ALUMINUM ALLOY SUBSTRATE FOR MAGNETIC DISK, ITS MANUFACTURING METHOD AND DIE FOR PUNCH-PRESSING ALUMINUM ALLOY SUBSTRATE FOR MAGNETIC DISK

摘要

PROBLEM TO BE SOLVED: To provide an aluminum alloy substrate for a magnetic disk wherein the sagging depth of an outer edge is shallow, to provide its manufacturing method, and to provide a die for punch-pressing the substrate. SOLUTION: The aluminum alloy substrate for the magnetic disk has the≤150μm average sagging depth of the outer edge. The die for punch-pressing provided with a die, a punch and a stripper for punching an aluminum alloy raw plate in a doughnut is characterized in that a projecting part whose inner edge constitutes an edge and which has a flat part having a prescribed width (a) is formed at the punching face of the die. The manufacturing method of the aluminum alloy substrate for the magnetic disk is characterized in that a flat part recessed in a stripper direction by a prescribed quantity and having a prescribed width a1 is formed at the inner edge of the contact surface of a skeleton with the die in a process for punching the aluminum alloy raw plate in the doughnut by using the die for the press provided with the die, the punch and the stripper. COPYRIGHT: (C)2006,JPO&NCIPI