WO2024166883A1 - Device for producing porous optical fiber base material - Google Patents

Abstract

This device for producing a porous optical fiber base material causes glass microparticles produced by flame hydrolysis of a starting gas to be deposited onto a starting material that is being taken up while being turned. The device is provided with a reaction chamber and a holding part for holding the burner used when depositing the glass microparticles. The holding position and/or the holding direction of the burner held by the holding part are variable. The burner attachment position and/or the attachment direction can also be varied as a result of the holding part being detachable with respect to the reaction chamber of this device for producing a porous optical fiber base material.

Description

Manufacturing equipment for porous optical fiber preform

The present invention relates to a porous glass preform manufacturing apparatus for manufacturing porous glass preform for optical fiber, for example, by the vapor-phase axial deposition (VAD) method.

There is a manufacturing apparatus for a porous base material which is "equipped with a reaction vessel 16 having an upper deposition chamber 2 having an exhaust port 5 and an air inlet 6, a lower deposition chamber 3 having an air inlet 7, and an upper chamber 4 located above the upper deposition chamber 2 for pulling up and storing the porous base material 1 formed by deposition" (for example, Patent Document 1).
[Patent Document 1] JP 2007-210837 A

One aspect of the present invention is a porous optical fiber preform manufacturing device that deposits glass particles generated by a flame hydrolysis reaction of a raw material gas onto a starting material that is pulled up while rotating. The device includes a reaction chamber and a holder that holds a burner for depositing the glass particles, and at least one of the mounting position and mounting direction of the burner can be changed in the holder.

In the above-mentioned porous optical fiber preform manufacturing apparatus, the holding part may be detachable from the reaction chamber, so that at least one of the burner holding position and holding direction may be changed. The holding part may be attached below the reaction chamber to form a sub-chamber of the reaction chamber. The reaction chamber may have two sub-chambers connected vertically by their openings, and the holding part may be attached to the lower sub-chamber to form part of the side wall of the lower sub-chamber.

In the above-mentioned porous optical fiber preform manufacturing apparatus, the holding section may have a plurality of openings capable of holding burners, and caps for closing the openings among the plurality of openings that do not hold the burners.

FIG. 2 is a schematic diagram for explaining an outline of a manufacturing apparatus for a porous optical fiber preform. 4 is a schematic diagram illustrating the seal structure between the burner and the flange surface of the burner insertion port. FIG. FIG. 2 is a schematic diagram showing an outline of an apparatus for producing a porous optical fiber preform according to the present embodiment, the reaction chamber of which is composed of two reaction compartments. FIG. 2 is a schematic diagram showing a configuration of a reaction chamber for explaining Example 1. FIG. 13 is a schematic diagram showing a configuration of a reaction chamber for explaining Comparative Example 1. FIG. 11 is a schematic diagram showing a configuration of a reaction chamber for explaining Example 2. FIG. 11 is a schematic diagram illustrating a configuration of a reaction chamber before the manufacturing conditions are considered, for explaining Example 3. FIG. 11 is an exploded perspective view of the reaction chamber of Example 3. FIG. 11 is an enlarged cross-sectional view of the reaction chamber and the reaction compartment mounting portion of Example 3. FIG. 11 is a schematic diagram illustrating a configuration of a reaction chamber that facilitates the examination of manufacturing conditions, for explaining Example 3. FIG. 11 is a schematic diagram showing a configuration of a reaction chamber for explaining Comparative Example 2. FIG. 13 is a schematic diagram showing the configuration of a reaction chamber for explaining Example 4. FIG. 13 is another schematic diagram showing the configuration of the reaction chamber for explaining Example 4.

The following describes embodiments, but is not limited to these, and various other configurations are possible.

In one embodiment of the porous optical fiber preform manufacturing apparatus, the reaction chamber is configured to have at least two reaction compartments, with the lower reaction compartment being removable and replaceable. This makes it easy to change the preform manufacturing conditions by replacing the lower reaction compartment with a reaction compartment in which, for example, the position of the first burner for depositing the cladding portion has been changed.

In yet another embodiment, the reaction chamber has an opening at its bottom, and a burner insertion plate with a burner insertion port at the opening can be removed and replaced freely. This makes it easy to change the manufacturing conditions of the base material by replacing the burner insertion plate with one that changes the positioning angle of the core deposition burner, for example.

