A variable cross-section deposition cavity for OVD process

Abstract

This invention relates to a variable cross-section deposition chamber for OVD (Optical Vapor Deposition) processes, comprising a deposition chamber body, one end of which is connected to an air inlet chamber. A row of vertically spaced blowtorches is vertically mounted on the side of the air inlet chamber. Upper and lower rotating chucks or blowtorches are installed within the deposition chamber body and are connected to a vertical moving device. The other end of the deposition chamber body is connected to an exhaust chamber. The invention is characterized by symmetrically mounted movable baffles on the inner sides of the front and rear sidewalls of the deposition chamber body. The rear of each movable baffle is connected to a telescopic propulsion device, forming a deposition chamber with an adjustable transverse cross-section. During deposition, as the diameter of the powder rod increases, the movable baffles slowly and continuously move towards the front and rear sidewalls under the drive of the telescopic propulsion device. This maintains a relatively constant distance between the outer periphery of the powder rod and the front and rear sidewalls of the deposition chamber body, allowing the airflow to maintain its initial laminar flow state even when heat causes flow changes, reducing turbulence and thus maintaining the stability of the airflow field during deposition.

Description

Technical Field

[0001] This invention relates to a variable cross-section deposition cavity for OVD process, belonging to the technical field of optical fiber preform and optical quartz glass manufacturing equipment. Background Technology

[0002] Direct and indirect synthesis methods based on flame hydrolysis deposition are currently the mainstream technologies for large-scale industrial production of high-purity quartz glass. Outside vapor deposition (OVD), an indirect synthesis method, is mainly used to prepare cylindrical quartz glass and optical fiber preforms. In the OVD deposition process, silicon-containing raw materials are generally silicon tetrachloride (SiCl4) or organosilicon (octamethylcyclotetrasiloxane, C8H4Cl4). 24 O4Si4, D4) undergoes a hydrolysis reaction in an oxyhydrogen flame to produce silicon dioxide (SiO2) and doped SiO2 particles. The SiO2 particles are deposited layer by layer on a rotating mandrel under thermophoretic action to form a porous soot preform. Subsequently, it undergoes dehydration treatment to remove water and metal impurities, and is sintered and vitrified in a temperature range of 1100℃-1500℃ to obtain a quartz preform.

[0003] The deposition chamber is the most crucial part of the OVD (Oven Vapor Deposition) deposition equipment. The deposition reaction takes place within the chamber, which provides air intake, exhaust, and a high-temperature combustion field for the deposition process. It also provides a suitable flow field for torch deposition within a complex fluid environment, ensuring the continuous deposition reaction and yielding qualified powder rods. Therefore, the performance of the deposition chamber directly affects the shape, density, and collection rate of the powder rods, and is a key factor in determining the sophistication of OVD deposition equipment. Most existing deposition chambers have a fixed rectangular cross-section in the transverse direction and a uniform cross-section in the longitudinal direction, meaning the gas flow area is equal from the air intake chamber to the exhaust chamber, and the airflow velocity entering the chamber is consistent throughout. As deposition and combustion continue, the temperature inside the chamber rises, and the outer diameter of the precast powder rods increases, ranging from an initial Φ40mm to Φ800mm. This increase in diameter reduces the gas flow cross-section, leading to a decrease in airflow and preventing timely dust removal, causing turbulence. Simultaneously, the upward movement of heat due to air convection creates temperature unevenness between the deposition area and the top and bottom of the precast powder rods, generating turbulence even within the negative pressure deposition chamber. These temperature and airflow variations directly affect the temperature gradient distribution and airflow stability during deposition, resulting in a reduced powder rod deposition rate, uneven deposition, and a decline in deposition quality. This phenomenon is particularly pronounced when depositing large-diameter powder rods. To address these issues, deposition chambers with larger cross-sectional widths are commonly used. While this alleviates the problems, issues remain, such as excessive initial airflow, significant differences in the gas flow area before and after deposition, and poor temperature gradient distribution and airflow stability during the deposition process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a variable cross-section deposition cavity for OVD process that addresses the shortcomings of the prior art. It can maintain the stability of the gas flow field during the deposition process, save energy and reduce emissions, and improve deposition quality and efficiency.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows: it includes a deposition chamber, one end of which is connected to an air inlet chamber, a row of vertically spaced blowtorches is vertically installed on the side of the air inlet chamber, upper and lower rotating clamps are installed in the deposition chamber, the upper and lower rotating clamps or blowtorches are connected to an upper and lower moving device, and the other end of the deposition chamber is connected to an exhaust chamber. The feature is that movable partitions are symmetrically installed on the inner sides of the front and rear side walls of the deposition chamber, and the rear of the movable partitions is connected to a telescopic propulsion device, thus forming a deposition chamber with an adjustable transverse cross-section.

