High-lightweight 3D printing invar steel double-sided reflector

Abstract

The invention discloses a high-light-weight 3D printing invar steel double-sided reflecting mirror which comprises a double-sided reflecting mirror body, a three-point ball head and an assembly supporting structure. The double-sided reflector body comprises a skin and a dot matrix; the skin covers the outer side of the dot matrix, and the dot matrix is formed through 3D printing; the double-sided reflecting mirror body is installed on the assembly supporting structure through the three-point ball head, and the three-point ball head is used for releasing the expansion freedom degree in the mirror face direction of the double-sided reflecting mirror body, so that quasi-static support is achieved. According to the invention, while double-sided reflection is realized, the envelope of an optical machine is reduced, the processing cost and the processing period are effectively reduced, and the method has important guiding significance for development and application of remote sensors.

Description

Technical Field

[0001] This invention relates to a method for fabricating a double-sided reflector for a remote sensing camera using a lightweight 3D printing process for Invar steel, belonging to the field of space optical remote sensing technology. Background Technology

[0002] Currently, the main materials used for remote sensing camera mirrors both domestically and internationally are ULE, microcrystalline silicon, and SiC. While these traditional mirror materials offer stable manufacturing processes, they suffer from high costs and long production cycles, thus accounting for a significant portion of the economic costs and development time in remote sensor development. With increasing demands for mass production and rapid assembly of remote sensors, reducing the manufacturing cost and time of mirrors has become a pressing issue for the development of large-scale, low-cost payloads.

[0003] Compared to ULE, microcrystalline, and SiC, metal-based mirrors have advantages in both cost and production time. As early as 1989, the Cassegrain infrared telescope on the NASA Aquiper space station used an 18.5cm diameter aluminum mirror as a oscillating secondary mirror, with its hyperbolic reflector and mounting reference surface both machined using a precision diamond lathe. Aluminum alloy mirrors obtained through forging have also gradually gained application due to their advantages such as good machinability and low material cost. However, due to the limitations of traditional machining methods, aluminum alloy mirrors struggle to simultaneously meet the requirements of lightweight and high rigidity, which to some extent restricts their application.

[0004] Aluminum-based reflectors also have problems during use because aluminum alloys have a relatively large coefficient of thermal expansion, reaching 23.0 × 10⁻⁶. -6 In optical system design, thermal matching is a critical consideration, which also presents significant challenges to temperature control. Furthermore, the bimetallic effect of the surface coating at low temperatures affects the stability of the film, limiting the use of aluminum mirrors. Therefore, there is an urgent need for new metal-based mirror materials that, while meeting the requirements of lightweight and high rigidity, possess low thermal expansion properties to achieve better surface stability.

[0005] Invar 4J32 series materials possess extremely low coefficients of thermal expansion, making them widely used in remote sensing camera structures where high thermal deformation requirements exist. As an iron-nickel-cobalt alloy, 4J32 Invar has excellent weldability, providing a good foundation for 3D printing. However, due to the difficulty in controlling its coefficient of thermal expansion, 3D printing of ultra-low expansion Invar is challenging. Currently, domestic and international technologies have not yet addressed the issue of lightweight 3D printing of Invar mirrors. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned defects and provide a lightweight 3D printed Invar double-sided mirror. This invention solves the technical problems of existing ULE mirrors, which cannot be configured in irregular shapes, microcrystalline mirrors, which are heavy and have poor specific stiffness, and SiC mirrors, which are expensive and have long processing cycles. This invention achieves double-sided reflection while reducing the optomechanical envelope, and effectively reduces processing costs and processing cycles. This invention has important guiding significance for the development and application of remote sensors.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A lightweight 3D-printed Invar double-sided reflector includes: a double-sided reflector body, a three-point ball head, and a component support structure; The double-sided mirror body consists of a skin and a dot matrix; the skin covers the outside of the dot matrix, which is formed by 3D printing. The double-sided reflector is mounted on the component support structure via a three-point ball joint. The three-point ball joint is used to release the expansion degree of freedom of the double-sided reflector in the mirror direction, thereby achieving quasi-statically determinate support.

[0008] Furthermore, the skin thickness at the three-point ball head of the double-sided reflector is 3-4mm, the skin thickness at the mirror surface of the double-sided reflector is 2-3mm, and the skin thickness of the remaining parts is 0.8-1.2mm.