The manufacturing device of this embodiment is configured in this way, making it possible to consider a variety of manufacturing conditions and to do so at low cost.

Figure 1 is a schematic diagram of a conventional manufacturing device for a porous optical fiber preform 12, which is equipped with a core deposition burner 13 for depositing the central core portion depicted at the bottom, a first cladding deposition burner 14 for depositing the cladding portion slightly above that, and a second cladding deposition burner 15 above that, and the soot is manufactured using multiple burners as a whole.

The core deposition burner 13 deposits glass particles generated in an oxyhydrogen flame, which is accompanied by dopant materials such as germanium tetrachloride in addition to silicon tetrachloride, onto the starting material, and then the cladding deposition burners 14 and 15 deposit the cladding so as to cover the core from the outside.

In order to minimize the intrusion of impurities into the porous optical fiber base material, to prevent corrosion of the equipment caused by hydrogen chloride produced in the flame hydrolysis reaction of the glass raw materials, and to ensure stable deposition without disturbance, deposition using the above-mentioned burners is carried out in a reaction chamber that is isolated from the outside air.

Each burner is inserted through a burner insertion port provided in the reaction chamber, and each burner insertion port must be adequately sealed to prevent outside air from being drawn in.

Figure 2 is a schematic diagram explaining the seal structure of the burner and the flange surface of the burner insertion port. A burner insertion port 51 with a flange surface is arranged on the burner installation wall of the reaction chamber, and a flexible seal member 53 with a flange surface is inserted into the cylindrical part of the burner 52. When the burner 52 is arranged, it is brought into contact with the flange surface of the burner insertion port 51 arranged on the reaction chamber side so that the contact area between the flange surface of the seal member 53 inserted into the burner 52 is maximized. In other words, it is important for sealing that the central axis of the burner 52 and the flange surface of the burner insertion port 51 are arranged so as to be perpendicular to each other.

The manufacturing device of the present invention will be specifically explained below based on examples.

Example 1
In this case, the manufacturing conditions are examined by changing the position of only the first burner for depositing the clad portion to face the burner for depositing the core portion.

In FIG. 3, reaction chamber 32 is composed of reaction compartment 21 and reaction compartment 22, which are connected by connection part 19, and reaction compartment 21 is removable and replaceable.

The reaction chamber 21 does not have a burner insertion port for placing the first burner 14 for depositing the clad portion opposite the burner 13 for depositing the core portion.

As shown in FIG. 4, another reaction chamber 23 having a first burner insertion port 14B for depositing the clad portion is prepared at a position opposite the core deposition burner 13, and is attached to the reaction chamber 22 in place of the reaction chamber 21 to create a new reaction chamber 33. Thus, in Example 1, a holding part for holding the core deposition burner 13 and the first burner for depositing the clad portion 14 is attached below the reaction chamber 22 to form the reaction chambers 21, 23, and because the holding part is detachable from the reaction chamber 22, the holding position of the first burner for depositing the clad portion 14 can be changed.

By configuring the reaction chamber in this way with two reaction compartments, the first burner 14 for depositing the clad portion can be easily moved to a position opposite the burner 13 for depositing the core portion by simply replacing reaction compartment 21 with reaction compartment 23, which reduces the cost of considering the manufacturing conditions compared to preparing an entire new reaction chamber.

Comparative Example 1
As in Example 1, this is a case in which only the first burner for depositing the cladding portion is changed to a position facing the burner for depositing the core portion, and manufacturing conditions are examined.

In FIG. 1, the reaction chamber 31 does not have a burner insertion port for changing the position of the burner for depositing the clad portion to a position opposite the first burner for depositing the clad portion 14. Therefore, it is necessary to change the design of the entire reaction chamber 31 and prepare a new reaction chamber 34 in which the first burner insertion port for depositing the clad portion 14B is moved to a position opposite that in FIG. 1, as shown in FIG. 5. This change in the design of the entire reaction chamber 31 will require extremely high costs for considering the manufacturing conditions.

Example 2
In this embodiment, the angle of the core deposition burner relative to the horizontal plane is changed from 60 degrees to 75 degrees, and manufacturing conditions are examined.

Figure 3 shows an outline of a manufacturing device that consists of a reaction chamber with two reaction compartments. In this device, the core deposition burner insertion port 13A is fixed to the reaction compartment 21 so that the angle of the core deposition burner 13 is 60 degrees, and the arrangement angle cannot be changed.

