Micro-hemispherical resonator thermoforming mold and method based on full mold constraint

Abstract

The present invention discloses a mold and method for thermoforming a micro-hemispherical resonator based on full mold constraint. The mold comprises a main body and a forming ball. The main body has a cavity recessed downward from its top surface, the cavity having a plurality of air holes communicating with the exterior of the main body, and the bottom of the cavity has positioning holes. The forming ball is placed in the cavity through the positioning holes. The shape parameters of the forming ball match the shape parameters of the inner cavity of the micro-hemispherical resonator. The method for thermoforming a micro-hemispherical resonator employs the above-mentioned mold to form the micro-hemispherical resonator. Compared with the prior art, the present invention utilizes a precisely machined forming ball to constrain the shape of the micro-hemispherical resonator during the forming process, thereby further improving the structural symmetry of the micro-hemispherical resonator and enabling control of the shape parameters of the micro-hemispherical resonator.

Description

Technical Field

[0001] The present invention relates to the technical field of vibrating gyroscopes, and in particular to a micro-hemispherical resonator thermoforming mold and method based on full mold constraint. Background Art

[0002] A hemispherical resonator gyroscope (HRG) is an inertial sensor that measures angular rate or attitude angle. It boasts outstanding advantages such as simple structure, high precision, long life, and high reliability. It is widely used in a variety of high-end applications such as deep space exploration, satellite attitude measurement, and ship navigation. Micro-hemispherical resonator gyroscopes (MRGs), manufactured using MEMS technology, offer the unique advantages of low cost, small size, and high precision, making them a current research hotspot in inertial devices. The micro-hemispherical resonator is the core component of a MRG, and its performance determines the gyroscope's ultimate performance. To ensure the high performance of a HRG, the resonator must possess characteristics such as a high quality factor and low frequency splitting. These characteristics are significantly affected by the shape symmetry of the MRG. Therefore, manufacturing a MRG with improved structural symmetry is key to developing high-precision MRGs.

[0003] In the prior art, there are two mainstream solutions for manufacturing micro-hemispherical resonators: (1) Figure 5 As shown in [1], the University of California, Irvine, USA, uses a free expansion method to complete the processing of micro-hemispherical resonators. Specifically, a cavity is first etched into the substrate glass and bonded to another glass sheet used to form the micro-hemispherical resonator to form a closed chamber with a certain air pressure. The glass is then heated to a high temperature to soften the glass and reduce the external air pressure. Under the action of the air pressure in the closed chamber, the glass expands freely to form a fully symmetrical wine glass-shaped micro-hemispherical resonator; (2) Figure 6 As shown, the University of Michigan uses a half-mold constraint method to complete the processing of micro-hemispherical resonators. Specifically, a piece of glass is placed on a cylindrical mold, heated to a high temperature to soften the glass, and the pressure difference between the upper and lower surfaces of the glass is controlled to allow the glass to expand downward freely. The mold serves to constrain the anchor points and edges of the micro-hemispherical resonator, but cannot constrain the shape of the formed micro-hemispherical resonator.

[0004] Both of these mainstream solutions are based on free expansion molding to complete the processing of micro-hemispherical resonators. The structural symmetry of the molding is greatly affected by the uniformity of the temperature field, and it is difficult to achieve high yield and high structural symmetry at the same time. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies in the above-mentioned prior art and to provide a micro-hemispherical resonator thermoforming mold and method based on full mold constraint. The mold and method use precision-machined forming balls to constrain the shape of the micro-hemispherical resonator during the forming process, thereby further improving the structural symmetry of the micro-hemispherical resonator forming and realizing the control of the shape parameters of the micro-hemispherical resonator.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a micro-hemispherical resonator thermoforming mold based on full mold constraint, comprising:

[0008] A main body, wherein the main body has a cavity recessed downward from the top surface thereof, the cavity has a plurality of air holes communicating with the outside of the main body, and the bottom of the cavity has a positioning hole;

[0009] A molded ball is placed in the mold cavity through the positioning hole, and the shape parameters of the molded ball match the shape parameters of the inner cavity of the micro-hemispherical resonator.

[0010] Preferably, the top surface of the main body has a fixing portion, and the fixing portion is used to fix the bonding sheet.

[0011] Preferably, the fixing portion is four raised portions arranged on the edges of the top surface of the main body, and the four raised portions are symmetrically spaced in pairs.