[0006] According to the above scheme, the width of the movable partition is the same as or substantially the same as the width of the front and rear side walls, and the height of the movable partition is greater than or equal to the effective length of the deposition powder rod.

[0007] According to the above scheme, the transverse cross-section of the deposition cavity is rectangular.

[0008] According to the above scheme, the front and rear sidewalls of the deposition chamber extend inward from one end of the air inlet chamber to a section of the air outlet chamber, and the transverse cross-section is an isosceles trapezoid shape.

[0009] According to the above scheme, the angle between the front and rear sidewalls of the deposition chamber and the center line of the transverse section of the deposition chamber is 10 to 20°, and the two movable partitions are arranged parallel to the front and rear sidewalls.

[0010] According to the above scheme, the telescopic propulsion device is a translational telescopic propulsion device.

[0011] According to the above scheme, the translational telescopic propulsion device includes a rhomboid telescopic frame and a telescopic drive cylinder or air cylinder connected to one end of the rhomboid telescopic frame, and the other end of the rhomboid telescopic frame is hinged to a movable partition.

[0012] According to the above scheme, the blowtorch is connected to the front and rear moving device.

[0013] According to the above scheme, during the deposition of the movable partition, as the diameter of the powder rod increases, it moves slowly and continuously to both sides of the front and rear side walls under the drive of the translation and telescopic propulsion device. That is, the distance between the front and rear movable partitions increases as the diameter of the powder rod increases, so that the distance between the outer periphery of the powder rod and the front and rear side walls of the deposition chamber is greater than or equal to G, where G is 175mm to 500mm.

[0014] According to the above scheme, the air inlet cavity is located on one side of the back of the blowtorch, the front of the air inlet cavity is connected to the deposition cavity, and the rear of the air inlet cavity is connected to the upper and lower separated sub-air inlet cavities.

[0015] According to the above scheme, the exhaust chamber is located on the front side of the blowtorch. The front of the exhaust chamber is connected to the deposition chamber. The rear of the exhaust chamber is connected to the upper and lower separated sub-exhaust chambers. Each sub-exhaust chamber has an air volume regulating valve connected in series at its air outlet to regulate the flow rate of the extracted gas. The air outlet of each sub-exhaust chamber is connected to the exhaust pipe.

[0016] According to the above scheme, the sub-air inlet cavity is arranged in 6 to 12 layers above and below the air inlet cavity, and each layer is divided into 2 to 4 compartments. The sub-exhaust cavity is arranged in 6 to 12 layers above and below the exhaust cavity, and each layer is divided into 2 to 4 compartments.

[0017] The beneficial effects of this invention are as follows: 1. Movable baffles are provided on the front and rear sidewalls of the deposition chamber, forming a deposition chamber with an adjustable transverse cross-section. During deposition, as the diameter of the powder rod increases, the movable baffles move slowly and continuously to both sides of the front and rear sidewalls under the drive of the translational telescopic propulsion device. That is, the distance between the front and rear movable baffles increases with the increase of the powder rod diameter, so that the distance between the outer periphery of the powder rod and the front and rear sidewalls of the deposition chamber remains relatively constant. Since the transverse cross-section of the deposition chamber increases continuously and slowly, and the distance between the outer periphery of the powder rod and the front and rear sidewalls of the deposition chamber remains relatively constant, the airflow in the deposition chamber maintains a slow flow rate increase. This allows the airflow to maintain its initial laminar state even when the flow changes caused by rising heat, reducing the generation of turbulence and thus maintaining the stability of the airflow field during the deposition process. 2. The setting of the translational telescopic propulsion device facilitates the automated synchronous control of the movable baffles, ensuring the consistency of the deposition process to the greatest extent, ensuring the smooth flow of the extraction airflow and the stability of the deposition state, and improving the deposition quality and efficiency. 3. The sub-inlet and sub-exhaust chambers facilitate gradient adjustment of the inlet and exhaust volumes, allowing for regional adjustment of the inlet and exhaust volumes. This maximizes adjustment methods, reduces the negative impact of the thermal field, improves the flow field environment, and provides conditions for achieving a uniform laminar flow field. 4. Movable baffles are installed in the deposition chamber, with front and rear ventilation to cool the baffles, enabling them to operate normally at high temperatures and reducing deformation. 5. This invention has a simple and reasonable structure, low manufacturing cost, and is easy to implement, making it particularly suitable for the deposition of large-diameter preforms. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of an embodiment of the present invention.

