METHOD FOR STRENGTHENING GLASS SHEET, AND DEVICE THEREOF

摘要

To provide a method for tempering a glass sheet, which causes a greater temperature difference between the surfaces and the center portion of the glass sheet. The method for tempering a glass sheet of the present invention comprises a heating step of heating the glass sheet to a temperature close to the softening point of the glass sheet, a quenching step of blowing a cooling medium to both surfaces in the thickness direction of the heated glass to cool it, and a pre-quenching step between the heating step and the quenching step and further has an internal heating substep of selectively heating the vicinity of the center portion in the thickness direction of the glass sheet at least in the quenching step, to create such a state that when the temperature at the center portion in the thickness direction of the glass sheet is close to the tempering point, the temperature at the surfaces in the thickness direction of the glass sheet is not higher than the annealing point.