CA1305860C

CA1305860C - Disposable grinding apparatus having an integral mounting hub

Info

Publication number: CA1305860C
Application number: CA000533436A
Authority: CA
Inventors: Joseph H. Mackay, Jr.
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-04-03
Filing date: 1987-03-31
Publication date: 1992-08-04
Anticipated expiration: 2009-08-04
Also published as: EP0318476A1; CN87102592A; AU7301487A; JPH01500578A; EP0318476A4; AU595604B2; WO1987005847A1; CN1008894B

Abstract

DISPOSABLE
GRINDING APPARATUS HAVING AN INTEGRAL
MOUNTING HUB

Abstract A disposable grinding apparatus such as a depressed center grinding wheel 10 for mounting on a rotatable threaded spindle 14 of a power tool 16. The grinding wheel 10 contains a retaining nut 44 on one side thereof and a backing flange 28 on the other side thereof non-removably secured together on the grinding wheel 10 without the aid of adhesives in such a manner that the grinding wheel is placed in compression when it is operably secured upon the spindle of the power tool under grinding loads. The nut 44 and flange 28 are secured together by upsetting one end 52 of the nut 44 causing it to protrude outwardly over the outer surface of the flange 28. A base assembly 60 is loosely secured to the spindle 14 of the power tool 16 for engaging the outer surface 38 of the backing flange 28 during operation of the grinding wheel 10. Alternatively, a pressure cap member 90 is secured to the outwardly protruding portion 56 of the nut 44 for engaging a shoulder formed on the spindle of the power tool during operation of the grinding wheel.

Description

~3C~

DISPOSABLE

MOUNTING HUB

Field of the Invention This invention relates generally to abrasive finishing articles and more particularly to abrasive grinding apparatus having a mounting hub permane~tly lU affixed thereto with the combination adapted for attachment to an appropriate portable power tool. More specifically the invention has application to disposable depressed center grinding wheels.

Ba kqround of the Invention The use of rotatably driven grinding devices i9 widespread and familiar in our industrial society.
One of the more serious problems encountered in the use of such devices resldes in the provislon of effective means for preventing undesired or accidental disassociation of the grinding device such as a wheel from the shaft, spindle or other rotatable drive means on which it is mounted. This problem is particularly acute when the connection between the grinding apparatus and it5 driving shaft or spindle is intentionally detachable to facilitate quick removal and replacement of the grinding apparatus. Into this category fall a host of devices, for example, portable powered grinders ~k ~3~36~

wherein grinding wheels employed are intentionally detachable from the power driven shaft so that they may be readily replaced. To properly mount the grinding wheel upon the shaft provision must be made to provide sufficient clamping force and also to secure the wheel rotationally.
One means of securing the grinding wheel to the drive shaft has been to provide an appropriate lU backing flange with a central opening which is aligned with an opening provided in the abrasive grinding wheel.
A bolt or nut member (depending upon the con~iguration of the drive shaft, that is, whether it is externally or internally threaded) is inserted from the face side of the grinding wheel and is then tightened in place. In this manner a plurality of loose parts are configured in a completed assembly ready for use. As the grinding wheel is utilized the appropriate clamping force is provided to securely affix the grinding wheel to the ~U drive shaft. Such an assembly, however, typically requires appropriate tools such as wrenches or the like to remove the grinding wheel from the drive shaft. Such a device is shown in U.S. Patent Nos. 3,596,415;
1,998,919; 566,883; 507,223; 1,162,g~0; 791,1S9; 4~9,14 and 3,210,8~2.
Subsequently it became desirable to affix the mounting hub permanently to the grinding wheel so that the entire unit may be quickly and easily attached and detached from the drive shaft and discarded when the ~U grinding wheel has been worn down. In these types of devices it is customary to utilize an adhesive such as an epox-y resin or the like between the backing flange and the back surface of the grinding wheel to retain integrity between the mounting hub and the grinding wheel to secure the wheel rotationally.

