DRAWING FURNACE CONTAINING DOUBLE CRUCIBLE

摘要

PURPOSE:To provide a drawing furnace capable of producing a high-quality optical fiber by preventing the contact of an optical fiber with oxygen and moisture in air in the course of drawing. CONSTITUTION:The drawing furnace is provided with a double crucible 2 composed of an inner crucible and an outer crucible having respective nozzles at the bottoms and an upper frame 12 and a lower frame 11 placed interposing a prescribed gap held by heat-resistant tubes 21, 22, 23. The outer crucible 3 is attached to the lower frame 11 and the top of the inner crucible 4 is fixed to a jig 13 attached to the upper frame 12.