METHOD AND APPARATUS FOR DELIVERING A GLASS STREAM FOR FORMING CHARGES OF GLASS

A method and apparatus for delivering a glass stream comprising a first inner layer and a second outer layer, comprising a generally vertical orifice, and delivering glass from a second source such that the glass from said second source provides an outer layer about the glass from the first source as it flows through said orifice. A resistance heated tube assembly is made of platinum or material having similar resistance heating properties and extends from a glass source to an orifice through which the glass flows from a glass source for the inner layer. The tube assembly includes a tube portion having an inlet end that communicates with the source for the outer layer and an outlet end that communicates with the source. The tube portion has an axis positioned at any angle ranging between the horizontal and vertical but preferably has an axis which is more vertical than horizontal. Flanges are secured to the ends of said tube portion, and the flanges are connected to an electric power supply. The cross sectional thickness of said flanges is preferably greater than the thickness of the tube portion. Each flange includes an annular groove adjacent its respective end of the tube portion into which the end of said tube portion extends. The flanges are welded to the tube portion. Flange heater modulessurround each end of the tube portion.