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Load Distributing Disk Clamp

IP.com Disclosure Number: IPCOM000061407D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Goeke, DC: AUTHOR [+2]

Abstract

A common clamping technique for securing data disks to the hub of a disk drive is the use of a ring shaped plate that has its inner diameter (ID) resting on the hub and its outer diameter (OD) held against a spacer at the ID of the disk stack. A series of screws threaded into the hub provide the loading forces securing the clamp ring and disk stack in place. Due to compliance of the clamping plate, the primary loading points to the disk stack are adjacent each of the screws. These discrete loading points cause deflections in the disks at their ID and normal to the disk surface which can be detected by repeatable X-double-dot measurements at the disk ID. The X-double-dot measurement is a mea of the acceleration of the disk surface toward the head caused by surface irregularities.

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Load Distributing Disk Clamp

A common clamping technique for securing data disks to the hub of a disk drive is the use of a ring shaped plate that has its inner diameter (ID) resting on the hub and its outer diameter (OD) held against a spacer at the ID of the disk stack. A series of screws threaded into the hub provide the loading forces securing the clamp ring and disk stack in place. Due to compliance of the clamping plate, the primary loading points to the disk stack are adjacent each of the screws. These discrete loading points cause deflections in the disks at their ID and normal to the disk surface which can be detected by repeatable X-double- dot measurements at the disk ID. The X-double-dot measurement is a mea of the acceleration of the disk surface toward the head caused by surface irregularities. These deflections are most severe in the top disk in the stack but can be detected in all disks of the stacks to a progressively lesser extent. This irregularity can reduce the yield of acceptable quality disk assemblies.

The disk clamp shown in the figure addresses the problem of clamp-induced deflections in the disks. By removing material from the clamp at each of the six loading points 5 adjacent the openings 6 for the mounting screws, the load is more evenly distributed. The final design is a six-sided plate which transfers the load to the disk stack at 12 points evenly spaced ar the ID of the disk stack. A second 1-millimeter seal plate is inserted benea...