Main support structure and fabrication method of large off-axis three-lens space mapping camera

Abstract

This invention relates to the field of space camera support structure technology, and particularly to a main support structure for a large off-axis three-lens reflex space mapping camera and its fabrication method. It includes: a bottom frame layer and a top frame layer arranged opposite each other and fixedly connected to a support rib assembly; a skin covering the outer surface of the support rib assembly; the support rib assembly being a grid-shaped structure with horizontally and vertically crisscrossing support ribs; protruding mirror cavity platforms pre-set in the optical element mounting areas of the bottom and top frame layers, connected to the optical elements via embedded parts on the protruding mirror cavity platforms; the bottom frame layer integrating several satellite platform interfaces and connected to the satellite platforms; the bottom frame layer, skin, top frame layer, and support rib assembly are all made of carbon fiber composite material, and the embedded parts are made of titanium alloy. Advantages include: an integrated layout resulting in a more compact structure; horizontal support ribs that can replace the camera aperture to suppress stray light; and further reduction in camera weight, achieving high strength and lightweight design.

Description

Technical Field

[0001] This invention relates to the field of space camera support structure technology, and in particular to a main support structure for a large off-axis three-lens reflex space mapping camera and its manufacturing method. Background Technology

[0002] Optical cameras are a crucial payload for space optical remote sensors, and the quality of their imaging directly impacts the sensor's performance. From design and manufacturing to assembly, testing, transportation, launch, and on-orbit operation, space cameras must withstand various external loads and environmental factors, thus placing high demands on the camera's dynamic and static mechanical properties and its adaptability to the space environment.

[0003] Space off-axis three-lens reflex cameras, with their large field of view and long focal length, can simultaneously achieve high resolution and wide swath imaging. However, as the performance of off-axis three-lens reflex space remote sensing cameras improves, their external envelope size also needs to increase. Furthermore, the significantly increased requirements for camera structural stability and the exacerbation of structural asymmetry have become the main factors affecting image quality. Therefore, the rational design of the camera's main support structure is the key to the development of large-scale space off-axis three-lens reflex cameras.

[0004] The design of the main support structure for a space remote sensing camera requires the stable and reliable support and fixation of optical components, focal plane assemblies, and light shields within the optical system. Under the influence of mechanical, thermal, and other complex loads from the external environment, the relative positional accuracy of the optical components within the space camera must remain unchanged to ensure the imaging quality of the optical system. Currently, the main support structures used in off-axis three-lens space cameras, both domestically and internationally, are primarily frame-type and truss-type structures. Frame-type support structures come in various forms, including integral and modular designs, while truss-type structures connect the front and rear back plates using truss struts to form the main support structure of the camera. The optical remote sensor carried by the US QuickBird-2 satellite and the ALI camera carried by the EO-1 satellite both employ thin-walled frame-type main support structures. A typical example of a space camera truss support structure is the Hubble Telescope (HST), while the independent mapping camera developed by Japan uses an inner and outer double-truss main support structure. The main support structure of the off-axis three-lens space camera developed in China is nothing more than a frame structure and a truss structure. The high-resolution camera carried by my country's Gaofen-6 satellite adopts a thin-walled frame structure. Its main frame has external dimensions of 1050mm×800mm×950mm. The support structure as a whole is made of high volume aluminum-based composite material. The Mars exploration remote sensing camera adopts a truss support structure. The truss rods and the light shield are made of carbon fiber composite material, and the front and rear back plates and rod joints are made of titanium alloy material.

