Abstract: Heating apparatuses and methods for glass tubing manufacturing are disclosed. A heating apparatus for glass tubing manufacturing includes a bowl configured to receive molten glass and a plurality of heating elements thermally coupled to the bowl. The bowl has a bowl height and includes a tub portion configured to hold the molten glass, a bowl well extending beneath the tub portion, and an orifice at a distal end of the bowl well. The plurality of heating elements include a first heating element disposed at a first vertical location along the bowl height, a second heating element disposed at a second vertical location along the bowl height, wherein the first vertical location is vertically spaced apart from the second vertical location.

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: An apparatus for producing composite glass tube with a plurality of glass layers includes a plurality of cylindrical containers of increasing inner dimensions concentrically arranged and stationary. Each cylindrical container includes a side wall, bottom wall, and a delivery ring. Adjacent cylindrical containers define an annular chamber, a flow control region, and an annular flow channel therebetween. The apparatus includes at least one flow control valve positioned in the flow control region and translatable relative to the adjacent cylindrical containers. Translation of the flow control valves relative to the cylindrical containers is operable to change an impedance to flow of molten glass through the flow control region, thereby modifying an overall flow rate or circumferential distribution of molten glass from the cylindrical containers. Systems and methods for producing composite glass tube using the apparatus are also disclosed.

Abstract: An apparatus for producing composite glass tube with a plurality of glass layers includes a plurality of cylindrical containers of increasing inner dimensions concentrically arranged and stationary. Each cylindrical container includes a side wall, bottom wall, and a delivery ring. Adjacent cylindrical containers define an annular chamber, a flow control region, and an annular flow channel therebetween. The apparatus includes at least one flow control valve positioned in the flow control region and translatable relative to the adjacent cylindrical containers. Translation of the flow control valves relative to the cylindrical containers is operable to change an impedance to flow of molten glass through the flow control region, thereby modifying an overall flow rate or circumferential distribution of molten glass from the cylindrical containers. Systems and methods for producing composite glass tube using the apparatus are also disclosed.

Abstract: Disclosed is an apparatus and method of making molten glass. The apparatus includes a glass former having a slot orifice design to deliver a glass ribbon. The slot orifice design can include a transition section, a slot extension, and external structural reinforcements. In some embodiments, the orifice opening distance of the slot extension varies along the width of the orifice. In some embodiments, the orifice has an orifice opening distance that is smaller at the center of the slot extension than at the edges of the slot extension, which limits glass flow at the center of the slot extension. Also disclosed is a method of making glass using the disclosed apparatus.

Abstract: A bell assembly for a glass tubing manufacturing apparatus includes a bell head and a support connected to the bell head. The support includes a bell shaft with an inner bore and an outer surface, and a liner positioned in the inner bore of the bell shaft. A thermal shield extends along the outer surface of the bell shaft and reduces temperature variation across a width of the bell shaft during glass tubing manufacturing.

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: An apparatus for producing composite glass tube with a plurality of glass layers includes a plurality of cylindrical containers of increasing inner dimensions concentrically arranged and stationary. Each cylindrical container includes a side wall, bottom wall, and a delivery ring. Adjacent cylindrical containers define an annular chamber, a flow control region, and an annular flow channel therebetween. The apparatus includes at least one flow control valve positioned in the flow control region and translatable relative to the adjacent cylindrical containers. Translation of the flow control valves relative to the cylindrical containers is operable to change an impedance to flow of molten glass through the flow control region, thereby modifying an overall flow rate or circumferential distribution of molten glass from the cylindrical containers. Systems and methods for producing composite glass tube using the apparatus are also disclosed.

Abstract: An apparatus for producing composite glass tube with a plurality of glass layers includes a plurality of cylindrical containers of increasing inner dimensions concentrically arranged and stationary. Each cylindrical container includes a side wall, bottom wall, and a delivery ring. Adjacent cylindrical containers define an annular chamber, a flow control region, and an annular flow channel therebetween. The apparatus includes at least one flow control valve positioned in the flow control region and translatable relative to the adjacent cylindrical containers. Translation of the flow control valves relative to the cylindrical containers is operable to change an impedance to flow of molten glass through the flow control region, thereby modifying an overall flow rate or circumferential distribution of molten glass from the cylindrical containers. Systems and methods for producing composite glass tube using the apparatus are also disclosed.

Abstract: Disclosed is an apparatus and method of making molten glass. The apparatus includes a glass former having a slot orifice design to deliver a glass ribbon. The slot orifice design can include a transition section, a slot extension, and external structural reinforcements. In some embodiments, the orifice opening distance of the slot extension varies along the width of the orifice. In some embodiments, the orifice has an orifice opening distance that is smaller at the center of the slot extension than at the edges of the slot extension, which limits glass flow at the center of the slot extension. Also disclosed is a method of making glass using the disclosed apparatus.

Abstract: A prefiner (28) is described and includes a chamber (34) for receiving molten glass exiting a submerged combustion melter. The prefiner (28) also includes a foam breaker (36) and an exit conduit (38). The molten glass holding chamber includes a top portion (42), a bottom portion (40), and an enclosing sidewall (44). The top portion (42) includes an opening to accommodate the foam breaker (36), which is positioned to break the glass bubbles within the chamber. The exit conduit (38) resides within the chamber (34) and is in fluid communication with an outlet (68) in the sidewall (44). The exit conduit (38) is positioned to permit molten glass to flow from the lower section of the chamber to the outlet (68) and to the next stage of processing, typically a finer.

Abstract: Heating apparatuses and methods for glass tubing manufacturing are disclosed. A heating apparatus for glass tubing manufacturing includes a bowl configured to receive molten glass and a plurality of heating elements thermally coupled to the bowl. The bowl has a bowl height and includes a tub portion configured to hold the molten glass, a bowl well extending beneath the tub portion, and an orifice at a distal end of the bowl well. The plurality of heating elements include a first heating element disposed at a first vertical location along the bowl height, a second heating element disposed at a second vertical location along the bowl height, wherein the first vertical location is vertically spaced apart from the second vertical location.

Abstract: A bell assembly for a glass tubing manufacturing apparatus includes a bell head and a support connected to the bell head. The support includes a bell shaft with an inner bore and an outer surface, and a liner positioned in the inner bore of the bell shaft. A thermal shield extends along the outer surface of the bell shaft and reduces temperature variation across a width of the bell shaft during glass tubing manufacturing.

Abstract: A prefmer (28) is described and includes a chamber (34) for receiving molten glass exiting a submerged combustion melter. The prefmer (28) also includes a foam breaker (36) and an exit conduit (38). The molten glass holding chamber includes a top portion (42), a bottom portion (40), and an enclosing sidewall (44). The top portion (42) includes an opening to accommodate the foam breaker (36), which is positioned to break the glass bubbles within the chamber. The exit conduit (38) resides within the chamber (34) and is in fluid communication with an outlet (68) in the sidewall (44) The exit conduit (38) is positioned to permit molten glass to flow from the lower section of the chamber to the outlet (68) and to the next stage of processing, typically a finer.