FASTENER SYSTEM

The present invention relates to a fastener system, in particular a novel fastener, especially a screw, bolt or the like, and a novel tool for inserting and/or removing the fastener.

It is well known to use fasteners, such as screws, bolts and the like, having a helical thread for engaging with a plain bore or a bore formed with a complimentary thread to that of the fastener. It is also well known to provide a tool for inserting and/or removing such fasteners, very common examples of which are screwdrivers or other tools provided with a suitable bit or other means for engaging with the fastener. Generally, the fastener is provided with a head formed to be engaged by the driving tool, such that the fastener may be rotated about its longitudinal axis for insertion or removal. The efficiency and effectiveness of such fastener systems is very largely reliant upon the proper engagement between the driving tool and the fastener head.

A very common fastener system is one in which the head of the fastener is provided with a slot, extending perpendicular to the longitudinal axis of the fastener. The driving tool is provided with a blade of suitable dimensions to engage with the slot, enabling the fastener to be rotated. A particular problem with this form of fastener arises when the blade of the driving tool is not matched in size and shape to the slot in the fastener head. The use of an improperly matched driver and fastener can result in either one or both being damaged. There is also a risk that the blade of the driver will disengage from the fastener and result in damage to surrounding materials and/or injury to the user.

An alternative form of fastener system relies upon a star-shaped recess being formed in the head of the fastener, the driver being provided with a tapered star- shaped portion to engage with the recess in the fastener head. Such a system in which the star-shaped recess has four lobes is often referred to in the art as a 'philips' fastener. An alternative arrangement with a driver having six lobes is disclosed in US 4,269,246. Again, problems arise when the driver is not matched to the fastener. As noted above, the driver can be caused to slip in the fastener head,

damaging the fastener and/or the driver. There is also the potential for damage to surrounding materials or injury to the user, as noted above.

The above problems with known fastener systems are exacerbated by the increasing use of relatively soft or poor quality materials for the fasteners. Such materials are easily damaged, rendering it impossible to insert the fastener as required. In addition, it is frequently the case that fasteners to be removed are damaged before removal can take place, requiring the user to resort to other time consuming and possible destructive methods of removing the fastener.

Accordingly, there is a need for an improved fastener system to address the aforementioned problems.

In an attempt to overcome the problems of poor engagement of the driver with the fastener, US 2,657,724 discloses a screwdriver with an expandable bit, which can be adapted in size to match the slot in a range of screw sizes. The expandable bit has two lateral blade members, that may be forced apart to the required width by means of a central, sliding wedge member. It is to be noted that the construction of US 2,657,724 involves many moving parts and components, making it difficult to manufacture and use.

One improved fastener system is disclosed in US 3,825,048, in which the fastener is formed with an undercut or dovetailed slot, that is a slot with an inverse taper such that the slot is broader at its inner portion that at its outer portion. A complimentary driver comprises a tapered driver blade provided with a pair of radially shiftable anchors. The anchors are moveable with respect to the blade from a first position, in which the anchors extend from the end of the blade and may be inserted into the slot in the fastener head. The blade is moved between the anchors by applied pressure from the user to the second position, forcing the anchors apart and into engagement with the slot in the fastener. This system is particularly complex to manufacture and operate, requiring the assembly and manipulation of several moving components in the driver. In addition, the driver must be closely matched in size to the fastener, in order for the system to function effectively.

US 4,130,152 discloses a slot-head fastener system, in which the fastener is formed with a transverse, inverted T-slot, which is engaged by the T-shaped end of a complimentary driver. The tip of the driver is inserted laterally into the slot. While this arrangement is of a simple construction, the need to slide the tip of the driver into the slot causes problems when trying to access fasteners in confined or difficult to reach locations.

A fastener and driver system for avoiding inadvertent disengagement of the driver from the fastener is disclosed in US 4,526,071. In this arrangement, the driver is provided with a flat tapered blade of largely conventional design. The blade is provided with a relatively small transverse member or T piece at one edge of the tip of the blade. The fastener with formed with a first slot to receive the blade and a second transverse slot to receive the transverse member. In use, the driver must be applied to the fastener head at an angle, in order to engage the transverse member with the transverse slot, before full engagement with the fastener can be achieved. In one embodiment, the driver is provided with a spring member, to prevent displacement of the blade from the fastener. Again, this system relies upon a driver that is complex to manufacture. Ih addition, it is believed that the transverse member would be vulnerable to being broken during use of the driver. It is also In addition, the fastener is complex in shape, which is unacceptable for a system to be used with a large number of fasteners. As with the previously discussed systems, the driver of US 4,526,071 must be closely matched in size to the slots in the fastener in order for the system to function.