[0005] Given the characteristics of large off-axis three-mirror optical systems, the manufacturing of an integral frame support structure is quite difficult. Therefore, frame support structures are mostly manufactured using modular molding. Typically, the main camera support is divided into three parts: a front frame, a middle support frame, and a rear frame. The front and rear frames, as multi-interface structural components of the camera, are often made of titanium alloy, while the middle support is made of carbon fiber composite material. Frame support structures offer good overall integrity, high stability, and simple assembly and adjustment, making them suitable for medium and large-sized space cameras. However, as the main support structure for large off-axis three-mirror cameras, their weight accounts for a significant portion, affecting the optimized design of other optical and mechanical structural components of the space camera, and consequently impacting the launch cost. Among large-scale space remote sensing cameras both domestically and internationally, the most typical use of carbon fiber composite materials for the main camera support structure is the truss structure. Truss structures use carbon fiber two-force members as the main support units, easily achieving high lightweight design in large spaces. However, they have disadvantages in terms of overall integrity and stability. The first-order resonant frequency of truss structures is relatively low, posing a stability risk when applied to large-scale space remote sensing cameras that are more sensitive to changes in structural dimensions. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a main support structure for a large off-axis three-lens reflex spatial mapping camera and its fabrication method.

[0007] The primary objective of this invention is to provide a main support structure for a large off-axis three-lens reflex spatial mapping camera, comprising a bottom frame layer, a skin, a top frame layer, a support rib assembly, and embedded parts;

[0008] The bottom layer of the frame and the top layer of the frame are arranged opposite to each other and are respectively fixedly connected to the support rib assembly; the skin is an enclosing structure that covers the outer surface of the support rib assembly; the support rib assembly is a grid-shaped support rib that is evenly distributed horizontally and vertically.

[0009] The bottom layer and the top layer of the frame each have an externally protruding mirror cavity platform pre-set in the optical element mounting area, and are connected to the optical element through the pre-embedded parts pre-embedded on the externally protruding mirror cavity platform; the bottom layer of the frame integrates several satellite platform interfaces, and is connected to the satellite platform through the satellite platform interfaces;

[0010] The bottom layer of the frame, the skin, the top layer of the frame, and the support rib assembly are all made of carbon fiber composite material, and the embedded parts are made of titanium alloy material.

[0011] Preferably, the main support structure of the large off-axis three-lens spatial mapping camera is a tower-shaped structure with a rounded bottom and an upper top;

[0012] The satellite platform has six interfaces.

[0013] Preferably, the primary mirror group and the three-mirror group are mounted in the optical element mounting area of ​​the bottom layer of the frame;

[0014] The bottom layer of the frame consists of a surface layer, reinforcing ribs, and an inner layer. The surface layer and the inner layer are plate-shaped support surfaces of the outer and inner layers, respectively. The reinforcing ribs are vertically connected to the surface layer and the inner layer, and a closed-cavity triangular structure is formed through co-curing.

[0015] Preferably, the optical element mounting area on the top layer of the frame is used to mount the secondary lens group, the folding lens group, and the camera lens hood.

[0016] Preferably, the support rib assembly includes transverse support ribs and longitudinal support ribs, which are evenly distributed inside the skin in a crisscross pattern to form multiple sets of grid-shaped support ribs.

[0017] The thickness of the reinforcing rib is a mm, where 0.3 mm ≤ a ≤ 1.5 mm; the thickness of the surface layer and the inner layer is the same, which is 4 to 6 times the thickness of the reinforcing rib.

[0018] Preferably, the skin, the transverse support ribs, and the longitudinal support ribs have the same thickness, which is twice the thickness of the reinforcing ribs.

[0019] The second objective of this invention is to provide a method for fabricating a main support structure for a large off-axis three-lens reflex space mapping camera, specifically comprising the following steps:

[0020] S1. Pre-compacting of the cavity support rib assembly: Process the metal mold block, brush two coats of high-temperature release agent on the outer surface of the metal mold block; lay T800 / cyanate ester prepreg on the outer surface of the pretreated metal mold block; assemble each metal mold block with the core mold inner cylinder;

[0021] S2. Pre-compaction of closed-cavity reinforcing ribs; including:

[0022] S201. First, apply two coats of waterproof adhesive to the outer surface of the water-soluble core mold; after the waterproof adhesive has completely dried, apply two coats of high-temperature release agent to the dried outer surface of the water-soluble core mold.

