POLISHING BRUSH, POLISHING METHOD, POLISHING APPARATUS, METHOD OF MANUFACTURING GLASS SUBSTRATE FOR MAGNETIC DISK, AND METHOD OF MANUFACTURING MAGNETIC DISK

摘要

A POLISHING BRUSH (20) IS USED IN A POLISHING METHOD FOR POLISHING THE INNER PERIPHERY (12) OF A CIRCULAR GLASS SUBSTRATE (1) HAVING A CIRCULAR HOLE IN THE CENTER BY ROTATING THE POLISHING BRUSH (20) IN CONTACT WITH THE INNER PERIPHERY (12) OF THE GLASS SUBSTRATE (1) WHILE A LIQUID ABRASIVE IS BEING SUPPLIED TO THE PERIPHERY (12). THE POLISHING BRUSH (20) INCLUDES AN AXIS (21) AND BRISTLE MATERIALS (22) PROTRUDING IN THE DIRECTION PERPENDICULAR TO THE AXIS (21), AND HAS TWO TYPES OF PORTIONS HAVING DIFFERENT OUTER DIAMETERS (D1 AND D2) ALTERNATELY ARRANGED IN THE DIRECTION OF THE AXIS (21). THE BRISTLE MATERIALS (22) OF THE PORTIONS HAVING SMALL DIAMETER (D2) HAVE A HIGHER HARDNESS THAN THE BRISTLE MATERIALS (22) OF THE PORTIONS HAVING LARGE DIAMETER (D1). FOR THIS PURPOSE, THE BRISTLE MATERIALS (22) OF THE PORTIONS HAVING SMALL DIAMETER (D2) OF THE POLISHING BRUSH (20) ARE BOUND TOGETHER WITH A RESIN.