Note: Descriptions are shown in the official language in which they were submitted.
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00875-1
IMPROV~D SUBSTRATE FOR RIGID DISK STORAGE MEDIA
AND METHOD ~ND APPARATUS FOR MAKING THE SAME
This invention relates to improvements in the
manufacture of data storage meaia and, more
particularly, to an improved rigid substrate for making
a rigid disk storage medium.
The information processing industry is
expanding at an extreme`ly high rate as is well known.
In fact, in the 1982 Annual Report of IBM, it is
predicted that the information processing industry will
exceed Sl trillion by 1990. In this prediction,
computer-related hardware is forecast to be a $200
bill~on segment of the industry. Of this segment, the
rigid disk drive portion is the single, largest
element. It is further forecast that the rigid disk
market will grow from an $11 billion business in 1983
to well over $40 billion dollars by 1990. This
prediction recognizes a market for the rigid disk type
of storage media which gives rise to the need for
improvements in the manufacture of rigid disks in such
a manner as to minimize production costs, increase
production yields, and improve the quality of such - -
storage media.
Conventional techniques of making rigid disk
recording media leave much to be desired because of the
inherent flaws and defects which remain in the media as
the result of the manufacture techniques which are
used. A rigid disk recording medium includes a rigid
' substrate over the faces of which a coating of storage
material~ such as magnetic or optical material, is
placed. Unless the substrate is properly manufactured,
these flaws or defects will arise inherently, and
control in the manufacture of the substrates to
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eliminate the flaws and defects is a time consuming,
high cost aspec~ of the overall manufacturing process.
To minimize the flaws in such conventional
substrates, several different techniques have been
adopted and used, none with any great success.
Among these techniques is an abrasive machining
technique in which an abrasive material is applied to
the faces of a substrate to eliminate the flaws or
defects on such faces. Another technique is the
so-called lathe-turning or diamond-turning technique
~here each substrate is rotated about its central axis
and subjected to the cutting technique of a diamond
tipped tool to smooth the faces and to flatten the same
while removing oxides and other coatings therefrom.
Still a third technique is an electrochemical machining
techn~que which subjects the faces of a rigid substrate
to an electrochemical process to clean the faces and
make them substantially flat and parallel with each
other. The most popular technique adopted and used to
date, however, is a combination of the three techniques
mentioned above. However, none of the techniques used
today is economical orprovides a high yield output;
thus, serious limitations exist in the manufacture of
substrates for rigid disk recording media if it is
desired to have a high quality product at minimum cost.
A typical procedure in the manufacture of a
substrate for use as the base of a rigid disk recording
medium includes the purchase of a disk blank with a
roughed inner diameter and outer diameter. The blank
is initially directed through a double disk grinder to
cause the faces of the blank to become substantially
; ' flat and to remove the oxide layer on the faces of the
blank. Then ! the blank is directed through an edging
and chamfer machine to bore the inner and outer
peripheries to try to assure that the inner and outer
diameters will be substantially within certain
tolerances. The blank is then directed through a flat
54 3~ ~ ~
baking oven and subjected to 10 to 12 hours of this
oven for annealing purposes. The blank is then put
into a diamond-turning lathe, and the two faces of the
I blank are subjected to a reduction step by the diamond
tool. After this has occurred, both faces of the blank
must then be examined and inspected to assure that it
contains no major flaws or defects and is within
certain tolerances specified for the manufacture of a
rigid disk recording medium. All the foregoing is
extremely time consuming and costly and provides a
limited yield at best, such as lO0 to 125 blanks per
hour. Moreover, not all of the flaws and defects
associated with the blanks are clearly eliminated;
thus, the quality of the resulting product for use as a
substrate for a rigid disk recording medium is
relat~vely low and rejections are common everyday
occurrences. Flaws and defects found in conventional
substrates are random and unpredictable. Their
combined effect is to produce substrates as unique as
fingerprints, traceable to the machinery and variables
that are used to produce them. The mechanical
integrity and strength of conventional substrates is -
questionable at all times and their reliability is
relatively low over long periods of time.
