U.S. patent application number 10/742498 was filed with the patent office on 2005-06-23 for precision surface polishing equipment.
Invention is credited to Brost, Randolph C..
Application Number | 20050136812 10/742498 |
Document ID | / |
Family ID | 34678464 |
Filed Date | 2005-06-23 |
United States Patent
Application |
20050136812 |
Kind Code |
A1 |
Brost, Randolph C. |
June 23, 2005 |
Precision surface polishing equipment
Abstract
Precision polishing equipment polishes a general surface, such
as an aspheric optical surface. A polishing element is rotatably
mounted in a frame of the equipment. Polishing element has a
compliant polishing member fixedly mounted to a substantially rigid
support member. Compliant polishing member has plurality of spaced
polishing portions for engaging the surface to be polished and
trapping polishing fluid between the interface of the surface to be
polished and nearest polishing portion in contact with the surface.
Important advantages derived from the polishing equipment of the
invention are that it can efficiently polish a general surface,
such as an aspheric optical surface, and it enables the polishing
fluid to evenly flow across the surface to be polished.
Inventors: |
Brost, Randolph C.;
(Albuquerque, NM) |
Correspondence
Address: |
Pamela R. Crocker
Patent Legal Staff
Eastman Kodak Company
343 State Street
Rochester
NY
14650-2201
US
|
Family ID: |
34678464 |
Appl. No.: |
10/742498 |
Filed: |
December 19, 2003 |
Current U.S.
Class: |
451/177 |
Current CPC
Class: |
B24B 29/00 20130101;
B24B 13/01 20130101 |
Class at
Publication: |
451/177 |
International
Class: |
B24B 007/00 |
Claims
What is claimed is:
1. Precision surface polishing equipment, comprising: a rigid
frame; a polishing element mounted for rotation in said rigid
frame, said polishing element having a substantially rigid support
member cooperatively associated with a compliant polishing member
fixedly attached thereto, said compliant polishing member having a
plurality of spaced polishing portions for engaging a surface to be
polished, each one of said plurality of spaced polishing portions
being projected radially outwardly from said substantially rigid
support member, and wherein nearest adjacent of said each one of
said plurality of spaced polishing portions form a fluid transport
region therebetween when said compliant polishing member is in
compressive contact with said surface to be polished; means
associated with said rigid frame for rotating said polishing
element; and, means for applying a layer of polishing fluid onto
said surface to be polished, said layer of polishing fluid being
substantially evenly applied onto said surface to be polished when
disposed in said fluid transport region of said polishing
element.
2. The precision polishing equipment recited in claim 1 wherein
each one of said plurality of spaced polishing portions is
configured to trap polishing fluid between the surface to be
polished and a nearest one of said plurality of spaced polishing
portions.
3. The precision polishing equipment recited in claim 2 wherein
each of said plurality of spaced polishing portions is
substantially torus shaped.
4. The precision polishing equipment recited in claim 1 wherein
said means for rotating is a motor.
5. The precision polishing equipment recited in claim 1 wherein
said means for applying a polishing fluid comprises a fluid
reservoir in fluid communications with a nozzle, said nozzle being
directed at said surface to be polished.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is related to U.S. Ser. No.
10/645,692 filed Aug. 21, 2003 of Randolph C. Brost, entitled
"Compliant Polishing Element And Method Of Manufacturing The Same",
Atty. Docket No. 85078/CEB.
FIELD OF THE INVENTION
[0002] The invention relates generally to the field of precision
surface polishing, and in particular to polishing of general
surfaces. More specifically, the invention relates to a tool for
polishing precision surfaces.
BACKGROUND OF THE INVENTION
[0003] It is well known in the art that precision surface polishing
is often performed by large pads that execute planar or spherical
motions relative to the surface to be polished. These large pads
are either flat or spherical, depending on the shape of the surface
to be polished. Because the pad shape and motion both match the
surface, a large pad can contact the surface over a large area, and
repetitive polishing motions can produce a precise surface by
averaging effects.
