Apparatus for, and method of, roll forming sheets of high refractive index glass

Patent metadata

Field	Value
Publication number	US-11964895-B2
Application number	US-202318119570-A
Country	US
Kind code	B2
Filing date	Mar 9, 2023
Priority date	Nov 13, 2020
Publication date	Apr 23, 2024
Grant date	Apr 23, 2024

Abstract

A method of forming a glass sheet comprises: (a) forming a ribbon of glass from molten glass with a pair of forming rollers; (b) reducing horizontal temperature variability of the ribbon of glass to be 10° C. or less across 80 percent of an entire width of the ribbon of glass before the ribbon of glass cools to a glass transition temperature; (c) controlling a cooling rate of the ribbon of glass while the ribbon of glass moves vertically downward within a setting zone such that the ribbon of glass has a first average cooling rate before the ribbon of glass cools to the glass transition temperature and a second average cooling rate after the ribbon of glass cools to the glass transition temperature, the first average cooling rate being less than the second average cooling rate; and (d) separating a glass sheet from the ribbon of glass.

First claim

The invention claimed is:

1. A method of forming a ribbon of glass comprising:
supplying molten glass into a gap separating a pair of forming rollers,
the molten glass having a viscosity of 0.01 Poise to 3000 Poise, and
each of the pair of forming rollers having an outer diameter of 20 mm to 80 mm;

forming the ribbon of glass from the molten glass; and
(i) reducing a rate of temperature decrease of the ribbon of glass vertically before the ribbon of glass cools to a glass transition temperature, and/or (ii) increasing the rate of temperature decrease of the ribbon of glass vertically after the ribbon of glass has cooled to the glass transition temperature.

2. The method of claim 1 , further comprising controlling horizontal temperature variability of the ribbon of glass to be 10° C. or less across 80 percent of an entire width of the ribbon of glass before the ribbon of glass cools to the glass transition temperature.

3. The method of claim 2 , further comprising controlling the horizontal temperature variability of the ribbon of glass to be 10° C. or less across 95 percent of the entire width of the ribbon of glass before the ribbon of glass cools to the glass transition temperature.

4. The method of claim 2 , further comprising controlling the horizontal temperature variability of the ribbon of glass to be 5° C. or less across 80 percent of the entire width of the ribbon of glass before the ribbon of glass cools to the glass transition temperature.

5. The method of claim 4 , further comprising controlling the horizontal temperature variability of the ribbon of glass to be 5° C. or less across 95 percent of the entire width of the ribbon of glass before the ribbon of glass cools to the glass transition temperature.

6. The method of claim 1 , further comprising cooling lateral edges of the ribbon of glass.

7. The method of claim 1 , further comprising reducing heat loss at a center portion of the ribbon of glass but not at lateral edges of the ribbon of glass.

8. The method of claim 1 , further comprising controlling a cooling rate of the ribbon of glass while the ribbon glass moves vertically downward within a setting zone such that the ribbon of glass has a first cooling rate before the ribbon of glass cools to the glass transition temperature and a second cooling rate after the ribbon of glass cools to the glass transition temperature, the first cooling rate being less than the second cooling rate.

9. The method of claim 8 , wherein the ribbon of glass cools at the first cooling rate from 50° C. above the glass transition temperature to the glass transition temperature and wherein the ribbon of glass cools at the second cooling rate from the glass transition temperature to 50° C. below the glass transition temperature.

10. The method of claim 8 , further comprising heating the ribbon of glass with heating elements to control the cooling rate of the ribbon of glass.

11. The method of claim 10 , further comprising blowing fluid at the ribbon of glass after the ribbon of glass has cooled to the glass transition temperature.

12. The method of claim 1 , wherein after the pair of forming roller has formed the ribbon of glass, the ribbon of glass has a viscosity of about 10 7 Poise.

13. The method of claim 1 , further comprising separating a glass sheet from the ribbon of glass.

14. The method of claim 13 , wherein the glass sheet has a warp of 100 microns or less.

15. The method of claim 14 , wherein the glass sheet has warp of 25 microns or less.

16. The method of claim 13 , wherein the glass sheet has a total thickness variation of 100 microns or less.

17. The method of claim 13 , wherein:
the glass sheet has a warp of 100 microns or less,
the glass sheet has a total thickness variation of 100 microns or less, and
the glass sheet has a thickness of 0.1 mm to 3.0 mm.

18. The method of claim 13 , wherein the glass sheet has an index of refraction of 1.65 or greater.

19. The method of claim 18 , wherein the glass sheet has an index of refraction of 1.7 or greater.

Assignees

• Corning Inc

Inventors

• Bressler Douglas Dale
• Deneka David Alan
• Gerrish Michael Charles
• Jennings Douglas Hull
• Kunitake Miki Eugene
• Lock William Edward
• Mudiraj Shyam Prasad
• Partridge Neil Eugene
• Payne Jeremy Nathan
• Proulx Ii Eugene Roland
• Sutton Ryan Christopher
• Tarcza Steven Howard

Classifications

• C03B17/067 Primary

  combined with thermal conditioning of the sheets · CPC title

• C03B17/068

  Means for providing the drawing force, e.g. traction or draw rollers · CPC title

• C03B17/064 Primary

  by the overflow downdraw fusion process; Isopipes therefor · CPC title

• C03B25/02

  in a discontinuous way · CPC title

• C03C3/062

  with less than 40% silica by weight · CPC title