A further fastener system is disclosed in US 4,936, 172. In a first arrangement, the head of a fastener, in particular a screw, is provided with a transverse slot having one or more undercut portions. A complimentary driver comprises a blade with one or more flanges at its extremity. The driver is also provided with a sliding sleeve and extensions. In use, the blade of the driver is inserted into the slot of the screw and rotated, to engage the one or more flanges with the corresponding one or more undercut portions. The sleeve is moved to force the extensions into contact with the screw, in order to hold the driver in engagement with the screw. The arrangement shown and described in US 4,936,172 does not

provide for a similar engagement with the screw for turning the screw in the opposite direction, for example to remove the screw.

In a second embodiment, US 4,936,172 discloses an arrangement in which the screw is formed with a curved recess with undercut portions. The complimentary driver is provided with a blade having a convex flange at its extremity. In use, the blade of the driver is moved in an arcuate path to engage the flange of the blade with the undercut portions of the recess in the head of the screw. A sliding sleeve is again provided to contact the head of the screw and hold the driver and screw in engagement. i

The systems of US 4,936,172 present a number of problems. First, the blade of the driver is particularly complex in both embodiments. Similarly, the head of the screw is difficult to form. In addition, both drivers comprise complex moving parts, which increase the complexity of manufacture and use. Indeed, it is not clear that the driver could be conveniently used with just one hand and may require two handed operation, which is a significant disadvantage. Further, the second embodiment requires the driver to be moved through a significant arc, in order to engage the blade with the screw. This is most undesirable and may preclude the use of the driver in confined situations.

There is a need for an improved fastener system, in which the driver may be easily and quickly engaged and disengaged with the fastener. The driver should be simple in form and easy to manufacture and operate, in particular with one hand. The driver should also be able to be used in confined spaces.

According to a first aspect of the present invention there is provided a fastener system comprising: a driver having a driving portion; a fastener having a head comprising a recess for receiving the driving portion of the driver, the driving portion and the recess being shaped such that rotation of the driving portion within the recess engages the driving portion with the head, such that further rotation of the driver causes the fastener to rotate, wherein the further rotation of the driver increases the engagement of the driving portion with the head.

The fastener system of the present invention provides significant advantages over the known fastener systems. In particular, the need to apply pressure to the driver in order to keep the driving portion engaged with the fastener is removed. This improves the safety of using the system, in particular when working in confined or difficult to reach locations. In particular, the ability to insert the driving portion, rotate the driver and engage with the fastener renders the system very easy to use. In addition, the action of the continued rotation of the driver to increase the engagement of the driving portion with the head of the fastener reduces or eliminates the possibility that the driver portion will become disengaged, reducing or eliminating damage to both the driver and the fastener. The system is particularly useful for the extraction of fasteners.

Continued or further rotation of the driving portion within the recess in the head of the fastener increases the engagement of the driving portion with the fastener. In this respect, increased engagement is a reference to the action of the rotation draws or forces the driving portion into engagement with the fastener. In this way, a higher torque applied to the driver will cause the driving portion to become more tightly engaged with the fastener. In this way, the risk of the driver slipping or jumping out of engagement, with the attendant risk of damage to surrounding materials or injury to the user, is reduced or eliminated.

In a preferred embodiment, the driving portion is tapered in the longitudinal direction, that is the longitudinal direction of the driver and fastener. In this embodiment, the driving portion is tapered to provide the widest portion of the driving portion at its extremity, that is an inward extending taper. In this embodiment, a preferred feature is to provide the driving portion with one or more lateral tapers extending transverse to the longitudinal taper, with the innermost portion of the driving portion being widest, that is one or more lateral outward tapers.

The driving portion may be in any suitable configuration, that engages with the fastener when rotated. As noted, the driving portion most preferably comprises one or more tapers in the longitudinal direction, to engage with one or more corresponding tapers in the head of the fastener. In one embodiment, the driving

portion comprises a tapered member extending laterally across the driver, the member having a generally tapered rectangular cross-sectional form. The head of the fastener has a corresponding generally rectangular, tapered recess for engagement by the member of the driving portion. The member and the corresponding recess may be square. In an alternative embodiment, the member of the driving portion is generally triangular in cross-section, for engagement with a generally triangular recess in the head of the fastener. In these respects, the cross- section referred to is a lateral cross-section through the driving portion of the driver and to a lateral cross-section through the head of the fastener.

In a further alternative embodiment, the driving portion may have a form that, when viewed in cross-section, comprises a plurality of radially extending protrusions, each protrusion comprising one or more tapers extending in the longitudinal direction of the driver. The protrusions are preferably generally rectangular. For example, the driving portion may have a generally cross-shaped or star-shaped cross-sectional form, with each limb of the cross or star comprising one or more of the aforementioned tapers. The number and size of the protrusions may be varied, with 3, 4, 6 or 8 radially extending protrusions being preferred.

The fastener has a recess in its head to receive the driver portion. Again, it is preferred that the recess is tapered in the longitudinal direction of the fastener, with the recess being widest at its innermost portion.

