CN109946812A - A mirror shaft support and clamping device used at low temperature - Google Patents

Abstract

The invention discloses a mirror shaft system supporting and clamping device used at low temperature. In the invention, the main support of the mirror body and the shaft system is carried out by the U-shaped frame, and the symmetrical deformation at low temperature is realized by installing the beam on the top of the U-shaped frame; Rotation; the two shafts are designed to be fixed and movable respectively; in the openings on both sides of the reflector, use adhesive to bond the inserts with a double-layer flexible structure, and the inserts are connected with the above two shafts by screws; Dowels are provided between the insert and the mirror body to increase the connection firmness. The device can be used for clamping and supporting mirrors that need to work at extremely low temperatures, experience vibration and shock environments, and still need to maintain good optical surface and high performance; the device of the invention is suitable for spaceborne optical communication. Extravehicular tracking and sighting mechanism and the mirror of scanning pointing mechanism for deep space exploration. The device has a compact structure, a light weight, a wide temperature range, and a good mirror surface shape.

Description

A mirror shaft support and clamping device used at low temperature

Technical field:

The invention relates to the fields of deep space optical detection and spaceborne optical communication, in particular to a mirror shaft support and clamping device, in particular to a mirror shaft support and clamping device used at low temperature, which is used for The shaft system of the pointing and scanning mirrors is made and fixed by clamping.

Background technique:

The pointing mirror is the core component of spaceborne optical communication and spaceborne optical remote sensing equipment. By driving the one-dimensional/two-dimensional rotation of the pointing mirror, the tracking and aiming of the optical terminal at a long distance (for example: artificial satellite-ground, artificial satellite) can be realized to realize optical communication, and the ground scanning imaging of optical remote sensing equipment can also be realized. or phase shift compensation.

The pointing mirror is usually arranged in front of the optical telescope to expand the dynamic detection/pointing range of the optical system. In addition to realizing the dynamic pointing of the optical path, the pointing mirror also needs to ensure good surface accuracy, so as to ensure the overall wavefront error index and imaging quality of the optical system. The deterioration of the precision of the pointing mirror surface will directly lead to the decline of the performance index of the optical system.

As a front optical system, the pointing mirror is often installed outside the satellite or rover due to its wide range of rotation and dynamic field of view, and is directly exposed to the outer space environment and withstands harsh temperature environments, usually extremely low temperature environments. When there is not enough energy to heat and keep it warm, how to ensure the optical surface accuracy of the pointing mirror at low temperature becomes a key technical issue.

The excessive temperature load formed by the excessive temperature difference and the weight limitation of the on-board load make the simple thermal matching of materials and the unloading of the free end of the shafting, which cannot effectively solve the problem. Special elastic design and optimization of structural configuration are required to further reduce the additional bending moment and stress effect of temperature load on the mirror body, so that the surface shape accuracy of the pointing mirror at low temperature can meet the requirements of use.

Invention content:

The purpose of the present invention is to provide a device for supporting the rotating shaft system of a pointing mirror and a mirror body clamping device which can be used in a very low temperature environment. How to design a set of extremely light weight, very compact structure, capable of withstanding the severe vibration and impact load brought by the aircraft platform, and at the same time ensuring good surface accuracy of the pointing mirror when working at low temperature, is the purpose of the present invention. technical problems solved.

The present invention utilizes the U-shaped frame to carry out the main support of the mirror body and the shaft system, and realizes its symmetrical deformation at low temperature by installing a beam on the top of the U-shaped frame; Rotation; the two sections of shafting are designed as fixed support and floating support respectively, the fixed end is realized by paired angular contact bearings, the floating end is fixed by the inner ring, and the outer ring is free of self-aligning bearings; holes are opened on both sides of the reflector , use the adhesive to bond the insert with a double-layer flexible structure, and the insert is connected with the rotating shafts of the above two shafts through screws; in order to increase the connection firmness of the insert and the mirror body, there are pins and pins between them. It fits tightly with the insert, leaving a gap with the mirror body, and the gap is filled with resin.

The specific device is shown in Figures 1-4.

