Information
-
Patent Grant
-
6283838
-
Patent Number
6,283,838
-
Date Filed
Tuesday, October 19, 199924 years ago
-
Date Issued
Tuesday, September 4, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Skjerven Morrill MacPherson LLP
- Steuber; David E.
- Halbert; Michael J.
-
CPC
-
US Classifications
Field of Search
US
- 451 63
- 451 173
- 451 168
- 451 302
- 451 307
- 029 9001
-
International Classifications
-
Abstract
A burnishing tape apparatus includes pads that press the burnishing tape against the surfaces of the disk to be burnished. The pads are mounted on pad holders that are biased to press the pads against both sides of the disk. Tape guides are used to apply tension to the burnishing pad when the pads are moved away from the disk. When the pads are away from the disk tape guides hold the burnishing tape away from the pads so that the burnishing tape may be indexed without damaging or dislodging the pads. As the pads are moved into contact with the disk, the tape guides release the tension on the burnishing tape while the centering guides ensure that the burnishing tape is centered on the pads. By releasing tension on the burnishing tape, the pads are permitted to press the approximate center of the burnishing tape against the surfaces of the disk without deforming in an uncontrolled manner.
Description
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for burnishing the surfaces of a disk, and more specifically burnishing the surfaces of a disk with burnishing tape and pads.
BACKGROUND
Magnetic memory disks, such as the type typically used in a computer hard drive, have a smooth surface over which the read/write head flies during operation. The trend has been to reduce the fly height of the read/write head over the surface of the disk to increase the data recording density on the disk. While it is desirable for a read/write head to fly as close as possible to the surface of the disk, it is important that the read/write head does not contact the disk or defects on the surface of the disk. A defect on the surface of the disk that physically contacts the read/write head may damage the read/write head, the disk, or both. Consequently, care must be taken during the disk processing and testing to assure that there are no defects on the surface of the disk that are greater than the fly height of the read/write head, which today is approximately 1 μ″ (microinch) or less.
Typical magnetic disks include an aluminum, glass, or silicon substrate that is plated with a NiP (nickel phosphate) layer and then textured, e.g., for the contact start stop zone. An underlayer of Cr (chromium) or NiP is sputtered on the plated NiP layer, a thin film of magnetic recording material, typically a Co (cobalt) alloy, is sputtered on the underlayer, followed by the deposition of a protective coating and a lubrication layer. The disk is then burnished to remove any asperities prior to testing the disk to assure the disk meets the required surface specifications. Presently, some magnetic disks are specified to have a roughness less than or equal to about 30 angstroms (3 nanometers).
In conventional methods of burnishing the surfaces of a disk, an abrasive burnishing tape is used. Prior art devices for burnishing a disk with an abrasive tape include the use of air knives and rollers and in some instances the combination of the two. A disadvantage with the use of air knives and rollers is that it is difficult to control the force used to press the burnishing tape against the disk and to ensure that an equal amount of force is applied to both sides of the disk. Without precise control of the force applied to both sides of the disk, one side of the disk may be burnished more than the other. Further, if one side of the disk has a much greater force applied to it than the other, the disk may be damaged. In addition, with air knives it is difficult to control the precise area of the burnishing tape that is pressed against the disk. It is also difficult to burnish with an adequate amount of force without scratching the surface of the disk. Further, rollers are difficult to keep flat against the surface of the disk.
SUMMARY
A burnishing head in accordance with an embodiment of the present invention includes burnishing pads that press a burnishing tape against the surfaces of a disk. The pads are mounted on pad holders that move to press the burnishing tape against the surfaces of the disk with the pads. The burnishing apparatus also includes tape guides that hold the burnishing tape away from the pads when the pads are not pressed against the surfaces of the disk. With the burnishing tape separated from the pads, the burnishing tape may be indexed without damaging or dislodging the pads from the pad holders. As the pad holders move the pads away from the disk, the tape guides apply tension to the burnishing tape used to keep the burnishing tape from contacting the pads. As the pad holders move the pads into contact with the disk, the tape guides release tension on the burnishing tape to prevent uncontrolled deformation of the pads. Consequently, the entire footprint of each pad is used to press the burnishing tape into contact with the surfaces of the disk.
The burnishing apparatus operates by mounting a disk on a disk handling apparatus, such as a motor driven spindle. The disk is then moved between the pads of the burnishing apparatus. As the pads are moved to press the burnishing tape against the surfaces of the disk, the tape guides release tension on the burnishing tape. Because there is little or no tension on the burnishing tape during the burnishing process, the entire footprint of the pads press the burnishing tape against the surfaces of the disk.
Once the disk is burnished, the pad holders are separated, e.g., by way of a pneumatic actuator or a stepper motor. As the pads are moved away from the surface of the disk, tension is applied to the burnishing tape. The burnishing tape is held away from the pads as the burnishing tape is indexed. Additionally, the disk is removed from between the burnishing pads, and the disk is replaced with the next disk to be burnished. The next disk is then moved between the pads, which then are moved to press an unused portion of the burnishing tape into contact with the surfaces of the next dish.
