Integrated all-metal mirror assembly based on additive manufacturing

Abstract

This invention belongs to the field of space optical remote sensor technology and relates to an integrated all-metal reflector assembly based on additive manufacturing. It solves the problems of low stiffness, sensitivity to assembly stress, and low lightweighting rate of traditional large-diameter aluminum alloy reflectors. The assembly includes a reflector, a honeycomb backplane, and a supporting base plate, which are integrally printed using additive manufacturing technology. The honeycomb backplane is composed of lattice units. Due to the high lightweighting rate and stiffness of the lattice structure, the specific stiffness of the reflector assembly can be effectively guaranteed. Simultaneously, the lattice structure is also a highly efficient heat exchange structure, resulting in a more uniform temperature distribution within the mirror body and improving the thermal stability of the reflector. The reflector is integrally mounted on the honeycomb backplane, with its optical axis perpendicular to the backplane. The supporting base plate is integrally mounted on the bottom of the honeycomb backplane. The bottom surface of the supporting base plate serves as the mounting surface for the reflector assembly and is parallel to the optical axis of the reflector. The distance between the bottom surface of the supporting base plate and the optical axis of the reflector is greater than the diameter of the reflector.

Description

Technical Field

[0001] This invention belongs to the field of space optical remote sensor technology and relates to an integrated all-metal reflector assembly based on additive manufacturing. Background Technology

[0002] With the rapid development of space-based Earth observation technology, the reflector, as a core component of high-resolution space optical remote sensors, directly affects the imaging quality of the optical system due to its surface accuracy. High stiffness design helps the reflector achieve high surface accuracy while ensuring a sufficiently high fundamental frequency during launch; high stability design reduces the reflector's sensitivity to external stresses and humid / hot environments, improving its surface accuracy under on-orbit conditions; and lightweight design significantly reduces the reflector's weight, thereby lowering launch costs. Commonly used space reflector materials include beryllium, aluminum alloys, glass-ceramic, quartz, ultra-low expansion fused silica (ULE), and silicon carbide (SiC).

[0003] Aluminum alloy mirrors have high specific stiffness and excellent machinability, offering advantages in processing cost and time compared to mirrors made of other materials. Therefore, they are widely used, especially in infrared optics. Traditional aluminum alloy mirrors are formed by machining. Figure 1 Due to limitations in its manufacturing process, aluminum alloy reflectors suffer from the following problems: 1) Using traditional milling and turning processes, the back of the aluminum reflector is usually open. For small-diameter reflectors, the impact is limited; however, as the reflector diameter increases, the overall stiffness is difficult to improve significantly. To ensure the overall stiffness of the reflector, the reinforcing ribs are usually quite thick, which is detrimental to improving the reflector's weight reduction rate. 2) As the diameter increases, the insufficient stiffness of the aluminum reflector makes it extremely sensitive to assembly stress, thus increasing the design difficulty of the support structure.

[0004] However, commonly used large-aperture mirror materials such as ULE and SiC often face the problem of material inconsistency between the mirror and the supporting structure, resulting in poor thermal matching and imposing extremely stringent requirements on the stability of both the mirror and the supporting structure. Summary of the Invention

[0005] To address the issues of low stiffness, sensitivity to assembly stress, and low lightweighting efficiency of traditional large-diameter aluminum alloy reflectors, this invention proposes an integrated all-metal reflector assembly based on additive manufacturing. The reflector and support structure are designed as a single unit and formed using additive manufacturing technology, thus balancing the trade-offs between structural stiffness, lightweighting efficiency, and processing performance.

[0006] The technical solution adopted in this invention is as follows:

[0007] The unique feature of the integrated all-metal reflector assembly based on additive manufacturing is that it includes a reflector, a honeycomb backplate, and a supporting base plate, which are integrally printed using additive manufacturing technology.

[0008] The honeycomb backplate is composed of lattice units. Because the lattice structure has high lightweight ratio and high stiffness, it can effectively ensure the specific stiffness of the reflector assembly. At the same time, the lattice structure is also a high-efficiency heat exchange structure, which makes the temperature distribution of the mirror body more uniform and improves the thermal stability of the reflector.

