Flexible hinge for spatial parallel directional vibration isolation platform and mounting method

Abstract

The invention relates to a flexible hinge for a spatial parallel directional vibration isolation platform and an installation method, and relates to the field of spatial control execution mechanisms. A tubular sheath wraps a radial limiting part, a radial positioning part and a hinge, and the top of the tubular sheath is connected with the radial positioning part to radially position the flexible hinge; a gap is formed between the bottom of the sheath and the radial limiting part to form secondary corner limiting; a plurality of groups of cutting grooves penetrate through the wall surface of the hinge, and the appearances of the adjacent cutting grooves are symmetrical along the cross section of the hinge; the groove width of the same part of the cutting groove and the hinge axis direction and the bending part is greater than the groove width of the part parallel to the hinge cross section; the L-shaped flexible beam is embedded into the wide part of the cutting groove; the groove width of the part parallel to the cross section of the hinge forms primary corner limit, the primary corner limit is larger than the maximum corner of the flexible hinge, the secondary corner limit is larger than the primary corner limit, and the flexible hinge has the advantages that the service life of the flexible hinge is effectively prolonged, and the reliability of the flexible hinge is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of space control actuator technology, and in particular to a flexible hinge and its installation method for a space parallel directional vibration isolation platform. Background Technology

[0002] In recent years, high-performance spacecraft have placed extremely high demands on the pointing accuracy, stability, and maneuverability of payloads. By employing multi-stage verification control technology and installing a parallel pointing and vibration isolation platform between the payload and the satellite platform, active pointing and active / passive vibration suppression functions are achieved. Combined with control technology, this enables precise pointing and rapid stabilization control of the payload.

[0003] The flexible actuator is the execution mechanism for the space-connected parallel pointing vibration isolation platform. The output shaft of the flexible actuator is connected to the satellite payload platform via a flexible hinge, which converts the linear motion output by the actuator into the rotational motion of the payload platform. The flexible hinge moves continuously and uninterruptedly during its on-orbit operation, directly affecting the lifespan and reliability of the flexible actuator, making it a key component of the space-connected parallel pointing platform.

[0004] Given the long-term, non-maintainable nature of spacecraft products operating in orbit, and considering the application requirements of parallel directional vibration isolation platforms in space, it is necessary to maximize the lifespan and reliability of flexible hinge components. Existing flexible hinge design technologies have studied the relationship between the geometric parameters, stiffness, and stress of flexible hinges, but have not considered the impact of factors such as installation methods, assembly methods, and production process control on the service life and reliability of flexible hinges.

[0005] Therefore, to address the above shortcomings, it is necessary to provide a flexible hinge and installation method for a spatially parallel directional vibration isolation platform. Summary of the Invention

[0006] (a) Technical problems to be solved The technical problem to be solved by this invention is how to improve the service life of flexible hinges.

[0007] (II) Technical Solution To address the aforementioned technical problems, this invention provides a flexible hinge for a spatially parallel directional vibration isolation platform, comprising a radial limiting part, a radial positioning part, a hinge, a flexible beam, a slot, and a sheath. The annular radial limiting part is fixed to the bottom of the tubular flexible hinge, and the annular radial positioning part is fixed to the top of the hinge. The tubular sheath covers the radial limiting part, the radial positioning part, and the hinge, with its top connected to the radial positioning part for radial positioning of the flexible hinge. A gap exists between the bottom of the sheath and the radial limiting part to form a secondary rotation angle limiting. The slot is U-shaped, with several sets of slots penetrating the hinge wall, and the shapes of adjacent slots are symmetrical along the hinge cross-section. The slot width of the portion of the slot aligned with the hinge axis and the bent portion is greater than the slot width of the portion parallel to the hinge cross-section. The U-shaped flexible beam is embedded within the wider portion of the slot. The slot width of the portion parallel to the hinge cross-section constitutes a primary rotation angle limiting, which is greater than the maximum rotation angle of the flexible hinge, and the secondary rotation angle limiting is greater than the primary rotation angle limiting.

[0008] As a further explanation of the present invention, preferably, the radial limiting part, the radial positioning part, and the hinge are made of beryllium bronze or titanium alloy, with a minimum strength limit of 1000 MPa.

