Full cylinder production, made of quartz glass, used in production of optical fibers, comprises drawing cylinder out of quartz glass hollow cylinder during vertical drawing

摘要

Production of a full cylinder (18) made of quartz glass comprises drawing the cylinder out of a quartz glass hollow cylinder (5) during a vertical drawing process; feeding the hollow cylinder to a heating zone (4) to soften a region in it; and drawing out the hollow cylinder from the softened region while maintaining the internal pressure inside the inner bore (19) of the hollow cylinder which is lower than the external pressure actin outside of the bore. Production of a full cylinder (18) made of quartz glass comprises drawing the cylinder out of a quartz glass hollow cylinder (5) during a vertical drawing process; feeding the hollow cylinder to a heating zone (4) to soften a region in it; and drawing out the hollow cylinder from the softened region while maintaining the internal pressure inside the inner bore (19) of the hollow cylinder which is lower than the external pressure actin outside of the bore. The vertical drawing process comprises an attraction phase and a drawing phase. The internal pressure gradually decreases by 10 mbar per minute or less until a predetermined set value is reached while simultaneously causing the inner bore to collapse. Preferred Features: The internal pressure is decreased during the time period before completely closing the inner bore depending on a remaining residual diameter.