A graphite mold for forming a micro-hemispherical resonator
By designing graphite molds for microhemispheric oscillator molding, the negative pressure cavity and pore structure are used to increase the negative pressure, the problems of uneven wall thickness and insufficient stiffness of the microhemispheric wall thickness are solved, and the wall thickness uniformity and quality factor are improved.
Patent Information
- Application Number
- CN202421495063.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-27
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-06-27
AI Technical Summary
In the preparation of microhemispheric oscillators, there are problems of poor mold symmetry accuracy and pressure uniformity, resulting in uneven thickness of shoulder walls of microhemispherics, reduced stiffness, and problems such as inflexion of the top of the hemispheric shell during the molding process, affecting the improvement of quality factor.
A graphite mold for microhemispherical oscillator forming is designed, with a limit groove in the center of the top surface and a negative pressure cavity for communication with the vacuum device in the center of the bottom surface, forming a ball shell with a central nail, the bottom wall thickness of the ball shell is greater than the side wall thickness, and a pore is opened at the bottom of the ball shell to increase the negative pressure and promote the rapid flow and molding of the quartz sheet.
By increasing the negative pressure, the quartz sheets are rapidly flowing and forming, which effectively improves the uniformity of the wall thickness of the microhemisphere, improves the quality factor, avoids the problem of too thin shoulder wall thickness, and enhances the stiffness and reliability of the microhemisphere.
Smart Images
Figure CN222715238U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of inertial navigation device preparation, in particular to a graphite mold used for molding a micro-hemispherical resonator. Background Art
[0002] The hemispherical resonant gyroscope is a high-precision vibrating gyroscope with high precision, strong stability, high reliability, good impact resistance, excellent radiation resistance and long life. According to literature data, the hemispherical resonant gyroscope can work continuously for more than 15 years and maintain a reliability of more than 44%, and is used in navigation, satellites, missiles, aviation and other fields.
[0003] The difficulty of manufacturing micro-hemispherical resonant gyroscope lies in the molding and processing of the resonant structure. In order to improve the quality factor of the resonator, reduce frequency cracking, and prepare high-precision electrodes, various processing methods have been developed at home and abroad, among which the high-temperature blowtorch blowing process based on hydrogen-oxygen flame is the mainstream. This method uses a high-temperature blowtorch to heat the molten quartz sheet to soften it, and uses a graphite mold to shape it through the surface pressure difference.
[0004] However, the micro-hemispheres prepared by the blowtorch thermoforming method are limited by the mold symmetry accuracy and poor pressure uniformity, resulting in the following problems:
[0005] 1) During the hot melt molding process of the micro-hemispherical ball, when the softened quartz flows along the graphite mold, the thickness of the shoulder away from the lip edge will be significantly smaller than the thickness of the lip edge. The unreasonable design of the mold will lead to an ultra-thin shoulder wall thickness, which greatly reduces the rigidity of the micro-hemispherical ball and causes the micro-hemispherical ball to break during transportation or vibration, greatly reducing its reliability.
[0006] 2) The shape of the mold design is unreasonable, resulting in poor stability and controllability of the negative pressure during molding, causing the hot-melt quartz to be unable to be molded according to the shape of the mold design and poor symmetry accuracy;
[0007] 3) During the blowing process, the top of the hemispherical shell of the micro-hemisphere often buckles inward toward the center pin because the upper structure cools faster than the lower structure, which affects the improvement of the quality factor of the micro-hemisphere.
[0008] 4) The shape design of the center pin molding needs to solve the problem of difficult demoulding. Summary of the invention
[0009] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and to provide a graphite mold for forming a micro-hemispherical resonator, which can improve the uniformity of the wall thickness of the formed micro-hemispherical resonator, thereby improving the quality factor of the micro-hemispherical resonator.
