A SAR antenna high-lightweight skin-integrated active mounting plate structure

Abstract

The application discloses a kind of SAR antenna high light-weight skin integrated forming active mounting plate structure, belong to spacecraft structure technical field.It includes integrated processing upper skin, integrated processing lower skin and the honeycomb core filled between the two;At least one structural feature in mounting hole, boss or thin-walled stiffener is formed integrally by machining on the integrated processing upper skin and integrated processing lower skin.The application replaces the traditional embedded part structure by skin integrated forming, and mounting hole, boss and thin-walled stiffener are directly machined on upper and lower skin, not only completely eliminates the additional weight caused by embedded part, but also significantly improves the local stiffness and impact resistance of mounting plate perpendicular to panel direction by the thin-walled stiffener added.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft structure technology, specifically relating to a lightweight integrated active mounting plate structure for SAR antennas, suitable for phased array antennas of spaceborne synthetic aperture radar. Background Technology

[0002] Synthetic Aperture Radar (SAR) is an important tool for aerospace remote sensing. Its phased array antenna typically consists of a large number of radiating elements, radio frequency transceiver components, a feed network, and an active mounting plate. As the core load-bearing structure of the antenna, the active mounting plate needs to achieve structured and modular integration and assembly of the above components, while simultaneously meeting stringent requirements such as lightweight, high rigidity, high dimensional stability, and high surface accuracy.

[0003] Currently, active mounting plates for spaceborne antennas widely adopt a honeycomb sandwich panel structure. This structure is typically formed by bonding and curing an upper skin, a lower skin, and an aluminum honeycomb core filled between them. It has technical advantages such as high specific strength, high specific stiffness, and good thermal insulation performance. The technology is mature and the process is stable.

[0004] However, since the skin is typically a thin-walled structure, it's impossible to directly tap threads to create effective connections. Therefore, traditional processes must use pre-embedded components at locations where electronic equipment or mechanical interfaces need to be installed. This involves pre-setting metal inserts at corresponding positions within the honeycomb core, then bonding them to the upper and lower skins and the honeycomb core using structural adhesive or foam. Connection holes are then machined into these pre-embedded components. For the installation requirements of large-scale phased array antennas, a single mounting plate often needs hundreds or even tens of thousands of mounting holes, requiring a corresponding number of independent pre-embedded components.

[0005] Existing honeycomb sandwich panel structures using embedded parts and their forming methods mainly have the following technical limitations:

[0006] First, the structural local load-bearing capacity is weak. Traditional honeycomb panels mainly rely on the upper and lower skins to bear in-plane tensile and compressive loads, while the honeycomb core bears shear loads. However, they have very poor resistance to concentrated loads perpendicular to the panel direction. When the panels are installed at equipment installation points, support points, or subjected to accidental impacts, they are prone to local panel dents or honeycomb core material crushing failure.

[0007] Secondly, the level of structural lightweighting is limited. To achieve the connection function of each mounting hole, a corresponding independent metal embedded part is required. The cumulative weight of numerous embedded parts severely restricts the lightweight design of the mounting plate, becoming a bottleneck hindering the development of lightweight designs for large-diameter load-bearing applications.

[0008] Third, the production process is complex and has a low degree of automation. The installation of embedded parts usually relies on a lot of manual labor, requiring many tedious steps such as wrapping the embedded parts with foam, drilling holes in the honeycomb core, positioning and assembling the embedded parts, and trimming their shape. The complex process not only results in low production efficiency and long cycle time, but also makes it difficult to guarantee consistent quality, which is not conducive to mass production and automation.

[0009] Fourth, insufficient overall surface accuracy. Differences in the coefficients of thermal expansion exist between the embedded parts and the skin and honeycomb core materials, and cumulative errors occur during the assembly and processing of multiple components, making it difficult to precisely control the surface accuracy of the mounting plate after overall curing. As spaceborne SAR develops towards higher frequencies and higher resolutions, traditional embedded part structures can no longer meet the increasingly stringent surface accuracy requirements.

