JP3370917B2 - Apparatus and method for manufacturing glass preform for optical fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for eliminating foreign substances and the like from a line for feeding raw materials and gases in manufacturing glass preforms for optical fibers (preforms) so as to avoid mixing into products. Alternatively, the present invention relates to a technique for preventing agglomeration, clogging, or a large pulsating flow of a raw material in a gas line.

[0002]

2. Description of the Related Art Conventionally, in an optical fiber manufacturing process,
If you try to make an ultra-fine optical fiber directly, it is difficult to control to have an optimum refractive index distribution. For this reason, first, make a thick glass preform with the same refractive index (preform), A method of manufacturing an ultrafine optical fiber by heating this glass preform and stretching it thin and long while controlling the outer diameter to a constant value is adopted.

Here, as a method for producing a glass base material, for example, a VAD method (vapor phase axis attaching method), a CVD method (chemical vapor deposition method) and the like are known. The former VAD method is a quartz rod. While rotating, the raw materials such as silicon tetrachloride (SiCl ₄ ) and germanium tetrachloride (GeCl ₄ ) are sprayed from below the quartz rod together with H ₂ and O ₂ gas to cause flame hydrolysis reaction with an oxyhydrogen burner. The soot-like reaction product (SiO ₂ ) is axially deposited below the quartz rod, and the quartz rod is rotated and pulled upward to form a glass preform.

In the latter CVD method, a so-called internal CVD method in which a reaction product is deposited on the inner peripheral surface of a quartz tube and then the quartz tube is crushed, and a reaction product in the radial direction on the outer peripheral surface of the quartz rod are used. There is known a so-called external CVD method in which a quartz rod is pulled out and crushed after depositing, but in the case of the external CVD method as well as the VAD method, a silicon tetrachloride (SiCl ₄ ) from an oxyhydrogen burner, Germanium tetrachloride (GeCl ₄ )
The above raw materials are sprayed together with H ₂ and O ₂ gas.

In the case of these VAD method and external CVD method, raw material lines for feeding raw materials such as silicon tetrachloride (SiCl ₄ ) and germanium tetrachloride (GeCl ₄ ) and H ₂ gas and O ₂ . ₍₂₎ Each gas line for feeding gas is connected to a burner facing the inside of the chamber so that the glass base material can be produced.However, the production of the base material is completed and the feed of raw material and gas is completed. When you stop paying,
The raw material and gas remaining in each line are discharged by line purging.

[0006]

By the way, while the supply of the raw material and the gas is stopped as described above, foreign matter such as soot enters from the tip of the burner into the line, or the wall surface is cleaned during the cleaning of the chamber. If foreign matter such as fine particles adhering to the air flies in the chamber and enters the line from the burner tip, the foreign matter cannot be discharged only by the line purge. There is a problem that it is often necessary to clean the inside of the base material, because if it jumps out of the line during manufacturing, it will cause bubbles and the like in the base material.

Further, during the operation of manufacturing the glass preform, the raw material may coagulate in the piping of the gas line, may be clogged, or may be retained at a turning angle, or a large pulsating flow of the raw material and gas may occur. As a result, there have been problems such as striae occurring in the product preform and fluctuations in the outer diameter.

Therefore, an attempt was made to prevent a large pulsating flow of raw materials and gas by providing a buffer tank or the like in the middle of the line, but a large pulsating flow cannot be sufficiently absorbed in a tank with a small capacity, and conversely. If the tank capacity is too large, there is a problem in that, when the supply of the raw material is stopped, it takes too much time for purging and the operating rate of the manufacturing apparatus is greatly reduced.

Therefore, according to the present invention, even if foreign matter such as soot enters from the tip of the burner, for example, the foreign matter in the line is removed before the glass preform is produced in the manufacturing process of the glass preform to produce the product. An object of the present invention is to provide an apparatus and a method for manufacturing a glass base material for an optical fiber, which can prevent deterioration of quality.

Another object of the present invention is to prevent striking, clogging, retention or large flow pulsation of the raw material in the raw material line or gas line during operation to generate striae in the product. First, it is an object of the present invention to provide a manufacturing apparatus and a manufacturing method of a glass base material for an optical fiber, which can prevent fluctuations in the outer diameter and the like.

