Tools having removable bits for engaging and driving various fasteners into a workpiece are known. For example, screwdrivers that have interchangeable, removable bits are known. The prior art is dominated with hexagonal driver bits modified with various fasteners to be used in an appropriately modified bit holder. A clearance is provided between the holder and the driver bit to allow ease of insertion and changing of the bit. Various retention methods that rely on interference fits e. g., rubber 0-rings, etc., or mechanical locking mechanism (snap rings, etc.), or magnetic attraction are currently used, but are subject to failure due to breakage, loss of parts, magnetic weakening and wear to the inner surfaces of the bit holder.

U. S. Patent No. 4,209,182 issued to Sheldon discloses an axially movable sleeve retained in the bore of a portable rotary housing, disposed around a spindle to hold captive a ball key which releasably retains a screwdriver bit. The sleeve is retained in the housing by a spring retainer (or the like), whereby the bit (and the retainer) may be removed and replaced by axial displacement of the sleeve. Two patents from Habermehl et. al., U. S. Patent Nos. 5,351,586 and 5,531,143 disclose a screwdriver with a replacement bit assembly, where the bit is secured to a mandrel that is axially slidable in a socket in the end of the mandrel. These patents teach a split-ring on the bit which serves to retain the bit in the socket.

Driver tools are also known in the art. For example, socket drivers are known to employ a displaceable ball bearing retaining mechanism to hold a plurality of sockets on the driver. However, such mechanism are also prone to wear, which can render the retaining mechanism ineffective. Similar driving devices having both male driving portions (e. g., hex keys, Allen wrenches, etc.) and female driving portions (e. g., socket wrenches, etc.) are known, but each suffered from the aforementioned problems associated with screwdriver bits.

Thus, although the prior art discloses various bit and driver retention mechanisms, none of the prior art provides a bit retention mechanism that can be used with standardized holders. Also, prior art devices suffer because there is the need to create complicated retention mechanisms and holders that can break, wear, or are expensive to manufacture.

Accordingly, the present invention solved the aforementioned drawbacks by providing a tool bit with a plurality of engaging projections that are formed within the standard geometric envelope of the shank of the bit, to permit the bit to be manufactured to standard dimensions.

Included in one preferred embodiment is a drill bit, comprising a shank portion having a geometric shape, e. g., hexagonal or circular, within a geometric envelope; and a plurality of projections formed on at least one of the sides or exterior surface of the shank and being within the geometric envelope; the projections engaging an inner surface of a bit holder or chuck to prevent slippage of the bit in the bit holder or chuck. Preferably, the projections have a triangular or sawtooth shape.

Also preferably, the projections have a varying height across the surface; wherein the projections vary in height, from smallest height to biggest height, progressively across the surface.

Advantageously, the drill bit of the present invention has projections on the bit shank that engage the inner surface of the bit holder when torque is applied to the bit thereby preventing slippage of the bit in the chuck. Also advantageously, the shank with projections of the present invention can be manufactured to the tolerances of a conventional drill bit shank so that the bit can be stored in a standardized graded drill bit holder.

In another embodiment, a ball hex key is provided for engaging various sockets, the key having projections (as described above in reference to the first embodiment) on at least the portion thereof that engages a socket. Advantageously, the key provides projections to interlock with the inner surface of the socket to reduce the tendency of the socket to slip off of the key. Also advantageously, the key of the present invention can be manufactured to the tolerance of standard sockets, so that the key can be used within any standard socket.

In yet another embodiment of the invention, a driver size adaptor has projections (as above described) on portions of the surface thereof that engages or joins other tools, to interlock with engaging surfaces of the other tools to reduce the tendency of the adaptor and the tools to separate.

Although the following Detailed Description will proceed with reference being made to preferred embodiments, the present invention is not intended to be limited to these preferred embodiments. Rather, the present invention is of broad scope and is intended to be limited as only set forth in the accompanying claims.

Other features and advantages of the present invention will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals depict like parts, and wherein: Figure 1A is a side elevational view of a drill bit in accordance with one embodiment of the present invention; Figure 1B is an end view of the drill bit of Figure 1A ; Figure 2A is a side elevational view of a drill bit in accordance with another embodiment of the present invention; Figure 2B is an end view of the drill bit of Figure 2A; Figure 2C is a perspective view of a drill bit holder for use with the drill bit of Figure 2A.

Figure 3A is a side elevational view of a drill bit in accordance with yet another embodiment of the present invention; Figure 3B is an end view of the drill bit of Figure 3A; Figure 4A is a side elevational view of an exemplary ball hex key made in accordance with yet another embodiment of the present invention; Figure 4B is a cross-sectional view of the ball hex key of Figure 4A; Figures 5A and 5B are views similar to Figure 4A, in partial cross-section, of a driver adaptor made in accordance with yet another embodiment of the invention.