[0019] Figure 2 This is a cross-sectional view of the deposition process in one embodiment of the present invention.

[0020] Figure 3 This is a longitudinal cross-sectional view of an embodiment of the present invention.

[0021] Figure 4 This is a cross-sectional view of a longitudinal section in another direction according to an embodiment of the present invention.

[0022] Figure 5 This is a front sectional view of an embodiment of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Example 1: The system includes a deposition chamber with a rectangular cross-section. Movable partitions 2 are symmetrically installed on the inner sides of the front and rear sidewalls 5 of the deposition chamber. These partitions are parallel to each other and parallel to the front and rear sidewalls. The rear of each partition is connected to a telescopic propulsion device 3. The width of each partition is approximately the same as the width of the front and rear sidewalls, with a slight gap. The height of each partition is greater than the effective length of the deposition powder rod. The telescopic propulsion device is a translational telescopic propulsion device, comprising a rhomboid telescopic frame. One end of the rhomboid telescopic frame extends beyond the front or rear sidewall and is hinged to a telescopic cylinder. The front section is hinged to the front and rear sidewalls. The other end of the rhomboid telescopic frame is hinged to the rear of the movable partition, thus forming a deposition chamber with an adjustable cross-section. Two translational telescopic propulsion devices are arranged on the left and right sides, extending and retracting synchronously. One end of the deposition chamber is connected to the air inlet chamber 1, which is located on the back side of the blowtorch. The front of the air inlet chamber is connected to the deposition chamber, and the rear of the air inlet chamber is connected to the upper and lower divided sub-air inlet chambers. The sub-air inlet chambers are arranged in 8 layers corresponding to the air inlet chamber, each layer is divided into 4 compartments, including left and right compartments 9 and two middle compartments 10, forming sub-air inlet chambers A1 to A8 on the left, D1 to D8 on the right, and B1 to B8 and C1 to C8 in the middle. A row of blowtorches 7 with upper and lower intervals is vertically installed in the middle of the air inlet chamber side. The blowtorches are connected to the upper and lower moving device through the blowtorch holder 8, and are also connected to the front and rear moving device. Upper and lower rotating clamping plates are installed in the middle of the deposition chamber. The upper and lower rotating clamping plates include upper and lower clamping plates 13 and connected to them. The drive shaft 16 is connected to the drive device 14 via the bearing seat 15, driving the upper and lower chucks to rotate. The upper and lower rotating chucks are used to hold the deposition target rod. The other end of the deposition chamber is connected to the exhaust chamber 6. The exhaust chamber is located on the front side of the blowtorch. The front of the exhaust chamber is connected to the deposition chamber. The rear of the exhaust chamber is connected to the upper and lower separated sub-exhaust chambers. The air volume regulating valve is connected in series at the air outlet of each sub-exhaust chamber for regulating the flow rate of the extracted gas. The air outlet of the sub-exhaust chamber is connected to the exhaust pipe. The sub-exhaust chambers are arranged in 8 layers above and below the exhaust chamber. Each layer is divided into 3 compartments, including left and right compartments 11 and middle compartments 12, forming left L1 to L8 sub-air inlet chambers, right R1 to R8 sub-air inlet chambers, and middle M1 to M8 sub-air inlet chambers. During deposition, the movable partition moves slowly and continuously to both sides of the front and rear sidewalls under the drive of the translational telescopic propulsion device as the diameter of the powder rod 4 increases. That is, the distance between the front and rear movable partitions increases as the diameter of the powder rod increases, so that the distance between the outer periphery of the powder rod and the front and rear sidewalls of the deposition chamber is greater than or equal to G. G is the optimal single-side deposition interval, ranging from 175mm to 500mm, and usually from 200mm to 350mm.

