High-stability assembling method for quartz accelerometer connecting ring

Abstract

The application relates to a high-stability assembling method for a quartz accelerometer connecting ring, which comprises the following steps: assembling a heating belt; assembling a piezoelectric ceramic sheet; mounting an accelerometer table core assembled with the connecting ring and the piezoelectric ceramic sheet on an auxiliary assembling tool of the accelerometer, and placing the accelerometer table core on a platform of a laser welding machine; laser welding; applying a high-frequency excitation signal to the piezoelectric ceramic sheet; turning off the power supply of the heating belt of the laser welding machine; when the temperature of the connecting ring returns to room temperature, turning off the power supply of the piezoelectric ceramic; taking down the accelerometer table core from an outer frame, and disassembling the heating belt and the piezoelectric ceramic sheet. According to the application, the residual stress of the welded section can be greatly reduced (the reduction amplitude is close to 100% according to the welded section with the minimum residual stress), meanwhile, the stress average uniformity of different welded sections can be greatly improved (the uniformity is improved from 68.5% to 94.3%), and the problem that the welding stress of the connecting ring affects the long-term stability of the accelerometer is successfully solved.

Description

Technical Field

[0001] This invention relates to the field of inertial measurement sensor technology, and specifically to a highly stable assembly method for a quartz accelerometer connecting ring. Background Technology

[0002] A quartz accelerometer includes a housing and an accelerometer core installed within the housing. The accelerometer core includes a connecting ring, an excitation ring, and a pendulum component. The excitation ring includes an upper excitation ring and a lower excitation ring. Figure 1 As shown, quartz accelerometers, as high-precision, small-sized, and low-cost inertial components, are widely used in various navigation systems. However, inertial navigation systems with medium to high precision have stringent requirements for the long-term stability of related indicators of this type of accelerometer. Current analysis suggests that the assembly stress during the assembly process has a significant impact on long-term stability. Taking the connecting ring of this type of accelerometer as an example, the connecting ring is segmented only by laser and then welded to the upper and lower excitation rings in multiple segments. The welding sequence is: weld segment (1-2up) → weld segment (1-2low) → weld segment (3-4up) → weld segment (3-4low) → weld segment (5-6up) → weld segment (5-6low), without any other auxiliary process measures. Currently, most stress control measures for welding the connecting ring of quartz accelerometers focus on adjusting laser parameters, heating the entire accelerometer core before welding, or modifying the connecting ring structure to reduce welding stress. Laser welding involves complex heat transfer, phase transformation, and deformation processes. An improper welding sequence can lead to significant differences in residual stress between different welded segments.

[0003] Patent number CN202311594425.5, entitled "An Impact-Resistant Quartz Accelerometer," proposes a method for connecting the accelerometer core. This method involves assembling the upper and lower stator components and the pendulum component together using a connecting ring. The connecting ring is connected to the upper and lower stator components via laser welding and bonding. The laser welding is performed in segments, with each segment spot-welded at four points. However, this patent does not disclose the welding sequence between different welding segments, nor does it disclose methods for reducing welding stress.

[0004] Patent number CN201410494717.6, entitled "Welding Method and Welding Structure for Accelerometer Core," proposes a method to reduce welding stress between the upper and lower torque devices and the abdominal belt. This method divides the traditional single-piece abdominal belt into N segments (2≤N≤10), performs pre-spot welding on each segment, and then adjusts the laser incident angle before formal welding. However, this patent does not disclose the welding sequence of the different welding segments.

[0005] The two patents mentioned above did not study or introduce the main factor that directly affects welding stress—the welding sequence. Therefore, the welding stress of the watch core welded using the above methods differs from the ideal value.