[0009] As a further explanation of the present invention, preferably, the flexible beam is a thin plate structure, and the width of the flexible beam is not less than 2 mm.

[0010] As a further explanation of the present invention, preferably, both the flexible beam and the bend of the groove are provided with rounded corners, and the radius of the rounded corners is not less than 1 mm.

[0011] As a further explanation of the present invention, preferably, the grooving is processed by a slow wire EDM method, and the surface roughness of the inner end face of the grooving is not less than Ra0.8.

[0012] As a further explanation of the present invention, preferably, the groove located on the portion parallel to the cross-section of the flexible hinge has a phase difference of 45° with the rotation direction of the flexible hinge.

[0013] As a further explanation of the present invention, preferably, a satellite payload bracket is fixedly connected to the radial positioning surface, and the actuator output shaft is mounted on the lower end face of the flexible hinge through an output shaft mounting flange. The inner hole of the actuator output shaft is engaged with the outer circular surface of the output shaft positioning surface so that the output shaft and the flexible hinge are radially positioned. The flexible hinge and the satellite payload bracket are positioned by inserting a cylindrical pin in the positioning pin hole.

[0014] The present invention also provides a method for installing a flexible hinge for a spatially parallel directional vibration isolation platform, comprising the following steps: Ⅰ. Install the flexible hinge on the actuator output shaft, and then fit the sheath over the flexible hinge. The actuator output shaft and the flexible hinge are radially positioned through the output shaft positioning surface and axially connected through the output shaft mounting flange. II. The satellite payload support abuts against the upper end face of the flexible hinge, and a cylindrical pin is installed in the positioning pin hole to position the flexible hinge and the satellite payload support; Ⅲ. Strain gauges are arranged in the groove of the flexible hinge, and the strain gauges are connected to an information acquisition device; VI. When installing the connecting screws of the satellite load support and the flexible hinge, simultaneously observe the strain changes displayed on the information acquisition device to ensure that the strain value does not exceed the set threshold range after installation; V. Remove the strain gauges, and finally move the sheath upwards along the axis of the actuator output shaft until it comes into contact with the satellite payload support and is secured with bolts.

[0015] As a further illustration of the present invention, preferably, the strain gauge is attached to the side wall of the flexible beam.

[0016] (III) Beneficial Effects The above-described technical solution of the present invention has the following advantages: 1. This invention optimizes the structure of the flexible hinge and reduces stress concentration in the flexible hinge by combining it with strain measurement during installation, thereby reducing the working stress level of the parts and improving the fatigue life of the parts.

[0017] 2. By rationally designing the groove size and adding an external mounting sleeve, two-level limiting of the flexible hinge is achieved, avoiding deformation and breakage of the flexible hinge due to excessive load, which would affect the reliability of the mechanism, and preventing foreign objects from entering the flexible hinge. Attached Figure Description

[0018] Figure 1 This is a diagram of the flexible hinge structure of the present invention; Figure 2 This is a diagram of the internal structure of the flexible hinge of the present invention; Figure 3 This is a dimension diagram of the flexible beam of the present invention; Figure 4 This is a diagram of the flexible hinge mounting structure of the present invention; Figure 5 yes Figure 4 Enlarged view of A in the middle; Figure 6 This is a diagram showing the strain gauge bonding positions of the present invention.

[0019] In the figure: 1. Radial limiting part; 11. Output shaft positioning surface; 2. Radial positioning part; 3. Hinge; 4. Flexible beam; 5. Groove; 6. Sheath; 7. Actuator output shaft; 8. Satellite load bracket; 81. Positioning pin hole; 9. Strain gauge. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] A flexible hinge for a spatially parallel directional vibration isolation platform, combined with Figure 1 , Figure 2 The system includes a radial limiting part 1, a radial positioning part 2, a hinge 3, a flexible beam 4, a slot 5, and a sheath 6. The annular radial limiting part 1 is fixed to the bottom of the tubular flexible hinge 3, and the annular radial positioning part 2 is fixed to the top of the hinge 3. The tubular sheath 6 covers the radial limiting part 1, the radial positioning part 2, and the hinge 3, and its top is connected to the radial positioning part 2 to radially position the flexible hinge. Several sets of slots 5 penetrate the wall of the hinge 3, and the shape of adjacent slots 5 is symmetrical along the cross-section of the hinge 3. The F-shaped flexible beam 4 is embedded in the wide part of the slot 5.