[0023] S202. Lay T800 / cyanate prepreg on the outer surface of the water-soluble core mold, with the layup angle and layup thickness being the same as in step S1; according to the preset positioning relationship, connect and assemble the water-soluble core mold with the prepreg laid on it to the metal core mold support structure; at the same time, design and reserve process holes on the closed cavity reinforcing rib structure.

[0024] S3. Fabrication of the framework layer and skin structure; including:

[0025] S301. After assembling the pre-compacted structure from steps S1 and S2, lay M55 / cyanate ester prepreg at the bottom and top to form the surface structure of the bottom layer and top layer of the frame.

[0026] S302. Lay M55 / cyanate ester prepreg on the outer surface of the support rib assembly to form the skin until the total skin thickness reaches 2mm; perform a vacuum pre-compaction operation every 4 layers of prepreg.

[0027] S303. Embedding of pre-embedded parts at the stress-bearing connection points of the skin structure;

[0028] S304. For flange areas where the thickness is inconsistent with the skin, M55 / cyanate ester prepreg is used for symmetrical cyclic laying and molding to reduce internal stress and prevent deformation; at the same time, machining allowance is reserved at the outer edge of the flange.

[0029] S4. Co-curing molding: After the skin is laid out, a metal mold-fitting process is used to close the mold, so that the support rib assembly, reinforcing ribs and skin are co-cured;

[0030] S5. Once the curing system has cooled to below 35°C, remove the product from the curing equipment; once the mold temperature has dropped to below 28°C, remove the metal mold block, and then remove the water-soluble core mold from the reserved process hole in the closed-cavity reinforcing rib structure; grind the interface area and perform hole-making treatment on the locations where holes need to be opened;

[0031] S6. Use room temperature curing epoxy adhesive to bond the connection surfaces of the main support structure and the accessories. The adhesive will cure at room temperature. After bonding, use bolts for auxiliary fixation to finally complete the overall assembly.

[0032] Preferably, in steps S1 and S2, the time interval between the two applications of the high-temperature release agent is 40-55 minutes, and the ambient temperature is maintained at 20-25°C and the relative humidity is below 45% during the process; the layup angle of the T800 / cyanate prepreg is set to (0° / 45° / 90° / -45°)n, and the layup thickness is 1 / 2 of the total thickness of the support rib assembly; wherein, n≥1;

[0033] In step S3, the layup angle of the M55 / cyanate prepreg is set to (0° / 60° / 90° / -60°)n, where n≥1;

[0034] The high-temperature resistant release agent includes polytetrafluoroethylene release agents or siloxane release agents;

[0035] The metal mold block is made of aluminum alloy.

[0036] Preferably, in step S201, the interval between the two applications of waterproof adhesive is 30-45 minutes, and the ambient temperature is controlled at 25-30℃ and the relative humidity is 30-45%.

[0037] Preferably, the co-curing regime in step S4 is set as follows: 100℃ / 2h; 120℃ / 2h; 150℃ / 2h; 180℃ / 1h; 230℃ / 2h; and the heating rate is controlled to be less than 0.5℃ / min and the cooling rate is controlled to be less than 0.3℃ / min during the co-curing process.

[0038] The adhesive curing time in step S6 is 40~50h; during the auxiliary fixing process, a torque wrench is used to control the tightening torque to ensure that the torque range is between 5~45N•m.

[0039] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0040] This invention provides a high-rigidity, low-weight, and high-dimensional-stability main support structure for a large off-axis three-lens reflex spatial mapping camera and its fabrication method. It solves the technical pain points of existing large off-axis three-lens reflex frame-type main support structures, which are characterized by large mass, complex manufacturing, and low overall stability of truss-type main support structures. The camera main support structure belongs to a frame-type support structure system and is mainly made of carbon fiber composite materials and titanium alloy materials. Based on the inherent characteristics of carbon fiber materials, a series of process measures and structural design forms are adopted to fully utilize the advantages of carbon fiber composite materials, so that the camera main support frame has the characteristics of simple and compact structure, excellent strength and rigidity, high lightweight ratio, and good dimensional stability. Furthermore, the main support structure of the camera adopts an integrated design concept of structural function reuse. The horizontal support ribs not only undertake the function of horizontal connection and support, but also replace the camera aperture to suppress stray light, further reducing the overall weight of the camera and effectively improving the structural function density ratio. It can not only provide a stable and reliable installation interface for optical elements and functional components, but also adapt to the requirements of multi-mirror interface arrangement, optical path obstruction and assembly space brought about by the integrated layout of front and rear downward-looking cameras of the dual-line array stereo mapping camera, ultimately reducing the launch cost and having significant practical value and promotion significance. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the main support structure of a large off-axis three-lens reflex spatial mapping camera according to an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the bottom layer of the frame provided according to an embodiment of the present invention.

