Process and Device for Manufacturing Flat Sheets of a Glass-Based Material

• US 20090019892A1
• Filed: 03/10/2006
• Published: 01/22/2009
• Est. Priority Date: 04/06/2005
• Status: Abandoned Application

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Tellier, Xavier, Gille, Claude Francois Maurice, Fredholm, Allan Mark, Pierron, Christophe
• Application Number:
  US11/918,029
• Publication Number:
  US 20090019892A1
• Time in Patent Office: Days
• US Class Current: 65/91
• CPC Class Codes: C03B 13/00 Rolling molten glass , i.e. where the molten glass is shaped by rolling re-forming shaped glass by rolling C03B23/004, C03B23/033, C03B23/055
• CPC Class Codes: C03B 17/06 Forming glass sheets
• CPC Class Codes: C03B 17/064 by the overflow downdraw fusion process; Isopipes therefor
• CPC Class Codes: C03B 40/04 using gas

Abstract

The present invention relates to a process for manufacturing flat sheets of a glass-based material and to a device associated with the process. The process comprises delivering the glass-based material (10) from a delivery system (16) to a reservoir (24) between two porous walls (12), the reservoir having a vertical length (L), a horizontal width (W) between side edges (22, 22′ of the walls and including a gap (14) between the walls which varies along the vertical length of the reservoir, the material being separated from the walls by a gas film (28), drawing the glass-based material in a sheet from an outlet of the reservoir, and wherein a flow of the glass-based material delivered to the reservoir is varied across the width of the reservoir, or wherein the gap (14) varies across the horizontal width (w) of the reservoir (24)

Claims

1. A method of drawing flat sheets of glass-based material comprising:

delivering a glass-based material (10) from a delivery system (16) to a reservoir (24) between two porous walls (12), the reservoir having a vertical length (L), a horizontal width (W) between side edges (22, 22′

) of the walls and including a gap (14) between the walls which varies along the vertical length of the reservoir, the material being separated from the walls by a gas film (28);

drawing the glass-based material in a sheet from an outlet of the reservoir; and

wherein a flow of the glass-based material delivered to the reservoir is varied across the width of the reservoir.

2. The method according to claim 1 wherein the flow of glass-based material delivered to a medial portion of the reservoir is greater than the flow delivered to a region of the reservoir adjacent the side edges.

3. The method according to claim 2 wherein the flow delivered adjacent the side edges is between about 10% and 30% of the flow delivered to the medial portion.

4. The method according to claim 1 wherein the glass-based material has a viscosity less than about 100,000 poise at the reservoir outlet.

5. The method according to claim 1 wherein the gas film is formed by delivering a gas (30) to pores in the porous walls through passages (38) which vary in size in a direction of flow of the glass-based material.

6. The method according to claim 5 wherein the passages increase in size in a direction of flow of the glass-based material.

7. The method according to claim 1 wherein a portion of the glass-based material delivered to the reservoir extends beyond the outside edges of the reservoir walls and the step of drawing comprises contacting the glass-based material extending beyond the side edges with opposing rollers (50) adjacent the side edges.

8. The method according to claim 7 wherein an axis of rotation (56) of the opposing rollers is no more than about 10 mm below an outlet level (B) of the reservoir.

9. The method according to claim 7 wherein a distance (54) separating the opposing rollers is maintained constant as the sheet of glass-based material is drawn.

10. The method according to claim 7 wherein a distance (54) separating the opposing rollers varies as the sheet of glass-based material is drawn.

11. The method according to claim 1 wherein the reservoir walls are formed by two rotating porous cylinders (62).

12. The method according to claim 1 wherein a head of the glass-based material in a medial portion of the reservoir is greater than a head of the glass-based material in a region of the reservoir adjacent the side edges.

13. A method of drawing flat sheets of a glass-based material comprising:

delivering a glass-based material (10) from a delivery system (16) to a reservoir (24) between two porous walls (12), the reservoir having a vertical length, a horizontal width between side edges (22, 22′

) of the walls and including a gap (14) between the walls which varies along the vertical length of the reservoir, the material being separated from the walls by a gas film (28);

drawing the glass-based material in a sheet from an outlet of the reservoir; and

wherein the gap varies across the horizontal width of the reservoir.

14. The method according to claim 13 wherein the gap is larger at the side edges of the reservoir than at a medial portion of the reservoir.

15. An apparatus for drawing flat sheets of a glass-based material comprising:

a reservoir comprising porous walls (12), the walls defining a gap (14) therebetween for accommodating a flow of the glass-based material, the gap varying over at least a portion of a vertical length of the reservoir; and

wherein the apparatus includes opposing rollers (50) rotatably mounted adjacent side edges (22, 22′

) of the reservoir for drawing the sheet of glass-based material.

16. The apparatus according to claim 15 wherein the rollers are cooled.

17. The apparatus according to claim 15 wherein the walls comprise passages (38) which vary in size along a vertical length (L) of the reservoir for delivering a gas to pores of the porous walls.

18. The apparatus according to claim 15 wherein the gap varies across a width of the reservoir.

19. The apparatus according to claim 15 wherein an axis of rotation (56) of the rollers is no more than about 10 mm below an outlet of the reservoir.

20. The apparatus according to claim 15 wherein the walls comprise rotating porous cylinders (62).