[0012] Preferably, a top cover is further included, and the top cover is used to press and fix the bonding sheet placed on the top surface of the main body.

[0013] Preferably, a plurality of the air holes are evenly arranged around the positioning hole and are located close to the formed ball.

[0014] Preferably, the positioning hole is in the shape of an inverted truncated cone.

[0015] Preferably, the top of the molded ball is flush with the top surface of the main body.

[0016] In a second aspect, the present invention provides a method for thermoforming a micro-hemispherical resonator based on full mold constraint, wherein the micro-hemispherical resonator is formed using the thermoforming mold for the micro-hemispherical resonator based on full mold constraint as described in the first aspect above, comprising the following steps:

[0017] A substrate of corresponding size is selected according to the size of the micro-hemispherical resonator and a cavity is processed on the substrate, wherein the substrate is made of a high-temperature resistant material;

[0018] Bonding a substrate for molding to the base to form a bonding sheet, wherein the substrate cooperates with the cavity to form a closed cavity with air pressure;

[0019] forming a demoulding layer on the substrate to facilitate demoulding after molding;

[0020] placing a molding ball in the mold cavity and mounting the bonding sheet on the top surface of the main body with the substrate facing the molding ball;

[0021] placing the main body with the formed balls and the bonding sheet installed in a thermoforming furnace and heating it to the thermoforming temperature of the substrate to soften the substrate;

[0022] The thermoforming furnace is evacuated at the thermoforming temperature of the substrate to reduce the pressure difference between the inside and outside of the closed cavity, and the substrate is gradually adhered to the outer surface of the forming ball under the action of the pressure difference between the inside and outside of the closed cavity to form a micro-hemispherical resonator;

[0023] After the forming is completed, the substrate is kept in the thermoforming furnace at the thermoforming temperature for a period of time to allow the substrate to be fully formed;

[0024] After the temperature of the thermoforming furnace drops to room temperature, the main body is taken out of the thermoforming furnace and the bonding sheet with the micro-hemispherical resonator formed thereon is demoulded and removed from the main body;

[0025] Excess materials around the edges of the micro-hemispherical resonator are removed to separate the micro-hemispherical resonator from the bonding sheet to obtain a final product.

[0026] Preferably, the cavity on the substrate is processed by dry etching.

[0027] Preferably, the substrate is made of fused quartz.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention constrains the shape of the micro-hemispherical resonator during the molding process by using a precisely machined molding ball. The molding substrate is fully fitted with the molding ball during the molding process, which can further improve the structural symmetry of the micro-hemispherical resonator and contribute to the production of a higher-precision micro-hemispherical resonator gyroscope. It has broad application prospects in the field of inertial navigation.

[0030] (2) The present invention can control the shape parameters of the micro-hemispherical resonator by controlling the shape parameters of the formed sphere;

[0031] (3) Due to the fixed constraints, the present invention can further improve the yield rate in the actual production of micro-hemispherical resonators and has the advantages of simple process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. It should be noted that in all the drawings, the various elements or parts are not necessarily drawn according to the actual scale.

[0033] Figure 1 This is a cross-sectional view of the overall structure of a thermoforming mold for a micro-hemispherical resonator based on full mold constraint according to an embodiment of the present invention;

[0034] Figure 2 This is a cross-sectional view of the overall structure of the main body of the thermoforming mold for a micro-hemispherical resonator based on full mold constraint according to an embodiment of the present invention;

[0035] Figure 3 This is a top view of the overall structure of the main body of the micro-hemispherical resonator thermoforming mold based on full mold constraint according to an embodiment of the present invention;

[0036] Figure 4 Schematic diagram of the molding process of the micro-hemispherical resonator thermoforming method based on full mold constraint according to an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of a process for forming a micro-hemispherical resonator in the prior art;

[0038] Figure 6 This is a schematic diagram of another process of forming a micro-hemispherical resonator in the prior art.

