JP2018172229A - Manufacturing device and manufacturing method of optical fiber porous preform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing device which suppresses a circulation flow of a gas in a reaction chamber, which reduces the amount of glass fine particles adhered to a wall surface in the reaction chamber, and which reduces generation of cracks in an optical fiber porous preform and generation of air bubbles in an optical fiber preform in which the optical fiber porous preform is vitrified.SOLUTION: A manufacturing device for optical fiber porous preform includes a reaction chamber 11, burners 14, 15 provided in the reaction chamber, and a gas supply part 17 for supplying a gas including a raw material gas and a combustible gas to the burners. In the reaction chamber 11, the gas is supplied from the burners to a starting material, fine particles generated by the reaction of the gas are accumulated on the outer periphery of the starting material and a porous preform 2 is formed. A partition plate 12 through which the porous preform can pass is provided in the reaction chamber 11. The inside of the reaction chamber is substantially partitioned by the partition plate into a reaction chamber 11A in which the burners exist and a reaction chamber 11B in which they do not exist, and a first exhaust part 21 and a second exhaust part 22 which can control an exhaust flow rate are provided in the reaction chamber where the burners exist and the reaction chamber where the burners do not exist respectively.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber porous preform manufacturing apparatus and manufacturing method.

  In general, a silica glass-based optical fiber is manufactured by drawing an optical fiber glass preform (hereinafter also referred to as an optical fiber preform) made of quartz glass. The optical fiber preform is manufactured by depositing glass fine particles on the outer periphery of a target (starting material) to form a porous layer, and then dehydrating and sintering the porous layer to vitrify it. The optical fiber preform is manufactured by a known method such as a VAD (Vapor Phase Axial Deposition) method, an MCVD (Modified Chemical Vapor Deposition) method, or an OVD (Outside Vapor Deposition) method.

  Among these, in the VAD method, glass particles generated by introducing a combustible gas, an auxiliary combustion gas, and a glass raw material into a burner for synthesizing glass particles and subjecting them to a flame hydrolysis reaction are used to rotate the target (starting material). An optical fiber porous base material (hereinafter also referred to as a porous base material) that is the base of the optical fiber base material is manufactured by being deposited in the direction of the rotation axis. The porous preform is further vitrified by a vitrification process to become an optical fiber preform.

  In Patent Document 1, in the VAD apparatus, the first to fourth horizontal partition plates arranged horizontally are used in order to maintain the flow direction of the air in the reaction chamber in the horizontal direction as much as possible while the circulation flow is generated. The structure which provides (baffle plate) is proposed. In Patent Document 2, in order to manufacture an optical fiber porous preform free of bubbles, in a VAD apparatus, a porous preform after glass fine particle deposition is placed in a round hole or cylinder having an inner diameter smaller than the maximum inner diameter in a reaction chamber. A method has been proposed in which the rising convection of the burner flame is suppressed by passing the gas through the gas.

JP 2004-161606 A JP 2001-322825 A

  However, Patent Document 1 described above describes that there is still a problem that a gas circulation flow is generated in the reaction chamber. When a circulating gas flow is generated in the reaction chamber, the generated glass particles are likely to adhere to the wall surface in the reaction chamber. When the glass fine particles adhere to the wall surface, there is a possibility that the peeled glass fine particles are reattached to the porous base material. Further, in Patent Document 2, there is a possibility that glass particles floating above the partition plate (baffle plate) accumulate on the partition plate, and the glass particles reattach to the porous base material. When such glass particles are reattached to the porous base material being manufactured, cracks may occur in the porous base material, or bubbles may be generated in the optical fiber base material obtained by vitrifying the porous base material. Is more likely to do.

  The present invention has been made in view of the above, and its object is to suppress the circulation of gas in the reaction chamber, to reduce the amount of glass particles adhering to the wall surface in the reaction chamber, and to provide a porous optical fiber porous matrix. An object of the present invention is to provide an optical fiber porous preform manufacturing apparatus and method that can reduce the occurrence of cracks in a material and the generation of bubbles in an optical fiber preform obtained by vitrifying an optical fiber porous preform.