The recess may extend transversely across the head of the fastener so as to open at one or both lateral sides. Alternatively, the recess may be closed at its sides and open only in the longitudinal direction.

The driver may comprise a handle or other suitable drive means for rotating the drive portion, such as in a conventional screwdriver or the like. Alternatively, the driver may be a component to be inserted into a suitable drive means, such as a manual driver assembly or a powered driver assembly or the like. Such a component is known in the art and hereinafter referred to as a 'bit'.

In a further aspect, the present invention provides a driver for use in the aforementioned fastener system, that is a driver having a driving portion at an extremity thereof for engagement with a recess in the head of a complimentary fastener, the driving portion and the recess being shaped such that rotation of the driving portion within the recess engages the driving portion with the head, such that further rotation of the driver causes the fastener to rotate, wherein the further rotation of the driver increases the engagement of the driving portion with the head.

The driving portion and driver are as hereinbefore described.

The present invention also provides a fastener system kit comprising a driver assembly having one or more drivers as defined and described hereinbefore. The fastener system kit may further comprise one or more fasteners.

In a further aspect, the present invention provides a fastener system comprising: a driver having a driving portion; a fastener having a head comprising a recess for receiving the driving portion of the driver, the driving portion and the recess being shaped such that rotation of the driving portion in a first direction within the recess engages the driving portion with the head in a first drive position, such that further rotation of the driver causes the fastener to rotate in the first direction, and rotation of the driving portion in a second direction, opposite to the first, engages the driving portion with the head in a second drive position, such that further rotation of the driver causes the fastener to rotate in the second direction.

Preferred features of the driver and fastener are as hereinbefore described. In particular, it is particularly preferred that continued or further rotation of the driving portion once engaged within the recess increases the engagement of the driving portion with the fastener.

In a further aspect, the present invention provides a driver having a driving portion at an extremity thereof for engagement with a recess in the head of a complimentary fastener, the driving portion and the recess being shaped such that

rotation of the driving portion in a first direction within the recess engages the driving portion with the head in a first drive position, such that further rotation of the driver causes the fastener to rotate in the first direction, and rotation of the driving portion in a second direction, opposite to the first, engages the driving portion with the head in a second drive position, such that further rotation of the driver causes the fastener to rotate in the second direction.

The driving portion and driver are as hereinbefore described. The present invention also provides a fastener system kit comprising a driver assembly having one or more such drivers. The fastener system kit may further comprise one or more fasteners.

As noted, the preferred embodiment of the present invention comprises a tapered driving portion on the driver and a complimentary tapered recess in the head of the fastener. Accordingly, in a further aspect, the present invention provides a fastener system comprising: a driver having a driving portion; a fastener having a head comprising a recess for receiving the driving portion; wherein the driving portion comprises at an extremity a fixed transverse wedge member having a longitudinal taper, the wedge member being arranged to have its widest portion at its extremity; and wherein the recess is tapered in the longitudinal direction to be wider at its innermost portion than at its outermost portion.

The wedge member may further comprise one or more lateral tapers, whereby the innermost portion of the wedge member is wider than one or both lateral sides. In a preferred arrangement, the driver further comprises a shoulder, such that rotation of the driving portion within the recess brings the shoulder into contact with the head of the fastener. In this way, the continued rotation of the driver causing the shoulder to come into contact with the head of the screw increases the engagement of the driver with the fastener, by causing the driving portion to grip the head of the screw.

The present invention also provides a driver for use with a fastener, the driver comprising a driver portion for engaging with a recess in the fastener, wherein the driving portion comprises at an extremity a fixed transverse wedge member having a longitudinal taper, the wedge member being arranged to have its widest portion at its extremity.

The driver may have the features described hereinbefore with respect to this aspect of the invention.

In addition, the present invention provides a fastener system kit comprising a driver assembly having one or more drivers as defined above. The kit may comprise one or more fasteners.

In still a further aspect, the present invention provides an improvement on the well known and long established flat blade fastener system. As noted above, this system relies on a driver having a flat blade to engage with a plain transverse slot in the head of the fastener. Unless the blade is a perfect fit within the slot, the action of rotating the driver causes the edges of the blade to contact the sides of the slot, rather than the faces of the blade. This provides a very small area of contact between the blade and the fastener, leading to damage to the fastener and/or driver and possible injury to the user. The tendency for the blade to disengage from the slot is exacerbated by the taper on the blade. To reduce this effect, the present invention provides a fastener system comprising: a driver having a blade member at an extremity thereof; a fastener having a head, the head comprising a transverse slot for receiving the blade member of the driver; wherein the blade member comprises opposing lateral tapers, whereby the innermost portion of the blade member is wider than both lateral edge portions; and wherein the transverse slot comprises opposing lateral tapers, such that the laterally outermost portions of the slot are both narrower than the innermost portion of the slot.

