Corning Incorporated
Apparatuses and methods for heating and cooling glass tubing

Abstract:

A muffle for a glass tube forming process includes an inlet end coupled to a bowl, an outlet end having an inner dimension larger than an inner dimension of the inlet end, and a sidewall extending from inlet end to the outlet end. A radial distance from a center axis of the muffle to an inner surface of the sidewall increases from the inlet end to the outlet end and the sidewall is substantially free of abrupt changes in the radial distance that produce instability regions within the muffle. The muffle includes a channel between an outer surface of a portion of the sidewall and an insulating layer disposed about the sidewall, the channel being operable to pass a heat transfer fluid into thermal communication with the sidewall to provide cooling to the muffle. Glass forming systems including the muffle and glass tube forming processes are also disclosed.