Single surface annealing of glass disks
View Patent ↗A method for annealing a glass disk is disclosed. The glass disk is placed on a base, whereby the bottom surface of the glass disk makes a contact with the base, and the top surface of the glass disk is exposed to air. The glass disk is heated with thermal energy supplied to the glass disk, the thermal energy comprising first thermal energy supplied from the air through the top surface and second thermal energy supplied from the base through the bottom surface.
1. A method for annealing a glass disk, the method comprising:
placing the glass disk on a base comprising a sheet of glass having a plurality of openings that facilitate air circulation, whereby the bottom surface of the glass disk makes a contact with the base, and the top surface of the glass disk is exposed to air; and
heating the glass disk with thermal energy supplied to the glass disk, the thermal energy comprising first thermal energy supplied from the air through the top surface and second thermal energy supplied from the base through the bottom surface.
2. The method of claim 1 , wherein the glass disk comprises Lithium Aluminum Silica (LAS).
3. The method of claim 1 , wherein the glass disk has a thickness between about 0.8 and 0.82 mm.
4. The method of claim 1 , wherein a sheet of glass comprises soda lime.
5. The method of claim 4 , wherein the sheet of glass has a thickness between about 10 and 20 mm.
6. The method of claim 1 , wherein the glass disk is heated until its temperature reaches an annealing temperature.
7. The method of claim 6 , wherein the annealing temperature is at or below 580 degrees Celsius.
8. The method of claim 6 , wherein the heating comprises raising the temperature of the glass disk from a room temperature to the annealing temperature.
9. The method of claim 8 , wherein the temperature is raised at a rate between about 4 and 5 degrees Celsius per minute.
10. The method of claim 8 , wherein the temperature raising lasts between about 120 and 135 minutes.
11. The method of claim 8 further comprising, after raising the temperature, maintaining the temperature substantially at the annealing temperature.
12. The method of claim 11 , wherein the temperature maintaining lasts between about 30 and 40 minutes.
13. The method of claim 1 further comprising lowering the temperature of the glass disk after the temperature maintaining.
14. The method of claim 13 , wherein during the temperature lowering, the temperature of the glass disk is lowered from the annealing temperature to the room temperature.
15. The method of claim 14 , wherein the temperature is lowered at a rate between about 3 and 3.5 degrees Celsius per minute.
16. The method of claim 13 , wherein the temperature lowering lasts between about 120 and 165 minutes.