[0043] Figure 3 This is a schematic diagram of the top layer of the frame provided according to an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram of a single off-axis three-lens space camera provided according to an embodiment of the present invention.

[0045] Figure label:

[0046] 1. Bottom layer of the framework;

[0047] 101. Surface layer; 102. Reinforcing rib; 103. Inner layer;

[0048] 2. Skin;

[0049] 3. Top layer of the frame;

[0050] 4. Horizontal support ribs;

[0051] 5. Longitudinal support bars;

[0052] 6. Embedded parts;

[0053] 7. Primary lens assembly;

[0054] 8. Three-lens system;

[0055] 9. Satellite platform interface;

[0056] 10. Secondary lens group;

[0057] 11. Folding lens assembly;

[0058] 12. Camera lens hood. Detailed Implementation

[0059] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0061] For dual-line array stereo mapping cameras, the support structure must consider not only factors such as weight, rigidity, and stability, but also issues such as the increased mirror interface arrangement, optical path obstruction, and assembly / adjustment space resulting from the integrated layout of the front and rear downward-looking cameras. Based on these issues, this invention provides an integrated dual-support large-scale off-axis three-mirror spatial mapping camera main support structure, such as... Figures 1-3 As shown; Figure 1The overall structure is shown, including a bottom frame layer 1, a skin 2, a top frame layer 3, a support rib assembly, and embedded parts 6. The top frame layer 3 and the bottom frame layer 1 are arranged opposite each other and are fixedly connected to the support rib assembly respectively. The skin 2 is connected to the bottom frame layer 1, the top frame layer 3, and the support rib assembly respectively, covering the outer surface. According to the size and envelope volume requirements of the space camera optical system, it is rationally shaped and removed along the optical path to obtain the initial configuration of the main support structure of the large off-axis three-mirror space mapping camera with integrated double support. The overall structure is a tower-like structure with a round bottom and an upper top.

[0062] The support rib assembly includes transverse support ribs 4 and longitudinal support ribs 5. The transverse support ribs 4 and longitudinal support ribs 5 are evenly distributed inside the skin 2 in a crisscross pattern, forming multiple sets of grid-shaped support ribs. This evenly disperses the force flow between the bottom layer 1 and the top layer 3 of the frame, improving the support structure's resistance to compression and shear, and reducing bending deflection. The grid-shaped layout, together with the skin 2, encloses a specific optical path channel. Its shape and position design directly replace the aperture component of a traditional camera, achieving optical path blocking inside the support structure and avoiding stray light interference with imaging quality. This achieves integrated reuse of structural support and aperture functions, reducing the weight and assembly process of additional aperture components.

[0063] The bottom layer 1 of the frame has a pre-set convex mirror cavity platform in the optical element mounting area. Through the pre-embedded parts 6 embedded in the convex mirror cavity platform, a high-precision connection with the main mirror group 7 and the three mirror groups 8 is achieved. The bottom layer 1 of the frame integrates several satellite platform interfaces 9. Through the satellite platform interfaces 9, the entire space mapping camera is stably mounted on the satellite platform, realizing the integration of the camera and the satellite platform.

