Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1999-08-31
2001-10-09
Yao, Sam Chuan (Department: 1733)
Bearings
Rotary bearing
Antifriction bearing
C384S585000, C360S099080, C360S265600, C310S049540, C310S06700R, C310S090000, C156S275500, C156S275700, C156S293000, C029S898070
Reexamination Certificate
active
06299358
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates in general to actuator pivot cartridges in hard disk drives and in particular to UV-transparent elements for allowing photosetting adhesives to cure in the actuator pivot cartridge or spindle motor assembly of a hard disk drive.
2. Background Art
Referring to
FIG. 1
, an information storage system comprising a hard disk drive
11
is shown. Drive
11
has a base
13
containing a plurality of stacked, parallel magnetic disks
15
(one shown) which are closely spaced apart. Disks
15
are rotated by a spindle motor located therebelow about a central drive hub
17
. An actuator
21
is rotatably mounted to base
13
about an actuator pivot assembly
23
. A controller
25
is mounted to base
13
for selectively pivoting actuator
21
. Actuator
21
has a mounting support
27
, cantilevered load beams or suspensions
29
extending from mounting support
27
, and a head gimbal assembly
31
having at least one magnetic read/write head secured to each suspension
29
for magnetically reading data from or magnetically writing data to disks
15
. Suspensions
29
have a spring-like quality which biases or maintains them in parallel relationship relative to one another. A motor assembly
33
having a conventional voice coil motor is also mounted to pivot assembly
23
opposite head gimbal assemblies
31
. Movement of actuator
21
(indicated by arrows) moves head gimbal assemblies
31
radially across tracks on the disks
15
until the heads on assemblies
31
settle on the target tracks.
Referring now to
FIG. 2
, pivot assembly
23
contains a set of bearings
35
. A photosetting, anaerobic adhesive
37
is used to bond and seal the races of bearings
35
to a stationary housing
39
and an internal pivot shaft
45
. Some adhesive
37
is located in the very small, circumferential gaps
46
,
48
(approximately one to ten microns each) which extend between each bearing
35
, and shaft
45
and housing
39
, respectively. A hole
40
extends through the side of housing
39
into its interior and is used for mounting purposes.
Typically, the adhesive
37
is cured by passing the assembled pivots
23
under a UV light source (not shown). However, due to geometrical constraints, such as the opaque flange
43
on the pivot shaft
45
, access to adhesive
37
is severely limited. In addition, the small size of gaps
46
,
48
makes access to them severely limited. Most of the emitted light
41
reflects off the pivot and oven surfaces with few UV rays penetrating gaps
46
,
48
and the narrow slit or space
47
(approximately 0.1 mm in width) between the circumference of flange
43
and the inner diameter of housing
39
. This results in joints with uncured adhesive and lower bond strengths. When the pivots
23
are later subjected to file operating temperatures, the uncured or poorly cured adhesive can lead to loss of pivot preload or head and disk contamination from volatile pivot adhesive.
To solve this problem, pivot manufacturers have increased the number of passes made through the UV oven. For some pivots, a minimum of five passes through the oven are required to cure the adhesive in all areas of the pivots. Another option is to increase the time the pivots are exposed to the UV light to ensure that the adhesive has sufficiently cured. Unfortunately, these solutions require more power and longer process times which result in increased manufacturing costs and process inefficiencies.
SUMMARY OF THE INVENTION
Ultraviolet-transparent seals, flange, and sleeve assemblies are used in actuator pivot cartridges for hard disk drives to cure adhesive located inside the pivot housing. The assemblies are formed from silica glass, polymers, or other suitable materials, and focus UV light into hard to reach, high aspect ratio areas between the pivot bearings, sleeve, and shaft. Some of the assemblies use transparent components with convex or fresnel lenses formed into their geometry. With these designs, UV light can enter the pivots axially and/or radially to reach and cure the adhesive regardless of its location.
REFERENCES:
patent: 5411338 (1995-05-01), Goto
patent: 5459361 (1995-10-01), Morioka
patent: 5596235 (1997-01-01), Yazaki et al.
IBM Corporation Technical Disclosure/vol. 36, No. 32, Feb. 1993 “Hard-Disk Spindle Motor Assembly Having a Spacer Ring Through Which Nitrogen Gas or UV Light Can Pass”.
IBM Corporation Technical Disclosure/vol. 37, No. 04A, Apr. 1994 “Nitrogen and UV Pass-Thru Preloader”.
Albertson Eric Martin
Prater Walter Lloyd
Bracewell & Patterson L.L.P.
International Business Machines - Corporation
Martin Robert B.
Tolin Michael A.
Yao Sam Chuan
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