DISK FILE INCLUDING MEANS FOR ENSURING DISK/HUB CONCENTRICITY

摘要

A disk file includes an expansion ring attached to the wall of the hub (26) and which is located between the lowermost disk (22) of the disk stack and the hub flange. A circular ridge (52) concentric with the hub is formed on the ring and engages the underside of the disk. The ring is adapted so that the thermal expansion of the ring is substantially equal to that of the aluminum disk at the position of contact between the two. A washer (51) interposed between ring and flange allows the ring to move freely relative to the flange. During thermal cycling, the ring and disk move at the same rate at the point of contact, the ring ensuring that the disks remain concentric with the hub throughout the range of disk file operating temperatures.