[0023] Combination Figure 1 , Figure 2 The radial limiting part 1, radial positioning part 2, and hinge 3 are hollow rotating bodies made of beryllium bronze or titanium alloy. Through aging and heat treatment, the material's tensile strength is increased to over 1000 MPa, giving the material a high fatigue life limit. Taking solution-treated beryllium bronze rods as an example, with material grade QBe2C, the parts undergo aging treatment after machining. The aging temperature is 310–330ºC, held for 2 hours, and then cooled in the furnace. Before aging treatment, the tensile strength of the material is 400–600 MPa; after aging treatment, the tensile strength reaches 1100–1380 MPa.

[0024] Combination Figure 1 , Figure 3 The flexible beam 4 is a thin plate structure. The stiffness of the flexible hinge is mainly determined by the width t and height h of the flexible beam 4. In the design process of the flexible hinge, the diameter and height range of the flexible hinge are first determined according to the spatial dimensions of the application mechanism. Under the premise of minimizing the bending stress of the flexible hinge, the stiffness of the flexible hinge is designed by adjusting the dimensional parameters t and h. In order to reduce the stress concentration during the operation of the flexible hinge and improve the fatigue resistance of the parts, the design elements of the fillet and groove width of the flexible beam 4 include two aspects: adopting a large fillet design, with fillet radii r1, r2, and r3 all not less than 1 mm; and adopting a large groove width design, with groove widths w2 and w3 at the deformation part of the flexible hinge not less than 2 mm.

[0025] Combination Figure 1 , Figure 3The grooves 5 are U-shaped, and the four sets of grooves 5 are symmetrically distributed relative to the center of the cylinder of the hinge 3, that is, the shape of adjacent grooves 5 is symmetrical along the cross-section of the hinge 3. To reduce stress concentration in the flexible hinge and improve fatigue resistance, the grooves 5 of the flexible hinge flexible beam 4 are machined using a slow wire EDM method, and the machining process parameters are controlled to ensure that the surface roughness of the machined groove 5 is not less than Ra0.8. w1 is the groove width of the non-deformable stress-bearing part of the flexible beam, which serves as the primary limit design for the rotation angle of the flexible hinge. When the flexible beam 4 of the flexible hinge undergoes bending deformation, the groove width at this part decreases. When the deformation of the flexible beam 4 exceeds the required stroke of the flexible hinge, the two sides of this groove 5 part come into contact. At this time, the load-bearing capacity of the flexible hinge is jointly borne by the flexible beam 4 and other non-flexible parts, avoiding excessive load on the flexible beam 4 and deformation damage.

[0026] Combination Figure 4 , Figure 5 An actuator output shaft 7 is fixedly connected to the radial limiting part 1 at the bottom of the flexible hinge. The radial limiting part 1 at the bottom of the flexible hinge and the actuator output shaft 7 are axially connected through a mounting flange. The bottom of the radial limiting part 1 is provided with a columnar output shaft positioning surface 11. The output shaft positioning surface 11 is inserted into the actuator output shaft 6 to achieve radial positioning with a clearance fit between the shaft and the hole. The radial limiting part 1 at the top of the hinge 3 is connected to the satellite payload bracket 8 by bolts. The radial positioning part 2 at the top of the flexible hinge is provided with a positioning pin hole 81. A cylindrical pin for positioning is also inserted between the positioning pin hole 81 and the satellite payload bracket 8.

[0027] The rotation direction of the flexible hinge is as follows Figure 4 As indicated by the arrow, to reduce the working stress of the flexible hinge, the installation phase difference between the groove 5 direction of the flexible beam 4 and the rotation plane of the flexible hinge is 45°. Taking the rated simulation data of a certain model of flexible hinge as an example, the flexible hinge is made of titanium alloy. When the groove 5 direction of the flexible beam 4 is orthogonal to the rotation plane of the flexible hinge, the maximum working stress of the flexible hinge when it rotates 1.2° is 322MPa. However, the present invention adopts a design where the groove 5 direction of the flexible beam 4 is at a 45° angle to the rotation plane of the flexible hinge, and the maximum working stress of the flexible hinge when it rotates 1.2° is 133MPa. Therefore, the 45° installation in this application can reduce the maximum working stress of the flexible hinge by 58.7% compared with the prior art, significantly improving the mechanical properties and on-orbit service life of the flexible hinge.

