AU2007100117A4

AU2007100117A4 - Security screw

Info

Publication number: AU2007100117A4
Application number: AU2007100117A
Authority: AU
Inventors: Francis Bernard Tovenati
Original assignee: ITW Australia Pty Ltd
Current assignee: ITW Australia Pty Ltd
Priority date: 2007-02-14
Filing date: 2007-02-14
Publication date: 2007-03-15
Anticipated expiration: 2015-02-14
Also published as: NZ565823A

Description

C4

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT Name of Applicant: Actual Inventor: Address for Service: Invention Title: ITW Australia Pty Ltd of 3 Chester Street, Oakleigh, Victoria 3166, Australia Francis Bernard Tovenati DAVIES COLLISON CAVE, Patent Attorneys, of 1 Nicholson Street, Melbourne, Victoria 3000, Australia "Security screw" The following statement is a full description of this invention, including the best method of performing it known to us: Q:\OPER\RSH\JAN 07 JUNE 07U0173594-44-INNOV.DOC 14/2/07 P OPERRSHOI73594-nov dc-3 2nL07 -1- SSECURITY SCREW The present invention relates to a screw having a head formation which requires use of a special driving tool particularly to release the screw.

Unauthorised access into a building can sometimes be obtained by the removal of roofing sheets or wall panels which have been fastened to the frame of the building by screwing.

SAlthough a variety of different screws are commonly used for the fixing of roof sheets or wall panels, most have a standard hexagonal head engageable by a hexagonal driver.

Hexagonal drivers are widely available and therefore it is comparatively straightforward for the fastening screws to be undone to permit removal of the roofing sheet or wall panel.

The present invention provides a screw which co-operates with a special driver to permit the screw to be applied and released only by use of that driver. Accordingly, by providing limited availability of the driver an increased degree of security can be obtained over that when conventional screws are used.

According to one aspect of the present invention there is provided a screw having a head of which a main body is cylindrical with a central post projecting axially outwardly from the main body, and driving segments formed within the outer end face of the main body and extending over part of the depth of the main body, each driving segment opening to the peripheral surface of the main body and having a base surface transverse to the axis of the screw, a first driving surface transverse to the base surface for driving engagement with a correspondingly shaped driving segment of a driver for installation of the screw, and a second driving surface transversely to the first to permit driving rotation of the screw in a direction to remove the screw by use of the same driver.

In a modification, the second driving surface can be omitted whereby the driver is not able to exert a removal torque on the screw head, whereby the screw is then unable to be removed without abnormal effort.

P.\OPER\RS O3')i73594-mno dcc-13OV2007 -2- SAccording to another aspect of the invention there is provided a driver having a driving end portion of complimentary form to that of the screw head, with driving segments configured to engage in the driving segments of the screw head and an axial recess into which fits the post of the screw head.

Advantageously the base surface of each driving segment in the screw head is substantially flat and is engaged by a flat end surface of the driving segments of the driver for transmission of axial loading from the driver to the screw head.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of a screw in accordance with an embodiment of the invention; and Figure 2 is a perspective view of a driver for use with the screw of Figure 1.

The screw in accordance with a preferred embodiment of the invention has a head having a main body 2 of generally cylindrical form with a central post 4 also of cylindrical form projecting axially from the upper or outer surface of the main body 2. The main body 2 is formed with a series of identical driving segments 6 uniformly spaced around the circumference. As shown there are four such segments although there may be greater than or less than four. Four segments, however, provide a configuration in which a driver (see Figure 2) is readily locatable on the head while providing driving surfaces of sufficient extent to ensure transmission of the driving forces without the driver slipping. Each segment 6 extends over a part of the depth of the main body 2 from its outer surface and opens onto the peripheral surface of the main body 2. The segment provides a main driving face 8 in the direction in which the screw is driven for insertion of the screw, and a secondary driving face 10 in the direction for removal of the screw. The two driving faces 8, 10 join at their inner ends and are at right angles one to the other. With the configuration shown, the main driving face 8 is longer than the secondary driving face The base 12 of the segment subtended between the driving faces 8, 10 is flat and extends in a plane perpendicular to the axis of the screw and these flat bases serve to carry the axial P \OPERRSI UOI73594-mnovdom-I13K2J2(X)7 -3load from the driver during insertion of the screw.