  In order to solve the above-described problems and achieve the above object, an optical fiber porous preform manufacturing apparatus according to the present invention includes a reaction chamber, a burner provided in the reaction chamber, a raw material gas and A gas supply unit for supplying a gas containing a combustible gas, and supplying the gas from the burner to the starting material in the reaction chamber to deposit fine particles generated by the reaction of the gas on the outer periphery of the starting material. An optical fiber porous base material manufacturing apparatus for forming a porous base material, wherein a partition plate through which the porous base material can pass is provided in the reaction chamber, and the reaction chamber has the reaction chamber, The reaction chamber in which the burner is present and the reaction chamber in which the burner is not present are substantially partitioned, and the reaction chamber in which the burner is present is provided with a first exhaust unit capable of controlling the exhaust flow rate, Wherein the serial burner is the second exhaust section capable of controlling the exhaust gas flow rate is provided in a reaction chamber that does not exist.

  In the optical fiber porous preform manufacturing apparatus according to one aspect of the present invention, in the above invention, a plurality of the partition plates are provided, and the reaction chamber in which the burner does not exist is further partitioned into at least two reaction chambers. It is characterized by that.

  An optical fiber porous preform manufacturing apparatus according to an aspect of the present invention is the above-described invention, wherein the gas supply unit can introduce gas into the reaction chamber in which the burner is present and the reaction chamber in which the burner is not present. Is provided. In this configuration, an apparatus for producing an optical fiber porous preform according to an aspect of the present invention includes an air supply unit provided in a reaction chamber in which the burner exists, and a supply unit provided in a reaction chamber in which the burner does not exist. The air part is provided independently of each other.

  In the method for producing a porous base material according to one aspect of the present invention, a gas containing a raw material gas and a combustible gas is supplied from a burner to a starting material in a reaction chamber, and is generated by reaction of the gas on the outer periphery of the starting material. An optical fiber porous preform manufacturing method in which fine particles are deposited to form a porous preform, wherein the burner is present in the reaction chamber by a partition plate through which the porous preform can pass. And a reaction chamber in which the burner is present, the gas in the reaction chamber in which the burner is present is exhausted by a first exhaust unit that can control the exhaust flow rate provided in the reaction chamber in which the burner is present. In addition, the gas in the reaction chamber without the burner is exhausted by the second exhaust unit that can control the exhaust flow rate provided in the reaction chamber without the burner. To.

  According to the manufacturing apparatus and the manufacturing method of the optical fiber porous preform according to the present invention, the circulation flow of the gas in the reaction chamber can be suppressed, the amount of glass fine particles adhering to the wall surface in the reaction chamber can be reduced, and the optical fiber porous It is possible to reduce the occurrence of cracks in the base material and the generation of bubbles in the optical fiber base material obtained by vitrifying the optical fiber porous base material.

FIG. 1 is a VAD device according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiment. It should be noted that the drawings are schematic, and dimensional relationships among elements may differ from actual ones.

(Optical fiber porous preform manufacturing equipment)
First, a VAD device according to an embodiment of the present invention will be described. FIG. 1 shows a VAD device used in this embodiment.

  As shown in FIG. 1, a VAD apparatus 1 as an optical fiber porous preform manufacturing apparatus according to this embodiment includes a reaction chamber 11, a partition plate 12, burners 14 and 15, a gas supply unit 17, and a control unit 18. It is configured with. The partition plate 12 is detachably provided in the reaction chamber 11 with respect to the reaction chamber 11. Each of the burners 14 and 15 is a burner having a concentric structure, for example, and at least one, for example, two in this embodiment is provided. The gas supply unit 17 and the control unit 18 are provided in, for example, a predetermined portion outside the reaction chamber 11.

  The reaction chamber 11 is substantially partitioned by a partition plate 12 into a first reaction chamber 11A in which the burners 14 and 15 are present and a second reaction chamber 11B in which the burners 14 and 15 are not present. The partition plate 12 is made of a material excellent in heat resistance and corrosion resistance, specifically, for example, made of quartz, metal, or a material coated with metal, but is not necessarily limited to these materials. Note that a plurality of partition plates may be provided, and the inside of the second reaction chamber 11B may be further substantially partitioned by a partition plate.

