US 2682733 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
July 6, 1954 o. s. BUCKNER FLEXIBLE ABRASIVE BAND 3 Sheets-Sheet 1 Filed Aug. 16, 1950 II l-Innl INVENTOR. 02 19270 5BucvrzeP CZL EorWey.
July 6, 1954 s. BUCKNER FLEXIBLE ABRASIVE BAND 3 Sheets-Sheet 2 Filed Aug. 16, 1950 ma Q .W 5 w QM m mm mm mm Fm Jul 6, 1954 o. s. BUCKNER FLEXIBLE ABRASIVE BAND 3 Sheets-Sheet 3 Filed Aug. 16, 1950 INVENTOR. 076270 5: ,Bac%rzv' Patented July 6, 1954 UNITED PATENT .OFFIGE Jae-82,733
' FEEXIBLE'ABRASIVE'BAND or'euo S;*Bucknerg-Northboro, Mass.,assignor to Bay ;State Abrasive Products Company, Westboro, Mass., acorporation of Massachusetts Applicatioh=-August--16, 1950,*Serial No."17 9,857
This invention relates to flexible abrasive articles' and is particularly concerned with abrasive flexible bands such as belts; .sleeves,l and'thelike and with novel processe'sior 'producing'them.
It is an object of the'invention to p'rovidflexi ble abrasive bands which are extremely flexible and which may beieasily manufactured inishapes with curved cross-sections.
:Another' object of the inventioneis to provide flexible abrasive bands-such as belts-sleeves; and the like 'Which'are" endless and have-no splices, thus eliminating 'the' surface irregularity and expense resulting-from splicing the ends of such bands and furnishing'less probability of rupture of such-bands.
A further object of the invention. "is to=provide flexible abrasive belts; sleeves, andthe likewhich may be formed with relatively thick"- abrasive layers so as to permit-them to replace economically the "set up wheels and single-layer abrasive:
belts which are now' generally used for "polishing and light grinding operations.
Still another object of-rthe-invention is *to'provide a convenient andinexpensive-method: of manufacturingendless flexible b'ackings wfor abrasive bands such as belts; 'sleevesrand the like.
Additional objects and advantages of-the invention will be' perceived from the 3 following description taken in conjunction with the *a'ccomr panying drawings in which:
Figure l is a perspective View of a--flexible abrasive belt or sleeve which embodiestheinvention of-thepresent application;
:Figure 2 is an enlarged"cross-sectional view I "Figures 6a, 6b'j and ec' 'illiistfat diagrammatically in cross-section several of the iiiariy pos sible' contours with "which flexible "abrasive sleeves may be manufactured in'aceordance with the present invention;
Figure 7 is a further enlarged fragmentary cross-sebtionallview', 's'im-ilarf to Figure 2;; or; a
attached to-such backing by an adhesive.
2 flexible abrasive sleeve or belt-manufactured in accordance with the presentin'vention in which flexible loops are provided on the flexible backing for reinforcing and anchoring theabrasive layer;
Figure 8 is a view similar to Figure '7 showing a modification ofthe backing of the flexible abrasive belt or sleeve; and
Figures 9 and 10 are reduced fragmentary views of the working surface of a flexible abrasive belt or sleeve, constructed in accordance with the teachings of the present invention, illustrating two of the numerous patterns or-combinations of grooves with which the outer face of a thick abrasive layer thereon may be provided.
backing material employed is commonly a woven cloth or a fibrous sheet material such as paper. In forming such abrasive articlesit' has been the practice to provide a web ofabrasive-coated material of the type desired and which is of the proper length and width and then to form the web'into a continuous abrasive band by splicing the-ends thereof together. Although considerable effort has been expended in attempts to provide an entirely satisfactory splice or joint for belts and the like, the attempts have been in vain. A large percentage of the failures of abrasive coated belts are the result of defective or weak joints or splices-which part during the constant and rapid flexing to which they are subjected in abrasive operations. Moreover, splices necessarily cause an irregularity in. the continuity ofthe abrasive surface of the belt or sleeve which is objectionable in polishing operations.
