US2819568A - Grinding wheel - Google Patents

Description

Jan. 14, 1958 J. N. KASlCK 2,819,563

GRINDING WHEEL Filed April 18, 1957 2 Sheets-Sheet 1 INVENTOR. JOHN N @1506 ATTORNEYS Jan. 14, 1958 J. N. KASICK 2,819J568 GRINDING WHEEL Filed April 18, 1957 2 Sheets-Sheet 2 /7 H 15 5 l5 l6 4 INVENTORQ Y 5 5 J HN Ni Kflsmz BYW 52 g, L

M-(r T 4 T TOPA/E 7 5 United This invention relates to grinding and sanding apparatus and methods and more particularly .to an apparatus for use as .a backing plate for a grinding or sanding disc. Mylinverition is particularly related to portable grinders or sanders such as are commonly used inautomobile refinishing and body shops and the like.

"Such apparatus commonly comprises .a small. motor, WhlCh may be easily lifted and carried, and has adrive shaft upon the remoteend of which is mounted 'achuck. A backing plate. is adapted to be mounted in the chuck and a sanding or grinding disc usually of the center mounting type is mounted -on the outer face thereof. The. grinding disc usually comprises a circular .base of kraft or other heavy paper or the like to one or .both faces of which aluminum oxide or other grit is secured by a resin or other suitable adhesive.

Alternativelyfthe chuck may be disposed-at the end of afiexible cable, the other end \of whichis driven by -a suitable motor. lnthe past a-great deal of:difliculty.has been experiencedfin the use of such apparatusbecause of the nature of the sanding discs, the material being worked, and the method and manner .usuallyfollowed in using the apparatus. Muchof the difficultyhas been caused by 'the heat, which is inevitably generated at the working surface, .due. to the friction of the disc upon the surface.

This heat hasa marked tendency to break down therdisc and cause the grit to come loose or to loseits hardness and sharpness more rapidly. Additionally,=where the surfacesbei-ng worked are ofsoft metal orhave been painted,

lacquered, varnished, or covered with plastics or other surface coatings, the heat tends to soften ormelt the same causing soft metal, paint or lacquer, etc., -to .gum .up orclogthe surface of the disc thereby coveringthe: grit and rendering thedisc unsuitable for further use. .Fur-

ther, where jthemetal is of thin gage the increase in.tem-.

perature thereof resulting from .the grinding or sanding has a marked tendency to cause buckling. Also, because the high heat tends to cause the disc to loseits sharpnessand cutting ability, there is a greater tendency to apply ggreater pressures against the disc and surface in ordertoextend the use of the disc over a greater and more economical length of time. These pressures also tend toincrease the probability of buckling.

I It is therefore a general object of my invention to. providean improved and more. efficient and economic -ap-- g CE apparatus under similar operating conditions; which :extendsthe useful life of the grinding of sanding disc and/ or prolongs and/or increases the etficiency thereof by pre venting mitigating deleterious effects thereon due to heat generated on the surface being treated during the use thereof, and; which protects the metal and surface being treated and/or the areas adjacent thereto from thedeleterious effects of heat by. providingrmeans to maintain the temperature thereof .at. {lower levels than would otherwise be possible :with similar apparatus used in a similar manner.

Still further objects iof inventionare to provide a backing plate, for a sanding or. grinding disc, which is adapted, in cooperation with 'the1disc,.to cause a flow of coolant across the surfaoebeing worked, and to provide a backing plate fore-sanding or grinding 'disc, which is adapatedpin cooper-ationwith the disc, to function as a centrifugal pump rtowdrawcool air across the surface being worked toward the center :of the disc and to expel the same, w hen heated, at the periphery of the backing plate.

These and other objects and advantages ofmy invention willyappear from the-following description of preferred and modified forms thereof, reference being had to the attached-drawingsin which:

.Figure l is a perspective view of .a backing plate and disc embodying mytinvention, with part of thedisc broken away better to show the structure of the backing plate;

. Figure .2 .is' .a ,plan .wiew of a backing wpl-ate show-11in Figure 1;

Figure .3 is a section .-taken along thenline "of Figure -1;

Figure 4 .isa {plan viewrof backing plate embodying my invention ,and illustratingrmodified forms sthereof; and

Figure. 5 is a sseotiontaken along.:theline-fi fi of Figure 4.