1. The fixed support shaft system 2 and the movable support shaft system 6 are respectively fixed in the openings on both sides of the top of the U-shaped frame 1; the beam 3 is fixed on the top of the U-shaped frame 1 by screws, and is equipped with a pin; the The mirror body inserts 5 are fixed in the inner holes on both sides of the reflector 4 by adhesive, and are respectively connected with the fixed support shaft system 2 and the movable support shaft system 6 on the outer end faces; one end of the pin 7 is connected with the mirror body insert block 5 Fit tightly, and the other end passes through the gap hole at the corresponding position on the back of the mirror 4, and fills the gap with epoxy resin.

2. The U-shaped frame 1 is made of a metal material that matches the thermal expansion coefficient of the reflector 4. The tops of the columns on both sides are open for supporting the shafting installation, the arc top processing platform of the column is used to install the beam 3, and the center hole at the bottom is used to install the beam 3. Used to communicate with other system optical paths;

3. The fixed support shaft system 2 includes the rotating shaft 2-1, the bearing seat 2-2, the paired angular contact bearing 2-3, the inner thread pressure ring 2-4, the outer thread pressure ring 2-5; the paired angular contact bearing 2-3 It is installed in the inner hole of the bearing seat 2-2, and the end face of the outer ring is in contact with the inner hole of the bearing seat 2-2; The end face of the inner ring of the bearing is fitted; the inner thread pressure ring 2-4 and the outer thread pressure ring 2-5 are respectively screwed into the rotating shaft 2-1 and the bearing seat 2-2 for the positioning and preloading of the paired angular contact bearing 2-3 force exerted;

4. The beam 3 is made of the same material as the U-shaped frame 1, and the configuration is an inverted U-shaped. It is fixed on the top of the U-shaped frame 1 by screws. After installation, it is equipped with pins to ensure reliable connection;

5. The mirror 4 is made of silicon carbide material, which has a central sandwich structure, and holes on both sides of the mirror body are used for the bonding and fixing of the mirror body inserts 5;

6. The mirror body insert 5 is made of invar material that matches the thermal expansion coefficient of the mirror 4, and three through arc-shaped grooves are processed on the outside to form the first layer of flexible structure 5-1, and then the outside of the elastic structure is formed. It is processed into a "T"-shaped structure 5-2 to increase the bonding area on the original elastic coefficient. This elastic structure can ensure the surface shape accuracy of the reflector 4 at low temperature;

7. For example, the floating support shaft system 6 includes a rotating shaft 6-1, a bearing seat 6-2, a double-row self-aligning bearing 6-3, and an external thread pressure ring 6-4; the double-row self-aligning bearing 6-3 is installed in the bearing seat In the inner hole of 6-2, the end face of the outer ring is fitted with the inner hole of the bearing seat 6-2; the shaft 6-1 is inserted into the inner ring of the double-row self-aligning bearing 6-3, and the shoulder of the bearing is in contact with the inner ring of the bearing. There is a certain gap on the end face; the external thread pressure ring 6-4 is screwed into the bearing seat 6-2 for the positioning of the double row self-aligning bearing 6-3;

8. The pin 7 is used to lock the position of the reflector 4. The pin 7 is made of invar material, one end is closely matched with the mirror body insert 5, and the other end passes through the gap hole at the corresponding position on the back of the reflector 4, and fills the ring at the gap. Oxygen resin.

The advantages of the present invention are:

1) The present invention greatly reduces the bending amount of the arms on both sides to both sides when the U-shaped frame itself is deformed at low temperature by simply adding a beam to the top of the conventional U-shaped frame. This bending deformation cannot pass through the shaft system. The axial unloading effect of the swimming support is canceled, and the additional moment generated thereby will cause a great deterioration of the mirror surface. Through the lightweight beam structure, the optical surface accuracy of the pointing mirror when working at low temperature is effectively improved;

2) The present invention improves the simple thermally matched rigid insert through the flexible structure at the periphery of the mirror insert during the clip design of the pointing mirror. This design can effectively reduce the adhesive glue between the insert and the mirror body. The thermal stress acting on the mirror caused by the shrinkage of the layer at low temperature; and the design of the positioning pin is added radially through the "T" structure and the insert on the outside of the flexible unit, which enhances the anti-surgical performance of the mirror body clamping;

3) The mirror body clamping and supporting design of the present invention significantly improves the surface shape accuracy of the pointing mirror at low temperature without adding any extra space and a small cost of quality.

