| 摘要 |
PURPOSE:In the optical fiber drawing furnace, the peripheral heating part and the furnace core part are kept air-tight from each other and a noncarbon heat- resistant material is used as the furnace core tube to reduce the formation of dust and produce optical fiber of high strength. CONSTITUTION:In the optical fiber drawing furnace, a noncarbon heat-resistant furnace core tube 5 made of tungsten or yttria is set inside the heating unit 4. The inside of the core tube 5 is kept air-tight on the side of the heating unit 4 with heat-resistant packings 6 such as made of flexible carbon. The parent material 1 is introduced from the top of the furnace, softened by local heating with the heating unit 4 and drawn into an optical fiber. At this time, the inside of the core tube 5 and the heating unit 4 are kept air-tight from each other and so the dusts formed by consumption of the heating unit 4 do not come into the core tube 5, thus giving high-strength optical fibers without adverse effect on its strength caused by dust contamination. |
