US3043063A - Rotary tool - Google Patents

Description

July 10, 1,962 R. o. PETERSON 3,043,063

- ROTARY Toor.

ed Dec. s, 1958 s sheets-sheet 1 ROTARY TOOL 5 Sheets-.Sheet 2 INVENTOR. 2055A/ 0. PffkLO/V M. i w

July l0, 1962 R. o. PETERSON Filed Dec. 8. 1958 July 10, 1962 R. o. PETERSON 3,043,063

ROTARY TOOL Filed Dec. 8. 1958 5 Sheets-Sheet 3 INVENToR. J PI/V O. PmR/V 25 om; MM

This invention relates as indicated to a rotary tool having an abrasive or labrading action, and more particularly to rotary abrasive buffing tools having abrasive material in granular or powdered form adhered to or incorporated in the fabric of which such buff is comprised and to other rotary tools wherein the Iabrading elements are carried by liexible sheet material.

Rotary buffs are employed in a wide variety of surface finishing operations and may be required either to remove a considerable amount of material from the work surface being acted upon or merely to obtain a high finish or gloss on such surface. Perhaps the best known form of bui merely comprises an assemblage of textile fabric discs secured together in side-by-side relationship and provided with an appropriate hub or like supporting means for mounting on an arbor. Standard abrasive and polishing materials such as emery, carborundum and rouge may be applied to the rotating buff in order that the latter may in turn apply the same to the surface to be conditioned. Certain waxes, oils, and greases may be incorporated with the abrasive or polishing material in order that the latter may be at least temporarily adhered to the Working surface of the bul and not immediately thrown off and dispersed. This arrangement, of course, makes for somewhat messy working conditions and the work-piece must frequently be subsequently treated .with a solvent or other cleansing agent to remove such wax, grease or oil therefrom. inasmuch as the abrasive material is thus ordinarily intermittently applied to the rotating buf, it is obvious that the surface conditioning characteristics of the latter will be far from uniform and the work-piece or work-pieces therefore non-uniformly treated.

Merely to form the buif of fabric discs having Iabrasive adhered to one or both sides thereof has not proven a satisfactory solution for the reason, among others, that a very rigid wheel results which does not have .the resilience and soft yielding action frequently desired in a buff. It is this yielding action Which permits a buff to be forced against -a work-piece Without danger to the latter or to the buff but at the same time obtaining desired penetration into hollows and conformance to irregular contours of the article being buied.

It is accordingly an important object of my invention to provide an abrasive buif which will be iiexible and adapted to conform to the contours of a work-piece being acted upon.

Another object is to provide a rotary buff formed by circularizing the bul material for mounting upon a hub or like support, which bui will have an abrasive working face.

Still another object is to provide a rotary tool having hard abr'ading elements carried by exible sheet material for engagement with the work in a yieldingly supported manner and with a minimum of vibration and stress concentration.

Other objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

ln said annexed drawing:

FIGS. 1 and 2 illustrate a rotary buff of a type generally similar to that disclosed in Murray Patent No. 2,140,208 but modified by the inclusion of abrasive areas in the manner taught `by my invention;

FIG. 3 is a fragmentary detail view of a step in the manufacture of such buff showing a modiied disposition of the abrasive areas;

FIG. 4 is a view similar to FIG. 3 but showing a different form of abrading element secured to the flexible sheet material;

FIG. 4a resembles FIG. 4 but shows utilization of alternate metaland granular abrasive areas;

FIG. 5 is a perspective view of a different type of tool embodying the principles of my invention Where hard thin sheet material abrading elements are mounted on exible sheet material strips secured in long lead helical conformation;

FIG. 6 is a diagrammatic illustration of one method of forming the strips of FIG. 5;

FIG. 7 shows a sheet of exible fabric to which abrasive has been bonded in certain areas preparatory to forming abrading fingers comprising a further embodiment of my invention;

FIG. 8 shows the sheet of FIG. 7 folded or pleated to form such novel fingers;

FIG. 9 illustrates the employment of the lingers of FIG. 8 in the continuous manufacture of brush strip;

FIG. 10 is a side elevational view of a section of such strip; 'and FIG. l1 is a transverse section taken on the line 11-11 on FIG. l0.