~30~

Even though the adhesive tended to work quite well in most applications, it was discovered that in some ins~ances the adhesive would brea~ loose and the grinding wheel woula rotate relative to the mounting hub. Such was particularly the case since the hub was a one-piece member which was internally threaded and held in place upon the grinding wheel by swaging an extension thereof into place, thus providing a fixed clampin~
force holding the grinding wheel. No additional clamping force was exerted during further rotation of the wheel during use as was the case with the traditional nut which was secured from the face as above described. As a result various keyways and corresponding key structures were developed between the wheel and the mounting hub and used in conjunction with ,the adhesive to preclude rotational movement between the mounting hub and the grinding wheel. Examples of such devices are shown ln U.S. Patent Nos. 3,136,100;
~0 4,015,371; 2,278,301; 3,081,584; 3,500,592; 3,800,483;
A,240,230 and 4,541,205.
Additional prior art patents known to applicant are U.S. Patent Nos. 3,041,797; 3,879,1~8;
1,~24,~42: 3,912,411; 3,8~9,178; 3,960,S16; 4,026,0~4;
25 4,054,425; 4,088,729; 4,601,661; 791,~91; ~2,932;

2,56~,782; 3,136,100, 3,210,892 and 3,621,621.
The devices utillzed in the prior art for providing the disposable grinding wheel asse~bly lncluding the permanent affixed mounting hub generally 3U provide the service intended. There are certain inherent disadvantages found with regard to the various devices. Such disadvantages are that in manufacturing the utilization of an adhesive adds additional materials and labor to the cost of manufacturing. In certain of the devices, parts must be keyed together and properly aligned in order to function appropriately. In addition ~hereto, throush the utilization of die-cast mounti~
hubs which include as an integral par~ the backing flange there is no additional clamping force exerted upon the grinding wheel as it is being rotated by the power tool. Furthermore, such die-cast mounting hubs are relatively bulky, take up space and add substantial weight and additional cost to the completed product.
ummarY of the Invention A grinding apparatus having a drive member non-removably affixed thereto for mounting on a rotatable spindle of a power tool. The drive member includes a backins flange on one side of the apparatus and a retaining nut positioned on the opposite side of the apparatus from the backing flange. The nut extends through an opening from the face toward the back of the apparatus and has a radial flange at one end thereof seated against the face of the apparatus and protrusion means extending from the other end thereof for non-removably securing the retaining nut and the backingflange together on the apparatus without the use of adhesives.
Loosely retained upon the power tool spindle is a base member which engages the outer surface of the backing flange to apply pres6ure to the ~lange during operation of the apparatus.
Alternatively, a pressure cap member may be affixed to the protrusion means. The pressure cap defines a central opening through which the power tool spindle extends to engage the nut.
More particularly, the securing means and the base member on the one hand or the pressure cap on the other are adapted to cause the nut and backing flange to place the apparatus in compression between them when the apparatus is operatively secured upon the spindle of the power tool.

~3~

Brief De cr~ption of the Draw_~g~
FIGURE 1 is a cross sectional view of a disposable grinding wheel assembly constructed in accordance with the principles of the present invention and mounted in operable position on the spindle of a power tool;
FIGURE 2 i5 an exploded view of the structure as illustrated in FIGURE 1;
1~ FIGVRE 3 is a cross sectional view of a backing flange constructed in accordance with the present invention;
FIGURE 4 is a cross section view of a retaining nut constructed in accordance with the principles of the present invention;
FIGURE 5 is a cross secti~nal view of the retaining nut of FIGURE 5 after beihg upset;
FIGURE 6 is an alternative construction of a spindle base assembly constructed in accordance with the ~0 present invention for use on small grinding wheels;
FIGURE ~ i5 a cross sectional view of an alternative embodiment of the grinding wheel assembly constructed in accordance with the principles of the present inventlon including a pressure cap and mounted 2~ in operable position on the spindle of a power tool;
FIGURE 8 is a cross sectional view showing construction of the pressure cap constructed in accordance with the present invention;
FIGURE 9 i9 a cross sectional view of another ~0 embodiment of a disposable grinding wheel assembly constructed in accordance with the principles of the present invention;
FIGURE 10 is a cross sectional view of a backing flange constructed in accordance with the present invention;

