Disc clamp and spacer

Details Disc clamp and spacer Disc clamp and spacer

1993-12-15

1997-03-25

Evans, Jefferson

Dynamic magnetic information storage or retrieval

Record transport with head stationary during transducing

Disk record

360 9912, G11B 1702

Patent

active

056150679

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to the field of magnetic recording and in particular disc clamps and spacers for hard disc drive spindles and disc stacks.


BRIEF DESCRIPTION OF THE PRIOR ART

Disc clamps for magnetic hard disc drive spindles have as their primary objective the clamping of the magnetic hard discs in a stack onto the spindle so that the discs do not shift radially under shock. Such a radial shift, otherwise known in the industry as "disc slip", can result in total failure of the disc drive due to misalignment of the pre-recorded tracks on the slipped disc from the pre-recorded tracks on the other discs.
The primary method of disc clamps in the prior art is to provide a vertical clamping force on the top disc of a stack with the bottom disc of the stack abutting a spindle flange. The discs themselves are separated by spacers.
The required disc clamping force is determined by the shock specification of the disc drive. For example if the disc drive specification requires that the disc drive withstand a shock of 300 G's, a radial force must be applied to the disc on the order of three pounds. In order to achieve this force, the disc clamp must apply, for example, a 20 pound vertical clamping force because the coefficient of friction between the clamp and the disc is in the range of 0.15, which would translate a vertical or axial force of 20 lbs. into approximately 3 lbs. horizontal or radial force.
As disc drives become smaller, they are also becoming thinner. This puts severe constraints on the overall stack height of the disc/spindle assembly, which in turn, necessitates a reduction in the thickness of the discs and the height of the disc clamp above the spindle. As discs become smaller, there is also a tendency for the discs to warp into a potato chip shape due to the required clamping force of the disc clap to prevent "disc slip". For all the above factors, a new disc clamping approach is required.
One approach suggested in PCT Application No. WO93/06599 is to employ an annular clamp and spacer having a plurality of fingers exerting a radial pressure on a first disc and a plurality of projections bearing on a second disc to control radial movement of the first disc and the separation of the two discs.
Another approach is suggested in IBM Technical Disclosure Bulletin Vol. 32, No. 6, November 1989, page 129, Disc Pack Assembly Design, which describes the use of a grooved spliting to clamp a plurality of discs. Each disc rests in a groove in the ring which is squeezed and slipped into the internal diameter of the discs, when the ring is released it exerts a radial clamping force on the discs.


SUMMARY OF THE INVENTION

The invention comprises a disc spacer assembly having an integral flange which is interference tit against the inside circumferential rim of a magnetic disc. This interference tit is designed to apply to the disc the required radial force to resist "disc slip" that is traditionally applied by the clamp. The force of this disc spacer against the disc is provided by making the diameter of the spacer (flange) slightly larger than the inside diameter of the disc.
In a first embodiment, this invention provides a disc spacer comprising: integral flange sections depending from the spacer section to form a T-shape in the radial direction when viewed in cross section; and discs abutting the flanges.
In a preferred embodiment, the spacer has a small gap at one location in the annulus of the spacer, so that the spacer may be compressed into a smaller diameter. The compressed spacer is fitted into the inside diameter of the disc and is released to provide a spring force against the inside diameter of the disc. Alternatively, the radial load can be applied by first cooling the slightly oversized disc spacer (no gap) before insertion into the inside diameter of the disc, such that when the spacer warms to operating temperature it expands to provide the required spring force and load against the inside diameter of the disc.
In a second embodiment this invention provides a disc

REFERENCES:
patent: 4945432 (1990-07-01), Matsudaira et al.
patent: 5243481 (1993-09-01), Dunckley et al.
patent: 5249090 (1993-09-01), Fehse
IBM Technical Disclosure Bulletin; vol. 16, No. 12; Apr. 74; Griffiths et al; "Disk Pack Assembly".
IBM Technical Disclosure Bulletin; vol. 32, No. 6A; Nov. 89; "Disk Pack Assembly Design".
IBM Technical Disclosure Bulletin; vol. 32, No. 12; May 90; "Disk Stack Clamping Means".

Affiliated with

Also associated with

Rating

Disc clamp and spacer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Disc clamp and spacer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disc clamp and spacer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2208882