| 摘要 |
PURPOSE:To increase considerably the drawing speed of an optical fiber and to reduce a drawing line by enclosing a drawing passage with a partition wall from the outdoor air and providing a stage for cooling the partition wall by passing a cooling refrigerant on the outside of the partition wall before a coating stage. CONSTITUTION:Gaseous N2 (a) is filled in a hollow chamber 8 of the 1st stage of a cooler 5 nearer a heating furnace 12 out of the coolers disposed in series on the drawing line for the optical fiber and is maintained under the pressure slightly higher than the pressure in the outside circumferential atmosphere of the heater 5 to prevent the intrusion of the ambient dust into the hollow chamber 8. The gaseous N2 is passed in a large amt. into the chamber 8 so as to generate 5-10m/s flow rate in the longitudinal direction of the optical fiber in the 2nd stage of the cooler 5. The change of the fiber temp. in the drawing process at 150m/min drawing speed is particularly larger as shown by a dotted line than the fiber temp. change by the natural cooling shown by a solid line between the optical fiber stretching stage provided with the cooling stage and the primary coating stage. |