The present invention further provides a driver having a blade member at an extremity thereof; wherein the blade member comprises opposing lateral tapers,

whereby the innermost portion of the blade member is wider than both lateral edge portions. A fastener for use with the driver has a head, the head comprising a transverse slot for receiving the blade member of a driver; wherein the transverse slot comprises opposing lateral tapers, such that the laterally outermost portions of the slot are both narrower than the innermost portion of the slot.

In one preferred embodiment, the blade member is also provided with tapers in the longitudinal direction of the driver and fastener, with the blade member being widest at its longitudinal extremity.

According to a further aspect of the present invention, there is provided a fastener having a head comprising a recess for receiving the driving portion of a driver, the driving portion and the recess being shaped such that rotation of the driving portion within the recess engages the driving portion with the head, such that further rotation of the driver causes the fastener to rotate, wherein the recess in the head of the fastener is tapered in the longitudinal axis of the fastener, such that the recess is widest at its furthest point from the surface of the head of the fastener, and wherein the recess further comprises one or more lateral tapers extending in a direction transverse to the longitudinal axis of the fastener.

The recess of the fastener comprises a plurality of tapers, the first extending in the longitudinal direction and the second in a transverse direction. In all cases, the tapers extend from the opening of the recess in the head of the fastener such that the recess increases in dimensions, when viewed in plan view, along the longitudinal axis of the fastener extending from the opening into the head.

The recess of the fastener comprises one or more lateral tapers. In this respect, a 'lateral taper' is a reference to a taper extending in the direction transverse to the longitudinal axis of the fastener. The one or more lateral tapers are in addition to and combine with the taper in the recess in the longitudinal direction. The recess preferably comprises a pair of lateral tapers. Each one of the pair of lateral tapers preferably extends from the centre of the recess to a lateral extremity of the recess.

The lateral tapers may be different in size and form, such as the angle of inclination to the longitudinal or transverse directions of the fastener. Preferably, the lateral tapers are each of the same size and form, extending at the same angle in the transverse direction. The taper angles may be different on each side of the fastener.

In one embodiment, the recess is widest at its transverse centre point. In this arrangement, the lateral tapers extend transversely from the centre of the recess, with the lateral extremities of the recess being wider than the central portion of the recess. The lateral tapers may extend in each direction from the same point on each side of the recess.

The recess preferably extends transversely across the head so as to open on opposing lateral sides of the head. Alternatively, the recess may be contained entirely within the head of the fastener, such that the recess is bounded on all sides by the head of the fastener.

The opening of the recess in the surface of the head of the fastener may have any suitable shape. However, a preferred shape for the opening of the recess in the surface of the head of the fastener is rectangular.

The recess may comprise a taper on all sides of the recess in the longitudinal direction, such that the recess increases in dimensions into the head of the fastener.

In all cases, the tapers are preferably continuous across their entire surface, that is the tapered surfaces each have a single profile and all portions of each tapered surface extend at the same angle.

According to a still further aspect of the present invention, there is provided a fastener having a head comprising a recess for receiving the driving portion of a driver, the driving portion and the recess being shaped such that rotation of the driving portion within the recess engages the driving portion with the head, such that further rotation of the driver causes the fastener to rotate, wherein the recess in the head of the fastener is tapered in the longitudinal axis of the fastener, such that the recess is undercut along all sides of the recess.

In the fastener of the this aspect of the invention, the recess has an opening in the surface of the head of the fastener and extends into the body of the head of the fastener. The recess increases in all transverse directions in the longitudinal direction away from the surface of the head of the fastener.

The recess may comprise one or more lateral tapers, as hereinbefore described, preferably a pair of lateral tapers extending along each side of the recess.

As the driver rotates in the recess, any regions of the fastener not swept by the driver can be left solid. This may ease the production of the fasteners and will increase the overall strength and rigidity of the fastener head, improving its resistance to being deformed under applications of high torque.

Further features of the recess are as described previously.

A fastener system kit comprises a driver assembly having one or more such drivers. The fastener system kit may comprise one or more of the aforementioned fasteners.

Finally, the present invention provides a novel use for fasteners having a head with a slot or recess therein that comprises one or more undercut portions. In many applications, in particular in building construction, fasteners are used to secure components of the structure, which are then coated. An example is the use of screws to secure plasterboard, sheet rock or the like, which screws are then coated with plaster or the like to allow the board or sheet to be finished. It is common to find that, due to differential thermal expansion and poor adhesion, the area of coating over and around the fasteners becomes loose and falls away. Fasteners that have plain slots or inwardly tapered recesses, such as Philips screws, provide little or no adhesion for a coating, such as plaster.

