| 摘要 |
PURPOSE:To prevent the sticking of impurities to a glass fiber obtd. by drawing a preform rod and to improve the mechanical strength of the fiber, by filtering a gas in a heating furnace and by returning the purified gas to the furnace. CONSTITUTION:A preform rod 2 is put in a heating furnace 1 kept at about 2,000 deg.C with a heater 13 from the inlet 3, and a glass fiber obtd. by drawing the rod 2 is taken out of the outlet 5. At this time, purge gas G is introduced into the furnace 1 through the 1st gas introducing chamber 11 and allowed to flow downward in the direction of arrows, and purge gas G is also introduced through the 2nd gas introducing chamber 12. The latter purge gas G flows downward from the outlet 14 without entering the furnace 1. Gas in the furnace 1 is sucked from each exhaust port 6, and it is cooled, purified, and returned to the furnace 1 through a pipe 8, a suction mechanism 9, a filter 10, a pipe 8 and a gas inlet 7. |