Referring now more particularly to such drawing and especially FIGS. l and 2 thereof, the method of forming a rotary bult as illustrated in such ligures is generally similar to that disclosed in Murray Patent No- 2,140,208. A continuous strip 1 of fabric buff material which may, for example, be of bias cotton sheeting has printed thereon a series .of transverse stripes 2 of powdered or granular abrasive material such as emery which may be adhered to the fabric by means of an appropriate adhesive such as one of the resin base adhesives commonly employed for such purposes. 'These abrasive stripes 2 will preferably extend to one edge of the fabric strip 1 which is to form the outer working face of the buff, but the other ends 3 of such stripes will be substantially spaced from the other edge of the fabric strip, commonly from onequarter -to one-third of the width of such strip from such edge and sometimes even one-half the width of such strip from such edge. Furthermore, such abrasive stripes, while preferably spaced from adjacent stripes throughout their length as shown, may desirably be somewhat wider in the regions adjacent the fabric edge to which they extend and will taper slightly to the other end of the stripe. These abrasive stripes will be applied to one side of the fabric strip only or to both sides of the same, but if applied to both sides, the stripes on each side should be directly opposite one another or staggered so that they do not overlap, thereby facilitating the pleating operation.

The strip of buff material thus treated will then be folded in accordion pleats along transverse lines such as 4 between each such abrasive stripe and the adjacent stripe and circularized into a helix as shown in FIG. l with the edge of the strip to which the abrasive stripes v2 do not extend forming the inner periphery of such helix. Stitching 5 may be employed to assist in securing the folded or pleated material in such condition, such stitching being provided in the non-abrasive edge portion of the fabric and therefore adjacent the inner periphery aoaaoes 3 of lthe circularized material. Alternatively, a suitable adhesive may be employed for this purpose.

A single turn 6 of such circularized pleated material (FIG. 2) may be secured in a binding ring 7 of the general type disclosed in Patent No. 1,922,108 or in any other well-known type of -annular binding ring or hub. It will thus be seen that an annular rotary buff element has been provided having abrasive material applied thereto in a manner which neither interferes with the manufacture of the same nor deleteriously affects the desired resilient characteristics of the finished buff. VThe folds or pleats 4 effect a transverse disposition of the buff material which prevents streaking of the work in use and also assists the outward ow of air which provides a Ventilating and cooling action. The abrasive stripes 2 applied to the transverse panels of the buff material accordingly likewise extend transversely of the buff face like so m-any labrasive fingers attachedY to adjacent lingers at alternate edges. 'Ihese abrasive regions or panels, of course, extend radially ofthe tool and lie in planesparallel to the axis of the latter. The abrasive is accordingly applied to the work in a most effective manner and is supported and retained by `the buff material more satisfactorily than is generally the case when abrasive is adhered to buff fabric lying in a plane transversely of the axis of the tool. The fact that a non-abrasive area intervenes between adjacent abrasive stripes not only assists in the initial formation of the tool as shown in FIGS. l and 2 of the drawing, but also affords a greater degree of exibility in the finished buff than would otherwise be the case. Since the inner peripheral portion of the buif material does not have abrasive thereon, it -is possible to compact-such material to permit a more dense outer working buff face than would otherwise be possible.v Of course, the buff may ordinarily be discarded when it has been worn down to such inner nonabrasive region.

The provision of such inner non-abrasive regionV not only has the advantagesindicated, and avoids waste of unused abrasive material, but also provides =a relatively flexible' and yielding inner lportion of the buff. Accordingly, when such buff is used on a work-piece having an irregular surface, it is possible by application of pressure to cause the buffto yield and conform to such irregularities and thereby achieve a uniform and complete surfacefinishing action. y

Referring now more particularly to FIG. 3 of the drawing, another modification of my invention is there illustrated wherein abrasive stripes 8 are applied to the strip 1 atl spaced intervals withthe spaces therebetween being of the same width between folds 4 as the panels bearing such abrasive stripes. buff material is pleated as above described, no two abrasive areas will `directly oppose one another. A more flexible and less abrasive buff is thus produced in whichthe Y shedding of abrasive is minimized since there will be no rubbing of opposed abrasive surfaces in use. Of course, the opposite side of strip -1 may be provided with abrasive Consequently, when the strip of o and greases such as those based on mutton tallow. Ordistripes in a similarmanner, and such stripes may be on alternate panels to those panels having abrasive stripes on their other sides.

