Abrasive finishing or grinding devices having disposable mounting devices are well known to the art. Many such systems utilize adhesives such as epoxy for securing the mounting system to the abrasive device. One of the features of the present invention is that no adhesives of any type are utilized to secure the hub portion of the mounting system to the abrasive device.

In the prior art there does exist some abrasive finishing or grinding devices having disposable hubs attached thereto without the aid of adhesives. Such devices work quite well, however, there remain disadvantages. For example, such devices contain extra parts which are discarded with the wheel thus producing excessive waste and cost. In addition, because of the high profile of the prior art devices containing the disposable mounting system an excess amount of space is occupied by such structures, particularly when they are stacked one on top of the other for shipping or storage. This in addition increases the overall weight of the abrasive finishing or grinding device containing the disposable mounting system. The best known prior art is illustrated in Applicant's U. S. Patent Nos. 4,760,670; and 4,694,615.

Summarv of the Invention The present invention is an abrasive finishing or grinding device mounting system for removably affixing the abrasive finishing or grinding device to a power tool threaded spindle for use or a threaded arbor secured in a power tool collet or chuck (hereinafter"spindle"). The device has a front and a back surface with a centerly located aperture therethrough, the mounting system includes a hub cap having a contact surface which is adapted to contact the back surface of the abrasive device herein used and which hub cap is disposed by way of a central opening therethrough

upon the spindle and is loosely retained thereon so that the hub cap is loosely positioned upon the spindle for easy removal after use. The retainer may be accomplished by an"O"ring, a nylon washer or similar such device. A hub having a centrally disposed opening therethrough includes a lower radially outwardly extending flange which engages the front surface of the abrasive device and a barrel having a body which extends from the flange and is adapted to be positioned within the aperture in the abrasive device. The barrel body has internal threads formed thereon which are adapted to threadedly receive the spindle. The outer periphery ofthe barrel includes an outer rim which extends upwardly therefrom and is formed integrally therewith. The rim is adapted to be formed into engagement with the back surface of the abrasive device to secure the hub permanently to the device. During use the contact surface on the hub cap engages the back surface of the abrasive device and clamps the abrasive device between the contact surface and the flange with increasing pressure being applied to the device between the contact surface and the flange during use.

Other objects and advantages of the present invention will become more apparent to those persons having ordinary skill in the art to which the present invention pertains from the foregoing description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings FIG. 1 is an exploded view of a portion of a power tool including the threaded spindle, the hub cap, the"O"ring retainer and the abrasive device having a hub affixed thereto; FIG. 2 is a view similar to FIG. 1 showing the hub cap positioned upon the threaded spindle of the power tool; FIG. 3 is a view similar to FIG. 2 but showing the abrasive device with the affixed hub threaded onto the threaded spindle of the power tool; FIG. 4 is a partial cross-sectional view taken about the lines 4-4 of FIG. 3 but with the guard of the power tool removed; FIG. 5 is a partial cross-sectional view illustrating one embodiment of the hub of the mounting system in position on an abrasive device;

FIG. 6 is an alternative embodiment of a hub of the mounting system of-the- present invention in position on an abrasive device; FIG. 7 illustrates a hub similar to that of FIG. 5 after being secured to an abrasive device and further illustrates a preferred embodiment of component parts utilized in constructing a hub cap in accordance with the present invention and of the type shown in FIG. 4; and FIGS. 8 through 13 illustrate in cross-section various types of abrasive devices having a hub constructed in accordance with the principles of the present invention affixed thereto.

Detailed Description of Preferred Embodiments of the Invention The mounting system for the present invention has been found to be extremely efficient versatile and is capable of being utilized with abrasive devices having diameters from two inches through nine inches and may be used with devices having smaller or larger diameters without departing from the scope of the invention. A primary feature of the present invention is that the hub cap is placed upon the threaded spindle and is retained loosely in place thereon through the utilization of a retainer member such as an"O"ring, nylon washer, or other such device (hereinafter"O"ring) which is positioned upon the threaded spindle below the hub cap after the hub cap has been placed upon the spindle below the spindle base. Thereafter, the abrasive finishing or grinding device is secured to the threaded spindle of the power tool by way of internally formed threads on a hub which is permanently secured to the abrasive device and is disposed along with the abrasive device when it has been spent through utilization. It can thus be seen that the hub cap remains by virtue of the"O"ring on the spindle of the power tool and only the abrasive device with the hub permanently affixed thereto is discarded. In many prior art devices the entire mounting assembly including the hub cap is discarded with the abrasive device after it has been spent through use.

