Browse Prior Art Database

Improved Low-Cost Oil Bearing Spindle for Hard Disk Drive

IP.com Disclosure Number: IPCOM000115737D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 103K

Publishing Venue

IBM

Related People

Albrecht, D: AUTHOR [+5]

Abstract

Disclosed is an improved hydrodynamic oil bearing spindle configuration for a disk drive with a bearing groove geometry that creates a pumping action to contain the low viscosity oil. An alternative lower cost implementation of this basic configuration is also disclosed in which the rotating disk hub and oil bearing journal/thrust surface are created in a single piece aluminum part. The journal bearing grooves are created in the rotating member by a broaching process and the stationary thrust plate bearing grooves can be created by a novel coining process. An alodine process can be used to give the aluminum journal and thrust surfaces superior tribology characteristics against the stationary shaft and thrust plate materials.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Improved Low-Cost Oil Bearing Spindle for Hard Disk Drive

      Disclosed is an improved hydrodynamic oil bearing spindle
configuration for a disk drive with a bearing groove geometry that
creates a pumping action to contain the low viscosity oil.  An
alternative lower cost implementation of this basic configuration is
also disclosed in which the rotating disk hub and oil bearing
journal/thrust surface are created in a single piece aluminum part.
The journal bearing grooves are created in the rotating member by a
broaching process and the stationary thrust plate bearing grooves can
be created by a novel coining process.  An alodine process can be
used to give the aluminum journal and thrust surfaces superior
tribology characteristics against the stationary shaft and thrust
plate materials.  By comparison, other fluid spindles known in the
art require more costly manufacturing processes while ball bearing
spindles have more Nonreaptable Runout (NRRO) and require more space
for the bearing system which gives less space for an efficient high
RPM motor.

      Fig. 1A shows the basis configuration of an inside diameter
motor oil spindle where the disk hub aluminum flange (1) is heat
shrunk to a steel inner member (2) that forms one half of the journal
and thrust surfaces.  The inner member provides the magnetic flux
return path for the motor magnets.  The herringbone bearing groove
patterns (9) on the shaft in Fig. 2 can either be machined or etched
and are asymmetrical in length to prevent the oil from being pumped
out of the journal gap which has a radial dimension of about 5
microns.  Low surface energy barrier films (4) are coated on either
end of the shaft (3) and the inside diameter of the rotating thrust
plate cap (5) to further deter migration of the oil from the bearing.
The stationary thrust plate (6) is rigidly connected to the shaft by
either a heat shrink or press fit and also contains a balanced pair
of spiral groove patterns (10) as shown in Fig. 2B.  This precision
pattern can be formed by a low cost coining operation for thrust
plates made from bronze or other similar formable materials.  Axial
clearance between the stationary and rotating thrust plates is on the
order of 10 microns.  The inner corner of the...