Method for heat treatment of glass plate to strengthen its peripheral region.

摘要

The invention relates to heat treatment of a glass plate (100) for strengthening only a peripheral region (100a) of the glass plate while annealing the major region. The glass plate is heated to a temperature of 550-650<o>C and placed on a ring-like holder (56) which is maintained at a temperature lower than the temperature of the glass plate by 100 to 600<o>C such that the peripheral region (100a) of the glass plate makes contact with a ring-like upper surface of the holder (56). Then the glass plate on the ring-like holder is kept in an annealing chamber maintained at a temperature in the range from 50 to 500<o>C and not higher than the initial temperature of the ring-like holder. After that the glass plate is allowed to cool down to room temperature. This method is applicable to either flat glass plates or curved glass plates and very suitable for treating glass plates ranging from 1.5 to 3.0 mm in thickness.