| 摘要 |
PURPOSE:To obtain the titled wire drawing furnace wherein temp. drop and temp. unevenness of the melted contracted diameter part of a base material for optical fiber are prevented and good wire drawing is enabled by performing the wire drawing of optical fiber while blowing inert gas previously heated into the furnace body. CONSTITUTION:A base material 1 for optical fiber is fed to the inside of a furnace core pipe 3 through an insertion port 11 of the sealing part 5 in the upper end of the core pipe 3 of a wire drawing furnace 2. Inert gas heated at the temp. close to the temp. of the upper end part of the core pipe 3 with a preheater 7 is fed to a blow-out port 12 provided to the sealing part 5 and allowed to collide against the outer peripheral wall of the base material 1, one part is raised to prevent the infiltration of the atmosphere, and the other part is descended and passed through the melted contracted diameter part of the base material 1 and discharged to the atmosphere through the sealing part 6 of the lower end of the core pipe so as to prevent the atmosphere contg. oxygen from being mixed into the core pipe 3 through a takeout port 13 of optical fiber. Thereby the temp. distribution of gas in the furnace body in the vicinity of the melted contracted diameter part of base material 1 can be definitely kept and the fluctuation of the diameter of optical fiber to be wire-drawn is prevented and also the flow rate of gas necessary to both the effective discharge of dust generated in the furnace body and the prevention of oxidation of parts of the wire drawing furnace can be supplied. |
