A method for molding high aspect ratio anchorless quartz micro-hemispherical harmonic oscillators and its vacuum adsorption fixture

Abstract

A method for molding a high aspect ratio, anchorless quartz micro-hemispherical resonator and its vacuum adsorption fixture are disclosed. This method aims to solve the problem of fabricating micro-hemispherical resonators with small diameter, large depth, and no structural defects using traditional thermoforming techniques. A quartz glass preform is fixed on a vacuum adsorption fixture with an internal vacuum chamber. The fixture is molded into a pre-defined, steeply concave optical surface. The fixture is rotated and the vacuum system is activated, using a flame torch for heating. As the quartz glass softens, its surface tension rheology, combined with the adsorption load provided by the vacuum adsorption force, promotes the uniform flow of material towards the molded surface, thereby forming a high aspect ratio micro-hemispherical preform with uniform wall thickness and no central anchor. The resonator prepared by this invention has significant advantages such as good axisymmetry, high mechanical quality factor, and low internal stress, making it particularly suitable for high-performance inertial navigation and precision sensing fields.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of micro-electro-mechanical system (MEMS) device manufacturing, and particularly relates to a high-aspect-ratio anchor-free column-free quartz micro-hemispherical resonator forming method and a vacuum adsorption tool thereof. BACKGROUND

[0002] Quartz glass, especially fused quartz, has become an ideal material for manufacturing high-precision MEMS gyroscopes (such as hemispherical resonator gyroscopes, HRG) and sensors due to its extremely low thermal expansion coefficient, extremely high mechanical quality factor (Q value), excellent thermal stability and chemical stability.

[0003] With the urgent demand for long-term, autonomous positioning capability of unmanned systems, autonomous navigation and precision instruments, the precision and stability of the core inertial sensor, i.e., the gyroscope, are almost at the limit of requirements. Micro-electro-mechanical system (MEMS) hemispherical resonator gyroscopes (HRG) are considered as a key path to achieve navigation-level precision due to their all-solid-state, high-reliability and long-life advantages. The performance core directly depends on: extremely high geometric symmetry, ultra-smooth surface roughness, uniform material structure and precise size control, in order to approach the theoretical limit of the mechanical quality factor (Q value).

[0004] Existing preparation technologies mostly follow the traditional path of "material removal" or "mold reshaping". The former, such as ultra-precision grinding and polishing, can ensure material purity, but it is inefficient and easily introduces micro-cracks and subsurface damage when processing brittle glass materials with complex curvature at millimeter or even smaller scales, which severely restricts the upper limit of Q value. This technology is limited by processing technology and tool size, cannot avoid tool interference, and is difficult to process high-aspect-ratio and steep sidewall, and is completely unsuitable for the preparation of high-aspect-ratio micro-hemispherical resonators. The latter (such as patent CN 119141834 A "A forming method of umbrella-shaped micro-hemispherical resonator") represents the current mainstream technology route, i.e., relying on a pre-made cavity mold (mostly graphite material) to heat-form softened glass, which will highly copy the microscopic unevenness of the mold surface and introduce impurities, resulting in subsurface damage. This technology is limited by the shape of the mold and the fixed vacuum degree, and there is not enough force to resist the strong surface tension to make the glass flow uniformly to the edge of the mold, i.e., the "umbrella opening" position, so it is not suitable for the preparation of high-aspect-ratio micro-hemispherical resonators with steep edges.

[0005] In summary, the essence of the dilemma of existing technologies lies in their inability to coordinate the relationship between "high-precision forming", "structural integrity" and "energy localization".

[0006] Therefore, there is an urgent need in the art for a new micro-hemisphere resonator preparation method that can fundamentally circumvent the above-mentioned defects, in order to obtain a high-performance resonator with complete structure, excellent performance and suitable for mass production. SUMMARY

[0007] The present application overcomes the deficiencies of the prior art, discards the traditional center column and complex cavity, and innovatively uses a smooth curved surface vacuum adsorption tool without protrusions. By precisely partitioning and dynamically controlling the vacuum degree, the synergistic effect of vacuum adsorption and surface tension is achieved, guiding the softened glass to naturally rheo-form under the dominance of surface tension. This method not only eliminates the anchor column energy loss caused by the center column, realizes the anchor column-free integrated structure, but also significantly improves the wall thickness uniformity and surface finish of the resonator due to the non-mold pressing forming mechanism, thereby achieving breakthroughs in structural integrity and energy localization. The finally prepared high aspect ratio micro-hemisphere resonator has higher mechanical Q value, better axial symmetry and lower inherent noise, providing a key technical foundation for the performance improvement of navigation-level MEMS gyroscopes.