FIGURE 11 is a cross section view of a retaining nut constructed in accordance with the principles of the present invention;
FI~UR~ 12 is a cross sectional view of the retaining nut of FIGURE 5 after being upset;
FIGURE 13 is an alternative construction of a spindle base assembly constructed in accordance with the present invention for use on small grinding wheels;
1~
Detailed Description By reference now more specifically to FIGURES
1 through 5, there is illustrated a preferred embodiment of a disposable grinding apparatus assembly constructed in accordance with the princlples of the present invention. Although the present invention has utility with respect to any disposable power driven grinding apparatus, the description herein is given with respect to a depressed center grinding wheel. As is shown in the drawings, a depressed center grinding wheel 10 has a disposable drive member assembly 12 permanently aff xed thereto 80 that the grinding wheel ~ay be attacned to the spindle 14 of an appropriate power tool 16.
According to the principles of the present invention, a disposable mounting hub or drive member ls constructed in such a manner that when the grinding wheel i5 placed in operation upon the spindle 14 the grinding wheel 10 is placed in compression and the more force which is applied to the grinding wheel during utillzation thereof, the greater the operational compression becomes. As a result of placing the grinding wheel in such compression the grinding wheel is maintained upon the spindle and cannot fly off and at the same time, through the compression or clamping force as applied, the drive wheel 10 cannot rotate relative to the driving member or hub 12. However, as a result of the construction of the driving member, the spent grinding wheel may be easily removed from ~he spindle for disposal without the utilization of hand tools or the like.
As is clearly shown, the grinding wheel 10 includes a back surface 18 and a front surface 20. The central portion of the grinding wheel is depressed as viewed from the front thereof and as i5 shown at 22, with a correspondinq central raised portion 24 on the back thereof. A centrally located aperture 26 is provided in the depressed center portion of the grinding wheel 10. The purpose of the depressed center of the grinding wheel 10 is to insure that the driving member or spindle does not protrude beyond the face portion 20 of the wheel 10 and thus interfere with a workpiece during the time the grinding wheei 10 is being utilized.
A backing flange 28 is provided and is adapted to be snugly received on the back surface 18 of the grinding wheel lO about the raised portion 24. The flange 28 has a diameter which is less than the diameter of the wheel 10. The backing flange 28 defines a second central aperture 30 therethrough which is aligned with the aperture 26 in the grindinq wheel 10. A pair of .5 reinforcing ribs 32 and 34 are formed in the backing flange 28 concentrically with the opening 30. The backing flange 28 is preferably stamped from sheet metal but of course could be constructed from other materials such as hard molded plastic or die cast metal should 3U such be desired.
As is shown more specifically in FIGURE 3, the backing flange 28 includes an inner surface 36 and an outer surface 38. The inner surface 36 is disposed opposed the back surface 18 of the abrasive finishing wheel 10. The inner surface 36 includes a pair of lands 40 and 42. The land 40 always is formed about the outer ~L3~

