JP2004161606A - Apparatus for producing optical fiber preform - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing an optical fiber preform in which abrupt flame-up of a flame containing glass fine particles blown out from a burner is suppressed, the productivity of soot is improved by accelerated formation of the soot, and the amount of glass fine particles which adhere to the wall of a reaction vessel is reduced. <P>SOLUTION: The apparatus is equipped with a reaction chamber 2 in which the soot 10 is formed, and has a reaction vessel 1 in which air is made to flow from one side to the other side of the reaction chamber in a horizontal direction, a core burner 7 for forming a core layer 11, a cladding burner 6 for forming a cladding layer 12 around the core layer 11, a lifting mechanism for lifting the soot 10 while rotating it so that the tip end part and the cylindrical part of the soot 10 are situated in a core forming area B and a cladding layer forming area B, respectively, and first to fourth horizontal baffles 19, 21, 23, 24 which are horizontally arranged so as to maintain the flow direction of air to be horizontal in the reaction chamber 2. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to an optical fiber preform manufacturing apparatus for forming soot by depositing glass fine particles generated by a burner.

  The soot, which is an optical fiber preform, is mainly manufactured by the VAD method. In the VAD method, air is caused to flow in a horizontal direction from one side to the other side in a reaction chamber, and a flame containing glass particles is generated by a burner disposed on one side, and the flame is blown against a seed rod. Thereby, glass particles are deposited. Then, this method is a method of obtaining a soot having a double columnar structure including a core layer and a clad layer by pulling up while rotating a seed rod. Therefore, in this VAD method, since the amount of glass particles deposited per unit time affects the soot diameter, it is important to stably spray a flame containing glass particles on the soot to obtain high-quality soot. It is.

  Therefore, in the related art, as disclosed in Patent Document 1, for example, an air storage chamber is formed by erecting a rectifying plate made of a filter on the entire surface on one side of the reaction chamber, and the air storage chamber is disturbed. After the air blown into the flow state is once stored, the air is supplied to the reaction chamber while being rectified by the rectifying plate, thereby stabilizing the flame in the air flow.

  Further, in Patent Document 2, an airflow rectifying plate is erected on one side of a reaction chamber so as to be orthogonal to an air flow, and by this airflow rectifying plate, air is prevented from flowing into a region around a flame. A configuration for stabilizing a flame is disclosed. Further, Patent Document 3 discloses that an air supply port is disposed above a burner, and a horizontal baffle plate is disposed above the burner, thereby further preventing the flow of air around the flame and stabilizing the flame. A configuration for achieving this is disclosed.

JP-A-11-34315 JP 2000-290035 A Japanese Utility Model Publication No. 1-108504

  However, the configuration of Patent Document 1 has a problem that the flame cannot be sufficiently stabilized because the distance between the straightening plate and the flame at the tip of the burner is large. That is, generally, when a flame containing glass particles is ejected from a burner, air flowing horizontally in a rectified state in the reaction chamber rises due to thermal expansion due to heating of the flame when passing near the flame. . If the distance between the straightening plate and the flame at the tip of the burner is large as in the conventional case described above, the heated air rises without resistance. And the rectification state of the air will be greatly disrupted. As a result, the flame of the burner rises with the turbulence of the air, and is greatly disturbed and becomes unstable.

  As a result, in the above-described conventional configuration, the density of the glass particles contained in the flame decreases and becomes unstable, so that there is a problem that the diameter of the soot formed by the deposition of the glass particles tends to become unstable. Furthermore, as a result of a large amount of glass particles adhering to the upper surface wall in the reaction chamber due to the upward flow of air, there is a problem that the glass particles are separated from the upper surface wall and easily adhere to the soot as impurities.

  Further, in the configurations of Patent Literature 2 and Patent Literature 3, since air is not supplied to the burner, there is a problem that the outer wall of the burner is easily overheated and the life of the burner is shortened particularly when a soot is formed by a large flame.

  In view of the above, the present invention considers the above-described problems, and stabilizes the flame by suppressing the upward flow of air due to the flame of the burner while ensuring long life by blowing air to the burner. It is another object of the present invention to provide an optical fiber preform manufacturing apparatus that stably forms a soot having a desired diameter with high productivity by preventing glass particles from adhering to an upper surface wall.

  The present invention is an optical fiber preform manufacturing apparatus for forming a soot having a double columnar structure composed of a core layer and a clad layer by depositing glass fine particles, comprising: a reaction chamber in which the soot is formed; A reaction vessel flowing horizontally from one side of the reaction chamber to the other side, and forming the core layer by jetting a flame containing the glass particles from one side of the reaction chamber toward a core layer formation region. A core burner; a clad burner for forming the clad layer around the core layer by jetting a flame containing the glass particles from one side of the reaction chamber toward the clad layer formation region; and the soot. A pull-up mechanism that pulls up while rotating the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively. It is characterized by having a horizontal baffle plate disposed above the arrangement position of the cladding burner a one side of the reaction chamber.

  According to the above configuration, since the horizontal baffle is disposed above the cladding burner, the horizontal flow of the gas on the upstream side of the gas flow as viewed from the soot is maintained. As a result, the rise of the gas causing the rise and turbulence of the flame is suppressed at least on the upstream side of the gas flow as viewed from the soot, so that the soot having a desired diameter can be formed stably with high productivity. Further, when the upward flow of gas is suppressed, the amount of glass particles adhering to the upper wall can be reduced, so that glass particles are less likely to be separated from the upper wall and adhere to the soot as impurities. it can. In addition, the life of the clad burner can be prolonged by blowing at least gas onto the clad burner having a large amount of heat to cool the burner. The gas introduced into the reaction chamber of the present invention is preferably a gas that has passed through a filter or a lattice, and a hepa filter can be suitably used for this filter.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above configuration, wherein the horizontal baffle plate is formed with a cutout portion so as to surround a part of a trunk portion of the soot.

  According to the above configuration, the rise of the gas causing the rise and the turbulence of the flame is further suppressed on the upstream side of the gas flow as viewed from the soot, so that the soot having a desired diameter is formed more stably with high productivity. be able to.

  Further, the present invention provides the optical fiber preform manufacturing apparatus having the above-described configuration, wherein the horizontal baffle is provided with at least one above the clad burner and between the clad burner and the core burner. It is characterized by having a multi-stage configuration. According to the above configuration, the rise of the gas causing the rise and the turbulence of the flame is further suppressed by the multi-stage horizontal baffle plate, so that the soot having a desired diameter can be formed more stably with high productivity. .