[0028] Combination Figure 4 , Figure 5The sheath 6 and the radial limiting part 1 have a gap w4. Gap w4 is the secondary limiting gap of the flexible hinge. The rotation angle range of the flexible hinge limited by this limiting gap should be greater than the rotation angle range limited by the primary limiting gap of the flexible hinge, and the stress of the flexible hinge should be reasonably designed. Taking a certain model of flexible hinge as an example, the flexible hinge is made of titanium alloy with a yield strength of 825 MPa. Taking a certain model as an example, the maximum working angle required by the flexible hinge under actual working conditions is only ±1.2°. The primary limiting gap w1 of the flexible hinge is designed to limit the rotation angle range of ±1.5°, and the secondary limiting gap w4 is designed to limit the rotation angle range of ±2.2°. When the deformation of the flexible hinge reaches ±2.2°, the maximum stress of the flexible hinge is 207 MPa, retaining a certain strength margin. Moreover, in extreme cases, when the flexible hinge bears an abnormally large load, the sheath 6 can ensure the reliable connection between the actuator output shaft 7 and the satellite payload support 8, ensuring that the load does not disengage. Meanwhile, the sheath 6 can prevent excess material from entering the slot 5, so as not to affect the movement of the flexible hinge.

[0029] The present invention also provides a method for installing a flexible hinge for a spatially parallel directional vibration isolation platform, comprising the following steps: Ⅰ. Install the flexible hinge on the actuator output shaft 7, and then fit the sheath 6 on the outside of the flexible hinge. The actuator output shaft 7 and the flexible hinge are radially positioned through the output shaft positioning surface 2, and axially connected through the output shaft mounting flange. II. The satellite payload bracket 8 abuts against the upper end face of the flexible hinge, and a cylindrical pin is installed in the positioning pin hole to position the flexible hinge and the satellite payload bracket 8; III. Strain gauges 9 are arranged in the groove 5 of the flexible hinge, and the strain gauges 9 are connected to the information acquisition device; VI. When installing the connecting screws of the satellite load support 8 and the flexible hinge, simultaneously observe the strain changes displayed on the information acquisition device to ensure that the strain value does not exceed the set threshold range after installation; V. Remove strain gauge 9, and finally move the sheath 6 upward along the axis of the actuator output shaft 7 until it abuts against the satellite payload bracket 8 and is fixed with bolts.

[0030] like Figure 6As shown, based on the test results, during the assembly process, the sidewall of the groove 5 of the flexible beam 4 is more sensitive to assembly stress. Two strain gauges 9 are attached to the sidewall of the flexible beam 4. One strain gauge 9 is located at the bottom of the groove 5, and the other is located at the top of the groove 5. Taking a certain type of flexible hinge as an example, the flexible hinge is made of titanium alloy. During assembly, the strain measurement value of the strain gauge 9 at the bottom of the groove 5 generally does not exceed ±800με, and the strain measurement value of the strain gauge 9 at the top of the groove 5 generally does not exceed ±1000με. The strain measurement value of the strain gauge 9 at the bottom of the groove 5 of the flexible hinge assembled using this method generally does not exceed ±180με, and the strain measurement value of the strain gauge 9 at the top of the groove 5 generally does not exceed ±180με, which is equivalent to a deformation stress of no more than 20MPa after the flexible hinge assembly.

