MICROWAVE HEATING GLASS BENDING PROCESS

• US 20150344346A1
• Filed: 08/06/2015
• Published: 12/03/2015
• Est. Priority Date: 05/30/2013
• Status: Active Grant

• Current Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Original Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Inventors: Jiao, Yu, Yu, Chao, Schrier, Russell W.
• Granted Patent: US 10,526,232 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C03B 2225/02 Means for positioning, aligning or orientating the sheets during their travel, e.g. stops
• CPC Class Codes: C03B 23/0235 involving applying local or additional heating, cooling or insulating means
• CPC Class Codes: C03B 23/0258 Gravity bending involving applying local or additional heating, cooling or insulating means
• CPC Class Codes: C03B 25/08 of glass sheets
• CPC Class Codes: C03B 29/08 Glass sheets
• CPC Class Codes: C03B 35/16 by roller conveyors
• CPC Class Codes: C03B 35/187 Rollers specially adapted for both flat and bent sheets or ribbons, i.e. rollers of adjustable curvature
• CPC Class Codes: C03B 35/202 by supporting frames C03B35/145 takes precedence
• CPC Class Codes: C03B 40/005 Fabrics, felts or loose covers

Abstract

Methods and systems are provided for automated shaping of a glass sheet. The methods comprise preheating the glass, bending the glass through selective, and focused beam heating through the use of an ultra-high frequency, high-power electromagnetic wave, and computer it processes utilizing thermal and shape (positional) data obtained in real-time, and cooling the glass sheet to produce a glass sheet suitable for use in air and space vehicles.

Claims

1. A method of shaping a glass sheet comprising:

a. preheating a glass sheet on a bending iron to a preheating temperature ranging from 600°

F. to 1000°

°

F.;

b. increasing the temperature of the sheet to a temperature ranging from greater than the preheating temperature to less than a temperature at which the glass sags;

c. bending the glass sheet by;

selectively heating a portion of the glass sheet with a device that produces ultra-high frequency, high-power electromagnetic waves controlled by a computer-implemented protocol to a temperature at which at least a portion of the glass sheet sags;

scanning at least a portion of the glass sheet with one or more thermal sensors at one or more time points during or after the selectively heating step and obtaining from data obtained from the one or more thermal sensors a temperature distribution in at least two dimensions for at least a portion of the glass sheet;

iii. comparing, using a computer-implemented process the obtained temperature distribution to a reference temperature distribution of the computer-implemented protocol; and

iv. selectively heating the glass sheet with the beam of the ultra-high frequency, high-power device controlled by a computer implemented process to match the obtained temperature distribution with the reference temperature distribution of the computer-implemented protocol.

2. The method of claim 1, wherein the device producing ultra-high frequency, high-power electromagnetic waves is a gyrotron.

3. The method of claim 1, further comprising repeating steps ii. through iv. of the bending step until the obtained temperature distribution matches the reference temperature distribution of the computer-implemented protocol.

4. The method of claim 1, in which bending step c. further comprises:

v. obtaining positional data of at least a portion of the glass sheet from one or more positional sensors at one or more time points during the selective heating step and producing a shape profile using a computer-implemented process for the glass sheet at the one or more time points;

vi. comparing, using a computer-implemented process a produced shape profile to a reference shape profile of the computer-implemented protocol;

vii. selectively heating the glass sheet with the beam of the ultra-high frequency, high-power device controlled by a computer-implemented process to match a shape profile of the glass sheet to the reference shape profile.

5. The method of claim 4, further comprising repeating steps v. through vii. of the bending step until the obtained shape profile matches the reference shape profile of the computer-implemented protocol.

6. The method of claim 4, wherein comparing steps iii. and vi. are performed substantially concurrently.

7. The method of claim 4, in which one or more of the positional sensors is a camera or charge-coupled device (CCD).

8. The method of claim 7, wherein the shape profile is a three-dimensional shape profile assembled from data obtained from a plurality of CCDs.

9. The system of claim 7, wherein the shape profile is a three-dimensional shape profile assembled from data obtained from a plurality of laser-light sensors.

10. The method of claim 4, wherein one or more of the one or more positional sensors are laser-light sensors.

11. The method of claim 1, wherein the glass sheet is cut-to-size prior to heating and shaping.

12. The method of claim 1, in which the thermal sensor is an IR scanner or IR imaging sensor.

13. A system comprising:

a first furnace comprising infrared heaters and temperature sensors;

a second furnace comprising infrared heaters, a device that produces ultra-high frequency, high-power electromagnetic waves, and an optical system for controlling shape, location and movement of a beam of the device to a glass sheet on a bending iron within the second furnace, and one or more infrared (IR) imaging sensors;

a conveyor system for carrying a glass sheet on a bending iron through the first and second furnaces;

a computer system connected to the one or more IR imaging sensors and the ultra-high frequency, high-power device, comprising a processor and instructions for controlling bending of a glass sheet in the second furnace by selective heating by the ultra-high frequency, high-power device, the instructions comprising a computer-implemented protocol for heating and bending a glass sheet in the second furnace, where the computer system obtains a temperature profile of the glass sheet at one or more time points during the bending of the glass data from the one or more IR imaging sensors, compares the obtained temperature profile to a reference temperature distribution of the computer-implemented protocol, and controls the ultra-high frequency, high-power device to selectively heat the glass sheet to match the reference temperature distribution; and

a third heating furnace to controllably cool the glass sheet, comprising IR heaters, a forced cool air convection system, and air fans.

14. The system of claim 13, wherein the device producing ultra-high frequency, high-power electromagnetic waves is a gyrotron.

15. The system of claim 13, further comprising one or more positional sensors in the second furnace arranged to obtain positional data for one or more portions of the glass sheet during bending, wherein the positional sensors are connected to the computer system and the computer system:

a. obtains data from the one or more positional sensors at one or more time points during the bending of the glass sheet;

b. produces a shape profile for the glass sheet from the obtained data from the one or more positional sensors at the one or more time points;

c. compares the obtained shape profile to a reference shape profile of the computer-implemented protocol; and

d. controls the ultra-high frequency, high-power device to selectively heat the glass sheet to match a shape profile of the glass sheet to the reference shape profile.

16. The system of claim 15, wherein one or more of the one or more positional sensors is a charge-coupled device (CCD).

17. The system of claim 16, comprising a plurality of CCDs, wherein the shape profile is a three-dimensional shape profile assembled from data obtained from the plurality of CCDs.

18. The system of claim 15, wherein one or more of the one or more positional sensors are laser-light sensors.

19. The system of claim 18, comprising a plurality of the laser-light sensors, wherein the shape profile is a three-dimensional shape profile assembled from data obtained from the plurality of CCDs.

20. The system of claim 13, wherein one or more of the one or more IR imaging sensors is a laser-light sensor or a CCD.

21. The system of claim 13, further comprising a third furnace having IR heaters, and wherein the conveyor system further carries the glass sheet through the third furnace.

22. The system of claim 21, wherein the first, second and third furnaces form a single tunnel.

23. The system of claim 22, comprising doors between the first and second furnaces and between the second and third furnaces.

24. The system of claim 13, in which the computer system obtains a temperature of the first furnace and adjusts the temperature of the first furnace using the IR heaters to match a preheating temperature according to the computer-implemented protocol.

25. The system of claim 13, in which the computer system obtains an ambient temperature of the second furnace and adjusts the temperature of the second furnace using the IR heaters to match a temperature ranging from greater than the preheating temperature to less than a temperature at which the glass sags.