High-precision low-stress assembly method for separated truss of space camera

Abstract

The invention discloses a high-precision low-stress assembly method for a space camera separation type truss, which comprises the following steps: carrying out multi-point support on an optical platform, integrally placing the optical platform on a marble platform, and carrying out high-precision positioning installation on the lower end surface of a truss rod and the optical platform; the gravity unloading force of the truss is calculated, a gravity unloading tool is designed and built, gravity unloading is conducted on the upper end of the truss, and gravity deformation of the truss in the state is compensated; a high-precision truss positioning tool is designed to position and install the separated truss, the gravity unloading force of the top end of the truss is monitored in the installation process, and it is guaranteed that the change of the force is within the allowance range; detecting and grinding a mounting surface formed at the top end of the truss to ensure that the planeness and parallelism of the mounting surface meet the design requirements; and the truss top plate and the top end face of the truss are installed, and the high-precision positioning tool is taken down. According to the technical scheme, the problem of residual stress deformation caused by the influence of gravity and assembly precision when the separated truss of the space camera is assembled and adjusted is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of space optical remote sensing and relates to a high-precision and low-stress assembly method of a separated truss of a space camera. Background Art

[0002] Space cameras are important instruments for humans to observe ground and space targets. As humans demand higher-resolution observations, they are gradually developing in the direction of large apertures and long focal lengths. However, as the focal length of space cameras increases, higher requirements are placed on the form and position tolerances and thermodynamic stability of the main supporting structure connecting the core optical elements.

[0003] The separated truss is a main support structure that realizes the connection and positional relationship of the primary and secondary mirrors of a long focal length space camera. The idea of ​​assembling and splicing separated truss units to form the main support greatly reduces the difficulty of processing and manufacturing the main support structure. However, in order to meet the shape and position tolerance requirements of the primary and secondary mirrors of a long focal length space camera, a higher assembly accuracy is required. In addition, due to the influence of gravity, it is difficult to ensure the ideal positional relationship of the separated truss structure during ground assembly and adjustment. When working in orbit, structural stress will be generated due to the release of gravity, which will lead to changes in the installation position of the optical components.

[0004] On the one hand, due to the limitations of current processing and manufacturing capabilities, the coplanarity of the upper end faces of the trusses composed of separate trusses is often poor, and direct installation will bring about greater assembly stress; on the other hand, the separate trusses will have a certain position deformation during assembly due to the influence of ground gravity, and direct assembly will generate greater assembly stress. Summary of the invention

[0005] The present invention aims to solve the problem of high-precision and low-stress installation and adjustment of a space camera separated truss structure on the ground. A high-precision and low-stress assembly method of a space camera separated truss is proposed, which can ensure the consistency of the separated truss ground assembly with the on-orbit application structure position.

[0006] A high-precision, low-stress assembly method for a space camera separated truss, wherein the separated truss main support structure comprises an optical platform, a truss rod and a truss top plate, wherein a gravity unloading device comprises a grid, a suspension point transfer tooling and a gravity unloading adjustment tooling, wherein the grid is in a U-shape arranged symmetrically on both sides and is formed by splicing a porous spherical joint and a support frame connecting rod; the suspension point transfer tooling comprises a pair of wedges, a profile frame, a hanging plate and a hanging plate hook, wherein the hanging plate is installed at the geometric center of the profile frame, and the installation position of the hanging plate hook is aligned with the center of the gravity unloading installation position of the upper end face of the truss rod; the gravity unloading adjustment tooling comprises a hanging line, an adjustable hook, a dynamometer and a truss upper end face interface transfer block, wherein one end of the gravity unloading tooling is connected to the truss rod and the other end is connected to the hanging plate hook, and the magnitude of the force applied to the top face of the truss rod can be adjusted by adjusting the adjustable hook, and the dynamometer can display the applied unloading force in real time, and the method comprises the following steps:

[0007] Step 1: Assemble with the optical axis vertically upward: Use equal-height blocks to support the optical platform at multiple points and place it as a whole on a leveled marble platform, and position and install the lower end surface of the truss rod and the optical platform;

[0008] Step 2: Build the grid, assemble the hanging point transfer tooling, and then preliminarily install the hanging point transfer tooling on the grid;

[0009] Step 3: Install the truss rods at corresponding positions on the optical platform;

[0010] Step 4: Calculate the unloading force required for the truss under the action of gravity in the vertical direction, build a gravity unloading device, and gravity unload the truss top plate;

[0011] Step 5: Connect the truss rod positioning fixture and the truss rod as a whole. During the installation process, monitor the gravity unloading force of the truss top plate to ensure that the force change is within the tolerance range;

[0012] Step 6: Disassemble the gravity unloading device, inspect and grind the coplanarity formed by the top surface of the truss rod to ensure that its flatness meets the design requirements;

[0013] Step 7: Install the truss top plate and the top surface of the truss, and remove the truss rod positioning tooling. At this point, the high-precision assembly of the space camera separate truss is completed.