[0039] In the picture:

[0040] 1. Main body; 11. Cavity; 12. Air hole; 13. Positioning hole; 14. Fixing part; 2. Molding ball; 3. Top cover; 4. Base; 41. Cavity; 5. Substrate. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the systems or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing those components. Unless otherwise stated, these terms have no special meanings and should not be construed as indicating or implying relative importance.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0044] A micro-hemispherical resonator is a core component of a micro-hemispherical resonator gyroscope, and its performance determines the ultimate performance of the gyroscope. To ensure that the hemispherical resonator gyroscope has high performance, the resonator should have characteristics such as a high quality factor and low frequency splitting, and these characteristics are significantly affected by the shape symmetry of the micro-hemispherical resonator. However, in the prior art, the molding of micro-hemispherical resonators is generally completed based on free expansion molding. The structural symmetry of the molding is significantly affected by the uniformity of the temperature field, making it difficult to achieve both high yield and high structural symmetry. Therefore, the present invention provides a micro-hemispherical resonator hot forming mold and method based on full mold constraint. The mold uses a precision-machined molding ball to constrain the shape of the micro-hemispherical resonator during the molding process, which can further improve the structural symmetry of the micro-hemispherical resonator molding and achieve control over the shape parameters of the micro-hemispherical resonator.

[0045] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0046] Example 1

[0047] like Figure 1-Figure 3 As shown, an embodiment of the present invention provides a micro-hemispherical resonator thermoforming mold based on full mold constraint, comprising:

[0048] The main body 1 has a cavity 11 that is recessed downward from its top surface. The cavity 11 has a plurality of air holes 12 that communicate with the outside of the main body 1. The bottom of the cavity 11 has a positioning hole 13.

[0049] The molded ball 2 is placed in the mold cavity 11 through the positioning hole 13. The molded ball 2 is formed by precision machining according to the shape parameters of the inner cavity of the micro-hemispherical resonator, and its shape parameters match the shape parameters of the inner cavity of the micro-hemispherical resonator.

[0050] In the embodiment of the present invention, a molding ball 2 having shape parameters that match the shape parameters of the inner cavity of the micro-hemispherical oscillator is disposed within the molding cavity 11 on the main body 1. During molding, a bonding sheet with a sealed cavity can be placed on the top surface of the main body 1. Then, the substrate 5 is softened by heating and the pressure difference between the inside and outside of the sealed cavity is changed by vacuuming, so that the softened substrate 5 gradually adheres to the molding surface to complete the molding. During the molding process of the substrate 5, the molding ball 2 fully constrains the shape parameters of the micro-hemispherical oscillator, which can further improve the structural symmetry of the micro-hemispherical oscillator molding, thereby further improving the high yield rate of the micro-hemispherical oscillator molding. At the same time, the embodiment of the present invention can also control the shape parameters of the micro-hemispherical oscillator by controlling the shape parameters of the molding ball 2.

[0051] Furthermore, the top surface of the main body 1 has a fixing portion 14. The fixing portion 14 can fix the bonding sheet during the molding process to prevent the bonding sheet from moving due to changes in air pressure, etc., which can further improve the yield rate of the micro-hemispherical resonator molding of this embodiment.

[0052] Preferably, the fixing portion 14 is four raised portions arranged on the edges of the top surface of the main body 1 , and the four raised portions are symmetrically spaced in pairs on the top surface of the main body 1 to form a bonding sheet placement area.

[0053] It is understood that the fixing portion 14 is not limited to the above-described structural form. In other embodiments of the present invention, other structural forms of positioning portions may be provided. For example, in some specific embodiments, a full circle of protrusions may be provided along the four edges of the top surface of the main body 1 as the fixing portion 14.

[0054] In some optional embodiments, in order to improve compatibility with bonding sheets of different sizes, several position-adjustable fixing members can be provided on the top surface of the main body 1 as fixing parts 14. When in use, the positions of the fixing members can be adjusted according to bonding sheets of different sizes to fix the bonding sheets.

[0055] Furthermore, a top cover 3 is included, which is used to press and secure the bonding sheet placed on the top surface of the main body 1. The top cover 3 can prevent the bonding sheet from moving up and down due to changes in the air pressure inside and outside the cavity 11 during the vacuuming process, thereby preventing the molding of the micro-hemispherical resonator from being affected by the movement of the bonding sheet.

[0056] Furthermore, a plurality of air holes 12 are evenly arranged along the circumference of the positioning hole 13 and are located adjacent to the formed ball 2 .

[0057] In this embodiment, a plurality of air holes 12 are evenly arranged at the bottom of the cavity 11 along the circumference of the positioning hole 13, so that the air pressure in the cavity 11 is evenly reduced along the surface of the molding ball 2 during the vacuuming process. This enables the substrate 5 to better fit the surface of the molding ball 2 during the molding process. The position of the air holes 12 close to the molding ball 2 helps to form a complete hemispherical resonator on the substrate 5, further improving the yield of this embodiment.

