A sealing device and control method for the mouth of a wire drawing furnace

Abstract

An apparatus for sealing a furnace mouth of a drawing furnace and a sealing control method. The apparatus comprises: an extendable and retractable sealing ring which is provided coaxially with the furnace mouth of the drawing furnace; an air extracting / inflating device which extracts air from or inflates air to the extendable and retractable sealing ring to change the pressure in the extendable and retractable sealing ring and correspondingly change the inner diameter of the extendable and retractable sealing ring; a laser diameter measuring instrument for measuring the actual diameter of an optical fiber preform; a pressure sensor for measuring the pressure in the extendable and retractable sealing ring; and a controller which analyzes, according to the measured pressure in the extendable and retractable sealing ring and the measured actual diameter of the optical fiber preform, diameter data of the optical fiber preform to control the air extracting / inflating device to extract air from or inflate air to the extendable and retractable sealing ring, so that the inner ring surface of the extendable and retractable sealing ring always abuts against the optical fiber preform. The control method can seal a gap between the furnace mouth of the drawing furnace and the optical fiber preform.

Description

technical field [0001] The invention relates to the field of optical fiber drawing, in particular to a sealing device for a furnace mouth of a drawing furnace and a control method thereof. Background technique [0002] An optical fiber is produced by a method in which an optical fiber preform mainly composed of silica is lowered from the upper opening of a drawing furnace into a furnace core tube, and the tip of the preform is heated and melted to make the preform The front end is tapered and drawn. At this time, the temperature in the drawing furnace is very high at 1,800-2,200 degrees Celsius, so graphite with excellent heat resistance is used for components of the drawing furnace. This graphite is oxidized and consumed in a high-temperature oxygen-containing atmosphere. In order to prevent the above, it is necessary to keep the inside of the drawing furnace in an atmosphere of rare gas such as argon or helium, or nitrogen (hereinafter collectively referred to as inert g...

AI Technical Summary

Problems solved by technology

The size of this quartz cylinder is fixed, and when selected, its size is usually larger than the thickest part of the preform, so when the diameter of the preform fluctuates or becomes smaller, the size of the cylinder does not correspond This will lead to poor sealing effect of the furnace mouth, air will enter the drawing furnace through the sealing device, and high-quality optical fibers cannot be drawn

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