High temp. induction furnace - with graphite heating element pierced with several heating chamber borings, used esp. for prodn. of optical fibres

摘要

Induction furnace for hich temps esp. 2300 degres C consists of a boring open at both ends, inside a heating element, itself surrounded by an induction coil inside a chamber filled with inert gas. Several other furnace-chambers may be provided by similar borings concentrically arranged around the central boring which is coaxial with the outer dia. of the heating element and the induction coil. Used esp. for mfg. preforms for optical fibres and other extrudable materials. Since the working life of the heating element (graphite) is short, the increased no. of working chambers provide locations for heating glass fibre blanks several at once, ready for drawing one after the other with more heat and equipment economy than several plants, esp. since only the outer circumference and the bores of the graphite are exposed to air.