Process and device for manufacturing glass sheet
The present invention relates to a process for manufacturing flat sheets of a glass-based material and to an apparatus therefor. The process comprises providing a glass preform, heating the glass preform in a furnace, forming a gob and a pre-sheet, removing the gob and drawing the glass pre-sheet into a flat glass sheet. Also provided is an apparatus for drawing a glass preform into a glass sheet, the apparatus comprising a draw furnace, stretching arms for stretching and drawing the pre-sheet into a glass sheet, and opposing edge rollers for applying a downward force on the glass sheet. The draw furnace may include a plurality of individual heating elements, the temperature of each heating element capable of being separately controlled. The apparatus may further include an annealing furnace for annealing the glass sheet.
1. A method for making a glass sheet comprising:
heating a glass preform in a furnace to form a pre-sheet having a direction of flow;
contacting edges of the pre-sheet with contact bars, thereby causing the pre-sheet to adhere to the contact bars, the contact bars comprising stretching arms;
moving the stretching arms in a direction perpendicular to the direction of flow while the contact bars are adhered to the pre-sheet to stretch the pre-sheet into a glass sheet having a predetermined width;
moving the stretching arms in a direction parallel to the direction of flow to draw the glass sheet downward while the contact bars are adhered to the glass sheet;
engaging the glass sheet with edge rollers; and
drawing the glass sheet to a predetermined thickness.
2. The method according to claim 1 wherein the glass sheet has a thickness less than about 4 mm.
3. The method according to claim 1 wherein the glass sheet has a thickness less than about 1 mm.
4. The method according to claim 1 wherein the glass sheet has a thickness less than about 100 μm.
5. The method according to claim 1 wherein the glass prefonn has a strain point greater than about 600° C.
6. The method according to claim 1 wherein the glass preform has a strain point greater than about 700° C.
7. The method according to claim 1 wherein the glass preform has a strain point greater than about 900° C.
8. The method according to claim 1 wherein a protective coating is applied to the glass sheet during the drawing process.
9. The method according to claim 8 wherein the protective coating is applied as a liquid.
10. The method according to claim 8 wherein the protective coating is applied as a solid film.
11. The method according to claim 1 further comprising the step of rolling the glass sheet onto a spool.
12. The method according to claim 1 further comprising detaching the contact bars from the glass sheet by rotating the stretching arms out of a plane of the glass sheet.