Description of drawings:

1 is a schematic structural diagram of a mirror shafting support and clamping device of the present invention;

In the figure: 1——U-shaped frame;

2—fixed support shafting;

3 - beam;

4—reflector;

5 - Mirror body insert

6 - Swimming support shaft system

7 - pin

FIG. 2 is a schematic diagram of the structural composition of the fixed support shaft system 2;

In the picture: 2-1——rotating shaft;

2-2 - bearing seat;

2-3 - paired angular contact bearings;

2-4——Internal thread pressure ring;

2-5——external thread pressure ring;

3 is a schematic diagram of the structure of the mirror body insert 5;

In the figure: 5-1 - flexible structure;

5-2 - "T" type structure;

FIG. 4 is a schematic diagram of the structural composition of the swimming support shaft system 6;

In the picture: 6-1——Rotating shaft;

6-2 - bearing seat;

6-3——Double row self-aligning bearing;

6-4——external thread pressure ring;

Detailed ways:

A preferred embodiment of the present invention is given below according to FIGS. 1 to 4 to illustrate the structural features and implementation methods of the present invention, but not to limit the scope of the present invention.

The mirror shafting support and clamping device used at low temperature in this embodiment is applied to the front pointing mechanism of an optical instrument for detecting the surface of a planet that lacks resources and has no active temperature control at all. The total angle range of mirror rotation is 110°, and the beam diameter is 100mm. The working temperature is -80 ℃, the maximum overload acceleration reaches 30 gravity accelerations during the launch and landing of the aircraft, the random vibration root mean square acceleration is 23g, and the shock reaches 1800g. The device specifically includes the following parts: a U-shaped frame 1 , a fixed support shaft 2 , a beam 3 , a reflector 4 , a mirror body insert 5 , a floating support shaft 6 and a pin 7 .

1) U-shaped frame 1: It is made of high-component aluminum-based silicon carbide composite material with small thermal expansion coefficient, high modulus and low density. After careful lightweight design, the weight after processing is 300 grams. The top of the arms on both sides has a 30mm diameter round hole for supporting the shaft system installation, and the coaxiality of the round holes on both sides is better than 0.01mm, so as to ensure the coaxiality of the two sections of the shaft system. The arc top processing platform of the side arm is used to install the beam 3, and the diameter of the central circular hole at the bottom is 110mm for connecting with the main optical path;

2) Fixed support shaft system 2: including rotating shaft 2-1, bearing seat 2-2, matching angular contact bearing 2-3, inner thread pressure ring 2-4, and outer thread pressure ring 2-5. The paired angular contact bearings 2-3 use 71704AC ultra-thin-wall bearings with an accuracy grade of P4. They are installed in the inner hole of the bearing seat 2-2 after positioning and preloading by grinding the spacer. The bearing seat is made of titanium alloy TC4, and the thermal expansion coefficient is the same as U-frame and bearing material match. The end face of the outer ring of the bearing group is fitted with the inner hole of the bearing seat 2-2; the material of the shaft 2-1 is also TC4, which penetrates into the inner ring of the paired angular contact bearing 71704, and the shoulder face is attached to the end face of the inner ring of the bearing. There are 3 through holes with a diameter of 2.9mm on the end face of the rotating shaft, which are used to connect and fix the mirror insert; the inner thread pressure ring 2-4 and the outer thread pressure ring 2-5 are made of stainless steel and processed into fine thread with a pitch of 0.5 mm, screwed into the shaft 2-1 and the bearing seat 2-2 respectively, for the positioning and preload application of the paired angular contact bearing 2-3;

4. Beam 3: Made of the same material as U-shaped frame 1, high-component aluminum-based silicon carbide composite material, the configuration is an inverted U-shaped, and the design weight is only 25 grams. The beam mainly provides axial tensile and compressive and bending stiffness, so the width of the beam should be increased as much as possible in the design of the beam, and the thickness should be reduced to reduce the position restriction on the rotation of the mirror. The two sides are fixed on the top of the U-shaped frame 1 by 4 M2 screws. After installation, they are equipped with cylindrical pins with a diameter of 2.5mm to ensure the connection rigidity during the learning process;