Because of the foregoing problems associated
with conventional disk media substrates, a need has
existed and continues to exist for a high quality rigid
disk media substrate for use in data storage
technology, including those in the microcomputer and
other markets, such as audio, video and laser disk
recording, all of which require a substrate of high
; quality specifications and consistent quality. The
present invention satisfies the need for such a high
quality rigid disk media substrate.
The present invention is directed to an
improved substrate for use as part of a rigid disk
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recording medium wherein the substrate is substantially
free of all the flaws and defects of conventional rigid
disk substrates yet the substrate of the present
invention can be made at high production speeds and be
5 of extremely high quality while assuring that the
substrate will be consistent in geometry and
reliability and will have high mechanical and
structural integrity and strength. Moreover, the
substrate of the present invention can be made so that
the faces of the substrate can have any desired
texture, lay or form so that the substrate will be
suitable for a wide variety of applications
notwithstanding its high quality and high structural
and mechanical integrity. Additional features of
substrates of the present invention is that they have
unifq~m part-to-part dimensions and consistent geometry
including uniformity of surface, parallelism of faces
and flatness of such faces. Each substrate is
symmetrical, pre-stressed, stronger and more
dimensionally stable and with greater integrity than
substrates which require machining from rough blanks.
Another aspect of the present invention is
the provision of apparatus and a method for forming a
substrate of the type described. Such apparatus and
method allow for the high yield manufacture of the
substrate in a single pass through a production line,
beginning with the blanking or stamping of disks from
an elongated strip of material, such as aluminum or ;-
aluminum alloy. The apparatus and method further
include cleaning and treating the blanks as they move
toward and through an embossing or coining press in
- which each substrate disk or blank is subjected to a
high pressure, such as 1500 tons or more, to cause a
cold flow of the material on the faces and within the
disks, resulting in a surface on each face of extremely
high quality, free of flaws, consistent and uniform in
dimensions and geometry and parallelism between the
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faces and flatness of each face, respectively. The
apparatus further includes means for packaging the
coined disks in such a manner that the disks are kept
free of contamination with the atmosphere, yet the
disks can be immediately moved to a point of use or
storage location depending upon needs for production of
high quality rigid disk storage media using the coined
substrates.
The primary object of the present invention
is to provide an improved substrate for use as a part
of a rigid disk storage medium wherein the substrate is
formed in a coining process to provide surfaces on the
substrate which are uniform in dimension and consistent
in geometry with other substrates, including uniformity
in surface, parallelism of faces and flatness of each
face~of the substrate, whereby the substrate is
virtually free of flaws typically found in substrates
produced by conventional diamond-turning and abrasive
machining techniques yet the substrate of the present
invention is of extremely high quality, can be made at
high production rates at minimum cost.
Another object of the present invention is to
provide an improved substrate of the type described
wherein the substrate can be fabricated with any
desired surface finish, texture, lay or form yet the -
substrate has high mechanical and structural integrity
and strength and can be made at a rate many times
greater than the rate at which conventional substrates -
can be produced, all of which reduces the cost of
production while providing a substrate of vastly
improved quality over conventional substrates.
; ' Another object of the present invention is to
provide an apparatus and a method for the high
production manufacture of substrates of the type
described wherein the substrates can be formed,
cleaned, coined, stacked and loaded onto trays in an
- automatic fashion, all- of which can be done at high
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production speeds, at minimum cost and substantially
with no operator attention except to provide stock
material to the apparatus.
Other objects of this invention will become
apparent as the following specification progresses,
reference being had to the accompanying drawings for an
illustration of the invention.
