Abstract:
A mounting system for rotating tools such as grinding wheels in a hand-held power tool, includes a hub mountable to the tool drive shaft and a rotating tool element removably affixable to the hub. The tool has at least one flange that engages a corresponding circumferential groove in a hub wall. Both the hub and tool have complimentary lock elements to frictionally retain the tool in a releasably fixed orientation upon the hub. One of the lock elements is in the form of a depression, while a mating element located on the other ports is a complimentary projection.

Description:
The present invention relates to a mounting system for affixing rotating tools, such as grinding wheels, circular saw blades, and the like to a tool arbor such is found in hand-held power tools. 
   BACKGROUND OF THE INVENTION 
   Hand-held power tools, such as grinders, sanders, saws, and the like include a motor driven arbor shaft to which is mounted an appropriate tool head, such as a grinding wheel, sanding disk, or circular saw blade. The arbor is typically threaded, allowing a tool hub to be affixed thereon, such as by a mounting nut assembly. The hub may be an integral part of the rotary tool, but often a hub is provided as an intermediate coupling unit between the arbor and the tool element, which is removably mounted to the hub. This latter form of tool head construction is often preferred, as it allows the work-engaging tool element, such as a grinding wheel, to be removed from the hub when worn without disengaging the hub itself from the arbor shaft. Further, such a construction allows the replacement and interchange of the working tool elements without replacement of the hub. This is of significant value, since during the course of operation a variety of tool elements often are required. This provides for more economical tool element exchange and further lessens the down time of the tool for such exchange. 
   Various constructions have been proposed for mounting disk-shaped tools on a hub in a removable manner. U.S. Pat. No. 6,116,996 to Yanase, for example, utilizes a flange system in conjunction with a gravity-driven stopper to assist maintaining the tool disk in position on a hub-like member. U.S. Pat. No. 6,786,811 to Krondorfer, et al mounts a tool element through a system utilizing circumferential and axial locking elements. Often sanding disks and the like are removably mounted using hook-and-loop fastener systems. While such systems are satisfactory for low rpm operation, they may not provide sufficient holding power for high rpm applications. 
   Notwithstanding the efforts of others, it remains a goal in the tool art to provide a mounting system for rotary tools that allows a rotary tool to be easily and quickly mounted upon or removed from a hub, but securely retains the rotating tool upon the hub to prevent inadvertent disengagement therefrom over a wide range of operating speeds. 
   It is accordingly an object of the present invention to provide such a tool mount which is of economical construction, and allows a rotary tool to be quickly and efficiently mounted upon and removed from a tool hub typically mounted to a tool arbor. 
   It is a further purpose of the present invention to provide such a mounting system that further provides secure retention of the tool element in a fixed position on the hub to prevent inadvertent disengagement therebetween. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In accordance with the foregoing and other objects and purposes, a rotary tool mounting system in accordance with the present invention comprises a hub mountable to the tool drive shaft and a tool element removably mountable on the hub. The tool element has an arcuate flange projecting into a central mounting aperture, while the hub has an axially-extending wall with a circumferential groove to retain the tool element flange. Each of the hub and tool element has at least one complementary lock element in the form of a projection or a mating depression. When the tool element is fully mounted on the hub the projections and depressions align, frictionally retaining the tool element in a fully mounted position on the hub. 
   In a first embodiment the hub may be provided with projections on a face, while the tool element has complementary depressions on an opposed face. In a second embodiment the tool element may have radially inwardly extending projections and the depressions are located on the hub wall. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A fuller understanding of the present invention will be attained upon consideration of the following detailed explanation of preferred but nonetheless illustrative embodiments of the invention, when reviewed in conjunction with the annexed drawings, wherein 
       FIG. 1  is an exploded perspective view of a first embodiment of the mounting system of the present invention; 
       FIG. 2  is a plan view of the hub depicted in  FIG. 1 ; 
       FIG. 3  is a plan view of the tool element of  FIG. 1 ; 
       FIG. 4  is a plan view of the mounting system showing the tool element in a mounted and locked position on the hub; 
       FIG. 5  is a section view taken along line  5 - 5  in  FIG. 4 ; 
       FIG. 6  is a section view of the hub taken along line  6 - 6  in  FIG. 5 ; 
       FIG. 7  is a bottom plan view of a tool element of a second embodiment of the mounting system; 
       FIG. 8  is a top plan view of a hub thereof; 
       FIG. 9  is a top plan view of the tool element; 
       FIG. 10  is a plan view of the second embodiment, depicting the tool element in the mounted and locked position upon the hub; and 
       FIG. 11  is a section view taken along line  11 - 11  in  FIG. 10 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With initial reference to  FIG. 1 , the mounting system of the present invention comprises a generally circular hub  10 , adapted to be mounted upon an arbor of a motorized tool, and particularly upon the arbor of a hand-held tool. The hub includes a central mounting bore  12  to accept the tool arbor or shaft, and may include recesses on its bottom face (not shown) to engage complementary lugs on an arbor flange. The hub is retained on the arbor shaft by means as known in the art, as by a flange and lock nuts. Circular tool element  14  is removably mounted to the hub. As recognized in the art, tool element  14  may be a retaining member to which a working element, such as a sandpaper disk or grinding member is affixed, or may itself comprise a cut-off wheel assembly or circular saw blade unit. The tool element is installed upon the hub by being moved axially with respect to the arbor into contact with hub face  16  and then rotated with respect to the hub into a retained and locked position. Removal of the tool element from the hub is easily performed by first counter-rotating the tool element to disengage the lock mechanism and clear the retention means, and then lifting the tool element axially off and away from the hub. 