peripheral portion of the backing flange 28. The land 42 is displaced inwardly toward the opening 30 and away from the land 40. The land 40 engages the back surface 18 of the abrasive finishing wheel away from the depressed center while the land 42 may engage the back surface of the abrasive finishing wheel 10 opposed the depressed center 22 thereof depending upon variations in wheel dimensions and manufacturing tolerances in the wheel and flanges.
As can be seen, particularly in FIGURE 3, the ribs 32 and 34 formed in the outer surface 38 of the backing flange 22 are continuous. The continuous rib 32 is disposed between the lands 40 and 42 and over the transitional area between the depressed center and the remainder of the grinding wheel lO while the continuous rib 34 is disposed intermediate the opening 30 and the land 42.
A retainer nut 44 includes a body portion 46 which is hollow and has a radially outwardly extending flange 48 at a first end 50 thereof. At the opposite or second end 52 of the body and slightly displaced therefrom there is provided a recess such as a continuous groove 54 which is formed at the time of assembly after the body 46 is inserted through the openings in the wheel 10 and backing flange 28. The internal surface of the body 46 has threads 56 ~ormed therealong for attachment to the threaded spindle 14 of the power tool. The nut 44 is inserted through the aperture 26 in the grinding wheel and the aperture 30 in the flange 28 from the front 20 toward the rear 18 of the grind.ing wheel 10. The end 52 of the nut 44 extends through the opening 30 in the flange 28 for a distance not exceeding the top of the rib 34.
Once the nut 44 has been inserted through the openings in the wheel 10 and the flange 28, the end 52 thereof is upset such as by a staking operation to provide the continuous groove 54 as shown specifically in FIGURE 5. The upsetting operation causes a protrusion 56 to extend outwardly from the body 46 in such a manner as to engage the flange 28 about the outer surface 38 thereof adjacent the opening 30 therethrough and is the only means used for securing the flange 28 and the nut 44 on the wheel 10. The protrusion 56 is illustrated as being continuous as is the groove 54, although it should be understood that it may be intermittent should such be desired. It should become apparent to those skilled in the art that the flange 28 and the nut 44 are mechanically secured together on the wheel 10 between the flange 48 and the protrusion 56 without the use of adhesives.
The nut 44 is preferably constructed from an aluminum extrusion which is then machined to provide the flange 38 and the threads 46. Alternatively the nut may be formed from aluminum or steel bar stock, or a metal die casting.
To provide proper operation of the throw-away grinding wheel as described in one embodiment, there is provided a base assembly 60 which includes a disc 62 having a first surface 64 at least part of which ls adapted for engaging the outer surface 3~ of the flange 28. The disc 62 is held in place on the spindle 14 by a retaining member 66 which, as shown in FIGVRE 1 in the preferred embodiment, may be a nylon annulus which is threadable onto the threaded spindle 14. The nylon annulus 66 will then loosely retain the disc 62 upon the spindle 14 at all times whether or not a grinding wheel is maintained in place. The first surface 64 of the disc 62 defines continuous ridges 68 and 70 which engage the ribs 34 and 32, respectively, of the flange 28 as can be seen. As i5 F,hown the ridges are displaced ~3~8~

downwardly and the disc defines a chamber or pocket into which the nut 44 may be partially retracted during use.
The contact between the ribs and ridges is essentially a line contact. As a result of ~he line contact the wneel 10 ma~ usually be relatively easily removed from the power tool 16. However, because of the tremendous amount of force which may have been exerted by the disc 62 during the grinding operation the spent wheel may sometimes be difficult to remove.
Positioned between the opposite surface 65 of the disc 62 and the shoulder 69 on the power tool 16 is a plastic washer 67 constructed preferably of a self-lubricating plastic. The washer 67 serves two functions. The first function is to accommodate power tools 16 of varying dimensional configurations. That is, the spindle 14 may vary in lengt;- requirin~ spacers to assure the end of the spindle does not protrude beyond the end of the nut 44 by any su~stantial amount.
The second function is to assist in removal of the wneel 10 from the power tool 16 after the wheel 10 is spent.
Since tremendous forces are generated during a grindin~
operation, metal-to-metal surfaces, particularly of similar t~pes, tend to bind or gall thereby necessitating the application of relatively large ~orces to remove the spent wheel. The self lubr:icating dissimilar surfaces between the washer 6'l and shoulder 69 and surface 65 provide an almost immediate release upon the application of m$nimal pressure to wheel 10.
Thereafter the line contact above referred to allows easy separation of the wheel from the base assembly 60.
The force necessary to cause the grinding wheel 10 to be placed in compression is generated upon attachment of the spindle 14 to the threads 56 in the nut 44. By reference to FIGURE 1 it will be noted that when the grinding wheel is threaded upon the spindle 14 .~