By the method of the present invention, it is possible to make endlessflexible abrasive belts or sleeves which do not require transverse splicing and, as a result, are free from any irregularity resulting therefrom, and which carry an abrasive layer-thatmay be several times thicker than the 'backing'or than the average diameter of the abrasive granules therein. Such "improved flexible abrasive bands (the term abrasive' band being T hereinafter" intended; except where the context-may otherwise indicate, to include both flexiblee abrasive? belts which are intended to be carried; in'use, on a plurality of pulleys or wheel's and flexibleiabrasive sleeves which are intended-to besmounted forv use on a The 3 single, expansible wheel) are convenient because the absence of a splice does not require their being mounted to run in a specified direction. In addition, as such abrasive bands are stronger, they are less likely to fail in use and they have a much longer useful abrasive life.
Furthermore, the present invention permits the construction of such abrasive bands having a degree of flexibility heretofore unobtainable, and allows the manufacture of flexible abrasive sleeves having irregular or curved cross-sections but carrying abrasive layers of substantial thickness.
The essence of the present invention is the employment of spirally overlapped flexible tape in forming an endless backing for abrasive bands. Since the abrasive layer on said bands is supported by what is in effect a series of overlapping pliable plates, the resultant abrasive band is quite flexible. The use of an overlapping tape backing also makes it possible to provide abrasive bands with various curved contours in cross-section Without forcing a distortion of a full width sheet backing.
Referring to the drawings, Figure 1 depicts an abrasive band constructed in accordance with the present invention and having an outwardly facing abrasive layer l and a backing l2 to which the abrasive is attached. As will be seen more clearly in Figures 2 and 3, the backing i2 is composed of a number of convolutions of flexible tape 14 which overlap one another across the width of the abrasive band.
In forming an abrasive sleeve in accordance with the present invention, a cylindrical mandrel or drum [6 (see Figures 5 and 6) having a periphery of the desired length is provided. The cylindrical outer face of the mandrel I6 is preferably first covered with a layer of cellophane or similar smooth-surfaced material (not shown) and then flexible tape l4 of suitable material is spirally wound thereon. Each convolution of the tape 14 subsequent to the first overlaps substantially half the width of the previous convolution and thus there is formed a backing of substantially uniform thickness the width of the periphery of the mandrel l6. The backing is preferably formed of a single long strip of tape but may, if desired, be formed of a number of overlapping strips.
The tape l4 which is employed is preferably narrow, tape one inch in width having been found very satisfactory for most purposes. However, the tape width may be varied where desired from about one-half inch to two inches. Various materials including organic fibers such as cotton, linen, etc., as well as inorganic fibers such as glass may be used in forming the tape I4. Furthermore, the tape may be either woven or felted. Good results have been obtained with a woven cotton tape of the type used commercially for binding seams and the like. A suitable adhesive material I! such, for example, as a liquid phenolic resin is preferably applied to the portion of the tape [4 which is to have the succeeding turn of tape wound over it so that the successive convolutions will be held in place and, when the winding is completed, form an endless backing.
In cases where the tape used has a low tensile strength or has a, tendency to stretch to an undesirable extent, it has been found desirable to reinforce the tape backing I2. A convenient method of reinforcing it is to wind around it, on the mandrel IS, a number of turns of thin wire l8 of steel, bronze, or other suitable metal. The reinforcing wire is preferably wound spirally and may be anchored at its ends by pushing it through the tape I4 and forming the ends into hooks 19 (see Figure 3) which engage in the tape.
