METHOD AND APPARATUS FOR MANUFACTURING OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To draw a line while easily and surely sealing a gap generated between an upper end opening in an optical fiber drawing furnace and an optical fiber preform even when the optical fiber preform has a large diameter variation.SOLUTION: An apparatus for manufacturing optical fibers comprises: a drawing furnace (a drawing furnace body 10) having an upper end opening for inserting an optical fiber preform 1; and a seal part 20 for sealing a gap between the upper end opening and the inserted optical fiber preform 1. The seal part 20 comprises: two or more carbon felt rings 21 and 22 having an inner diameter of the maximum outer diameter of an effective portion of the optical fiber preform 1 or less; a sheet ring 24 having an inner diameter of the maximum outer diameter of the effective portion provided between the carbon felt rings 21 and 22 or more. At least one of the two or more carbon felt rings 21 and 22 has an inner diameter different from these of the other carbon felt rings and has an inner diameter of the minimum outer diameter of the effective portion or less.SELECTED DRAWING: Figure 2A