[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0011] A graphite mold for molding a micro-hemispherical resonator, wherein a limiting groove matching a quartz plate is provided at the center of the top surface of the graphite mold, the center of the bottom surface of the limiting groove is depressed downward to form a hemispherical cavity, and the center of the bottom surface of the cavity extends upward to form a center pin; a negative pressure cavity for connecting with a vacuum device is provided at the center of the bottom surface of the graphite mold, the negative pressure cavity extends upward to form a spherical shell with a center pin between the cavity and the negative pressure cavity, a plurality of air holes penetrating the spherical shell to connect the cavity and the negative pressure cavity are provided on the wall surface of the cavity, the bottom wall thickness of the spherical shell is greater than the side wall thickness, and the air holes are provided at the bottom of the spherical shell.
[0012] The utility model discloses a graphite mold for forming a micro-hemispherical resonator. The negative pressure cavity for communicating with a vacuum pumping device is opened at the center of the bottom surface of the graphite mold, and the negative pressure cavity is extended upward to form a spherical shell with a center nail between the mold cavity and the negative pressure cavity, and the bottom wall thickness of the spherical shell is made greater than the side wall thickness. Then, an air hole for communicating with the mold cavity and the negative pressure cavity is opened at the bottom of the spherical shell. Since the material of graphite has a certain porosity and the opening at the bottom, gas can flow from the inner cavity to the outer cavity. According to the flow loss relationship of fluid mechanics, the thicker the wall thickness and the deeper the hole depth, the greater the pressure loss. Therefore, the greater the pressure difference between the inner cavity and the outer cavity, the negative pressure can be effectively increased, so that the softened quartz sheet can flow quickly toward the outer cavity wall.
[0013] Optionally, the bottom wall thickness of the spherical shell is 3-5 times the side wall thickness thereof.
[0014] Optionally, the side wall surface of the negative pressure chamber is a conical surface that is narrow at the top and wide at the bottom.
[0015] Optionally, projections of the plurality of pores on the cross section of the central nail are radially distributed with the central nail as the center.
[0016] Optionally, a first rounded corner is provided at a connection between the bottom wall of the limiting groove and the side wall of the cavity.
[0017] Optionally, the radius of the first rounded corner is R0.1-R0.3.
[0018] Optionally, a second rounded corner is provided at a connection between the outer wall of the center nail and the bottom wall of the cavity.
[0019] Optionally, the radius of the second fillet is R12-R16.
[0020] Optionally, the height of the center pin is smaller than the depth of the cavity.
[0021] Optionally, the center of the top surface of the graphite mold extends upward to form a boss, the limiting groove is opened on the boss, and the depth of the cavity is less than the height of the boss.
[0022] Optionally, a plurality of connection holes for fixing to a vacuum pumping device are provided on the edge of the top surface of the graphite mold.
[0023] Compared with the prior art, the utility model has the following beneficial effects: the utility model effectively increases the negative pressure, prompting the softened quartz sheet to flow quickly toward the outer cavity wall, thereby effectively increasing the wall thickness of the micro-hemispherical body formed there, avoiding the shoulder wall thickness of the micro-hemispherical body being too thin, thereby greatly improving the uniformity of the wall thickness of the formed micro-hemispherical body, and then improving the quality factor of the micro-hemispherical body. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a schematic cross-sectional structure diagram of a graphite mold for forming a micro-hemispherical resonator according to an embodiment of the utility model;
[0025] Figure 2 The three-dimensional structure schematic diagram of the graphite mold used for forming a micro-hemispherical resonator according to an embodiment of the utility model.
[0026] Legend: 1. Boss; 2. Limiting groove; 4. Negative pressure cavity; 5. Connecting hole; 6. Second fillet; 7. Center pin; 8. Cavity; 9. Air hole; 10. Outer wall; 11. First fillet. DETAILED DESCRIPTION
[0027] The present invention is further described below in conjunction with specific preferred embodiments, but the protection scope of the present invention is not limited thereby.