[0008] The technical solution of the present application is as follows:

[0009] A forming method for a high aspect ratio quartz micro-hemisphere resonator includes the following steps:

[0010] 1) providing a quartz glass preform and fixing it on a forming end face of a vacuum adsorption tool, the forming end face being a smooth circular ring plane with step limiting, and the center of the circular ring plane being provided with a high-steepness concave optical curved surface as a forming surface;

[0011] 2) starting the vacuum system to provide an initial vacuum degree P1, applying a first vacuum adsorption force F1 through a vacuum chamber provided inside the vacuum adsorption tool and a micro-hole array opened on the forming surface in communication with the vacuum chamber, and adsorbing and fixing the quartz glass preform on the forming end face;

[0012] 3) rotating the vacuum adsorption tool with the quartz glass preform around the center axis, and heating the quartz glass preform with a flame spray gun until the quartz glass reaches the softening temperature and has rheological properties;

[0013] 4) increasing the vacuum degree provided by the vacuum system to a second vacuum degree P2 higher than the initial vacuum degree P1, to exert a second vacuum adsorption force F2 through the micropore array, while the surface tension Fsur of the softened quartz glass itself is used to form a synergistic effect with the second vacuum adsorption force F2, wherein the direction of the second vacuum adsorption force F2 points to the forming surface, to counteract the inward shrinkage tendency caused by the surface tension Fsur and guide the softened quartz glass material to flow along the profile of the forming surface until complete fitting, thereby forming an integral micro-hemispherical shell preform without a central anchor column;

[0014] 5) stopping heating, keeping the rotating state of the vacuum adsorption tooling and maintaining the second vacuum adsorption force F2, and allowing the micro-hemispherical shell preform to cool and set;

[0015] 6) taking the set micro-hemispherical shell preform off the tooling, performing edge cutting and surface polishing, and obtaining a high aspect ratio quartz glass micro-hemispherical resonator. Preferably, the forming surface of the vacuum adsorption tooling is a high-aspect-ratio concave optical surface with an aspect ratio ≥ 0.5, which is used to guide and replicate the high-precision surface of the resonator.

[0016] Preferably, the high-aspect-ratio concave optical surface has an aspect ratio greater than or equal to 0.5, which is used to form a micro-hemispherical resonator with a corresponding aspect ratio.

[0017] Preferably, the micropore array includes a center region corresponding to the center region of the forming surface and an edge region corresponding to the edge region, wherein the micropore density of the edge region is higher than that of the center region, to achieve zoned enhanced control of the vacuum adsorption force and ensure that the material can be preferentially and sufficiently filled to the steep edge region of the forming surface during the rheological forming process in step S4.

[0018] Preferably, the synergistic effect of the adsorption force F2 and the surface tension Fsur of the softened quartz glass is as follows: the glass is heated to the initial stage of softening and rheology, the surface tension Fsur is activated, driving the material to flow, the edge has a tendency to shrink inward, the vacuum degree is increased to P2, generating a stronger adsorption force F2 to counteract the shrinkage tendency and guide the material to flow to the curved surface of the vacuum adsorption tooling, under the continuous action of the flame, the glass is further softened, uniformly flows and extends to the high-aspect-ratio concave optical surface of the vacuum adsorption tooling under the action of the surface tension Fsur and the vacuum adsorption force F2, and gradually fits on the curved surface, including the most difficult to form edge region.

[0019] Preferably, the relationship between the vacuum suction force F2 and the surface tension Fsur meets the proportional relationship of Ohnesorge_modified (Oh_modified) ≈ F2 / Fsur ≈ 1, indicating that the two forces reach an optimal state of synergy: the vacuum suction force is sufficient to guide and constrain the shape, while the surface tension has sufficient ability to perform surface self-smoothing and uniformization. If the ratio is too large or too small, it will affect the forming quality of the micro-hemisphere resonator. If the ratio is too large, the vacuum suction force will dominate absolutely, and the forming process will be more like "molding", affecting the surface quality; if the ratio is too small, the surface tension will dominate, and the material will strongly tend to form a sphere, rather than being formed into the required hemisphere by suction, resulting in incomplete edge filling or forming failure. By dynamically and zonally controlling the vacuum degree, the balance point of synergy is adjusted in real time to meet the above proportional relationship, so as to realize the precise forming of micro-hemisphere resonators with different geometric characteristics, especially high aspect ratio micro-hemisphere resonators.