[0011]

In order to solve the above-mentioned problems, the present invention provides a fiber raw material and a reaction gas from a burner connecting a raw material line and a gas line toward the surface of a base material. In a manufacturing device in which a soot-like reaction product is sprayed onto a predetermined portion of the base material to manufacture a glass preform for optical fibers, the raw material line and the gas line are vibrated or shaken by a vibration generation device. To be motivated,
According to the third aspect of the present invention, the raw material line and the gas line are vibrated or oscillated while the production is stopped or the line is purged.

By vibrating or swinging the line in this way, even if foreign matter or the like adheres to the wall surface in the line, it can be peeled off and lifted,
Easily discharged outside the line during line purging.

As the means for generating vibrations, for example, when the rigidity of the line is high, it is appropriate to vibrate with a vibration generator, but when the line is made of a flexible material such as a hose. May be rocked using a rocking generator or the like.

Further, such vibration generating means is VA
Not only when the reaction product is deposited below the substrate (quartz rod) as in the D method, but also when the reaction product is deposited around the substrate (quartz rod) as in the external CVD method. It can be applied.

Further, the fiber raw material and the reaction gas are blown from the burner connecting the raw material line and the gas line toward the surface of the base material, and the soot-like reaction product is deposited on a predetermined portion of the base material to emit light. In a manufacturing apparatus adapted to manufacture a glass preform for fibers, a raw material line and a gas line, a flow rate control mechanism, a pressure booster, or a high-pressure gas source, a large flow rate for discharging residual raw materials, foreign matters, etc. in the line, or A high-pressure gas purge line was connected, and with this device, a large flow rate or high-pressure purge gas was periodically circulated through the raw material line and the gas line while the production was stopped or the line was purged.

The large-flow or high-pressure gas purge line is provided separately from the conventional line purge for the purpose of discharging the raw material and gas remaining in the line, and is large for the purpose of discharging foreign matters and the like in the line. Increase the flow rate or pressure.
Further, at this time, if this purge gas is circulated at the same time as the conventional line purge, it becomes a larger flow rate or a higher pressure purge gas, and a synergistic effect can be obtained.

Further, in claim 2 , a device provided with a large flow rate or high pressure purge gas is combined with a device provided with a means for generating vibrations and the like, and in claim 4 , a large flow rate or high pressure gas is supplied to the raw material line and the gas line. The method of circulating the purge gas and the method of applying vibration to each of these lines were combined. That is, foreign matter or the like adhering to the wall surface in the line is peeled off and lifted up by the means for generating vibrations and the like is discharged with a large flow rate or high-pressure purge gas, so that the foreign matter or the like in the line can be efficiently discharged.

According to a fifth aspect of the present invention, the fiber raw material and the reaction gas are blown from the burner connecting the raw material line and the gas line toward the surface of the base material, and the predetermined portion of the base material is blown. In a manufacturing method in which a soot-like reaction product is deposited to manufacture a glass preform for an optical fiber, the raw material line and the gas line are continuously vibrated or oscillated by a vibration generation means during a manufacturing operation. The raw material is prevented from agglomerating and clogging in the line, or a large pulsating flow is prevented.

By vibrating or swinging the line during the manufacturing operation as described above, it is possible to prevent the raw material from agglomerating, clogging, or a large pulsating flow in the line, and to stabilize the continuous operation. , Prevention of striae during product preform,
A great effect can be given to the prevention of fluctuation of the outer diameter of the preform.

Further, in the sixth aspect , the production method according to the third aspect , wherein the raw material and gas lines are vibrated or oscillated by the means for generating vibration while the production is stopped or the line is purged. The raw material and the manufacturing method of continuously vibrating or oscillating the gas line during the manufacturing operation described in claim 5 are combined.

Thus, if the line is vibrated or swung while the manufacturing is stopped, even if foreign matter or the like adheres to the wall surface in the line, it can be peeled off and lifted up, thus facilitating its discharge. You can In addition, during operation, it is possible to prevent agglomeration, clogging, or large pulsating flow of the raw material, the raw material in the gas line, so that glass fiber preforms for optical fibers with almost no striae or outer diameter fluctuation can be manufactured. can do.

