Overflow downdraw glass forming method and apparatus

Patent metadata

Field	Value
Publication number	US-9802851-B2
Application number	US-201514978681-A
Country	US
Kind code	B2
Filing date	Dec 22, 2015
Priority date	Aug 8, 2001
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

The present invention discloses improved methods and apparatus for forming sheet glass. In one embodiment, the invention introduces a counteracting force to the stresses on the forming structure in a manner such that the thermal creep which inevitably occurs has a minimum impact on the glass flow characteristics of the forming structure.

First claim

What is claimed is:

1. An apparatus for forming sheet glass, comprising:
a trough including sides attached to a structure including downwardly sloping sides converging along a downward direction to a root of the structure, the structure including a wedge-shaped cross-section taken perpendicular to a length of the trough;
at least one inlet end compression block located at an inlet end of the structure;
at least one far end compression block located at an opposite end of the structure as the at least one inlet end compression block; and
at least one of the at least one inlet end compression block and the at least one far end compression block including a cross-sectional compression block shape taken perpendicular to the length of the trough, the cross-sectional compression block shape tapering in at least one of the downward direction and an upward direction opposite the downward direction.

2. The apparatus of claim 1 , wherein the cross-sectional compression block shape tapers in both the downward direction and the upward direction.

3. The apparatus of claim 1 , wherein the cross-sectional compression block shape includes a length in the downward direction from an upper end of the cross-sectional compression block shape to a lower end of the cross-sectional compression block shape, wherein an upper half of the length spans an upper portion of the cross-sectional compression block shape and a lower half of the length spans a lower portion of the cross-sectional compression block shape, and the lower portion includes a larger cross-sectional area than a cross-sectional area of the upper portion.

4. The apparatus of claim 1 , wherein the cross-sectional compression block shape of the far end compression block includes an upper end portion and a lower end portion positioned below the upper end portion in the downward direction, and the upper end portion includes two protrusions that are spaced apart and extend in the upward direction.

5. The apparatus of claim 1 , wherein the at least one inlet end compression block includes at least two compression blocks that are angled inward relative to one another in a direction of the length of the trough.

6. An apparatus for forming sheet glass, comprising:
a trough including sides attached to a structure including downwardly sloping sides converging along a downward direction to a root of the structure, the structure including wedge-shaped cross-section taken perpendicular to a length of the trough;
a bottom opening of a chamber containing the apparatus aligned with the root in the downward direction, the bottom opening including a width that varies in a longitudinal direction.

7. The apparatus of claim 6 , wherein the root includes a continuously parabolically curved shape in a convex upward direction.

8. The apparatus of claim 7 , wherein an inverted slope of the structure is at a constant angle with respect to the downward direction.

9. The apparatus of claim 7 , wherein an inverted slope of the structure has a lesser angle with respect to the downward direction at an inlet end and a far end than at a center of the structure.

10. The apparatus of claim 6 , wherein the width of the bottom opening is defined between a first edge and a second edge, wherein at least a portion of the first edge is angled relative to a corresponding portion of the second edge to vary the width in the longitudinal direction.

11. The apparatus of claim 10 , wherein the first edge and the second edge each shaped in a series of straight sections.

12. The apparatus of claim 6 , wherein the width of the bottom opening is defined between a first edge and a second edge, wherein the first edge and the second edge each include a parabolic shape.

13. An apparatus for forming sheet glass, comprising
a trough including sides attached to a structure including downwardly sloping sides converging along a downward direction to a root of the structure, the structure including a wedge-shaped cross-section taken perpendicular to a length of the trough;
at least one inflow measurement device to measure a mass flow of air into a muffle door chamber; and
at least one outflow measurement device to measure a mass flow of air out of the muffle door chamber; the outflow measurement device to regulate cooling air flowing out of the muffle door chamber equal to a measured value that flows into the muffle door chamber such that no air leaks through cracks and openings between the muffle door chamber and glass flowing off the root.

14. The apparatus of claim 13 , wherein the trough is positioned within an interior area of a muffle, the muffle including a muffle door including the muffle door chamber at least partially defined by a front wall of the muffle door, the front wall positioned between the muffle door chamber and a muffle door zone, and the muffle door zone aligned with the root in the downward direction to allow a glass sheet being drawn off the root to exit the interior area of the muffle.

15. The apparatus of claim 14 , wherein the muffle door includes a plurality of vent openings to provide air flow between the muffle door chamber and the interior area of the muffle.

16. The apparatus of claim 14 , further including a plurality of cooling tubes that are each positioned to direct cooling air into the muffle door chamber and against the front wall of the muffle door.

17. The apparatus of claim 14 , wherein the muffle door further includes an exit port to remove air from the muffle door chamber without entering the interior area of the muffle.

18. An apparatus for forming sheet glass, comprising:
a trough including sides attached to a structure including downwardly sloping sides converging along a downward direction to a root of the structure, the structure including a wedge-shaped cross-section taken perpendicular to a length of the trough;
at least one inlet end compression block located at an inlet end of the structure, the at least one inlet end compression block including at least two compression blocks that are angled inward relative to one another in a direction of the length of the trough; and
at least one far end compression block located at an opposite end of the structure as the at least one inlet end compression block.

19. The apparatus of claim 18 , wherein at least one of the at least one inlet end compression block and the at least one far end compression block including a cross-sectional compression block shape taken perpendicular to the length of the trough, the cross-sectional compression block shape tapering in the downward direction and an upward direction opposite the downward direction.

20. The apparatus of claim 18 , wherein at least one of the at least one inlet end compression block and the at least one far end compression block including a cross-sectional compression block shape taken perpendicular to the length of the trough, and the cross-sectional compression block shape includes a length in the downward direction from an upper end of the cross-sectional compression block shape to a lower end of the cross-sectional compression block shape, wherein an upper half of the length spans an upper portion of the cross-sectional compression block shape and a lower half of the length spans a lower portion of the cross-sectional compression block shape, and the lower portion includes a larger cross-sectional area than a cross-sectional area of the upper portion.

21. The apparatus of claim 18 , wherein at least one of the at least one inlet end compression block and the at least one f

Assignees

• Corning Inc

Inventors

• Pitbladdo Richard Bruce

Classifications

• C03B17/067

  combined with thermal conditioning of the sheets · CPC title

• C03B17/064 Primary

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

• Y02P40/57

  Improving the yield, e-g- reduction of reject rates · CPC title