JP2006248824A - Method and apparatus for manufacturing glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing glass, whereby working efficiency is improved and soot can be removed without getting any bubbles mixed in the glass. <P>SOLUTION: In the method for manufacturing a glass preform for an optical fiber, while rotating a tubular structure comprising at least a glass pipe 11 and an exhaust pipe 12 around its central axis and feeding gas containing a glass material to the tubular structure from the glass-pipe side, the glass pipe is heated from outside to form glass soot which is deposited on the inner wall of the glass pipe to form a glass layer. Here, a gas-introducing tube 17 is inserted into the exhaust tube to introduce gas from the gas-introducing tube, and the soot deposited on the inner wall of the exhaust tube is sucked by a suction tube 16. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a glass manufacturing method, and more particularly, to a method for manufacturing an optical fiber preform by an internal CVD method in which bubbles or the like are less likely to be mixed into the optical fiber preform and an apparatus for manufacturing the same.

As one method for manufacturing an optical fiber preform, there is an internal CVD (Chemical Vapor Deposition) method.
In the internal CVD method, a glass pipe and an exhaust pipe are coaxially attached to form a tubular structure, and a reactive gas such as SiCl ₄ , GeCl ₄ , POCl _{3 and the} like is formed in the tubular structure from the glass pipe side. A glass raw material containing gas composed of oxygen gas is introduced and heated from the outside of the glass pipe. As a result, the reactive gas is oxidized and becomes particulate glass soot and adheres to the inner wall of the glass pipe. The adhering glass soot is heated to a high temperature to be vitrified, and a glass layer having a higher or lower refractive index than that of the glass pipe is formed.
In this way, a solidified optical fiber preform is manufactured by forming a number of glass layers.

  However, not all of the glass soot adheres to the glass pipe, but is carried and deposited in the exhaust pipe by the flow of the glass raw material containing gas. Thus, the glass soot deposited in the exhaust pipe becomes soot, which closes the exhaust pipe and causes the glass pipe to burst.

Therefore, conventionally, a method of preventing a soot from adhering to the inside of the exhaust pipe by using a thermophoresis effect by heating a part or the whole of the exhaust pipe with an auxiliary burner, or a time when one glass layer is formed. In addition, the exhaust pipe is cooled, a rod-shaped body such as a metal is inserted into the exhaust pipe, the soot in the exhaust pipe is scraped, the supply of the glass raw material containing gas is once stopped, and the glass raw material containing gas is supplied again. A method of blowing off the soot scraped out of the exhaust pipe with the glass raw material-containing gas, a method of chemically etching the exhaust pipe (see Patent Document 1), a method of dissolving soot using HF (see Patent Document 2), etc. Has been proposed.
However, in recent years, with the advancement of technology, the production rate of glass has been increased. Particularly, regarding the production of optical fiber preforms, production is performed at a high rate of 1.0 g / min or more. There was a problem that the effect of removing soot was small and the production speed could not be accommodated.

Therefore, a method has been proposed in which a suction pipe is inserted into the exhaust pipe and soot is discharged outside the exhaust pipe (see Patent Document 3).
However, in the method of discharging the soot out of the exhaust pipe using the suction pipe, if the suction pipe is used for suction near the joint between the glass pipe and the exhaust pipe where the soot is most likely to accumulate, the tip of the suction pipe The vicinity of the part is locally in a negative pressure state. For this reason, the exhaust gas flows backward from the exhaust port side of the exhaust pipe toward the vicinity of the tip of the suction pipe. There was a problem that the soot was carried to the glass pipe portion as a product by riding on this back flow, and bubbles were generated.

  In addition, when the optical fiber preform is manufactured by the internal CVD method, a part of the glass pipe is softened because the deposited glass soot is melted to form a glass layer. Normally, nitrogen gas or the like is introduced from both ends of the glass pipe so that the softened part of the glass pipe does not collapse. However, the nitrogen gas on the exhaust pipe side is exhausted from the suction pipe as described above. The effect of introducing such as becomes low, the glass pipe will be crushed. Therefore, especially when the exhaust pipe side of the glass pipe has been softened, the heating of the glass pipe must be stopped once, and the soot must be removed by inserting the suction pipe after the glass pipe has cooled, There was a problem that work efficiency was bad.

