US3007189A - Cushioned polishing disc - Google Patents

Description

Nov. 7, 1961 s. P. CRANE ,00 ,1

CUSHIONED POLISHING DISC Filed Oct. 21, 1957 24 INVENTOR.

Samuel P Crane Z TTORNEY United States Patent f 3,007,189 CUSHIONED POLISHING DISC Samuel P. Crane, Great Neck, NY. R. 0. Kent Corp., 132 W. 31st St., New York 1, N.Y.) Filed Oct. 21, 1957, Ser. No. 691,348 8 Claims. (Cl. 230) This invention relates to polishing buffs in the form of flexible discs or pads intended to be secured to the rapidly rotating head of a polishing machine for polishing surfaces of various shapes such as the newly painted metallic surfaces of an automobile.

Such polishing discs are frequently made in the form of a pile fabric having a pile of lambs wool backed with or based on a sheet of relatively hard canvas for strength and dimensional stability, the disc being provided with a central hole for attachment to the rotatable head of a manually controlled motor-driven polisher. The wool pile normally projects outwardly to some extent beyond the peripheral edge of the canvas base. While the disc is relatively new, the Wool pile remains relatively long, and besides its polishing function, the pile retains its cushioning function to a sufficient extent to prevent damaging pressure by the peripheral portion of the disc and particularly the edge of the canvas, upon the painted surface, as when said portion is accidentally or otherwise pressed into contact with an angularly disposed or concave area While polishing an adjacent area. However, when some of the wool pile has worn off, there becomes considerable danger that the diminished cushioning action thereof will excessively increase the cutting action of the disc and permit the disc to abrade or burn the paint, thereby necessitating repainting of the burned area. Fur thermore, the shortened or Worn pile no longer remains effective to prevent the relatively hard canvas from burning the paint on surfaces with which it may accidentally come into contact.

Attempts have been made to supplement the cushioning action of the wool pile in various ways and with varying degrees of success. For example, relatively soft permanent or detachable pads on the head of the polishing machine have been tried. However, such auxiliary pads are expensive and in order to last a reasonable length of time and thereby to justify the cost thereof, they must be made durable enough to withstand hard wear and consequently in practice cannot be made soft enough for adequate cushioning action. If so made, the needed softness would militate against durability. Even an auxiliary soft pad backed with a more resistant backing has proven to be too costly and too inconvenient to manipulate for adoption by the industry.

The present invention therefore contemplates the provision of an effective but inexpensive soft resilient cushioning foam backing member directly and permanently secured in face to face relation to the back sheet of a wool pile disc in such a manner that the disc can be safely used for a much longer period than is otherwise possible, without danger of excessive abrasion Or burning of the painted surface to be polished either by the operating surfaces or the edge portion of the disc.

The invention further contemplates the provision of a polishing disc having a permanently attached protective and reinforcing cushioning back as an integral part of the disc, the back adding to the useful life of the disc not only by serving as a reinforcement of the pile but also by assuming part of the cushioning function of the pile, and being discardable therewith as a unit only when the pile is worn out, and without significant loss.

The invention further contemplates the provision of a polishing disc carrying its own efficient cushioning ma- :terial whereby the proper cushion is always present and at hand without the need for experiment or inspection, re-

3,007,189 Patented Nov. 7, 1961 pair or replacement, or separate attachment of the auxiliary cushion to the head of the polishing machine, the cushioning material or backing being so shaped as to protect the canvas edge of the disc and to prevent said edge from exerting too great a cutting action on a surface toward which it may accidentally be pressed, so long as the wool pile at the edge is long enough to perform its polishing function.

The various objects of the invention will be clear from the descripion which follows and from the drawings, in which:

FIG. 1 is a fragmentary bottom plan view of one form of the invention showing one half of the disc and the permanent foam back thereof.

FIG. 2 is a vertical sectional view thereof showing in dash-dot lines the stud and nut securing the disc to the head of a polishing machine and the shape assumed by the central portion of the disc when the disc is so secured to the machine.