The term fabric as employed herein and in the claims is intended to include any suitable sheet material whether textile or imperforate plastic sheet, for example. rThus,

o cotton cloth, nylon (polyamide resins), Plioflm (rubber hydrochloride), or certain Ytypes of paper sheet material are entirely suitable for use in embodiments of my invention for certain purposes, and other natural or manufactured fiber materials may likewise be employed.-

While many types of adhesives may be employed-to secure the abrasive to the buff fabric, depending on the particular application, the following may be mentioned: animal glues, glycerinev phthalate resin compositions such as Dulux, Bakelite resin compositions, cellulose base resin compositions, casein glue compositions, and. even wax compositions such as those based on'cerotic acid wax narily, adhesives are prefered which have relatively little stiening effect on the fabric and do not tend to smear the work, or at least may be readily removed from such work. The adhesive should not be too brittle but should stand up under impact in use. When Vsynthetic plastic sheet material isV employed as the buff fabric, the abrasive may be adhered by pressing into the plasticV surface, with application of heat or solvent where appropriate to bond the abrasive grains thereto.

Adhesive will desirably be printed on the fabric by the well-known roller process Vand the abrasive then dusted thereon. In this manner, the abrasive will lbe secured only to the precise areas desired and all excess is readily blown away. lf desired, however, the abrasive and adhesive can be applied together.

Among abrasive materials suitable for diiferent operations are: aluminum oxides such as Alundum and Aloxite, -silicon carbide (carborundum),V precipitated aluminum oxide, emery, rouge, pumice (Tripoli), sharp sand, bauxite, and diatomaceous earth. Fabric having abrasive areas may also be provided byV interweaving abrasive strands which may be of the type taught in Radford Patent No. 2,328,998, for example.

Since the abrasive stripes preferably do not extend radially inwardly to the inner periphery of my new rotary buffs, not only do I obtain improved ventilation with proper density at the working surface (despite radial spreading) but also the buff fingers are attached by relatively exible means lto the back or the like. The resultant rotary surface-conditioning tool preserves the desirable attributes of the buff, with a much enhanced abrasive action.

It will be seen from the foregoing that l have provided a type of abrasive buff construction which is both exiblc and cool in operation and which is particularly adapted for machine manufacture. The various radially extending folds and pleats do not expose cut fabricedges so that raveling and premature dissolution of the Abuff fabric is substantially eliminated. Y n

While the buff strip of my invention may commonly be circularized to form a helix or single turn annulus with the buff material extending generally radially therefrom, straight lengths of my new buff Vstrip may also be employed arranged parallel to the arbor on which they are supported or in long lead helical form. Buffs and brushes of this general conformation are, of course, already known in the art. Likewise, a length o f buff strip may be circularized with the buff material extending in a generally axial direction rather than radially to form a cup-shaped buliingV tool. VFi`his general type'of4 construction is also weil known and oneV form is illustrated in Nelson et al. Patent 2,626,414. Y

A variety of hubs, adapters', etc., which may be of cardboard, metal, wood, or plastic materials, well yknown in the art, may be employed to mount therannular buing tools upon an arbor or mandrel. Ventilating adapters such as those disclosed in my prior Patents/No. 2,409,309, No. 2,320,384and No. V2,37l76,l85, for example, may desirably be employed. Clamping end plates having provision for entry of cooling air within the inner periphery of the buff should also `be utilized in conjunction therewith asvtaught in'such prior patents.

Certain benefits of my invention may be obtained when the strip of fabric 1 is coated uniformly with abrasive except in the region adjacent one edge which is to form the inner periphery of the tool (see FIG. 3 of the drawing in my co-pending application Serial No. 329,791 led January 6, 1953), now abandoned. While a less flexible buff is then produced and manufactureisV somewhat more ,diiiicult, a tool is nevertheless obtained in which a relatively dense working surface is achieved, ventilation is facilitated, and the radially inner non-abrasive portion permits a degree of inwardly Vyielding action.Y VI ordinarily much prefer to apply the abrasive in stripes, however, with the folding of the fabric taking place intermediate such stripes, the yielding, exible characteristics of the buff being thereby enhanced.

The sheet material strip 1 may be slit part way in from the outer peripheral edge of the buff along the lines 4, if desired, so that the fingers bearing the abrading regions will extend more or less independently and more nearly in radial planes parallel to the axis of rotation. The pleats will often be retained, however, since they keep cut fabric edges to a minimum, preventing raveling in the case of textiles, for example, and also tending to skew the fiat abrasive regions somewhat relative to the axis of rotation. As used herein and in the claims, the term planes generally parallel to the axis of the tool is intended to include such skewed planes (but not normal to the axis of rotation as are the layers of buff material in the usual prior art buffs).

In my co-pending application Serial No. 232,036 filed June 16, 1951, now Patent No. 2,879,631, dated March 31, 1959. I disclose certain novel sheet metal brush material in the form of thin flat fingers which may be of extremely hard material such as Hadeld steel, for example. In accordance with my present invention dat fingers of such hard sheet material may be adhered or otherwise secured to the much more flexible buff fabric, for example, in place of the granular abrasive regions above described, thereby providing an abrading tool having the advantages previously explained but of quite a different character in its action on the work.

