Precision surface polishing equipment
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.
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 INVENTIONThe 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, 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.
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 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:
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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
- 62 third configuration of compliant polishing member 18
- 64 lobes of third configuration
- 66 slightly rounded peak of lobes 62
- 70 slightly curved recess between nearest adjacent lobes 62
- 72 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
- 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. 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.
Type: Application
Filed: Dec 19, 2003
Publication Date: Jun 23, 2005
Inventor: Randolph Brost (Albuquerque, NM)
Application Number: 10/742,498