METHOD FOR STRETCHING GLASS ROD

摘要

PURPOSE:To increase precision of an outside diameter in case of heating and stretching a glass rod while measuring the outside diameter of a melted part by an outside diameter measuring instrument by providing a shielding plate between the outside diameter measuring instrument and a burner and inhibiting penetration of burner flames into the outside diameter measuring instrument. CONSTITUTION:Both ends of a glass rod A are held by the rotating chucks 1a, 1b and heated by a burner 3 while rotating it and the glass rod A is stretched by transferring the chucks 1a, 1b in the stretching direction of the glass rod while measuring the outside diameter of a melted part (a) of the glass rod by an outside diameter measuring instrument 4 so that the outside diameter of the melted part (a) due to heating is specified. On this occasion, the flames of a burner 3 are inhibited from penetrating into the measuring instrument 4 by interposing a shielding plate 12 between the measuring instrument 4 and the burner 3. Thereby laser light which is projected from a projector 4a of the measuring instrument 4 and received by a light receiving part 4b is inhibited from being interrupted by the flames, and high-precision stretching for the glass rod can be performed.