When the backing I2 is completed, the portions of the tape I4 that overhang the edges of the drum or mandrel iii are turned over the edges and covered by the removable mandrel end rings 20. Each of the end rings 20 has an outside-diameter somewhat greater than the diameter of the mandrel IS. The rings are arranged concentrically on the opposite ends of the drum or mandrel, being secured thereto by suitable means such as studs 22 which are preferably integral with the ends of the drum and extend through holes in the end rings to cooperate with the wing-nuts in holding the rings 20 tightly in place. The mandrel I6 is thus provided, by the projecting edges of the rings 20, with a pair of spaced peripherally-extending flanges 28. Each end of the mandrel I6 is also preferably provided with a centrally disposed stub shaft 30 which is adapted to be rotatably mounted in a suitable support (not shown) so that the'mandrel may be freely turned about a horizontal axis.
In Figures 4 and 5 there is illustrated diagrammatically the preferred manner in which the bonded abrasive layer I0 is applied to the backing I! on the mandrel [6. Although a simple mixture ofabrasive particles and bond may be employed, better uniformity and structure (i. e. the space and volume relation of bond, abrasive and pores) -may usually be obtained by using abrasive granules that have been pre-coated with a heat-settable resinoid bond in any of the ways well known in the art. The coated abrasive granules are fed from the hopper 32 and deposited in a thick loose mass 34 of even thickness on the outer surface of the backing i2. As the mandrel I6 is rotated slowly in a counterclockwise direction as shown in Figure 5, the loose mass 34 of bond-covered abrasive is carried under a plunger 36. When pressure is applied by the plunger 36 to the loose mass 34 of bond-covered abrasive granules, the mass is compressed into a thinner, more compact layer 40.
The lower face 38 of the plunger 36 is the same length as the width of the cylindrical face of the drum or mandrel l6 and has a transverse arcuate curvature of suitable radius to form the compressed abrasive layer 40 with an outer surface that is concentric with the cylindrical face of the mandrel. The plunger may be actuated to provide a tamping 0r compacting action on the abrasive mass 34 by any suitable source of power (not shown). If desired, the adhesion of the particles to one another and to the backing l2 may be increased by applying a light spray 4! or coating of bond solvent or plasticizer to the mass 34 of bond-covered abrasive between the hopper 32 and the plunger 36 through a perforated pipe or nozzle 42 that extends transversely of the mandrel H5. The pressing procedure just described is successively carried out on adjacent loosen masses of bond-covered abrasive granules until the entire outer surface of the backing is covered with a compacted abrasive layer 40. The comp-acted layer 40 is then finally compressed and the heat-settable bond thereof is cured in any suitable manner.
Preferably the mandrel I6 is hollow and is proa ines (not slidwn) backing .1 12 is? partially; cured-and *seti :Thei'sleeve may-@thenibe removed from :the :mandr'el and the cureiofrthei abrasivegibend'fmayg be completed by heating the sleeve in an oven :(hot 'shown) at approximately 320 F. :fo'riaboutbnet hour. 1 After the; bond islcured' the sleevewhich is now provided. withaafdensexcompaot abrasive layer prefeltablyseveral times thicker than theiba'cliin'g and the talhelta e diameter of thel individual abrasive granules gtherein, ismade v ready for: use by trimming, off the; protruding gedgesaof tape l 4 i and griridir g,or,v cutting off: any. exposed ,free ends" of thegreinforcingwirej8i-.
alternative procedure; is; preferred when the length; of; t e abrasive.;bands issuch that; the cylindrical:- mandrel, Ieqliiibd, ;for their ,produconwwould.beu de iramy large ingsiz Accor ing to the alternative method, the flexibletape beatin -lien r gsaeeb si eg and is. fo me $1 611; of .the desired;,;siz e hich .is supported on r or. m r .wb e s P. e. :w ni e a being wound on the belt n;pverlapping -convolutions in a manner very similar to the construct ofitof such baekings on thetiylin'drieal drum gthah q insis.sgm leied th abrasive layer is formed in generall the same manner as ,b fore by successivelyp ing areas of'the backing which 'arecovere 1th an fabra'sive grooves. such grooves-may be easily molded into the abrasive layerduring -the"'cure thereof in any desired pattern, tnepatterns of intersecting grodvesbn 'arid 6|, illustrated-in Figures 9 and 10 resp-eetivdwbem merely' e 'ples. Beneficial resmts of enfploy-ing such in'te c'ting groove patlQEIIYSJaiGI-tH obtainingo'f greater flexibility in the abrasive bands,;thereductionin the loadin of the abrasivesurfaceduring use, the grooves serving to carry away detritus formed during grinding; and 'cooler cutting.