   A first embodiment of the mounting system is depicted in  FIGS. 1-6 . Hub  10  has face  16  against which a bottom face of the tool element  14  abuts. Circumferential wall  18  extends upwardly from the hub face surface, axially with respect to the tool arbor on which the hub is mounted. The diameter of tool element mounting bore  20  is chosen to create a closely aligning fit with the wall. As may be seen in  FIGS. 1 and 5 , the wall  18  is undercut along its outer surface adjacent face  16  to provide one or more, and preferably three, circumferential recesses or grooves  22 . 
   Tool element  14  includes spaced flanges or projections  24  extending inwardly along the sidewall  26  of its mounting bore  20 . The projections are dimensioned to be received by the recesses  22 , thereby retaining the tool element  14  upon the hub. As seen in  FIG. 2 , the hub wall  18  is provided with a corresponding number of cut-out portions  28 , complimentary to the shape of the projections  24 , to provide access to the recesses by the aligned projections. With the tool element mounted upon the hub the tool element can be rotated with respect to the hub, moving the projections out of alignment with the receiving cut-outs  28  to retain the tool element on the hub. As seen in  FIG. 1 , each of the grooves  22  terminates at an end wall  30  against which the projections abut to define an endpoint for mounting rotation of the tool element with respect to the hub. 
   To maintain the tool element in the fully mounted position, the hub and tool element are provided with complementary frictional lock elements. As may be best seen in  FIGS. 1 and 6 , the sidewalls  36  of hub grooves  22  are provided with detents  32 , contoured to receive the projection elements  24  as the tool element is rotated into the fully mounted position. Engagement of the projections with these recesses provides a further frictional retaining force between the tool and hub. The recess sidewalls may be inclined away from the center of the hub at areas y-y as they approach the detents  32 , forming a smooth approach surface to the detent while permitting a sufficiently deep detent to be formed to retain the projection. The end wall  30  of the groove may form the distal end of the detent. 
   As seen in  FIGS. 1 and 3 , each of projection elements  24  may be formed as a neck-like portion of the tool element material, typically a tough and resilient plastic or synthetic, about bores  34 . Such a construction provides sufficient resiliency for the projection/flange elements to be slightly deformed or compressed as they engage against the inclined portions of the recess sidewall as the tool element is rotated on the hub, returning to an uncompressed state when they enter the detent depressions  32  to releasably lock the tool element in position. 
     FIGS. 7-11  depict an alternative embodiment of the invention. With initial reference to  FIG. 8 , hub  10  with mounting aperture  12  accepts tool element  14 . Circumferential hub wall  18  has an outer surface  38  which is sized to mate with the inner surface  40  of tool element mounting bore  20 . The surface  40  may comprise the inner edge of a circumferential wall  42  extending upwardly from tool element face  44  to provide a greater bearing surface against the hub wall. 
   As seen in  FIG. 11 , hub wall  18  is again undercut to provide an arcuate recess  22  to accept a pair of opposed arcuate projections or flanges  46  extending inwardly into the mounting bore  20  from the inner bore surface  40 . Wall  18  of hub  10  has a pair of cut-out sections  48  to accommodate the flanges  46 , dividing the recess  22  into two diametrically opposed portions, and to allow the flanges  46  to align with and enter the wall recess or groove portions  22  as the tool element  14  is rotated with respect to the hub  10  for mounting purposes. 
   To maintain the tool element in the fully-mounted position, the hub and tool element are again provided with complementary frictional lock elements. Projections  50  are located on the face  16  of the hub, and may comprise a pair of small metal balls  52  embedded in the hub and extending slightly above the hub face  16 , forming exposed spherical caps. Alternatively, the projections may be merely raised portions of the plastic or similar material from which the hub is formed. As depicted in  FIG. 7 , the lower face  54  of the tool element is provided with corresponding spherical cap depressions  56 , the projecting detent balls  54  engaging with the depressions when the tool element is placed upon the hub and rotated into a locking position. As may be seen in  FIG. 10 , the recesses  22  in the hub wall  18  are stopped at  58 , thus providing a radially-extending end surface against which the forward end of flange  46  abuts when the tool element is fully mounted on the hub. The stops are so located such that abutment with the flanges occur simultaneously with the engagement of the detent projections  50  with the depressions  56 . The resiliency of the tool element material permits the tool element to locally flex as the flange initially contacts and passes over the projections  50  until they enter the depressions  56  to retain the tool element in the fully mounted position.