A DRIVE ATTACHMENT FOR A POWER DRILL OR LIKE TOOL

Abstract: A drive attachment for a power tool utilising a chuck which enables the tool to be used as a screwdriver or other tool without removing a drill bit from the chuck, comprises a tubular portion 1 adapted to fit over the bit and having at one end drive means providing direct driving engagement with the jaws or head of the chuck. The drive means may comprise a circumferentially spaced array of two or more longitudinally extending projections 2 adapted to engage in the spaces between the chuck jaws. A male or female portion 3 of non-circular configuration fits into or over a correspond­ ingly shaped portion 3a of a nut-runner 5 or other tool component. The attachment may be retained by grub screws 4. If required the attachment can be closed at one end to completely shroud the drill bit. The closed end may be shaped as or provided with, the tool component which is to be rotatably driven, such as a screw driver head. In other examples the projections may be movable radially to engage the chuck head, for example to engage in key holes in the chuck.

Description: TITLE "A drive attachment for a power drill or like tool" TECHNICAL FIELD AND BACKGROUND ART This invention relates to an attachment which can be used to provide a drive connection between a tool such as a screwdriver, a nut-runner or other tool requiring a rotary drive and the chuck of a power drill or like tool utilising a chuck. - The invention is primarily concerned with screwdriving but can clearly be applied to other operations for which a power tool can be used, for example, drilling, grinding, engraving, reaming, cutting or countersinking, and could also be used to drive a tap or die holder. It is well known to use a power drill to bore a hole in wood or masonry, and then to use the same drill to drive a screw into the hole. This normally involves first removing the drill bit from the chuck of the power drill and then inserting the screwdriver bit and re-tightening the chuck. This is time consuming. Another drawback is that the drill bit is soften very hot and this makes removal somewhat difficult and may be dangerous. It has been proposed to use a screwdriver in the form of a sleeve or tube which fits over the drill bit and can therefore be operated without removing the bit. This results in a considerable saving in time where a large number of holes have to be bored and screws individually inserted. It is an object of the present invention to provide a drive attachment which simplifies the drive connection between a power tool and a screwdriver or other tool requiring a rotary drive temporarily coupled to the power tool. STATEMENTS OF INVENTION According to the present invention there is provided a drive attachment for a power tool utilising a chuck, the attachment comprising a tubular portion adapted to fit over a drill bit mounted in the chuck and having at one end drive means adapted to provide a direct driving engagement with the--chuck jaws or the chuck head of the power tool. Further according to the present invention there vs provided the combination of a drive attachment as specified in the immediately preceding paragraph and a power tool utilising a chuck within which is mounted a drill bit and wherein the bit is received within the tubular portions of the attachment and the drive means at the end of the attachment is in direct driving engagement with the chuck jaws on the chuck head of the power tool. The drive means may comprise one or more lugs or projections and these lugs or projections preferably extend longitudinally but they may extend radially with respect to the tubular portion. If the lugs extend longitudinally they will usually be three or four in number and are preferably dimensioned so as to engage in the circumferentially disposed spaces between the three or four jaws of the chuck. If the lugs ox projections extend radially they may be movable radially into driving engagement with the chuck head, for example into the chuck key-holes. Instead of using lugs or projections the drive means may comprise a friction grip acting on the cylindrical surface of the chuck head. Thus it may comprise a rubber or plastics sleeve or ring provided with means for forcing it tightly against the said cylindrical surf ace The parts of the sleeve adjacent the chuck key-holes may be forced partly into these holes thereby improving the friction drive. The attachment according to the invention may be made of metal or of suitable plastics material, or of a combination of metal and plastics The attachment may be made to suit any size of drill bit or supplied blank (that is without the centre hole forming the tubular portion so that the blank can be drilled to form the tubular portion by the bit over which it will be used to give very accurate location for precision work). For masonry work it is likely that one size of centre hole for the tubular portion (say that giving 6 mm. clearance) will suit approximately 80E to 90% of industrial, commercial, "Do-it-yourself" and other applications. The-end of the tubular portion remote from. the drive means may have an internal or external polygonal or other non-circular configuration adapted to mate with a portion of complementary shape of a tool component to be driven by the power tool. Alternatively this remote end of the tubular portion may comprise an integral tool piece such as a screwdriver head. FIGURES IN THE