gap between the foam core and the cavity is smaller than the set gap.
[0011] An adhesive film is laid on the inner wall of the cavity, and the foam core that has been polished and repaired twice is assembled into the cavity to form a sandwich structure. Then, the sandwich structure is bagged, vacuumed, and placed in a thermostatic jar to complete the curing.
[0012] Remove the sandwich structure from the autoclave.
[0013] As a further technical solution, the gap area includes, but is not limited to, the step area, the end rounded corner area, and the edge R-corner area.
[0014] As a further technical solution, the set gap is set to 0.13mm.
[0015] As a further technical solution, before pre-assembling the pre-polished and repaired foam core into the cavity, a first diaphragm is laid between the foam core and the plastic part.
[0016] As a further technical solution, before laying the plastic part in the gap area, a second diaphragm is first laid in the cavity.
[0017] As a further technical solution, before laying the adhesive film on the inner wall of the cavity, the metal skin is first phosphoric acid anodized, and the foam core that has been polished and repaired is dried.
[0018] As a further technical solution, before performing preliminary grinding and repair on the foam core, the unground foam core is placed in the cavity, and the area to be ground is marked.
[0019] Molding auxiliary components, wherein the molding auxiliary components are applied to the molding method of metal-bonded foam sandwich structures, including:
[0020] Plastic parts are laid inside the cavities of the metal skin;
[0021] The first diaphragm is laid between the plastic part and the foam core assembled in the cavity;
[0022] The second diaphragm is laid between the plastic part and the inner wall of the cavity.
[0023] As a further technical solution, the plastic part is set as modeling clay.
[0024] As a further technical solution, the first diaphragm and the second diaphragm may be selected from polyimide film, polypropylene film, polytetrafluoroethylene film, and graphene film.
[0025] Compared with the prior art, the molding method and molding auxiliary components for the metal-bonded foam sandwich structure provided by the present invention have the following technical advantages:
[0026] 1. During the sandwich structure molding process, the unformed foam core is first pre-polished and fitted to ensure it matches the size, depth, and shape of the cavity. Then, plastic parts are laid in the corresponding gap areas within the cavity, and the pre-polished foam core is pre-assembled into the cavity containing the plastic parts. After bagging and full-pressure vacuuming, the plastic parts are completely molded. The plastic parts are then removed, and the fit between them and the cavity wall is analyzed. Based on the analysis, the foam core is polished a second time until the gap between the foam cores is smaller than the set gap after placement in the cavity. Next, an adhesive film is laid in the cavity, and the second-polished foam core is assembled into the cavity to form the sandwich structure. The sandwich structure is then bagged, vacuumed, and placed in an autoclave for curing. After curing, the sandwich structure is removed from the autoclave, thus completing one sandwich structure molding process. In this process, the fit between the foam core and the inner wall of the cavity is obtained by using a plastic part. On the one hand, there is no need for autoclave curing during the entire process, thus saving one autoclave curing process, thereby improving molding efficiency and reducing molding costs. On the other hand, before obtaining the fit between the foam core and the inner wall of the cavity, there is no need for the adhesive film to come into contact with the foam core and the metal skin. This avoids the situation where the adhesive contaminates the foam core or the metal skin when obtaining the fit between the foam core and the inner wall of the cavity, thereby further reducing molding costs.
[0027] 2. Since the plastic part is laid inside the cavity, the first diaphragm is laid between the plastic part and the foam core, and the second diaphragm is laid between the inner wall of the cavity and the plastic part. Therefore, during the foam core molding process, by using the plastic part to obtain the fit between the foam core and the inner wall of the cavity, one autoclave curing process can be eliminated, thereby improving molding efficiency and reducing molding costs. At the same time, before obtaining the fit between the foam core and the inner wall of the cavity, there is no need for the adhesive film to come into contact with the foam core and the metal skin, thus avoiding the occurrence of adhesive contamination of the foam core or the metal skin when obtaining the fit between the foam core and the inner wall of the cavity, further reducing molding costs. The first diaphragm separates the plastic part and the foam core, preventing them from affecting each other and avoiding contamination of the foam core by the plastic part before molding. The second diaphragm separates the plastic part and the inner wall of the cavity, preventing them from affecting each other and avoiding contamination of the metal skin by the plastic part before molding, thus further reducing production costs. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.