By referring now more particularly to FIG. 1, there is illustrated schematically and partially in cross-section in a power tool 10 having a guard 12 affixed thereto.

Extending downwardly from the power tool 10 is a threaded spindle 14 having a spindle base 16. A hub cap 18 having a central aperture 20 therethrough is disposed

beneath the threaded spindle 14. An"O"ring 22 is used to loosely retain the hub cap 18 on the threaded spindle 14 after it is inserted thereon by inserting the threaded spindle through the aperture 20. An abrasive device such as a grinding wheel 24 has a hub 26 permanently affixed thereto in a manner to be described more fully below.

By reference now to FIG. 2, there is illustrated the structure of FIG. 1 wherein the hub cap 18 has been positioned upon the threaded spindle 14 as above described and the"O"ring 22 (not shown in FIG. 2) is received upon the threaded spindle 14 to loosely retain the hub cap 18 in position thereon.

By reference now to FIG. 3, the abrasive device 24 has been threaded upon the spindle 14 in such a manner that the hub cap 18 is in engagement with the back surface 28 of the abrasive wheel 24. The top 30 of the hub cap 18 is in engagement with the spindle base 16. It will be noted from FIGS. 1,2 and 3 that the hub cap 18 defines an outer peripheral surface 32 which as formed thereon a plurality of flats such as shown at 34 and 36 thereby defining a substantially hexagonal surface. This surface may be utilized to receive a wrench or similar device in the event that after use it becomes difficult to remove the abrasive wheel by hand. Normally, such does not occur and the wheel may be easily removed simply by applying a counter clockwise force to the abrasive wheel. In some instances, however, it has been found that the forces applied to the wheel during grinding are so great that the wheel is tightened and the clamping forces applied by the mounting system, to be described more fully below, are so great that hand pressure along is insufficient to loosen the wheel from the power tool. Under these circumstances a tool is needed and the wrench may be fitted upon the flats and a slight twist given to eliminate the clamping pressure. The wheel may then easily be removed by hand. This is possible since the hub cap is not in any way integrally affixed to the grinding wheel and is retained loosely by the"O"ring upon the spindle. It is also because of this structure that normally the grinding wheel or other abrasive finishing device can easily be removed by hand.

By referring now more specifically to FIG. 4 the mounting system for an abrasive finishing or grinding device is more fully shown in schematic cross-sectional format and is illustrated with a hub 26 affixed to the abrasive wheel 24. Such is accomplished by forming a portion of a hub 26 as is illustrated at 40 to effectively secure the wheel 24 between a flange 38 which extends radially outwardly from the

body 42 of the hub 26. Upon such forming the hub may deform the upper portion of the opening in the abrasive device. As is illustrated, the hub 26 body includes a centrally disposed opening 44 which defines internal threads thereon which are adapted to receive the external threads found on the spindle 14 to thereby draw the wheel 24 with the hub 26 affixed thereto upwardly into engagement with a contact member 46 formed on the hub cap 18. As is illustrated, the hub cap 18 includes a top 48 and a bridging member 50 which interconnects the top 48 with the contact member 46. The contact member 46 includes a surface which contacts the back surface of the abrasive wheel 24 while the flange 38 contacts the front surface 54 of the abrasive wheel 24.

By reference now to FIG. 5, there is illustrated one embodiment of a hub constructed in accordance with the principles of the present invention. As is therein shown, the hub includes a body 60 having an internally threaded opening 62 therethrough for receiving the threaded spindle. A radially outwardly directed flange 64 is formed at the lower end of the body 60. At the upper end of the body 60 there is define a groove 66 which in turn defines an upwardly extending rim 68. If desired, the upper portion 70 of the body may be deleted so that the rim 68 extends from a position slightly below the back surface 72 of the abrasive wheel 74 so long as sufficient threads remain at the aperture of the body 60 for attachment to the power tool spindle. In either case, through the application of appropriate pressure by simple tools known to those skilled in the art, the rim 68 is formed into engagement with the back surface 72 of the wheel 74 or other abrasive device to trap the device between the flange 64 and the surface 76 of the rim 68 after it is formed as is illustrated in FIG.

4 as well as in FIG. 7.