Referring now more particularly to FIG. 4 of the drawing, a plurality of thin sheet metal panels or lingers 9 may be adhered or otherwise firmly secured to the fabric strip 1 at spaced intervals'therealong arranged in the same general manner as the abrasive regions 2 of FIG. l so that when suc-h strip is pleated intermediate the ngers at 4, a rotary tool is produced similar to that of FIGS. l and 2 but with the outer working portion of the tool being largely formed by the outer ends of the sheet metal ngers 9. Obviously, such fingers lie in radial planes generally parallel to the axis of rotation of the tool and are adapted to have a strong cutting or shaving action on the work. This tool may be further modified 'as by securing such sheet metal fingers 9 to alternate panels 10 of the strip 1 with abrasive stripes 2 adhered to the intermediate panels (FIG. 4a). Vvfhen the strip is then pleated and circularized, there will be only one-'half as many metal ngers comprising the working face of the tool, with hard granular abrasive regions interposed therebetween.

In FIG. 5 there is illustrated another form of rotary tool comprising a rotatable support or hub 11 having channelform back members such as 12 mounted thereon in long lead helical conformation with a plurality of layers of flexible sheet material 13 secured therein and extending therefrom. The sheet metal fingers 9 are secured to such strip 13 similarly to strip 1 with the inner ends of such metal fingers 9 being spaced from the back 12 and the outer ends extending to the working surface of the tool. Lengths of strip such as those formed by channel back i12, fabric 13 `and fingers 9 may conveniently be produced in the manner taught in my prior Patent No. 2,303,386 and diagrammatically illustrated in FIG. 6 of the drawing where two rows of ngers 9 are secured to a strip of fabric 13 and such strip placed upon a sheet metal backing strip 12. Wire or like elongated retaining element 14 is superimposed upon fabric 13 centrally of the same and sheet metal strip 12 `and the latter formed to channel shape. The sides of the channel 12 may be provided with inwardly protruding teeth adapted to penetrate the fabric and overlie wire 14 to `assist in securing the latter -in place in the manner shown in my prior Patent 2,303,386 or the sheet metal channel may be formed with a relatively narrow neck in well-known manner, serving the same general purpose.

While the tool of FIG. 5 may appear to be rather different in conformation from the forms of my new tool 6 Y previously described, it will nevertheless be noted that the flat sheet metal ngers 9 are arranged in generally radial planes generally parallel to the axis of rotatable support 11. As is apparent from they foregoing, the rotatable tools described may utilize the sheet metal regions or granular abrasive regions as may be desired for the work at hand.

It will generally be preferred that the fabric strips 1 and 13 'be continuous not only to facilitate manufacture of the tools but also to maintain the abrasive regions or lingers in proper relationship in the finished tool. If desired, however, such strips may be slit intermediate the abrasive regions or fingers to make such fingers substantially independent of one another and therefore considerably more fiexible. Conversely, when a relatively rigid structure is desired, the several layers of strips `13 comprising the long lead helical elements of FIG. 5 may be stitched or bonded together as at S adjacent the backs 12 and even throughout their entire inter-faces for maximum rigidity. In the latter type of tool it will sometimes be desired to incorporate granular abrasive in the adhesive so that in effect a sandwich of thin metal sheets and granular abrasive is produced. (See my co-pending application Serial No. 232,036 led June 16, 1951, now Patent 2,879,631.)

The ngers 9 Iare shown as being relatively long and narrow, and this will ordinarily be preferred, but they may in some circustances be much wider than shown. The fabric to which the sheet metal fingers are secured may be considerably more flexible than such fingers and accordingly impart `a different action to the latter in use. Moreover, the usual concentrations of vibrations and stresses incurred when metal bristles or the like are seated directly in a back element such as channel 12 are avoided. In the FIG. 5 type of tool it will generally be preferred that the abrading regions or lingers, whether of granular abrasive or sheet metal, do not taper appreciably along their length.

Obviously, a great variety of sheet metal ngers 9 may be employed in addition to Austenitic manganese steel (Hadlield steel) including Monel metal and silicon bronze, for example. The metal fingers 9 maybe coated with a plastic such as rubber (if operating temperatures not too high), neoprene (polychloroprene), Hycar (modified copolymers of butadiene and acrylonitrile), nylon (polyamide resins), vinyl plastics (vinyl polymers and copolymers), and melamine resins (melamine-formaldehyde reaction products). Such plastic coating yassist in protecting the metal from corrosion.