[0004] However, for polishing general surfaces, such as aspheric
optical surfaces, existing polishing devices and systems have
proven woefully inadequate. For these surfaces, the contact between
the polishing tool and the surface must be much smaller than the
pads used for planar or spherical surfaces, because the local
radius of curvature varies across the surface. Further, polishing
pads that are entirely sufficient for polishing planar or spherical
surfaces are not sufficiently compliant to accommodate the
variations in curvature radius inherent in aspheric surfaces to be
polished.
[0005] While there have been numerous attempts in the prior art to
address the challenges presented when polishing aspheric surfaces,
there has been limited success in overcoming the aforementioned
problems. As an example, in one known device for polishing an
aspheric surface, a small contact patch is used to contact the
surface. In another instance, a large wheel device is used that
achieves a small contact patch by exploiting magneto-rheological
fluids. Further, other polishing systems that have attempted to
solve the aforementioned problem have used a convex pad to polish
the surface, sometimes with a pressing motion. One shortcoming with
all of the above-mentioned polishing systems is that the polishing
tool is large relative to the contact patch, which makes it
impossible to use for surfaces with small, deep concavities. There
is one prior art attempt that seeks to overcome this latter problem
disclosed in co-pending U.S. patent application Ser. No.
10/318,787, filed Dec. 13, 2002 by Stephen C. Meissner, titled
"Sub-Aperture Compliant Toroidal Polishing Element," hereby
incorporated herein by reference. The compliant polishing tool in
U.S. Ser. No. 10/318,787 uses a very small toroidal compliant tool
to achieve a small polishing contact patch that can reach into
small concavities.
[0006] One problem that is known to occur with the above and all of
the existing compliant polishing tools is that a deficiency in
polishing fluid coverage on the surface to be polished results as
contact pressure is increased between the polishing member and the
surface. It is our experience that this deficiency arises because
polishing fluid is forced away from the center of the contact
region of the polishing member and surface to be polished, leaving
a region deficient in fluid coverage for effective polishing. As a
result, it is well known that prior art polishing devices limit the
contact pressures that may be applied by the polishing member on
the surface to be polished, which in turn limits material removal
rates. Consequently these compliant tools cannot achieve the
polishing productivity and efficiency that might be attained if
positive fluid flow throughout the contact was assured.
[0007] Therefore, there remains a need for a compliant polishing
element for polishing surfaces, particularly aspheric surfaces,
that provides a small contact patch that can reach into deep
concavities, while maintaining fluid flow throughout the contact
even while significant contact pressure is applied by the polishing
member.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to overcoming one or more
of the problems set forth above. Briefly summarized, according to
one aspect of the present invention, precision surface polishing
equipment has a rigid frame and a polishing element mounted for
rotation in the rigid frame. The polishing element has a
substantially rigid support member cooperatively associated with a
compliant polishing member fixedly attached thereto. The compliant
polishing member has a plurality of spaced polishing portions for
engaging a surface to be polished, each one of the plurality of
spaced polishing portions being projected radially outwardly from
the substantially rigid support member. Nearest adjacent of the
plurality of spaced polishing portions form a fluid transport
region therebetween when the compliant polishing member is in
compressive contact with the surface to be polished. Means
associated with the rigid frame is provided for rotating the
polishing element. Further, a polishing fluid is applied to the
surface with an appropriate means such as a reservoir connected to
a fluid nozzle. The layer of polishing fluid is substantially
evenly applied onto the surface to be polished when disposed in the
fluid transport region of the polishing element.
[0009] The present invention has numerous advantages over prior art
developments. For instance, the polishing device can polish
aspheric surfaces. Moreover, the polishing device of the invention
is not complicated to manufacture and is easy to use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above and other objects, features, and advantages of the
present invention will become more apparent when taken in
conjunction with the following description and drawings wherein
identical reference numerals have been used, where possible, to
designate identical features that are common to the figures, and
wherein:
[0011] FIG. 1A is an elevated, slightly tilted side view of the
polishing device of the invention;
[0012] FIG. 1B is an elevated side view of the polishing device of
FIG. 1A partially sectioned and exploded to show the lobes of the
polishing member;
[0013] FIG. 2 is a schematic of the polishing tool of the invention
during polishing;
[0014] FIG. 3A is an elevated side view of an alternative
embodiment of the invention;
[0015] FIG. 3B is an elevated side view of the embodiment of FIG.
