| 摘要 |
PURPOSE:To improve flexural strength of optical fiber and life of the furnace, by introducing an inert gas dropping in a drawing furnace into an inner peripheral face side of a bottom diffuser, exhausting the gas by suction and further sucking the gas in the midst of a hole through which optical fiber is passed. CONSTITUTION:An exhaust hole 15 of an inert gas which is fed to a top diffuser 6 and drops in a drawing furnace 1 is set in an inner peripheral face of a bottom diffuser 10. A small circular hole 21 through which the optical fiber is passed is laid at the central part of the bottom diffuser 10, a suction section is made in the midst of the circular hole 21 and the suction section is connected to an exhaust hole 15 by pumps 25 and 19. Consequently, the inert gas containing dust is made to flow in the direction to separate the gas from the optical fiber and discharged from the exhaust hole 15. The open air which is made to flow through the small circular hole 21 into the furnace 1 is prevented from entering. Consequently, adhesion of dust generated in the furnace to the optical fiber, oxidation and deterioration of the optical fiber and a core pipe can be prevented. |