The use of relatively narrow flexible tape as a backing for abrasive sleeves permits the construction of such sleeves with contoured surfaces so that the carrying out of abrading and polishing operations on articles having non-planar surfaces is simplified. Thus moldings, castings, and forged or pressed articles such as automobile bumpers and the like may be ground or polished with sleeves having correspondingly shaped abrasive surfaces. In Figure 6 there are shown in cross-section several of the many possible shapes in which flexible abrasive sleeves may be constructed in accordance with the present invention.
Although the same general method may be ample, in producing such-1 an" abrasive sleeve pn ama'ndrel or drum the cylindrical 'face thereof must' be 'forr'ned in' the desired' shape:"Moi-eover;it will benec'essary, if the sleeve is to carry an' abi'asive' Iayer of un'iformt thickness, to 'em plo'y a scraper orotherl'means to form: the "loose mass '3'4 of bond-coated i-abrasive "'granu1es deposited from thenhopper'.32"onthe surface of the :pliabie tape backing I 2. 'intothe desired -shape prior'- to pressingi'iln shapingthe mass 34--a suitably formedtemplate or scraper (not shown) maybesupported: on the opposed peripherally extending flanges 28. in contact with the mass.
The plungeritfi must also, ofcourse, bem'odifled so that its bottom face 38 willbe of proper shape and curvature. to'cooperate. withthe curved surface of the'mandrel It in forming the abrasive layer 10. The abrasivelayer jmay becompacted onthe backing and the'bond thereof may becured in: substantially the same way as previouslydescribed. H
ltswill beseen that-byusing a comparatively narrow tape a shapedbacking which is substantially smooth and free of wrinkles may beeasi y provided. A flexible abrasive sleeve utilizing such a backing will preserve its shape better and ,will be" subject to less stress infoperation than will an abrasive sleeve in which a s gle sheet or web of a' backing is forcedtoaSS mQfihe. des d h p .In Figure 7 there is shownin enlar ed QIf section an abrasive band embodying the invention of the present applicationbut modified-by the provision of outwardly. projecting filaments 50, of thread or. similar material on the flexible p king, 12. l o h they-m 1a+ig the'filam'ents 50, as shown in Figures7 and; 8, are
preferably formed as umnatted, stitch loops.
They may be applied to the tape l4 prior toforming the backingin any desired or convenientway such, asw-ith. a sewing machine which maybe adjusted to provide loops of -the required height, spaced in rows as desired. The loops 50 are provided on one half of one'side only of the tape and are preferably of such length as toextend outwardly from the surface of the tape. about inch. Their length, however, may be varied in accordance with the thickness of the abrasive layer whi'chis desired. It is also. preferred to closely space the loops 50, a spacing between adjacent loops of from 5inch tov inch having been found satisfactory.
The filaments or loops 58 may be formed of any preferred materials, anumber of those which are suitable being set forth in applicantszcopending application, Serial No. 171,165, filed'June-ZQ, i950. The advantages and benefits accruing from the use of such reinforcing filaments in flexible abrasive articles are also set forth in the application sirable to stiffen the filaments or loops. As disclosed in applicants copending application referred to above, this may conveniently be done by applying to them a solution of a stiffening agent such as latex. Furthermore, it is necessary to modify somewhat the above described method of forming the abrasive layer. In order to insure satisfactory packing of the abrasive-bond mixture within and around the loops or filaments 50, after the loose mass 34 of the abrasive-bond mixture has been applied to the surface of the flexible backing I2, a comb or stiff brush (not shown) is run through the mass to work it down into the nap provided by the filaments. When an even layer of the loose mass has thus been provided, pressing and curing of the abrasive layer may be carried out in the, same manner as described above for the production of flexible abrasive bands in which filaments 50 are not used.