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above configuration, wherein the horizontal baffle plate of each stage is formed with a cutout portion so as to surround a part of the trunk of the soot. And

  According to the above configuration, the rise of the gas that causes the rise and the turbulence of the flame is further suppressed by the multi-stage horizontal baffle plate and the cutout portion of each stage, so that the soot having a desired diameter can be more stably produced with high productivity. Can be formed.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above-described configuration, wherein the notch portion of the horizontal baffle plate of each stage is set to have a size corresponding to the diameter of the soot in each stage. It is characterized by.

  According to the above configuration, the rise of the gas that causes the rise and turbulence of the flame is further suppressed by the cutouts of the respective stages whose sizes are set so as to correspond to the diameters of the soot in the respective stages. The soot having a diameter can be formed more stably with high productivity.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above-described configuration, wherein a wind direction in which a flow direction of a gas in the reaction chamber is changed from an outside in a width direction of the reaction chamber to an inside of the soot is located. It is characterized by having a plate.

  According to the above configuration, the gas flowing in the horizontal direction can be caused to flow toward the soot by the wind direction plate. Thereby, even if a small amount of gas is supplied, the flow velocity of the gas toward the soot can be sufficiently increased.

  Further, the present invention is an optical fiber preform manufacturing apparatus for forming a soot having a double columnar structure composed of a core layer and a clad layer by depositing glass fine particles, comprising: a reaction chamber in which the soot is formed; A reaction vessel that flows horizontally from one side of the reaction chamber to the other side, and the flame containing the glass particles is ejected from one side of the reaction chamber toward the core layer formation region to form the core layer. A core burner to be formed, and a flame containing the glass particles is ejected from one side of the reaction chamber toward a clad layer forming region, so that a clad burner that forms the clad layer around the core layer. Pulling up while rotating the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively. And structure, is characterized by having a horizontal baffle plate disposed above the arrangement position of the cladding burner a second side of the reaction chamber.

  According to the above configuration, since the horizontal baffle is disposed on the other side of the reaction chamber and above the cladding burner, the horizontal flow of the gas downstream of the gas flow as viewed from the soot is maintained. . As a result, the rise of the gas causing the rise and turbulence of the flame is suppressed at least on the downstream side of the gas flow when viewed from the soot, so that the soot having a desired diameter can be formed stably with high productivity. Further, when the upward flow of gas is suppressed, the amount of glass particles adhering to the upper wall can be reduced, so that glass particles are less likely to be separated from the upper wall and adhere to the soot as impurities. it can. In addition, the life of the clad burner can be prolonged by blowing at least gas onto the clad burner having a large amount of heat to cool the burner.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above configuration, wherein the horizontal baffle plate is formed with a cutout portion so as to surround a part of a trunk portion of the soot.

  According to the above configuration, the rise of the gas causing the rise and the turbulence of the flame is further suppressed on the upstream side of the gas flow as viewed from the soot, so that the soot having a desired diameter is formed more stably with high productivity. be able to.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above-mentioned configuration, wherein the horizontal baffle is provided at least one each above the clad burner and between the clad burner and the core burner. It is characterized by a configuration of a plurality of stages arranged.

  According to the above configuration, the rise of the gas causing the rise and the turbulence of the flame is further suppressed by the multi-stage horizontal baffle plate, so that the soot having a desired diameter can be formed more stably with high productivity. .

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above configuration, wherein the horizontal baffle plate of each stage is formed with a cutout portion so as to surround a part of the trunk of the soot. And

  According to the above configuration, the rise of the gas that causes the rise and the turbulence of the flame is further suppressed by the multi-stage horizontal baffle plate and the cutout portion of each stage, so that the soot having a desired diameter can be more stably produced with high productivity. Can be formed.

  Further, the present invention is an optical fiber preform manufacturing apparatus for forming a soot having a double columnar structure composed of a core layer and a clad layer by depositing glass fine particles, comprising: a reaction chamber in which the soot is formed; A reaction vessel horizontally flowing from one side to the other side of the reaction chamber, and forming the core layer by ejecting a flame containing the glass particles from the upstream side of the gas toward the core layer formation region. A burner for a core that forms the clad layer around the core layer by blowing a flame containing the glass particles from an upstream side of the gas toward a clad layer forming region; A pull-up machine that rotates and pulls up the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively. When it is characterized by having a first gas delivery mechanism for flowing the gas traveling through the upper wall near the reaction chamber at a speed higher than the gas traveling through the other parts.

  According to the above configuration, the gas flowing in the vicinity of the upper surface wall of the reaction chamber is caused to flow at a high speed by the first gas delivery mechanism in the reaction vessel, so that the glass fine particles contained in the flames of the core burner and the clad burner are sooted. When it rises without adhering to the upper surface of the reaction chamber, it can be blown downstream with a high-speed gas flow before adhering to the upper wall of the reaction chamber. As a result, the amount of many glass particles adhering to the upper surface wall in the reaction chamber can be reduced, so that the glass particles can be separated from the upper surface wall and hardly adhere to the soot as impurities.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above configuration, wherein a shielding plate for reducing a circulating flow of gas to the core burner is provided on the other side of the reaction chamber as viewed from the soot. It is characterized by having.

  According to the above configuration, since the circulating flow of the gas toward the core burner is blocked by the shielding plate, it is possible to prevent the flame of the core burner from being disturbed by the circulating flow. Thereby, productivity can be improved by forming a core layer with a stable flame.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above-described configuration, wherein the reaction chamber includes a clad layer forming space containing a clad burner and a core layer forming space containing a core burner. It is characterized by being partitioned.

  According to the above configuration, since the reaction chamber is divided into the clad layer formation space and the core layer formation space, the gas circulation flow in the clad layer formation space does not go to the core burner. Thereby, since the turbulence of the flame of the core burner due to the circulating flow can be reduced, productivity can be improved by forming the core layer with a stable flame.

  Further, the present invention is an optical fiber preform manufacturing apparatus for forming a soot having a double columnar structure composed of a core layer and a clad layer by depositing glass fine particles, comprising: a reaction chamber in which the soot is formed; A reaction vessel horizontally flowing from one side to the other side of the reaction chamber, and forming the core layer by ejecting a flame containing the glass particles from the upstream side of the gas toward the core layer formation region. A burner for a core that forms the clad layer around the core layer by blowing a flame containing the glass particles from an upstream side of the gas toward a clad layer forming region; A pull-up machine that rotates and pulls up the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively. And a horizontal baffle plate horizontally disposed in the reaction chamber so that the flow direction of the gas in the reaction chamber is maintained in a horizontal direction, and the gas traveling near the upper surface wall of the reaction chamber travels to another part. A first gas delivery mechanism for flowing the gas at a higher speed than the gas, wherein the reaction chamber is divided into a clad layer forming space containing a clad burner and a core layer forming space containing a core burner. It is characterized by having.

