A laser polishing method for hemispherical resonator

Abstract

This invention belongs to the technical field of hemispherical resonator gyroscope manufacturing and discloses a laser polishing method for hemispherical resonators. The method includes: cleaning a ground hemispherical resonator to remove surface impurities, followed by drying; clamping the hemispherical resonator on a five-axis linkage platform, and sequentially scanning the outer and inner surfaces of the hemispherical resonator according to a set trajectory using a controlled laser, thereby performing melt polishing of the outer and inner surfaces, reducing surface roughness while repairing subsurface damage; finally, annealing the laser-polished hemispherical resonator to eliminate residual stress. Compared with existing technologies, this invention effectively solves the problems of low processing efficiency and inability to completely remove subsurface damage layers in existing polishing methods for hemispherical resonators. Furthermore, it eliminates the chemical corrosion step in existing processes, thus improving the production efficiency of hemispherical resonators and being more environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the technical field of hemispherical resonator gyroscope manufacturing, and more specifically, relates to a laser polishing method for hemispherical resonators. Background Technology

[0002] A hemispherical resonant gyroscope is a type of Gothic gyroscope that uses the precession of standing waves from a hemispherical harmonic oscillator to measure angles or angular velocities. Hemispherical resonant gyroscopes are characterized by high precision, long lifespan, high reliability, small size, and low power consumption. They have been successfully applied in fields such as navigation, aerospace, aviation, and weaponry, demonstrating significant technological advantages and broad application prospects.

[0003] The hemispherical resonator is the core component of a hemispherical resonant gyroscope, typically made of high-quality quartz glass. The machining accuracy, surface roughness, and subsurface damage of the hemispherical resonator are key factors affecting the performance of the hemispherical resonant gyroscope. For example... Figure 6 As shown, the current manufacturing process of hemispherical resonators mainly includes: rough grinding, precision grinding, polishing, chemical etching, quality leveling, and surface coating. Polishing aims to reduce the surface roughness and subsurface damage of the hemispherical resonator. Even after polishing, a certain depth of processing damage layer remains on the resonator surface, which has a significant negative impact on the resonator's quality factor. Therefore, chemical etching is needed to further remove the damage layer from the resonator's surface.

[0004] A search revealed that existing polishing methods for hemispherical resonators mainly include traditional mechanical polishing, magnetorheological polishing, and mechanorheological polishing. However, further research shows that these existing technologies still have the following drawbacks: for example, mechanical polishing has low processing efficiency and introduces new subsurface damage; magnetorheological and mechanorheological polishing do not generate new subsurface damage, but they cannot completely remove existing subsurface damage and have low processing efficiency. Accordingly, further improvements are urgently needed in this field to meet the manufacturing requirements of higher quality and higher performance hemispherical resonators. Summary of the Invention

[0005] To address the shortcomings and improvement needs of existing technologies, this invention redesigns the entire polishing process and its mechanism by closely integrating the product characteristics and application requirements of the hemispherical resonator. Simultaneously, it optimizes and improves some key processing parameters. Consequently, it not only more effectively reduces the surface roughness of the hemispherical resonator and repairs subsurface damage, but also eliminates the need for chemical etching after polishing, significantly improving processing efficiency and environmental friendliness. Therefore, it is particularly suitable for mass production applications of hemispherical resonators.

[0006] To achieve the above objectives, according to the present invention, a laser polishing method for a hemispherical harmonic oscillator is provided, characterized in that the method includes the following steps:

[0007] (i) Preprocessing steps

[0008] The hemispherical harmonic oscillator, after being ground, is cleaned to remove surface impurities and then dried.

[0009] (ii) Polishing steps for the outer surface

[0010] The hemispherical harmonic oscillator is clamped onto a five-axis linkage platform, and the laser is turned on so that the laser spot is perpendicularly irradiated on the outer surface of the hemispherical harmonic oscillator.

[0011] By controlling the relative motion between the hemispherical harmonic oscillator and the laser head, the trajectory of the laser spot covers the outer surface of the hemispherical harmonic oscillator, and the laser melting and polishing process of the entire outer surface is completed.