In reference now, more particularly, to FIG. 6, there is shown an alternative embodiment of a hub constructed in accordance with the principles of the present invention. As is therein shown, the inner portion 76 of the body 78 extends substantially upwardly from the top 80 of the rim 82 with again the groove 84 being such as to be positioned at or slightly below the back surface 86 of the abrasive device 88. The additional extension as shown at 76 provides additional threads 90 for securing the hub onto the spindle for certain devices.

By reference now more particularly to FIG. 7, there is illustrated an abrasive grinding wheel 92 having a hub 94 affixed thereto as above-described. More specifically, the hub cap 96 is shown in its component parts as is illustrated therein.

One of the components is an inverted cup-shaped member 98 having an upper planar portion 100 with a downwardly depending skirt 102 formed thereon. The planar member has an outer surface 104 which is the top of the hub cap. Disposed below the cup-shaped member is a washer-shaped member 106 which has a diameter greater than the cut-shaped member and includes a contact surface 108 which is adapted to engage the back surface 110 ofthe abrasive device 92. Disposed beneath the washer- shaped member 106 is a bell-shaped member 112 having a generally vertical section 114 which extends upwardly and under the skirt 102 and also includes a second vertical section 116 which is displaced outwardly from the vertical section 114. The two vertical sections of the bell-shaped member 112 are bridged by a member which forms the bell-shaped member. To form the hub cap in the configuration as shown in FIGS. 1 through 4, the three component parts namely the inverted cup, the washer and the bell-shaped members are pressed together to cause them to fuse at the contact points and effectively become a unitary member which functions as a hub cap in accordance with the principals of the present mounting system.

An important feature of the present invention is that the lower distal end of the bell-shaped member 112 as shown at 118 engages the back surface 110 along with the contact surface 108 on the washer-shaped member 106. This surface contacts and supports the abrasive device just inside the outer diameter of the flange 38 on the hub 94. This prevents the flange on the hub from being pulled into the abrasive device even under extreme tightening conditions during use.

It is important to note that the distance between the contact surface 108 and the bridging member of the bell-shaped component is greater than the fitness of the outer rim after it has been rolled over as shown in FIG. 7 or FIG. 4. This provides a sufficient clearance as shown at 120 in FIG. 4 to permit the abrasive device 24 to be securely clamped between the flange 38 and the contacting member 46 as using forces are applied to the abrasive device 24 as it is placed against the work surface while being rotated by the power tool 10. It should also be understood that there is also provided a distance between the back surface of the abrasive device and the inner

surface of the planar portion of the cup-shaped member 98, a distance which is greater than the distance measured from the back surface to the upper terminus of the body portion of the barrel so as to provide sufficient clearance for the clamping to occur as above-described. Thus, it can be seen as a result of these clearances that the hub is permitted to travel upwardly as viewed in FIG. 4 as working pressure is applied to the abrasive wheel 24 as it is rotated by the power tool. This upward movement which occurs as the abrasive wheel initially is further tightened as a result of the co-action between the threads in the opening of the body 42 and on the spindle 44 to thereby provide secure clamping to preclude further rotation of the wheel 24 during operation.

By referring now to FIGS. 8 through 13, there is illustrated various abrasive devices which are capable of having the hub as a well described affixed permanently thereto in the manner above-described so that the device may be secured upon the spindle of the power tool which has positioned thereon a hub cap. For example, as is shown in FIG. 8, there is a cut-off wheel, in FIG. 9 there is illustrated a depressed center grinding wheel, in FIG. 10 there is shown a saucer-type device, in FIG. 11 there is illustrated a beveled flexible finishing device, in FIG. 12 there is shown a flap disk and in FIG. 13 a centrally counterbored surface finishing wheel.

With certain abrasive finishing devices such as a four inch diameter or less, a hub cap having only the inverted cup-shaped member as shown at 98 in FIG. 7 may be utilized. Even when such is done, the operation is the same as above-described as are the various clearances and clamping structures. The important thing is that the diameter of the inverted cup-shaped member 98 is sufficiently great that it fits over the outer rim after it has been formed into the back surface of the abrasive device. It should also be noted that it is with such smaller diameter structures that the upper portion of the body of the hub may be eliminated leaving only the outer rim extending upwardly to be formed into the back surface of the abrasive finishing device.

From the foregoing detailed description, it will be evident that there are a number of changes, adaptations and modifications of the present invention which come within the province of those skilled in the art. However, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof as limited solely by the claims appended hereto.