IN THE DRAWINGS:
Fig. la is a perspective, schematic view of
the upstream stage of an apparatus for the high volume
manufacture of substrates for use as parts of storage
media, the view showing the way in which rolled stock
material is first treated before the stock is blanked
or stamped to form the disks which are used to form the
15 substrates;
~ Fig. lb is a view similar to Fig. la but
showing the next stage of the apparatus, and
illustrating the way in which the stamped disks are
directed out of a blanking machine and through a
mechanical cleaner;
Fig. lc is another view of the apparatus of
the present invention, showing the way in which the
disks are moved through cleaning tanks before being
sent to an embossing press for coining of the disks;
Fig. ld is another view of the apparatus of
the present invention, showing the way in which the
disks are moved out of a cleaning tank in one section
of a clean room and into a final clean room section
where the disks are subjected to high mechanical
pressures of the embossing press to coin the faces of
the disks;
; ' Fig. le is a view of the apparatus, showing
the way in which the coined disks leave the embossing
press and are placed in trays for transit through an
air lock separating the final clean room from the
ambient atmosphere;
,
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Fig. 2 is a top plan view of a section of the
elongated stock material showing various stages of
stampi~g the stock material to form the disks, the
center hole for the disks, and the chamfers on the
inner and outer peripheries of the disks;
Fig. ~ is a section through the stock
material showing the various stages of the stamping of
the disks therefrom;
Fig. 4 is an enlarged cross-sectional view of
the stock material, showing the way in which chamfers
are formed by dies on opposite sides of a disk;
, Fig. 5 is a perspective view of a transfer
device for feeding the disks into, through and out of
the embossing press in which the disks are coined;
Fig. 6 is a section through the die of the
embo~sing press, showing the way in which a disk is
contained between the faces of the die for coining
thereby;
Fig. 7 is a feed mechanism for stacking the
coined disks from the transfer device of Fig. 5 into
the grooves of a tray disposed on a conveyor.
The apparatus for forming coined or cold
forged substrates of the present invention for use as
storage media is shown in Fig.s la-le and is broadly
denoted by the numeral 10. Apparatus 10 is adapted for
forming substrates whose opposed faces are coined to
present a high quality product substantially free of
flaws associated with conventional substrates of
storage media. The resulting storage medium formed
with the substrate of this invention is of the type
shown in Fig. 8 in which the faces of the substrate are
coated with respective layers of a particular storage
material`and then used as a rigid disk, data storage
medium. Typical coatings include magnetic and optical
coatings to allow the storage medium to be used with
magnetic and optical read-write heads for recording
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digital or analog data and other information, such as
found in audio, video or computer applications.
Apparatus 10, at the upstream end thereof,
includes a holder 12 for mounting a roll 14 of a
suitable stock material, such as aluminum, for use in
forming disks which are to become the substrates of the
present invention. However, the stock material can be
of any type which constitutes a malleable or coinable
material or combination of materials, including clads
and laminates. Typically, the stock material is in the
form of a strip 16 of a standard width, such as from 7
to 9 inches. The strip is sufficiently flexible so
that it can be bent and doubled upon itself so that it
can be moved off and away from roll 14, past a guide
post 18 and into and through a straightening machine 20
havi~g a series of parallel rollers 22 which straighten
the strip 16 so that it is generally coplanar between
the side marginal edges thereof. The strip is then
moved past a second guide post (not shown) and into and
through a press 25 having a series of vertically
aligned rollers 26. The strip passes between the
center rollers 26 of the set to develop an
ultra-precision thickness for the strip. Typically,
the thickness of the stock strip is within a tolerance
range of l.003 inch. After passing the press 25, strip
16 will have a thickness tolerance in the range of
+.0001 inch. The purpose of this reduction in the
tolerance is to have a precision volume of material -
presented by each disk to the coining or embossing
press at a downstream location as hereinafter
described. Without such precision volume in the disk,
inconsistencies in dimensional and mechanical
characteristics of the various disks could develop
which would present problems encountered in the
manufacture of conventional substrates.
After the strip 16 leaves press 25, it moves
past a guide post (not shown) and into a blanking or
3~,'25~
stamping machine 30 in which a number of different
stamping steps are perfor~ed. The stamping machine 30
can be conventional in construction and has a specific
set of dies to perform the desired stamping steps. The
end result of the stamping operation in the stamping
machine 30 is a series of flat disks which have center
holes and which are chamfered on the inner and outer
peripheries thereof. A suitable stamping machine for
this purpose is a 250 ton blanking machine made and
sold by Minster Machine Company of Minster, Ohio.
The machine includes a series of dies 32 only two of
which are shown in Fig. lb.