As shown in FIG. 6, another reaction chamber 24 was replaced with the reaction chamber 21, and connected to the reaction chamber 22 via a connector 19 to form a new reaction chamber 35. The core deposition burner insertion port 13C is arranged in the reaction chamber 24 so that the central axis of the core deposition burner 13, whose angle with respect to the horizontal plane has been changed from 60 degrees to 75 degrees, is perpendicular to the flange surface of the core deposition burner insertion port 13C. This allows the periphery of the burner to be sufficiently sealed as described above. Therefore, in Example 2, the holding portion that holds the core deposition burner 13 and the first clad deposition burner 14 is attached below the reaction chamber 22 to form the reaction chambers 21 and 24, and the holding portion is detachable from the reaction chamber 22, making it possible to change the holding direction of the first clad deposition burner 14.

By configuring the reaction chamber in this way as two separate reaction chambers, it is possible to change the angle of the core deposition burner 13 more easily than if an entire reaction chamber were to be prepared, thereby reducing the cost of considering manufacturing conditions.

Example 3
In this embodiment, as in the second embodiment, the angle of the core deposition burner with respect to the horizontal plane is changed from 60 degrees to 75 degrees, and manufacturing conditions are examined.

The reaction chamber 36 shown in FIG. 7 has an opening at the bottom of the reaction chamber 25, where a burner insertion plate 41 with a burner insertion port is installed. The core deposition burner insertion port 13A is fixed to the burner insertion plate 41, and the burner angle is 75 degrees.

As shown in FIG. 8, the lower part of the reaction chamber 25 forms a reaction chamber 60 connected to the upper part by an opening 27. The reaction chamber 60 has a triangular prism shape with one side open, and has a flange 62 around the opening. The flange 62 has a plurality of through holes 64. The flange 62 is attached to the bottom surface of the upper part of the reaction chamber 25, where the opening 27 is provided, via a heat-resistant sealant 70. The sealant 70 has a through hole 72 at a position corresponding to the through hole 64. As shown in FIG. 9, a bolt 74 is inserted into the corresponding through holes 64, 72, and the sealant 70 is sandwiched between the bolt 74 and the nut 76. This fixes the upper part of the reaction chamber 25 and the reaction chamber 60 while maintaining airtightness around the opening 27. This fixing method may be used in other embodiments, for example, as a fixing method using the connector 19 in FIG. 6.

The burner insertion plate 41 is attached to the side opposite the opening in the reaction chamber 60. A flange 66 is provided on this side. The side of the flange 66 facing the burner insertion plate 41 is frosted. Similarly, the area of the burner insertion plate 41 facing the flange 66 is also frosted. With the burner insertion plate 41 in contact with the flange 66, they are attached with heat-resistant tape and clipped in place with a metal clip. This fixes the burner insertion plate 41 to the flange 66 while maintaining an airtight seal.

The burner insertion plate 41 can be removed from the reaction chamber 60 by removing the clips and peeling off the heat-resistant tape. The burner insertion plate 41 is provided with a burner insertion port 13A for core deposition and a first burner insertion port 14B for clad deposition.

Furthermore, as shown in FIG. 10, another burner insertion plate 42 equipped with a core deposition burner insertion port 13C corresponding to a burner angle of 75 degrees was connected to the opening at the bottom of the reaction chamber 25 in place of the burner insertion plate 41 to form a new reaction chamber 37. Thus, in Example 3, the burner insertion plate 41 that holds the core deposition burner 13 and the first clad deposition burner 14 is attached to the reaction chamber 60 as a holding part to form part of the side wall of the reaction chamber 60, and since the holding part is detachable from the reaction chamber 60, it is an example in which the holding direction of the first clad deposition burner 14 can be changed.

In this way, by configuring the entire reaction chamber as a reaction chamber with an opening at the bottom and a burner insertion plate, it was possible to study the manufacturing conditions more easily and at lower cost than if an entire reaction chamber were to be prepared separately. In addition, by replacing the burner insertion plate 41 with a burner insertion plate that changes the holding position of the first burner 14 for depositing the clad portion, it is possible to change the holding position of the first burner 14 for depositing the clad portion.

Comparative Example 2
As in the second and third embodiments, the angle of the core deposition burners with respect to the horizontal plane is changed from 60 degrees to 75 degrees, and manufacturing conditions are examined.