Claims7Then, during the production stop, or
Large flow rate toward raw materials and gas lines during line purging
Or, circulating a high-pressure purge gas periodicallyProduction method
And claims5During the manufacturing operation described in
Combining with the manufacturing method of vibrating or swinging the spline
I'm sorry.

In this way, while the production is stopped or the line is being purged, residual raw materials, foreign substances, etc. are eliminated as much as possible, and the operation is restarted. During the operation, the raw material line and the gas line are continuously vibrated or rocked. By doing so, it is possible to prevent the raw material being supplied from aggregating and clogging the line, and also to prevent a large pulsating flow of the raw material and gas, so that there is no striae and the outer diameter is uniform. A glass preform for optical fibers can be manufactured.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited thereto. Here, FIG. 1 is a schematic diagram showing a configuration example in the case where a vibration generator is provided as a vibration or the like generating means in the manufacturing apparatus of the present invention, and FIG. 2 is a case where a swing generator is provided as the vibration or the like generating means. 3 is a schematic diagram showing a configuration example, FIG. 3 is a schematic diagram showing a configuration example in which a gas purge line is provided, and FIG. 4 is a schematic diagram showing a configuration example in which vibration generating means and a gas purge line are provided side by side.

The apparatus for producing a glass preform for optical fibers according to the present invention is applied to, for example, an apparatus for producing a glass preform (preform) by the VAD method (vapor phase axial attachment method), and this apparatus is shown in FIG. As described above, the chamber 1 into which the quartz rod 2 as the base material is inserted, the exhaust pipe 3 for making the inside of the chamber 1 into a vacuum state, and the tip end are arranged toward the target portion 2 a at the lower end of the quartz rod 2. A burner 4 is provided, and the burner 4 is provided with silicon tetrachloride (Si
Cl ₄ ), a raw material line such as germanium tetrachloride (GeCl ₄ ) as a dopant for controlling the refractive index, or a gas line such as H ₂ gas or O ₂ gas (raw material / gas line R, ...) Is connected. ing.

With such an apparatus, the raw material and gas are blown from the burner 4 toward the target portion 2a while rotating the quartz rod 2 to cause a flame hydrolysis reaction to cause a soot-like reaction on the surface of the target portion 2a. Product (SiO
₂ ) is deposited in the axial direction and the quartz rod 2 is pulled up to manufacture a glass preform for optical fibers.

In such a manufacturing method, when the supply of the raw material and gas from the raw material / gas lines R, ... Is stopped, the inside of the raw material / gas lines R ,. The raw material and gas remaining in the respective lines R, ... Are discharged, but the burner 4 is used when the apparatus is stopped or when the chamber 1 is cleaned.
When foreign matter, such as soot, enters the respective lines R, ... From the tip of the, it is difficult to completely remove the foreign matter and the like by the conventional line purge.

Further, during the manufacturing operation, the raw material may be agglomerated, clogged, stagnant, or the like in the gas line R, ..., And a large pulsating flow may occur, resulting in a product preform. There is an inconvenience that striae are generated inside and the outer diameter is changed.

Therefore, according to the present invention, the foreign substances and the like that have entered the raw material / gas line R, ...
It was developed mainly for the purpose of preventing stagnation and the like and preventing large pulsating flow. In the configuration example shown in FIG. 1, each line R, ... did.

As the vibration generator 5, an appropriate type such as a vibrator or an ultrasonic oscillator is used in consideration of the material and rigidity of each line R, ...
Appropriately select the frequency, etc. to effectively remove foreign substances and the like adhering to the inner wall of each line R, ..., Prevent aggregation of raw materials, clogging, retention, etc., and prevent large pulsating flow. . Then, for example, if the line purge is performed simultaneously with this vibration or after that, foreign matters and the like are discharged, but it is more effective if the line purge is performed simultaneously with the vibration. Also,
When vibration is applied during the manufacturing operation, it is possible to prevent the raw material from aggregating, clogging, stagnant, etc. and to prevent large pulsating flow.

