A method for severing a glass sheet includes preferentially heating a region of the glass sheet to form a softened region. A slit is formed in the softened region of the glass sheet to form a slit region. The slit extends at least partially into a thickness of the glass sheet. Heat is preferentially applied to the slit region of the glass sheet.

A method of producing a glass vessel includes holding a borosilicate glass tube with a first holding device, and holding an open end portion of the glass tube with a second holding device such that the second holding device is spaced apart from the first holding device. Heat is applied to the glass tube by a burner to separate the open end portion and form a bottom portion on the open end portion. Fire-blast treatment of an inner surface of the open end portion with a flame from a point burner is performed during at least a part of (i) applying heat to the borosilicate glass tube for separation, (ii) applying heat to the separated open end portion for bottom portion formation, and/or (iii) a period applying heat to the separated open end portion and prior to releasing the glass vessel from the second holding device.

A method of producing a glass vessel includes holding a borosilicate glass tube with a first holding device, and holding an open end portion of the glass tube with a second holding device such that the second holding device is spaced apart from the first holding device. Heat is applied to the glass tube by a burner to separate the open end portion and form a bottom portion on the open end portion. Fire-blast treatment of an inner surface of the open end portion with a flame from a point burner is performed during at least a part of (i) applying heat to the borosilicate glass tube for separation, (ii) applying heat to the separated open end portion for bottom portion formation, and/or (iii) a period applying heat to the separated open end portion and prior to releasing the glass vessel from the second holding device.

A method includes indirectly engaging a surface of a moving ribbon of inorganic material with a non-contacting support unit. The ribbon is severed with a thermal separating unit while the non-contacting support unit is indirectly engaged with the ribbon.

A method includes indirectly engaging a surface of a moving ribbon of inorganic material with a non-contacting support unit. The ribbon is severed with a thermal separating unit while the non-contacting support unit is indirectly engaged with the ribbon.

An improved method and an improved apparatus are provided for producing a thin glass ribbon, which provide borders at the edges of the ribbon. The edges formed are of high mechanical quality and a formation of new secondary borders after the severing or at least the thickness of such secondary borders is reduced compared to the original borders. The method includes drawing the thin glass ribbon from a molten glass or from a preform, severing the borders, and cooling the resulting glass ribbon. The severing is effected at a location along the moving direction of the thin glass ribbon and at a time at which during the cooling of the thin glass ribbon the viscosity of the glass is in a range from 10.sup.7 dPa.Math.s to 10.sup.11 dPa.Math.s, so that the edges of the thin glass ribbon newly produced by the severing of the borders are rounded off.

An improved method and an improved apparatus are provided for producing a thin glass ribbon, which provide borders at the edges of the ribbon. The edges formed are of high mechanical quality and a formation of new secondary borders after the severing or at least the thickness of such secondary borders is reduced compared to the original borders. The method includes drawing the thin glass ribbon from a molten glass or from a preform, severing the borders, and cooling the resulting glass ribbon. The severing is effected at a location along the moving direction of the thin glass ribbon and at a time at which during the cooling of the thin glass ribbon the viscosity of the glass is in a range from 10.sup.7 dPa.Math.s to 10.sup.11 dPa.Math.s, so that the edges of the thin glass ribbon newly produced by the severing of the borders are rounded off.