Process and apparatus for the production of glass foil

A process for producing glass foil using a gaseous blowing agent wherein a glass melt is continuously drawn from a heated crucible of a smelting furnace, said furnace having a distribution reservoir feeding annularly arranged distributing slots, having circumferentially arranged conveyor belts, having a draw-off guide roller arranged in a hot bath of liquids, and having an after-treatment zone for treating the glass foil, comprising the steps of:

• (a) heating glass in a smelting furnace until the glass reaches its melting point, and then conveying the glass through a distribution reservoir to annularly arranged distributing slots such that a plurality of jets of glass emerge from the distributing slots;
• (b) combining the plurality of jets of glass emerging from the distributing slots at a funnel-shaped wall to form a hollow, cylindrical mass of glass;
• (c) flowing the hollow, cylindrical mass of glass downward due to its own weight through a heating and cooling zone, said zone being under pressure and being gas-heated, cooling off the glass for shaping, and grasping the hollow, cylindrical mass of glass with circumferentially arranged auxiliary conveyor belts;
• (d) stretching the hollow, cylindrical mass of glass while still in its plastic state to a predetermined wall thickness with the auxiliary conveyor belts, then separating the hollow, cylindrical mass of glass on one side with a separating device and bending the mass of glass into a substantially planar mass of glass, and then conveying the planar mass of glass to a hot bath of liquids wherein a draw-off guide roller is arranged to draw-off glass foil in full width;
• and
• (e) conveying glass foil drawn-off by the draw-off guide roller from the bath of liquids through an after-treatment zone wherein the glass foil is treated to a coiling device, and then coiling the treated glass foil.

Apparatus for producing glass foil using a gaseous blowing agent wherein a glass melt is continuously drawn in the form of a hollow, cylindrical glass mass from a heated crucible of a smelting furnace, comprising:

• a revolving crucible, said crucible being electrically heated and having a pre-melting reservoir, a main-melting reservoir connected to the pre-melting reservoir, and a distribution reservoir connected to the main-melting reservoir;
• an annular distributing disk, said disk being connected to the distribution reservoir and having a plurality of flow-through passages opening onto a funnel-shaped wall;
• a packing/distance tube member for sealing the apparatus from the outside atmosphere;
• heating and cooling means disposed about the hollow, cylindrical glass mass drawn from the crucible for forming a gas cushion about said glass mass;
• conveyor belt means adjacent to said heating and cooling means for stretcing the hollow, cylindrical glass mass;
• bath means for receiving and bathing glass;
• a seal member coaxially disposed relative to said heating and cooling means and extending up to said bath means;
• means for separating the hollow, cylindrical glass mass, said means being located between said seal member and said bath means;
• draw-off guide roller means located in said bath means for drawing-off glass foil in full width from the glass received by said bath means;
• after-treatment means located outside said bath means for receiving and treating the glass foil drawn-off in said bath means;
• and
• means for coiling the glass foil after said foil is treated by said after-treatment means.