[0064] In a specific embodiment, the number of satellite platform interfaces 9 is 6;

[0065] In a specific embodiment, the embedded part 6 serves as a transitional connector between the carbon fiber frame and the optical elements, which not only avoids direct stress damage to the carbon fiber, but also ensures the spatial position accuracy of the primary lens group 7 and the three-lens group 8 through its high-precision processing characteristics.

[0066] like Figure 2 As shown, the bottom layer 1 of the frame is formed by the co-curing of the surface layer 101, the reinforcing rib 102, and the inner layer 103 to form a closed-cavity triangular structure. Specifically, the surface layer 101 and the inner layer 103 are the plate-shaped support surfaces of the outer and inner layers, respectively. The reinforcing rib 102 is located between the two and vertically connects the surface layer 101 and the inner layer 103. The three together form multiple sets of triangular closed-cavity units, which greatly improves the bending and shear resistance of the bottom layer 1 of the frame.

[0067] Among them, the thickness of the reinforcing rib 102 is a mm, 0.3 mm ≤ a ≤ 1.5 mm; the thickness of the surface layer plate 101 and the inner layer plate 103 is the same, which is 4 to 6 times the thickness of the reinforcing rib 102, and the thickness is (4 to 6) a mm;

[0068] The skin 2, the transverse support 4, and the longitudinal support 5 have the same thickness, which is twice the thickness of the reinforcing rib 102, and the thickness is 2amm.

[0069] like Figure 3 As shown, the top layer 3 of the frame is the connecting layer for the optical element secondary lens group 10, the folding lens group 11, and the camera lens hood 12.

[0070] The top layer 3 of the frame has a pre-set convex mirror cavity platform in the optical element mounting area. Through the pre-embedded parts on the convex mirror cavity platform, a high-precision connection is achieved with the secondary mirror group 10, the folding mirror group 11, and the camera lens hood 12.

[0071] Specifically, the bottom layer 1, skin 2, top layer 3, and support rib assembly of the frame are made of carbon fiber composite material, while the embedded part 6 is made of titanium alloy.

[0072] The fabrication method of the aforementioned large off-axis three-lens reflex spatial mapping camera main support structure specifically includes the following steps:

[0073] S1. Pre-compactment of the cavity support rib assembly (transverse support ribs and longitudinal support ribs):

[0074] S101. Pretreatment of metal mold blocks: In accordance with the design requirements of the main support structure of a large off-axis three-lens reflex spatial mapping camera, aluminum alloy is used to process the metal mold blocks. To avoid adhesion during subsequent demolding, two coats of high-temperature release agent are brushed onto the outer surface of the metal mold blocks, with the time interval between the two coats controlled at 40~55 minutes. Throughout the pretreatment process, the ambient temperature is kept at 20~25℃ and the relative humidity is kept below 45% to ensure that the high-temperature release agent is evenly adhered and fully dried.

[0075] Specifically, high-temperature resistant mold release agents include polytetrafluoroethylene (PTFE) mold release agents or siloxane (siloxane) mold release agents.

[0076] S102. On the outer surface of the pretreated metal mold block, lay T800 / cyanate prepreg (thickness 0.1~0.2mm) to form the support rib structure. The layup angle is set to (0° / 45° / 90° / -45°)n, and the layup thickness is 0.5mm (i.e., 1 / 2 of the total thickness of the support rib). During the layup process, the metal mold is pre-compacted to remove air bubbles between the prepreg layers and improve the structural density. After the support rib prepreg is laid, assemble each aluminum alloy metal mold block with the core mold inner cylinder. To ensure assembly accuracy, pins are used for positioning between the metal mold block and the core mold inner cylinder to ensure that the relative positions of each component meet the design requirements. Wherein, n≥1.

[0077] S2. Pre-compacting of closed-cavity reinforcing ribs:

[0078] S201. Pretreatment of water-soluble core mold: To avoid the moisture on the outer surface of the water-soluble core mold affecting the curing effect of the prepreg, first apply two coats of waterproof adhesive to the outer surface of the water-soluble core mold, with an interval of 30-45 minutes between the two coats. The ambient temperature should be controlled at 25-30℃ and the relative humidity at 30-45%. After the waterproof adhesive has completely dried, apply two coats of high-temperature release agent to the dried outer surface of the water-soluble core mold, with an interval of 40-55 minutes between the two coats. The ambient temperature should be maintained at 20℃-25℃ and the relative humidity at less than 45% to ensure that the surface treatment of the core mold meets the standards.

