Apparatus for drawing glass tapes
AssigneeSchott Glaswerke
InventorFranz Guenthner
Life of this patent
Estimating the term…
Abstract
A method for drawing glass sheets of crystallization-sensitive glass such as borosilicate glass or glass ceramic. A melt in a vat of a glass furnace is supplied through a feed channel to a drawing chamber from which a glass sheet is drawn perpendicularly upwardly essentially across a full width of the drawing chamber. The melt in the drawing chamber is heated by at least two current-charged precious metal strips at each of the opposite sides of a drawing plane in a region of the surface of the sheet. This heating occurs in sections at each side of the drawing plans so that the melt is sectionally heated and crystallization at walls of the drawing chamber lying opposite one another at the vertical drawing plane is effectively prevented. In addition, the drawing chamber can be sectionally covered by slides.
Claims11
A glass sheet drawing apparatus for crystallization-sensitive glass wherein a glass sheet is drawn from a glass melt, comprising:
- a drawing chamber means for receiving the glass melt such that a surface of the glass melt is at a given design level;
- a closed feed channel means for connecting said drawing chamber means to a glass melt source, an uppermost portion of said closed feed channel means lying below said design level for the surface of the glass melt;
- and a width of said feed channel means being less than an interior width of said drawing chamber means where said feed channel means enters;
- a drawing means positioned above said drawing chamber means for drawing a glass sheet in a drawing plane;
- at each side of the drawing plane in the drawing chamber means at least two heating strip means for resistance type radiant heating of the melt, the heating strip means being arranged parallel and side-by-side substantially across said interior width of said drawing chamber means, each of the strip means being positioned at said design level for the surface of the melt and extending above and below said design level within a region at the design level;
- each of the at least two heating strip means at each side of the drawing plane of the glass sheet having connection means for connecting each strip means to an independently controllable heater circuit means for indirectly heating the glass melt by independently heating each of the strip means at the opposite sides of the drawing plane so that said interior width of the heating chamber at each side of the glass sheet is differently heatable in at least two sections;
- heating means positioned in said drawing chamber means and below a level of said heating strip means and which are heatable independently of the heating strip means;
- and
- means for cooling the surface of the melt at said design level for cooling glass layers of the melt flowing to a root of the melt where the glass sheet is drawn from the melt.
Dependencies are inferred from the claim text.