JP2922483B

Apparatus (10) for forming a cased glass stream having an inner core glass surrounded by an outer casing glass includes a spout (13) for receiving core glass from a first source (12) and delivering such glass through a first orifice (22). A second orifice (28) is vertically spaced beneath and aligned with the first orifice, and is surrounded by an annular chamber (30) that communicates with the second orifice through the gap between the first and second orifices. A tube (32) delivers casing glass from a second source (40) to the annular chamber in such a way that glass flows by gravity from the first and second sources through the orifices to form the cased glass stream. The core glass delivery spout includes a reservoir (12) for receiving and holding the core glass, and having at least one lower opening (16) of a first diameter. An orifice ring (24) is positioned beneath the reservoir, and has at least one opening of second diameter less than the first diameter aligned with the first opening and forming the first orifice (22). A collar of uniform inside diameter equal to the first diameter extends from the first opening to the orifice ring, and thereby spaces the reservoir from the orifice ring so as to increase hydrostatic head pressure on glass flowing from the reservoir through the first orifice. The core glass reservoir is surrounded by a metal casing (18), and the casing glass delivery tube extends through a notch in the sidewall of the core glass casing. An air-cooled liner controls heat transfer from the casing glass delivery tube to the core glass reservoir.