When using hard sheet material fingers 9` as above described, a scraping action is obtained quite different from the action of the ordinary wire brush material and such action has been found to be most efficient in removing soft metal from weld surfaces of castings, for example, without the usual tendency of the brush material also 'to enter into the weld hollows and therefore remove more metal than desired. Tools of this type are also effective in removing scale from billets, steel strip, and the like.

In the FIGS. 1-4 embodiments it will be seen that the abrasive or abrading ngers may be closely enough spaced so as to afford a fairly continuous working surface at the outer periphery of the tool. Since the abrasive or sheet metal regions or fingers do not extend entirely to the inner periphery of the tool the inner portion need not be excessively dense to achieve the desired density at the working face. While such lingers do not lie in planes normal to the `axis of rotation of the tool they may nevertheless often be skewed out of complete parallelism with such axis. They present themselves at least partially flatfwise rather than entirely edgewise to the work when the tool is rotated.

One method suitable for applying hard metal areas to more flexible sheet material such as cloth is to spray molten metal thereon utilizing well-known procedures and commercially available equipment.

' Referring now more especially to FIGS. 7-11 inclusive of the drawing, a modiiied embodiment of my invention. is there illustrated. A sheet of ilexible fabric material l5.

has applied and adhered thereto certain spaced regions 16, y 17, 18 and 19 of granularabrasive, suchY regions extendY ing to the outer edges of the rectangular piece of fabric but spaced at their inner ends from the center line 2t?. Similar regions of abrasive material 2l, 22, 23 and 24 may be bonded to the opposite side of the sheet in similar regions opposed to non-abrasive panels on the near side of the sheet (FIG. 7). Sheet 15 may then be pleated as illustrated in FIG. 8 to form an elongtaed strip with the abrasive areas inside, the sheet having been pleated intermediate the same. Moreover, when such abrasive areas are spaced as shown in FIG. 7, for example, they will be opposed to non-abrasive areas when the sheet is thus pleated, `and consequently no two abrasive areas will rub against one another. A plurality yof flat pleated lingers 25 may be placed in close side-by-side relationship transversely of a sheet metal backing strip 26 in the manner taught in my prior Patent No. 2,303,386 andan elongated retaining element such as Wire 27 placed thereon longitudinally of such strip. When `the strip is now formed to channel shape withV the strips 25 being thereby folded about wire 27 and the latter secured Within the channel by teeth 28 punched in from the channel sides, the respective ends of the pleated strips 25 will now extend in the same general direction in side-by-side relationship. Brush strip of this type may be circularized to form annular or helical elements or such teeth may be mounted in the general manner illustrated in FIG. 5, for example.

It willV be appreciated that a continuous strip of flexible sheet material may have stripes or regions of abrasive applied thereto in the indicated pattern andrthat such strip may then be cut into sections comparable :to that shown in FIG. 7. The abrasive areas will ordinarily preferably be of general rectangular shape as shown in FIG. 7 when medially of the pleated sheet, preferably both the inner and outer faces of such folded pleated sheet being uncoated throughout Ya band extending about and along the 'median fold. When such polishing elements are assembled into an elongated brush strip as shown in FIGS. 9 and 10 to mount the same, such lbrush strip may thereupon be circularized in Well-known manner to form the resultant ngers are to be employed in a rotary tool Where they will encounter the Work generally flatwise, as in the case of the FIG. 5 tool. Where the brush strip formed therefrom is to be circularized, such abrasive areas may desirably taper somewhat toward the inner ends of Vthe fingers. As expalined above in connection with the other embodiments of the invention, the abrading material employed may be in the form of metal sheets or strips secured to the flexible sheet material inthe same regions indicated for the granular abrasive, such metal strips being cut from thin sheets or formed by spraying the molten metal directly on the fabric.

The pleated ngers 25 are self-Ventilating to a large degree in use and are, of course, relatively more'flexible in the region where joined to the supporting back than they are in their outer abrasive end portions. Since the abrasive is preferably confined interiorly of the pleated strip, relatively little is thrown oif and lost in use without having been effectively Vapplied to the Work. While, of course, the length and proportions of the pleated strips making up my novel buiiing or brushing fingers may vary over a wide range, the folded or pleated finger 25 may commonly have a width of from 1% inches to 1/4 inch. Instead of employing spaced regions of abrasive as shown in 'FIG 7, the entire outer end portions of the strip may be covered with abrasive material, particularly When such outer end portions are to be bonded together after the sheet has been pleated to FIG. 8 form. When thus bonded, opposed abrasive surfaces will not rub together in use with consequent premature loss of Y abrasive particles therefrom.

