JPS604979Y2 - Glass particle synthesis torch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a glass particle coalescing torch for use in the VAD method in which the distribution and density of glass particles and the temperature of the deposition surface can be controlled separately.

Conventionally, it is well known that optical fibers have attracted attention and are considered promising as optical communication transmission media, and one of the methods for manufacturing optical fiber base materials for manufacturing optical fibers is the VAD method (vapor phase axis). There is a method (additional method).

This method uses glass forming raw materials (mainly 5iC14, Ge)
Chlorides such as Cl4 and POCl3) are flame-hydrolyzed in a flame of hydrogen gas and oxygen gas, and the synthesized Takara fine particles (oxides such as St02w GeO2 and P2O5) are sequentially attached to the tip of a support rod (starting seed rod). This process forms a rod-shaped porous glass body, which is then heated, degassed, and made into transparent glass to obtain an optical fiber base material.

The configuration of a conventional glass particle synthesis torch used in this method will be explained with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a conventional glass particle synthesis torch, in which 1 is a gas phase raw material inlet, 2 is an inert gas inlet, 3 is a combustible gas inlet, and 4. is a combustible gas inlet, 5 is a gas phase raw material conduit, 6 is an inert gas conduit, 7 is a combustible gas conduit,
This figure shows an 8-piece combustion auxiliary gas conduit.

Frit gas (SiC) introduced from gas phase raw material population 1
14, GeCl4 and POCI, etc.) are blown out in a gaseous state from the outlet of the gas phase raw material conduit 5, and an inert gas (e.g. Ar gas, He gas, N2 gas, etc.) introduced from the inert gas inlet. from the outlet of the inert gas conduit 6, and the combustible gas (e.g. gas and propane gas) introduced from the combustible gas inlet 3 from the outlet of the combustible gas conduit 7, and the combustible gas inlet 4. auxiliary combustion gas (
For example, 02 gas) from the outlet of the auxiliary gas conduit 8,
By blowing out each, combustible gas is combusted with combustion supporting gas, glass raw material gas is flame hydrolyzed, and 5in.
2. Glass fine particles such as P2O5 and α0° are synthesized.

A flame containing the glass particles synthesized in this manner is injected onto the support rod to deposit the glass particles, thereby forming a rod-shaped porous glass body.

An optical fiber base material is produced by heating and degassing this porous glass body to make it transparent vitrified.

The optical properties of the optical fiber produced by the VAD method are as follows:
It is almost determined at the stage of forming the porous glass body.

That is, the optical characteristics of the optical fiber are determined by the distribution state of the glass particles in the flame, the temperature distribution on the glass particle adhesion deposition surface (hereinafter referred to as the deposition surface), the density of the porous glass body, and the like.

However, according to the conventional glass particle synthesis torch shown in FIG. Since the factors are all controlled by the flame obtained by the combustible gas and the combustible gas, there is a drawback that each of the above factors cannot be controlled separately.

This idea was made in view of the current situation,
The aim is to overcome the above-mentioned drawbacks and to provide a glass particle synthesis torch in which the factors determining the optical properties can be controlled separately and easily.

To summarize the present invention, the glass particle synthesis torch of the present invention consists of a glass particle synthesis gas phase raw material conduit, a combustible gas conduit, and an auxiliary gas conduit conduit arranged concentrically and in a multi-tubular manner. A glass particulate deposition surface heating element consisting of a combustible gas conduit pipe and a combustion auxiliary gas conduit pipe is arranged concentrically and in a multi-tubular manner around the synthesis element, and the glass particulate deposition surface heating element is It is characterized in that the gas outlet is set higher than the gas outlet of the glass particulate threat element by a distance sufficient to complete the synthesis of glass particulates.

The structure and operation of the present invention will be specifically explained with reference to the drawings.

That is, FIG. 2 is a schematic cross-sectional view showing a specific example of the glass particle synthesis torch of the present invention, with reference numerals 1.3.4.
5.7 and 8 have the same meaning as in Figure 1;
Reference numeral 9 indicates a combustible gas inlet for glass particle synthesis, 10 indicates a combustion auxiliary gas inlet for glass particle synthesis, 11 indicates a combustible gas conduit for glass particle synthesis, and 12 indicates a combustion auxiliary gas conduit for glass particle synthesis; represents the distance between the gas outlet of the glass particle synthesis element and the gas outlet of the glass particle deposition surface heating element.

The glass particulate threat element in the present invention is composed of the gas phase raw material conduit 5 for glass particulate synthesis, the combustible gas conduit 11, and the auxiliary combustion gas conduit 12, which are arranged concentrically and in a multi-tubular manner. The surrounding glass particle deposition surface heating elements are connected to the combustible gas conduit 7 and the combustible gas conduit 8 which are also concentrically arranged in a multi-tubular configuration.

That is, each of the conduction tubes has the gaseous phase raw material conduit tube 5 for glass particle synthesis at the center, and the combustible gas conduit tube 11 for glass particle synthesis, the auxiliary gas conduit tube 12 for glass particle synthesis, and the combustible gas are arranged around it. The conduit tube 7 (for heating the glass particulate deposition surface) and the combustion-assisting gas conduit tube 8 (same as above) are arranged concentrically and in a multi-tubular manner in this order, and the gas outlet of the element for heating the glass particulate deposition surface is connected to the glass particulate deposition surface. It is set higher than the gas outlet of the particulate threat element by a distance a sufficient to complete the synthetic skin of the glass particulates.

Gas phase raw material population 1 to gas phase raw material (e.g. 5 iCl, .