JP 2003-12338 A JP 2002-114534 A JP 2003-176148 A

  Therefore, it has been desired to develop a glass manufacturing method and a glass manufacturing apparatus capable of improving the working efficiency and removing soot without bubbles or the like being mixed into the glass.

The present invention has been made to solve the above problems, and specifically has the following configuration.
(1) Rotating a tubular structure including at least a glass pipe and an exhaust pipe around the central axis of the tubular structure, and supplying the glass raw material-containing gas into the tubular structure from the glass pipe side, the glass pipe In the manufacturing method of the optical fiber preform, the glass soot is generated by heating from the outside, and the glass soot is deposited in the glass pipe to form a glass layer on the inner surface of the glass pipe. Soot deposited in the exhaust pipe by one or a plurality of suction pipes inserted into the exhaust pipe while introducing gas from the gas introduction pipe inserted in the exhaust pipe during or before or after the glass layer formation. It is the manufacturing method of the glass characterized by attracting | sucking.
In the present invention, by adopting the configuration of (1), the soot accumulated in the exhaust pipe is prevented from moving into the glass pipe due to the backflow of gas from the exhaust port side generated in the exhaust pipe, The soot accumulated in the exhaust pipe can be efficiently removed.
(2) The method for producing glass according to (1) above, wherein the distance between the suction port of the one or more suction tubes and the gas introduction port of the gas introduction tube is within 30 mm.
The present invention employs the configuration (2) to suppress the generation of local negative pressure due to suction by the suction pipe, and to reduce the speed of the back flow of gas from the exhaust port side generated in the exhaust pipe. It has the action.
(3) The method for producing glass according to (1) or (2) above, wherein the gas introduced through the gas introduction pipe contains one or more selected from N ₂ , O ₂ , and He. It is.
In the present invention, by adopting the configuration of (3) above, even if the gas introduced from the gas introduction pipe into the glass pipe enters the glass pipe, the gas introduced from the gas introduction pipe and the glass raw material It does not react with the contained gas, and has an effect that the influence on the production of glass is small.
(4) The method for producing glass according to any one of (1) to (3), wherein the gas introduced through the gas introduction tube contains a molecule having a fluorine atom.
The present invention has the effect of making the soot lump accumulated in the exhaust pipe fine and easy to suck by adopting the configuration of (4).
(5) The gas introduced through the gas introduction pipe has a moisture content in the gas of 5 wtppm or less, and the glass according to any one of (1) to (4), It is a manufacturing method.
By adopting the configuration (5), the present invention has the effect of preventing moisture from entering the glass pipe and increasing transmission loss of the optical fiber.
(6) The glass according to any one of (1) to (5), wherein the suction of the soot by the one or more suction tubes is started within 15 seconds after the formation of the glass layer. It is a manufacturing method.
By adopting the configuration (6), the present invention has an effect that glass can be efficiently manufactured without waiting for the soot suction operation until the glass pipe is cooled.
(7) The soot accumulated in the exhaust pipe is removed while moving the one or more suction pipes and the gas introduction pipe in the longitudinal direction of the exhaust pipe. ). The manufacturing method of the glass as described in any one of.
The present invention has an effect that the soot accumulated in the exhaust pipe can be removed throughout the exhaust pipe by adopting the configuration of (7).
(8) From the above (1) to (7), the soot sucked from the one or more suction pipes is accommodated in a soot box, and the pressure fluctuation in the soot box is 100 Pa / s or less. ). The manufacturing method of the glass as described in any one of.
This invention has the effect | action of suppressing the penetration | invasion of a soot into a glass tube by employ | adopting the structure of said (8).
(9) The soot accumulated in the exhaust pipe is sucked by one or a plurality of suction pipes inserted into the exhaust pipe while introducing the gas from the gas introduction pipe so that the glass pipe is not deformed. It is the manufacturing method of the glass as described in any one of Claim 1 to 8.
By adopting the configuration (9), the present invention has the effect that soot can be sucked without deforming the glass pipe, so that glass of good quality can be produced.
(10) The glass manufacturing method according to any one of (1) to (9), wherein the one or more suction pipes are a plurality of suction pipes.
The present invention has an effect that soot can be sucked efficiently by adopting the configuration (10) and using a plurality of suction pipes.
(11) A mechanism for rotating a tubular structure including at least a glass pipe and an exhaust pipe around its central axis, a mechanism for supplying a glass raw material containing gas into the glass pipe, the glass pipe and the glass raw material containing gas Are heated from the outside of the glass pipe, a gas introduction pipe for introducing a pressure adjusting gas into the exhaust pipe, and a suction pipe for sucking the soot accumulated in the exhaust pipe. It is a glass manufacturing device.
This invention has the effect | action that a glass with few bubbles can be manufactured efficiently by employ | adopting the structure of said (11).

