| 摘要 |
PROBLEM TO BE SOLVED: To press-form a glass substrate for recording information to have the precise thickness and outside diameter. SOLUTION: In the method of manufacturing the glass substrate for recording information, a glass is press-formed between a lower die to which a gob is supplied and an upper die having an annular projected line and projectingly provided integrally on the outer peripheral part of the forming surface. In such a case, the annular projecting line is brought into contact with the lower die in the press-forming and no contact with the glass. The glass substrate having the same thickness as that of the annular projected line and the prescribed outside diameter is precisely formed because the annular projected line is formed integrally with the upper die. When the press-forming is carried out using a plurality of the lower dies with one piece of the upper die, the variation of the thickness and the diameter of the glass substrate is remarkably reduced even when any lower die is used in the press-forming because the annular projected line is provided on the upper die instead of the lower mold. COPYRIGHT: (C)2005,JPO&NCIPI
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