| 摘要 |
PROBLEM TO BE SOLVED: To provide a drawing and heating furnace capable of producing an optical fiber controlled in a fiber diameter by eliminating the fluctuation in an in-furnace pressure and inert gaseous flow occurring in a clearance fluctuation. SOLUTION: The furnace core tube 3 of the drawing and heating furnace 1 for producing the optical fiber 10 by heating, melt stretching and drawing an optical fiber preform 7 in the presence of the inert gas within the furnace core tube 3 has a first inert gas introducing port 6 which is opened on the inner side near the end on the bottom side, a second inert gas introducing port 12 which is opened on the inner side near the end on a supporting rod 8 side and a gas flow control ring 14 which is disposed above this second inert gas introducing port 12 and acts to guide the inert gas in the furnace to the center at the apex of the furnace core tube 3. A discharge mechanism 16 which allows the inflow of the inert gas from the gas flow control ring 14 and forcibly discharges the inert gas to the outside of the furnace is disposed between the gas flow control ring 14 and an airtight plate 8 enclosing the supporting rod 8. |