[0009] Furthermore, the lattice is constructed using BCC cells; BCC cell size is 6 mm×6 mm×6 mm~7 mm×7 mm×7 mm, rod diameter is 0.55-0.65 mm.

[0010] Furthermore, the three-point ball head includes three sets of ball head assemblies, each set of ball head assemblies including a ball head, a ball head pressure ring, and a ball head adapter seat; The ball head is fixedly mounted on the double-sided reflector body by a ball head pressure ring; One end of the ball joint adapter is inserted into the ball joint, and the other end is fixedly installed on the component support structure.

[0011] Furthermore, the double-sided reflector body is provided with three ball head mounting holes. The ball head is placed in the ball head mounting holes, and the ball head pressure ring is screwed to the three ball head mounting holes to fix the ball head in the ball head mounting holes.

[0012] Furthermore, the ball joint adapter has a conical structure. The small end of the ball joint adapter is inserted into the ball head, and the large end is connected to the component support structure by screws. When the double-sided reflector expands due to heat, the ball joint adapter moves axially, releasing the expansion degree of freedom in the mirror direction.

[0013] Furthermore, the axes of the three ball joints in the three-point ball joint are all located on the plane of symmetry of the double-sided reflector, and the three ball joints are distributed at 120° on the plane of symmetry.

[0014] Furthermore, the ball head is a GE17C standard bearing.

[0015] Furthermore, the component support structure is made of titanium alloy using 3D printing. The double-sided reflector is 3D printed using Invar steel.

[0016] Furthermore, the double-sided reflector body includes two symmetrical reflectors, and the component support structure includes a main support and two auxiliary supports vertically connected to both ends of the main support; the main support and the two auxiliary supports respectively enclose the bottom and two sides of the double-sided reflector body, and the three connection points between the three-point ball head and the double-sided reflector body are located at the upper and lower ends of one auxiliary support and the middle of the other auxiliary support.

[0017] Compared with the prior art, the present invention has at least one of the following advantages: (1) The present invention can realize a double-sided reflection configuration, and the double-sided reflector as a whole has a high specific stiffness; (2) This invention can effectively reduce processing costs and processing cycle; (3) The Invar mirror body and the mirror support and transition structure of the present invention are integrally formed in the additive manufacturing process. The component interface has strong compatibility and compact layout. While realizing double-sided reflection, the optical-mechanical envelope is reduced. (4) The present invention adopts a three-point ball head and component support structure, which can release the expansion degree of freedom in the mirror direction, improve the thermal adaptability of the mirror body and the support structure, and realize quasi-statically indeterminate support. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall lightweight 3D printed Invar double-sided reflector of the present invention; Figure 2 Here are (a) an overall schematic diagram and (b) a schematic diagram of the skin of the mirror body of the present invention; Figure 3 Here are (a) an overall schematic diagram and (b) a cell schematic diagram of the dot matrix of the present invention; Figure 4 This is a schematic diagram of the three-point ball head of the present invention; Figure 5 This is a schematic diagram of the component support structure of the present invention. Detailed Implementation

[0019] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0020] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0021] This invention employs a lightweight 3D printing process using Invar steel with a lattice-based skin to achieve meter-scale double-sided mirrors with irregular configurations. It overcomes the shortcomings of existing ULE mirrors (which cannot be configured in irregular shapes), microcrystalline mirrors (which are heavy and have poor specific stiffness), and SiC mirrors (which are expensive and have long processing cycles). Furthermore, the Invar steel mirror body and mirror support structure are integrally formed during additive manufacturing, resulting in highly compatible component interfaces and a compact layout. This achieves double-sided reflection while reducing the optomechanical envelope.

[0022] This invention relates to a double-sided reflector assembly located at the center of a dual-line array stereo mapping camera. It features double-sided reflection and is shared by two camera lenses, subject to stringent weight and envelope constraints. The reflector assembly comprises three parts: the mirror body, a three-point ball joint, and a support structure. The mirror body is fabricated using 3D-printed Invar steel. To improve the specific stiffness of the mirror body, a skin-plus-dot matrix configuration is adopted. The mirror body is a symmetrical mirror image, comprising an outer skin and an inner dot matrix. The outer skin has varying thicknesses in different areas: 2mm for the mirror surface, 3mm for the ball joint transition area, and 1mm for the remaining areas. The internal dot matrix uses BCC cells with a cell size of 6×6×6mm and a rod diameter of 0.6mm, balancing printability, weight, and stiffness. The three-point ball joint is a 120-degree distributed ball joint structure, releasing the expansion freedom in the mirror plane direction, improving the thermal adaptability of the mirror body and support structure, and achieving quasi-statically determinate support. The support structure provides mounting interfaces for the three-point ball joint and for the reflector assembly to the entire machine.

