GB1103276A - Improvements in or relating to the manufacture of flat glass - Google Patents

Abstract

<PICT:1103276/C1/1> In the manufacture of flat glass during which the glass is advanced in ribbon form on a bath of molten metal, the transfer of impurities in the molten metal to the interface between the glass ribbon and the molten metal from parts of the bath surface which are exposed to the atmosphere ove the bath is impeded preferably by one or more physical barriers, thus reducing the uptake of contaminants by the bottom surface of the glass ribbon. The barriers are in the form of screens 12 arranged vertically in the bath 3 on either side of the glass ribbon 11. They may be of denser or lighter material than the molten metal (e.g. tin) of the bath, and may be made of carbon, or refractory material or spheroidal graphite iron. The screens 12 may extend from the floor of the bath to the surface of the molten metal, or extend from the floor to just below the molten metal surface, or they may float with their upper edges above the surface and their lower edges above the bath floor. They may also be supported in position by arms located in the side walls of the tank structure above the bath, see Figs. 2a to 2c (not shown). The screens may also be in the form of partially submerged boats or V-shaped channel members. The screens are maintained spaced apart from the glass ribbon. In an alternative embodiment a pocket 16 (Fig.3) may be built into the tank structure so that an additive may be put into the molten metal as in Specification 1,025,583. Screens 12a seal off the pocket 16 from the rest of the bath.