METHOD OF MANUFACTURING GLASS SUBSTRATE AND DIE FOR MOLDING GLASS SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To inexpensively manufacture a large quantity of glass substrates for magnetic disks optimum for recording medium such as magnetic disks having ultrasmoothness on the substrate surfaces and excellent axisymmetricalness, and to provide a die for molding the glass substrates. SOLUTION: The manufacturing method comprises arranging a glass blank 7 between the upper and lower dies 1 and 4 provided with forming surfaces 2 and 5 formed to a recessed or projecting shape and press forming the glass substrate 18 by a heating and pressurizing process step and a cooling process step, where a temperature difference is provided in such a manner that the temperature of the upper die 1 is higher than the temperature of the lower die 4 in the cooling process step. The glass substrate 18 warped to the lower die 4 side of the projecting shape is warped to the upper die 1 side of the recessed shape by the temperature difference between the upper and lower sides 1 and 4, by which the glass substrate 18 having the ultrasmoothness on the substrate surfaces is obtained.