Abstract: A glass tube manufacturing apparatus for manufacturing glass tubing includes a glass delivery tank with molten glass. The glass delivery tank has a bottom opening. A bell has an upper portion with an outer diameter located at the bottom opening. A heating apparatus is at least partially disposed around the bell. The heating apparatus includes a heated portion and a muffle portion located below the heated portion. A lower extended muffle structure extends downwardly from the muffle portion. The lower extended muffle structure extending about the glass tubing on all sides to manage convective airflow therethrough.

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.

Abstract: Embodiments of glass forming apparatuses are disclosed herein. In one embodiment, a glass forming apparatus may include a forming body defining a draw plane extending from the forming body in a draw direction. An actively-cooled thermal sink may be positioned below the forming body in the draw direction and spaced apart from the draw plane. An infrared-transparent barrier may be positioned between the actively-cooled thermal sink and the draw plane. The infrared-transparent barrier may comprise an infrared-transparent wall positioned proximate the actively-cooled thermal sink or an infrared-transparent jacket positioned around the actively-cooled thermal sink.

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.

Abstract: A glass tube manufacturing apparatus for manufacturing glass tubing includes a glass delivery tank with molten glass. The glass delivery tank has a bottom opening. A bell has an upper portion with an outer diameter located at the bottom opening. A heating apparatus is at least partially disposed around the bell. The heating apparatus includes a heating portion and a muffle portion located below the heating portion. A lower extended muffle structure extends downwardly from the muffle portion. The lower extended muffle structure extending about a periphery of the glass tubing to manage convective airflow therethrough.