GB1073603A - Improvements in or relating to the manufacture of flat glass - Google Patents

Abstract

<PICT:1073603/C1/1> In a method of manufacturing flat glass in ribbon form by the float glass process the molten glass is caused to flow at a controlled rate from a channel in a free fall of 1 1/2 to 6 inches on to the surface of the molten metal bath. The channel may be a spout comprising a floor and side jambs. The free fall of the molten glass from the lip of the spout to the bath ensures that the glass which has formed the upper surface of the glass on the spout continually flows forwardly into the upper surface of the layer on the bath, and the glass which has formed the undersurface of the glass in contact with the spout surface flows rearwardly under the spout thus forming a heel of glass and preventing the glass which was in contact with the spout surface from forming the bottom surface of the advancing glass layer so that bottom surface distortion, derived from physical contact of molten glass with the spout, is minimal. Molten glass 11 flows along a spout 3 which overhands the back wall 14 of a molten metal bath 15, and is allowed to fall on to the surface of the molten metal (e.g. tin or tin alloy). The overhang of the spout, permits the formation of a heel 36 of glass from the underlayer of molten glass in the spout. The molten glass forms a ribbon 35 which is advanced along the bath and cooled by regulators 29 so that it can be removed without damage by rollers 27, 28 through an outlet 21 in the end wall 42. A protective atmosphere is maintained over the molten metal.