JPH02289438A - Chamber for producing optical fiber preform - Google Patents

Abstract

PURPOSE:To prevent the falling of fine glass grains and the intrusion of impurities due to the breakage of the preform and redeposition by forming many fine glass grain passage holes in the inner wall of the chamber and allowing the gap between the inner and outer walls to communicate with an exhaust duct. CONSTITUTION:The chamber 1 is box shaped as a whole with both ends and the side opposed to a burner opened and provided with a bottom wall 10 and an upper wall 12. The upper wall 12 consists of the inner wall 14 and the outer wall 16, and a gap 18 is formed between both walls 14 and 16. Many holes 20 are formed in the inner wall 14 to trap the flown up fine glass grains. The fine glass grains 7 formed by a burner 6 are deposited on a starting member 4 to form the porous-glass optical fiber preform 5. A part of the grains not deposited are led to the exhaust duct 2, and the other part is carried to the upper wall 12 by the ascending current, trapped by the many holes 20 provided in the inner wall 14 of the upper wall 12 and led to an exhaust duct 3 through the gap 18.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a chamber for producing an optical fiber preform by an external method, in which the preform is produced by a flame hydrolysis reaction or a thermal oxidation reaction, and is produced by a flame hydrolysis reaction or a thermal oxidation reaction. This provides a structure that can successfully exhaust to the outside the glass particles that fly up to the upper part of the chamber due to the rising airflow caused by the heat.

(Prior Art) In a conventional chamber of this type, the burner is installed by providing an exhaust port on the opposite side, and guiding glass particles that have not adhered and deposited on the starting member from the exhaust port to the exhaust duct.
It was disposed of by removing it with a scrubber.

(Problems to be Solved by the Invention) With the above-described apparatus, most of the glass particles fly upwards on the rising air current due to heat during deposition, and are deposited on the chamber earthen walls.

This phenomenon becomes noticeable when the suction pressure of the duct decreases for some reason, and a mass of glass particles deposited on the upper wall of the chamber may fall onto the base material being deposited, damaging the base material, or directly falling. Even if it is not, there is a problem that it will fall to the bottom of the chamber and contaminate it, and then fly up again and adhere to the base material, introducing impurities. Furthermore, the interior of the chamber must be cleaned every time the deposition is completed, which is inconvenient.

(Means for Solving the Problems) The present invention is designed to successfully (process) glass particles flying up to the upper part of a chamber from one or more viewpoints.
Its features are that the external chamber is a chamber for manufacturing optical fiber preforms using a method; It is located in a chamber with a gap formed between its inner and outer walls communicating with an exhaust duct.

(Function) The glass particles that fly up to the upper part of the chamber due to the rising airflow caused by the heat during deposition pass through a number of holes formed in the inner wall of the upper chamber wall, pass through the gap created by both the inner and outer walls, and reach the exhaust duct. Because it is guided, the flying glass particles do not fall and adhere to the base material.

(Example) FIG. 1 shows a schematic explanatory diagram of a chamber for manufacturing an optical fiber preform according to the present invention, and l is a chamber that is box-shaped as a whole and is open at both ends and the side facing the burner described later. It has a bottom wall 10 and a top wall 12, and the top wall 12 has a double structure consisting of an inner wall 14 and an outer wall 16, and a gap 18 is formed by the inner and outer walls 14 and 16. Numerous holes 20 are formed in the inner wall 14 and are used to trap glass fine particles that fly up, which will be described later. 2 is an exhaust duct communicating with the chamber 1, and 3 is an exhaust duct communicating with the gap 18. 4 is chamber l
5 is a porous glass preform for an optical fiber deposited around it; 6 is a burner which applies flame hydration; This is for producing glass fine particles 7 through decomposition or thermal oxidation reaction.

In the above configuration, the glass fine particles 7 generated by the burner 6 are deposited around the starting member to form the porous glass preform 5 for optical fiber. At this time, some of the glass particles that have not been deposited are guided to the exhaust duct 2, but some of them are carried by the upward air current and head toward the upper wall 12.

Then, it is trapped in a number of holes 20 provided in the inner wall 14 of the upper wall 12 and guided to the exhaust duct 3 through the gap 18 .

In the above embodiment, the starting member 4 is parsed, but the burner 6 and the chamber 1 may be traversed without traversing the starting member 10.

(Effects of the Invention) As described above, the present invention guides the glass particles flying upward in the chamber through a number of holes provided in the inner wall of the double-layer earthen wall into the gap between the inner wall and the outer wall and exhausts them. This prevents the base material from falling onto the base material being manufactured, thereby preventing damage to the base material and contamination of impurities due to redeposition.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a chamber for manufacturing an optical fiber according to the present invention. In figure 0, l: chamber, 12: earthen wall, 14: inner wall, 20: hole. Figure 1 Patent applicant Mamoru Takeuchi, agent for Fujikura Electric Cable Co., Ltd., patent attorney

Claims (1)

[Claims] This is a chamber for manufacturing optical fiber preforms using an external attachment method, and its upper wall is composed of an inner and outer double wall with a gap between them, and a large number of glass particle insertion holes are formed in the inner wall, and A chamber for manufacturing an optical fiber base material, characterized in that a gap formed by both walls is communicated with an exhaust duct.