In accordance with another embodiment of the present invention, the pads are mounted on pad holders that are coupled together with a tension spring. The tension spring biases the pad holders together such that the pads automatically press against the surfaces of the disk with an equal amount of force. The pad holders are slidably mounted on a rail which permits the pad holders to slide away from and toward each other. The pad holders have the freedom to slide in unison so that when the pads are pressed against the surfaces of the disk, the pads automatically align with the center of the disk. A separating mechanism, such as a pneumatic actuator, is used to overcome the bias of the spring and to move the pads away from the disk, for example, when the disk is being replaced and the burnishing tape is indexed.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying figures, where:
FIG. 1
is a top view of a disk being burnished by a burnishing apparatus in accordance with an embodiment of the present invention;
FIG. 2
shows a top plan view of the disk mounted on spindle with a pad pressing a portion of burnishing tape against the surface of the disk;
FIG. 3
shows a side view of the burnishing apparatus with pads, mounted on pad holders, positioned such that the pads are not in contact with the disk;
FIG. 4
shows a side view of the burnishing apparatus with pads, mounted on pad holders, positioned such that the pads are in contact with the disk;
FIG. 5
is a simplified top view of the burnishing apparatus along dimensions A—A illustrated in
FIG. 3
;
FIG. 6
is a simplified top view of the burnishing apparatus along dimensions B—B illustrated in
FIG. 4
;
FIGS. 7A
,
7
B,
7
C are detailed top, side and front views, respectively, of burnishing apparatus;
FIG. 8
shows an exploded perspective view of the burnishing apparatus;
FIGS. 9A and 9B
show respective side and top views of an upper tape tracking assembly with an intermediate arm upon which are mounted centering guides;
FIG. 10
shows a cut-away side view of a supply reel with a spring loaded mechanism to adjust the resistance of the rotation of supply reel;
FIG. 11
shows a perspective view of a pad holder with a removable tip;
FIGS. 12A and 12B
show side and top views, respectively, of the pad holder shown in
FIG. 11
;
FIG. 13
is a perspective view of a burnishing apparatus in accordance with another embodiment of the present invention with the pads mounted on scissor-like pad holders;
FIGS. 14 and 15
are respective top plan and front views of opposing pad holders used in the burnishing apparatus shown in
FIG. 13
;
FIG. 16
shows a top plan view of one pad holder;
FIG. 17
shows the apparatus used to open and close the pad holders;
FIGS. 18 and 19
show a top plan view and a front end view, respectively, of the swing arms used to release and provide tension on the burnishing tape;
FIGS. 20 and 21
show a simplified top plan view of burnishing apparatus
300
in a closed and an open position, respectively;
FIG. 22
shows a side view of a motor driven takeup reel;
FIGS. 23A and 23B
show a front view and a side view, respectively, of a motor driven of capstan rollers used to index the burnishing tape; and
FIG. 24
is a side view of an index guide and sensor used to detect the amount that the burnishing tape has been indexed.
DETAILED DESCRIPTION
FIG. 1
is a top view of a magnetic disk
101
being burnished by a burnishing apparatus
100
in accordance with an embodiment of the present invention. The burnishing apparatus
100
uses burnishing pads
106
and
108
to press a burnishing tape (not shown in
FIG. 1
) against the surfaces of a magnetic disk
101
while magnetic disk
101
rotates about a spindle
102
as indicated by arrow
102
a
. As can be seen, burnishing pads
106
and
108
are static, non-rolling pads. Disk
101
is shown in a side view in FIG.
1
. Burnishing apparatus
100
may be used to burnish not only magnetic disks, but any other disk, including, e.g., optical or magneto-optical disks.
Disk
101
is shown mounted on disk handling hardware including a spindle
102
that is driven by a motor
103
to rotate disk
101
at high speed, e.g., 500 inches per second (ips). The angular velocity, however, may range from 300 ips to 1000 ips, depending on the amount of burnishing desired and the length of processing time, i.e., the higher the angular velocity of disk
101
, the shorter the processing time, but less burnishing will occur. In some embodiments, a constant linear velocity (CLV) may be used that vary from, e.g., 30 meters/minute to 300 meters/minute.
As disk
101
rotates, a burnishing surface of an abrasive burnishing tape is brought into contact with disk
101
. Burnishing tape is pressed against both surfaces
104
,
105
of disk
101
by pads
106
and
108
, respectively, to burnish surfaces
104
,
105
. While disk
101
rotates about spindle
102
, disk
101
, spindle
102
and motor
103
are moved in a lateral direction, as illustrated by arrow
107
, such that approximately the entire area of surfaces
104
,
105
of disk
101
, from the inside diameter to the outside diameter or vice versa, may be brought into contact with the burnishing tape and thereby burnished.
Once the burnishing of disk
101
is complete, disk
101
, spindle
102
and motor
103
are moved away from burnishing apparatus
100
, the rotation of disk
101
is stopped and disk
101
is removed from spindle
102
. By moving disk
101
away from burnishing apparatus
100
, disk
101
may be easily removed from spindle
102
. A new disk to be burnished is then mounted on spindle
102
. The rotation of the new disk is initiated and the new disk and spindle
102
are moved laterally between burnishing pads
106
and
108
to be burnished. It should be understood the lateral movement between disk
101
and burnishing apparatus
100
is relative. Thus, if desired, burnishing apparatus
100
may be moved laterally while disk
101
, spindle
102
and motor
103
are held stationary as disk
101
rotates about spindle
102
.
Pads
106
,
108
are mounted on pad holders
110
,
112
, respectively, which are mounted on respective carriages
114
,
116
. Carriages
114
,
116
are mounted on a rail
118
. It should be understood that if desired pad holders
110
,
112
may be mounted on rail
118
without intervening carriages
114
,
116
. Thus, carriages
114
,
116
actually function as an extension of pad holders
110
,
112
that is mounted on rail
118
and therefore may be considered part of pad holders
110
,
112
. Rail
118
is, e.g., a ball bearing linear slide rail or any other type of device that will permit carriages
114
,
116
to move linearly back and forth perpendicular to the plane of disk
101
with little friction. A tension spring
122
connected between carriage
114
and carriage
116
is used to bias pads
106
and
108
together. Thus, as illustrated by arrows
115
and
117
, respectively, carriages
114
,
116
along with pad holders
110
,
112
and pads
106
,
108
move towards disk
101
to press pads
106
,
108
against disk
101
, i.e., in a “closed position,” as shown in FIG.