  An optical fiber porous base material (hereinafter referred to as a porous base material) 2 manufactured in the VAD apparatus 1 is formed on the outer periphery of a target rod 3 as a starting material and is synthesized on the inner side, and the inner deposition soot 2a. It consists of the outer deposition soot 2b synthesized on the outer side of the deposition soot 2a. The inner deposition soot 2a becomes a core part in the optical fiber as the final product. The outer deposition soot 2b becomes a clad portion around the core portion in the optical fiber as the final product. The pulling mechanism 4 is configured to be able to pull up while rotating the target rod 3 while holding it. The partition plate 12 is provided with an opening 12 a having a size that allows the porous base material 2 to be pulled up to pass without contacting.

The burner 14 in the VAD apparatus 1 is a burner for synthesizing the inner deposition soot 2a. The burner 15 is a burner for synthesizing the outer deposition soot 2b. Each of the burners 14 and 15 is supplied from a gas supply unit 17 by, for example, a raw material gas such as silicon tetrachloride (SiCl ₄ ) or siloxane, a hydrogen (H ₂ ) gas that is a combustible gas, and an oxygen (O ₂ ) that is a combustion gas. Gas, carrier gas, etc. are flowed. In addition, you may provide the auxiliary | assistant burner for baking the boundary part of the inner deposition soot 2a and the outer deposition soot 2b separately. By the hydrolysis reaction of these gases in the flame, synthetic quartz glass fine particles (hereinafter referred to as glass fine particles) are sprayed and deposited on the target rod 3 to form an inner deposition soot 2a and an outer deposition soot 2b.

  A first air supply port 19 and a second air supply port 20 as an air supply unit capable of introducing clean air as a gas into the reaction chamber 11 are provided on the side of the reaction chamber 11 independently of each other. Yes. The first air supply port 19 is provided in the first reaction chamber 11 </ b> A and includes at least one air supply port. The first air inlet 19 may be composed of a plurality of air inlets. Further, the second air supply port 20 is provided in the second reaction chamber 11B, and in this embodiment, the second air supply port 20 is configured by one air supply port, but may be configured by a plurality of air supply ports.

  A first exhaust duct 21 and a second exhaust duct 22 are provided at positions facing the first air supply port 19 and the second air supply port 20 in the side portion of the reaction chamber 11, respectively. That is, the porous base material 2 is configured to be positioned between the first air supply port 19 and the first exhaust duct 21 and between the second air supply port 20 and the second exhaust duct 22. . The first exhaust duct 21 is provided in the first reaction chamber 11A, and is configured to mainly discharge the gas in the first reaction chamber 11A. As a result, the gas 42a containing glass particles is exhausted from the first reaction chamber 11A. The second exhaust duct 22 is provided in the second reaction chamber 11B, and is configured to mainly discharge the gas in the second reaction chamber 11B. Thereby, the gas 42b containing glass fine particles is exhausted from the second reaction chamber 11B.

  The first exhaust duct 21 as the first exhaust part is connected to the first flow rate adjusting part 31 as the first flow rate adjusting means through the pipe 31a. The first flow rate adjusting unit 31 is composed of, for example, a flow rate adjusting valve capable of adjusting the flow rate of the gas 42 a discharged through the first exhaust duct 21. The second exhaust duct 22 as the second exhaust part is connected to the second flow rate adjusting part 32 as the second flow rate adjusting means through the pipe 32a. The second flow rate adjustment unit 32 is configured by, for example, a flow rate adjustment valve capable of adjusting the flow rate of the gas 42 b discharged through the second exhaust duct 22. The pipes 31a and 32a communicate with the external exhaust pipe 34, respectively. That is, the first exhaust duct 21 and the second exhaust duct 22 are connected to the external exhaust pipe 34 via the first flow rate adjustment unit 31 and the second flow rate adjustment unit 32, respectively. The external exhaust pipe 34 is connected to a pump (not shown), and the gas in the reaction chamber 11 can be exhausted through the external exhaust pipe 34 by the pump. The first flow rate adjustment unit 31, the second flow rate adjustment unit 32, and the pump are each controlled by the control unit 18. In addition, you may comprise the 1st flow volume adjustment part 31, the 2nd flow volume adjustment part 32, and a pump so that an operator can set manually.

