US 2653428 A
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Sgpt. 29, 1953 P. K. FULLER 2,653,428
GRINDING DISK Filed April 10, ,1952
IN V EN TOR. Paul K. Fuller A7 r ORIVE Y3 Patented Sept. 29, 1953 UNITED STATES" PATENT" OFFICES-" camp re DISK Paul K. Fuller, Rocky River, Ohio Application April 10, 1952, Serial Nb. 281,592
This invention relates to improvements in grinding disks and more particularly to a pattern formed in the grinding area.
One of the objects of the present invention is to provide a tough flexible grinding disk generally circular in form having a smooth central area where the disk is secured to a backing plate and having smooth non-abrasive paths extending generally radially outwardly through the grinding area of the disk, these smooth paths bending alternately clockwise and counterclockwise around the disk, so that when the disk is ro tated and applied to a piece of work, the edges of said smooth paths provide draw cuts to the work alternately radially inwardly and radially outwardly.
Other objects and advantages of my invention will be apparent from the accompanying drawings and description and the essential features thereof will be set forth in the appended claim.
In the drawings,
Fig. 1 is a top plan view of a grinding disk embodying my invention;
Fig. 2 is a fragmental sectional view greatly enlarged taken along the line 2-2 of Fig. 1;
Fig. 3 is a small side elevational view of a grinding disk mounted upon a backing plate and applied to a piece of work, while Fig. 4 is a top plan view of a grinding disk similar to Fig. 1 but showing a slightly different pattern of the smooth paths extending through the grinding area.
Grinding disks of the type here described are usually about seven or nine inches in diameter and these disks are often used on yieldable supporting pads mounted on a rigid backing member or the disks may be mounted directly upon a flexible backing plate so that the abrasive disk may yield somewhat as it is applied to the Work. A common manner of mounting these disks is shown in Fig. 3 where a grinding disk 10 is mounted upon a backing plate H which in turn is rotatable with a shaft l2 by which the grinding disk is applied to the work, here indicated at 13 as being two plates welded together and the grinding disk is utilized to smooth away the weld I 4 prior to applying a finish to the smooth surface. Other uses of grinding disks of the kind here shown are well known and require no further amplification.
The structure of the disk itself may vary greatly within the scope of my invention. I have chosen to illustrate here a grinding disk like that disclosed and claimed in the copending application of Aaron J. Teller, Serial No. 270,163, filed 1 Claim. 01. 51-195) February 6, 1952, for
2 Grinding Disk Construction. Referring to Fig. 2, the above-mentioned -patent application describes a tough flexible backing sheet I5 of fiber board or the like approximately s s inch thick. To this backing sheet is applied a base coat [6 by dipping or the like. On top of this base coat there is provided a making coat I! of polymerized furan processedaccording to the above-mentioned Teller patent application so as to give a tough but yielding base in which the abrasive particles l8 are held. The abrasive particles may be any suitable material but I prefer aluminum oxide or silicon carbide or sharp particles of steel. A No. 24 grit of aluminum oxide gives very good results. Over the making coat I! and the abrasive particles IB there is formed a cover coat I 9 which may also be of polymerized furan so treated that it is slightly more brittle than the coat I! but is highly resistive to the temperatures generated during a grinding operation.
My invention does not consist in the particular nature of the abrasive coating applied to the backing sheet but rather to the pattern formed by the abrasive material thereon.
Referring to Fig. 1, the abrasive disk H] has a smooth central area 20, in the center of which there may be provided an opening 2| for securing the disk to the backing plate as by means of the bolt 22 as shown in Fig. 3. Outside of the central area 20 is the grinding area 22. Through this grinding area I provide smooth non-abrasive paths 23a and 23b extending generally radially outwardly through the grinding area but bending somewhat out of the radial path as shown in Fig. l. The path 23a bends clockwise, then the path 23b bends counterclockwise and so on alternately around the disk. A simple way of providing these paths is to form the making coat l1 in the pattern of Fig. 1 on top of the base coat l6 leaving the paths 23a and 23b free of the making coat l1. Then when the abrasive particles l 8 are sprinkled upon the disk, they adhere only to the areas between the smooth paths 23a and 23b.
It results from the construction shown in Figs. 1 and 2 that when the disk I0 is rotated and applied to a piece of work, the generally parallel edges of the path 23a apply draw cuts to the work. The outer portion of the path 23a indicated at 24, will provide a draw out generally radially outwardly when the disk I0 is rotating in the direction of the arrow shown in Fig. 1. The next following edges 25 of the outermost portion of the path 23b will provide draw cuts radially inwardly. This is repeated alternately around the periphery of the disk. On the other hand, the inner portion 26 of the path 23a will have edges providing dr-aw cuts radially inwardly while the following edges in the portion 21 of the path 231) will provide draw cuts extending radially outwardly. I find that this application of draw cut alternately radially inwardly and radially outwardly around the entire disk gives a pattern of crissorossing scratches of very fine character which resultsqina "very smooth piece of'work.
In the modification of Fig. 4 everything is exactly like that described in connection with Fig. 1 except that here the paths 28a and where smooth curves rather than angularly related as in Fig. 1. It will be noted that draw.'-cuts=.alternately radially inwardly andradiallyoutwardly around the disk will be provided asthe diskis applied to the work.
It will be noted thatrin both forms of my in- .vention=-as-.shownsindiigu 1-;andeFig. 4, the-.smooth gpaths==23a i23b and 28:1,:2817 providechannels stltrr ngh e'which eairs, is thrownscentrifugally outwardly during the rotation of the-.disk l0. This .eresultsina coolingaction-ruponethe abrasive disk eandiatzthe same-time :keeps. thersmootl'r paths 2 3 a, 13b, 28a,- and 28b cleartof .-.abrasive particlesv or ,portions. freed from the. work by the abrasive par- -:ticles. Since the.smooth-. paths are .open at the periphery of .thedisk, thesair-ahas free escapefrom ,the; edges. ofithe'. diskrandsany particles. collecting in the smooth paths are easily thrown outwardly and cleared from the disk at the peripheral edge thereof.
What I claim is:
An abrasive disk comprising :a tough flexible backing sheet of circular form, there being a smooth central area surrounded by a grinding area, said grinding area comprising abrasive particles bonded to said backing sheet, there being asmooth' non-abrasive paths extending outwardly through said grinding area from a" zone within said grinding area spaced outwardly from said -smooth central area to the periphery of said disk, esaidsmooth paths bending alternately clockwise and counterclockwise around said disk, whereby, r-whensaid zdisk is rotated and applied to a piece of.work, the edges of said smooth paths provide -draw cuts to'the work alternately radially inwardly and radially outwardly.
References Citedlin .the,file of ;this patent .UNITED STATES 1 PATENT S