3A partially sectioned and exploded to show the features of the
polishing member;
[0016] FIG. 4 is an enlarged perspective view of the compliant
polishing member used in the embodiment of FIGS. 3A and 3B;
[0017] FIGS. 5A-5F are top plan views of several exemplary
compliant polishing members used in the invention;
[0018] FIG. 6A is an elevated side view of another alternative
embodiment of the invention;
[0019] FIG. 6B is an elevated side view of the embodiment of FIG.
6A partially sectioned and exploded to show the polishing
member;
[0020] FIG. 7 is an enlarged perspective view of the compliant pad
illustrated in FIGS. 6A and 6B;
[0021] FIG. 8A is an elevated side view of yet another embodiment
of the invention;
[0022] FIG. 8B is the embodiment of FIG. 8A partially sectioned and
exploded to show the polishing member;
[0023] FIG. 9 is an enlarged perspective view of the compliant pad
of the embodiment illustrated in FIGS. 8A and 8B;
[0024] FIG. 10 is a perspective view of a polishing tool containing
the polishing element of the invention; and,
[0025] FIG. 11 is an elevated side view of the polishing tool of
FIG. 9 in service polishing a surface;
DETAILED DESCRIPTION OF THE INVENTION
[0026] Turning now to the drawings, and more particularly to FIGS.
1A and 1B, polishing element 10 of the first embodiment of the
invention is illustrated. According to FIGS. 1A and 1B, polishing
element 10 has a substantially rigid support member 12 with an
outer perimeter 14 for cooperatively associating with a tool, such
as the exemplary rotary tool shown in FIG. 10. The outer perimeter
14 terminates at one end with a mounting surface 16 provided for
affixing a compliant polishing member or pad 18. Compliant
polishing member 18 may be affixed to mounting surface 16 in any
number of ways including gluing, friction or interference fit, or
with a screw. Moreover, the compliant polishing member 18 may be
molded to the mounting surface 16.
[0027] Referring to FIGS. 1A, 1B, and 2, polishing tool 26
comprises a polishing fluid applicator or nozzle 23 and the
polishing element 10 (compliant polishing member 18 only
illustrated) in a precision surface polishing application, for
example, polishing an aspheric optical surface 22. Compliant
polishing member 18 of the invention has a plurality of regularly
spaced polishing portions or lobes 20 for spreading polishing fluid
21 across the surface 22 to be polished. The recess 24 between
nearest adjacent lobes 20 enables a predetermined amount of
polishing fluid 21 to be spread in a predictable manner across the
surface 22 to be polished. During a precision polishing
application, the polishing element 10 is structurally mounted into
a spindle (not shown) of a rotary device (FIG. 11) via the
substantially rigid support member 12 (FIGS. 1A and 1B). The
polishing element 10 is rotated while in compressive contact with
the surface 22 to be polished. A polishing fluid, such as a slurry
of abrasive particles, is disposed, typically via nozzle 23, in an
interfacial area between adjacent lobes 20 of the compliant
polishing element 10 and the surface 22 to be polished. As the
polishing element 10 is rotated by the rotary device, the plurality
of spaced polishing portions or lobes 20 traps polishing fluid 21
between the surface 22 to be polished and the nearest of the lobes
20. This action forces the polishing fluid 21 across the surface 22
to be polished. In the process, it also prevents polishing fluid
starvation from any area on the surface 22 to be polished.
[0028] Referring to FIGS. 3A, 3B, and 4, in a second embodiment of
the invention, polishing element 30 has a substantially rigid
support member 33 and a compliant polishing member 35 mounted on an
end portion (not shown) of the support member 33. Compliant
polishing member 35 has a plurality of spaced lobes 37 each being
connected to a nearest adjacent lobe 37 by a recess 39. A
continuous groove 41 passes through each of the lobes 37 about the
circumference of the compliant polishing member 35. A portion of
each lobe 37 separated by the groove 41 is directed inwardly
towards the groove 41. Groove 41 prevents polishing fluid 21 from
escaping from between the lobes 37 and surface to be polished 22
(shown in FIG. 2) as polishing element 30 rotates. According to
FIG. 4, continuous groove 41 is clearly shown in a close-up view of
the polishing element 30.