[0014] The beneficial effects of the present invention are:

[0015] 1. The present invention proposes a high-precision and low-stress assembly method for a space camera separated truss, which can effectively guide the high-precision assembly of similar products;

[0016] 2. When the separated truss rod and optical platform are installed between the truss top plate and the upper end surface of the truss, the cylindrical pins are used for positioning, which can greatly improve the installation position accuracy and facilitate the subsequent optical assembly and adjustment;

[0017] 3. The present invention adopts a vertical upward assembly method, and by gravity unloading the truss rod, the influence of gravity deformation during the assembly of the truss rod can be effectively eliminated, thereby avoiding additional assembly stress and improving the stability of the assembled structure;

[0018] 4. The present invention uses a high-precision truss rod positioning tool to fix the separated truss rods into a whole, and grinds the combined surface of the upper end surface of the truss to improve the coplanarity accuracy of the combined installation surface. After the truss top plate is installed, the assembly stress can be effectively reduced and the stability of the assembled structure can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a high-precision, low-stress assembly device for a space camera separated truss of the present invention;

[0020] Figure 2 The gravity unloading device of the present invention;

[0021] Figure 3 The lifting point transfer tool of the present invention;

[0022] Figure 4 The gravity unloading adjustment tool of the present invention;

[0023] Figure 5 It is a schematic diagram of the truss rod positioning tool structure of the present invention;

[0024] Figure 6 It is a schematic diagram of the separated truss main support structure of the present invention;

[0025] Among them, 1 is a grid, 2 is a hanging point adapter tool, 2-1 is a pair of wedges, 2-2 is a profile frame, 2-3 is a hanging plate, 2-4 is a hanging plate hook, 3 is a gravity unloading adjustment tool, 3-1 is a hanging line, 3-2 is an adjustable hook, 3-3 is a force gauge, 3-4 is a truss upper end surface interface adapter block, 4 is a truss rod positioning tool, 5 is a truss rod, 6 is an optical platform, 7 is an equal height block, 8 is a marble platform, and 9 is a truss top plate. DETAILED DESCRIPTION

[0026] In order to clearly illustrate the implementation process, the features and advantages of the auxiliary tooling of the present invention, the following takes the main support structure of three common separated trusses as an example, combined with the attached Figure 1 ~Attached Figure 6 The present invention is further described in detail. Figure 1 Three separated trusses are shown as an example, but it should be understood that the present invention is not limited in the number of trusses.

[0027] The main support structure of the separated truss includes an optical platform 6, a truss rod 5 and a truss top plate 9. The gravity unloading device consists of a grid 1, a suspension point transfer fixture 2 and a gravity unloading adjustment fixture 3. The grid 1 is in a U-shape arranged symmetrically on both sides, and is spliced ​​by a porous spherical joint and a support frame connecting rod; the suspension point transfer fixture 2 consists of a pair of wedges 2-1, a profile frame 2-2, a hanging plate 2-3 and a hanging plate hook 2-4. The hanging plate 2-3 is installed at the geometric center of the profile frame 2-2, and the installation position of the hanging plate hook 2-4 is aligned with the center of the gravity unloading installation position on the upper end face of the truss rod 5; the gravity unloading adjustment fixture 3 consists of a hanging line 3-1, an adjustable hook 3-2, a dynamometer (or a high-precision electronic scale) 3-3 and a truss upper end face interface adapter block 3-4. One end of the gravity unloading tool 3 is connected to the truss rod 5, and the other end is connected to the hanging plate hook 2-4. The force applied to the top surface of the truss rod can be adjusted by adjusting the adjustable hook 3-2, and the dynamometer 3-3 can display the applied unloading force in real time. The above structure is not described in detail and belongs to the content well known to those skilled in the art.