[0029] Figure 1 This is a schematic diagram showing the positions of the molding auxiliary components, metal skin, and foam core in an embodiment of the present invention;
[0030] Figure 2 This is a schematic diagram showing the positions of the molded foam core and metal skin in an embodiment of the present invention.
[0031] In the picture:
[0032] 10. Foam core; 20. Metal skin; 21. Cavity;
[0033] 100, Plastic part; 200, First diaphragm; 300, Second diaphragm. Detailed Implementation
[0034] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.
[0035] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.
[0036] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.
[0037] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.
[0038] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values not using relative terms should also be disclosed as specific values with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.
[0039] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.
[0040] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.
[0041] Combination Figure 1 and Figure 2 As shown, the molding method for the metal-bonded foam sandwich structure provided in this embodiment is used to bond the foam core 10 in the sandwich structure to the cavity 21 of the metal skin 20 through molding auxiliary components, thereby improving molding efficiency and reducing molding costs. Specifically, the molding method includes the following steps:
[0042] Step 1: Perform preliminary grinding and fitting of the foam core 10 according to the size, depth and shape of the cavity 21.
[0043] Step 2: First, lay the plastic part 100 in the molding auxiliary component in the gap area of the cavity 21, then pre-assemble the foam core 10 that has been pre-polished and repaired into the cavity 21, and then bag and vacuum process the metal skin 20 in sequence.
[0044] Step 3: After the plastic part 100 in the cavity 21 is shaped, remove the bag and take out the plastic part 100 and the foam core 10 that has been preliminarily polished and repaired. Analyze and record the fit between the plastic part 100 and the inner wall of the cavity 21.
[0045] Step 4: Based on the fit between the plastic part 100 and the inner wall of the cavity 21, the foam core 10 that has been initially ground and fitted is subjected to secondary grinding and fitting until the foam core 10 that has been ground and fitted is reassembled into the cavity 21 and the gap between the foam core 10 and the cavity 21 is smaller than the set gap.
[0046] Step 5: Lay an adhesive film on the inner wall of cavity 21, and assemble the foam core 10, which has been polished and repaired twice, into cavity 21 to form a sandwich structure. Then, the sandwich structure is bagged, vacuumed, and placed in an autoclave to complete the curing.
[0047] Step 6: Remove the sandwich structure from the autoclave.
[0048] During the molding of the sandwich structure, the unformed foam core 10 is first pre-polished and fitted to ensure that the pre-polished and fitted foam core 10 matches the size, depth, and shape of the cavity 21. Then, a plastic part 100 is laid in the corresponding gap area inside the cavity 21, and the pre-polished and fitted foam core 10 is pre-assembled into the cavity 21 where the plastic part 100 is laid. After bagging and full-pressure vacuuming, the plastic part 100 is completely molded. Then, the plastic part 100 is removed, and the fit between the plastic part 100 and the inner wall of the cavity 21 is analyzed. Based on the analysis results, the foam core is polished a second time. 10. After the foam core 10 is placed into the cavity 21, the gap between the foam cores 10 is less than the set gap; then, a film is laid in the cavity 21, and the foam core 10 that has been polished and repaired for the second time is assembled into the cavity 21 to form a sandwich structure. The sandwich structure is then bagged, vacuumed, and placed in a thermostatic jar to complete the curing process. After curing, the sandwich structure is taken out of the thermostatic jar, and the formed sandwich structure is then demolded, repaired, and subjected to non-destructive testing. The sandwich structure that has passed the non-destructive testing is then painted and put into storage. This completes one forming process of the sandwich structure. In this process, the fit between the foam core 10 and the inner wall of the cavity 21 is obtained with the help of the plastic part 100. On the one hand, there is no need for autoclave curing in the whole process, so the entire molding process can save one autoclave curing process, thereby improving molding efficiency and reducing molding cost. On the other hand, before obtaining the fit between the foam core 10 and the inner wall of the cavity 21, there is no need for the adhesive film to come into contact with the foam core 10 and the metal skin 20. Therefore, when obtaining the fit between the foam core 10 and the inner wall of the cavity 21, the situation of adhesive contamination of the foam core 10 or the metal skin 20 can be avoided, thereby further reducing molding cost.