[0031] In summary, this invention achieves two-stage limiting of the flexible hinge by rationally designing the dimensions of the slot 5 and adding an external mounting sleeve 6. This avoids deformation and breakage of the flexible hinge due to excessive load, which could affect the reliability of the mechanism, while also preventing foreign objects from entering the flexible hinge. By monitoring the deformation stress of the flexible hinge during assembly, assembly stress is effectively reduced, further improving the fatigue resistance of the parts. Ultimately, this achieves the effects of reducing stress concentration in the flexible hinge, lowering the working stress level of the parts, and improving the fatigue life of the parts.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible hinge for a spatially parallel directional vibration isolation platform, characterized in that: It includes a radial limiting part (1), a radial positioning part (2), a hinge (3), a flexible beam (4), a cutting groove (5) and a sheath (6). The annular radial limiting part (1) is fixedly connected to the bottom of the tubular flexible hinge (3), and the annular radial positioning part (2) is fixedly connected to the top of the hinge (3). The tubular sheath (6) covers the radial limiting part (1), the radial positioning part (2) and the hinge (3), and its top is connected to the radial positioning part (2) to radially position the flexible hinge. There is a gap between the bottom of the sheath (6) and the radial limiting part (1) to form a secondary rotation angle limit; the cutting groove (5) is in the shape of a "son" character, and several groups of cutting grooves (5) penetrate the wall surface of the hinge (2). The outer shapes of adjacent cutting grooves (5) are symmetric along the cross-section of the hinge (3); the groove width of the part of the cutting groove (5) in the same direction as the axis of the hinge (3) and the bent part is larger than the groove width of the part parallel to the cross-section of the hinge (3); the "factory" shaped flexible beam (4) is embedded in the part of the cutting groove (5) with a larger groove width; the groove width of the part parallel to the cross-section of the hinge (3) forms a primary rotation angle limit, the primary rotation angle limit is greater than the maximum rotation angle of the flexible hinge, and the secondary rotation angle limit is greater than the primary rotation angle limit.

2. The flexible hinge for a spatially parallel directional vibration isolation platform according to claim 1, characterized in that: The radial limiting part (1), the radial positioning part (2) and the hinge (3) are made of beryllium bronze or titanium alloy, and the minimum ultimate strength is 1000 MPa.

3. A flexible hinge for a spatial parallel directional vibration isolation platform according to claim 2, characterized in that: The flexible beam (4) is a thin plate structure, and the width of the flexible beam (4) is not less than 2 mm.

4. A flexible hinge for a spatially parallel directional vibration isolation platform according to claim 3, characterized in that: Round corners are provided at the bends of the flexible beam (4) and the cutting groove (5), and the radius of the round corners is not less than 1 mm.

5. A flexible hinge for a spatially parallel directional vibration isolation platform according to claim 4, characterized in that: The cutting groove (5) is processed by the slow wire cutting method, and the surface roughness of the inner end face of the cutting groove (5) is not lower than Ra0.

8.

6. A flexible hinge for a spatially parallel directional vibration isolation platform according to claim 5, characterized in that: The part of the cutting groove (5) parallel to the cross-section of the flexible hinge has a 45° phase difference with the rotation direction of the flexible hinge.

7. A flexible hinge for a spatially parallel directional vibration isolation platform according to claim 6, characterized in that: A satellite payload bracket (8) is fixedly connected to the radial positioning part (2). The output shaft (7) of the actuator is installed on the lower end face of the flexible hinge through the output shaft mounting flange. The inner hole of the output shaft of the actuator is mated with the outer cylindrical surface of the output shaft positioning surface (11) to radially position the output shaft and the flexible hinge. The flexible hinge and the satellite payload bracket (8) are positioned by inserting a cylindrical pin into the positioning pin hole (81).

8. The method for installing a flexible hinge for a spatially parallel directional vibration isolation platform according to claim 7, characterized in that: It includes the following steps: Ⅰ. Install the flexible hinge on the output shaft (7) of the actuator, and then put the sheath (6) on the outside of the flexible hinge. The output shaft (7) of the actuator and the flexible hinge are radially positioned through the output shaft positioning surface (11) and axially connected through the output shaft mounting flange; Ⅱ. The satellite payload bracket (7) abuts against the upper end face of the flexible hinge, and a cylindrical pin is installed in the positioning pin hole (81) to position the flexible hinge and the satellite payload bracket (7); Ⅲ. Strain gauges (8) are arranged in the cutting grooves (4) of the flexible hinge, and the strain gauges (8) are connected to an information acquisition device; Ⅵ. When installing the connecting screws of the satellite load bracket (8) and the flexible hinge, simultaneously observe the strain change shown on the information acquisition device to ensure that the strain value after installation does not exceed the set threshold range; Ⅴ. Remove the strain gauges (9), and finally move the sheath (6) upward along the axis direction of the output shaft (7) of the actuator until it abuts against the satellite payload bracket (8) and is fixedly connected by bolts.

9. The method for installing a flexible hinge for a spatially parallel directional vibration isolation platform according to claim 8, characterized in that: [[ID=

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