~3~

the ridges 68 and 70 engage in a line fashion the ribs 34 and 30 on the flange. The flange is forced in a downward d rection by such engagement. At the same time the interengagement between the threads 14 and 56 of the spindle and nut, respectively, urge the nut upward toward the flange 28 to cause the grinding wheel to be placed in compression. An examination of the drawings, particularly FIGURE 1, will disclose that when t~e grinding wheel is in operation forces are transmitted downwardly from the power tool 16, the washer 6~, the disc 62 and the land 40 of the flange 28. At the same time, forces are being applied upwardly through the flange 48 on the nut 44. These forces are generated through the threaded engagement between tne spindle 14 and the interior 56 of the nùt 44 through application of torque to the rotating wheel when it is placed into engagement with a workpiece. Those skilled in the art will recognize that as the grinding wheel lO is used by being placed against a workpiece additional torque is applied causing the grinding wheel to be further tightened onto the spindle 14. That is, as the grinding wheel moves during contact with a workpiece, the friction between the nut and the grinding wheel center causes the nut to rotate in a further tightening direction. Such rotation of the nut further urges the nut towarcl the flange which in turn applies a further force to the flange. The more the grindirg wheel is tightened the greater the operational compression force becomes and the more securely the grinding wheel lO is clamped between the backing flange 28 and the flange 48 on the nut 44. As a result of this strong clamping or compression the grinding wheel lO is precluded from movement relative to the hub or drivinq member 12 and at the same time is precluded from disengaging from the spindle 14. It should also be noted that the inner surface 64 of the disc 62 provides a space or chamber 71 above the top 52 of the nut 44. This chamber 71 provides room for the nut to move upwardly durinq operation in a manner unrestricted by the power tool or base assembly.
FIGURE 6 illustrates an al~ernati~e structure similar to that shown in FIGURE 1 but specifically designed for use with smaller grinding wheels, for example, those having a diameter of five inches or less.
The only difference is that the disc in the base assembly is of smaller diameter and designed to engage only the ~irst rib adjacent the opening through the backing flange. As is shown, the disc 80 defines a peripheral surface 82 which engages the top surface of the continuous rib 34 on the backing flange 28. It has been found that the smaller grinding wheels do not require the larger backing flange for satis~actory operation although it should be understood that the smaller grinding wheels operate satisfactorily with the larger backing flanges.
Alternatively, as illustrated in ~I~U~ES 7 and 8, to provide proper operational compressive forces of the throwaway grinding wheel as above~descriDed, a pressure cap 90 is snapped into locking eng~gement with the hub assembly lZ. Under these circumstances the base assembly 60 as above described will be dispensed witn.
The pressure cap 90 includes a first rear surface 92 for engaging the surface 69 on the power tool spindle wnen the grinding wheel is in an operable position on the power tool 16. A second or front surface 96 on the pressure cap 90 contacts the top of the continuous rib 34. The pressure cap 9o is retained in position on the hub assembly 12 by a gripping rib 98 which extends radially inwardly from a downwardly depending skirt 84 on the front surface 96 of the body 84 of the pressure ~3~

cap 90. The gripping rib 98 snaps over the protrusion 56 and engages the lip 5~ on the enc 52 of the retainer nut 44. At the same time the surface 74 on the continuous reinforcing rib 34 of the backing flange 28 applies a radially inwardly directed force to secure the gripping rib 98 in place in the space between the lip 57 and the periphery of the backing flange surrounding the opening 30. Preferably the pressure cap 90 is constructed of molded plastic such as polypropylene, polyamide, acetal or the like. The gripping rib 98 may be continuous or intermittent as desired as illustrated by the dashed lines 99. An important feature is that the pressure cap may be easily snapped into locking position as shown in FIGURE 1 by the distributor or user before use if desired or, alternatively, at the time of assembly in the factory. Such capability saves space in shipment in that the assembled wheel without the pressure cap may be packed in containers with pressure caps placed in interstices between wheels or wheels and the container. Thus a greater number of wheels may be packaged, on top of each other, in the same container.
It will also be recognized that the pressure cap 90, once installed, remains on the g~inding wheel and is di~sposed of along with the spent wheel.
The force necessary to cause the grinding wheel 10 to be placed in compression is generated upon attachment of the spindle 14 to the threads 56 in the nut 44. By reference to FIGURE 7 it will be noted that when the grinding wheel is threaded upon the spindle 14 the surface 92 engages the surface 69. Force i5 thus transmitted through the pressure cap 90 to the backing flange 28 through the contact between the surface 96 and the reinforcing rib 34 causing the backing flange to be forced in a downward direction. At the same time the interengagement between the threads 14 and 56 of the spindle and nut, respectively, urge the nut upward toward the flange 28 to cause the grinding wheel to be placed in compression. Those skilled in the art will recognize that as the grinding wheel 10 is used by being placed against a workpiece additional torque is applied causing the grinding wheel to be further ti~htened onto the spindle 14 as was the case with the base assembly 60.
By reference now more specifically to FIGU~ES
9-13, there is illustrated another embodiment of a disposable grinding wheel-drive member assembly constructed in accordance with the principles of the present invention. As is therein shown a depressed center grinding wheel 10 has a disposable drive member assembly 12 permanently affixed thereto so that the grinding wheel may be attached to the spindle 14 of an appropriate power tool shown in phantom at 16.
As is clearly shown, the grinding wheel 10 includes a back surface 18 and a front surface 20. As is clearly shown the central portion of the grinding wheel is depressed as viewed from the frort thereof and as is shown at 22, with a corresponding central raised portion 24 on the back thereo~. A centrally located aperture 26 is provided in the depressed center portion of the grinding wheel 10.
A backing flange 128 is provided and is adapted to be snugly received on the back surface 18 of the grinding wheel 10 about the raised portion 24. The flange 128 has a diameter which is less than the diameter of the wheel 10. The backing plate or flange 128 defines a second central aperture 130 therethrough which is aligned with the aperture 26 in the grinding wheel 10. A reinforcing rib 132 is formed in the backing flange 128 concentrically with the opening 130.
The backing plate or flange 128 is preferably stamped 13~

