Patent ID: 9003834
Filing Date: 2015-04-14
Classification: B24B,C03B,C03C,G11B,Y10T

Abstract:
1. A manufacturing method of glass substrate for a magnetic disk, the method comprising: operating a cutting unit to cut molten glass flowing out from a molten glass outflow port to form a lump of the molten glass that is separated from the molten glass flowing out from the molten glass outflow port; after the operating of the cutting unit, operating a first die and a second die to move horizontally toward each other to form a sheet glass material by performing press forming from both sides of a falling path of the lump as the lump is falling to catch and spread the lump along an inner circumferential surface of the first die and an inner circumferential surface of the second die, and maintaining the first die and the second die proximate to each other to retain the lump spread along the inner circumferential surface of the first die and the inner circumferential surface of the second die until the lump is cooled to become the sheet glass material, such that the sheet glass material has a surface shape to be ground using a fixed abrasive grain; grinding the principal surface of the sheet glass material using the fixed abrasive grain; and polishing the sheet glass material using a loose abrasive grain, such that the sheet glass material is polished into the glass substrate including a principal surface having a target flatness for the magnetic disk.