Quartz tube and tube cap oxyhydrogen flame automatic seal welding method based on multi-degree-of-freedom cooperative control

Abstract

The invention provides a multi-degree-of-freedom cooperative control-based quartz tube and tube cap oxyhydrogen flame automatic seal welding method. The method comprises the following steps of S1, vacuum preparation: fixing a quartz tube loaded with indium phosphide polycrystal materials and a tube cap on a positioning platform for vacuumizing; the three-dimensional coordinates of the quartz tube and the tube cap are obtained through laser scanning, a seven-axis mechanical arm path is generated, and the fitting error is smaller than or equal to 0.05 mm; s3, a preheating stage; s4, a heat sealing stage, wherein the temperature is kept constant after temperature rise, and the circumferential speed of a mechanical arm is 0.8-1.2 rad / s; s5, a slow cooling stage, wherein the temperature is reduced to 700 DEG C, and the moving speed is 8-12 mm / s; and S6, airtightness detection: the standard is less than or equal to 5 * 10 Pa.m / s. The problem of quartz tube and tube cap curved surface welding is solved through four-degree-of-freedom dynamic compensation, thermal field stable control is achieved through gradient gas distribution, the vacuum sealing quality is guaranteed through time sequence interlocking, and the operation reliability is guaranteed through a millisecond-level safety mechanism.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor single crystal preparation technology, specifically relating to an automatic oxyhydrogen flame sealing method for quartz tubes and tube caps based on multi-degree-of-freedom collaborative control. Background Technology

[0002] Quartz tubes and caps, serving as sealed containers for the preparation of indium phosphide single crystals, function to hold polycrystalline raw materials in a vacuum environment and withstand temperatures above 1600℃, enabling the indium phosphide material to complete its single-crystal transformation. In practical applications, the quartz tubes and caps must create a vacuum seal after being filled with polycrystalline indium phosphide, with a leakage rate below 10⁻⁹ Pascals per second; otherwise, crystal oxidation defects will occur. Traditional manual sealing welding has three major drawbacks: First, the process is highly volatile; when operators adjust the oxyhydrogen flame based on experience, the weld width deviation can reach ±2 mm, and the temperature field uniformity cannot exceed ±50℃, resulting in a batch product qualification rate of only 75% to 80%. Second, it is inefficient, with a single welding session taking 35 to 45 minutes, requiring the vacuum pump to operate continuously, leading to excessive energy consumption. Finally, it poses significant safety hazards; industry data from the past three years shows that the annual incidence of oxyhydrogen flame backfire accidents exceeds 0.6%.

[0003] In existing technologies, some automated solutions employ a five-axis robotic arm in conjunction with a fixed welding torch, for example, reducing welding time to 25 minutes and minimizing temperature deviation to ±15°C through programmed control. While these solutions partially address the efficiency issue, they expose three new drawbacks: First, insufficient adaptability to curved surfaces; rigid welding torches result in incomplete welds in areas with a curvature radius of less than 80 mm for quartz tubes and caps, with weld thickness differences exceeding 0.1 mm. Second, insufficient temperature control precision; open-loop control leads to a 12% thermal stress cracking rate in quartz materials above 1300°C. Third, poor process coordination; a time difference of more than 30 seconds between the vacuum unit and welding start-up increases the risk of cavity contamination by 28%.