1
. Of course, during burnishing operations a burnishing tape is placed between burnishing pads
106
and
108
and sides
104
and
105
, respectively. Rail
118
includes an inlet connector
120
for an air supply that is used to pneumatically separate carriages
114
,
116
. Thus, as illustrated by arrows
115
and
117
, respectively, carriages
114
,
116
along with pad holders
110
,
112
and pads
106
,
108
may be moved away from disk into an “open position.” Of course, carriages
114
,
116
need not be separated pneumatically, but may be separated by any desired manner to place pads
106
,
108
into an open position.
With the use of tension spring
122
coupled to carriages
114
,
116
, pads
106
and
108
are biased together. Consequently, an equal amount of pressure is applied to surfaces
104
,
105
of disk
101
. By applying the same amount of pressure on surfaces
104
and
105
with pads
106
and
108
, respectively, surfaces
104
and
105
will receive the same amount of burnishing. In addition, the equal application of pressure by pads
106
,
108
results in no net force being applied to disk
101
thereby avoiding damage to disk
101
.
Moreover, carriages
114
,
116
are mounted on rail
118
such that carriages
114
,
116
float, i.e., carriages
114
,
116
move together in unison as illustrated by arrow
119
. Because carriages
114
,
116
move together in unison, pads
106
,
108
will be centered on disk
101
. Thus, carriages
114
and
116
are automatically aligned with disk
101
, thereby avoiding damage to disk
101
when pads
106
,
108
are placed in contact with disk
101
. Carriages
114
and
116
have approximately 0.250″ of float or movement that accommodates any non-centered condition of disk
101
and will thereby maintain equal pressure on surfaces
104
and
105
. Thus, if disk
101
is not centered, carriages
114
and
116
will move together to place disk
101
in the center of pads
106
and
108
.
FIG. 2
shows a top plan view of disk
101
mounted on spindle
102
with pad
106
pressing a portion of burnishing tape
126
against surface
104
. In accordance with one embodiment of the present invention, burnishing tape
126
extends tangentially over disk
101
, as shown in FIG.
2
. Thus, as pad
106
presses burnishing tape
126
against surface
104
, the edges of burnishing tape
126
will not contact disk
101
. Consequently, the edges of burnishing tape
126
will not scratch or otherwise damage disk
101
. In addition, burnishing tape
126
has enough surface tension that when pad
106
presses tape
126
against surface
104
, the only portion of tape
126
that contacts surface
104
is below the footprint of pad
106
. By ensuring that only the portion of burnishing tape
126
that is below the footprint of pad
106
is in contact with surface
104
, the amount of burnishing by tape
126
may be precisely controlled, e.g., by changing the pad size. It should be understood that another burnishing tape is similarly pressed into contact with surface
105
by pad
108
, but is hidden from view in FIG.
2
.
Burnishing tape
126
may be any tape with an appropriate roughness to burnish disk
101
. One example of burnishing tape
126
is 1 micron Alumina manufactured by Mypox of Japan.
Pads
106
,
108
may be any soft material, such as neoprene rubber, that is deformable during use and preferably has anti-static properties. Pads
106
,
108
are approximately 5 mm×12 mm or 5 mm×10 mm, with a thickness of 2.5 mm. An example of a material that may be used as pads
106
,
108
is the neoprene rubber material model number 4701-40, formerly manufactured by Rubitex of Texas.
FIGS. 3 and 4
show front views of burnishing apparatus
100
with pads
106
,
108
in the “open position” (i.e., not in contact with disk
101
) and in the “closed position” (i.e., pressing against disk
101
), respectively. As shown in
FIGS. 3 and 4
, burnishing apparatus
100
also includes tape handling hardware, which generates the desired tension in the burnishing tape while pads
106
,
108
are in the open and closed positions.
FIGS. 3 and 4
do not show carriages
114
,
116
, tension spring
122
, or rail
118
for the sake of clarity.
FIG. 3
shows pads
106
and
108
, mounted on respective pad holders
110
and
112
, in the open position. Burnishing tapes
126
and
128
extend from respective supply reels
130
,
132
to respective take-up reels
134
,
136
. For the sake of clarity and simplicity, the path of burnishing tape
126
will be described with the understanding that the path of burnishing tape
128
is the same but in mirror image.
Burnishing tape
126
extends over rollers
138
,
140
, and
142
, which are mounted on an upper tape tracking assembly
144
. Burnishing tape
126
extends around a first tape guide roller
146
, over two centering guides
148
and
150
and around a second tape guide roller
152
. Tape guide rollers
146
,
152
are mounted on pad holder
110
, while centering guides
148
,
150
are mounted on arms
154
,
156
, respectively, which are connected to upper tape tracking assembly
144
via an intermediate arm
158
. Burnishing tape
126
then continues through a tape guide
160
, around a capstan assembly with rollers
162
and
164
and is received by take-up reel
134
.
The upper tape tracking assembly
144
and centering guides
148
,
150
, along with the various associated arms, are held in a fixed position. Pad holder
110
with pad
106
, however, is not fixed, and may move laterally as illustrated by arrow
166
so that pad
106
may be placed into a closed position, as shown in
FIG. 4
, or an open position as shown in FIG.
3
.
FIG. 4
shows burnishing apparatus with pads
106
and
108
in a closed position pressing against disk
101
. As can be seen in
FIG. 4
, pad holder
110
has moved toward disk
101
relative to centering guides
148
,
150
.
FIG. 5
is a simplified top view of burnishing apparatus
100
in an open position shown along dimensions A—A as illustrated in FIG.