Accordingly, the present invention provides the use of a fastener having a head comprising a recess, the recess comprising one or more undercut portions, to

secure a component, wherein the component is coated in a material to cover the head of the fastener.

The fastener may be provided with any suitable form of recess in its head, provided the recess comprises one or more undercut portions to provide an improved adhesion or key with a coating, such as plaster and the like. In a preferred embodiment, the recess comprises an outwards taper, such that the recess is wider at its innermost portion.

Embodiments of the present invention will now be described, by way of example only, having reference to the accompanying drawings, in which:

Figure 1 is a longitudinal cross-sectional view of a driver assembly comprising a driver according to a first embodiment of the present invention;

Figure 2 is a first side view of the driver of Figure 1 ;

Figure 3 is a second side view of the driver of Figure 2 along the line Ill-Ill;

Figure 4a is a first side view of a second embodiment of the driver of Figure 1 ;

Figure 4b is a side view of an alternative design of the embodiment of the driver of Figure 4a;

Figure 5 is a second side view of the driver of Figure 4a along the line V-V:

Figure 6 is a vertical cross-section through a fastener according to the present invention;

Figure 7 is a vertical cross-section through the fastener of Figure 6 along the line VII-VII;

Figure 8 is a vertical cross-section of the driver of Figures 4 and 5 inserted into the head of the fastener of Figures 6 and 7;

Figure 9 is a vertical cross-section of the driver and fastener of Figure 8, with the driver rotated clockwise to engage the driving portion with the fastener head;

Figure 10 is a vertical side view of a driver according to a further embodiment of the present invention;

Figure 11 is a vertical side view of the driver of Figure 10 along the line X-X;

Figure 12 is a plan view of the head of a fastener for use with the driver of

Figures 10 and 11 ;

Figure 13 is a plan view of a driver according to a further embodiment of the present invention;

Figure 14 is a side elevation of the driver of Figure 13 along the line XIV-XIV;

Figure 15 is a plan view of the head of a fastener for use with the driver of Figures 13 and 14;

Figure 16 is a plan view of a driver according a further embodiment of the present invention;

Figure 17 is a side elevation of the driver of Figure 16 along the line XVII- XVII;

Figure 18 is a plan view of the head of a fastener for use with the driver of Figures 16 and 17;

Figure 19 is a plan view of a driver according a further embodiment of the present invention;

Figure 20 is a side elevation of the driver of Figure 19 along the line XX-XX;

Figure 21 is a plan view of the head of a fastener for use with the driver of Figures 19 and 20;

Figure 22 is a plan view of a driver according a further embodiment of the present invention;

Figure 23 is a side elevation of the driver of Figure 22 along the line XXIII- XXIII;

Figure 24 is a plan view of the head of a fastener for use with the driver of

Figures 22 and 23;

Figure 25 is a plan view of a driver according a further embodiment of the present invention;

Figure 26 is a side elevation of the driver of Figure 22 along the line XXVI- XXVI;

Figure 27 is a plan view of the head of a fastener for use with the driver of Figures 25 and 26;

Figure 28 is a plan view of the head of the fastener according to a preferred embodiment;

Figure 29 is a plan view of the head of the fastener according to a further embodiment;

Figure 30a is a plan view of the head of the fastener according to a further embodiment;

Figure 30b is a plan view of the head of the fastener according to still a further embodiment;

Figure 31 is a plan view of the head of a fastener according to a yet further embodiment;

Figure 32 is a plan view of the head of a fastener according to a further alternative embodiment; and

Figure 33 is a plan view of the head of an alternative fastener of the general type shown in Figure 32.

Referring to Figure 1 , there is shown a driver assembly, generally indicated as 2, of generally conventional construction. The driver assembly 2 comprises a handle 4 and a driver shaft 6 coaxial with and extending from the handle 4. The driver shaft 6 is tubular, at least at its end portion 8, and receives a driver 10 according to the present invention. The driver 10 is retained in the driver shaft 6 by conventional means (not shown) such as a ball detent and/or by one or both of the driver shaft 6 and the driver 10 being magnetic. Details of the driver 10 are shown in Figure 2 and described below.

Shown in Figure 2 is a first detailed side view of the driver 10 of Figure 1.

Figure 3 is a second side view of the driver 10. The driver 10 is elongate and generally hexagonal in cross-section, as is known in the art. The driver 10 comprises a driving portion 12 at one end extending transversely across the driver 10. The driving portion 12 has opposing tapered surfaces 14 and 16, such that the extremity 18 of the driving portion 12 is wider than the inner portion 20. The driving portion 12 extends from the end of the driver 10, to leave a shoulder 22 adjacent the innermost portion 20 of the driving portion 10.