[0004] The aforementioned deficiencies give rise to four key technical challenges that this method needs to overcome: how to achieve curvature-adaptive welding to ensure a thickness error of no more than 0.05 mm; how to establish a dynamic temperature control system with a range of ±3°C; how to reduce the vacuum welding connection time to within 8 seconds; and how to control the total operation time to less than 18 minutes. Solving these problems is directly related to core technical features such as four-degree-of-freedom positioning, dual-ring gradient gas distribution, and seven-parameter temperature control. Therefore, it is necessary to design an automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, an automatic hydrogen-oxygen flame sealing method for quartz tubes and tube caps based on multi-degree-of-freedom collaborative control is provided.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An automated oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control, the method comprising the following steps: S1 Vacuum preparation: The quartz tube and cap loaded with indium phosphide polycrystalline material are fixed on the positioning platform and vacuum is applied; S2 Collaborative Positioning: Laser scanning acquires the three-dimensional coordinates of the quartz tube and its cap, generating a 7-axis robotic arm path with a fitting error ≤0.05mm; S3 Preheating stage: Move the double 8-nozzle welding torch at 2.5-3.5 mm / s, introduce H2 at 2.0-3.0 L / min and O2 at 1.0-1.5 L / min, and heat to 550-650℃ for 2-4 min; S4 Sealing Stage: After heating, maintain constant temperature; circumferential speed of the robotic arm: 0.8-1.2 rad / s. S5 Slow Cooling Stage: Control parameters are: H2 1.2-1.8L / min and O2 0.6-1.0L / min, cooling to 700℃ at a rate of 40-60℃ / min, with a moving speed of 8-12 mm / s; S6 Airtightness Test: Fill with 0.6-0.8 MPa helium, maintain pressure for 6-10 hours, and then test for leak rate. Standard ≤5×10⁻¹ 0 Pa·m³ / s.

[0007] In the S1 vacuum preparation, the vacuum level is 3 × 10⁻ 4 Up to 8×10⁻ 4 Pa.

[0008] The S4 sealing stage includes the following two stages: S4.1 Heating section: H2 increases to 3.5-4.5 L / min, O2 to 1.6-2.0 L / min, heating to 1250-1350 ℃ at 15-20 ℃ / s; S4.2 Constant temperature zone: Adjust H2 to 5.0-6.0 L / min and O2 to 2.2-2.6 L / min, and maintain 1300-1400℃ for 3-5 minutes.

[0009] In S2 cooperative positioning, the Z-axis is raised / lowered by 0-300 mm / ±0.05 mm, the Y-axis is translated by 0-200 mm / ±0.03 mm, the θ-axis is rotated by 0-360° / ±0.1°, and the ψ-axis is tilted from -15° to +15°.

[0010] During the S3 preheating stage, the dual 8-nozzle welding torch is configured as follows: a double concentric circle layout with 16 nozzles, an inner ring H2:O2 mass ratio of 105-110:50, an outer ring H2:O2 mass ratio of 112-118:47, and a nozzle axis angle of 25°-45° with the normal.

[0011] During the S3 preheating stage, the dual 8-nozzle welding torch is 8-12 mm away from the surface of the quartz tube and the cap.

[0012] The method also includes the following safety mechanism: when ΔP(H2-O2) > 0.15-0.25MPa or temperature change rate > 30℃ / ms, a 0.08s-level cutoff is triggered.

[0013] The S5 slow cooling stage is divided into two phases: cooling at 60℃ / min in the 1000-800℃ range and cooling at 40℃ / min in the 800-700℃ range.

[0014] Over-temperature protection is performed during the S4 sealing stage: when the temperature exceeds 1400 ℃, H2 is cut off and O2 is increased, so that the ratio of the two is 1:1.5.

[0015] The time required for each step is as follows: S1 takes 3-5 minutes, S2-S5 take a total of 14-16 minutes, and S6 is timed independently.

[0016] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention utilizes the pose adjustment function of a four-degree-of-freedom positioning platform, combined with the motion path generated by laser scanning, to precisely match the nozzle axis of the dual eight-nozzle welding torch with the normal direction of the curved surface of the quartz tube and cap. This dynamic pose compensation mechanism ensures that the distance between the welding torch and the surface of the quartz tube and cap remains constant in the curvature variation region, thus solving the problem of weld thickness uniformity.

[0017] 2. This invention employs a differentiated gas distribution strategy with a dual concentric circle nozzle layout. The inner ring nozzle creates an antioxidant environment with a hydrogen-to-oxygen ratio of 105 to 110 parts by mass, while the outer ring nozzle maintains a high-temperature field with a hydrogen-to-oxygen ratio of 112 to 118 parts by mass. This zoned gas supply design achieves a balance between thermal stability and explosion-proof safety through regional control of the hydrogen-oxygen chemical reaction.