3
.
FIG. 6
is a simplified top view of burnishing apparatus
100
in a closed position shown along dimensions B—B as illustrated in FIG.
4
.
FIGS. 5 and 6
show pad holder
110
,
112
mounted on carriages
114
,
116
, which are mounted on rail
118
. Also shown in
FIGS. 5 and 6
is the spring
122
biasing pad holders
110
and
112
together. Burnishing tapes
126
and
128
and part of the tape handling hardware, i.e., supply reel
130
, upper tape tracking assembly
144
, tape guide
160
, rollers
162
,
164
and take-up reel
134
, are not shown in
FIGS. 5 and 6
for the sake of clarity.
As illustrated in
FIGS. 3 and 5
, when pad holder
110
is in an open position, pad
106
does not contact burnishing tape
126
. As discussed above, pad holder
110
is pneumatically forced into an open position. When placed in an open position, pad holder
110
is moved away from disk
101
by an amount sufficient to ensure that pad
106
does not contact burnishing tape
126
and to cause tape guide rollers
146
,
152
to press against tape
126
applying tension to tape
126
. Pad holder
110
may move approximately 0.250″ to 0.375″ when transitioning from a closed position (with pads
106
and
108
in contact with disk
101
) to an open position. When in an open position, pad
106
is approximately 1 mm away from burnishing tape
126
. Centering guides
148
,
150
, which are held stationary relative to pad holder
110
, hold burnishing tape
126
away from pad
106
. With pad holder
110
in the open position, disk
101
is moved from between pads
106
and
108
. Disk
101
may then be removed and replaced with another disk to be burnished. Meanwhile, tape
126
is indexed so that an unused portion of burnishing tape
126
is placed in front of pad
106
. Because centering guides
148
,
150
hold burnishing tape
126
away from pad
106
while tape
126
is indexed, burnishing tape
126
may be advanced without damaging or dislodging pad
106
. Consequently, the life of pad
106
is increased. When pad holder
110
is placed in a closed position (as shown in
FIGS. 4 and 6
) an unused portion of burnishing tape
126
will be between pad
106
and disk
101
.
A motor (not shown) connected to take-up reel
134
rotates take-up reel
134
by the appropriate amount to index the burnishing tape
126
. In addition, the capstan assembly, shown as rollers
162
and
164
in
FIG. 3
, may be driven by a motor to index the burnishing tape. A spring on the supply reel
130
provides the appropriate amount of resistance in the rotation of supply reel
130
to maintain tension on tape
126
as the motor driven take-up reel
134
indexes tape
126
. Supply reel
130
is discussed in more detail in reference to FIG.
10
.
Pad holder
110
is placed in a closed position by decreasing the pneumatic force below the bias force of tension spring
122
(shown in FIGS.
5
and
6
). Thus, pad holder
110
along with tape guide rollers
146
,
152
moves toward disk
101
into the closed position (shown in FIG.
4
and
6
). Because tape guide rollers
146
,
152
move toward disk
101
when in the closed position, tension that was applied by tape guide rollers
146
,
152
when in the open position is relieved. There is little or no tension applied to burnishing tape
126
when the burnishing pads are pressed against the disk, as illustrated in FIG.
4
. Consequently, when pad
106
presses burnishing tape
126
against surface
104
of disk
101
, pad
106
will not be deformed from tension on burnishing tape
126
. Thus, burnishing tape
126
is pressed against disk
101
by the entire surface area of pad
106
. If there is tension on burnishing tape
126
as pad
106
presses against disk
101
, the corners and sides of pad
106
would be deformed by tape
126
causing only a central portion of the surface area of pad
106
to press tape
126
against disk
101
. This would cause a loss of efficiency in the burnishing of disk
101
, as well as less control over the equalization of burnishing on both sides of disk
101
.
In addition, as pad holder
110
moves forward toward disk
101
, centering guides
148
,
150
center burnishing tape
126
with respect to pad
106
. The flanges on centering guides
148
,
150
and the flanges on tape guide rollers
146
,
152
hold tape
126
such that it is centered on pad
106
as pad holder
110
moves into the closed position. Thus, when pad
106
makes contact with burnishing tape
126
, pad
106
is centered on the tape
126
.
FIGS. 7A
,
7
B,
7
C are detailed top, side and front views, respectively of burnishing apparatus
100
without burnishing tape
126
,
128
, arms
154
,
156
or centering guides
148
,
150
. As shown in
FIGS. 7A
,
7
B, and
7
C, rail
118
is connected to a pneumatic apparatus
169
for opening pad holders
110
,
112
. of course any other means for opening pad holders
110
,
112
may be used. Pneumatic apparatus
169
is a conventional pneumatic rotary cylinder, such as Model P/N manufactured by Shunck Corporation.
FIG. 8
shows an exploded perspective view of burnishing apparatus
100
where only one side of burnishing apparatus
100
is illustrated for the sake of clarity.
FIG. 8
also shows the tape handling mechanism.
As shown in
FIG. 8
, burnishing apparatus
100
includes pad holder
110
upon which are mounted tape guide rollers
146
and
152
. Pad holder
110
includes a depression
113
in which pad
106
is mounted. Pad
106
may be mounted using a rubber based glue such as BHE Adhesive or High Strength 90 Adhesive manufactured by 3M. Of course, pad
110
may use any mounting surface and does not necessarily require a depression. Pad
106
is not shown mounted on pad holder
110
in
FIG. 7
for the sake of clarity. Pad holder
110
is mounted on carriage
114
with pin
115
passing through a central orifice
111
in pad holder
110
. It should be understood that if desired, carriage
114
and pad holder
110
may be one unit. Thus, one unit may serve as both pad holder
110
and carriage
114
. A bolt (not shown) may be used to tighten pad holder
110
on pin
115
. Also mounted on carriage
114
is a spring tension arm
170
upon which is mounted tension spring
122
via bolt
123
. Tension spring
122
is also mounted on the complementary spring tension arm on the other pad holder
110
. Tension spring
122
is, e.g., part number 185-A spring manufactured by Century of Los Angeles, Calif. When in the closed position, spring
122
provides a force of approximately 100 grams.
