GB2299531A

GB2299531A - Drill/driver chuck

Info

Publication number: GB2299531A
Application number: GB9507025A
Authority: GB
Inventors: Mark Stratford
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 1995-04-05
Filing date: 1995-04-05
Publication date: 1996-10-09
Anticipated expiration: 2015-04-05
Also published as: GB9507025D0; GB2299531B

Abstract

A chuck (2) for use with a drill/driver has an inner body through which clamping jaws (6a, 6b, 6c) may move axially and radially. The jaws (6a, 6b, 6c) each have screwthread engagement with an outer body (8). Rotation of the outer body (8) relative to the inner body causes the jaws to move. The surface of the outer body (8) is formed with three "flats" (14a, 14b, 14c) to aid grip of the chuck (2). This arrangement is particularly beneficial with spindle - locked drill/drivers.

Description

DRILL/DRIVER CHUCK The present invention relates to drill/driver chucks and has particular, though not exclusive, relevance to drill/driver chucks for use with spindle-locked drill/drivers.

So-called spindle-locked drill/drivers generally comprise a conventional power drill or screwdriver having a motor which may drive an output spindle of the drill/driver in a rotary manner about its axis. The output spindle carries implements such as drill bits or screwdriver heads and use of a spindle-lock permits use of the tool manually, ie without power. The locking mechanism allows rotation of the output spindle by the motor but locks rotation of the spindle when torque is applied at the implement end of the spindle or the housing of the drill/driver so as to permit manual use of the tool. Such a spindle-locked drill/driver is described, for example, in US-A-5,016,501.

Whether or not a drill/driver incorporates a spindle-lock, there is always a need to have some mechanism by which the drill bit or the screwdriver bit can be mounted to and released from the output spindle. Conventionally this is achieved by use of a chuck. The chuck comprises an outer housing including a rotatable ring, the inside surface of which ring bears a screwthread. Rotation of the ring causes jaws within the housing to either converge (thereby to clamp the bit) or diverge (thereby to release the bit). Rotation of this ring was formerly achieved by use of a chuck key which carried teeth to co-operate with teeth on the ring.

Latterly, the housing has been split into two halves, one of which acts as the ring and may be rotated manually relative to the other half of the housing. This requires two-handled operation.

Chucks such as those generally described above are necessary even with spindle-locked drill/drivers. There are, however, several shortcomings with such arrangements. If the type of chuck used is that which requires use of a key, this may often be misplaced by the user. Alternatively, if a manually operable chuck is used, users often encounter difficulties in gripping the two halves of the chuck and applying the necessary amount of torque in order to grip the bit between the jaws sufficiently tightly.

It has been proposed, in the case of manually operable chucks, to form the two halves of the chuck from rubber, or at least to coat their surfaces with rubber, in order to aid the grip of the user. This does not offer a satisfactory solution, however, because in use of the drill/driver, it is common for the chuck to scrape against the workpiece being operated upon and thus tear or wear the rubber away.

It is thus an object of the present invention to at least alleviate the aforementioned shortcomings and provide a chuck for a drilll/driver which neither requires a chuck key, nor necessitates two-handed operation.

Accordingly, the present invention provides a drill/driver chuck having a inner body member within which clamping jaws are slidably mounted and an outer body formed around the inner body and rotatable relative to the inner body, the outer body being of unitary construction and having screwthread engagement with the jaws for advancing the jaws through a forward portion of the inner body to grip a drill/driver bit shank and for retracing the jaws, characterised in that the outer body is generally cylindrical yet formed with at least three substantially planar surfaces on the periphery thereof. This enables the chuck to be gripped by the hand of a user more easily than with previous chucks.The planar surfaces, or "flats" contrast with the rest of the circular periphery of the body member and engage with the hand of the user in such a way as to permit a better grip and, therefore, more torque to be applied than with a chuck of purely circular cross-section Preferably the at least three substantially planar surfaces are equi-spaced circumferentially around the periphery of the body member. Alternatively or additionally, the periphery of the body member bears, or is formed from, areas of relatively high friction material between the planer surfaces.

The present invention will now be described, by way of example only and with reference to the accompanying drawings, of which; Figure 1 shows a perspective view of a drill/driver chuck in accordance with the present invention; Figure 2 illustrates schematically a section through the line X-X of figure 1, and; Figure 3 illustrates schematically a section through a line orthogonal to line X-XX.