[0018] 3. The phased temperature control program established in this invention uses a hydrogen-to-oxygen ratio of 2.0 to 3.0 liters per minute and 1.0 to 1.5 liters per minute to form a base thermal field of 550 to 650 degrees Celsius during the preheating stage. During the sealing stage, a linear heating phase of 15 to 20 degrees Celsius per second is followed by a high-temperature maintenance phase of 3 to 5 minutes, combined with a gradient cooling phase of 40 to 60 degrees Celsius per minute, forming a complete thermal process control chain. This time-sequential temperature management effectively suppresses sudden changes in thermal stress in quartz materials.

[0019] 4. This invention directly links the vacuum pressure sensor with the welding process, initiating the welding torch ignition procedure within 8 seconds when the detected vacuum level reaches 5 x 10⁻⁴ Pascals. This timing mechanism minimizes the cavity exposure time, ensuring semiconductor-grade cleanroom requirements.

[0020] 5. The safety monitoring mechanism of this invention cuts off the gas supply within 0.08 seconds when the pressure difference between hydrogen and oxygen exceeds 0.15 to 0.25 MPa or the temperature change rate is greater than 30 degrees Celsius per millisecond. This dual-criteria rapid response system provides safety assurance for high-temperature and high-pressure operating conditions.

[0021] 6. The staged cooling strategy employed in the slow cooling phase of this invention performs rapid cooling at 60 degrees Celsius per minute in the 1000-800 degree Celsius range, and switches to slow cooling at 40 degrees Celsius per minute in the 800-700 degree Celsius range. This non-linear cooling mode conforms to the thermodynamic properties of quartz materials and avoids the accumulation of residual stress. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The technical solution of this application is as follows: An automated oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control, the method comprising the following steps: S1 Vacuum preparation: The quartz tube and cap loaded with indium phosphide polycrystalline material are fixed on the positioning platform and vacuum is applied; S2 Collaborative Positioning: Laser scanning acquires the three-dimensional coordinates of the quartz tube and its cap, generating a 7-axis robotic arm path with a fitting error ≤0.05mm; S3 Preheating stage: Move the double 8-nozzle welding torch at 2.5-3.5 mm / s, introduce H2 at 2.0-3.0 L / min and O2 at 1.0-1.5 L / min, and heat to 550-650℃ for 2-4 min; S4 Sealing Stage: After heating, maintain constant temperature; circumferential speed of the robotic arm: 0.8-1.2 rad / s. S5 Slow Cooling Stage: Control parameters are: H2 1.2-1.8L / min and O2 0.6-1.0L / min, cooling to 700℃ at a rate of 40-60℃ / min, with a moving speed of 8-12 mm / s; S6 Airtightness Test: Fill with 0.6-0.8 MPa helium, maintain pressure for 6-10 hours, and then test for leak rate. Standard ≤5×10⁻¹ 0 Pa·m³ / s.

[0024] In the S1 vacuum preparation, the vacuum level is 3 × 10⁻ 4 Up to 8×10⁻ 4 Pa.

[0025] The S4 sealing stage includes the following two stages: S4.1 Heating section: H2 increases to 3.5-4.5 L / min, O2 to 1.6-2.0 L / min, heating to 1250-1350 ℃ at 15-20 ℃ / s; S4.2 Constant temperature zone: Adjust H2 to 5.0-6.0 L / min and O2 to 2.2-2.6 L / min, and maintain 1300-1400℃ for 3-5 minutes.

[0026] In S2 cooperative positioning, the Z-axis is raised / lowered by 0-300 mm / ±0.05 mm, the Y-axis is translated by 0-200 mm / ±0.03 mm, the θ-axis is rotated by 0-360° / ±0.1°, and the ψ-axis is tilted from -15° to +15°.

[0027] During the S3 preheating stage, the dual 8-nozzle welding torch is configured as follows: a double concentric circle layout with 16 nozzles, an inner ring H2:O2 mass ratio of 105-110:50, an outer ring H2:O2 mass ratio of 112-118:47, and a nozzle axis angle of 25°-45° with the normal.

[0028] During the S3 preheating stage, the dual 8-nozzle welding torch is 8-12 mm away from the surface of the quartz tube and the cap.

[0029] The method also includes the following safety mechanism: when ΔP(H2-O2) > 0.15-0.25MPa or temperature change rate > 30℃ / ms, a 0.08s-level cutoff is triggered.

[0030] The S5 slow cooling stage is divided into two phases: cooling at 60℃ / min in the 1000-800℃ range and cooling at 40℃ / min in the 800-700℃ range.

