| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a high grade preform free from devitrification and striae even when glass not so high in stability or glass having volatile in a melted state is used. SOLUTION: In the method of manufacturing the glass preform used for precise press molding, molten glass lump is separated from molten glass flowing out from a flow out port and is press-molded to form a glass body having a shape similar to that of the preform and the glass body is formed into the preform at least through a grinding process. COPYRIGHT: (C)2008,JPO&INPIT
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