[0079] S202. On the outer surface of the pretreated water-soluble core mold, lay T800 / cyanate prepreg with a layup angle of (0° / 45° / 90° / -45°)n and a layup thickness of 0.5mm, consistent with the layup parameters of the prepreg for the open-cavity reinforcing rib to ensure uniform structural performance of the reinforcing rib; according to the preset positioning relationship, connect and assemble the water-soluble core mold with the prepreg laid on it to the metal core mold support structure; at the same time, design and reserve process holes on the closed-cavity reinforcing rib structure to facilitate the removal of the internal water-soluble core mold after subsequent product molding; where n≥1;

[0080] After pre-compaction, an internal reinforcement structure is formed in the bottom and top layers of the frame.

[0081] S3. Fabrication of the framework layer and skin structure; specific steps are as follows:

[0082] S301. After assembling the pre-compacted structure from steps S1 and S2, lay M55 / cyanate ester prepreg at the bottom and top to form the surface structure of the bottom layer and top layer of the frame.

[0083] S302. Lay M55 / cyanate ester prepreg (single layer thickness 0.1mm) on the outer surface of the support rib assembly to form the skin. The layup angle is set to (0° / 60° / 90° / -60°)n until the total skin thickness reaches 2mm. To remove interlayer gas and ensure skin density, perform a vacuum pre-compaction operation every 4 layers of prepreg. Wherein, n≥1.

[0084] S303. Embedded parts: Precisely embed titanium alloy embedded parts at the stress connection points of the skin structure (corresponding to the optical component mounting positions and satellite platform interface positions) to ensure that the position of the embedded parts matches the connection requirements of subsequent components, laying the foundation for high-precision connection;

[0085] S304. Special treatment for flange area: For areas where the flange and skin thickness are inconsistent, M55 / cyanate ester prepreg is used for symmetrical cyclic laying and molding. This process reduces the internal stress of the flange and avoids structural deformation due to thermal stress release after the flange is cured. At the same time, a 5mm machining allowance is reserved on the outer edge of the flange, which is removed after the product is cured and demolded to release the residual stress inside the product and improve the dimensional stability during operation.

[0086] To ensure the structural strength of the skin, the circumferential continuity of the fibers is maintained during the prepreg laying process to fully utilize the mechanical properties of the fibers.

[0087] S4. Co-curing molding: After the skin is laid out, the product is molded using a metal-on-molding process; a mold-on-molding curing process is used to co-cur the supporting rib assembly, reinforcing ribs and skin, which can ensure the product's structural dimensions and surface roughness; the curing regime is set as follows: 100℃ / 2h; 120℃ / 2h; 150℃ / 2h; 180℃ / 1h; 230℃ / 2h; and during the co-curing process, the heating rate is controlled to be less than 0.5℃ / min and the cooling rate to be less than 0.3℃ / min, further reducing the internal residual stress of the product;

[0088] S5. Demolding and Post-processing: After the cured system cools down to below 35℃, remove the product from the curing oven; after the mold temperature drops to below 28℃, first remove the connecting bolts and pins of the mold metal block, remove the metal mold block, and then remove the water-soluble core mold from the reserved process hole of the closed cavity reinforcing rib structure; according to the product assembly size requirements, use grinding technology to process the interface parts to ensure interface accuracy; for the positions where holes need to be opened on the product, use a special conical diamond grinding rod to perform hole opening treatment to reduce damage to the composite material body during the hole opening process;

[0089] S6. Assembly process of main support structure: Use room temperature curing epoxy adhesive to bond the connection surfaces of the main support structure and the auxiliary parts. The adhesive is cured at room temperature for 40-50 hours to ensure that the bonding strength meets the standard. After the bonding is completed, use bolts for auxiliary fixation. During the bolting process, use a torque wrench to control the tightening torque to ensure that the torque range is between 5 and 45 N•m, so as to ensure the stability and consistency of the bolting. Finally, complete the overall assembly.

