| 摘要 |
PURPOSE:To form a glass lens having excellent transparency and wave front aberration, preventing contamination of mold surface with foreign material, by compression molding a glass gob with a mold composed of a pair of molds and a side mold while forcibly circulating the atmosphere in the mold. CONSTITUTION:The exterior gas atmosphere of a mold is introduced through an air vent 20 and a channel (a) into the mold and the gas in the mold is discharged through a channel (b) by sucking a nozzle 30 with a pump. The atmospheric gas in the mold is circulated by this process. The mold is heated from its circumference to slowly heat the glass raw material 40. When the temperature of the glass reaches the evaporation temperature of a low-melting metal existing in the glass, the metal begins to evaporate from the surface of the material and discharged from the mold. The glass raw material is further heated to a temperature near the softening point of the glass, when the glass is vertically pressed with the upper and lower molds to form a glass lens 40. The discharge of the atmospheric gas in the mold is continued during the molding operation. Consequently, the contamination of the mold with deposited foreign material can be completely prevented, the shape of the cavity face of the mold can be accurately transferred to the molded lens and a glass lens having excellent transparency and wave front aberration can be produced.
|