FIG. 3 is a vertical sectional view of a modified form of the invention wherein the cushioning back is recessed for the reception of the head of the polishing machine.

FIG. 4 is a similar fragmentary view of another modified form of the invention similar to that of FIG. 3 but employing a backing sheet for the foam layer.

FIG. 5 is a fragmentary elevational view, partly in section, of a surface being polished showing the polishing disc and polishing machine in the positions assumed thereby when polishing a concave or angular surface.

FIG. 6 is an enlarged fragmentary sectional view of the disc showing the flexing action of the edge portion of the cushioning layer when protecting an adjacent s ur-face.

Throughout this specification, the term wool pile is used for convenience to designate not only the types of wool piles now in customary use for the front portions of polishing discs, but such term is also intended to designate any fabric or textile suitable for the polishing layer and of substantial thickness. It will therefore be understood that the polishing fibers may be other than wool, or admixtures of other yarns such as nylon or the like with Wool or other suitable materials without wool, and that the fibers may be held together in any suitable manner other than in a pile, as for example, in the form of knitted, Woven or felted fabrics or textiles, all of which are intended to be included in the term wool pile.

In the practical embodiment of the invention shown herein by way of example, the polishing layer 10 may be of any of the usual types wherein wool or other fibers or tufts 11 are secured together in any suitable manner, as for instance to project from a canvas or the like back sheet 12. In the form shown as a pile, the outermost diameter of the pile is greater than that of the back sheet, the fibers or tufts 11 projecting outwardly over the edge of the sheet 12. A hole as 13 is made at the center of the back sheet for the passage therethrough of the shank of a suitable threaded stud projecting from the head of the polishing machine. The fibers are omitted from the sheet 12 over a sufficient area surrounding said hole, to accommodate the nut or other fastening member which engages the stud and serves to engage and secure the disc removably to the head of the polishing machine shown in FIG. 5.

lnstead of the usual flat backing sheet, the sheet 12 of a distinctive shape is employed. To attain said shape, the outer peripheral portion of the sheet is bent as by heat, moisture and pressure into, and retained in, the outwardly convex form shown in FIGS. 2-4. However, the central portion of the disc is shown as normally substantially flat in that form of the invention shown in FIG. 2. At said central portion surrounding the hole 13, the wool or other polishing material is omitted from p the sheet 12 so that the securing nut may act directly against the sheet in a manner which is Well understood.

To attain the desired supplementary cushioning action, the cushioning layer 16 in the general form of a disc, is added to the polishing layer to form the rear portion of the polishing disc. Said layer is made of a suitable inexpensive flexible foam material such as flexible synthetic resin foam of the polyurethane, polyethylene, vinyl or the like types. The front surface 17 of the cushioning layer is made preferably, thought not necessarily, slightly convex especially at the outer peripheral portion thereof, while the rear surface remains planar in the form shown in FIG. 2. Said foam cushioning layer is made of lesser outer diameter than that of the sheet 12 and is arranged entirely within the peripheral portion of the wool pile to permit the edge portion of said sheet 12 to be shaped convexly as previously described in order to extend past the outer edge of said layer and to cover said foam layer. By so shaping the outer edge portion of the back sheet, the wool pile portion 20 at the edge of the polishing disc is carried around the edge of the back sheet to a much greater extent than is possible were the back sheet fiat throughout, whereby greater protection is afforded against excessive cutting action by the edge of the polishing disc. A greater density of fibers than elsewhere is preferably concentrated at the edge portion of the disc, which is the part subjected to the greatest wear. The useful life of the disc is consequently prolonged.

