AU2003204517B2

AU2003204517B2 - Screws

Info

Publication number: AU2003204517B2
Application number: AU2003204517A
Authority: AU
Inventors: Francis Bernard Tovenati
Original assignee: ITW AFC Pty Ltd
Current assignee: ITW AFC Pty Ltd
Priority date: 2002-07-18
Filing date: 2003-06-03
Publication date: 2010-03-04
Anticipated expiration: 2023-06-03
Also published as: AU2003204517A1

Description

ITW AFC Pty Ltd AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION for the invention entitled: "Screws" The invention is described in the following statement: Q:\OPER\RSHVANUARY 03 - JUNE 03\12238460-CAP-154.DOC -3/6/03 C:\NRPortbMDCC\PLB\2669696 DOC-3II20 10 -1 SCREWS The present invention relates to screws and more particularly to screws for use in assembling metal frame sections for use in building construction. 5 When assembling together metal frame sections for use in building construction, holes may be pre-punched into a frame section to receive a fastening screw by which that frame section is secured to an adjacent frame section similarly pre-punched to receive the screw in threaded engagement therewith. Although, typically, the hole is formed within the 10 central part of a recessed or dimpled zone formed when punching the hole and in which part of the head of the screw can sit, existing screws for this purpose have a head profile with a peripheral edge of substantial depth which tends to project above the surface of the frame section. This projecting peripheral edge of substantial depth has a tendency to catch on other components such as other frame sections in a factory situation where trusses and 15 other frames are pre-assembled. In situations where the surface of the frame section from which the head of the screws project is itself intended to carry cladding material such as plasterboard sheeting, the projecting edges of the heads do tend to impede easy application of the sheeting as the heads can prevent sliding of the sheeting across the surface of the frame section during application. 20 According to the present invention there is provided an assembly having a first metal section secured to a second metal section by a screw having a head and a threaded shank, wherein the first metal section has a dimpled zone with a hole which receives the screw shank in threaded engagement therewith, the head of the screw having an undersurface 25 comprising a lower face extending radially outwardly with respect to the threaded shank of the screw, and a peripheral edge surface which diverges outwardly from the lower face such that the peripheral edge surface sits within the dimpled zone such that the head of the screw does not present a profile causing a substantial impediment to sliding movement across the surface of the first metal section. 30 Advantageously the profile of the undersurface of the head corresponds to the profile of the dimpled zone. An embodiment of the invention will now be described by way of example with reference C:\NRPorbl\DCCPLB\266%%_ L DOC.3IM1/2010 -2 to the accompanying drawings in which: Figure 1 is a side view of a screw in accordance with the preferred embodiment of the invention; 5 Figure 2 is a perspective view of the screw from above; Figure 3 is a perspective view of the screw from below; and Figure 4 shows the manner in which the screw is used to secure together two metal frame sections by driving into holes pre-formed in the sections. 10 As shown in the accompanying drawings a screw in accordance with the invention comprises a threaded shank 2, the thread preferably being a buttress thread which provides improved resistance to pull-out when used with relatively thin metal sections. The undersurface of the head 4 of the screw has a substantially planar bottom face 6 radially outwardly of the shank 2 and a peripheral edge surface 8 which diverges upwardly and 15 outwardly from the face 6. It will be seen that the thread terminates adjacent the bottom face 6 of the head 4 to thereby permit threaded engagement within a hole in a dimpled zone in a metal section as will be described with reference to Figure 4. The upwardly divergent peripheral edge surface 8 leads via an edge 9 into a slightly domed upper surface 10. A socket 12 for receiving a suitable driver such as an Allen key is formed in the 20 central part of the head 4. Figure 4 shows the screw when used to secure together two metal frame sections 14,16 each pre-punched with a hole to receive the screw in the threaded engagement therewith. As shown, each hole is formed within the central part of a dimple formed during punching 25 of the hole and consisting of a recessed land 20 of substantially circular shape with an inclined peripheral surface 22 extending between the land 20 and the outer surface of the section. The planar bottom face 6 of the head 4 lies against or closely adjacent to, the recessed land 20 of the dimple and the inclination of the inclined peripheral surface 22 of the dimple substantially matches that of the peripheral edge surface 8 so that the surface 8 30 is able to sit within the dimple. As a result of this configuration, the head 4 of the screw Lr:tK HV 3,,12fl -sp.c4.AWj -3 does not present substantial projecting edge to form an impediment to sliding of another metal section, plasterboard sheet, or other article across the surface of the section. More particularly, the edge 9 which lies at the transition between the undersurface and the upper surface of the head 4, lies substantially at the level of the surface of the metal section such 5 that it is substantially only the domed upper surface which projects beyond the surface of the metal section and this domed upper surface will not tend to impede sliding movement either of the metal section or other components along the surface of the section. Advantageously, the peripheral edge surface 8 of the head is provided with ribs 8a to 10 provide torque robbing on assembly by providing increased resistance to rotation of the screw. The embodiment has been described by way of example only and modifications are possible within the scope of the invention.

Claims

1. An assembly having a first metal section secured to a second metal section by a 5 screw having a head and a threaded shank, wherein the first metal section has a dimpled zone with a hole which receives the screw shank in threaded engagement therewith, the head of the screw having an undersurface comprising a lower face extending radially outwardly with respect to the threaded shank of the screw, and a peripheral edge surface which diverges outwardly from the lower face such that the peripheral edge surface sits 10 within the dimpled zone such that the head of the screw does not present a profile causing a substantial impediment to sliding movement across the surface of the first metal section.

2. An assembly according to claim 1, wherein the lower face of the head is substantially planar extending substantially perpendicularly to the axis of the screw. 15

3. An assembly according to claim 1 or claim 2, wherein the thread is a buttress thread.

4. An assembly according to any one of claims I to 3, wherein the peripheral edge 20 surface of the head is provided with formations operative to provide increased resistance of the screw to provide a torque robbing effect.

5. An assembly according to any one of claims I to 4, wherein the undersurface of the head corresponds to the profile of the dimpled zone. 25

6. An assembly according to any one of claims 1 to 5, wherein the upper surface of the head is domed and a peripheral edge of the head forming a transition between the peripheral edge surface of the undersurface and the upper surface of the head does not project beyond the surface of the first metal section. 30

7. An assembly according to any one of claims 1 to 6, wherein the assembly is a frame for use in building construction. C.\NRPonb\DCC\PLB2(6%%- I.DOC-13,01/2010 -5

8. An assembly substantially as hereinbefore described with reference to the accompanying drawings.