DRAWINGS Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings, in which Figure 1 is a side view bf one form of the drive attachment according to the invention; Figure 2 shows the attachment of Figure 1 fitting into a nut runner shown in cross section; Figure 3 is a side view, partly in section, showing a form of screwdriver attachment in accordance with the invention; Figure 4 is a cross section, to a larger scale, on the line A - A of Figure 1; Figure 5 is an isometric view of the drive means at one end of an attachment according to the invention; Figure 6 diagrammatically illustrates a side view of a lug forming part of the drive means of the attachments in the embodiments shown in Figures 1 to 5; ; Figures 7 and 8 are similar views to that in Figure 6 and show modified forms of lugs; Figure 9 is a cross sectional diagrammatic view of a further embodiment according to the invention; Figure 10 is a similar view to that in Figure 9 and shows a still further embodiment, and Figure 11 is a diagrammatic view of part of the arrangement shown in Figure 10. DESCRIPTION OF THE DRAWINGS The attachment shown in Figure 1 comprises a tubular portion 1 having at one end two or more longitudinally extending lugs or projections 2 which are circumferentially spaced and dimensioned so as to fit snugly into the spaces between the jaws of the chuck of a power drill when those jaws receive and are in tight engagement with a drill bit which is received within the tubular portion 1. The other end of the tubular portion 1 comprises a part 3 of polygonal or other non-circular section. Over this part 3 can be fitted a complementarily shaped part 3a of for example a nut runner 5 as shown in Figure 2. One or more grub screws 4 may be used for holding the attachment in place, the screw or screws bearing against the side portions of the drill bit. When a hole has been drilled using the drill bit, the nut runner 5 is simply slipped over the drill bit so that the parts 3 and 3a are in engagement. Preferably the ends of the lugs 2 are bevelled or rounded or otherwise shaped to facilitate ready insertion into the spaces between the jaws of the chuck. The length of the lugs 2 is preferably such that the end faces 6 of the tubular portion at the base of, and circumferentially between, the lugs come into contact with the free outer end portions of the chuck jaws. It is possible that if the lugs 2 are over-long they may tend to get bent in use, hence it is advisable to make them just long enough to give a good driving engagement with the chuck jaws. Each of the lugs 2 preferably has its circumferentially (or peripherally) opposed side faces 7 (Figures 4 and 6) parallel so as to co-operate with the opposed parallel faces of adjacent chuck jaws. Rotary drive from the power tool will be trausmitted through one or the other of the side faces 7 of each lug. If required, the lugs 2 can have their non-driven side faces 8 sloping as indicated in Figures 7 and 8 (that is where the lugs are each in the form of a right-angled triangle the hypotenuse of which comprises the non-driven face 8 of the lug). It is believed that this triangular shape may increase the strength of the lug, although it has the disadvantage that the power tool cannot be used to drive the attachment in reverse (for example, to withdraw a screw or unscrew a nut). The embodiment shown in Figure 3 is similar to that in Figure 1 but the attachment is long enough to shroud the drill bit completely. At the end of the tubular portion 1 remote from the lugs 2 the attachment has a recess 8 for example of hexagonal section to receive, for example, a screwdriver bit 9. Clearly, instead of providing a separate bit 9 the end of the portion 1 could be simply shaped as an in .. . .. . tegral screwdriver head or other tool to be rotary driven. The attachment according to the invention may be made by drilling a bore in a-solid metal rod and then forming the lugs by a grinding operation. Alternatively the lugs may be.first formed by a forging pperation, followed by a drilling operation to produce the bore of the tubular portion. It will be realised that the dimensions of the attachment, such as the diameter of the bore of the tubular portion will vary with the size of the drill bit being used. Similarly the lateral cross sectional dimensions of the lugs 2 will vary with-the size of the drill bit. --By way of example it was found that a 5.5 mm. diameter drill bit required an attachment having lugs 2 that were approximately 3 mm. x 4 mm. and equally spaced circumferentially. The internal diameter of the tubular portion was 5.7 mm. and the external diameter 10.2 .mm. In the example shown in Figure 9 the attachment comprises a tubular portion 11 which fits over a drill bit D and is rigidly connected to a tubular housing or sleeve 12 which fits over the head H of the chuck of a power tool such as a drill. This housing 12 is provided with three radially extending projections (not shown) which can readily be moved into driving engagement with the key holes 13 of the drill chuck The projections may be in the form of pins, rods or balls and known mechanism such as a locking ring 14 is provided for advancing the projections into driving engagement with the holes 13 and releasably holding them there during use of the attachment. The locking ring 14 may comprise a ring with three tapered sections each of which forces one of the lugs or projections into one of the holes 13 when the ring is rotated. Once again it is not