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

• Main Authors: IMAGAWA KIMIE, KITAMURA NAOKI, KITAWAKI KOTARO, NAKAMURA TADAHIRO, YOSHIMURA KEITA, TAKAHASHI HIDEKI, KUMAGAI KO
• Format: Patent
• Language: English; Japanese
• Published: 03.10.2019
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

To provide an aluminum alloy substrate for a magnetic disk having high flatness with improved floating stability of the magnetic disk.SOLUTION: An aluminum alloy substrate 1 for a magnetic disk is defined as a rolling streak direction as a rolling mark, and when a direction parallel to the rolling streak direction from a center S of a disk with radius r is 0°, a clockwise direction on a main surface of the disk is positive, and plate thicknesses at the respective positions b1, b2, b3, a1, a2, a3 of polar coordinates (0.72r, 45°), (0.53r, 90°), (0.72r, 135°), (0.72r, 315°), (0.53r, 270°), (0.72r, 225°) are defined as t, t, t, t, t, t, these six plate thicknesses satisfy a predetermined inequality relationship.SELECTED DRAWING: Figure 1 【課題】磁気ヘッドの浮上安定性を向上させた高平坦な磁気ディスク用アルミニウム合金基板を提供する。【解決手段】磁気ディスク用アルミニウム合金基板１は、圧延目を圧延スジ方向と定義し、半径ｒのディスクの中心Ｓから上記圧延スジ方向に平行な方向を０°とし、上記ディスクの主面において右回りを正として極座標（０．７２ｒ，４５°）、（０．５３ｒ、９０°）、（０．７２ｒ，１３５°）、（０．７２ｒ，３１５°）、（０．５３ｒ，２７０°）、（０．７２ｒ，２２５°）それぞれの位置ｂ１、ｂ２、ｂ３、ａ１、ａ２、ａ３での板厚をｔｂ１、ｔｂ２、ｔｂ３、ｔａ１、ｔａ２、ｔａ３と定義したとき、これら６箇所の板厚が所定の不等式関係を満たす。【選択図】図１