[0025] Example 2: The main difference in the second embodiment of the present invention is that the front and rear sidewalls of the deposition chamber extend inward from one end of the air inlet chamber to the exhaust chamber, with a transverse cross-section in the shape of an isosceles trapezoid. The angle between the front and rear sidewalls of the deposition chamber and one side of the center line of the transverse cross-section of the deposition chamber is 10-20°, and the two movable partitions are arranged parallel to the front and rear sidewalls. The rest of the structure is basically the same as the first embodiment.

Claims

1. A variable cross-section deposition chamber for OVD process, comprising a deposition chamber body, one end of which is connected to an air inlet chamber, a row of vertically spaced blowtorches vertically mounted on the side of the air inlet chamber, upper and lower rotating chucks or blowtorches mounted in the deposition chamber body, the upper and lower rotating chucks or blowtorches being connected to an up-and-down moving device, and the other end of the deposition chamber body being connected to an exhaust chamber, characterized in that... The deposition chamber is symmetrically equipped with movable partitions on the inner sides of the front and rear side walls. The rear of the movable partitions is connected to the telescopic propulsion device to form a deposition chamber with an adjustable transverse cross-section. The width of the movable partitions is the same as the width of the front and rear side walls, and the height of the movable partitions is greater than or equal to the effective length of the deposition powder rod. The telescopic propulsion device is a translational telescopic propulsion device.

2. The variable cross-section deposition cavity for OVD process according to claim 1, characterized in that... The deposition cavity has a rectangular cross-section.

3. The variable cross-section deposition cavity for OVD process according to claim 1, characterized in that... The front and rear sidewalls of the deposition chamber extend inward from one end of the air inlet chamber to one end of the air outlet chamber, and the transverse cross-section is an isosceles trapezoid shape.

4. The variable cross-section deposition cavity for OVD process according to claim 3, characterized in that... The angle between the front and rear sidewalls of the deposition chamber and the center line of the transverse cross section of the deposition chamber is 10~20°, and the two movable partitions are arranged parallel to the front and rear sidewalls.

5. The variable cross-section deposition cavity for OVD process according to claim 1, characterized in that... The aforementioned translational telescopic propulsion device includes a rhomboid telescopic frame and a telescopic drive hydraulic cylinder or pneumatic cylinder connected to one end of the rhomboid telescopic frame, with the other end of the rhomboid telescopic frame hinged to a movable partition.

6. The variable cross-section deposition cavity for OVD process according to claim 1 or 2, characterized in that... The blowtorch is connected to the front and rear moving device.

7. The variable cross-section deposition cavity for OVD process according to claim 1 or 2, characterized in that... During deposition, the movable partition moves slowly and continuously to both sides of the front and rear sidewalls under the drive of the translational telescopic propulsion device as the diameter of the powder rod increases. That is, the distance between the front and rear movable partitions increases as the diameter of the powder rod increases, so that the distance between the outer periphery of the powder rod and the front and rear sidewalls of the deposition chamber is greater than or equal to G, where G is 175mm~500mm.

8. The variable cross-section deposition cavity for OVD process according to claim 1 or 2, characterized in that... The air inlet chamber is located on one side of the back of the blowtorch. The front of the air inlet chamber is connected to the deposition chamber, and the rear of the air inlet chamber is connected to the upper and lower separated sub-air inlet chambers.

9. The variable cross-section deposition cavity for OVD process according to claim 8, characterized in that... The exhaust chamber is located on the front side of the blowtorch. The front of the exhaust chamber is connected to the deposition chamber. The rear of the exhaust chamber is connected to the upper and lower separated sub-exhaust chambers. Each sub-exhaust chamber has an air volume regulating valve connected in series at its air outlet to regulate the flow rate of the extracted gas. The air outlet of each sub-exhaust chamber is connected to the exhaust pipe.

10. The variable cross-section deposition cavity for OVD process according to claim 9, characterized in that... The sub-air inlet chambers are arranged in 6 to 12 layers above and below the air inlet chambers, with each layer divided into 2 to 4 compartments. The sub-exhaust chambers are arranged in 6 to 12 layers above and below the exhaust chambers, with each layer divided into 2 to 4 compartments.

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