necessary to remove the drill bit when the attachment is fitted and a considerable saving in time is effected. In an alternative arrangement the locking ring may comprise several tapered sections adapted to clamp a radially displaceable ring of, for example, rubber or plastics material against the cylindrical outer surface of the chuck head. It will be found that the friction between the chuck head and a rubber or plastics ring provides sufficient grip to transmit drive to, for example, a screwdriver or like tool attachment. In a modification of the example shown in Figure 9, instead of making the parts 11, 12 integral with each other, the tubular portion 11 may have an end section or a recess of polygonal or other non-circular configuration adapted to fit snugly into or over a complementarily shaped recess or section at one end of the sleeve 12. Instead of having a locking ring 14 the sleeve 12 may have three . projections located so that they can be advanced into the three chuck key holes 13. Each projection may, for example, comprise a grub screw having an unthreaded hole-engaging portion at its inner end. In the example shown in Figure 10 the projections or lugs 2 are partly embedded in an outer member 18 which may be shaped somewhat in the form of a hollow screwdriver handle. The member 18 may be made, for example, as an injection moulded plastics component with the lugs or projections projecting internally thereof. The attachment may be secured in place on the chuck by means of one or more grub screws 15 engaging the chuck head or one or more grub screws 16 engaging the drill bit. The end 17 of the member 18 remote from the chuck can be appropriately shaped (for example, hexagonal) to receive a complementarily shaped socket in a tool component to be driven. The whole unit could be diecast Mazack and therefore relatively inexpensive. Figure 11 shows a part of the embodiment of Figure 10 with certain parts omitted for the sake of clarity for example only one of the lugs 2 is shown, The drill bit D is shown held by means of chuck jaws J. In a modification of the embodiment of Figures 10 and 11, instead of having three separate metal lugs 2 embedded in the plastics member 18, the three lugs may project from a single cylindrical metal member which is itself embedded in the plastics material It will be realised that the drive attachment according to the invention can be used to drive any known type of screwdriver bit, for example slotted, or those known by the Trade Marks "Phillips", "Posidrive", "Supadrive" or "Robinson" pr a nut runner, Allen Key driver and the like, or a tap holder, die holder, chuck or collet, flexible drive countersink bit or other component which is intended to be rotary driven

Claims: CLAIMS 1. A drive attachment for a power tool utilising a chuck characterised by a tubular portion (1) adapted to fit over a drill bit (D) mounted in the chuck (H) of the power tool, and having at one end drive means (2) adapted to provide a direct driving engagement with the chuck jaws or the chuck head of the power tool. 2. An attachment as claimed in claim 1 characterised in that the drive means comprises at least one lug or projection (2). 3. An attachment as claimed in claim 2 characterised in that the or a lug or projection (2) extends longitudinally with respect to the tubular portion (1). 4. An attachment as claimed in claim 3 characterised in that at least two projections (2) are provided which are circumferentially spaced to be longitudinally receivable in spaces provided between the chuck jaws. 5. An attachment as claimed in claim 2 characterised in that the or a lug or projection extends radially with respect to the tubular portion. 6. An attachment as claimed in claim 5 characterised in that the lugs or projections are intended to be movable radially into engagement with key holes (13) provided in the chuck head. 7. An attachment as claimed in any one of claims 2 to 4 characterised in that the or a lug or projection (2) is dimensioned to be closely received between the jaws of the chuck. 8. An attachment as claimed in any one of claims 2 to 7 characterised in that the free end of the or a lug or projection (2) is rounded or bevelled to facilitate engagement thereof between the chuck jaws or in key holes provided in the chuck head. 9. An attachment as claimed in claim 1 characterised in that the drive means comprises a fiexible sleeve (12) or ring provided with means (14) for displacing and securing the sleeve in frictional engagement with the chuck head (H). 10. An attachment as claimed in any one of the preceding claims characterised in that the end of the tubular portion remote from the drive means has a drive portion (8) adapted to mate with a portion of a complementary shape of a tool component (9) to be driven by the power tool. 11. An attachment as claimed in any'of the preceding claims characterised in that it comprises a screwdriver to be power driven. 12. The combination of a drive attachment as claimed in any one of the preceding claims and a power tool utilising a chuck within which is mounted a drill bit characterised in that the bit (D) is received within the tubular portion (11) 'of the attachment and the drive means at the end of the attachment is in direct driving engagement with the chuck jaws or the chuck head (H). of the power tool.

Inventors: DUNN, CHARLES GLEN
Applicants: DUNN, CHARLES GLEN
Application year: 1982
Main classification: B25B21
IPC codes: B25F3