In the embodiment shown, the screw is configured as a self-drilling screw with a drilling portion 14 at the end of the shank and a thread 16 inwardly of the drilling portion. As shown, the drilling portion 14 is of a type designed for drilling into metal and the thread 16 is a self-tapping thread. It is however to be understood that the shank of the screw can have any required configuration appropriate to the intended use of the screw. For example, the screw can be a self-drilling wood screw of the type commonly referred to as a type 17 screw, a conventional wood screw, or a screw having a drilling end portion and shank as described in our patent no. 719725.

For roofing applications it is not practical for the head to be of a diameter sufficient to accept a standard neoprene sealing washer and in that case a separate neoprene washer bonded to an aluminium washer can be assembled to the screw if required.

The driver is shown in Figure 2 and has a driving end portion 20 which is complimentary to the design of the screw head. As such the driving end portion 20 has raised driving segments 22 of the same shape as those of the segments 6 formed within the screw head so as to fit into those segments, with primary and secondary driving faces 24, 26 to engage those in the screw head. The axial depth of the driving faces 24, 26 being substantially the same as those in the screw head and when the driver is engaged with the screw head the axial outer end faces 28 of the driving segments 22 will bear against the bases 12 of the segments 6 in the screw head for transmission of axial load. The driving end portion also includes a circular passage 30 to receive the central post 4 at the end of the screw head. The central post 4 and its engagement within the passage 30 in the driver is of significance as it tends to prevent the screw head from breaking away from the driver as may otherwise occur if the screw and driver are not both perpendicular to the sheeting or other product being installed. At its opposite end, the driver is configured for engagement within the chuck of a drill or for coupling with another form of driving tool.

The design of the screw head while being effective in terms of its ability to be driven by ~J I.

P NOPERkRSIHUO I] 7394-nno doc. I 3A)22007 -4the driver while resisting breakaway between the driver and head during driving is also such that it is able easily to be made by conventional metal pressing/stamping techniques.

A principal application of the screw is in the fastening of sheeting, particularly, but not exclusively, roof sheeting, in buildings which require an improved degree of security to prevent unauthorised entry by removal of that sheeting to achieve access. As the screw requires the purpose-designed driver for its installation and removal, it is envisaged that the driver itself will be produced in limited numbers and supplied on a controlled and restricted basis.

Although the screw head as particularly described is designed so as to permit removal of the screw by use of the driver, an alternative version of the screw head can be produced with slight modification so that the secondary driving face of each segment is removed with that face of the segment then being ramped or chamfered so that the driver is not able to exert a removal torque on the screw head. It is envisaged that this alternative version would be supplied in conjunction with screws as previously described, to give a choice between the use of screws which are able to be removed by means of the special driver or screws which are unable to be removed without abnormal effort.

The embodiment has been described by way of example only and modifications are possible within the scope of the invention.

Claims

1. A screw having a head of which a main body is cylindrical with a central post projecting axially outwardly from the main body, and driving segments formed within the outer end face of the main body and extending over part of the depth of the main body, each driving segment opening to the peripheral surface of the main body and having a base surface transverse to the axis of the screw, a first driving surface transverse to the base surface for driving engagement with a correspondingly shaped driving segment of a driver for installation of the screw, and a second driving surface transversely to the first to permit driving rotation of the screw in a direction to remove the screw by use of the same driver.

2. A screw according to claim 1, wherein the base surface of each driving segment is substantially flat and at right angles to the axis of the screw and provides a surface by which axial load is transmitted from the driver to the screw.

3. A screw according to claim 1 or claim 2 modified in that the second driving surfaces are omitted to prevent its driving rotation by use of the driver.

4. A screw having a head substantially as hereinbefore described with reference to the drawings. A driver having a driving end portion of complimentary form to that of a screw head according to any one of the preceding claims, the driving end portion having driving segments configured to engage in the driving segments of the screw head and an axial recess into which fits the post of the screw head.