US 3499250 A
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United States Patent 3,499,250 POLISHING APPARATUS Elmer W. Jensen, Mount Vernon, N.Y., and Hans R.
Jacobsen, Norwalk, C0nn., assignors to Geoscience Instruments Corporation, Mount Vernon, N.Y., a corporation of New York Continuation-impart of application Ser. No. 562,757,
July 5, 1966. This application Apr. 7, 1967, Ser.
Int. Cl. B24b 7/00, 9/00, 11/00 U.S. Cl. 51109 7 Claims ABSTRACT OF THE DISCLOSURE An organization for polishing bulk materials such as glass, stone, metals or the like, includes layers of a poromeric material such as Corfam and sponge rubber to produce an internal self-cleaning, waste material expelling mechanism.
This invention relates to apparatus for effecting polishing operations. The application is a continuation-in-part of my pending application Ser. No. 562,757, filed July 5, 1966.
There is extensive present applications for materials to impart a highly polished finish to glass, Corning Ware (a trademark of the Corning Glass Works for a ceramic composition), stone and the like. To effect such finishing, a polishing cloth is typically used in conjunction with an abrasive polishing slurry.
However, prior art compositions which have heretofore embodied polishing cloths have been characterized by one or more of the following deficiencies: (l) temperature sensitivity, and therefore instability at high polishing rates; (2) heterogeneous consistency; (3) a propensity to pick up and retain foreign elements; (4) poor wear characteristics requiring frequent replacement; (5) variations from sample to sample; (6) the characteristic of being impermeable and thereby preventing a polishing slurry from reaching all surface areas of a work material being operated upon; (7) relatively little tensile strength, thereby being subject to distortion; and (8) a resistance to bonding thereby being difiicult to affix to cooperating compositions and/or a lapping plate.
To expand upon item (3) above, a polishing cloth for finishing bulk materials must be self-cleaning, i.e., must have an internal mechanism to expel large slurry or waste particles thrown off by the subject material when materials of relatively large size, such as those illustratively specified above, are polished. Failure to expel these undesirable particles will cause scratching, rather than polishing of the workpiece surface, and also results in destruction of the polishing material when the requisite high polishing speeds are employed.
It is therefore an object of the present invention to provide an improved apparatus for polishing workpieces.
More specifically, an object of the present invention is the provision of a resilient, homogeneous polishing organization which is porous, relatively insensitive to temperature, and which is self-cleaning, i.e., which expels undesirable waste products.
These and other objects of the present invention are realized in a specific illustrative polishing organization which comprises a layer of Corfam (a trademark of the Du Pont Corporation for poromeric material, i.e.," a microporous and permeable coriaceous nonwoven sheet comprising a urethane polymer base reinforced with polyester), having a plurality of apertures therethrough. A layer of sponge rubber is disposed between the Corfam material and a polishing mechanism such as a lapping or polishing plate.
The active Corfam surface is made flat, and is adapted to polish workpieces brought in frictional contact'therewith. A Corfam composition including the above-mentioned apertures cooperates with the sponge rubber layer to impart a living texture, i.e., the properties of compressibility and resiliency to the composite polishing organization. Accordingly, the Corfam composition expels rather than retains slurry particles and waste materials from the workpiece coming in contact therewith.
A complete understanding of the present invention and of the above and other objects thereof may be gained from a consideration of an illustrative embodiment thereof depicted in the accompanying drawing.
Referring now to the drawing, there is shown in elevation form an illustrative polishing organization which embodies the principles of the present invention. The arrangement includes a layer of Corfam 20 having a layer,
of Buna-N rubber 35 affixed thereto via an adhesive 30. The Corfam 20 has a plurality of apertures 25 therethrough from its active upper polishing surface to, and optionally through the Buna-N rubber 35. The function of these apertures 25 is presented hereinbelow. A pressure sensitive clean release adhesive 40 is employed to bond the Buna-N rubber 35 to a layer of sponge rubber 50. It is noted that other poromeric materials, as well as other compositions embodying the attributes of Corfam described herein may be employed in place of the Corfam 20.