from sheet metal but of course could be constructed A~rom other materials such as hard molded plastic should such be desired.
A retainer nut 134 includes a body portion 136 which is hollow and has a radially outwardly extendin~
flange 138. At the opposite end 142 of the body and slightly displaced therefrom there is provided a recess such as a continuous groove 144. The internal surface of the body 136 has threads 146 formed therealong for attachment to the threaded spindle 14 of the power tool.
The nut 134 is inserted through the aperture 26 in the grinding wheel and the aperture 130 in the flange 128 from the front 20 toward the rear 18 of the grinding wheel 10.
A hollow cup-shaped member 150 is slipped over the upper portion of the retaining nut which extends beyond the flange ~8 and is non-removably secured to the nut by depressing a portion thereof into the groove 144.
As is shown, the hollow cup (spindle cup) has a side wall 152 with a radially outwardly extending flange 154 disposed at the end 156 thereof. The opposite end 15 of the sicle wall 152 is turned inwardly and defines a third aperture 160 therethrough. The inwardly turned portion of the side wall 152 al60 functions a~s a locating area for the spindle 14 of the power tool '6 thus making it relatively easy for a user to locate the grinding wheel upon the power tool 16. The side wall 152 of the cap 150 may be affixed to the groove 144 of the nut by a simple staking operation to provide indentations as shown at 164 and 166 of FI~UR~ 1. It will be obvious to those skilled in the art that the indentations 164 and 166 may be one or more in number and may be independent or alternatively a compete continuous upset of the side wall 152 may be accomplished if desired. It will further be recognized that the continuous groove 144 may be formed in a discontinuous manner, that is, a plurality of recesses should such be desired. In any event the cup 150 is affixed to the nut 134 in a non-removable fashion but in such a manner that the cup and nut may be urged relatively toward each ot~er to place the grinding wheel 10 in compression.
The force necessary to cause the grinding wheel 10 to be placed in compression is generated upon attachment of the spindle 14 to the threads 146 in the nut 134. By reference to FIGURE 1 it will be noted that when the grinding wheel is threaded upon the spindle 14 the surface 69 (which may be an appropriate washer, spacer or a portlon of the spindle) engages in a line fashion, the upper surface 170 of the domed or curved portion 162 of the side wall 152. Thus, the cup is forced in a downward direction by such engagement. At the same time the interengagement between the threads 14 and 146 of the spindle and nut, respectively, urge the nut toward the cup. Since the surface 172 of the flange 154 on the cup 150 engages the surfaces 174 on the backing flange 128, a force is applied through the backing flange and the back surface 18 of the grinding wheel 10 to cause the yrinding wheel to be placed in compression as above described with respect to the base assembly 60 and the pressure cap 90.
If desired, the flange 128 and the cup 150 may be formed as an integral unit as is shown in FIGURE 12.
If such is desired, the composite nut-flange may be stamped from a single piece of sheet metal to provide the desired depression area 180 to accommodate the raised portion 24 of the depressed center wheel. From the central section of the body 182 there would be extended the side walls 184 of the cup with the inwardly turned end 186 to provide the dome structure 188 as ~L3~