[0023] Compared to the ULE solution, the 3D printing additive manufacturing of this invention has advantages in irregular configurations, enabling the realization of double-sided reflection configurations; compared to the microcrystalline solution, this invention can achieve higher specific stiffness. Due to the requirement of double-sided reflection, the microcrystalline solution cannot achieve high lightweighting, and its overall specific stiffness is lower; compared to the SiC solution, 3D printing has advantages in economic cost and processing cycle; in addition, the Invar mirror body and the mirror support adapter structure are integrally formed during the additive manufacturing process, with strong component interface adaptability and compact layout, reducing the optomechanical envelope while achieving double-sided reflection.

[0024] Therefore, considering factors such as specific stiffness, irregular configuration, structural adaptability, economic cost, and processing cycle, 3D printed Invar mirrors are the better choice for double-sided mirrors.

[0025] Example: The double-sided reflector in this invention is a reflector in a dual-line array stereo mapping remote sensing camera. Taking this reflector as an example, the specific implementation of this invention will be described. The double-sided reflector is located at the center of the entire optomechanical body and is shared by two camera lenses, therefore it has strict weight requirements and envelope size constraints. The single-sided reflector has a light transmission aperture of 740×220mm, and the two sides are mirror-symmetrical. The weight of the entire reflector assembly (including the supporting structure) must be less than 23Kg. To meet the compact layout of the entire machine, the envelope size of the entire reflector must be less than 740×220×300mm. Traditional ULE, microcrystalline, and SiC solutions cannot simultaneously address factors such as specific stiffness, irregular configuration, structural adaptability, economic cost, and processing cycle. This invention uses 3D printing additive manufacturing of Invar steel to solve the design requirements of this double-sided mirror. The designed Invar steel mirror weighs 13.5Kg and has a surface density of 41Kg / m³. 2 The entire double-sided reflector assembly weighs 21 kg, with a bare mirror fundamental frequency of 810 Hz and an assembly fundamental frequency of 88 Hz. The surface shape under 1G gravity adjustment is better than 1 / 50λ, and the material safety factor under 20G overload is >3. The mechanical and thermal stability and assembly and adjustment testability of the assembly meet the usage requirements.

[0026] like Figure 1 The reflector assembly consists of three parts: a double-sided reflector body 1, a three-point ball head 2, and an assembly support structure 3.

[0027] like Figure 2 and Figure 3 The double-sided reflector body 1 comprises: a skin 1.1 and a lattice 1.2. The skin 1.1 has different thicknesses for different functional positions: the mirror skin 1.1.1 is 2mm thick, the ball-end mounting skin 1.1.2 is 3mm thick, and the remaining skin 1.1.3 is 1mm thick. The lattice 1.2 is composed of 3D-printed BCC cells 1.2.1, with dimensions of 6×6×6mm and a rod diameter of 0.6mm, balancing printing manufacturability and the specific stiffness requirements of the mirror body.

[0028] like Figure 4 The three-point ball head 2 comprises: a ball head 2.1, a ball head retaining ring 2.2, and a ball head adapter 2.3. The ball head 2.1 is a GE17C standard bearing; the outer ring of the ball head retaining ring 2.2 has a threaded structure. After the ball head mounting skin 1.1.2 is installed in the ball head 2.1, it is screwed in to fix the ball head. The three-point ball head 2.1 is distributed at 120 degrees, releasing the expansion freedom in the mirror direction, improving the thermal adaptability of the mirror body and the support structure, and achieving quasi-statically determinate support. The ball head adapter 2.3 provides the mounting interface between the three-point ball head 2 and the component support structure 3.

[0029] like Figure 5The component support structure 3 includes: a main support 3.1 and an auxiliary support 3.2. To facilitate the assembly and installation of the double-sided reflector 1 and the three-point ball head 2, the component support structure 3 is divided into two independent parts: the main support 3.1 and the auxiliary support 3.2. Both parts are made of lightweight 3D printed titanium alloy to reduce the weight of the component.