[0009] The reflector is integrally mounted on the honeycomb backplate, and the optical axis of the reflector is perpendicular to the honeycomb backplate;

[0010] The supporting base plate is integrally set at the bottom of the honeycomb back plate. The bottom surface of the supporting base plate is the mounting surface of the reflector assembly and is parallel to the optical axis of the reflector. The distance between the bottom surface of the supporting base plate and the optical axis of the reflector is greater than the diameter of the reflector.

[0011] Furthermore, the parallelism between the optical axis of the reflector and the bottom surface of the supporting base plate is better than 10 μm, and the bottom surface of the supporting base plate can be used as the mounting reference surface of the reflector assembly.

[0012] Furthermore, in order to improve the stiffness of the components, a cellular backsheet is obtained through topology optimization, which gives it extremely high specific stiffness.

[0013] Furthermore, the support base plate is provided with two mounting holes, through which the reflector assembly is fixed to other frames.

[0014] Furthermore, the reflector has a diameter of 150mm and a center thickness of 10mm to ensure that the reflector panel itself has sufficient rigidity to meet the local rigidity requirements of processing and polishing. Its top surface is the reflective surface, and its shape is determined according to the equation of the optical reflective surface. The distance between the bottom surface of the supporting base plate and the optical axis of the reflector is greater than 200mm to reduce the impact of assembly stress on the surface accuracy.

[0015] Furthermore, the reflector, honeycomb backplate, and supporting base plate are all made of AlSi10Mg.

[0016] This invention relates to an integrated all-metal reflector assembly based on additive manufacturing, which has the following advantages compared with existing reflector technologies:

[0017] 1) The reflector and reflector support structure of this invention are designed and manufactured as a single unit, eliminating the need for assembly and avoiding the assembly stress generated during the assembly process. Furthermore, the reflector and reflector support structure are made of the same material, avoiding the thermal property matching problems caused by material inconsistencies.

[0018] 2) The mounting surface of the reflector assembly of the present invention is set on the support base plate, and the installation stress direction is along the radial direction of the reflector (the radial stiffness of the reflector is much greater than the axial stiffness); at the same time, the force transmission path is through the support base plate and the honeycomb back plate to the reflector, and the path is longer, thus reducing the impact of assembly stress on the surface accuracy.

[0019] 3) Compared with traditional machining methods, additive manufacturing technology is less affected by structural form. Through topology optimization technology, a lattice structure with a higher weight reduction rate can be obtained, thereby further improving the specific stiffness of the mirror assembly. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of a traditional aluminum alloy reflector;

[0021] Figure 2 This is a 3D structural diagram of an integrated all-metal reflector assembly based on additive manufacturing.

[0022] The attached figures are labeled as follows: 1-reflector, 2-honeycomb backplate, 3-support base plate, 101-reflective surface, 201-dot matrix unit, 301-mounting hole, 302-bottom surface of support base plate. Detailed Implementation

[0023] The inventive concept of this invention is as follows:

[0024] This invention proposes an integrated all-metal reflector assembly based on additive manufacturing. The reflector and its support structure are designed and molded as a single unit, avoiding problems such as the mismatch in thermal properties between traditional aluminum alloy reflectors and support structure materials, and high assembly stress. A lattice-type honeycomb backplane obtained through biomimetic topology optimization gives the reflector a higher weight reduction ratio and specific stiffness. Simultaneously, the excellent heat transfer performance of the lattice structure improves the thermal stability of the reflector.

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] from Figure 2 As can be seen, this embodiment is an integrated all-metal reflector assembly based on additive manufacturing, including a reflector 1 and a supporting structure. The supporting structure includes a honeycomb backplate 2 and a supporting base plate 3. To reduce the assembly stress generated during the assembly of the reflector 1 and the supporting structure, in this embodiment, the reflector 1, the honeycomb backplate 2, and the supporting base plate 3 are integrally printed using additive manufacturing technology. Simultaneously, the reflector 1, the honeycomb backplate 2, and the supporting base plate 3 are made of the same material, avoiding the thermal property matching problem caused by the inconsistency between the materials of the reflector and the supporting structure. In this embodiment, the materials of the reflector 1, the honeycomb backplate 2, and the supporting base plate 3 are all AlSi10Mg.