[0031] Over-temperature protection is performed during the S4 sealing stage: when the temperature exceeds 1400 ℃, H2 is cut off and O2 is increased, so that the ratio of the two is 1:1.5.

[0032] The time required for each step is as follows: S1 takes 3-5 minutes, S2-S5 take a total of 14-16 minutes, and S6 is timed independently.

[0033] This invention achieves adaptive welding of quartz tubes and caps on curved surfaces through four-degree-of-freedom dynamic pose compensation. Combined with a dual-ring gradient gas distribution strategy, it simultaneously improves thermal stability and explosion-proof safety. A multi-stage temperature control model precisely manages the welding thermal process, and a vacuum-welding timing interlock mechanism ensures a semiconductor-grade clean environment. Ultimately, under a millisecond-level safety protection system, it achieves thickness deviation ≤0.04mm, temperature fluctuation ±4℃, and leakage rate ≤5×10⁻¹. 0 With a high-quality seal of Pa·m³ / s, the overall operating efficiency is improved by more than 50% compared with traditional processes.

[0034] The technical effects of the present invention are described in detail below with reference to embodiments and comparative examples. The comparative examples are verified by comparing the same test methods. The equipment used includes: a four-degree-of-freedom positioning platform (Z / Y / θ / ψ axes), a seven-axis robotic arm, a double concentric circle 16-nozzle oxyhydrogen flame welding torch, a multispectral thermometer, and a helium mass spectrometer leak detector. Example 1

[0035] The vacuum preparation step involves fixing the quartz tube containing indium phosphide polycrystalline material and its cap, and then evacuating to a vacuum level of 8×10⁻⁻⁻⁶. 4Pa. In the collaborative positioning phase, a robotic arm path is generated via laser scanning, with Z-axis lifting accuracy of +0.05mm (300mm), Y-axis translation accuracy of -0.03mm (100mm), θ-axis rotation accuracy of +0.1° (180°), and ψ-axis tilt accuracy of +15°. In the preheating phase, a dual 8-nozzle welding torch is positioned 12mm from the surface of the quartz tube and cap, moving at a speed of 2.5mm / s, while hydrogen (3.0L / min) and oxygen (1.0L / min) are introduced, raising the temperature to 650℃ and holding for 2 minutes. In the sealing phase, the heating stage involves: hydrogen (4.5L / min), oxygen (1.6L / min), raising the temperature to 1350℃ at 20℃ / s; the isothermal stage involves: hydrogen (5.0L / min), oxygen (2.6L / min), maintaining the temperature at 1400℃ for 3 minutes, with the robotic arm's circumferential speed at 0.8rad / s. During the slow cooling phase, hydrogen (1.2 L / min) and oxygen (1.0 L / min) were introduced at a moving speed of 12 mm / s, with a two-stage cooling rate of 60 °C / min: 60 °C / min in the 1000-800 °C range and 40 °C / min in the 800-700 °C range. For airtightness testing, helium was introduced at 0.8 MPa and maintained at that pressure for 6 hours. Example 2

[0036] In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows: Vacuum up to 3×10⁻ 4 Pa. Cooperative positioning settings: Z-axis lifting 0mm accuracy -0.05mm, Y-axis translation 200mm accuracy +0.03mm, θ-axis rotation 0° accuracy -0.1°, ψ-axis tilt -15°. Preheating stage: Welding torch 8mm from surface, moving at 3.5mm / s, with hydrogen 2.0L / min and oxygen 1.5L / min, heating to 550℃ and holding for 4min. Sealing stage: Heating phase: hydrogen 3.5L / min, oxygen 2.0L / min, heating to 1250℃ at 15℃ / s; Isothermal phase: hydrogen 6.0L / min, oxygen 2.2L / min, maintaining 1300℃ for 5min, circumferential speed 1.2rad / s. Slow cooling stage: moving speed 8mm / s, hydrogen 1.8L / min and oxygen 0.6L / min, cooling in stages at 40℃ / min. Air tightness test: filled with 0.6MPa helium and held for 10h. Example 3