Fig. 2 shows a sequence in the stamping of a
disk from strip 16 in machine 30. The first step
occurs when strip 16 is stamped to form holes 34 in the
stri~. These holes are used for receiving guide pins
which advance the strip through the machine to assure
precision stamping of the disks from the strip. When
holes 34 are formed, the disk 36 is also formed from
the strip, the disk being integral with strip 16 only
at webs 38. Also, a center hole 40 is formed by
stamping in the strip to form the center hole for disk
36. Fig. 3 shows strip 16 as it corresponds to Fig. 2
in the stamping of the disk.
Fig. 2 further shows a disk 36 after it has
heen chamfered at the inner periphery and at the outer
periphery thereof. The chamfering is achieved by the
use of a pair of dies 42 and 44 (Fig. 4), the dies -
having circular projections 46 which are triangular in
cross-section and which form chamfers 48 and 50 at the
inner and outer peripheries of the disk 36. These
chamfers are adjacent to chamfer rings 52 and 54. The
next sta~ping operation shown in Fig. 2 is for the
purpose of removing the chamfered ring 54. Fig. 3
shows the center hole 40 free of such ring 54.
The next stamping step occurs to separate the
disk itself from the chamfered ring 52, such ring being
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held by webs 38 to s~rip 16. The strip can then be
chopped into segments, such as along the line 45 (Fig.
2), to form scrap material which is taken out of the
stamping machine by way of a conveyor 47 and directed
into a bin 48. In such a case, the scrap material can
be reused or sold as scrap.
The disks 36 resulting from the stamping
operation are carried out of machine 30 by a conveyor
49 and directed into an abrasive or mechanical cleaner
50 where both faces of the disks are subjected to an
abrasive or mechanical cleaning treatment to remove
foreign material from the faces of the disks and to
reduce oxide coatings, if any, on the disks. The disks
36 are then moved by conveyor 52 out of cleaner 50 and
onto a conveyor system 54 where they are oriented in
vert~cal planes. While in this vertical orientation,
each disk becomes coupled to a moving hook 54 depending
from the rail 55 of a transfer system 56, each hook
having a lower end which is received in the center hole
40 of the corresponding disk 36, whereby the disk can
be lifted and caused to move along the serpentine path
of the rail 55.
Transfer system 56 delivers the disks 36 in a
serial fashion to a cleaning tank 60 having a number of
compartments 62, 64, 66 and 68, wherein different
cleaning solutions are located to progressively clean
the disks as they are lowered into each compartment,
then lifted up and then lowered into the successive
compartments. The cleaning solutions remove remaining
foreign materials and oxides from the disks. After the
disks are removed from tank 60, they pass through a
dryer 70 where they are dried while they are still
coupled to hooks 54. Then the disks are moved into a
de-greasing tank 72 and then out of the de-greasing
tank onto a transfer mechanism 74 where the disks are
separated in a suitable fashion from hooks 54. The
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hooks then return to a location near conve~or 54 (Fig.
lb) to pick up and transfer additional disks 36.
As conveyor 56 extends away from dryer 70,
the conveyor extends into one open rear side 71 (Fig.
lc) of a clean room section 73 defined by a top wall
75, a front wall 83 (~ig. ld), a bottom wall 77 and a
pair of spaced side walls 79. This clean room section
is constructed so that air flows out ~f the region 73
through the open side 71, the air flow being denoted by
the arrows 80. To this end, a blower 82 (Fig. ld) is
mounted on the upper wall 75 and blows air through
plenums 77 and then into louvered passages 79 in front
wall 83, whereby the air leaving the passages 79 is
substantially laminar flow toward, into and through
open end 71. Thus, the interior 73 of the clean room
cont~ining de-greasing tank 72 is substantially kept
free from any foreign matter entering the ciean room
which would otherwise tend to enter the clean room by
way of the open side 71.
The end wall 83 in which plenums 77 and
passages 79 are located has a port 84 through which
conveyor 74 extends. The conveyor includes a static
platform 86 and a reciprocal disk-advancing or feed
device 88 for supporting the disks 36 and for advancing
them one by one into an embossing press 90 which
contains the coining dies for coining the faces of the
disks. Press 90 is in a f~nal clean room section 92
which is enclosed by wall 83, top wall 94, end wall 96
(Fig. le) and bottom wall 98. The air flow through the
final clean room section 92 is from the louvered
passages 100 in top wall 94 and downwardly into a
porous floor 102 and into a plenum chamber 104 for flow
of the air to a recirculating plenum. The air flow is
directed from a blower 106 into and through passages
100 and downwardly into and through floor 102.