(Manufacturing method of optical fiber porous base material)
Next, the manufacturing method of the optical fiber porous preform | base_material by VAD method using the VAD apparatus 1 by one Embodiment comprised as mentioned above is demonstrated.

That is, as shown in FIG. 1, the inner deposition soot 2 a is formed by spraying and depositing glass fine particles on the target rod 3 from the burner 14. At the same time, the outer deposition soot 2b is deposited by spraying each gas from the burner 15 to deposit the glass particles on the outer side of the inner deposition soot 2a. Thereby, the outer deposition soot 2b is deposited outside the inner deposition soot 2a, and the porous base material 2 is manufactured. The heating power can be adjusted by adjusting the flow rates of H ₂ gas and O ₂ gas flowing from the burners 14 and 15 of the VAD device 1.

  During the production of the porous base material 2, in the first reaction chamber 11 </ b> A of the reaction chamber 11, among the glass particles synthesized by spraying from the burners 14 and 15, the inner deposition soot 2 a or the outer deposition soot 2 b is deposited. The fine glass particles that are not suspended are floating. Similarly, in the second reaction chamber 11B that is partitioned from the first reaction chamber 11A by the partition plate 12, the first reaction chamber 11A passes through the gap around the opening 12a between the partition plate 12 and the porous base material 2. Fine glass particles that entered from above are floating. In particular, since the outer diameter of the outer deposition soot 2b is small at the beginning of the production of the porous base material 2, the gap around the opening 12a between the partition plate 12 and the porous base material 2 is large, and the glass is floating. Most of the fine particles enter the second reaction chamber 11B through the gap.

  Therefore, by controlling the first flow rate adjusting unit 31 by the control unit 18, the exhaust flow rate of the gas 42a containing glass fine particles from the first reaction chamber 11A and the flow rate of the air 41a introduced into the first reaction chamber 11A are controlled. By controlling, a desired air flow is formed in the first reaction chamber 11A. Similarly, by controlling the second flow rate adjusting unit 32 by the control unit 18, the flow rate of the gas 42b discharged from the second reaction chamber 11B and the flow rate of the air 41b introduced into the second reaction chamber 11B are controlled. Thus, a desired air flow is formed in the second reaction chamber 11B. By appropriately controlling the first flow rate adjusting unit 31 and the second flow rate adjusting unit 32 independently of each other, generation of a circulating flow of a gas containing glass fine particles inside the first reaction chamber 11A and the second reaction chamber 11B. Is suppressed.

  According to the embodiment of the present invention described above, the first reaction chamber 11A in which the burners 14 and 15 are present and the second reaction chamber 11B in which the burners 14 and 15 are present, which are substantially partitioned by the partition plate 12 in the reaction chamber 11, respectively. A first exhaust duct 21 and a second exhaust duct 22 are provided, and the exhaust amount is adjusted in each of the first reaction chamber 11A and the second reaction chamber 11B. Thereby, since air supply and exhaust can be set for each space in the reaction chamber 11 substantially partitioned by the partition plate 12, the circulation flow of the gas containing glass fine particles in the reaction chamber 11 can be suppressed. Accordingly, since the amount of glass particles adhering to the wall surface of the reaction chamber 11 or depositing on the partition plate 12 can be reduced, the possibility that the glass particles will reattach to the porous base material 2 is reduced, and the porous base material 2 is reduced. It can suppress that a crack generate | occur | produces in the material 2 or a bubble generate | occur | produces in the optical fiber base material which vitrified the porous base material 2. FIG.

  Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

  In the above-described embodiment, the pump is commonly used and the exhaust duct is provided with a flow rate adjusting unit, and the exhaust flow rate is adjusted in each exhaust duct. However, the control unit 18 controls each of the plurality of exhaust ducts. A pump capable of controlling the exhaust flow rate may be connected.

