JPH0651247U - Manufacturing equipment for porous glass base material - Google Patents

Abstract

(57) [Summary] (Modified) [Object] The present invention aims to provide a manufacturing apparatus for manufacturing a porous glass base material by an external CVD method with high purity and high efficiency. The apparatus for producing a porous glass preform of the present invention produces a porous glass preform by depositing glass fine particles produced by flame hydrolysis of a gaseous glass raw material with an oxyhydrogen flame burner on a carrier. In the device, an exhaust port 4 is provided at a position facing the oxyhydrogen flame burner 2 so as to be able to reciprocate left and right in synchronization with the movement of the burner 2, and the exhaust port 4 is connected to a heat resistant flexible hose 5. It is characterized by becoming.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a porous glass base material manufacturing apparatus, and more particularly to a manufacturing apparatus for manufacturing a porous glass base material for manufacturing an optical fiber preform by an external CVD method with high purity and high efficiency.

[0002]

[Prior art]

 The production of the porous glass preform for producing the optical fiber preform has been conventionally performed by the external CVD method. For example, as shown in FIG. 3, a heat-resistant quartz glass rod or the like used as the carrier 11 is installed horizontally, and a gaseous glass raw material such as silicon tetrachloride is introduced into this while rotating it. The porous glass base material 13 is made by depositing the silica fine particles generated by the oxyhydrogen flame burner 12 that reciprocates left and right, and the exhaust gas generated by the reaction at this time is sent to the reactor 14. It is designed to be discharged from a fixedly provided exhaust port 15.

[0003]

[Problems to be solved by the device]

 However, in this conventional method, although the oxyhydrogen flame burner 12 reciprocates left and right, the exhaust port 15 is fixed, so the exhaust efficiency is poor, and it is included in the exhaust gas that is not exhausted. Since unreacted glass raw materials and dopants adhere to the porous glass preform deposited on the carrier, the optical fiber preform obtained by heating this to produce transparent vitrification There is a problem that the transmission characteristics deteriorate.

For this reason, a method of enlarging the exhaust port is also used in order to improve the exhaust efficiency, but also in this case, there is a disadvantage that a large exhaust facility is required due to the large exhaust area. Furthermore, when the exhaust port is enlarged, impurities enter from the outside, and the characteristic value of the glass decreases.

[0005]

[Means for Solving the Problems]

 The present invention relates to an apparatus for producing a porous glass base material capable of solving such disadvantages and drawbacks, which is a glass produced by flame hydrolysis of a gaseous glass raw material with an oxyhydrogen flame burner. In an apparatus for producing a porous glass preform by depositing fine particles on a carrier, an exhaust port is provided at a position facing an oxyhydrogen flame burner, and the exhaust port is connected to a heat resistant flexible hose. In a porous glass preform manufacturing apparatus characterized by reciprocating left and right in synchronization with the movement of the burner, it is possible to reciprocate left and right in synchronization with the movement of the burner at a position facing the oxyhydrogen flame burner. The present invention relates to an apparatus for producing a porous glass base material, which is provided with such an exhaust port.

That is, the inventors of the present invention have conducted various studies on an apparatus for carrying out the production of a porous glass base material by the external CVD method with high purity and efficiency, and as a result, in the conventional method, the apparatus was fixedly provided on the upper part of the reaction furnace. The exhaust port is connected to a heat-resistant flexible hose so that it can reciprocate left and right in synchronization with the movement of this burner at the position facing the oxyhydrogen flame burner. The exhaust gas generated is efficiently exhausted because its exhaust port is always in the position facing the oxyhydrogen flame burner, and unreacted glass raw materials and dopants do not adhere to the resulting porous glass base material. It was found that the desired porous glass base material can be manufactured with high purity and efficiency, and that the porous glass base material thus obtained is We completed the present invention by confirming that the optical fiber obtained by drawing the optical fiber preform made from these materials will have good transmission characteristics. This will be described in more detail below.

[0007]

[Action]

 The apparatus for producing a porous glass preform according to the present invention is an apparatus provided with an exhaust port at a position facing an oxyhydrogen flame burner in the external CVD method so that the exhaust port can reciprocate left and right in synchronization with the movement of the burner. .

FIG. 1 is a vertical sectional view of a porous glass preform manufacturing apparatus according to the present invention, and FIG. 2 is a horizontal sectional view thereof. The porous glass base material manufacturing apparatus shown in Figs. 1 and 2 is used to manufacture a porous glass base material by holding a heat-resistant carrier rod 1 such as quartz glass, silicon carbide, or carbon horizontally in a furnace. The silica glass fine particles produced by flame hydrolysis with an oxyhydrogen flame burner 2 into which a gaseous glass raw material such as silicon tetrachloride was introduced are deposited to form the porous glass base material 3. The hydrogen flame burner 2 is fixed to a supporter 7 which is reciprocally moved left and right at a constant speed by a moving motor 8 because the outer diameter of the porous glass base material 3 is made substantially equal. .