[0020] Preferably, the heating position, movement trajectory and heat flux density of the flame spray gun are adjustable to ensure uniform heating of the quartz glass preform and to achieve gradual or synchronous softening from the outer edge to the central area in step S3.

[0021] Preferably, the vacuum suction tool of the forming method comprises:

[0022] The forming end face is a smooth plane with an annular stepped limit;

[0023] The forming surface is a high-steepness concave optical curved surface with an aspect ratio ≥ 0.5, located in the central area of the forming end face;

[0024] The vacuum chamber is built-in in the tool;

[0025] The micro-pore array is composed of a plurality of through micro-pores, one end of which is open to the forming surface, and the other end is connected to the vacuum chamber;

[0026] The vacuum interface is connected with the vacuum chamber for external connection of the vacuum system;

[0027] The distribution density of the micro-pore array on the forming surface is non-uniform, and the micro-pore density of the edge area is greater than that of the central area.

[0028] Preferably, the micro-pore aperture in the micro-pore array is in the range of 1-100 microns, the micro-pore aperture of the edge area is greater than or equal to that of the central area, and the micro-pore distribution density of the edge area is 20%-200% higher than that of the central area.

[0029] Preferably, the surface roughness Ra of the high-steepness concave optical curved surface forming surface is less than 0.01 microns, and the curvature is continuous and has no abrupt change.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. Eliminate anchor loss and obtain an ultra-smooth, low-damage surface:

[0032] In terms of product performance, this method fundamentally eliminates the central anchor inherent in traditional resonators, significantly reducing vibration energy loss and laying the physical foundation for obtaining an ultra-high mechanical quality factor (Q value). Simultaneously, the resonator prepared by this method exhibits excellent wall thickness uniformity and an ultra-smooth surface, ensuring higher structural strength and vibration stability while reducing surface losses.

[0033] 2. Solved the key problem of high aspect ratio micro-hemispherical molding:

[0034] For complex structures with high aspect ratios (≥0.5), this technology solves the problem of manufacturing high-performance resonators using traditional methods. Through a dynamic and zone-controlled vacuum adsorption strategy, precise control of the molding process is achieved. Dynamic vacuum control maintains a specific ratio between vacuum adsorption force and surface tension, ensuring a synergistic effect on product molding. This effectively guarantees high geometric accuracy and axisymmetry, especially in the edge regions, and improves production yield and repeatability. This is also the key to achieving high-precision micro-hemispherical molding. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the manufacturing equipment for the micro-hemispherical resonator in this invention.

[0036] Figure 2 This is a schematic diagram of the vacuum adsorption fixture structure in this invention.

[0037] Figure 2 (a) is a schematic diagram of a vacuum adsorption fixture with a regular curved surface and concave structure. Figure 2 (b) is a schematic diagram of the micropore partitioning of the vacuum adsorption fixture. Figure 2 (c) is a schematic diagram of the high aspect ratio quartz micro-hemispherical harmonic oscillator being formed on a vacuum adsorption fixture.

[0038] Figure 3 To pass Figure 2 A schematic diagram of a harmonic oscillator structure with an aspect ratio of 0.71 prepared by vacuum adsorption tooling.

[0039] The above schematic diagrams are only used to illustrate a method for preparing a high aspect ratio quartz glass micro-hemispherical resonator and a certain scenario in the preparation process, and should not be used to limit the scope of protection of this invention. Detailed Implementation

[0040] The present invention will be further described below with reference to embodiments, but these should not be construed as limiting the scope of the invention.

[0041] Reference Figure 1 The implementation of this invention requires a high-precision glass forming system, as shown in the figure. This manufacturing equipment includes: a vacuum system 1, a combustible gas pipeline system 2 with a precision control device, a rotary clamping mechanism 3 that is interconnected with and sealed to the vacuum system 1, a self-designed vacuum adsorption fixture 4 with a concave structure, and a flame nozzle and its motion adjustment mechanism 5. The rotary clamping mechanism 3 has through holes and a sealing function. One end of it is connected to and interconnected with the self-built vacuum system 1, and the other end is connected to the self-designed vacuum adsorption fixture 4 with a concave structure and through holes, forming a vacuum pipeline. The combustible gas pipeline system 2 with the precision control device is connected to the flame nozzle of the flame nozzle and its motion adjustment mechanism 5, forming a combustible gas supply pipeline.