According to the glass manufacturing method of the present invention, it is possible to manufacture glass with high work efficiency and few bubbles.
In particular, in the production of an optical fiber preform, a large optical fiber preform can be efficiently produced by the internal CVD method, and a high-quality optical fiber preform can be produced.

In the method of manufacturing glass by forming a glass layer on the inside of a glass pipe, the glass pipe and the exhaust pipe are connected in the longitudinal direction to create a tubular structure and rotated about the central axis of the tubular structure. However, a glass raw material containing gas is introduced from the glass pipe side of the tubular structure to form a glass layer.
Further, in the production of the optical fiber preform, the glass pipe is a portion that becomes the cladding of the optical fiber, and the glass layer formed inside the glass pipe becomes the optical cladding of the optical fiber or the core of the optical fiber. Part.
Hereinafter, taking the case of manufacturing an optical fiber preform as an example, the glass manufacturing method and glass manufacturing apparatus of the present invention will be described in detail.

FIG. 1 is a schematic diagram showing a general process for manufacturing an optical fiber preform using an internal CVD method. As shown in FIG. 1, a glass raw material-containing gas is supplied into a glass pipe 11 and heated by a heat source such as a plasma flame 15 from the outside of the glass pipe to form glass soot that is fine particles of glass, It accumulates inside the glass pipe. Further, when a heat source such as a plasma flame moves from the glass raw material containing gas introduction side of the glass pipe toward the exhaust pipe 12 side, a glass soot is formed by the heat of the heat source, and the heat source is from the exhaust pipe side of the glass pipe. When moving toward the glass raw material containing gas introduction side, the deposited glass soot is melted to form a glass layer. Therefore, normally, one glass layer is formed every time the heat source reciprocates once.
At this time, by-products and unreacted gas that are not used in the formation of the glass soot are exhausted through the exhaust pipe, but the soot flows on the inside of the exhaust pipe on the exhaust flow, Accumulate.

As the glass pipe 11, a quartz pipe is generally used, and glass pipes having various diameters and lengths can be used depending on the application.
As the exhaust pipe, a quartz pipe is generally used, and exhaust pipes having various diameters and lengths can be used according to the size of the glass pipe.
A tubular structure is obtained by heating and integrating the connecting portion of the glass pipe and the exhaust pipe.

The suction pipe 16 is for sucking the soot in the exhaust pipe 12 and is inserted into the exhaust pipe from the exhaust port side of the exhaust pipe, and sucks the soot accumulated inside the exhaust pipe.
There is no restriction | limiting in particular in the material of the said suction tube, For example, various materials, such as a metal, a ceramic, glass, can be used. Among these, a metal suction tube excellent in workability and strength, or a ceramic suction tube excellent in heat resistance is preferable.
The diameter of the suction tube is preferably 3 to 15 mm. If the diameter of the suction pipe is less than 3 mm, soot may clog the suction pipe. If the diameter of the suction pipe exceeds 15 mm, the degree of freedom of the suction pipe and the gas introduction pipe in the exhaust pipe is reduced, and soot removal work is reduced. It may be difficult to do.