The Corfam 20 is fabricated such that the active, or upper surface thereof exhibits the requisite flatness for a particular polishing operation (assuming that a fiat surface is desired for a workpiece). To effect such polishing, the layer 20 is urged into bearing pressure contact with a material 15 to be polished, with such elements 15 typically comprising, for example, glass, stone, metal surfaces, Corning Ware or the like. The polishing is advantageously performed in a slurry environment, with a slurry being supplied by a source 60 thereof via a nozzle 61 The Corfam material 20 is very porous, and hence the slurry is translated by the layer 20 to all portions of the surface of the element 15 thereby effecting uniform polishing. Also, the Corfam material 20 is essentially insensitive to temperature, at least in the temperature range of interest for polishing operations. Accordingly, polish ing may be accompli hed at the high rates of speed required for relatively large workpieces. Moreover, the Corfam 20 is homogeneous, and may be fabricated in relatively large quantities to produce many uniform polishing elements without material variation from sample to sample.
With large, bulk work elements 15 as illustratively enumerated above, prior art polishing cloths have worn very rapidly. In such polishing applications, the large, hard waste particles from the subject workpiece, and large abrasive particles in the slurry, become embedded in the cloth. Then when the cloth rubs against the workpiece at the characteristic high rate of speed, the trapped particles operate to rapidly destroy the polishing cloth.
According to one aspect of the present invention, the Corfam 20 with its associated axial apertures 25, acting in cooperation with the sponge rubber 50, impart a living texture to the cloth. That is, when the polishing surface is depressed by an applied pressure, it will spring back when the pressure is removed. Further, such a depression may traverse across the polishing surface. These qualities have been found to impart a self-cleaning property to the composite polishing cloth, i.e., to enable it to expel any waste particles with which it comes in contact. This, in turn, imparts a long service life to the polishing organization, which is not self-consuming when effecting its polishing function.
As an additional feature, the active, upper surface of the Corfam layer 20 can be treated or impregnated for special polishing operations. Such treatment may comprise, for example, brushing, knapping, skiving or texturing the Corfam surface to increase the active polishing area, or calendaring the surface to increase its flat- By way of functional operation, the composite laminated polishing operation 20-2530354045-50 is urged in rotational bearing contact by a lapping plate 55 or the like in the presence of slurry supplied bythe source 60. The resulting frictional interface between the upper surface of the Corfam 20 and the work-piece imparts the desired polished surface to the member 15. During such polishing, the characteristic living texture for the composite organization is effective to expel all undesirable particles to ensure a prolonged life for the Corfam material 20.
It is noted at this point that the clean release adhesive 40, and the Buna-N rubber 30 to which such an adhesive readily bonds, are employed to facilitate the removal of the Corfam from the sponge rubber 50 at the termination of useful life for the active layer 20. If desired, the sponge rubber 50 may be affixed to the Corfam 20, either directly cured therein or attached by any of the well known adhesives therefor.
It is to be understood that the above-described method and organization are only illustrative of the application of the principles of the present invention. Numerous other arrangements and modes of operation may be devised by those skilled in the art without departing from the spirit and scope of the invention.
What is claimed is:
1. In combination in a polishing apparatus, a poromeric material having a first operative polishing surface and an oppositely disposed second surface, a plurality of vacated apertures formed in said poromeric material and included in said first poromeric surface and aligned toward said second surface, and a layer of compressible material afiixed to said second surface of said poromeric material.
2. The combination as in claim 1 wherein said compressible material comprises sponge rubber.
3. The combination as in claim 1 further comprising a layer of Buna-N rubber interposed between said second surface of said poromeric material and said compressible material.
4. The combination as in claim 3 further comprising a pressure sensitive clean release adhesive interposed between said Buna-N rubber and said sponge rubber.
5. In combination in a polishing organization, a poromeric material having a plurality of vacated, formed, apertures in said poromeric material separate from the natural properties of said poromeric material, and means for urging work pieces to be polished into :bearing contact with said poromeric material.
6. The combination as in claim 5 further comprising a layer of compressible material interposed between said poromeric material and said urging means.
7. The combination as in claim 6 wherein said compressible material comprises sponge rubber.
References Cited UNITED STATES PATENTS 671,130 4/1901 Darden 51401 804,853 11/ 1905 Ireson. 1,923,719 8/1933 Fuller 5l30'1 2,644,280 7/1953 ONeil.
OTHER REFERENCES Boot and Shoe Recorder Oct. 1, 1963, article titled The Story of Corfam, pp. 1 and 2 thereof.
HAROLD D. WHITEHEAD, Primary Examiner US. Cl. X.R. 51-401; 161160