To provide a method of manufacturing a preform for press molding and a molding apparatus by which the preform having a shape suitable for press molding is manufactured directly from molten glass with high productivity, the preform for press molding which has a relatively large volume and front and back surfaces respectively having nearly equal curvature and is directly molded from the molten glass and a method of manufacturing an optical device by which the optical device is manufactured with high productivity.
The method of manufacturing the preform for press molding is carried out by supplying molten glass gob on a mold and piling up at least the center area of the molten glass gob and molding. The piling up operation is carried out by arranging a nozzle having a gas jetting port at the tip above the molten glass gob and jetting a gas radially toward the more outer side than the center area from the gas jetting port or by arranging a nozzle having a gas jetting port at the tip above the molten glass gob and jetting the gas from the gas jetting port to locally reduce the pressure of the atmosphere in the vicinity of the center area.
UTSUKI KATSUMI
YOSHIDA MASAHIRO
| JPH10310439A | 1998-11-24 | |||
| JP2001163627A | 2001-06-19 | |||
| JP2001278630A | 2001-10-10 | |||
| JP2003073135A | 2003-03-12 |