Further, for removing soot in the exhaust pipe, only one suction pipe may be used, or a plurality of suction pipes may be used simultaneously. If the number of suction pipes is too large, the degree of freedom of the suction pipes in the exhaust pipe becomes small, and it becomes difficult to move the suction pipes. Therefore, the number of suction pipes is most preferably two or three.
When using a plurality of suction pipes, use some suction pipes to remove the soot accumulated at the connection between the glass pipe and the exhaust pipe, and move the remaining suction pipes in the longitudinal direction of the exhaust pipe while If it is used to remove the soot accumulated other than the connection portion between the pipe and the exhaust pipe, the soot can be efficiently removed.

The suction by the suction pipe is performed by the decompression device 22 connected to the suction pipe. As the decompression device, a commonly used device such as a vacuum pump, a decompression pump, or a fan can be used.
In addition, the soot sucked by the suction pipe is accommodated in a soot box 20 provided between the suction pipe 16 and the decompression device 22.

  If suction by the suction pipe is performed too rapidly, a local negative pressure is suddenly generated in the vicinity of the suction port of the suction pipe and accompanied by a fast gas flow. Therefore, it becomes a cause of entering the glass pipe. Therefore, it is preferable to suppress the pressure fluctuation in the soot box to 100 Pa / s or less, and more preferably to 30 Pa / s or less. The pressure fluctuation in the soot box can be measured by installing a pressure gauge 23 in the soot box.

The gas introduction pipe 17 reduces the local negative pressure due to suction by ejecting the gas from the gas introduction opening, thereby preventing the gas from flowing back from the exhaust opening side of the exhaust pipe and softening glass. This prevents the pipe from collapsing.
In particular, when the gas flowing backward from the exhaust pipe side of the exhaust pipe penetrates into the glass pipe vigorously, the soot accumulated inside the exhaust pipe is carried into the glass pipe and bubbles are formed in the resulting optical fiber preform. Therefore, the flow of the backflowing gas is suppressed.

The diameter of the gas introduction pipe is not particularly limited as long as it can be inserted into the exhaust pipe, but is preferably 3 to 15 mm. When the diameter of the gas introduction pipe is less than 3 mm, the generation of negative pressure due to soot suction may not be suppressed. When the diameter exceeds 15 mm, the degree of freedom of the gas introduction pipe and the suction pipe in the exhaust pipe is reduced. It may be difficult to remove the soot.
For removing soot in the exhaust pipe, only one gas introduction pipe may be used, or a plurality of gas introduction pipes may be used simultaneously as shown in FIG. If the number of gas introduction pipes is excessively large, the degree of freedom of the suction pipes in the exhaust pipe becomes small, and it becomes difficult to move the suction pipes. Therefore, the number of suction pipes is most preferably one or two.

  In addition, by providing a plate-like body 26 on the side surface of the gas introduction pipe, it is possible to scrape the soot accumulated inside the exhaust pipe using the plate-like body and facilitate the suction of the soot by the suction pipe. it can. When the plate-like body is provided in the gas introduction pipe, as shown in FIG. 4, a gas introduction port 27 is provided on a side surface of the gas introduction pipe so that the gas strikes the plate-like body 26. The soot can be prevented from adhering to the plate-like body.

As the gas introduced through the gas introduction pipe, an inert gas and / or a molecule having a fluorine atom is preferable, and N ₂ , O ₂ , He, HF, F ₂ , SF ₆ , and SiF ₄ are particularly preferable. By introducing a gas containing a molecule having a fluorine atom, the soot itself or a portion where the soot is fused can be melted and the soot can be easily sucked by the suction tube.
The gas introduced from the gas introduction pipe preferably has a moisture content of 5 wtppm or less. If the moisture content in the gas exceeds 5 wtppm, moisture may be mixed into the glass to be produced, which may increase transmission loss. Specific methods for reducing the moisture content in the gas to 5 wtppm or less include a method using a gas whose moisture has been adjusted in advance, or dehydrating the gas through a dehydrating agent such as potassium hydroxide, silica gel or calcium chloride. For example, there is a method of introducing the produced gas using a gas introduction pipe.

