A lightweight metal mirror structure with a wide environmental adaptation range

Abstract

The application discloses a light metal mirror structure with wide environmental adaptability, and relates to the technical field of optical imaging and measurement, which comprises a mirror body formed by a plurality of triangular structures into a disc body, and a back plate connecting surface arranged on the mirror body; a back plate supported by three points of the back plate connecting surface and connected to the mirror body, the back plate being formed by a rigid end inside and a flexible end outside; and a connecting part, the mirror body and the back plate being connected and fixed through the connecting part and being provided with positioning by positioning pins. The back plate adopts the design of combination of high rigidity and large flexibility, greatly reduces the deformation of the back plate and the mounting surface of the mirror body, and guarantees the high precision of the mirror surface; a three-way rod-shaped flexible structure is designed, radial and axial deformations can be realized at the same time, so that the installation and temperature stress are eliminated, and good mechanical properties are guaranteed; the mirror structure is compact, light in weight by selecting light metal materials, and temperature adaptability and mechanical adaptability are considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging and measurement, and in particular to a lightweight metal mirror structure with a wide environmental adaptation range. BACKGROUND

[0002] The photoelectric load in the aviation and near space is one of the main load forms of space remote sensors, and is an important technical means for obtaining ground information, which is widely loaded on manned aircraft or unmanned aircraft. Environmental adaptability is one of the main technical indicators for measuring the performance of the photoelectric load in the aviation and near space, including natural environmental adaptability and mechanical environmental adaptability. The natural environment generally includes factors such as air pressure, temperature, heat and humidity, mold, salt spray, etc. when the photoelectric load is working or storing, and the mechanical environment generally includes factors such as impact, vibration, acceleration, etc. when the photoelectric load is working or storing. The mirrors inside the photoelectric load, especially the primary mirror and the secondary mirror, directly affect the performance of the photoelectric load, so the mirrors inside the photoelectric load are required to have good environmental adaptability.

[0003] The environmental adaptability of the mirrors inside the photoelectric load is mainly designed from four aspects of structure form, material, coating and surface treatment. By reasonably selecting the mirror material and surface treatment method, and coating a three-proofing protective film, the environmental adaptability problems of the mirror during working or storage, such as air pressure, heat and humidity, mold, salt spray, etc. can be solved, and there is a relatively mature solution at present. However, the performance of the mirror under different temperature environments and mechanical environments needs to be solved through structural design.

[0004] According to actual measurement, when the flight height is 20000m, the minimum environmental temperature can reach about -90℃, but the photoelectric load is produced and assembled at room temperature (20℃). When used at low temperature, the thermal deformation of the mirror inside the photoelectric load and its support structure will be inconsistent due to the difference in material and structure, which will reduce the mirror surface accuracy and seriously affect the imaging quality. When the weight, volume and power consumption of the system are allowed, the photoelectric load can be temperature controlled so that the internal mirror remains within the allowed temperature range. However, when the weight, volume and power consumption of the system are limited, the photoelectric load cannot be effectively temperature controlled, so the mirror is required to have a wide temperature adaptability and always maintain good optical performance.

[0005] The aircraft will produce the maximum impact, vibration or acceleration during takeoff, landing or extreme environment. The impact environment is generally the most severe. The mirror inside the electric load is required to be not damaged during the mechanical environmental action or after the mechanical environmental action, and to maintain the same optical performance. Although the shock absorber of the photoelectric load system can attenuate the force transmitted to the internal mirror, it cannot be completely isolated, and even the impact can be amplified.

[0006] Based on the above technical problems, the skilled in the art urgently needs to develop a lightweight metal mirror structure which can maintain good optical performance, effectively improve the strength and rigidity of the mirror structure, and does not increase the weight, and has a wide environmental adaptation range. SUMMARY

[0007] The purpose of the present application is to provide a lightweight metal mirror structure which can maintain good optical performance, effectively improve the strength and rigidity of the mirror structure, and does not increase the weight, and has a wide environmental adaptation range.

