Method of manufacturing a glass optical part

A method of manufacturing an optical part, comprising the steps of:

• causing molten glass having a viscosity of 10.sup.2 to 10.sup.6 poise to flow down continuously;
• positioning a pair of shaping mold members for pressing the flowing-down glass so as to form at least one optical surface;
• heating the shaping mold members to a predetermined temperature and holding the shaping members at said temperature;
• pressing the flowing-down glass by moving the shaping mold members so as to approach each other;
• cutting the continuously flowing-down glass above a portion where the pressing step is being performed by the shaping mold members;
• allowing the shaping mold members to cool down;
• completing the pressing step when the glass being pressed between the shaping mold members reaches a temperature that is below the glass strain point;
• moving the shaping mold members back from each other;
• taking out a molded article having an ear that protrudes outwardly with relation to glass pressed between the shaping mold members;
• and
• removing the ear by applying an external force to the molded article, thereby producing the optical part,
• wherein a groove forming ring is provided around a shaping surface of at least one of the shaping mold members, whereby the groove forming ring, upon pressing, forms a groove at a boundary between a portion of the optical part and the ear protruding outwardly therefrom.

A method of manufacturing a glass optical part, comprising the steps of:

• pressing flowing-down molten glass from opposite sides thereof with a pair of shaping mold members, thereby manufacturing an optical part having surfaces corresponding to the shaping surfaces of said shaping mold members, wherein one shaping mold member of said pair is constructed of a plurality of constituent members;
• continuing to press the glass without the space between said pair of shaping mold members being reduced to its narrowest open position until the glass reaches a temperature below a strain point thereof;
• moving the plurality of constituent members of one of said pair of shaping mold members at different strokes;
• and
• cutting the flowing-down molten glass above that portion thereof, which is being pressed, to obtain a glass molded article having an ear protruding outwardly relative to an optical part body portion formed between said shaping mold members,
• wherein a groove forming ring is provided around the shaping surface of the other shaping mold member of said pair of shaping mold members, and a groove is formed in the molten glass by said groove forming ring during said pressing of the molten glass, wherein said ear is formed outside of said groove.