[0029] Referring now to FIGS. 5A-5F, illustrated are several
substantially star-shaped configurations 40, 50, 60, 70, 80, 90 for
compliant polishing member 18 or pads. Each of these substantially
star-shaped configurations 40, 50, 60, 70, 80, 90 may be used in
the polishing element 10 of the invention to produce substantially
the same result. More particularly, each of the substantially
star-shaped configurations 40, 50, 60, 70, 80, 90 produces similar
favorable fluid dynamics at the interface of the surface 22 and
compliant polishing member 18. According to FIG. 5A, configuration
40 has typically six lobes 42 having rounded peaks 44 separated by
slightly arcuate recesses 46 which form a slightly arcuate angled
lobe 42. According to FIG. 5B, configuration 50 has a plurality of
lobes 52 (typically six) each having a relatively flat and
substantially straight peak 54 separated from the nearest adjacent
lobe 52 by a slightly curved recess 56 to form a flat,
substantially straight lobe 52. According to FIG. 5C, configuration
60 has a plurality of lobes 62 (typically six) each having a
relatively narrow and slightly rounded peak 64 separated by a
slightly curved recess 66 to form a substantially straight lobe 62.
According to FIG. 5D, configuration 70 has a plurality of lobes 72
(typically six) each having a relatively narrow and round peak 74
separated from the nearest adjacent lobe 72 by substantially curved
recess 76 to form a narrow, substantially arcuate shaped lobe 72.
According to FIG. 5E, configuration 80 has a plurality of lobes 82
each having a narrow rounded peak 84 separated from the nearest
adjacent peak 84 by substantially wide, arcuate shaped recess 86 to
form a substantially wide arcuate lobe 82. Finally, according to
FIG. 5F, configuration 90 has a plurality of lobes 92 each having a
narrow, very round peak 94 separated from the nearest adjacent
narrow, very round peak 94 by a very arcuate shaped recess 96 to
form a narrow, very arcuate lobe 92.
[0030] Turning now to FIGS. 6A, 6B, and 7, a third embodiment of
the compliant polishing element 100 is illustrated. According of
FIGS. 6A, 6B, and 7, compliant polishing element 100 has a
substantially disk-shaped polishing member 102 supported on
substantially rigid support 104. A central opening 106 passes
through the compliant polishing member 102 for locating onto the
substantially rigid support 104. As indicated above, substantially
rigid support 104 cooperates with a rotary tool for polishing a
work piece (Shown in FIG. 10). In this embodiment, compliant
polishing element 100 is characterized by a plurality of spaced
depressions 108 arranged in the circumference 110 of the compliant
polishing member 102. the portions of the circumference 110 between
the depressions 108 form the compliant polishing portions 112. As
in the previous embodiments, the spaced depressions 108 trap the
polishing fluid between the surface 22 to be polished and the
compliant polishing member 102 during polishing. Further, spaced
depressions 108 assure that the polishing fluid will spread across
the surface without leaving voids. Depressions 108 may be formed in
the circumference of compliant polishing member 102 in a number of
ways, including cutting or forming during a molding process.
[0031] Referring now to FIGS. 8A, 8B, and 9, a fourth embodiment of
the compliant polishing element 120 is illustrated. In this
embodiment, the compliant polishing element 120 has a substantially
rigid support 122 and a compliant polishing member 124 attached to
one end of the rigid support 122. Important to the invention,
compliant polishing member 124 has a plurality of spaced compliant
polishing portions 126 each having a surface shape generally in the
form of a torus, as best seen in FIG. 9. The compliant polishing
portions surround recessed portions 128. As in previous
embodiments, the substantially torus-shaped compliant polishing
member 124 traps polishing fluid between the interface of the
surface 22 to be polished and the recessed portions 128 of the
compliant polishing member 124. Compliant polishing member 124
further provides means for distributing the polishing fluid across
the surface area of the surface 22 to be polished.