[0010] Therefore, a new installation structure is urgently needed to solve the above-mentioned technical problems. Summary of the Invention

[0011] To solve the above-mentioned technical problems, the present invention provides a lightweight integrated active mounting plate structure for SAR antennas. By designing the upper and lower skins as an integrated machined structure, mounting holes, bosses and thin-walled reinforcing ribs are directly formed on the skin, thereby completely replacing the traditional independent embedded parts.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] A lightweight integrated active mounting plate structure for SAR antennas includes an integrated upper skin, an integrated lower skin, and a honeycomb core between the two. The integrated upper and lower skins are integrally formed by machining at least one of the following structural features: threaded mounting holes, bosses, or thin-walled reinforcing ribs. The integrated upper and lower skins are bonded to the honeycomb core by hot pressing and molding, and the whole structure has no independent embedded parts.

[0014] Furthermore, the thin-walled reinforcing ribs run vertically through the entire structure and are connected to the honeycomb core by adhesive bonding. Their distribution principle is as follows: horizontal and vertical in the panel direction, vertically through the panel direction, sparsely distributed in non-load-bearing areas, and densely distributed in load-bearing areas.

[0015] Furthermore, the cross-sectional shape of the thin-walled reinforcing rib is any one of rectangular, trapezoidal, U-shaped, or cap-shaped, and its wall thickness is consistent with the thickness of the honeycomb core, ensuring that the upper and lower skins are completely connected.

[0016] Furthermore, the thin-walled reinforcing ribs adopt a gradient layout, with increased rib density around the threaded mounting holes, around the electrical connector mounting holes, and in the projection area of ​​the antenna radiating unit connecting boss, and relaxed rib density in non-functional areas.

[0017] Furthermore, the integrated upper skin has a boss structure integrally machined on the side opposite to the thin-walled reinforcing rib, which is fixedly connected to the antenna radiating unit. The boss structure and the skin are integrally formed.

[0018] Furthermore, the forming process of the integrated upper skin and the integrated lower skin includes roughing, semi-finishing and finishing processes in sequence, and a vacuum suction cup tool is used to fix the parts during the processing.

[0019] Furthermore, the material of the integrated upper skin and the integrated lower skin is aluminum alloy 5A06-T651, and the specifications of the honeycomb core are a side length of 4 mm and a foil thickness of 0.05 mm.

[0020] Furthermore, the cylindrical root of the threaded mounting hole and the electrical connector mounting hole is provided with a process fillet.

[0021] Furthermore, the integrated upper skin and the integrated lower skin are bonded to the honeycomb core by a modified epoxy structural adhesive film, and then cured under pressure and heat in an autoclave or hot press.

[0022] Furthermore, the thin-walled reinforcing ribs are arranged using a periodic grid topology, which can be any one of an orthogonal grid, a rhombic grid, or a hexagonal honeycomb grid.

[0023] The beneficial effects of this invention are as follows:

[0024] First, it significantly improves the local stiffness of the structure. This invention adds thin-walled reinforcing ribs that run vertically through the integrated skin, which significantly enhances the resistance of the mounting plate to compression and impact in the direction perpendicular to the panel, effectively solving the problems of panel denting and core material crushing that easily occur at connection points and support points in traditional honeycomb sandwich structures.

[0025] Secondly, it achieves high-efficiency and lightweight structure. Mounting holes and bosses are directly formed through integrated skin machining, completely replacing traditional separate metal embedded parts. For the tens of thousands of mounting holes in large-scale array antennas, this structure eliminates the accumulated weight of embedded parts, significantly improving the load-bearing capacity.

[0026] Third, it is suitable for automated mass production. The upper and lower skins are formed by integral CNC milling, which greatly reduces tedious processes such as manual pre-embedding, foaming, and trimming, reduces reliance on operator experience, and significantly improves product consistency and batch production efficiency.