  According to the above configuration, the rise of the gas causing the rise and turbulence of the flame is suppressed by the horizontal baffle on the upstream side of the gas flow as viewed from the soot, so that the soot of a desired diameter can be stably produced with high productivity. Can be formed. Also, by causing the gas flowing near the upper wall of the reaction chamber to flow at a high speed by the first gas delivery mechanism, the glass particles contained in the flame of the core burner and the clad burner rise without adhering to the soot. In addition, the gas can be blown downstream with a high-speed gas flow before adhering to the upper wall of the reaction chamber. As a result, the amount of many glass particles adhering to the upper surface wall in the reaction chamber can be reduced, so that the glass particles can be separated from the upper surface wall and hardly adhere to the soot as impurities.

  Furthermore, since the reaction chamber is divided into the clad layer formation space and the core layer formation space, the gas circulation in the clad layer formation space does not flow toward the core burner. Thereby, since the turbulence of the flame of the core burner due to the circulating flow can be reduced, productivity can be improved by forming the core layer with a stable flame.

  Further, the present invention is the optical fiber preform manufacturing apparatus having the above-described configuration, wherein the optical fiber preform manufacturing apparatus has an exhaust unit disposed on the other side in the reaction chamber, the exhaust cross-sectional area up to an exhaust port is gradually reduced. It is characterized by.

  According to the above configuration, by narrowing the cross-sectional area up to the exhaust port for exhausting the gas flowing horizontally in the reaction chamber, the gas, the gas is ejected from the cladding burner and the core burner, the core layer and The suction force for exhausting the surplus glass fine particles not deposited as the cladding layer is improved, and the exhaust can be efficiently exhausted. In addition, stagnation of gas in the reaction chamber due to glass particles contained in the flame can be reduced.

  According to the present invention, there is a case where a soot having a desired diameter can be formed stably with a high productivity by suppressing a rise of a gas which causes a rise and a turbulence of a flame. Furthermore, since the amount of glass particles adhering to the upper surface wall can be reduced by suppressing the upward flow of the gas, there is a case where the glass particles are less likely to separate from the upper surface wall and adhere to the soot as impurities. is there. Further, in some cases, the life of the clad burner can be prolonged by blowing at least a gas onto the clad burner having a large amount of heat to cool the burner.

(1st Embodiment)
First Embodiment An optical fiber preform manufacturing apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  The optical fiber preform manufacturing apparatus according to the present embodiment includes a hollow reaction vessel 1 as shown in FIG. The reaction vessel 1 is formed of a material having excellent acid resistance and heat resistance. The first to fourth horizontal baffles 19, 21, 23, and 24 described later are also formed of the same material.

  The above-described reaction vessel 1 includes a reaction chamber 2 in which a soot 10 is formed. The reaction vessel 1 has an air retention chamber 14 and an exhaust part 35 on one side and the other side, respectively, with the reaction chamber 2 as a center, and also has a soot accommodation chamber 8 above the reaction chamber 2. The soot 10 is composed of a core layer 11 and a clad layer 12 formed by depositing fine glass particles, and has a double columnar structure in which the clad layer is formed in an annular shape around the core layer 11.

  In the reaction chamber 2 described above, a partition wall 5 is provided horizontally across the entire lower part. The partition wall 5 divides the reaction chamber 2 into an upper clad layer forming space 3 and a lower core layer forming space 4. The cladding layer forming space portion 3 is set in a rectangular parallelepiped shape. One side on the right side in the figure is opened as an air supply port 3a, and the other side on the left side in the figure is opened as an air exhaust port 3b. ing. A filter 13 is provided on the entire surface of the air supply port 3a. The filter 13 and the partition of the reaction vessel 1 form an air retention chamber 14.

  The air stagnation chamber 14 is divided into a first air stagnation section 15 on the upper wall 1 a side of the reaction vessel 1 and a second air stagnation section 16 located below the first air stagnation section 15. A first blower 17 and a second blower 18 are respectively connected to these air staying portions 15 and 16. Each of the blowers 17 and 18 is capable of supplying air in the atmosphere to each of the air retaining sections 15 and 16 at respective supply rates. As a result, the air stays in each of the air staying portions 15 and 16, and the air passes through the filter 13 and is introduced into the cladding layer forming space 3. The air supply amount of each of the blowers 17 and 18 is set, for example, so that the air traveling near the upper surface wall 1a of the clad layer forming space 3 flows faster than the air traveling other parts. It is set based on the volume of the parts 15 and 16 and the like.

  In addition, as shown in FIG. 4, as a method of blowing air from the air stagnation sections 14 and 15 (air stagnation chamber 14) to the reaction chamber 2, the burner arranging section is made as small as possible, and the air is blown from almost the entire surface. As shown in FIG. 5, there is a method of dividing the air from the second air retaining section 16 into two parts and blowing out the air from two places on the left and right sides, and any of these methods may be adopted.

  The first air stagnation section 15 and the second air stagnation section 16 are defined by a first horizontal baffle plate 19. The first horizontal baffle plate 19 is disposed horizontally from the air stagnation chamber 14 through the filter 13 to the position where the soot 10 exists in the clad layer forming space 3. The first horizontal baffle plate 19 helps to suppress the rise of air in the clad layer formation space 3. The first horizontal baffle plate 19 is preferably provided so as to divide the gas flowing in the reaction chamber 2 in the horizontal direction. That is, it is preferable to supply gas above and below the horizontal baffle. In this case, the gas flows up and down the first horizontal baffle plate 19, so that the gas in the reaction chamber can move smoothly in the horizontal direction.

  As shown in FIG. 2, a notch 19 a is formed at the end of the first horizontal baffle plate 19 so as to surround a part of the body of the soot 10. The notch 19a reduces the gap between the body of the soot 10 and the first horizontal baffle plate 19, thereby reducing the rise of air due to leakage from the gap.

  Above the first horizontal baffle plate 19, a pair of wind direction plates 20 are erected symmetrically. The wind direction plates 20 are disposed between the first horizontal baffle plate 19 and the upper surface wall 1a of the cladding layer forming space 3. As shown in FIG. 2, these wind direction plates 20 have respective rear ends connected to ends (outside) in the width direction of the filter 13, and respective front ends on the soot 10 side are positioned inside in the width direction. It is arranged to be located. As a result, the direction of flow of the air supplied from the first air retaining portion 15 to the cladding layer forming space 3 is changed from the outside in the width direction of the cladding layer forming space 3 to the inside where the soot 10 is located. It is changed to go to. Accordingly, the wind direction plates 20 and 20 allow the air flowing in the horizontal direction to flow toward the soot 10, so that even if a small amount of air is supplied from the first air retaining portion 15, the air flowing toward the soot 10 It is intended to increase the flow rate and flow rate sufficiently.