[0032] Referring now to FIGS. 10 and 11, precision surface
polishing equipment, such as tool, 200 for precision polishing a
general surface, for instance an aspheric optical surface, is
shown. In FIG. 11, a partial schematic of polishing element 220 of
polishing equipment 200 is shown polishing an aspheric surface 240
(FIG. 11). According to FIG. 10, polishing equipment 200 comprises
a movable work piece holder 210 for precise engagement by compliant
polishing member 230 of polishing element 220. Polishing element
220 comprises compliant polishing member 230 affixed to
substantially rigid support member or frame 250. In the preferred
embodiment, polishing element 220 is slightly angled from the
polishing surface normal (FIG. 11). Means, such as a nozzle
(described above) is provided for applying a layer of polishing
fluid onto the surface to be polished. The polishing fluid is not
shown. This configuration allows polishing of flat surfaces and
concavities using a uniform contact condition.
[0033] The invention has been described with reference to a
preferred embodiment. However, it will be appreciated that
variations and modifications can be effected by a person of
ordinary skill in the art without departing from the scope of the
invention.
Parts List
[0034] 10 first embodiment of polishing element
[0035] 12 substantially rigid support member
[0036] 14 outer perimeter of support member 12
[0037] 16 mounting surface
[0038] 18 compliant polishing member of first embodiment
[0039] 20 lobes
[0040] 21 polishing fluid
[0041] 22 surface to be polished
[0042] 23 nozzle
[0043] 24 recess between nearest adjacent lobes 20
[0044] 26 partial polishing tool
[0045] 30 second embodiment of polishing element
[0046] 33 substantially rigid support member of second
embodiment
[0047] 35 compliant polishing member of second embodiment
[0048] 37 lobes of second embodiment
[0049] 39 recess separating nearest adjacent lobes 37
[0050] 40 first configuration of compliant polishing member 18
[0051] 41 continuous groove
[0052] 42 lobes of first configuration
[0053] 44 rounded peaks of lobes 42
[0054] 46 slightly arcuate recess
[0055] 50 second configuration of compliant polishing member 18
[0056] 52 lobes of second configuration
[0057] 54 substantially straight peak of lobe 52
[0058] 56 slightly curved recesses between nearest adjacent lobes
52
[0059] 62 third configuration of compliant polishing member 18
[0060] 64 lobes of third configuration
[0061] 66 slightly rounded peak of lobes 62
[0062] 70 slightly curved recess between nearest adjacent lobes
62
[0063] 72 fourth configuration of compliant polishing member 18
[0064] 72 lobes of fourth configuration
[0065] 74 round peak of lobes 72
[0066] 76 substantially curved recesses between nearest adjacent
lobes 72
[0067] 80 fifth configuration of compliant polishing member 18
[0068] 82 lobes of fifth configurations
[0069] 84 narrow rounded peaks of lobes 82
[0070] 86 substantially wide, arcuate shaped recess between nearest
adjacent lobes
[0071] 90 sixth configuration of compliant polishing member 18
[0072] 92 lobes of sixth configuration
[0073] 94 very round peaks of lobes 92
[0074] 96 very arcuate shaped recess between nearest adjacent lobes
92
[0075] 100 third embodiment of compliant polishing element
[0076] 102 disk shaped polishing member of third embodiment
[0077] 104 rigid support of third embodiment
[0078] 106 central opening passing through member 102
[0079] 108 spaced depressions in compliant polishing member 102
[0080] 110 circumference of compliant polishing member 102
[0081] 112 compliant polishing portions of polishing member 102
[0082] 120 fourth embodiment of compliant polishing element
[0083] 122 rigid support of compliant polishing element 120
[0084] 124 compliant polishing member of fourth embodiment
[0085] 126 spaced polishing portions
[0086] 128 recessed portion
[0087] 200 tool for precision polishing
[0088] 210 movable work piece holder
[0089] 220 polishing element of tool 200
[0090] 230 compliant polishing member of element 220
[0091] 240 aspheric surface
[0092] 250 substantially rigid support member of element 220
* * * * *