Mounting system for grinding wheels and the like

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.

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.

DETAILED DESCRIPTION OF THE INVENTION

With initial reference toFIG. 1, the mounting system of the present invention comprises a generally circular hub10, 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 bore12to 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 element14is removably mounted to the hub. As recognized in the art, tool element14may 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 face16and 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 inFIGS. 1-6. Hub10has face16against which a bottom face of the tool element14abuts. Circumferential wall18extends 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 bore20is chosen to create a closely aligning fit with the wall. As may be seen inFIGS. 1 and 5, the wall18is undercut along its outer surface adjacent face16to provide one or more, and preferably three, circumferential recesses or grooves22.

Tool element14includes spaced flanges or projections24extending inwardly along the sidewall26of its mounting bore20. The projections are dimensioned to be received by the recesses22, thereby retaining the tool element14upon the hub. As seen inFIG. 2, the hub wall18is provided with a corresponding number of cut-out portions28, complimentary to the shape of the projections24, 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-outs28to retain the tool element on the hub. As seen inFIG. 1, each of the grooves22terminates at an end wall30against 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 inFIGS. 1 and 6, the sidewalls36of hub grooves22are provided with detents32, contoured to receive the projection elements24as 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 detents32, forming a smooth approach surface to the detent while permitting a sufficiently deep detent to be formed to retain the projection. The end wall30of the groove may form the distal end of the detent.

As seen inFIGS. 1 and 3, each of projection elements24may be formed as a neck-like portion of the tool element material, typically a tough and resilient plastic or synthetic, about bores34. 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 depressions32to releasably lock the tool element in position.

FIGS. 7-11depict an alternative embodiment of the invention. With initial reference toFIG. 8, hub10with mounting aperture12accepts tool element14. Circumferential hub wall18has an outer surface38which is sized to mate with the inner surface40of tool element mounting bore20. The surface40may comprise the inner edge of a circumferential wall42extending upwardly from tool element face44to provide a greater bearing surface against the hub wall.

As seen inFIG. 11, hub wall18is again undercut to provide an arcuate recess22to accept a pair of opposed arcuate projections or flanges46extending inwardly into the mounting bore20from the inner bore surface40. Wall18of hub10has a pair of cut-out sections48to accommodate the flanges46, dividing the recess22into two diametrically opposed portions, and to allow the flanges46to align with and enter the wall recess or groove portions22as the tool element14is rotated with respect to the hub10for 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. Projections50are located on the face16of the hub, and may comprise a pair of small metal balls52embedded in the hub and extending slightly above the hub face16, 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 inFIG. 7, the lower face54of the tool element is provided with corresponding spherical cap depressions56, the projecting detent balls54engaging with the depressions when the tool element is placed upon the hub and rotated into a locking position. As may be seen inFIG. 10, the recesses22in the hub wall18are stopped at58, thus providing a radially-extending end surface against which the forward end of flange46abuts 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 projections50with the depressions56. The resiliency of the tool element material permits the tool element to locally flex as the flange initially contacts and passes over the projections50until they enter the depressions56to retain the tool element in the fully mounted position.