Optical fiber drawing method for large-diameter optical fiber preform rod

Abstract

The invention relates to an optical fiber drawing method for a large-diameter optical fiber preform rod. The method comprises the following steps: continuously moving the large-diameter optical fiber preform rod downwards to enter an optical fiber drawing furnace through a lifter, heating and drawing to form a finished optical fiber, inputting protective gas into the furnace body through an extension pipe at the furnace bottom, allowing the protective gas to flow upwards, allowing the gas to flow out of a gas outlet of a gas guide disc, and allowing the protective gas input by the gas guide disc and a gas sealing cover to flow out of the gas outlet of the gas guide disc. The method has the advantage that the large-diameter optical fiber preform rod can be drawn to form the optical fiber with stable quality.

Description

technical field [0001] The invention relates to an optical fiber drawing method, in particular to an optical fiber drawing method for a large-diameter optical fiber preform. Background technique [0002] At present, the drawing method of optical fiber is to continuously move the lower end of the quartz glass rod of the optical fiber preform into the fiber drawing furnace and draw it into an optical fiber after being heated. A draft pipe, an extension pipe and a furnace top gas tray; the upper and lower walls of the furnace body are respectively provided with an upper drawing hole and a lower drawing hole, and the middle casing is arranged in the furnace body through the upper drawing hole and the lower drawing hole, and the heat preservation The body is arranged in the furnace body, the heating element is arranged in the furnace body between the middle casing and the heat preservation body, the top gas plate is set on the upper drawing hole, one end of the extension pipe is ...

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Problems solved by technology

There is also the design of directly sealing the optical fiber preform and the drawing furnace mouth through the graphite soft felt; the invention patent 200810134932. Sealing, however, in these designs, because the drawing furnace adopts a downward airflow direction, the sealing material used at the furnace mouth is under the action of high temperature and friction, causing some graphite soft felt carbon powder to enter the drawing furnace, which will cause the strength of the optical fiber to decrease ; In the structure of the two-unit graphite sheet seal in the invention patent 200810134932.x, the elasticity of the graphite sheet is very small at high temperature, and for an optical fiber preform with a large diameter change, it will cause air leakage and cause oxidation of the drawing furnace; As the diameter of the optical fiber preform becomes larger and larger, the fluctuation range of the diameter of the optical fiber preform becomes larger, so that the fluctuation range of the gap between the upper drawing hole and the preform inserted into the furnace becomes larger, so it is difficult to control the drawing furnace The laminar flow stability of the high-temperature gas inside; especially at the end of the fiber, its diameter gradually decreases, thus making it impossible to pull out a fiber with stable quality at this section

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