FURNACE FOR MANUFACTURING OPTICAL FIBERS PREFORMS, PREVENTING OXIDATION OF HEATING ELEMENT AND METHOD FOR MANUFACTURING OPTICAL FIBERS PREFORMS USING THE SAME

摘要

A furnace for manufacturing optical fiber preforms and a method for manufacturing optical fiber preforms by using the same are provided to inhibit oxidation of a heating element and to prevent oxides generated by oxidation of the heating element from being attached onto a preform tube. A furnace for manufacturing optical fiber preforms includes a case(110) having an inlet and an outlet for a preform tube(200); a heating element(120) provided in the case, which surrounds the preform tube while maintaining a gap from the preform tube; muffle tubes(130) which are provided at the inlet and the outlet of the case, respectively to be extended to the vicinity of the heating element while maintaining a gap from an internal surface of the heating element; first and second injection holes(140,140') for injecting inert gas between the heating element and the case, which are provided at both ends of the heating element. In the furnace, each flow amount(A',B') of inert gas being injected into the first and second injection hole, and a transfer speed(C) along a process direction of the furnace satisfy the formulae: A>=5.2Îexp(0.15ÎB) and A+B>=0.23ÎC+5.5.