[0027] As can be seen from the figure, the honeycomb backplane 2 is composed of lattice units 201. Because the lattice structure has a high weight reduction ratio and high stiffness, it can effectively ensure the specific stiffness of the reflector assembly. At the same time, the lattice structure is also a highly efficient heat exchange structure, which makes the temperature distribution of the mirror body more uniform and improves the thermal stability of the reflector. In order to further improve the specific stiffness of the reflector assembly, a lattice structure with a higher weight reduction ratio can be obtained through topology optimization method, thus optimizing the honeycomb backplane.

[0028] The reflector is integrally mounted on the honeycomb backplate, with its optical axis perpendicular to the backplate, ensuring that the installation stress direction is radially along the reflector. In this embodiment, the reflector has a diameter of 150mm and a center thickness of 10mm, guaranteeing that the reflector panel itself has sufficient rigidity to meet the local rigidity requirements of processing and polishing. Its top surface is the reflective surface 101, the shape of which is determined according to the equation of the optical reflective surface.

[0029] The supporting base plate 3 is integrally set at the bottom of the honeycomb back plate 2. The bottom surface 302 of the supporting base plate serves as the mounting surface for the reflector assembly. To increase the force transmission path and reduce assembly stress, the distance between the bottom surface 302 of the supporting base plate and the optical axis of the reflector 1 can be set to be greater than the diameter of the reflector. This can also be understood as increasing the height of the honeycomb back plate 2 to increase the force transmission path. In this embodiment, the distance between the bottom surface 302 of the supporting base plate and the optical axis of the reflector 1 is greater than 200mm. The optical axis of the reflector 1 is parallel to the bottom surface 302 of the supporting base plate, with a parallelism better than 10μm. The bottom surface 302 of the supporting base plate can be used as the mounting reference surface for the reflector assembly. As can be seen from the figure, the supporting base plate 3 has two mounting holes 301, through which the reflector assembly is fixed to other frames.

[0030] The present invention's transmitting mirror assembly balances the contradictions between the structural stiffness, lightweight ratio, and processing performance of the reflector, while also possessing the advantages of high stiffness, low assembly stress, and lightweight, making it widely applicable to optical payloads in the aerospace or aviation fields.

Claims

1. An integrated all-metal mirror assembly based on additive manufacturing, characterized by: The mirror (1), the honeycomb back plate (2) and the supporting bottom plate (3) are integrally printed by additive manufacturing technology. The honeycomb back plate (2) is composed of lattice units and is obtained by a topological optimization method. The mirror (1) is integrally arranged on the honeycomb back plate (2), and the optical axis of the mirror (1) is perpendicular to the honeycomb back plate (2). The supporting bottom plate (3) is integrally arranged at the bottom of the honeycomb back plate (2), the bottom surface (302) of the supporting bottom plate is a mirror assembly mounting surface and is parallel to the optical axis of the mirror (1), and the distance between the bottom surface (302) of the supporting bottom plate and the optical axis of the mirror is greater than the diameter of the mirror (1). The parallelism between the optical axis of the mirror (1) and the bottom surface (302) of the supporting bottom plate is better than 10 microns. Two mounting holes (301) are arranged on the supporting bottom plate (3), and the mounting holes (301) are used for being fixedly connected with other frames.

2. The integrated all-metal mirror assembly based on additive manufacturing of claim 1, wherein: The diameter of the mirror (1) is 150 mm, the center thickness is 10 mm, and the distance between the bottom surface (302) of the supporting bottom plate and the optical axis of the mirror (1) is greater than 200 mm.

3. The integrated all-metal mirror assembly based on additive manufacturing of claim 2, wherein: The materials of the mirror (1), the honeycomb back plate (2) and the supporting bottom plate (3) are all AlSi10Mg.

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