5. Reflector 4: Made of silicon carbide material by reaction sintering process. A flat mirror in the shape of an ellipse. The short axis is 110mm and the long axis is 200mm. The mirror body is designed as a trapezoid-like structure, with a thickness of 20mm at the center along the long axis and a thickness of 4mm at the edge to reduce the weight of the mirror body. The mirror is a central sandwich structure, the reflective surface and the back are closed, and a lightening groove is opened in the vertical thickness direction. This design can maximize the rigidity of the mirror body under a certain weight, thereby reducing the beneficial deformation at low temperature. There are 14mm diameter semi-circular holes on both sides of the mirror body for bonding and fixing the mirror body inserts 5;

6. Mirror body insert 5: Made of invar 4J36 material that matches the thermal expansion coefficient of mirror 4, the shape is a semicircle with a diameter of 14mm and a thickness of 8mm. Three M2.5 threaded holes are machined on the end face of the insert for fixed connection with the shaft. The first layer of flexible structure 5-1 is formed by processing three penetrating arc-shaped grooves on the outside of the flexible structure. The span of the flexible structure is 8mm and the thickness is 0.5mm; In order to increase the bonding area on the original elastic coefficient, the length of the "T" structure beam is 12mm, the width is 8mm, and the thickness is 1mm; the length of the vertical column structure is 1mm and the width is 8mm. This elastic structure is formed by precision wire cutting, and the elastic structure parameters are optimized by simulation analysis, which can ensure the surface shape accuracy of the mirror 4 at low temperature and can withstand the required mechanical load; the insert and the mirror body pass through the ring Oxygen resin adhesive bonding, the thickness of the adhesive layer is 0.1mm, and there are three bonding points on both sides;

7. Such as swimming support shaft 6: including rotating shaft 6-1, bearing seat 6-2, double-row self-aligning bearing 6-3, external thread pressure ring 6-4; double-row self-aligning bearing 6-3 is specially designed , to ensure the two-dimensional free rotation of the axis while eliminating its radial clearance to meet the radial stiffness of the shafting support. The bearing is installed in the inner hole of the bearing seat 6-2, the end face of the outer ring is in contact with the inner hole of the bearing seat 6-2, and the material of the bearing seat is TC4; the rotating shaft 6-1 is inserted into the double row self-aligning bearing 6-3 There is a certain gap between the shoulder surface and the end face of the inner ring of the bearing. The material is also TC4, and the end face is machined with three through holes with a diameter of 2.9mm, which are used to connect with the pointing mirror insert; the outer thread pressure ring 6- 4 is made of stainless steel with fine thread, the pitch is 0.5mm, screwed into the bearing seat 6-2, used for the positioning of the double row self-aligning bearing 6-3; the bearing and the rotating shaft are directly unconstrained, so as to realize the axial direction of the floating end Thermal deformation unloading;

8. Pin 7: used to lock the position of the mirror 4 in the academic environment, the pin is a cylinder with a diameter of 2.5mm and is made of invar material. One end is in an interference fit with the mirror body insert 5, and the other end passes through the clearance hole at the corresponding position on the back of the reflector 4. The diameter of the clearance hole is 2.9mm, and epoxy resin is filled at the gap (0.2mm), which ensures reliable positioning. At the same time, the excessive impact of the rigid connection on the mirror body in the vibration environment is avoided.

As mentioned above, the shafting support and clamping design of the mirror can ensure the reliable support and clamping in the academic environment, and at the same time, the surface shape accuracy of the mirror can be satisfied when working at low temperature. In the shafting support, the additional effect of structural deformation on the mirror at low temperature can be effectively reduced by adding a beam on the top of the U-shaped frame and the optimized design of the supporting shaft at the floating end; The optimized design ensures that the mirror can resist large academic loads while unloading the low temperature thermal stress. The support and clamping device of the reflector has a compact structure and light weight, which can adapt to large overload and low temperature working environment, and can be applied to the point-and-shoot scanning mechanism outside the cabin that has strict requirements on quality and volume, and the heat environment and its harsh space. application.