[0049] Preferably, the gap area includes, but is not limited to, the step area, the end rounded corner area, and the edge R-corner area. This ensures the accuracy of the fit between the foam core 10 and the inner wall of the cavity 21, thereby minimizing the gap between the foam core 10 after secondary grinding and fitting and the inner wall of the cavity 21, ensuring that the foam core 10 after secondary grinding and fitting is fully adapted to the inner wall of the cavity 21, and thus ensuring the molding effect of the sandwich structure.
[0050] Preferably, the gap is set to 0.13mm. This avoids a situation where the gap between the foam core 10 and the cavity 21 becomes too large after the foam core 10 has been re-assembled and repaired, resulting in the molded sandwich structure failing to meet the usage requirements.
[0051] In order to prevent the plastic part 100 from contaminating the foam core 10, before the pre-assembled and pre-polished foam core 10 is pre-assembled into the cavity 21, a first diaphragm 200 is laid between the foam core 10 and the plastic part 100, and the foam core 10 and the plastic part 100 are separated by the first diaphragm 200.
[0052] In order to prevent the plastic part 100 from contaminating the metal skin 20, a second diaphragm 300 is laid in the cavity 21 before the plastic part 100 is laid in the gap area, and the plastic part 100 and the inner wall of the cavity 21 are separated by the second diaphragm 300.
[0053] Preferably, before laying the adhesive film on the inner wall of the cavity 21, the metal skin 20 is first phosphoric acid anodized, and the foam core 10, which has been polished and repaired for the second time, is dried.
[0054] Phosphoric acid anodizing treatment is applied to the metal skin 20 to form a porous and uniform oxide film on its surface, thereby improving the adhesion, corrosion resistance, hardness, and electrical insulation of the metal skin 20 to ensure the subsequent molding effect of the sandwich structure. The foam core 10 is dried to prevent the damp foam core 10 from affecting the subsequent molding effect of the sandwich structure.
[0055] Preferably, before the initial sanding and fitting of the foam core 10, the unsanded foam core 10 is placed in the cavity 21, and the area to be sanded is marked. This ensures the accuracy of the sanding area during the initial sanding of the foam core 10, thereby guaranteeing the sanding effect and improving sanding efficiency.
[0056] A molding auxiliary component is used in the molding method of metal-bonded foam sandwich structure. The molding auxiliary component includes a plastic part 100, a first diaphragm 200 and a second diaphragm 300: the plastic part 100 is laid in the cavity 21 of the metal skin 20; the first diaphragm 200 is laid between the plastic part 100 and the foam core 10 assembled in the cavity 21; and the second diaphragm 300 is laid between the plastic part 100 and the inner wall of the cavity 21.
[0057] Since the plastic part 100 is laid inside the cavity 21, the first diaphragm 200 is laid between the plastic part 100 and the foam core 10, and the second diaphragm 300 is laid between the inner wall of the cavity 21 and the plastic part 100, during the molding process of the foam core 10, the fit between the foam core 10 and the inner wall of the cavity 21 can be obtained by using the plastic part 100, which can eliminate one autoclave curing process, thereby improving molding efficiency and reducing molding costs. At the same time, before obtaining the fit between the foam core 10 and the inner wall of the cavity 21, there is no need for the adhesive film to come into contact with the foam core 10 and the metal skin 20, thereby avoiding the situation where the adhesive contaminates the foam core 10 or the metal skin 20 when obtaining the fit between the foam core 10 and the inner wall of the cavity 21, further reducing molding costs. The first diaphragm 200 separates the plastic part 100 and the foam core 10, preventing them from influencing each other and avoiding contamination of the foam core 10 by the plastic part 100 before molding. The second diaphragm 300 separates the plastic part 100 from the inner wall of the cavity 21, preventing them from influencing each other and avoiding contamination of the metal skin 20 by the plastic part 100 before molding, thereby further reducing production costs.
[0058] To ensure the accuracy of obtaining the fit between the foam core 10 and the inner wall of the cavity 21, the molding part 100 is made of a soft, easily moldable, and chemically stable material, including but not limited to memory foam, dough, polymer clay, silicone clay, and modeling clay. In this embodiment, the molding part 100 is set as modeling clay.