[0028] According to an embodiment of the present invention, a high-precision and low-stress assembly method for a space camera separated truss is provided, the method comprising the following steps:

[0029] Step 1: This assembly method is to assemble with the optical axis vertically upward. The optical platform 6 is supported at multiple points by the equal height blocks 7 and placed as a whole on the leveled marble platform 8. Among them, the marble platform 8 is leveled before placement, and the leveling accuracy is better than 1′, which can be measured with a level; the marble platform 8 is 00 grade, and the equal height of the equal height blocks 7 for multi-point support is better than 0.01mm;

[0030] Step 2: Build the grid 1, assemble the hanging point transfer tooling 2, and then preliminarily install the hanging point transfer tooling 2 on the grid 1. The process includes: adjusting the position of the grid 1 so that the deviation between the position of the hanging plate hook 2-4 along the gravity unloading direction and the gravity unloading theoretical position of the truss rod is less than 5mm, which can be measured by hanging a plumb line. After adjustment, the thickness of the paired wedges 2-1 is adjusted to ensure that the horizontality of the hanging point transfer tooling 2 is better than 1′, and the horizontality can be measured with a level;

[0031] Step 3: Install the truss rods 5 at the corresponding positions on the optical platform 6, including: each truss rod has two cylindrical pin holes at the bottom end, and the corresponding positions of the optical platform also have corresponding cylindrical pin holes, such as Figure 6 As shown, the position accuracy is better than 0.02mm. Through the positioning installation of the cylindrical pin, the high-precision positioning installation of the truss rod 5 can be achieved, wherein the gap between the cylindrical pin and the cylindrical pin hole is better than 0.015mm;

[0032] Step 4: Calculate the unloading force required for the truss rod under the action of gravity in the vertical direction, build a gravity unloading device, and gravity unload the truss top plate to ensure that the position accuracy of the truss rod is negligibly affected by gravity. This step includes: installing the gravity unloading adjustment tooling 3 with the suspension point adapter tooling 2 and the truss top plate 9, wherein the suspension line 3-1 is connected to the suspension plate hook 2-4, and the truss upper end surface interface adapter block 3-4 is connected to the truss top plate 9. After installation, adjust the adjustable hook 3-2 so that the values ​​of the three dynamometers 3-3 are all 48.2N (this value is obtained by finite element calculation).

[0033] Gravity unloading is to eliminate the assembly stress introduced by the self-weight deformation of the truss rod. It is related to the direction of gravity on the truss rod and the position where gravity unloading is performed. This method is to apply a vertical upward force to the top of the truss rod in a vertical state to perform gravity unloading. The gravity unloading force can be obtained by theoretical calculation and finite element analysis.

[0034] Step 5: Connect the truss rod positioning fixture 4 and the truss rod 5 as a whole. During the installation process, monitor the gravity unloading force of the truss top plate 9 to ensure that the force change is within the tolerance range. The detailed process of this step is described below: After step 4, the truss rod 5 is in a gravity unloading state, and its position is in the designed theoretical position after gravity unloading. At this time, the truss rod positioning fixture 4 is fixedly connected to the three truss rods 5 to facilitate subsequent grinding. Since the processing error of the angle of the three mounting surfaces of the truss rod positioning fixture 4 is better than 0.005°, and the flatness is better than 0.003mm, the assembly stress caused by the truss after the connection can be ignored. The magnitude of the assembly stress can also be inferred by monitoring the change in the indication of the dynamometer 3-3. The change in the indication of the dynamometer 3-3 is required to be less than 0.1N. If the indication exceeds 0.1N during assembly, the position of the truss rod positioning fixture 4 is appropriately adjusted until the requirement is met. The angular error of the mounting surface between the truss rod positioning fixture 4 and the truss group 5 needs to be controlled, and is required to be better than 0.005°. When installing the truss rod positioning fixture 4, the unloading force displayed by the dynamometer needs to be monitored, and the change is required to be no greater than 0.1N. Figure 5 It is a schematic diagram of the truss rod positioning tool structure of the present invention.

[0035] Step 6: Dismantle the gravity unloading device, inspect and grind the coplanarity formed by the top end surface of the truss rod to ensure that its flatness meets the design requirements. This step may include: manually grinding the truss top plate 9, and measuring the flatness of the combined plane of the truss upper end surface with a laser tracker while grinding, until the flatness of the plane is better than 0.01mm;

[0036] Step 7: Install the truss top plate 9 with the top surface of the truss, remove the truss rod positioning tool 4, and complete the high-precision assembly of the split truss. This step may include: after the flatness of the combined plane of the upper end surface of the truss meets the requirements, install the truss top plate 9, and the truss top plate 9 and the upper end surface of the truss are also high-precision positioned by pins, in a similar way to the high-precision positioning in step 3.