Broadly my invention comprises; providing'ia grinding or sanding apparatuswwhich is adapted, bydts motion ,incident .to. the .grinding or sanding, to acauseva 'fiowdof coolant across the surface being worked whereby -to-control orv lower the temperature thereof below thatwhich would ...otherwise obtain under r-similar @operating conditions.

Briefly myinvention comprises arbacking'plateaand disc mounted thereon, which function 35921-Shl0l1d6d centrifugal .-impeller, pumping .hot air from .the center of the disc adjacent. the surface being worked to the periphery of the backingplate and, thereby, causing cool air to rush or..flow toward the-center of the disc from the periphery thereofacrossthe. surface being worked so as to cool-or reduce the temperature thereof.

. Particularly as best-seenin Figures 1., 2 and 3 apparatus embodyingmy invention is indicated generally at 2 and comprises a backing plate indicated generally at 3 and a grinding or sanding disc. 4. .Disc 4 may beof any conventional construction, except as hereinafter noted, and usuallyand conveniently comprises. a backing of kraft paper or the like on-t he working ,surfaceof-Which is .se

cured garnet, .sand, aluminum oxide or other sharpmate rial set in .a suitable binder in; a .manner .wellknown to the art. .Such discs, are frequently provided with-intersecting slots or a hole at the center through which the shank of a screw or other fastening device 5 is inserted in order to secure the disc to the backing plate.

The backing plate 3 comprises a generally flat disc portionfi and a center shank portion 8, which extends perpendicularly and rearwardly therefrom (see Figure 3). The rearward extremity of the shank 8 is adapted to be mounted in .a chuck (not shown), which in -turn is socured to a. drive shaft flexible cable or other source of rotative power as is well known in the art. The other 3 end 11 of shank 8 is bored and tapped through the upper face or surface 13 of plate 3 so as to receive the fastening device 5; the face or surface 13 being dished or countersunk in order that the head of the fastening device does not protrude above the working surface of the disc 4.

The portion 6 of the backing plate 3 may be formed from any convenient material such as metal, hard rubber, or cork, but is preferably flexible at least near or approaching its periphery in order that the outer portions of the surface 13 and portion 6 may be bent so as to facilitate the use and application of the apparatus.

All of the above described parts and portions of the apparatus are old and well known in the art and considerations regarding their structure and use are within the knowledge and practice thereof.

In order to accomplish the objects of my invention and cause the operation of the sander or grinder to induce a flow of air across the surface being worked, I provide the backing plate with a plurality of substantially radially extending passages which extend from near the center of the plate to near the periphery thereof and which function in the manner of a centrifugal pump to move air or gas from the center of the plate to the outer exterior thereof. I also provide means by which the air can enter the center of the plate (eye of the impeller) through the disc 4 from adjacent the surface being worked.

More particularly, I provide the disc 4, near its center, with a plurality of apertures 14 extending entirely therethrough. Preferably and conveniently the apertures 14 take the form of equal angularly spaced, circular holes disposed on a circle concentric with the disc and near the center thereof.

Preferably the passages in the plate 3 comprise open faced grooves or channels 16 formed in the surface 13 and having their exits or ends in and at the periphery 18 of the plate, as shown. As previously stated the grooves or channels 16 extend in a substantially radial direction albeit I have shown and prefer that the channels 16 be curved oppositely to the direction of rotation of the plate in order to improve the pumping efiiciency, thereof.

