PRODUCITON OF PREFORM ROD

摘要

PURPOSE:To obtain a preform rod without making the core rod eccentric by guiding a detachbly fixed eccentricity-preventive moving body along the axis of rotation of the core rod by a guide cylinder when the core rod is moved. CONSTITUTION:A rotary holder 11 is rotated to turn a core rod 10 with the center axis as the axis of rotation. Meanwhile, soot is blown against the rod 10 from burners 14 and 15 and deposited to form a clad layer 20 on the rod 10, and a lift 12 is moved upward in synchronization with the growth rate of the clad layer 20. The lower end of the rod 10 is held through an eccentricity- preventive moving body 17 and a guide cylinder 16 so that the center axis of the rod 10 is positioned on the axis of rotation of the holder 11. Accordingly, the rod 10 is not bent even if soot is blown against it, and the moving body 17 is moved concentrically upward in the guide cylinder 16 along with the rod 10 while the rod 10 is lifted up by the lift 12.