[0030] This invention designs a double-sided reflective elongated mirror configuration, a three-point ball head support for the double-sided reflective elongated mirror, a 3D-printed Invar steel configuration with a lightweight skin and dot matrix for the double-sided reflective elongated mirror, thickness specifications of the outer skin of the 3D-printed Invar steel mirror in different functional areas, size specifications of the internal BCC dot matrix, and a compact enveloping support form for the double-sided reflective mirror assembly, which has broad application prospects.

[0031] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0032] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A lightweight 3D-printed Invar double-sided reflector, characterized in that, include: Double-sided reflector body (1), three-point ball head (2) and component support structure (3); The double-sided mirror body (1) includes a skin (1.1) and a dot matrix (1.2); the skin (1.1) covers the outside of the dot matrix (1.2), and the dot matrix (1.2) is formed by 3D printing; The double-sided reflector (1) is mounted on the component support structure (3) via a three-point ball head (2). The three-point ball head (2) is used to release the expansion degree of the double-sided reflector (1) in the mirror direction, thereby achieving quasi-statically indeterminate support.

2. The lightweight 3D-printed Invar double-sided reflector according to claim 1, characterized in that, The skin thickness at the three-point ball head (2) of the double-sided reflector body (1) is 3-4mm, the skin thickness at the mirror surface of the double-sided reflector body (1) is 2-3mm, and the skin thickness of the remaining parts is 0.8-1.2mm.

3. The lightweight 3D-printed Invar double-sided reflector according to claim 1, characterized in that, The lattice (1.2) is constructed using BCC cells; BCC cell size is 6 mm×6 mm×6 mm~7 mm×7 mm×7 mm, rod diameter is 0.55-0.65 mm.

4. The lightweight 3D-printed Invar double-sided reflector according to claim 1, characterized in that, The three-point ball head (2) includes three sets of ball head assemblies, each set of ball head assemblies including a ball head (2.1), a ball head pressure ring (2.2) and a ball head adapter (2.3). The ball head (2.1) is fixedly installed on the double-sided reflector body (1) by the ball head pressure ring (2.2); One end of the ball head adapter (2.3) is inserted into the ball head (2.1), and the other end is fixedly installed on the component support structure (3).

5. A lightweight 3D-printed Invar double-sided reflector according to claim 4, characterized in that, The double-sided reflector body (1) has three ball head mounting holes. The ball head (2.1) is placed in the ball head mounting hole, and the ball head pressure ring (2.2) is screwed to the three ball head mounting holes to fix the ball head (2.1) in the ball head mounting hole.

6. The lightweight 3D-printed Invar double-sided reflector according to claim 5, characterized in that, The ball head adapter (2.3) is a conical structure. The small end of the ball head adapter (2.3) is inserted into the ball head (2.1), and the large end is connected to the component support structure (3) by screws. When the double-sided reflector (1) is heated and expanded, the ball head adapter (2.3) is displaced along the axial direction, releasing the expansion degree of freedom in the mirror direction.

7. A lightweight 3D-printed Invar double-sided reflector according to claim 4, characterized in that, The axes of the three ball head adapters (2.3) in the three-point ball head (2) are all located on the plane of symmetry of the double-sided mirror body (1), and the three ball heads (2.1) are distributed at 120° on the plane of symmetry.

8. A lightweight 3D-printed Invar double-sided reflector according to claim 7, characterized in that, The ball head (2.1) is a GE17C standard bearing.

9. A lightweight 3D-printed Invar double-sided reflector according to claim 1, characterized in that, The component support structure (3) is formed by 3D printing of titanium alloy; The double-sided reflector body (1) is formed by Invar 3D printing.

10. A lightweight 3D-printed Invar double-sided reflector according to claim 4, characterized in that, The double-sided mirror body (1) includes two symmetrical mirrors. The component support structure (3) includes a main support (3.1) and two auxiliary supports (3.2) vertically connected to both ends of the main support (3.1). The main support (3.1) and the two auxiliary supports (3.2) respectively enclose the bottom and two sides of the double-sided mirror body (1). The three-point ball head (2) and the three connection points of the double-sided mirror body (1) are located at the upper and lower ends of one auxiliary support (3.2) and the middle of the other auxiliary support (3.2).

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