  In the above-described embodiment, an example in which the present invention is applied to a VAD apparatus has been described. However, the present invention can also be applied to an OVD (Outside Vapor Deposition) apparatus.

  In the above-described embodiment, the first air supply port 19 and the second air supply port 20 are provided independently of each other, but the first air supply port 19 and the second air supply port 20 are provided. You may comprise from the same inlet.

  In the above-described embodiment, the example in which one partition plate 12 is provided in the reaction chamber 11 has been described. However, a plurality of partition plates may be provided. Since the second reaction chamber 11B is substantially partitioned by the further partition plate, the movement of the suspended glass particles to the upper part of the partitioned reaction chamber 11 can be suppressed in the second reaction chamber 11B. The amount of glass fine particles adhering to the upper wall surface or depositing on the partition plate can be further reduced, and the reattachment of the glass fine particles to the porous base material 2 can be further suppressed.

  In the above-described embodiment, each of the first exhaust duct 21 as the first exhaust part and the second exhaust duct 22 as the second exhaust part is configured by one duct. It is not limited. Each of the first exhaust part and the second exhaust part may be composed of a plurality of exhaust ducts.

DESCRIPTION OF SYMBOLS 1 VAD apparatus 2 Porous base material 2a Inner deposition soot 2b Outer deposition soot 3 Target rod 4 Lifting mechanism 11 Reaction chamber 11A 1st reaction chamber 11B 2nd reaction chamber 12 Partition plate 12a Opening 14,15 Burner 17 Gas supply part 18 Control part 19 1st air supply port 20 2nd air supply port 21 1st exhaust duct 22 2nd exhaust duct 31 1st flow volume adjustment part 31a, 32a piping 32 2nd flow rate adjustment part 34 External exhaust pipe 41a, 41b Air 42a, 42b gas

Claims (5)

A reaction chamber;
A burner provided in the reaction chamber;
A gas supply unit for supplying a gas containing a raw material gas and a combustible gas to the burner,
Production of an optical fiber porous preform in which the gas is supplied from the burner to the starting material in the reaction chamber, and fine particles generated by the reaction of the gas are deposited on the outer periphery of the starting material to form a porous preform. A device,
A partition plate through which the porous base material can pass is provided in the reaction chamber;
By the partition plate, the reaction chamber is substantially partitioned into a reaction chamber in which the burner exists and a reaction chamber in which the burner does not exist,
The reaction chamber in which the burner is present is provided with a first exhaust part capable of controlling the exhaust flow rate, and the reaction chamber in which the burner is not present is provided with a second exhaust part capable of controlling the exhaust flow rate. An optical fiber porous preform manufacturing apparatus.   2. The apparatus for producing a porous optical fiber preform according to claim 1, wherein a plurality of the partition plates are provided, and a reaction chamber in which the burner is not present is further partitioned into at least two reaction chambers.   The optical fiber porous mother according to claim 1 or 2, wherein an air supply unit capable of introducing a gas from outside is provided in a reaction chamber in which the burner exists and in a reaction chamber in which the burner does not exist. Material manufacturing equipment.   The air supply unit provided in the reaction chamber in which the burner exists and the air supply unit provided in the reaction chamber in which the burner does not exist are provided independently of each other. Optical fiber porous preform manufacturing equipment. An optical fiber porous material in which a gas containing a raw material gas and a combustible gas is supplied from a burner to a starting material in a reaction chamber, and fine particles generated by the reaction of the gas are deposited on the outer periphery of the starting material to form a porous base material. A method of manufacturing a base material,
The reaction chamber is provided in the reaction chamber in which the burner is present in a state where the reaction chamber is substantially partitioned into a reaction chamber in which the burner exists and a reaction chamber in which the burner does not exist by a partition plate through which the porous base material can pass. The first exhaust unit that can control the exhaust flow rate exhausted the gas in the reaction chamber in which the burner exists, and the second exhaust unit that can control the exhaust flow rate provided in the reaction chamber in which the burner does not exist The method for producing a porous optical fiber preform, wherein the gas in the reaction chamber without the burner is exhausted.

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