OPTICAL FIBER DRAWING FURNACE

摘要

PURPOSE:To suppress the fluctuation in a diameter of the optical fiber to a lower level even if a large-sized base material is drawn by providing a heat insulating material in at least a part of the circumference of an inside cylindrical pipe and specifying the min. temp. of the inert gas in a drawing chamber. CONSTITUTION:The heat insulating material 20 is provided around the inside cylindrical pipe 7 and the inert gas from the inside of the inside cylindrical pipe 7 is heated by the heat from a heater 4. The flow of the inert gas of a relatively high temp. is generated in the space A on the side upper than the optical fiber base material 10. A part of the optical fiber base material 10 of the relatively high-temp. flow passes around the circumference of the optical fiber base material 10 and flows into the space B which is the drawing part on the lower side of the optical fiber base material 10. Since the temp. difference between the gas in the space B and the gas in the space A is smaller than heretofore, the drawing is stably executed without disturbing the gaseous flow in the space B.