METHOD FOR DRAWING GLASS PREFORM

摘要

PROBLEM TO BE SOLVED: To provide a method for drawing a glass preform capable of performing such drawing that the external diameter after the drawing is made uniform. SOLUTION: The glass preform 11 is lowered by parting an upper chuck 12 clamping the upper part of the glass preform 11 and a lower chuck 12 clamping the lower part thereof relatively from each other. Namely, the descending speed of the lower chuck 12 is higher than the descending speed of the upper chuck 12 and therefore the glass preform 11 is drawn during descending. At this time, only the descending speed of the lower chuck 12 is made gradually higher in accordance with the amount of descending of the glass preform 11 and therefore the drawing speed is gradually increased and the glass preform 11 is eventually drawn to a smaller diameter. As a result, the external diameter which heretofore increases gradually toward the end of the drawing can be made uniform. COPYRIGHT: (C)2004,JPO