A method for repairing a casing preform

Abstract

The present invention discloses a repair processing method for a sleeve preform rod, which includes the steps of perforating, cleaning with a water-based cleaning solution, pickling, ventilation and drying, sealing and vacuum drawing. The repair method of the present invention effectively avoids cutting off the entire melt-cone head of the sleeve, has a short operation process, and reduces the waste of raw materials. The repaired part can be used as the turning part of the subsequent secondary drawing, and does not need to be re-coned, which can save a lot of propane and oxygen costs. At the same time, it can effectively reduce the risk of bursting caused by uneven heating during the sleeve taper drawing process. In addition, the present method can also avoid the subsequent secondary assembly process of the core rod and the sleeve, and avoid the attenuation and strength problems caused by scratches and secondary pollution generated during the assembly process.

Description

Technical Field

[0001] The invention relates to a method for repairing a sleeve preform rod, and belongs to the technical field of optical fiber manufacturing. Background Art

[0002] Optical fiber, as the most important carrier for communication transmission, plays an irreplaceable role in the communications field. Optical fiber preforms are the parent material used to produce optical fibers, and their quality largely determines the quality of the fiber. Currently, the production process for optical fiber preforms primarily utilizes a two-step process: the preform is typically manufactured first, followed by the cladding. Typical outer cladding preparation techniques include external vapor deposition, the sleeve method, and plasma spraying. The sleeve method has become the mainstream production method in the market due to its advantages, such as large size and length, significantly improved production efficiency, and significant cost advantages. During the sleeve method, optical fiber production often requires repair due to material defects, dimensional variations, and improper process flow. This process typically requires cutting the melted cone, removing the sleeve and core rod for separate processing, and then re-tapering and re-tapering the sleeve. This operation often results in significant raw material loss and consumes large amounts of propane and oxygen. The tapering process can also easily cause breakage in the finished section, leading to extensive rework and repair issues, significantly increasing optical fiber production costs and reducing production efficiency. Even if the sleeve material inspection is qualified, the main reason for the unqualified optical fiber parameters is the interface contamination problem during the sleeve and core rod assembly operation. The use of conventional cutting, taper grinding, and taper pulling processes will seriously affect the production cycle, ultimately affecting the delivery time and increasing production costs. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for repairing a sleeve preform rod to solve the above technical problems.

[0004] The technical solution for achieving the purpose of the present invention is: a method for repairing a sleeve preform rod specifically comprises the following steps:

[0005] S1: Fix the repaired casing preform and drill a single-side through hole in the unmelted area of the repaired casing;

[0006] S2: Drill another single-side through hole on the opposite side of the single-side through hole to form a double-side through hole in the casing preform;

[0007] S3: Cleaning the punched casing preform in a water-based cleaning solution;

[0008] S4: performing pickling treatment on the casing preform rod that has completed the water-based cleaning;

[0009] S5: Drying the pickled casing preform: N2 is passed through to remove impurities, and then drying is performed;

[0010] S6: sealing the casing preform;

[0011] S7: The sealed casing preform tail tube is hung on a drawing tower for vacuum drawing.

[0012] This repair method uses drilling and liquid flushing methods to repair the side of the unmelted area of the repaired casing, effectively avoiding the removal of the entire melted cone head of the casing. The operation process is short and the waste of raw materials is small. The repaired part can be used as the turning part of the subsequent secondary wire drawing. It does not need to be re-tapered, which can save a lot of propane and oxygen costs. At the same time, it can effectively reduce the risk of bursting caused by uneven heating during the taper drawing process of the casing. In addition, this method can also avoid the subsequent secondary assembly process of the core rod and the casing, avoiding the attenuation problem caused by scratches and secondary contamination generated during the assembly process.

[0013] Further or optionally, in order to match the size of the preform rod in the production process and prevent the optical fiber preform rod from breaking during the drilling process, the diameter of the drill bit in step S1 is 5-10 mm.