Referring to Figures 4a and 5, there is shown a second embodiment of the driver of Figure 1. The driver 110 is of the same general configuration as that of Figures 2 and 3 and comprises a transverse driving portion 112 at one end. The driving portion 112 has opposing tapered surfaces 114 and 116, each of which have lateral tapered faces 114a, 114b and 116a, 116b. A shoulder 122 is formed on the

end portion of the driver 110 adjacent the innermost portion of the driving portion 112, as in the embodiment of Figures 2 and 3.

Referring to Figure 4b, an alternative to the arrangement shown in Figure 4a is shown. The driver of Figure 4b has the same general features as that of Figure 4a identified using the same reference numerals and as described above. However, the lateral tapered faces 114a, 114b and 116a, 116b extend at a more acute angle to the end face of the driving portion.

Referring to Figure 6, there is shown a fastener of the present invention, generally indicated as 200 for use with the driver of Figures 1 to 5. The fastener 200 is of conventional general design and comprises a head 202 and a shank 204 bearing a thread. The head 202 is provided with a transverse recess 206. The recess 206 is tapered, as shown in Figure 7, with the wider portion of the recess being the innermost portion 208.

Referring to Figure 8, the driver 110 of Figures 4 and 5 has been inserted into the recess 206 of the fastener 200 of Figures 6 and 7. As is shown, the driving portion 112 of the driver 110 is sized to enter the recess 206 when the driving portion 112 and the recess 206 are properly aligned. The driver 110 is then rotated in a clockwise direction to engage the driving portion 112 with the head 202 of the fastener 200, as shown in Figure 9. In this position, the lateral tapered face 114a is brought into contact with one side wall of the recess 206, while the opposing lateral face 116b is brought into contact with the opposite side wall of the recess 206. With the driving portion 112 and fastener head 202 engaged in this way, the driving portion cannot be removed from the fastener head by a simple longitudinal pull, helping the driver 110 to stay engaged with the fastener 200. In addition, rotation of the driver 110 causes the tapered surfaces of the driving portion 112 to interact with and bear against the side walls of the recess. This locks the driving portion 112 in the recess 206. Further or continued rotation of the driver 110 causes the driving portion 112 to be pulled into and more tightly locked into the recess. This is further aided when the shoulder 122 abuts the surface of the fastener head 202.

Removal of the driving portion 112 from the recess 206 is simply a matter of rotating the driver 110 in the reverse direction until the driving portion 112 and the recess 206 are aligned. Continued rotation of the driver 110 will cause the driving portion 112 to engage with the head 202 of the fastener 200 in the opposite orientation, allowing the fastener to be rotated in the opposite anticlockwise direction.

Figures 10 and 11 show a further embodiment of a driver, generally indicated as 300. The driver 300 comprises a driving portion 302 in the form of a transverse blade member 304. The blade member 304 is tapered from its centre or innermost portion 306 to its ends 308, 310, so as to provide side faces 312a, 312b and 314a, 314b. Figure 12 shows the head 350 of a fastener 352 having a transverse recess 354. The recess is formed with side faces 356a, 356b and 358a and 358b to correspond with side faces 312a, 312b and 314a, 314b respectively of the blade member of the driver 300. Use of the driver 300 and fastener 352 simply requires that the blade member 304 is fully inserted into the recess 354. The sides faces 312a, 312b and 314a, 314b of the blade member 304 engage with side faces 356a, 356b and 358a and 358b respectively of the recess, providing for a large contact surface area between the driving portion 302 and the fastener head 350, in turn providing an improved transfer of torque from the driver 300 to the fastener 352.

Referring to Figures 13 and 14, there is shown a further embodiment of a driver, generally indicated as 400. The driver 400 comprises a shaft 402 having a blade member 404 mounted at one end. The blade member 404 extends laterally across the end of the shaft 402. The blade member 404 is provided with lateral tapers, such that the lateral ends 406 and 408 of the blade member are narrower than the innermost portion 410. The blade member 404 is further tapered in the longitudinal direction of the shaft 402, such that the blade member 404 is narrow adjacent the end of the shaft. The arrangement of tapers on the blade member 404 forms tapered side faces 412a, 412b, 414a and 414b, and tapered end faces 416a and 416b.

Referring to Figure 15 there is shown the head of a fastener, generally indicated as 430, for use with the driver 400 of Figures 13 and 14. The head 430 comprises a recess 432, extending transversely across the face of the head. The

opening of the recess 432 is of a tapered rectangular configuration, being narrower at its ends 434 and 436 and widest at its mid point 438. The recess 432 is also tapered internally, such that the innermost portion of the recess is wider than the opening, with undercut portions 440a to 44Od.

In use, the blade member 404 of the driver 400 is inserted into the recess 432 in the head 430 of the fastener and rotated to engage two diagonally opposing tapered side faces 412a, 414b or 412b, 414a, with the respective undercut portions 440c, 440b or 44Od, 440a of the recess, depending upon the direction of rotation. The tapered side faces of the blade member cooperate with the undercut portions of the recess to increase the engagement of the blade member with the head of the fastener, as the torque applied to the driver is increased.