Centering guides
148
,
150
are mounted onto arms
154
,
156
via pins
149
,
151
, respectively. Pins
149
,
151
may serve as axes about which centering guides
148
,
150
rotate or, alternatively, may simply hold centering guides
148
,
150
which do not rotate. Centering guides
148
,
150
may be manufactured from Teflon or other similar material. Arms
154
,
156
are mounted on an intermediate arm
158
. Arms
154
,
156
may of course be mounted on any element that is stationary relative to the movement of pad holder
110
, such as a wall.
Intermediate arm
158
is mounted to upper tape tracking assembly
144
, which is mounted on back plate
143
with guide pin
145
.
FIGS. 9A and 9B
show respective side and top views of upper tape tracking assembly along with intermediate arm
158
and centering guides
148
,
150
. As shown in
FIG. 9A
, centering guides
148
and
150
include flanges
148
A and
150
A, respectively to ensure that the burnishing tape
126
is maintained centered on pad
106
.
The upper tape tracking assembly
144
and centering guides
148
,
150
along with the arms
154
,
156
, and
158
are held in a fixed position, while carriage
114
with pad holder
110
is permitted to slide on rail
118
(not shown in FIG.
8
).
Take-up reel
134
with cover
134
a
is driven by motor
172
. Supply reel
130
with cover
130
a
is spring loaded to provide a desired amount of resistance when indexing the burnishing tape
126
.
FIG. 10
shows a cut-away side view of supply reel
130
with a spring loaded mechanism to provide resistance to the rotation of supply reel
130
. Supply reel
130
is mounted on bearings
180
a
,
180
b
, and
182
, which are mounted on axis
184
. A spring
186
is pressed against supply reel
130
via a washer
188
. A nut
190
may be tightened on a bolt
192
, which is coupled to axis
184
to adjust the force with which spring
186
is pressed against supply reel
130
. Washers
194
and
196
are used to center spring
186
on nut
190
. Thus, by adjusting nut
190
the resistance in the rotation of supply reel
130
may be adjusted to the desired amount, e.g., 100 grams.
The force applied by tension spring
122
may be adjusted by adjusting the distance between the tension arms on the pad holders
110
and
112
. Further, the tension on the burnishing tape
126
may be adjusted by altering the position of tape guides
146
and
152
relative to the position of the pads
106
and
108
. By moving tape guides
146
and
152
away from disk
101
, tension on burnishing tape
126
will be increased, while moving tape guides
146
and
152
towards disk
101
will decrease the tension on burnishing tape
126
.
The force applied by tension spring
122
and the tension on burnishing tape
126
is calibrated by burnishing a test disk. Ink, e.g., from a felt tip marker, or some similar substance is applied to the test disk prior to burnishing the test disk. The ink is transferred to the burnishing tape during the burnishing process. Thus, by inspection of the burnishing tape after burnishing the marked test disk, one can determined whether the pad is square to the surface of the disk. A square pad print on the burnishing tape indicates that the pad is square to the disk.
FIG. 11
shows a perspective view of a pad holder
210
in accordance with another embodiment of the present invention. Pad holder
210
is similar to pad holder
110
(
FIG. 8
) like designated elements being the same, however, pad holder
210
includes a main body
211
on which is mounted a removable tip
212
. Tip
212
includes a depression
214
in which pad
106
is mounted. Tip
212
also includes a central orifice
213
that is aligned with orifice
111
when tip
212
is mounted on pad holder
210
.
Tip
212
is mounted on body
211
of pad holder
210
with a bolt
215
. The use of a removable tip
212
permits pad
106
to be replaced with a new pad without requiring the disassembly of burnishing apparatus
100
. Advantageously, with the use of tip
212
, pad
106
can be replaced by simply removing tip
212
. A new pad may then be mounted on tip
212
, which is then remounted on body
211
or a new tip, upon which a new pad is mounted, may then be mounted on body
211
of pad holder
210
.
FIGS. 12A and 12B
show side and top views, respectively of pad holder
210
. As shown in
FIGS. 12A and 12B
, tape guide rollers
146
and
152
include flanges
146
A and
152
A, which assist in maintaining the correct position of burnishing tape
126
(shown in FIGS.
3
and
4
). Tape guide rollers
146
and
152
are mounted on the body
211
of pad holder
210
via bolts
216
and
218
, respectively, along with respective spacers
220
and
222
. Spacers
220
and
222
ensure that tape guide rollers
146
and
152
are at the correct position relative to pad
106
(shown in
FIGS. 3 and 4
) as well as permitting rotation of tape guide rollers
146
and
152
. It should be understood that tape guide rollers
146
and
152
may be mounted on pad holder
110
(shown in
FIGS. 3 and 4
) in a similar manner.
FIG. 13
is a perspective view of a burnishing apparatus
300
in accordance with another embodiment of the present invention. The pad holders on burnishing apparatus
300
are opposing scissor-like pad arms
302
, on which are mounted burnishing pads
304
. Burnishing apparatus
300
also includes swing arms
306
, which provide tension on burnishing tape (not shown for the sake of clarity) when the tape is to be indexed. Burnishing apparatus
300
also includes supply reels
310
and take-up reels
312
, which are similar to the supply reels and take-up reels described above. A series of rollers
314
,
316
,
318
, capstan rollers
320
,
321
and index guides
322
are also included in burnishing apparatus
300
. A base plate
324
is also provided, which advantageously separates motors (e.g., used with the take-up reels
312
) and moving parts from the burnishing area near burnishing pads
302
.