Press 90 can be of any suitable construction.
Typically, it can be one made by Minster Machine
~ J ~L~5~
Company in Minster, Ohio and known as a 1500 ton
knuckle joint embossing press. A machine of this type
can deliver up to 100 strokes per minute.
The feed device 88 for advancing disks 36
into embossing press 90 is a ladder mechanism operable
in cooperation with static platform 86, the platform
having a plurality of posts or spindles 87 thereon,
shown in Figs. ld and 5. Device 88 includes a pair of
spaced rails 90 and 92 which move axially and
transversely of their longitudinal axes. Each rail has
a plurality of fingers 94 thereon which engage the
outer peripheries of the various disks 36 and clamp the
disks between the rails. When the rails are lifted to
separate the disks from posts 87, the rails are shifted
axially to advance the disks incrementally, whereby the
disk~ are advanced successively into and through the
embossing press 90 where the disks are coined. The
ladder mechanism is conventional in construction and is
made by a number of different companies, including
Minster Machine Company of Minster, Ohio.
- The typical operation of the ladder mechanism
includes the steps of moving the rails 90 and 92 -
inwardly relative to and toward each other so that the
- fingers 94 grip the opposed side marginal edge portions
of the disks on first posts 87. Then, the rails are
lifted a slight amount to lift the disks off the posts.
Then the rails are advanced toward the machine 90 and
through a distance sufficient to align each disk with
the next adjacent, downstream post 87. Then the rails
are lowered, thereby lowering the disks on vertically
aligned posts therebeneath, following which the rails
are moved away from each other, separating the fingers
from con~act with the respective disks. Then the rails
are moved in the opposite direction to positions at
3S which the fingers 94 are again aligned with the next
adjacent disks 36. Then the process is repeated and
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proceeds at a rate correlated with the stroke rate of
embossing press 90.
As each disk 36 is advanced, there is one
disk 36 which is moved into the die zone 110 (Fig. 6)
of embossing press 9Q. The press has dies 112 and 114
mounted on reciprocal shafts 116 and 118, the shafts
having lower and upper ends, respectively, which are
chamfered to effectively receive the chamfered center
hole of each disk 36 aligned therewith. Dies 112 and
114 have die faces 120 and 122, respectively, for
engaging the opposed faces of the disk 36. The die
further has stop members 124 which limit the travel of
the die 112 toward die 114.
The downward movement of die 112 is stopped
by stop members 124 moving into engagement with each
othe~. When this occurs, the die faces engage the
faces of the disk 36, and the pressure exerted on the
disk faces is of the order of 1500 tons, depending upon
the size of the disk, causing a coining or cold flow of
the material of the disk, while the inner and outer
diameters of the disk are contained, rendering the
faces of the disk extremely smooth, flat and in
parallelism with each other. Embossing press 90
operates at a rate of approximately 100 strokes per
minute; thus, the transfer device 88 defined by the
ladder mechanism 90 operates at this same speed or
faster.
After each disk 36 is subjected to the -
contained, massive pressures of dies 112 and 114, the
disk is moved progressively toward an exit port 130 in
a side wall 131 of embossing press 90. The transfer
; device 88 advances each coined disk 36 to a tray
loading mechanism 132 for loading the coined disks in
trays 134 at a location adjacent to the side wall 131
of embossing press 90 near exit port 130 thereof. The
trays are directed into a final clean room through an
air lock 136 (Fig. le) by a conveyor 138 which carries
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the tray, with a lid 140 thereon, into a machine 142
within clean room section 92 which removes the lid from
the tray and uses that particular lid for covering a
full tray of coined disks on a second conveyor 144
which extends toward and through air lock 136.
Each tray 134 has grooves 150 therein for
receiving and supporting a stack of coined disks 36
arranged in vertical planes as shown ~y stack 152 (Fig.