As pointed out above, in somecases the tape M employed in forming the backing 12 for flexible abrasive bands may be low in strength or may stretch excessively under tension. Instead of using the wire l8 as a reinforcing device to reinforce the backing, the backing may be provided (as illustrated in Figure 8) on the side opposite from that to which the abrasive layer is to be applied with a reinforcement of a strong, flexible material such, for example, as thin vulcanized fiber. In forming a flexible abrasive band on the mandrel or drum I-G with a vulcanized fiber reinforcement, a strip 55 of the fiber is preferably wound spirally around the drum and coated with a suitable adhesive 56 prior to starting the winding of the flexible tape M. The tensile strength of vulcanized fiber is great enough to provide adequate reinforcement even in very thin strips which do not interfere substantially with the flexibility of the backing. If desired,. the reinforcing strips may be wider than that shown in Figure 8 and provided with longitudinal scoring which will permit easy flexing transversely of the abrasive band.
The flexible tape backings disclosed herein are,
as pointed out above, of particular value in forming abrasive bands with thick abrasive layers. However, relatively thin layers of abrasive may also be employed and if desired such backings may be provided with a substantially single layer of adhesively secured abrasive granules by any of the well known and suitable methods described in the prior art. While the useful life of flexible abrasive bands according to the present invention having thin abrasive layers will be comparatively short, the substantial nature and strength of the backing is such that they can be recoated many times.
It is to be understood that the embodiments of the present invention hereinabove described may be considerably modified and varied Without departing from the spirit of the invention. Thus,
for example, the materials employed in forming.
variation as is the method employed in construct ing the flexible abrasive back. Moreover, the abrasive granules used may be of any desired type and grit size and the bond therefor may be of any suitable type. The foregoing mention of some possible variations is not, however, to be considered as limiting the invention beyond the scope of the appended claims.
The invention claimed is:
.1. A flexible abrasive band comprising an endless flexible backing and a porous abrasive layer attached to the outer face thereof, said backing being formed of a plurality of side by side, overlapping convolutions of flexible textile tape and having a plurality of unmatted stitch loops at tached thereto and projecting from the'outer face thereof, said abrasive layer encasing saidloops and providing a relatively thick, continuous, substantially smooth, abrasive surface across substantially the whole width of said band Without interruption at the overlapping edges of said convolutions.
2. A flexible abrasive band as set forth in claim 1 in which said abrasive layer is several times thicker than said backing and is molded on said backing from a granular mix.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 63,341 Trant Mar. 26, 1867 305,068 Fullerton Sept. 16, 1884 592,992 Lowry et al Nov. 2, 1897 604,569 Ringstrom May 24, 1898 1,844,165 Kabelac Feb. 9, 1932 1,850,413 Porte Mar. 22, 1932 1,929,274 Ellis Oct. 3, 1933 1,952,978 Ellis Mar. 27, 1934 1,961,911 Pusch June 5, 1934 1,963,357 Filley June 19, 1934 2,038,782 Ellis Apr. 28, 1936 2,071,563 Newcomb et a1. Feb. 23, 1937 2,115,897 Woocldell et a1 May 3, 1938 2,137,305 Perazzoli Nov. 22, 1938 2,138,882 Robie Dec. 6, 1938 2,189,754 Cherrington Feb. 13, 1940 2,277,520 Martin et a1 Mar. 24, 1942 2,347,244 Colt et a1 Apr. 25, 1944 2,413,551 Engluncl Dec. 31, 1946 2,483,293 Minarik et a1. Sept. 28, 1949 FOREIGN PATENTS Number Country Date 125,775 Switzerland May 1, 1928