METHOD AND APPARATUS FOR PRESSING HOLLOW BLANKS FROM GLASS

摘要

Method and apparatus for pressing hollow blanks from glass Hollow blanks from glass are pressed between a hollow mold and a plunger (10). The mold comprises an inner wall complementary to the outer side of a blank. The plunger (10) comprises an open-pore plunger head (11) having a surface (24) complementary to the inner side of the blank and an inner cavity (16) which is filled with a liquid. In each working cycle a partial amount of the liquid evaporates by heat transfer from the glass to the plunger head (11) at the surface (24) of the latter, a separating vapour layer forming between said surface and the glass. The liquid pressure in the cavity (15) of the plunger head (11) is adapted to the pressing pressure obtaining in the glass during the pressing in each case until the glass has reached its dimensional stability necessary for withdrawal of the plunger head (11).