METHOD OF PRODUCING GLASS MOLDED PRODUCT, APPARATUS OF PRODUCING THE SAME, AND METHOD OF PRODUCING GLASS PRODUCT

摘要

PROBLEM TO BE SOLVED: To form a semiprocessed glass product effectively suppressing generation of shrink at the glass surface after pressed and hence having a reduced margin for scraping in the direct press-forming method. SOLUTION: The upper surface of a glass gob on the forming surface of a lower die is cooled and the temperature inside the glass gob is brought close to that of the periphery of the glass gob by suppression of heat radiation from the glass gob. Thereafter, the fused glass fed to the forming surface of the lower die is pressed. The pressing of the glass gob is carried out with viscosity of 3.5-10.65 poise. Since the upper surface of the glass is quenched before the pressing of the glass, heat of the glass is rapidly removed and the temperature difference between the inside and outside of the glass is made closer and thus the glass can be pressed with a relatively high and uniform viscosity. Hence, heat contracting amount of the glass can be reduced and the difference of heat contracting amount between the inside and outside of the glass can also be reduced. Accordingly, generation of shrink on the surface of the glass is decreased.