It will be seen that I have provided a novel abrasive wheel in which the abrasive material such as` granular abrasive particles or iiat sheet metal may be bonded to the surface of asheet of fibrous material such as cloth, such sheet being pleated as shown in FIGS. 7-11, for example,

' 'to form polishing elementsAwhich are thereupon folded Y being flexibly interconnected annular or helically wound units adapted to be seated upon a rotatable hub such as 11`of FIG. 5, for example. The abrasive coating will gener-ally preferably be of uniform thickness and may cover the entire sheet surface althoughrit is much preferred that the abrasive be altogether omitted in the region of the median fold, as indicated above, and also that the abrasive be lapplied in spaced regions facilitating pleating of the sheet, thereby to cause the relatively stift' abrasive coated portions to be interconnected by the more exible uncoated fold portions. Both the provision of the abrasive material and the pleats naturally have a rigidifying effect on the folded sheet lmaterial radially of the assembled tool. The pleats are contiguous and generally preferably fully overlap one another as shown. Obviously, :the radially outer edges of the pleats are adapted to be bent angularly with respect to the pleat when the abrasive Wheel is brought into contact with la Work-piece, lthe outer end portions of the pleats being bent over at an angle to the direction of rotation of the Wheel when contacted against the Workpiece.

When pleated sheet material such as that shown in FIG. 1 is circularized in the manner indicated and described, adjacent turns will, of course, tend to overlap one another somewhat so that the pleats of one turn only partially overlap the pleats or" a next adjacent turn. Whether a continuous strip is employed as shown in FIG.

- l or a seriesv of individual pleated lingers as shown in FIG. 10, the bui material may be relatively densely compacted Where it is mounted and secured to the central hub as it does not carry abrasive material in this region. An abrasive Wheel may accordingly be produced having a relatively dense outer working face.

yThis application is a continuation-impart of my copending application Serial No. 318,160 led November l, 1952, now abandoned and of Serial No. 329,791 tiled January 6, 1953, now abandoned, both of such latter applications in turn being continuations-inpart of application Serial No. 173,465 tiled July 12, 1950, now Patent No. 2,704,916.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided theY features stated -in any of the following claims or the equivalent of such be employed.

I therefore particularly point out `and distinctly claim as my invention:

l. A rotary surface-finishing tool comprising a central annular supporting member and a plurality of at sheet metal fingers extending radially therefrom `and lying in planes generally parallel to the `axis of rotation of said tool, said fingers being connected 4to said supporting member by more flexible sheet material and said lingers along their radially extending edges.

2. A rotary surface-iinishing'tool comprising a rotatable support and a plurality of contiguous at abrading sheet metal iingers extending generally radially therefrom to the outer periphery of the tool but with said ngers being spaced substantially outwardly fromsaid support and connected to the latter by more flexible material, and `said hat metal sheets lying in radial planes generally parallel to the axis of rotation of said tool. Y

3. A rotary tool comprising a rotatable support and iiexible sheet material extending radially therefrom and lying in planes generally parallel to the axis of rotation lof said support, and areas ofhard metal sprayed on the surface of said flexible sheet material spaced radially outwardly from said support, being connected to the latter by said iiexible sheet material thereby affording a relatively dense hard abrading outer peripheral portion of said tool yieldingly supported on said rotatable support by said flexible sheet material.

4. A rotary tool comprising a rotatable support and a plurality of generally at fingers of sheet material extending therefrom and lying in planes generally parallel to the axis of rotation of said support, said fingers being liexible in the regions adjacent said support, and sheet metal regions extending to the working ends of said iingers but spaced substantially from said support.

5. A rotary tool comprising a rotatable support and a plurality of individual generally dat fingers of sheet material extending therefrom and lying in planes generally parallel to the axis of rotation of said support, said iingers being iiexible in the regions adjacent said support and comprising sheets of flexible fabric longitudinally pleated to form generally dat elongated strips, said strips being folded at their mid-points and there secured to said support with their two end portions extending therefrom in general side-by-side relationship, and regions of hard abrading material on said iingers extending to the working ends thereof but spaced substantially from said support.