The distance between the suction port of the suction tube 16 and the gas introduction port of the gas introduction tube 17 is preferably within 30 mm. When the distance exceeds 30 mm, local negative pressure is generated by suction by the suction pipe, and gas may flow backward from the exhaust port side of the exhaust pipe. Therefore, when sucking soot while moving the suction pipe in the longitudinal direction of the exhaust pipe, it is preferable to move the gas introduction pipe at the same time.
In addition, as shown in FIG. 3, the suction tube and the gas introduction tube are previously fixed in a bundle so that the distance between the suction port of the suction tube and the gas introduction port of the gas introduction tube is within 30 mm. You can also. Thereby, the distance between the suction port of the suction tube and the gas introduction port of the gas introduction tube does not change, and the generation of a local negative pressure near the suction port can be suppressed. In particular, as shown in FIG. 4, if a plurality of gas inlets are provided for one gas inlet tube, even if a plurality of suction tubes are used, the suction ports of the respective suction tubes It is preferable because the distance to the gas introduction port is shortened, the pressure of the gas introduced from each gas introduction port is weakened, and soot can be suppressed from dancing with the gas introduced from the gas introduction tube. Further, by configuring the gas inlet so as to blow on the soot scraping blade 26, it is possible to prevent the soot from adhering to the soot scraping blade 26.

In the glass manufacturing method of the present invention, by using the suction pipe and the gas introduction pipe in combination, it is possible to prevent soot from being mixed into the glass as a product due to the backflow of gas from the exhaust port side of the exhaust pipe, By introducing the gas introduced from the gas introduction pipe, it is possible to prevent the softened glass pipe from being crushed.
Therefore, since the soot removal operation can be performed without waiting for the glass pipe to be cooled, the work efficiency in the glass manufacturing process can be improved.
Therefore, the cooling time of the glass pipe, which required 30 seconds or more in the conventional method, is not necessary, and soot removal work can be performed within 15 seconds after the formation of the glass layer. So that the soot removal operation can be performed before the deposition of the glass film is started again. In particular, when the suction pipe and the gas introduction pipe are made of ceramic with high heat resistance, the soot removal operation can be performed even immediately after the formation of the glass layer where the portion near the exhaust pipe of the glass pipe is most softened. Yes.

  By controlling the movement of the heat source such as the plasma flame 15, the movement of the suction pipe 16, and the movement of the gas introduction pipe 17 together using the computer 24, the heat resistance of the suction pipe and the gas introduction pipe is low. Even in this case, the soot removal operation can be performed without deteriorating the suction pipe and the gas introduction pipe, and without stopping the heating by the heat source and providing a cooling time. Specifically, the heat source moves from the glass raw material-containing gas inlet to the exhaust pipe side and deposits a glass film, and the heat source reaches the vicinity of the connection between the glass pipe and the exhaust pipe. After detecting that the glass film has been deposited and the heat source has started to return to the glass raw material containing gas inlet side, in the exhaust pipe, the soot removal work in the exhaust pipe and in the vicinity of the glass pipe and exhaust pipe connection is performed. , The suction pipe and the gas introduction pipe reciprocate on the rail 19 to suck and discharge the soot. The soot discharge operation ends before the heat source starts to deposit the next glass film.

  As a mechanism for rotating the tubular structure used in the glass manufacturing apparatus of the present invention around its central axis, a commonly used mechanism such as a glass lathe 13 can be used. By rotating the tubular structure about its central axis, a uniform glass layer can be formed in the glass pipe.

