| 摘要 |
PURPOSE:To enable even a glass tube of a large thickness and large diameter to be collapsed in a short time by moving and heating the rotating glass tube and axially stretching the same to the glass tube of a smaller thickness and diamater then stopping the stretching. CONSTITUTION:A glass tube 1 which has a refractive index distribution in its section is rotated like an arrow 3 at a constant revolving speed. A heater 2 moves the tube 1 in the direction of an arrow 4 at a constant temperature and a constant speed. At this time, the tube 1 is stretched at a constant speed in the direction of an arrow 5 in the direction opposite from the arrow 4, becoming the glass tube 1a of the reduced outside diameter and thickness. Next, when pulling in the axial direction is stopped, the tube 1a being rotated, moved and heated becomes a solid glass bar. |