6. A rotary tool comprising a rotatable support and a plurality of individual generally fiat ngers of sheet material extending .therefrom and lying in planes generally parallel to the axis of rotation of said support, said fingers being iiexible in the regions adjacent said support and comprising sheets of iiexible fabric longitudinally pleated to form generally dat elongated strips, said strips being folded at their mid-points and there secured to said support with their two end portions extending therefrom in general side-by-side relationship, and stiff hard regions of granular abrasive secured to internal flat surfaces only of said pleated ngers opposed to non-abrasive surfaces thereof and extending to .the working ends of said ngers but spaced substantially from said support to aord a relatively exible connection therewith and thereby yieldably support the abrasive bearing portions.

7. A brush element comprising a support and ya plurality of individual generally dat flexible fingers extending therefrom, said fingers comprising sheets of liexible material longitudinally pleated to form generally flat elongated strips, said strips being doubled at their longitudinal midpoints and there secured to saidk support with .their two end portions extending therefrom in general side-by-side relationship, and regions of hard abrading material on tiat internal surfacesonly of said pleated fingers Iand extending to the working ends of said fingers but spaced substantially from said support to afford a relatively exible connection therewith.

8. A rotary buit comprising a continuous strip of ilexible bud fabric having a series of spaced transverse stripes of abrasive material adhered thereto and extending to one edge of said strip only, such stripes tapering to their other ends spaced a substantial distance from the other edge of said strip, said strip being folded in a series of reverse bends in the non-abrasive regions intermediate said abrasive stripes to form a series of transverse pleats, and said pleated strip being circularized with the edge thereof lto which said abrasive stripes extend forming the outer periphery and means securing the inner peripheral portion of said circularized pleated strip in such circularized pleated condition with the portions of such buff fabric bearing said abrasive stripes lying in generally radial planes parallel to the `axis of said buit.

9. A rotary buit comprising a continuous strip of flexible buit fabric having aseries of spaced transverse stripes of abrasive material adhered thereto and extending to one edge of said strip only, such stripes tapering to their other ends spaced a substantial distance from the other edge of said strip, said strip, said strip being folded in a series of reverse bends in the non-abrasive regions intermediate said abrasive stripes to form a series of transverse pleats, and said pleated strip being circularized with the edge thereof to which said abrasive stripes extend forming the outer periphery, stitching securing said strip in such pleated condition, and an inner metal annulus engaging and clamping the inner periphery of said circularized strip to support the same with the portions of such buff fabric bearing said abrasive stripes lying in generally radial planes parallel to the axis of said buff.

l0. A rotary surface-finishing tool comprising a large number of contiguous flat layers of radially folded sheet material having relatively hard, stiff yabrasive `regions extending to the outerperiphery of the tool and enclosed between closely adjacent layers of said sheet material, said layers extending radially from and in planes generally parallel to the axis of rotation of the tool to form an outer work-engaging face of substantial width and circumferential continuity and said layers being closely connected to adjacent layers throughout their radial extent.

l1. A rotary surface-nishing tool comprising a rotatable support and a plurality of contiguous Hat abrasive fingers extending generally radially therefrom, said iingers comprising exible sheet material having abrasive regions extending to the outer periphery of the tool but with said regions spaced substantially outwardly from said support, the portions of said lingers including such abrasive regions being of greater thickness than the non-abrasive portions adjacent said support and said sheet material iingers lying in planes generally parallel to the axis of rotation of said tool, and said abrasive regions occurring on one side only of each finger and alternated to prevent two abrasive regions being directly opposed to one another, thereby aording a relatively hard abrading outer peripheral portion of said tool yieldably supported on said rotatable support.

l2. A rotary tool comprising a continuous strip of flexible fabric having a series of spaced transverse sheet metal strips secured thereto and extending to one edge of said fabric strip only, the other ends of said sheet metal strips being spaced a substantial distance from the other edge of said fabric strip, said fabric strip being folded in a series of reverse bends in the regions intermediate said metal strips to form a series -of transverse pleats, said pleated fabric strip being circularized with the edge thereof to which said metal strips extend forming the outer periphery, and means securing the inner peripheral portion of said circularized pleated strip in such circularized pleated condition with said metal strips lying in generally radial planes generally parallel to the axis of rotation of said tool.

13. A rotary tool comprising a continuous strip of exible fabric sheet material having relatively stiff hard sheet material secured thereto adjacent one edge of said strip only, said hard sheet material being spaced a substantial distance from the other edge of said strip, said strip being folded in a series of reverse bends to form a series of transverse pleats, and said pleated strip being circularized with said hard sheet material extending to the outer periphery, and means securing said strip in such circularized pleated condition.

