GB960497A - Apparatus for drawing sheet glass - Google Patents

Abstract

An apparatus for drawing sheet glass from a bath of molten glass through a drawing chamber partially defined by refractory members supported on each side of the plane of draw of the glass sheet, a cooling member being on each side of the plane of draw of the glass sheet within the drawing chamber, comprises sheet-like insulating refractory material impervious to gases and partially transparent to infra-red radiation closely adjacent at least one major surface of the cooling member. In a sheet drawing apparatus, Fig. 2, in which a sheet 10 is drawn from molten glass 12 in a drawing chamber 22 by rolls 18 in a chamber 20, the chamber 22 is substantially enclosed, with the sheet 10 passing up between catch pans 30 and L-blocks 24 lying adjacent the molten glass 12. The air flow within the chamber 22 is modified by burners 44 sited adjacent L-blocks 24 and <PICT:0960497/C1/1> <PICT:0960497/C1/2> by L-shaped coolers 32 backed by plates 36 of silica or 96% silica glass or other high softening point glass. In another embodiment, Fig. 3, each cooler comprises a taller L-shaped cooler 40 backed with a plate 36 and carrying an additional silica or silica glass plate 46. In a further embodiment, particularly suitable for drawing thin glass sheets, plates of silica or silica glass cover substantially the whole of the front surface of the cooler. Mounting means for the silica and silica glass plates are described. A suitable high softening point glass comprises 43-49% SiO2, 7-12% CaO, 5-8% MgO, 19-26% Al2O3, 4-10% B2O3, 6-12% BaO and 0.1-2% Na2O. A suitable 96% silica glass comprises 96.3% SiO2, 2.9% B2O3, 0.4% Al2O3 and 0.4% other alkalies. Reference has been directed by the Comptroller to Specification 908,148.