When each line R, ... Is a flexible hose or the like, the swing generator 6 as shown in FIG. 2 is effective. The swing generator 6 may be, for example, an eccentric crank mechanism using a motor, a cam mechanism, or any other commonly used mechanism.
In this way, the foreign substances and the like adhering to the inner walls of the lines R, ... Are rocked to be stripped off and discharged by the line purge.

By the way, since it is considered that the foreign matter or the like that has entered from the tip of the burner 4 generally adheres to the inner wall of each line R, ... Near the burner 4, the vibration generator 5 or
It is considered effective that the rocking generator 6 is installed at a position near the burner 4 which is slightly inserted from the tip of the burner 4.

Next, in FIG. 3, a gas purge line P for discharging foreign matters and the like is connected to each line R, ...
From this, a large flow rate of purge gas is made to flow periodically. This large flow rate of purge gas is made to flow periodically, for example, when the raw material supply and gas supply are stopped, and if it is carried out simultaneously with the line purge for purging the residual raw material from the raw material / gas lines R ,. The flow rate can be increased to enhance the effect of discharging foreign matters and the like.

Further, such a gas purge line P, ...
Uses a pressure booster or the like instead of the flow control mechanism 7,
Alternatively, a high-pressure gas source may be used to allow a high-pressure purge gas to flow. In this case, the effect of high pressure can enhance the effect of discharging foreign matters and the like.

Next, in FIG. 4, the vibration generator 5 and the gas purge lines P, ... Are used together. In this case, it is more effective if the vibration generator 5 is used to peel off foreign matter or the like adhering to the inner walls of the lines R, ...

[0036]

EXAMPLES Next, examples and comparative examples of the present invention will be described. (Example 1) After manufacturing an optical fiber preform using the apparatus of FIG. 1, supply of raw materials and gas is stopped, and each line R, ... Is slightly vibrated at 60 Hz during the next preparation for manufacture. Line purging was performed and the following production was performed. This was repeated 10 times,
No foreign matter was found in each line R, ... Before the start of the production for 10 times, and no bubbles or foreign matter were generated or mixed in the finished product.

(Embodiment 2) Using the apparatus of FIG. 2, each line R, which is composed of a flexible tube, is made to oscillate by an oscillating generator 6, and the supply of raw materials and gas is stopped and is being prepared. The respective lines R, ... Are continuously shaken and purged during this period, and then the base material is manufactured. This was repeated 10 times, but no foreign matter or the like was found in the lines R, ... In any of the products, neither air bubbles nor foreign matter was generated or mixed in.

(Embodiment 3) After the optical fiber preform was manufactured using the apparatus shown in FIG. 3, the supply of the raw material and the gas was stopped, and 10 liters / minute was supplied every 2 minutes during the next preparation for the manufacture. min
The following production was performed by flowing a large flow rate of N ₂ gas for 5 seconds.
This was repeated 10 times, but no foreign matter was found in each line R, ... Before the start of production, and no bubbles or foreign matter were generated or mixed in the finished product. Incidentally, the conventional line purging for purging the raw materials and gas of each line R, ... Is usually performed with N ₂ gas at a flow rate of 1.5 liter / min.

(Embodiment 4) After manufacturing an optical fiber preform using an apparatus connected to a high-pressure gas purge line, supply of raw material and gas was stopped, and during the next preparation for manufacture, 5
A high-pressure N ₂ gas of 6 kg / cm ² was allowed to flow for 5 seconds at intervals to perform the next production. This was repeated 10 times, but no foreign matter was found in each line R, ... Before the start of production, and no bubbles or foreign matter were generated or mixed in the finished product. By the way, each line R, which has been used conventionally, ...
The line purging for purging the raw material and gas is usually performed with N ₂ gas at a pressure of 1 kg / cm ² .

(Comparative Example 1) After the optical fiber preform was manufactured using the conventional apparatus, the supply of the raw material and the gas was stopped, and the flow rate of 1.5 liter / min was supplied during the next preparation for the manufacture. The following production was carried out by line purging with N ₂ gas at a pressure of 1 kg / cm ² . This was repeated 5 times, but fine particles were recognized in each line R, ...
Bubbles were generated in the finished product.