Various heating mechanisms for heating from the outside of the glass pipe used in the glass manufacturing apparatus of the present invention can be used. For example, a torch 14 that emits an oxyhydrogen flame or a plasma flame, and a gas cylinder of fuel gas ( (Not shown). The torch moves along the longitudinal direction of the glass pipe and heats the glass pipe.
In addition, as the gas introduction pipe 17 and the suction pipe 16 used in the glass manufacturing apparatus of the present invention, the above-described gas introduction pipe and suction pipe can be used.

Example 1
An exhaust pipe having a length of 500 mm and an inner diameter of 40 mm was connected to a glass pipe having a length of 20 cm and an inner diameter of 45 mm, and fixed to a glass lathe. A glass raw material containing gas was supplied from the end of the glass pipe opposite to the side where the exhaust pipe was connected, and a plasma flame was used as a heat source, and an optical fiber preform was manufactured by an internal CVD method. .
A ceramic pipe having an outer diameter of 6 mm was used for each of the suction tube and the gas introduction tube, and one suction port and one gas introduction port were provided on the end surfaces of the suction tube and the gas introduction tube, respectively.
The suction pipe is connected to a decompression pump via a soot box (trap) that contains soot, and the gas introduction pipe is connected to the nitrogen gas cylinder 21 via a dehydration pipe filled with calcium chloride and introduced from the gas introduction pipe. Nitrogen gas (water content: 5 ppm or less) was used as the gas to be produced. The fluctuation of the pressure in the soot box was 25 Pa / s.
Soot was removed by manually moving the suction pipe and the gas introduction pipe in the longitudinal direction of the exhaust pipe so that the distance between the suction opening of the suction pipe and the gas introduction pipe of the gas introduction pipe was within 30 mm.

(Example 2)
In the configuration of Example 1, the number of suction pipes 16 is two. One suction pipe is arranged along the inner wall of the exhaust pipe 12, and the other suction pipe is arranged so as to protrude from the one suction pipe on the substantially central axis of the exhaust pipe 12. The gas introduction pipe 17 was inserted into the side of the inner wall of the exhaust pipe 12 where the suction pipe was not arranged. The rest of the configuration was the same as in Example 1, and the optical fiber preform was manufactured by the MCVD method while removing the soot in the exhaust pipe. The suction pipe along the inner wall of the exhaust pipe 12 was suitable for removing soot accumulated on the lower side of the exhaust pipe 12. The suction pipe arranged on the central axis of the exhaust pipe 12 was suitable for removing soot accumulated at the connection portion between the exhaust pipe 12 and the glass pipe 11. With the configuration of Example 2, it was possible to continuously form 60 glass layers at a deposition rate of 1.4 g / min.

(Example 3)
A rail 18 is provided below the glass pipe, the plasma torch moves on the rail, and the plasma torch reciprocates on the rail at a constant cycle by automatic control by a computer. The same operation as in Example 1 was performed except that the suction pipe and the gas introduction pipe were moved by automatic control by a computer.
In order to perform soot removal work in the exhaust pipe and in the vicinity of the connection between the glass pipe and the exhaust pipe from 5 seconds after detecting that the plasma torch has started to return to the glass raw material containing gas inlet side, the suction pipe and gas in the exhaust pipe The introduction tube was reciprocated to suck out the soot. The soot discharge operation was terminated before the heat source started to deposit the next glass film.
The suction pipe and the gas introduction pipe are fixed so that the distance between the suction pipe and the gas introduction pipe is 5 mm and the tip of the suction pipe protrudes 10 mm from the tip of the gas introduction pipe. Were simultaneously moved back and forth in the longitudinal direction of the exhaust pipe. There was no deformation of the pipe.

Example 4
Example 3 is the same as Example 3 except that a mixed gas (moisture content: 5 ppm or less) having a weight ratio of 5: 1 is used as the gas introduced from the gas introduction pipe with a moisture content of nitrogen gas and hydrogen fluoride gas. The same was done.
By using a mixed gas of nitrogen gas and hydrogen fluoride gas, the soot that became a lump could be made finer, and soot could be reliably removed by the suction pipe.

