| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wire drawing furnace equipped with a seal structure which has a sufficient sealing function even when a glass preform with large variations in outer diameter is used in wire drawing. <P>SOLUTION: The wire drawing furnace includes an upper end opening 2a into which the glass preform 5 for optical fiber drawing is loaded, a furnace core tube 3 to hold the glass preform 5 loaded from the upper end opening 2a, a heating source to heat and melt the glass preform 5 held in the furnace core tube 3, and the seal structure 11 to seal a clearance between the upper end opening 2a and the glass preform 5. The seal structure 11 is equipped with a seal member 13 disposed so as to surround the glass preform 5, which is heat resistant and flexible and is pressed to the outer peripheral surface of the glass preform 5 by the pressure of a seal gas, to seal the clearance. <P>COPYRIGHT: (C)2012,JPO&INPIT |