[0006] The welding results of the accelerometer segments were inspected using an X-ray diffractometer, and the results are as follows: Figure 2 , Figure 3 As shown: First, it can be found that the residual stress value of the welded section of this type of accelerometer is relatively large, and there is a large space for stress release in the later stage. Therefore, it will have an adverse effect on the long-term performance of this type of accelerometer. Secondly, it can be found that the stress difference (based on the average value) between different welded sections is relatively large. These residual welding stresses with different average values ​​will be transmitted to the capacitor plate of the pendulum through the three steps of the pendulum, which will cause torsional deformation of the capacitor plate and affect the relevant performance indicators of this type of accelerometer.

[0007] To address the above technical problems, this invention proposes a highly stable assembly method for the connecting ring of a quartz accelerometer. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a highly stable assembly method for the connecting ring of a quartz accelerometer. This method can significantly reduce the residual stress in the welded sections (approximately 100% reduction for the welded section with the lowest residual stress) and significantly improve the uniformity of the average stress in different welded sections (from 68.5% to 94.3%). This successfully improves the problem of the welding stress of the connecting ring affecting the long-term stability of the accelerometer.

[0009] The technical problem solved by this invention is achieved through the following technical solution: A highly stable assembly method for a quartz accelerometer connecting ring, wherein the quartz accelerometer includes a housing and an accelerometer core installed within the housing, the accelerometer core includes a connecting ring, an excitation ring, and a pendulum component, and the excitation ring includes an upper excitation ring and a lower excitation ring, comprising the following steps: Step 1: Assemble the heating belt: A heating element is assembled around the outer periphery of the connecting ring of the accelerometer core; Step 2: Assemble the piezoelectric ceramic sheet: Piezoelectric ceramic sheets are assembled on the end faces of the upper and lower excitation rings respectively; Step 3: Install the accelerometer core with the assembly connecting ring and piezoelectric ceramic sheet on the accelerometer auxiliary assembly fixture and place it on the platform of the laser welding machine; The accelerometer auxiliary assembly fixture includes an outer frame, a top rod, a top cap, and a V-shaped iron. The V-shaped iron is installed in the middle of the outer frame, and the top rod and top cap are installed on the outer frame. The top rod and top cap clamp the accelerometer core onto the V-shaped iron. Step 4: Laser welding; 1) Turn on the power to the heating belt of the laser welding machine, adjust the power output to 15V, and heat the connecting ring to 200℃ through the heating belt; 2) Measure the temperature of the connecting ring using a temperature measuring device. When the measurement result shows 200℃, turn on the welding power of the laser welding machine and weld the connecting ring to the upper excitation ring and the lower excitation ring using the laser. Step 5: Apply a high-frequency excitation signal to the piezoelectric ceramic sheet: Turn on the piezoelectric ceramic control power supply to provide a high-frequency output signal to the piezoelectric ceramic sheet; Step 6: Turn off the power to the heating element of the laser welding machine; Step 7: When the temperature of the connecting ring returns to room temperature, turn off the piezoelectric ceramic control power supply; Step 8: Remove the accelerometer core from the outer frame and remove the heating band and piezoelectric ceramic plate.

[0010] Furthermore, in step 2, the piezoelectric ceramic sheets are respectively assembled onto the end faces of the upper excitation ring and the lower excitation ring by adhesive bonding.

[0011] Furthermore, in step 4, the connecting ring is first spot welded, the V-shaped iron is removed, and then segmented welding is performed. The laser welding sequence is: weld segment (5-6up) → weld segment (5-6low) → weld segment (1-2up) → weld segment (1-2low) → weld segment (3-4up) → weld segment (3-4low).

[0012] Furthermore, in step 5, the signal frequency is within the same order of magnitude as the natural frequencies of the upper and lower excitation loops, with an error not exceeding ±50Hz.

[0013] Furthermore, in step 5, a 40kHz high-frequency output signal is given to the piezoelectric ceramic sheet.

[0014] The advantages and positive effects of this invention are: 1. The present invention provides a high-stability assembly method for the connecting ring of a quartz accelerometer. Since there is an assembly gap between the connecting ring and the upper and lower excitation rings, a heating belt is used to preheat the connecting ring separately, so that there is an overall temperature difference between the upper and lower excitation rings and the connecting ring. When the connecting ring returns to room temperature, a shrinkage force can be applied to the weld, which plays a role in releasing and stabilizing the residual welding stress.

