GLASS SUBSTRATE FORMING MOLD, GLASS SUBSTRATE FORMING GLASS MATERIAL, PRODUCTION METHOD FOR GLASS SUBSTRATE AND GLASS SUBSTRATE FOR MAGNETIC DISK

摘要

A parallel, flat glass substrate is produced by placing a glass material (4) into a forming mold consisting of a pair of upper and lower molds (1, 2) and a regulating member (3) for regulating a space between the upper and lower molds, heating the glass material to be softened, and pressing it, the heat shrinkage at this time of the regulating member being smaller than that of the glass material so that, after forming, the glass substrate is separated from the mold at cooling. The glass substrate is excellent in surface smoothness and shape precision, low in cost, suitable for mass-production, and optimal for a recording medium such as a magnetic disk.