APPARATUS AND METHOD FOR DYNAMIC THERMAL TEMPERING OF GLASS

• US 20190308901A1
• Filed: 12/01/2017
• Published: 10/10/2019
• Est. Priority Date: 12/01/2016
• Status: Active Application

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Bressler, Douglas Dale, Sheehan, Brian Christopher, Thomas, John, Wasson, Kevin Lee
• Application Number:
  US16/464,957
• Publication Number:
  US 20190308901A1
• Time in Patent Office: Days
• CPC Class Codes: C03B 27/02 using liquid
• CPC Class Codes: C03B 27/04 using gas
• CPC Class Codes: C03B 27/0413 Stresses, e.g. patterns, values or formulae for flat or bent glass sheets
• CPC Class Codes: C03B 27/048 on a gas cushion
• CPC Class Codes: C03B 29/12 being in a horizontal position on a fluid support, e.g. a gas or molten metal
• CPC Class Codes: C03B 35/22 on a fluid support bed, e.g. on molten metal
• CPC Class Codes: C03B 35/24 on a gas support bed

Abstract

A process for thermally strengthening a glass article comprising first conveying a glass article, having a temperature above a transition point of the glass of the article, into position between two fluid bearing surfaces then moving the fluid bearing surfaces toward the glass article and cooling the glass article, with at least 20% of said cooling taking place by conduction from the glass article to the fluid bearing surfaces. Apparatuses for performing the process and products resulting are also disclosed.

Claims

1. A process for thermally strengthening a glass article, the process comprising

first conveying a glass article, the article having a temperature above a transition point of the glass of the article, into position between a first two fluid bearing surfaces;

second moving one or both of the first two fluid bearing surfaces toward the glass article and cooling the glass article, with at least 20% of said cooling taking place by conduction, from the glass article to the fluid bearing surfaces, during at least some point in time during the cooling.

2. The process according to claim 1 wherein at least 30% of said cooling takes place by conduction from the glass article to the fluid bearing surfaces.

3. The process according to claim 1 wherein at least 40% of said cooling takes place by conduction from the glass article to the fluid bearing surfaces.

4. The process according to claim 1 wherein at least 50% of said cooling takes place by conduction from the glass article to the fluid bearing surfaces.

5. The process according to claim 1 wherein the conduction takes place from the glass article through a fluid of the fluid bearing to the fluid bearing surfaces.

6. The process according to claim 1 wherein the conduction takes place at least in part from the glass article through directly to the fluid bearing surfaces without conduction through a fluid of the fluid bearing.

7. The process according to claim 1 further comprising the step of heating the glass article before conveying the glass article, wherein the step of heating is performed with the article positioned between a second two fluid bearing surfaces.

8. The process according to claim 7 wherein the step of heating the glass article further comprises moving one or both of the second two fluid bearing surfaces toward the glass article.

9. The process according to claim 1 wherein the step of conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that the glass article changes in temperature, during transition to a position fully within the cooling zone, by less than 50°

C.

10. The process according to claim 1 wherein the step of conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that the glass article changes in temperature, during transition to a position fully within the cooling zone, by less than 20°

C.

11. The process according to claim 1 wherein the step of conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that the glass article changes in temperature, during transition to a position fully within the cooling zone, by less than 10°

C.

12. The process according to claim 1 wherein the step of conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that the glass article changes in temperature, during transition to a position fully within the cooling zone, by less than 5°

C.

13. The process according to claim 1 wherein the step conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that of a maximum temperature variation along the surface of the glass sheet in the direction of travel is less than 30°

C.

14. The process according to claim 1 wherein the step conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that of a maximum temperature variation along the surface of the glass sheet in the direction of travel is less than 10°

C.

15. The process according to claim 1 wherein the step conveying comprises transitioning the article to a point fully within the cooling zone sufficiently quickly such that of a maximum temperature variation along the surface of the glass sheet in the direction of travel is less than 5°

C.

16. The process according to claim 1 wherein the first two bearing surfaces have a surface shape other than planar.

17. The process according to claim 1 wherein the first two bearing surfaces have a curved surface shape other than a section of a cylindrical surface and other than a section of a toroidal surface.