Burnishing apparatus
300
operates in a manner similar to burnishing apparatus
100
described above. Burnishing apparatus
300
, however, does not use pad holders that move on a linear slide rail, such as the type manufactured by Del-Tron part number 101x, but uses scissor-like pad arms
302
as pad holders that have a rotational movement.
FIGS. 14 and 15
are respective top plan and front views of opposing pad arms
302
. Pad arms
302
are mounted on bearings
330
at approximately the center of mass. Pad arms
302
are preferably balanced at the point of rotation at bearings
330
. Bearings
330
include a housing
332
that is attached to a pad arm plate
334
by pins and/or bolts
336
or any other appropriate method. Thus, pad arms
302
swing open and closed, i.e., respectively away and towards each other, as indicated by arrows
338
.
Dead weights
340
, shown in
FIG. 15
, are coupled to one end of pad arms
302
via dead weight rollers
342
, which are mounted on pad arm plate
334
. Pad arm plate
334
is mounted above base plate
324
by a support
344
. Dead weights
340
hang by a cable
341
below base plate
324
, as shown in FIG.
15
. Dead weights
340
bias pad arms
302
into a closed position, i.e., pads
304
are biased together. Because pad arms
302
are balanced at the point of rotation at bearings
330
, the force with which pads
304
are biased together can be carefully controlled. Thus, for example, a fifty gram dead weight
340
(including the weight of cable
341
) will supply a
50
gram bias force on pads
304
. When pad arms
302
are in a closed position, pads
304
press a burnishing tape against the surfaces of a disk.
Pad arms
302
also include extensions
346
, which extend below pad arm plate
334
through holes
347
. Extensions
346
are used to open pad arms
302
and to permit pad arms
302
to close in a controlled fashion as will be described in more detail below in reference to FIG.
17
. Extensions
346
may be integrally formed as part of arms
302
or may be a separate element that is mounted on arms
302
.
In one embodiment of the present invention, housing
332
may be adjusted inward and outward as indicated by arrows
331
, for example by adjustment screws. Thus, distance between pad arms
302
may be adjusted to compensate for variations in the thickness of the disk being burnished, e.g., when different types of disks are being burnished. Further, if the size or shape of the burnishing pad
304
varies, the distance between pad arms
302
may be adjusted accordingly. In another embodiment, both housings
332
may be placed on a linear slide and coupled together with a spring that provides less force than dead weights
340
. Thus, arms
302
and pads
304
will be automatically biased together to provide equal pressure on both sides of a disk and will be automatically centered on the disk.
FIG. 16
shows a top plan view of one pad arm
302
. Pad arm
302
includes a notch
350
at one end of the arm
302
into which a burnishing pad
304
is mounted. Notch
350
is approximately 0.3 inches deep. Burnishing pad
304
is mounted to pad arm
302
by inserting burnishing pad
304
into notch
350
and inserting a pin
351
(shown in
FIG. 13
) through the pad arm
302
and into burnishing pad
304
. Thus, burnishing pad
304
may be easily replaced. Of course, if desired, burnishing pad
304
may be glued or otherwise mounted to pad arm
302
. Notch
350
is at a small angle θ, e.g., approximately two degrees, relative to perpendicular to pad arm
302
. Consequently burnishing pad
304
is held at a small angle relative to perpendicular. Thus, when pad arm
302
is closed, the entire top surface of burnishing pad
304
is pressed against the surface of a disk. A second notch
352
is located at the other end of pad arm
302
and is used to mount extension
346
.
Pads
304
may be for example 0.46×0.4 inches and {fraction (3/16)} inch thick. Pads
304
may be manufactured from a material such as Poron 4701-40 from Western Rubber and Supply, located in Livermore, Calif.
FIG. 17
shows a stepper motor
362
used to open and close pad arms
302
.
FIG. 17
also shows a front view of pad arms
302
(similar to that shown in
FIG. 15
) in broken lines and extensions
346
. Stepper motor
362
, which for example is manufactured by IMS, is mounted under base plate
324
on a mount plate
364
. Stepper motor
362
drives a pair of screws
364
that are coupled to actuator arms
368
with nuts
370
. Actuator arms
368
are mounted to base plate
324
at hinges
372
.
As shown in
FIG. 17
, the ends of actuator arms
368
contact extensions
346
. Thus, to open pad arms
302
, stepper motor
362
rotates screws
366
to force nuts
370
away from each other. Consequently, actuator arms
368
press inward on extensions
346
. As extensions
346
are pressed toward each other, burnishing pads
304
at the end of pad arms
302
will be opened, i.e., moved away from each other. By reversing stepper motor
362
, pad arms
302
may be closed. Because a stepper motor
362
is used, pad arms
302
are closed in a controlled fashion. Thus, the initial contact between the disk and the burnishing tape is gentle, which advantageously prevents damage to the disk.
FIGS. 18 and 19
show a top plan view and a front end view, respectively, of swing arms
306
and the apparatus that rotates swing arms
306
to release and provide tension on the burnishing tape.
Tape guides
382
and
384
are mounted on swing arms
306
. Because the abrasive side of the burnishing tape will contact tape guide
382
, tape guide
382
is a roller. Tape guide
384
only contacts the back side of the burnishing tape and therefore may be a pin. Swing arms
306
are mounted on a shaft
386
that extends through bearings
388
and bearing housing
390
. Bearing housing
390
is mounted to base plate
324
by bolt
391
. Shaft
386
extends through base plate
324
and is mounted to actuator arms
392
. Actuator arms
392
are coupled to a linear actuator
394
via couplers
396
,
398
and tie rods
399
. Thus, as linear actuator
394
slides back and forth, actuator arms
392
will rotate shaft
386
, which will rotate swing arms
306
as indicated by arrows
307
.