(Example 5)
As shown in FIG. 4, the gas introduction tube was the same as Example 1 except that a plate-like body was provided on the side surface of the gas introduction tube and the gas introduction port was provided on the side surface of the gas introduction tube.
Since the soot accumulated in the exhaust pipe can be scratched by the plate-like body provided in the gas introduction pipe, and the soot that has become a lump can be finely divided, the suction operation is easy to perform. Further, since the gas introduced from the gas introduction tube hits the plate-like body, soot did not adhere to the plate-like body.

  The glass production method and glass production apparatus of the present invention can be used particularly for the production of optical fiber preforms.

FIG. 1 is a schematic diagram showing a general process for manufacturing an optical fiber preform using an internal CVD method. FIG. 2 is a schematic view showing an example of the main part of the method for producing glass of the present invention. FIG. 3 is a schematic diagram showing an example of the glass manufacturing apparatus of the present invention. FIG. 4 is a schematic view showing an example of a gas introduction tube used in the glass manufacturing method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Glass pipe 12 Exhaust pipe 13 Glass lathe 14 Plasma torch 15 Plasma flame 16 Suction pipe 17 Gas introduction pipe 18 Heat source rail 19 Suction pipe and gas introduction pipe rail 20 Soot box 21 Gas cylinder 22 Pressure reducing device 23 Pressure gauge 24 Computer 25 Glass raw material Contained gas cylinder 26 Plate 27 Gas outlet

Claims (11)

A tubular structure composed of at least a glass pipe and an exhaust pipe is rotated around the central axis of the tubular structure, and a glass raw material-containing gas is supplied from the glass pipe side into the tubular structure, and from the outside of the glass pipe. In the method for producing an optical fiber preform, the glass soot is produced by heating, the glass soot is deposited in the glass pipe, and a glass layer is formed on the inner surface of the glass pipe. Soot accumulated in the exhaust pipe is sucked by one or a plurality of suction pipes inserted in the exhaust pipe while introducing gas from a gas introduction pipe inserted in the exhaust pipe during or around A glass production method characterized by the above. The method for producing glass according to claim 1, wherein a distance between the suction port of the one or more suction tubes and the gas introduction port of the gas introduction tube is within 30 mm. The method for producing glass according to claim 1 or 2, wherein the gas introduced through the gas introduction pipe contains one or more selected from N ₂ , O ₂ , and He. The method for producing glass according to any one of claims 1 to 3, wherein the gas introduced by the gas introduction pipe contains a molecule having a fluorine atom. The method for producing glass according to any one of claims 1 to 4, wherein the gas introduced through the gas introduction pipe has a water content of 5 wtppm or less in the gas. 6. The method for producing glass according to claim 1, wherein the suction of the soot by the one or the plurality of suction pipes is started within 15 seconds after the formation of the glass layer. 7. The soot accumulated in the exhaust pipe is removed while moving the one or more suction pipes and the gas introduction pipe in the longitudinal direction of the exhaust pipe. The manufacturing method of glass as described in any one of. The soot sucked from the one or a plurality of suction pipes is accommodated in a soot box, and the pressure fluctuation in the soot box is 100 Pa / s or less. The manufacturing method of glass as described in any one of. The soot accumulated in the exhaust pipe is sucked by one or a plurality of suction pipes inserted into the exhaust pipe while introducing the gas from the gas introduction pipe so that the glass pipe is not deformed. The manufacturing method of the glass as described in any one of 1 to 8. The method for producing glass according to claim 1, wherein the one or more suction tubes are a plurality of suction tubes. A mechanism for rotating a tubular structure consisting of at least a glass pipe and an exhaust pipe around its central axis, a mechanism for supplying a glass raw material-containing gas into the glass pipe, the glass pipe and the glass raw material-containing gas. A glass production comprising a mechanism for heating from the outside of a glass pipe, a gas introduction pipe for introducing a pressure adjusting gas into the exhaust pipe, and a suction pipe for sucking soot accumulated in the exhaust pipe apparatus.

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