[0015] 2. The high-stability assembly method for the quartz accelerometer connecting ring of the present invention solves the problem that the residual stress of the accelerometer connecting ring is large after multi-segment laser welding, and the residual stress values ​​of different weld segments are large. These problems will be further transmitted to the capacitor plate of the accelerometer pendulum component and cause unnecessary deformation. If the problem of welding residual stress is not solved, it will seriously affect the long-term performance indicators of this type of accelerometer.

[0016] 3. The high-stability assembly method for the quartz accelerometer connecting ring of this invention can significantly reduce the residual stress in the welded sections of the accelerometer connecting ring (approximately 100% reduction based on the welded section with the lowest residual stress), effectively reducing the welding residual stress of this type of accelerometer connecting ring. Simultaneously, it can significantly improve the uniformity of the average stress across different welded sections (from 68.5% to 94.3%), improving the uniformity of welding residual stress across different welded sections (based on the average). This successfully addresses the problem of welding stress affecting the long-term stability of the accelerometer, making a significant contribution to improving the long-term stability of related accelerometer indicators. The method and technology developed in this invention can also be applied to laser welding of other similar structural parts. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall assembly of an existing quartz accelerometer; Figure 2 The results of residual welding stress detection between the connecting ring and the upper and lower excitation rings of an existing quartz accelerometer are as follows: Figure 3 The results of residual welding stress detection between the connecting ring and the upper and lower excitation rings of the existing quartz accelerometer are as follows: Figure 4 This is a schematic diagram showing the installation positions of the accelerometer core, piezoelectric ceramic plate, and heating belt in the quartz accelerometer of the present invention. Figure 5 This is a schematic diagram of the connecting ring of the quartz accelerometer of the present invention; Figure 6 This is a schematic diagram of the weld joint between the connecting ring and the upper excitation ring of the quartz accelerometer of the present invention; Figure 7 This is a schematic diagram of the weld joint between the connecting ring and the lower excitation ring of the quartz accelerometer of the present invention; Figure 8 This is a schematic diagram of the overall assembly of the accelerometer core of the quartz accelerometer of the present invention; Figure 9 The third result is the detection result of the welding residual stress between the connecting ring and the upper and lower excitation rings of the quartz accelerometer of the present invention; Figure 10 The fourth result is the detection result of the welding residual stress between the connecting ring and the upper and lower excitation rings of the quartz accelerometer of the present invention; 1. Housing; 2. Accelerometer core; 3. Connecting ring; 4. Upper excitation ring; 5. Lower excitation ring; 6. Swing component; 7. Weld section (1-2up); 8. Weld section (1-2low); 9. Weld section (3-4up); 10. Weld section (3-4low); 11. Weld section (5-6up); 12. Weld section (5-6low); 13. Piezoelectric ceramic sheet; 14. Heating belt; 15. Outer frame; 16. Top rod; 17. Top cap; 18. V-block; 19. Laser. Detailed Implementation

