Method and apparatus for press molding a glass product

摘要

A method comprises the step of supplying a molten glass onto a molding surface of a lower die, the step of controlling the temperature of the glass supplied onto the molding surface of the lower die so that an inner part of the glass and an outer peripheral part of the glass are close in temperature to each other, and the step of pressing the glass by the molding surfaces of the lower die and a molding surface of an upper die when the glass controlled in temperature has a viscosity within a range between 10<3.5> and 10<6.5> poises (dPa<.>s). By making the temperatures of the inner and the outer peripheral parts of the glass close to each other before pressing and by pressing the glass at such a relatively high viscosity, it is possible to reduce heat shrinkage of the glass after pressing and to reduce the difference in heat shrinkage between the inner and the outer peripheral parts of the glass. Thus, occurrence of sink marks on a glass surface is suppressed.