Figures 1A and 1B depict elevational and end views, respectively, of a drill bit 10 of the present invention. The drill bit is a spade bit with a hex shank end portion 20. As shown in Figure 1B, the bit includes a main shaft defining a geometric envelope 30, having a plurality of flat sides in a geometric shape (e. g., hexagon, rectangle, etc.), with a plurality of surfaces 12. Provided on at least one of the surfaces 12 are one or more projections 14 that are formed on the surface 12 to a predetermined depth 16. The projections 14 can be provided across all or part of the surface 12.

Preferably, the projections 14 are provided on the surface 12 to a depth of between 0.002 and 0.004 inches (0.00508 and 0.01016 cm.), however, the depth of the projections can be altered without departing from the scope of the present invention.

For example, the projections 14 may extend slightly about the surface 12, but within the geometric envelope 30. Also preferably, as shown in Figure 1B, the projections 14 can vary in height of relief (as depicted by angle 18) across the surface 12.

Accordingly, the projections 14 would be of greatest height on the edge of the holder engagable surface where maximum torsional loading occurs when a fastener is being driver by the bit 10.

The bit 22 as shown in Figures 2A and 2B is similar to the above-described embodiment of Figures 1A and 1B, except that the shank end of the shaft 24 is round in cross-section. As depicted in Figure 2A, projections 26 are formed on the periphery surface of the shank. When rotational force is applied to the bit, the projections 26 engage the inner surface of the chuck in such a manner as to prevent slippage of the bit under torque.

A key feature of the present invention is to provide a drill bit that can be used with standardized bit holders or chucks and also may be stored in a standardized graded drill bit holder. Accordingly, the bit 22 of the present invention is formed to an appropriate geometric shape that is within a geometric envelope of a conventional drill bit holder. Thus, the bits 22 of the present invention has a geometric envelope 30 (i. e., cross-sectional diameter) that are within the manufacturing tolerances of a conventional graded drill bit holder 32 (see Figure 2C).

Referring to Figures 3A and 3B, there is illustrated yet another embodiment of the invention. In the embodiment of Figures 3A and 3B, the shank end of the drill shaft is reduced in diameter, i. e., at 40, so that a large diameter drill bit may be used in a smaller diameter drill chuck. For example, a 1/2inch (1.27 cm.) drill bit may be accommodated in a 1/4 inch (0.635 cm.) drill.

In another embodiment, illustrated in Figures 4A and 4B, a ball hex key 50 is provided with projections, as described above with reference to the drill bit, on the engagement end 52 (i. e., male end). The projections 54 are provided to engage the inner surfaces of a socket or threaded fastener. In this case, the portion carrying the projections 54 engage a socket or threaded fastener. Additionally, and optionally, projections 54 may be formed on the other end 56 of the key as well. Also similar to the previous embodiments, the key 50 has a geometric envelope (cross-sectional diameter) that is within the manufacturing tolerance of the socket, or other piece. In addition, the projections 54 can vary in height of relief across the surface.

The invention is susceptible to further modification. For example, as shown in Figures 5A and SB, a driving tool adaptor 60 comprises a square drive socket wrench size adaptor for reducing, e. g., a 1/2 inch (1.27 cm.) square drive 62 to a 1/4 inch (0.635 cm.) square drive (Figure SA), or for stepping up, e. g., from a 1/4 inch (0.635 cm.) square drive to a 1/2 inch (1.27 cm.) square drive (Figure 5B). As in the case of the earlier embodiments, projections 66 are formed on one or more surfaces of the drive stud 62 for enhancing engagement of the drive stud 62 with a socket. As before, projections 66 are contained within the geometric envelope of the drive stud. Also, if desired, one or more of the interior wall surfaces 68 may be provided with projections 70 for engaging with a driving tool.

Thus, it is evident that there has been provided a tool that fully satisfies both the aims and objectives hereinbefore set forth. It will be appreciated that although specific embodiments and methods of use have been presented, many modifications, alternatives and equivalents are possible. For example, the projections can have different shapes, e. g., spikes, circular indents, etc. without departing from the scope of the present invention. Also, as shown in Figures 1A and 3A, the projections may be individually formed at an angle with respect to the surface, e. g., angled away from the driving portion of the shank. Of course, the present invention can be modified with other projection angles without departing form the scope of the present invention. In addition, although the bits described above have been in reference to hexagonal, round and square bits, any geometric cross-sectional shape (e. g., triangular, rectangle, etc.), may be employed. The present invention also can be modified to incorporate the projections, as described herein, on the inner surfaces (i. e., female surfaces) of a socket or other driving mechanism.

Thus, advantageously, the present invention a bit tool that can be manufactured easily, and that can be used with bit holders and sockets of standardized dimensions.