High and low temperature working condition stress unloading mechanism

Abstract

According to the stress unloading mechanism under the high and low temperature working conditions, a single-point fixed connection structure and a stress unloading fixing structure arranged on the single-point fixed connection structure in a sleeving mode are arranged, the single-point fixed connection structure sequentially penetrates through a lower fixing unit, a connecting part of an off-axis case and an upper fixing unit, and the tail end of the single-point fixed connection structure is connected with a beam combining case in a fastened mode; the upper matching surface and the lower matching surface of the stress unloading fixing structure and the off-axis case connecting part are in rolling contact, and when the temperature changes, sliding friction between the two matching surfaces can be changed into rolling friction, so that the friction force of the matching surfaces is greatly reduced, the stress unloading fixing structure can relatively move along the matching surfaces when the temperature changes, internal stress is reduced, and the service life of the off-axis case is prolonged. Meanwhile, structural deformation is reduced, and equipment optical axis stability is guaranteed.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical machinery, and particularly relates to a stress unloading mechanism under high and low temperature working conditions. Background Art

[0002] Invar is a steel with a small thermal expansion coefficient (about 1.5×10 -6 / ℃) of metal alloy material. Since its thermal expansion coefficient is close to that of most optical materials, Invar is often used in certain optical systems to improve the accuracy of the optical system under different temperature conditions. Among them, as a typical representative, off-axis optical system generally chooses Invar as the structural material to adapt to the high and low temperature working conditions of the equipment and ensure the relative position accuracy of its primary and secondary mirrors.

[0003] However, due to its high density (about 8.1×10 3 kg / m 3 ), it will not be widely used in some optical systems that have requirements on weight, and aluminum alloys or other materials with lower density will be chosen.

[0004] Therefore, in many optical systems, there is a phenomenon that Invar coexists with aluminum alloy or other materials. The thermal expansion coefficient of general metal materials, such as aluminum alloy, is relatively large (about 23×10 -6 / ℃). Two metals with different thermal expansion coefficients expand or contract to different degrees when the temperature changes. When they are fastened together and the mounting surfaces cannot move, thermal stress will be generated, causing the equipment to bend. This will have a significant impact on the stability of the optical axis of the optical system.

[0005] In the design of an optical system, it is necessary to assemble a beam combining chassis whose main material is aluminum alloy and an off-axis chassis whose main material is invar. The assembly effect diagram of the two is shown in the figure below. Figure 1 shown.

[0006] After assembling the two, it was found that the optical axis of the equipment changed significantly when working at high and low temperatures. In order to calculate the impact of temperature on the equipment, the design model was subjected to thermal-mechanical multi-field coupling analysis using Ansys Workbench finite element analysis software. Combining the analysis of stress cloud map and deformation cloud map, it was found that after the two chassis were assembled, due to the different thermal expansion coefficients, large thermal stress was generated, which caused the chassis to deform significantly, thus causing the optical axis to change.

[0007] Therefore, it is necessary to develop a stress unloading mechanism to assemble two chassis made of different materials together, so as to generate relatively small thermal stress when the temperature changes, thereby ensuring the stability of the optical axis of the equipment. Summary of the invention

[0008] The utility model aims to provide a stress unloading mechanism for high and low temperature working conditions in view of the deficiencies of the above-mentioned prior art, so as to ensure that smaller thermal stress is generated when the temperature changes, and to ensure the stability of the optical axis of the equipment.

[0009] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0010] A high and low temperature working condition stress unloading mechanism, comprising a single point fixed connection structure and a stress unloading fixing structure sleeved on the single point fixed connection structure, wherein the stress unloading fixing structure comprises an upper fixing unit and a lower fixing unit symmetrically arranged in pairs;

[0011] The single-point fixed connection structure passes through the lower fixing unit, the connection part of the off-axis chassis, and the upper fixing unit in sequence, and its end is tightly connected to the beam combining chassis;

[0012] The upper and lower mating surfaces of the stress unloading fixed structure and the off-axis chassis connection portion are both in rolling contact.

[0013] The upper and lower fixing units both include a ball retainer and balls installed in the ball retainer, and the balls are in contact with the connecting portion of the off-axis chassis.

[0014] The connection part of the off-axis chassis adopts mounting lugs, and the mounting lugs are fixedly arranged around the off-axis chassis accordingly.

[0015] The stress unloading fixed structures are distributed correspondingly around the off-axis chassis, and are all equipped with single-point fixed connection structures in a one-to-one correspondence.

[0016] The single-point fixed connection structure is a mounting screw, and a thread is provided at the end thereof and is threadably matched with a threaded hole provided on the off-axis chassis connecting portion.

[0017] The mounting lug is provided with a mounting hole for mounting the single-point fixed connection structure, and the mounting single-point fixed connection structure is clearance-matched with the mounting hole.