Referring to the figures, it can be seen that the drill/driver chuck has an inner body 4 which carries each of three clamping jaws 6a, 6b and 6c. The jaws 6 are able to move slidably within the inner body 4 by virtue of the fact that each of these jaws 6 is formed with a screwthread 7 on its outermost surface. These screwthreads each co-operate with a screwthread formed on the inner surface of outer body 8. Rotation of the outer body 8 causes each of the jaws 6 to move either toward a forward end of the chuck 2 (thereby closing the jaws) or a rearward end of the chuck 2 (thereby opening the jaws) depending upon the sense of rotation of the outer body 8.

It will be understood that any rotation of the outer body 8 must be relative to that of the inner body 4. In this way the screwthread 7 of the outer body 4 co-operates with the screwthreads on each of the jaws 6 to enable the jaws 6 to move. To achieve this relative rotation the inner body 4 is rigidly mounted on a spindle 10. The outer body 8 is then slid over the inner body 4 and a snap-fit connection 11 formed. Between the inner body 4 and the outer body 8 are rollers 12 which enable relative rotation between the bodies.

Referring now particularly to figure 2, it can be seen that although the outer body 4 is substantially cylindrical, it has a cross-sectional shape that is not wholly circular. The cross-sectional shape is formed so as to comprise alternative circular and linear regions. In this way there are provided three "flats", ie planar surfaces, 14a, 14b, 14c which the user of the chuck 2 finds easier to grip with their hand than compared to chucks of purely circular cross-sectional shape. Provision of these flats enables a tighter grip than has been hitherto possible and hence a greater amount of torque is able to be applied to the chuck 2. In order to enhance the grip the user can apply to the chuck 2, the circular regions of the outer body 8 bear serrations 16.

It will be understood by those skilled in the art, that the spindle 10 may be of the locked variety or not. If the spindle is a locking one, then it will only be able to rotate when driven from its side (not shown) remote to that of the chuck 2. The remote side (not shown) would commonly be a power tool. Any attempt to rotate the spindle 10 as shown in the drawings will fail. If however the spindle 10 is non-locking, then rotation of the outer body 8 may cause sympathetic rotation of the spindle 10 and hence there will be no relative movement between the inner 4 and outer 8 bodies and thus no movement of the jaws 6. In this event the user would simply grip the outer body 4 rigid and run the power tool (not shown). This causes rotation of the spindle and hence moves the jaws. This latter possibility is not as effective or as safe, as the former option of using a locking spindle. The principles of locking spindles are well-known to those skilled in the art and so will not be discussed herein.

Whilst in the above three flats have been shown, it will be appreciated that more can be employed. Although this will affect the grip which the user may place upon the chuck, it may have certain advantages for people with either very large or very small hands. However, if the chuck is formed with more than six flats, than this becomes too circular and the advantages of the present invention are lost.

It will be apparent to those skilled in the art that a snap-fit is not the only possible means by which the outer body may be mounted over the inner body. It is possible, for example, that the outer body may be bisected axially and the two halves moulded together around the inner body. In any event this particular feature, in common with the method of operation of the chuck, is not germane to the present invention and so will not be further elaborated upon.

Claims

1 A drill/driver chuck having an inner body within which clamping jaws are slidably mounted and an outer body formed around the inner body and rotatable relative to the inner body, the outer body being of unitary construction and having screwthread engagement with the jaws for advancing the jaws through a forward portion of the inner body to grip a drill/driver bit shank and for retracting the jaws, characterised in that the outer body is generally cylindrical yet formed with at least three substantially planar surfaces on the periphery thereof

2 A drill/driver chuck according to claim 1 wherein the at least three substantially planar surfaces are equi-spaced circumferentially around the periphery of the body member.

3 A drill/driver chuck according to claim 2 wherein the periphery of the body member bears, between the substantially planar surfaces, areas of relatively high friction material.

4 A drill/driver chuck according to claim 3 wherein the areas of relatively high friction material are formed from scores in the surface of the outer body.

5 A drill/driver chuck according to any one of the preceding claims wherein the outer body and the inner body are separated by means of bearings therebetween, the bearings enabling relative rotation between the inner body and the outer body.

6 A drill/driver chuck according to any one of the preceding claims wherein the inner body and the outer body are generally tubular and co-axial and the clamping jaws are simultaneously axially and radially moveable through the periphery of the inner body upon relative rotation between the inner body and the outer body.

7 A drill/driver chuck substantially as hereinbefore described and with reference to the accompanying drawings.