14. A rotary tool comprising a rotatable support and flexible sheet material attached thereto and extending radially therefrom and lying in planes generally parallel to the axis of rotation of said support, and sections of relatively stiff, hard abrading sheet material secured to said flexible sheet material and spaced radially outwardly from said support, being connected to the latter by said iiexible sheet material, and lying in the same planes, thereby affording a relatively hard abrading outer peripheral portion of said tool yieldably supported on said rotatable support.

l5. A rotary tool comprising a rotatable support and stiff, flat hard abrading fingers extending radially therefrom in planes generally parallel to the axis of rotation 11 of said support, said fingers being laterallyv interconnected along substantially their flexible and relatively non-abrasive material.

16. A rotary tool comprising a rotatable support and flat lfingers of sheet material extending radimly therefrom in planes generally parallel to the axis of rotation of said tool,` said fingers having hard granular abrasive regions'extendingto the working ends of said fingers but spaced from the other ends of said fingers and being laterally interconnected along substantially their entire length by much more flexible non-abrasive material whereby said fingers bearing such hard granular abrasive regions may move relative to one another when the tool is in use. K

17. VA brush element comprising a support and a plurality of individual generally fiat flexible fingers extending therefrom, each of said fingers comprising a sheet of flexible material longitudinally pleated to form a generally t fiat narrow elongated strip, said strip being secured to said support and extending longitudinally outwardly therefrom in general side-by-side relationship, and relatively stiff regions of hard abrading material on each of said fingers extending to the outer working ends thereof but spaced substantiallyV from said support to afford a rela- '25 said hub in the region of such latter fold, said elements Vhaving abrasive regions extending avmajor portion of tively flexible Vconnection with said support, thereby providing a relatively dense hard abrading working portion yieldingly secured to said support and each said narrow finger being capable of individual movement relative to the other said lingers.

18. A rotary surface-finishing tool comprising a central `annular supporting member and a plurality of fiat abrasive coated finger portions extending radially therefrom and lying in planes parallel tothe axis of rotation of said tool, said abrasive coated fingers being directly laterally interconnected along their radially extending edges by more fiexible uncoated portions.

19. In a polishing wheel having a hub for mounting polishing elements, the improvements in a polishing element therefor comprising a sheet of fibrous material, pleats in said sheet forming a wave-like edge, a fold medially of said pleated sheet whereby the sheet is folded upon itself, and an abrasive coating bonded on at least one face of the sheet, said face on which the coating is applied being uncoated throughout a band extending about and along the median fold. t

20. In a polishing wheel lhaving a hub for mounting polishing elements, the improvements in apolishing element therefor comprising a sheet of fibrous material, pleats in said sheet forming a wave-like edge, a fold medially of said .pleated sheet whereby the sheet is folded upon itself, and an abrasive face coating bonded Y on said sheet, the inner face of said folded sheet being entire length by much more Y 12 uncoated throughout a band extending about and along the medial fold.

21. In a polishing wheel having a hub for mounting polishing elements, the improvements in a polishing element therefor comprising Va sheet of fibrous material, pleats in said sheet forming a wave-like edge, a fold medially of said pleaded sheet whereby the sheet Iis folded upon itself, and an abrasive face coating bonded on said sheet, the outerY face ofY said folded sheet being uncoated throughout a band extending about and along the median fold.

22. In a polishing wheel having a hub for mounting polishing elements, the improvements in a polishing element therefor comprising a sheet of fibrous material, pleats in said sheet formingY a wave-like edge, a fold medially of said pleated sheet whereby the sheet is folded upon itself, and an abrasive face coating bonded on said Sheet, the inner and outer faces of said folded sheetr being uncoated throughout bands extending about and along the medial fold.

23. A surface-finishing Wheel having a rotatable hub Y and pleated fabric polishing elements secured thereto and extending outwardly therefrom, said elements comprising-pleated fabric sheet material also folded on a medial linev transversely of such pleats and secured to their length to ,the outer ends thereof but vspaced Vfrom the regions of such transverse folds. Y

24.-!In a coated abrasive wheel having a central hub and mounting means associated therewith: a plurality of individual coated abrasive elements radially disposed about said hub and held thereto by said mounting means, said coated abrasive elements each comprising at least one sheet of flexible material having a relatively hard, stiff abrasive coating on and at least partially covering a substantial portion of at least one side thereof, said sheet being prefol'ded prior to mounting on said wheel to provide a plurality of contiguous overlapping pleats, said pleats extending from said mounting means to the outerperiphery of said wheel and having abrasive coated outer end portions thereof adapted upon contact of said element with a work-piece to bend lover at an angle to the direction of rotation of said wheel.

References Cited in the file of this patent Y UNITED STATES PATENTS Murray Dec. 13,

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