GeC1, POCl3, etc.), combustible gas (for example, H2 gas and propane gas, etc.) from the combustible gas for glass particle synthesis 9, and combustible gas (for example, 02 gas) from the combustible gas inlet 10 for glass particle synthesis. Then, combustible gas (such as H2 gas and propane gas) is supplied from the flammable gas inlet 3, and combustible gas (such as H2 gas and propane gas) is supplied from the combustible gas inlet 3.
For example, 02 gas) is introduced respectively.

In this case, the combustible gas for glass particle synthesis and the combustion auxiliary gas for glass particle threat need only be supplied at a flow rate that allows the supplied gas phase raw materials to undergo flame hydrolysis and become glass particles.
Therefore, the flame obtained by the combustible gas for glass particle synthesis and the combustion auxiliary gas for glass particle threat is generated between the outlet of the combustible gas conduit for glass particle synthesis 12 and the outlet of the combustible gas conduit 7. formed within a distance a.

Therefore, at the position of the outlet of the combustible gas conduit 7, only the flow of glass fine particles synthesized inside the torch exists.

As a result, the flame formed by the combustible gas blown out from the outlet of the combustible gas conduit 7 and the combustible gas blown out from the outlet of the combustible gas conduit 8 has already been synthesized inside the glass particle synthesis torch. It will contain glass particles.

Therefore, the amount of gas blown out from the combustible gas conduit 7 and the combustible gas conduit 8 may be adjusted so as to reach the desired temperature of the deposition surface, regardless of glass particle synthesis.

Further, according to the studies of the present inventors, it is appropriate that the distance a sufficient for the synthesis of the glass particles to be completed is approximately 3 hours or more, and if it is less than this, the distance a that is sufficient to complete the synthesis of the glass particles is approximately 3 hours or more. The formation of glass fine particles becomes insufficient, and the combustible gas and combustion auxiliary gas blown out from the gas outlet become involved in the synthesis of glass fine particles, making it difficult to separately and reliably adjust the temperature of the deposition surface.

Incidentally, according to experiments by the present inventors, for example, 5iC14
and GeCl4 in a gaseous state to the gaseous raw material conduit 5,
When this is flame-hydrolyzed to synthesize glass particles, and the synthesized glass particles are deposited on a support rod while maintaining the temperature of the deposition surface at about 700°C, combustible gas conduction for glass particle synthesis is required. By flowing N2 gas at a rate of 0.51/min from the pipe 11 and flowing 02 gas at a rate of 21/min from the combustion auxiliary gas conduit 12 for glass particle synthesis, the gas phase raw material can be flame-hydrolyzed. , N2 gas is supplied from the combustible gas conduit 7 for 3//min, and 0/min is supplied from the combustible gas conduit 8.
By flowing the two gases at a rate of 41/min, the temperature of the deposition surface could be maintained at about 700°C.

According to the glass particle synthesis torch of the present invention, the glass particles synthesized inside the synthetic leather torch are sintered in the axial direction by the flame obtained by the combustible gas and the combustible gas blown out from the surroundings to form a porous glass body. The distribution of glass particles in the flame and the state of the glass particles (crystalline or amorphous) are important for controlling the optical properties of the optical fiber. The temperature of the deposition surface can be controlled by the flow rate of the flammable gas and the combustion auxiliary gas blown out from the combustible gas conduit 11 and the combustion auxiliary gas for glass particle synthesis, and the distance a shown in FIG. Gas conduction pipe 7 and combustion auxiliary gas conduction pipe 8
The flow rates of the combustible gas and the combustion-assisting gas blown out from the combustible gas can be controlled separately and easily.

In the above specific example, N2 gas and 02 gas were used for flame hydrolysis of the gas phase raw material, but steam, hot air, etc., which can hydrolyze or oxidize the gas phase raw material to synthesize glass particles, can also be used. You can also.

In addition, in the specific example shown in FIG. 2 above, the flow pipe for the inert gas as the carrier gas for preventing device clogging is omitted.
If necessary, an inert gas (e.g. Ar gas, He gas,
(gas, N2 gas, etc.) can be provided.

As explained above, in the multi-tube structure glass particle synthesis torch used in the VAD method, according to the present invention, the temperature of the synthetic skin and the deposition surface of glass particles can be controlled separately, which makes it possible to The optical characteristics of the optical fiber can be easily and reliably controlled, which is difficult to do with a synthetic torch.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional schematic diagram of a conventional glass particle synthesis torch.
FIG. 2 is a schematic cross-sectional view showing a specific example of the glass particle synthesis torch of the present invention. 1... Gas phase raw material inlet, 2... Inert gas inlet, 3... Flammable gas inlet, 4...
- Combustion auxiliary gas inlet, 5... Gas phase raw material conduit, 6
...Inert gas communication pipe, 7...Flammable gas communication pipe, 8...Combustion auxiliary gas communication pipe, 9...
...Flammable gas inlet for glass particle synthesis, 10...
... Combustion aid gas inlet for glass particulate threat, 11...
...Flammable gas conduit for glass particle synthesis, 12.
... Combustion auxiliary gas conduit for glass particle synthesis.

Claims (1)

[Scope of utility model registration request] Concentric and multi-tubular arrangement of gas-phase raw material conduit for glass particle synthesis, combustible gas conduit, and auxiliary combustion gas conduit. A glass particulate deposition surface heating element consisting of a combustion gas conduit and a combustion auxiliary gas conduit is arranged, and the gas outlet of the glass particulate deposition surface heating element is connected to the gas outlet of the glass particulate synthesis element. A glass fine particle synthetic torch characterized by being raised by a distance sufficient to complete the synthetic skin of the glass fine particles.