Claims (8)

1. A mirror shafting support and clamping device used at low temperature, comprising a U-shaped frame (1), a fixed support shafting (2), a beam (3), a mirror (4), a mirror body insert (5), a swimming support shaft system (6) and a pin (7), characterized in that: The fixed support shaft system (2) and the floating support shaft system (6) are respectively fixed in the openings on both sides of the top of the U-shaped frame (1); the beam (3) is fixed on the U-shaped frame (3) by screws. 1) The top is equipped with pins; the mirror body inserts (5) are fixed in the inner holes on both sides of the reflector (4) by adhesive, and the outer end faces are respectively connected with the fixed support shaft system (2) and the floating support The shaft system (6) is connected; one end of the pin (7) is closely matched with the mirror body insert (5), and the other end passes through the gap hole at the corresponding position on the back of the reflector (4), and the gap is filled with epoxy resin . 2. A mirror shafting support and clamping device for use at low temperature as claimed in claim 1, wherein the U-shaped frame (1) is adapted to match the thermal expansion coefficient of the mirror (4). (±1) made of metal material, the tops of the columns on both sides are supported by the shaft system, and there is a circular arc top of the column where the beam (3) is installed, and the center hole at the bottom is connected to the optical paths of other systems. 3. The mirror shafting support and clamping device used at low temperature according to claim 1, wherein the fixed support shafting (2) comprises a rotating shaft (2-1), a bearing seat (2-2), paired angular contact bearing (2-3), inner thread pressure ring (2-4), outer thread pressure ring (2-5); The paired angular contact bearing (2-3) is installed in the inner hole of the bearing seat (2-2), and the end face of the outer ring is in contact with the inner hole of the bearing seat (2-2); the rotating shaft (2-1) Insert into the inner ring of the paired angular contact bearing (2-3), and its shoulder resting surface fits with the end face of the inner ring of the bearing; the inner thread pressure ring (2-4) and the outer thread pressure ring (2-5) are respectively screwed into the rotating shaft (2-1) and bearing seat (2-2), locating and applying preload and matching angular contact bearing (2-3). 4. A mirror shafting support and clamping device used at low temperature as claimed in claim 1, wherein the beam (3) is made of the same material as the U-shaped frame (1). , the configuration is an inverted U shape, which is fixed on the top of the U-shaped frame (1) by screws, and is equipped with a pin (7) after installation to ensure reliable connection. 5. The mirror shafting support and clamping device used at low temperature according to claim 1, wherein the mirror (4) is made of silicon carbide material, and has a central sandwich structure , and the mirror body inserts (5) are glued and fixed on both sides of the mirror body. 6. A mirror shafting support and clamping device for use at low temperature as claimed in claim 1, wherein the mirror body insert (5) is adapted to match the thermal expansion coefficient of the mirror (4). It is made of invar material, and three through arc-shaped grooves are processed on the outside to form the first layer of flexible structure (5-1), and then the outside of the elastic structure is processed into a "T"-shaped structure (5-2), In order to increase the bonding area on the original elastic coefficient, this elastic structure can ensure the surface shape accuracy of the reflector (4) at low temperature. 7. A mirror shafting support and clamping device for use at low temperature according to claim 1, characterized in that, the floating support shafting (6) comprises a rotating shaft (6-1), a bearing Seat (6-2), double row self-aligning bearing (6-3), external thread pressure ring (6-4); The double-row self-aligning bearing (6-3) is installed in the inner hole of the bearing seat (6-2), and the end face of the outer ring is in contact with the inner hole of the bearing seat (6-2); the rotating shaft (6-1) ) into the inner ring of the double-row self-aligning bearing (6-3), leaving a certain gap between the shoulder surface and the end face of the inner ring of the bearing; the outer thread pressure ring (6-4) is screwed into the bearing seat (6-2) , for the positioning of double row self-aligning bearings (6-3). 8 . The mirror shafting support and clamping device used at low temperature according to claim 1 , characterized in that the pins ( 7 ) are made of invar material. 9 .