[0028] like Figure 1 and Figure 2 As shown, the graphite mold for forming a micro-hemispherical resonator in this embodiment has a limit groove 2 matching the quartz plate at the center of the top surface of the graphite mold, the center of the bottom surface of the limit groove 2 is depressed downward to form a hemispherical cavity 8, and the center of the bottom surface of the cavity 8 extends upward to form a center pin 7; a negative pressure cavity 4 for connecting with a vacuum device is opened at the center of the bottom surface of the graphite mold, and the negative pressure cavity 4 extends upward to form a spherical shell with a center pin 7 between the cavity 8 and the negative pressure cavity 4, and a plurality of air holes 9 penetrating the spherical shell to connect the cavity 8 and the negative pressure cavity 4 are opened on the wall surface of the cavity 8, the bottom wall thickness of the spherical shell is greater than the side wall thickness, and the air hole 9 is opened at the bottom of the spherical shell.
[0029] Therefore, by opening a negative pressure cavity 4 for connecting with the vacuum equipment at the center of the bottom surface of the graphite mold, and extending the negative pressure cavity 4 upward to between the cavity 8 and the negative pressure cavity 4 to form a spherical shell with a center pin 7, and making the bottom wall thickness of the spherical shell greater than the side wall thickness, and then opening an air hole connecting the cavity 8 and the negative pressure cavity 4 at the bottom of the spherical shell, since the material of graphite has a certain porosity, plus the opening at the bottom, the gas can flow from the inner cavity to the outer cavity. According to the flow loss relationship in fluid mechanics, the thicker the wall thickness and the deeper the hole depth, the greater the pressure loss, so the greater the pressure difference between the inner cavity and the outer cavity, thereby effectively increasing the negative pressure, prompting the softened quartz sheet to flow quickly toward the outer cavity wall, thereby effectively increasing the wall thickness of the micro-hemispherical formed at this location, avoiding the shoulder wall thickness of the micro-hemispherical being too thin, thereby greatly improving the uniformity of the wall thickness of the formed micro-hemispherical, and then improving the quality factor of the micro-hemispherical.
[0030] In this embodiment, the bottom wall thickness of the ball shell is 3-5 times the side wall thickness. Practice shows that this wall thickness range can not only form micro hemispheres with uniform wall thickness, but also ensure the service life of the mold.
[0031] In this embodiment, the side wall of the negative pressure chamber 4 is a tapered surface that is narrow at the top and wide at the bottom. The negative pressure chamber 4 adopts a slope design that is narrow at the top and wide at the bottom to avoid energy loss in the vortex zone and improve the efficiency of pumping negative pressure.
[0032] In this embodiment, projections of the plurality of air holes 9 on the cross section of the center nail 7 are radially distributed with the center nail 7 as the center.
[0033] Therefore, due to the evenly distributed pores 9 and the negative pressure cavity 4 with an outward expanding wall shape, the negative pressure forms a uniform pressure in the entire mold cavity to promote the molding of the hemisphere. By controlling the heating and pressure, it is possible to avoid the hemisphere from contacting the pores due to excessive local pressure, resulting in local excessive deformation.
[0034] In this embodiment, a first rounded corner 11 is formed at the connection between the bottom wall of the limiting groove 2 and the side wall of the cavity 8 .
[0035] Due to the design of the first fillet 11, when the flame leaves the softened quartz sheet, the cooled quartz sheet will not shrink toward the center pin 7, which can effectively improve the quality factor of the formed micro-hemispherical. In other words, due to the existence of the first fillet 11, the surface tension of the formed micro-hemispherical is directed toward the mold, which can resist a part of the cold shrinkage effect and avoid the defect of the lip edge and the hemispherical body connecting the micro-hemispherical body being sunken toward the center (i.e., shrinking) after the micro-hemispherical body is formed.
[0036] In this embodiment, the radius of the first fillet 11 is R0.1-R0.3, which can better avoid the shrinkage defect at the junction of the lip edge and the hemispherical body after the micro-hemisphere is formed, and does not affect the quality of the hemispherical resonator.