It will be understood that the back sheet may be omitted in certain types of the wool pile, but where said sheet is employed, the rear surface therof is preferably adhesively secured to the front surface of the auxiliary foam layer 16. Consequently, said layer reinforces the polishing layer 10 and aids in maintaining the convex shape and the dimensional stability of the back sheet and of the polishing layer or wool pile, functioning for that purpose similarly to the action of an additional stiffening sheet or layer of canvas which is frequently used as a reinforcement in such discs. By selecting flexible foam material of the requisite softness, stiffness and thickness for the layer 16 and employing a polishing layer 10 of the proper material, it becomes possible to use the double or single sheet 12, or to use a lighter and less expensive fabric for such sheet than would otherwise be required, by reason of the substantial reinforcing properties of the foam layer. When, as shown by the dash-dot lines of FIG. 2, the disc-securing nut is tightenend against the central portion of the sheet 12, said portion is depressed while the corresponding central portion of the foam layer 16 is highly compressed. The fibers surrounding the central portion of the disc are consequently bent toward the center line of the disc to fill the otherwise empty space at that area.

Should the wool pile become considerably worn as it will in time after use, thereby increasing the danger of excessive frictional heating of the painted surface of the work, cushioning properties lost by the worn pile are materially compensated for by the foam layer 16 which permits the relatively hard canvas back sheet 12 to yield under excessive pressure by compressing the foam material sufficiently to prevent burning the paint during the polishing operation. The operator of the machine can depend on the presence of the requisite cushion merely on the single operation of securing the polishing disc to the head of the machine without the need for first selecting an auxiliary separate cushioning pad and then fastening the pad as a distinct operation to the head of the machine before finally securing the polishing disc to the machine.

In that form of the invention shown in FIG. 3, the foam layer may be thicker at its outer periphery than elsewhere to provide a rearwardly projecting rim or flange 26 surrounding the preferably circular central recess 27 therein. When the back sheet 28 for the wool pile is used as shown, it is continued or lengthened to extend rearwardly over the front surface of the member 25 and the rim 26 thereof, whereby a substantial area and volume of the wool pile may be arranged to protect the edge of the canvas sheet or of the polishing head from exposure or near exposure at the edge of the polishing disc, and more cushioning protection is afforded for the edge of the disc. At the central portion of the foam material is omitted to form a central recess in said layer. The recess is shaped to conform to the shape of the correspondingly depressed central portion 14 of the back sheet 28. Said portion 14 is fitted into and adhesively secured to the wall of the recess.

As shown in FIG. 4, to attain still greater form and dimensional stability for the disc than is possible when a single back 28 and the foam layer are used by themselves, the foam layer may be additionally reinforced by another backing layer or sheet of canvas or suitable plastic as 30. A double thickness of backing material is thereby provided, such thicknesses being in contact with each other at the annular area surrounding the hole 13 and at the portion 14 of the sheet 28 which is devoid of fibers.

Referring to FIGS. 5 and 6 wherein a portion as 24 of a typical reentrant surface such as the hood of an automobile is shown, the edge of the polishing disc, if unprotected, would ordinarily damage the paint unless extraordinary precautions were taken. However, with the protected and cushioning edge shown, pressure on the edge causes the rim 26 or other edge part of the foam layer to be compressed and doubled back partway on itself, interposing additional wool tufts or fibers between the work and the back sheet 12 or 28 and 30 of the disc, and thereby preventing such damage. The life of the disc is also prolonged because the wool pile may be used until worn down relatively close to the back sheet, sufficient cushioning action being inherent in the foam layer to make up to a considerable extent for the loss of such action in the wool pile.

It will now be seen that the various objects of the invention have been adequately and simply attained and an inexpensive but well cushioned and edge protected polishing disc has been provided which it self contained and which requires no separate auxiliary pads or cushions to be interposed between it and the head of a polishing machine.

While certain specific forms of the invention have herein been shown and described, various obvious changes may be made therein without departing from the spirit of the invention defined in the appended claims.

I claim:

1. A polishing disc and protecting cushion combined to form a single unit and comprising the combination of a relatively thick pile of polishing material having cushioning properties, the peripheral edge portion of the pile being permanently dished, a flexible backing sheet for the pile, and highly compressible means forming a permanent part of the unit inseparable from the backing sheet and constituting the sole means for permanently supplementing the cushioning properties of the pile and for increasing the cushioning properties of the disc beyond that afforded only by the pile and backing sheet, for reinforcing the pile, for increasing the dimensional stability of the pile and for maintaining the pile in the dished shape thereof, said means comprising a sheet of resilient cellular material having a convex peripheral portion adhesively secured to the backing sheet, the pile and the sheet of cellular material having a central opening therethrough, the backing sheet being depressed into the opening of the sheet of cellular material and being adhesively secured to the Wall of the opening to line the opening wall, the inner peripheral portion of the backing sheet extending inwardly past said Wall and having a central hole therein.