[0037] In this embodiment, the similarities to those in Embodiment 1 will not be repeated, and the differences are as follows: Vacuum up to 5.5×10⁻ 4Pa. Cooperative positioning settings: Z-axis lifting 150mm accuracy ±0.02mm, Y-axis translation 100mm accuracy ±0.01mm, θ-axis rotation 90° accuracy ±0.05°, ψ-axis tilt angle 0°. Preheating stage: Welding torch 10mm from surface, moving at 3.0mm / s, with hydrogen 2.5L / min and oxygen 1.25L / min supplied, heating to 600℃ and holding for 3min. Sealing stage: Heating phase: hydrogen 4.0L / min, oxygen 1.8L / min, heating to 1300℃ at 17.5℃ / s; Isotherm phase: hydrogen 5.5L / min, oxygen 2.4L / min, maintaining 1350℃ for 4min, circumferential speed 1.0rad / s. Slow cooling stage: moving speed 10mm / s, hydrogen 1.5L / min and oxygen 0.8L / min, cooling in stages at 50℃ / min. For airtightness testing, fill with 0.7MPa helium and maintain pressure for 8 hours. Comparative Example 1

[0038] In this comparative example, the similarities with Example 2 will not be repeated, and the differences are as follows: The dual-nozzle gradient gas distribution is eliminated, and the inner / outer ring is uniformly composed of 110 parts hydrogen and 50 parts oxygen. Comparative Example 2

[0039] In this comparative example, the similarities with Example 3 will not be repeated, and the differences are as follows: The tilt angle of the ψ axis is fixed at 0°. Comparative Example 3

[0040] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows: The constant temperature section eliminates the step-by-step cooling, maintaining a constant temperature of 60℃ / min throughout. Comparative Example 4

[0041] In this comparative example, the similarities with Example 3 will not be repeated, and the differences are as follows: Vacuum welding connection is delayed by 30 seconds. Comparative Example 5

[0042] In this comparative example, the similarities with Example 1 will not be repeated, and the differences are as follows: The security mechanism has a response time of 0.5 seconds. Performance Test Results and Analysis

[0043] The sealing operation was performed according to the parameters of the embodiment and the comparative example, and the results were tested. The specific test results are shown in Table 1.

[0044] As shown in Table 1, the weld thickness difference in the example group was controlled within 0.02-0.04 mm, while in Comparative Example 2, due to the elimination of ψ-axis tilt adjustment, a thickness difference of 0.12 mm appeared in the region with a radius of curvature of 60 mm. This indicates that the four-degree-of-freedom dynamic compensation mechanism solved the problem of incomplete welding in traditional rigid welding guns by matching the surface normal in real time. In particular, when intermediate parameters were used in Example 3, the 0.02 mm thickness difference was better than the technical requirement of 0.05 mm limit.

[0045] The temperature fluctuations in the example group did not exceed ±4℃, while in Comparative Example 1, the fluctuations reached ±18℃ after the gradient gas distribution was eliminated. The oxygen-rich ratio in the inner ring formed an oxide layer that suppressed tempering, while the hydrogen-rich ratio in the outer ring maintained the stability of the high-temperature field. This synergistic effect resulted in a thermal field fluctuation of only ±2℃ at 1350℃ in the isothermal section of Example 3. Compared with the single-stage cooling of Comparative Example 3, its 14.9% crack rate confirms the crucial role of staged slow cooling in eliminating thermal stress.

[0046] The leakage rate in all example groups was less than 5 × 10⁻¹ 0 Pa·m³ / s, while in Comparative Example 4, the leakage rate increased to 12.7×10⁻¹ due to a 30-second connection delay. 0 Pa·m³ / s. The vacuum pressure sensor interlocking mechanism in this embodiment enables welding initiation within 8 seconds, preventing secondary contamination of the cavity. Helium mass spectrometry analysis shows a pressure of 2.1 × 10⁻¹ in Example 3. 0 The leakage rate of Pa·m³ / s meets the requirements for indium phosphide single crystal preparation.

[0047] Table 1 Analysis of Test Results

[0048] Test results show that, although the safety response delay to 0.5 seconds in Comparative Example 5 did not significantly affect the welding quality, tempering occurred in the simulated pressure surge test. The 0.08-second cutoff mechanism in Example Group achieved a zero-accident rate through dual criteria, confirming the necessity of millisecond-level response.