[0012] (iii) Polishing steps for the inner surface

[0013] By changing the clamping position of the hemispherical resonator and controlling the relative movement between the hemispherical resonator and the laser head, the trajectory of the laser spot covers the inner surface of the hemispherical resonator, and the laser melting and polishing process of the entire inner surface is completed.

[0014] (iv) Post-processing steps

[0015] After the hemispherical harmonic oscillator has undergone laser melting and polishing of its outer and inner surfaces, it is annealed to eliminate residual stress, thus completing the entire laser polishing process.

[0016] Based on the above concept, on the one hand, this invention introduces a laser melting polishing method. When a laser irradiates the surface of a material, the surface absorbs energy and the material heats up. After the material reaches its melting point, a phase transition occurs. The part melted by the laser flows to and fills depressions and cracks, and after cooling, it re-solidifies into a new surface, playing a role in "filling valleys with melting peaks." Compared with existing technologies, this method can significantly reduce surface roughness and effectively repair subsurface damage. On the other hand, the entire polishing process of this invention no longer uses any coolant or chemical polishing fluid, and eliminates the chemical corrosion process. This method is more environmentally friendly and greatly improves overall production efficiency, which is conducive to the mass production of hemispherical harmonic oscillators.

[0017] As a further preferred embodiment, in step (i), the hemispherical harmonic oscillator preferably has an initial surface roughness of 50nm-200nm after grinding.

[0018] As a further preferred embodiment, in step (i), the hemispherical harmonic oscillator is preferably ultrasonically cleaned with a cleaning solution, then rinsed with deionized water, and finally dried in a clean environment.

[0019] As a further preferred embodiment, in steps (ii) and (iii), the process parameters for the laser melting polishing process are preferably set as follows: a pulsed CO2 laser is used as the laser source, the laser wavelength is 10.6 μm, the laser power is 100 W, and the spot diameter is 50 μm-200 μm.

[0020] As a further preferred embodiment, in steps (ii) and (iii), it is preferable to measure the thickness of the subsurface damage layer of the hemispherical harmonic oscillator in advance, and to ensure that the surface molten pool depth of the hemispherical harmonic oscillator is greater than the thickness of the subsurface damage layer by adjusting a series of process parameters such as the output power, spot diameter, frequency, duty cycle, scanning speed, and scanning spacing of the laser.

[0021] As a further preferred embodiment, in step (iv), the hemispherical harmonic oscillator is preferably placed in a constant temperature furnace for stress-relief annealing, and the annealing temperature is 800℃-1000℃, and the annealing time is more than 12 hours.

[0022] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0023] 1. This invention redesigns the entire polishing process and mechanism of the hemispherical harmonic oscillator, which can make full use of the laser melting polishing effect so that the part melted by the laser flows to the depressions and cracks and fills them. After cooling, it resolidifies into a new surface, achieving the effect of "melting peak filling valley". This significantly reduces the surface roughness and effectively repairs the subsurface damage.

[0024] 2. The present invention further makes targeted improvements to several key parameters of the entire polishing process, which can effectively ensure that the depth of the molten pool on the inner and outer surfaces of the hemispherical harmonic oscillator is greater than the thickness of the subsurface damage layer, and obtain hemispherical harmonic oscillator products with better quality and performance.

[0025] 3. The laser polishing method of the present invention can eliminate the chemical etching process in the existing process flow, and at the same time, it no longer requires the use of any coolant and chemical polishing liquid, which is more environmentally friendly. It also greatly improves the overall processing efficiency and is conducive to the mass production of hemispherical harmonic oscillators. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall process flow of the laser polishing method for a hemispherical harmonic oscillator designed according to the present invention;

[0027] Figure 2 This is a schematic diagram showing a hemispherical harmonic oscillator mounted on a five-axis linkage platform;

[0028] Figure 3 This is a schematic diagram of a hemispherical harmonic oscillator structure;

[0029] Figure 4 This is a schematic diagram illustrating the laser scanning trajectory on the outer surface of a hemispherical harmonic oscillator.

[0030] Figure 5 This is a schematic diagram illustrating the laser scanning trajectory on the inner surface of a hemispherical harmonic oscillator.