Also, I prefer that the grooves or channels 16 be connected at their inner end by a 360 arcuate groove or channel 19, which is concentric with the center of the plate. The groove or channel 19 is preferably radially spaced from the center of the plate 3 by the same distance as the apertures 14 are spaced from the center of the disc'4 so that when the disc is mounted on the plate the apertures are in communication with the channel 19. When the channel 19 is provided there is automatically a continuous path from the apertures 14 to the channels 16 without regard to the relative angular positions of the disc and plate, whereas in those instances where no channel 19 is provided it is necessary that care be exercised to align radially the apertures 14 with the inner ends of the channel 16 so as to have the communication, between the apertures and the radial channels, necessary for the proper functioning of apparatus embodying my invention as will hereinafter more fully appear. In the latter instance the channels 16 are made of suflicient length so as to underlie the properly positioned apertures. It will be noted that the advantage of the channel 19 is that no care need be exercised in locating the disc on the plate since no matter what the radial position of the apertures relative to the channels 16 there will be communication between the same via the channel 19.

Alternatively the groove or channel 19 may have less than 360 of arc and may be continuous or segmented as illustrated at 19 in Figure 4. When segmented the channel in effect lengthens, circularly or arcuately, the inner ends or openings of the channels 16 without however interconnecting the same thereby making it easier to align the apertures 14 and grooves 16.

In use the disc 4 is mounted on the plate 3 by com tering the disc on the plate, inserting the fastening means 5 through the central hole of the disc, and tightening the means 5 into the internally threaded end 11 of shank 8. When it is desired to work a surface the drive means is actuated causing the plate and disc to rotate. Rotation of the plate with the disc thereover, causes the channels 16 to function as a fully shrouded centrifugal impeller, pumping the air from the inner ends of the channel 16 and channel 19, to the exterior of the plate. This results in a reduced pressure at the eye of the impeller, the inner ends of the channel 16 and the channel 19, and hot air is thereupon drawn therein through the apertures 14 from adjacent the surface being worked thereby causing cool air to flow across the surface being worked toward the center of the disc in order to fill the partial vacuum otherwise created by the flow of the hot air through the disc and into the channels of the plate. This cool air reduces the temperature of the surface being worked,

as it flows across the same absorbing heat therefrom and itself becoming heated and is in its turn pumped away by the action of the apparatus embodying my invention.

Figures 4 and 5 also disclose an alternate form of my invention, which is similar in all respects to that described above except that the channels 16' in the backing plate 3 have their exits in the back of the portion 6 of the backing plate adjacent the peripheral edge thereof, instead of being open faced and having their exits in the peripheral edge 18 of the backing plate. For purposes of illustration I have also shown this modified form of my invention without the arcuate channel 19 on the right side thereof as viewed, and with a segmented channel 19 on the left side thereof, as viewed, it being understood that both the modified and preferred forms of my invention may be made with or without all or part of the arcuate channels 19 or 19' as desired.

The operation and use of the modified form of my invention is substantially the same as with the preferred form thereof described above.

Modifications, changes and improvements to the preferred and modified forms of my invention herein described may occur to those skilled in the art who come to understand the precepts thereof. Accordingly I do not care to be limited in the scope of my patent to the specific preferred and modified embodiments of my invention herein described but rather desire that the scope of my patent be limited only by the advance by which my invention has promoted the art.

I claim:

1. In a rotary grinding or sanding apparatus, a backing plate having a flexible disc portion with a flat forward face and a peripheral edge and a rearwardly extending shank portion concentric therewith, driving means secured to said shank portion of said plate and adapted to provide rotative motion for said plate, and a detachable grinding or sanding disc removably secured to the face of said plate in concentric alignment therewith, said disc having a plurality of equiangularly spaced apertures extending therethrough, said apertures being disposed so that their centers lie on a circle which is concentric with the center of said disc, said face of said plate having a plurality of substantially radially extending open channels or grooves therein, each said channel having side walls extending from near the center of said face to the periphery thereof and having its exit in the peripheral edge of said plate, said side walls of each channel being parallel and curving arcuately away from the direction of rotation of the plate, a circular 360 open-faced channel or groove interconnecting the inner ends of said radial channels and being concentric with the center of said plate and disc and being spaced from the center of said plate the same distance that said apertures are spaced from the center of said disc, said apertures being in communication with said arcuate channel and said disc otherwise closing the open side of said channels, said covered radial channels functioning as a shroud ed impeller, when said plate and disc are rotated, to pump hot air from adjacent said apertures and the surface being worked and out the exits of said radial channels and thereby cause cooler air to flow across the surface being worked toward said apertures whereby to cool said surface.