[0027] Fourth, the overall surface shape accuracy is high. Thanks to the overall processing of the skin and the limiting effect of the evenly distributed thin-walled reinforcing ribs in the direction perpendicular to the panel, the overall deformation of the mounting plate after curing is small and the surface shape accuracy is high, which can meet the stringent structural accuracy requirements of high-frequency, high-resolution spaceborne phased array antennas.

[0028] Fifth, it facilitates electromechanical and thermal integration. The skin can be directly and integrally machined with boss structures that are fixed to components such as radiating elements, reducing the use of adapter fasteners and providing a structural basis for lightweight and integrated antenna product design. Attached Figure Description

[0029] Figure 1 A schematic diagram illustrating the structural principle of a traditional pre-embedded honeycomb sandwich panel;

[0030] Figure 2 This is a schematic diagram illustrating the structural principle of the integrated molded honeycomb sandwich panel proposed in this invention.

[0031] Figure 3 This is an exploded structural diagram of an integrated active mounting plate structure for a lightweight SAR antenna skin according to the present invention.

[0032] Figure 4 This is a schematic diagram of the integrated processing skin structure in this invention;

[0033] Figure 5 This is a schematic diagram illustrating the connection between the active mounting plate and the antenna radiating unit of the present invention.

[0034] Figure label:

[0035] 1. Upper skin, 2. Honeycomb core, 3. Lower skin, 4. Fully embedded parts, 5. Semi-embedded parts;

[0036] 6. Integrated processing of upper skin; 7. Integrated processing of lower skin;

[0037] Thin-walled reinforcing rib 8, threaded mounting hole 9, electrical connector mounting hole 10, antenna radiating element 11, boss structure 12. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] The principle of traditional pre-embedded honeycomb sandwich structure is as follows: Figure 1As shown, the upper skin 1 and the lower skin 3 are filled with honeycomb core 2 and are glued together. The key feature is that the upper skin 1 and the lower skin 3 are both thin-walled structures of equal thickness, which cannot directly form effective connecting threads. Therefore, all positions on the mounting plate that require mechanical interfaces must be provided with embedded parts. The embedded parts are in the form of full embedded parts 4 and semi-embedded parts 5. During the assembly process, foaming adhesive is added appropriately in the gaps as needed to improve the rigidity of the entire plate.

[0040] This invention proposes a lightweight, integrated active mounting plate structure for SAR antennas, replacing the traditional pre-embedded honeycomb sandwich panel structure. Its configuration principle is as follows: Figure 2 As shown. An integrated upper skin 6 and an integrated lower skin 7 replace the traditional thin-walled skin of equal thickness. The two are filled with a honeycomb core 2 and then bonded together by hot pressing. Unlike traditional structures that rely on embedded parts, the mounting holes and connection structures of this invention are directly machined integrally onto the skin, eliminating the need for any embedded parts. This integrated machining fundamentally replaces the embedded parts approach, significantly reducing the weight of the mounting plate. Large phased array SAR antennas have a very large scale and number of channels; the active mounting plate of a full-array antenna often has tens of thousands of holes. Without loss of generality, for a single 1m × 1.6m honeycomb panel with nearly 1300 holes, the surface density of a traditional honeycomb panel is approximately 4kg / m³. 2 Each embedded part and adhesive weighs approximately 0.005 kg. Therefore, the total weight of this traditional honeycomb panel is 1300 × 0.005 kg + 1m × 1.6m × 4 kg / m. 2 =12.9kg, while by using integrated processing instead of embedded parts, the total weight of the honeycomb panel is 8.9kg, a weight reduction of more than 30%, which is a significant effect.

[0041] An exploded view of the lightweight, integrated active mounting plate structure of the SAR antenna of this invention is shown below. Figure 3 As shown, the assembly relationship between the integrated upper skin 6, the integrated lower skin 7, and the honeycomb core 2 filling between them is more clearly demonstrated. The upper and lower skins are formed by integral CNC milling, which greatly reduces manual pre-embedding, foaming, and trimming operations, and is conducive to realizing the mass automated production of active mounting plates.