Claims

1. A high-precision, low-stress assembly method for a space camera separated truss, characterized in that: The separated truss main support structure comprises an optical platform (6), a truss rod (5) and a truss top plate (9); the gravity unloading device comprises a grid frame (1), a suspension point transfer fixture (2) and a gravity unloading adjustment fixture (3); the grid frame (1) is in a U-shape arranged symmetrically on both sides and is formed by splicing a porous spherical joint and a support frame connecting rod; the suspension point transfer fixture (2) comprises a pair of wedges (2-1), a profile frame (2-2), a suspension plate (2-3) and a suspension plate hook (2-4); the suspension plate (2-3) is installed at the geometric center of the profile frame (2-2); the suspension plate hook ( 2-4) The installation position is aligned with the center of the gravity unloading installation position on the upper end surface of the truss rod (5); the gravity unloading adjustment tool (3) is composed of a suspension line (3-1), an adjustable hook (3-2), a dynamometer (3-3) and a truss upper end surface interface adapter block (3-4); one end of the gravity unloading tool (3) is connected to the truss rod (5) and the other end is connected to the suspension plate hook (2-4); the magnitude of the force applied to the top surface of the truss rod can be adjusted by adjusting the adjustable hook (3-2); the dynamometer (3-3) can display the applied unloading force in real time; the method comprises the following steps: Step 1: Assemble with the optical axis vertically upward: support the optical platform (6) at multiple points through equal height blocks (7) and place the entire platform on a leveled marble platform (8), and position and install the lower end surface of the truss rod (5) and the optical platform (6); Step 2: construct the grid frame (1), assemble the hanging point transfer tooling (2), and then preliminarily install the hanging point transfer tooling (2) on the grid frame (1); Step 3: Install the truss rods (5) at corresponding positions on the optical platform (6); Step 4: Calculate the unloading force required for the truss under the action of gravity in the vertical direction, build a gravity unloading device, and perform gravity unloading on the truss top plate (9); Step 5: Connect the truss rod positioning fixture (4) and the truss rod (5) into a whole, and monitor the gravity unloading force of the truss top plate (9) during the installation process to ensure that the force change is within the tolerance range; Step 6: Disassemble the gravity unloading device, inspect and grind the coplanarity formed by the top surface of the truss rod to ensure that its flatness meets the design requirements; Step 7: Install the truss top plate (9) and the top surface of the truss, and remove the truss rod positioning tool (4). At this point, the high-precision assembly of the space camera separated truss is completed.

2. The high-precision and low-stress assembly method of the space camera separated truss according to claim 1, characterized in that: The height of the height-conforming blocks (7) is better than 0.01 mm, the marble platform (8) is of grade 00 and its leveling accuracy is better than 1′.

3. The high-precision and low-stress assembly method of the space camera separated truss according to claim 1, characterized in that: Step three includes: each truss rod has two cylindrical pin holes at the bottom end, and the optical platform also has corresponding cylindrical pin holes at the corresponding positions, and the position accuracy is better than 0.02 mm. The installation between the lower end surface of the truss rod (5) and the optical platform (6) is carried out through the two cylindrical pin holes matched between the bottom end of the truss rod (5) and the optical platform.

4. The high-precision and low-stress assembly method of the space camera separated truss according to claim 1, characterized in that: Step 4 includes: The gravity unloading adjustment tool (3) is installed with the suspension point transfer tool (2) and the truss top plate (9), wherein the suspension wire (3-1) is connected with the suspension plate hook (2-4), and the truss upper end surface interface transfer block (3-4) is connected with the truss top plate (9). After installation, the adjustable hook (3-2) is adjusted so that the value of the dynamometer (3-3) is 48.2N.

5. The high-precision and low-stress assembly method of the space camera separated truss according to claim 1, characterized in that: Step 2 includes: The position of the grid (1) is adjusted so that the position of the hanging plate hook (2-4) along the gravity unloading direction deviates from the gravity unloading theoretical position of the truss rod by less than 5 mm. After the adjustment, the thickness of the paired wedge blocks (2-1) is adjusted to ensure that the horizontality of the hanging point transfer tooling 2 is better than 1′.

6. The high-precision and low-stress assembly method of the space camera separated truss according to claim 1, characterized in that: Step 4 includes: the angle error of the mounting surface between the truss rod positioning fixture (4) and the truss group (5) is better than 0.005°, and when the truss rod positioning fixture (4) is installed, the unloading force displayed by the dynamometer is monitored, and the change is required to be no greater than 0.1N.

7. The high-precision and low-stress assembly method of the space camera separated truss according to claim 1, characterized in that: Step six includes: grinding the coplanar surface formed by the top end surface of the truss rod until the flatness of the coplanar surface is better than 0.01 mm, and the flatness is measured by a laser tracker.

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