Browse Prior Art Database

Zero Droop Disk Clamping Assembly

IP.com Disclosure Number: IPCOM000042004D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Allen, KD: AUTHOR [+3]

Abstract

This new design solves the problem of disk droop. Disk droop is defined as the difference between the axial deflection of the disk OD (outer diameter) and ID (inner diameter). This new design also reduces home-address shift in the presence of clamping force relaxation. The essential ingredients of the design are (1) a number of disks, (2) disk spacers, and (3) a clamping mechanism. Conventional disk clamp design (Fig. 1) makes the clamp contact points line up with the center-line of the disk spacer outside and inside diameters. This conventional design causes droop in the top and bottom disks as the disk stack is clamped. The other disks experience droop as well, but a minor amount compared to the outer disks. The droop for the disks in the middle of the stack is essentially zero.

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Zero Droop Disk Clamping Assembly

This new design solves the problem of disk droop. Disk droop is defined as the difference between the axial deflection of the disk OD (outer diameter) and ID (inner diameter). This new design also reduces home-address shift in the presence of clamping force relaxation. The essential ingredients of the design are (1) a number of disks, (2) disk spacers, and (3) a clamping mechanism. Conventional disk clamp design (Fig. 1) makes the clamp contact points line up with the center-line of the disk spacer outside and inside diameters. This conventional design causes droop in the top and bottom disks as the disk stack is clamped. The other disks experience droop as well, but a minor amount compared to the outer disks. The droop for the disks in the middle of the stack is essentially zero. Droop occurs because the clamp exerts a radial shear force on the disks as it expands under load. The new design (Fig. 2) presented here eliminates disk droop by making the clamp contact points and disk spacer center- line radially offset from one another. Figure 2 illustrates: The offsets at the top and bottom of the disk stack compensate for the radial shear and will result in zero disk droop for properly chosen offsets. The offset can be achieved by varying any or all of three parameters: the diameter of the clamp contact points, the disk spacer inside diameter, and the disk spacer outside diameter. The configuration depicted in Fig. 2 will result in zero droop for the top and bottom disks only, which have far more droop than the other disks anyway. The optimal design, where the droop for all disks is zero, would probably have each disk spacer be a different diameter. The amount and direction of the proper offsets can be determined by an iterative process using finite element structural analysis, or by experimental techniques. The taper spacer on a current disk file does a satisfactory job of reducing disk droop. However, in the event of some relaxation in the clamp force, the disk w...