Manufacturing method of a glass blank for magnetic disk and manufacturing method of a glass substrate for magnetic disk
AssigneeHoya Corporation
InventorsHideki Isono, Akira Murakami, Shinji Eda
Life of this patent
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Abstract
A manufacturing method of a glass blank for magnetic disk including a pair of principal surfaces, the method including: dropping process for dropping a lump of molten glass; pressing process for forming a sheet glass material by sandwiching simultaneously the lump from both sides of the dropping path of the lump with surfaces of the pair of dies facing together, and performing press forming to the lump; and temperature adjusting process for adjusting temperature of the lump before the pressing process such that viscosity variation of the lump is reduced with respect to positions over the entirety of the lump in the pressing process.
Claims21
A manufacturing method of a glass blank for a magnetic disk including a pair of principal surfaces, the method comprising:
- a dropping process for dropping a lump of molten glass by cutting molten glass with cutting blades so that the lump of molten glass is separated from the molten glass and is out of contact with the molten glass as the lump falls along a dropping path;
- a pressing process for forming a sheet glass material by sandwiching the lump from both sides of the dropping path of the lump, at substantially the same time, with surfaces of the pair of dies facing together to catch the lump as the lump is falling along the dropping path, and performing press forming to the lump;
- and
- a temperature adjusting process for adjusting temperature of the lump during a period of time beginning at a time when the lump is dropped and ending at a time that the pair of dies press the lump in the pressing process such that the temperature adjusting process occurs while the lump is falling vertically along the dropping path and viscosity variation of the lump is reduced with respect to positions over the entirety of the lump in the pressing process.
A manufacturing method of a glass blank for a magnetic disk including a pair of principal surfaces, the method comprising:
- a dropping process for dropping a lump of molten glass by cutting molten glass with cutting blades so that the lump of molten glass is separated from the molten glass and is out of contact with the molten glass as the lump falls along a dropping path;
- a pressing process for forming a sheet glass material by sandwiching the lump from both sides of the dropping path of the lump, at substantially the same time, with surfaces of the pair of dies facing together to catch the lump as the lump is falling along the dropping path, and performing press forming to the lump;
- and
- a temperature adjusting process for providing a temperature higher than a transition temperature of the glass to heat the lump with the temperature higher than the transition temperature of the glass during a period of time beginning at a time when the lump is dropped and ending at a time that the pair of dies press the lump such that the temperature adjusting process occurs while the lump is falling vertically along the dropping path.
A manufacturing method of a glass blank for a magnetic disk, the method comprising:
- a cutting process for cutting molten glass with cutting blades to obtain a lump of molten glass so that the lump of molten glass is separated from the molten glass and is out of contact with the molten glass as the lump falls along a dropping path;
- a heating process for heating the lump of molten glass beginning at a time when the lump is dropped such that the heating process occurs while the lump is falling vertically along the dropping path;
- and
- a forming process for preparing a glass blank for magnetic disk of sheet glass material by press forming the lump of molten glass with a pair of dies that catch the lump as the lump is falling along the dropping path after the heating process which ends at a time that the pair of dies catch the lump as the forming process begins.
A manufacturing method of a glass substrate for a magnetic disk by use of a glass blank for magnetic disk manufactured by a method of a glass blank for magnetic disk, the method of a glass blank for magnetic disk comprising:
- a cutting process for cutting molten glass with cutting blades to obtain a lump of molten glass so that the lump of molten glass is separated from the molten glass and is out of contact with the molten glass as the lump falls along a dropping path;
- a heating process for heating the lump of molten glass beginning at a time when the lump is dropped such that the heating process occurs while the lump is falling vertically along the dropping path;
- and
- a forming process for preparing a glass blank for magnetic disk of sheet glass material by press forming the lump of molten glass with a pair of dies that catch the lump as the lump is falling along the dropping path after the heating process which ends at a time that the pair of dies catch the lump as the forming process begins.
Dependencies are inferred from the claim text.