From the above, if each line R, ... Is vibrated or oscillated by means for generating vibrations, etc. as in the present invention, and a large flow rate or high pressure purge gas is flown from the gas purge line P ,. It was confirmed that foreign substances could be discharged efficiently. Further, it is expected that the combined use of both will be more effective.

(Embodiment 5) Using the apparatus shown in FIG. 1, each line R, ... Is continuously vibrated slightly at 60 Hz during production to produce an optical fiber preform. ,
For all ten, no large pulsating flow was generated in the raw material flow in the raw material line, and no striae or outer diameter variation was found in the finished product.

(Comparative Example 2) An optical fiber preform was manufactured using a conventional apparatus in which the vibration generator was removed from the apparatus shown in FIG. 1. When one of the three fibers was pulled up, the flow rate of the raw material was increased. Had a large pulsation, and a slight striae was found in the area corresponding to that area.

As described above, when the respective lines R, ... Are vibrated or oscillated by the vibration generating means during the manufacturing operation, there is almost no agglomeration, clogging, retention of the raw material or pulsating flow having a large flow rate. As a result, striae were not generated in the product preform, and the outer diameter was hardly changed.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, has substantially the same configuration as the technical idea described in the scope of the claims of the present invention, and has any similar effect to the present invention. It is included in the technical scope of the invention.

[0046]

The present invention as described above, according to the present invention is as claimed in claim 1 and claim 3, by blowing the raw material and the reaction gas fiber toward the burner feed line and a gas line is connected to the surface of the substrate When manufacturing the glass preform for optical fiber, the raw material line and the gas line are
Since the vibrating or oscillating means is used to vibrate or swing, the foreign matter or the like adhering to the wall surface in each line can be peeled off and lifted up, and the purge gas can be easily discharged from the line.

Further, the raw material line and a gas line, the foreign substances in the line connecting the high flow or high pressure gas purge line for discharging, so that a large flow rate or pressure of the purge gas to feed line and the gas line is periodically circulated Even so, it is effective for discharging foreign matters. When the large flow rate or high pressure purge gas and the vibration generating means are combined as in the second and fourth aspects, the discharge effect can be further enhanced.

Further, as described in claim 5 , the raw material line and the gas line are continuously vibrated or oscillated by the means for generating vibrations during the manufacturing operation, so that the raw material in each line is agglomerated, blocked, It is possible to prevent large pulsating flow of stagnation or raw materials and gas, and as a result, manufacture glass base material for optical fiber with excellent quality characteristics without striae in the product preform and fluctuation of outer diameter. You can do it.

If claim 3 and claim 5 are combined, as in claim 6 , foreign matter or the like is peeled off and lifted up by the generating means such as vibration or rocking while the manufacturing is stopped or the line is purged. The discharge of gas is promoted, and during the production operation, it is possible to prevent agglomeration, clogging, retention of the raw material or a large pulsating flow rate, and it is possible to stabilize the operation and improve the quality throughout the production period.

Then, as described in claim 7 , the raw material line and the gas are
From the burner to which the spline is connected to the surface of the substrate,
The raw material for fiber and the reaction gas are sprayed, and the predetermined part of the base material is blown.
Glass substrate for optical fiber by depositing soot-like reaction products
Stop production in a manufacturing method that is designed to manufacture wood
Flow control mechanism, pressure booster,
Or from a high pressure gas source to the raw material line and the gas line
A large flow rate or high pressure purge gas periodically to
By combining the method for producing a glass preform for optical fibers according to claim 5 with residual raw materials, foreign substances, etc. removed during production suspension or purging of the line, during production operation In addition, it is possible to prevent agglomeration, clogging, retention of the raw material or a large pulsating flow rate, and it is possible to stabilize the operation and improve the quality throughout the manufacturing period.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example in the case where a vibration generator is provided as a vibration generating unit according to the manufacturing apparatus of the present invention.

FIG. 2 is a schematic diagram showing a configuration example in the case where a rocking generator is provided as a vibration generating unit.

FIG. 3 is a schematic diagram showing a configuration example when a gas purge line is provided.

FIG. 4 is a schematic diagram showing a configuration example in which vibration generating means and a gas purge line are provided together.