[0018] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0019] like Figure 1 , Figures 4 to 8 A highly stable assembly method for a quartz accelerometer connecting ring, wherein the quartz accelerometer includes a housing 1 and an accelerometer core 2 installed inside the housing 1, the accelerometer core 2 includes a connecting ring 3, an excitation ring, and a pendulum component 6, the excitation ring including an upper excitation ring 4 and a lower excitation ring 5, comprising the following steps: Step 1: Assemble the heating belt 14: Assemble the heating belt 14 around the connecting ring 3 of the accelerometer core 2; Step 2: Assemble the piezoelectric ceramic sheet 13: The piezoelectric ceramic sheet 13 is assembled onto the end faces of the upper excitation ring 4 and the lower excitation ring 5 by adhesive bonding. Step 3: Install the accelerometer core 2 with the assembly connecting ring 3 and piezoelectric ceramic sheet 13 on the accelerometer auxiliary assembly fixture and place it on the platform of the laser welding machine; The accelerometer auxiliary assembly fixture includes an outer frame 15, a top rod 16, a top cap 17, and a V-shaped iron 18. The V-shaped iron 18 is installed in the middle of the outer frame 15. The top rod 16 and the top cap 17 are installed on the outer frame 15. The top rod 16 and the top cap 17 clamp the accelerometer core 2 on the V-shaped iron 18. Step 4: Laser welding; 1) Turn on the power of the heating belt 14 of the laser welding machine, adjust the power output to 15V, and heat the connecting ring 3 to 200℃ through the heating belt 14; Since there is an assembly gap between the connecting ring 3 and the upper excitation ring 4 and the lower excitation ring 5, the heating belt 14 is used to preheat the connecting ring 3 separately, so that the upper excitation ring 4 and the lower excitation ring 5 and the connecting ring 3 have an overall temperature difference. When the connecting ring 3 returns to room temperature, a shrinkage force can be applied to the weld, which plays a role in releasing and stabilizing the welding residual stress. 2) Use a temperature measuring device to measure the temperature of the connecting ring 3. When the measurement result shows 200℃, turn on the welding power of the laser welding machine and weld the connecting ring 3 to the upper excitation ring 4 and the lower excitation ring 5 through the laser 19. First, spot weld the connecting ring 3, remove the V-shaped iron 18, and then perform segmented welding. The laser welding sequence is as follows: weld segment (5-6up) 11 → weld segment (5-6low) 12 → weld segment (1-2up) 7 → weld segment (1-2low) 8 → weld segment (3-4up) 9 → weld segment (3-4low) 10. This welding sequence is the optimized welding sequence after simulation. By adjusting the welding sequence, the residual welding stress can be significantly reduced.

[0020] Step 5: Apply a high-frequency excitation signal to the piezoelectric ceramic sheet 13: Turn on the piezoelectric ceramic control power supply and give the piezoelectric ceramic sheet 13 a high-frequency output signal of 40KHz; the signal frequency is in the same order of magnitude as the natural frequency of the upper excitation ring 4 and the lower excitation ring 5, with an error of no more than ±50Hz; Step 6: Turn off the power to the heating element 14 of the laser welding machine; Step 7: When the temperature of connecting ring 3 returns to room temperature, turn off the piezoelectric ceramic control power supply; Step 8: Remove the accelerometer core 2 from the outer frame 15, and remove the heating band 14 and piezoelectric ceramic plate 13.

[0021] The present invention provides a highly stable assembly method for the quartz accelerometer connecting ring 3. By adjusting the welding sequence, increasing the temperature difference between the connecting ring 3 and the upper and lower excitation rings 5 ​​during welding, and increasing high-frequency vibration after welding, the laser welding stress is significantly improved. The residual stress detection curve is shown in the figure. Figure 9 , Figure 10 As shown in Table 1, the residual stress test results are as follows.

[0022]

[0023] Table 1 Results of Welding Residual Stress Detection After adopting this method, the average residual stress of the same weld segment decreased significantly, and the uniformity of welding residual stress between different weld segments was also greatly improved.

[0024] The present invention provides a high-stability assembly method for the quartz accelerometer connecting ring 3, which solves the problem that the accelerometer connecting ring 3 has large residual stress after multi-segment laser welding and that the residual stress values ​​of different weld segments are large. These problems will be further transmitted to the capacitor plate of the accelerometer pendulum component 6, causing unnecessary deformation. If the problem of welding residual stress is not solved, it will seriously affect the long-term performance indicators of this type of accelerometer.