  On the other hand, as shown in FIG. 1, a second horizontal baffle plate 21 is provided at a predetermined interval below the first horizontal baffle plate 19 in the cladding layer forming space 3. The second horizontal baffle plate 21 is disposed horizontally from the filter 13 to the position where the soot 10 is formed. Similarly to the first horizontal baffle 19 described above, the second horizontal baffle 21 prevents at least the soot 10 from rising in the cladding layer forming space 3 that causes the flame 30 of the cladding burner 6 to rise and disturb, which will be described later. From the viewpoint of the air flow. Further, a cutout portion 21 a is formed at the end of the second horizontal baffle plate 21 so as to surround a part of the body of the soot 10. The notch 21a reduces the gap between the body of the soot 10 and the second horizontal baffle plate 21 to reduce the rise in air due to leakage from the gap. The second horizontal baffle plate 21 and the first horizontal baffle plate 19 configured as described above are formed in a plurality of stages in the cladding layer formation space portion 3 to further suppress the rise of air. Is possible.

  The clad burner 6 is provided below the second horizontal baffle plate 21. The cladding burner 6 is disposed so as to blow out the flame 30 from one side of the cladding layer formation space 3 toward the cladding layer formation region A. That is, the burner 6 for cladding has the burner port 6a on the front end side facing the body of the soot 10 in the cladding layer formation region A. Here, the clad layer forming region A is a region located at a position in a height direction and a horizontal direction that is optimal for efficiently forming the clad layer 12 by depositing glass fine particles in the flame 30. The cladding burner 6 is provided horizontally in the horizontal direction toward one side of the cladding layer forming space 3 so that the jet direction of the flame 30 coincides with the gas flow direction. Then, after the clad burner 6 is provided through the above-described filter 13 and the second air retaining section 16, the rear end is disposed outside the machine. The clad burner 6 may be inclined so that the burner port 6a is located above the rear end.

  The above-mentioned clad burner 6 has a multi-tube structure in which a quartz tube member is used as a partition, and has multiple annular gas flow paths from the center to the outer periphery. The rear end of the cladding burner 6 is connected to a gas supply device (not shown). The gas supply device is configured to be able to supply hydrogen gas (H2), oxygen gas (O2), argon gas (Ar), and silicon tetrachloride gas (SiCl4 + Ar) at respective flow rates. The hydrogen gas (H2), the oxygen gas (O2), the argon gas (Ar), and the silicon tetrachloride gas (SiCl4 + Ar) pass through the respective gas passages arranged from the center to the outer periphery of the cladding burner 6. To be supplied.

  A partition wall 5 is provided below the clad burner 6. The partition wall 5 functions to divide the reaction chamber 2 into the cladding layer forming space 3 and the core layer forming space 4 as described above, and also to divide air flowing below the cladding burner 6 in the horizontal direction. It functions to move smoothly. As a result, in the cladding layer forming space 3, a smooth flow of air is maintained between the partition wall 5, the first horizontal baffle plate 19, and the second horizontal baffle plate 21.

  On the other hand, a third horizontal baffle plate 23 and a fourth horizontal baffle plate 24 are provided on the other side of the clad layer formation space 3. These horizontal baffles 23 and 24 are provided horizontally at the same height as the horizontal baffles 19 and 21 provided on one side of the cladding layer formation space 3. The horizontal baffles 23 and 24 are provided at a predetermined distance from the trunk of the soot 10. Each of the horizontal baffles 23 and 24 maintains the horizontal flow of air downstream of the air flow when viewed from the soot 10. Furthermore, these horizontal baffles 23 and 24 are arranged in multiple stages so as to more effectively maintain the horizontal flow of air.

  A core burner 7 having a multi-tube structure similar to the clad burner 6 is provided in the core layer forming space 4 located below the cladding layer forming space 3. The core burner 7 is disposed so as to blow out the flame 31 from one side of the core layer forming space 4 toward the core layer forming region B. That is, in the core burner 7, the burner port 7a on the tip side is opposed to the core layer 11 in the core layer formation region B. Here, the core layer forming region B is a region located at a position in the height direction and the horizontal direction that is optimal for efficiently forming the core layer 11 by depositing the glass fine particles in the flame 31. Then, the core burner 7 is lowered while being inclined toward one side of the core layer forming space 4, and the rear end is disposed outside the machine.

  The core burner 7 is connected to a gas supply device (not shown), like the clad burner 6. The gas supply device is configured to be able to supply hydrogen gas (H2), oxygen gas (O2), argon gas (Ar), and silicon tetrachloride gas (SiCl4 + GeCl4 + Ar) at respective flow rates. The hydrogen gas (H2), the oxygen gas (O2), the argon gas (Ar), and the silicon tetrachloride gas (SiCl4 + GeCl4 + Ar) correspond to each gas flow path arranged from the center to the outer periphery of the core burner 7. To be supplied.

  The air exhaust port 3b of the clad layer formation space 3 is provided with an exhaust unit 35 for discharging the air of the clad layer formation space 3 out of the machine. The upper surface wall 1a of the reaction vessel 1 forming the exhaust portion 35 forms the clad layer formation space 3 so as to reduce the resistance to the high-speed flowing air and to easily exhaust the upward flow in the reaction vessel 1. It is arranged in the horizontal direction similarly to the upper surface wall 1 a of the reaction vessel 1.

  The exhaust part 35 has one end face and the other end face opened, and the other end face has an exhaust port 35a. On the other hand, one end surface of the exhaust unit 35 is connected to the air exhaust port 3b of the clad layer forming space 3. The exhaust unit 35 includes an exhaust path 36 communicating from an opening on one end surface to an exhaust port 35a on the other end surface. The exhaust path 36 has an exhaust cross-sectional area from the opening on one end surface to the exhaust port 35a. Has been gradually reduced. As a result, the exhaust unit 35 efficiently exhausts air and glass particles from the clad layer forming space 3 by improving the suction force by narrowing the exhaust path 36 leading to the exhaust port 35a. And reduce stagnation of air.

  Above the cladding layer forming space 3, a pulling mechanism 38 is provided. The pulling-up mechanism 38 has a pulling-up device (not shown) that pulls up the soot 10 and the soot storage chamber 8 that stores the soot 10 pulled up by the pulling-up device. The pulling device is configured to pull up the soot 10 while rotating the soot 10 so that the tip and the trunk of the soot 10 are located in the core layer forming region B and the clad layer forming region A, respectively. Thus, the soot 10 is formed such that the clad layer 12 having a predetermined thickness is formed around the core layer 11 in the clad layer formation region A while the core layer 11 is formed at a constant growth rate in the core layer formation region B. Has become.

  The operation of forming the soot 10 by using the optical fiber preform manufacturing apparatus in the above-described configuration in the synthesizing step by the VAD method will be described.