FIGS. 20 and 21
show a simplified top plan view of burnishing apparatus
300
in a closed and an open position, respectively. As shown in
FIG. 20
, a burnishing tape
301
extends from supply reel
310
between tape guides
382
and
384
on swing arm
306
and around pad arm
302
. In the closed position there is little or no tension on burnishing tape
301
. The only tension on burnishing tape
301
required in the closed position is used to hold burnishing tape
301
in position on the various guides and rollers. The tip of pad arms
302
have a groove
303
(shown in
FIG. 13
) which helps center burnishing tape
301
over pads
304
. Pads
304
press burnishing tape
301
against the surfaces of disk
400
. Burnishing tape
301
then extends over various rollers and guides which prevent burnishing tape
301
from contacting disk
400
, except where pads
304
press burnishing tape
301
against disk
400
. Burnishing tape
301
is finally taken up at take-up reels
312
.
FIG. 21
shows pad arms
302
in an open position with swing arms
306
in a position to provide tension on burnishing tape
301
. With pad arms
302
in an open position, pads
304
are no longer pressing burnishing tape
301
against the surfaces of disk
400
. Thus, disk
400
may be replaced with a new disk to be burnished. Further, by rotating swing arms
306
, tape guide
382
applies tension to burnishing tape
301
such that burnishing tape
301
is not in contact with pads
304
. Consequently, burnishing tape
301
may be indexed to a new position without damaging pads
304
.
Burnishing tape
301
is indexed by capstan rollers
320
and
321
and the amount of indexing is detected by index guides
322
. As shown in
FIG. 13
, index guides
322
include a sensor to indicate the precise amount that index guides
322
have moved. Thus, the amount burnishing tape
301
is indexed may be carefully controlled. If desired, burnishing tape
301
may be indexed by take-up reels
312
. However, as burnishing tape
301
is taken up, the effective radius of the takeup reel
312
will change, making precise indexing of burnishing tape difficult.
FIG. 22
shows a side view of a take-up reel
312
. As can be seen, take-up reel
312
is mounted on a shaft
410
that is driven by a motor
412
, such as a model number 3TK6GN-AUL motor manufactured by Oriental Motor or part number M409M378 manufactured by Globe Motor. Take-up reel
312
is permitted to slip on shaft
410
. Thus, as the effect radius of the take-up reel
312
changes due to the accumulation of burnishing tape
301
on take-up reel
312
, the amount that take-up reel
312
rotates does not need to be changed.
FIGS. 23A and 23B
show a front view and a side view of capstan rollers
320
and
321
, both sets, and the driving mechanism. A gearmotor
420
, such as part number M409M378 manufactured by Globe Motor located in Dayton, Ohio, drives a belt (not shown) around two pulleys
422
and
424
. Pulley
424
drives both rollers
321
via gears
426
and
428
.
FIG. 24
is a side view of an index guide
322
, which freely rotates, along with a sensor
430
used to detect the amount that index guide
322
has rotated and thus how much burnishing tape
301
has been indexed. Sensor
430
may be, for example, may be the type manufactured by Omron located in Japan.
Burnishing apparatus rotates disk
400
at a constant linear velocity (CLV), e.g.,
300
meters/minute. The burnishing process is applied from the inside diameter to the outside diameter of disk
400
. The desired burnish constant (K), which is e.g.,
50
, is controlled by the CLV and the time spent at each radial point. Thus, as is well understood by those skilled in the art, the burnishing apparatus
300
must have a differential traverse speed, which is specified by the burnish constant K. Of course, if desired the revolutions per minute (RPMs) of disk
400
may be held constant.
While the present invention has been described in connection with specific embodiments, one of ordinary skill in the art will recognize that various substitutions, modifications and combinations of the embodiments may be made after having reviewed the present disclosure. The specific embodiments described above are illustrative only. Various adaptations and modifications may be made without departing from the scope of the invention. For example, various additional elements, such as sensors may be included in the burnishing apparatus. The spirit and scope of the appended claims should not be limited to the foregoing description.
Claims
- 1. An apparatus comprising:burnishing tape; burnishing tape indexing mechanism; at least one pad for pressing said burnishing tape against a surface of a disk to be burnished; a pad holder upon which said pad is mounted, said pad holder being movable so that said pad presses said burnishing tape against said surface of said disk; and at least one tape guide, said burnishing tape extending over said tape guide and said pad, said tape guide preventing said burnishing tape from contacting said pad when said burnishing tape is indexed by said burnishing tape indexing mechanism.
- 2. The apparatus of claim 1, wherein said pad holder moves so that said pad presses said burnishing tape against said surface of said disk.
- 3. The apparatus of claim 2, wherein said pad holder is biased so that said pad presses said burnishing tape against said surface of said disk.
- 4. The apparatus of claim 3, wherein said pad holder is a first pad arm having a first pad and said apparatus further comprises a second pad arm having a second pad, said first pad arm and said second pad arm being biased so that said first pad and said second pad press burnishing tape against a first surface and a second surface of said disk.
- 5. The apparatus of claim 4, wherein said first pad arm and said second pad arm movable to be centered on said disk.
- 6. The apparatus of claim 1, wherein said at least one tape guide applies tension to said burnishing tape when said pad does not press said burnishing tape against said surface of said disk to prevent said burnishing tape from contacting said pad.