[Explanation of symbols]

1 ... Chamber, 2 ... Quartz rod,
2a ... target part, 3 ... exhaust pipe,
4 ... Burner, 5 ... Vibration generator, 6 ... Oscillation generator, 7 ... Flow control mechanism, P ... Gas purge line, R
… Raw materials and gas lines.

Front Page Continuation (72) Hideo Hirasawa Inventor Hideo Hirasawa 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd., Precision Materials Research Laboratory (56) Reference JP-A-8-81234 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C03B 37/018 C03B 8/04

Claims (7)

(57) [Claims] 1. A fiber raw material and a reaction gas are blown toward a surface of a base material from a burner connecting a raw material line and a gas line, and a soot-like reaction product is deposited on a predetermined portion of the base material to emit light. A production apparatus for producing a glass preform for fibers, wherein the raw material line and the gas line are adapted to be vibrated or oscillated by means for generating vibration or the like. Base material manufacturing equipment. 2. A raw material line and a gas line are connected to the optical fiber glass preform manufacturing apparatus according to claim 1.
From the burner to the surface of the substrate, the fiber raw material and the reaction gas
Soot-like reaction product sprayed onto a predetermined portion of the base material
To produce a glass preform for optical fiber.
Which is a manufacturing apparatus, wherein the raw material line and the gas line are
From the flow control mechanism, intensifier, or high pressure gas source, to the line
High-pressure or high-pressure gas that discharges residual raw materials and foreign substances inside
Optical fiber characterized by connecting a purge line
An apparatus for producing a glass base material for an optical fiber, which is combined with an apparatus for producing a glass base material. 3. A fiber raw material and a reaction gas are blown toward a surface of a base material from a burner connected to the raw material line and a gas line, and a soot-like reaction product is deposited on a predetermined portion of the base material to emit light. In a manufacturing method adapted to manufacture a glass preform for fibers, while the manufacturing is stopped or while the line is being purged, the raw material line and the gas line are vibrated or oscillated by a vibration generating means, and foreign substances in the line A method for manufacturing a glass preform for an optical fiber, characterized in that the discharge of the glass is promoted. 4. The method for producing a glass base material for an optical fiber according to claim 3 , and a raw material line and a gas line are connected.
From the burner to the surface of the substrate, the fiber raw material and the reaction gas
Soot-like reaction product sprayed onto a predetermined portion of the base material
To produce a glass preform for optical fiber.
In the manufacturing method,
Flow control mechanism, intensifier, or high pressure gas source
A large flow rate or a high flow rate toward the raw material line and the gas line.
It is characterized in that a pressure purge gas is periodically circulated.
A method for producing a glass preform for an optical fiber, which is combined with a method for producing a glass preform for an optical fiber. 5. A fiber raw material and a reaction gas are blown from a burner connecting a raw material line and a gas line toward the surface of a base material, and a soot-like reaction product is deposited on a predetermined portion of the base material to emit light. In a manufacturing method adapted to manufacture a glass preform for fibers, the raw material line and the gas line are vibrated or oscillated by a vibration generating means continuously during the manufacturing operation, thereby aggregating or clogging the raw material in the line. Alternatively, a method for producing a glass preform for an optical fiber, characterized in that a large pulsating flow is prevented. The manufacturing method according to claim 6 glass preform for optical fiber according to claim 3, for an optical fiber, characterized in that the process for producing a glass preform for optical fiber according to claim 5 are combined Method for manufacturing glass base material. 7. A bar to which a raw material line and a gas line are connected.
The raw material for the fiber and the reaction gas from the corner toward the surface of the substrate
To spray a soot-like reaction product on a predetermined portion of the base material.
The glass base material for optical fiber was manufactured by deposition.
In the manufacturing method, during the suspension of manufacturing or purging of the line
From the flow control mechanism, intensifier, or high pressure gas source,
High flow rate or high pressure toward the raw material line and gas line
An optical fiber characterized by circulating the purge gas periodically.
A method for producing an optical fiber glass preform, characterized in that the method for producing a glass preform for fiber and the method for producing an optical fiber glass preform according to claim 5 are combined.