In the conventional manufacturing equipment of FIG. 1, the burner cannot be positioned at 75 degrees to the horizontal plane in the core deposition burner insertion port 13A of the reaction chamber 31. To change the burner angle, it is necessary to change the overall design of the reaction chamber 31 in FIG. 1 and prepare a new reaction chamber 38 with a core deposition burner insertion port 13C that sets the burner position angle at 75 degrees, as shown in FIG. 11. Replacing this reaction chamber makes the cost of considering the manufacturing conditions extremely high.

Example 4
12 and 13 are schematic diagrams of the reaction chamber 80 in the production apparatus according to Example 4. In the production apparatus of Example 4, the structure above the reaction chamber 80 is the same as that of other examples, for example, Example 3, and therefore illustrations and explanations thereof are omitted.

The reaction chamber 80 of the manufacturing apparatus of Example 4 has two openings 81, 82 for the first burner 14 for depositing the clad portion, and one opening 83 for the burner 13 for depositing the core portion. In addition, multiple openings are provided for one first burner 14 for depositing the clad portion. In FIG. 12, the first burner 14 for depositing the clad portion is inserted into the opening 81, and the burner 13 for depositing the core portion is inserted into the opening 83.

A cap 84 is inserted into the opening 82 into which the first burner 14 for depositing the clad portion is not inserted, of the two openings 81, 82. The portion of the cap 84 that is inserted into the opening 82 and its flange portion have an outer shape that corresponds to the outer shape of the first burner 14 for depositing the clad portion and the seal member 53, for example the same outer shape. The cap 84 is formed from a heat-resistant material. This allows the opening 82 into which the burner is not inserted to be airtightly sealed.

In FIG. 13, instead of FIG. 12, the first burner 14 for depositing the clad portion is inserted into the opening 82, and a cap 84 is inserted into the opening 81. This allows the first burner 14 for depositing the clad portion to be held in a holding position different from that in FIG. 12.

According to the manufacturing apparatus of Example 4, the reaction chamber 80 has a plurality of openings 81, 82 capable of holding the first burner 14 for depositing the clad portion, and the holding position of the first burner 14 for depositing the clad portion can be changed by blocking the opening 81, 82 that is not holding the first burner 14 for depositing the clad portion with a cap 84. In addition, the holding direction of the first burner 14 for depositing the clad portion may be changed by changing the orientation of the flanges between the openings 81 and 82.

11... starting material,
12...Porous optical fiber preform,
13...Core deposition burner,
14: First burner for depositing clad portion,
15: Second burner for depositing clad portion,
13A-C: Core deposition burner insertion port,
14A, B: first burner insertion port for deposition of clad portion,
15A: second burner insertion port for deposition of clad portion,
19...connector,
21-24: Reaction chambers,
25...reaction chamber having an opening,
27...Opening,
31 to 38: reaction chamber,
41, 42 ... burner insertion plate 51 ... burner insertion port,
52...Burner,
53...sealing member,
60... reaction compartment,
62... flange,
64...through hole,
66...flange,
70...sealing material,
72 ... through hole,
74...volts,
76...Nut,
80...Reaction chamber,
81...Opening,
82...Opening,
83...Opening,
84...Cap.

Claims (5)

1. An apparatus for manufacturing a porous optical fiber preform, comprising: a starting material which is rotated and pulled up, and on which glass particles generated by a flame hydrolysis reaction of a raw material gas are deposited;
A reaction chamber;
a holder for holding a burner for depositing glass particles;
The apparatus for manufacturing a porous optical fiber preform is capable of changing at least one of the holding position and the holding direction of the burner in the holding section. The porous optical fiber preform manufacturing apparatus according to claim 1, wherein the holding part is detachable from the reaction chamber, so that at least one of the holding position and holding direction of the burner can be changed. The porous optical fiber preform manufacturing apparatus according to claim 2, wherein the holding section is attached below the reaction chamber to form a sub-chamber of the reaction chamber. The reaction chamber has two separate chambers connected vertically by openings,
3. The apparatus for manufacturing a porous optical fiber preform according to claim 2, wherein the holding portion is attached to the lower compartment and forms a part of a side wall of the lower compartment. The holding portion is
A plurality of openings capable of holding the burners;
2. The apparatus for manufacturing a porous optical fiber preform according to claim 1, further comprising a cap for closing an opening that does not hold the burner among the plurality of openings.

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