[0058] Preferably, the positioning hole 13 is in the shape of an inverted truncated cone. The inverted truncated cone-shaped positioning hole 13 can adapt to the positioning of the formed balls 2 of different diameters within a certain range, which can further enhance the flexibility of this embodiment.

[0059] Preferably, the top of the molded ball 2 is flush with the top surface of the main body 1. Through the above configuration, the substrate 5 of this embodiment abuts against the molded ball 2 at the beginning of molding, which can further enhance the constraining effect of the molded ball 2 on the substrate 5 and ensure that the substrate 5 gradually adheres to the surface of the molded ball 2 along both sides of the abutment with the molded ball 2 during molding, thereby further enhancing the structural symmetry of the micro-hemispherical resonator molded in this embodiment.

[0060] Example 2

[0061] This embodiment provides a method for thermoforming a micro-hemispherical resonator based on full mold constraint, based on the micro-hemispherical resonator thermoforming mold based on full mold constraint provided in the first embodiment, including the following steps:

[0062] S100 selects a substrate 4 of corresponding size according to the size of the micro-hemispherical resonator and processes a cavity 41 on the substrate 4, the substrate 4 being made of a high-temperature resistant material such as a silicon carbide sheet;

[0063] S200. The substrate 5 for forming the bonding is bonded to the base 4 to form a bonding sheet, and the substrate 5 cooperates with the cavity 41 to form a closed cavity having air pressure;

[0064] S300 is formed by coating a release layer on the substrate 5 to facilitate demolding after molding, the release layer material can be selected such as chromium, gold and other materials;

[0065] S400. The molded ball 2 is placed in the mold cavity 11, and the bonding sheet is mounted on the top surface of the main body 1 so that the substrate 5 faces the molded ball 2;

[0066] S500. The main body 1 of the molded ball 2 and the bonding sheet is installed and placed in a thermoforming furnace and heated to the thermoforming temperature of the substrate 5 to soften the substrate 5;

[0067] S600. The thermoforming furnace is vacuumed at the thermoforming temperature of the substrate 5 to reduce the pressure difference between the inside and outside of the closed cavity, such as Figure 4 As shown, during the vacuum process inside the cavity 11 of the main body 1, the gas will be discharged outside the cavity 11 through the air hole 12. The air pressure inside the cavity 11 gradually decreases as the gas inside it is discharged. The pressure difference between the inside and outside of the closed cavity gradually increases as the air pressure inside the cavity 11 decreases. The substrate 5 bonded to the base 4 gradually adheres to the outer surface of the molded ball 2 under the action of the pressure difference between the inside and outside of the closed cavity, forming a micro-hemispherical resonator.

[0068] S700. After the forming is completed, the substrate 5 is kept in the thermoforming furnace at the thermoforming temperature for a period of time so that the substrate 5 is fully formed;

[0069] S800. After the temperature of the thermoforming furnace drops to room temperature, the main body 1 is removed from the thermoforming furnace and the bonding sheet formed with the micro-hemispherical resonator is demoulded from the main body 1;

[0070] S900. Remove excess material around the edges of the micro-hemispherical resonator by laser cutting or chemical mechanical polishing to separate the micro-hemispherical resonator from the bonding wafer to obtain a final product.

[0071] Furthermore, the cavity 41 on the substrate 4 of this embodiment is processed by dry etching or wet etching.

[0072] Furthermore, the substrate 5 of this embodiment is made of glass.

