BENDING OF GLASS SHEETS COMPRISING LOCALIZED COOLING
A process for manufacturing a bent individual glass sheet including a peripheral compression belt, the process including heating a glass sheet to its bending temperature in a furnace, performing an individual bending of the glass sheet, and performing a general cooling of the heated glass sheet, applying to one zone of the glass sheet at least partially inside the peripheral compression belt, which forms a locally cooled zone, after the heating of the glass sheet, a local cooling faster than the general cooling, when the glass sheet is at a temperature of at least 530° C.
1 . A process for manufacturing a bent individual glass sheet comprising a peripheral compression belt, the process comprising:
heating a glass sheet to its bending temperature in a furnace, performing an individual bending of the glass sheet, and performing a general cooling of the heated glass sheet,
applying to one zone of the glass sheet at least partially inside said peripheral compression belt, which forms a locally cooled zone, after the heating of the glass sheet, a local cooling faster than the general cooling, when the glass sheet is at a temperature of at least 530° C.
2 . The process as claimed in claim 1 , wherein the local cooling is applied before the bending.
3 . The process as claimed in claim 1 , wherein the local cooling is applied during the bending.
4 . The process as claimed in claim 1 , wherein the local cooling is applied after the bending.
5 . The process as claimed in claim 1 , wherein the glass sheet is heated individually in the furnace.
6 . The process as claimed in claim 1 , wherein the glass sheet undergoes the local cooling individually.
7 . The process as claimed in claim 1 , wherein the bending is carried out after the removal of the glass sheet from the furnace.
8 . The process as claimed in claim 1 , wherein the local cooling is applied when the glass sheet is in an environment which has a temperature within the range extending from 5° C. to 50° C.
9 . The process as claimed in claim 1 , wherein the local cooling is applied when the glass sheet is in a chamber, the environment of which is at a temperature within the range extending from 400° C. to 650° C. and is at a temperature is lower than that of the glass sheet.
10 . The process as claimed in claim 1 , wherein the local cooling is administered on the glass sheet when the latter is at a temperature within the range extending from 530° C. to 660° C.
11 . The process as claimed in claim 1 , wherein the local cooling is administered on the glass sheet by convection and/or conduction and/or radiation.
12 . The process as claimed in claim 11 , wherein the local cooling is carried out by air blowing.
13 . The process as claimed in claim 1 , wherein the glass sheet has a thickness within the range extending from 0.7 to 3 mm.
14 . The process as claimed in claim 1 , wherein the glass sheet undergoes a semi-tempering or tempering treatment after bending, giving it a surface stress within the range extending from 20 to 200 MPa.
15 . The process as claimed in claim 1 , wherein the locally cooled zone covers an area of between 0.5 cm 2 and 70 cm 2 .
16 . The process as claimed in claim 1 , wherein the locally cooled zone is at a distance from the edge of the glass of greater than one times the diameter of the locally cooled zone.
17 . The process as claimed in claim 1 , wherein the locally cooled zone is at a distance from the edge of the glass of greater than 2 cm.
18 . The process as claimed in claim 1 , wherein the locally cooled zone covers an area of less than 10% of the area of a main face of the glass sheet.
19 . The process as claimed in claim 1 , wherein the local cooling is sufficient in duration and intensity so that the edge compressive stresses after cutting in said locally cooled zone are greater than 4 MPa.
20 . A process for manufacturing a bent glazing comprising a glass sheet comprising a peripheral compression belt comprising the preparation of the glass sheet by the process of claim 1 , followed by cutting in the locally cooled zone.
21 . The process as claimed in claim 20 , further comprising cutting an orifice in the locally cooled zone at least partially inside the peripheral compression belt, said orifice having an edge compressive stress of at least 4 MPa.
22 . The process as claimed in claim 20 , wherein the glass sheet is conveyed individually during the heating thereof and up to the bending tool on a roller bed.