[0031] Figure 6 This is a flowchart of the existing technology manufacturing process for hemispherical harmonic oscillators;

[0032] Figure 7 This is a flowchart of the manufacturing process of a hemispherical harmonic oscillator after laser polishing, as introduced in this invention.

[0033] In the diagram: 1. Five-axis linkage platform; 2. Hemispherical resonator; 3. CO2 laser; 4. Beam expander; 5. Optical shutter; 6. Aperture; 7. Focusing lens. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Figure 1 This is a schematic diagram of the overall process flow of the laser polishing method for hemispherical harmonic oscillators designed according to the present invention. Figure 7 This is a flowchart illustrating the manufacturing process of a hemispherical resonator after laser polishing, as introduced according to this invention. Figure 1 and Figure 7 As shown, this invention redesigns the entire polishing process and its mechanism, which not only more effectively reduces the surface roughness of the hemispherical resonator and repairs subsurface damage, but also eliminates the chemical corrosion step in the existing process of hemispherical resonators. This not only improves the production efficiency of hemispherical resonators, but is also more environmentally friendly.

[0036] According to the basic concept of this invention, the above-mentioned laser polishing method mainly includes the following steps:

[0037] First, there is the preprocessing step.

[0038] In this step, the hemispherical resonator, which has been ground, is cleaned to remove surface impurities and then dried.

[0039] More specifically, for example, an ultrasonic cleaner can be used in a Class 10,000 cleanroom to ultrasonically clean a precision-ground hemispherical resonator. To remove as many surface impurities as possible from the hemispherical resonator, it can first be ultrasonically cleaned with a cleaning solution, then rinsed with deionized water, and finally dried in a dryer.

[0040] Next comes the polishing step for the inner and outer surfaces.

[0041] In this step, the hemispherical resonator is clamped on a five-axis linkage platform, and the laser is turned on so that the laser spot is perpendicularly irradiated on the outer surface of the hemispherical resonator. By controlling the relative movement between the hemispherical resonator and the laser head, the trajectory of the laser spot covers the outer surface of the hemispherical resonator, and the laser melting and polishing process of the entire outer surface is completed.

[0042] Next, the clamping position of the hemispherical resonator is changed, and the relative movement between the hemispherical resonator and the laser head is controlled so that the trajectory of the laser spot covers the inner surface of the hemispherical resonator, and the laser melting and polishing process of the entire inner surface is completed.

[0043] More specifically, such as Figure 2 As shown, a hemispherical resonator is mounted on a five-axis linkage platform. The laser head is fixed horizontally, and the Z-axis is moved so that the axis of the hemispherical resonator and the laser head are on the same horizontal plane. The laser is turned on, and parameters such as output power, spot diameter, frequency, and duty cycle are set. The position of the hemispherical resonator is adjusted so that the laser spot is perpendicularly irradiated on the outer surface of the hemispherical resonator. Furthermore, the movement of the hemispherical resonator along the X and Y axes and its rotation around the A and C axes can be achieved through CNC control, and the scanning speed and scanning interval can be controlled so that the laser spot can follow the specified path. Figure 4 The trajectory shown scans the outer surface of the hemispherical harmonic oscillator.

[0044] Next, the clamping position of the hemispherical resonator is changed, and the movement of the hemispherical resonator along the X and Y axes and its rotation around the A and C axes are further controlled by numerical control, so that the laser spot can move according to... Figure 5 The trajectory shown scans the inner surface of the hemispherical harmonic oscillator.

[0045] Furthermore, through simulation analysis of the temperature field of quartz glass under laser irradiation, the influence of process parameters such as output power, spot diameter, frequency, duty cycle, scanning speed, and scanning spacing on the depth of the quartz glass molten pool is studied. Accordingly, the value range of these process parameters can be determined specifically according to actual needs.

[0046] According to a preferred embodiment of the present invention, the process parameters for the laser melting and polishing process are preferably set as follows: a pulsed CO2 laser is used as the laser source, the laser wavelength is 10.6 μm, the laser power is 100 W, and the spot diameter is 50 μm-200 μm.