18. The process according to claim 1 wherein the step of moving one or both of the first two fluid bearing surfaces toward the glass article comprises moving one or both of the first two fluid bearing surfaces toward the glass article until one or both of the first two fluid bearing surfaces contact the glass article.

19. The process according to claim 1 wherein the step of moving one or both of the first two fluid bearing surfaces toward the glass article is performed such that the first two fluid bearing surfaces do not contact the glass article during said step.

20. The process according to claim 1 wherein the first two fluid bearing surfaces comprise surfaces of gas bearings.

21. The process according to claim 1 wherein the first two fluid bearing surfaces comprise surfaces of liquid bearings.

22. The process according to claim 1 wherein the glass article is a sheet.

23. A process for thermally strengthening a glass article, the process comprising

first, heating a glass article positioned in a hot zone between two hot zone fluid bearing surfaces while moving one or both of the two hot zone fluid bearing surfaces toward the glass article without contacting the glass article, said heating to a temperature above a transition point of a glass of the article with at least 20% of said heating taking place by conduction during at least some point in time during said heating;

second, conveying the glass article into position in a cold zone between a two cold zone fluid bearing surfaces.

24. The process according to claim 23, further comprising the step of:

third, moving one or both of the two cold zone fluid bearing surfaces toward the glass article and cooling the glass article, with at least 20% of said cooling taking place by conduction, from the glass article to the fluid bearing surfaces, during at least some point in time during the cooling.

25. The process of claim 23, wherein the step of first, heating a glass article further comprises moving one or both of the two hot zone fluid bearing surfaces toward the glass article until a gap between the two hot zone fluid bearing surfaces matches a gap between the two cold zone bearing surfaces matching or being small than a gap between the two cold zone fluid bearing surfaces.

26. An apparatus for thermal tempering of glass, the apparatus comprising:

a cold zone comprising two cold zone fluid bearing surfaces, one or both of the cold zone fluid bearing surfaces being moveable, under automated control, toward and away from the other of the two cold zone fluid bearing surfaces so as automatically vary a gap between the two cold zone fluid bearing surfaces; and

a conveyor moveable under automated control between the hot zone and the cold zone so as to be capable to move a glass article under treatment from the hot zone to the cold zone;

wherein the moveable cold zone fluid bearing surface(s) and the moveable conveyor are moveable independently and wherein the automated control of the moveable cold zone fluid bearing surface(s) is programmed and/or designed so as to move the moveable cold zone fluid bearing surface(s) during processing of a glass article.

27. The apparatus of claim 26 further comprising:

a hot zone comprising two hot zone fluid bearing surfaces, one or both of the hot zone fluid bearing surfaces being moveable, under automated control, toward and away from other of the two hot zone fluid bearing surfaces so as automatically vary a gap between the two hot zone fluid bearing surfaces, and

wherein the moveable hot zone fluid bearing surface(s) and the moveable conveyor are moveable independently and wherein the automated control of the moveable hot zone fluid bearing surface(s) is programmed and/or designed so as to move the moveable hot zone fluid bearing surface(s) during processing of a glass article.

28. The apparatus of claim 26 wherein one or both of the cold zone fluid bearing surfaces is supported on or by a controlled force actuator.

29. The apparatus of claim 28 wherein the controlled force actuator comprises one spring or multiple springs.

30. A strengthened glass article comprising:

a first major surface;

a second major surface opposite the first major surface and separated from the first major surface by a thickness t;

an interior region located between the first and second major surfaces; and

an outer edge surface extending between and surrounding the first and second major surfaces such that the outer edge surface defines a perimeter of the article;

wherein the article is thermally tempered such that at the first major surface is under compressive stress;

the strengthened glass article comprising a glass material having a low temperature linear CTE, expressed in 1/°

C., of α

^S_CTE, a high temperature linear CTE, expressed in 1/°

C., of α

^L_CTE, an elastic modulus, expressed in GPa, of E, a strain temperature, expressed in units of °

C., of T_strain, and a softening temperature, expressed in units of °

C., of T_soft;

the compressive stress of the first major surface is less than 600 MPa and greater than