[0008] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0009] The lightweight metal mirror structure with a wide environmental adaptation range comprises:

[0010] A mirror body formed by a plurality of triangular structures to form a disc body, and a back plate connecting surface is provided on the mirror body; and

[0011] A back plate supported by the back plate connecting surface and connected to the mirror body, the back plate is formed by a rigid end inside and a flexible end outside;

[0012] The structure further comprises:

[0013] A connecting part, the mirror body and the back plate are connected and fixed through the connecting part, and positioning is provided through a positioning pin.

[0014] Further, a circular ring interface is provided in the middle of the mirror body, a first stress groove is opened in the circular ring interface, and the circular ring interface forms a three-point connection structure with the mirror surface of the mirror body through the first stress groove;

[0015] The back plate connecting surface is arranged at the middle position of the first stress groove and a second stress groove is provided, the second stress groove is coplanar with three small planes at the connecting position of the back plate, so that the mirror body and the back plate are three-point connected.

[0016] Preferably, the flatness of the three small planes is 0.002mm.

[0017] Further, the connecting part 3 comprises three pressing blocks arranged along the circumference of the circular ring interface, and the flatness of the pressing blocks and the mirror body mounting surface is 0.002mm; and

[0018] A fixing screw matched with the pressing block, a fixing structure is formed by the pressing block and the fixing screw to connect the mirror body and the back plate;

[0019] The pressing block and the positioning pin are made of RSA6061 aluminum alloy material, and the fixing screw is made of 0Cr18Ni9 material.

[0020] Further, the rigid end of the back plate is configured as an inner layer, and the flexible end of the back plate is configured as three outer layers evenly distributed on the outer circumference of the inner layer.

[0021] The end of the back plate away from the mirror body is configured as a mounting surface.

[0022] The outer layers include two first flexible rods which are inclined and symmetrically arranged.

[0023] A second flexible rod is connected between the two first flexible rods.

[0024] Preferably, the mirror body and the back plate are made of RSA6061 aluminum alloy material.

[0025] Preferably, the first flexible rod and the second flexible rod have a rectangular overall cross section, a width of 2 mm, a height of 4 mm, and an included angle of 120° between adjacent first flexible rods and second flexible rods.

[0026] In the above technical solution, the light metal mirror structure with a wide environmental adaptation range provided by the present application has the following beneficial effects:

[0027] The light metal mirror structure with a wide environmental adaptation range provided by the present application has a simple structure, and the back plate is designed by combining high rigidity and large flexibility, which greatly reduces the deformation of the back plate and the mounting surface of the mirror body, and ensures the high precision of the mirror surface.

[0028] A three-way rod-shaped flexible structure is designed, which can realize radial and axial deformation at the same time to eliminate installation and temperature stress, and at the same time ensure good mechanical properties; the mirror structure is compact, light in weight by selecting light metal material, and takes into account temperature adaptability and mechanical adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0030] Figure 1 The overall structure principle diagram of the light metal mirror structure with a wide environmental adaptation range provided by the embodiment of the present application is shown in the figure.

[0031] Figure 2 The top view of the light metal mirror structure with a wide environmental adaptation range provided by the embodiment of the present application is shown in the figure.

[0032] Figure 3A lateral sectional view of a light metal mirror structure with wide environmental adaptability range is provided for the embodiment of the present application.

[0033] Figure 4 A structure principle diagram of a mirror body in a light metal mirror structure with wide environmental adaptability range is provided for the embodiment of the present application.

[0034] Figure 5 A structure principle diagram of a back plate in a light metal mirror structure with wide environmental adaptability range is provided for the embodiment of the present application.

[0035] Figure 6 A structure diagram of a pressing block in a light metal mirror structure with wide environmental adaptability range is provided for the embodiment of the present application.