Referring to Figures 16 and 17, there is shown a further embodiment of a driver, generally indicated as 500. The driver 500 comprises a shaft 502 having a driving portion 504 mounted at one end. The driving portion 504 is generally square in plan or end view, as shown in Figure 16. The driving portion 504 is tapered in the longitudinal direction of the shaft 502 on each side, such that the driving portion 504 is narrow adjacent the end of the shaft.

Referring to Figure 18 there is shown the head of a fastener, generally indicated as 530, for use with the driver 500 of Figures 16 and 17. The head 530 comprises a recess 532, located centrally within the face of the head. The opening of the recess 532 is square. The recess 532 is tapered internally, such that the innermost portion of the recess is wider than the opening, with undercut portions, indicated by dotted lines in Figure 18.

In use, the driving portion 504 of the driver 500 is inserted into the recess 532 in the head 530 of the fastener and rotated to engage opposing tapered side faces of the driving portion with the respective undercut portions of the recess, depending upon the direction of rotation. The tapered side faces of the blade member cooperate with the undercut portions of the recess to increase the engagement of the blade member with the head of the fastener, as the torque applied to the driver is increased.

Referring to Figures 19 and 20, there is shown a further embodiment of a driver, generally indicated as 600. The driver 600 comprises a cylindrical shaft 602 having a driving portion 604 mounted at one end. The driving portion 604 is generally triangular in plan or end view, as shown in Figure 19. The driving portion 604 is tapered in the longitudinal direction of the shaft 602 on each of its three sides, such that the driving portion 604 is narrow adjacent the end of the shaft.

Referring to Figure 21 there is shown the head of a fastener, generally indicated as 630, for use with the driver 600 of Figures 19 and 20. The head 630 comprises a recess 632, located centrally within the face of the head. The opening of the recess 632 is triangular, to match the driving portion 604 of the driver. The recess 632 is tapered internally, such that the innermost portion of the recess is wider than the opening, with undercut portions, indicated by dotted lines in Figure 21.

In use, the driving portion 604 of the driver 600 is inserted into the recess 632 in the head 630 of the fastener and rotated to engage opposing tapered side faces of the driving portion with the respective undercut portions of the recess, depending upon the direction of rotation. The tapered side faces of the blade member cooperate with the undercut portions of the recess to increase the engagement of the blade member with the head of the fastener, as the torque applied to the driver is increased.

Referring to Figures 22 and 23, there is shown a further embodiment of a driver, generally indicated as 700. The driver 700 comprises a cylindrical shaft 702 having a driving portion 704 mounted at one end. The driving portion 704 is generally cross-shaped in plan or end view, as shown in Figure 22, and comprises four orthogonal protrusions 706a, 706b, 706c and 706d. Each protrusion is tapered on its side surface, so as to have a triangular cross-section, with the base of the triangle being disposed furthest from the shaft 702. In addition, each protrusion has its end tapered, as shown in the figures. The end taper may be omitted, if desired.

Referring to Figure 24 there is shown the head of a fastener, generally indicated as 730, for use with the driver 700 of Figures 22 and 23. The head 730

comprises a recess 732, located centrally within the face of the head. The opening of the recess 732 is in the form of a cross, with four orthogonal recess portions 734a, 734b, 734c and 734d, to match the driving portion 704 of the driver. The recess 732 is tapered internally, such that the innermost portion of the recess and each recess portion is wider than the opening, with undercut portions, indicated by dotted lines in Figure 24.

In use, the driving portion 704 of the driver 700 is inserted into the recess 732 in the head 730 of the fastener and rotated to engage opposing tapered side faces of the protrusions 706a to 706d of the driving portion with the respective undercut recess portions 734a to 734d, depending upon the direction of rotation. The tapered side faces of the blade member cooperate with the undercut portions of the recess to increase the engagement of the blade member with the head of the fastener, as the torque applied to the driver is increased.

Referring to Figures 25 and 26, there is shown a further embodiment of a driver, generally indicated as 800. The driver 800 comprises a cylindrical shaft 802 having a driving portion 804 mounted at one end. The driving portion 804 is generally star-shaped in plan or end view, as shown in Figure 25, and comprises eight equally spaced protrusions 806a to 806h. Each protrusion is tapered on its side surface, so as to have a triangular cross-section, with the base of the triangle being disposed furthest from the shaft 802. In addition, each protrusion has its end tapered, as shown in the figures. The end taper may be omitted, if desired.

Referring to Figure 27 there is shown the head of a fastener, generally indicated as 830, for use with the driver 800 of Figures 25 and 26. The head 830 comprises a recess 832, located centrally within the face of the head. The opening of the recess 832 is in the form of a star-shape, with eight equally spaced recess portions 834a to 834h, to match the driving portion 804 of the driver. The recess 832 is tapered internally, such that the innermost portion of the recess and each recess portion is wider than the opening, with undercut portions, indicated by dotted lines in Figure 27.

