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Integral Ball Bearing Spindle/Hub Assembly for Disk Drives

IP.com Disclosure Number: IPCOM000104913D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 117K

Publishing Venue

IBM

Related People

Albrecht, D: AUTHOR

Abstract

An improved integral ball bearing spindle/hub cartridge assembly is shown in Figs. 1 and 2 where the two outer races are integrally ground in a single piece and one of the inner races is also integral to the shaft. The outer races are of an angular contact geometry to permit easy axial assembly of preassembled cage/ball complements of a high ball count. The integral inner race can be either a deep groove or angular contact geometry. In Fig. 1, the outer race is stationary and the inner rotates so the integral inner race is located nearest the rotating hub datum to ensure the least amount of RRO and NRRO of that surface. In Fig. 2, the outer race with hub rotates, so the integral inner race is located nearest the spindle assembly mounting surface in order to create a stiff mechanical arrangement in cantilevered applications.

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Integral Ball Bearing Spindle/Hub Assembly for Disk Drives

      An improved integral ball bearing spindle/hub cartridge
assembly is shown in Figs. 1 and 2 where the two outer races are
integrally ground in a single piece and one of the inner races is
also integral to the shaft.  The outer races are of an angular
contact geometry to permit easy axial assembly of preassembled
cage/ball complements of a high ball count.  The integral inner race
can be either a deep groove or angular contact geometry.  In Fig. 1,
the outer race is stationary and the inner rotates so the integral
inner race is located nearest the rotating hub datum to ensure the
least amount of RRO and NRRO of that surface.  In Fig. 2, the outer
race with hub rotates, so the integral inner race is located nearest
the spindle assembly mounting surface in order to create a stiff
mechanical arrangement in cantilevered applications.  In Fig. 2, as
both rotating races are integral to the rotating member, there is no
significant advantage in having the integral inner race near the hub
datum.

      The following advantages are realized as a result of the
spindle assembly configurations shown.

      The first advantage involves ease of assembly.  The geometry of
the spindle assemblies is such that the hub can be first assembled to
the bearing rotating member by some suitable means such as adhesive
or a press fit, and then the hub datum surface machined true to the
rotating datum in the bearing.  After machining, this subassembly can
be easily cleaned.  Then for the spindle arrangement shown in Fig. 1,
the upper shield and cage/ball complement can then be assembled in
the outer bearing member and that subassembly axially inserted over
the shaft with the integral race.  The second discreet inner race
with its preassembled cage/ball complement is then assembled to the
shaft, dead weight preloaded in the axial direction, and adhesively
bonded to lock in the preload, thus creating a high precision
spindle/hub assembly with only one bond joint in the bearing system.
Fig. 3 is an exploded diagram that illustrates the above assembly
process.  A similar assembly process is used for the spindle assembly
in Fig. 2.

      Other advantages of this spindle arrangement include that for a
given spindle bearing volume, the largest ball count...