Compliant polishing element and method of manufacturing the same
A precision polishing element polishes a general surface, such as an aspheric optical surface. A compliant polishing member is mounted to a substantially rigid support member. The compliant polishing member has plurality of spaced compliant 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. An important advantage derived from the polishing element of the invention is that it enables the polishing fluid to evenly distribute across the surface to be polished.
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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 INVENTIONIt 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.
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.
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.
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.
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 INVENTIONThe 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, a precision polishing element has a substantially rigid support member having an outer perimeter for cooperating with a tool. The outer perimeter terminates at one end in a mounting surface to which is mounted a polishing member. Important to the invention, polishing member has a plurality of regularly spaced compliant polishing portions or lobes for engaging a surface to be polished. Each one of the regularly spaced compliant polishing portions project outwardly from a recess separating nearest adjacent compliant polishing portions. The recess separating nearest adjacent compliant polishing portions provides a polishing fluid transport region there between when the polishing member is in compressive contact with the surface to be polished.
The present invention has numerous advantages over prior art developments. For instance, the polishing device can polish general surfaces, such as aspheric optical surfaces. Moreover, the polishing device of the invention eliminates deficient polishing fluid zones on the surface to be polished. Further, the polishing device of the invention is simple to construct and easy to utilize.
BRIEF DESCRIPTION OF THE DRAWINGSThe 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:
Turning now to the drawings, and more particularly to
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 (
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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
- 10 first embodiment of polishing element
- 12 substantially rigid support member
- 14 outer perimeter of support member 12
- 16 mounting surface
- 18 compliant polishing member of first embodiment
- 20 lobes
- 21 polishing fluid
- 22 surface to be polished
- 23 nozzle
- 24 recess between nearest adjacent lobes 20
- 26 partial polishing tool
- 30 second embodiment of polishing element
- 33 substantially rigid support member of second embodiment
- 35 compliant polishing member of second embodiment
- 37 lobes of second embodiment
- 39 recess separating nearest adjacent lobes 37
- 40 first configuration of compliant polishing member 18
- 41 continuous groove
- 42 lobes of first configuration
- 44 rounded peaks of lobes 42
- 46 slightly arcuate recess
- 50 second configuration of compliant polishing member 18
- 52 lobes of second configuration
- 54 substantially straight peak of lobe 52
- 56 slightly curved recesses between nearest adjacent lobes 52
- 60 third configuration of compliant polishing member 18
- 62 lobes of third configuration
- 64 slightly rounded peak of lobes 62
- 66 slightly curved recess between nearest adjacent lobes 62
- 70 fourth configuration of compliant polishing member 18
- 72 lobes of fourth configuration
- 74 round peak of lobes 72
- 76 substantially curved recesses between nearest adjacent lobes 72
- 80 fifth configuration of compliant polishing member 18
- 82 lobes of fifth configurations
- 84 narrow rounded peaks of lobes 82
- 86 substantially wide, arcuate shaped recess between nearest adjacent lobes 82
- 90 sixth configuration of compliant polishing member 18
- 92 lobes of sixth configuration
- 94 very round peaks of lobes 92
- 96 very arcuate shaped recess between nearest adjacent lobes 92
- 100 third embodiment of compliant polishing element
- 102 disk shaped polishing member of third embodiment
- 104 rigid support of third embodiment
- 106 central opening passing through member 102
- 108 spaced depressions in compliant polishing member 102
- 110 circumference of compliant polishing member 102
- 112 compliant polishing portions of polishing member 102
- 120 fourth embodiment of compliant polishing element
- 122 rigid support of compliant polishing element 120
- 124 compliant polishing member of fourth embodiment
- 126 spaced polishing portions
- 128 recessed portion
- 200 tool for precision polishing
- 210 movable work piece holder
- 220 polishing element of tool 200
- 230 compliant polishing member of element 220
- 240 aspheric surface
- 250 substantially rigid support member of element 220
Claims
1. A precision polishing element, comprising:
- a substantially rigid support member having an outer perimeter for cooperating with a tool, said outer perimeter terminating at one end in a mounting surface;
- a polishing member mountable to said mounting surface of said substantially rigid support member, said polishing member having a plurality of spaced compliant polishing portions, nearest adjacent ones of said plurality of spaced compliant polishing portions being separated by a recessed portion, said recessed portion forming a fluid transport region when nearest adjacent compliant polishing portions are in compressive contact with a surface to be polished.
2. The precision polishing element recited in claim 1 wherein said polishing member has a substantially toroidal shape.
3. The precision polishing element recited in claim 1 wherein said polishing member has a substantially polygonal shape.
4. The precision polishing element recited in claim 1 wherein said polishing member has a substantially star-like shape having irregularly configured lobes.
5. The precision polishing element recited in claim 1 wherein said polishing member has a continuous groove formed in a circumferential portion thereof.
6. The precision polishing element recited in claim 1 wherein said compliant polishing member comprises a material selected from the group consisting of an elastic solid material, a polymeric material, and a mixture thereof.
7. The precision polishing element recited in claim 6 wherein said polymeric material is selected from the group consisting of: polyurethane, chloroprene, fluorocarbon, fluorosilicone, ethylene propylene, and nitrile.
8. The precision polishing element recited in claim 7 wherein said polymeric material is nitrile.
9. The precision polishing element recited in claim 1 wherein said substantially rigid support member is mounted to said polishing member by chemical bonding.
10. The precision polishing element recited in claim 1 wherein said substantially rigid support member is mounted to said polishing member by thermal bonding.
11. The precision polishing element recited in claim 1 wherein said substantially rigid support member is mounted to said polishing member by mechanical bonding.
12. The precision polishing element recited in claim 1 wherein said substantially rigid support member is mounted to said polishing member by direct molding.
13. The precision polishing element recited in claim 1 wherein each of said plurality of spaced compliant polishing portions has a Shore A hardness in the range of about 40-95.
Type: Application
Filed: Aug 21, 2003
Publication Date: Feb 24, 2005
Applicant:
Inventor: Randolph Brost (Albuquerque, NM)
Application Number: 10/645,692