- 7. The apparatus of claim 6, wherein said at least one tape guide releases substantially all the tension from said burnishing tape when said pad presses said burnishing tape against said surface of said disk.
- 8. The apparatus of claim 1, wherein said tape guide centers said burnishing tape over said pad when said pad holder moves said pad to press said burnishing tape against said surface of said disk so that said pad presses the approximate center of said burnishing tape against said surface of said disk.
- 9. The apparatus of claim 1, wherein said burnishing tape is indexed over said pad in a direction that is tangential relative to said disk.
- 10. The apparatus of claim 1, further comprising an arm upon which said at least one tape guide is mounted.
- 11. The apparatus of claim 8, wherein relative movement in a first direction between said at least one tape guide on said arm and said pad holder applies tension to said burnishing tape when said pad holder removes said pad from contact with said surface of said disk.
- 12. The apparatus of claim 9, wherein relative movement in a second direction opposite said first direction releases tension on said burnishing tape when said pad holder moves to place said pad in contact with said surface of said disk.
- 13. The apparatus of claim 8, wherein said arm swings to move said at least one tape guide to apply tension on said burnishing tape.
- 14. The apparatus of claim 1, wherein said burnishing tape indexing mechanism comprises:a motor driven take-up reel; and a resistantly rotating supply reel supplying said burnishing tape.
- 15. The apparatus of claim 14, further comprising a motor driven capstan reel over which said burnishing tape extends, said capstan reel controllably indexes said burnishing tape.
- 16. A method comprising:providing a disk between a first pad and a second pad; rotating said disk; providing burnishing tape between said first pad and a first surface of said disk and between said second pad and a second surface of said disk; moving said first pad and said second pad so that said first pad and said second pad press said burnishing tape in contact with said first surface and said second surface of said disk, respectively moving said first pad and said second pad away from said first surface and said second surface of said disk, respectively; and holding said burnishing tape away from said first pad and said second pad when said first pad and said second pad are moved away from said first surface and said second surface of said disk.
- 17. The method of claim 16, further comprising indexing said burnishing tape when said burnishing tape is held away from said first pad and said second pad.
- 18. The method of claim 17, further comprising applying tension to said burnishing tape prior to indexing said burnishing tape.
- 19. The method of claim 18, further comprising releasing tension on said burnishing tape when said first pad and said second pad are moved towards said first surface and said second surface of said disk, respectively.
- 20. The method of claim 16, wherein said first pad and said second pad are mounted on a first pad holder and a second pad holder, respectively, wherein moving said first pad and said second pad so that said first pad and said second pad press said burnishing tape in contact with said first surface and said second surface of said disk, comprises moving said first pad holder and said second pad holder in unison.
- 21. The method of claim 16, wherein moving said first pad and said second pad so that said first pad and said second pad press said burnishing tape in contact with said first surface and said second surface of said disk, respectively, further comprises automatically applying equal pressure on said first surface and said second surface.
- 22. An apparatus comprising:burnishing tape; pads to press said burnishing tape against opposing surfaces of a disk to be burnished; pad holders coupled to said pads; and means for holding said burnishing tape away from said pads when said pads are not pressing said burnishing tape against said opposing surfaces of said disk.
- 23. The apparatus of claim 22, wherein said means for holding said burnishing tape away from said pads applies tension on said burnishing tape when said burnishing tape is indexed over said pad.
- 24. The apparatus of claim 23, wherein said means for holding said burnishing tape away from said pads also removes tension from said burnishing tape when said pads press said burnishing tape against said opposing surfaces of said disk.
- 25. The apparatus of claim 24, wherein said means for holding said burnishing tape away from said pads comprises tape guides mounted on swing arms and movable pad holders, said swing arms and said pad holders move said tape guides and said pads relative to each other to apply tension to said burnishing tape as said burnishing tape is held away from said pads.
- 26. The apparatus of claim 22, further comprising a means for biasing said pad holders together to apply approximately equal pressure against said surfaces of said disk with said pads.
- 27. The apparatus of claim 26, further comprising means for automatically centering said pads on said disk.
- 28. An apparatus comprising:a disk handling mechanism for rotating a disk; a first pad and a second pad; and a first pad holder upon which said first pad is mounted and a second pad holder upon which said second pad is mounted, said first pad holder and said second pad holder being configured to hold said first pad and said second pad on opposing sides of said disk mounted on said disk handling mechanism, said first pad holder and second pad holder being biased together such that said first pad and said second pad automatically apply approximately equal pressure to both sides of said disk; wherein said first pad holder and said second pad holder are linearly movable in unison in a direction perpendicular to the plane of said disk wherein said first pad holder and said second pad holder move linearly to center said first pad and said second pad on said disk.
- 29. The apparatus of claim 28, further comprising a spring coupled to said first pad holder and said second pad holder, said spring biasing said first pad holder and said second pad holder together such that said first pad and said second pad automatically apply equal pressure to both sides of said disk.
- 30. The apparatus of claim 28, further comprising a rail coupled to said first pad holder and said second pad holder, said rail permitting said first pad holder and said second pad holder to move towards each other and away from each other, said rail further permitting said first pad holder and said second pad holder to move together in unison in a direction perpendicular to the plane of said disk so that said first pad and said second pad are automatically centered on said disk.
- 31. The apparatus of claim 30, wherein said first pad holder and said second pad holder move together in unison on said rail while said first pad holder and said second pad holder are coupled to a spring that biases said first pad and said second pad together to automatically apply equal pressure to both sides of said disk.
US Referenced Citations (12)
Foreign Referenced Citations (2)
Number |
Date |
Country |
4-30674 |
Mar 1987 |
JP |
1140958 |
Jun 1989 |
JP |