[0042] Figure 2 Figure (a) shows a schematic diagram of the self-designed vacuum adsorption fixture. As can be seen from the figure, the vacuum adsorption fixture includes a forming end face 41, a steep concave optical surface 42, a vacuum chamber 43 connected to the vacuum system, micropores 44 connecting the steep concave optical surface 42 and the vacuum chamber 43, and... Figure 1 The rotating clamping mechanism is connected to the threaded area 45. Among them, the micro-hole 44 can be a micro-hole array, which includes at least two regions: a center and an edge. The number and density of micro-holes on the edge are greater than those in the center region. The size and position of the micro-holes can be designed and adjusted according to actual needs. The size and aspect ratio of the high-steep concave optical surface 42 can be freely designed and adjusted according to needs. Figure 2 (b) is a schematic diagram of the micropore 44 partitioning of the vacuum adsorption fixture: the micropore area 441 is distributed in an array in the central region and the micropore area 442 is distributed in an array uniformly in the edge region. Figure 2 (c) is a schematic diagram of the high aspect ratio quartz micro-hemispherical resonator forming process in a vacuum adsorption fixture: including vacuum adsorption fixture 4 and high aspect ratio micro-hemispherical resonator structure 6.

[0043] Figure 3 This is a schematic diagram of the high aspect ratio quartz glass micro-hemispherical resonator prepared by the present invention. As shown in the figure, the micro-hemispherical resonator prepared by the high aspect ratio anchorless quartz micro-hemispherical resonator forming method and vacuum adsorption tooling of the present invention includes a substrate portion 61 and a resonator main body structure 62.

[0044] Example

[0045] S1. Provide a quartz glass preform with a diameter of Φ29mm and a thickness of 0.5mm, and place it on the forming end face of the vacuum adsorption fixture;

[0046] S2. Start the vacuum system to provide a first vacuum adsorption force to generate a negative pressure in the vacuum chamber, so as to exert an adsorption force on the quartz glass preform through the micropore array, so that the quartz glass preform is fixed on the forming end face;

[0047] S3. Drive the quartz glass preform to rotate by the vacuum adsorption tooling, and at the same time, heat the quartz glass preform by using a flame spray gun until it is softened;

[0048] S4. Adjust the vacuum pumping speed, and provide a second adsorption force by the micropore density of the vacuum adsorption tooling, so as to make the quartz glass preform flow and completely fit the profile of the high-steepness inner-concave optical curved surface by the synergistic effect of the adsorption force and the surface tension of the softened quartz glass. During the forming process, the edge region preferentially flows to the vacuum chamber due to the large micropore density of the tooling, and the flow and fitting of the central region are slightly delayed, so as to avoid the phenomenon of low thickness at the top of the micro-hemisphere in the traditional hot forming process, and form an integrated high-aspect-ratio micro-hemisphere preform with higher wall thickness uniformity and without a central anchor column;

[0049] S5. Stop heating and cool the shaped body under the conditions of keeping rotation and adsorption;

[0050] S6. Take out the micro-hemisphere shell preform, cut the edge of the micro-hemisphere shell preform using a picosecond laser, and obtain a high-aspect-ratio quartz glass micro-hemisphere resonator, the structure of which is shown in Figure 3 , and the measured aspect ratio is 6.85 / 9.6=0.71.

[0051] The lip edge of the micro-hemisphere resonator is welded and fixed to the test device by laser welding, and the Q value and wall thickness deviation of the resonator are tested. The initial Q value of the resonator without fine grinding modification reaches 105190.

[0052] The embodiment adopts a synergistic mechanism of dynamic partition vacuum adsorption force and surface tension of softened glass, replaces the traditional mold pressing method, and realizes the precise rheological forming of an anchor column-free integrated high-aspect-ratio quartz micro-hemisphere resonator. This method fundamentally solves the technical problems of traditional processes that are difficult to balance high-aspect-ratio structure forming, wall thickness uniformity and ultra-low energy loss.