[0018] The gap between the installation single-point fixed connection structure and the installation hole is 1-2 mm.

[0019] The beneficial effects of the utility model are:

[0020] (1) The stress unloading mechanism for high and low temperature working conditions is provided with a single-point fixed connection structure and a stress unloading fixed structure sleeved on the single-point fixed connection structure. The single-point fixed connection structure passes through the lower fixed unit, the connection part of the off-axis chassis, and the upper fixed unit in sequence, and its end is tightly connected to the beam combining chassis; and the upper and lower mating surfaces of the stress unloading fixed structure and the connection part of the off-axis chassis are both in rolling contact. When the temperature changes, the sliding friction between the two mating surfaces can be changed into rolling friction, thereby greatly reducing the friction force of the mating surfaces, so that the relative movement can occur along the mating surfaces when the temperature changes, reducing the generation of internal stress, while reducing structural deformation, and ensuring the stability of the optical axis of the equipment.

[0021] (2) The structure is compact, occupies little space, has a significant stress unloading effect, and can significantly improve the stability of the optical axis.

[0022] (3) For structures that have not considered stress unloading in advance and have taken remedial measures, the present invention does not require major changes to the original structure and has a high promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the utility model;

[0024] Figure 2 yes Figure 1 A partial enlarged schematic diagram of

[0025] Figure 3 It is an assembly cross-sectional view of the single-point fixed connection structure and the stress unloading fixed structure;

[0026] Figure 4 It is a cross-sectional view of the stress unloading fixed structure. DETAILED DESCRIPTION

[0027] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0028] See also Figure 1. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should fall within the scope of the technical content disclosed by the utility model without affecting the effects and purposes that can be achieved by the utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the utility model without substantial changes in the technical content.

[0029] The utility model provides a stress unloading mechanism for high and low temperature working conditions, such as Figures 1 to 4 shown.

[0030] A stress unloading mechanism for high and low temperature working conditions comprises a single-point fixed connection structure 1 and a stress unloading fixed structure sleeved on the single-point fixed connection structure 1, and the stress unloading fixed structure comprises an upper fixed unit 6 and a lower fixed unit 7 symmetrically arranged in pairs; the single-point fixed connection structure 1 passes through the lower fixed unit 7, the connecting portion 41 of the off-axis chassis 4, and the upper fixed unit 6 in sequence, and its end is tightly connected to the beam combining chassis 5; and the upper and lower mating surfaces of the stress unloading fixed structure and the connecting portion of the off-axis chassis 4 are both in rolling contact.

[0031] The upper and lower fixing units each include a ball cage 3 and a ball 2 mounted in the ball cage 3, and the ball 2 is in contact with the connection portion 41 of the off-axis chassis 4. The connection portion 41 of the off-axis chassis 4 adopts a mounting lug, and the mounting lug is fixedly arranged around the off-axis chassis 4. The mounting lug is provided with a mounting hole for mounting a single-point fixed connection structure, and the single-point fixed connection structure is installed with a clearance fit between the mounting hole; preferably, the clearance between the single-point fixed connection structure and the mounting hole is 1-2 mm.

[0032] The stress unloading fixed structure is correspondingly distributed around the off-axis chassis, and is evenly equipped with a single-point fixed connection structure. In this embodiment, the single-point fixed connection structure is a mounting screw, and its end is provided with a thread and is threaded with the threaded hole opened on the off-axis chassis connection part, and the ball retainer and the mounting screw and the threaded hole on the beam-combining chassis remain relatively stationary; in this embodiment, the single-point fixed connection structure is fixed with 4 M8 screws, and the fixing screws are evenly distributed on a circle with a diameter of 100mm. The stress unloading fixed structure is correspondingly distributed at four positions at the four corners of the chassis; each stress unloading fixed structure is composed of two ball retainers 3 and a number of balls 2, and 16 balls with a diameter of 2mm are installed in each ball retainer.

[0033] The single-point fixed connection structure is used for the fastening connection between the beam combining chassis 5 and the off-axis chassis 4. It is fixed at the center position of the mating surfaces around the two and is fastened only in a small local area to ensure that there is no relative displacement between the two in the front and back, left and right, and up and down directions, and no relative rotation in the azimuth direction.

[0034] The stress unloading fixed structure is the core of the stress unloading mechanism under high and low temperature conditions. It is used for auxiliary connection between the beam combining chassis and the off-axis chassis and is fixed at the four corners of the mating surfaces of the two. The stress unloading fixed structure only limits the displacement between the beam combining chassis 5 and the off-axis chassis 4 in the up and down directions and the rotation in the pitch and roll directions, but does not limit the displacement in the front and back, left and right directions and the rotation in the azimuth direction.