[0047] According to another preferred embodiment of the present invention, the thickness of the subsurface damage layer of the hemispherical harmonic oscillator can be measured in advance, and a series of process parameters such as the output power, spot diameter, frequency, duty cycle, scanning speed, and scanning spacing of the laser can be adjusted to ensure that the surface molten pool depth of the hemispherical harmonic oscillator is greater than the thickness of the subsurface damage layer.

[0048] Finally, there is the post-processing step.

[0049] In this step, the hemispherical harmonic oscillator, after undergoing laser melting and polishing of the outer and inner surfaces, is annealed to eliminate residual stress, thus completing the entire laser polishing process.

[0050] More specifically, the laser-polished hemispherical harmonic oscillator can be placed in a constant temperature furnace for stress-relief annealing at a temperature of 800℃-1000℃ for a time of more than 12 hours.

[0051] Figure 6 This is a flowchart of the existing manufacturing process for hemispherical harmonic oscillators. Figure 7 This is a flowchart of the manufacturing process of a hemispherical resonator after laser polishing according to the present invention. Comparing the two, it can be found that the outstanding advantages of the laser melting polishing method used in this invention are: firstly, it significantly reduces surface roughness while effectively repairing subsurface damage; secondly, the chemical etching step in the existing resonator manufacturing process can be omitted, and the manufacturing process of the hemispherical resonator according to the present invention is significantly shortened, which not only improves production efficiency but is also more environmentally friendly.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser polishing method for a hemispherical resonator, characterized by, The method includes the following steps: (i) Preprocessing steps The hemispherical harmonic oscillator, after being ground, is cleaned to remove surface impurities and then dried. (ii) Polishing steps for the outer surface The hemispherical harmonic oscillator is clamped onto a five-axis linkage platform, and the laser is turned on so that the laser spot is perpendicularly irradiated on the outer surface of the hemispherical harmonic oscillator. By controlling the relative motion between the hemispherical harmonic oscillator and the laser head, the trajectory of the laser spot covers the outer surface of the hemispherical harmonic oscillator, and the laser melting and polishing process of the entire outer surface is completed. (iii) Polishing steps for the inner surface By changing the clamping position of the hemispherical resonator and controlling the relative movement between the hemispherical resonator and the laser head, the trajectory of the laser spot covers the inner surface of the hemispherical resonator, and the laser melting and polishing process of the entire inner surface is completed. In steps (i) and (iii), the process parameters for the laser melting polishing process are set as follows: a pulsed CO2 laser is used as the laser source, the laser wavelength is 10.6 μm, the laser power is 100 W, and the spot diameter is 50 μm-200 μm; in addition, the thickness of the subsurface damage layer of the hemispherical harmonic oscillator is measured in advance, and it is ensured that the surface molten pool depth of the hemispherical harmonic oscillator is greater than the thickness of the subsurface damage layer. (iv) Post-processing steps After the hemispherical resonator has undergone laser melting and polishing of its outer and inner surfaces, it is annealed to eliminate residual stress, thus completing the entire laser polishing process. In the entire polishing process described above, no coolant or chemical polishing fluid is used, and the chemical etching process is eliminated.

2. The laser polishing method as described in claim 1, characterized in that, In step (i), the hemispherical harmonic oscillator has an initial surface roughness of 50nm-200nm after grinding.

3. The laser polishing method as described in claim 2, characterized in that, In step (i), the hemispherical harmonic oscillator is ultrasonically cleaned with a cleaning solution, then rinsed with deionized water, and finally dried in a clean environment.

4. The laser polishing method according to any one of claims 1-3, characterized in that, In steps (ii) and (iii), a series of process parameters, such as the output power, spot diameter, frequency, duty cycle, scanning speed, and scanning spacing of the laser, are adjusted to ensure that the surface molten pool depth of the hemispherical harmonic oscillator is greater than the thickness of the subsurface damage layer.

5. The laser polishing method as described in claim 4, characterized in that, In step (iv), the hemispherical harmonic oscillator is placed in a constant temperature furnace for stress-relief annealing at a temperature of 800℃-1000℃ for a time of 12 hours or more.

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