Further, in this apparatus, an exhaust port 4 is provided at a position facing the oxyhydrogen flame burner 2, and this exhaust port 4 is also fixed to the above-mentioned supporter 7, which is an oxyhydrogen flame burner. Since it reciprocates left and right at a constant speed in synchronization with the movement of 2, the exhaust port 4 is always provided at a position facing the oxyhydrogen flame burner 2.

However, in this reactor, fine silica particles are constantly generated from the oxyhydrogen flame burner 2 during the reaction, and the fine silica particles are deposited on the carrier 2 to form the porous glass base material. Since the unreacted gas and unreacted dopant substances are constantly discharged from the oxyhydrogen flame burner 2, it is necessary to discharge them from the system as soon as possible.

In the device of the present invention, the exhaust port 4 reciprocates in synchronization with the oxyhydrogen flame burner 2 as described above, and since the exhaust port 4 is always provided so as to face the oxyhydrogen flame burner 2, The exhaust gas generated from the oxyhydrogen flame burner 2 is promptly sent to the exhaust port and exhausted to the outside, so this exhaust is performed very efficiently, and the unreacted gas contained in this exhaust gas. Further, since the dopant and the like are also prevented from adhering to the porous glass base material, there is an advantage that it can be made highly pure.

Since the exhaust port 4 reciprocates together with the oxyhydrogen flame burner 2 as described above, the exhaust gas from the exhaust port 4 is connected to the fixed exhaust port 6 provided in the furnace, which is heat resistant. It is assumed that the flexible hose 5 is used for communication, which allows efficient exhaust. Materials such as stainless steel and glass cloth are used for this heat resistant flexible hose.

[0013]

【Example】

 Next, examples of the present invention will be given. Example A germanium-doped glass rod 1 for a core having a diameter of 17.7 mmφ and a length of 620 mm was fixed in a closed furnace, an oxyhydrogen flame burner 2 was placed below the quartz glass rod 1 and an exhaust port 4 was placed above the quartz glass rod 1. In parallel with this, a moving motor 8 was attached to a supporter 7 that reciprocates at a speed of 100 mm / min, and a flexible hose 5 made of glass cloth was attached to the exhaust port 4 to make the device shown in FIGS.

Next, the quartz glass rod 1 is rotated at 50 rpm, and the supporter 7 is reciprocally moved at a speed of 100 mm / min, so that the oxyhydrogen flame burner 2 has 20 g / min of silicon tetrachloride and 25 liters / min of oxygen gas. When hydrogen gas was supplied at 50 liters / minute to ignite, silica fine particles generated here were deposited, and exhaust gas such as unreacted gas was sucked from the exhaust port 4 and exhausted to cause reaction for a time. A porous glass preform having a diameter of 100 mm and a length of 800 mm and a weight of 4,000 g was obtained.

Next, when the porous glass base material was heated to 1,500 ° C. in an electric furnace to be vitrified, an optical fiber preform with a diameter of 58.1 mmφ was obtained. When we made a fiber and investigated its transmission characteristics, it showed a value of 0.33 dB / km at 1.3 μm.

However, for comparison, when the exhaust port 4 in the above was not movable but was fixed to the upper part of the furnace, a porous glass preform of the same size could be obtained. The transmission characteristics of the optical fiber were 0.38 dB / km at 1.3 μm.

[0017]

[Effect of device]

 The present invention relates to an apparatus for producing a porous glass preform by an external CVD method, which is, as described above, located at a position facing the oxyhydrogen flame burner in the external CVD method in synchronization with the burner. It is characterized by the provision of an exhaust port with a heat-resistant flexible hose that reciprocates in the interior.However, according to this, the exhaust port is always facing the oxyhydrogen flame burner, and the The reaction gas, dopant, etc. are quickly exhausted, so the exhaust is performed efficiently, and unreacted gas, dopant, etc. do not adhere to the target porous glass base material, so this should be made highly pure. This results in the advantage that the transmission characteristics of the optical fiber made from this porous glass preform can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a porous glass preform manufacturing apparatus of the present invention.

FIG. 2 is a cross-sectional view of the porous glass preform manufacturing apparatus of the present invention.

FIG. 3 is a vertical sectional view of a conventionally known porous glass base material manufacturing apparatus.

[Explanation of symbols]

1, 11 ... Carrier, 2, 12 ... Oxygen flame burner, 3, 13 ... Porous glass base material, 4 ... Movable exhaust port,
5 ... Flexible hose, 6 ... Fixed exhaust port, 7 ... Support, 8 ... Moving motor, 14 ... Exhaust device, 15 ... Fixed exhaust port.

Claims (1)

[Scope of utility model registration request] 1. An apparatus for producing a porous glass preform by depositing glass fine particles produced by subjecting a gaseous glass raw material to flame hydrolysis with an oxyhydrogen flame burner to produce a porous glass base material, at a position facing the oxyhydrogen flame burner. 1. An apparatus for producing a porous glass preform, wherein an exhaust port capable of reciprocating left and right in synchronization with the movement of the burner is provided, and the exhaust port is connected to a heat resistant flexible hose.