PURPOSE: To obtain a moldings of a high grade in good yields by immersing a molding which is heted to temp. near the temp. of molten glass or higher than said temp. in the molten glass in a crucible, then subjecting the molding in a hot hydrostatic pressing treatment in a high temp. high pressure gaseous atmosphere.
CONSTITUTION: A molding 7 which is heated to temp. near the temp. of the molten glass 8 in a crucible 6 or higher than said temp. is immersed n said glass while the molding is held contained in a basket-like supporting member 1. While the crucible 6 is kept at high temp., the crucible is charged nto a preheated hot hydrostatic press device (HIP furnace), by which the molding 7 is hot hydrostatically pressed under high pressure of at least about 500 atm with an inert gas such as gaseous N2 as a primary pressure medium. Thereafter the member 1 is pulled up together with the molding 7 and the glass 8 is dropped into the crucible 6 and is separated from the molding 7. It is preferable to coat previously a release agent consisting of boron nitride powder or the like beforehand on the surface of the molding 7. As a result, the max. operating efficiency of the HIP device is attained with a min. rate of heat energy consumption.
FUJIKAWA TAKAO
MIYANAGA JIYUNICHI