  First, the seed rod 39 is attached to a pulling device (not shown), and set so that the lower end of the seed rod 39 is located in the core layer forming region B of the core layer forming space 4. Thereafter, the first blower 17 and the second blower 18 are driven, and the air in the atmosphere is supplied to the first air holding portion 15 and the second air holding portion 16 of the air holding chamber 14, respectively. At this time, the air pressure of the first air stagnation section 15 is made higher than the air pressure of the second air stagnation section 16.

  The air supplied to the first air retaining portion 15 is temporarily stored, passes through a filter that is the filter 13, and is disposed between the first horizontal baffle plate 19 and the upper wall 1a in the cladding layer forming space 3. At a relatively high speed. This air moves smoothly and horizontally in the direction of the soot 10 by the first horizontal baffle plate 19, and is accelerated by the flow direction changing to the soot 10 direction and concentrated by the wind direction plates 20 and 20. The air delivered to the high-speed region blows onto the soot 10 as a very high-speed air flow, and flows near the upper surface wall 1a on the other side of the clad layer forming space 3, and then flows to the upper surface wall 1a. The air is exhausted to the outside through the exhaust part 35 while traveling in the horizontal direction.

  On the other hand, the air supplied to the second air retaining portion 16 is temporarily stored, then passes through the filter 13, and passes between the first horizontal baffle plate 19 and the partition wall 5 in the cladding layer forming space 3. Is sent to the low-speed area. This air smoothly moves in the horizontal direction to the other side of the cladding layer formation space 3 on the lower surface of the first horizontal baffle plate 19, the upper and lower surfaces of the second horizontal baffle plate 21, and the upper surface of the partition wall 5. This air partially blows against the clad burner 6 to cool the burner 6 or flow into the clad layer formation region A, and then the third horizontal baffle plate on the other side of the clad layer formation space 3. The flow direction is regulated in the horizontal direction by the 23 and the fourth horizontal baffle 24, and the air is exhausted to the outside through the exhaust part 35. Turbulence occurs when air partially blows on the clad burner. The effect of the first horizontal baffle plate 19 and the second horizontal baffle plate 21 can minimize the effect.

  The air flowing through the above-described clad layer forming space 3 is exhausted by a large suction force because the exhaust passage 36 of the exhaust unit 35 is narrowed toward the exhaust port 35a. Therefore, stagnation of air hardly occurs in both the high-speed region and the low-speed region.

  When the air is supplied to the clad layer forming space 3 as described above, hydrogen gas (H2), oxygen gas (O2), and argon gas (Ar) are supplied from a gas supply device (not shown) to the core burner 7. And silicon tetrachloride gas (SiCl4 + GeCl4 + Ar) are supplied. Then, the core burner 7 is ignited, and a flame 31 containing glass fine particles is jetted toward the core layer formation region B. As a result, the glass fine particles adhere and accumulate on the tip of the seed rod 39 set in the core layer formation region B. Then, the seed rod 39 is pulled up at a constant speed while being rotated by the pulling-up device, so that the core layer 11 of the soot 10 having a predetermined diameter (layer thickness) is formed, and the leading end of the core layer 11 is placed in the core layer forming region. B is grown in the axial direction of the seed rod 39 so as to be located at B.

  When the core layer 11 is formed as described above, the burner port 7a of the core burner 7 is accommodated in the core layer forming space 4, and the core layer forming space 4 is cut off the flow of air. ing. Therefore, the situation in which the flame 31 is not significantly disturbed by the air flow does not occur, so that the core layer 11 can be formed stably. Since the core burner 7 has a relatively small amount of heat of the flame 31, even if it is not cooled by blowing air, there is no problem that the core 31 is melted by overheating by the flame 31.

  Next, when a predetermined time has elapsed after the core layer 11 formed in the core layer formation region B is formed, a hydrogen gas (H2) and an oxygen gas (O2) are supplied to the cladding burner 6 from a gas supply device (not shown). ), Argon gas (Ar) and silicon tetrachloride gas (SiCl4 + Ar) are supplied. Then, the burner 6 for cladding is ignited, and a flame 31 containing glass particles is ejected toward the cladding layer forming region A. As a result, the glass particles adhere and accumulate around the core layer 11, and the clad layer 12 of the soot 10 having a predetermined diameter (layer thickness) is formed. The soot 10 having a double columnar structure composed of the core layer 11 and the clad layer 12 is formed by depositing and pulling up the glass particles by the flames 30 and 31 of the clad burner 6 and the core burner 7, respectively. Therefore, it is stored in the soot storage room 8.

  By the way, when the flame 30 of the cladding burner 6 is jetted toward the cladding layer formation region A, the air flowing horizontally in the cladding layer formation space 3 of the reaction chamber 2 passes near the cladding layer formation region A. When the flame 30 is heated, the flame 30 is thermally expanded and rises. However, in the rising direction of the air, two-stage first and second horizontal baffle plates 19 and 21 are provided on the upstream side when viewed from the soot 10, and two-stage third and fourth horizontal baffle plates 23 are provided. 24 is provided downstream from the soot 10. Therefore, when the air rises, the air collides with the first to fourth horizontal baffles 19, 21, 23, and 24, and the rise of the air is suppressed. Further, the first and second horizontal baffle plates 19 and 21 on the upstream side narrow a gap with the soot 10 by surrounding a part of the body of the soot 10 with the cutout portions 19a and 21a. Thereby, the rise of air is further suppressed on the upstream side.

  As a result, the rise of air is suppressed by the first to fourth horizontal baffles 19, 21, 23, 24 and the cutout portions 19a, 21a, so that significant turbulence of air is prevented. As a result, the rise and turbulence of the flame 30 of the cladding burner 6 caused by the upward flow of air can be suppressed, so that the cladding layer 12 is formed of stable glass particles having a large density. In addition, when the rise of the flame 30 is suppressed, a large amount of the flame 30 reaches the soot 10, so that the flame 30 easily wraps around the entire body of the soot 10, thereby promoting the formation of the clad layer 12.

  The glass fine particles not used in the soot 10 will rise along with the upward flow of air, but the upward flow of air is suppressed as described above. The amount reaching 1a is reduced. Further, the third and fourth horizontal baffles 23 and 24 on the downstream side prevent the glass fine particles from rising. Further, even when the glass particles reach the vicinity of the upper surface wall 1a, since the high-speed air flow exists, most of the glass particles are exhausted by this air flow. As a result, the amount of the glass particles adhering to the upper surface wall 1a is extremely small, and it is difficult to peel off. Further, even when the glass fine particles adhered to the upper surface wall 1a are peeled off, the glass particles are discharged by the high-speed air flow, so that it is extremely unlikely that the glass particles adhere to the soot 10 as impurities.

