| 摘要 |
PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a larger spherical glass than the conventional one and the large spherical glass made from a molten glass having a low melt viscosity, and to provide a production method for a press molding using a spherical shape to a preform manufactured by this method. SOLUTION: A molten glass block is floated by blowout stream from a gas blowout nozzle, by using a molding section composed of an inverted-conical molding surface which is open upward for a spherical glass molding (an angular aperture of the inverted-cone is between 10 deg. and 50 deg.). The spherical glass molding having the gas blowout nozzle near the top of the inverted-cone (a diameter of the aperture of the gas blowout nozzle is between 30% and 95% of the diameter of the spherical glass obtained by molding). The production method of the spherical glass is to choose a flow rate of the stream of intermittently contact with the surface of the molding white the molten glass block is moved up and down repeatedly. A production method for a press molding is to heat and soften a manufactured spherical glass as a preform for a press molding, and to press mold by a press molding tool.
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