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CN-122029587-A - Method and apparatus for forming partially thinned glass and foldable sheet glass article made therewith

CN122029587ACN 122029587 ACN122029587 ACN 122029587ACN-122029587-A

Abstract

A method for producing a foldable glass article (1) is provided, the glass article (1) having a strip section (3) of reduced average thickness compared to adjacent sections (5, 7) such that the rigidity of the strip section (3) is reduced by the reduction of average thickness, whereby the glass article (1) can be folded around the strip section (3) without breaking, the method comprising forming glass (10) of a glass sheet (2) by dispensing softened glass such that the glass thickness is reduced along the strip section (3) in a thermoforming step.

Inventors

  • XIAO WEI
  • JI JIAHUI
  • HE FENG
  • H. Wegener

Assignees

  • 肖特股份有限公司
  • 肖特玻璃科技(苏州)有限公司

Dates

Publication Date
20260512
Application Date
20231018

Claims (20)

  1. 1. A method for producing a foldable glass article (1), the glass article (1) having a strip section (3) of reduced average thickness compared to adjacent sections (5, 7) such that the rigidity of the strip section (3) is reduced by the reduction of average thickness such that the glass sheet (1) can be folded around the strip section (3) without breaking, the method comprising forming glass (10) of a glass sheet (2) by dispensing softened glass such that the glass thickness is reduced along the strip section (3) in a thermoforming step.
  2. 2. The method according to claim 1, wherein glass (10) is dispensed without removing the glass from the glass sheet (2).
  3. 3. The method of claim 1, comprising forming a glass sheet in the form of a glass ribbon (20) from a glass melt (21) by drawing, wherein the glass (10) is dispensed before the glass (10) of the glass ribbon (20) cools and solidifies.
  4. 4. The method according to claim 1, wherein the dispensing of the glass (10) is achieved by means of a bulge (14) which locally slows down the flow of the glass melt (21), in particular extends into the flow of the glass melt (21).
  5. 5. The method according to claim 4, wherein the glass sheet (2) is formed in the form of a glass ribbon (20) by drawing the glass (10) downwards from a slit-shaped aperture (12), the aperture (12) having a bulge (14) narrowing the width.
  6. 6. A method according to claim 4, wherein the glass sheet (2) in the form of a glass ribbon (20) is formed by overflow-melting from a trough (18) having a boss (14) on at least one side thereof.
  7. 7. The method according to claim 1, wherein a glass ribbon (20) is produced, the glass ribbon (20) having a plurality of strip-shaped sections (3) of reduced average thickness, the plurality of strip-shaped sections being laterally spaced apart in a direction perpendicular to the longitudinal direction of the glass ribbon (20), wherein the glass ribbon (20) is cut along at least one cutting line extending along two strip-shaped sections (3) and between two strip-shaped sections (3), and the glass ribbon (20) is further cut perpendicular to the longitudinal direction of the glass ribbon (20) to obtain a plurality of glass articles (1), each glass article having at least one strip-shaped section (3) of reduced average thickness.
  8. 8. Method according to claim 1, wherein the glass sheet (2) is formed by drawing in the form of a glass ribbon (20), wherein the glass (10) is locally heated along a strip-shaped region (16) to a higher temperature than adjacent regions of the glass ribbon (20) while still in a softened state, such that its viscosity along this region (16) is lower than in the adjacent regions, wherein the strip-shaped region (16) extends parallel to the drawing direction, and wherein a drawing force having a component perpendicular to the drawing direction is applied such that the glass thickness decreases along the strip-shaped region (16) as a result of the drawing.
  9. 9. Method according to claim 1, wherein a glass sheet (2) is provided, the glass sheet (2) preferably having a uniform thickness and being locally heated along a strip-shaped region (16) such that glass (10) in the strip-shaped region (16) is softened, and wherein the glass sheet (2) is drawn in a direction transverse to the strip-shaped region (16) such that the strip-shaped region (16) is expanded and the glass thickness within the strip-shaped region (16) is reduced.
  10. 10. Method according to claim 1, wherein a glass sheet (2) having a strip-shaped section (3) of reduced average thickness is provided and heated such that the glass (10) of the glass sheet (2) is softened, and wherein the glass sheet (2) is drawn in a direction along the longitudinal direction of the strip-shaped section (3) to reduce the thickness of the glass sheet (2).