[0059] During the molding process, in order to separate the plastic part 100 and the foam core 10 using the first diaphragm 200, and to separate the plastic part 100 and the inner wall of the cavity 21 using the second diaphragm 300, and to prevent the first diaphragm 200 from contaminating the foam core 10 and the second diaphragm 300 from contaminating the metal skin 20, while also preventing the hardness and thickness of the first diaphragm 200 and the second diaphragm 300 from affecting the fit between the foam core 10 and the inner wall of the cavity 21, both the first diaphragm 200 and the second diaphragm 300 are made of chemically stable, highly flexible, and ultra-thin membranes. Specifically, the first diaphragm 200 and the second diaphragm 300 can be selected from polyimide film, polypropylene film, polytetrafluoroethylene film, and graphene film according to the actual situation, without specific limitations here.
[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A method for molding a metal-bonded foam sandwich structure, characterized in that, A molding process for bonding a foam core (10) in a sandwich structure to a cavity (21) of a metal skin (20) using molding auxiliary components, the molding method comprising: S1, the foam core (10) is initially polished and fitted according to the size, depth and shape of the cavity (21); S2, first lay the plastic part (100) in the molding auxiliary component in the gap area of the cavity (21), then pre-assemble the foam core (10) that has been pre-polished and repaired into the cavity (21), and then bag and vacuum process the metal skin (20) in sequence. S3, after the plastic part (100) in the cavity (21) is shaped, remove the bag and take out the plastic part (100) and the foam core (10) that has been preliminarily polished and repaired, analyze and record the fit between the plastic part (100) and the inner wall of the cavity (21); S4. Based on the fit between the plastic part (100) and the inner wall of the cavity (21), the foam core (10) that has been initially polished and fitted is subjected to secondary polishing and fitting until the foam core (10) that has been second-fitted and fitted is second-time assembled into the cavity (21), and the gap between the foam core (10) and the cavity (21) is less than the set gap. S5, lay an adhesive film on the inner wall of the cavity (21), and assemble the foam core (10) that has been polished and repaired twice into the cavity (21) to form a sandwich structure. Then, bag the sandwich structure, vacuum it, and put it into a thermostatic jar to complete the curing. S6, Remove the sandwich structure from the autoclave.
2. The molding method of the metal-bonded foam sandwich structure according to claim 1, characterized in that, The gap area includes a stepped area, a rounded end area, and an edge R-corner area.
3. The molding method of the metal-bonded foam sandwich structure according to claim 1, characterized in that, The set gap is set to 0.13 mm.
4. The molding method of the metal-bonded foam sandwich structure according to claim 1, characterized in that, Before the pre-assembled foam core (10) after preliminary grinding and repair is pre-assembled into the cavity (21), a first diaphragm (200) is laid between the foam core (10) and the plastic part (100).
5. The molding method of the metal-bonded foam sandwich structure according to claim 1, characterized in that, Before the plastic part (100) is laid in the gap region, a second diaphragm (300) is laid in the cavity (21).
6. The molding method of the metal-bonded foam sandwich structure according to claim 1, characterized in that, Before the inner wall of the cavity (21) is covered with adhesive film, the metal skin (20) is first phosphoric acid anodized, and the foam core (10) after secondary grinding and repair is dried.
7. The molding method of the metal-bonded foam sandwich structure according to any one of claims 1-6, characterized in that, Before performing preliminary polishing and repair on the foam core (10), the unpolished foam core (10) is placed in the cavity (21), and the area to be polished is marked.
8. A molding auxiliary component, characterized in that, The molding auxiliary component is applied to the molding method of the metal-bonded foam sandwich structure according to any one of claims 1-7, comprising: A plastic part (100) is laid in the cavity (21) of the metal skin (20); A first diaphragm (200) is laid between the plastic part (100) and the foam core (10) assembled in the cavity (21); A second diaphragm (300) is laid between the plastic part (100) and the inner wall of the cavity (21).
9. The molding auxiliary component according to claim 8, characterized in that, The plastic part (100) is made of modeling clay.
10. The molding auxiliary component according to claim 8, characterized in that, Both the first diaphragm (200) and the second diaphragm (300) are selected from polyimide film, polypropylene film, polytetrafluoroethylene film, and graphene film.