[0090] In a specific embodiment, the curing time is 48 hours.

[0091] In this invention, a material scheme combining M55 high-modulus fiber and T800 high-strength fiber is used to simultaneously provide high rigidity and strength for the main support structure of the integrated dual-support space mapping camera, ensuring its structural dimensional stability. The cyanate ester resin system has a glass transition temperature exceeding 240℃ and a thermal decomposition temperature exceeding 400℃, making it resistant to melting and decomposition, thus meeting the high-temperature mechanical performance requirements of the structure. Cyanate ester resin has low water absorption; when combined with high-modulus M55 carbon fiber, it significantly improves its dimensional stability in a vacuum environment, making it less susceptible to the effects of water, acids, alkalis, and other substances, exhibiting good chemical stability.

[0092] like Figure 4 The diagram shows the structure of a single off-axis three-lens reflex space camera, which is supported by the support structure of this invention.

[0093] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0094] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method of fabricating a large off-axis three-mirror space mapping camera main body support structure, characterized by: Specifically comprising the following steps: S1. Pre-compaction of the open-cavity support rib assembly: process the metal mold block, brush two coats of high-temperature resistant release agent on the outer surface of the metal mold block; lay T800 / cyanate prepreg on the outer surface of the pretreated metal mold block; Assemble each metal mold block with the core mold inner cylinder; S2. Pre-compaction of the closed-cavity rib; including: S201. First, brush two coats of waterproof glue on the outer surface of the water-soluble core mold; after the waterproof glue is completely dry, brush two coats of high-temperature resistant release agent on the dry outer surface of the water-soluble core mold; S202. Lay T800 / cyanate prepreg on the outer surface of the water-soluble core mold, with the same layer angle and layer thickness as in step S1; according to the preset positioning relationship, connect and assemble the water-soluble core mold with the prepreg laid on it with the metal core mold support structure; at the same time, design the reserved process holes on the closed-cavity rib structure; S3. Frame layer and skin structure preparation; including: S301. After assembling the pre-compacted structures of steps S1 and S2, lay M55 / cyanate prepreg on the bottom and top to form the surface structure of the frame bottom layer and the frame top layer; S302. Lay M55 / cyanate prepreg on the outer surface of the support rib assembly to form the skin, until the total thickness of the skin reaches 2mm; perform vacuum pre-compaction operation once every 4 layers of prepreg laid; S303. Pre-bury the pre-buried parts at the stress connection parts of the skin structure; S304. For the flange parts with inconsistent thickness with the skin, use M55 / cyanate prepreg for symmetrical and cyclic laying to form, reduce the internal stress of the flange, and avoid deformation; at the same time, reserve processing allowance on the outer edge of the flange; S4. Co-curing forming: after the skin laying is completed, use the metal mold process to close the mold, so that the support rib assembly, the rib and the skin are co-cured; S5. After the curing system is cooled to below 35℃, the product is taken out from the curing equipment; after the mold temperature is reduced to below 28℃, the metal mold block is taken out, and then the water-soluble core mold is taken out from the reserved process holes of the closed-cavity rib structure; grind the butt joint part, and open the hole at the position needing to be opened; S6. Select room temperature curing epoxy adhesive to glue the connecting surface of the main support structure and the auxiliary part, and the adhesive is cured at room temperature; after gluing is completed, use bolts for auxiliary fixation, and finally complete the overall assembly.

