Methods and apparatus for forming a glass ribbon

A forming roll comprising:

• a working zone portion comprising a working zone surface for engaging a stream of molten glass, the working zone surface including a length extending along a rotation axis of the forming roll;
• and
• a frustoconical groove defined in the forming roll and extending at an acute angle relative to the rotation axis of the forming roll.

A method of forming a glass ribbon with at least one forming roll and a forming body spaced to define a glass forming gap between the forming roll and forming body, wherein the forming roll comprises a working zone portion comprising a working zone surface including a length extending along a rotation axis of the forming roll, wherein the forming roll includes a thermal resistance boundary extending at an acute angle relative to the rotation axis of the forming roll, the method comprising the steps of:

• (I) supplying a stream of molten glass;
• and
• (II) feeding the stream of molten glass through the gap to form a glass ribbon including a formed thickness, wherein the thermal resistance boundary facilitates substantial uniform radial expansion of the working zone surface relative to the rotation axis across the length of the working zone surface in response to heating of the working zone portion by the molten glass.