Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
2001-05-31
2004-02-03
Letscher, George J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06687093
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to disk drives and methods for manufacturing disk drives.
2. Description of the Prior Art
A typical hard disk drive includes a head disk assembly (“HDA”) and a printed circuit board assembly (“PCBA”). The HDA includes at least one magnetic disk (“disk”), a spindle motor for rotating the disk, and a head stack assembly (“HSA”) that includes a head with at least one transducer for reading and writing data. The HSA is controllably positioned by a servo system in order to read or write information from or to particular tracks on the disk. The typical HSA has three primary portions: (1) an actuator assembly that moves in response to the servo control system; (2) a head gimbal assembly (“HGA”) that extends from the actuator assembly and biases the head toward the disk; and (3) a flex cable assembly that provides an electrical interconnect with minimal constraint on movement.
A typical HGA includes a load beam, a gimbal attached to an end of the load beam, and a head attached to the gimbal. The load beam has a spring function that provides a “gram load” biasing force and a hinge function that permits the head to follow the surface contour of the spinning disk. The load beam has an actuator end that connects to the actuator arm and a gimbal end that connects to the gimbal that carries the head and transmits the gram load biasing force to the head to “load” the head against the disk. A rapidly spinning disk develops a laminar airflow above its surface that lifts the head away from the disk in opposition to the gram load biasing force. The head is said to be “flying” over the disk when in this state.
Within the HDA, the spindle motor rotates the disk or disks, which are the media to and from which the data signals are transmitted via the/head on the gimbal attached to the load beam. The transfer rate of the data signals is a function of rotational speed of the spindle motor; the faster the rotational speed, the higher the transfer rate. A spindle motor is essentially an electro-magnetic device in which the electromagnetic poles of a stator are switched on & off in a given sequence to drive a hub or a shaft in rotation, the hub including a permanent magnetic ring.
FIG. 1
shows the principal components of a magnetic disk drive
100
constructed in accordance with the prior art. With reference to
FIG. 1
, the disk drive
100
is an Integrated Drive Electronics (IDE) drive comprising a HDA
144
and a PCBA
114
. The HDA
144
includes a base
116
and a cover
117
attached to the base
116
that collectively house a disk stack
123
that includes a plurality of magnetic disks (of which only a first disk
111
and a second disk
112
are shown in FIG.
1
), a spindle motor
113
attached to the base
116
for rotating the disk stack
123
, an HSA
120
, and a pivot bearing cartridge
184
(such as a stainless steel pivot bearing cartridge, for example) that rotatably supports the HSA
120
on the base
116
. The spindle motor
113
rotates the disk stack
123
at a constant angular velocity about a spindle motor rotation axis
175
. The HSA
120
comprises a swing-type or rotary actuator assembly
130
, at least one HGA
110
, and a flex circuit cable assembly
180
. The rotary actuator assembly
130
includes a body portion
140
, at least one actuator arm
160
cantilevered from the body portion
140
, and a coil portion
150
cantilevered from the body portion
140
in an opposite direction from the actuator arm
160
. The actuator arm
160
supports the HGA
110
with a head. The flex cable assembly
180
includes a flex circuit cable and a flex clamp
159
. The HSA
120
is pivotally secured to the base
116
via the pivot-bearing cartridge
184
so that the head at the distal end of the HGA
110
may be moved over a recording surface of the disks
111
,
112
. The pivot-bearing cartridge
184
enables the HSA
120
to pivot about a pivot axis, shown in
FIG. 1
at reference numeral
182
. The storage capacity of the HDA
111
may be increased by including additional disks in the disk stack
123
and by an HSA
120
having a vertical stack of HGAs
110
supported by multiple actuator arms
160
.
According to the prior art, the HSA
120
is shipped together with a conventional shipping comb that separates and protects the heads during the shipping of the HSA
120
and prior to the integration of the HSA
120
in the HDA
144
. The combination of the HSA
120
and the conventional shipping comb is conventionally installed into the base
116
of the HDA
144
and held in position away from the disk stack
123
by means of a device such as a temporary pin
190
. This temporary pin
190
is typically inserted through a hole
192
defined at least in the top VCM plate
170
and through a hole (or slot)
194
defined in the overmolding of the coil portion
150
of the VCM. This immobilizes the HSA
120
and keeps the heads clear of the disks
112
,
111
. After the HSA
120
is secured to the baseplate
116
, a merge comb (not shown) is inserted between the suspensions of the HSA
120
to spread the heads with sufficient clearance to enable them to be safely merged onto the disk(s)
111
,
112
. Once the merge comb is positioned, the conventional shipping comb and the temporary pin
190
are removed so that the heads may be merged onto the disk(s)
111
,
112
.
The use of the temporary pin
190
, however, brings about a number of problems. Such problems include, for example, extra part handling during the assembly process by the production operator. Such extra handling may equate to about three seconds of lost throughput for each drive built. Competitive pressures in the disk drive industry drive continue to drive storage prices downward and three seconds of lost throughput per drive represents a non-trivial cost, when aggregated over a large volume of drives. Other disadvantages associated with the temporary pin
190
include the finite reusable lifespan thereof and the cost of the mold used to manufacture the pin
190
, as well as the cost of the pin
190
. There is also a danger that the temporary pin
190
may be inadvertently left in place during the merge operation, with catastrophic results for the HDA
144
. Indeed, if the pin
190
is left in place as the merge operation is performed, the HDA
144
and/or HSA
120
may be damaged, as may be the assembly tooling. In addition, the presence of the temporary pin
190
may cause foreign object damage or a back end test failure of the HDA
144
.
What is needed, therefore is an alternative to the use of the temporary pin
190
during the HDA assembly process. What are also needed are less costly methods of manufacturing disk drives and disk drives that are not prone to the actual and potential problems associated with the use of such temporary pins
190
.
SUMMARY OF THE INVENTION
Accordingly, this invention may be regarded as a method of making a head disk assembly, the head disk assembly including a base and a head stack assembly having a voice coil motor and a pair of load beams, each load beam having a head. The method comprises the steps of providing a head stack structure including a shipping comb positioned on the head stack assembly, the shipping comb including an extended pin feature and a shipping comb finger that is configured for insertion between the load beams to separate the heads; installing the head stack structure to the base such that the extended pin feature of the shipping comb extends into a blind receptacle defined into the base; engaging a merge comb having a merge comb finger into the head stack structure such that the merge comb finger is disposed between the load beams, and removing the shipping comb from the head stack structure.
The present invention is also a disk drive, comprising a housing including a base, the base defining a blind receptacle; a spindle motor attached to the base; a disk mounted to the spindle motor; a head stack assembly pivotally coupled to
Butler Walter W.
Cheng Chunjer C.
Congdon Craig W.
Ketchu Charles E.
Lloyd Robert E.
C. Kim, Esq. Won Tae
Letscher George J.
Shara, Esq. Milad G.
Western Digital Technologies Inc.
Young, Esq. Alan W.
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