PRODUCTION OF PREFORM FOR NONOXIDE GLASS FIBER

摘要

PURPOSE:To easily produce the long-sized preform for a nonoxide glass fiber in which foams, striae and crystals do not exist by bringing the polished surfaces of glass for a clad having a polished base and core glass into contact with each other and extruding and welding the glass under heating in an extruder. CONSTITUTION:The nonoxide glass having nearly parallel surfaces is molded to the shape nearly the same as the cross section of an extruding punch 3 and the base is polished to produce the glass 4 for the clad and the glass 5 for the core. The polished surfaces of the glass 4 for the clad and the glass 5 for the core are brought into contact (characteristic optical contact) with each other and are put into a cylinder 1 in such a manner that the glass 4 for the clad exists on a molding part 2 side. The glass is then heated to the temp. above the yield point of the glass and below the crystallization initiation temp. and is extruded from a molding hole 2a by the extruding punch. The extruded glass is slowly cooled in a liner part 6 and the preform for the glass fiber is obtd.