SHAPED GLASS ARTICLE HAVING A PREDEFINED GEOMETRY PRODUCED WITHOUT USING A MOLD, METHOD AND USE OF THE SAME

• US 20160031737A1
• Filed: 07/31/2015
• Published: 02/04/2016
• Est. Priority Date: 07/31/2014
• Status: Active Grant

• Current Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Original Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Inventors: Hoppe, Bernd, Haselhorst, Georg, Seibert, Volker
• Granted Patent: US 10,023,489 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C03B 23/0086 Heating devices specially adapted for re-forming shaped glass articles in general, e.g. burners C03B23/02, C03B23/04, C03B23/18 take precedence
• CPC Class Codes: C03B 23/023 by bending
• CPC Class Codes: C03B 23/0235 involving applying local or additional heating, cooling or insulating means
• CPC Class Codes: C03B 23/0256 Gravity bending accelerated by applying mechanical forces, e.g. inertia, weights or local forces
• CPC Class Codes: H05K 5/03 Covers

Abstract

The disclosure relates to a method for producing, without a mold, a shaped glass article having a predefined geometry. For this purpose a method is provided for producing a shaped glass article without using a mold, which method comprises at least the steps of:

• • providing a starting glass;
  • supporting the starting glass;
  • heating a portion of the starting glass so that in this portion a predetermined spatial viscosity distribution of the starting glass is obtained from 10⁹ to 10⁴ dPa·s, in particular from 10⁴ to 10⁸ dPa·s, and so that at the points where the starting glass is supported a predetermined spatial viscosity distribution of the starting glass does not fall below 10¹³ dPa·s, wherein the heating is accomplished using at least one laser beam; and
  • deforming the heated starting glass by action of an external force until the predefined geometry of the glass article is obtained, and the portion is raised or lowered with respect to the surrounding regions so that a local elevation or depression is obtained.

Claims

1. A method for producing, without a mold, a shaped glass article having a predefined geometry, the method comprising at least the steps of:

providing a starting glass;

supporting the starting glass;

heating a portion of the starting glass so as to obtain, in the portion, a predetermined spatial viscosity distribution of the starting glass from 10⁹ to 10⁴ dPa·

s, and so that at the points where the starting glass is supported a viscosity of the starting glass does not fall below 10¹³ dPa·

s, wherein the heating is accomplished using at least one laser beam; and

deforming the heated portion through action of a predetermined external force until the predefined geometry of the glass article is obtained, wherein the portion is raised or lowered with respect to the surrounding regions so that a local elevation or depression is obtained.

2. The method of claim 1, wherein only the portion is deformed and adjacent regions of the starting glass remain in their original position.

3. The method of claim 1, wherein the predetermined viscosity distribution is adjusted by causing a power level of the laser beam to decrease from the edge towards the center of the portion.

4. The method of claim 1, wherein the heating of the portion is effected by locally and/or temporally varying the laser power.

5. The method of claim 4, comprising producing at least two deformations laterally spaced from one another, wherein the power of the laser beam is reduced or switched off while the laser beam sweeps over the space between the portions that are heated by the laser beam to produce the individual deformations.

6. The method of claim 1, comprising laterally distributing the laser beam on the surface of the starting glass with an optic system so that the predetermined viscosity distribution is achieved.

7. The method of claim 1, further comprising keeping constant during deforming a shaping force, and a pressure difference of a gas pressure between two opposite sides of the starting glass.

8. The method of claim 1, wherein the heating step further comprises heating a portion of the starting glass that has a surface that defines a region of a star-shaped, wherein the portion is deformed and adjacent regions keep their position relative to the surface of the starting glass.

9. The method of claim 1, wherein the starting glass is flat glass.

10. The method of claim 1, wherein the starting glass is selected from the group consisting of a soda-lime glass, a borosilicate glass, and an aluminosilicate glass.

11. The method of claim 1, further comprising the step of preheating the starting glass, wherein the preheating is effected at least in a region that includes the portion of the starting glass that is to be heated for producing the deformation, wherein the heating is performed up to a temperature of at least 300°

C. but remains below the softening point temperature at which the glass reaches a viscosity of 10^7.6 dPa·

s.

12. The method of claim 1, wherein the heating has heating parameters comprising the viscosity of the starting glass to be obtained in the portion, and deformation parameters comprising deformation time, are chosen so that deformation ceases when the starting glass has assumed the predefined geometry.

13. The method of claim 1, wherein the heating is performed using a burner or by infrared radiation.

14. The method of claim 13, wherein the portion is scanned with a frequency of the laser beam of at least 2 Hz.

15. The method of claim 1, wherein the portion is heated simultaneously or in a temporal sequence.

16. The method of claim 1, wherein the heating step is performed so that a predetermined thermal gradient is adjusted between the portion and other regions of the starting glass.

17. The method of claim 16, further comprising the step of measuring the thermal gradient with a thermal imaging sensor.

18. The method of claim 1, further comprising the step of measuring an amount of deformation during the deforming step with optical sensors and/or acoustic sensors.

19. The method of claim 1, wherein during the deforming step, a plurality of deformations are produced in one glass article, and

wherein between the points in time at which two closest neighboring deformations are produced, at least one deformation is produced that is not a closest neighbor of the two deformations;

or

wherein between the irradiation of two portions for producing closest neighboring deformations a time interval of at least 5 seconds is observed, during which interval the irradiation with the laser beam is interrupted.

20. The method of claim 1, wherein the external force is exerted by a pressure difference across the starting glass.

21. The method of claim 20, wherein the pressure difference is an overpressure and/or an underpressure on the portion.

22. A shaped glass article produced by the method of claim 1, wherein the article has a sheet-like basic shape and a deformed portion, wherein the deformed portion defines an elevation on one side and a depression on the opposite side,

wherein the surface of the deformation comprises a region of convex curvature which transitions into a region of concave curvature, wherein the height of the elevation or the depth of the depression is at least 0.1 mm and is not greater than the width of the deformation, and wherein the minimum wall thickness of the deformation corresponds to at least 0.5 times the thickness of the article.

23. The article of claim 22, wherein the minimum curvature radius of the curvature at the edge of the deformation is smaller than the minimum radius of curvature in the center of the deformation.

24. The article of claim 22, wherein the surface in the center of the elevation or depression is curved, and wherein the deformation has a continuously curved or dome-shaped surface.

25. The article of claim 22, wherein the article has laterally spaced elevations arranged in a manner so as to represent Braille characters.

26. The article of claim 22, further comprising a control field, the control field comprising at one line-shaped elevation or at least one depression, wherein the at least one-shaped elevations or at least one depressions have associated therewith at least one sensor for generating a control signal.

27. The glass article of claim 22, wherein the elevation is surrounded by a peripheral indentation or wherein the depression is surrounded by a peripheral elevation.

28. The glass article of claim 22, wherein either the depression or the elevation of the deformed portion has a spherical cap-shaped curvature, and wherein a deviation from an ideal spherical surface is less than 100 μ

m.

29. The glass article of claim 22, further comprising a tray-shaped depression, wherein the tray-shaped depression has a flat bottom and an edge region, wherein the depression has a depth of at least 0.1 millimeters and a maximum depth equal to four and a half times a thickness of the glass article, wherein the edge region is convexly curved, and wherein inwardly towards the flat bottom the convex curvature transitions into a concave curvature.