JPS63307137A - Production of glass preform for optical fiber - Google Patents

Abstract

PURPOSE:To obtain a glass preform having long-period stable qualities, by vaporizing raw materials or additives for glass preform, having a boiling point higher than room temperature under heating, feeding to a burner nozzle and heating the root end part of the nozzle. CONSTITUTION:A burner 1 has structure wherein a glass raw material gas is made to flow from two nozzles to the burner. In the burner, SiCl4 as the glass raw material gas and hydrogen as a combustible gas are made to flow from a central nozzle 2, respectively, an inert gas comprising argon, etc., is sent from a second nozzle 3 successively to the outside, SiCl4 and GeCl4 as the raw material gas plus oxygen as an auxiliary gas are made to flow from a third nozzle 4. Another gas comprising an inert gas such as argon is fed from a fourth nozzle 5. The central nozzle 2 to send the glass raw materials and the combustion gas and the third nozzle 4 to feed the glass raw material gas and the auxiliary gas are equipped with heaters 6 at the root end parts, respectively. The heaters 6 are connected temperature control device to control the temperatures in desired temperatures.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a glass preform for an optical fiber by a gas phase reaction using a carbohydrolysis burner.

[Prior art]

Conventionally, V
The AD method is well known. This method uses a multi-tube burner to guide vaporized raw materials or additives such as GeCl4 together with combustible gas, combustion assisting gas, or inert gas to a predetermined nozzle of the multi-tube burner, and then air is introduced in front of the nozzle. A glass preform for optical fibers is manufactured by synthesizing glass particles through a phase reaction and depositing them on a rotating support rod.

By the way, commonly used raw materials and additives include 5
These substances include iC14, GeC1a, TiCl4, POCl2, etc., and these substances are usually liquid or solid at room temperature. Therefore, conventionally, a system has been adopted in which the gas is forcibly vaporized using another gas, and then the concentration is maintained constant and the vapor is fed to the burner nozzle.

Therefore, the piping system communicating with the burner is heated by a heater or the like to prevent the glass raw material (hereinafter referred to as glass raw material including additives) from liquefying or solidifying.

In the conventional manufacturing method of glass base material for optical fibers described above, heating efficiency is poor at the piping joints, burner nozzles, and especially the nozzle in the center for glass raw material, and the glass raw material gas tends to liquefy or solidify at these locations. Something happened. As a result, if glass base material is manufactured for a long period of time, phenomena such as clogging of the nozzle for glass raw material gas may occur, making it impossible to feed a certain amount of glass raw material, resulting in a stable quality glass base material for optical fibers. There was a problem that it could not be manufactured.

As a means of solving this problem, for example,
As described in the above publication, a proposal has been made to provide a hollow part in each partition wall of the burner nozzle and seal a heat medium for heating the nozzle in the hollow part, but this method makes the burner complicated and There was a problem that it became large.

[Purpose of the invention]

In view of the above problems, an object of the present invention is to easily prevent liquefaction and solidification of glass raw material gas by simply making improvements to conventional burners, and thereby to produce a glass base material for optical fibers with stable quality over a long period of time. An object of the present invention is to provide a method for manufacturing a glass preform for optical fiber.

[Structure of the invention]

In order to achieve the above object, the present invention provides a method for manufacturing a glass preform for optical fibers by a gas phase reaction, in which raw materials or additives for the glass preform having a boiling point higher than room temperature are heated and vaporized by a raw material supply device to produce a glass raw material. It is characterized in that it is fed as a gas to the burner nozzle and that the base end of the burner nozzle to which the frit gas is fed is heated.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of a burner used in the method of manufacturing a glass preform for optical fiber according to the present invention.

As shown in this figure, the burner 1 used in the present invention has a structure in which frit gas flows from two nozzles.
14 and hydrogen, which is a combustible gas, are flowed respectively, and an inert gas such as argon is sequentially flowed outward from the second nozzle 3, and auxiliary combustion is performed on the glass raw material gas 5iC1n and GeCl4 from the third nozzle 4. Oxygen, which is a reactive gas, is added and flowed through the fourth nozzle 5, and another gas consisting of an inert gas such as argon is flowed through the fourth nozzle 5.
A heater 6 is installed at the base end of each nozzle through which the frit gas flows, that is, the central nozzle 2 through which the frit gas and combustible gas flow, and the third nozzle 4 through which the frit gas and combustion auxiliary gas flow.
Each heater 6 is connected to a temperature controller (not shown) and is controlled to a desired temperature.

In FIG. 1, the base ends of all the nozzles may be covered with a heater, but in order to prevent the heater from increasing in size, it is more preferable to heat only the base end of the frit gas nozzle described above with the heater. .

Furthermore, it goes without saying that the present invention is not limited to the burner structure shown in the embodiments described above, but can be applied to burners of various structures.

When a glass base material for optical fiber was manufactured using the burner 1 as described above, no condensation was observed at all in the nozzles 2 and 4 for supplying frit gas, and no nozzle clogging occurred for a long period of time. .

As a result, we were able to manufacture a glass base material for optical fibers with stable quality over a long period of time.

〔Effect of the invention〕

As described above, according to the present invention, by making extremely simple improvements to the burner, it is possible to prevent the glass raw material gas from liquefying or solidifying, thereby making it possible to produce a glass base material for optical fibers with stable quality over a long period of time. .

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a burner used in the present invention.

Claims (1)

[Claims] In a method for manufacturing a glass preform for optical fibers by a gas phase reaction, raw materials or additives for the glass preform having a boiling point higher than room temperature are heated and vaporized by a raw material supply device and fed to a burner nozzle as a glass raw material gas, and the A method for producing a glass preform for optical fibers, which comprises heating the base end of a burner nozzle to which frit gas is fed.