[0014] Further or optionally, in order to improve the cleaning efficiency and reduce cleaning residues, an ultrasonic cleaning device is used in the water washing process in step S3, and the concentration of the water-based cleaning solution is 1-2%.

[0015] Further or optionally, in order to control the amount of sleeve corrosion and the optical parameters of the finished optical fiber, the acid solution in the pickling process in step S4 is 20%-30% HF acid or 20%-30% HF acid and 2%-5% HNO3 to form a mixed acid solution, and the sleeve corrosion amount is 0.4-0.8mm. Within this corrosion range, the early contamination on the core rod surface can be effectively removed, and impurity particles and metal ions can be prevented from diffusing into the core rod during the subsequent firing process. Under the premise of ensuring that the internal radius of the core rod does not change drastically, the optical performance of the finished product after drawing is met.

[0016] Further or optionally, in order to prevent water vapor from causing attenuation and strength performance of optical fiber drawing, during the drying process in step S5, dry N2 gas enters the inner wall of the sleeve from the tail pipe and flows out from the hole punched at the sleeve cone head, and the drying time is 36~48h.

[0017] Further or optionally, in order to improve the vacuuming efficiency and further improve the internal cleanliness and reduce the residual water vapor, clean N2 gas needs to be introduced during the sealing process in step S5 to prevent the internal water vapor from remaining during the sealing; in step S6, the vacuum drawing process uses a vacuum device to check the sealing of the sleeve, and the negative pressure is controlled to -0.1MPa.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects:

[0019] The optical fiber preform cleaning method of the present invention uses drilling and liquid flushing methods to perform repair on the side of the unmelted area of the repair sleeve, effectively avoiding the removal of the entire melted cone head of the sleeve, and the operation process is short, with less waste of raw materials. The repaired part can be used as the turning part of the subsequent secondary drawing, and it does not need to be re-tapered, which can save a lot of propane and oxygen costs, and can effectively reduce the risk of explosion caused by uneven heating during the tapering process of the sleeve; in addition, the use of this method can also avoid the subsequent secondary assembly process of the core rod and the sleeve, avoiding the attenuation problem caused by scratches and secondary contamination generated during the assembly process.

[0020] The optical fiber preform repair method of the present invention limits the drill bit size to 5-10 mm, effectively avoiding the problem of preform bursting caused by an oversized drill bit.

[0021] The present invention adopts ultrasonic cleaning equipment for cleaning and limits the concentration of water-based cleaning liquid to 1-2%. It has high cleaning efficiency, less residue and little effect on optical fiber parameters.

[0022] The present invention limits the acid solution composition and the amount of casing corrosion, and effectively controls the optical parameters of the finished optical fiber by limiting these parameters. Compared with other cleaning methods, the quality of the finished optical fiber is more stable.

[0023] The optical fiber preform of the present invention is dried using N2 and the ventilation time is controlled, and a subsequent drying treatment is performed, which can effectively prevent moisture from entering the preform and prevent the drawing process from affecting the attenuation performance and strength performance of the optical fiber.

[0024] The present invention performs negative pressure vacuuming during the sealing process, which can further prevent water vapor from remaining and improve the cleanliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein

[0026] Figure 1 It is a schematic diagram of the process of the present invention.

[0027] Figure 2 Schematic diagram of traditional casing preform repair process.

[0028] Figure 3 This is a schematic diagram of the punching process for the sleeve preform rod repair process of the present invention.

[0029] Among them, there are 1 casing, 2 tail tubes, 3 core rods, 4 original cone heads of casing preform rods, 5 cone heads of casing preform rods repaired for secondary taper drawing, and 6 side holes. DETAILED DESCRIPTION

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0032] All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work shall fall within the scope of protection of the present invention.