[0073] The micro-hemispherical resonator hot forming method provided in this embodiment fully constrains the shape of the micro-hemispherical resonator by forming a molded ball 2 whose shape parameters match the shape parameters of the inner cavity of the micro-hemispherical resonator, and can realize the processing of micro-hemispherical resonators with higher structural symmetry. It has the advantages of controllable shape parameters of the micro-hemispherical resonator, high yield, and simple process flow, which helps to produce higher-precision micro-hemispherical resonator gyroscopes and has broad application prospects in the field of inertial navigation.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A micro-hemispherical resonator thermoforming mold based on full mold constraint, characterized in that: include: A main body (1), the main body (1) having a cavity (11) recessed downward from its top surface, the cavity (11) having a plurality of air holes (12) communicating with the outside of the main body (1), and a positioning hole (13) at the bottom of the cavity (11); A molded ball (2), the molded ball (2) is placed in the mold cavity (11) through the positioning hole (13), the shape parameters of the molded ball (2) match the shape parameters of the micro-hemispherical resonator cavity, and the top of the molded ball (2) is flush with the top surface of the main body (1); A substrate (4) of corresponding size is selected according to the size of the micro-hemispherical resonator, and a cavity (41) is processed on the substrate (4), wherein the substrate (4) is made of a high-temperature resistant material, a substrate (5) for molding is bonded to the substrate (4) to form a bonding sheet, and the substrate (5) and the cavity (41) cooperate to form a closed cavity with air pressure; The molded ball (2) is molded by precision machining according to the shape parameters of the inner cavity of the micro-hemispherical resonator, and its shape parameters match the shape parameters of the inner cavity of the micro-hemispherical resonator. The molded ball (2) plays a full constraint role on the shape parameters of the micro-hemispherical resonator during the molding process of the substrate (5), and can further improve the structural symmetry of the molded micro-hemispherical resonator.

2. The micro-hemispherical resonator thermoforming mold based on full mold constraint according to claim 1, characterized in that: The top surface of the main body (1) is provided with a fixing portion (14), and the fixing portion (14) is used to fix the bonding sheet.

3. The micro-hemispherical resonator thermoforming mold based on full mold constraint according to claim 2, characterized in that: The fixing portion (14) is four raised portions arranged on the edges of the top surface of the main body (1), and the four raised portions are symmetrically spaced in pairs.

4. The micro-hemispherical resonator thermoforming mold based on full mold constraint according to claim 1, characterized in that: It also includes a top cover (3), which is used to press and fix the bonding sheet placed on the top surface of the main body (1).

5. The micro-hemispherical resonator thermoforming mold based on full mold constraint according to claim 1, characterized in that: The plurality of air holes (12) are evenly arranged along the circumference of the positioning hole (13) and are located close to the formed ball (2).

6. The micro-hemispherical resonator thermoforming mold based on full mold constraint according to claim 1, characterized in that: The positioning hole (13) is in the shape of an inverted truncated cone.

7. A method for thermoforming a micro-hemispherical resonator based on full mold constraint, characterized in that: The molding of a micro-hemispherical resonator is performed by using the micro-hemispherical resonator thermoforming mold based on full mold constraint according to any one of claims 1 to 6, comprising the following steps: A substrate (4) of corresponding size is selected according to the size of the micro-hemispherical resonator and a cavity (41) is processed on the substrate (4), wherein the substrate (4) is made of a high-temperature resistant material; Bonding a substrate (5) for forming with the base (4) to form a bonding sheet, wherein the substrate (5) cooperates with the cavity (41) to form a closed cavity with air pressure; forming a demoulding layer on the substrate (5) to facilitate demoulding after molding; Placing the molded ball (2) in the mold cavity (11), and installing the bonding sheet on the top surface of the main body (1) so that the substrate (5) faces the molded ball (2); placing the main body (1) with the formed ball (2) and the bonding sheet installed in a thermoforming furnace and heating it to the thermoforming temperature of the substrate (5) to soften the substrate (5); The thermoforming furnace is evacuated at the thermoforming temperature of the substrate (5) to reduce the pressure difference between the inside and outside of the closed cavity, and the substrate (5) is gradually attached to the outer surface of the forming ball (2) under the action of the pressure difference between the inside and outside of the closed cavity to form a micro-hemispherical resonator; After the forming is completed, the substrate (5) is kept in the thermoforming furnace at the thermoforming temperature for a period of time to allow the substrate (5) to be fully formed; After the temperature of the thermoforming furnace drops to room temperature, the main body (1) is taken out of the thermoforming furnace and the bonding sheet with the micro-hemispherical resonator formed thereon is demoulded and taken out from the main body (1); Excess materials around the edges of the micro-hemispherical resonator are removed to separate the micro-hemispherical resonator from the bonding sheet to obtain a final product.

8. The method for thermoforming a micro-hemispherical resonator based on full mold constraint according to claim 7, characterized in that: The cavity (41) on the substrate (4) is processed by etching.

9. The method for thermoforming a micro-hemispherical resonator based on full mold constraint according to claim 7, characterized in that: The substrate (5) is made of fused quartz.

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