[0037] In this embodiment, a second fillet 6 is formed at a connection between the outer wall 10 of the center pin 7 and the bottom wall of the cavity 8 .
[0038] The center pin 7 is cylindrical at the top, and the connection position with the inner cavity wall 3 adopts a wedge-shaped design with a rounded transition, which can effectively improve the demoulding problem after the micro-hemispherical molding and ensure that the center pin still has an effective clamping length in subsequent use.
[0039] In this embodiment, the radius of the second fillet 6 is R12-R16.
[0040] In this embodiment, the height of the center pin 7 is smaller than the depth of the cavity 8 .
[0041] In this embodiment, the center of the top surface of the graphite mold extends upward to form a boss 1 , the limiting groove 2 is opened on the boss 1 , and the depth of the cavity 8 is less than the height of the boss 1 .
[0042] In this embodiment, a plurality of connection holes 5 for fixing to the vacuum equipment are provided on the edge of the top surface of the graphite mold.
[0043] The above is only a preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.
Claims
1. A graphite mold for forming a micro-hemispherical resonator, characterized in that: A limiting groove (2) matching the quartz plate is provided at the center of the top surface of the graphite mold, the center of the bottom surface of the limiting groove (2) is recessed downward to form a hemispherical cavity (8), and the center of the bottom surface of the cavity (8) extends upward to form a center pin (7); A negative pressure cavity (4) for connecting with a vacuum device is provided at the center of the bottom surface of the graphite mold. The negative pressure cavity (4) extends upward to form a spherical shell having a center pin (7) between the mold cavity (8) and the negative pressure cavity (4). The wall surface of the mold cavity (8) is provided with a plurality of air holes (9) penetrating the spherical shell to connect the mold cavity (8) and the negative pressure cavity (4). The bottom wall thickness of the spherical shell is greater than the side wall thickness, and the air holes (9) are provided at the bottom of the spherical shell.
2. The graphite mold for forming a micro-hemispherical resonator according to claim 1, characterized in that: The bottom wall thickness of the spherical shell is 3-5 times the side wall thickness.
3. The graphite mold for forming a micro-hemispherical resonator according to claim 1, characterized in that: The side wall surface of the negative pressure chamber (4) is a conical surface that is narrow at the top and wide at the bottom.
4. The graphite mold for forming a micro-hemispherical resonator according to claim 1, characterized in that: Projections of the plurality of air holes (9) on the cross section of the central nail (7) are radially distributed with the central nail (7) as the center.
5. The graphite mold for forming a micro-hemispherical resonator according to any one of claims 1 to 4, characterized in that: The connection between the bottom wall of the limiting groove (2) and the side wall of the cavity (8) has a first rounded corner (11).
6. The graphite mold for forming a micro-hemispherical resonator according to claim 5, characterized in that: The radius of the first rounded corner (11) is R0.1-R0.
3.
7. The graphite mold for forming a micro-hemispherical resonator according to claim 5, characterized in that: A second fillet (6) is provided at the connection between the outer wall (10) of the center pin (7) and the bottom wall of the cavity (8), and the radius of the second fillet (6) is R12-R16.
8. The graphite mold for forming a micro-hemispherical resonator according to any one of claims 1 to 4, characterized in that: The height of the center pin (7) is smaller than the depth of the cavity (8).
9. The graphite mold for forming a micro-hemispherical resonator according to any one of claims 1 to 4, characterized in that: The center of the top surface of the graphite mold extends upward to form a boss (1), the limiting groove (2) is opened on the boss (1), and the depth of the cavity (8) is less than the height of the boss (1).
10. The graphite mold for forming a micro-hemispherical resonator according to any one of claims 1 to 4, characterized in that: The top edge of the graphite mold is provided with a plurality of connection holes (5) for being fixedly connected to a vacuum pumping device.