2. The method of claim 1, wherein the method further comprises: providing a plurality of support members; and coupling the plurality of support members to the plurality of support structures. In the steps S1 and S2, the time interval for brushing the high-temperature resistant release agent twice is 40-55min, and the environmental temperature is ensured to be 20-25℃ and the relative humidity is less than 45% during the process; the layer angle of the T800 / cyanate prepreg is set to (0° / 45° / 90° / -45°)n, and the layer thickness is 1 / 2 of the total thickness of the support rib assembly; wherein n≥1; In the step S3, the layer angle of the M55 / cyanate prepreg is set to (0° / 60° / 90° / -60°)n, wherein n≥1; The high-temperature resistant release agent includes polytetrafluoroethylene release agent or siloxane release agent; The material of the metal mold block is aluminum alloy.

3. The method of claim 1, wherein the method further comprises: providing a plurality of support members; and coupling the plurality of support members to the plurality of support structures. The interval between the two brushings of waterproof glue is 30-45 min, the ambient temperature is controlled at 25-30 DEG C, and the relative humidity is 30-45% in the step S201.

4. The method of claim 1, wherein the method further comprises: providing a plurality of support members; and coupling the plurality of support members to the plurality of support structures. The co-curing system in the step S4 is set as: 100 DEG C / 2h; 120 DEG C / 2h; 150 DEG C / 2h; 180 DEG C / 1h; 230 DEG C / 2h; and the temperature rising rate is controlled below 0.5 DEG C / min and the temperature falling rate is controlled below 0.3 DEG C / min during the co-curing process; The adhesive curing time of the step S6 is 40-50h; the torque wrench is used to control the tightening torque in the auxiliary fixing process, to ensure that the torque range is 5-45N between m and m+1.

5. A large off-axis three-mirror space mapping camera main body support structure, which is prepared by the preparation method of the large off-axis three-mirror space mapping camera main body support structure according to claim 1, characterized in that: The frame bottom layer, the skin, the frame top layer, the support rib assembly and the embedded part are included. The frame bottom layer and the frame top layer are oppositely arranged and fixedly connected with the support rib assembly respectively; the skin is a surrounding structure and is covered on the outer surface of the support rib assembly; the support rib assembly is a cross staggered and uniformly distributed well-shaped support rib. The frame bottom layer and the frame top layer are respectively provided with an outer convex mirror cavity platform in the optical element mounting area, and the embedded part embedded on the outer convex mirror cavity platform is connected with the optical element; the frame bottom layer is integrated with a plurality of satellite platform interfaces connected with the satellite platform. The frame bottom layer, the skin, the frame top layer and the support rib assembly are all made of carbon fiber composite material, and the embedded part is made of titanium alloy material.

6. The large off-axis three-mirror space mapping camera body support structure according to claim 5, wherein: The main support structure of the large off-axis three-mirror space mapping camera is in a tower shape with the lower part being round and the upper part being square. The number of the satellite platform interfaces is six.

7. The large off-axis three-mirror space mapping camera body support structure according to claim 5, wherein: The optical element mounting area of the frame bottom layer is provided with a primary mirror group and a three-mirror group. The frame bottom layer and the frame top layer are both composed of a surface layer plate, a reinforcing rib and an inner layer plate, the surface layer plate and the inner layer plate are respectively plate-shaped support surfaces of outer layer and inner layer, and the reinforcing rib is vertically connected with the surface layer plate and the inner layer plate to form a closed cavity triangular structure through co-curing.

8. The large off-axis three-mirror space mapping camera body support structure according to claim 5, wherein: The optical element mounting area of the frame top layer is provided with a secondary mirror group, a folding mirror group and a camera light shield.

9. The large off-axis three-mirror space mapping camera body support structure according to claim 7, wherein: The support rib assembly includes horizontal support ribs and vertical support ribs, which are cross staggered and uniformly distributed inside the skin to form a plurality of well-shaped support ribs. The thickness of the reinforcing rib is a mm, and 0.3 mm≤a≤1.5 mm; the thickness of the surface layer plate and the inner layer plate is consistent, which is 4-6 times of the thickness of the reinforcing rib.

10. The large off-axis three-mirror space mapping camera body support structure according to claim 9, wherein: The thickness of the skin, the horizontal support rib and the vertical support rib is consistent, which is twice of the thickness of the reinforcing rib.

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