7). Typically, there are 25 to 50 such disks 36 in a
10 tray 134. The incoming, empty trays 134 are directed
- to a first station adjacent to a loading mechanism 132,
whereupon a transfer member 154, which can be
.electrically, hydraulically or pneumatically actuated,
pushes an empty tray 134 into a position beneath and
adjacent to loading mechanism 132. Thus, an empty tray
will~be in position to receive coined disks one by one
in the slots or grooves 150 of the tray aligned with
and beneath mechanism 132.
Mechanism 132 includes a box-like housing 161
(Fig. 7) having a pair of opposed, parallel sides 156
mounted on a shaft 158 for rotation in the direction of
arrows 160. The housing has four sliding end walls 162 .
shiftably mounted on sides 156, each end wall 162
having an expandable mandrel 164 thereon which is
expanded by a mechanism (not shown) within housing 161
to grip and hold a coined disk 36 as housing 161 is
rotated in a clockwise direction when viewing Fig. 7
through an arc of approximately 90. When the housing
has rotated through such an angle, the corresponding
vertical end wall 162 having a coined disk on its
mandrel is allowed to move downwardly under the
influence of another means (not shown) within housing
161. Thls downward movement occurs until the coined
disk is inserted in a corresponding groove 150 of the
corresponding tray 134, whereupon the mandrel is
. contracted and the conveyor 144 is advanced in a
direction of arrow 147 (Fig. 7~ through a slight
5~ ~O
distance until the next groove 150 is aligned with the
downward path of travel of the next coined disk 36.
Then, before housing 161 is rotated again, the
downwardly extending end wall 162 is elevated,
following which the housing 161 is rotated once again,
all of which occurs or will occur after transfer device
88 has deposited a disk 36 on the mandrel 164 of the
topmost end wall 162.
The process continues until a tray 134 has
been filled and the tray has moved out from beneath
housing 161. Transfer member 154 is then energized to
push the next available empty tray 134 into a position
beneath and vertically aligned with the housing 161.
The full tray moves away from loading mechanism 88 and
into and through the machine 142, where it receives a
lid ~40 taken from an empty tray traveling in the
opposite direction toward zone 135. The machine 142
can be of any suitable construction, such as a vacuum
lift including a piston and cylinder assembly 149 and a
control mechanism (not shown) for actuating assembly
149 to lift off, by suction or otherwise, the lid 140
from an incoming tray and placing the lid on an
outgoing, full tray.
Conveyors 138 and 144 work intermittently and
extend through the air lock 136. The air lock has an
entry gate 163 and an exit gate 165 with reference to
the direction of movement of the incoming empty trays.
The gates are operated by fluid piston and cylinder
assemblies 167 and 169 operated by control means (not
shown) which are pre-programmed in accordance with the
rate of coining of embossing press 90 and the
incremental advancement of conveyors 138 and 144.
~ After the full trays have been passed out of
the apparatus through airlock 136, the coined substrate
disks in the full trays are not exposed in any way to
the ambient atmosphere. They are taken to a job site
and into clean rooms for receiving coatings on the
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disks to form the storage media for which the
substrates are designed.
Fig. 8 shows a completed disk with a layer
170 of material thereon, such material being sufficient
to provi~e a storage capability for the dis~. For
purposes of illustration, the coating is a magnetic
coating which is applied in any conventional manner.
,. ~ , .. ... . .
The coat material could also be suitable for optical
recording as well as audio, video and computer
io recording.
}n operation, apparatus 10 is first provided
with a roll 14 of material, such as aluminum or
aluminum alloy, in strip form. The strip 16 is then
initially fed into the straightener machine 20, then
through the press machine 25 where the thickness of the
stri~ 16 is controlled within a tolerance range of
~.0001 inch. The strip is then fed through the
blanking machine 30 in which the individual disks 36
are formed, the scrap from the blanking or stamping
operation being directed into a bin 48 for reuse or for
sale.
The disks 36 are then moved into and through
the cleaning machine 50, then out of the machine and
into coupled relationship with hooks 54 on conveyor 56.
25 The disks are then directed into the various ;
compartments of cleaning tank 60, then out of the tank,
through dryer 70, and then into de-greasing tank 72 for
the purpose of cleaning the disks prior to their being
coined in embossing press 90.