[0033] (Example 1)

[0034] See Figure 1 In this embodiment, a method for repairing a sleeve preform is provided, comprising the following steps:

[0035] S1. Place the repaired casing preform 1 on a drilling lathe, select a drill bit with a suitable diameter, align it with the side of the unmelted area of the repaired casing preform 1, and drill until a hole is formed on one side;

[0036] Furthermore, the symmetrical side surfaces of the hole in the sleeve preform 1 are also drilled to form a double hole through-hole;

[0037] Furthermore, the drill bit has a diameter of φ5-10 mm;

[0038] S2. Place the casing preform 1 in an ultrasonic cleaning device for cleaning to remove impurities and oil stains inside and outside the casing preform 1;

[0039] Furthermore, the ultrasonic cleaning equipment is configured with a water-based cleaning solution with a concentration of 1-2%;

[0040] S3, placing the casing preform rod 1 in an acid washing device for acid treatment to remove metal particle impurities;

[0041] Furthermore, the acid solution is configured with 20%-30% concentration of HF acid or 2%-5% HNO3 is added to form a mixed acid solution;

[0042] Furthermore, the corrosion amount of the sleeve preform rod 1 during acid treatment is 0.4-0.8 mm;

[0043] S4, drying the casing preform rod 1 by introducing clean N2 from the tail pipe into the inner wall of the casing and flowing out from the holes on the side of the casing preform rod to form a passage;

[0044] Furthermore, the drying time of the sleeve preform 1 is 36-48 hours to ensure that all the water vapor in the inner hole of the sleeve preform 1 is exhausted;

[0045] S5. The dried casing preform rod 1 is sealed by melting a clean quartz mandrel with an oxyhydrogen flame lamp to block the hole punched by the casing cone head;

[0046] Furthermore, clean N2 can also be introduced into the tail pipe during the sealing process to prevent water vapor from appearing in the inner hole of the casing preform rod 1 during the sealing process;

[0047] Furthermore, the sealing performance of the casing seal was checked using a vacuum device, with the negative pressure reaching -0.1 MPa;

[0048] S6. The sealed casing preform rod 1 is directly hung on the drawing tower, and the tail tube is vacuumed and drawn normally.

[0049] It should be understood that the present invention is described by way of certain embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A method for repairing a casing preform, comprising the following steps: S1: Fix the repaired casing preform and drill a single-side through hole in the unmelted area of the repaired tube; then drill another single-side through hole on the opposite side of the single-side through hole to form a double-side through hole in the casing preform; S2: Cleaning the punched casing preform in a water-based cleaning solution; S3: performing pickling treatment on the casing preform rod that has completed water-based cleaning; S4: Drying the pickled casing preform: N2 is passed through to remove impurities, and then drying is performed; S5: sealing the casing preform; S6: The sealed casing preform tail tube is hung on a drawing tower for vacuum drawing.

2. The method for repairing a sleeve preform according to claim 1, wherein: In step S1, the diameter of the drill bit is 5-10 mm.

3. The method for repairing a sleeve preform according to claim 1, wherein: In the water washing process in step S2, ultrasonic cleaning equipment is used, and the concentration of the water-based cleaning solution is 1-2%.

4. The method for repairing a sleeve preform according to claim 1, wherein: In the pickling process in step S3, the acid solution is 20%-30% HF acid or a mixed acid solution of 20%-30% HF acid and 2%-5% HNO3, and the casing corrosion amount is 0.4-0.8mm.

5. The method for repairing a sleeve preform according to claim 1, wherein: During the drying process in step S4, dry N2 gas enters the inner wall of the casing from the tail pipe and flows out from the holes punched at the casing cone head. The drying time is 36 to 48 hours.

6. The method for repairing a sleeve preform according to claim 1, wherein: In the sealing process of step S5, clean N2 gas needs to be introduced to prevent internal water vapor from remaining during sealing; in the vacuum drawing process of step S6, a vacuum device is used to check the sealing of the sleeve, and the negative pressure is controlled to -0.1 MPa.

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