[0035] When the temperature changes, due to the different thermal expansion coefficients, the chassis of the two materials tend to move relative to each other on the mating surfaces; after installing a fixing unit between their mating surfaces, the sliding friction between the two mating surfaces can be changed to rolling friction, thereby greatly reducing the friction force of the mating surfaces, allowing them to move relative to each other along the mating surfaces when the temperature changes, reducing the generation of internal stress, while reducing structural deformation and ensuring the stability of the equipment's optical axis.

[0036] In this embodiment, the upper and lower fixing units of the stress unloading fixing structure both include balls 2 and ball retainers 3; the function of the balls is to change the sliding friction at the mating point into rolling friction, remove the displacement constraint in the horizontal direction at the mounting lugs, and reduce the thermal stress generated on the mating surface when the temperature changes, while the ball retainer limits the free movement range of the balls to prevent the balls from falling off.

[0037] The ball cages are used in pairs. The balls installed in the ball cages are in contact with the two end faces of the mounting lugs on the off-axis chassis. The ball cages, screws and threaded holes on the beam-combining chassis remain relatively still. The mounting lugs of the off-axis chassis can move relative to the mounting surface of the beam-combining chassis in the horizontal direction to unload the stress caused by temperature changes. The maximum displacement between the mounting lugs of the off-axis chassis and the mounting surface of the beam-combining chassis is determined by the gap between the mounting lug mounting holes and the mounting screws; in this example, the mounting lug mounting hole diameter is 10 mm, the mounting screw diameter is 8 mm, and the single-side distance between the mounting screw and the mounting hole is reduced to 1 mm. Therefore, the maximum displacement of the two chassis at the lug is 1 mm.

[0038] In addition, a thermal-mechanical coupling analysis was performed on the equipment using the stress unloading mechanism. The analysis results are as follows:

[0039] After adopting the stress unloading mechanism, the thermal stress generated by the equipment under high and low temperature conditions is greatly reduced, and is concentrated near the single-point fixed structure in the middle, which has little effect on the deformation of the whole machine; although the other structures also deformed, they almost moved horizontally without obvious bending deformation, which had little effect on the optical axis, and the maximum value of the horizontal displacement of the structure did not exceed 0.67mm. The designed 1mm clearance is sufficient to ensure the normal operation of the stress unloading mechanism.

[0040] It can be seen from the above that, through the high and low temperature working condition stress unloading mechanism, the thermal stress generated by assembling two chassis of different materials together can be reduced when the temperature changes, thereby ensuring the stability of the optical axis of the equipment.

[0041] If the words "first", "second" and so on are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the utility model and simplifying the description, and the above words have no special meaning.

[0042] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. The utility model may have various changes and improvements without departing from the spirit and scope of the utility model. These changes and improvements fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

[0043] In the description of the present invention, it is necessary to understand that the terms "front", "rear", "left", "right", "center", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the protection content of the present invention.

Claims

1. A stress unloading mechanism for high and low temperature working conditions, characterized in that: It includes a single-point fixed connection structure and a stress unloading fixed structure sleeved on the single-point fixed connection structure, and the stress unloading fixed structure includes an upper fixed unit and a lower fixed unit symmetrically arranged in pairs; The single-point fixed connection structure passes through the lower fixing unit, the connection part of the off-axis chassis, and the upper fixing unit in sequence, and its end is tightly connected to the beam combining chassis; The upper and lower mating surfaces of the stress unloading fixed structure and the off-axis chassis connection portion are both in rolling contact.

2. A high and low temperature working condition stress unloading mechanism according to claim 1, characterized in that: The upper and lower fixing units both include a ball retainer and balls installed in the ball retainer, and the balls are in contact with the connecting portion of the off-axis chassis.

3. A high and low temperature working condition stress unloading mechanism according to claim 1, characterized in that: The connection part of the off-axis chassis adopts mounting lugs, and the mounting lugs are fixedly arranged around the off-axis chassis accordingly.

4. A high and low temperature working condition stress unloading mechanism according to claim 3, characterized in that: The stress unloading fixed structures are distributed correspondingly around the off-axis chassis, and are all equipped with single-point fixed connection structures in a one-to-one correspondence.

5. A high and low temperature working condition stress unloading mechanism according to claim 1, characterized in that: The single-point fixed connection structure is a mounting screw, and a thread is provided at the end thereof and is threadably matched with a threaded hole provided on the off-axis chassis connecting portion.

6. A high and low temperature working condition stress unloading mechanism according to claim 3, characterized in that: The mounting lug is provided with a mounting hole for mounting the single-point fixed connection structure, and the mounting single-point fixed connection structure is clearance-matched with the mounting hole.

7. A high and low temperature working condition stress unloading mechanism according to claim 6, characterized in that: The gap between the installation single-point fixed connection structure and the installation hole is 1-2 mm.

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