above described. As desired, the reinforcing -ing l9O
may also be included.
It will be recognized by those skilled in the art that the grinding wheel assemblies as illustrated in the drawings and as above described requires no adhesive for construction and may be simply and easily assembled, is relatively light in weight as compared to the prior art devices utilizing the cast hubs and provides a secure attachment of the grinding wheel to the power tool and through the utilization of the increased compression precludes relative rotation of the grinding wheel with regard to the driving member. It has also been discovered that the utilization of the device as lS above described and as constructed in the preferred embodiment is extremely smooth in op~ration with no vibration. The reason for such extremely smooth operation is that all of the parts are perfectly aligned one with the other with the abutting surfaces parallel when in compression and only the wheel lO can cause any vibration and then only if it is not properly ~alanced during the construction thereof.
Through the structures as illustrated and described, all currently known sizes of standard diameter depressed center grinding wheels, namely four inch, four and one half lnch, ~ive inch, seven inch and nine inch may be accommodated. At the present time, through the utilization of the die-cast integral hub-flange structure, only seven and nine inch grinding wheels utilize the throw away hub while the four, four and one half and five inch wheel utilize the conventional two-piece mountinq set traditional in the prior art and as above described.
There has thus been disclosed a disposable grinding wheel-driving member assembly which securely holds the grinding wheel during operation, which is ~3~5~

light in weight, vibration-free, and less expensive than prior art throw-away grinding wheels while meeting all safety standards currently known and in existence.

Claims

1. In a disposable finishing apparatus having a face and a back with a first central aperture, a disposable drive member for securing said apparatus on a threaded rotatable shaft of a power tool characterized in that said drive member includes:
a backing flange having a diameter smaller than the diameter of said finishing apparatus and defining a second centrally disposed aperture therethrough, said backing flange seated on said back of said finishing apparatus with said first and second apertures aligned;
a retaining nut having a hollow internally threaded body having first and second ends, a first radially outwardly extending flange extending from said first end of said body, said body extending through said first aperture from said face toward said back with said flange seated against said face; and means including said second end of said body for non-removably securing said retaining nut and said backing flange to said apparatus without the use or adhesives while permitting relative axial movement between said retaining nut and said backing flange toward each other as loads are applied to said apparatus during use to compress said apparatus between said backing flange and said flange on said nut.

2. A disposable drive member for a finishing apparatus as defined in claim 1 wherein said securing means includes means outwardly protruding from at least a portion of said second end of said body.

3. A disposable drive member for a finishing apparatus as defined in claim 2 wherein said portion of said body includes a continuous ring seated against said backing flange.

4. A disposable drive member for a finishing apparatus as defined in claim 3 wherein said second end of said body is upset to provide said continuous ring.

5. A disposable drive member for a finishing apparatus as defined in claim 4 wherein said backing flange includes an inner surface and an outer surface and wherein said inner surface is disposed opposed said back of said apparatus and includes an outer peripheral land, said land contacting said back of said apparatus.

6. A disposable drive member for a finishing apparatus as defined in claim 5 wherein said outer surface of said backing flange includes rib means extending therefrom.

7. A disposable drive member for a finishing apparatus as defined in claim 6 wherein said rib means includes first and second continuous ribs.

8. A disposable drive member for a finishing apparatus as defined in claim 7 wherein said backing flange is formed of sheet metal and said land and ribs are formed by stamping said sheet metal back flange.

9. A disposable drive member for a finishing apparatus as defined in claim 1 wherein said finishing apparatus is a depressed center grinding wheel.

10. A disposable drive member for a finishing apparatus as defined in claim 1 which further includes means disposed between said backing flange and said power tool for applying force to said backing flange as said shaft draws said nut toward said tool by threaded engagement therewith to effect said compression.

11. A disposable drive member for a finishing apparatus as defined in claim 10 wherein said means for applying force is carried by said shaft.

12. A disposable drive member for a finishing apparatus as defined in claim 11 wherein said means for applying force is loosely held on said shaft and which further includes an annulus threaded onto said shaft for retaining said means for applying force thereon.