  In some cases, glass fine particles adhere to the third horizontal baffle plate 23 and the fourth horizontal baffle plate 24 on the downstream side and separate from these baffle plates 23 and 24. Since the glass particles 23 and 24 are separated from the soot 10 and the glass particles are moved to the opposite side from the soot 10 by an air flow, the glass particles hardly adhere to the soot 10.

  When the soot 10 having a predetermined length is formed in the synthesis process in this way, the soot 10 is taken out of the machine and transported to the sintering process. Then, the glass fine particles are sintered and vitrified to form a preform. When the diameter of the preform is small, a desired preform is formed by repeating formation of a new cladding layer 12 in the synthesis step and vitrification in the sintering step. Therefore, even when the synthesizing process is repeated, the soot 10 can be produced with high quality and with high productivity by using the optical fiber preform manufacturing apparatus of the present embodiment. Thereafter, in the drawing step, the preform is drawn into a preform having a desired length and diameter, and then, in the drawing step, an optical fiber is formed.

  As described above, the optical fiber preform manufacturing apparatus of the present embodiment forms soot 10 having a double columnar structure including the core layer 11 and the clad layer 12 by depositing glass fine particles. A reaction vessel 1 having a reaction chamber 2 (cladding layer forming space 3) formed therein, in which air (gas) flows horizontally from one side to the other side in the reaction chamber 2, and a flame 31 containing glass particles. The core burner 7 that forms the core layer 11 by ejecting the gas from the upstream side of the air toward the core layer forming region B, and the flame 31 containing the glass fine particles is directed toward the cladding layer forming region A from the upstream side of the air. By jetting, the clad burner 6 for forming the clad layer 12 around the core layer 11 and the tip and the trunk of the soot 10 are moved to the core layer formation region B and the clad layer formation region A. A pull-up mechanism for pulling up the soot 10 while rotating the soot 10 so as to be positioned at each position; and first to fourth horizontally arranged in the reaction chamber 2 so as to maintain the flow direction of air in the reaction chamber 2 in the horizontal direction. It has a configuration having horizontal baffles 19, 21, 23 and 24. The gas introduced into the reaction chamber of the present invention is preferably a gas that has passed through a filter or a lattice. A hepa filter can be suitably used for this filter.

  Thus, the first to fourth horizontal baffles 19, 21, 23, and 24 act to maintain the flow direction of air in the reaction chamber 2 in the horizontal direction, thereby suppressing the upward flow of air. While at the same time, it is possible to prevent significant turbulence of the air. As a result, the rise and turbulence of the flame 30 of the cladding burner 6 can be suppressed, so that the cladding layer 12 can be formed with stable glass particles having a large density. In addition, when the rise of the flame 30 is suppressed, a large amount of the flame 30 reaches the soot 10, so that the flame easily wraps around the entire body of the soot 10, so that the formation of the clad layer 12 can be promoted.

  Further, when the upward flow of air is suppressed, the amount of glass particles adhering to the upper surface wall 1a can be reduced, so that glass particles are less likely to separate from the upper surface wall and adhere to the soot 10 as impurities. Can be. Thereby, the soot 10 having a desired diameter can be formed stably with high productivity. In addition, by blowing air onto the clad burner 6 having a large amount of heat and cooling it, the life of the clad burner 6 can be extended.

  In the present embodiment, air is flown as a gas in the reaction chamber 2, but the present invention is not limited to this, and the gas may be an inert gas in addition to air. In the present embodiment, the soot 10 is formed by two burners of the clad burner 6 and the core burner 7, but the present invention is not limited to this, and the soot 10 is formed by three or more burners. 10 may be formed. In the present embodiment, the rise of air is suppressed by the first to fourth horizontal baffles 19, 21, 23, and 24. However, the present invention is not limited to this, and any one or more combinations It may be.

  For example, even if only one of the first horizontal baffle plate 19 and the second horizontal baffle plate 21 provided on one side of the reaction chamber 2 and above the position where the clad burner 6 is provided is provided. good. In this case, since the first horizontal baffle plate 19 or the second horizontal baffle plate 21 is disposed above the cladding burner 6, the horizontal flow of air at the upstream side of the air flow as viewed from the soot 10 is maintained. Is done. As a result, the rise of the air causing the rise and the turbulence of the flames 30 and 31 is suppressed at least on the upstream side of the air flow when viewed from the soot 10. Then, with the two-stage configuration as in the present embodiment, such an increase in air can be further suppressed.

  Alternatively, only one of the third horizontal baffle plate 23 and the fourth horizontal baffle plate 24 disposed on the other side of the reaction chamber 2 and above the position where the clad burner 6 is disposed may be used. . In this case, since the third horizontal baffle plate 23 or the fourth horizontal baffle plate 24 is disposed on the other side of the reaction chamber 2 and above the cladding burner 6, the downstream side of the air flow as viewed from the soot 10 The horizontal flow of air at is maintained. As a result, the rise of the air which causes the rise and the turbulence of the flames 30 and 31 is suppressed at least on the downstream side of the air flow as viewed from the soot 10, so that the soot 10 having a desired diameter can be formed stably with high productivity. can do. Then, with the two-stage configuration as in the present embodiment, such an increase in air can be further suppressed. The first to fourth horizontal baffles 19, 21, 23, and 24 are arranged in two stages on the upstream side and the downstream side, respectively, but are not limited thereto.

  Further, by forming cutout portions 19a and 21a in the first and second horizontal baffles 19 and 21 on the upstream side among the first to fourth horizontal baffles 19, 21 and 23 and 24, the body of the soot 10 is formed. It is designed to surround a part of the portion, but the present invention is not limited to this. Notches may be formed in all of the first to fourth horizontal baffles 19, 21, 23 and 24. Notches may be formed in the first to fourth horizontal baffles 19, 21, 23, 24. Further, the first to fourth horizontal baffles 19, 21, 23 and 24 are preferably provided so as to divide the gas flowing into the reaction chamber 2 in the vertical direction. Gas flows into the reaction chamber 2 from above and below the horizontal baffles 19, 21, 23, and 24, so that the gas flow in the horizontal direction of the reaction chamber 2 can be smoothly maintained.

  In addition, the optical fiber preform manufacturing apparatus according to the present embodiment has a first gas delivery mechanism (first air stagnation mechanism) that causes air traveling near the upper wall 1a of the reaction chamber 2 to flow at a higher speed than air traveling through other parts. And a first blower 17). Thereby, the air flowing near the upper surface wall 1a of the reaction chamber 2 is caused to flow at high speed by the first gas delivery mechanism, so that the glass fine particles contained in the flames 30 and 31 of the core burner 7 and the clad burner 6 are sooted. When it rises without adhering to the upper surface 10, it can be blown downstream by a high-speed air flow before adhering to the upper wall of the reaction chamber 2.