In use, the driving portion 804 of the driver 800 is inserted into the recess 832 in the head 830 of the fastener and rotated to engage opposing tapered side faces of the protrusions 806a to 806h of the driving portion with the respective undercut recess portions 834a to 834h, depending upon the direction of rotation. The tapered side faces of the blade member cooperate with the undercut portions of the recess to increase the engagement of the blade member with the head of the fastener, as the torque applied to the driver is increased.

It is to be noted that the side faces of the various drivers shown in Figures 16 to 27 may be formed with lateral tapers, of the general type shown in the preceding figures, in particular Figures 4 and 5, and described hereinbefore. The provision of lateral tapers to the side faces will improve the engagement of the driver with the surfaces in the recess in the head of the respective fastener, again as hereinbefore described.

Referring to Figure 28 there is shown the head of a fastener, generally indicated as 902. The head 902 comprises a recess 904, located centrally within the face of the head. The opening of the recess 904 has a pair of parallel opposing end faces 906. The sides 908 of the recess each comprise two portions, 908a and 908b, extending from the ends of the end faces 906 to the central point of each side 908, such that the recess tapers from its centre line, where it is widest, to the narrower end faces 906. The recess 904 is tapered internally, such that the innermost portion of the recess greater in area, when viewed in plan as shown in Figure 28, than the opening. Accordingly, each of the sides 906, 908 of the recess is tapered in the longitudinal direction of the fastener 902 away from the opening 904 into the head of the fastener. This arrangement provides each side of the opening 904 with tapered undercut portions, indicated by dotted lines in Figure 28.

Figure 29 shows a plan view of an alternative to the fastener of Figure 29. The fastener 920 comprises a recess 922 having opposing, parallel end faces 924 extending perpendicular to the opening of the recess, that is without a taper, although end tapers may be added if desired. The sides of the recess 926 each comprise portions 926a and 926b extending from a respective end face 924 to the centre point of each side 926. The sides 926 comprise longitudinal tapers of similar form to those

of Figure 28. However, the side portions 926a and 926b of the sides 926 are tapered laterally in the opposite manner to those of Figure 28 such that the opening of the recess is narrower at its centre point than at the end faces 924, as shown in plan view in Figure 29. The internal tapers of the recess extending into the head of the fastener are indicated by dotted lines in Figure 29.

An alternative arrangement of the fastener of Figure 29 is shown in Figure 30. The general arrangement of the fastener of Figure 30 is as described above with reference to Figure 29, with the exception that the opening of the recess as viewed in plan view is rectangular and of constant width along the length of the opening.

The fastener of Figure 30b is substantially as described in Figure 30a, but with the inclusion of end tapers 928 extending from the ends of the opening 922, to provide the recess with tapers extending from each of the four sides of the opening into the head of the fastener. As described hereinbefore, the inclusion of the end tapers 928 allows a driver to occupy the entire opening and rotate within the recess, improving the engagement between the driver and the recess, in turn improving the transmission of torque from the driver to the fastener.

Figure 31 shows a further alternative embodiment of the fastener, generally indicated as 930. The fastener 930 comprises a recess 932 having a generally rectangular opening at the surface of the fastener head. Each of the end faces 934 and side faces 936 of the recess extend into the head of the fastener and taper outwards, as indicated by the dotted lines in Figure 31 , such that the area of the recess, when viewed in plan view as in Figure 31 , increases in the longitudinal direction of the fastener.

Turning to Figure 32, there is shown a plan view of the head of an alternative embodiment of fastener, generally indicated as 1002. The fastener has a recess 1004 extending into the head, having a generally rectangular opening 1006 at the surface of the fastener head. Each of the end faces 1008 and side faces 1010 of the recess extend into the head and taper outwards, as indicated by the dotted lines in Figure 32, such that the area of the recess when viewed in plan view increases in a direction extending into the fastener head. The recess 1004 has each of its corners

1012 extend longitudinally into the head of the fastener substantially perpendicular to the surface of the head and the opening. In this way, the regions of the head of the fastener at the corners of the recess that are unswept by a driver within the recess remain. This increases the amount of material present in the head of the fastener, increasing its resistance to deformation under high torque conditions. In addition, the formation of the recess with four perpendicular tapered walls, 1008 and 1010 is easier.

Finally, turning to Figure 33, there is shown a plan view of the head of a further alternative embodiment of a fastener. The fastener has a recess of the same generally configuration as that of Figure 32. However, each of the tapered surfaces of the recess, 1008 and 1010, are provided with lateral taper portions 1008a, 1008b, 1010a and 1010b, extending across the taper, as indicated by further dotted lines in Figure 33.