13. A disposable drive means for a finishing apparatus as defined in claim 11 wherein said means for applying force is a base plate defining a third centrally disposed aperture which is axially aligned with said first and second apertures and downwardly displaced ridge means for contacting said backing flange.

14. A disposable drive means for a finishing apparatus as defined in claim 13 wherein said base plate defines a chamber between the combination of said backing flange and nut and said base plate into which said second end of said nut may be drawn during operation.

15. A disposable drive means for a finishing apparatus as defined in claim 10 wherein said means for applying force is carried by said finishing apparatus.

16. A disposable drive means for a finishing apparatus as defined in claim 15 wherein said means for applying force is a cap member.

17. A disposable drive means for a finishing apparatus as defined in claim 16 wherein said cap member is constructed of molded plastic and is removably secured to said apparatus.

18. A disposable drive means for a finishing apparatus as defined in claim 16 wherein said cap member is constructed of metal and is non-removably secured to said apparatus.

19. A disposable drive means for a finishing apparatus as defined in claim 5 which further includes a base means for attachment to said threaded shaft for engagement with said outer surface of said backing flange when said apparatus is threaded onto said rotatable shaft.

20. A disposable drive member for a finishing apparatus as defined in claim 19 wherein said outer surface of said backing flange includes rib means extending therefrom and said base means includes a disc having a first surface for engaging said rib means and means for loosely retaining said disc on said shaft in the absence of said apparatus.

21. A disposable drive member for a finishing apparatus as defined in claim 20 wherein said disc first surface defines continuous ridge means for engaging said rib means substantially in line contact.

22. A disposable drive member for a finishing apparatus 25 defined in claim 21 wherein said means for loosely retaining said disc is an annular member formed of plastic and threadable upon said shaft.

23. A disposable drive member for a finishing apparatus as defined in claim 2 wherein said rib means includes first and second continuous ribs and said disc includes first and second ridges for engagement with said first and second ribs substantially in line contact.

24. A disposable drive member for a finishing apparatus as defined in claim 19 wherein said base means further includes washer means disposed adjacent said shaft on said power tool.

25. A disposable drive member for a finishing apparatus as defined in claim 24 wherein said washer is constructed of material which is dissimilar to said power tool.

26. A disposable drive member for a finishing apparatus as defined in claim 25 wherein said washer is plastic.

27. A disposable drive member for a finishing apparatus as defined in claim 26 wherein said washer is a self-lubricating plastic.

28. A disposable drive member for a finishing apparatus as defined in claim 2 wherein said outwardly protruding means defines a lip and which further includes pressure cap means defining a centrally disposed opening therethrough and having means for gripping said lip to secure said cap to said apparatus.

29. A disposable drive member for a finishing apparatus as defined in claim 28 wherein said outwardly protruding portion of said body includes a continuous ring seated against said backing flange and defining said lip.

30. A disposable drive member for a finishing apparatus as defined in claim 29 wherein said means for griping includes a radially inwardly directed member.

31. A disposable drive member for a finishing apparatus as defined in claim 30 wherein said pressure cap further includes a cap body having a downwardly depending skirt terminating in said gripping means.

32. A disposable drive member for a finishing apparatus as defined in claim 31 wherein said cap body, includes a first surface for engaging said power tool shaft and a second surface for engaging said backing flange when said pressure cap is secured to said apparatus.

33. A disposable drive member for a finishing apparatus as defined in claim 32 wherein said backing flange has an inner and an outer surface and wherein said outer surface of said backing flange includes a continuous reinforcing rib extending therefrom and wherein said second surface engages said reinforcing rib.

34. A disposable drive member for a finishing apparatus as defined in claim 33 wherein said reinforcing rib is disposed adjacent and surrounding said outwardly protruding portion of said retainer nut and said pressure cap gripping means is disposed between and in engagement with said rib and said outwardly protruding lip.

35. A disposable drive member for a finishing apparatus as defined in claim 34 wherein said rib urges said gripping means toward said lip as said pressure cap is secured in place on said wheel.

36. A disposable drive member for a finishing apparatus as defined in claim 35 wherein said gripping means is an inwardly directed ridge at the terminus of said skirt.

37. A disposable drive member for a finishing apparatus as defined in claim 36 wherein the terminus of said skirt defines a plurality of notches therein.