[0042] The integrated machining of the upper skin (6) and lower skin (7) requires a vacuum suction cup fixture with leak-proof protection to fix the parts during machining, replenish coolant in a timely manner, and gradually complete the roughing, semi-finishing, and finishing processes to ensure the flatness of the parts and address the stretching issues of the skin during machining. The skin material is aluminum alloy 5A06-T651, which has low residual stress during machining, ensuring better machining accuracy and making it more suitable for integrated thin-walled complex structures. The aluminum honeycomb core specifications are 4mm side length and 0.05mm foil thickness.

[0043] Traditional pre-embedded honeycomb panels often only have vertically continuous support points at the fully pre-embedded parts, resulting in poor rigidity of the entire installation panel in the direction perpendicular to the panel. Figure 4 The integrated fabrication skin structure proposed in this invention can be reinforced with thin-walled stiffeners 8 running vertically through the entire structure, as needed for strength. These stiffeners are bonded to the honeycomb core 2 using adhesive bonding, enhancing the resistance to concentrated loads perpendicular to the panel direction. The distribution principle of the thin-walled stiffeners 8 is that they are horizontally and vertically aligned within the panel direction, running vertically perpendicular to the panel direction, sparsely distributed in non-load-bearing areas, and densely distributed in load-bearing areas. For example, the layout can adopt a periodic grid topology, including but not limited to orthogonal grids, rhomboid grids, or hexagonal honeycomb grids. Among them, orthogonal grids are suitable for scenarios mainly bearing bidirectional orthogonal loads; rhomboid grids are suitable for areas dominated by shear loads; and hexagonal grids can achieve optimal equal stiffness distribution.

[0044] To further optimize the balance between lightweight effect and stiffness improvement, the cross-sectional shape of the thin-walled reinforcing rib 8 is not limited to rectangle; trapezoidal, U-shaped, or cap-shaped cross-sections can be used. Rectangular cross-sections are simple to process, while trapezoidal or U-shaped cross-sections can further reduce stress concentration at the root. In the thickness direction, the wall thickness of the thin-walled reinforcing rib 8 is consistent with the thickness of the honeycomb core 2, ensuring complete connection between the upper and lower skins. Finite element analysis shows that, compared to traditional structures without reinforcing ribs, the local compressive stiffness of the structure of this invention is increased several times under the same areal density. The increased stiffness of the mounting plate perpendicular to the panel effectively solves the problems of panel indentation and core material crushing at connection and support points when traditional pre-embedded honeycomb panels are subjected to local compression and impact. In addition, on the same side of the thin-walled reinforcing rib 8, the skin also has an integrally machined ordinary thread mounting hole 9 and an electrical connector mounting hole 10. Since the skin is very thin, in order to prevent the machining process from causing the ordinary thread mounting hole 9 and the electrical connector mounting hole 10 at the cylinder root, which would lead to root cutting, a process fillet can be added to the cylinder root to improve the reliability of the integrated skin machining process.

[0045] Furthermore, based on the mechanical requirements of different installation areas, the thin-walled reinforcing ribs 8 can adopt a gradient layout: around the threaded mounting holes 9, around the electrical connector mounting holes 10, and within the projection area of ​​the antenna radiating unit 11 connecting boss structure 12, the density of the thin-walled reinforcing ribs 8 is increased to a grid side length ≤ 20mm; in non-functional areas, the grid side length can be widened to 50-100mm. This variable density design can effectively improve local stiffness with minimal increase in weight.

[0046] Traditional pre-embedded honeycomb sandwich panels have a low degree of automation in assembly and inspection, especially the pre-installation process of embedded parts, which relies heavily on manual operation. The SAR antenna high-lightweight integrated active mounting plate structure proposed in this invention has its upper and lower skins integrally milled, making full use of the advantages of CNC machining, significantly reducing the manual operation process, and is suitable for mass automated production of active mounting plates.