[0036] Explanation of reference signs:

[0037] 1, mirror body; 2, back plate; 3, connecting part; 4, positioning pin;

[0038] 101, back plate connecting surface; 102, circular ring interface; 103, first stress groove; 104, second stress groove;

[0039] 201, inner layer; 202, outer layer; 203, mounting surface; 2021, first flexible rod; 2022, second flexible rod;

[0040] 301, pressing block; 302, fixing screw. DETAILED DESCRIPTION

[0041] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings.

[0042] Reference is made to Figures 1-6 the drawings.

[0043] The light metal mirror structure with wide environmental adaptability range of the present application comprises:

[0044] The mirror body 1 is formed into a disc body by a plurality of triangular structures, the mirror body 1 adopts a triangular light weight structure to ensure rigidity while reducing weight, and a back plate connecting surface 101 is arranged on the mirror body 1; and

[0045] The back plate 2 is supported by three points through the back plate connecting surface 101 and connected to the mirror body 1, and the back plate 2 is formed by a rigid end inside and a flexible end outside;

[0046] The structure further comprises:

[0047] The mirror body 1 and the back plate 2 are connected and fixed through the connecting part 3, and positioning is provided through the positioning pin 4.

[0048] As a further introduction of the embodiment, the mirror body 1 is provided with a circular ring-shaped interface 102, the circular ring-shaped interface 102 is provided with a first stress groove 103, and the circular ring-shaped interface 102 is connected to the mirror surface of the mirror body 1 through the first stress groove 103 to form a three-point connection structure.

[0049] The back plate connecting surface 101 is arranged at a middle position of the first stress groove 103, and a second stress groove 104 is arranged, and the second stress groove 104 is coplanar with three small planes at the connection position of the back plate 2, so that the mirror body 1 and the back plate 2 are connected by three points.

[0050] Overall, the force transmission path is extended by the stress groove, and the connection stress caused by the plane error is reduced by the three-point connection. When the circular ring-shaped interface 102 structure is optimal, it should be symmetrical about the center of gravity of the mirror body 1 in the axial direction. If the structure does not allow, the circular ring-shaped interface 102 structure should be as close to the center of gravity of the mirror body 1 as possible. The width of the connection point of the mirror surface and the circular ring-shaped interface 102, and the width of the connection node of the circular ring-shaped interface 102 and the back plate 2 need to be determined comprehensively according to the weight of the mirror body 1, the size of the fixing screw 302, etc. The heavier the mirror body 1, the larger the size of the fixing screw 302, and the larger the size of the connection point.

[0051] As a further introduction of the embodiment, the connecting part 3 includes three pressing blocks 301 arranged along the circumference of the circular ring-shaped interface 102, and the planeness of the pressing block 301 and the mounting surface of the mirror body 1 is 0.002mm; and

[0052] The fixing screw 302 matched with the pressing block 301 forms a fixing structure through the pressing block 301 and the fixing screw 302 to connect the mirror body 1 and the back plate 2. The mirror body 1, the back plate 2, the pressing block 301 and the positioning pin 4 provided in the embodiment are all made of the same material to ensure that the linear expansion coefficients of each structure are the same when the temperature changes, and no temperature stress is generated. The material can be selected from aluminum alloy, beryllium aluminum alloy, beryllium, silicon aluminum, etc. as long as the processing requirements and environmental adaptability are met. If the material of the mirror body 1 can meet the stress requirements of the fixing screw 302, the fixing screw 302 is made of the same material as the mirror body 1. If the material of the mirror body 1 cannot meet the stress requirements of the screw 302, the fixing screw 302 can be made of high-strength materials such as stainless steel. At this time, the screw connection position must have a stress relief design to avoid the influence of the temperature stress caused by the difference in linear expansion coefficient when the temperature changes on the mirror surface precision

[0053] Specifically, the pressing block 301 and the positioning pin 4 are made of RSA6061 aluminum alloy material, and the fixing screw 302 is made of 0Cr18Ni9 material.

