Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-07-23
2003-05-13
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S275700, C156S294000, C156S379600, C156S379800, C360S099080, C385S123000
Reexamination Certificate
active
06562176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates in general to curing photosetting adhesives and in particular to devices and methods for curing photosetting adhesives in a pivot cartridge assembly with concentrated UV light.
2. Description of the Related 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 motor located therebelow about a central drive hub
17
. An actuator
21
is rotatably mounted to base
13
about a pivot assembly
23
. A controller
25
is mounted to base
13
for selectively moving actuator
21
as will be described below.
Actuator
21
has a mounting support
27
, a pair of parallel, 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.
During operation (FIG.
2
), bearings
35
inside pivot assembly
23
emit oil vapor and aerosol droplets of grease which are a potential source of contamination in the disk drive. Reducing this type of contamination is important to improve the reliability of disk drives. In pivot assembly
23
, a photosetting, anaerobic adhesive
37
is used to bond and seal the rings of the 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
41
. 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 perimeter of flange
43
and the inner diameter of housing
39
. This results in joints with uncured adhesive and lower bond strengths. When the pivot
23
is later subjected to file operating temperatures, the uncured adhesive will outgas from parts and may also propagate cracks in the bond, which can lead to pivot failure.
To solve this problem, pivot manufacturers have increased the time the pivots are exposed to the UV light to ensure that the adhesive has sufficiently cured. Unfortunately, this solution requires more power and longer process times which result in increased manufacturing costs and process inefficiencies.
Therefore, it is a feature of the present invention to provide improved methods for directing UV light to the less accessible portions of pivots to provide a completely cured bond.
It is another feature of the present invention to provide decreased manufacturing costs and cycle times for processing pivots.
SUMMARY OF THE INVENTION
One embodiment of an adhesive curing apparatus and method utilizes the end of a tube or optical fiber extending from a UV light source. The tube end is inserted into the mounting hole in the side of a pivot assembly. The tube projects concentrated UV light into the interior of the assembly for curing the adhesive used to bond the bearings to the shaft and the housing. The tip at the end of the tube has beam splitting mirrors or prisms to distribute the UV light more effectively. The interior of the assembly, including the outer surface of the shaft and the inner surface of the housing are smooth, polished metal to further enhance the intensity of the light incident on the adhesive.
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patent: 60026075 (1985-02-01), None
patent: 63186789 (1988-02-01), None
patent: 01048879 (1989-02-01), None
patent: 3108171 (1991-05-01), None
patent: 405109819 (1993-04-01), None
Hard Disk Motor Assembly Process with Ultra-iolet Adhesive in Nitrogen Atmosphere, IBM Technical Disclocure Bulletin, Dec. 1992, vol. 35, No. 7.
Hard Disk Spindle Motor Assembly Having a Spacer Ring Through Which Nitrogen Gas of UV Light can Pass, IBM Technical Disclosure Bulletin, Feb. 1993, vol. 36, No. 2.
Albertson Eric Martin
Prater Walter Lloyd
Aftergut Jeff H.
Bracewell & Patterson L.L.P.
Goff John L.
International Business Machines - Corporation
Martin Robert B.
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