2. In a rotary grinding or sanding apparatus a backing plate having a peripheral edge and a substantially flat face for supporting a grinding or sanding disc, a grinding or sanding disc removably mounted on said backing plate and supported on said plate against said face and in concentric alignment therewith, and means to drive said plate, said disc having a plurality of equiangularly spaced apertures extending therethrough, said apertures being disposed With their centers on a circle concentric with said disc, a plurality of substantially radially extending open faced channels in the face' of said backing plate, each of said channels having side walls extending from near the center of said plate to the periphery thereof and having its exit in the peripheral edge of said plate, said side walls being parallel and curving arcuately away from the direction of rotation of the plate, a circular 360 open-faced channel interconnecting the inner ends of said radial channels and being concentric with the center of said plate and disc and being spaced from the center of said plate the same distance that said apertures are spaced from the center of said disc, said apertures being in communication with said arcuate channel and said disc otherwise closing the open faces of said channels.

3. In a rotary grinding or sanding apparatus a backing plate having a peripheral edge and a substantially fiat face for supporting a grinding or sanding disc, a grinding or sanding disc removably mounted on the face of said plate in concentric alignment therewith, and means to rotate said plate and disc, said disc having a plurality of angularly spaced apertures extending therethrough, said apertures being disposed with their centers on a circle concentric with said disc, a plurality of substantially radially extending open faced channels in said face of said plate, each said channel extending from near the center of said plate to the periphery thereof and having its exit in the peripheral edge of said plate, a circular open-faced channel interconnecting the inner ends of said radial channels and being concentric with the center of said plate and disc and being spacedfrom the center of said plate the same distance that said apertures are spaced from the center of said disc, said apertures being in communication with said arcuate channel and said disc otherwise closing the open faces of said channels.

4. In a rotary grinding or sanding apparatus a backing plate having a peripheral edge and a substantially flat face for supporting a grinding or sanding disc, at detachable grinding or sanding disc removably mounted on said face in concentric alignment therewith and means to drive said plate and disc, said disc having a plurality of spaced apertures extending therethrough, a plurality of substantially radially extending open face channels or grooves in said face of said plate having their exits in the peripheral edge of said plate, each said aperture being in communication with the inner end of at least one of said channels and said disc otherwise closing the open face of said channels.

5. The apparatus according to claim 4 in which an open faced circular channel or groove is provided in said face and interconnects said radial channels and underlies at least a portion of each said aperture to provide communication between said apertures and said radial channels, said disc otherwise closing the open face of said circular channel.

6. In a rotary grinding or sanding apparatus a backing plate having a substantially flat face for supporting a grinding or sanding disc and a grinding or sanding disc removably mounted on said face, said disc having a plurality of spaced apertures extending therethrough, a plurality of substantially radially extending channels in said plate, each said channel extending from near the center of said plate and having its exit directed away from said face, the inner end of each said channel being in communication with at least one of said apertures.

7. The apparatus according to claim 6 with a circular open faced channel in the face of said plate and interconnecting the inner ends of said radial channels and being in communication with a portion of each said aperture.

8. The apparatus according to claim 6 with a circular open faced channel in the face of said plate, said channel intersecting at least a portion of said radial channels at their inner ends and providing communication between each said intersected channel and one or more of said apertures.

9. The apparatus according to claim 8 in which said circular open faced channel is segmented, each said segment intersecting at least one of said radial channels.

10. In a rotary grinding or sanding apparatus a backing plate having a peripheral edge and a substantially flat face for supporting a grinding or sanding disc and a grinding or sanding disc removably mounted on said plate against said face, said disc having a plurality of apertures extending therethrough, a plurality of substantially radially extending open face channels in the face of said plate having their exits in the peripheral edge of said plate and their inner end portions in communication with said apertures, said disc otherwise closing the open faces of said channels and being adapted to function as a shrouded impeller when said apparatus is rotated.

References Cited in the file of this patent UNITED STATES PATENTS

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