  Further, the optical fiber preform manufacturing apparatus of the present embodiment has a configuration in which the exhaust section 35 is provided on the other side in the reaction chamber 2 and the exhaust cross-sectional area up to the exhaust port 35a is gradually reduced. Have been. Thereby, the suction force of the exhaust unit 35 is improved, and the air can be efficiently exhausted. The exhaust unit 35 may be provided with an exhaust pump, and the pump may be configured to forcibly exhaust air.

  Further, the optical fiber preform manufacturing apparatus of the present embodiment is configured so as to be divided into a clad layer forming space portion 3 containing a clad burner 6 and a core layer forming space portion 4 containing a core burner 7. ing. Thus, even if a circulating flow of air from the exhaust part 35 toward the core burner 7 is generated, the circulating flow does not reach the core layer forming space 4, so that the flame 31 of the core burner 7 is disturbed. Can be reduced.

(Second embodiment)
Next, a second embodiment of the optical fiber preform manufacturing apparatus according to the present invention will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  The optical fiber preform manufacturing apparatus according to the present embodiment includes a hollow reaction vessel 51 as shown in FIG. The reaction vessel 51 includes a reaction chamber 2 in which the soot 10 is formed. The reaction vessel 1 has an air retention chamber 14 and an exhaust part 52 on one side and the other side, respectively, with the reaction chamber 2 as a center, and a soot accommodation chamber 8 above the reaction chamber 2. The air retention chamber 14 is formed by a filter 13 and a partition provided on the entire one end surface of the reaction chamber 2. The exhaust part 52 has an exhaust port 35a at the center of the other end surface, and the cross-sectional area of the exhaust path 36 is reduced from the reaction chamber 2 side to the exhaust port 35a. The upper surface wall 1 a of the reaction vessel 1 is formed in a horizontal direction from the air retention chamber 14 to the reaction chamber 2, and is inclined downward at the exhaust part 52.

  The reaction chamber 2 is provided with a burner 6 for cladding and a burner 7 for core. A first horizontal baffle plate 19 is provided above the cladding burner 6 which is one side of the reaction chamber 2. On the other hand, below the cladding burner 6, a second horizontal baffle plate 21 is provided. The second horizontal baffle plate 21 is set at a height position close to the cladding layer formation region A. Further, a fifth horizontal baffle plate 53 is provided between the second horizontal baffle plate 21 and the core burner 7. The fifth horizontal baffle plate 53 is set at a height position close to the core layer formation region B.

  Each of the horizontal baffles 19, 21 and 53 has notches 19a, 21a and 53a, respectively. Each notch 19a, 21a, 53a has a radius corresponding to the diameter of the soot 10, so that the amount of air leaking from a gap with the soot 10 is minimized.

  On the other hand, a third horizontal baffle plate 23 and a fourth horizontal baffle plate 24 are provided on the other side of the reaction chamber 2. Each of the horizontal baffles 23 and 24 is set at the same height position as the horizontal baffles 19 and 21 described above. Each of the horizontal baffles 23 and 24 has cutouts 23a and 24a, and the cutouts 23a and 24a surround a part of the trunk of the soot 10. Each of the notches 23a and 24a has a radius corresponding to the diameter of the soot 10.

  Further, a shielding plate 54 is provided in the exhaust path 36 of the exhaust unit 52. The shielding plate 54 is disposed in a horizontal direction from the lower surface wall of the exhaust path 36, and blocks a circulating flow of air toward the core burner 7. Other configurations are the same as those of the first embodiment.

  In the above configuration, the operation of the optical fiber preform manufacturing apparatus will be described. First, a seed rod (not shown) is attached to the pulling device, and set so that the lower end of the seed rod is located in the core layer forming region B. Thereafter, the first blower 17 and the second blower 18 are driven, and the air in the atmosphere is supplied to the first air holding portion 15 and the second air holding portion 16 of the air holding chamber 14, respectively. Then, relatively high-speed air is sent from the first air holding section 15 to the reaction chamber 2, while relatively low-speed air is sent from the second air holding section 16 to the reaction chamber 2. This allows high-speed air to flow near the upper surface wall 1a, thereby preventing glass particles from adhering to the upper surface wall 1a.

  The air sent from the second air retaining section 16 to the reaction chamber 2 is smoothly moved in the horizontal direction to the other side of the reaction chamber 2 by the first to third horizontal baffles 19, 21 and 53. Then, a part of the air blows against the clad burner 6 and the core burner 7 to cool both the burners 6 and 7. Part of the air flows into the cladding layer forming region A and the core layer forming region B. Thereafter, the flow direction is regulated in the horizontal direction by the third horizontal baffle plate 23 and the fourth horizontal baffle plate 24 arranged on the other side of the reaction chamber 2, and the air is exhausted to the outside through the exhaust part 35.

  When the air is supplied to the cladding layer forming space 3 as described above, the core burner 7 and the cladding burner 6 are ignited at a predetermined timing, and the flames 31 and 30 containing glass particles are formed in the core layer forming region. B and the cladding layer formation region A are ejected. Then, the soot 10 having a predetermined diameter (layer thickness) is formed by pulling up the glass particles while being attached and deposited.

  By the way, when the flames 30 and 31 of the burners 6 and 7 are jetted toward the cladding layer forming region A and the core layer forming region B, the air flowing in the reaction chamber 2 in the horizontal direction becomes the respective forming regions A and B. When passing through the vicinity, the flames 30 and 31 are thermally expanded by heating of the flames 30 and 31 and rise. However, in the rising direction of the air, three stages of first, second and third horizontal baffles 19, 21 and 53 are provided on the upstream side when viewed from the soot 10, and two stages of third and third horizontal baffles 19, 21 and 53 are provided. Four horizontal baffles 23 and 24 are provided downstream from the soot 10. Therefore, when the air rises, the air collides with the first to fifth horizontal baffles 19, 21, 23, 24, 53, and the rise of the air is suppressed. Further, the upstream all-horizontal baffles 19, 21, 23, 24, 53 narrow the gap with the soot 10 by the cutout portions 19a, 21a, 23a, 24a, 53a corresponding to the diameter of the soot 10. Thereby, the rise of air in the entire reaction chamber 2 is further suppressed.

  As a result, the rise of air is suppressed by the first to fifth horizontal baffles 19, 21, 23, 24, 53 and the notches 19a, 21a, 23a, 24a, 53a. Collapse is prevented. Further, the shielding plate 54 prevents the circulating flow from the exhaust part 52. As a result, the rise and turbulence of the flames 30 and 31 of the burners 6 and 7 due to the upward flow of air can be suppressed, so that the clad layer 12 and the core layer 11 are formed of stable glass particles having a large density. Will be. Other operations are the same as those of the first embodiment.

