JPS604980Y2 - optical fiber spinning furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber spinning furnace for producing optical fibers by heating a preform.

Optical fibers are manufactured by heating and melting an optical glass rod, that is, a preform, processed to have a predetermined refractive index distribution in an electric furnace or the like, and drawing it down to a desired outer diameter.

At this time, a preform with an outer diameter of several centimeters is
Since the diameter is reduced to less than 1.0 inch, even small scratches on the outer surface of the preform can cause breakage of the optical fiber during the spinning operation.

Furthermore, even if the fiber is not broken during spinning, there is an extremely high risk of breakage in the subsequent process.

To solve this problem, conventional methods include smoothing the outer surface of the preform with hydrofluoric acid before transferring it to the spinning process, or flame polishing, which involves setting the preform in a glass lathe and heating and melting the outer surface with oxyhydrogen flame. I was trying to do it.

However, this process requires several hours for one preform, which hinders productivity improvement.

The present invention has been developed with the above-mentioned points in mind, and it is an object of the present invention to provide an optical fiber spinning furnace that can omit or significantly reduce the time required for preliminary flame polishing treatment.

The figure is a vertical cross-sectional view of an embodiment of the spinning furnace of the present invention, in which a preform rod 1 is inserted through a through hole 3 at the top of a furnace body 2, and a first heater using cylindrical carbon is wound around an electric heater or the like. 4, the end portion 5 is heated and melted, and the optical fiber 6 is wound downward in the figure by a winding mechanism (not shown).

Needless to say, at this time, the preform rod 1 is fed downward at a predetermined speed.

Here, in front of the first heater 4 in the furnace body 2, a second heater 7 having a substantially similar configuration is further provided.

This second heater 7 is capable of outputting an amount of heat to heat and soften the outer surface 8 of the preform rod 1 before spinning the preform rod 1 into the optical fiber 6.

By this heat treatment, scratches on the outer surface of the preform rod 1 that were formed before this process are removed.

According to the optical fiber spinning furnace of the present invention having the above configuration, there is no need to previously polish the outer surface of the preform rod before spinning.

Moreover, if the preform rod, which has been polished in advance, is attached to the furnace, if the outer surface of the preform rod is touched by hand or foreign matter adheres to it, this can also cause breakage during spinning.
There are no such inconveniences.

That is, in the present invention, since the outer surface of the preform rod is flame-polished immediately before spinning, the spinning operation can be performed in ideal conditions without scratches, and it is possible to continuously manufacture homogeneous long optical fibers. It is.

In addition, since the preform rod is heated prior to heating during spinning, the amount of heat of the heating source for spinning, that is, the amount of heat of the first heater, can be reduced, resulting in energy savings compared to the case where flame polishing is performed as a separate process. .

In the above embodiment, an example was shown in which one second heater was provided, but the same effect can be obtained even if two or more second heaters are provided.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of an embodiment of the spinning furnace of the present invention, where 2 is the furnace body, 1
1 is a preform rod, 6 is an optical fiber, 4 is a first heater, and 7 is a second heater.

Claims (1)

[Scope of utility model registration request] a first heater that heats and melts the end of the preform rod that is fed in at a predetermined speed to enable spinning of the optical fiber; 1. An optical fiber spinning furnace comprising: a second heater for heating and softening the fiber and performing a flame polishing process.