Bent glass-ceramic plate and a method of making glass-ceramic bent plate

DETAILED DESCRIPTION The present invention is therefore aimed at providing a procedure that makes it possible to produce quality glass-ceramic plates bent at a slight radius of curvature which are especially useful in the manufacture of cooking plates.
More particularly the invention involves a procedure for producing a glass-ceramic plate having at least one bend by: a) providing a precursor of a glass-ceramic flat plate, b) preheating the plate to a temperature at least 10.
degree.
C.
and preferably 20.
degree.
C.
lower than the nucleation temperature of the glass-ceramic precursor, c) quickly heating an area of the plate to be bent until the viscosity of the glass-ceramic precursor in this area reaches a value appropriate for bending, forming at least one bend with a radius of curvature no greater than 5 cm, the duration of the heating being short enough so as not to cause a significant nucleation of the glass-ceramic precursor, and d) ceramming the bent glass-ceramic precursor plate.
Optionally, the plate may be annealed after bending, and cooled down prior to the ceramming step.
The invention also concerns glass-ceramic plates having at least one bend the radius of curvature of which is less than 5 cm.
The invention finally concerns cooking plates comprising a glass-ceramic plate, characterized by the fact that the aforesaid glass-ceramic plate contains at least one bend, the radius of curvature of which is less than 5 cm.
Preferably, the aforesaid bend has a radius of curvature preferably less than 2 cm, and most preferably in the range of 4 to 12 mm.