2. The combination of claim 1, a second flexible backing sheet secured to the rear face of the sheet of cellular material and extending inwardly past the wall of the opening and in contact with the inwardly extending portion of the first mentioned backing sheet, said second sheet having a central hole therein in registration with the hole of the first mentioned backing sheet.

3. A self-cushioning polishing unit comprising a relatively thick polishing layer having a central opening therethrough, a first canvas back for the layer having an inner peripheral portion projecting inwardly into the opening, a disc of foam polyurethane secured to the back in face to face relation thereto, and a second canvas back on the rear face of the foam disc having an inner peripheral portion secured to the inner peripheral portion of the first back.

4. A self-cushioning polishing disc comprising a. flexible polishing layer and a flexible supplementary cushioning layer of resilient cellular material bonded to and reinforcing the polishing layer, the cushioning layer having a rearwardly projecting rim surrounding a recess in the rear surface of said layer, said recess being adapted to receive the head of a polishing machine, a back sheet for the polishing layer and a second back sheet bonded to the rear surface of the cushioning layer and to the first mentioned back sheet at the central portion of the disc.

5. A self-cushioning unitary polishing disc comprising a fibrous backed Wool pile having a permanently dished rearwardly turned peripheral portion, and combined cushioning, form-maintaining and dimension stabilizing means constituting a substantially inseparable part of the disc and the only means for maintaining substantially unchanged the rearwardly turned position of said peripheral portion and for cushioning the pile, said means comprising a circular layer of resilient cellular material permanently secured to the rear face of the backed pile and having a permanently convex peripheral portion secured to the adjacent dished part of the backed pile.

6. A unitary polishing disc having a peripheral portion of dished shape and having a central portion provided With a central opening, said disc comprising a wool pile, a circular dished backing sheet for the pile of substantially the same diameter as that of the disc, and a rear sheet secured to the backing sheet having a permanently rearwardly turned peripheral edge portion in contact with and secured to the rear surface of the peripheral portion of the backing sheet and constituting the sole means for maintaining the rearwardly turned position of the peripheral portion of the disc.

7. A unitary self-cushioning polishing disc having a peripheral portion of dished shape and having a central portion provided with an opening, said disc comprising a Wool pile, a circular fabric backing sheet for the pile of substantially the same size as that of the disc and having a central opening therein and having a rearwardly depressed area surrounding the opening and also having a dished peripheral portion secured to the rear face of the pile, a second fabric sheet having a central opening therein in registration with the opening of the first mentioned sheet, and means arranged between and secured to the sheets for holding said sheets against relative displacement throughout the area of the second sheet and having a rearwardly turned peripheral portion for maintaining the peripheral portion of the disc in a rearwardly turned position.

8. A preshaped unitary flexible polishing disc having a preformed peripheral portion of dished shape and having a central portion provided with a central opening, said disc comprising a Wool pile, a circular backing sheet secured to the pile and having a rearwardly turned peripheral portion terminating substantially at the edge of the pile, and a circular rear sheet secured to the backing sheet and substantially coextensive therewith, the rear sheet having a permanently rearwardly turned peripheral edge portion secured to the rear surface of the peripheral portion of the backing sheet and constituting the means for maintaining the preformed rearwardly turned position of the peripheral portion of the disc.

References Cited in the file of this patent UNITED STATES PATENTS 336,695 Byers Feb. 23, 1886 1,998,244 Lang Apr. 16, 1935 2,227,588 Kemp Jan. 7, 1941 2,650,385 Michel Sept. 1, 1953 2,934,775 Bergstrom May 3, 1960

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