JPS58661Y2 - Glass particle synthesis torch - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a glass particle synthesis torch.

This type of glass particle synthesis torch (hereinafter simply referred to as a synthesis torch).

) is used when manufacturing an optical fiber base material by the method shown in FIG. 1 (the so-called VAD method).

In FIG. 1, glass fine particles synthesized by a synthesis torch are attached and sintered to form a rod-shaped glass sintered body (hereinafter referred to as a sintered body) 2.

The sintered body 2 is rotated and pulled up by a rotation/lifting device 3 and enters an electric furnace 4 .

5 is a heating element that heats the sintered body to 1600-1700°C to form a transparent glass body.

This transparent glass body is the optical fiber base material 6.

7 is a protective container, and 8 is an exhaust regulator. Normally, in the VAD method, silicon tetrachloride, which is the raw material for glass fine particles or
Because this process is carried out by hydrolyzing germanium tetrachloride, phosphorous oxyoxide, boron tribromide, etc. using an oxyhydrogen flame, the partition wall between the flammable gas outlet and the combustible gas outlet in the synthesis torch is extremely becomes high temperature.

Conventionally, quartz lath has been used as the material for synthetic torches because it has a high softening point and is free from impurities such as transition metals (which increase optical fiber loss).

However, quartz glass has a melting point of approximately 1650°C, and devitrification (crystallization from the glass state of SiO2) occurs in the range of 1000 to 1713°C, resulting in deterioration of properties.

For this reason, the oxyhydrogen flame causes high temperatures (1700 to 2000
C), the partition wall gradually collapses from its tip, and the synthesis torch becomes unusable after 100 to 200 hours.

In particular, devitrification causes rapid deterioration of quartz glass and further shortens the life of the synthetic torch.

The present invention uses a material (such as sapphire) that does not soften or devitrify at high temperatures for the partition walls between the flammable gas outlet and the combustion supporting gas outlet of the synthesis torch.The purpose of this is to prevent the partition walls from collapsing and The purpose is to allow the torch to be used for a long time.

FIG. 2 shows an embodiment of the present invention, in which 21 is a raw material outlet, 22 is an inert gas surrounding it (for example, Ar,
23 is an outlet for flammable gas,
Reference numeral 24 indicates an outlet for the combustible gas, and 25 indicates a partition wall between the combustible gas outlet and the combustible gas outlet, which is made of sapphire.

The melting point of sapphire is 2040°C, which is higher than that of quartz glass, and there is no property deterioration such as devitrification, so the synthetic torch can be used for a long time.

For example, when using the synthesis torch of the present invention to flow 5 l/min of combustible gas and 10 l/min of combustible gas to coalesce glass particles, the center temperature of the flame will be 1600-1800°C.
The temperature at the tip of the partition wall is 1500 to 1600°C,
Sapphire has a thermal conductivity of 2000% compared to quartz glass.
Since it eats about twice as much, the temperature at the tip tends to drop and the partition wall is difficult to collapse.

This synthesis torch can be used for 500 to 1000 hours with little deterioration, and if 100g of glass raw material is fed per hour to coalesce glass fine particles and form a sintered body, one synthesis torch can produce 12 to 24 kg. Optical fiber base material (outer diameter 150
It was possible to manufacture a 300 to 600 km long optical fiber by drawing it into a μm optical fiber.

As explained above, in the synthetic torch of the present invention, the partition wall between the flammable gas outlet and the combustible gas outlet is softened at high temperature.
Since it uses a material that does not devitrify, it has the advantage of greatly increasing the life of the synthetic torch.

Furthermore, if the life of the synthetic beam is extended, there is an advantage that not only can optical fiber preforms with uniform manufacturing conditions be mass-produced, but also the price of optical fibers can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical fiber preform manufacturing apparatus, and FIG. 2 is a diagram of an embodiment of the present invention. 1... Synthesis torch, 2... Sintered body, 3
...Rotating/pulling device, 4...Electric furnace, 5...Heating element, 6...Optical fiber base material, 7... Protective container, 8... Exhaust regulator, 21... Raw material outlet, 22...
・Inert gas outlet, 23... Flammable gas outlet, 24... Combustible gas outlet, 25.
...Sapphire bulkhead.

Claims (1)

[Scope of utility model registration request] Glass raw materials are blown into a flame created by burning flammable gas, and glass particles are synthesized through hydrolysis.
In a synthesis torch that has a raw material outlet in the center, which is surrounded one after another by an inert gas outlet, a combustible gas outlet, and an auxiliary gas outlet, the combustible gas outlet and the combustion auxiliary gas outlet are A glass particle synthesis torch characterized in that a partition made of a material that does not soften or devitrify at a temperature higher than the softening point of quartz glass is provided between the gas outlet.