[0054] As a further introduction of the embodiment, the rigid end of the back plate 2 is configured as an inner layer 201, and the flexible end of the back plate 2 is configured as three outer layers 202 uniformly distributed on the outer circumference of the inner layer 201.

[0055] The end of the back plate 2 away from the mirror body 1 is configured as a mounting surface 203.

[0056] The outer layer 202 includes two first flexible rods 2021 which are inclined and symmetrically arranged with respect to each other.

[0057] A second flexible rod 2022 is connected between the two first flexible rods 2021.

[0058] The back plate 2 is connected with the mirror body 1 during processing, and the connection is generally within the range of 30-60 nm in mirror surface accuracy (RMS). It is required that the change in surface accuracy (RMS) after connection does not exceed 3 nm. After the back plate 2 is connected with the mirror body 1, the flatness of the outer mounting surface 203 of the back plate 2 is re-measured, and it is required to be better than 3 nm. If the requirement is not met, it is required to be satisfied by grinding or other methods.

[0059] As a preferred technical solution of the embodiment, the in-plane (back plate radial) deformation of the first flexible rod 2021 eliminates the radial stress caused by connection or temperature, and the out-of-plane (back plate axial) deformation of the second flexible rod 2022 eliminates the axial stress caused by the flatness error of the mounting surface. The inner layer 201 is designed with high rigidity, and the mounting surface (three small planes) is processed to have a flatness of 0.002 mm by single-point diamond turning or grinding. The high rigidity design ensures that the inner layer mounting surface maintains high flatness when the outer layer deforms flexibly, thereby eliminating the influence of the flexible deformation of the outer layer on the mirror surface accuracy. The size of the first flexible rod 2021 and the second flexible rod 2022 is determined according to the total weight of the mirror body 1 and the back plate 2, and the shape and size are determined through surface shape analysis and stress analysis.

[0060] As a preferred technical solution of the embodiment, the mirror body 1 and the back plate 2 are made of RSA6061 aluminum alloy material. The flatness of the mirror body 1 and the mounting surface 203 is processed to be better than 0.002 mm by single-point diamond turning, and the flatness of the mounting surface of the pressing block 301 is processed to be better than 0.002 mm by grinding.

[0061] As a preferred technical solution of the embodiment, the first flexible rod 2021 and the second flexible rod 2022 have a rectangular overall cross section, with a width of 2 mm and a height of 4 mm. The included angle between adjacent first flexible rods 2021 and second flexible rods 2022 is 120°. The stress relief groove of the mirror body 1 has a width of 1 mm. The connection point between the mirror surface and the circular ring-shaped interface 102 has a width of 7 mm. The connection node between the circular ring-shaped interface 102 and the back plate 2 has a width of 17.6 mm.

[0062] After the mirror body 1 and the back plate 2 are mechanically finished, the surface of the parts is blackened.

[0063] When the surface accuracy (RMS) of the mirror body 1 is better than 35 nm, the mirror body 1 and the back plate 2 are installed together by using the fixing screw 302 and the pressing block 301, and the pin is matched, the gap between the pin and the pin hole is 0.002-0.003 mm, the mirror body 1 is ensured not to be pressed by the pin, and the pin and the fixing screw 302 are fixed by using the silicone rubber; after the connection, the surface accuracy of the mirror body 1 is detected, when the surface accuracy (RMS) of the mirror surface is better than 40 nm, it is indicated that the connection is effective, otherwise the connection needs to be reconnected; after the effective connection, the flatness of the mounting surface 203 of the back plate 2 is detected, the flatness is required to be 0.002-0.003 mm, otherwise the grinding treatment is performed until the requirement is met.

[0064] The light metal mirror shown in the drawing of the embodiment has a 150 mm aperture and an axial height of 35 mm, after the connection of the mirror body and the back plate is completed, the mounting surface and the mirror surface are subjected to the spray of the extinction paint and the sand blasting treatment; after the mirror surface is processed to have a surface accuracy (RMS) better than 15 nm, the aluminum reflecting film and the three-proofing film are plated.

