Patent ID: 8210903
Filing Date: 2012-07-03
Classification: C03C,G11B

Abstract:
1. A method of manufacturing a glass substrate for a magnetic disk, comprising an inner circumference polishing step in which an inner circumferential end face of a cylindrical polishing object is polished, the polishing object including a plurality of disk-like glass substrates stacked on one another, each of the disk-like glass substrates having an inner hole formed in its center, wherein, in the inner circumference polishing step: a plurality of polishing cloths disposed around a rotation axis of an inner circumference polishing section having the rotation axis are contacted by pressure to the inner circumferential end face of the polishing object at even pressure and are pressed in face contact to the inner circumferential end face as a whole of the polishing object, then a polishing liquid, which is a slurry including free abrasive grains, is supplied between the inner circumferential end face of the polishing object and the inner circumference polishing section, and then the inner circumference polishing section and the polishing object are relatively rotated/moved with the rotation axis as a center, or relatively moved in a direction of the rotation axis, thereby the inner circumferential end faces of said plurality of disk-like glass substrates are mirror-polished, and wherein: while the center of the inner hole of each of the disk-like glass substrates is allowed to correspond to the rotation axis of the inner circumference polishing section, the inner circumferential end faces of said plurality of disk-like glass substrates are mirror-polished, said plurality of polishing cloths are disposed around the rotation axis of the inner circumference polishing section with a space left between adjacent ones of said plurality of polishing cloths, the spaces between said plurality of polishing cloths are passages of the slurry, and outer diameter formed by outer surfaces of said plurality of polishing cloths is formed to have a curved surface along an inner diametrical shape of each of said plurality of disk-like glass substrates, said outer diameter fits with a circumferential surface of inner diameter of each of said plurality of disk-like glass substrates.