The disks are then separated from hooks 54
and then become coupled to the transfer device 88 for
transit successively into, through and out of embossing
press 90 in which the disks are coined. Fig. 6
illustrates the way in which the dies 112 and 114 are
shifted relative to each other and into engagement with
the opposed faces of the disks 36 to coin them. The
pressure exerted by press 90 is of the order of 1500
~ S~ 3~ (
tons, depending upon the size of the disk, to effect a
flow of the material on the faces thereof so that the
faces become extremely smooth, flat and parallel with
each other, free of flaws and ready to be coated with a
material for making the disks substrates of high
quality for use in making rigid sto.age media.
As soon as the disks are coined, they are
moved out of press 90 by transfer mechanism 88 and
become coupled with transfer mechanism 132 so that the
coined disks are fed one by one into a tray 134 below
mechanism 132 and movable by conveyors 138 and 144.
The coined disks eventually fill each tray and the full
trays are moved incrementally by conveyor 144 through
machine 142 where the full tray receives a lid and then
is moved out of the final clean room 92 through an air
lock ~36 and then to a location at which the encased
coined disks are stored or put into actual use.
The present invention provides for the
economical and high yield manufacture of high quality
substrates for use as data storage media by coining.
The invention further includes apparatus and a method
for making the substrate. The substrates made in
accordance with the teachings of the present invention
have uniform part-to-part dimensions and consistent
geometries, including uniformity of surface texture,
parallelism of the faces of the substrate and flatness
of such faces. The substrates of the present invention
are virtually free of all flaws typically found in
substrates produced by diamond-turning and abrasive
machining. Thus, the substrate of the present
invention improves both product quality and thereby
minimizes the amount and degree of inspection tests
following manufacture. The substrate of the present
invention can aIso be provided with any desired surface
finish, texture, lay or form. This feature could
include but is not limited to cross-hatch, radial,
circumferential and random lays. This is achieved by
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5~3
18
selecting the desired finish, texture, lay or form of
the die faces which contact the faces of each disk 36
in the manner shown in Fig. 6.
The substrate of the present invention
eliminates the problem of asymmetrical stresses
associated with other substrate fabrication techniques.
The substrate of the pre~ent invention is symmetrical
throughout its entirety, is symmetrically pre-stressed,
and is stronger and more dimensionally stable and has
greater structural integrity than those conventionally
machined from solid parts. The substrate of the
present invention ~urther exhibits sub-micron flatness
and smoothness and has exceptional axial acceleration
characteristics in dynamic functions.
The substrate of the present invention can be
prod~ced from high purity, corrosion-resistant aluminum
materials (al-clad) that are not adaptable to
conventional fabrication techniques. Moreover, the
substrate of the present invention is made such that it
needs only a minimum amount of nickel undercoating
currently required in post-processing of conventional
substrates. The substrate of the present invention can
be thinner than conventionally produced substrates and
still be a high quality product.
The substrate of the present invention can be
produced at much greater production rates per
manufacturing station than conventionally produced
substrates. At their maximum yield rates, conventional
techniques provide for maximum production rates at best
of no more than lO0 to 125 substrates per hour. In
contrast, the present invention, when in operation, can
produce as many as 4800 to 6000 substrates per hour so
as to have a throughput over 40 times as fast as
conventional techniques. Moreover, the present
invention provides higher manufacturing yields than is
capable with conventional techniques of producing
substrates.
~. .
r ~. 5~
19
The substrate made in accordance with the
present invention improves yields in post-processing
media applications and in disk drive assembly and
qualification.
The coined substrate of the present invention
minimizes the effect of impurities of the malleable
material on surface finish and product functionality.
Less scrap material is generated and fewer production
and inspection operations are necessary in the
manufacture and quality control of the substrate of the
present invention.
The substrate of this invention can be
fabricated with special features, such as index and
timing marks and integral spacer rings 200 (Fig. 8)
which simplify the disk drive assembly process by
reducing the number of parts and part interfaces,
thereby minimizing tolerance build up. The substrate
of this invention can use a number of different
preforms including blanked, forged, extruded, sintered
2~ and rolled material forms. Thé substrate can be
fabricated by the use of compensated dies that account
for the expansion charact~ristics of given materials.
The substrate can be fabricated with precision chamfers
and other unique features, including tapered substrates
for low inertia systems.