[0049] The three sets of examples had an operation time of 16.5-17.2 minutes, which is more than 50% shorter than the traditional process. Example 3 with optimized parameters completed the entire process in 16.5 minutes. The design of maintaining a constant temperature for 4 minutes during the sealing stage balanced efficiency and quality, avoiding the increase in crack rate caused by excessive pursuit of speed in Comparative Example 3.

[0050] This invention solves the welding problem of curved surfaces of quartz tubes and caps through four-degree-of-freedom dynamic compensation, achieves stable control of the thermal field through gradient gas distribution, ensures vacuum sealing quality through time-sequence interlocking, and ensures operational reliability through millisecond-level safety mechanisms.

[0051] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for automatic oxyhydrogen flame sealing of quartz tubes and caps based on multi-degree-of-freedom collaborative control, characterized in that, The method includes the following steps: S1 Vacuum preparation: The quartz tube and cap loaded with indium phosphide polycrystalline material are fixed on the positioning platform and vacuum is applied; S2 Collaborative Positioning: Laser scanning acquires the three-dimensional coordinates of the quartz tube and its cap, generating a 7-axis robotic arm path with a fitting error ≤0.05mm; S3 Preheating stage: Move the double 8-nozzle welding torch at 2.5-3.5 mm / s, introduce H2 at 2.0-3.0 L / min and O2 at 1.0-1.5 L / min, and heat to 550-650℃ for 2-4 min; S4 Sealing Stage: After heating, maintain constant temperature; circumferential speed of the robotic arm: 0.8-1.2 rad / s. S5 Slow Cooling Stage: Control parameters are: H2 1.2-1.8L / min and O2 0.6-1.0L / min, cooling to 700℃ at a rate of 40-60℃ / min, with a moving speed of 8-12 mm / s; S6 Airtightness Test: Fill with 0.6-0.8 MPa helium, maintain pressure for 6-10 hours, and then test for leak rate. Standard ≤5×10⁻¹ 0 Pa·m³ / s.

2. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, In the S1 vacuum preparation, the vacuum level is 3 × 10⁻ 4 Up to 8×10⁻ 4 Pa.

3. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, The S4 sealing stage includes the following two stages: S4.1 Heating section: H2 increases to 3.5-4.5 L / min, O2 to 1.6-2.0 L / min, heating to 1250-1350℃ at 15-20 ℃ / s; S4.2 Constant temperature zone: Adjust H2 to 5.0-6.0 L / min and O2 to 2.2-2.6 L / min, and maintain 1300-1400℃ for 3-5 minutes.

4. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, In S2 cooperative positioning, the Z-axis is raised / lowered by 0-300 mm / ±0.05 mm, the Y-axis is translated by 0-200 mm / ±0.03 mm, the θ-axis is rotated by 0-360° / ±0.1°, and the ψ-axis is tilted from -15° to +15°.

5. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, During the S3 preheating stage, the dual 8-nozzle welding torch is configured as follows: a double concentric circle layout with 16 nozzles, an inner ring H2:O2 mass ratio of 105-110:50, an outer ring H2:O2 mass ratio of 112-118:47, and a nozzle axis angle of 25°-45° with the normal.

6. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, During the S3 preheating stage, the dual 8-nozzle welding torch is 8-12 mm away from the surface of the quartz tube and the cap.

7. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, The method also includes the following safety mechanism: when ΔP(H2-O2) > 0.15-0.25MPa or temperature change rate > 30℃ / ms, a 0.08s-level cutoff is triggered.

8. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, The S5 slow cooling stage is divided into two phases: cooling at 60℃ / min in the 1000-800℃ range and cooling at 40℃ / min in the 800-700℃ range.

9. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, Over-temperature protection is performed during the S4 sealing stage: when the temperature exceeds 1400 ℃, H2 is cut off and O2 is increased, so that the ratio of the two is 1:1.

5.

10. The automatic oxyhydrogen flame sealing method for quartz tubes and caps based on multi-degree-of-freedom collaborative control according to claim 1, characterized in that, The time required for each step is as follows: S1 takes 3-5 minutes, S2-S5 take a total of 14-16 minutes, and S6 is timed independently.

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