  11. 11. Method according to claim 1, wherein the glass sheet (2) is formed by drawing in the form of a glass ribbon (20), and wherein a plurality of strip-shaped sections (3) of reduced average thickness compared to adjacent sections (5, 7) are formed in the drawing process, wherein the longitudinal direction of the strip-shaped sections (3) extends transversely, preferably perpendicularly, to the drawing direction.
  12. 12. The method according to the preceding claim, wherein forming a plurality of strip-shaped sections (3) of reduced average thickness comprises at least one of the following steps: -changing the drawing speed; -changing the temperature such that the temperature of the strip-shaped region extending transversely to the drawing direction is increased compared to the adjacent region.
  13. 13. The method according to claim 1, wherein dispensing the softened glass such that the glass thickness decreases along the strip section (3) comprises at least one of the following features: -combining and melting glass melt streams (23, 24) or softened glass strips (27, 29) having different widths to make a glass ribbon (20) in which the glass strips (27, 29) or glass melt streams (23, 24) are arranged to produce at least one strip-shaped section (3) of reduced average thickness; -blowing a gas jet (49) onto the softened glass (10) or glass melt (21).
  14. 14. A method according to claim 1, wherein the average thickness of the strip-shaped sections (3) is further reduced by etching the glass sheet (2).
  15. 15. A method according to claim 1, wherein the ratio of the thickness D of the glass sheet (2) to the minimum thickness Dmin at the strip section (3) is increased by uniformly removing glass from at least one side (101, 102) of the glass sheet (2).
  16. 16. The method according to claim 1, wherein a glass ribbon (20) is drawn, the glass ribbon (20) having at least two laterally spaced apart strip-shaped sections (3) of reduced average thickness, wherein a glass article (1) is cut from the glass ribbon (20) such that the glass article (1) has at least two strip-shaped sections (3), wherein at least three sections (5, 7, 9) are foldably connected together by the strip-shaped sections (3).
  17. 17. An apparatus (30) for performing the method according to any one of the preceding claims for producing glass articles (1), the apparatus (30) having means for dispensing glass in a softened or molten state to make glass sheets having strip-shaped sections (3), the strip-shaped sections (3) having a reduced average thickness compared to adjacent sections (5, 7) so as to reduce the rigidity of the strip-shaped sections (3) and enable the glass sheets (1) to be folded around the strip-shaped sections (3) without breaking.
  18. 18. The apparatus (30) according to the preceding claim, wherein said means for dispensing glass in a softened or molten state comprise at least one of the following: -a boss (14), the boss (14) being located in the aperture (12) for drawing a glass ribbon (20); -a local heating device (25).
  19. 19. A foldable sheet-like glass article (1), which glass article (1) is particularly producible using the method or the apparatus (30) according to any of the preceding claims, which glass article (1) has two opposite sides (101, 102) and a circumferential edge (104) and a strip-shaped section (3) of reduced average thickness compared to adjacent sections (5, 7), such that the rigidity of the strip-shaped section (3) is reduced by the reduction of average thickness, whereby the glass sheet (1) can be folded around the strip-shaped section (3) without breaking, which strip-shaped section (3) extends laterally along the sides (101, 102) and is terminated at its two ends (33, 34) by the circumferential edge (104), wherein the surface profile of at least one of the sides (101, 102) and/or the thickness profile within the strip-shaped section (3) is continuously curved, wherein the surface of the centre of the strip-shaped section (3) is concavely curved and wherein the concavely curved surface is arranged from the concavely curved surface towards the convexly curved surface (36, 37) in the direction between the convexly curved surfaces (37, 37).
  20. 20. The plate-shaped glass article (1) according to the preceding claim, comprising at least one of the following features: -the combined width of the convex curved surface portions (36, 38) of the strip-shaped section (3) is at least as large as the width of the concave curved surface portions (37); -the width of the recess (105) is at least three times, preferably at least five times, greater than the depth of the recess (105); -the glass article (1) comprises a thickened transition section (50, 70) between the strip-shaped section (3) and the adjacent section (5, 7) of constant thickness.