[0065] After the analysis, the mirror can adapt to a temperature difference of 80 ℃ (20 ℃ to-60 ℃), can withstand a 100 g half-sine shock (4 ms), and the weight is not more than 350 g. Among them, the maximum stress is 147 Mpa at the flexible joint position of the back plate in the Z direction (axial direction), which does not exceed the proportional limit of the RSA6061 aluminum alloy; after the mirror surface experiences a temperature difference from 20 ℃ to-60 ℃, the surface accuracy (RMS) of the mirror surface is 2.8 nm.

[0066] In the above technical solution, the light metal mirror structure with a wide environmental adaptation range provided by the present application has the following beneficial effects:

[0067] The light metal mirror structure with a wide environmental adaptation range provided by the present application has the following beneficial effects:

[0068] The present application designs a three-way rod-shaped flexible structure, which can realize radial and axial deformation at the same time to eliminate the installation and temperature stress, and at the same time ensure good mechanical properties; the mirror structure is compact, light in weight by using light metal materials, and takes into account the temperature adaptability and mechanical adaptability.

[0069] The above only describes certain exemplary embodiments of the present application by way of illustration, and it is needless to say that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present application. Therefore, the above drawings and descriptions are illustrative in nature and should not be understood as limiting the scope of protection of the claims of the present application.

Claims

1. A lightweight metal reflector structure with a wide environmental adaptability range, characterized in that, The structure includes: The mirror body (1) is formed into a disk by multiple triangular structures, and the mirror body (1) is provided with a back plate connecting surface (101); and The back plate (2) is supported by three points on the back plate connecting surface (101) and connected to the mirror body (1). The back plate (2) is formed by an inner rigid end and an outer flexible end. The structure also includes: The connecting part (3) connects and fixes the mirror body (1) and the back plate (2) and provides positioning through the positioning pin (4); The rigid end of the back plate (2) is configured as an inner layer (201), and the flexible end of the back plate (2) is configured as three outer layers (202) evenly distributed on the outer circumference of the inner layer (201). The end of the back plate (2) away from the mirror body (1) is configured as a mounting surface (203); The outer layer (202) includes two inclined and symmetrically arranged first flexible rods (2021); and A second flexible rod (2022) is connected between the two first flexible rods (2021); The mirror body (1) has a circular interface (102) in the middle, and a first stress groove (103) is opened in the circular interface (102). The circular interface (102) forms a three-point connection structure with the mirror surface of the mirror body (1) through the first stress groove (103). The back plate connecting surface (101) is arranged in the middle of the first stress groove (103) and a second stress groove (104) is provided. The second stress groove (104) and the back plate (2) are three small planes that are coplanar, so that the mirror body (1) and the back plate (2) are connected at three points. The flatness of all three small planes is 0.002 mm; The connecting part (3) includes three pressure blocks (301) arranged around the circumference of the annular interface (102), and the flatness of the pressure blocks (301) and the mounting surface of the mirror body (1) is 0.002 mm; and A fixing screw (302) adapted to the pressure block (301) forms a fixing structure through the pressure block (301) and the fixing screw (302) to connect the mirror body (1) and the back plate (2); The pressure block (301) and the positioning pin (4) are both made of RSA6061 aluminum alloy, and the fixing screw (302) is made of 0Cr18Ni9 material.

2. The lightweight metal reflector structure with a wide environmental adaptability range according to claim 1, characterized in that, The mirror body (1) and back plate (2) are made of RSA6061 aluminum alloy.

3. The lightweight metal reflector structure with a wide environmental adaptability range according to claim 1, characterized in that, The first flexible rod (2021) and the second flexible rod (2022) have a rectangular cross-section with a width of 2mm and a height of 4mm. The included angle between adjacent first flexible rods (2021) and second flexible rods (2022) is 120°.

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