[0025] This invention provides a highly stable assembly method for the quartz accelerometer connecting ring. This method significantly reduces the residual stress in the welded sections of the accelerometer connecting ring 3 (approximately 100% reduction based on the welded section with the lowest residual stress), effectively reducing the welding residual stress in this type of accelerometer connecting ring 3. Simultaneously, it significantly improves the uniformity of stress average across different welded sections (from 68.5% to 94.3%), enhancing the uniformity of welding residual stress across different welded sections (based on the average). This successfully addresses the issue of welding stress in the connecting ring 3 affecting the long-term stability of the accelerometer, making a significant contribution to improving the long-term stability of related accelerometer indicators. The method and technology developed in this invention can also be applied to laser welding of other similar structural parts.

[0026] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A high-stability assembly method for a quartz accelerometer connecting ring, wherein the quartz accelerometer includes a housing (1) and an accelerometer core (2) installed inside the housing (1), the accelerometer core (2) includes a connecting ring (3), an excitation ring, and a pendulum component (6), the excitation ring including an upper excitation ring (4) and a lower excitation ring (5), characterized in that, Includes the following steps: Step 1, Assemble the heating belt (14): A heating band (14) is assembled around the outer periphery of the connecting ring (3) of the accelerometer core (2); Step 2, Assemble the piezoelectric ceramic sheet (13): Piezoelectric ceramic sheets (13) are respectively assembled on the end faces of the upper excitation ring (4) and the lower excitation ring (5). Step 3: Install the accelerometer core (2) with the assembly connecting ring (3) and piezoelectric ceramic sheet (13) on the accelerometer auxiliary assembly fixture and place it on the platform of the laser welding machine; The accelerometer auxiliary assembly fixture includes an outer frame (15), a top rod (16), a top cap (17), and a V-shaped iron (18). The V-shaped iron (18) is installed in the middle of the outer frame (15). The top rod (16) and the top cap (17) are installed on the outer frame (15). The top rod (16) and the top cap (17) clamp the accelerometer core (2) on the V-shaped iron (18). Step 4: Laser welding; 1) Turn on the power of the heating belt (14) of the laser welding machine, adjust the power output to 15V, and heat the connecting ring (3) to 200℃ through the heating belt (14); 2) Use a temperature measuring device to measure the temperature of the connecting ring (3). When the measurement result shows 200℃, turn on the welding power of the laser welding machine and weld the connecting ring (3) to the upper excitation ring (4) and the lower excitation ring (5) by laser. Step 5: Apply a high-frequency excitation signal to the piezoelectric ceramic sheet (13): Turn on the piezoelectric ceramic control power supply to provide a high-frequency output signal to the piezoelectric ceramic sheet (13); Step 6: Turn off the power to the heating element (14) of the laser welding machine; Step 7: When the temperature of the connecting ring (3) returns to room temperature, turn off the piezoelectric ceramic control power supply; Step 8: Remove the accelerometer core (2) from the outer frame (15) and remove the heating band (14) and piezoelectric ceramic plate (13).

2. The high-stability assembly method for the quartz accelerometer connecting ring according to claim 1, characterized in that, In step 2, the piezoelectric ceramic sheet (13) is assembled on the end faces of the upper excitation ring (4) and the lower excitation ring (5) by bonding.

3. The high-stability assembly method for the quartz accelerometer connecting ring according to claim 1, characterized in that, In step 4, the connecting ring (3) is first spot welded, and the V-shaped iron (18) is removed before segment welding is performed. The laser welding sequence is weld segment (5-6up) (11) → weld segment (5-6low) (12) → weld segment (1-2up) (7) → weld segment (1-2low) (8) → weld segment (3-4up) (9) → weld segment (3-4low) (10).

4. The high-stability assembly method for the quartz accelerometer connecting ring according to claim 1, characterized in that, In step 5, the signal frequency is within the same order of magnitude as the natural frequencies of the upper excitation ring (4) and the lower excitation ring (5), with an error not exceeding ±50Hz.

5. The high-stability assembly method for the quartz accelerometer connecting ring according to claim 1, characterized in that, In step 5, a 40KHz high-frequency output signal is given to the piezoelectric ceramic sheet (13).

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