[0047] Thanks to the integrated manufacturing process and the limiting effect of the thin-walled reinforcing ribs that are evenly distributed in the horizontal and vertical directions on the skin and run vertically to the panel direction, the mounting plate configuration proposed in this invention has high overall surface accuracy and is suitable for use in high-frequency high-precision phased array antennas.

[0048] Figure 5 The connection method between the active mounting plate and the antenna radiating element of the present invention is shown. The integrated upper skin 6 is designed as a single unit to meet the electrical requirements of the phased array antenna. A boss structure 12, which is fixed to the antenna radiating element 11, can be directly machined onto the upper skin 6 (on the side opposite to the thin-walled reinforcing rib 8). This integral molding ensures that the skin and the boss structure 12 are a single unit, reducing the use of fasteners such as adapter screws and facilitating the lightweighting of large phased array antennas. The antenna electrical connector can be directly connected to this structure through the electrical connector mounting hole 10, contributing to the electromechanical integration of the antenna product.

[0049] In summary, this invention replaces the traditional embedded part structure with an integrated upper and lower skin molding, effectively reducing the structural weight, improving local stiffness and overall surface accuracy, and simplifying the production process. It has significant application value for high-frequency, lightweight spaceborne phased array antennas.

[0050] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lightweight, integrated active mounting plate structure for SAR antenna skin, characterized in that, It includes an integrated upper skin, an integrated lower skin, and a honeycomb core filled between the two; the integrated upper skin and the integrated lower skin are integrally formed by machining at least one of the following structural features: threaded mounting holes, bosses, or thin-walled reinforcing ribs; the integrated upper skin and the integrated lower skin are bonded to the honeycomb core by hot pressing, and the whole has no independent embedded parts.

2. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 1, characterized in that, The thin-walled reinforcing ribs run through the entire structure from top to bottom and are connected to the honeycomb core by adhesive bonding. Their distribution principle is as follows: horizontal and vertical in the panel direction, vertical and vertical in the vertical panel direction, sparsely distributed in non-load-bearing areas, and densely distributed in load-bearing areas.

3. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 2, characterized in that, The cross-sectional shape of the thin-walled reinforcing rib can be any one of rectangular, trapezoidal, U-shaped, or cap-shaped, and its wall thickness is consistent with the thickness of the honeycomb core, ensuring that the upper and lower skins are completely connected.

4. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 2, characterized in that, The thin-walled reinforcing ribs are arranged in a gradient pattern. The density of the reinforcing ribs is increased around the threaded mounting holes, around the electrical connector mounting holes, and in the projection area of ​​the antenna radiating unit connecting boss, while the density of the reinforcing ribs is relaxed in the non-functional areas.

5. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 1, characterized in that, The integrated processing of the upper skin has a boss structure integrally processed on the side away from the thin-walled reinforcing rib, which is fixed to the antenna radiating unit. The boss structure and the skin are integrally formed.

6. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 1, characterized in that, The forming process of the integrated upper skin and the integrated lower skin includes roughing, semi-finishing and finishing processes in sequence. During the processing, a vacuum suction cup tool is used to fix the parts.

7. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 1, characterized in that, The integrated upper and lower skins are made of aluminum alloy 5A06-T651, and the honeycomb core has a side length of 4 mm and a foil thickness of 0.05 mm.

8. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 1, characterized in that, The cylindrical root of the threaded mounting hole and the electrical connector mounting hole is provided with a process fillet.

9. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 1, characterized in that, The integrated upper skin and integrated lower skin are bonded to the honeycomb core by a modified epoxy structural adhesive film, and then cured under pressure and heat in an autoclave or hot press.

10. The SAR antenna high-lightweight integrated active mounting plate structure with skin according to claim 2, characterized in that, The thin-walled reinforcing ribs are arranged using a periodic grid topology, which can be any one of an orthogonal grid, a rhombic grid, or a hexagonal honeycomb grid.

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