Aluminum alloy substrate for magnetic disk, disk drive device, method for manufacturing aluminum alloy substrate for magnetic disk, and method for measuring aluminum alloy substrate for magnetic disk

Abstract

Provided is an aluminum alloy substrate for a magnetic disk, with which high flattening of the entire aluminum alloy substrate is achieved, and with which it is possible for floating stability of a magnetic head to be improved further. In an aluminum alloy substrate (1) for a magnetic disk, when a rolling direction is defined as a rolling streak direction, a direction parallel to the rolling streak direction from a center S of a disk having a radius r is defined as 0 degree, and a clockwise rotation on a principal surface of the disk is defined as positive, if the plate thickness of the disk at a position (b1) represented by polar coordinates (0.72r, 45 degrees) is defined as tb1, the plate thickness at a position (b2) represented by polar coordinates (0.53r, 90 degrees) is defined as tb2,the plate thickness at a position (b3) represented by polar coordinates (0.72r, 135 degrees) is defined as tb3, the plate thickness at a position (a1) represented by polar coordinates (0.72r, 315 degrees) is defined as ta1, the plate thickness at a position (a2) represented by polar coordinates (0.53r, 270 degrees) is defined as ta2, and the plate thickness at a position (a3) represented by polarcoordinates (0.72r, 225 degrees) is defined as ta3, at least two of three inequalities in an inequality group [A] are satisfied and all four inequalities in an inequality group [B] are satisfied, orat least two of the three inequalities in the inequality group [A] are satisfied and all four inequalities in an inequality group [C] are satisfied.

Description

technical field [0001] The present invention relates to an aluminum alloy substrate for a magnetic disk, a disk drive device, a method for manufacturing an aluminum alloy substrate for a magnetic disk, and an aluminum alloy substrate for a magnetic disk, and particularly relates to an aluminum alloy substrate for a magnetic disk used as a recording medium for a computer and the manufacture of the aluminum alloy substrate method. Background technique [0002] Conventionally, disk drives such as hard disk drives (hereinafter referred to as "HDDs") have been widely used in computers. In general, an HDD includes: one or more disks for recording data; a spindle motor for rotating the disks; a clamping member for fixing the inner diameter side of the disks; a magnetic head for processing data for each disk; a swing arm for movably supporting the magnetic head; and an actuator for rotating and positioning the swing arm. [0003] In such an HDD, it is necessary to rotate the magne...

AI Technical Summary

Problems solved by technology

However, when the disk rotates at a high speed, air flow is generated by the air rotating with the disk, and the air flow is disturbed, causing the disk to vibrate, and a phenomenon called chatter occurs.

Such chattering is the main cause of deteriorating the floating stability of the magnetic head, lowering the positioning accuracy of the magnetic head relative to the disk, and hindering the improvement of the recording density.

[0004] It is known that the flatness of the magnetic disk has a great influence on the floating stability of the magnetic head

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