Manufacturing method for a glass substrate for magnetic disk
AssigneeHoya Corporation
InventorsShinji Eda, Hideki Isono, Akira Murakami
Life of this patent
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Abstract
The present invention provides a manufacturing method of a sheet glass material excellent in flatness. A manufacturing method of glass substrate for magnetic disk including a pair of principal surfaces, the method comprising the steps of: dropping process for dropping a lump of molten glass; pressing process for forming a sheet glass material by performing press forming to the lump while sandwiching the lump from both sides of the dropping path of the lump with facing surfaces of a pair of dies, the pair of dies being set to substantially the same temperature; and processing process for processing the sheet glass material, while the lump drops down while revolving around its dropping axis.
Claims14
A manufacturing method of a sheet glass material for a magnetic disk including a pair of principal surfaces, the method comprising:
- performing a cutting process to cut molten glass to cause a lump of molten glass to drop;
- and
- performing a pressing process to form a sheet glass material by performing press forming on the lump of molten glass such that the lump of molten glass extends along flat inner surfaces of a pair of dies disposed along both sides of the dropping path by sandwiching the dropping lump of molten glass between the inner surfaces of the pair of dies at the substantially the same timing, the pair of dies facing each other and being set to substantially the same temperature,
- the molten glass being cut during the cutting process such that the lump of molten glass is shorter in a parallel direction to the inner surfaces than the sheet glass material is after being formed, and
- the molten glass being cut during the cutting process such that the lump of molten glass drops down while revolving around its dropping axis, and the cutting process is such that a revolving speed of the lump of molten glass is controlled.
A manufacturing method of a glass substrate for a magnetic disk, the method comprising:
- performing a cutting process to cut molten glass to cause a lump of molten glass to drop;
- performing a pressing process to form a sheet glass material by performing press forming on the lump of molten glass such that the lump of molten glass extends along flat inner surfaces of a pair of dies disposed along both sides of the dropping path by sandwiching the dropping lump of molten glass between the inner surfaces of the pair of dies at the substantially the same timing, the pair of dies facing each other and being set to substantially the same temperature;
- grinding principal surfaces of the sheet glass material using a fixed abrasive grain;
- and
- polishing, after the grinding, the principal surfaces of the sheet glass material using a loose abrasive grain,
- the molten glass being cut during the cutting process such that the lump of molten glass is shorter in a parallel direction to the inner surfaces than the sheet glass material is after being formed, and
- the molten glass being cut during the cutting process such that the lump of molten glass drops down while revolving around its dropping axis, and the cutting process is such that a revolving speed of the lump of molten glass is controlled.
Dependencies are inferred from the claim text.