| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a thread part from being left on a glass drop by a simple structure by disposing a thread cutting member which partly projects from the end face of a nozzle within the periphery of the nozzle. SOLUTION: A plurality of through-holes 6b are arranged in a thread cutting member 6b set in a nozzle 1, and the glass flowing down from a crucible is passed through the through-holes. The columnar part 6d of the thread cutting member 6 projects from the end face 1a of the nozzle 1, and the tip 6c is made conical. Further, an annular-sectioned glass passage 1b is formed by the inner face of the nozzle 1 and the outer face of the columnar part 6d of the thread cutting member 6, and glass is allowed to flow down therefrom. Since the glass hardly flows down when the passage 1b is narrow and the thread part is easily formed when the passage is wide, the cross-sectional area is preferably controlled to 0.8-51 mm2. The projection of the thread cutting member 6 from the end face 1a of the nozzle 1 is preferably adjusted to 1-7 mm.</p> |