  As described above, the present invention has been described in the above preferred embodiments, but the present invention is not limited thereto. It will be understood that various embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, the operation and effect of the configuration of the present invention are described, but these operation and effect are only examples and do not limit the present invention.

It is a schematic structure figure of an optical fiber preform manufacturing device. FIG. 2 is a cross-sectional view taken along line XX of FIG. It is a schematic structure figure of an optical fiber preform manufacturing device. FIG. 2 is an explanatory view of a cross section taken along line YY of FIG. 1. FIG. 2 is an explanatory view of a cross section taken along line YY of FIG. 1.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Reaction container 2 Reaction chamber 3 Cladding layer formation space part 4 Core layer formation space part 5 Partition wall 6 Clad burner 7 Core burner 8 Soot accommodation room 10 Soot 11 Core layer 12 Clad layer 13 Filter 14 Air retention chamber 15 First Air retention section 16 Second air retention section 17 First blower 18 Second blower 19 First horizontal baffle 20 Wind direction plate 21 Second horizontal baffle 23 Third horizontal baffle 24 Fourth horizontal baffle 30 Flame 31 Flame 35 Exhaust Part 36 Exhaust path 38 Pull-up mechanism 39 Seed rod 51 Reaction vessel 52 Exhaust part 53 Fifth horizontal baffle 54 Shielding plate

Claims (15)

An optical fiber preform manufacturing apparatus for depositing glass fine particles to form a soot having a double cylindrical structure including a core layer and a clad layer,
A reaction vessel including a reaction chamber in which the soot is formed, and a gas in which gas flows horizontally from one side of the reaction chamber to the other side,
A core burner for forming the core layer by ejecting a flame containing the glass particles from one side of the reaction chamber toward a core layer forming region,
By blowing a flame containing the glass particles from one side of the reaction chamber toward the clad layer forming region, a clad burner for forming the clad layer around the core layer,
A pull-up mechanism that pulls up while rotating the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively.
An optical fiber preform manufacturing apparatus, comprising: a horizontal baffle plate disposed on one side of the reaction chamber and above a position where the clad burner is disposed. The horizontal baffle is
The optical fiber preform manufacturing apparatus according to claim 1, wherein a cutout portion is formed so as to surround a part of a trunk portion of the soot. The horizontal baffle is
2. The optical fiber preform manufacturing according to claim 1, wherein the optical fiber preform has a multi-stage structure in which at least one is disposed above the clad burner and between the clad burner and the core burner. apparatus. The horizontal baffle of each stage is
The optical fiber preform manufacturing apparatus according to claim 3, wherein a cutout portion is formed so as to surround a part of a trunk portion of the soot.   The optical fiber preform manufacturing apparatus according to claim 4, wherein the cutout portions of the horizontal baffle plates in each of the stages are set to have a size corresponding to the diameter of the soot in each stage.   The airflow direction plate which changes the flow direction of gas in the reaction chamber from the width direction outside of the reaction chamber to the inside where the soot is located, has a wind direction plate. An optical fiber preform manufacturing apparatus according to the above. An optical fiber preform manufacturing apparatus for depositing glass fine particles to form a soot having a double cylindrical structure including a core layer and a clad layer,
A reaction vessel including a reaction chamber in which the soot is formed, and a gas in which gas flows horizontally from one side of the reaction chamber to the other side,
A core burner for forming the core layer by ejecting a flame containing the glass particles from one side of the reaction chamber toward a core layer forming region,
By blowing a flame containing the glass particles from one side of the reaction chamber toward the clad layer forming region, a clad burner for forming the clad layer around the core layer,
A pull-up mechanism that pulls up while rotating the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively.
An optical fiber preform manufacturing apparatus, comprising: a horizontal baffle plate provided on the other side of the reaction chamber and above a position where the clad burner is provided. The horizontal baffle is
The optical fiber preform manufacturing apparatus according to claim 7, wherein a cutout portion is formed so as to surround a part of a trunk portion of the soot. The horizontal baffle is
8. The optical fiber preform manufacturing according to claim 7, wherein a plurality of stages are provided, one or more of which are respectively disposed above the clad burner and between the clad burner and the core burner. 9. apparatus. The horizontal baffle of each stage is
The optical fiber preform manufacturing apparatus according to claim 9, wherein a cutout portion is formed so as to surround a part of a trunk portion of the soot. An optical fiber preform manufacturing apparatus for depositing glass fine particles to form a soot having a double cylindrical structure including a core layer and a clad layer,
A reaction vessel comprising a reaction chamber in which the soot is formed, and a reaction vessel in which gas flows horizontally from one side to the other side in the reaction chamber,
A core burner for forming the core layer by ejecting a flame containing the glass particles from an upstream side of the gas toward a core layer forming region,
By burning the flame containing the glass particles from the upstream side of the gas toward the clad layer forming region, a clad burner that forms the clad layer around the core layer,
A pull-up mechanism that pulls up while rotating the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively.
An optical fiber preform manufacturing apparatus, comprising: a first gas delivery mechanism for causing gas traveling near the upper wall of the reaction chamber to flow faster than gas traveling in other parts.   The optical fiber preform manufacturing apparatus according to claim 11, wherein a shield plate for reducing a circulating flow of gas to the core burner is provided on the other side of the reaction chamber when viewed from the soot. . The reaction chamber is
The optical fiber preform manufacturing apparatus according to claim 11, wherein the optical fiber preform manufacturing apparatus is divided into a cladding layer forming space accommodating a clad burner and a core layer forming space accommodating a core burner. An optical fiber preform manufacturing apparatus for depositing glass fine particles to form a soot having a double cylindrical structure including a core layer and a clad layer,
A reaction vessel comprising a reaction chamber in which the soot is formed, and a reaction vessel in which gas flows horizontally from one side to the other side in the reaction chamber,
A core burner for forming the core layer by ejecting a flame containing the glass particles from an upstream side of the gas toward a core layer forming region,
By burning the flame containing the glass particles from the upstream side of the gas toward the clad layer forming region, a clad burner that forms the clad layer around the core layer,
A pull-up mechanism that pulls up while rotating the soot so that the tip and the trunk of the soot are located in the core layer forming region and the cladding layer forming region, respectively.
A horizontal baffle horizontally disposed in the reaction chamber so as to maintain a horizontal flow direction of the gas in the reaction chamber,
A first gas delivery mechanism that causes the gas traveling near the top wall of the reaction chamber to flow at a higher speed than the gas traveling through other parts,
The optical fiber preform manufacturing apparatus according to claim 1, wherein the reaction chamber is divided into a clad layer forming space containing a clad burner and a core layer forming space containing a core burner.   The optical fiber according to any one of claims 1 to 14, further comprising an exhaust unit disposed on the other side in the reaction chamber and having an exhaust cross-sectional area gradually reduced to an exhaust port. Base material manufacturing equipment.

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