[0053] The specific embodiments of the application are described above. It should be understood that the application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the application. The above embodiments and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for molding a high aspect ratio, anchorless quartz micro-hemispherical resonator, characterized in that, The method comprises the following steps: 1) providing a quartz glass preform and fixing it on a forming end face of a vacuum suction tooling, the forming end face being a smooth circular plane with a step limit, and the circular plane is provided with a high-steepness inner concave optical curved surface as a forming surface; 2) starting a vacuum system to provide an initial vacuum degree P1, applying a first vacuum suction force F1 through a vacuum chamber arranged inside the vacuum suction tooling and a micropore array (44) opened on the forming surface and communicated with the vacuum chamber, and fixing the quartz glass preform on the forming end face; 3) rotating the quartz glass preform around a central axis of the vacuum suction tooling while heating the quartz glass preform by using a flame spray gun until the quartz glass reaches a softening temperature and has rheological properties; 4) increasing the vacuum degree provided by the vacuum system to a second vacuum degree P2 higher than the initial vacuum degree P1 to apply a second vacuum suction force F2 through the micropore array (44), and meanwhile, utilizing the surface tension Fsur of the softened quartz glass itself to form a synergistic effect of the second vacuum suction force F2 and the surface tension Fsur, wherein the second vacuum suction force F2 is directed to the forming surface to resist the inward shrinkage trend of the material caused by the surface tension Fsur and guide the softened quartz glass material to flow along the profile of the forming surface until complete fitting, thereby forming an integrated micro-hemisphere spherical shell preform without a central anchor column; 5) stopping heating, keeping the rotating state of the vacuum suction tooling and maintaining the second vacuum suction force F2 to cool and shape the micro-hemisphere spherical shell preform; 6) taking the shaped micro-hemisphere spherical shell preform from the tooling, performing edge cutting and surface polishing to obtain a high aspect ratio quartz glass micro-hemisphere resonator.

2. The high aspect ratio anchorless post quartz microhemispherical resonator forming method of claim 1, wherein, The high-steepness inner concave optical curved surface has an aspect ratio greater than or equal to 0.5 for forming a micro-hemisphere resonator with a corresponding aspect ratio.

3. The high aspect ratio anchorless pillar quartz microhemispherical resonator forming method of claim 1, wherein, The micropore array (44) comprises a central zone (441) corresponding to the central region of the forming surface and an edge zone (442) corresponding to the edge region, wherein the micropore density of the edge zone (442) is higher than that of the central zone (441) to realize zoned enhanced control of the vacuum suction force and ensure that the material can be preferentially and sufficiently filled to the steep edge region of the forming surface (42) in the rheological forming process of step S4.

4. The high aspect ratio anchorless pillar quartz microhemispherical resonator forming method of claim 1, wherein, The synergistic effect of the suction force F2 and the surface tension Fsur of the softened quartz glass is as follows: the glass is heated to the initial stage of softening and rheological properties, the surface tension Fsur is activated to start driving the material flow, the edge has a tendency to shrink inward, the vacuum degree is increased to P2 to generate a stronger suction force F2 to resist the shrinkage trend and guide the material to flow to the vacuum suction tooling curved surface, under the continuous action of the flame, the glass is further softened, and under the action of the surface tension Fsur and the vacuum suction force F2, the glass uniformly flows and extends to the high-steepness inner concave optical curved surface of the suction tooling and gradually fits on the curved surface, including the most difficult to form edge region.

5. The high aspect ratio anchorless pillar quartz microhemispherical resonator forming method according to claim 1 or 2, characterized in that, The relationship between the vacuum suction force F2 and the surface tension Fsur is in accordance with the Ohnesorge number Ohnesorge_modified=F2 / Fsur=1.

6. The high aspect ratio anchorless post quartz microhemispherical resonator forming method of claim 1, wherein, The heating position, moving track and heat flux density of the flame spray gun can be adjusted to ensure uniform heating of the quartz glass preform and to achieve progressive or synchronous softening from the outer edge to the central region in step S3.

7. A vacuum suction tooling for carrying out the forming method according to any one of claims 1-6, characterized in that, It comprises: a shaped end face (41) which is a smooth plane with an annular stepped limit; a shaped face (42) which is a high-steepness concave optical curved surface with a depth-width ratio ≥0.5 located in the central region of the shaped end face (41); a vacuum chamber (43) built in the tooling; a micropore array (44) composed of a plurality of through micropores, one end of which is open to the shaped face (42) and the other end of which is connected to the vacuum chamber (43); a vacuum interface (45) connected with the vacuum chamber (43) for external connection of a vacuum system; wherein the distribution density of the micropore array (44) on the shaped face (42) is non-uniform, and the micropore density corresponding to the edge region of the shaped face is greater than that of the central region.

8. The vacuum chucking tool according to claim 7, wherein The micropore aperture in the micropore array (44) is in the range of 1-100 microns, the micropore aperture of the edge region (442) is greater than or equal to that of the central region (441), and the micropore distribution density of the edge region (442) is 20%-200% higher than that of the central region (441).

9. The vacuum chucking tool according to claim 7, wherein The surface roughness Ra of the high-steepness concave optical curved surface shaped face (42) is less than 0.01 microns, and the curvature is continuous and has no abrupt change.

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