Description

Method and apparatus for forming partially thinned glass and foldable sheet glass article made therewith Technical Field The present invention relates generally to the manufacture of glass sheets. In particular, the present invention relates to the production of glass sheets having one or more sections of reduced thickness to facilitate glass bending. Background Foldable electronic displays employ a front cover or carrier that is flexible enough to achieve tight bends. However, providing an electronic display with a cover or carrier that is both foldable and durable has proven challenging. Currently, structured metal plates are often used as backplates to flexibly support a display. The tuning folding force is provided by local structuring. Typically, such back sheets employ stainless steel or titanium having a thickness of about 0.15 mm. However, a disadvantage of metal carriers is that they are prone to fatigue due to the ductility of the material. An alternative material for flexible displays is glass, which can also provide considerable strength, especially if the glass is chemically strengthened. On the other hand, glass is a brittle material and is generally not suitable for bending. For current foldable devices, ultra Thin Glass (UTG) has become a standard solution for display cover glass. Its flexibility and foldability are key to folding applications. However, UTG has a disadvantage in that it has a very small thickness and thus is less resistant to sharp impacts or scratches. To achieve higher impact resistance, the glass must be thicker, which can negatively impact its bendability. However, a bendable glass sheet may be obtained by structuring the strip-shaped areas to reduce its rigidity. Accordingly, cover glass having a hinge structure or a thinned folded region has been increasingly attracting manufacturers' interest. These cover glasses have thicker glass in the main display area and have a structured or thinned fold area to achieve the desired flexibility. Accordingly, various methods have been attempted. One possible method is to introduce an arrangement of holes. However, this method requires a multi-step process, such as profiling the hole using a laser and then etching. The next generation foldable display devices even surpass single-fold designs and integrate multi-fold functionality for larger screens. Popular solutions include, for example, so-called S-type, G-type and book-type folding displays. The S-shaped and G-shaped fold variants are characterized in that they have two fold regions with different bending radii. Of these two variants, the S-type variant is particularly advantageous, since in contrast to previous foldable devices, this display design, when the device is in the folded state, is provided with a foldable cover glass as well on the unprotected outer side of the device. In this case, at least one folding zone will also be exposed to the outside of the device in a particularly vulnerable state, since the glass is under tensile stress in its folded state. In addition, for these foldable displays, partially structured glass may not be the best solution for cover glass due to its finely structured hinge regions and the potential optical defects associated with these regions. Therefore, locally thinning the glass may be a viable solution. So far, locally thinned glass has been manufactured mainly by etching preformed glass of uniform thickness. The fold region is thinned by various etching techniques. These methods may include or be combined with locally applying an etching solution to the fold areas (e.g., by applying an etching paste or solution, masking the fold areas, etc.), immersing only the fold areas in the etching solution, locally machining (laser or machining) and then etching the fold areas, or applying the etching solution with localized heating to increase the etching rate only in the target areas, among other methods. All these methods have in common that they are secondary processes which require selective post-treatment of bare glass substrates of uniform thickness, which are not only technically difficult but also time-consuming and costly. US 2021/0107829 A1 discloses a method in which laser ablation is used to thin glass. The ablation process may be performed in the hot state of the glass ribbon. However, laser ablation requires high beam energy and typically results in narrow trench-like structures defined by the beam profile. To obtain a wider area of reduced stiffness, a plurality of parallel grooves are introduced. It is therefore an object of the present invention to facilitate the manufacture of foldable glass sheets, particularly glass sheets that can be used as carriers for flexible electronic displays. This object is achieved by the independent claims. Advantageous developments are defined in the respective dependent claims. Disclosure of Invention Accordingly, a method is provided for producing a foldable glass article having a strip-shaped se